Study On External Reference Establishment Of Three-dimensional Deformations Optical Measurement System

A Three Deformations Optical Measurement System (3D-OMS) based on autocollimation light path and CCD imaging is used to measure the deformation of deck onthe ship, but there are some distances between reference of the main inertial navigationsystem (INS) and the measuring points of the3D-OMS. For this reason, an externalreference of the3D-OMS is needed to build and to transfer from the INS to the3D-OMS. This makes the relative deformation angles in the3D-OMS are transferred tobe absolute deformation angles in the INS coordinate system or even in the terrestrialcoordinate system. Some cubic mirrors are adopted as external coordinate carrier andtwo methods of coordinate calibration are proposed for the two parts of the3D-OMS byusing theodolites. Besides, reference transmission techniques are investigated, and areference transmission methodology is designed base on the mature techniques oftheodolite measurement, the results of experiments show the methodology is with highaccuracy. The main works in this paper are1. Principle and application of the Three Deformation Optical MeasurementSystem (3D-OMS) are introduced briefly. The measurement accuracy of the3D-OMS istested in two different ways. One method is only use high accuracy autocollimator tofinish accuracy test of the3D-OMS; and the other method is to use both autocollimatorand electronic level meter to finish the accuracy test. Experiments show that twomethods are equal in accuracy.2. Definitions of coordinates in the3D-OMS especially the coordinate in theemitting part and the CCD coordinate in the receiving part are introduced. Meanwhile,the establishment of external coordinate by using cubic mirror is introduced. Then twodifferent calibration methods are proposed to finish the coordinate calibration in theemitting part and the receiving part. At last, axis error of theodolite is analyzed.3. Principle of reference transmission is investigated, and a methodology ofreference transmission is designed. Then the error components of reference transmissionare analyzed.4. Experiments are designed to finish the calibration of CCD coordinate and theexternal reference in the receiving part. Experiments of reference transmission indoorare finished. Different attitudes of three cubic mirrors are detected and transferred to theunified coordinate, attitudes transmission between three cubic mirrors can achieve to5″, and the relative attitude transfer to absolute attitude is achieved.