Research On Autonomous Health State Assessment Method Of Micro-Satellite

Micro-satellite is developed based on microelectronics, with advantages of small size, low power consumption, light weight, low cost, low risk and short development cycles and so on. Most devices of micro-satellite are commercial off-the-shelf industrial-grade components, with high integration and low accuracy, but they are more likely to suffer the effects of the space environment. The orbits of micro-satellite are most low earth orbit, ground control personnel have been unable to detect and deal with the on-orbit faults because of the limited time of satellite passes. Some failures on-orbit for micro-satellites not only affect the work of satellite, they may also give rise to permanent damage of the onboard equipment, such as single event affect. Research on autonomous health state assement method of micro-satellite can be realized on-orbit status monitoring and fault handling, can also provide references for ground testing and screening.Based on the hierarchy of micro-satellite, we should analyse the health state of component, subsystem and system of micro-satellite to realize the micro-satellite health state assessment. According to the characteristics of micro-satellite health assessment information generation and transmission, model of health assessment Petri net is innovated and its mathematical description is given. In this health assessment Petri net for micro-satellite, health state information of the minimum monitoring units is taken as the input. The health state of satllite units is described by five levels of health state, that is healthy, subhealthy, neutral, degenerate, dangerous. The model of micro-satellite health assessment Petri net can directly describes the micro-satellite hierarchy, reflect the association between components and systems and the rules for health reasoning. The model of micro-satellite health assessment Petri net is pure net without conflict and deathlock. It can realize system modular modeling through the deletes, inserts, and synthetic operation of the health state model.To reflect the association between components and systems and make health assessment results more reasonable, some model parameters are studied, such as the health grade, weight, degree of confidence and so on. The data dimensionless method, the determining method for weights of characteristic parameters, the determining method for health grade, and the factors of degree of confidence are analyzed to relize the health state assement of micro-satellite.Finally, this paper establishes a health evaluation Petri net model for Lilac Sat-2 micro-satellite, and achieve the health state assessment based on its telemetry data. Through finishing the health state assessment of Lilac Sat-2, it verifies the validity of the health state assessment Petri net model for micro-satellite.