Research on Fuzzy Sliding Mode Electro-hydraulic Proportional Servo Control System under Negative Load Conditions

Aimed at the error caused by spool dead-zone and cylinder asymmetry in proportional valve-controlled asymmetric hydraulic cylinder control, a fuzzy sliding mode controller with variable dead-zone compensation is designed, and the control accuracy and stability of this controller under no-load and negative load conditions are studied. The simulation results show that the sliding mode control method with variable dead-zone compensation can reduce the tracking errors and hysteresis caused by the dead-zone characteristics of the spool and the asymmetry of the cylinder. In the no-load test, the maximum tracking error of sliding mode control method with variable dead-zone compensation is ±5 mm, while the maximum tracking error of fuzzy sliding mode control method with variable dead-zone compensation is ±2.5 mm. In the negative load test, by adding the counterbalance valve, the problem of shaking when the piston rod extends under the negative load of 20 kg is solved.