| Spacecraft relative hovering means that the service spacecraft remains stationary relative to the space target in the reference coordinate system.In space on-orbit service missions,whether the target is captured or the module is replaced,there is a hovering maneuver in front of the target.This paper focuses on the analysis and control method of the near-range hovering characteristics of non-cooperative space targets,and studies the dynamics and energy characteristics analysis,uncertainty propagation and hovering control method of spacecraft hovering problem.The main research contents are as follows:(1)The establishment of hovering error band under the influence of non-cooperative target navigation deviation.Firstly,the Monte Carlo method is used to analyze the evolution of the target navigation deviation,and the distribution law of the position state of the non-cooperative target under the influence of the initial time deviation is determined.Furthermore,the hovering collision probability under the influence of the deviation is calculated by the double integral method,and the hovering error band is established to complete the navigation deviation analysis of the non-cooperative target.(2)Modeling and analysis of hovering energy characteristics in hovering error band.According to the dynamic model of the hovering control,the analytical expressions of the hovering control force and the hovering energy are derived.According to the force characteristics of the spacecraft in the hovering error zone,the hovering energy distribution characteristics in the hovering error zone are analyzed,and the unperturbed minimum hovering control force and the minimum fuel consumption hovering position are determined.(3)Design of close-range hovering and attitude-orbit joint control method.On the basis of establishing the relative position and attitude dynamics model of service spacecraft,two control methods considering underactuated hovering and attitude alignment are proposed.Two controllers are designed respectively: 1)Considering the attitude-orbit joint control method in the hovering observation scenario;2)Considering the fixed-time control method of underactuated hovering.Through the designed close-range hovering and attitude keeping control method,hovering in the desired position and alignment observation of non-cooperative target can be realized.In this paper,the close-range hovering problem is studied from four aspects:deviation evolution,collision probability,hovering fuel consumption and control method.The results of this paper will lay a theoretical foundation for the close-range hovering task of non-cooperative targets,and provide safety guarantee for the close-range hovering engineering practice of non-cooperative targets. |
