A fuzzy sliding mode approach for the two-mass system

This paper presents a new speed control method for a so called two mass system. To achieve a good performance, the state variables are divided into two groups. The sliding surface is designed in a reduced order state-space and the remaining state variables are controlled by a fuzzy method. Two control loops are proposed, the outer angular speed control loop based on fuzzy logic calculates the reference signals (in other words the sliding manifolds) for the inner loop, where the torsion of the shaft is handled as a variable under control. An observer based discrete-time sliding mode (ODSM) control is implemented in the inner loop. The simulated system consists of a conventional DC servo gear motor with encoder feedback and inertia load coupled by a flexible shaft