Research On Space Target Tracking And Hovering Control In The Geostationary Orbit

Geostationary Orbit(GEO)satellites have special properties such as wide ground coverage and fixed sub-satellite trajectories,and are widely used in civil and military fields such as communications,navigation,meteorology,ground observation,and military early warning.However,a large amount of GEO orbit resources is occupied by the uncontrolled targets such as failed satellites,upper stages of rockets,and space debris,which threaten the safe operation of orbiting spacecraft seriously.In order to ensure the safety of space assets,on-orbit services such as on-orbit maintenance and orbit clean-up have been highly valued by major space powers.Due to the characteristics of GEO satellites such as maneuvering,non-cooperation,and diversity of platforms,tracking and hovering control of space targets have been the key technologies urgently to be solved for space tasks such as on-orbit services.It is focused on high-precision target motion estimation over large distance spans during the rendezvous process,target detection observability improvement methods under under-dimensional measurement,and fast and high-precision tracking of mobile targets,and research on low fuel consumption hover control in the article,some research results have been achieved,which are mainly as follows:Aiming at the problems of performance evaluation and filter parameter tuning faced by high-precision relative navigation,the estimation error propagation model of CW equation un-modeling error in filtering process was deduced,and the design margin(ratio of state variable estimation variance and true variance)is used as the filtering estimation performance criteria.The relationship between the performance criteria of the Kalman filtering algorithm and the process noise and the attenuation factor is numerically analyzed,some analysis and simulation about the method used in the scene on the fixedrange companion and 1-100 km range companion are given respectively.Aiming to inhibit the low frequency fluctuation of relative navigation estimation error due to the minimum resolution of radar measurement,an adaptive variable step size design method is proposed,and the propagation model of measurement error during the filtering process is derived.Both analysis and simulation show that the method has far better accuracy than the Lowbandwidth filters commonly used in practical project.Low-cost,simple-configuration satellites face the problem of full-dimensional state estimation with insufficient measured information.Relative navigation in the absence of ranging information requires the chase satellites to perform orbital maneuvers to improve the observability of the system.Aiming at the problem of orbital maneuvering direction optimization and fast convergence in this method,a Kalman filtering method based on the recursive correction of the ratio of the estimated motion trajectory to the real trajectory is proposed.The ratio is used as the state parameter(scale factor).The observability model and error propagation model of the scale factor are derived.After that,the analysis method of the optimal maneuvering direction under the two typical configurations of flying around and accompanying flying is given.Aiming at the relative navigation problem missing the yaw attitude measurement,the weak correlation between intersatellite measurement and yaw attitude motion(similar to orbital compass)is proposed,and the attitude and orbit combined Kalman filtering method is given.Observability analysis is performed on two typical configurations of flying around and flying accompany.The analysis showed that the filtering algorithm is observable under both configurations,and the estimation accuracy meets the requirements of medium precision formation flying task.After that,the problem of high-precision and fast tracking of non-cooperative maneuvering targets in space based on IMM(Interactive Multiple Model)and TSKF(Two-stage Kalman Filter)methods is studied.The problems of poor steady-state accuracy and high computational complexity exist in the IMM method based on the augmented CW equation,a adaptive reduced-dimensional IMM algorithm using the acceleration estimation likelihood function to modify the model prediction probability is proposed.Aiming to solve the contradiction between TSKF's steady-state estimation accuracy and maneuvering-target tracking speed,an adaptive variable-dimensional TSKF method is proposed,which uses the target maneuver detection information to adaptively modify the observation matrix and process noise matrix of the deviation filter.Compared with the previous algorithm,it has the same steady-state accuracy and faster tracking response speed.Mathematical simulation shows that the adaptive reduced-dimensional IMM filter and adaptive TSKF proposed in this paper can both achieve high-precision steady-state estimation and fast target tracking under the three maneuvering indexes of minimum,average,and maximum.Finally,the formation mechanism,design method,and low fuel consumption control problem under the hybrid propulsion of the "droplet" hovering configuration are studied.The characteristic parameters of the "water drop" configuration described by the CW equation are complicated to model and the configuration is not easy to design.To solve this problem,the relative orbit elements difference model is used to establish the in-plane relative motion equation,and the forming mechanism of the "water drop" hovering configuration.After in-depth research,the expressions of the characteristic parameters of the configuration(such as revisit time,upper boundary,etc.)are deduced.After that,a configuration design method based on the semi-major axis difference and eccentricity difference is given,which is suitable for pulse-thrust control.In order to further reduce fuel consumption,the high specific impulse advantage of electric propulsion can be used to assist chemical propulsion for hovering control,but the continuous action of electric propulsion destroys the symmetry of the "water drop" configuration and increases the difficulty of configuration design.In order to solve this problem,the CW equation and the orbital element difference mixed modeling method is used to derive the revisit period and the control variable solution equations.A hovering configuration design and control method under a multi-mode hybrid propulsion system is proposed.Mathematical simulation shows that the control method is effective and the fuel consumption is close to the optimal fuel consumption.A space motion simulation test system is designed and the relative navigation method and hovering control method in this paper are verified by the semi-physical experiments.