The Application Of Fuzzy Control Theory In Attitude Control Of Launch Vehicle

In this dissertation, the fuzzy control method of attitude-control system is investigated, and is validated through simulation.The contributions include the following:1. The launch vehicle control system with classical control theory is introduced. And the defects of this design method are pointed out, which include the difficulty in selecting parameters of the controller, the complexity and long period of the design process, and poor adaptability to the change of the parameters of the vehicle.2. Several kinds of the fuzzy self-adaptive control methods are introduced. And the factors that affect the performance of the fuzzy control system are analyzed. The simulation shows that fuzzy controller with self-adaptive proportion factor has good performance.3. The normal fuzzy attitude control system of the pitch channel is designed based on rigid model of a launch vehicle, which is used to send satellite A. In order to improve the normal fuzzy controller's performance, no-quantification analytic fuzzy method is adopted; and is validated by simulation.4. The advanced fuzzy controller based on rigid model is directly used in the attitude control, the simulation shows that the attitude angle error is large because of the elastic vibration affection. So a filter is adopted, and the results of simulation illustrates that it is effective.5. A kind of fuzzy self-adaptive controller with proportion factor and modificative factor self-tuning is presented to replace the advanced fuzzy controller. From simulation, it can be concluded that the fuzzy self-adaptive controller has better performance and is more adaptive to parameter change than the controller designed with the classical control theory or advanced fuzzy control method.6. The fuzzy self-adaptive controller is applied to the attitude control of the launch vehicle used to launch the satellite B. From the simulation we find that the controller is applicable and has better performance than the classical controller.It is concluded that fuzzy control is well suited to the attitude control system of launch vehicle, and the fuzzy controller is simpler and adaptive to the parameter change, and achieves better performance than the classical attitude control system.