Close Range Attitude And Orbit Control Method Of Spacecraft Relative To Tumbling Target

The on-orbit repair of the failed spacecraft is a hot issue in the current aerospace field,and the close range attitude and orbit control of the spacecraft relative to the tumbling target is one of the key technologies.The failed spacecraft is generally in free tumbling motion in orbit due to the absence of attitude control,which brings great challenges to close-range operation.Thus,the paper studies Attitude and Orbit Control Method of Spacecraft Relative to Tumbling Target in Close Range.The main results of the paper are as follows:1.Aiming at the flying around and hovering of the tumbling target,the forced flying around control strategy,the fuzzy based and the non-singular terminal sliding mode based hovering control method are proposed respectively.(1)A control strategy for forced flying around the tumbling target spacecraft is proposed.The problem of flying around the target by the chaser is transformed into a two-dimensional control problem in the instantaneous rotation plane of the line of sight.The motion of the line of sight and the vertical line of sight is controlled by sliding mode controller.(2)Fuzzy control method is used to achieve position hovering of the tumbling target.The nominal hovering position and velocity of the chaser in the orbit coordinate system of the target are derived.The hovering problem is decoupled into a two-dimensional fuzzy control problem with three channels,and a Mamdani type fuzzy controller is designed with one channel as an example.(3)The adaptive non-singular terminal sliding mode control method is used to realize hovering of the tumbling target.An integrated dynamic model of nonlinear six-degree-of-freedom coupling is established in the chaser's body coordinate system.An adaptive non-singular terminal sliding mode controller is designed.The adaptive tuning method is used to overcome the influence of system model uncertainties and external disturbances.The boundaries of uncertainty and external disturbances do not need to be known in advance.2.Aiming at the approaching strategy of the tumbling target,the Augmented Proportional Navigation(APN),Linear Quadratic Regulator(LQR)and the integrated attitude and control method are proposed respectively.(1)The APN law control method is proposed to approaching the tumbling target.The three-dimensional relative motion equation between the chaser and the approximation point is established on the chaser's line of sight rotation coordinate system.Based on the idea of feedback control,the control of the line of sight of the approximation point is introduced on the basis of the traditional true proportional navigation law.The chaser approaches the line of sight along the approximation point according to the exponential decay.(2)The LQR method is used to approaching the tumbling target.The nominal position and nominal velocity of the chaser and the target approximation point are derived on the target's orbital coordinate system.The LQR controller was designed based on the Linear Quadratic Regulator.(3)An integrated attitude and orbit control method for approaching the tumbling target is proposed.Considering the safety of the approaching process,the nominal trajectory of the chaser is designed,and the exponential deceleration method is used to approaching the uncontrolled tumbling target spacecraft.Considering the external disturbances and system uncertainties,an adaptive non-singular terminal sliding mode controller is designed and the stability of the system is proven.3.Aiming at the safe approach of the tumbling target,the elliptical vine surface potential function and the spherical potential function guidance methods are proposed respectively.(1)Safety approaching and obstacle avoidance guidance based on potential function of elliptic vine surface.The safety and obstacle avoidance problem of approaching tumbling target is transformed into the path planning problem of dynamic environment.The attractive potential function is designed according to the state error.A safe corridor of elliptical vine is designed in the final approaching section.The obstacle is assumed to be a sphere with a certain radius,and the obstacle potential function is designed based on the Gaussian function method.(2)Safety approaching and obstacle avoidance guidance based on spherical potential function.The safety zone constructed by the elliptical vine surface potential function belongs to the semi-safety zone.Based on the semi-safety zone analysis,the spherical full safety zone and the cone safety corridor are designed according to the mission requirements of the full safety zone.4.A ground suspension experimental method of spacecraft relative to tumbling target's close range motion control is designed.(1)A ground experiment platform based on suspension gravity compensation system was built.Its working principle is to use the constant pulling force of the follow-up platform's sling to offset the gravity of the experimental spacecraft thus,simulating the weightlessness environment of the space.(2)The control scheme of ground dynamics experimental is designed.Firstly,the scale factor of the suspension contraction experiment is derived according to the similarity theory.Secondly,the relative position and relative attitude control strategies of the ground are given.Finally,the close range motion control experiment of the chaser simulator relative to the tumbling target simulator was carried out.