Problem statement: While classical PID controllers are sensitive to variations in the system parameters, Fuzzy controllers do not need precise information about the system variables in order to be effective. However, PID controllers are better able to control and minimize the steady state error of the system. To enhance the controller performance, hybridization of these two controller structures comes to one mind immediately to exploit the beneficial sides of both categories. Approach: A hybrid fuzzy PID controller for the Electro-Hydraulic Position Servo System (EHPSS) was proposed in this study. The proposed control scheme was separated into two parts, fuzzy controller and PID controller. Fuzzy controller was used to control the piston when the piston locates far away from the target position. PID controller is applied when the piston is near the desired position. Results: We demonstrated the performance of control scheme via experiments performed on the EHPSS. Conclusion:The results from the experiments showed that the proposed hybrid fuzzy PID controller has superior performance compared to individual PID controller and fuzzy controller.

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Existing fuzzy control methods do not perform well when applied to proportional hydraulic systems (PHS) containing nonlinearities arising from unknown deadzones. In this paper, a two-layered fuzzy logic controller is proposed for controlling a PHS with deadzones. The two-layered control structure consists of a fuzzy logic-based precompensator followed by a usual fuzzy PD controller. This system was implemented for PHS position control. The results show that a two-layered fuzzy logic controller has superior performance compared to usual fuzzy PD controller. In addition, the proposed scheme is robust to disturbance.

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