Robustness Improvement of an Electro-Hydraulic Servo System Using a Switching Fuzzy-PID Controller

Electro-hydraulic servo systems are widely used in industrial applications but suffer from performance degradation due to inherent nonlinearities such as valve dead zones, friction, and asymmetric cylinder characteristics. To address these challenges, this study proposes a switching fuzzy-PID composite control strategy that, by setting a reasonable error threshold, dynamically selects the appropriate controller based on the magnitude of the tracking error. The controller was validated through both simulation and experimental implementation. Results demonstrate that the proposed method significantly improves system robustness, achieving faster response, nearly eliminating overshoot and steady-state error, and reducing tracking error and delay. Robustness tests under varying signal frequencies (0.2-0.25 Hz) and loads (0-10 kg) confirm its enhanced adaptability, making it a practical solution for high-performance electro-hydraulic servo control.