U.S. patent application number 14/610031 was filed with the patent office on 2015-11-05 for automatic prosthesis for above-knee amputees.
The applicant listed for this patent is Rizzoli Ortopedia S.P.A.. Invention is credited to Alessandro BALBONI, Leonardo BALLI, Denis Mattia DE MICHELI, Gabriele DONATI, Nicola FERRINI.
Application Number | 20150313728 14/610031 |
Document ID | / |
Family ID | 40445283 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150313728 |
Kind Code |
A1 |
BALBONI; Alessandro ; et
al. |
November 5, 2015 |
AUTOMATIC PROSTHESIS FOR ABOVE-KNEE AMPUTEES
Abstract
A above knee prosthesis (P) applied to femoral connection (100)
of an amputee that comprises a upper hinge (1) connected to femoral
connection (100) of the patient, an articulation axis (2) with the
function of reproducing the knee movements, a tibia-calf muscle
unit (3) pivotally connected to the femoral segment (1) and a
damper (5) that reproduces some functions of the calf muscle and
ensures to the prosthesis (P) to brake and to allow the sequential
swing and stance phases typical of the gait. The damper (5)
comprises a cylinder (5c) wherein a piston (10) and a stem (9) act
connected to each other and adapted to carry out a damping reaction
of said damper responsive to the forces loaded on the prosthesis.
In particular, a force transducer is provided in the damper (5)
arranged, in particular, in the stem (9) with a microprocessor that
receives a force signal from the transducer and operates means for
adjusting the reaction of the damper responsive to the detected
force signal. Exemplary embodiments are equipped with means for
adjusting the gait parameters during a gait cycle, means for
exploiting the energy dissipated by the prosthesis, means to assist
the charge and the change of batteries, means to know the direction
and/or the intensity of resultant forces transmitted through the
prosthesis.
Inventors: |
BALBONI; Alessandro;
(Granarolo dell'Emilia, IT) ; BALLI; Leonardo;
(Firenze, IT) ; DE MICHELI; Denis Mattia;
(Navacchio di Cascina, IT) ; DONATI; Gabriele;
(Pescia, IT) ; FERRINI; Nicola; (Terricciola,
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rizzoli Ortopedia S.P.A. |
Budrio |
|
IT |
|
|
Family ID: |
40445283 |
Appl. No.: |
14/610031 |
Filed: |
January 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12989092 |
Dec 8, 2010 |
8974543 |
|
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PCT/IB2008/001074 |
Apr 30, 2008 |
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14610031 |
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Current U.S.
Class: |
623/25 |
Current CPC
Class: |
A61F 2002/5006 20130101;
A61F 2002/764 20130101; A61F 2002/702 20130101; A61F 2/60 20130101;
A61F 2002/6818 20130101; A61F 2002/6642 20130101; A61F 2002/5033
20130101; A61F 2002/6621 20130101; A61F 2/72 20130101; A61F
2002/665 20130101; A61F 2/70 20130101; A61F 2002/607 20130101; A61F
2002/745 20130101; A61F 2002/7635 20130101; A61F 2/68 20130101;
A61F 2002/701 20130101; A61F 2002/704 20130101; A61F 2002/748
20130101; A61F 2002/768 20130101; A61F 2/6607 20130101; A61F
2002/608 20130101; A61F 2002/7625 20130101; A61F 2002/6836
20130101 |
International
Class: |
A61F 2/60 20060101
A61F002/60 |
Claims
1. A prosthesis for above-knee amputees, said prosthesis having a
femoral segment, which can be fixed to a femoral connection, and a
tibial segment pivotally connected to each other about an
articulation axis that reproduces the knee movements, said tibial
segment being articulated by an ankle to a foot having toes, a sole
of the foot and a heel, wherein said knee movements comprise a
swing phase, between bringing the toes off the ground and landing
the heel, and a stance phase, comprising landing the heel, loading
the sole of the foot and bringing the toes off the ground, a
hydraulic damper being provided having respectively a upper hinge
and a lower hinge connected respectively with said femoral segment
and said tibial segment and damping the relative movement of said
tibial segment with respect to said femoral segment, so that in the
stance phase the tibial segment is braked with respect to the knee
articulation between said femoral segment and said tibial segment,
wherein the hydraulic damper comprises a cylinder-piston and a stem
connected to said piston, and a microprocessor is provided for
adjusting the damping reaction of said damper wherein a force
transducer is provided in said stem, and the microprocessor
receives a force signal from said force transducer on the stem and
adjusts the damping reaction of said damper responsive to the force
signal from the stem.
2. Prosthesis, according to claim 1, characterised in that said
force transducer is provided in said stem, and the microprocessor
receives a force signal from said transducer on the stem and
adjusts the damping reaction of said damper responsive to the
detected force signal on the stem.
3. Prosthesis, according to claim 1, characterised in that said
force transducer is a ring dynamometer put in a hole made in said
stem, with axis of the hole orthogonal to the axis of the stem.
4. Prosthesis, according to claim 1, characterised in that said
force transducer on the damper is a load cell arranged at said
lower hinge of said damper.
5. Prosthesis, according to claim 1, wherein a force transducer is
provided in said femoral segment, selected from the group comprised
of: an orthogonal force transducer, a longitudinal force
transducer, a torque transducer, or a combination thereof, and said
microprocessor receives a force signal from said force transducer
in the femoral segment and adjusts the reaction of said damper
responsive to the force signal present on said femoral segment.
6. Prosthesis, according to claim 1, wherein a further force
transducer is arranged to detect a situation of singularity in
flexion by measuring the presence of overloads in bending.
7. Prosthesis, according to claim 5, wherein a memory unit is
provided for memorizing the force data of said force transducers,
and means for comparing them with maximum admissible values.
8. Prosthesis, according to claim 1, wherein a position transducer
is provided at the articulation axis that reproduces the knee
movements, said position transducer measuring the rotation of the
knee.
9. Prosthesis, according to claim 1, wherein said femoral segment
and said tibial segment are geometrically conformed in order to be,
at the beginning of a gait cycle at the end of the swing, in a
condition of singularity measured by a mechanical abutment
integrated in the damper, said force transducer on the damper
measuring the actual load transmitted to the articulation also in
the condition of singularity and the microprocessor that computes
the measure can discriminate and control this step during the
gait.
10. Prosthesis, according to claim 1, wherein said damper is of
hydraulic type and comprises blades arranged as check valve blade
springs for opening an oil flow responsive to a speed of the stem
in the cylinder.
11. Prosthesis, according to claim 1, wherein said damper is of
hydraulic type and comprises: a first chamber (A) and a second
chamber (B), separated by said piston; a compensation chamber; a
channel (E_1) extending from chamber B to compensation chamber,
between which a check valve (VN_1) without pre-charge and an
adjustment valve remote are arranged; a channel (E_2) extending
from compensation chamber to chamber (A), between which a check
valve (VN_2) without pre-load is arranged; a channel (C_1)
extending from chamber (A) to compensation chamber, between which a
check valve (VN_3) without pre-charge and an adjustment valve
remote are arranged; a channel (C_2) extending from compensation
chamber to chamber (B), between which a check valve (VN_4) is
arranged; a channel that connects a chamber of an oil sealing
chamber to chamber and is used to avoid pressure peaks in the oil
sealing chamber as well as it can be used as compensation chamber
and air emptying chamber in a phase of filling damper.
12. Prosthesis, according to claim 1, wherein said prosthesis has
the characteristic of being equipped, at the foot, with an insole
having an array of force and position transducers whose signals are
computed by said microprocessor for determining the mode of
interaction of the foot of the patient with the surroundings, where
the transducers located at the insole allow to determine a data
selected from the group comprised of: a resultant load vector on
said prosthesis, in its intensity, direction and position
components, whereby said microprocessor can adjust most favourably
the reaction of the damper; the point of application of the
resultant load vector, wherein one or more force transducers
located in the artificial limb whose signals, computed with the
signal generated by said insole, allow the microprocessor to
determine a transmitted resultant load vector.
13. Prosthesis, according to claim 12, wherein said artificial limb
comprises a further transducer of the angular position located at
the ankle and adapted to control the relative inclination between
tibia and foot, said microprocessor receiving signals from said
transducer of the angular position located at the ankle for
determining, in association to the data on the force vector
provided by the insole, the position of the ankle responsive to the
vector force.
14. Prosthesis, according to claim 1, wherein said knee
articulation axis comprises a generator/motor capable of providing
energy in some phases of the gait cycle and of receiving energy
during other phases, an energy storage unit being provided adapted
to accumulate and to release again said energy through said motor
controlled by said microprocessor during the phases of the gait
cycle.
15. Prosthesis, according to claim 14, wherein force and position
transducers are provided arranged according to said knee
articulation, in said microprocessor program means being provided
that operate responsive to signals coming from said force and
position transducers arranged according to said knee articulation,
said microprocessor supplying signals to said motor/generator for
working respectively as motor during a leg realignment phase and as
generator during a support phase.
16. Prosthesis, according to claim 15, wherein said microprocessor
directs to said energy storage unit the energy dissipated by the
knee from said motor/generator with function of generator and
recalls energy from said energy accumulator with a variable delay
addressing it to said motor/generator with function of motor as
propulsion when accelerating the tibia to ensure realignment with
the femur.
17. Prosthesis, according to claim 14, where in said damper
variable pitch springs are provided that allow to have low
stiffness for small angular travel between the femoral segment and
the tibial segment, and high stiffness for large angular
travel.
18. Prosthesis, according to claim 14, wherein said ankle
articulation between said tibial segment and said foot comprises a
further motor/generator.
19. Prosthesis, according to claim 18, wherein said ankle
articulation comprises a damping element arranged in parallel to
said motor/generator.
20. Prosthesis, according to claim 18, wherein said ankle
articulation comprises furthermore, force and angular position
transducers connected to said microprocessor responsive to signals
coming from said force and angular position transducers arranged in
the ankle, sending to said energy storage unit the energy generated
by the ankle during the step of support of the heel onto the
ground, and recalling energy from said accumulator with a variable
delay addressing it to said motor/generator on the ankle as power
necessary to lift the foot, acting as motor, allowing a much easier
and natural gait avoiding possible foot-ground impacts.
21. Prosthesis, according to claim 18, wherein said microprocessor
administers said motors/generators of the knee-ankle with program
means adapted to recognize the phase of the gait owing to the
signals coming from said force and position transducers arranged at
said knee and ankle articulations.
22. Prosthesis, according to claim 18, wherein said motor/generator
on the knee and said further motor/generator on the ankle share a
same energy storage unit.
23. Prosthesis, according to claim 22, wherein said motor/generator
devices associated to the joints of the knee and of the ankle and
the energy accumulator are fluidic devices.
24. Prosthesis, according to claim 1, wherein means are provided
adapted to adjust the pace of the gait in a same gait cycle, said
means providing functions at least of the following variables:
time, relative rotation angle between tibia and femur; or, in
equivalence, relative rotation angle between tibia and femur, and
first derivative with respect to time for said angle; means being
provided for measuring the variation of said angle and of said
first derivative or speed in a gait cycle and means for causing the
tibia to follow a function corresponding to that phase of the gait
cycle characterized by predetermined values of the angle and of the
speed.
25. A prosthesis for above-knee amputees, said prosthesis having a
femoral segment, which can be fixed to a femoral connection, and a
tibial segment, pivotally connected to each other about an
articulation axis that reproduces the knee movements, said tibial
segment being articulated by an ankle to a foot having toes, a sole
of the foot and a heel, wherein said knee movements comprise a
phase so-called swing, between bringing the toes off the ground and
landing the heel, and a phase so-called stance, comprising landing
the heel, loading the sole of the foot and bringing the toes off
the ground; a motor/generator, the motor being supplied by a
current whose intensity is adjusted by a microprocessor to obtain a
desired torque at the articulation axis so that in the stance phase
the tibial segment is braked about said articulation axis, said
microprocessor changing the damping reaction of said damper of said
gear motor according to a predetermined force-position function,
wherein means are provided adapted to adjust the pace of the gait
in a same gait cycle, said means providing functions at least of
the following variables: time, relative rotation angle between
tibia and femur; or, in equivalence, relative rotation angle
between tibia and femur, and first derivative with respect to time
for said angle; means being provided for measuring the variation of
said angle and of said first derivative, or speed, in a gait cycle
and means for causing the tibia to follow a function corresponding
to that phase of the gait cycle characterized by predetermined
values of the angle and of the speed.
