Study On Laser Gyro Inertial Surveying And Attitude Reference Systems By Dynamic Constraint Analysis

This thesis is aimed to investigate the laser gyro inertial surveying and altitude reference systems in the condition of dynamic environment . The work is based on some important practical engineering researches in which the author involved, including :1) A railway track surveying experiment system on laser gyros.,2) The laser gyro attitude reference system of a fire control system.3) Theoretic and experiment study of a shipboard attitude reference system using laser gyros.Many references show that the theoretic and practical researches on inertial surveying and attitude reference systems are predominantly in the field of sensor data integration. It is suggested that the dynamic constraint or character of the body attitude is also a kind of information in many engineering applications. A series of effectual algorithms based on the dynamic constraint of the body attitude is presented in this thesis .Two aspects of applications of the body dynamic constraint are analyzed as follows:1) The inertial surveying and attitude reference system with incomplete inertial sensors.2) The identification of the undetermined parameter in the inertial surveying and attitude reference system.Common theoretic problems in a variety of engineering applications are analyzed as follows:1. The laser gyro inertial surveying and attitude reference system model with incomplete inertial sensors are first derived under the body dynamic constraint. The different characteristics of the dithered laser gyro and the four frequency laser gyro are analyzed.2. The time variant nonlinear model of the laser gyro inertial surveying and attitude reference system is changed and simplified to time invariant linear model of the error states using robust analysis method . These results make frequency analysis based on transfer function become possible which is important for dynamic system analysis .3. Model transformation method are induced to avoid conservative robust design by decreasing the model uncertainties . The robust stability condition of periodic time variant system is derived.4. Considering the body dynamic constraint , system parameter identification method based on frequency domain analysis and correlation is bring forward. It is shown that the complicated identification problem in time domain model can be rather simple in frequency domain model.The theoretic analysis based on body dynamic constraint lays a foundation for further engineering researches which are shown as follows:1. Different characteristics of the railway track surveying system and the attitude reference system for fire control are analyzed. The body dynamic constraint conditions in frequencydomain are derived for these two applications. The relationship between the body dynamicfrequency bandwidth and the precision of the dynamic surveying with incomplete inertial sensors is clarified which can be a guideline for practical inertial system designs.2. The necessity and difficulty are discussed for the in-place calibration of inertial measurement unit being subjected to the vibration, shock and acceleration induced by the host vehicles. A new in-place calibration method based on the fixed axe rotation constraint is presented.3. The system performance variations for the railway track surveying due to the different choices of coordinate projection and system model description are analyzed . A new algorithm based on incomplete inertial sensors is presented which still has appropriate measuring precision when the train passed switches and curves.4. The identification and compensation of the lever-arm effect in the shipboard inertial system are analyzed by which accurate measuring of roll and pitch angle is achieved .5. Some engineering problems associating with practical research projects are discussed . The vector analysis method for strapdown north finding systems is introduced by which system error analysis is simplified. A new railway train location algorithm for track surveying based on the charac...