A sit-to-stand assist device can serve the needs of people suffering from muscle weakness due to age or disabilities that make sit-to-stand a difficult functional task. The objective of this paper is to design a passive gravity-balancing assist device for sit-to-stand motion. In our study, it has been shown that the contribution to the joint torques by the gravitational torque is dominant during sit-to-stand motion. On the basis of this result, a gravity balanced assistive device is proposed. This passive device uses a hybrid method to identify the center-of-mass of the system using auxiliary parallelograms first. Next, appropriate springs are connected to the device to make the total potential energy of the system due to the gravity and the springs constant during standing up. A demonstration prototype with the underlying principles was fabricated to test the feasibility of the proposed design. The prototype showed gravity balancing and was tested by the authors. This prototype will be modified appropriately for clinical testing.

1.
Ficke
,
R. C.
, 1991, “
Digest of Data on Persons with Disabilities
,” Technical report, National Institute on Disabilities and Rehabilitation Research, Washington, DC.
2.
Dawson
,
D.
,
Hendershot
,
G.
, and
Fulton
,
J.
, 1987, “
Aging in the Eighties: Functional Limitations of Individuals Age 65 and Over
,” National Center for Health Statistics Advance Data, U.S. Department of Health and Human Services, 133, pp. 1–11.
3.
Riley
,
P. O.
,
Schnekman
,
M. L.
,
et al.
, 1991, “
Mechanics of a Constrained Chair-Rise
,”
J. Biomech.
0021-9290,
24
(
1
), pp.
77
85
.
4.
Bajd
,
T.
,
Karl
,
J.
, and
Turk
,
R.
, 1982, “
Standing-Up of a Healthy Subject and a Paraplegic Patient
,”
J. Biomech.
0021-9290,
15
(
1
), pp.
1
10
.
5.
Donaldson
,
N. de N.
, and
Yu
,
C.-H.
, 1996, “
FES Standing: Control by Handle Reactions of Leg Muscle Stimulation (CHRELMS)
,”
IEEE Trans. Rehabil. Eng.
1063-6528,
4
(
4
), pp.
280
284
.
6.
Kamnik
,
R.
, and
Bajd
,
T.
, 2003,
Robot Assistive Device for Augmenting Standing-Up Capabilities in Impaired People
,”
Proceedings of the 2003 IEEE/RSJ Int. Conference on Intelligent Robot and Systems
, pp.
3606
3611
, Las Vegas, Nevada.
7.
Peshkin
,
M.
,
et al.
, 2005, “
KineAssist: A Robotic Overground Gait and Balance Training Device
,”
Proceedings of the 2005 IEEE 9th Int. Conference on Rehabilitation Robotics
, pp.
241
246
, Chicago, IL.
8.
Kamnik
,
R.
,
Bajd
,
T.
,
et al.
, 2005, “
Rehabilitation Robot Cell for Multimodal Standing-Up Motion Augmentation
,”
Proceedings of the 2005 IEEE Int. Conference on Robotics and Automation
, pp.
2289
2294
, Barcelona, Spain.
9.
Streit
,
D. A.
, and
Shin
,
E.
, 1993, “
Equilibrators for Planar Linkages
,”
ASME J. Mech. Des.
1050-0472,
115
(
3
), pp.
604
610
.
10.
Rahman
,
T.
,
Ramanathan
,
R.
,
Seliktar
,
R.
, and
Harwin
,
W.
, 1995, “
A Simple Technique to Passively Gravity-Balance Articulated Mechanisms
,”
ASME J. Mech. Des.
1050-0472,
117
, pp.
655
658
.
11.
Ebert-Uphoff
,
I.
,
Gosselin
,
C. M.
, and
Laliberte
,
T.
, 2000, “
Static Balancing of Spatial Parallel Platform Mechanisms-Revisited
,”
ASME J. Mech. Des.
1050-0472,
122
(
1
), pp.
43
51
.
12.
Agrawal
,
S. K.
,
Gardner
,
G.
, and
Pledgie
,
S.
, 2001, “
Design and Fabrication of a Gravity Balanced Planar Mechanism Using Auxiliary Parallelograms
,”
ASME J. Mech. Des.
1050-0472,
123
(
4
), pp.
525
528
.
13.
Rahman
,
T.
,
Sample
,
W.
,
Seliktar
,
R.
,
Alexander
,
M.
, and
Scavina
,
M.
, 2000, “
A body-powered functional upper limb orthosis
,”
J. Rehabil. Res. Dev.
0748-7711,
37
(
6
), pp.
675
680
.
14.
Cardoso
,
L. F.
,
Tomazio
,
S.
, and
Herder
,
J. L.
, 2002, “
Conceptual Design of a Passive Arm Orthosis
,” in
Proceedings, ASME Design Engineering Technical Conferences
, Paper No. MECH-34285, Montreal, Canada.
15.
Agrawal
,
S. K.
, and
Fattah
,
A.
, 2004, “
Theory and Design of an Orthotic Device for Full or Partial Gravity-Balancing of a Human Leg During Motion
,”
IEEE Trans. Neural Syst. Rehabil. Eng.
1534-4320,
12
(
2
), pp.
157
165
.
16.
Fattah
,
A.
, and
Agrawal
,
S.
, 2005, “
On the Design of a Passive Orthosis to Gravity Balance Human Legs
,”
ASME J. Mech. Des.
1050-0472,
127
(
4
), pp.
802
808
.
17.
Schultz
,
A. B.
,
Alexander
,
N. B.
, and
Ashton-Miller
,
J. A.
, 1992, “
Biomechanical Analysis of Rising from a Chair
,”
J. Biomech.
0021-9290,
25
(
12
), pp.
1383
1391
.
18.
NASA Reference Publication 1024
, 1978, “
Anthropometric Source Book: Volume I: Anthropometry for Designers
,” NASA.
19.
Riener
,
R.
, and
Fuhr
,
T.
, 1998, “
Patient-Driven Control of FES-Supported Standing Up: A Simulation Study
,”
IEEE Trans. Rehabil. Eng.
1063-6528,
6
(
2
), pp.
113
124
.
20.
Angeles
,
J.
, 1997,
Fundamentals of Robotic Mechanical Systems: Theory, Methods, and Algorithms
,
Springer-Verlag
, New York.
21.
Goulart
,
F. R. P.
, and
Valls-Sole
,
J.
, 1999, “
Patterned Electromyographic Activity in the Sit-to-Stand Movement
,”
Clin. Neurophysiol.
1388-2457,
110
, pp.
1634
1640
.
22.
Banala
,
S. K.
,
Agrawal
,
S. K.
,
Fattah
,
A.
,
Rudolph
,
K.
, and
Scholz
,
J. P.
, 2004,
A Gravity Balancing Leg Orthosis for Robotic Rehabilitation
,
Proceedings of the 2004 IEEE International Conference on Robotics and Automation
, pp.
2474
2479
, New Orleans, LA.
You do not currently have access to this content.