Optimization of Ankle-Foot Prosthesis with Active Alignment by Passive Elements

Today, often ankle’s active prosthesis is used for transtibial amputated people’s walking, because these prostheses have some advantages such as increasing power and decreasing metabolism. In most of active prosthesis in order to create a movement or increase the force at the push-off, electrical actuators are used like a motor. In cases where a higher-power motor is necessary, the capacity, weight and using electricity in motor become increased, which causes problem for people with an amputation. This research is conducted to optimize ankle prosthesis with use of an active alignment which is made by experts. In this prosthesis to reduce the motor power, a passive element of spring is used in order to save energy while walking and release it in push-off. After setting spring position in the prosthesis, the dynamic and kinematic analysis are done and eventually the amount of used force in both modes of spring and non-spring would be compared. The results show that the presence of spring in the selected mechanism would cause motor to perform force increase and power reduction to mechanism at the push-off phase.