An above-knee prosthesis with magnetorheological variable-damping

This work presents the design of a variable-damping prosthesis for above-knee amputees. The proposed low cost system is self-contained and based on a four-bar polycentric mechanism, in which a magnetorheological linear damper is integrated to enable variable-damping control. The paper also describes a control strategy based on a Finite State Machine, which will modulate the damping level according to the actual state of the gait cycle. Preliminary tests on an amputee subject provided a satisfactory performance of the system while operating in the passive mode, i.e., simulating situations when the battery runs out, and also enabled correct identification of gait events.