Research On Modeling,Analysis And Nonlinear Control Method In Electromechanical Operating System

Electromechanical Actuator(EMA)is a special servo system which controls the load indirectly by motor,it is widely used in aerospace and defense technology.Transmission mechanism is an important part of EMA which combines the load and motor,torque can be amplified to drive the load by transmission mechanism.Transmission mechanism consists of a set of gears which contains backlash nonlinearity.Backlash nonlinearity brings adverse effects to EMA especially in speed loop.This paper focuses on the influence of backlash torque on speed tracking of EMA and it provides two methods of identification based on study of mutiple backlash models and real engineering scenarios.The first method is based on a dead zone model,in which the model is divided in three linear models and each linear model can be identified with least squares method.The second method is based on approximate continuous dead zone model.In this method,netic algorithm which has parameter optimization ability is applied to identify the approximate model.For a validation of model effectiveness and identification reliability,this paper carries on identification and compensation experiment on the platform of EMA.The experiment results prove model accuracy.Backlash nonlinearity is an external disturbance to speed loop especially in speed tracking.It is necessary to design a compensation algorithm to suppress this interference.This paper puts forward a new model compensation design to solve this problem which offset backlash nonlinearity by current compensation.Model compensation can offset the majority of backlash nonlinearity interference.However,there are still some interferences like model deviation and current tracking error in the system.A new continuous sliding mode control which does not have chattering problem is selected to deal with the rest interferences.The simulation results demonstrate the effectiveness of the design scheme.Continuous sliding mode control needs an appropriate switching gain to suppress the rest interferences,switching gain results in large speed volatility in steady state.In order to improve system anti-disturbance ability and speed tracking effect,a new GPIO is designed to estimate external disturbance and provide feedforward compensation.The continuous sliding mode control based on backlash compensation and GPIO has a better anti-disturbance performance and speed tracking effect.