Study On Rapid Tracking And Measurement Of Laser Tracker

Laser tracker is a three-dimensional coordinate measuring instrument with large measuring range. With the feature of large measuring range, high precision and real-time tracking, it is widely used in large aircraft assembly, automobile manufacturing, robot posture correction and scientific research. Based on the structure of UOI laser tracker, this article is mainly studied the key technology such as method of absolute distance measurement, the method of dynamic target position deviation detection and real-time tracking feedback control. The subject improves the ability of measurement and tracking of UOI laser tracker system. Meanwhile, it lays a solid foundation for the development of laser tracker product with independent intellectual property rights. The main research works of the dissertation can be summarized as following:Based on the measurement model on three-dimensional coordinates of the laser tracker, the tracking principle of system and the beam projection principle of target detection unit are analyzed. A compensation model of spatial coordinate measuring is established. The decoupling relation between the dynamic measuring deviation and the PSD coordinate is studied. Aims to fulfill the requirement of rapid tracking measurement, a overall scheme of monitoring and control for laser tracker is designed.To solve the problem that measurement accuracy is limited by the original system whose optical path is built by discrete components, an integrated optic-mechanical platform for detection is designed, which use a IR semiconductor laser as tracking light source. Because PSD detection accuracy is limited by the stray light back light from optical surfaces, a hardware and software filtering unit and interference spot compensation unit are designed. It fulfills the requirement of real-time testing for fast moving target position deviation. Using the reference position from the certain way to achieve dual-frequency interference absolute distance measurement. An electronic breakdown module which can achieve the subdivision count for 32 times is designed. It achieves a resolution of 0.01μm interference distance.Based on PID regulation mode for servo control, the advantages and disadvantages of the servo system speed loop control strategy and position loop control strategy are compared. And then the theoretical track faster speed loop control strategy is chosen. The tracking control algorithm is designed, and a tracking parameter estimation model is established. To fulfill the technical requirement of servo tracking control, the angular coordinate measuring technique, the modulus transmission technology and dual core cooperative communication technology are studied. Based on USB communication, a Lab VIEW real-time 3D dynamic display interface is built, which achieves the real-time monitoring to measurement results and the state of various parts.Finally, a single station laser tracker system is established based on the overall scheme. Experiments that single-axis tracking speed tests, repeatability testing, system resolution experiment and comprehensive tracking and measurement experiments are conducted. The experiment results show that the laser tracker rapid tracking and control system can track the target of up to 0.51 m / s velocity perfectly within the 3.5m. System repeatability is better than ± 10.6μm, and measurement resolution can reach 10μm.