Cascaded Quasi-Resonant ESO-Based Active Disturbance Rejection Speed Control for Robotic Joint PMSMs

Introduction: Smooth speed regulation of permanent magnet synchronous motor (PMSM) drivers in robotic joints is crucial for achieving precise and flexible grasping. In conventional speed control loops, both aperiodic and periodic disturbances can cause speed fluctuations, reducing disturbance rejection capability and hindering high-precision operations. This paper proposes a cascaded quasi-resonant extended state observer-based active disturbance rejection control (CQR- ESO-ADRC) strategy to achieve high-precision and robust control of robotic joint PMSMs. Methods: A cascaded active disturbance rejection control (ADRC) strategy is implemented by replacing the traditional proportional-integral (PI) controller with a parallel structure composed of an extended state observer (ESO) and a quasi-resonant (QR) controller. In this scheme, the ESO is primarily responsible for estimating and compensating for aperiodic disturbances, while the QR controller suppresses periodic disturbances. Results: Analysis of the transfer functions associated with disturbances demonstrates the disturbance- rejection capability of the ESO against aperiodic disturbances and that of the QR controller against periodic disturbances. Simulation experiments verify that the proposed strategy improves speed accuracy by enhancing overall disturbance suppression. Discussion: The proposed cascaded quasi-resonant extended state observer (CQR-ESO) effectively suppresses both periodic and aperiodic disturbances in the speed control loop. The parallel configuration of the quasi-resonant controller and the extended state observer allows for simultaneous estimation and compensation of periodic and non-periodic disturbances, respectively. Conclusion: Compared with conventional PI control and ESO-ADRC, the proposed CQR-ESO-ADRC demonstrates superior dynamic performance and disturbance rejection capability, offering an effective solution for high-precision speed control of robotic joint PMSMs.