An Adaptive Control Approach of Body Weight Support System for Lower Limb Exoskeleton Based on Trajectory Feedforward

An adaptive control method is proposed to resist disturbance while walking with given trajectory. The method contains two parts. The optimal control method of quadratic exponent of linear system is used to avoid random interference caused by unpredicted motion. Considering that the center of gravity (COG) of user varies while walking with lower limb exoskeleton, an estimable systematic disturbance is introduced to the BWS system. And a feedforward control method based on error input is designed to avoid systematic interference. The systematic interference is modeled according to the structure of the leg in lower limb exoskeleton. The complete control approach is the combination of two controllers. Finally, simulations of different control methods have been carried out to prove the effectiveness of the proposed method.