U.S. patent application number 14/647808 was filed with the patent office on 2015-11-19 for virtually-interfaced robotic ankle & balance trainer.
This patent application is currently assigned to Northeastern University. The applicant listed for this patent is Northeastern University. Invention is credited to Amir Bahador Farjadian BEJESTAN, Alexandra BUGLIARI, Paul R. DOUCOT, Maureen HOLDEN, Nathaniel LAVINS, Constantinos MAVROIDIS, Alexander MAZZOTTA, Jan VALENZUELA.
Application Number | 20150328497 14/647808 |
Document ID | / |
Family ID | 50828505 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150328497 |
Kind Code |
A1 |
DOUCOT; Paul R. ; et
al. |
November 19, 2015 |
VIRTUALLY-INTERFACED ROBOTIC ANKLE & BALANCE TRAINER
Abstract
According to an aspect of the invention, a robotic ankle and
balance training platform comprises a footplate to support a foot.
The footplate is capable of rotation about an inversion/eversion
axis and a plantar/dorsiflexion axis. The robotic platform further
comprises an actuation system configured to apply an assistive
inversion/eversion force and a resistive inversion/eversion force
to the footplate and an assistive plantar/dorsiflexion force and a
resistive plantar/dorsiflexion force to the footplate.
Inventors: |
DOUCOT; Paul R.; (US)
; MAZZOTTA; Alexander; (US) ; BUGLIARI;
Alexandra; (US) ; LAVINS; Nathaniel; (US)
; BEJESTAN; Amir Bahador Farjadian; (US) ; HOLDEN;
Maureen; (US) ; MAVROIDIS; Constantinos;
(Arlington, MA) ; VALENZUELA; Jan; (US) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Northeastern University |
Boston |
MA |
US |
|
|
Assignee: |
Northeastern University
Boston
MA
|
Family ID: |
50828505 |
Appl. No.: |
14/647808 |
Filed: |
November 28, 2013 |
PCT Filed: |
November 28, 2013 |
PCT NO: |
PCT/US13/72444 |
371 Date: |
May 27, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61730819 |
Nov 28, 2012 |
|
|
|
Current U.S.
Class: |
482/146 |
Current CPC
Class: |
A63B 21/00181 20130101;
A63B 24/0087 20130101; A61H 1/0266 20130101; A63B 21/4034 20151001;
A63B 2022/0094 20130101; A63B 2220/805 20130101; A61H 2201/0176
20130101; A63B 21/4015 20151001; A63B 2220/52 20130101; A63B
2024/0096 20130101; A63B 2220/24 20130101; A61H 2201/5002 20130101;
A61H 2201/1215 20130101; A63B 2024/0068 20130101; A63B 24/0062
20130101; A61H 2201/5092 20130101; A61H 2201/1642 20130101; A61H
2201/5061 20130101; A63B 2071/0683 20130101; A63B 21/00178
20130101; A63B 2024/009 20130101; A63B 2071/0636 20130101; A63B
22/18 20130101; A63B 2208/0204 20130101; A61H 2201/1676 20130101;
A63B 69/0057 20130101; A63B 2071/0081 20130101; A63B 2220/16
20130101; A63B 26/003 20130101; A61B 5/1036 20130101; A63B 69/0064
20130101; A61H 2201/018 20130101; A61H 2201/1633 20130101; A63B
23/085 20130101; A63B 21/0058 20130101; A63B 23/08 20130101; A63B
71/0622 20130101; A63B 2208/0233 20130101; A63B 2024/0093 20130101;
A61H 2201/5064 20130101 |
International
Class: |
A63B 26/00 20060101
A63B026/00; A63B 23/08 20060101 A63B023/08 |
Claims
1. A robotic ankle and balance training platform comprising: a
footplate to support a foot, said footplate capable of rotation
about an inversion/eversion axis and a plantar/dorsiflexion axis;
and an actuation system configured to apply: an assistive
inversion/eversion force and a resistive inversion/eversion force
to the footplate; and an assistive plantar/dorsiflexion force and a
resistive plantar/dorsiflexion force to the footplate.
2. The robotic ankle and balance training platform of claim 1,
further comprising: an inversion/eversion frame to allow rotation
of the footplate about the inversion/eversion axis; and a
plantar/dorsiflexion frame to allow rotation of the footplate about
the plantar/dorsiflexion axis.
3. The robotic ankle and balance training platform of claim 2,
wherein one of the inversion/eversion frame and the
plantar/dorsiflexion frame are integral with the footplate.
4. The robotic ankle and balance training platform of claim 1,
further comprising: sensors for measuring at least one of tensile
force, compressive force, and footplate position.
5. The robotic ankle and balance training platform of claim 4,
wherein sensors comprise: at least one pair of load cells; and at
least one spring configured to assert a preload on the at least one
load cell pair.
6. The robotic ankle and balance training platform of claim 5,
wherein the sensors comprise two load cell pairs and two springs
and the load cells are located in the Anterior(A)/Posterior(P) and
Medial(M)/Lateral(L) planes with respect to the ankle supported on
the footplate.
7. The robotic ankle and balance training platform of claim 4,
wherein: the sensors are capable of measuring a center of pressure
on the footplate.
8. The robotic ankle and balance training platform of claim 4,
wherein: the sensors are capable of measuring at least one of the
assistive inversion/eversion force, the resistive
inversion/eversion force, the assistive plantar/dorsiflexion force,
and the resistive plantar/dorsiflexion force.
9. The robotic ankle and balance training platform of claim 1,
wherein the plantar/dorsiflexion axis is offset between
approximately 20% and 40% of a length of the footplate from an end
of the footplate.
10. The robotic ankle and balance training platform of claim 1,
further comprising: a mechanical stop to physically limit at least
one of inversion/eversion and plantar/dorsiflexion movement of the
footplate.
11. The robotic ankle and balance training platform of claim 2,
further comprising: a first pair of shafts substantially aligned
with the inversion/eversion axis, wherein capheads on the first
pair of shafts are counter sunk in the inversion/eversion frame;
and a second pair of shafts substantially aligned with the
plantar/dorsiflexion axis, wherein capheads of the second pair of
shafts are counter sunk in the plantar/dorsiflexion frame.
12. The robotic ankle and balance training platform of claim 1,
wherein the actuator system further comprises: at least one of an
inversion/eversion motor and a plantar/dorsiflexion motor.
13. The robotic ankle and balance training platform of any of
claims 12, wherein the at least one motor comprises: a pulley
assembly; a gearbox to transfer force to the footplate via the
pulley assembly.
14. The robotic ankle and balance training platform of claim 1,
further comprising: an encoder positioned to read at least one of
an inversion/eversion position of the footplate and a
plantar/dorsiflexion position of the footplate.
15. A robotic ankle and balance training device comprising: a
robotic first ankle and balance training platform according to
claim 1; a robotic second ankle and balance training platform
according to claim 1.
16. The robotic ankle and balance training device of claim 15,
further comprising: a controller for determining a desired force
for at least one of the assistive forces and the resistive forces
and instructing the actuator system of at least one of the robotic
platform to provide the desired force to the footplate of the at
least one of the robotic platforms.
17. The robotic ankle and balance training device of claims 16,
further comprising: a sliding track, wherein the sliding track is
configured to allow a distance between the first and second robotic
platforms to be adjusted.
18. The robotic ankle and balance training device of claim 14,
further comprising: a stationary platform to house the first and
second robotic platforms; a safety rail connected to the stationary
platform; a lift-assist chair to allow use of the first and second
robotic platforms in a seated or a standing position; and a virtual
reality interface configured to interface with the first and second
robotic platforms and provide feedback in response to at least one
of a footplate orientation and a force asserted by the foot.
19. The robotic ankle and balance training device of claim 18,
wherein at least one of the robotic platforms actuates in response
to at least one of the force asserted by the foot and the feedback
from the virtual reality interface.
20. The robotic ankle and balance training device of claim 18,
wherein the virtual reality interface is configured to provide
visual feedback in response to a center of pressure measurement to
at least one of the robotic platforms.
21. A method of ankle and balance training comprising: measuring a
range of motion of an ankle in at least four directions and in a
circular motion using a robotic ankle and balance training
platform; measuring a maximum exertion of the ankle in at least the
four directions using the robotic platform; determining a fatigue
point of the ankle at approximately 20% of the maximum exertion
using the robotic platform; and detecting a weight shift of a
patient using the robotic platform.
22. The method of ankle and balance training of claim 21, wherein
the weight shift is detected while a footplate of the robotic
platform is stationary.
23. The method of ankle and balance training of claim 22, wherein
the weight shift is detected while a footplate of the robotic
platform is rotating about one or more of an inversion/eversion
axis and a plantar/dorsiflexion axis.
24. A method of ankle and balance training comprising: placing a
foot on a robotic ankle and balance training platform of claim 1;
and receiving a visual feedback from a visual interface based on at
least one of an orientation of the foot on the robotic platform and
a force asserted by the foot against the robotic platform.
Description
CROSS-REFERENCE(S) TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Patent Application No. 61/730,819, filed on Nov. 28,
2012, the content of which is hereby incorporated by reference
herein in its entirety.
[0002] This patent disclosure may contain material that is subject
to copyright protection. The copyright owner has no objection to
the facsimile reproduction by anyone of the patent document or the
patent disclosure as it appears in the U.S. Patent and Trademark
Office patent file or records, but otherwise reserves any and all
copyright rights.
INCORPORATION BY REFERENCE
[0003] All patents, patent applications and publications cited
herein are hereby incorporated by reference in their entirety in
order to more fully describe the state of the art as known to those
skilled therein as of the date of the invention described
herein.
TECHNICAL FIELD
[0004] This technology relates generally to patient rehabilitation.
In particular, aspects of this invention relate to ankle
rehabilitation and balance training devices.
BACKGROUND
[0005] Due to the wide range of neurological impairments and
orthopedic ankle injuries, there is a need for a device that can
efficiently and accurately measure a patient's ankle strength and
balance abilities as well as monitor their progress throughout
therapy. There is additionally a need for a device that can be used
in stable and dynamic operational modes and can utilize a virtual
reality user interface for the training exercises. There is further
a need for a device that can be controlled in real-time, can vary
assistive and resistive forces, and analyze and provide feedback on
patient performance. There is also a need for a device with
diagnostic and rehabilitative capabilities.
[0006] As such, an object of one or more embodiments of the
invention is to provide a robotic ankle rehabilitation device that
will help patients improve their ankle balance and strength. A
further object of one or more embodiments of the invention is to
provide a device that can be robotically controlled, can
incorporate a virtual reality user interface, and can provide
diagnostic capabilities as well as objective feedback at a lower
cost than its competitors. An additional object of one or more
embodiments of the invention is to provide a device that can
efficiently and accurately measure a patient's ankle strength and
balance abilities as well as monitor their progress throughout
therapy. A further object of one or more embodiments of the
invention is to provide a device that can be used in stable and
dynamic operational modes and can utilize a virtual reality user
interface for the training exercises. An additional object of one
or more embodiments of the invention is to provide a device that
can be controlled in real-time, can vary assistive and resistive
forces, and can analyze and provide feedback on patient
performance. It is also an object of one or more embodiments of the
invention to provide a device with diagnostic and rehabilitative
capabilities.
SUMMARY
[0007] According to an aspect of the invention, a robotic ankle and
balance training platform comprises a footplate to support a foot.
The footplate is capable of rotation about an inversion/eversion
axis and a plantar/dorsiflexion axis. The robotic platform further
comprises an actuation system configured to apply an assistive
inversion/eversion force and a resistive inversion/eversion force
to the footplate and an assistive plantar/dorsiflexion force and a
resistive plantar/dorsiflexion force to the footplate.
