U.S. patent application number 12/018530 was filed with the patent office on 2009-01-29 for interface to fes control system.
This patent application is currently assigned to Neopraxis Pty. Ltd.. Invention is credited to Andrew Barriskill, Michael Robert Duncan, Simon Geoffrey Parker.
Application Number | 20090030482 12/018530 |
Document ID | / |
Family ID | 3823471 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090030482 |
Kind Code |
A1 |
Barriskill; Andrew ; et
al. |
January 29, 2009 |
INTERFACE TO FES CONTROL SYSTEM
Abstract
A functional electrical stimulation system for controlling the
movement of a portion of a body of a subject, such as the subject's
legs. The system comprises a sensor that in one arrangement is
mountable to a portion of the subjects' body other than the legs,
for example the torso. In another arrangement, the sensor can be
mountable to a walking aid, such as a crutch. The sensor outputs
signals representative of the position and/or movement of the torso
or walking aid. The system also comprises a control means that
receives and processes the signals output by the sensor and outputs
control signals to a stimulator adapted to provide electrical
stimulation to the legs via electrodes in response to the position
and/or movement of the torso or walking aid as determined by the
sensor.
Inventors: |
Barriskill; Andrew; (Lane
Cove, AU) ; Duncan; Michael Robert; (Lane Cove,
AU) ; Parker; Simon Geoffrey; (Randwick, AU) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
Neopraxis Pty. Ltd.
|
Family ID: |
3823471 |
Appl. No.: |
12/018530 |
Filed: |
January 23, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10344554 |
Jul 11, 2003 |
7346396 |
|
|
PCT/AU01/00992 |
Aug 14, 2001 |
|
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12018530 |
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Current U.S.
Class: |
607/49 |
Current CPC
Class: |
A61N 1/36003 20130101;
A61B 5/11 20130101 |
Class at
Publication: |
607/49 |
International
Class: |
A61N 1/00 20060101
A61N001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 14, 2000 |
AU |
PQ9413 |
Claims
1. A functional electrical stimulation system for controlling the
movement of one or both legs of a body of a subject comprising: a
measuring device having at least one sensor that is mountable to at
least one of the torso or head of the subject and which outputs
signals representative of the angle of said subject's torso or head
relative to a predetermined a predetermined spatial reference
plane; a controller that receives and processes the signals output
by the measuring device and outputs control signals; and a
stimulator that receives the control signals and is adapted to
provide electrical stimulation to said one or both legs in response
to said output signals determined by the measuring device.
2. The functional electrical stimulation system of claim 1 wherein
the measuring device only measures the angle of said at least one
of the torso or head when that body portion has stopped gross
movement.
3. The functional electrical stimulation system of claim 1 wherein
the measuring device comprises at least one transducer.
4. The functional electrical stimulation system of claim 3 wherein
said at least one transducer is implantable within the subject.
5. The functional electrical stimulation system of claim 1 wherein
the controller further comprises a storage unit having at least one
predetermined action sequence storable therein, and further
wherein, on receipt of signals from the measuring device, said at
least one predetermined action sequence is provided to the
stimulator.
6. The functional electrical stimulation system of claim 5 wherein
said at least one predetermined action sequence results in the
subject moving from a standing to a sitting position, or moving
from a sitting to a standing position, walking, or moving the legs
in a pedaling action.
7. The functional electrical stimulation system of claim 1 wherein
said at least one sensor is mounted to the torso and further
wherein, the controller outputs control signals to the stimulator
when the torso of the subject is bent forward by an angle of
between about 10.degree. and about 60.degree. relative to a
notional horizontal plane.
8. The functional electrical stimulation system of claim 1 wherein
said at least one sensor is mounted to the torso and further
wherein, the controller outputs control signals to the stimulator
when the torso of the subject is bent forward by an angle of
between about 250 and about 500 relative to a notional horizontal
plane.
9. The functional electrical stimulation system of claim 1 wherein
said at least one sensor is mounted to the torso and further
wherein, the controller outputs control signals to the stimulator
when the torso of the subject is bent forward by an angle of
between about 250 and about 450 relative to a notional horizontal
plane.
10. The functional electrical stimulation system of claim 1 wherein
the stimulator further comprises at least one electrode mountable
on said body portion and is electrically connected to the output of
the stimulator.
11. The functional electrical stimulation system of claim 1 wherein
the system further comprises an override device that monitors the
position of said subject and prevents provision of electrical
stimulation to said body portion if the position of said subject is
such that stimulation is inappropriate or unsafe for the
subject.
12. The functional electrical stimulation system of claim 1 wherein
the system further comprises a feedback device that measures the
position or movement of said body portion being stimulated by the
stimulator and provides output signals to the controller
representative of these measurements.
13. The functional electrical system of claim 1 wherein the
controller has an operation having an activation and deactivation
device that allows the subject to selectively turn on and off at
least one of the controller and the functional electrical
stimulation system.