26. Prosthesis, according to claim 25, wherein said means adapted
to adjust the pace of the gait in a same gait cycle comprises
closed curves, said microprocessor memorizing a plurality of gait
modes, each mode being described by a family of said closed curves
having similar shape and having different amplitude responsive to
an average walking speed.
27. Prosthesis, according to claim 25, wherein said space comprises
further coordinates selected from the group comprised of: algebraic
value of the resultant load vector acting on the limb and
transmitted to the ground; algebraic value of the moment of said
resultant vector with respect to the axis of rotation of the
articulation; moment transmitted by the femur to the articulation.
longitudinal force on the femur; orthogonal force on the femur;
second derivative of said angle of rotation, or combination
thereof.
28. Prosthesis, according to claim 25, wherein said space comprises
also the longitudinal force acting on the damper.
29. Prosthesis, according to claim 25, wherein said means adapted
to adjust the pace of the gait in a same gait cycle provides also
functions at least of the following variables: relative rotation
angle between tibia and foot; first derivative with respect to time
for said angle set between tibia and foot; means being provided for
measuring changes of said first derivative, or speed, in a gait
cycle and means for causing the foot to follow a function
corresponding to that phase of the gait cycle and having that
speed, in order to cause the prosthesis to reproduce the features
of that function.
30. Prosthesis, according to claim 25 wherein transducer means are
provided adapted to measure, continuously with respect to time, or
at discrete time intervals, said parameters that represent the
coordinates of said space, and to memorize said parameters with
respect to time, said microprocessor comprising means adapted to
analyse the data determined by the transducers, comparing them with
the data recorded in said memory unit, for determining, among the
recorded data, the curve that is most suitable for representing the
actual gait, called ideal curve.
31. Prosthesis, according to claim 30, wherein said microprocessor
adjusts the reaction of the damper and/or of the motor for
minimizing errors, said errors consisting of deviations, in said
n-dimensional space, between an actual point, whose coordinates are
the measurements made by the transducers, and a corresponding point
of the ideal curve.
32. Prosthesis, according to claim 29, wherein said microprocessor
adjusts the reaction of the damper according to variations of
moment and/or force orthogonally to the femur within a gait
cycle.
33. Prosthesis, according to claim 25 wherein program means are
provided residing in said microprocessor adapted to measure the
duration of support of the foot to ground during the gait, and for
associating a parameter of confidence to each different support
duration, to each parameter of confidence corresponding a measured
damping stiffness imparted by said microprocessor to said damper,
wherein said means for measuring the duration of support of the
foot to ground during the gait measure the duration of an event
double pitch cause the speed of the gait and the time for load of
the limb amputed, comparing them with data recorded relative to the
time for load of a missing limb, and allowing a flexion to the knee
tanto higher what lower is the deviation between the time for load
determined and the time for load of a missing limb.
34. Prosthesis, according to claim 1, wherein a reduction gear is
provided having a fast shaft connected to an electric motor and a
slow shaft connected to the knee articulation, the motor being
supplied by a current whose intensity is adjusted by said
microprocessor to obtain a desired torque at the articulation
axis.
35. A prosthesis for above-knee amputees, said prosthesis having a
femoral segment, which can be fixed to a femoral connection, and a
tibial segment pivotally connected to each other about an
articulation axis that reproduces the knee movements, said tibial
segment being articulated by an ankle to a foot having toes, a sole
of the foot and a heel, wherein said knee movements comprise a
phase so-called swing, between bringing the toes off the ground and
landing the heel, and a phase so-called stance, comprising landing
the heel, loading the sole of the foot and bringing the toes off
the ground, a reduction gear being provided having a fast shaft
connected to an electric motor and a slow shaft connected to said
articulation axis of the knee, the motor being supplied by a
current whose intensity is adjusted by a microprocessor to obtain a
desired torque at the articulation axis so that in the stance phase
the tibial segment is braked about said articulation axis, said
microprocessor changing the damping reaction of said damper of said
gear motor according to a predetermined force-position
function.
36. Prosthesis, according to claim 35, wherein a second gear motor
is provided connected to the ankle articulation having a fast shaft
connected to an electric motor and a slow shaft connected to the
ankle articulation, the motor being supplied by a current whose
intensity is adjusted by said microprocessor to obtain a desired
torque at the articulation axis.
37. Prosthesis, according to claim 35 wherein said or each gear
motor acts also as generator.
38. Prosthesis, according to claim 35 wherein said fast shaft and
said slow shaft connected to said articulation are orthogonal to
each other, to achieve a reduced encumbrance as far as possible
similar to the anatomic sizes.
39. Prosthesis, according to claim 38, wherein said gear motor has
a gear ratio between said fast shaft and said slow shaft that is
higher or equal to five, on said fast shaft a first position
transducer being mounted to determine the instant position of said
fast shaft; on said slow shaft a second position transducer being
mounted , said motor piloting said fast shaft in order to maintain
a predetermined play with said slow shaft and to allow the
reversibility of the motion.
40. Prosthesis, according to claim 35 wherein between said
reduction gear, located at said knee articulation, and said
articulation a freewheel is located adapted to free the tibia from
the reduction gear during the swing phase, i.e. when the inertia of
the leg is active, vice-versa the freewheel constrains the two
movements to each other when the motor/brake has to act on the
tibia.
41. Prosthesis, according to claim 40 where in flexion phase said
microprocessor operates said motor in order to brake the movement
of the tibia ensured by said freewheel when in a meshed position,
whereas during the extension phase said microprocessor operates or
does not operate said motor causing said freewheel to mesh or not
to mesh.
42. Prosthesis, according to claim 35 wherein said shafts of the
reduction gear provide two angular transducers adapted to measure
the angular position of said shafts, wherein said reduction gear
has backward efficiency less than a forward efficiency, said
microprocessor computing the data produced by said transducers and
operating the motor to limit the dissipation in the reduction gear
of the kinetic energy of the leg recovering suitably play occurring
in the kinematical chain.
43. Prosthesis, according to claim 35wherein said shafts of the
reduction gear provide one or more moment transducers.
44. Prosthesis, according to claim 1 wherein a rechargeable battery
is provided, and means for releasably engaging with said
rechargeable battery, said battery feeding electronic devices that
are arranged in said prosthesis.
45. Prosthesis, according to claim 44, wherein said battery is
connected to said prosthesis in a front position with respect to
the articulation axis and is accessible from the above by the
patient who is in a sitting position, in a way congruent with the
geometry of the limb, allowing the sitting patient to extract
/position it.
46. Prosthesis, according to claim 45, wherein a port is provided
arranged to connect said artificial limb to a computer for
recharging said battery that feeds the electronic devices that are
arranged in said artificial limb, updating the firmware,
transferring, for a deferred analysis, the data recorded by the
artificial limb to the computer.
47. Prosthesis, according to claim 46, wherein said rechargeable
battery comprises a recharging circuit connectable with a supply
circuit external to the limb by a primary/secondary connection of a
transformer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of orthopaedic
appliances and more precisely it relates to an automatic prosthesis
for above-knee amputees.
[0002] Furthermore, the invention relates to an electronic
apparatus capable to control this prosthesis.
DESCRIPTION OF THE TECHNICAL PROBLEM
[0003] Various types are known of prostheses for above-knee
amputees. In many of these types a configuration is provided with a
femoral segment and a tibial segment pivotally connected to each
other about an articulation axis that reproduces the knee
movements. Furthermore, a hydraulic damper is provided that
connects the femoral segment with the tibial segment. An example of
these prostheses is disclosed in JP52047638, GB826314, U.S. Pat.
No. 4,212,087, U.S. Pat. No. 3,599,245.
[0004] The tibial segment is articulated by an ankle to a foot
having toes, a sole of the foot and a heel, and the knee movements
can be divided into a phase so-called swing, between bringing the
toes off the ground and landing the heel, and a phase so-called
stance, comprising landing the heel, loading the sole of the foot
and bringing the toes off the ground. By damping the relative
movement of the femoral segment with the tibial segment, in the
stance phase the tibial segment is braked with respect to the
connection hinge between the femoral segment and the tibial
segment.
[0005] In some cases, like in GB2216426, a valve with adjustable
choking changes the braking action of the damper in the various
steps of flexion and extension of the knee, with the adjustable
valve controlled by a program and a microprocessor. GB2244006
provides also a choking cross-section through which passes the
fluid of the damper. The fluid is of electrorheological type, so
that when influenced by an electric field it causes the damping
rate to change. A force transducer transmits data on the force
acting on the leg and the microprocessor adjusts therefore the
viscosity of the hydraulic damper.
[0006] Concerning the articulation axis, it can be a simple hinge,
like in the above described documents, or a motor or an
electromagnetic brake, like in FR2623086. The choice of the phases
in which the articulation is braked or left free or, in particular,
accelerated, is obtained by force transducers arranged on the
tibial segment, which allows to operate the motor or the brake.
Furthermore, always
[0007] FR2623086 teaches to recover energy using the energy
dissipated by a hydraulic pumping operated by the foot of the
prosthesis, which operates a hydraulic motor located at the
articulation.
[0008] One of the many problems of the existing prostheses for
above-knee amputees is the risk for the toes to hit the ground
during the swing phase, so-called Toe Clearance. In particular at a
low speed of the gait, there is a minimum dynamic effect of the
femur that is traduce in a small lifting the prosthetic foot. The
stiffness of the foot same, does not assist the extension necessary
between femur and tibia during the swing phase generating the risk
for the toes to hit the ground during the swing phase.
[0009] Another problem, during walking on a plane ground in elder
patients or in patients that are recovering the gait after
above-knee amputation, is realigning the tibia with the femur. In
fact, once passed the TDC between the femoral segment and the
tibial segment, a difficulty arises to re-align the femoral segment
and the tibial segment owing to a minimum swinging action of the
tibial segment.
[0010] A further problem is the impossibility, in the existing
prostheses, to adjust the pace within a gait cycle. This need is
felt in situations where an unexpected obstacle is met, with need
of a speed variation for passing it, or the need of stopping
quickly the gait.
[0011] Yet another problem is the difficulty, for existing
prostheses, to adjust the parameters of the gait progressively as
the patient gets familiar with the prosthesis. Normally, it is
necessary to change prosthesis or to carry out mechanical
adjustments by technical experts.
[0012] Further problems are in the range of the prosthesis, which
needs of battery motors or electric actuators, where present, as
well as in the simplicity of the battery recharge phase.
SUMMARY OF THE INVENTION
[0013] It is an general object of the present invention to provide
a prosthesis for above-knee amputees that restores the gait ability
of the amputees in a way similar to that of a not disabled persons
improving the prior art technique and solving the above described
problems.
[0014] It is also a feature of the invention to provide an
artificial limb that reproduces all the features of a missing limb,
and, in particular, allows detecting data on the surroundings, and
on the relative position of the limb with respect to the
surrounding space.
[0015] It is another feature of the invention to provide an
artificial limb that allows also detection of data on the status of
the limb, in particular on the stress-strain to which the limb is
subject, allowing an analysis of the instant stiffness conditions
of the joints concerned with the prosthesis.
[0016] It is a further feature of the invention to provide an
artificial limb that has a better logical of control with respect
to the prior art, allowing to choose the operations to carry out to
ensure comfort and a safe gait.
[0017] It is also a feature of the invention to provide an
artificial limb that allows to supply/dissipate/recover energy
during the gait at the knee joint and/or at the ankle joint,
allowing in particular, to recover energy of first species (for
example mechanical work) acquired during the dissipative gait
phases and available to be used in the phases with a demand of
energy from the limb.
[0018] It is a further feature of the invention to provide an
artificial limb that allows to an above-knee amputee to perform a
natural gait, with reduced energy consumption by the patient, with
a reaction that is responsive to the pace, with adaptation to a
variety of types of route, to minimize a request for energy from
the prosthesis.
[0019] It is also a feature of the invention to provide an
artificial limb to assist a patient with a very limited gait
ability, i.e. elder people or patients with an unsecure gait.
