The modeling and controlling of electrohydraulic actuator for quadruped robot based on fuzzy Proportion Integration Differentiation controller

Hydraulic actuators are widely used in various kinds of industrial applications. High-power density is key parameters for engineering applications especially for quadruped robots applied in the outdoor environment. Therefore, an increasing number of advanced robots are equipped with hydraulic actuators. In this paper, to compensate the inherent nonlinearities and enhance the performance of the quadruped robot, a hybrid fuzzy controller composed of fuzzy logic controller and Proportion Integration Differentiation controller is evaluated both in simulations and experiments. The control strategy is developed based on the accurate mathematical model. The Matlab Simulink and Fuzzy Logic Toolbox are implemented to accomplish the simulations under flexible loads. Single hydraulic actuator and single leg experiments are accomplished on the specific platforms. Both the simulations and the experimental results indicate that the fuzzy Proportion Integration Differentiation control strategy is capable of fulfilling the specific position tracking under diverse loads. Compared with the conventional Proportion Integration Differentiation controller, the fuzzy Proportion Integration Differentiation controller provided a desirable performance under heavy load with comparatively little response and settling time. Results show that the fuzzy Proportion Integration Differentiation control strategy can effectively achieve the objective of enhancing position tracking robustness under flexible loads and improve the performance of quadruped robot.