Fuzzy Sliding Mode Controller Design For 3-DOF Helicopter Model

Helicopter is one of the most unique inventions in the 20th century, it expands the application range of aircraft. Helicopter has the notable features of hover, vertical take off and land, rotary flight, flexible and takes little space, and helicopter becomes increasingly important in both military and civilian application. With the rapid development of science and technology, control theory and technology of helicopter comes to an important stage. The 3-DOF helicopter model designed by Quanser company is a simulation platform for real helicopter mechanical and electronic system. It is complicated as a MIMO system with uncertainty and nonlinear, so it is not easy to control. High-performance controller design for this model is a guide for relative controller design and control theory study.Firstly, the composition of this platform was analyzed and mathematical model was established, after reducing the model, the system was analysis as open loop unstable, fully controllability, and observability. Then PID controller and LQR controller were designed in MATLAB, simulation results demonstrated that these controllers can track the desired gesture stably, but exit overshoot and the robustness is not good.Sliding mode controller has the advantages of fast response and strong robustness. In this paper, optimal sliding mode controller based on LQR was designed to enhance robustness and quick response. However, this improvement brought two negative impacts: system chattering at the sliding mode and intense response when system state is far from the" sliding mode. Then fuzzy rules for compensation voltage and weight parameter were designed to solve these problems. Simulation explained that the new controller made the system not only robust steady and responded quickly, but also reduced the chattering and avoid serious response.Then, LQR controller, optimal sliding mode controller and fuzzy optimal sliding mode controller were applied to the helicopter platform. Experiment showed that these controllers can make the system stable, while LQR controller was soft, slow, of overshooting, not so robustness. Optimal sliding mode controller was quick, robust steady, but when the point was far from the sliding mode, it responded fiercely, and the voltage switched very seriously. Finally, with the fuzzy logic, the controller performance not only quick and robust steady, but also soft and smooth.