Study On Attitude Intelligent Coordinated Control Of Micro-Nano Spacecraft Swarm

In recent years, the concept of micro-nano spacecraft swarm has successfully attracted attention in the astronautics field. Since it can dramatically shorten the development cycle and reduce the cost of research, the system can explore places in deep space where a single and monolith spacecraft is impractical. The mission challenge proposes high demand of attitude control of the swarm-based system. Under the background of micro-nano spacecraft swarm, this thesis focuses on the attitude coordinated control problem of spacecraft formation flying(SFF) in leader-follower approach. Fuzzy control method is combined with the classical control theory to design the attitude coordinated controllers, which make the controllers be more intelligent. The main contents of this dissertation are as follows:Aiming at the desired attitude be a constant, PD attitude coordinated controllers are designed under the ideal condition without external disturbances. Considering the appropriate parameters of PD controllers cannot be regulated easily, the Mamdani fuzzy reasoning method is applied to study the controllers based on the structure of the PD controllers. Moreover, numerical simulations and comperative analysis are performed. The result shows that the two kinds of controllers can both achieve the attitude targets, and the performance of the fuzzy controllers show a little bit better than the PD controllers. However, since the design of the fuzzy controllers just rely on the experience and knowledge, they cannot keep high control accuracy, which means the designed fuzzy controllers have disadvantages obviously.Aiming at the desired attitude be a time-varying signal, an adaptive fuzzy sliding mode control scheme is designed to achieve attitude coordinated control in spacecraft formation in the presence of model uncertainties and external disturbances. The proposed control law consists of two parts: equivalent control and switching control. In order to attenuate high-frequency chattering caused by the switching control, double fuzzy systems are applied. The adaptive fuzzy control is utilized to approach the sign function of the switching control. Moreover, fuzzy rules are employed to smooth the switching control based on the sliding surface. Simulation results and comparative analysis are carried out to demonstrate the proposed control law can effectively attenuate the chattering phenomena and meanwhile keep strong robustness of the control system.