[0020] Another feature of the invention is to provide an artificial
limb that ensures a dynamic damping, such that comfort and
steadiness are achieved during the gait avoiding unnatural
stiffening reactions.
[0021] It is also a feature of the invention to provide an
artificial limb that increases the safety for controlling the knee
to achieve a larger clearance in the so-called Toe-Clearance
phase.
[0022] A further feature of the invention is to provide an
artificial limb that is adapted, through the application of
suitable transducers, to determine the position of the load as the
vector force with respect to the ground.
[0023] It is also a feature of the invention to provide an
artificial limb that allows determining the point of application of
the force from the foot to the ground as well as its intensity.
[0024] One of the objects of the invention is also to provide an
artificial limb that allows perceiving and recognizing the position
of the prosthesis in space and, in particular, the position of the
foot with respect to the patient's body.
[0025] It is also a feature of the invention to provide an
artificial limb for changing the stiffness of the knee reaction as
well as it assists to avoid shocks, to recover the position of the
ankle in the presence of curbs, to ensure a highly safe gait but
also at avoid to the patient of have look continuously after the
surroundings.
[0026] It is another feature of the invention to provide an
artificial limb for changing pace of the gait within a gait
cycle.
[0027] It is another feature of the invention to provide an
artificial limb that increases the range of the prosthesis, by
means of batteries that can be easily charged and changed.
[0028] These and other features are accomplished with one exemplary
prosthesis for above-knee amputees, said prosthesis having a
femoral segment, which can be fixed to a femoral connection, and a
tibial segment pivotally connected to each other about an
articulation axis that reproduces the knee movements, said tibial
segment being articulated by an ankle to a foot having toes, a sole
of the foot and a heel, wherein said knee movements comprise a
phase so-called swing, between bringing the toes off the ground and
landing the heel, and a phase so-called stance, comprising landing
the heel, loading the sole of the foot and bringing the toes off
the ground, a hydraulic damper being provided having respectively a
upper hinge and a lower hinge connected respectively with said
femoral segment and said tibial segment and damping the relative
movement of said tibial segment with respect to said femoral
segment, so that in the stance phase the tibial segment is braked
with respect to the knee articulation between said femoral segment
and said tibial segment, wherein the hydraulic damper comprises a
cylinder-piston and a stem hinged to said piston, and
microprocessor means for adjusting the damping reaction of said
damper.
[0029] In a first particular aspect of the invention, the
prosthesis has a force transducer in said damper, and the
microprocessor receives a force signal from said force transducer
and operates the means for adjusting the reaction of said damper
responsive to the force signal from said damper.
[0030] In particular, said force transducer is arranged on said
stem. Preferably, said force transducer is a ring dynamometer, such
as a Morehouse ring, put in a hole made in said stem with axis of
the hole orthogonal to the axis of the stem.
[0031] Alternatively, said force transducer on the damper is a load
cell arranged at said lower hinge of said damper.
[0032] This way it is possible an instant verification of the
status of load on the damper and a feedback control on the dynamic
behaviour of the knee.
[0033] Advantageously, a further force transducer is provided in
said femoral segment, and said microprocessor receives a force
signal from said force transducer in the femoral segment operating
said means for adjusting the reaction of said damper responsive to
the detected force signal on said femoral segment.
[0034] In an advantageous exemplary embodiment, said force
transducer in said femoral segment comprises a first force
transducer adapted to measure the action on the femur according to
a direction longitudinal to the femur, and a second force
transducer adapted to measure the action on the femur in a
direction orthogonal to the femur. This way, the overall force
information on the femur and on the damper is capable of
determining satisfactorily the tensional status in the artificial
limb.
[0035] In an exemplary simplified embodiment, said second force
transducer on the femur provides only the sign of the force on the
femur in a direction orthogonal to the same.
[0036] Furthermore, a position transducer can be provided at the
articulation axis that reproduces the knee movements, said position
transducer measuring the rotation of the knee.
[0037] Advantageously, the femoral segment and the tibial segment
is located, at the beginning of a step at the end of the swing,
which is the phase of maximum extension of the movement, in a
condition of singularity measured by a mechanical abutment
integrated in the damper. This way, the force transducer on the
damper measures the actual load transmitted to the articulation
also in the condition of singularity, and the microprocessor that
computes the measure can discriminate and control this step during
the gait.
[0038] Advantageously, said condition of which is a condition of
maximum flexion of the articulation and that normally is not part
of the gait, is detected and determined by a special transducer, or
by said force transducer integrated in the damper if the abutment
is integrated in the damper same, so that the microprocessor can
measure the full history of the loads applied to the artificial
limb and, precisely, the occurrence of possible overloads that may
have jeopardized the soundness of the artificial limb same,
actuating, in this case, suitable signalling and emergency
means.
[0039] Advantageously the damper is of hydraulic type and is
characterised by blades adapted to control the oil outflow in the
presence of high loads, for example shocks, assuring a high comfort
to the patient.
[0040] Preferably, said damper is of hydraulic type and provides a
first chamber (A) and a second chamber (B), separated by said
piston, the following being also provided: [0041] a compensation
chamber; [0042] a first unidirectional duct from said compensation
chamber to said first chamber; [0043] a second unidirectional duct
from said first chamber (A) to the compensation chamber along which
an adjustable flow valve is located controlled by said
microprocessor; [0044] a third unidirectional duct from said
compensation chamber to said second chamber; [0045] a fourth duct
selected from the group comprised of: [0046] an unidirectional duct
from the second chamber to the compensation chamber along which an
adjustable flow valve is located controlled by said microprocessor;
[0047] an unidirectional axial duct in said stem between said
second chamber and said first chamber, said stem crossing said
second chamber and having a plurality of radial apertures in said
second chamber such that, with the movement of said stem in said
extension phase, such apertures are progressively obstructed in
order to provide higher resistance against the movement of said
piston.
[0048] In particular, a fifth duct is provided between said
compensation chamber and a oil sealing chamber on said stem, such
that the pressure in said oil sealing chamber is identical to the
compensation chamber, to avoid pressure peaks in the oil sealing
chamber.
[0049] In a second particular aspect of the invention said
prosthesis has the characteristic of being equipped, at the foot,
with an insole having an array of force and position transducers
whose signals are computed by said microprocessor for determining
the mode of interaction of the foot of the patient with the
surroundings.
[0050] In a possible embodiment of the insole the transducers
located at the insole allow to determine the resultant load vector,
in its intensity, direction and position components, whereby the
microprocessor can adjust most favourably the reaction of the
damper.
[0051] In another embodiment of the insole the transducers located
at the insole provides data on the point of application of the
resultant load vector, wherein one or more force transducers are
provided located in the artificial limb whose signals, computed
with the signal generated by said insole, allows the microprocessor
to determine the transmitted resultant load vector.
[0052] Advantageously, said artificial limb comprises a further
transducer of the angular position located at the ankle and adapted
to control the relative inclination between tibia and foot. This
information allows determining, in association to the data on the
force vector provided by the insole, the position of the ankle
responsive to the corresponding vector force, since necessarily the
load passes through the ankle.
[0053] In a third particular aspect of the invention, said knee
articulation axis comprises a generator/motor capable of providing
energy in some phases of the gait cycle and of receiving energy
during other phases, an energy storage unit being provided adapted
to accumulate and to release again said energy through said motor
operated by said microprocessor during the phases of the gait
cycle.
[0054] In particular, force and position transducers are provided
arranged at said knee articulation for driving the energy exchange
between said energy storage unit and said generator/motor, which is
therefore capable of supplying/dissipating/recovering energy. More
precisely, in the microprocessor program means are resident that
operate responsive to signals coming from said force and position
transducers arranged according to said knee articulation, and that
cause said motor/generator to work respectively as motor during a
leg realignment phase and as generator during a support phase.
[0055] This way, since a large part of the gait has the knee
dissipating the energy supplied by the femur in the femur-tibia
relative movement, like when walking on a plane ground, there is a
sensitive energy recovery by accumulating, as far as possible, the
energy dissipated and releasing it back as the articulation of the
leg moves when necessary. More precisely said microprocessor
reduces the swinging action of the tibial segment with braking
torque when landing with stabilising function. During these
moments, the energy dissipated by the knee is recovered by said
energy storage unit and is supplied with a variable delay in some
phases of the gait cycle, in particular, when accelerating the
tibia to ensure realignment with the femur. Other passive phases,
for example when mechanical work is applied to the artificial limb,
for example when sitting, have energy that is accumulated in
storage unit.
[0056] Then, using a brake/motor device on the knee articulation,
it is possible to ensure a correct arrangement of the femoral
segment with respect to the tibial segment in all the gait
conditions, in particular at low speed.
[0057] Advantageously, said motor acts assuring the correct
realignment of the tibia if the patient, in particular, a new
amputee or an elder person, has hesitations during the path.
[0058] Preferably, for reducing the energy consumption of the
prosthesis, and increasing the range of the motor/generator system,
variable pitch springs are provided that allow to achieve ideal
stiffness, i.e. low stiffness for small angular travel between the
femoral segment and the tibial segment, and high stiffness for
large angular travel.
[0059] In particular, said variable pitch springs are helical
springs having a diameter and a first pitch P.sub.1 at one end and
a second pitch P.sub.2 at the other end with a continuous
transition of the stiffness between a first value K.sub.1 and a
second value K.sub.2. Alternatively, the spring is characterized by
two portions having different pitch.
[0060] Advantageously, also said ankle articulation between said
tibial segment and said foot comprises a motor/generator, which can
be arranged in parallel to a resilient element and/or to a damping
element, to force and angular position transducers connected to the
microprocessor.
[0061] This way, also the ankle is adapted to brake the tibia-foot
relative rotation when the heel lands, acting as generator, and to
provide the power necessary to lift the foot, acting as motor.
[0062] Advantageously the motor/generator on the ankle is capable
to adjust the incidence of the foot with respect to the tibial
segment, allowing a much easier and natural way to avoid risks for
the toes to hit the ground during the swing phase (Toe
Clearance).
[0063] Owing to this feature, said prosthesis is good for amputees
with low gait ability, i.e. elder people or people that hesitate
during the gait, thus assisting the gait.
[0064] To avoid risk for the toes to hit the ground during the
swing phase the microprocessor administers the system consisting of
the motors/generators of the knee-ankle with program means adapted
to recognize the phase of the gait owing to the signals coming from
said force and position transducers arranged according to said
ankle articulation, and to determine the risk for the toes to hit
the ground during the swing phase, changing the angles of incidence
of the foot with respect to the tibial segment, avoiding such risk
for the toes to hit the ground during the swing phase. Thus, the
knee-ankle system is adaptive with respect to the evolution of the
gait of the patient assuring a better and safer performance.
[0065] Advantageously, the knee and the ankle share a same energy
storage unit; therefore when the motor/generator connected to the
knee must work as motor it can use the energy accumulated in the
energy storage unit, previously generated by the motor/generator
connected to the ankle in the phases where the latter has worked as
generator.
[0066] An application of this concept is to go up the stairs: the
foot rests a step, and the forward movement of the barycentre
produces a work on the ankle that can be accumulated, this energy
is then used as a contribution the knee for lifting the patient's
body. This way, the knee and the ankle are interfaced with each
other and exchange energy through said energy storage unit to
accomplish a total energy recovery (Total Recovery System).
[0067] Advantageously the motor/generator devices that are
associated to the joints of the knee and of the ankle and the
energy accumulator are fluidic devices.
[0068] In a fourth particular aspect of the invention, the
artificial limb comprises means adapted to adjust the pace of the
gait in a same gait cycle, said means providing functions at least
of the following variables: time, relative rotation angle between
tibia and femur, and first derivative with respect to time for said
angle.
[0069] In particular, said means adapted to adjust the pace of the
gait in a same gait cycle comprises closed curves. Walking on a
plane ground, for example, is defined by a family of similar curves
having different amplitude responsive to the average walking speed.
More precisely, said means adapted to adjust the pace of the gait
in a same gait cycle provides defining the curves in a
n-dimensional space adapted to describing a gait cycle, said curves
consisting of the trajectory of the tibia with respect to time
described by the angle tibia-femur and by its derivatives with
respect to time.
