Study On The Enhancement Of The Accuracy Of Laser Tracking 3D Coordinate Measurement

In recent years, more and more 3D coordinate measurement requirements have appeared in the fields such as industry, national defense, etc, therefore various kinds measuring systems have been developed. Among these systems, more and more attentions have been paid to the laser tracking 3D coordinate measuring system based on multi-lateration principle for its advantages such as high accuracy, large measuring range, flexibility, dynamic measurement, in-situ measurement, self-calibration, lost information recovery. With the financial support from the National Natural Science Foundation of China (project contract No. 59875064), a four-beam laser tracking 3D coordinate measuring system has been developed by our research group.In this dissertation, a study on the enhancement of the coordinate measurement accuracy of the system is carried on. The main work and creative research fulfilled in the dissertation include:1. Extensive investigations on the progress and status quo both at home and aboard about 3D coordinate measuring techniques, especially about laser tracking 3D coordinate measuring techniques, are carried out. Working principle and main functional characteristics of the four-beam laser tracking 3D coordinate measuring system are analyzed. Design considerations of the main subassemblies of the system are introduced.2. The 2nd and 3rd generations of the folk-supporting tracking mechanism with a single tracking mirror and two independent drives are designed. By improving the principle, structures and techniques, the accuracy of the tracking mechanism is enhanced.3. A hemisphere-supporting tracking mechanism with a single tracking mirror and two independent drives is designed. A steel ball which has high form accuracy is used to produce the hemisphere and components to adjust the mirror eccentricity and the position of the laser spot is configured. These measures enhance the accuracy of the tracking mechanism significantly.4. The idea that measuring optical error of the cat's eye retro-reflector and then compensating it in the process of self-calibration and coordinate measurement according to the measured result is proposed. A simple and practical measuring method to measure the optical error of the cat's eye and associated data processing method, a method to correct the optical error of the cat's eye in the process of self-calibration and coordinate measurement, are proposed.5. An overall and detail analysis for various error factors which affect the 3D coordinate measurement accuracy of the system is carried out.6. Further studies on system arrangements of self-calibration and 3D coordinate measurement are carried out. Through simulation and comparison, a new self-calibration plan is proposed which can make errors of systematic parameters smaller. Based on above, system arrangements when tracking range is limited is studied.7. Corresponding experiments and simulations are done according to associated studies.