Study On Distributed Satellites Dynamics Modeling And Control

Distributed satellites system (DSS) is a new research field of space technology, may lead to revolution in the applications of the spacecraft. Coordination and control of the DSS is a key technology to enable distributed satellite, referring to technology in orbital dynamics, auto navigation and control, sensors and actors, data processing and computation etc. In this thesis, the problem of coordination and control of DSS was studied from aspects of dynamics and control.First, The dynamics fundamental of the DSS was studied. The basic characteristic of formation flying of the satellites in the DSS was based on the dynamics of two spacecraft near by each other. Then a set of parameters used to describe formation configuration were defined. Various dynamics models were analyzed with analytical and numerical methods. Then a selective guide line of dynamics model of the DSS was established.Secondly, the control methods for formation configuration of the DSS were studied. The coordination and control of multi-satellite DSS must be implemented under a control architecture, so a layer control architecture enabling coordination and control of multi-satellite DSS was selected. Under the architecture, a scheme of formation initialization using two impulses was presented, and a control strategy was concluded to guarantee that the initialization of the multi-satellite DSS could be completed in one orbital period. A new reaching law with an attenuation multiplier to the switch gain of sliding mode varied structure control (VSC) was presented. The robust precise formation keeping of the DSS was realized based on the control law, and the conflict between control time and control precision was conquered using the control law. A control scheme without radial control for the DSS formation keeping was presented, the controller was designed based on a new VSC method, which used the optimal Guaranteed Cost Control (GCC) methods of the uncertain discrete time system to design sliding surface of the VSC, and the problem of the VSC of linear discrete system with mismatched uncertainty was resloved. The path plan problem of the DSS reconfiguration was studied with a quadric programming method, the objective functions for optimization of the DSS reconfiguration were presented, including fuel consumption optimization, equality of fuel consumption optimization and the optimization of both fuel consumption and equality. In addition, a DSS reconfiguration strategy with one satellite fault was presented in study of the DSS reconfiguration. Then an overall scheme of coordination and control of DSS was established based on the study of formation initialization, formation keeping and formation reconfiguration.Then design of typical DSS system was studied. The concept of distributed space surveillance system was presented, the elements and detection method for space target sensor were studied, and the orbit and configuration of the system were designed. The optical characteristic of space target was studied, a strategy for star image preprocess was presented, and a new algorithm for locating star point was presented by a two-step projection checking method. Then the moving target was checked with a direct method and a mthod based on the Grubbs law.Finally, a distributed real-time simulation environment for common DSS and a distributed hardware-in-loop simulation environment for space surveillance were built, inclding models of high precision orbital dynamics, typical thrustors and sensors. Simulation for coordination and control of DSS and distributed space surveillance mission were made to validate the methods studied in the thesis.