Safety Velocity Tracking Control for an Omnidirectional Rehabilitative Training Walker with Uncertainty

In this study, a new nonlinear trajectory tracking method with safety velocity constraints is proposed for omnidirectional rehabilitative training walker. The controller with safety velocity performance is formulated by considering the uncertain variable parameters based on an estimator. According to robust control technique and Lyapunov theory, the safety velocity controller can be designed to maintain stability in terms of solutions of linear matrix inequalities. The sufficient condition for the existence of such a controller with safety velocity constraints performance is derived. As an application, simulation results confirm the effectiveness of the proposed method and verify that the walker can provide safe training velocity.