In this paper, design a composite of sliding mode controller for a water tank level system to accomplish the liquid level control. The schemes of this paper, we considered a cascade of mechanical subsystem and electrical subsystem, and lead out a auxiliary error function concept, using a back-step like method to design a composite sliding mode controller for the mechanical subsystem and the electrical subsystem, respectively, finally, improving the control performance of. the water tank level system response. Through the real model simulation testing, in the case of step, continuous step and successive variation command input, the experimental simulation results show that the propose control scheme has better of tracking precision and rising time performance than that the controller design of the simplify system.
