Research On Disturbance Torque Suppression And Performance Optimization Of Electric Servo Loading System

Electric servo loading system(ESLS),also known as electric load simulator,is mainly used to simulate the real load borne by the load-bearing mechanism under actual working conditions.It is widely used in aerospace,rail transit,scientific research and experiment fields.It is an important ground semi-physical simulation equipment.ESLS can simulate various types of load spectra that the steering gear is subjected to in actual working conditions,and it plays a very important role in analyzing and studying the mechanical structure parameters and control performance of the steering gear system.The key technical problem of electric servo loading system control is: ESLS is a passive loading system.The loading motor passively follows the movement of the steering gear system,which interferes with the normal loading of the loading system.As the movement frequency increases,the excess torque of the loading system becomes larger and larger;and,The system itself has frictional non-linear interference factors,and friction interference torque is generated during the loading process,which is the same direction or opposite to the loading force,which affects the force servo tracking accuracy of the loading system.Aiming at the problems of low loading accuracy,low bandwidth and poor anti-interference ability of ELLS caused by disturbances such as excess force and friction,this paper conducts in-depth research on the control strategy of electric servo loading system.First of all,this article starts from the composition structure and working principle of the electric servo loading system,and uses the mechanism modeling method to complete the establishment of the mathematical model of the ESLS and steering gear system.Aiming at the frictional nonlinear interference in the system,the Lu Gre model is used,and the model parameters are identified through genetic algorithm.Then the loading system,steering gear system and friction model are coupled to obtain the overall model of the electric servo loading system.Secondly,the ESLS open-loop frequency characteristics are analyzed,and phase lag compensation and force closed-loop PID control are introduced to ensure system stability and loading accuracy;the reason for the excess force of the system is derived theoretically,and its influence factors are analyzed,and the excess force suppression strategy is studied.Based on the theory of structure invariance,the force command feedforward compensation and disturbance feedforward compensation strategies are proposed,and the feasibility of the designed controller is verified through simulation results.Finally,in the low-frequency loading process of the electric servo loading system,the frictional interference causes the dead zone and the output unevenness of the loading system output force to be suppressed by the backstep adaptive control method based on the state observer,and through the system simulation test,Compared with the traditional PID controller,it is proved that the designed backstepping controller can eliminate the frictional nonlinear influence factors to a certain extent,and improve the system loading accuracy.Based on the above theoretical analysis,perfect the experimental platform of the electric servo loading system,and rely on this platform to complete the static loading experiment,dynamic loading experiment and steering gear system test experiment.The experimental results show that the static and dynamic loading accuracy of ESLS meets the design index requirements within the specified frequency,which better solves the system interference such as excess force and friction,and improves the overall performance of the system.