Impact of Electro-mechanical Properties of the Actuation Mechanism on the Peak Power and Energy Requirements of Active Foot Prostheses

Unlike passive ones, active prosthetic feet have the potential to mimic ankle kinematics and kinetics close to those of able-bodied humans. To achieve this goal, however, there are a number of challenges. One of them is the actuation mechanism. In some previous studies, we investigated on the peak power and energy requirements of the active foot prostheses just due to the activity. In other words, these requirements were calculated assuming no power losses in the system. In this study we extend our scope and take into account the electro-mechanical parameters of the actuation mechanism. We investigate, to what extent those peak power and energy requirements would change because of motor inertia, resistance, damping and ball screw transmission efficiency. The results show that resistance has the most influence on the increase of the peak power and energy requirements with respect to their ideal values. The least impact is related to the viscous damping. Furthermore, although these parameters can change the power and energy requirements drastically, they do not necessarily result in the deviation of the optimal stiffness from the ideal value.