Application and Comparison of Finite State Control of Above-Knee Prosthesis with Pneumatic Cylinder at Different Phases

In this study, performance test results of "various phases state control" of the semi active knee joint with pneumatic damper have been presented in a comparative manner. Performance tests have been conducted with natural human gait and prosthetic gait via image based motion measurement system and sensor based motion measurement system. Subjects are realized gait onto treadmill with different gait velocities as 1 km/h, 2 km/h and 3 km/h. The phase control of the prosthetic gait is performed under two phase, three phase and five phase scenarios. Under the facts drawn by these performance tests, the optimum control strategy related to phases of gait can be determined in a qualitative fashion and the response of the developed prosthesis under different gait velocities can be measured successfully. Mean absolute knee angle error results from natural gait and prosthetic gait are considered as performance criteria, derived from image based motion measurement system. It is concluded that the response time of the stepper motor causes a major limitation onto proper control over the pneumatic cylinder based prosthesis and associated conclusions are shared.