SPEED-ADAPTIVE REFERENCE KNEE TRAJECTORY GENERATION BASED ON FOURIER FUNCTIONS

For the intelligent control of lower limb prostheses, kinematic reference trajectories are required. Due to individual difference and various preferred reference walking-speed, a general reference knee angle trajectory is difficult to adapt different people and their different walking speed. To solve this problem, gait kinematic information of thirty healthy subjects was collected at their preferred speeds and the relationship between kinematic models of knee joint and speeds was analyzed. Each knee angle trajectory was modeled based on Fourier functions, and the parameters of models were proved to be related to walking speed. Finally, kinematic models for knee angle trajectories were reconstructed based on regression equations. The reconstructed trajectories not only can adapt to the various walking-speeds, but also adapt to different people. The result of analysis showed that the reconstructed trajectories matched the measured motion trajectories well.