Design Of Intelligent Monitor And Control System For Satellite Environment

The major task of satellite environment control is to guarantee that the satellite tested in launch complex is kept in the environment as required in terms of temperature, humidity, cleanliness, vibration, ect. Therefore, it is a key research project of Xichang Satellite launch center .The upgrading of intelligence standard in the satellite environment control is of great significance to assure the satellite's quality, prolong its working life, and sharpen China's competitiveness in the international commercial satellite launch market. On the basis of analysis of pre-launch satellite's requirement to the environment in different stages in addition to the current state and defects of the satellite environment control system, the paper presents a new concept and specific method to design a new satellite environment control system by applying fuzzy logic theory. With the design and simulation of intelligent satellite environment control as the highlight, the paper illustrates that the basic means to realize the intelligent control is to design a fuzzy logic-based satellite environment controller. The paper can be divided into three parts. The first part clarifies the tasks and features of satellite environment control, establishes a model and makes clear the control tactics of system according to the work process of satellite environment control after introducing and analyzing the working environment characteristics of pre-launch satellites and the major factors may be concerned. The second part is highlighted by the design of fuzzy logic controller of the system. Firstly, the design of the controller's single variable and two dimension system structure which takes the error change rate as well as error into account and improves the system structure's properties. Secondly, the determination of out/input variables and universe and the adoption of appropriate membership degree function to fuzzily them. Thirdly, he formulation of 56-point temperature control rules on the basis of sum-up of the knowledge and experience of the experts and operators who are long-timer in the satellite environment control. The production rules enable the accurate and detailed expression of the experts' control thinking, which makes fuzzy logic controller characterized by artificial intelligence function as experts do in a certain degree. Fourthly, the design of fuzzy inference engine for satellite environment control in accordance to the fuzzy inference theory. Fifthly, the derivation of control output and fuzzy control table. The contradiction between the slowspeed of controller resulting from the great computation volume and strict requirement of satellite environment to real-time properties is settled by adopting fuzzy logic control table method. The third part conducts a simulation of the designed fuzzy logic control system with the MATLAB as the platform and the system's dynamic properties as the focus to test whether the system's membership degree function and control rules is appropriate, and whether the system design is rational in addition to optimizing the system's parameter. The comparison between fuzzy controller and PID controller proves that the former is better than the latter in respect of dynamic properties and robustness. And therefore it is exceptionally applicable to the control system of spacecraft launch complex.