Fuzzy attitude control of flexible multi-body spacecraft

Abstract

In order to complete the flexible multi-body spacecraft attitude control, this chapter will research on the dynamics and attitude control problems of flexible multi-body spacecraft which will be used in the future space missions. Through investigating plentiful literatures, it is known that some important progress has been obtained in the research of flexible multi-body spacecraft dynamic modeling and fuzzy attitude control technologies. In the aspect of dynamic modeling, most models were founded according to spacecrafts with some special structures. In order to satisfy the requirement of modern project design and optimization, acquire higher efficiency and lower cost, researching on the dynamic modeling problem of flexible multi-body spacecraft with general structures and founding universal and programmable dynamic models are needed. In the aspect of attitude control system design, the issues encountered in flexible spacecraft have increased the difficulties in attitude control system design, including the high stability and accuracy requirements of orientation, attitude control and vibration suppression, high robustness against the different kinds of uncertain disturbances. At the present time, classical control theory and modern control theory are often used in flexible multi-body spacecraft attitude control. These two methods have one common characteristic which is basing on mathematics models, including control object model and external disturbance model. It is usually considered that the models are already known or could be obtained by identification. But those two methods which are based on accurate math models both have unavoidable defects for large flexible multi-body spacecraft. Until this time, the most advanced and effective control system is the human itself. Therefore, researching on the control theory of human being and simulating the control process is an important domain of intelligent control. If we consider the brain and the nerve center system as a black box, we only investigate the relationship between the inputs and the outputs and the behavior represented from this process, that is called fuzzy control. The fuzzy control doesn’t depend on the accurate math models of the original system. It controls the complicated, nonlinear, uncertainty original system through the qualitative cognition of the system dynamic characteristics, intuitional consequence, online determination or changing the control strategies. This control method could more easily be realized and ensured its real time characteristic. It is especially becoming to the control problem of math models unknown, complicated, uncertainty nonlinear system. Accordingly, large flexible multi-body spacecraft attitude control using fuzzy control theory is a problem which is worth researching.