Chatter reduction in variable structure control

Several techniques for eliminating or reducing chatter in variable structure control systems are reviewed in this paper. The authors also propose a new technique that uses two filters: one to place control chatter in an acceptable part of the control loop, and a second filter for synthesis of a linear sliding surface and approximation of a state estimator. Other approaches that are reviewed include: (1) continuous approximation of switching control, (2) adjustment of switching gains, and (3) the use of state observers. Several design examples are included to help illustrate merits and differences of the various approaches