The Study Of Variable Structure Control With Sliding Mode In The Applicatioin To Aerocraft Attitude Controlling System

Variable structure control with sliding mode (VSS) was firstly proposed by Emelyanov, a Soviet researcher, in the 1950s. It was gotten most attention because of its excellent invariance to the change of system parameters ,external disturbance, namely complete robustness. During the 50 years, it has been applied in all sorts of controlling fields such as robot, technical control, Aeronautics & Astronautics etc. However, it has its own disadvantage that after the system state getting to the sliding surface, it will produce high frequency chattering around the sliding surface. The chattering is very harmful to the control.The paper makes some research of VSS, especially the controller and the chattering. We summarize the design step of the controller and the methods of the weakening chattering. The paper reasons the dynamic equation and the kinematic equation of the attitude based on the unit quaternion by means of the description of the attitude parameter. The paper also makes research of aerocraft attitude controlling system and applies VSS to it. The aerocraft attitude control is divided into two parts: attitude stabilization and attitude track. We designed two controllers of the attitude stabilization using the Lyapunov's direct method. The two controllers were proved correct.Finally, the paper designed an aerocraft attitude tracking controller with VSS based on error quaternion. We make simulation to the controller. Simulation results show that the controller has excellent robustness to the system uncertainties and the external disturbance and perfect dynamic performance.