Highly robust position control of BLDDSM using an improved integral variable structure systems

A highly robust position controller for brushless direct drive servo motors (BLDDSM) is presented using a new improved variable structure system with an integral-augmented sliding surface. With the proposed technique, the reaching phase is completely removed by the integral sliding surface. The dynamics of its ideal sliding mode is analytically obtained from a given initial condition to the origin without any reaching phase. In order to choose a suitable integral sliding surface, the optimal regulator theory is effectively applied. Moreover, the suggested control technique can exhibit the output response identical to that previously designed in the integral sliding surface for all the load variations and parameter uncertainties. The usefulness of the proposed algorithm is illustrated through the comparative experiment studies on the position controls of BLDDSM under load variations.