Research On Disturbance Suppression Of Airborne Optical Platform With Two Axis And Four Frame Structures

The airborne optoelectronic platform is a highly integrated reconnaissance equipment that integrates light,mechanical and electricity modules.It is widely used in civil and military fields.With the continuous improvement of the requirements in the field of reconnaissance,the airborne optoelectronic platform with farther visible distance,stronger anti-interference ability and higher precision has become the demand of present social development.Therefore,the airborne optoelectronic platforms with different frame structures emerge as the times require.Among the frame structures of many airborne optoelectronic platforms,the advantages of the optoelectronic platform with two-axis four-frame structure become increasingly obvious,which can increase the tracking angle range of the platform,improve the stability accuracy of visual axis and prevent self-locking of traditional photovoltaic platforms.The airborne platform with two-axis four-frame usually works in extremely harsh environments,and is not only disturbed by wind resistance,friction disturbance,high-frequency sway of the carrier and so on.But also the coupling inside the frame due to the complicated mechanical structure,brings the two-axis four-frame structure great difficulties in servo control.Therefore,this thesis analyzes the internal and external disturbances of the two-axis four-frame structure optoelectronic platform to improve the anti-interference ability of the photoelectric platform servo control system.This thesis outlines the development and trend of airborne optoelectronic platforms at home and abroad,and introduces the composition of the two-axis four-frame system of the airborne optoelectronic platform.Various disturbances of the two-axis four-frame structure airborne optoelectronic platform are studied and analyzed,and mathematical model is established based on the characteristics of various disturbances to lay the foundation for the subsequent disturbance suppression control.The coupling kinematics of the two-axis four-frame structure airborne optoelectronic platform is analyzed.The analysis results play an important role in the disturbance conduction and isolation of the two-axis four-frame structure.Aiming at the problem that it is difficult to model the moment of inertia of each frame axis due to the complex coupling between the internal and external frames of the two-axis four-frame structure,this paper deduces the coupled moment of inertia of the two-axis four-frame structure of the airborne optoelectronic platform by using the direction transfer matrix,and establishes the mathematical model of moment of inertia of each frame axis.Based on the derived mathematical model of moment of inertia,the dynamic mathematical model of two-axis four-frame is established.The simulation data of airborne optoelectronic platform is designed by UG software to verify the correctness of the mathematical model of moment of inertia.The model and simulation analysis results provide a basis for the control system design of the two-axis four-frame optoelectronic platform.Aiming at the disturbance caused by the disturbance of the two-axis four-frame structure airborne optoelectronic platform and the uncertainty of the frame moment of inertia caused by the coupling of moment of inertia,this paper proposes to add the improved disturbance observer to the speed loop PI control loop of each frame.The new algorithm,the improved inertia self-correcting disturbance observer in the velocity loop not only has the robustness and stability of the traditional disturbance observer,but also greatly improves the dynamic immunity of the servo system.The paper innovatively bring the mathematical model of the established and simulated verified moment of inertia into the nominal inverse model of the disturbance observer,realize real-time observation of system parameter changes,simulate and verify the new optimization algorithm,and compare the inertia self-correction disturbance.The suppression performance of the suppression algorithm is 7.2 times higher than that of the traditional PID speed loop disturbance suppression performance.The new disturbance observer disturbance suppression performance has a behavior of up to 4.5times higher than the traditional disturbance observer in the two-axis four-frame structure servo control speed loop.