Study And Development Of Attitude Determination System Based On GPS

With the rapid development of the carrier phase differencing technique and digital signal processing hardware, it is possible to implement real-time processing of GPS based attitude determination system. Real-time attitude determination is derived from extremely precise differential carrier phase measurements among multiple GPS antennas mounted on the vehicle. In this dissertation, the theory and method of GPS based attitude determination techniques are studied, and the algorithm is deducted in detail, a real-time attitude determination system scheme is also proposed.Carrier phase measurements were post-processed using a double difference approach in which integer ambiguities were resolved in seconds using the known antenna separations as constraints. So the integer ambiguity resolution is the key problem here. To shorten the time of the solution of integer ambiguity and improve its validity, the LAMBDA algorithm is introduced. And the attitude parameters are estimated using direct computation method. Attitude determination with GPS is investigated with emphasis on algorithms of attitude estimateion and on ambiguity resoluteion on-the-fly. Detailed expressions are derived.At last a GPS based real-time attitude determination system scheme using two baseline is proposed, in which the GPS receivers are Jupiter OEM. This system has a two-CPU (16 bit MCU+DSP) structure. The high speed DSP (TMS320VC5416) handles signal processing in real time and the MCU (MSP430F169) processes all other general tasks. Most parts of the system's hardware and software are illuminated.