14. A functional electrical stimulation system for controlling the
movement of a portion of a body of a subject comprising: a
measuring device having at least one sensor that is mountable to
the torso of the subject and which outputs signals representative
of the angle of said subject's torso relative to a predetermined
spatial reference plane; a controller that receives and processes
the signals output by the measuring device and outputs control
signals; and a stimulator that receives the control signals and is
adapted to provide electrical stimulation to said one or both legs
in response to the angle of the subject's torso determined by the
measuring device; wherein, on detecting twisting movements of the
torso and that the subject is at least substantially horizontal,
the controller outputs control signals that cause the stimulator to
output a sequence of stimulation impulses that serve to roll the
subject over.
15. The functional electrical stimulation system of claim 14
wherein the controller is programmed to output signals to the
stimulator to cause roll over of the subject at predetermined
times.
16. The functional electrical stimulation system of claim 15
wherein the controller is programmed to output signals causing roll
over of the subject at least 2 times in an 8 hour period.
17. A functional electrical stimulation system for controlling the
movement of one or both legs of a body of a subject comprising: a
measuring device having at least one sensor that is mountable to at
least one of the torso or head of the subject and which outputs
signals representative of the angle of said subject's torso or head
relative to a predetermined spatial reference plane; a controller;
and a stimulator; wherein the controller further comprises a
storage unit having at least one predetermined action sequence
storable therein that is provided to the stimulator on receipt of
predetermined control signals from the controller, said action
sequence resulting in the subject moving from a standing to a
sitting position or moving from a sitting to a standing
position.
18. A controller for a functional electrical stimulation system
that provides a subject that is unable to walk naturally with a
means of continuously controlling a walking sequence created by the
functional electrical stimulation system during performance of the
sequence, the functional electrical system comprising: a measuring
device having at least one sensor that is mountable to at least one
of the torso or head and which outputs signals representative of
the current position and movement of said subject's torso or head
that can be moved naturally by the subject; a controller; and a
stimulator; wherein the controller receives and processes signals
output by the measuring device and outputs control signals to the
stimulator to provide electrical stimulation suitable to cause the
legs of the subject to move with a walking movement, said movement
being in response to the current position and movement of said
subject's torso or head as determined by the measuring device.
19. A method of controlling functional electrical stimulation
provided to one or both legs of a subject and so controlling the
movement of one or both legs, the method comprising: measuring the
angle of said subject's torso or head relative to a predetermined
spatial reference plane; processing the signals; and outputting
electrically stimulation to said one or both legs in response to at
least one of the measured position and movement of said subject's
torso or head.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a functional electrical
stimulation (FES) system and method of using such a system. More
particularly, the invention relates to a device and method for
providing a person using functional electrical stimulation with a
means of controlling the electrical stimulation provided to their
limbs.
BACKGROUND OF THE INVENTION
[0002] In the area of medical technology, much advancement have
been made to assist individuals who have previously been considered
to be disabled in some way, to lead a relatively normal life in
spite of such disabilities. Such advancements include the provision
of hearing aids and cochlear implants for the hearing impaired, as
well as pacemakers for those who experience cardiac problems, to
name a few. However with regard to persons suffering from spinal
cord injury and those who have lost function of their limbs, the
provision of a device or devices to return desired function to the
individual has as yet proven difficult to implement. Functional
electrical stimulation (FES) systems of various types are seen to
have particular application in providing persons suffering from
spinal cord injury or deficiency, such as paraplegia, with a
capacity to make controlled movements of their dysfunctional
legs.
[0003] Functional electrical stimulation systems use electronics to
generate electrical impulses. These impulses are then delivered to
the serves or muscles of a subject via electrodes to stimulate
movement of the muscles that axe otherwise dysfunctional. In order
for useful and controlled movements of limbs to be achieved several
muscles must usually be operated in concert. This is normally
achieved by an algorithm executed under the control of the FES
system to deliver a pattern or sequence of stimulation
impulses.
[0004] An important aspect of the successful implementation of such
an FES system is the provision of a control technique that controls
the limbs of a patient so that they follow a desired trajectory. It
is extremely difficult, however, to choose a trajectory of the
limbs so that a functional task such as standing is performed. In
one proposal, control is provided by a touch pad interface which
can be activated by the subjects fingers to some control types of
movement, such as standing, sitting and walking.
[0005] Such touch pad interfaces as known in the art do not provide
an intuitive interface for the subject with the FES system and
assume that the subject has full hand control to enable use of such
a device. Existing FES systems are, therefore, relatively difficult
to learn how to use and require a certain amount of dexterity which
has the potential to move subjects in undesirable ways.
[0006] Any discussion of documents, acts, materials, devices,
articles or the like which has been included in the present
specification is solely for the purpose of providing a context for
the present invention. It is not to be taken as an admission that
any or all of these matters form part of the prior art base or were
common general knowledge in the field relevant to the present
invention before the priority date of each claim of this
application.
SUMMARY OF THE INVENTION
[0007] Throughout this specification the word "comprise", or
variations such as "comprises", or "comprising", will be understood
to imply the inclusion of a stated element, integer or step, or
group of elements, integers or steps, but not the exclusion of any
other element, integer or step, or group of elements, integers or
steps.
