Study On The Orbit Control Of Space Rendezvous And Docking Using Active Disturbance Rejection Control

With the increasing demand of human exploration of space, space rendezvous and docking technology is getting more and more attentions in the whole world. For the space rendezvous and docking, completing the mission in a high precision, good robustness, less fuel consumption way has been a research focus in this field. Thus we begin the research with special problems of orbit control. In this dissertation, the research includes the dynamics modeling and control design of rendezvous and docking. The main work is summarized as follows:(1) Firstly, the circular orbit dynamic model and elliptical orbit dynamic model of the space rendezvous and docking are established, and the analytical solutions of these models are calculated. Then, the characteristics of these models are analyzed. Finally, the problems and difficulties of the control of rendezvous and docking are pointed out.(2) Smooth without overshoot, good robustness and fuel-saving control are essential for the orbit control task of space rendezvous and docking, thus it is very difficult to get stable and accurate control performances by using traditional controllers. To solve this problem, a transient process for orbit control is proposed, and the ultimate goal is refined to gradually arrival goals to build the transient process between the initial coordinate and the target coordinate of the system. The output of the transient process is designed as a smooth S-type curve which has three different motion sections of acceleration, uniform speed and deceleration, and the transient process is conducive to stable orbit control.(3) By combining the transient process and feature model, we designed the golden section controller and the nonlinear golden section controller based on the transient process. In order to verify the advantages of the transient process, we then designed the tracking differentiator controller and PID controller based on the transient process. Then simulation experiments are implemented in the position control system of the space rendezvous and docking. The superiority of the new method over existing algorithms is studied.(4) A control method based on active disturbance rejection controller is proposed in this paper for the difficult control problem of autonomous rendezvous of space crafts on elliptical orbit in the absence of orbit information. Under the conditions of the elliptical orbit dynamics model, a transient process between the initial coordinate and the target coordinate of the system is designed to reduce tracking error and solve the contradiction between system rapidity and overshoot. Using extended state observer to estimate the real-time information of the unavailable time-varying parameters and external disturbances, then the estimated value is compensated by nonlinear feedback control law. Simulation experiments are implemented in the ideal condition and the external interference condition of the system. The superiority of the new method over existing algorithms is studied.