Double Extended Sliding-Mode Observer-Based Synchronous Estimation of Total Inertia and Load Torque for PMSM-driven Spindle-Tool Systems

This article proposes a double extended sliding-mode observer-based (DESMO-based) synchron- ous estimation method of total inertia and load torque for complex permanent magnet synchronous motor (PMSM)-driven spindle-tool systems with time-varying properties. The novel DESMO is designed by extending double recursive equations from a sliding-mode observer of the motor speed to observe the total inertia and the load torque simultaneously, and the corresponding convergence conditions are analyzed in theory. Additionally, a robust activator is introduced to suppress the coupling effect of the observation errors between the total inertia and the load torque. The simulation results show that, compared with two existing methods, the proposed DESMO-based method has satisfactory robustness to the modeling errors and small sensitivity to the algorithm parameters. Furthermore, experiments were performed on a roller grinding machine, and the results validate the effectiveness of the proposed method, especially the robustness to the time-varying friction torque and the sampling noise.