A bilateral electro-hydraulic actuator system to measure dynamic ankle joint stiffness during upright human stance

A bilateral electro-hydraulic actuator system has been developed to measure the dynamic joint stiffness of the human ankle during standing. The apparatus consists of two foot pedals that are each connected to an electro hydraulic rotary actuator. Transducers are incorporated to measure the position and torque of each actuator, the angle of the ankle with respect to the foot plate, and the positions of the knee and hip. Nonlinear identification techniques will be used to determine the reflex contribution to the overall torque.