Speed control using sliding mode theory for an axis with constraints

An application of the theory of variable structure control associated with the sliding mode is presented. The servomotor consists of an electrical actuator and an elastic two-mass system. Equivalent control in the sliding mode was used to place the poles in order to achieve optimal dynamic behavior. The axis includes a backlash and an elastic joint, where the torque is not measurable; thus a reduced observer is built to reconstruct this state variable. A simple implantation procedure is proposed. Numerical simulation results are given to illustrate the application of the proposed technique