Strategy And Control Of Space Robots For Capturing Tumbling Objects

With the rapid development of space technology,many countries are not only getting great benefits,but also bearing the risks hard to predict.The utilization of space robots on orbit service can effectively reduce the risk and cost of space activities.So On-Orbit Servicing has great significance.On orbit capture by space robots is key technologies of advanced On-Orbit Servicing.On this background,the research on the attitude control of the assembly of spacecraft and the eliminating rotation with friction torque to non-cooperative target is carried out.This study provides a new way for solving the problem of capturing the non-cooperative tumbling spacecraft,and provides reference for the follow-up study.This is the first time to propose a solution for the high speed spin target,which has important engineering significance.Firstly,the paper presents a new method for eliminating rotation of the uncontrolled tumbling objects in orbit with friction moment.A new type of mechanical arm is designed for this idea,which has a component eliminating rotation with friction torque.In order to improve the reliability and simplify the design of the manipulator,we implement an executive body can effective capture the target satellite and the component can eliminate rotation with friction torque to the manipulator.Secondly,the stability of the attitude motion of the spacecraft under the action of gravity gradient torque is studied.First,the attitude dynamics model and kinematics model of the spacecraft with a biased momentum wheel are established.On this base,considering the motion condition on the elliptical orbit,the attitude motion equation is simplified.Secondly,the influence of the factors on the movement trend is analyzed by considering the different bias momentum wheel speed.In order to solve the continuous variation of the gravity gradient in the elliptic periodic orbit,the approximate series solution of the attitude motion of the spacecraft is derived by using the piecewise series approximation method of the gravity gradient torque of spacecraft.Finally,the simulation analysis is carried out to verify the correctness of the analysis method.I study the characteristics of the spacecraft's attitude motion of the spacecraft with a biased momentum wheel through this method of half simulation and half analysis.Thirdly,research on the strategy of the space robot to catch the target body on orbit servicing task propose a method of solving the problem of the attitude control of the spacecraft in the elliptical orbit and to eliminate rotation of the target at the same time..Firstly,the dynamic model of the system is established according to the concept of the mechanical arm.Then,the attitude dynamics model of the space robot and target body is given.Finally,the proposed method is verified by phase plane divisional control method and the sliding mode control method.The chief mission of this paper is to solve the problem of the attitude control of the spacecraft in the elliptical orbit and to eliminate rotation of the target at the same time.Firstly,design the mechanical arm required by the task.Secondly,fit the gravitation gradient moment by using the method of the piecewise series approximation,and gives the approximate solution method of the attitude motion.The simulation results show that the solution of the series is in good agreement with the numerical results,which could explain the cyclical movement of the attitude of the spacecraft.This part of the paper has an important significance for understanding the characteristics of the spacecraft's attitude motion in the elliptical orbit and for the research of the corresponding control problem.In the end,I analyze and design the strategy which the spacecraft's attitude control can be achieved at the same time to eliminate rotation.The simulation shows that the proposed method can keep the attitude of the spacecraft stable,eliminate the rotation of the target and effectively protect the robot arm,which illustrates the effectiveness of the proposed method.In this part,a new method for rotation elimination of tumbling spacecraft is presented.