Trajectory Tracking for Swing Phase of the Lower Limb Exoskeleton In this paper, the dynamic model of swing phase of the lower limb exoskeleton is firstly established. Based on the proposed model, system identification experiments at each joint are conducted to determine unknown parameters and joint friction torques by tracking desired reference signals. The experimental data are processed by the least squares method. Another validation experiment is taken to verify the accuracy of the estimated model. Both linear and nonlinear controllers are designed. The linear controller is a proportionalderivative (PD) controller, and the nonlinear controller is a PD controller with gravity and friction torque compensation. Experiments show that the transient response of the tracking performance of the nonlinear controller is significantly better than that of the linear controller.

Lower Limbs Exoskeleton Control Strategy Based On Optimized Compliance Algorithm Aiming at achieving the compliance control of lower limbs exoskeleton, a compliant control strategy basing on optimized compliance algorithm was proposed. The motion trajectory of human body was collected by using inertial sensors and electromyography sensors, and the information is taken as the reference information to the exoskeleton robot. By introducing muscle activation degree as the feedforward loop to offset the hysteresis phenomenon which is shown in the process of movement, the following movement achieved compliant. The feasibility of this control method is both verified on the simulation software platform and physical prototype. The experimental results show that this control method is effective and feasible in the lower limbs exoskeleton system.