Optimization of an unpowered energy-stored exoskeleton spring stiffness for spinal cord injuries

GUAN Xinyu; JI Linhong; WANG Rencheng

doi:10.16511/j.cnki.qhdxxb.2017.21.035

PDF(2016 KB)

Journal of Tsinghua University(Science and Technology) ›› 2017, Vol. 57 ›› Issue (11) : 1179-1184. DOI: 10.16511/j.cnki.qhdxxb.2017.21.035

MECHANICAL ENGINEERING

Optimization of an unpowered energy-stored exoskeleton spring stiffness for spinal cord injuries

{{article.zuoZhe_EN}}

Author information +

History +

Abstract

The unpowered energy-stored exoskeleton can provide precise walking assistance for spinal cord injury patients for a specified body height, weight and injury level. Since the energy-stored springs are standard components of the exoskeleton, their stiffness should be constant. The aim of this study is to select the optimal stiffness of the exoskeleton springs. The hip joint moment was related to the body height, body weight and hip joint angle through an inverse dynamics model for spinal cord injury patients walking in the single support phase from mid stance to terminal stance. The optimization method minimized the integral of the absolute moment generated by the hip joint and springs. The results show that the stiffness of spring 1 (k₁) has a normal distribution while the stiffness of spring 2 (k₂) does not. The medians of the two spring stiffnesses (the median k₁=3 180 N/m and the median k₂=1 279 N/m) can apply to patients whose heights and weights are in the P1-P99 ranges.

Key words

spinal cord injury / walking / standing / exoskeleton / energy-stored

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

GUAN Xinyu, JI Linhong, WANG Rencheng. Optimization of an unpowered energy-stored exoskeleton spring stiffness for spinal cord injuries[J]. Journal of Tsinghua University(Science and Technology). 2017, 57(11): 1179-1184 https://doi.org/10.16511/j.cnki.qhdxxb.2017.21.035

References

[1] Kirshblum S C, Burns S P, Biering-Sorensen F, et al.International standards for neurological classification of spinal cord injury (revised 2011)[J]. The Journal of Spinal Cord Medicine, 2011, 34(6):535-546.[2] Maimoun L, Fattal C, Micallef J, et al.Bone loss in spinal cord-injured patients:From physiopathology to therapy[J]. Spinal Cord, 2006, 44(4):203-210.[3] Johnson W B.Walking mechanics of persons who use reciprocating gait orthoses[J]. Journal of Rehabilitation Research and Development, 2009, 46(3):435.[4] Colombo G, Wirz M, Dietz V.Driven gait orthosis for improvement of locomotor training in paraplegic patients[J]. Spinal Cord, 2001, 39(5):252-255.[5] Audu M L, To C S, Kobetic R, et al.Gait evaluation of a novel hip constraint orthosis with implication for walking in paraplegia[J]. IEEE Transactions on Neural Systems & Rehabilitation Engineering, 2011, 18(6):610-618.[6] Drake R, Vogl A W, Mitchell A W, Gray's Anatomy for Students[M]. New York:Bellevue Literary Press, 2014.[7] Middleton J W, Sinclair P J, Smith R M, et al.Postural control during stance in paraplegia:Effects of medially linked versus unlinked knee-ankle-foot orthoses[J]. Archives of Physical Medicine & Rehabilitation, 1999, 80(12):1558-1565.[8] Abe K.Comparison of static balance, walking velocity, and energy consumption with knee-ankle-foot orthosis, walkabout orthosis, and reciprocating gait orthosis in thoracic-level paraplegic patients[J]. Journal of Prosthetics & Orthotics, 2006, 18(18):87-91.[9] Walsh C J, Paluska D, Pasch K, et al. Development of a lightweight, underactuated exoskeleton for load-carrying augmentation[C]//Proceedings 2006 IEEE International Conference on Robotics and Automation. Orlando, FL, USA:IEEE, 2006:3485-3491.[10] Guan X, Liu Y, Gao L, et al.Trunk muscle activity patterns of a person with spinal cord injury walking with different un-powered exoskeletons:A case study[J]. Journal of Rehabilitation Medicine, 2016, 48(4):390-396.[11] Zajac F E, Neptune R R, Kautz S A.Biomechanics and muscle coordination of human walking:Part I:Introduction to concepts, power transfer, dynamics and simulations[J]. Gait & Posture, 2002, 16(3):215-232.[12] Johnson W B, Fatone S, Gard S A.Walking mechanics of persons who use reciprocating gait orthoses[J]. Journal of Rehabilitation Research & Development, 2009, 46(3):435-446.[13] Chiu M C, Wu H C, Chang L Y.Gait speed and gender effects on center of pressure progression during normal walking[J]. Gait & Posture, 2013, 37(1):43-8.[14] Fineberg D B, Asselin P, Harel N Y, et al.Vertical ground reaction force-based analysis of powered exoskeleton-assisted walking in persons with motor-complete paraplegia[J]. The Journal of Spinal Cord Medicine, 2013, 36(4):313-321.[15] Winter D A, Biomechanics and Motor Control of Human Movement[M]. New York:John Wiley & Sons, 2009.[16] Reynolds H M, Snow C C, Young J W.Spatial geometry of the human pelvis[J]. Spatial Geometry of the Human Pelvis, 1982.[17] Lin K H, Lu T W, Hsu P P, et al.Postural responses during falling with rapid reach-and-grasp balance reaction in patients with motor complete paraplegia[J]. Spinal Cord, 2008, 46(3):204-209.