GPS/GLONASS Attitude Determination Research under Long Endurance and High Dynamic Conditions
|School||Shanghai Jiaotong University|
|Course||Instrument Science and Technology|
|Keywords||GPS GLONASS GNSS attitude determination multi-antennae analytic method ambiguity ambiguity function method INS|
The background and technological requirements of this thesis are based on the national 863 project,“High Precision Integrated Navigation Technology under Long Endurance and High Dynamic Conditions”. According to the actual experience about guidance of aero carriers, the author and team members of the project researched and designed a kind of multi-antenna attitude determination system using GPS/GLONASS, and completed the integration with inertial instruments. Furthermore, a theoretical prototype was achieved. Under participations and instructions of the author’s adviser, other teachers in staff room and cooperative orgnization, a multi-antenna attitude determination system using GPS/GLONASS was researched and built, and a prototype machine, which combined GPS/GLONASS attitude determination system with INS, was implemented. Then, static and dynamic experiments were conducted.Multi-Antenna attitude determination system using GPS is gradually replacing traditional methods owing to the high precision, no cumulative error, no-misalignment, and low-cost. However, only GPS attitude determination system has a serial of limitations, the GPS/GLONASS combinated attitude determination system has the characteristic of high reliability, high efficiency and high precision. Till now, multi-antenna attitude determination products adopting satellites are still mainly from European countries and U.S. and mainly based on GPS.Firstly, investigation, analysis and summarization about appilications of multi-antenna attitude determination system using GPS/GLONASS in aero and space area was delt with. Secondly, the application requirements and specifications of multi-antenna attitude determination system using GPS/GLONASS were determined. Thirdly, the coordinate system, the algorithm of attitude determination using carrier phase, the resolution of OTF integer ambiguity, the principle of GPS/GLONASS receiver and related issues were deeply investigated. According to performances and features of attitude determination system using GPS/GLONASS, system design and error analysis were accomplished, and an error model and an observation equation were established. All the work mentioned previously lays the theoretical foundation for establishment and implementation of the high precision attitude determination system using GNSS. Based on the research of theory, the system simulation, the hardware platform construction, the software test and examination were carried on and a test facility was set up. According to application requirements and specifications, a series of key technological problems were conquered in the process of system implementation. To address the issues from static and dynamic experiments, improvements and perfection of the system were performed.The main work that this paper accomplished including:1) A navigation scheme, which integrated GPS/GLONASS with INS for attitude determination, is put forward together with teachers involved in the project. Prior to this, great efforts are put into investigations of attitude determination system under long endurance and high dynamic conditions. At the same time, the requirements on attitude determination system, which is from control system and guidance system, was deeply researched. Besides, extra issues are also considered, such as components available, specifications of the project and so on.2) A full-scale theoretical basis was founded by studying the theories and development of GPS, GLONASS, comparing the similarities and differences of the two systems, analyzing a serial of questions and errors when the two systems combinated.3) According to the special application conditions and operating environments, corresponding attitude measurement equation, which is based on local level coordinates system, is set up, and a new attitude calculation method is proposed.4) On the basis of deeply researches about various OTF ambiguity resolution methods, an improved ambiguity function method is proposed, and the results of simulations and experiments are attached.5) Development and tests of multi-antenna attitude determination prototype machine are covered, including the purchase of hardwares, system building, interface design, structural and installation design, software development, system debug and so on.6) Outcomes of the static, dynamic and compare experiments are provided. Furthermore, some improvements and enhancements were done to address issues exposed in experiments. The final system met all of the design criteria and results meet the original specifications.To address issues in system requirements and problems exposed both in theoretical research, simulation, prototype development and system experiments, a series of key technologies were examined and conquered including:1) Research on measurement model of carrier phase single difference integrated attitude determination in 3 dimensions, which is based on local level coordinates system using GPS/GLONASS.2) On the basis of traditional attitude determination algorithms, a new algorithm was proposed, which used analytical method to determine the attitude of single baseline.3) A new algorithm, which used analytical resolutions of non-linear double baselines to determine the three dimensional attitudes of a carrier, was thoroughly investigated.4) Research of improved ambiguity function method applied in GPS/GLONASS attitude determination.5) Utilizing three OEM boards feeded with a common clock, a protoype machine was implemented, which could determine a carrier’s three dimensional attitude angles.6) Related algorithms were developed, which were based on multi-antenna GNSS attitude determination in three dimensions.7) An algorithm for integrated system was developed, which combined multi-antenna GNSS attitude determination system with INS.Of which, the innovative works include:1) The high precision and high dynamic attitude determination system, which is based on single-carrier phase difference in GPS/GLONASS and its application in hypersonic cruise missiles, were researched.2) A new algorithm used in three dimension attitude determination system, which was based on analytical method of double satellites, was proposed for the first time.3) On the basis of ambiguity function method and least squares search method, a new method, which was based on improved AFM method of intersection point on sphere, was proposed.4) Through improving common single frequency OEM board, a attitude determination system prototype, which is based on GPS/GLONASS, was designed and built.5) The integration of attitude determination system based on GPS/GLONASS and INS was researched preliminarily. In conclusion, this paper’s results had the following features:1) High precision. In condition of 2 meters baseline, the precision of attitude determination system achieved 0.1 (1σ);2) More reliable results, smaller amount of computation, shorter initialization time, and better integration performance with INS. All of these features could meet the requirements of high dynamic environment.3) The ultimate satellite number, which was used to get a carrier’s three dimension attitude angles through analytical resolution, was reduced to 2. This feature met the acquirements of attitude determination in bad satellites’signal tracking condition, such as blackout. And results of dynamic vehicle experiments in bad conditions also proved the feature.Above features and inherent feature of no accumulated errors of GNSS attitude determination system could meet the acquirements of high precision attitude determination system under long endurance and high dynamic conditions.At the same time, it should be noted that, the algorithm this paper proposed could not only be applied to GPS/GLONASS, but also could be applied to European GALILEO and Chinese COMPASS II, which would be put into operation in future.