Gait analysis of powered bionic lower prosthesis

With the demand of active prosthesis continuing to rise, the necessity of developing stable humanoid robots and intelligent leg prosthesis becomes more and more important. This paper presents a closed-loop position servo system of the powered prosthesis, which is designed according to the moving feature of human leg, and consists of the position, velocity and current feedback. Based on bionics principle, this lower limb prosthesis is simplified as rigid body structure and its joints as single-axis mechanism. This paper uses servo motors to drive its thigh joint and knee joint, sets up non-linear dynamics model and adopts PD control algorithm to improve the robustness, speed of response, intelligent behavior and position accuracy of this servo system. The gait parameters of healthy young people walked in different constant pace were collected, its joints angle are regarded as input signal of this system to achieve gait imitation. The result indicates that the multi-axis artificial leg can simulate normal human gait well.