On Design of an Ankle Prosthesis with a Series and Parallel Elastic Actuator for Sagittal Movement and a Passive Inversion-Eversion Joint

Series and Parallel Elastic Actuators (SPEA) provide many advantages in torque control of the prosthesis and reducing the peak power and energy requirements. In this paper, we design the ankle prosthesis with one passive joint for ankle inversion and eversion movement and one active joint for dorsiflexion and plantarflexion of the ankle by employing the SPEA. Design parameters such as length of the links and stiffness of springs are selected optimally to minimize the error between the human intact leg and designed prosthesis torque-angle curve of the ankle joint. This torque-ankle curve causes the same stiffness of the prosthesis to the human body and subsequently the same walking gait properties.

Nafise Faridi Rad1, Aghil Yousefi-Koma2, Moosa Ayati3, Mohammad Ali Bazrafshani4 1,2,4- Center of Advanced Systems and Technologies (CAST),School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran. 3- Advanced Instrumentation Lab, School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.