Research On Fault Diagnosis Method For Spacecraft Monopropellant Propulsion System And Its Realization

This paper mainly studies the fault diagnosis of satellite monopropellantpropulsion system. Based on the analysis of monopropellant propulsion systemcharacteristics, this paper studies satellite fault detection method, analyzes failuremode of propulsion system, establishes a real-time expert diagnosis system, andrealizes the satellite fault monitoring and diagnosis in its process of running and itsresponse in time when it goes wrong to minimize the effect caused by faults. Finally,software platform of satellite propulsion system fault diagnosis is built throughVC++6.0.This paper firstly analyzes the basic structure of liquid monopropellantpropulsion system, on the basis of which mathematical models of propulsion systemin various parts are built and mathematical simulations of propulsion system areimplemented via matlab. Then based on the simulation, the system characteristics areanalyzed. And at last, fault model of every component in the propulsion system isbuilt, which lays a foundation for the following fault detection and diagnosis.In order to realize the fault diagnosis detection of satellite propulsion system,the paper analyzes the operation process of propulsion system. And according tocharacteristics in time domain of the propulsion system, the paper studies faultdetection method respectively based on the threshold and based on the sequentialprobability ratio test, both of which can be well applied in satellite fault detection; inaddition, according to the characteristics in frequency domain of propulsion system,the paper studies fault detection method based on Hilbert-Huang Transform (Hilbert-Huang Transform，HHT). Finally, expert diagnosis system is established. The rulesin the knowledge base are summed up and design method based on backwardreasoning principles of inference engine is given according to propulsion systemfailure mode and effect analysis in the Failure Mode and Effects Analysis (FailureMode and Effects Analysis, FMEA) table, which culminates in the establishment ofthe satellite fault diagnosis expert system.At last, software platform of satellite propulsion system fault diagnosis is built.The platform realizes three functions, including dynamic display, real-time faultdiagnosis, and simulation fault diagnosis of satellite running state parameters.Dynamic display can display satellite current operating condition in real-time; realtime fault diagnosis uses the satellite transmission parameters to monitor satellite inreal time, to prevent the fault from damaging system; simulation fault diagnosis usessatellite test process parameters and inject faults on the basis of fault model to detectthe accuracy and practicality of fault diagnosis. User interface of the program isdesigned through VC++6.0, and the whole diagnosis system is established with theuse of C++, which has excellent versatility and portability.