[0008] According to a first aspect, the present invention is a
functional electrical stimulation system for controlling the
movement of a portion of a body of a subject comprising:
[0009] a measuring means having at least one sensor, mountable to a
portion of the subjects body other said body portion, that outputs
signals representative of the position and/or movement of said
other portion of the subject's body; and
[0010] a control means that receives and processes the signals
output by the measuring means and outputs control signals to a
stimulating means adapted to provide electrical stimulation to said
body portion in response to the position and/or movement of said
other body portion determined by the measuring means.
[0011] In one embodiment of this aspect, the said other body
portion is selected from the group comprising the torso, the head
or one or both arms of the subject.
[0012] In a further embodiment, said body portion is one or both
legs of the subject.
[0013] The present invention provides a system that can be
relatively easily used, in one arrangement, to generate one or more
desired angles between the respective thighs and lower legs of a
paraplegic with the legs being controlled by electrical stimulation
of the muscles so that the actual measured angle of the thigh and
lower leg corresponds to the desired angles.
[0014] In a preferred embodiment, the measuring means measures the
angle of the subject's torso relative to a predetermined plane. The
predetermined plane can be a sagittal plane, a frontal plane or a
horizontal plane. In one embodiment, the measuring means only
measures the angle when the torso has stopped gross movement. In
another embodiment, the measuring means measures the angle
throughout the range of movement of the torso.
[0015] In another embodiment, the measuring means detects torso
movements that are determined by the control means as indicative
that the subject wishes to roll over when they are in a horizontal
position, such as when they are asleep. Such torso movements will
typically comprise twisting movements of the torso.
[0016] In yet another embodiment, the measuring means measures the
angle of the torso relative to the position of one or both of the
lower limbs of the subject.
[0017] In one embodiment, the measuring means can be carried by the
subject. The measuring means may be carried in a harness or
clothing worn by the subject. In another embodiment, the measuring
means may be strapped about the torso of the subject. In an
alternative embodiment, the measuring means or componentry thereof
can be implantable within the subject.
[0018] In a preferred embodiment, the measuring means comprises one
or more transducers that outputs signals representative of the
position and/or movement of the transducer to the control means.
Where the measuring means is measuring the angle of the torso
relative to the lower limbs, a transducer can be mounted on the
torso and on one or both of the lower limbs. More than one
transducer mounted on the torso and/or the lower limbs can be
envisaged. Each of the transducers in this case would output
signals to the control means.
[0019] The control means preferably processes the output signals of
the transducer or transducers and then outputs signals to the
stimulating means to provide electrical stimulation to the muscles
of the subject. The control means can execute an algorithm that
leads to provision of electrical stimulation to the appropriate
muscle(s) at the appropriate intensity as dictated by the subject
or a predetermined programme. The output signals of the transducer
or transducers and those of the control means to the stimulating
means can comprise electrical or optical signals.
[0020] In a further embodiment, the control means can have a
storage means having at least one predetermined action sequence
storable therein. On receipt of signals from the measuring means,
said at least one predetermined action sequence can be provided to
the stimulating means. The predetermined action sequence can result
in the subject moving from a standing to a sitting position, or
moving from a sitting to a standing position, walking, or moving
the legs in a pedaling action. Other suitable predetermined action
sequences can be envisaged.
[0021] In one embodiment, the control means is adapted to output a
pre-determined sequence of signals to the stimulating means upon
receiving signals from the transducer or transducers that the
subject's torso is at a particular pre-determined angle relative to
a plane, such as a notional horizontal plane, or the lower limbs.
For example, when the subject bends their torso forward from the
hip this can be measured by the transducer with appropriate signals
provided to the control means.
[0022] In one embodiment, the pre-determined sequence of signals to
the stimulating means can be output by the control means when the
torso has bent forward by an angle of between about 10.degree. and
about 60.degree., more preferably between about 25.degree. and
50.degree., and still more preferably between about 25.degree. and
45.degree..
[0023] In another embodiment, the control means is adapted to
output a series of predetermined signals representative of the
position of the subject's torso.
[0024] A particular series of various positions of the torso can
cause the control means to output a particular series of signals to
the stimulating means so causing a particular series of
stimulations to the muscles of the subject. This allows a subject
to learn a particular series of movements that lead to a particular
desired series of movements of the stimulated limbs of the subject.
For example, a movement or series of movements of the torso may
initiate a step by a leg or a series of steps by the subject's
legs. Alternatively, a movement or a series of movements of the
torso may initiate a standing or sitting action.
[0025] In response to the detection of signals from the control
means, the stimulating means is adapted to output electrical
impulses. These impulses axe transmitted to the subjects nerves or
muscles from a stimulator through electrically conducting leads to
stimulation electrodes. The electrodes can be surface mounted on
the skin of the subject, percutaneous intramuscular electrodes that
are implanted with a minimally invasive needle insertion procedure,
or fully implanted electrodes. The stimulating means preferably has
circuitry adapted to drive whatever electrodes are selected for use
with a particular subject.
