Analytical Study on Control of Above-Knee Prosthesis in Swing Phase

The performance of the knee component of above-knee prosthesis greatly affects the gait of the user. Recently, the intelligent knee joint that can adapt itself to the change of walking speed has been developed. The purpose of this study is to develop above-knee prosthesis that is able to be automatically adapted to various gates by using simple and passive control units at the knee joint. In this paper, control of the knee joint in swing phase of the gate cycle is analytically investigated by using a simplified dynamic model of a lower limb. As the result, it was clarified that the control of viscosity of the knee was more effective to change the pace than the control of inertia of the shank and the friction force. In addition, it was also clarified that extension torque was required at the knee joint in the latter half of the swing phase under the condition of instructed step size and pace