[0008] According to one or more embodiments of the invention, the
robotic ankle and balance training platform further comprises an
inversion/eversion frame to allow rotation of the footplate about
the inversion/eversion axis; and a plantar/dorsiflexion frame to
allow rotation of the footplate about the plantar/dorsiflexion
axis. According to further embodiments, the inversion/eversion
frame and the plantar/dorsiflexion frame are integral with the
footplate. In still further embodiments of the invention, the
robotic ankle and balance training platform includes sensors for
measuring at least one of tensile force, compressive force, and
footplate position. In one or more additional embodiments, the
sensors comprise at least one pair of load cells; and at least one
spring configured to assert a preload on the at least one load cell
pair. In a further embodiment of the invention, the sensors
comprise two load cell pairs and two springs and the load cells are
located in the Anterior(A)/Posterior(P) and Medial(M)/Lateral(L)
planes with respect to the ankle supported on the footplate. In
additional embodiments of the invention, the robotic ankle and
balance training platform includes the sensors are capable of
measuring a center of pressure on the footplate. In one or more
additional embodiments of the invention, the ankle and balance
training platform includes sensors are capable of measuring at
least one of the assistive inversion/eversion force, the resistive
inversion/eversion force, the assistive plantar/dorsiflexion force,
and the resistive plantar/dorsiflexion force. In one or more
embodiments of the invention, the plantar/dorsiflexion axis is
offset between approximately 20% and 40% of a length of the
footplate from an end of the footplate. In further embodiments of
the invention, the robotic ankle and balance training platform of
any of further includes a mechanical stop to physically limit at
least one of inversion/eversion and plantar/dorsiflexion movement
of the footplate. In additional embodiments of the invention, the
robotic ankle and balance training platform further comprises a
first pair of shafts substantially aligned with the
inversion/eversion axis, wherein capheads on the first pair of
shafts are counter sunk in the inversion/eversion frame; and a
second pair of shafts substantially aligned with the
plantar/dorsiflexion axis, wherein capheads of the second pair of
shafts are counter sunk in the plantar/dorsiflexion frame. In
additional embodiments of the invention, the actuator system
further comprises at least one of an inversion/eversion motor and a
plantar/dorsiflexion motor. In still one or more additional
embodiments of the invention, the robotic ankle and balance
training platform includes a pulley assembly; a gearbox to transfer
force to the footplate via the pulley assembly. In one or more
additional embodiments of the invention, the robotic ankle and
balance training platform further includes an encoder positioned to
read at least one of an inversion/eversion position of the
footplate and a plantar/dorsiflexion position of the footplate.
[0009] According to a further aspect of the invention, a robotic
ankle and balance training device can include a first robotic ankle
and balance training platform according to any of the previous
embodiments and a second robotic ankle and balance training
platform according to any of claims 1-14. In one or more
embodiments of the invention, the robotic ankle and balance
training device additionally includes a controller for determining
a desired force for at least one of the assistive forces and the
resistive forces and instructing the actuator system of at least
one of the robotic platform to provide the desired force to the
footplate of the at least one of the robotic platforms. In further
embodiments of the invention, the robotic ankle and balance
training device further comprises a sliding track, wherein the
sliding track is configured to allow a distance between the first
and second robotic platforms to be adjusted. Additionally, in one
or more additional embodiments of the invention, the robotic ankle
and balance training device further includes a stationary platform
to house the first and second robotic platforms; a safety rail
connected to the stationary platform; a lift-assist chair to allow
use of the first and second robotic platforms in a seated or a
standing position; and a virtual reality interface configured to
interface with the first and second robotic platforms and provide
feedback in response to at least one of a footplate orientation and
a force asserted by the foot. In further embodiments of the
invention, at least one of the robotic platforms actuates in
response to at least one of the force asserted by the foot and the
feedback from the virtual reality interface. In additional
embodiments of the invention, the virtual reality interface is
configured to provide visual feedback in response to a center of
pressure measurement to at least one of the robotic platforms.
[0010] According to an additional aspect of the invention, method
of ankle and balance training comprises measuring a range of motion
of an ankle in at least four directions and in a circular motion
using a robotic ankle and balance training platform; measuring a
maximum exertion of the ankle in at least the four directions using
the robotic platform; determining a fatigue point of the ankle at
approximately 20% of the maximum exertion using the robotic
platform; and detecting a weight shift of a patient using the
robotic platform. In one or more further embodiments, the weight
shift is detected while a footplate of the robotic platform is
stationary. In one or more additional embodiments, the weight shift
is detected while a footplate of the robotic platform is rotating
about one or more of an inversion/eversion axis and a
plantar/dorsiflexion axis.
[0011] According to a further aspect of the invention, a method of
ankle and balance training comprises placing a foot on a robotic
ankle and balance training platform any of the preceding
embodiments and receiving a visual feedback from a visual interface
based on at least one of an orientation of the foot on the robotic
platform and a force asserted by the foot against the robotic
platform.
[0012] These and other aspects and embodiments of the disclosure
are illustrated and described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Aspects and embodiments of the invention are described with
reference to the following figures, which are presented for the
purpose of illustration only and are not intended to be
limiting.
[0014] In the Drawings:
[0015] FIG. 1 shows an Overall Virtually-Interfaced Robotic Ankle
and Balance Trainer System Design according to one or more
embodiments of the invention.
[0016] FIG. 2 shows a conceptual illustration of a robotic platform
in accordance with one or more embodiments of the invention.
[0017] FIG. 3 shows a linear actuator utilizing vertical
orientation in accordance with one or more embodiments of the
invention.
[0018] FIG. 4 shows linear actuation providing motion in 2 Degrees
of Freedom (DOF) using lever arms in accordance with one or more
embodiments of the invention.
[0019] FIG. 5 shows a view of the footplate assembly using rotary
motors to provide motion in 2 Degrees of Freedom (DOF) in
accordance with one or more embodiments of the invention.
[0020] FIG. 6 shows a platform according to one or more embodiments
of the invention.
[0021] FIG. 7 shows a platform using a vertical motor and universal
joint drive system according to one or more embodiments of the
invention.
[0022] FIG. 8 shows a platform using a half-gear mounted underneath
a footplate according to one or more embodiments of the
invention.
[0023] FIG. 9 shows a platform using a partial gear design and
right angle gearbox according to one or more embodiments of the
invention.
[0024] FIG. 10 shows a front-left view of a robotic platform
according to one or more embodiments of the invention.
[0025] FIG. 11 shows a rear-right view of a robotic platform
according to one or more embodiments of the invention.
[0026] FIG. 12 shows a robotic platform in an actuated position
(plantarflexion and inversion) according to one or more embodiments
of the invention.
[0027] FIG. 13 shows an isometric view of a footplate assembly
according to one or more embodiments of the invention.
[0028] FIG. 14 shows a top view of the footplate assembly according
to one or more embodiments of the invention.
[0029] FIG. 15 shows an isometric view of the footplate assembly
according to one or more embodiments of the invention.
[0030] FIG. 16 shows a close-up of the peak-stress location on the
footplate assembly according to one or more embodiments of the
invention.
[0031] FIG. 17 show an inversion/eversion mechanical stop according
to one or more embodiments of the invention.
[0032] FIG. 18 shows a plantar/dorsiflexion mechanical stop
according to one or more embodiments of the invention.
[0033] FIG. 19 shows a track in accordance with one or more
embodiments of the invention.
[0034] FIG. 20 shows an example of a safety harness, which can be
used in accordance with one or more embodiments of the
invention.
[0035] FIG. 21 shows a safety railing setup with a patient seated
in a chair in accordance with one or more embodiments of the
invention.
[0036] FIG. 22 shows a safety railing setup with a patient standing
out of a chair in accordance with one or more embodiments of the
invention.
[0037] FIG. 23 shows an example of a chair base with a hydraulic
foot pump in accordance with one or more embodiments of the
invention.
[0038] FIG. 24 shows exemplary design flex calculations for one or
more embodiments of the invention.
[0039] FIG. 25 shows a 3D CAD image of an exemplary robotic
platform support frame according to one or more embodiments of the
invention.
[0040] FIG. 26 shows an image of an interior frame with both
rotating frame sub-assemblies according to one or more embodiments
of the invention.
[0041] FIG. 27 shows an image of the interior frame
inversion/eversion sub-assembly according to one or more
embodiments of the invention.
[0042] FIG. 28 shows an image of an interior frame
plantar/dorsiflexion frame sub-assembly according to one or more
embodiments of the invention.
[0043] FIG. 29 shows an image of plantar/dorsiflexion pulley and
timing belt assembly according to one or more embodiments of the
invention.
[0044] FIG. 30 shows a LabVIEW Control System for
Plantar/dorsiflexion axis according to one or more embodiments of
the invention.
[0045] FIG. 31 shows a block diagram representing flow of
information from the user's hand to the footplate according to one
or more embodiments of the invention.
[0046] FIG. 32 shows a LabVIEW control window according to one or
more embodiments of the invention.
[0047] FIG. 33 shows deformation due to loading on the ball of the
foot on a resized frame according to one or more embodiments of the
invention.
[0048] FIG. 34 shows cap heads of shafts counter sunk into a frame
according to one or more embodiments of the invention.
[0049] FIG. 35 shows load cell placement according to one or more
embodiments of the invention.
[0050] FIG. 36 shows a crossbar for mounting the load cells and
springs according to one or more embodiments of the invention.
[0051] FIG. 37 shows a "Sandwich" design to preload load cells
according to one or more embodiments of the invention.
[0052] FIG. 38 shows a cover for an inversion/eversion encoder
according to one or more embodiments of the invention.
[0053] FIG. 39 shows an inversion/eversion motor cover according to
one or more embodiments of the invention.
[0054] FIG. 40 shows a slanted cover design according to one or
more embodiments of the invention.
[0055] FIG. 41 shows a front view of platform and railings
according to one or more embodiments of the invention.
[0056] FIG. 42 shows rear view of platform and railings according
to one or more embodiments of the invention.
[0057] FIG. 43 shows a CAD design for a bench according to one or
more embodiments of the invention.
[0058] FIG. 44 shows an embodiment of the invention comprising
robotic platforms.
[0059] FIG. 45 shows a robotic force-plate according to one or more
embodiments of the invention.
[0060] FIG. 46 shows a force-plate structure in accordance with one
or more embodiments of the invention.
[0061] FIG. 47 shows a mechanism of tensile force measurement in
accordance with one or more embodiments of the invention.
[0062] FIG. 48 shows a flow chart representing an exemplary
collection of load cell data in accordance with one or more
embodiments of the invention
[0063] FIG. 49 shows load cell calibration characteristics in
accordance with one or more embodiments of the invention.
DETAILED DESCRIPTION
[0064] FIG. 1 shows a view of a Virtually-Interfaced Robotic Ankle
and Balance Trainer system 100 according to one or more embodiments
of the invention. According to one or more embodiments, the ankle
and balance trainer system can include a stationary platform 101,
which can house two robotic platforms 202. The robotic platforms
include footplates for accommodating one or both feet of the user.
Embodiments of the invention can also include safety features 103
and a lift-assist chair device 104. The robotic platforms 102 can
move in inversion/eversion and plantarflexion/dorsiflexion motions.
The two robotic platforms 102 can provide balance training as well
as assistive and resistive exercise modules. The platform 101 can
have extra room around the robotic platforms 102 so a patient can
step forward or backward while using the robotic platforms 102 to
exercise. The safety harness can be used on patients that are
training in the standing position and risk falling during exercise
due to poor balance. The safety railings can be in place for
patients to use during sitting or standing for extra support if
needed. The chair device 104 can provide the ability for the
patient to train in the seated position and can have a lift assist
device that can change the angle of the patient's position. The
system can also include a computer-based controller with a data
acquisition system and a motor control system that can calculate
forces experienced during use and provide the desired resistive and
active forces of the system. A description of each of these
features according to one or more embodiments of the invention is
described below.