[0026] In one embodiment, the stimulator can be carried by the
subject. The stimulator can be carried in a harness or clothing
worn by the subject. In another embodiment, the stimulator may be
strapped to the subject. In an alternative embodiment, the
stimulator or componentry thereof can be implanted within the
subject. The electrical leads extending from the stimulator to the
electrodes can be totally implantable within the subject or carried
externally on the body of the subject.
[0027] In a preferred embodiment, the electrodes can be mounted to
the lower limbs of the subject. It will be envisaged that the
electrodes could be mounted to the upper limbs or that electrodes
may be mounted to both the upper and lower limbs of the
subject.
[0028] Where the electrodes are mounted to the lower limbs, the pre
determined sequence of signals generated by the control means is
provided to the lower limbs.
[0029] In the embodiment where a bend of the torso to a
pre-determined angle relative to the horizontal plane is made, the
control means can be programmed such that the predetermined
sequence of signals generated on detection of such a change in the
position of the torso causes the subject to be moved from a sitting
position to a standing position or vice versa.
[0030] As discussed above, in another embodiment, a particular
series of various positions of the torso can cause the control
means to output a particular series of signals to the stimulating
means so causing a particular series of stimulations to the muscles
of the subject. For example, when the subject is in a particular
pre-determined position, the angle of the torso relative to the
horizontal plane can determine the angle between the thigh and
lower leg of each leg of the subject. The control means preferably
only allows torso movement to control limb angle when the subject
is in a position that variation in limb angle is appropriate or
safe for the subject. When the torso is upright, the angle between
the torso and the horizontal plane is about 90.degree.. If the
angle between the thigh and lower leg is not about 90.degree., the
stimulating means stimulates the muscles within the leg until this
angle is achieved. This should be relatively comfortable for the
subject as when sitting upright in a chair a person's thighs are
typically about normal to the lower leg. When the subject bends
their torso relatively forward, the angle between the torso and the
horizontal plane decreases. This decrease in angle leads the
control means to output signals causing flexion of the lower leg,
preferably to a predetermined degree, so moving the feet to a
position ready to allow the subject to stand. Once the feet are in
position, the subject can, for example, move their torso backwardly
relative to the horizontal plane. This movement, if detected by the
control means following the previous forward movement, can lead the
control means to cause full extension of the legs so moving the
subject from a sitting to standing position.
[0031] Detection of other movements of the torso can lead the
control means to output other pre-programmed sequences of signals.
For example, if the subject considers that they are not in a
position to stand once the feet have been moved the predetermined
degree, a further forward or other movement of the torso can cause
the control means to stimulate the lower leg to return to a
position about 90.degree. relative to the thigh so leaving the
subject in a sitting position.
[0032] When a subject is in a standing position, controlled
movement of the torso can allow the subject to move to a sitting
position. For example, forward bending of the torso relative to the
horizontal plane (so decreasing the angle of the torso to the
notional horizontal plane) can cause the control means to stimulate
the legs of the subject to decrease the angle between the thigh and
lower leg from about 180.degree. gradually towards about 90.degree.
at which point the legs are in a position to allow the subject to
comfortable sit upon a chair.
[0033] In another embodiment, when the subject is in a particular
pre-determined position, variation in the angle of the torso and/or
head, or both in combination, relative to the lower limbs can allow
a subject to control initiation of a step or sequence of steps.
Sequential variations in torso position relative to the lower limbs
can control a series of alternate steps by the subject's legs.
Preferably, the subject can learn to perform this sequential
variation in torso and/or head angle and so control their step
movement. Again, the control means preferably only allows torso
movement to control step initiation when the subject is in a
position that step initiation is appropriate or safe for the
subject.
[0034] A system of using torso and/or head angle allows the subject
to define their preferred limb angle. This allows the subject to be
trained to control the standing and sitting process or wading using
the FES system. This gives the subject a greater sense of
controlling the stimulation provided to their limbs rather than
being in a position of feeling that the system is entirely in
control of their movement. This is envisaged as providing the
subject with a greater sense of confidence in using function
electrical stimulation systems so leading to greater use of the
system.
[0035] As discussed above, the control means can be adapted to
output a pre-determined sequence of signals to the stimulating
means on receiving signals from the transducer that the subject is
twisting their torso in a manner indicative that the subject wishes
to roll over. In this case, the stimulating means can be adapted to
stimulate the legs in a manner that assists the subject in turning
over. In one embodiment, the system will assist turning over when
the subject is asleep. In this case, it is preferred that the
stimulations to the legs are just sufficient to assist turnover
without being of a magnitude that significantly disturbs the sleep
of the subject.
[0036] In a preferred embodiment, stimulation of the legs to assist
turning over is only activated by the control means when the
patient is lying in a substantially horizontal plane. For example,
the transducer can determine the orientation of the subject and
provide a signal to the control means representative of the
orientation. In such instances, whenever the transducer is
outputting a signal that indicates that the subject is not
substantially horizontal, the control means is locked from
outputting the signal sequence that would be employed to assist
rolling over.
