Research On Configuration Keeping Control Method Of Cooperative Imaging With Dual-satellite Following Flying

Satellite formation cooperative imaging plays a pivotal role in the military and civilian fields,and is widely applied in space reconnaissance,weather forecasting,agricultural census,and many other aspects.Because of the progress of micro-nano satellite and the demand for remote sensing imaging,the research on satellite formation configuration maintaining control strategy for cooperative imaging has great theoretical and practical significance.Aiming at the problem of dual-satellite formation collaborative imaging configuration maintenance control,this paper carries out system research work from many aspects such as theoretical model,control strategy,interference and fault estimation.The following is a summary of the thesis:1.According to the relative motion mechanism of dual-satellite following flight for cooperative imaging,the relative motion dynamic model of two satellites including the perturbation effect is built with a dynamic analysis carried out.In order to obtain the linearized model of relative motion and solve the equation of relative motion,the analysis and approximate simplification are carried out according to the circular assumption of reference orbit and the disturbance ignored.Then,the basic configuration of satellite formation is discussed,and the space perturbation forces on satellites are analyzed.2.The SDRE(The state-dependent Riccati equation)control strategy is proposed based on the nonlinear dynamic model of dual-satellite relative motion.Firstly,a state-dependent coefficient model is established to transform the original nonlinear system into a linearized form.Then the SDRE is solved,and the SDRE controller is designed.Finally,The SDRE controller is compared with PD and LQR(linear quadratic regulator)controllers.The simulation shows the effectiveness and superiority of the proposed control strategy.3.Aiming at the configuration maintenance problem of dual-satellite collaborative imaging under interference and output saturation conditions,an anti-interference compound control strategy is proposed based on an observer.Firstly,considering the various perturbation forces and unknown disturbance that the satellite formation is subjected during its orbit flying,a kind of interference observer is designed,which can estimate the system state and interference at the same time.The Lyapunov theory and LMI are used to give the existence conditions of the observer.The pole configuration method is used to improve the characteristic of the observer system.An exponential decay factor is introduced to improve the convergence speed of the controller.Then,considering the output saturation characteristic of the actuator,a composite control strategy of weighted PD+LQR feedback is proposed to realize the dynamic adjustment of the controller.Finally,the simulation illustrate that the algorithm can realize the anti-disturbance configuration maintaining control of the dual-satellite formation.4.In order to solve the low accuracy and poor stability of dual-satellite formation orbit control caused by system model error,disturbance and fault,an anti-interference fault-tolerant control strategy based on augmented observer is proposed.Firstly,an augmented observer based on double proportional integral adaptive law is designed to estimate the system state,intermittent fault,fast time-varying fault and modelable disturbance quickly and accurately,and the influence of indescribable disturbance on the control system is suppressed by H_∞optimization technique.Secondly,the residual differential module is added to the observer to improve the precision.The Lyapunov theory is used to ensure the asymptotic stability of the dynamic error system.Then,the estimated information of the observer for the system is drew into the controller as the feedforward compensation,and a closed-loop anti-interference fault-tolerant control law based on"feedforward compensation+feedback"is designed.Finally,the simulation illustrate that the proposed method can increase the control accuracy,which can meet the precise control requirements of dual-satellite formation cooperative imaging.