GPS/Gyro Integrated Attitude Determination for Near Equatorial Orbit Micro Satellite

A short baseline GPS attitude determination system integrated with 3-axis Fibre Optic Gyro (FOG) for a Near Equatorial Orbit (NEO) satellite is studied in this paper. GPS carrier phase based attitude determination is described briefly first, then the mathematics model of GPS and gyro integrated system is given in detail. A hardware-in-the-loop experiment with Spirent GNSS Simulator 8000 connected to NovAtel OEM 6TM Receivers was conducted. Raw data of GPS L1 carrier phase, pseudorange observations and GPS satellite ephemeris RINEX files of a typical earth pointing NEO satellite was collected in the experiment. The processing results show that for a short baseline of 26.7 cm, if GPS/Gyro integrated attitude determination system is used to replace GPS standalone attitude determination system, one order of magnitude improvement in attitude accuracy from several degrees to several tenth-degrees is achievable; GPS and FOG integrated system, which can provide continuous attitude to bridge the gap of GPS standalone attitude determination caused by ambiguity resolution failure, is a potentially robust, continuous, high accuracy and high update rate attitude determination system for NEO satellite.