Finite time non-singular terminal synergistic control of hydraulic servo system considering time-varying disturbance

This paper introduces a novel control strategy combining a hybrid nonlinear disturbance observer with a finite-time synergistic control approach for hydraulic servo systems, focusing on compensating time-varying disturbances and suppresses chattering. Recognizing the critical challenges posed by these disturbances and the chattering phenomenon in hydraulic servo systems, our work offers significant advancements in enhancing system robustness and control precision. Through meticulous classification and handling of matched and unmatched disturbances, the study unveils a dual-channel finite-time disturbance observer capable of simultaneously addressing both disturbance types with high accuracy, particularly focusing on the often overlooked and challenging to observe friction effects. Key contributions include the pioneering integration of cooperative control theory with sliding mode control, employing fractional-order terms to minimize chattering, thereby improving system stability. The experimental evaluation underlines the proposed controller’s superior performance over traditional control strategies, including PID, TSMC, and SMC, under both low and high-frequency operational conditions. Notably, the proposed FTNTSC controller demonstrates exceptional robustness and effectiveness, with significantly lower performance degradation when transitioning from low to high-frequency conditions compared to its counterparts.