Study On GPS Attitude Determination System

The real-time attitude parameters estimation of platform is always an important research branch in measurement and control domain. But the traditional attitude determination ways have many abuses in the aspects of processing speed and system cost. Along with the elevation of positioning precision basing on GPS, the platform attitude determination technic with GPS has come into being. This paper investigates the single-baseline two-dimensional attitude determination technology which is based on GPS, and provide theory and practis basis for platform attitude determination with GPS.Firstly, this paper introduces the system composing of GPS, positioning theory, carrier phase measurement theory, error sources of GPS measurement and the corresponding resolving means. Then discuss the attitude determination theory in detail, and introduces the related coordinate systems, the conversion relationship of the coordinate systems, the observation equations of attitude determination too. The key problems of attitude determination that ambiguity resolution and cycle slip detection are also discussed in detail in this paper.This paper proposes a two-dimensional attitude determination system which is composed of PC(notebook PC) and PC104 based on the principal and subordinate mode. The lower position machine is composed of a PC104 mainbord, two OEM4 GPS receivers and two 701 L1 antennas. The paper introduces the data format of GPS receiver and data preprocess exhaustively. The software of upper/lower position machine is developmented with C in C++ Builder and particular design flow chart is proposed.Finally, field tests approve the performance of the proposed attitude determination system. Under the static condition, the test shows the correctness and reliability of the proposed attitude determination system versus the dedicated heading determination system, and we get good precision. Then, two another tests show the baseline length and mask angle's affection on measurement precision under the static condition. The dynamic test shows that proposed attitude determination system can work steadily under dynamic condition, but the precision isn't as good as static test. Also, the system cost is taken into account, and there are tests showing the performance of another attitude determination system which integrated with low-cost GPS receivers. The test results show that the low-cost attitude determination system can work well under static condition, but can't work steadily under dynamic condition.