[0070] In case of walking on a plane ground each curve defines an
ideal gait cycle for a determined average speed, such that as the
average speed changes the curve changes its amplitude, but the
curve shape is substantially the same. Then a family of similar
curves, described in a plane or a multidimensional space,
identifies univocally walking on a plane ground and a parameter,
such as the average speed, discriminates the curves of the family
from one another.
[0071] Means are provided for measuring changes of the speed in a
gait cycle and means for causing the tibia to follow a
corresponding curve in that phase of the gait cycle. This way, it
is possible to recognize quickly the need of the amputee to change
the speed of the gait, and then to switch the tibia to follow a
curve of different amplitude with respect to the previously
followed curve without awaiting the beginning of the successive
cycle.
[0072] The typical operations of stopping from walking, sitting
down and standing up can be defined in turn by special families of
curves. Similarly, walking uphill, downhill, going down and up the
stairs, pedalling on a bicycle, skiing, and substantially any other
possible gait types, can be represented, in general, in a
n-dimensional space, by families of characteristic curves.
[0073] Each family of curves is characterized by one characteristic
shape and by parameters that label them to distinguish them with
respect to other curves.
[0074] In a possible configuration, exemplifying and not
limitative, in said space the coordinates are five: [0075] time;
[0076] relative rotation angle between tibia and femur; [0077]
first derivative with respect to time for said angle; [0078]
algebraic value of the resultant load vector transmitted to the
ground; [0079] algebraic value of the moment of said resultant
vector with respect to the axis of rotation of the
articulation.
[0080] It is possible to put further parameters, such as the second
derivative of the angle, for representing in a more complete and
generalized way the different possible gait conditions.
[0081] In a preferred simplified configuration the coordinates of
the space are three: tibia-femur rotation angle, first derivative
with respect to time for the tibia-femur rotation angle, force
acting on the damper.
[0082] Transducer means are further provided adapted to measure
continuously with respect to time, or at discrete time intervals,
the parameters that represent the coordinates of said space. In
particular, at least one memory unit is provided, such as a RAM,
ROM, EPROM etc. adapted to memorize the characteristic data of said
curves and to memorize the data determined by the transducers with
respect to time.
[0083] Furthermore, a microprocessor is provided adapted to analyse
the data determined by the transducers, comparing them with the
data recorded in said memory unit, for determining, among the
recorded data, the family of curves and the curve that is most
suitable for representing the actual gait, called ideal curve.
[0084] Said microprocessor adjusts the reaction of the damper for
minimizing errors, for example distance errors, in n-dimensional
space, between the actual point, whose coordinates are defined by
the measurements made by the transducers in the actual instant, and
the corresponding point of the ideal curve as well as force errors
under the angle an the derivative of the angle of the articulation
(knee or ankle).
[0085] Advantageously, said microprocessor ascertains, according to
the error, to the ideal curve used and to the family of curves, if
it is useful to continue on the actual ideal curve, or if it is
better to use a different ideal curve or to change family of
curves.
[0086] Advantageously, said architecture of control is adapted to
optimize the gait responsive to the evolution of the psychophysical
conditions of the patient, therefore the patient walks always at
best both just after the amputation, when hesitation for the gait
is high, and when the amputee has acquired more confidence. A
further advantage is that the time for rehabilitation is reduced,
since the patient is continuously assisted by a device that carries
out the function of electronic rehabilitating device suitable for
correcting and improving the gait.
[0087] A possible exemplary embodiment provides measuring the
moment of the femur at the articulation, and in this case, without
limiting the scope of the invention, the coordinates of said space
are the following: [0088] time; [0089] relative rotation angle
between tibia and femur; [0090] first derivative with respect to
time for said angle; [0091] longitudinal force acting on the
damper; [0092] moment transmitted by the femur to the
articulation.
[0093] The latter parameter allows detecting indirectly the wishes
of the patient because these are evidenced by the moment that the
stump produces on the articulation.
[0094] Without limiting the scope of the invention the need of
accelerating the gait on a plane ground causes a variation of
moment and/or force orthogonally to the femur, and a situation
similar occurs when the patient wishes to decelerate.
[0095] The control system, acquiring the values of these parameters
that are correlated to the need of the patient, is capable to
adjust the behaviour of the artificial limb to ensure a very quick
response to follow instantly the wishes of the patient. Said
control system is suitable especially for those patients that need
a high dynamism. In general it recovers, at least partially,
proprioception of the missing limb, since a direct relationship is
established between wishes of the patient, for example the pressure
of the stump on the prosthesis, action and perception.
[0096] Alternatively, said means for defining the gait conditions
are of matrix type.
[0097] In a fifth particular aspect of the invention, a reduction
gear is provided having a fast shaft connected to an electric motor
and a slow shaft connected to the knee articulation, the motor
being supplied by a current, whose intensity is adjusted by a
microprocessor to obtain a torque at the articulation axis similar
to that obtainable by a hydraulic damper.
[0098] Advantageously a second gear motor is provided connected to
the ankle articulation controlled by the microprocessor, in order
to obtain a torque similar to a hydraulic damper.
[0099] Advantageously said reduction gear, located at said knee
articulation, has a fast shaft connected to an electric motor and a
slow shaft connected to the articulation that are orthogonal to
each other, to achieve a reduced encumbrance as far as possible
similar to the anatomic sizes.
[0100] Advantageously the artificial limb provides a second gear
motor having orthogonal axes connected to the slow shaft at the
ankle articulation.
[0101] Preferably, said gear motor, in particular a worm drive, has
a gear ratio between said fast shaft and said slow shaft that is
higher or equal to 5, on said fast shaft a first position
transducer being mounted to determine the instant position of said
fast shaft; on said slow shaft a second position transducer being
mounted , said motor piloting said fast shaft in order to maintain
a predetermined play with said slow shaft and to allow the
reversibility of the motion.
[0102] Advantageously between said reduction gear, located at said
knee articulation, and said articulation a freewheel is located
adapted to free the tibia from the reduction gear during the swing
phase, i.e. caused by the inertia of the leg, vice-versa the
freewheel constrains the two movements to each other when the
motor/brake has to act on the tibia.
[0103] Alternatively to said freewheel, on said shafts of the
reduction gear two angular transducers are applied adapted to
measure the angular position of said shafts.
[0104] Since said reduction gear is characterised by backward
efficiency less than a forward efficiency, said microprocessor
computes the data produced by said transducers and operating the
motor for keeping the contact between the teeth of the gears
opposite to the transmission side of the retrograde torque, to
limit the dissipation in the reduction gear of the kinetic energy
of the leg; this may take place owing to the unavoidable backlash
present in the kinematical chain that, in this case, has a positive
role allowing to the microprocessor to operate the motor in order
not to brake, or to brake the least possible, the inertial energy
of the leg.
[0105] In an alternative exemplary embodiment, one or more moment
transducers are provided instead of the angular transducers; in
this case the microprocessor operating the motor managing the
amount of power that has to be dissipated on the gear motor and/or
has to be stored the accumulator.
[0106] In a sixth particular aspect of the invention, the
electronic devices that are arranged in the artificial limb, both
in the case of only the knee articulation and in the case of the
latter in combination with the ankle articulation, are fed by a
rechargeable battery, for example of the type with lithium ions,
replaceable quickly and autonomously by the same patient that can
wear the artificial limb when replacing the batteries.
[0107] A special device, for example an acoustic alarm, signals to
the patient when the battery on the artificial limb is going to be
flat, and the patient can easily replace it with a second battery
that has been brought with; this way, the range of the prosthesis
is longer.
[0108] The number of charged batteries that the patient carries
with can be naturally larger than two, and this is advantageous for
patients who like trekking, or who are accommodated, even
occasionally, where electricity is not easily available, or to
avoid long waits for one battery to be recharged.
[0109] Alternatively, on the artificial limb a USB port is present,
in an exemplifying and not limitative way, by means of which the
artificial limb can be connected, both in the case of only the knee
articulation and in the case of the latter in combination with the
ankle articulation, to a computer for recharging the battery that
feeds the electronic devices that are arranged in said artificial
limb, updating the firmware, transferring, for a deferred analysis,
the data recorded by the artificial limb to the computer.
[0110] Advantageously special software installed on the computer or
available in the network analyse the data stored in the memory of
the artificial limb and program again the firmware for improving
the behaviour of the artificial limb responsive to the wishes of
the patient.
[0111] Advantageously, in combination or alternatively, with the
previous features, on the artificial limb, both in the case of only
the knee articulation or in case of a combination of the latter
with the ankle articulation, the devices are fed by a rechargeable
battery, for example of the type with lithium ions, whose
recharging circuit may be connected to the supply circuit external
to the limb by a primary/secondary connection of a transformer.
[0112] This way, the patient can easily recharge the battery while
wearing the artificial limb, the aesthetic coating and the
clothes.
[0113] Advantageously the outer recharging circuit is fed in turn
by a battery of larger size, which the patient can wear, for
example fastened to the waistbelt, in a backpack, in a pocket
etc.
BRIEF DESCRIPTION OF THE DRAWINGS
[0114] The invention will be made clearer with the following
description of an exemplary embodiment thereof, exemplifying but
not limitative, with reference to the attached drawings
wherein:
[0115] FIG. 1 shows a diagrammatical kinematical view of an above
knee prosthesis of prior art;
[0116] FIG. 2 shows a first cross sectional view of a preferred
embodiment of an above knee prosthesis in two functional gait
configurations;
[0117] FIG. 3 shows a second cross sectional view of a preferred
embodiment of an above knee prosthesis in two functional gait
configurations;
[0118] FIG. 4 shows a cross sectional enlarged view of a part of
the above knee prosthesis of FIGS. 2 and 3 with piston completely
withdrawn;
[0119] FIG. 5 shows the above knee prosthesis in a cross sectional
view showing constraint means that connect the damper in the
tibia-calf muscle unit;
[0120] FIG. 6 shows a first hydraulic diagram of a damper
operation, according to the invention;
[0121] FIG. 6A shows a second hydraulic diagram of a damper
operation, according to the invention;
[0122] FIG. 7 shows a front view of the cylinder of the damper
unit, with control unit and servomotors mounted on respective valve
groups;
[0123] FIG. 8 shows a cross sectional view of the valve unit
integral to the damper with a respective servo-motor (not cross
sectioned);
[0124] FIG. 9 shows a cross sectional view of the valve unit
according to arrows IX-IX of FIG. 8, in the zone where the fluid
passes through respective ports;
[0125] FIG. 10 shows a perspective view of a possible exemplary
embodiment of a stem-piston device, showing a ring-like force
transducer mounted in the stem;
[0126] FIG. 11 shows a perspective view of the piston member of
FIG. 10 separated from the stem;
[0127] FIG. 12 shows a particular "four faces" stem-piston similar
to that of FIG. 11 when the oil outflow occurs;
[0128] FIG. 13 shows a cross sectional view of the geometrically
adjustable braking device;
[0129] FIG. 14 shows an enlarged view of the device of FIG. 13;
[0130] FIG. 15 shows a diagrammatical kinematical view of FIG. 1
illustrating the position of transducers;
[0131] FIG. 16 shows a diagrammatical kinematical view of the above
knee prosthesis;
[0132] FIG. 17 shows the Toe Clearance;
[0133] FIG. 17A shows the Toe Clearance;
[0134] FIG. 17B shows the Toe Clearance;
[0135] FIG. 18 diagrammatically shows an above knee prosthesis with
hydraulic damper having lamellar piston;
[0136] FIG. 18A shows a graphic diagram of the hydraulic damper
having lamellar piston of FIG. 18;
[0137] FIG. 18B shows a graphic diagram of the hydraulic damper
having lamellar piston of FIG. 18;
[0138] FIG. 19 diagrammatically shows an arrangement of the
interface and control transducers with respect to the
surroundings;
[0139] FIG. 19A shows the graphic diagram of the knee and of the
ankle;
[0140] FIG. 19B shows the graphic diagram of the knee and of the
ankle;
[0141] FIG. 20 diagrammatically shows an above knee prosthesis that
provides magnetic motors applied as alternative to hydraulic
dampers;
[0142] FIG. 21 diagrammatically shows the system with fluidic shock
absorbers and electric motors controlled by load cells and pressure
transducers;
[0143] FIG. 22 shows the hydraulic system, in a possible exemplary
embodiment, having spring mechanical accumulators;
[0144] FIG. 23 shows the arrangement of position transducers on the
foot in a proprioceptive leg;
[0145] FIG. 23A shows their graphic diagram responsive to the
relative angles between femur/tibia and tibia/foot;
[0146] FIG. 23B shows their graphic diagram responsive to the
relative angles between femur/tibia and tibia/foot;
[0147] FIG. 24 shows a sensorized insole for detecting the
direction of the force with respect to the ground;
[0148] FIG. 25 shows the sensorized insole of FIG. 24 applied to
the foot of the above knee prosthesis;
[0149] FIG. 26 shows a diagrammatical view of a prosthesis for an
above-knee amputee where the hinge of the knee is in a forward
position;
[0150] FIG. 27 shows a diagrammatical view of an above knee
prosthesis with knee articulation axis arranged in a forward
position;
[0151] FIG. 27A shows how the angle formed between the femoral
segment and the tibial segment changes during the swing phase of
FIG. 27;
[0152] FIG. 28 shows a diagrammatical view of an above knee
prosthesis with knee articulation axis arranged in a forward
position;
[0153] FIG. 29 shows the position of transducers on the femoral
segment and on the damper and the direction of the vector force
with respect to the ground;
[0154] FIG. 30 shows a diagrammatical view of a motor/reduction
gear with freewheel;
[0155] FIG. 31 shows a cross sectional view of an example of a
bicycle-type freewheel to which a gear motor is fixed that works as
brake/motor;
[0156] FIG. 31A shows a cross sectional view of an example of a
bicycle-type freewheel to which a gear motor is fixed that works as
brake/motor;
[0157] FIG. 32 shows a gear motor of worm drive type in a
simplified configuration of operation;
[0158] FIG. 33 shows a motor having variable pitch springs that
allow to achieve optimal stiffness in various configurations;
[0159] FIG. 34 shows a graphic diagram that reproduces the phases
of the gait cycle, respectively at 2 and at 4 km/h;
[0160] FIG. 35 shows, in a three-dimensional simplified
representation, curves identifying, respectively, the tibia-femur
rotation angle, the first derivative with respect to time of the
same and the force acting on the damper;
[0161] FIG. 35A shows in addition a three-dimensional curve where
each curve represents a gait different from a model of
reference;
[0162] FIG. 35B shows a flow-sheet of the main phases followed by
the microprocessor in the operation and control of the gait;
[0163] FIG. 36 shows a storage unit in the form of a rechargeable
battery applied in a releasable way on the tibial segment,
[0164] FIG. 37 shows the energy storage unit, of FIG. 36, with a
respective protection element;
[0165] FIG. 38 shows an external battery of larger size than an
inner battery and that the patient can carry for charging the
latter;
[0166] FIG. 39 shows the energy storage unit, enclosed in
respective housing, having interconnection elements;
[0167] FIG. 40 shows diagrammatically the operations of extracting
the battery, shown in FIG. 39, for charging and/or changing it.
DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT
[0168] With reference to FIG. 1, a diagrammatical kinematik view is
shown of a prosthesis P of prior art for above-knee amputees,
applied to a femoral connection 100 of a possible patient,
comprising: [0169] an upper hinge or femoral segment 1 belonging to
prosthesis P that accomplishes the connection with the femoral
connection 100 of the patient; [0170] an articulation axis 2 that
connects femoral segment 1 with a tibial segment 3 and reproduces
the movement of a normal knee; [0171] an ankle 3a that connects
tibial segment 3 with a prosthetic foot 400; [0172] a damper 5
located between femoral segment 1 and tibial segment 3 that dampens
the relative movement between the above described segments and
allows the above knee prosthesis P to repeat some of the functions
of a normal limb.
[0173] In particular, in the above knee prosthesis P, of FIG. 1,
femoral segment 1 and tibial segment 3 are pivotally connected to
each other about articulation axis 2 that reproduces the knee
movements. Furthermore, tibial segment 3 is articulated by the
ankle 3a to foot 400 comprising toes 400a, a sole of foot 400b and
a heel 400c.
[0174] As well known, the knee movements can be divided into a
phase so-called swing, between bringing the toes off the ground
400a and landing of heel 400c, and a phase so-called stance,
comprising landing of heel 400c, loading the sole of foot 400b and
bringing the toes off the ground 400a.
[0175] The hydraulic damper 5 connects femoral segment 1 with
tibial segment 3 and damps the relative movement of femoral segment
1 with tibial segment 3, so that, especially in the stance phase,
but also in the swing phase, tibial segment 3 is braked with
respect to connection hinge 2 and to femoral segment 1.
[0176] With reference to FIGS. 2 and 3, an above knee prosthesis P
is shown, according to the invention, applied to a femoral
connection 100 of an amputee; conveniently, in FIGS. 2 and 3, the
ankle is not shown in detail and is concealed by an artificial foot
cover.
[0177] Prosthesis P comprises: [0178] upper hinge or femoral
segment 1, which is connected to femoral connection 100 of the
patient; [0179] an articulation axis 2, with the function of
reproducing the knee movements; [0180] a tibia-calf muscle unit or
tibial segment 3 with the function of housing inside the many
elements making up prosthesis P such as hydraulic, electric and
electronic elements, pivotally connected to femoral segment 1;
[0181] damper 5 that reproduces some functions of the calf muscle
and ensures to prosthesis P to brake and to allow the sequential
swing and stance phases typical of the gait; [0182] a lower hinge
11 for connection with a relative ankle 3a (not shown) and a
prosthetic foot 400.
[0183] FIGS. 2 and 3 show also damper 5 comprising a cylinder 5c
where a piston 10 and a stem 9 connected to each other run and are
adapted to carry out a damping reaction responsive to the forces
loaded on the prosthesis.
[0184] In the present exemplary embodiment damper 5 is a hydraulic
damper containing oil in cylinder 5c.
[0185] In particular, the alternated motion of piston 10 and of
stem 9 in cylinder 5c allow the relative movement between femoral
segment 1 and tibial segment 3, allowing to prosthesis P two
principal movements, a first extension movement 14, visible in FIG.
2, and a second compression movement 15, visible in FIG. 3.
Specifically, tibial segment 3, according to a preferred exemplary
embodiment, can rotate about articulation axis 2 of an about
110.degree. angle.
[0186] With reference to FIG. 4, in an enlarged view of the upper
part of prosthesis P, in addition to showing again the femoral
segment 1, the articulation axis 2, tibial segment 3 that houses
damper 5, it shows also a zone 6 housing a battery (not
shown--indicated as 80 in FIGS. 32 and 33) for an electric supply
of prosthesis P and two valve groups 20a and 20b, integral to
damper 5, operated and controlled by relative microprocessors (not
shown), as well as servo-motors (not shown and indicated as 20 in
FIG. 7). In FIG. 4 an arrow 7a indicates where the servomotors are
mounted on the two respective valve groups 20a and 20b. The latter
are operated by the microprocessor, not shown, residing in the
control unit, which operates the opening and closing movements of
the valves (not shown in the figure) that cause the extension
movement 14 and the compression movement 15.
[0187] In particular, femoral segment 1 comprises a connecting
element 1c engaging with femoral connection 100. Connecting element
1c, according to a preferred exemplary embodiment, has prismatic
shape.
[0188] In FIG. 4 it is also visible, according to an exemplary
embodiment of the invention, a gear motor 4, not shown in detail,
which is an active element of knee articulation 2, connected to
femoral segment 1 by an anti-rotation device (not visible in the
figure).
[0189] In parallel, the prosthesis comprises a passive element,
i.e. damper 5, which is connected to two hinges 5a (shown in FIG.
5) to tibial segment 3 and with a hinge 5b (FIG. 4) to femoral
segment 1. In particular, gear motor 4 provides a torque, in some
phases of the gait cycle, adapted to adjust the operation of the
prosthesis with the needs of the user. For example, the gear motor
4, is operated when, during a slow gait, the inertia of the femur
is not enough to align the tibial segment with the femoral
segment.
[0190] With reference to FIG. 5, knee prosthesis P is shown
according to the invention in a cross sectional view made with an
axial plane orthogonal to that of FIG. 4, comprising gear motor 4
mounted in a metal frame 4a, constrained by a connection screw (not
visible in the figure) to femoral segment 1. In particular, metal
frame 4a rotates on bushings 4b, for example of PTFE, arranged in a
support 4c that is constrained by means of screws 4e to tibial
segment 3.
[0191] Such a connection allows to a shaft 4d of gear motor 4 to be
integral to tibial segment 3, while it allows the body of gear
motor 4 to be integral to femoral segment 1. In particular, the
connection between gear motor 4 and femoral segment 1 is carried
out through a shaft 1a and a positive engagement 1b (visible also
in FIG. 4). This way, with respect to femoral segment 1, gear motor
4 generates a motion to shaft 4d that causes tibial segment 3 to
rotate.
[0192] Furthermore, in FIG. 5 the two hinges 5a are shown, which
connect pivotally damper 5 to tibial segment 3 and that allow the
damper to adjust its angular position responsive to the relative
movement between femoral segment 1 and tibial segment 3.
[0193] With reference to FIG. 6 a diagrammatical hydraulic
simplified view is shown of damper 5, mounted on a prosthesis P, of
the types previously described, comprising a cylinder 5c in which
piston 10 and stem 9 slide, which are the dynamic parts of damper
5. In particular, stem 9 and the respective piston 10 divide
cylinder 5c into two chambers, a chamber an and a chamber B,
containing hydraulic oil.
[0194] During the extension 14 or the compression 15 of prosthesis
P, the oil flows from chamber A to chamber B. In particular, since
the volume of stem 9 that enters/exits from cylinder 5c has to be
compensated in volume, an external compensation chamber 16 is
provided partially filled with oil 13 and with air 18 in
pressure.
[0195] In a different exemplary embodiment, not shown,
alternatively to air 18 a spring can be provided with a determined
elastic constant.
[0196] The diagrammatical hydraulic view of damper 5, of FIG. 6,
comprises furthermore: [0197] a channel E_1 extending from chamber
B to compensation chamber 16, between which a check valve VN_1
without pre-charge and an adjustment valve remote 19_E are
arranged; [0198] a channel E_2 extending from compensation chamber
16 to chamber A, between which a check valve VN_2 without pre-load
is arranged; [0199] a channel C_1 extending from chamber A to
compensation chamber 16, between which a check valve VN_3 without
pre-charge and an adjustment valve remote 19_C are arranged; [0200]
a channel C_2 extending from compensation chamber 16 to chamber B,
between which a check valve VN_4 is arranged; [0201] a channel 14'
that connects a chamber 9b of an oil sealing chamber 9a to chamber
16 and is used to avoid pressure peaks in the oil sealing chamber
9a as well as it can be used as compensation chamber and air
emptying chamber in a phase of filling damper 5.
[0202] In addition, two further channels can be considered on the
piston, in particular, a channel 10A and a channel 10B that act as
check valves with pre-loaded spring and with intrinsic damping
characteristics. In particular, these channels bring directly into
contact chamber A with chamber B and act as possible safety systems
for pressure peaks.
[0203] The operation of damper 5 provides mainly a compression 15
and an extension 14. In particular, the compression phase 15,
during the operation of damper 5, comprises: [0204] the movement of
piston 10 and of stem 9 so that the volume of chamber A decreases
while the volume of the respective chamber B increases. This way,
the depression created in channel E_1 and in channel E_2 causes
check valves VN_1 and VN_2 to close. The oil flows then through
channel C_1 pushed by the compression of piston 10, and opens valve
VN_3. Then the oil at the outlet of valve VN_3 finds the resistance
of valve 19_C adjusted with a suitable inlet pressure. The oil,
once passed the resistance of valve 19_C, enters then compensation
chamber 16. In particular, the amount of oil, which is caused by
stem 9 at the inlet, remains in compensation chamber 16 while the
amount of oil attracted by upper chamber B enters through channel
C_2 and opens valve VN_4.
[0205] The extension phase 14 comprises instead: [0206] The
movement of piston 10 and of stem 9 so that the volume of chamber A
increases while the volume of respective chamber B decreases. This
way, channel C_1 and C_2 are closed by check valves VN_3 and VN_4.
