Title :
The effect of joint stiffness on simulation of the complete gait cycle
Author :
Scheiner, Avram ; Ferencz, Donald C. ; Chizeck, Howard J.
Author_Institution :
Gait Lab., Cleveland V.A. Med. Centre, OH, USA
Abstract :
A computer simulation of paraplegic, walker assisted gait through multiple gait cycles is described. Computational problems associated with changing constraints during transitions between phases of gait are avoided by modeling foot-to-floor contact as an external force. Net joint torques, computed from kinematic data by inverse dynamics and transformed into sine functions, are used to drive limb motion. Model instability is overcome by emulating the effects of `stiffness´ at the joints by using proportional-derivative (PD) controllers. Maximum joint torques needed to achieve stable gait were found to be within normal physiological range. Joint kinematics and foot contact forces generally followed a normal gait pattern producing a forward displacement of approximately 0.8 m/s at a walking frequency of 0.5 Hz. The most significant deviation from a normal walking pattern was excessive hip abduction during stance phase causing a waddling (medial-lateral sway) motion. A quantitative measurement of the dynamic stability of the simulation is calculated based on Floquet theory
Keywords :
biocontrol; biomechanics; digital simulation; kinematics; legged locomotion; medical computing; muscle; neurophysiology; physiological models; torque; 0.5 Hz; Floquet theory; complete gait cycle simulation; computer simulation; dynamic stability; excessive hip abduction; foot contact forces; foot-to-floor contact; forward displacement; gait phases; inverse dynamics; joint stiffness; kinematic data; limb motion; medial-lateral sway; model instability; multiple gait cycles; net joint torques; normal gait pattern; normal physiological range; paraplegic walker assisted gait; proportional-derivative controllers; sine functions; stance phase; waddling motion; walking frequency; Computational modeling; Computer simulation; Foot; Frequency; Hip; Kinematics; Legged locomotion; PD control; Proportional control; Stability;
Conference_Titel :
Engineering in Medicine and Biology Society, 1994. Engineering Advances: New Opportunities for Biomedical Engineers. Proceedings of the 16th Annual International Conference of the IEEE
Conference_Location :
Baltimore, MD
Print_ISBN :
0-7803-2050-6
DOI :
10.1109/IEMBS.1994.411991
