Performance Optimization For Aircraft Rudder Electric Load Simulator Based On Brushless Direct Current Motor

The electric load simulator of aircraft rudder is a semi-physical ground simulation equipment that simulates air power torque of rudder during the flying time in the laboratory,in order to verify static and dynamic performance indicators under the air load.As a passive force servo control system,due to the active movement of the rudder subjected to position command signal during the test process,extraneous torque will be generated,which brings strong motion disturbance and seriously affects loading performance.In addition,friction in the transmission mechanism and external disturbance will act on the system in the form of nonlinear disturbance torque,and will also have an adverse effect on the output.Therefore,how to suppress extraneous torque as far as possible,reduce the damage from friction and external disturbance,and realize the real simulation capability to the load torque of the aircraft rudder in the actual working process,has become an urgent research topic.Firstly,the structure of aircraft rudder electric load simulator is designed with brushless direct current motor as the main execution mechanism,based on the analysis of the situation of research inside and outside China currently.Then,the main performance indicators of the system are given.Secondly,according to the electrical characteristics of the elements,the mathematical model of the nonlinear system is reconstructed in combination with the Lu Gre friction model.The components of the load torque output are analyzed to clarify the disturbance torque output brought to system by the position of rudder,friction and external disturbance.Thirdly,the improvement of Whale Optimization Algorithm is executed,an improved Whale Optimization Algorithm is designed by introducing Skew Tent Chaos Mapping,constructing the dynamic search factor and building a small over-tune Integrated Time and Absolute Error objective function,which improves the algorithm’s population diversity,searching efficiency and reliability of the results.Fourthly,a double loop composite control strategy is proposed,including a motor speed loop controller design and a torque loop controller design.On the one hand,in the design of inner loop controller for motor speed,in order to improve the control quality,a nonlinear disturbance observer and friction observer are established to realize the compensation control of external disturbance,and a zero Active Disturbance Rejection Controller with self-adjustment parameters based on the improved Whale Optimization Algorithm is designed.On the other hand,in the design of outer loop controller for load torque,in order to optimize the control quality,a new reaching law is designed that is proved mathematically that can address the chattering problem and reduce convergence time,and a sliding mode controller based on the new reaching law is designed by backstepping method.Finally,the experimental results from Matlab/Simulink demonstrate that the double loop composite controller can effectively suppress extraneous torque,reduce the effect of friction and external disturbance,so that significantly improve the loading performance of the system.