Low-complexity control for exoskeleton robots with funnel performance guaranteed

A low-complexity funnel control scheme is proposed to address the trajectory tracking issue for exoskeleton robots subject to performance constraints. The funnel functions are defined to avoid exceeding the boundaries of time-varying performance constraints. The ‘low-complexity’ nature allows the scheme to deal with uncertain dynamics without employing function approximation to estimate the unknown dynamics online and utilizing an additional adaptation law. Under the framework of backstepping technique, in view of the low-complexity funnel control scheme, a novel performance-constraint control scheme is proposed, for which funnel performance is proven analytically. Numerical studies further demonstrate the method.