The oil flows then through channel E_1, thus opening valve VN_1 and
meeting the resistance of valve 19_E, which is adjusted also
according to a given output pressure. The oil enters compensation
chamber 16 and the exiting amount flows from chamber 16 to chamber
A through check valve VN_2. Channel 14' is used in the presence of
pressure peaks during the extension phase acting as low pressure
system on the sealing member.
[0207] Then, for the extension phase the braking action is of "pure
leakage" type with leakage area that is variable responsive to
position, with braking action that is activated in the last
7.degree.-10.degree. of the knee flexion stroke. The compression of
the limb is carried out, instead, substantially with a plurality of
inverse phases.
[0208] In the alternative exemplary embodiment of FIG. 6A, instead,
there is an adjustment of the braking action during the extension
phase of "geometric" type. More precisely, during the extension
phase, instead of channel 10A, a leakage stem 9' is provided, where
holes 9'' are made with different size from one another and that
allow a progressive passage of oil. In this case, in fact, during
the extension phase oil returning channel C_2 is closed by check
valve VN_4 and does not allow the oil passage. This way, the oil
flows from chamber B to chamber A through the channel present on
stem 9', owing to check valve VN_5 arranged on such channel. In
particular, the oil flows from transversal holes 9'' on stem 9'
into the channel made in stem 9' and opens valve VN_5. Conversely,
during the compression phase the check valve on the stem is
blocked.
[0209] Also it is to be noted that the oil flow is adjusted by
transversal holes 9'' on stem 9'. When they are in the sliding bush
of stem 9', they not take part to the oil flow, and is reduced
therefore the cross section of the oil passage, such that the
braking action tends in this way to become stronger, in a way as
above defined "geometric".
[0210] FIG. 7 shows a view of cylinder 5c of damper 5 having
outside the two valve groups 20a and 20b connected to the
respective servo-motors 20. In particular, the servomotors 20
transmit a torque, adjusted by the respective microprocessor
control unit (not shown) for each valve unit 20a to 20b, which
operates and adjusts the opening and the closing steps of a
respective inner valve 24 (visible in FIG. 8).
[0211] In particular, the damping action of damper 5 is obtained by
adjusting at the same time or separately the extension phase 14 and
the compression phase 15 of FIGS. 2 and 3 according to the needs
deriving from particular gait conditions. Each servo-motor 20 is
mounted separately on the respective valve unit 20a or 20b, for
controlling separately both the extension phase 14 and the
compression phase 15.
[0212] FIG. 8 shows furthermore, in an enlarged view, one of the
two servo-motors 20, depicting the mechanical and hydraulic
connection with the relative valve unit 20a (or 20b not shown). In
particular, the valve unit 20a, depicted in cross section
comprises: [0213] the microprocessor control unit, not shown, which
operates and adjusts a valve 24, where valve 24 has a fixed body
24a on which apertures 19 are made, and a tap 24b that, by
rotating, opens and blocks apertures 19 (see also FIG. 9); [0214] a
sleeve joint 23 for transmitting the torque between a shaft 21 of
servo-motor 20 and tap 24b. In particular, tap 24b transmits its
rotational movement to valve body 24, in order to adjust the
opening and the closing movements of apertures 19; [0215] a bearing
22a where sleeve 23 turns, and a mounting ring element 23a adapted
to support it; [0216] a seal element 23b for the oil flowing in
valve body 24 and an end stop 25 for valve 24a.
[0217] In particular, the microprocessor unit is connected by
cables (not shown) to a Hall effect angular transducer 7 and to
servo-motor 20.
[0218] FIG. 9 shows in particular, a view of the cross section
according to lines IX-IX of valve 24a, tap 24b and valve body 24.
In particular, apertures 19 are shown, which allow the oil to flow,
and are arranged in succession and have an variable size. This way,
valve 24a in the relative rotation about valve body 24, where
apertures 19 are made, adjusts the partial or total opening of the
above described apertures 19 allowing the oil to flow, according to
the damping intensity required by the prosthesis.
[0219] With reference to FIG. 10, a perspective view shows stem 9
and respective piston 10 that is the active portion of damper 5 and
divides cylinder 5c into two chambers an and B (shown in FIG. 6).
In particular, on stem 9 a hole can be made 8a, with an axis
perpendicular to the axis of stem 9, where a dynamometer 8 is
inserted, so-called "Morehouse ring". Obviously, on the stem other
types can be applied of force transducers.
[0220] At the upper end of stem 9, furthermore, a housing 9c is
made for connection with its antithetic part (not visible in the
figure) that represents the hinge 5b of femoral segment 1 (visible
in FIG. 4).
[0221] Alternatively, or in addition, in a way not shown, as
provided by the present invention, force transducers can be
provided on the damper at other points, such as at housing 9c of
upper hinge 5b (see FIG. 10), or in the housing lower hinge 5a, for
example using strain gauges or load cells, or ring transducers.
[0222] FIG. 11 shows a perspective view and detailed of piston 10,
of FIG. 10, which is part of damper 5. In particular, piston 10
comprises "faces" 10a, 10b, 10c and 10d and is arranged for being
covered by metal blades and discs of different thicknesses and
diameters (shown in FIG. 12) that act as springs and open the
apertures according to the speed of the stem in cylinder 5c.
[0223] FIG. 12 shows in an enlarged view piston 10 and the relative
stem 9 comprising, according to a preferred exemplary embodiment, a
first lamina 30a and a second lamina 30b with diameter and
thickness less than first lamina 30a. In particular, first lamina
30a is located at the face 10a of piston 10 (visible in FIG. 11)
whereas second lamina 30b is located at first lamina 30a.
Specifically, blades 30a and 30b are located at piston 10, such
that the respective axes of symmetry coincide with the axis of stem
9.
[0224] In detail, first lamina 30a creates a gap 10e between face
10b of the piston (visible in FIG. 11) and the lower surface of
lamina 30a same. In particular, gap 10e allows a minimum oil flow
from chamber A to chamber B. More precisely, the movement of piston
10, shown in FIG. 12, represents the compression phase 15 in
cylinder 5c. In the compression movement 15 the oil flows from
chamber A to chamber B through a channel 10f. The force of the oil
flow 69 passing through channel 10f causes a deformation of the
blades 30a and 30b, allowing the leakage of oil from one chamber to
the other. Specifically, blades 30a and 30b control a higher or
lower oil flow responsive to the force exerted on the damper and to
the speed of piston 10. Under similar operative steps as described
above, also the extension phase 14 of the prosthesis (not shown in
the figure) can be controlled.
[0225] FIGS. 13 and 14 show a cross sectional view of the device
that carries out the braking action of the knee prosthetic P with a
geometric control, as diagrammatically shown in the hydraulic
circuit of FIG. 6A. In particular, in this device the oil flow is
adjusted by transversal holes 9'' made on stem 9'. This way, when
these are within a sliding bush of stem 9', the oil flow stops, so
that the cross section of the oil passage stops and therefore the
braking action increases.
[0226] In an exemplary embodiment of the present invention, with
reference to FIG. 1,5 and showing again a diagrammatical view of
the prosthesis for above-knee amputees P, also in addition to any
of the exemplary embodiments above described, the following are
provided: [0227] a transducers unit 31 for receiving the data on
the surroundings and, in particular, to allow acquisitions of
information on relative position with respect to the femur, or also
on force; [0228] a microprocessor 32 for computing data and
defining the best logic of control and choice of the operations to
carry out to ensure comfort and a safe gait. [0229] an accumulator
33 of energy that acts in a way suitable to ensure storing energy
of first species (noble) obtained by recovering energy during the
gait and using it in the steps of demand of energy from the device;
[0230] a constraint having an adjustable stiffness, comprising a
device capable of providing/dissipating/recovering energy during
the gait provided at the knee joint, indicated as 34, or at the
ankle joint, indicated as 35, or both.
[0231] In FIG. 16, what shown in FIG. 15 is depicted as block
diagram, i.e. a knee-ankle TRS (Total Recovery System) comprising:
[0232] a recovery device 34 between femoral segment 100 and tibial
segment 3; [0233] a recovery device 35 between tibial segment 3 and
foot 400; [0234] an accumulator 33 of energy; [0235] a data
acquisition transducer 36 for ankle 3a; [0236] a data acquisition
transducer 31 in the articulation axis 2.
[0237] In particular, the operation of the TRS allows the
articulation axis 2 and the ankle 3a to interface with each other
exchanging data and energy.
[0238] As well known, during walking on a plane ground during a
large part of the gait the articulation axis 2 works dissipating
the energy supplied, since the energy supplied by the femur 100
(relative motion between femur and tibia) lifts and launches tibia
3. The articulation axis 2 operates reducing the swinging action of
tibia 3 and supplying safety with a stabilizing moment during a
support phase. During these phases, the dissipated energy, normally
at the articulation axis 2, can be recovered using a suitable
storing device in a unit that has a function of energy accumulator
33. The energy can be exploited partially from the same
articulation axis 2, for example supplying energy in some phases of
the gait cycle and, in particular, when accelerating tibia 3, to
ensure a realignment with femoral segment 1, and partially by the
ankle 3a or for other objects.
[0239] During the gait, the ankle 3a works both as dissipative
element and as active element. In particular, in the first phase of
the gait starting from landing the heel 400c, the ankle 3a acts as
system of a spring and a damper in parallel, where an energy
dissipation occurs in the relative movement of foot 400 with
respect to tibia 3. Then, when heel 400c is not compressed any
more, foot 400 acts as active element supplying energy for lifting
the limb. During the dissipative phase, the energy surplus can be
accumulated in the accumulator 33 at the articulation axis 2. In
analogy to what occurs at articulation axis 2, ankle 3a uses energy
from the accumulator 33 during its active phase, using another
active element in parallel to the spring provided in the ankle.
[0240] The energy storage unit 33 can be for example arranged on
the tibia, as indicated in FIG. 15. Alternatively, the storage unit
is integrated in the motor 34 mounted on the hinge of the knee.
[0241] The device 34 integrated with the device 33, allows to act
on the behaviour of the ankle 3a and of the articulation axis 2,
such that the behaviour of the integrated device 34 and 33 is
suitably phased; the position data of the articulation axis 2 and
of the ankle 3a are continuously monitored by a transducer 36 and
by a transducer 31, which administer also the exchange of data of
the forces of the two transducers.
[0242] FIG. 17 shows how the motor/generator on the knee and on the
ankle can form a knee-ankle system TC (Toe Clarence) comprising:
[0243] a device 41 to adjust and control the articulation axis 2
integrated in the motor/generator 34 of FIG. 16; [0244] a device 42
to adjust and control of the ankle 3a integrated in the
motor/generator 35 of FIG. 16; [0245] The microprocessor 32 that
works as unit decisional; [0246] two transducers 44 and 45 of
interface ground/leg for defining the status of the gait.
[0247] Furthermore, an angle .alpha. is defined determined between
femoral segment 1 and tibia 3 and an angle .beta. determined
between tibia 3 and an axis 3a' orthogonal to tibia 3.
[0248] In particular, at a low speed it is normal that the minimum
dynamic effect of the femur 100 determines a small lifting of
prosthetic foot 400, that, owing to the stiffness of foot 400, ends
for not exceeding the TDC between femoral segment 1 and tibia 3 in
phase of swing, but can generate a risk for the toes to hit the
ground I during the swing phase (FIG. 17A).
[0249] During the gait on a plane ground in elder patients or in
patients in phase of recovery after amputation, it is easy that
realigning tibia 3 with femoral segment 1 is problematic. In a
first case, a Toe Clearance situation occurs, i.e. of lack of
clearance between toes 400a and ground during the gait (FIG. 17A
I). In this phase, the minimum dynamic effect provided by the femur
100 causes a not appropriate lifting action on tibia 3 that has a
relative angle with respect to femoral segment 1 very low with the
risk for the toes of foot 400 to hit the ground. In a latter case,
once passed the TDC between femoral segment 1 and tibia 3, the
problem arises of an effective realignment in case of minimum
swinging action of tibia 3. In order to solve the first problem,
i.e. toe clearance during the swing phase, the knee-ankle system TC
identifies the current configuration according to the data
determined by the transducers and compares these data with the
values of the corresponding ideal configuration. This way, changing
the angle .beta. of incidence of foot 400 with respect to tibia 3,
the risk for the toes can be avoided to hit the ground during the
swing phase (visible in FIG. 17A II). Similarly, supplying energy
to the articulation axis 2, a realignment is ensured of femoral
segment 1 and of tibia 3 for low gait speed.
