Research On Key Technologies Of 3D Ship Deformations Measurement Based On Collimated Conjugated Optical Structure

The synchronous and highly accurate measurement for three dimensional(3D) ship deformations plays an important role in the establishment of the unified spatial coordinate reference, the improvement of the ship combat capability and the ship construction design. However, 3D ship deformations measurement is a difficult problem around the world, not only for the complexity of the ship structure, but also the variability of the performance environment. In this paper, we propose a highly accurate optical collimated method, to realize the highly precise 3D ship deformations measurement. With the research on the measurement principle and the key technologies of the method, we achieved the accuracy of arc-second and sub-arc-second. At the basis of theoretical investigation, we developed a 3D ship deformations real-time measurement system, and the experiments of ship deformations measurement were carried out at sea. The main researches and creativities of this dissertation are as follows.(1) We proposed a 3D deformation measurement method based on the collimated conjugated optical structure, aming at the requirement of long distance and highly precise measurement for the naval vessel. According to the light propagation in the optical system, we established the imaging model of the collimated optical structure. We demonstrated the relationship between the imaging variation and the 3D deformations, and the calculation method of the 3D deformations is proposed according to the variation of the image features.(2) Based on the image model of the collimated optical structure, we analyzed the restricted relationships between the structural parameters and the measuring performances of the optical system, and proposed an optimization method. According to the imaging model of the collimated optical structure, we investigated five restricted relationships in the collimated measurement system, and demonstrated the relationships between each pair of the measurement precision, the measurement range and the measurement distance, of which the improvement always results in the degradation of the other. In this way, we research on the optimazation of the parameters of the optical system to meet the requirements of the practical measurements.(3) We established the imaging model of quasi-collimated optical structure, and analyzed the measurement errors of the 3D deformations caused by the minor maladjustment of the optical elements. Minor deviations of the positions and attitudes of each components in the optical system are inevitablely taken place in installation process of the optical system, thus the practical optical structure is a quasi-collimated optical structure, rather than collimated optical structure, by which the measurement errors are induced reaching to several tens of arc-second or even larger. We investigated imaging model of quasi-collimated optical structure in detail and demonstrated the relationship between the measurement error and the maladjustment parameters.(4) We proposed the measurement method utilizing the special projected object to improve the measurement precision, particularly, the measurement of the roll angle. We proposed the measurement method of rolling angle based on the gray intensity distribution of the target figure, and established a model to estimate the measurement precision. We carried out the experiments of 3D deformation measurement based on the cross-fringes and the 20×20 point arrays, and the results indicated that the precision reached to arc-second, and sub-arc-second respectively.(5) Aiming at the requirement of practical measurement, we developped the synchronous measurement system of the 3D deformation. According to the practical environment, we analyze the error induced by atmosphere turbulence, image processing, and maching assemblage and so on. We also executed the static test of the main properties of the measurement system, and the results indicated that the measurement precision was better than 1", with the measured distance of 22 m and measured range of-150″~150″. We accomplished the experiments on the naval vessel, further demonstrated the validity of the measurement method.Both the theoretical and experimental studies shown that the collimated optical measurement achieved real-time, high-precision and non-contact measurement of 3D ship deformations. With further research, this method can be used for the measurement of 3D deformations of other large platforms.