Upgrading linear to sliding mode feedback algorithm for a digital controller

The goal of this paper is to investigate if it is possible to upgrade a given linear controller to a sliding mode one with an improvement of the control performance. Starting from a given linear controller, a design procedure for a sliding mode control having better performance than the linear one, is proposed. If the system has disturbances, which is always the case in experiments, the upgraded sliding mode control brings also a better robustness with respect to the given linear robust controller. The main idea is to divide the state-space into two areas, introducing a design parameter which separates the area of the linear control from the area of the sliding mode control. Some issues related to the chattering reduction are discussed. The control scheme’s efficiency is demonstrated experimentally on a rotary inverted pendulum. The experimental results demonstrate the effectiveness of the obtained controls, and show an improvement with respect to the given linear proportional control.