REACHING CONDITIONS FOR VARIABLE-STRUCTURE CONTROL WITH OUTPUT-FEEDBACK

A design technique for satisfying the reaching condition when applying variable structure control to a linear system with output feedback is described. The control consists of a linear feedback term and a disco ntinuous feedback term. By combining the linear term with the disconti nuous term, very good disturbance rejection and robustness can be achi eved with a lower control effort than would be required from either co ntrol when used independently. The linear gain and the discontinuous g ain are designed so that the sliding surface exists and is globally re achable. Furthermore, the time spent in the reaching phase can be redu ced by proper selection of a scalar parameter that is imbedded in the linear-gain matrix. A specific algorithm is given along with a numeric al example.