Research On Design And Simulation Of High-accuracy Laser Tracker Control System

Focus on the tracking accuracy and response speed of Laser Tracker.Gradually, exploring the application and research status, measurement principle,system modeling, control system design and error analysis.Defense industry and civilian manufacturing enterprises would like to developtoward for high-precision and high-efficiency production, they need rely onhigh-precision, real-time, intelligent measurement instruments, instead of thetraditional measuring instrument. Laser Tracker, as a new three-dimensionalcoordinate measuring instrument, which owns the advantages above required and hasthe ability of parameters self-calibration. It has a broad application prospect, so theresearch work is very meaningful.The article elaborates the working principle, drive motor, reflecting mirror andsensors of Laser Tracker Head, which is a pivotal component on Laser Tracker.Established the system model, designed the photoelectric encoder and PSD interfacecircuit, designed PID controlled current-speed-position loop servo control system,and verified tracking performance of the system. Tentative showed that once themeasuring distance reduced progressively, the system dynamic performance becameworse in regulating of position loop controller designed at remote point. It indicatedthat the controller can not guarantee the controlled system maintaining excellentresponsing performance in a whole measuring range. Deducing proved that thesystem response characteristics is associated with measured length L. Therefore,make a further reaserch on intelligent control law applied in this system. In view offuzzy control algorithm has the ability of universal approximating characteristics,being not sensitive to controlled object parameters changing or non-linear factors. So,the reaserch concentrated on the combined algorithm of fuzzy logic and PIDapplicated in the system. After designed fuzzy logic control law, respectively madefuzzy PID switch control, fuzzy PID soft handover and fuzzy self-tuning PID parameters control. Validation showed that by using the latter two control strategies,the servo system responded quickly without overshoot and also can maitain therequired accuracy in the entire measuring range.Additionally, established the mathematical model of horizontal and verticalshaft vibration on Laser Tracker Head. Analyzed the influence of shaft vibration totracking accuracy and distance measuring accuracy. It demonstrated that slightvibration of high-precision shaft can hardly influence the tracking accuracy, eitherthe interferometric measuring. The impact on distance measuring accuracy wasmuch smaller, which can achieve nanometer level.