基于LMI方法的电液舵机动刚度H_∞控制器分析与设计

The stiffness of a steering gear determines the control ability of the aircraft to the position of the rudder. When the aircraft is moving, with the change of the load disturbance frequency of the rudder, the stiffness characteristics are also changing. If the stiffness of a frequency point is minimum, the rudder surface is drastically jitter, and the safety of the entire vehicle will not be guaranteed. Therefore, a large number of simulation calculations are needed during the design of a steering gear controller, and the method of reducing the disturbance should be found at the beginning of the design phase. In this paper, the system model of an electro-hydraulic rudder was set up first, and the stiffness characteristics of the system were obtained by simulation. Then the H_∞ controller was designed based on the Linear Matrix Inequality method, by solving the LMI optimization problem with constraint conditions. The designed controller can improve the dynamic stiffness of the system to a great extent. Finally, the simulation results show that the controller can improve the anti disturbance ability of the system. The stiffness of the system is constant in a certain range of disturbance frequency, and the control gain of the disturbance channel is reduced. When the system parameters fluctuate, the system can still keep good anti-disturbance ability and strong robustness, the design of the controller was verified by the actual project.