Development of a safe mode attitude control for a FPGA based micro satellite

This paper presents the development of the safe mode attitude controller for the micro-satellite Flying Laptop (FLP). The safe mode for the FLP is defined as the situation when the satellite is able to continue its normal operation with reduced functionality on the occurrence of serious anomaly in the software or the hardware of the satellite, which cannot be automatically processed and corrected on board. This mode is used to ensure the satellite's vital functions (e.g. on board power) while in the meantime, the failure is being analyzed on ground. In safe mode, the satellite is controlled through autonomous software dedicated for such a condition. The sensors used for this mode should reflect high reliability and the sensor outputs need to be available all the time, however only a coarse pointing knowledge is required during this mode.