Restrain And Improve Disturbure Torque Of Airborne Optoelectronic Platform

Airborne Electro-Optical Platform (AEOP) is precision reconnaissanceequipment with highly integrated optical, mechanical and electrical, which has beenwidely used in the firepower control, navigation and reconnaissance system. As a coretechnology in the photoelectric precision tracking technology, servo system is theimportant guarantee of high precision optical axis stability to the airborneoptoelectronic platform. The ability of resisting disturbance torques is an importantsymbol to measure the performance of AEOP servo system, and is one of the maintopics of AEOP servo system. The main research contents of this paper is how toimprove the ability of AEOP servo system in resisting disturbance torque, in order toimprove the low speed performance of airborne photoelectric platform, to improvethe line of sight (LOS) stabilization accuracy of AEOP.In this paper, the object is AEOP with a two axis four framework, and eachframe of AEOP coupling were analyzed. This paper pointed out that the movementcoupling and inertia coupling between different frames are caused by mechanicalstructure of AEOP, are the cause of disturbance torques that affected the servo systemperformance of AEOP. And the inertia coupling also affects the accuracy of thecontrol object model. AEOP always is operated in frequent starting and braking state,especially tracked the target in the long focal length, generally work in low-speedmode, working environment is very bad because of the influence of friction,disturbance resistance, carrier sloshing and line disturbance brings, so high dynamicperformance is required,which requires AEOP servo system has strong dynamic anti- disturbance performance. Traditional servo system of AEOP as a classic Single-inputSingle-output system (SISO), is used with traditional three closed-loop control modethat includes position loop, velocity loop, current loop, and control law generally usethe Proportional Integral (PI) controller. This has resulted in ability of resistingdisturbance torques of servo control system is weak, difficult to effectively overcomedisturbance torques. It is particularly, such as LOS stabilization accuracy of AEOP isbad, degrade image quality and even cause tracking failure, when AEOP is operatedunder low speed,.In the design of AEOP servo system, the disturbance torque is seen as the input,the servo system is a Dual-input (Miss Distance and Disturbance Torques) Single-output (Miss Distance) system (DISO). So designing of AEOP servo system in thispaper, the acceleration feedback is introduced in the servo system to improve the lowspeed performance and the ability of resisting disturbance torques, and then improvethe AEOP stabilization accuracy. Because the control object model of AEOP with twoaxes and four frame is established difficultly, a method of direct measurement of shaftangular acceleration was adopted in this paper. So the acceleration feedback loop isnot based on the control object model, and the problem that the control object modelof the AEOP is difficult to establish was avoided.In this paper, the acceleration feedback introduced in the servo system of theAEOP is analyzed and researched, and analysis results show that the accelerationfeedback loop enhances dynamic stiffness of the servo system, improves the ability tosuppress disturbance moment in the servo system of the AEOP. The accelerationfeedback was put to test in the servo system of AEOP with two axis four framework.Experimental results show that, when the acceleration feedback loop was introducedin the classical PI control system, rejection disturbance torques ability of the servosystem raised about5dB on0.3N·m sudden disturbance torque; raised about14dB onposition sinusoidal motion at θ=sin4πtwith aircraft simulation turntable; and LOSstabilization accuracy was raised from48.39μrad to28.75μrad on position sinusoidalmotion at θ=sin2πtwith aircraft simulation turntable.