Sliding controller design for servo drive systems subject to mechanical and electrical perturbations

In this paper, control of a servo drive subject to both mechanical and electrical perturbations is addressed. Due to the existence of the external perturbations, it will be shown that the control system turns into a system with mismatched disturbances. Under this circumstance, tracking performance would be limited by the size external disturbances. To solve this problem, a synthetic control strategy including a robust nonlinear PI(proportional integral)-type controller and a sliding controller is developed. The corresponding control parameters are determined through a formulation of linear matrix inequalities (LMIs). Simulations show that asymptotic tracking performance can be guaranteed even in the presence of both mechanical and electrical external perturbations.