Robotic Platform
[0065] FIG. 2 shows a conceptual illustration of a robotic platform
201 showing patient position in accordance with one or more
embodiments of the invention. In one or more embodiments of the
invention, a two degrees of freedom system can be provided that can
provide and withstand torque for assisting or resisting a patient's
motion during exercises. One or both footplates can be used for
training purposes. In one or more embodiments, the robotic platform
of the ankle and balance trainer system can include mechanical
stops that restrict the range of motion of the footplate for
balance training and diagnostics. One or more embodiments of the
invention can also include features to the reduce cost and/or the
size of a device.
[0066] In one or more embodiments, the height of the robotic
platform can be ten inches or less, which can advantageously keep
the height close to that of the average stair step. Many potential
users of the ankle and balance trainer system in accordance with
embodiments of the invention will be neurologically impaired, so
situating oneself on the machine should be as easy as possible.
[0067] In one or more embodiments the robotic platform includes a
multicomponent footplate in which an inner component provides a
support for the user's foot as well as plantar/dorsiflexion (PFDF)
about an axis, and an outer component provides inversion/eversion
(INEV) about a separate axis. In further embodiments of the
invention, the inner component can provide inversion/eversion about
an axis and an outer component can provide plantar/dorsiflexion
about a separate axis.
[0068] In one or more embodiments of the invention, a pulley-timing
belt system can be used to drive the desired inversion/eversion and
plantar/dorsiflexion motion. A belt and pulley can be selected
based on the horsepower of the motor, speed of the shaft, and
maximum torque output desired. Also, in one or more embodiments of
the invention, the ratio of the pulleys can be 1:1 because the
torque multiplication and speed reduction in certain embodiments
can be sufficient from the gearbox alone. In other embodiments,
other ratios can be used. In one or more embodiments of the
invention, a contained gearbox assembly can be used to provide safe
and reliable transfer of rotation to a footplate via the pulley and
timing belt assembly.
[0069] FIG. 10, FIG. 11, and FIG. 12 show views of one or more
embodiments of the invention, which can include a robotic
footplate, where pulley and timing belt assemblies can be used for
the inversion/eversion and plantar/dorsiflexion axes of rotation.
FIG. 10 shows a front-left view of a robotic platform 1200
according to one or more embodiments of the invention, in which
robotic footplate 1200 can comprise a footplate assembly 1201,
including an inner footplate 1202 and an outer footplate 1203,
shafts 1204, which can interface the inner footplate 1202 and the
outer footplate 1203, a frame 1205, shafts 6806, which can
interface the outer footplate 1203 and the frame 1205, and pulley
and timing belt assemblies 1207, including belts 1208 and pulleys
1209, and can include gearbox assemblies 1211, which can
independently transfer inversion/eversion and plantar/dorsiflexion
rotation to footplates 1202 and 1203 via the pulley and timing belt
assemblies 1207. As shown in FIG. 10, the shafts 1204 can be
located substantially along an inversion/eversion axis and the
inner footplate 1202 can rotate about an inversion/eversion axis.
Further, as shown in FIG. 10, the shafts 1206 can be located
substantially along a plantar/dorsiflexion axis and the outer
footplate 1203 can rotate about a plantar/dorsiflexion axis.
Additionally, as shown in FIG. 10, a robotic footplate 1200 can
include bearings 1210 in which shafts 1206 can rotate. In further
embodiments of the invention, an inner footplate can provide
plantar/dorsiflexion rotation and an outer footplate can provide
inversion/eversion rotation. Additionally, in further embodiments
of the invention, shafts can interface an inner footplate with an
outer footplate substantially along a plantar/dorsiflexion axis and
other shafts can interface an outer footplate with a frame
substantially along an inversion/eversion axis.
[0070] FIG. 11 shows a rear-right view of a robotic platform 1300
according to one or more embodiments of the invention, in which
robotic footplate 1300 can comprise a footplate assembly 1301,
including an inner footplate 1302 and an outer footplate 1303,
shafts 1304, which can interface the inner footplate 1302 and the
outer footplate 1303, a frame 1305, shafts 1306, which can
interface the outer footplate 1303 and the frame 1305, and pulley
and timing belt assemblies 1307, including belts 1308 and pulleys
1309, and can include gearbox assemblies 1311, which can
independently transfer inversion/eversion and plantar/dorsiflexion
rotation to footplates 1302 and 1303 via the pulley and timing belt
assemblies 1307. As shown in FIG. 11, a gearbox assembly 1311 can,
for example, be attached to footplate assembly 1301 to transfer
inversion/eversion force and another gearbox assembly 1311 can, for
example, be mounted to a frame 1305 to transfer
plantar/dorsiflexion force. As shown in FIG. 11, the shafts 1304
can be located substantially along an inversion/eversion axis and
the inner footplate 1302 can rotate about an inversion/eversion
axis. Further, as shown in FIG. 11, the shafts 1306 can be located
substantially along a plantar/dorsiflexion axis and the outer
footplate 1303 can rotate about a plantar/dorsiflexion axis. As
noted previously, other in other embodiments of the invention,
different configurations can be used and different components can
provide inversion/eversion and/or plantar/dorsiflexion motion.
[0071] FIG. 12 shows a robotic platform 1400 in an actuated
position (plantarflexion and inversion) according to one or more
embodiments of the invention, in which robotic footplate 1400 can
comprise a footplate assembly 1401, including an inner footplate
1402 and an outer footplate 1403, shafts 1404, which can interface
the inner footplate 1402 and the outer footplate 1403, a frame
1405, shafts 1406, which can interface the outer footplate 1403 and
the frame 1405, and pulley and timing belt assemblies 1407,
including belts 1408 and pulleys 1409, and can include gearbox
assemblies 1411, which can independently transfer
inversion/eversion and plantar/dorsiflexion rotation to footplates
1402 and 1403 via the pulley and timing belt assemblies 1407. As
shown in FIG. 12, a gearbox assembly 1411 can, for example, be
attached to footplate assembly 1401 to transfer inversion/eversion
force and another gearbox assembly 1411 can, for example, be
mounted to a frame 1405 to transfer plantar/dorsiflexion force. As
shown in FIG. 12, the shafts 1404 can be located substantially
along an inversion/eversion axis and the inner footplate 1402 and
can rotate about an inversion/eversion axis. Further, as shown in
FIG. 12, the shafts 1406 can be located substantially along a
plantar/dorsiflexion axis and the outer footplate 1403 can rotate
about a plantar/dorsiflexion axis. As noted previously, other in
other embodiments of the invention, different configurations can be
used and different components can provide inversion/eversion and/or
plantar/dorsiflexion motion.
[0072] In one or more embodiments of the invention, the
plantar/dorsiflexion axis can be located between approximately 20%
to 40% of the length of a platform, and preferably at approximately
33% of the length of the platform. Such placement can improve
alignment of the plantar/dorsiflexion axis with alignment of an
ankle joint. In one or more embodiments of the invention, the
inversion/eversion axis can be located at approximately 50% of the
width of the platform. In other embodiments, the
plantar/dorsiflexion axis and the inversion/eversion axis can be
located in other locations along the platform.
[0073] The use of a pulley and timing belt assembly for
plantar/dorsiflexion axis in certain embodiments has several
potential advantages. First, it can reduce cost. The cost of a
right-angle gearbox can be significantly higher than the cost of an
in-line gearbox with the same ratio. In addition, the weight and
the lead time can be higher for a right-angle gearbox because, at
times, they are in less demand. Another advantage of a pulley and
timing belt assembly can be to provide a more compact robotic
footplate assembly. By choosing an in-line gearbox, the size of the
motor/gearbox combination can be smaller and can be fit underneath
the footplate. This can provide a simpler design for certain
embodiments, as well an easier allocation of space for lateral
adjustment of the robotic footplates on rails in certain
embodiments.
[0074] In one or more embodiments of the invention, the design can
advantageously minimize the weight of the footplate. In certain
embodiments, a single slab of aluminum can be used, but the weight
can be high and the weight may not be warranted for purposes of
rigidity. As such, in certain embodiments, the footplate can be
assembled as four pieces of aluminum that create an inner frame
with two aluminum bars that go across for supporting an acrylic
piece that can rest on top of that. Acrylic can be significantly
lighter than aluminum and can provide a relatively high rigidity.
Two support beams can be added to ensure minimal deflection in the
plate with a weight of one patient (300 lbs.) on a single
plate.
[0075] FIG. 6 shows a view of a robotic platform 600 according to
one or more embodiments of the invention. In FIG. 6, the robotic
platform 600 can comprise a footplate 601, including an inner
component 602 providing plantar/dorsiflexion about a
plantar/dorsiflexion axis and an outer component 603 providing
inversion/eversion about an inversion/eversion axis. The inner
component 602 can interface with the outer component 603 with
shafts 604, and the outer component 603 can interface with the
frame 605 with shafts 606. The robotic platform 600 can further
include bearings 610 in which shafts 604 and 606 can rotate. The
robotic platform 600 can additionally include motors 609, a drive
shaft 607, and a linkage-shaft 608.
[0076] When the link such as a linkage-shaft 608 is further from an
axis such as a plantar/dorsiflexion axis, the link may travel
further but may use less force to provide torque. By contrast, when
a link is closer to an axis, the link may travel less, but may use
greater force. In one or more embodiments of the invention, the
plantar/dorsiflexion motion can, for example, be at least
50.degree. plantarflexion and 20.degree. dorsiflexion. As such, in
one or more embodiments of the invention, the front of the inner
footplate can, for example, travel a total of about 9.25 inches
downward and 4 inches upward. To permit a desired range of motion
for a platform about the plantar/dorsiflexion axis and the
inversion/eversion axis, in one or more embodiments of the
invention, motors and links controlling plantar/dorsiflexion and
inversion/eversion motion can be located to avoid interfere.
[0077] Additionally, since it may be desirable in some embodiments
for plantar/dorsiflexion torque to be higher than
inversion/eversion torque, one or more embodiments of the invention
can use a direct drive system. For example, FIG. 7 shows a view of
an embodiment of the invention in which a robotic platform 700 can
comprise a footplate 701, including an inner component 702
providing inversion/eversion about an inversion/eversion axis and
an outer component 703 providing plantar/dorsiflexion about a
plantar/dorsiflexion axis. The inner component 702 can interface
with the outer component 703 with shafts 704, and the outer
component 704 can interface with to the frame 705 with shafts 706.
The robotic platform 700 can further include bearings 710 in which
shafts 704 and 706 can rotate. The robotic platform 700 can
additionally include motors 709, a drive shaft 707, and a
linkage-shaft 708, and a high-torque universal joint 711.
[0078] In another alternative embodiment of the invention, a
partial gear such as a half gear can be secured underneath a
footplate driven by a gear attached to a motor shaft. Gears can be
used to increase torque and/or reduce speed. Depending on gear
ratios, an input speed from a motor can be multiplied by an
increase factor the output torque sees from the input torque. In
many embodiments, a footplate speed of 50 rpm can be sufficient.
FIG. 8 shows a view of an embodiment of the invention in which
robotic footplate 1000 can comprise a footplate assembly 1001,
including an inner component 1002 and an outer component 1003,
shafts 1004, a frame 1005, shafts 1006, and a partial gear 1007
secured underneath the footplate assembly 1001 and driven by a gear
1008 attached to a motor shaft 1009. The inner footplate component
1002 can interface with the outer footplate component 1003 with
shafts 1004, and the outer footplate component 1003 can interface
with to the frame 1005 with shafts 1006. The robotic platform 1000
can further include bearings 1010 in which shafts 1006 can rotate.
