Design and Simulate Analysis on Fuzzy Sliding Mode Controller in High Precise Electro-Hydraulic System

There are two remarkable characteristics of sliding mode control system. One is its strong robustness about parameter perturbation and external disturbance, the other is chattering caused by no ideal switching action. At present, chattering is main obstacle of this control theory to engineering application. This paper designs a fuzzy sliding mode controller, which uses fuzzy logic to obtain equivalent control signal after system states reaching sliding manifold. As a result, high-frequency chattering caused by switching action is weakened effectively. Moreover, the equivalent control can restrain unknown external disturbance well. In order to design a good fuzzy controller without professional experience, membership functions of output linguistic variable and control rules are optimized by means of genetic algorithm simultaneously. Simulate result shows that the proposed controller adequately satisfies control demand of an electro-hydraulic system with large moment of inertia of load. Furthermore, it is insensitive to parameter perturbation, external disturbance and uncertainty of system model. The controller exhibits excellent performance.