| Electro-optical stabilization platform is widely used on various carrier aircrafts to isolate the disturbance from the carrier and perform the tasks of battlefield reconnaissance and the tracking of targets.The platform stabilization accuracy is the key index of the servo system,which determines the reconnaissance performance of the airborne electro-optical stabilization platform directly.The roar of the engine,changes of the flight attitude,airflow disturbance and other factors make the airborne electro-optical stabilization platform to be in the perturbation environment which is periodic vibration based and also contains lower broadband random vibration.Therefore,the stabilization accuracy of the stabilization platform is greatly limited by the ability of the servo system to suppress the periodic vibration.So the perturbation transfer mechanism of the carrier aircraft and the suppression characteristics of the stabilization platform are analyzed in the paper.The suppression scheme of periodic perturbation is proposed and the control system is designed by theoretical calculation.The theme is finally validated by simulations and experiments.The paper includes the following parts:1.The mathematical model of the stabilization platform is deduced.The transmission characteristics of the disturbing angular velocity of the pedestal and the suppression characteristic of the stabilization platform are analyzed.The experimental model of the stabilization platform is established through system identification and its consistency with the theoretical model is demonstrated through proper simplify of the current loop.2.Aiming at the periodic vibration,the repetitive control method based on continuous time-delay internal model is introduced and a more practical Plug-In type repetitive control method is proposed to study its basic structure,stability condition,effectiveness condition,convergence and convergence rate.The design specification of the Plug-In type repetitive control system based on the index of the steady-state convergence ratio is proposed and a simulation example is given to prove the rationality of the design specification.3.The basic thought of the finite-dimensional repetitive control method is introduced.The configuration of series-type and shunt-type finite-dimensional repetitive controllers is proposed and their characteristics on complex frequency domain are analyzed.The change of the position of the zero point with the width coefficient is obtained,by which the effect degree of the periodic disturbance rejection ability of these two configurations are judged.The Louts stability criterion is used to infer that the stability of the shunt-type is better than the series-type.4.A stable platform experiment environment which possesses the function of producing pedestal disturbance,power-driven,sensing angular velocity,signal acquisition and processing and controller realization is built.The anti-disturbance experiment is designed to test the steady state accuracy of the Plug-In type repetitive control system,whose stabilization accuracy is superior to that of traditional gain integral controller and notch filter.A contrast experiment is designed.By comparing the steady-state precision and dynamic response of series-type and shunt-type finite-dimensional repetitive control systems,their ability to eliminate more than half of the RMS of the residual error under the conventional PI controller is reflected and the conclusion that the series-type system is more accurate than the shunt-type system but less stable is verified.This paper focuses on the studies of the suppression technology of the periodic perturbation.Simulation and experiment results show that the Plug-In type repetitive controller and the finite-dimensional repetitive controllers can effectively suppress the periodic perturbation.The research of this paper provides reference for the further improvement of anti-interference ability and the stabilization accuracy of the airborne stabilization platform. |
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