[0037] In another embodiment, the control means can be programmed
to output signals to the stimulating means to cause roll over of
the subject at predetermined times or at predetermined rates. For
example, the control means can be programmed to output signals
causing roll over of the subject at least 2 times in an 8 hour
period. These roll overs could be additional to those that occur in
response to detection of torso twisting or movement indicating a
desire by the subject to roll over. In one embodiment, the control
means could monitor the number of assisted roll overs performed in
response to torso movement or twisting and only institute an
involuntary roll over if the subject has not rolled over for a
predetermined minimum period of lime. For example, the control
means may be adapted to institute an involuntary roll over if no
roll over has occulted for at least 4 hours.
[0038] Assistance in rolling over provided by the present system
should reduce the incidence of pressure sores and disrupted sleep
for spinal cord injured persons who are unable to relieve pressure
during sleep by rolling over.
[0039] In a preferred embodiment, the system includes a feedback
means that measures the position and/or movement of said body
portion being stimulated by the stimulating means and provides
output signals to the control means representative of these
measurements. The feedback means can comprise one or more
transducers mounted to the limbs being stimulated. Where a subjects
legs axe being stimulated, one or more transducers may be mounted
to the thigh and/or lower leg of the subject. In another
embodiment, the transducers can be fully implantable within the
legs.
[0040] The signals provided by the feedback means can be used to
override the instruction provided by the subject by bonding their
said other body portion, such as their torso, if the control means
detects that the limbs are in an unsuitable position to be
stimulated. Once stimulation has commenced, for example to cause
the subject to stand, the control means can also use the output
signals of the feedback means to determine if the limbs of the
subject are responding and to adjust the pattern and location of
the stimulation if required. Such a feedback means provides the
system with the flexibility to adjust its performance depending on
the circumstances faced by the subject. For example, a different
stimulation pattern may be required to successfully move a subject
from a sitting position on a low couch to a standing position
compared to that required to achieve the same result from sitting
in an upright chair.
[0041] The signals provided by the feedback means can also be used
by the control means as a means of determining if the subject is in
a substantially horizontal position. If the feedback means outputs
signals to the control means that the subject is not substantially
horizontal, the control means is preferably locked from outputting
the sequence of signals that would normally be output to the
stimulating means to assist rolling over on detection of torso
movements normally indicative that the subject does wish to roll
over.
[0042] In a preferred embodiment, the control means has an
operating means. The operating means preferably comprises en
activation and deactivation means. The activation and deactivation
means preferably allows the subject to turn on and off the control
means and the YES system when desired. Where the FES system is
fully implanted, the activation and deactivation means is
preferably controllable from outside the body. In one embodiment,
the activation and deactivation means can comprise a switch. Where
the control means is implanted, the system preferably can still be
operated through the skin of the subject. The operating means
preferably incorporates a locking means to prevent inadvertent
activation or deactivation.
[0043] Where implanted, an external controller can communicate with
the implanted unit using radio frequency (RF) transmissions.
[0044] According to a further aspect, the present invention is a
functional electrical stimulation system for controlling the
movement of a portion of a body of a subject comprising:
[0045] a measuring means having at least one sensor, mountable to a
walking aid, that outputs signals representative of the position
and/or movement of said walking aid when operated by a subject of
the system; and
[0046] a control means that receives and processes the signals
output by the measuring means and outputs control signals to a
stimulating means adapted to provide electrical simulation to said
body portion in response to the position and/or movement of said
walking aid determined by the measuring means.
[0047] In this aspect, the subject can learn a series of positions
and/or movements of the aid that cause pre-programmed control
signals or sequences thereof to be supplied to the stimulating
means.
[0048] In one embodiment, the walking aid can comprise a crutch or
walking stick. Placement of the crutch or stick at a particular
angle relative to vertical or its movement in a particular way can
be pre-programmed to cause stimulation of a lower limb in a manner
that allows the subject to walk. In a preferred embodiment, the
system relies on at least one measuring means mounted on respective
crutches supporting the subject. A particular movement or position
of the left crutch can be adapted to cause stimulation of the right
leg. A subsequent particular movement or position of the right
crutch can be adapted to cause stimulation of the left leg. In this
manner, a subject cam learn to walk using the FES system by
alternately moving or adjusting the position of the crutches used
to support them. In an alternative arrangement, it can be envisaged
that the subject rely on one crutch or walking stick. In this case,
variation in the position and/or movement of the aid can lead to
stimulation of the opposing leg. The adjacent leg can then be
stimulated to take a stride 180.degree. out of phase of the
opposing leg.
[0049] In this aspect, the monitoring means, control means and
stimulating means can have the features of the equivalent systems
already defined herein.
[0050] According to a still further aspect, the present invention
is a walking aid for a subject being assisted to walk using
functional electrical stimulation system, the walking aid having at
least one sensor mounted thereon that outputs signals
representative of the position and/or movement of the walking
aid.