In one or more embodiments of the invention, a larger partial gear
1007 can be used, cutting off more than half of partial gear 1007,
such that an imaginary pivot center of half gear 1007 lines up with
a desired inversion/eversion axis of the footplate. This
modification can increase the axis of rotation for
inversion/eversion, which might otherwise be undesirably low. In
one or more embodiments, bearings are selected to provide a larger
range of motion so as to permit the partial gear 1007 and the gear
1008 to maintain full contact with each other when the outer
footplate 1003 sees plantar/dorsiflexion. However, in an
alternative embodiment depicted in FIG. 8, when the footplate is
plantar/dorsiflexed and also begins inversion/eversion rotation, it
is possible for the gear 1007 to disengage from the drive gear
1008.
[0079] In one or more embodiments, an inversion/eversion movement
can use a partial gear, such as a half-gear or a third-gear,
attached to the inversion/eversion axis on the rear of the
footplate for inversion/eversion and can include a drive-gear/motor
assembly mounted to the footplate for plantar/dorisflexion. FIG. 9
shows a view of an embodiment of the invention in which the robotic
footplate 1100 can comprise a footplate assembly 1101, including an
inner footplate 1102 and an outer footplate 1103, shafts 1104, a
frame 1105, shafts 1106, and a partial gear 1107 attached to an
inversion/eversion axis on the rear of the footplate 1101 and
driven by a gear 1108 attached to a drive-gear/motor assembly 1109
mounted to the footplate assembly 1101. The inner footplate 1102
can interface with the outer footplate 1103 with shafts 1104, and
the outer layer 1103 can interface with to the frame 1105 with
shafts 1106. The robotic platform 1100 can further include bearings
1110 in which shafts 1106 can rotate. The robotic platform 1100 can
additionally include a right angle gearbox 1111 to drive motion
about the plantar/dorsiflexion axis.
[0080] There are several benefits to embodiments as depicted in
FIG. 9 that were not provided in previous designs. For example, the
motor 1109 can be situated in an open housing where it can sit on
two brackets and have two brackets above it. The brackets above the
motor 1109 can serve the purpose of a mechanical stop on the
inversion/eversion axis to prevent over-rotation, which can help
reduce risk of injury to a patient or user. An additional advantage
of mounting a motor to the underside of a footplate as, for
example, shown in FIG. 9, can be that it can prevent potential
issues with a drive gear and a half gear disengaging by allowing a
motor and a drive gear to move with plantar/dorsiflexion
rotation.
[0081] In one or more embodiments of the invention, a partial gear
can be approximately one-third of a gear. Using a partial gear such
as a one-third gear can allow for over-rotation such that the drive
gear disengages from the one-third gear to prevent the motor from
continuously applying torque when the footplate cannot rotate any
farther. In one or more embodiments, safety can be further enhanced
by advantageously including a mechanical safety that can deactivate
the motor in the event that this disengagement happens. In certain
embodiments, the ratio from the drive gear to a partial gear, such
as a one third gear, can be 1:1. In further embodiments, other gear
ratios can be used.
[0082] In one or more alternative embodiments of the invention,
linear actuators can provide direct force on the plate to provide
the desired resistive and active forces. In one or more embodiments
of the invention, linear actuators can be placed adjacent to the
footplate and lever arms can be used to transfer force. FIG. 3
shows an embodiment of the invention that can include two vertical
linear actuators 301 per footplate 302 to control
plantarflexion/dorsiflexion and inversion/eversion, respectively.
The amount of space below the footplate is reduced to provide a
desired height by having the linear actuators 301 oriented
vertically at the side of the footplate 302. Lever arms 303 provide
the mechanical connection between the linear actuator and the
footplate.
[0083] FIG. 4 shows a side perspective view of the vertically
displaced linear actuation to illustrate the motion in 2 Degrees of
Freedom (DOF) at the footplane. The motion is achieved using lever
arms 403, which apply a pivoting force about a pivot point 404.
Advantage of such embodiments of the invention can include
improving the force applied from actuators 401 (not shown) to the
footplate 402 utilizing the lever principle. However, since the
levers can serve as the means to transmit the force from the
actuator 401 (not shown) to the footplate 402, the lever arms 402
should generally be rigid enough to withstand significant force.
Additionally, since it may be desirable to be able to adjust the
stance width, the actuators 401 should generally be fixed to
something that can be adjusted to different horizontal positions
and that can withstand the reaction force.
[0084] In one or more alternative embodiments of the invention,
rotary motors can provide force used to provide the desired
resistive and active forces of the system. Rotary motors can offer
a compact source of motion because they are generally rotational,
whereas the motion of linear actuators is generally linear. One or
more alternative embodiments of the invention can use direct drive
to drive two axes of rotation directly from a drive shaft of each
of two rotary motors.
[0085] In one or more embodiments of the invention, torque output
can be converted from a drive shaft to a linear motion by use of a
linkage-shaft attachment. FIG. 5 shows a view of the footplate
assembly, including a footplate 501, using rotary motors 502 to
provide motion in 2 DOF in accordance with one or more embodiments
of the invention. Torque output can be converted from a drive shaft
503 to a linear motion by use of a linkage-shaft attachment 504. An
advantage of such embodiments can be that the force, if applied at
the edge of the footplate 501, can act over a moment arm that can
be a distance from the shaft contact with the footplate 501 to the
axis of rotation. This can effectively multiply the force over that
distance. The drive shafts 503 of the motors 502 can be connected
to one end of a linkage that can transfer force to a vertical shaft
attached to the footplate. The base of the footplate 501 can also
seated on a ball joint 505 atop a support structure 506 that can
allow for a wide range of motion. The motors 502 can be oriented on
a base plate 507 and connected to the footplate 501. Each motor 502
can provide motion in 1 DOF, such that the combination of motors
can provide inversion/eversion and plantarflexion/dorsiflexion
forced motion. The support structure 506 can minimize direct force
on the shafts 504 driving motion, which can allow for more
efficient transfer of force from the motors 502. In such
embodiments of the invention, it may be desirable for the motors
502 to provide force to the foot plate 501 while keeping the
overall size of the system small. In this alternative embodiment,
an input torque from a motor can, for example, be 50 N-m along with
a crank arm of 0.0762 meters and a footplate moment arm of 0.1016
meters, and the upper end of the footplate angle can, for example,
have approximately 30 N-m of applied torque.
[0086] For certain applications, it may be desirable for a robotic
platform to provide enough force to counter act a patient's weight,
while still providing a desired minimum range of motion for
exercises. According to one or more embodiments of the invention, a
footplate can rest on a ball joint and motion can be provided with
two motors, as described, for example, with reference to FIG.
5.
Stress Analysis of Exemplary Robotic Platform Components
[0087] FIGS. 13-15 show further views of one or more embodiments of
the invention. FIG. 13 shows an isometric view of a footplate
assembly 1501 according to one or more embodiments of the
invention. The footplate assembly 1501 can include an inner
footplate 1502 and an outer footplate 1503, links 1504 interfacing
the inner footplate 1502 and the outer footplate 1503, a frame 1505
(not shown), and links 1506 interfacing the outer footplate 1503
and the frame 1505 (not shown). FIG. 14 shows a top view of a
footplate assembly 1601 according to one or more embodiments of the
invention. The footplate assembly 1601 can include an inner
footplate 1602 and an outer footplate 1603, links 1604 interfacing
the inner footplate 1602 and the outer footplate 1603, a frame 1605
(not shown), and links 1606 interfacing the outer footplate 1603
and the frame 1605 (not shown). Based on testing an embodiment of
the invention, a maximum deflection can occur, for example, at the
location of the peak force 1507 and 1607 shown in FIG. 13 and FIG.
14, respectively. The maximum deflection can, for example, be
approximately 0.275 millimeters in one or more embodiments of the
invention. In an embodiment, the maximum allowable deflection that
would be noticed by a user can, for example, be 2 millimeters. It
can be desirable that a patient not feel deflection of the
footplate under his/her weight and not experience a loss of
confidence in the safety of a device. Since one or more embodiments
of the invention can be used as medical devices and with patients
experiencing balance issues, it can be desirable for a plate
assembly to be strong enough to make the users feel comfortable and
safe. With certain embodiments having, for example, 0.27 mm as the
maximum deflection, these embodiments can, for example, provide a
Factor of Safety (SF) of 7.4.
[0088] Stresses experienced in an embodiment of the footplate
assembly were also assessed. FIG. 15 shows an isometric view of an
footplate assembly 1701 according to one or more embodiments of the
invention. The footplate assembly 1701 can include an inner
footplate 1702 and an outer footplate 1703, links 1704 interfacing
the inner footplate 1702 and the outer footplate 1703, a frame 1705
(not shown), and links 1706 interfacing the outer footplate 1703
and the frame 1705 (not shown). FIG. 16 shows a close-up of an
example of a peak-stress location on a footplate assembly according
to one or more embodiments of the invention. The footplate assembly
1801 can include an inner footplate 1802 and an outer footplate
1803, links 1804 (not shown) between the inner footplate 1802 and
the outer footplate 1803, a frame 1805 (not shown), and links 1806
between the outer footplate 1803 and the frame 1805 (not shown). In
an embodiment of the invention, the majority of the footplate
assembly, as shown in 17, can, for example, experience less than
10.6 MPa. The location of peak-stress can occur in an embodiment of
the invention, for example, on an AISI 1566 steel drive shaft as
shown in 18 with a value of 47.6 MPa. In an embodiment of the
invention, the allowable stress for acrylic, which can be the
material of the center of the footplate, can, for example, be 48
MPa, and since the stress it experiences can be less than 10.6 MPa,
such that the FS can, for example, be about 4.6 for this
embodiment. For aluminum 6061, which can be the majority of the
footplate assembly in this embodiment, the allowable stress can,
for example, be 172.4 MPa, such that the FS can, for example, be 16
in this embodiment. Finally, a location of peak-stress can, for
example, use AISI 1566 steel in an embodiment of the invention,
which can, for example, have an allowable stress of 2.07 Gpa this
embodiment. This means the FS can, for example, be 43.5 in this
embodiment. However, a shaft can, for example, be 0.75 inch
diameter in an embodiment of the invention due to high torque. The
calculation for the shaft diameter can be based on the allowable
stress of the shaft material and the applied torque in an
embodiment of the invention.
.sigma. = TD 21 ##EQU00001## I = .pi. D * 32 ##EQU00001.2##
[0089] These two equations can be substituted into each other and
simplified, with the diameter isolated. The following equation can
result:
D = T .times. 16 .pi..sigma. s ##EQU00002##
[0090] For example, using 2.07 GPa as an allowable stress and a
torque of 210 Nm, in an embodiment of the invention, one such
appropriate diameter can be found to be 0.008 meters, or 0.315
inches certain embodiments. The chosen shaft diameter can, for
example, be 0.75 inches in an embodiment of the invention, which
means there can, for example, be an FS of 2.38 in this embodiment.
In certain embodiments, this can be a more realistic FS than, for
example, 43.5 for the static analysis. If an embodiment were only
experiencing static loads, then the shaft diameter could be much
smaller, but since the limiting factor in this embodiment can be
the stress produced by the dynamic torque, this calculation can be
used to decide a shaft diameter in this embodiment.
Mechanical Stops
[0091] One or more embodiments of the invention can include safety
precautions such as mechanical stops, which can be located
underneath the footplate. Mechanical stops can act as a limiter to
prevent over rotation of the footplate. In one or more embodiments
of the invention, for example, the maximum rotation on the
inversion/eversion axis can be 40.degree. of rotation. Mechanical
stops can be included in case the control system fails to stop the
user at 40.degree.. In other embodiments, the maximum rotation on
the inversion/eversion axis can be greater than 40.degree. of
rotation, and in still other embodiments, the maximum rotation on
the inversion/eversion axis can be less than 40.degree. of
rotation. The stops also can be lower to allow the rotation to go
past a maximum angle so that the stops prevent motion after a
control systems fails. FIG. 17 shows a stop 1907 for the
inversion/eversion axis according to one or more embodiments of the
invention in which the footplate assembly 1901 can include an inner
footplate 1902 and an outer footplate 1903, links 1904 between the
inner footplate 1902 and the outer footplate 1903, a frame 1905,
links 1906 between the outer footplate 1903 and the frame 1905, and
a stop 1907.
