Robust model reference adaptive control for five-link robotic exoskeleton

Abstract

In this paper, H∞-based model reference adaptive control (MRAC) for controlling five-link lower limb robotic exoskeleton is developed during the single support phase with uncertainties and unknown external disturbances. Unlike classical MRAC, the presented scheme using H∞ control and MRAC with adaptive error gain is proposed under uncertain parameter vector and external disturbance. For robustness, H∞ method is applied to minimise the impact of perturbation. Moreover, robust asymptotic stability of the overall system is investigated by Barbalat Lemma selecting a suitable Lyapunov functional candidate. Finally, the efficacy of developed scheme is validated by a relevant example.