[0250] The knee-ankle system TC is therefore characterised by the
presence of devices that control the bidirectional flows of energy
towards and from the joints of the system, allowing, thus, by means
of suitable control logics, to determine conditions of the gait
optimized with respect to safety, comfort and energy saving.
[0251] FIG. 18 shows diagrammatically an exemplary embodiment
similar to that shown in figures from 4 to 14, i.e. an above knee
prosthesis P on which a hydraulic damper 46 is mounted comprising
two interfacing chambers 46b,46c, by a hydraulic cylinder 46a with
two valves in parallel: a leakage valve 46e and a lamina valve 46d,
characterized by the possibility to exploit a piston with 2 or 4
faces (visible in FIG. 11). The combination of the two valves 46e
and 46d is like an equivalent valve with variable area responsive
to the speed of the piston 46a. This solution determines a
progressive braking behaviour with equivalent control in force
instead of position. The result is a very progressive dynamic
behaviour that excludes sudden differential reactions of the damper
in case of impulsive loads; such reactions are typical of the
traditional pure leakage systems that have fixed area apertures.
Therefore the damper is like low-pass filter, capable of filtering
and not transmitting to the patient the impulsive loads and
assuring therefore a higher comfort in the gait. It should be noted
that the above knee prosthesis P can be controlled acting on the
stiffness of the lamina valve 46d or on the relative area of the
by-pass, thus ensuring translation of the braking curves
IV,V,VI,VII of FIG. 18B, obtaining high equivalent stiffness for
the phases of support and adjustable for other dynamic phases of
the gait, by damping and stopping the phase of realignment or of
lifting the heel at high gait speeds.
[0252] FIG. 19 represents diagrammatically a possible embodiment of
the invention on an above knee prosthesis P, comprising transducers
48 that allow detecting data on the inner deformation of prosthesis
P, a transducer 49 on the prosthetic foot sole 400, position
transducers 50 and a position transducer for acquisition of data 51
on the surroundings. In particular, such a prosthesis allows an
above-knee amputee to perform a natural gait, developing a system
for adjusting and controlling the gait that reproduces partially
the proprioceptive functions, owing to activity of receptors
similar to those of the muscles and of the tendons, as well as the
view and the spatial relative position. Prosthesis P, if controlled
in this way, may have aspects of predictivity with respect to the
surroundings, in a way suitable to ensure the use of control logics
that is suitable in the actual gait, where the limb seeks safe and
comfortable responses.
[0253] With reference to FIG. 20, a possible embodiment of the
invention is shown diagrammatically on an above knee prosthesis P,
comprising low noise motors/generators. In particular, according to
a preferred exemplary embodiment, such motors/generators 52 are
ultrasonic pulse motors or linear magnetic motors, like those used
in some automotive applications. Furthermore, the device is
characterized for giving to motors 52 a function of generator and
of electronic damper.
[0254] FIG. 21, shows diagrammatically a possible embodiment of the
invention on an above knee prosthesis P, comprising hydraulic
dampers 55 and 56, electric motors 57 and 58, applied respectively
between femoral segment 1 and tibia 3 and between tibia 3 and foot
400. In particular, the electric motors 57 and 58 have respective
position transducers 59, for example encoders, and provide a torque
during the gait, as needed. Furthermore, in FIG. 21 a load
transducer 60 and an energy recovery device 61 are shown, to which
the two hydraulic dampers 55 and 56 are connected. During the
dissipative steps, in particular, in the movement of the
articulation axis 2, the energy surplus can be accumulated in the
device 61. In analogy to articulation axis 2, the ankle 3a can
absorb energy through the device of recovery 61 for carrying out
the active steps.
[0255] FIG. 22 shows diagrammatically an above knee prosthesis P
comprising a energy storage device by means of a spring. Figure
shows, in particular, hydraulic unit 63 and 63a connected to spring
accumulators 64. Furthermore, the above knee prosthesis P has
preloading springs 67 that act in parallel to the hydraulic unit 62
in a relative damping between femoral segment 100, tibia 3 and foot
400. In figure are then shown position transducers 63 applied to
articulation axis 2 and to ankle 3a that are interfaced with the
load cell 68, located at the foot sole 400. Such transducers are
continuously monitored by the software that administers the
exchange of data concerning the forces of the two systems and are
relevant for determining the status of the gait.
[0256] FIG. 23 shows in particular, the arrangement of the position
transducers 70 installed on foot 400 of prosthesis P. In
particular, such transducers 70 are interfaced with each other
measuring the position of the foot with respect to ground and
changing the possible height from ground. FIG. 23A represents, in
detail, the course of the angle .beta. (in the drawing 23A
corresponding to the angle visible in FIG. 16) compared with the
distance from ground .DELTA.t, FIG. 23B, in the corresponding
phases of the gait cycle.
[0257] With reference to FIG. 24, in a second particular aspect of
the invention, a prosthesis is shown having the characteristic of
being equipped with, at foot 400, as shown in FIG. 25, an insole
having an array of force and position transducers, whose signals
are computed by the microprocessor for determining the mode of
interaction of foot 400 of the patient with the surroundings.
[0258] In a possible embodiment of the insole the transducers
located at the insole 200, indicated as closed curves 201 allow to
determine the resultant load vector, in its intensity, direction
and position components, whereby the microprocessor can adjust most
favourably the reaction of the damper.
[0259] In another embodiment of the insole 200 the transducers 201
located at the insole provides data on the point of application of
the resultant load vector, wherein one or more force transducers
are provided located in the artificial limb whose signals, computed
with the signal generated by said insole, allows the microprocessor
to determine the transmitted resultant load vector.
[0260] In addition, the artificial limb comprises a further
transducer of the angular position located at the ankle 3a (not
shown) and adapted to control the relative inclination between
tibia 3 and foot 400. This information allows determining, in
association to the data on the force vector provided by the insole,
the position of the ankle responsive to the corresponding vector
force, since necessarily the load passes through the ankle.
[0261] In FIG. 25 is shown this sensorized insole 200 applied to
foot 400 of the above knee prosthesis P. In particular, the insole
acquires data relative to the position of the force developed in
the contact between foot 400 and the ground on which it rests. This
way, it is possible to ensure with good precision proprioception of
the position of prosthesis P in space and, in particular, of foot
400 with respect to the body of the user. The main object is that
of knowing the point of application of the force on the ground,
which is integrated, in parallel, to the intensity of the force
determined through the axial force transducers.
[0262] FIG. 26 shows an above knee prosthesis P with the
articulation axis 2 in a forward position. This configuration
allows a more raised position of foot 400 and is characterized by
being safe owing to the braking action given by blocked damper
5.
[0263] In case of the swing visible in FIG. 27 the position
described of the IRC recovers space with respect to the ground as
shown in the graphic representation of FIG. 27A, where the peak
value 101 corresponds to a maximum angle formed between femoral
segment 1 and tibial segment 3 (visible in FIG. 19). In particular,
since the phase of Toe Clearance corresponds approximately to the
maximum relative angle between femoral segment 1 and tibia 3, an
anticipated position of the articulation axis 2' ensures some mm of
clearance with respect to the ground. Specifically, with an angle
of 20.degree. of the femur with respect to a vertical direction, it
is possible to have a clearance with respect to the ground of 0.35
mm for each mm of forward movement of the articulation axis 2'. A
forward movement of 1 cm is equivalent approximately to a recovery
of 3.5 mm, clearance from the ground, 2 cm are equivalent 7 mm from
the ground.
[0264] FIG. 28, according to an exemplary embodiment of the
invention, represents diagrammatically a prosthesis P1 with axis of
the femur 100 orthogonal to the ground. FIG. 28 shows the position
of the articulation axis 2' and the different arrangement of damper
5 in prosthesis P1. In particular, the unsteadiness of prosthesis
P1, owing to the position of the articulation axis 2' is
compensated by the safety supplied by damper 5 in the phases of
gait.
[0265] With reference to FIG. 29 the above knee prosthesis P, in
particular according to the first particular aspect of the
invention, is shown. The prosthesis has a force transducer S1
located at damper 5, and the microprocessor receives a force signal
by the force transducer S1 and operates the means for adjusting the
reaction of the damper responsive to the detected force signal on
the damper.
[0266] In particular, the force transducer S1 is arranged on the
fastening the stem, alternatively to what shown in FIG. 10.
[0267] Alternatively, the force transducer on the damper is a load
cell arranged on lower hinge 5a of damper 5. This way it is
possible an instant verification of the status of the load on the
damper and a feedback control on the dynamic behaviour of the
knee.
[0268] According to an advantageous exemplary embodiment,
alternatively, or in addition, a further force transducer S2 on
femoral segment 1 (FIG. 29) is provided so that the microprocessor
receives a force signal from the transducer S2 on femoral segment 1
and operates the means for adjusting the reaction of damper 5
responsive to the detected force signal on femoral segment 1.
[0269] In an advantageous embodiment, the force transducer S2 on
femoral segment 1 comprises a first force transducer adapted to
measure the action on the femur 100 according to a direction
longitudinal to the femur, and a second force transducer adapted to
measure the action on the femur in a direction orthogonal to the
femur. This way, the overall force information on femur 100 and on
damper 5 is capable of determining satisfactorily the tensional
status in the artificial limb.
[0270] In an exemplary simplified embodiment, the second force
transducer on the femur 100 provides only the sign of the force on
the femur in a direction orthogonal to the same.
[0271] Furthermore, a position transducer can be provided at the
articulation axis 2 that reproduces the knee movements, the
position transducer measures, thus, the rotation of the knee.
[0272] In a particular embodiment, the operation provides that
femoral segment 1 and tibial segment 3 are located, at the
beginning of a phase at the end of the swing, which is the phase of
maximum extension of the movement, in a condition of singularity
measured by a mechanical abutment integrated in the damper. This
way, the force transducer S1 on damper 5 measures the actual load
transmitted to the articulation also in the condition of
singularity and the microprocessor that computes the measure can
discriminate and control this phase during the gait.
[0273] FIG. 30 shows, in a fifth particular aspect of the
invention, a motor on the knee articulation capable of allowing in
any case to the patient a swinging action, or swing. In a first
possible embodiment this is obtained with a reduction gear 92
mounted on the motor 91 and have a fast shaft (not shown) connected
to the electric motor 91 and a slow shaft 93 connected to the knee
articulation. The motor 91 supplied by a current whose intensity is
adjusted by the microprocessor (not shown) to obtain a torque at
the articulation axis similar to that obtainable by a hydraulic
damper. An encoder 90 transmits to the microprocessor the rpm of
the motor. On the slow shaft 93 an output shaft 95 is mounted with
a measurement system of the backlash.
[0274] In particular, the angular position of the motor 91 is
continuously determined by an encoder 90. The angular position of
the slow shaft 95 is continuously determined by a second encoder or
by a Hall effect sensor 94 having a magnet. This way, it is
possible to driving the servomotor in order to accumulate the
backlash present in the kinematical chain at the desired speed of
rotation, for example concordant or discordant with the moment
transmitted and depending on the forward or backward movement of
the gear motor; this way, it is possible to minimize the amount of
energy dissipated in the backward movement that is characterised by
less efficiency than the forward movement, and maximizing then the
use of the kinetic energy and the energy recovery in the
accumulator.
[0275] Similarly, in a way not shown but in a way similar to the
gear motor for knee, a second gear motor can be provided connected
to the ankle articulation controlled by the microprocessor in order
to obtain a torque similar to a hydraulic damper.
[0276] In a way not shown, the reduction gear, located at the knee
articulation, has a fast shaft connected to the electric motor and
a slow shaft connected to the articulation that are orthogonal to
each other, to achieve a reduced encumbrance as far as possible
similar to the anatomic sizes. In a similar way, the artificial
limb provides a second gear motor having orthogonal axes and
connected to the slow shaft at the ankle articulation.