[0051] In this aspect, the functional electrical stimulation system
can have the features of the FES system defined above.
[0052] In this aspect, the walking aid can comprise a crutch. He
crutch can comprise a tall crutch that fits under the armpits with
double uprights and a small horizontal hand bar extending between
the uprights, a Lofstrand crutch which consists of a single tube of
aluminium surrounded by a metal cuff that fits around the forearm
and has a handbar positioned proximally thereto, or a Canadian
elbow extensor crutch which is a variation of the Lofstrand crutch.
Still further, the walking aid can comprise a walking stick.
[0053] The walking aid can have an on-board power supply, such as a
rechargeable battery, that provides power to the sensor. In another
embodiment, componentry of the FES system, such as the control
means and stimulator can be mounted on or in the walking aid.
Electrical connectors can also be incorporated into the walking aid
to allow cables to extend from the componentry mounted to or in the
walking aid to the one or more transducers and/or the stimulating
electrodes.
[0054] According to a further aspect, the invention is a method of
controlling functional electrical stimulation provided to a portion
of a body of a subject, the method comprising the steps of:
[0055] measuring the position and/or movement of a portion of the
body of the subject other than said body portion; and
[0056] processing the signals and outputting electrically
stimulation to said body portion in response to the measured
position and/or movement of said other body portion.
[0057] In a preferred embodiment of this aspect, the method is
adapted to use the position and/or movement of the torso, the head,
one or both, or a combination thereof, to control the stimulation
provided to the legs of the subject. In a particularly preferred
embodiment, the position and/or movement of the torso and/or head
can be used to initiate and control a standing or sitting action of
the subject. In another embodiment, the movement of the torso
and/or head can be used to initiate stimulation of the legs that
allows the subject to roll over when in a substantially horizontal
position.
[0058] According to a still further aspect, the invention is a
method of controlling functional electrical stimulation provided to
a portion of a body of a subject, the method comprising the steps
of
[0059] measuring the position and/or movement of a walking aid
operated by the subject; and
[0060] processing the signals and outputting electrical stimulation
to said body portion in response to the measured position and/or
movement of said walking aid.
[0061] In a preferred embodiment of this aspect, the electrical
stimulation is provided to the legs of the subject to cause the
subject to walk.
[0062] In a preferred embodiment of these latter aspects, the
method includes a step of measuring the position and/or movement of
the legs and using the measurements to modify or control the
electrical stimulation generated in response to movement of the
subject's torso or walking aid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0063] By way of example only, preferred embodiments of the
invention are now described with reference to the accompanying
drawing, in which:
[0064] FIG. 1 is a sequence of drawings depicting the movement of a
subjects body from a sitting position to a standing position using
functional electrical stimulation;
[0065] FIG. 2 is a sequence of drawings depicting the movement of a
subject's body from as standing position to a sitting position
using functional electrical stimulation;
[0066] FIG. 3 is a side elevation view of one embodiment of a
walking aid according to the present invention;
[0067] FIG. 4 is a sequence of drawings depicting the gait of a
person using waking aids in concert with a functional electrical
stimulation system; and
[0068] FIG. 5 is a simplified block diagram depicting one
embodiment of a FES system according to the present invention.
PREFERRED MODE OF CARRYING OUT THE INVENTION
[0069] A FES system according to the present invention is generally
depicted as 30 in FIG. 5.
[0070] The system has a housing 31 that houses a control means 32
and a stimulator 35. A power source in the form of a rechargeable
battery 43 is also provided in the housing 31. The depicted control
means 32 receives a first set of signals through a first signal
path 33 provided by a cable 40 extending from a first transducer 60
to an electrical connector 33a on the housing 31. The transducer 60
and cable 40 are depicted schematically in FIG. 5 and are not shown
to scale. The transducer 60 is adapted to be mounted to a portion
of the body of the subject that is under the control of the
subject. For example, in the case of subject with paraplegia, the
transducer can be mounted to the upper torso of the subject.
[0071] The signals output by transducer 60 and provided through
signal path 33 represent the magnitude and type of movement of the
torso made by the subject.
[0072] While the control means 32 could rely only on the input from
transducer 60, the depicted control means 32 also receives a second
set of output signals through a second signal path 34 provided by a
cable 50 extending from a transducer 61. Transducer 61 can also be
mounted to the torso of the subject or at another location on the
subject's body. While depicted schematically in FIG. 5, the cables
40,50 can be envisaged as being a flexible cables extending between
the respective transducers 60,61 and the connectors 33a,34a of the
housing 31. The signals output by transducer 61 and provided
through signal path 34 can also represent the magnitude and type of
movement made by the portion of the subject's body to which the
transducer 61 is mounted.
[0073] In one arrangement, the control means 32 receives the first
set of output signals through the first signal path 13 from
transducer 60 when mounted to the torso of the subject and the
second set of output signals through the second signal path 34 from
transducer 61 mounted to one of the legs of the subject. While FIG.
5 depicts only one transducer providing signals through each of the
signal paths 33 and 34, more than one transducer could be utilised
to provide signals through each signal path.
