Relative Position And Attitude Tracking Control In Close-range Proximity To Space Tumbling Target

Space Tumbling Target,refers to a type of in-orbit spacecraft that has rolling motion characteristics under the influence of the earth’s multi-source perturbation in an uncontrolled state due to component failure or reaching the service life of the mission.In order to extend the service life of the tumbling failure spacecraft,space on-orbit service are required,such as on-orbit repairment,module replacement,fuel refueling,and debris removal.In order to ensure the safety and reliability of on-orbit service missions to space tumbling targets within ultra-close-range,it is necessary to control the on-orbit service spacecraft to perform precise operations actively,such as synchronized flight and safe proximity.Also study is necessary,on a fast,accurate,and safe control method for ultra-close-range under the impact of multi-source perturbation,to further meet the needs of subsequent tasks such as performing complex shape reconstruction,capturing point and docking port selection of space tumbling targets.In this paper,the following aspects are specifically studied for the ultra-close-range tracking control of space tumbling targets:(1)The relative motion modeling method of the space rolling target is studied.In this paper,based on the description of attitude motion of the space tumbling target,the time-varying capture point of tumbling target is given as tracking trajectory.Based on dual quaternion,the 6-DOF relative motion model of the target and service spacecraft is established.(2)The method of fast and accurate tracking control for sychronous flight of space tumbling target is studied.Considering the presence of unknown external disturbances and parameter uncertainties,a fast terminal sliding mode control method based on an extended state observer is proposed to achieve the attitude-orbit coupled control requirements of fast response,high accuracy and strong robustness(3)A safe approach control method for tumbling target with a complex shape is studied.Aiming at the collision risk problem that occurs during the ultra-close approach to the space tumbling target,the artificial potential function of the shortest distance of the ellipsoid is proposed based on the consideration of the tumbling motion and the complex shape of the two spacecraft.(4)The experiment of tumbling target tracking and approaching is set up and demonstrated.Based on the introduction of the software,hardware,and parameter identification methods of the experimental system,the control algorithm was carried out for the two scenario and verified by the experiment.