The Design And Research Of Electrical Actuator Load Simulator

Electrical actuator load simulator is an essential equipment of the hardware-in-loop simulation system, which is used to simulate the aerodynamic torque load on the rudder of aerocraft in the process of flight. Load simulation technology has been an important task in the field of navigation and spaceflight over the years. This paper analyses and discusses the characeristics of elecrical load simulator, control methods and the design of controller's harderware and software.Firstly, the structure and working principle of electrical load simulator are analyzed, and establish mathematical model of the system. Based on system model , through a detailed analysis of the characteristics of eletrical load simulator, it is concluded that: extraneous torque generated by the movement of actuator, indirectly reflected by load inertia and electromagnetic extraneous torque; Simultaneously, the stiffness between load simulator and actuator play a opposite role on the extraneous torque and open-loop frequency characteristic, so the choice of stiffness should be considered in the middle way.Secondly, specificly analyze the control algorithm of electrical load simulator. The feed-forward compensation based on structure invariance principle is introduced to eliminate extraneous torque in the first. Then differential torque feedback is imported to improve system damping characteristic, use PI controller to increase system bandwidth and tracking precision. Finally, explore the intelligent algorithm, the new fuzzy-PI controller combined by fuzzy and PI controller with switching function is imported to slove the step response's overshoot , which is too large, and can not be avoided under the PI control. Simulation results show that fuzzy-PI controller has excellent performance.Finally, the cotroller hardware based on FPGA is designed. For the part of software design, fourfold frequency circuit design method, which can improve the accuracy of actuator position, velocity detection is proposed based on state machine; and use direct digital frequency synthesis (DDS) to generate sinusoidal loading signal. The design methods proved correctly by simulation and experimental results.