[0092] In one or more embodiments of the invention, a maximum
rotation on the plantar/dorsiflexion axis can, for example, be
60.degree. of rotation. In one or more embodiments of the
invention, a stop on this axis can be built into the frame using a
cross beam. The stop can, for example, be constructed from the 8020
or another material. FIG. 18 shows a stop for the
plantar/dorsiflexion axis according to one or more embodiments of
the invention in which the footplate assembly 2001 can include an
inner footplate 2002 and an outer footplate 2003, links 2004
between the inner footplate 2002 and the outer footplate 2003, a
frame 2005, links 2006 between the outer footplate 2003 and the
frame 2005, and a stop 2006.
Stationary Platform
[0093] According to one or more embodiments of the invention, a
stationary platform can be included. As shown in FIG. 2, a larger
stationary platform 202 can enclose two robotic platforms 201. For
some exercises, it may be desirable to have additional space for
patients to practice taking steps and balancing at different
orientations. As such, a larger stationary platform can provide
additional space in the front of the robotic platforms or in other
locations around the robotic platforms to allow additional space
for patients to practice taking steps and balancing at different
orientations.
[0094] One or more embodiments of the invention can include a
stationary platform, which can provide structural support for the
entire system. FIG. 1 shows a view of a Virtually-Interfaced
Robotic Ankle and Balance Trainer system 100 according to an
embodiment of the invention. The Virtually-Interfaced Robotic Ankle
and Balance Trainer system 100 can comprise a stationary platform
101, and the stationary platform 101 can house two robotic
platforms 102. Additionally, safety features such as safety rails
103 can attach to the stationary platform 101. The system 100 can
also include a lift-assist chair device 104. In one embodiment of
the invention, the platform can, for example, be 50''
wide.times.58'' long x 15.5'' tall (not including the railings). In
other embodiments, the platform can be built to other dimensions.
In an embodiment, there can be additional room in front of the
robotic platforms to allow for additional exercises. In additional
embodiments of the invention, there can, for example, be 18'' of
platform space to allow for a step to be taken. In other
embodiments, there can be other amounts of platform space. One or
more embodiments of the invention can, for example, use
1.5''.times.1.5'' aluminum extrusions from 80/20 for a base frame
to provide structural support and quick assembly. In further
embodiments, other materials with other dimensions can be used to
provide structural support. Additionally, in one or more
embodiments of the invention, a base frame can be built in, for
example, four separate parts for quick disassembly so it can be
more easily moved.
Sliding Track
[0095] In one or more embodiments of the invention, a sliding track
system for robotic platforms that can be included. The sliding
track system can be attached underneath the stationary platform.
Due to different anatomies, the comfortable stance width between
two feet varies from person to person. A sliding track in
accordance with one or more embodiments of the invention can allow
for footplate subsystems to be adjustable. One or more embodiments
of the invention an include fixed positions to ensure stability and
prevent the footplates from shifting unintentionally. For one or
more embodiments of the invention, the stance width can vary, for
example, from six to sixteen inches. As such, in one or more
embodiments of the invention, the track can provide for
adjustability at every two inches. Of course in other embodiments
of the invention, the spacing between the footplate subsystems can
vary by other amounts and the spacing can be incremented by other
amounts or can be adjusted continuously. By allowing for adjustment
of the distance between the footplate assemblies, embodiments with
a sliding track can provide a third degree of freedom, in addition
to inversion/eversion and plantar/dorsiflexion.
[0096] In one or more embodiments of the invention, a foot plate
and subcomponents can be placed on a track on the floor. FIG. 19
shows foot plate and subcomponents 2301 and tracks 2302. In one or
more embodiments, mechanical stops can be added to for stability. A
potential concern when the spacing between footplates can be
adjusted may be gaps between the footplates where a user could fall
or step into a gap, potentially causing injury. In one or more
embodiments of the invention, this can be addressed with the use of
attachable platforms to be placed in between the footplates.
Safety Features
[0097] For one or more embodiments of the invention, many the
patients using the system may not have sufficient ankle balance and
strength to use the device without additional safety features. For
this reason, one or more embodiments of the invention can include
handlebars, a safety harness, and/or other safety features.
Handle Bars
[0098] For one or more embodiments of the invention, handlebars
such as curved railings 203 in FIG. 2 can allow for any person, no
matter the height, to comfortably hold onto them while stepping
onto the platform. Curved railings can also advantageously
eliminate some or all sharp edges, which can improve patient safety
in the event that a patient falls. The railing 204 in the front can
be adjustable from, for example, three to four feet, or other
amounts, to accommodate different patient heights.
[0099] In one or more embodiments, safety rails 203 can be included
on top of the stationary platform, as shown in FIG. 2. Since
patients can be at risk of losing their balance when performing
exercise, the inclusion of safety rails in certain embodiments can
advantageously provide structure for them to hold onto while
exercising. In an embodiment of the invention, the design can
utilize 1.5'' hollow-aluminum rods that provide standard rigidity
for rails. "Slip-On" rail fittings can be used to allow for quick
and easy assembly, while maintaining structural support to provide
stability to the system. In one or more embodiments, the left,
right, and front handle bars can be adjustable in height from 24''
to 40'' to accommodate the different patient heights. In other
embodiments, the design can utilize different materials with
different dimensions.
Harness
[0100] In one or more embodiments of the invention, a safety
harness can serve to protect a patient if he or she were to lose
his or her balance. A safety harness can also be used to bear some
of the patient's weight. In certain embodiments, a safety it may be
used as an unweighing safety harness. In one or more embodiments, a
safety harness can be mounted directly onto the overall system and
can be easily be attached or detached. FIG. 20 shows an example of
a safety harness 2501, which can be used in accordance with one or
more embodiments of the invention.
Foot Release Mechanism
[0101] In one or more embodiments of the invention, a foot release
mechanism can be used to provide additional safety for a patient as
well as to protect the components of the device. In one or more
embodiments, a foot release mechanism can securely hold a patient's
foot in place while operating under normal conditions and can
release a patient if a patient falls or begins to exceed a max
allowable torque on the device. Additionally, it may be desirable
for the foot release mechanism to be low cost and simple.
Velcro.TM. or Button Strap
[0102] In one or more embodiments of the invention, a strap can be
attached to the foot plate and can lay over the patient's foot to
secure it to the foot plate. An advantage of such embodiments is
the adjustability. Due to a wide range of the size of a patient's
foot, the strap can easily be adjusted to fit the patient
accordingly.
"Ski Binding Quick Release"
[0103] One or more embodiments of the invention can incorporate a
foot release mechanism like a ski binding, where, when a large
amount of torque is applied to the binding, the device can release
the foot.
Chair
[0104] One or more embodiments of the invention can provide a chair
system to allow a patient to perform exercises over a range of
angular seated positions. For example, a stroke patient that has
trouble standing may benefit from adjustable seating so that
retraining muscle control can be performed over incremental
positions between sitting and standing. In one or more embodiments
of the invention, the rehabilitation device can provide training
capabilities at a common seated position, as shown, for example, in
FIG. 21 and standing, as shown, for example, in FIG. 22.
Embodiments of the invention can provide an easy way for a user to
attach a chair subsystem to the main platform, to sit comfortably
in the chair, and adjust the height or angle as desired.
Chair on Moving Platform
[0105] One or more embodiments of the invention can include a chair
2601 on a standalone platform 2602 that can be wheeled up to a main
platform and can be secured to it. The chair can be a basic
off-the-shelf component in conjunction with a lift-assist seat pad
(also off-the-shelf) placed on top of the chair that can
electronically adjust to increase the seated angle from 0.degree.
up to 80.degree., for example, as can be seen in FIG. 21. In
addition, for safety and comfort, a seatbelt can be included to
secure around the waist of a user to keep the user from sliding off
the seat pad when at an incline.
[0106] Rolling height-adjustable chair
[0107] One or more embodiments of the invention can use a chair
2901 that can include wheels on the bottom and can be wheeled
directly up to the platform. In one or more embodiments, the chair
2901 can use a hydraulic pump system, similar to a barber chair. As
shown in FIG. 23, the chair 2901 can be lowered so the patient can
sit down and be secured via a seatbelt into the chair 2901. After
being brought over to the platform, the chair height of chair 2901
could be raised using the foot pump until the patients feet can
comfortably reach the robotic platform. Similar to depiction in
FIG. 23, the chair 2901 device can have a lift-assist seat to
adjust the patients seated angle during rehabilitation.
Transmission System
[0108] A robotic footplate according to one or more embodiments of
the invention can provide controlled rotation, speed, and torque
with accuracy and precision. Furthermore, in one or more
embodiments of the invention, a robotic footplate can be controlled
by a motor/gearbox combination for each degree of freedom, both in
inversion/eversion and plantarflexion/dorsiflexion. Additionally,
in one or more embodiments of the invention, a gearbox can provide
torque amplification and speed reduction. Possible mechanical
specifications according to one or more exemplary embodiments are
summarized in Table 1 below.
TABLE-US-00001 TABLE 1 Possible mechanical specifications
Plantarflexion/Dorsiflexion Configuration Specifications Rated
Torque 230 N-m (2036 lb.-in) Speed 20-30 RPM Power 480-720 Watts
Inversion/Eversion Configuration Specifications Rated Torque 64 N-m
(567 lb.-in) Speed 15-20 RPM Power 100-135 Watts
[0109] Of course in other embodiments, different mechanical
specifications can be used.
Exemplary Pulley and Timing Belt Selection
[0110] In one or more embodiments of the invention, the power from
both the inversion/eversion and plantarflexion/dorsiflexion motors
can be transmitted through the use of a timing belt, as discussed
previously. Such embodiments can reduce or minimize backlash and
misalignment issues. In one or more embodiments of the invention,
the belt and pulley can provide torque and RPM from each motor. In
one or more embodiments of the invention, the length of the belt
can, for example, be selected based on the center distance between
the driver and driven shaft. Exemplary input values and exemplary
selected drive output for an exemplary embodiment can be seen in
FIG. 24.
Exemplary Sensor Selection
[0111] In one or more embodiments of the invention sensors can be
employed to supply feedback to motors for precise control. One type
of feedback that can be provided is positional feedback of the
footplate, which can be provided by an encoder. Another sensor that
can be used in one or more embodiments of the invention is a
pressure map system for measuring peak pressure on the foot in
magnitude and location so that the torque output from the motor can
be appropriate for a given patient's treatment regimen. A single
force sensor on each footplate can also be used in one or more
embodiments of the invention to provide a total weight of the
patient. This information may also be used for determining a weight
percentage distribution for different applications of the
device.
Encoders
[0112] In one or more embodiments of the invention, an encoder can
be placed on each motor shaft. In one or more embodiments of the
invention, there can be an encoder on the footplate shafts for each
rotational direction. If there is an error in the transmission of
rotation between the motor and the footplate shaft, the error can
be read between the two encoders on each degree of freedom.
[0113] An encoder can be used on both axes of rotation. A
differential, optical rotary encoder can, for example, be used. An
exemplary encoder can, for example, have resolution of 1,250 counts
per revolution. In other embodiments, other encoders can be used.
In one or more embodiments of the invention, for the
inversion/eversion axis, the encoder can be directly mounted to the
motor via a dual-shaft configuration. In one or more embodiments of
the invention, for the plantarflexion/dorsiflexion motor, an
encoder can be applied directly to the axis of rotation. In other
embodiments, encoders can be attached in other manners.