[0074] The transducer 60 mounted to the torso of the subject 12
provides a signal output representative of the angle of the torso
relative to a horizontal plane and the movement of the torso. The
transducer 61 mounted to one of the legs of the subject provides a
signal output representative of the angle of the thigh of the leg
relative to a horizontal plane and the movement of the legs. When
monitoring only one leg, the control means 32 can be operated in a
manner that assumes the other leg is in a position 180.degree. out
of phase to the monitored leg, when the subject is receiving
functional electrical stimulation that results in the subject being
able to walk or move their legs in some repetitive manner, such as
rotate the pedals of an exercise bicycle.
[0075] FIG. 1 depicts one use of one embodiment of the FES system
30 depicted in FIG. 5. In FIG. 1, a simplified view of a subject 12
receiving functional electrical stimulation is depicted. In FIG.
1a, the subject 12 is shown seated on a chair 13. As shown in FIG.
1b, the subject 12 can move their torso 14 forwardly to a position
that is at a particular angle relative to a horizontal plane. The
transducer 60 mounted to the torso 14 detects this movement and
outputs signals representative of this to the control means 32. The
control means 32 on receipt of these signals in turn outputs
suitable control signals to the stimulator 35 which outputs
electrical impulses to electrodes 53 mounted to the legs 15 of the
subject 12. For reasons of clarity, the system 30 and electrodes 53
are not depicted in FIG. 1
[0076] As can be seen in FIG. 1b, as the subject 12 moves their
torso 14 forward, the lower legs of the subject 12 move backwardly.
The angle of the torso 14 controls the angle of movement of the
lower legs about the knees of the subject 12.
[0077] Once the feet of the subject 12 are in the correct position,
the subject 12 can return their torso 14 back to an upright
position as depicted in FIG. 1c. This movement leads to further
signals being output to the control means 32. Once the torso 14 is
back in an upright position, the control means 32 can output
control signals to the stimulator 15 which result in the stimulator
35 outputting a sequence of stimulation impulses to the legs 15
that result in the subject 12 moving to a standing position (see
FIGS. 1d and 1e).
[0078] FIG. 2 depicts another use of en embodiment of the FES
system 30. In these figures, the subject 12 is firstly shown
standing in front of a chair 13. On a subject 12 moving their torso
14 forward a particular desired angle, such as greater than
30.degree., and then returning to an upright position within a
predetermined time (see FIG. 2a), the transducer 60 detects this
combination of movements and outputs appropriate representative
signals to the control means 32. The control means 32 on receiving
this combination of signals, outputs control signals to the
stimulator 35 which results in the thighs of the subject 12 bending
backwardly relative to the knees (see FIG. 2b) so as to move the
subject 12 back down onto the chair 13 as depicted in FIG. 2c.
[0079] FIGS. 1 and 2 depict examples of how the FES system 30 can
be used by the subject 12 adjusting their torso to control the
movement of their dysfunctional legs.
[0080] The control means 32 is programmed to output a particular
stimulation signal sequence to the stimulator 35 on detection of a
predetermined torso position adopted by the subject 12. In this
way, the subject 12 can learn to create particular different
stimulation patterns or signal sequences by the stimulator 35 by
adopting various different torso positions.
[0081] While the use of torso orientation is depicted in FIGS. 1
and 2 for initiating a standing up or sitting down action, torso
orientation changes can also be used to initiate and maintain a
walking sequence. In another embodiment, the control means 32 can
be adapted to watch for twisting movements of the torso that axe
indicative, when the subject is laying down, that the subject
wishes to roll over. The control means can also include a timer
means that ensures the subject 12 rolls over a predetermined number
of times in a particular time period.
[0082] The transducer 61 mounted to the legs of the subject 12 can
also be utilised as a means of feeding back information to the
control means 32 following electrical stimulation of the legs by
the stimulator 35. For example, the transducer 61 can inform the
control means 32 that the stimulator 35 has or has not achieved the
outcome for the legs expected by the provided stimulation.
[0083] The control means 32 can also control the stimulation
applied by the stimulator 35 based on a comparison of angles or
orientation of the torso relative to the upper and lower leg (knee)
angle. As previously mentioned, the detected torso angle relative
to the horizontal plane can be approximated to the desired knee
angle such that the desired knee angle can be considered as a
function of the measured torso angle. The control means 32 can then
initiate appropriate signals to ensure that the actual knee angle
closely approximates that of the desired knee angle based on a
model of desired knee angles and torso angles.
[0084] The depicted control means 32 comprises a microprocessor and
includes a data storage buffer that stores measured torso movements
measured by the transducer 60 and/or leg movements resulting from
the provision of electrical stimulation thereto.
[0085] One embodiment of a crutch for use as a walking aid
according to the present invention is depicted generally as 20 in
FIG. 3. The depicted crutch comprises a standard tall crutch,
however, the present invention could also equally rely on a
Lofstrand crutch or Canadian elbow extensor crutch.
