Research On Long-range Collimation Of Tracking Beam And Dynamic Measuring And Control Technology For Laser Tracker

As a high-precision and large-scale three-dimensional coordinate measuring instrument in modern industrial measurement systems, laser tracker combines laser interferometer measurement technology, photoelectric detection technology, precision machinery technology, servo motor control and computer technology, which can track moving targets, and measure targets’ three-dimensional coordinate real-time and dynamically with high accuracy. Because of the numerous advantages such as large measuring range, high measuring accuracy, measuring efficiency and excellent dynamic performance, laser tracker has been widely used in the many industry fields such as the large equipments’ assembly and testing, and laser tracker is an important indicator to evaluate the level of modern precision equipment manufacturing.This dissertation, namely research on long-range collimation of tracking beam and dynamic measuring and control technology for laser tracker, based on th e existing laser tracker prototype structure, analyzes the working principle of the laser tracking system. Aimed at the problems that the tracking and measurement range is limited by the divergence characteristics of tracking beam, and the tracking speed i s limited by the bandwidth of the measurement and control unit, this dissertation carrys out researchs about the long-range collimation technology of tracking beam and dynamic measuring and control technology for moving targets, so that can achieve the tar get of large-scale and high-speed measurement and tracking, and lay a solid foundation of developing high-performance laser tracker with independent intellectual property rights. The main contents of this paper can summarized as following.Aimed at the first problem that the tracking and measurement range is limited by the divergence characteristics of tracking beam, this dissertation analyzes the influence of optical power and collimation characteristics of tracking beam, namely semiconductor laser, on tracking range. Aimed at the influence of the laser optical power on the tracking range, this paper redesigns the target displacement detecting and dual frequency interferometer optical path in the laser tracker system with the intent of improving the photosynthetic efficiency of two beam mentioned above, and the result show that the beam utilization is improved by 15 times.For the influence of the collimation characteristics of tracking beam on the tracking scale, this paper firstly analyzes the characteristics of semiconductor laser which passes through optical fiber before. and next, determine the tracking beam collimation scheme, including the collimation principle analysis, system design and simulation, and the mechanical structure design.Focused on the issue that the tracking speed is limited by the bandwidth of the measurement and control unit, this dissertation based on the tracking control principle of laser tracker, analyzes the effect of the target deviation detection module bandwidth on the tracking performance. Aiming at the influence, the circuit redesign of the target deviation detection module is carried out, which makes the bandwidth of the target deviation detection module more than 0.8 MHz, and meets the requirement of tracking system to the bandwidth, and the speed of response of the system is promoted. In addition, aiming at the problems that the design of signal demodulation and coordinate decoupling unit digital interface is complex, the optimization design of signal demodulation and coordinate decoupling unit digital interface is carried out, which saves chip resources, simplifies the hardware circuit and program design, and improves the control unit design and debugging efficiency.Finally, based on the composition of laser tracking and measurement system, this dissertation launches the experiment platform constructing of tracking and control system, and carries on the long range alignment test experiment of tracking beam, dynamic tracking performance test experiment and the large-scale tracking test experiment. The experiment results indicate that tracking beam characteristics in the range of 100 m meets requirements of tracking and measurement, laser tracker in the range of 10 m single axis tracking speed reaches 0.9 m/s, and the laser tracking system can meet the goal of dynamic tracking measurement for moving target with the distance range of 0.3m~10m, yaw range of ±180°and pitch range of 45°~135°.