Dynamic-Decoupling Robust Integral Sliding-Mode Control for Performance-Degraded Electromagnetic Actuators

Abstract

This paper proposes an adaptive robust integral sliding-mode control (ARISMC) strategy centered on dynamic decoupling to address control-performance degradation in electromagnetic actuators for reciprocating compressors caused by coil aging and spring fatigue. First, a nonlinear electromechanically coupled model incorporating electromagnetic, mechanical, and circuit dynamics is developed and validated using test-rig data; the correlation coefficients between the experimental and simulated displacement responses are all above 0.95. A controller is then constructed by integrating backstepping-based dynamic decoupling, nonsingular terminal integral sliding mode, dynamic-surface filtering, and adaptive disturbance compensation. Conditions are established under voltage, current, sampling, and boundary-layer constraints to ensure bounded closed-loop signals and finite-time entry of the displacement- and current-loop sliding variables into a compact neighborhood. Under the 50% constant-load condition, ARISMC achieves an MAE of 0.0013–0.0021 mm under the tested degradation conditions, with a detected timing offset below 0.1 ms; under constant loads of 30%, 70%, and 90%, its maximum RMSE is 0.004600 mm. Under random variable-load operation and eight degradation conditions, its MAE remains within 0.001–0.002 mm, the detected timing offset is below 0.1 ms, and no sustained loss of tracking occurs. Ablation and post-tuning sensitivity results show that dynamic decoupling/compensation is the principal source of performance improvement, the integral sliding mode further reduces residual error, and adaptive compensation provides a modest, condition-dependent gain. The results demonstrate high tracking accuracy and parameter robustness within the degradation and load-switching simulation scenarios considered and provide a basis for subsequent closed-loop hardware validation.