Pressure Map
[0114] According to an aspect of the invention, in one or more
embodiments, to provide peak pressure and center of pressure (COP)
readings, a pressure mapping sensor can be employed. In one or more
embodiments of the invention, a pressure map can be interfaced with
a computer via a USB connection and an interface module. In other
embodiments, other interfaces and connections can be used.
[0115] In one or more embodiments of the invention, pressure map
measurements can be incorporated into a motor control system that,
for example, uses Lab View or other software. In an embodiment of
the invention, the pressure map software provided can also be used
separately from motor control.
[0116] In one or more exemplary embodiments of the invention, a
pressure map can, for example, provide readings up to 30 PSI or
206.84 kPa. In other embodiments of the invention, a different type
of pressure map can be used. In addition, in an exemplary
embodiment of the invention, the size of the pressure map can, for
example, be 23 cm long and can, for example, be shaped like a foot.
For other embodiments of the invention a higher or different value
can be used, as well as other shapes. Additionally, in one or more
embodiments of the invention, a custom size pressure map can be
used.
Exemplary Support Frame of Robotic Platform
[0117] In an exemplary embodiment of the invention, as a result of
finite element analysis, as well as calculations, materials for the
support frame were selected to provide safe and effective operation
with minimal deflection and minimal stress under maximum weight
application. In one or more embodiments of the invention, the
support frame of the robotic platforms can, for example, be
aluminum. In one or more embodiments of the invention, the outer
frame of the robotic platform can be robust and can precisely fit
together. In further embodiments of the invention, other materials
can be used for the support frame.
[0118] FIG. 25 shows a 3D CAD image of an exemplary robotic
platform support frame 3300 according to one or more embodiments of
the invention.
Interior Frames of Robotic Platform
[0119] In one or more embodiments of the invention, interior
components of a robotic platform can be driven by a transmission
system. Additionally, in one or more embodiments of the invention,
two rectangular interior frames can be combined together such that
they can each rotate around a different axis (providing 2 degrees
of freedom motion), such as an inversion/eversion axis and a
plantar/dorsiflexion axis. In one or more embodiments of the
invention, an inversion/eversion frame can be located within a
plantar/dorsiflexion frame. In one or more further embodiments of
the invention, a plantar/dorsiflexion frame can be located within
inversion/eversion frame. In one or more embodiments of the
invention, an inversion/eversion frame can be part of a footplate,
and in one or more further embodiments of the invention, a
plantar/dorsiflexion frame can be part of a footplate.
[0120] FIG. 26 shows a sub-assembly of a rotating portion of a
robotic platform according to one or more embodiments of the
invention. In an embodiment of the invention shown in FIG. 26, a
rotating portion of a robotic platform can comprise a footplate
assembly 3401, which can include an inversion/eversion frame 3402
and a plantar/dorsiflexion frame 3403. As shown in FIG. 26, the
inversion/eversion frame 3402 can be located within the
plantar/dorsiflexion frame 3403. In other embodiments, a
plantar/dorsiflexion frame can be located within an
inversion/eversion frame. The robotic platform can further
comprise, shafts 3404 and 3406. The shafts 3404 can be located
between the inversion/eversion frame 3402 and the
plantar/dorsiflexion frame 3403, and shafts 3406 can be located
between the plantar/dorsiflexion frame 3403 and a support frame
3405 (not shown). In other embodiments, other arrangements can be
used. For example, in one or more embodiments, the shafts 3406 can
be located between the inversion/eversion frame 3402 and the
plantar/dorsiflexion frame 3403, and shafts 3404 can be located
between the plantar/dorsiflexion frame 3403 and a support frame
3405 (not shown). The robotic platform can further include supports
3407, which can reinforce the footplate assembly 3401.
[0121] In one or more embodiments, an inversion/eversion frame can
rotate around two shafts, as, for example, shown in FIG. 26. A
challenge with fabricating components for an inversion/eversion
frame can be alignment. In an embodiment of the invention, a single
shaft through the whole length of a footplate can be used. In such
an embodiment, a more precise fabrication process can be used for
proper rotation. In an embodiment, two separate shafts can be used
to mitigate twist that can be seen in a drive shaft by making the
shaft shorter. For one or more embodiments of the invention, it may
be desirable to use a process of machining/fabricating these parts
with high accuracy, for example, within one-thousandth of an inch
(0.001''), to help provide proper alignment. A further potential
challenge for an inversion/eversion frame such as the one depicted
in FIG. 26 can be alignment issues with screw holes. For example,
in an exemplary embodiment, screw holes can be located at the
corners of aluminum bars that can be used for a frame structure.
For one or more embodiments of the invention, adjustments can be
made to the width of ledges on either end such that holes line up.
Such adjustments can be an part of the fabrication process. In one
or more embodiments of the invention, the frame can be square to
prevent contact with a support frame during rotation. In other
embodiments of the invention other structures can be used to
provide inversion/eversion rotation and plantar/dorsiflexion
rotation. Such structures can use a variety of shapes and
constructions and are not limited to the exemplary embodiments
shown, for example, in FIG. 26.
[0122] In one or more embodiments of the invention, a footplate on
which a user stands can be made of acrylic to decrease the weight
of the moving components. In other embodiments of the invention,
other materials can be used to construct the footplate. In one or
more embodiments of the invention, bars, which can be made of steel
and/or other materials, can be incorporated into the design, for
example as horizontal supports under the acrylic, to minimize the
deflection experienced by the acrylic alone. In further embodiments
of the invention, vertical supports or supports with any other
orientation can be used. FIG. 27 shows an image of an interior
frame inversion/eversion sub-assembly 3501 according to one or more
embodiments of the invention, which can comprise an
inversion/eversion frame 3502 and shafts 3504, which can be located
between the inversion/eversion frame 3502 and a
plantar/dorsiflexion frame 8353 (not shown), and supports 3507. In
other embodiments, other configurations can be used. For example,
an inversion/eversion frame can be an outer frame, and shafts 3503
can be located between the inversion/eversion frame and a support
frame or other structure.
[0123] According to an aspect of the invention, in one or more
embodiments, cutouts or other structures for locking pins or other
locking mechanisms can be included to lock the position of the
footplate for operation in a stable mode. In one or more
embodiments of the invention, an acrylic footplate and steel
supports can be mounted to an inside frame, which can comprise
bars. In one or more embodiments, there can, for example, be four
bars, which can be made of aluminum and/or other materials. In one
or more embodiments, the bars can include cutouts for locking pins
for stable mode. For example, FIG. 27 shows holes 8308, which can
be used as cutouts for locking pins for stable mode. In one or more
embodiments of the invention, there can also be cutouts in two side
aluminum bars, such that steel bars and an acrylic plate can be
flush with the top of the aluminum bars.
[0124] In one or more embodiments, an inversion/eversion frame
and/or a plantar dorsiflexion frame, which can be inner frames or
outer frames, can be constructed, for example, using four aluminum
bars. In one or more embodiments, such aluminum bars can be
designed to fit each other at each corner without significant
overlap or room to shift. In one or more embodiments, these parts
can be secured with two 8-32 socket head fasteners at each corner
of the aluminum frame and along the sides of the acrylic footplate
to secure it to the steel supports and the aluminum frame. In other
embodiments, components of an interior frame, such as an
inversion/eversion sub-assembly or a plantar/dorsiflexion
subassembly, can be constructed with other materials and
combinations of materials and can use other attachments.
[0125] In one or more embodiments of the invention, a
plantar/dorsiflexion frame can rotate around an axis perpendicular
to that of an inversion/eversion frame. FIG. 28 shows an image of
an interior frame plantar/dorsiflexion frame sub-assembly 3601
according to one or more embodiments of the invention, which can
comprise a plantar/dorsiflexion frame 3603, shafts 3604, and shafts
3606. The shafts 3604 can be on the ends and can be for
inversion/eversion. In one or more embodiments of the invention,
the shafts 3604 can pass through the plantar/dorsiflexion frame to
reach a pulley system that can be driven by the motor and gearbox.
The shafts 3606 can be on the side and can be for
plantar/dorsiflexion rotation. In one or more embodiments of the
invention, a shaft 3604 can be keyed at the end and can attach to a
pulley after passing through a mounted bearing. The shaft 3604 at
the other side that can be not keyed at the end and can fit into a
mounted bearing and can keep the plate horizontal for alignment and
add support. As with an inversion/eversion frame sub-assembly,
potential fabrication/machining concerns with these components can
include shaft alignment and hole alignment, but these problems can
be avoided with precise machining, accurate measurements, and/or
other alignment techniques.
[0126] In an exemplary embodiment, the plantar/dorsiflexion frame
3603 can use two 8-32 socket head fasteners at each corner of
aluminum bars such that the components of a rectangular assembly
can stay at substantially 90.degree. to each other. In other
embodiments, the plantar/dorsiflexion frame 3603 can be constructed
from other materials and structures and can use other
fasteners.
Transmission System Assembly
[0127] In one or more embodiments of the invention, a pulley and
timing belt assembly can be used to drive shafts from motors. In an
exemplary embodiment of the invention, the ratio of a drive pulley
to a driven pulley can, for example, be 1:1. In other embodiments,
other ratios can be used. In one or more embodiments of the
invention, a gearboxes can provide a mechanical advantage and
pulleys can, for example, be kept at the same radius for each
respective degree of freedom system. In one or more embodiments of
the invention, a sprocket of the pulley assembly can, for example,
be mounted to a coupler, which can fit on to a steel drive shaft,
and the transmission of force can be through a key.
[0128] One or more embodiments of the invention can provide an
appropriate tension to the belt such that there is little or no
slippage or backlash when high forces/torques are experienced,
which can provide for safe and precise operation of a pulley and
timing belt assembly. This tension can be provided, for example, by
an idler pulley that can be installed on both inversion/eversion
and plantar/dorsiflexion drive systems. An exemplary idler pulley
for the plantar/dorsiflexion timing belt according to one or more
embodiments of the invention is shown in FIG. 29. In an exemplary
embodiment, an idler pulley can be included for the
plantar/dorsiflexion timing belt to tension it to 50 pounds, for
example, or to another tension. In an exemplary embodiment, for the
inversion/eversion timing belt, an idler pulley can be used to
tension it to 20 pounds, for example, or to another tension.
System Controls
[0129] In one or more embodiments of the invention, the system can
be controlled by a controller system controlling the motor. In one
or more embodiments, each motor can have its own controller to
control its movement. In an exemplary embodiment, software and a
controller can, for example, be used. Table 2 shows exemplary input
specifications for each motor in an exemplary embodiment of the
invention.
TABLE-US-00002 TABLE 2 Exemplary input specifications for each
motor in an exemplary embodiment Input PFDF Motor INEV Motor Rotor
Inertia (oz-in-s.sup.2) 0.03399 0.01133 No. of Poles 8 8 Peak
Torque (oz.-in) 900 297 Rated Torque (oz.-in) 297 Velocity Limit
(RPM) Torque Constant (oz.-in/A) 17 53.8 Back EMF Volt. (V/kRPM)
11.5 29.5 L2L Resistance (ohms) 0.16 3.8 L2L Inductance (mH) 0.3
10.95
[0130] In an exemplary embodiment of the invention, motor position
can be controlled, for example, with the software using internal
sensors.
[0131] In one or more embodiments of the invention, encoders can be
used to control each motor and, as such, to control rotation of a
footplate. In an exemplary embodiment, an encoder can, for example,
be integrated into software control for each motor. In an exemplary
embodiment of the invention, once control of the motor was
established using, the software was eliminated and the controller
was controlled by LabVIEW. 38 shows an exemplary
plantarflexion/dorsiflexion controller using a dial in the control
window according to one or more embodiments of the invention.
