Disturbance Rejection With Transmission Torque Constraint Using a Novel EMPC-DSMC Method in Elastic Servo Drive Systems

To effectively address mechanical vibrations, torque constraint and disturbance rejection issues in elastic servo systems, a novel algorithm combining explicit model predictive control (EMPC) and discrete-time sliding mode control (DSMC) is proposed. First, EMPC significantly improves computational efficiency by replacing the fully online computation process of conventional MPC with offline pre-computation of control laws stored in lookup tables. A Luenberger observer is designed for observation and feedback of the system state. Second, compared to conventional DSMC, a nonlinear DSMC method with dual disturbance compensation (DSMCC) is designed. The two compensation terms are added to the sliding mode surface and the control law, respectively. When the system is disturbed, this design enables both sliding dynamics and control inputs to respond rapidly to disturbances, thereby further improving the system disturbance rejection performance. Finally, both simulations and experiments validate that the designed EMPC-DSMCC method offers advantages such as arbitrary torque constraint, high tracking accuracy, fast dynamics, and strong disturbance rejection.