Finite Element Analysis of Piezoelectric Strips for Modifying Ankle Torques in Active Prosthetic Feet: A Pilot Study

Over the last fifty years there has been a steady advance in prosthetic foot technologies. These advances have primarily focused on more accurately mimicking the biologic foot for amputees. One field of research currently being explored is active/powered prosthetic feet in which the movement of the foot is actively controlled through the use of electric motors. Some of these feet also seek to reproduce the ankle torques seen in the biologic foot. This paper proposes a novel method for more accurately reproducing these ankle torques through the use of piezoelectrics in conjunction with the electric motors. FEA software is used to simulate the modification of ankle torques through the use of piezoelectric bending actuators in a general case. A number of different configurations for the piezoelectric strips are examined to test the versatility of the piezoelectrics in this application. The general trends of the ankle torque vs gait cycle found in the literature have been reproduced in the simulations.