Research On Fault Prevention Technology Of Satellite Attitude Control System Based On Fuzzy Mapping Relation

Although the satellite attitude control systems are developed in details under strict management system,failure is inevitable due to the complex system composition and harsh working environment.Some failure gives rise to the degeneration of satellite attitude performance,some leads to error pointing,some even results in all failure of on-orbit missions which leads to tremendous economic loss.It is of great significance to carry out the research of on-orbit satellite fault prevention technology for on-orbit maintenance,to avoid fault propagations and reduce the rate of satellite failure.This paper focuses on fault prevention technology applied to satellite attitude control system(SACS).The typical failure modes of key components of the SACS are firstly analyzed,and the study of the relationship between failure modes and prevention actions is followed.The research is expanded by a fuzzy relationship between fault modes and prevention actions built with regarding of the restriction of satellite energy and the reliability index of the changed SACS system after actions.Firstly,studying the structure and working mechanism of satellite attitude control system,analyzing the causes,model and influence of key components failure of the SACS.Based on the investigation of a large number of documents,this paper establishes mathematical models for actuator,sensor and controller of SACS,then analyzes the causes and influences of the their failure.Secondly,the relationship between typical faults and prevention actions is studied.The system is divided into several fault levels according to the pointing error.And the common prevention actions are classified from the perspective of hardware and software.Based on summarizing and analyzing the actions,the relationship between fault and prevention actions based on the fault level is established.Thirdly,studying the selection of fault prevention actions based on system energy restriction.The prevention actions should satisfy the allowable range of energy consumption of the system,otherwise,exceeding the range,the prevention actions could not be implemented.Considering the restriction of the energy,this paper carries out the study on prevention actions select strategy focusing on the typical actuator fault situations.Introducing the fuzzy mapping relationship between typical failure and prevention actions based on the energy restriction of the system and verificate the theory through simulations.Finally,studying the selection strategy of fault prevention actions based on system reliability prediction.Considering the situation that various measures could be adopted,this paper studies the system failure recovery cost and introduces the reliability factor to describe the influence of cost on the reliability of the system.Using the Petri net model to describe the process of system state transition after executing the actions,then predicting the reliable operation time of the system degeneration starting with the state after executing the prevention actions.Combining the reliability factor and the results of prediction to obtain the reliability index,which eventually guild the determination of appropriate fault prevention actions.