Research On Spacecraft Orbital Configuration And Autonomous Rendezvous And Docking Control Method

With the continuous development of space technology and increasing demand for different types of space missions during the recent years,the autonomous rendezvous and docking of spacecraft has gradually become a research hotspot and attracted considerable research interest.In order to complete the mission of rendezvous and docking of the target spacecraft,especially for the noncooperative on-orbit spacecraft,an on-orbit servicing spacecraft is usually utilized to proceed a series of orbital configuration control tasks over the target spacecraft to obtain its states estimation,including companion-flying,fly-around and hovering,due to its noncooperative property.Therefore,the autonomous rendezvous and docking of noncooperative target spacecraft is investigated in this paper with the problems of spacecraft orbital configuration control,initiative fly-around for the slowly rotating noncooperative target spacecraft with collision avoidance,and robust rendezvous and docking control for the noncooperative target spacecraft considering the autonomous collision avoidance studied,based on C-W equations,sliding mode control method,potential functions and adaptive control technique.The main contributions the paper are listed as follows.Firstly,the tracking control problem of Euler-Lagrange system with collision avoidance is studied.Based on the sliding mode control and potential function methods,an asymptotic tracking controller with collision avoidance is proposed.By introducing the collision avoidance function to the sliding mode surface,and utilizing the boundedness property of the hyperbolic tangent function,the collision avoidance function can be ensured to be upper bounded during the control process,which leads to the successful obstacle avoidance throughout the control process.Rigorous stability analysis is given to show that the proposed collision avoidance controller is without the local minimum value problem.Simulation results are presented to show that the proposed tracking collision avoidance controller can track the target quickly without colliding with the obstacles in the tracking process.Secondly,the spacecraft orbital configuration control including companion-flying,fly-around and hovering are studied.In the first place,C-W equations are used to describe the companion-flying,and pulse control strategy is given for the long-term companion-flying control.And based on the sliding mode control method,a continuous asymptotic convergence companion-flying controller is designed.Simulation results are used to show that,the companion-flying controller can achieve great steady states precision under the sliding mode controller.Moreover,the natural fly-around and initiative fly-around control strategies are given respectively for the fly-around control problem.In natural fly-around,natural elliptical fly-around and non-coplanar natural elliptical fly-around are analyzed,respectively.In initiative fly-around,the control strategy of impulse fly-around are given.Furthermore,a continuous fly-around controller with finite time convergence is designed based on the fast terminal sliding mode surface.Simulation results are used to show that the designed fly-around control strategies are able to realize the fly-around task,and the continuous controller achieves higher precision.Finally,for the hovering control,a control strategy applicable to engineering is designed.Based on the multivariable super-twisting sliding mode(MSTSM)method,a finite time convergence hovering controller without input chattering is proposed.Considering the saturation problem,a finite time convergence hovering controller under actuator saturation is proposed based on hyperbolic tangent function.All the hovering controllers have been given strict theoretical proof,and the simulation results verify that the designed hovering controller can achieve high precision hovering.Thirdly,the initiative fly-around collision avoidance control problem of slowly rotating noncooperative target spacecraft is studied.First of all,under the spherical collision avoidance model,a finite time stabilizing controller for the initiative fly-around of collision avoidance is designed under actuator saturation,based on a hyperbolic tangent function,considering upper bounded external disturbance which is known.Moreover,using adaptive control,the robust adaptive finite time saturation collision avoidance control problem is solved,considering the initiative fly-around problem of collision avoidance without knowing the external disturbance’s upper bound.Furthermore,the target spacecraft body-fixed coordinates ellipsoid collision avoidance model is established to solve the infeasibility problems of the spherical collision-avoidance-zone.Based on a hyperbolic tangent function and a modified sliding mode surface,the asymptotic stabilizing initiative fly-around controllers considering collision avoidance are designed for systems with and without prior knowledge of external disturbance,respectively.Then,based on the improved non-singular terminal sliding surface,the finite time initiative fly-around controllers considering collision avoidance are designed for systems with and without the knowledge of external disturbances’ upper bound,respectively.Theoretical proof and digital simulations verify the correctness and effectiveness of the proposed initiative fly-around control strategies.Finally,the autonomous rendezvous and docking control issues for noncooperative target spacecraft considering collision avoidance are studied.Firstly,a collision avoidance model based on elliptic cissoid is established,and the noncooperative rendezvous and docking controller is designed to satisfy the autonomous collision avoidance requirement using a potential function and the sliding mode control method.Secondly,in order to further solve the unwinding and collision avoidance problem simultaneously,a coupled translational and rotational dynamics of the spacecraft,where the rotation matrix parameter is used to describe the attitude of spacecraft,is used to put forward the improved autonomous rendezvous and docking controller considering collision avoidance,which can solve the problems of unwinding and collision avoidance.Furthermore,in order to obtain better convergence performance of the closed-loop system,a finite time rendezvous and docking controller is proposed to enable the system to avoid collision in a limited time.Theoretical proof and mathematical simulation verify the correctness and effectiveness of the proposed autonomous rendezvous and docking collision avoidance control methods.