ON THE EFFICIENCY OF FUZZY LOGIC APPLICATIONS IN HYDRAULIC ACTUATOR CONTROL SYSTEMS

The paper considers the possibility to apply intelligent controllers as setting devices and adjusters of hydraulic actuators of different purpose. The authors proposed a method of positioning control of a hydraulic steering actuator based on a fuzzy logic controller (FLC). FLC corrective action is implemented based on three input parameters similar to the traditional proportional-integral-derivative controller. To evaluate the efficiency of FLC application in the system of hydraulic actuator positioning, the authors developed a mathematical model describing the work of a complex electro-hydromechanical system including electromechanical converter, fluidic hydraulic actuator, and hydraulic cylinder actuator. Non-linear mathematical model of an electro-hydraulic servo is implemented in MatLab Simulink software; the proportional-integral-derivative FLC was formed using the Fuzzy Logic Toolbox means. The authors set the FLC parameters using the linguistic rule-based expert system and the change in the membership function form, varying which it is possible to get linear and non-linear output characteristics. The obtained piecewise-linear hyperplane of FLC controlling characteristic determining the non-linear nature of correction theoretically allows getting the improved quality of transient processes. Using the numerical experience method, the authors assessed the efficiency of control algorithms with traditional controllers and the equivalent fuzzy controllers within the known mathematical model of a control object (electro-hydraulic follower actuator). When synthesizing the proportional-type FLC, the authors formed the nonlinear control law which allowed compensating the nonlinearity of the hydraulic actuator system. When implementing the linear dependence of the proportional-integral FLC, the system demonstrates the behavior attributable to the traditional controller. Generated FLC with nonlinear characteristics did not show significant quality improvement of the transient process compared to the traditional controller. Based on the received results, the authors concluded the reasonability of FLC application within the control systems with hydraulic actuating elements.