Time sub-optimal/sliding mode controller for a flexible structure

This paper describes the combined design of a time-optimal and a sliding mode controller for a single-axis, one-mode model of a flexible slewing structure, where the goal is the real-time implementation of a fast controller. The model of a flexible aluminum link with torque actuation (DC motor) at its hub is considered in modal coordinates, and a previously introduced time-optimal torque law for this system that can be implemented in real time is used. A sliding-mode controller for the DC motor is designed so that the torque generated by the motor converges to the desired time-optimal torque law. Computer simulations are included in this paper to illustrate the design idea.