[0132] In one or more embodiments of the invention, a controller
can be integrated into the system to control both motors at the
same time. For an exemplary embodiment of the invention, after the
LabVIEW program was complete for each individual motor, a physical
controller was integrated into the system to control both motors at
the same time. For this mode, the user can, for example, control
the position of the footplate with a joystick controller or other
controller. Both inversion/eversion and plantarflexion/dorsiflexion
can be controlled, for example, with a single remote. FIG. 31 shows
a block diagram depicting the flow of information from the user's
hand to the position of the footplate in one or more embodiments of
the invention. In an exemplary embodiment, a joystick position can
be read by LabVIEW and can be converted to a corresponding voltage,
and a motor controller can output this voltage to the motor and
gearbox which can rotate the footplate.
[0133] In an exemplary embodiment, the footplate position can be
read by the encoder, and an angular position read by an encoder can
be displayed, for example, in a LabVIEW program. FIG. 32 shows an
exemplary LabVIEW control window according to one or more
embodiments of the invention. There can be two inputs in the
controller: a mouse to turn the motor on/off and a joystick to
control the position. The input voltage for each motor can have a
numerical display. A graphical output of each direction can also be
shown. In other embodiments, other inputs and configurations can be
used to measure a position of the footplate.
[0134] In one or more embodiments of the invention, the control of
the system can be a closed loop, limiting the angular range of each
direction to specifications. A software "stop" can prevent the user
from rotating a footplate past an acceptable limit. Additionally,
as noted previously, mechanical stops can also be included in one
or more embodiments.
Clinical Exercises and Control Design
[0135] In one or more embodiments of the invention, the system can
include controls for clinical exercises. Table 3 lists examples of
some of the clinical exercises and stretches that one or more
embodiments of the invention can be configured for a patient to
perform.
[0136] In one or more embodiments of the invention, the device can
have the capability to operate in various modes. Depending on the
mode, the motor control can vary. Additionally, some exercise can
have the option to be run in multiple modes. One or more
embodiments of the invention can include the modes described in
Table 4.
TABLE-US-00003 TABLE 4 Device modes and control design notes
Control Mode Description Design Notes Diag- In this mode the device
can allow the user A measurement nostic to run through their ROM
and can give the system for ROM therapist information on the
severity of and strength injury. This will include their strength
and can be used. flexibility. Assis- The device can assist the user
in completing A patients foot tive a desired motion. This can be
for users should not be entering therapy that do not have the moved
too strength or flexibility to complete the quickly, this may
exercise. cause spasticity. Pas- The device only compensate for its
own Programming can sive weight, giving the effect that the
patient's account for foot is not attached to anything; they can
motor and foot- complete the exercise by their own will. plate
weight so the user is not being weighed down by them Resis- For
more advanced users the device can Forces should not tive resist
the users motion in a similar manner be too high as to a band,
making the exercise more to strain the difficult. users foot.
Haptic This mode can be used to train the users Pathway muscle do
perform a correct motion path. boundaries This can be done, for
example, in assistive, can be defined. passive, or resistive modes.
As the user deflects from the path of motion the device can resist
their motion, correcting the pathway. Balance In this mode, the
platforms can be locked The center of into position and the
pressure maps can be pressure can be used to locate the users
center of pressure. calculated. The user can then practice shifting
their weight to change their center of pressure.
Frame Resizing to Reduce the Stance Width
[0137] In one or more alternative embodiments of the invention, the
footplate and rotating frames can have reduced size to reduce
stance width. After an initial build of the two robotic platforms
according to an exemplary embodiment of the invention, it was
decided that it was desirable to provide one or more embodiments
where the overall stance width can be narrower. A smaller version
of the platforms according to one or more embodiments was first
modeled in CAD to determine where material could be removed. In one
or more embodiments, the footplate can be narrower and the gaps in
between each plate can be made smaller, and the shafts in the
bearings can be cut down.
[0138] For an exemplary embodiment, an FEA analysis with was
completed. Models for isometric stress, maximum stress, and
deformation were created for a 3001b load at the ball of the foot
and in the center of the footplate. FIG. 33 is an example of one of
the FEA models and Table 5 shows the results for each model
according to an exemplary embodiment of the invention. FIG. 33
shows exemplary deformation due to loading on the ball of the foot
on resized frame according to one or more embodiments of the
invention.
TABLE-US-00004 TABLE 5 Exemplary results of FEA analysis on the
resized frames. All results are maximum values for exemplary
embodiment. Load Applied to: Iso Stress (Pa) Max Stress (Pa)
Deformation (m) Ball of Foot 5.148e8 5.148e8 6.85e-4 Center of
Plate 7.214e8 7.214e8 8.74e-4
[0139] In an embodiment of the invention, each piece of the outer
frame and footplate that contributes to the width of the device can
be cut down. Both platforms in an embodiment of the invention can
be taken apart, cut down, and reassembled. To reduce the gap width
in-between inversion/eversion and planter/dorsiflexion footplates,
in one or more embodiments of the invention, the cap heads 4201 on
the shafts 4202 can be countersunk into the frame 4203. FIG. 34
shows an example cap heads 4201 of shafts 4202 counter sunk into a
frame 4203 according to one or more embodiments of the invention.
In one or more embodiments, such changes can reduce the overall
stance width down to approximately 12 inches. In one or more
embodiments, the platforms can be adjusted for a wider or narrower
stance width.
Load Cell Implementation
[0140] In one or more embodiments of the invention, sensors can be
used to measure the tension and compression applied to the
footplate by the user for feedback control for the platform.
Because of the desirability of providing a tension reading when a
foot is in dorsiflexion and other orientations, in one or more
embodiments of the invention, load cells can be used under a
footplate. FIG. 35 shows an example of load cell 4301 placement
according to one or more embodiments of the invention. In one or
more embodiments of the invention, four load cells 4301 can be
placed under four screws 4302 on a footplate 4303.
[0141] FIG. 36 shows an example of a crossbar 4403 for mounting
load cells 4401 and springs 4402 according to one or more
embodiments of the invention. In one or more embodiments of the
invention, to measure tension with the compression load cells 4401,
a pre-load can be applied using mechanical springs 4402. The load
cells 4401 can be attached, for example, to a custom machined
crossbar 4403 under a platform 4404.
[0142] In one or more embodiments of the invention, a sandwich
configuration can be used to preload load cells 4501, an example of
which is shown in FIG. 37. The load cells 4501 can be attached to a
cross bar 4503 and then sandwiched by an upper plate 4505. A bolt
4506 can be inserted through the cross bar 4503 and upper plate
4505 and secured above the plate 4505 by a bolt 4506, which can be
covered by the footplate 4504. In between the bolt head/washer 4507
and the crossbar 4503 can be a compression spring 4502.
[0143] In one or more alternative embodiments of the invention, the
design can be fully adjustable for a desired preload. For example,
tightening the bolt puts can put a compression load onto the load
cells 4502, which can be manually adjusted for a desired preload on
each load cell. In one or more alternative embodiments of the
invention, there can be one spring 4502 for two load cells 4501. In
one or more alternative embodiments of the invention, there can be
a total of two springs 4502 and four load cells 4501. In other
embodiments of the invention, any other numbers of springs and any
other number of load cells can be used.
[0144] In one or more embodiments of the invention, spring
selection can be based, for example, on overall length, deformation
percentage, and/or the spring error. In an exemplary embodiment of
the invention, a spring can, for example, have a length of
approximately 1 inch. In an exemplary embodiment of the invention,
a deformation in the spring can, for example, be greater than 33%
of the overall length due to the spring mechanics. In an exemplary
embodiment of the invention, the approximate movement to the spring
because of the load cells can, for example, be 0.001 inches, which
can be the error in the preload.
[0145] Table 6 shows spring characteristics and calculations for
exemplary springs in one or more embodiments of the invention.
TABLE-US-00005 TABLE 6 Exemplary spring selection. Total pre-load
force 200 lbs. # Load Cells 4 qty Pre-load per load cell 50 lbs. #
Springs 2 qty Load per spring 100 lbs. Length 1.00 in Calc def.
length 0.18 in K 564.00 lbs./in Deflection % 17.73% Spring Error
0.56 lbs. Spr. Error % 0.56%
[0146] Springs can be assembled onto a device built according to an
embodiment of the invention and can be tightened to apply a
preload, for example, a 50 pound preload, on each load cell. In
further embodiments of the invention, preloads of amounts other
than 50 pounds may also be applied.
[0147] In one or more embodiments of the invention, such as a four
load cell configuration, a device according to an embodiment of the
invention can indicate a center of a pressure map. A patient's foot
can be on a platform, and a red dot can be displayed in a LabVIEW
interface and can show where the center of pressure is on the
platform. Both platforms can be censored such that a center of
pressure calculation can be an overall center of pressure of the
user, in addition to or instead of a single foot. In one or more
embodiments of the invention, a center of pressure measurement can
be used for the balance exercises and can also be implemented with
a game.
Encoders
[0148] In one or more embodiments of the invention, an
inversion/eversion encoder and a plantar/dorsiflexion encoder can
be used to measure inversion/eversion and plantar/dorsiflexion of a
footplate. In one or more embodiments of the invention, an
inversion/eversion encoder can be built into the back of an
inversion/eversion motor, and a plantar/dorsiflexion encoder can be
placed onto an outer shaft and can directly measure the actual
angle of the footplate. In other embodiments of the invention,
inversion/eversion encoders and plantar/dorsiflexion encoders can
be located in other locations. For example, as shown in FIG. 38, in
one or more embodiments of the invention, an inversion/eversion
encoder 4601 be located on a shaft 4602. The shaft 4602 can attach
to a drive belt 4603 and can be turned down and a cover 4604 can be
included. The cover 4604 can house the encoder 4601. The cover can
be constructed, for example, using a 3D printer.
[0149] In one or more embodiments, absolute encoders can be used
for acquiring data. In other embodiments, other encoders may be
used.
Inversion/Eversion Motor Cover
[0150] In one or more embodiments of the invention, an
inversion/eversion motor can be completely enclosed, which may
advantageously improve patient safety. FIG. 39 shows a CAD design
of a cover 4701 on a motor 4702 according to one or more
embodiments of the invention.
[0151] In one or more embodiments of the invention, a slant can be
included in a front face of a cover, which may advantageously avoid
a patients ankle or heel being affected by the cover. FIG. 40 shows
a slant 4802 in a cover 4801 according to one or more embodiments
of the invention. Advantageously, such embodiments can help avoid
obstructing the users motion, for example, when used in a seated
mode.
Surrounding Platform and Chair
[0152] According to an aspect of the invention, the device can
include a platform and railing. In one or more embodiments of the
invention, the platform can allow for a patient to train one leg at
a time. In one or more embodiments of the invention, the platform
can have enough room for a patient to take a step forward during
training The platform can also have a rail system for patient
safety. The rail system can be made of a material such as aluminum.
One or more embodiments of the invention can include sliding rails
that allow for adjustability to patient height. The extension of
the rails can also allow a patient to use the railings while
getting up on the platform. FIGS. 41 and 42 show views of a CAD
model of a platform and rail system according to one or more
embodiments of the invention. In FIG. 41, an embodiment of the
invention comprises surrounding platform 4901, rail system 4902,
and robotic platform 4903. In FIG. 42, an embodiment of the
invention comprises surrounding platform 5001, rail system 5002,
and robotic platform 5003.
[0153] In one or more embodiments of the invention, the platform
base can be made out of a material such as 80-20. The robotic
platform can also be made out of similar material for ease of
assembly. The railings can be made out of a material such as
aluminum piping to make it more stable and keep it relatively
lightweight. In further embodiments, other materials can be used
for these features.
