The Research Of Stabilization And Tracking Control Techniques On Airborne Opto-electric Platform Servo System

Airborne opto-electronic stabilization platform,which is known as the "eye" of the aircraft,is widely used in the zone of aerial reconnaissance,target location,attack collation and effect evaluation due to the ability to capture,track and target moving targets in the airborne environment quickly.In recent years,a large number of new materials and high-performance detectors have been used in airborne optoelectronic stability platform.And long-distance,high-precision are becoming the problem to be solved in the airborne opto-electronic stabilized platform.Especially the detection range has been gradually increased from ten kilometers to dozens of kilometers,or even hundreds of kilometers.With the development of aerial reconnaissance,target location,attack collation and effect evaluation which can be described as long distance and high precision,the accuracy of the reconnaissance image and the accuracy of the target location should be higher than before.And the stability accuracy and tracking accuracy of servo system in airborne opto-electronic stabilized platform also should be higher than before.In the process of airborne opto-electronic stabilization platform,the servo control system will always be subject to model interference,torque interference,sensor and actuator noise interference and so on.Usually,the model of airborne opto-electronic stabilization platform can not be accurately obtained and the characteristics of the system would change with the change of outside environment.Alos torque interference,sensor and actuators noise interference are uncertain and time-varying.In order to solve the uncertainties of the airborne opto-electronic stabilization platform and to improve the stability accuracy and tracking accuracy of the system,we take a certain type of two-axis and four-frame airborne opto-electronic stabilized platform servo system as the research object and carry out the following aspects of research on the stability and tracking accuracy of the servo control system:(1)The composition of the system and engineering requirements of the airborne opto-electronic stabilization platform are analyzed in this paper.On this basis,the working process of the airborne opto-electronic stabilization platform and the four working states of the servo system are discussed.Then,the paper analyzes the types and characteristics of the opto-electronic encoder,the rate gyroscope and the control motor in the servo control system,which provides the basis for the selection of the sensor and the actuator in the servo control system of the airborne opto-electronic stable platform.(2)The disturbances in the airborne opto-electronic stabilization platform are divided into three categories in this paper: model interference,moment interference and noise interference of sensor or actuators.And the characteristics of those disturbances and the suppression methods in airborne opto-electronic platform are analyzed in detail.Then,the double closed-loop control model of the servo system in airborne opto-electronic platform are established based on the DC brushless torque motor,which are the velocity control loop and the position control loop.And the performance requirements of the open-loop phase margin,closed-loop bandwidth,closed-loop moment stiffness and disturbance isolation of the airborne opto-electronic platform servo system are introduced based on this double closed-loop control model,which provides the basis for the design of the servo system.(3)Several classic control strategies and modern control strategies are discussed in this paper.And we choose the robust control strategy to design the volecity control loop of the servo system based on the characteristics of airborne opto-electronic platform model and the uncertainty of interference.By the analysis of the standard robust H_? control,the design of the mixed sensitivity H_? controller of the airborne opto-electronic platform servo system is discussed in detail.And we mainly solve the problems follows: the selection of the weighting function in the hybrid sensitivity H_? controller.Experiments show that the hybrid sensitivity H_? controller used in this paper is superior to the PI controller in terms of suppressing the disturbance of the model,torque and angular velocity disturbance and response speed.The stability accuracy is better than 8?rad when the disturbance is 1 ° 1Hz.(4)In this paper the generation process of the miss distance in the airborne opto-electronic stabilization platform is introduced.On this basis,we conclude that the miss distance information received from the airborne opto-electronic platform servo system has uncertain delay which is bounded and time-varying.And we analyze the influence of this miss distance delay on the stability and tracking accuracy of the control system in the airborne opto-electronic platform.After introducing the commonly used Kalman predictive filtering method based on the uniform acceleration model and its shortcomings,this paper presents the compensation of uncertain bounded time-varying delay based on the current statistical Singer model.The simulation results show that Kalman,H_? predictive filtering methods based on constant delay are less pleasure for compensating unknown time-varying delay in opto-electronic platform tracking servo system.And the proposed method is more effective for compensating unknown time-varying delay.And the tracking experiment on the airborne opto-electric stabilization platform shows that the proposed method is effective and the tracking accuracy is better than 0.5mrad when tracking 10 ° 0.2Hz signal with 1 ° 1Hz disturbance.