A modified discrete-time sliding mode control for proximate time-optimal servomechanisms

In this paper, a modified discrete-time sliding mode control for proximate time-optimal servomechanisms is proposed in order to improve the performance of point-to-point motion in a 2nd-order damped linear system. The proposed method consists of a proximate time-optimal control, a time varying sliding mode control, and a variable convergence rate factor in discrete-time. Three sufficient conditions are also proposed to ensure the stability of the suggested scheme. The variable convergence rate factor is implemented in the discrete-time sliding mode control in order to eliminate the overshoot problem and reduce the settling time. The proposed controller was applied to a scanning probe microscope-based data storage system so as to compare its performance to that of a proximate time-optimal servomechanism and a sliding mode proximate time-optimal servomechanism.