Research Of Inertial Positioning Technology Based On Cadastral Surveying Process

The conventional measurement method based on satellite positioning, total station and other measuring technology has the defects of high dependence on environment and low efficiency. By taking the advantages of low dynamics and "halt-measure-move arbitrarily" of the cadastral surveying process, strapdown inertial positioning technology which has characteristics of low environmental dependence, strong anti-interference ability, simple structure and easy maintenance was proposed for cadastral surveying in this thesis. Aiming at the error accumulation of strapdown inertial measurement system, the method using different special measuring points in cadastral surveying process, H2/H∞ filter and UKF-KF filter is put forward to estimate and compensate system errors of strapdown inertial mesurement system and errors of inertial sensors, which can finally get high precision positioning information of cadastral surveying points to be measured.The main research work of this thesis includes the following three aspects:1. The basic principle of application of strapdown inertial measurement system in cadastral surveying is described. The positioning performance of strapdown inertial measurement system in inertial working condition is analyzed. According to the characteristics of dynamic measurement process, the calculation method of quaternion differential equation for attitude calculation of strapdown inertial measurement system is improved. The influence of different quaternion updating algorithms on the final postioning performance is given. The error equation of strapdown inertial measurement system is derived, at last.2. The application strategy of special measuring points in cadastral surveying is investigated. System state equation and obserbation equation of strapdown inertial measurement system on different special measuring points are derived in detail. Then, based on the mathematical model of strapdown inertial measurement system, the degree of observability of system state variables on different special measurement points is analyzed by using the method of singular value decomposition (SVD). The estimation effect of system state variables on different special measurement points is given based on Kalman filter (KF). At last, according to observability analysis conclusions and KF simulation results, the application stategy of special measuring points is given.3. The applications of H2/H∞ filter and UKF-KF filter in cadastral surveying are investigated. When the accuracy of system model is bad or the statistics of system noise is unkown, the standard KF meets the problem of accuracy decline and even filter divergence which leads to the requirement of high accuracy of cadastral surveying can not be satisfied. Aiming at this problem an estimation weghted H2/H∞ algorithm based on nonlinear mapping is proposed in this thesis. Taking zero-velocity correct point as an example, the applicacibilty of H2/H∞ filter in cadastral surveying is given. According to the actual situation of cadastral surveying on position-kown points, in order to improve the measuring efficiency, a nonlinear system model is derived and simplified. Based on the idea of mixed dynamic filtering, UKF-KF filter is proposed to estimate and compensate system state on position-kown points.Mathematical and simi-physical simulation experiments are carried out to prove the validity and effectiveness of the application strategy of special measuring points and practical filtering techniques proposed in this thesis.