Ali Razzazan - Department of Mechanical Engineering, University of Tehran, Tehran, Iran
Mohammad Shokri - Department of Electrical and Computer Engineering, University of Tehran, Tehran, Iran
Mohammadreza Razzazan - Department of Mechanical Engineering , Iran University of Industries and Mines, Tehran, Iran

Fuzzy sliding mode control is a procedure that can be used to control systems with severe nonlinearities and also unknown systems. In this paper Fuzzy sliding mode control is used to control an electro-servo hydraulic actuator. Because of nonlinearity and complicated model of such systems, conventional linear control methods are unable to control them. To implant Fuzzy sliding mode controller, a number of rules are obtained by use of sliding mode control theory, then using the obtained rule base, and scalar function s and its derivative as fuzzy control inputs, the control signal is obtained and can be feed to the plant as input to the valve. The control objective is to make system follow a desired load actuation pressure that is time-variant and also dependent on the system internal friction force. Two models for friction force is considered in this paper, the first model only considers viscous friction, but the other model includes static, Stribeck and viscous friction together. Results show that using this method the phenomenon chattering does not occur and also system follows its desired state within a second. By exerting noise on the power supply of the system it is found out that Fuzzy sliding mode controller cannot eliminate noise from the system and use a high-frequency filter might be considered.

Electro-servo hydraulic actuator, Fuzzy sliding mode control, Stribeck friction effect, nonlinear control