Reference Sliding Variable Based Chattering-Free Quasi-Sliding Mode Control

The aim of this study is to design a new sliding mode controller with disturbance compensation for disturbed sampled data systems. As in such systems, the state measurements and control signal updates take place at the discrete time instants only, discrete time sliding mode analysis must be applied. Considering previous findings in this field, a new quasi-sliding mode controller, based on a reference sliding variable profile is developed. In order to eliminate the chattering problem, the reference is generated with a simple, nonswitching type reaching law. Next, the reference is incorporated into the control law for the real disturbed system. This approach limits the disturbance influence on the plant and results in an ultimate band width of O(T) order. Furthermore, the proposed control strategy is extended with a disturbance compensation method, which allows to achieve the quasi-sliding mode band width of O(T
²
) order. Hence, the system's robustness improves with each reduction of the discretization period T. The paper clearly shows that the proposed sliding mode controller guarantees stability of the closed-loop system and eliminates the chattering phenomenon.