Adaptive Control of a Lower Limb Exoskeleton Based on Fuzzy Compensation

A novel adaptive fuzzy approach is proposed for the control system which is used for a lower limb exoskeleton developed by us. In this study, the fuzzy compensation is used to approximate the human-exoskeleton interaction, uncertainties and unmodeled items of the exoskeleton system. Above all, a detailed dynamic model of swing leg is constructed with a consideration of the actuators, and also the human-exoskeleton interaction and uncertainties are taken into account in the dynamic modeling. Then, an adaptive controller with fuzzy compensator which can adjust the control law through the output is designed for the lower limb exoskeleton with a stability analysis. The simulation results showed that the proposed method can effectively help the swing leg to track the desired trajectory with little error. With the presented control strategy, it is able to mitigate the effects of uncertainties, imprecise model and human-exoskeleton interaction to the control of lower limb exoskeleton.