Funnel tracking control for nonlinear servo drive systems with unknown disturbances.

In this paper, a novel robust tracking control strategy based on funnel control is proposed for servo drive systems with unknown disturbances. A modified funnel variable is defined and incorporated into the control design to guarantee the tracking error within a prescribed boundary. To reject the bounded disturbances, a robust integral of the sign of the error (RISE) controller based on the funnel variable is proposed for servo drive systems. Moreover, the desired compensation technique is incorporated into the developed controller to reduce the sensor noise. The proposed robust controller theoretically guarantees asymptotic tracking control performance with external disturbances. The closed-loop system convergence is analyzed via the Lyapunov stability theory. Comparative numerical and experimental results of the servo drive system are provided.