[0086] The crutch 20 has an armpit portion 21 and two double
uprights 22 that extend from the armpit portion 21 to a foot 23. A
small horizontal handbar 24 extends between the uprights 22 which
allows the subject 12 to use and support themselves on the crutch
20.
[0087] Mounted to the crutch 20 below the handbar 24 is a
transducer 25. The transducer 25 can have the same or different
features to that of transducer 60 described above. Extending from
the transducer is a cable 26. In the depicted embodiment, cable 26
is adapted to be electrically connected to connector 33a of the FES
system 30. The transducer 25 is used to provide signals to the
control means 32 in replacement of or in addition to signals
provided by transducer 60 mounted to the torso of the subject 12.
By varying the position of one or two crutches being used by the
subject 12, the subject 12 can control the stimulation pattern
output by the stimulator 35. In one example, forward movement of
the left crutch can result in a forward step of the right leg of
the subject 12 and subsequent forward movement of the right crutch
can result in a forward step of the left leg of the subject 12.
Further the control means 32 of this embodiment can determine the
distance between the subject's leg and the associated crutch and
cause the leg to be brought towards the crutch when the distance
exceeds a specific limit. By learning to appropriately move the
supporting crutches, a subject 12 can create a sequence of steps
using the FES system 30.
[0088] While FIG. 3 only depicts the transducer 25 mounted to the
crutch 20, in another embodiment, the housing 31 could be mounted
on the crutch 20.
[0089] FIG. 4 depicts a subject 12 using a walking stick in each
hand to control the FES system 30 in a manner similar to that
described for crutch 20. Walking stick 27a is in the right hand of
the subject 12 and walking stick 27b in the left band. For the
purposes of clarity, the left leg, left arm and left walking stick
27b of the subject 12 are depicted in phantom in FIG. 4.
[0090] Each waling stick 27a,27b has a transducer 25 mounted
thereon (not visible) that is used to provide signals to the
control means 32 in replacement of or in addition to signals
provided by transducer 60 mounted to the torso of the subject 12.
By varying the position of the sticks 27a,27b, the subject 12 can
control the stimulation pattern output by the stimulator 35.
[0091] In one example, forward movement of the left stick 27b can
result in a forward step of the right leg 15a of the subject 12 and
subsequent forward movement of the right stick 27a can result in a
forward step of the left leg 15b of the subject 12. As depicted in
FIG. 4b, the subject 12 has moved the left stick 27b forward which
in turn has resulted in the subjects right leg 15a stepping forward
a distance similar to or the same as that moved by the left stick
27b. Once this step is complete, the subject 12 can move the right
stick 27a forward (as depicted in FIG. 4c) which in turn leads the
FES system 30 to move the left leg 15b forward a distance similar
to or the same as that moved by the right stick 27a. By
continuously moving the sticks 27a,27b forward in alternate
fashion, the subject 12 can walk across a surface.
[0092] While the use of the sticks 27a,27b is depicted in FIG. 4 as
resulting in a walking movement of the subject 12, it will be
appreciated that other movements of one or both sticks can result
in other movements of the subject 12. For example, the lifting of
one of the sticks may cause the subject to sit or stand.
[0093] The components of the depicted FES system 30 can be fully
implanted within the subject 12. It will, however, be appreciated
that the control means 32 and other components could be external
the body of the subject 12. Electrical stimulation to the muscles
is provided, in the depicted embodiment, by electrodes 53 mounted
to the skin or implanted within the muscles identified as requiring
stimulation to achieve the movement desired when installing the
system 30. As depicted in FIG. 5, the electrodes 53 are
electrically connected by cables 54 to the output of stimulator 35
through a connector 35a on the housing 31.
[0094] As depicted in FIG. 5, the system 30 further comprises an
operating means 36 that receives signals from a transducer 37
adapted to monitor the position of another portion of the subjects
body, such as the subjects head. The transducer 37 outputs signals
through cable 38 connected to connector 39 in the housing 31. The
transducer 37 and cable 38 are not depicted to scale. More than one
such transducer 37 can also be envisaged. On receipt of a
predetermined signal from the transducer 37, the operating means
can activate or deactivate the control means 32 and/or the
stimulator 35. For is example, the transducer 37 can be mounted to
the head of the person 12, and adapted to output a predetermined
signal on determination of a particular movement of the person's
head relative to the their torso. This provides the person 12 with
a ready means to activate or deactivate the FES system 30 simply by
a predetermined movement of their head. It can be envisaged that
movement of the subject's torso 14 or the walking aid 20 held by
the person 12 could also be used to activate or deactivate the
control means 32 and/or the FES system 30.
[0095] The FES system 30 provides a relatively easier and more
natural interface for the subject 1Z to initiate a step or other
movement when compared to button presses using known touch pad
interfaces.
[0096] It will be appreciated by persons skilled in the art that
numerous variations and/or modifications may be made to the
invention as shown in the specific embodiments without departing
from the spirit or scope of the invention as broadly described. The
present embodiments are, therefore, to be considered in all
respects as illustrative and not restrictive.
* * * * *