Trajectory Design and Adaptive Impedance Control of Lower Limb Exoskeleton

Abstract

This paper proposes a novel human-in-loop control framework for the lower limb exoskeleton, assisting the pilot to move under different working conditions. Under the premise of ensuring the stability of the exoskeleton, the method of Zero Moment Point (ZMP) theory is used to generate the expected motion trajectory of the exoskeleton under different working conditions. In order to ensure the comfort of the pilot, an adaptive impedance controller is designed. The controller has a double closed-loop structure. The position loop realizes the exoskeleton tracking the desired trajectory, and the impedance control loop adjusts the impedance parameters to ensure the comfort of the human body. Then Lyapunov s definition was used to prove the stability of the control framework. The simulation results show that the proposed scheme can help pilots complete walking on a plane, climbing and squatting movements.