Research On Control Method Of Electro-hydraulic Servo System Based On Unkown Estimation

The Electro-Hydraulic servo system has the characteristics of large power-to-volume ratio,strong carrying capacity,fast response speed.It is widely used as a rudder system in large projectile flight control systems that require large steering torque.The deflection of the air rudder and gas rudder,and control the movement of the swing nozzle is controlled by the instructions of the control system,so as to achieve the adjustment of the flying attitude of the projectile.In addition,electro-hydraulic servo systems are also widely used in other national defense and civilian industrial fields.With the improvement of mechanical working precision,response speed and automation degree,the control accuracy requirements of electro-hydraulic servo systems in various fields have also continuously increased.This not only requires higher performance of hydraulic control components,but also requires the system to adopt more advanced control methods.However,in the process of designing an advanced electro-hydraulic servo position tracking system controller,the following challenges are encountered.For example,the system is affected by unknown external interference.This external interference can be a matched disturbance or a non-matched disturbance.Another example is the problem that the information needed in the process of designing the model compensation controller cannot be satisfied,that is,the problem of output feedback or partial state feedback,and other problems such as model uncertainty and friction compensation.Therefore,in summary,this article will use the appropriate unknown estimation strategy to make the following research on the above problems in the electro-hydraulic servo position tracking control system:1 Aiming at the problem of estimation and compensation of matching disturbances and mismatching disturbances in the electro-hydraulic servo system,compared with the methods in the existing literature,this paper will propose a more simple and effective solution.Firstly,the matching and mismatching disturbances in the electro-hydraulic servo system are estimated.On this basis,the corresponding control rate and virtual control rate are designed,and the two disturbances are compensated separately.According to the characteristics of the disturbance observer,the concept of lumped disturbance observation compensation is further proposed,which greatly reduces the model information needed in the process of designing the controller,reduces the time cost of the controller design,and improves the economic benefit.2 Aiming at the problem of the construction of the controller and the observer of the electro-hydraulic servo control system in the absence of speed signals,this paper uses position signals and pressure signals to reshape unknown signals.First,a new unknown state containing known location information and unknown velocity information is constructed by linear combination.An "estimated value" of the unknown state is constructed by the Kreisselmeier observer,where the concept of the estimate is assumed,but the estimate of the unknown state is still unknown.Although the estimated state is still unknown,the internal state of the observer is known.By using the known internal state,the design of the backstepping controller can be implemented smoothly,and the coupling problem between parameter estimation and state estimation is solved.Finally,the feasibility of the proposed control observation framework is proved by experiments.3 Aiming at the output feedback problem of the electro-hydraulic servo system,that is,the problem of constructing a fully closed-loop model compensation controller when only the position signal is known.The electro-hydraulic servo control system contains a large number of nonlinear factors such as servo valve pressure flow nonlinearity and friction nonlinearity.These nonlinear factors cause difficulties in designing the electro-hydraulic servo system output feedback controller.In order to construct a full-closed model compensation controller smoothly,this paper firstly makes a reasonable linearization assumption for the nonlinear factors in the system,and then appropriately transforms the model to use the Kreisselmeier observer.The observer has an extended structure that enables parameter adaptive design while observing the state,thereby adaptively estimating the relevant unknown parameter variables.For state estimation error,parameter estimation error and uncompensated disturbance variable,the corresponding robust term is designed to stabilize each step in the backstepping design process.The final designed controller can obtain good preset control performance,and the effectiveness of the designed controller is verified by comparative experiments.4 Aiming at the controller design of non-linear electro-hydraulic servo system processing output feedback and friction compensation at the same time,this paper first proposes an integrated design strategy.Different from the previous application of high gain state observer for output feedback design,in this paper,the speed estimation state is first obtained by a speed differentiator,and then the estimated values of other unknown states are obtained during the controller design process.For the friction compensation problem,this paper uses the modified Lu Gre friction model combined with the output feedback controller for friction compensation.The entire controller design process uses backstepping control,taking into account model uncertainty,estimation error and parameter uncertainty.In the end,the stability of the controller was proved by theoretical proof,and the relevant verification was carried out through simulation and experiments.