Principles of obstacle avoidance with a transfemoral prosthetic limb. (bibtex)
by Helco G. van Keeken, Aline H. Vrieling, At L. Hof, Klaas Postema, Bert Otten
Abstract:
In this study, conditions that enable a prosthetic knee flexion strategy in transfemoral amputee subjects during obstacle avoidance were investigated. This study explored the hip torque principle and the static ground principle as object avoidance strategies. A prosthetic limb simulator device was used to study the influence of applied hip torques and static ground friction on the prosthetic foot trajectory. Inverse dynamics were used to calculate the energy produced by the hip joint. A two-dimensional forward dynamics model was used to investigate the relation between obstacle-foot distance and the necessary hip torques utilized during obstacle avoidance. The study showed that a prosthetic knee flexion strategy was facilitated by the use of ground friction and by larger active hip torques. This strategy required more energy produced by the hip compared to a knee extension strategy. We conclude that when an amputee maintains enough distance between the distal tip of the foot and the obstacle during stance, he or she produces sufficiently high, yet feasible, hip torques and uses static ground friction, the amputee satisfies the conditions for enable stepping over an obstacle using a knee flexion strategy.
Reference:
Principles of obstacle avoidance with a transfemoral prosthetic limb. (Helco G. van Keeken, Aline H. Vrieling, At L. Hof, Klaas Postema, Bert Otten), In Med Eng Phys, 2011.
Bibtex Entry:
@ARTICLE{2011a,
  author = {{van Keeken}, Helco G. and Vrieling, Aline H. and Hof, At L. and
	Postema, Klaas and Otten, Bert},
  title = {Principles of obstacle avoidance with a transfemoral prosthetic limb.},
  journal = {Med Eng Phys},
  year = {2011},
  month = {Dec},
  __markedentry = {[hvk:]},
  abstract = {In this study, conditions that enable a prosthetic knee flexion strategy
	in transfemoral amputee subjects during obstacle avoidance were investigated.
	This study explored the hip torque principle and the static ground
	principle as object avoidance strategies. A prosthetic limb simulator
	device was used to study the influence of applied hip torques and
	static ground friction on the prosthetic foot trajectory. Inverse
	dynamics were used to calculate the energy produced by the hip joint.
	A two-dimensional forward dynamics model was used to investigate
	the relation between obstacle-foot distance and the necessary hip
	torques utilized during obstacle avoidance. The study showed that
	a prosthetic knee flexion strategy was facilitated by the use of
	ground friction and by larger active hip torques. This strategy required
	more energy produced by the hip compared to a knee extension strategy.
	We conclude that when an amputee maintains enough distance between
	the distal tip of the foot and the obstacle during stance, he or
	she produces sufficiently high, yet feasible, hip torques and uses
	static ground friction, the amputee satisfies the conditions for
	enable stepping over an obstacle using a knee flexion strategy.},
  doi = {10.1016/j.medengphy.2011.11.017},
  institution = {Center for Human Movement Sciences, University Medical Center Groningen,
	University of Groningen, Groningen, The Netherlands.},
  language = {eng},
  medline-pst = {aheadofprint},
  owner = {hvk},
  pii = {S1350-4533(11)00308-0},
  pmid = {22197358},
  timestamp = {2012.08.21},
  url = {http://dx.doi.org/10.1016/j.medengphy.2011.11.017}
}
 
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