Study On Navigation And Guidance Of Formation Space Robots For Rendezvous With Non-Cooperative Target Of Geo

In Geostationary Orbit(GEO), the on-orbit servicing(OOS) of valuable and strategic satellites will make important and positive impact on economy, politics and society. Because GEO satellites have the characteristics of non-cooperation, long period and large size, it is quite difficult for a single space robotic system to perform relative navigation and guidance to GEO satellites in different range rendezvous.This dissertation is prepared in accordance with a project sponsored by the National High-Tech R&D Program of China(863 Program) in aerospace area. By a formation space robotic system, the relative navigation and guidance methods to a GEO non-cooperative and malfunctioned satellite are studied. The researches have important theoretical significance and application value for future OOS in GEO.According to the OOS mission objective of the GEO malfunctioned satellite, an autonomous, cooperative and multitasking formation space robotic system is established. Due to the non-cooperation, long period and large size of the GEO satellite, the formation space robotic system which consists of a dual-manipulators operation space robot and a monitor space robot can solve the problems of weak observation of relative navigation, low precision of relative guidance and unobtainable pose measurement. The system composition and rendezvous plan of each space robot are presented in detail. The relative dynamics and light condition of rendezvous are seriously analysed for the design of relative navigation and guidance methods.Based on the formation space robotic system, relative navigation methods for rendezvous with GEO non-cooperative satellite are designed in different range. In middle and close range rendezvous, the relative navigation method based on single line-of-sight and range is introduced. To solve the discontinuous problem of velocity state caused by velocity impulse, an improved Extend Kalman Filter(EKF) algorithm with velocity impulse is proposed to estimate relative state. In far range rendezvous, the distributed relative navigation method based on double line-of-sights is proposed to overcome the problem of weak observability. The state dimension of EKF is reduced. And the observability and precision of relative navigation are improved.Under the condition of relative navigation, the relative guidance and control methods for fast rendezvous with GEO non-cooperative satellite are designed in different range. In middle and close range rendezvous, the guidance laws inclu de the line guidance law, circular guidance law of fly-around and quaternion guidance law of attitude tracking. The control methods include Pulse Width Modulation(PMW) PD control and Quaternion PD control. In far range rendezvous, the tri-impulses C-W guidance law with mid-correction is studied to improve guidance precision and save rendezvous time. According to the constraint of relative navigation and the principle of fixed-time fuel-optimal, the improved Particle Swarm Optimization(PSO) algorithm with dynamic inertia weight and factors is proposed to realize tri-impulses C-W guidance. And the thrust-limited robust H∞ control method is presented to achieve tracking control.In final berthing of rendezvous, a single vision camera can not observe the whole feature of the GEO non-cooperative satellite to measure the position and attitude for relative navigation. The structured light vision system consists of a single vision camera and a simple structured light are proposed. According to the character of the target, the point and line structured light vision systems are designed. And the measurement model, the feature extraction method and the measurement steps are also given. Based on partial rectangle feature of the target, two pose determination algorithms by circular point constraint and rectangular constraint are studied. The algorithms can reconstruct a whole rectangl e to obtain enough feature points. Using the feature points, the relative pose is derived by least square method. The structured light vision methods for pose measurement are initiative, simple and reliable.In order to verify and validate the relative navigation and guidance methods of the formation space robotic system, a semi-physical simulation system based on two vision cameras is built. The simulation system combines the virtual 3D scene and two real cameras together by the principle of ‘virtual extended projection’. The two real cameras simulate the measurement system to obtain line-of-sights and natural features of the GEO non-cooperative satellite. These information are introduced into closed-loop control model to verify the relative navigation, guidance and control methods. The hardware-in-loop simulation system enhances the credibility of verification, which can be used in early verification phase of OOS mission.