| Passive electro-hydraulic servo loading system is also known as Electro-hydarulic load simulator.It is one of the main equipment of flight control semi-physical simulation and its typical application is to simulate the aerodynamic load of the rudder surface of the aircraft under the condition of ground laboratory,so as to detect the technical performance index of the steering gear.The system is mainly composed of two parts,the bearing system and the loading system.The two systems,connected with a rigid shaft,can track their designated signals and achieve closed-loop control by using the angular displacement sensor and torque sensor signals.It is difficult to control the performance of the system at work because the strong position disturbance of the loading system will produce a large extra torque and the output control flow of electro-hydraulic servo valve is nonlinear and the system parameters are time-varying.Hence,this paper makes depth study of passive electro-hydraulic servo loading system theory and experimental research.It is hoped that a high-precision torque control strategy will be formed to provide theoretical support and technical means for electrohydraulic servo loading control.Firsty,through consulting the related literatures home and abroad in recent years,the main technical indexes,the main technical problems,research status and challenges of the passive electro-hydraulic servo loading system are discussed.Finally,this paper adopts the control compensation method to improve the loading performance of the system.Secondly,this paper introduces the mechanical structure of the passive electrohydraulic servo loading system.Ignoring the influence of the unimportance factors,the nonlinear mathematical model of the passive electro-hydraulic servo loading system is established,the nonlinear system equation is derived based on the nonlinear mathematical model of the system.The production mechanism and the influencing factors of extra torque in the system are analyzed.Thirdly,based on the theory of nonlinear control,an adaptive backstepping sliding mode controller is designed by combining the backstepping adaptive control method with the sliding mode control strategy aimed at the torque control problems of passive electro-hydraulic servo loading system.And the stability of the controller is proved by Lyapunov stability theorem.This paper uses MATLAB simulation softwareplatform to build the Simulink model of the controller.By comparing the control effect of various control methods,it is proved that the control strategy proposed in this paper can effectively suppress the excess torque,and it has strong robustness to the perturbation of parameters and external disturbance.Finally,the simulation experimental rig of the passive electro-hydraulic servo loading system is constructed.Subsequently,the experimental study on the adaptive backward sliding mode control method of the passive electro-hydraulic servo loading system is carried out by using the passive electro-hydraulic servo loading system simulation experiment platform,and the effectiveness of the proposed method is verified. |
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