[0277] Alternatively, located at the knee articulation and the
articulation of the ankle a freewheel is located (FIG. 31, 31A)
adapted to free the tibia from the reduction gear during the swing
phase, i.e. caused by the inertia of the leg, vice-versa the
freewheel constrains the two movements to each other when the
motor/brake has to act on the tibia. A further exemplary embodiment
not shown provides that on the freewheel, on the shafts of the
reduction gear, two angular transducers are applied adapted to
measure the angular position of the shafts.
[0278] An exemplary alternative structure, equivalent to the
previous, provides one or more moment transducers at the
transducers angular.
[0279] FIG. 32 shows a gear motor 110 of worm drive type. In
particular, the wheel 105 has a gear ratio between the fast shaft
107 and the slow shaft 108 higher or equal to 5.
[0280] On the quick shaft 107, in particular, a first position
transducer is applied (not shown) to determine the instant position
of the same; on the slow shaft 108 a second position transducer is
mounted (not shown). This way the motor 109 drives the fast shaft
107 in order to maintain a predetermined play with the slow shaft
108 and to allow the reversibility of the motion.
[0281] FIG. 33 shows another exemplary embodiment of the
brake/motor device 96 on the knee articulation 2. The object is of
assuring a correct position of femoral segment 100 with respect to
tibial segment 3 in all the gait conditions, in particular at low
speed.
[0282] In particular, the motor 96 intervenes assuring the correct
realignment of tibia 3 if the patient, in particular a new amputee
or a elder person, has hesitations during the gait.
[0283] According to the operation of this solution, for reducing
the energy consumption of prosthesis P, and increasing the range of
the motor/generator system 96, variable pitch springs 97 are
provided that allow to achieve an ideal stiffness, i.e. low
stiffness for small angular travel between femoral segment 100 and
tibial segment 3, and high stiffness for large angular travel.
[0284] In particular, variable pitch springs 97 are helical springs
having a diameter and a first pitch P.sub.1 at one end and a second
pitch P.sub.2 at the opposite end in order to obtain a continuous
transition of the stiffness between a first value K.sub.1 and a
second value K.sub.2.
[0285] FIG. 34 shows, according to the fourth particular aspect of
the invention, a graphic diagram that reproduces the movement of
the artificial limb, for adjusting the pace of the gait in a same
gait cycle. In particular, FIG. 34 shows a case of walking on a
plane ground, is defined by a family of similar curves having
different amplitude responsive to the average walking speed. The
curves comprise the trajectory of tibia 3 with respect to time
described by the angle tibia-femur and by its derivatives with
respect to time.
[0286] More precisely, for a measured speed, an ideal curve that
describes a gait comprises two sub-curves, a smaller inner curve
X', corresponding to the stance phase, and a larger external curve
X'', always corresponding in part to the stance phase, at least for
part in the first quadrant.
[0287] Both curve pass through the origin. Versus the speed of the
gait the curves change shape, describing wider trajectories with an
increase of the speed of the gait, respectively depicted by the
corresponding curves XI', XI''. In particular, the relative speed
of the gait are 2 and 4 km/h, respectively for curves X', X'' and
XI', XI''.
[0288] Then, since each curve defines an ideal gait cycle for a
measured speed, and the curve changes its shape versus the gait
speed, and each curve has a corresponding parameter, once detected
a change of the speed within a gait cycle, it is possible to cause
tibia 3 to follow a curve corresponding in that phase of the gait
cycle, but for a new speed. This way, by recognizing quickly the
need of the amputee to change the speed of the gait, it is possible
to cause the prosthesis to follow a curve of different amplitude
with respect to that followed previously.
[0289] The typical operations of stopping from walking, sitting
down and standing up can be defined in turn by special families of
curves. Similarly, walking uphill, downhill, going down and up the
stairs, pedalling on a bicycle, and, in general, other possible
conditions of movement, can be represented, in general in a
n-dimensional space, by a characteristic curve.
[0290] It is possible to increase the parameters defining the
curve, and in a possible configuration of the space, exemplifying
and not limitative, the coordinates are five: [0291] time; [0292]
relative rotation angle between tibia and femur; [0293] first
derivative with respect to time for said angle; [0294] algebraic
value of the resultant load vector transmitted to the ground;
[0295] algebraic value, with respect to the axis of rotation of the
articulation, of the moment of the resulting from.
[0296] It is possible to put further parameters, such as the second
derivative of the angle, for representing in a more complete and
generalized way the different possible gait conditions; or it is
possible to reduce the number of coordinates to obtain a simplified
but rougher representation.
[0297] In addition, further transducer means are provided adapted
to measure continuously with respect to time, or at discrete time
intervals, the parameters that represent the coordinates of the
space. In particular, at least one memory unit is provided, such as
a RAM, ROM, EPROM etc. adapted to memorize the characteristic data
of the curve X',X'' and XI',XI'' and to memorize the data
determined by the transducers with respect to time.
[0298] Furthermore, a microprocessor is provided adapted to analyse
the data determined by the transducers, comparing them with the
data recorded in the memory unit, for determining, among the
recorded data, the curve that is most suitable for representing the
actual gait, called ideal curve.
[0299] This way, the microprocessor adjusts the reaction of the
damper for minimizing the error definable as the distance, in an
n-dimensional space, between the actual point, whose coordinates
are the measurements made by the transducers, and the corresponding
point of the ideal curve. Furthermore, the microprocessor
ascertains, according to the error, to the ideal curve used and to
the family of curves, if it is useful to continue on the actual
ideal curve, or if it is better to use a different ideal curve or
to change family of curves.
[0300] This architecture of control is capable, thus, of optimize
the gait responsive to the evolution of the psychophysical
conditions of the patient, therefore the patient walks always at
best both just after the amputation, when hesitation for the gait
is high, and when the amputee has acquired more confidence. A
further advantage is that the time for rehabilitation is reduced,
since the patient is continuously assisted by a device that carries
out the function of electronic rehabilitating device suitable for
correcting and improving the gait.
[0301] Another possible exemplary embodiment provides measuring the
moment of the femur at the articulation, and in this case, and
without limiting the scope of the invention, the coordinates of the
space are the following: [0302] time; [0303] relative rotation
angle between tibia and femur; [0304] first derivative with respect
to time for said angle; [0305] longitudinal force acting on the
damper; [0306] moment transmitted by the femur to the
articulation.
[0307] The latter parameter allows detecting indirectly the wishes
of the patient, because these are evidenced by the moment that the
stump produces on the articulation.
[0308] FIG. 35 shows a curve that defines an ideal gait cycle for a
determined average speed. With respect to the average speed the
curve changes its amplitude, but the curve shape is the same. Then
a family of similar curves, described in a three-dimensional space,
like that of FIG. 35, identifies univocally walking on a plane
ground and a parameter, such as the average speed, discriminates
the curves of the family from one another.
[0309] FIG. 35A shows, instead, a plurality of three-dimensional
curves used, in particular, as reference for controlling and for
adjusting the swing phase. The present figure highlights a curve
120 which distinguishes from the model of reference. In this case,
the reason could be a wrong gait of the patient that hits against
an obstacle or stumbles during the gait.
[0310] In the present simplified configuration, the coordinates of
the space are three: tibia-femur rotation angle 102, first
derivative with respect to time for the tibia-femur rotation angle
103 and force acting on the damper 104, orthogonally to the plane
containing the two axes 102 and 103.
[0311] Without limiting the scope of the invention, the need of
accelerating the gait on a plane ground causes a variation of
moment and/or force orthogonally to the femur. The same occurs when
the patient wishes to decelerate.
[0312] The control system, acquiring the values of these parameters
that are correlated to the need of the patient, is capable to
adjust the behaviour of the artificial limb to ensure a very quick
response to follow the wishes of the patient, about substantially
instantaneously. This control system is suitable especially for
those patients that need a high dynamism. In general it recovers,
at least partially, proprioception of the missing limb since a
direct relationship is established between the wishes of the
patient, (for example the pressure of the fastening of the
prosthesis on the skin of the stump) action and perception.
[0313] Alternatively, the means for defining the gait conditions
are of matrix type.
[0314] FIG. 35B shows a flow-sheet of a loop of control and
operation of the gait mounted on the prosthesis. In particular,
after the input of data such as, for example, angle of the
articulation and first derivative thereof, estimation is calculated
of the speed of the gait. At the same time, the program recalls
from a memory the reference curves. Then, there the speed of
reference obtained integrating the chosen reference curve is
obtained. This way, in the successive gait cycle, a corresponding
reference of force and compensation of the error are obtained
through an input and output of the force applied on the damper. As
final step, a command signal is sent for adjusting the oil flow by
the respective solenoid valves, If the hydraulic circuit of the
prosthesis is that of FIG. 6. Vice-versa, the command signal is
sent only to the solenoid valve in the case of FIG. 6A with
geometric adjustment of the extension phase.
[0315] FIGS. 36 and 37 show a view, in a sixth particular aspect of
the invention, of the electronic devices that are arranged in the
artificial limb, both in the case of only the knee articulation and
in the case of the latter in combination with the ankle
articulation, fed by a rechargeable battery 80, for example of the
type with lithium ions, replaceable quickly and autonomously by the
same patient that can wear the artificial limb when replacing the
batteries.
[0316] A special device, for example an acoustic alarm (not shown),
signals to the patient when battery 80 on the artificial limb is
going to be flat. The patient can, thus, easily replace it with a
second battery that has been brought with; This way, the range of
the prosthesis is longer.
[0317] The number of charged batteries that the patient carries
with can be naturally larger than two, and this is advantageous for
patients who like trekking, or who are accommodated, even
occasionally, where electricity is not easily available, or to
avoid long waits for one battery to be recharged.
[0318] Battery 80 is located at the rotula in a forward position
with respect to the articulation axis 2; the patient can approach
battery 80 for removing and replacing it only in safety conditions,
i.e. when sitting, whereas the slot containing the battery cannot
be opened in other situations (as shown in FIG. 40); therefore the
arrangement in a front position of the battery allow an easy access
from the above ensuring at the same time a geometry following the
anatomy of the missing limb, respecting safety ergonomic
conditions.
[0319] In combination or alternatively, with the previous features,
on the artificial limb, both in the case of only the knee
articulation or in case of a combination of the latter with the
ankle articulation, the devices are fed by a rechargeable battery
80, for example of the type with lithium ions, whose recharging
circuit may be connected to the supply circuit 83' external to the
limb by a primary/secondary connection 88 of a transformer, as
shown in FIG. 38.
[0320] The recognition and the connection between the two circuits
is effected by two respective magnets 130 that in use, are located
coincident with each other. This way, the patient can easily
recharge battery 80 while wearing the artificial limb, an aesthetic
coating 81, also shown in FIG. 36, and clothes 81'.
[0321] In addition, the outer recharging circuit can be supplied in
turn by a battery of larger size (not shown) that the patient can
wear, for example fastened to a waistbelt, in a backpack, in a
pocket etc.
[0322] Alternatively, on the artificial limb a port is present 85,
for example of USB type, shown in FIG. 39, by means of which the
artificial limb P can be connected, both in the case of only the
knee articulation and in the case of the latter in combination with
the ankle articulation, to a computer in order to obtain, by a
single link, the charge of battery 80 that feeds the electronic
devices that are arranged in the artificial limb, for updating the
firmware, and transferring, for a deferred analysis, the data
recorded by the artificial limb to the computer.
[0323] Furthermore, special software installed on the computer or
available in the network analyses the data stored in the memory of
the artificial limb and programs again the firmware for improving
the behaviour of the artificial limb responsive to the wishes of
the patient.
[0324] FIG. 40 shows the steps of changing battery 80. In
particular, they comprise simply opening a cover 84 and changing
battery 80. Battery 80 is at the rotula in a forward position with
respect to the articulation axis 2 and is accessible from the above
by the patient who is in a sitting position, in a way congruent
with the geometry of the limb, in a safety position with sitting
patient.
[0325] The foregoing description of a specific embodiment will so
fully reveal the invention according to the conceptual point of
view, so that others, by applying current knowledge, will be able
to modify and/or adapt for various applications such an embodiment
without further research and without parting from the invention,
and it is therefore to be understood that such adaptations and
modifications will have to be considered as equivalent to the
specific embodiment. The means and the materials to realise the
different functions described herein could have a different nature
without, for this reason, departing from the field of the
invention. It is to be understood that the phraseology or
terminology employed herein is for the purpose of description and
not of limitation.
* * * * *