[0154] In one or more embodiments of the invention, the chair
design can be modeled as a bench. In one or more embodiments, a
bench can account for different patient leg lengths as well as
motors on the back of a device and bring a patients foot close
enough for training A bench can also be adjustable in height and
can be on wheels so that a patient can be moved over a platform
according to one or more embodiments of the invention. FIG. 43
shows a CAD design for a bench 5101 according to one or more
embodiments of the invention. The bench 5101 can be made out of any
material. For example, in one or more embodiments of the invention,
the bench 5101 can be constructed out of metal and/or wood. In one
or more embodiments of the invention, the bench 5101 can be
separate from a frame 5102 and can be removable. One or more
embodiments of the invention can further comprise platforms 5103,
which can, for example, be 31 inches by 18 inches by 16 inches, or
any other dimensions.
[0155] In one or more embodiments of the invention, a platform can
be controlled with a hand-held remote control. FIG. 44 shows an
embodiment of the invention, which can comprise robotic platforms
5201 and a remote control 5202.
[0156] In one or more embodiments of the invention, patients can be
seated and can play a simple game, such as a maze game.
Additionally, patients can perform tasks such as an isometric
strength task and a free ankle movement task at various speeds. One
or more embodiments can further include a chair and foot strap as
discussed previously.
Static Force Measurement
[0157] In one or more embodiments of the invention, an ankle and
balance rehabilitation system can measure human interaction force.
For example, one or more embodiments of the invention can include
four compression load cells installed in the footplate and can
include a unique mechanical design such that both tensile and
compressive loads can be measured. One or more embodiments of the
invention can include load cells calibrated separately and can
include load cells preloaded in pairs.
Mechanical Design
[0158] FIG. 45 shows top view A, a CAD drawing, side view B, and a
top view C of a robotic force-plate according to one or more
embodiments of the invention. As shown in FIG. 45, in one or more
embodiments of the invention, a force-plate can include five
different layers: four compression load cells 1, an acrylic
footplate 2, a metal plate 3, two metal crossbars 4, surrounding
aluminum beams 5 that can be connected to a system ground, and the
linear spring 6 that can create a preload. A patient's foot can be
strapped on the acrylic plate 2. Four load cells 1 can be inserted
symmetrically in the four corners of the footplate, in between the
metal plate 3 and metal crossbars 4. The metal crossbars 4 can be
connected to the surrounding aluminum beams 5, which can be
connected to system body. Load cells 1 can be placed in the
Anterior(A)/Posterior(P) and Medial(M)/Lateral(L) planes with
respect to the human ankle.
[0159] In one or more embodiments of the invention, a footplate can
be composed of two layer rectangular plates: an acrylic and a metal
plate. In an exemplary embodiment, the footplate can, for example,
be 36.3 cm.times.16.2 cm (14 5/16 feet.times.63/8 feet) and can,
for example, weigh 2.295 Kg. In certain embodiments of the
invention, acrylic can be lighter than metal and can provide a
relatively high rigidity. In one or more embodiments of the
invention, the metal plate can be attached to the acrylic plate to
support and strengthen the footplate and to reduce deflection.
Plastic shimmer paper can be used in between the plate and two
specific load cells to compensate for an uneven metal surface. FIG.
46 shows a force-plate structure in accordance with one or more
embodiments of the invention, which can comprise an acrylic plate
5401 connected to the metallic plate 5402. In one or more
embodiments of the invention, shimmer papers can be used in between
the footplate and AL and PM load cells to further even the
contact.
[0160] In one or more embodiments of the invention a force plate
can include load cells for force and pressure measurements. In one
or more embodiments of the invention, four compression load cells
can be inserted in a sandwich configuration in between a footplate
and a system body or a mechanical ground. A tensile force
measurement can be achieved by utilizing a preload configuration.
FIG. 47 shows a mechanism of tensile force measurement in
accordance with one or more embodiments of the invention, which can
comprise springs 5501, which can create a preload on load cells. In
one or more embodiments of the invention, a spring 5501 can be used
for pairs of load cells in the anterior and posterior plane of the
footplate. In an exemplary embodiment, the spring 5501 can, for
example, have k.apprxeq.10000 N/m. In other embodiments, springs
with other k values can be used. The spring 5501 can be inserted in
between a bolt head/washer 5502 and a metal crossbar 5503 below a
force-plate 5504. A bolt can be screwed into a nut which can be
welded on top of the footplate. In other embodiments, other
arrangements can be used to apply a preload to load cells and to
measure force and pressure.
[0161] In one or more embodiments of the invention, the amount of
preload on each pair of load cells can be adjusted by
tightening/loosening bolts. The preloaded force measurements can,
for example, be set to zero and consequently a subject's
dorsiflexion, for example, can relax the load cells and lead to
tensile (negative) force measurements. In one or more embodiments
of the invention, an applicable load to the springs can, for
example, be 600 N, and the anterior and posterior springs can be
preloaded, for example, by 220 N and 390 N respectively. In further
embodiments of the invention, the springs can be preloaded with
other values. In still further embodiments, these values can be
acquired experimentally, which can improve accuracy in force
measurement.
Load Cells
[0162] In one or more embodiments of the invention, four
compression load cells can be used to measure a subject's
interaction forces with the footplate. The load cell signals can,
for example, be amplified and sampled into a desktop computer by,
for example, using an NI PCI 6251. FIG. 48 shows a flow chart
representing an exemplary collection of load cell data in
accordance with one or more embodiments of the invention. Load cell
signals can, for example, further be amplified and converted to
digital. In one or more embodiments of the invention, each load
cell can, for example, be connected to a corresponding external
amplifier and analog channel on data acquisition board.
[0163] In one or more exemplary embodiments of the invention, load
cells can, for example, produce 10 my output (2 mV/V.times.5 V
excitation voltage) at a full load condition (e.g., 226 Kg). Using
a built-in potentiometers, amplifier gain can, for example, be
adjusted to 1000 (to create a 10 V output) and the offset voltage
can be removed. Considering, for example, a 16-bit data acquisition
board, in an embodiment of the invention, a minimum load resolution
can, for example, be estimated as 3.5 g.
[0164] In one or more embodiments of the invention, load cells can
be calibrated independently, for example, using an Instron machine,
which can be used to provide test loads. FIG. 49 shows an example
of load cells calibration characteristics in accordance with one or
more exemplary embodiments of the invention. In accordance with one
or more exemplary embodiments of the invention, FIG. 49 shows an
example of a response of an exemplary individual load cell to
exemplary applied loads provided, for example, by Instron machine.
Test loads can be applied to the load cells and the output voltages
can be recorded.
[0165] In one or more embodiments of the invention, load cells can
be placed in the Anterior(A)/Posterior(P) and Medial(M)/Lateral(L)
planes with respect to the human ankle As shown in FIG. 49, in one
or more exemplary embodiments of the invention, six ascending test
loads followed by 5 descending points, for example, can be
considered to calibrate each load cell (e.g., 11 points in total).
A curve fitting procedure can, for example, be conducted to find a
best linear estimate (e.g., R.sup.2>0.998) for each load cell
and acquired equations can, for example, be used to represent the
corresponding load cells.
Force-Plate
[0166] In one or more embodiments of the invention, four load cells
can be placed in between a footplate and a system ground to create
a force-plate. Such embodiments can provide for measuring tensile
and compressive loads. The force-plate can be used to measure total
force and center of pressure (COP).
[0167] In one or more embodiments of the invention, load cells can
have estimated linear curves that can be used to convert a voltage
readings to force values. A LabVIEW program, for example, can be
used to read load cell data from a data acquisition board and
represent the values in a computer. In one or more embodiments of
the invention, a Virtually-Interfaced Robotic Ankle and Balance
Trainer can be equipped with four load cells under a rectangular
footplate to measure both compressive and tensile forces. Load
cells can be calibrated separately (e.g., out of the system) and
mounted into the platform. A center of pressure and a total applied
force to the force-plate can be acquired to evaluate the accuracy
of a platform.
[0168] In one or more embodiments of the invention, a rectangular
metallic plate in contact with four load cells may not perfectly
straight and smooth. As such, shimmer papers can be used in
addition to unequal preloads (e.g., 220 N vs. 390 N) to reduce
unbalanced contact and provide more even interaction between a
footplate and load cells. In certain embodiments, higher preload in
the posterior plane can result in more accurate force
measurements.
[0169] Load cell calibrations can demonstrate a strongly linear
profile. Applied test loads can, for example, have a radius of 1.4
cm, which can limit accuracy evaluation in center of pressure. In
one or more embodiments of the invention, point loads can be
applied to the force-plate. Additionally, in one or more
embodiments of the invention, the error in center of pressure under
both loads can, for example, be less than 1.4 cm across the
force-plate. The total applied force to the force-plate can, for
example, also show less than 5% mean value in certain
embodiments.
Rehabilitation Exercises
[0170] In one or more embodiments of the invention, a force-plate
can be used in any type of static force and center of pressure
measurement. Human subjects can, for example, be instructed to
stand on a force-plate and play an ongoing virtual reality game,
which can be driven by the center of pressure and total applied
force to the footplate.
[0171] One or more embodiments of the invention can be used for a
variety of exercises for rehabilitating a patient. For example, one
or more embodiments of the invention can be used for minimal
resistance exercises. For such exercises, an embodiment of the
invention can measure range of motion in four directions and in
circular movements. Additionally, one or more embodiments of the
invention can be used for maximum strength exercises. For such
exercises, an embodiment of the invention can allow a patient to
exert maximum force in different directions and can measure the
force asserted. Further, one or more embodiments of the invention
can be used for 20% of maximum through range of motion exercises.
For these exercises, an embodiment of the invention can allow a
patient to exert approximately 20% of his or her maximum exertion
through a range of motion and can determine a fatigue point.
[0172] One or more embodiments of the invention can be used for a
variety of balance exercises. For example, one or more embodiments
of the invention can be used in a locked mode for proactive balance
exercises. One or more robotic footplates in accordance with one or
more embodiments can be locked in position and a patient can, for
example, shift his or her weight. The robotic platform can detect
the weight shift using the force plate and can provide visual
feedback, for example, through a virtual reality interface.
Additionally, other balance tests such as a Romberg test can be
performed by a center of pressure measurement from an embodiment of
the invention to detect a weight shift and to provide feedback. One
or more robotic footplates in accordance with one or more
embodiments can also be unlocked for reactive balance training. For
example, the inversion/eversion and plantar/dorsiflexion position
of one or more footplates can be adjusted and center of pressure
measurements can be made with one or more force plates.
[0173] In one or more embodiments of the invention, measurements
can be provided by the force plate load cells and from angular
potentiometers during ankle movements. Virtual reality training
scenes can use force and motion data from ankle movements to
interactively control a cursor within a maze-like game
environment.
[0174] In one or more embodiments of the invention, patients can be
tested in the seated position, with knee and ankle at 90 degrees,
and the tested foot resting on the force plate of the device. A
strap can be used to hold the ankle to the footplate. Isometric
strength of dorsiflexor, plantarflexor, inverter and everter muscle
groups can be tested with the footplate axes locked in a stable
mode. Additionally, the anterior-posterior and medial-lateral axes
of the footplate can be unlocked in a dynamic mode and ankle motion
measures can be taken. Angular excursion of the ankle joint in each
direction can be measured, for example at natural, self-selected
and at fast-paced, but self-selected speeds. A patient's individual
measured values for isometric force, movement excursion and
movement velocity can then be used to customize input thresholds to
move a cursor in various virtual reality games.
[0175] In one or more embodiments, virtual reality games can use
the ankle isometric force control. In further embodiments of the
invention, virtual reality games can use ankle motion/velocity
control. In one or more additional embodiments, multiple levels of
difficulty can be tested for each type of game. In further
embodiments of the invention, resistive forces can be applied
during testing. Additionally, in further embodiments of the
invention, testing can be performed with the patient standing.
[0176] It will be appreciated that while a particular sequence of
steps has been shown and described for purposes of explanation, the
sequence may be varied in certain respects, or the steps may be
combined, while still obtaining the desired configuration.
Additionally, modifications to the disclosed embodiment and the
invention as claimed are possible and within the scope of this
disclosed invention.
* * * * *