Analysis of Laser Tracker Coordinate Measurement Accuracy

Laser Tracker is the most accurate portable coordinate measuring system.The actual measurement accuracy meets the nominal accuracy directly determines the measurement accuracy can meet the demand for accuracy.Therefore,the analysis of the measurement accuracy of the instrument coordinate is very important.Coordinate transformation model is the theoretical basis of the coordinates accuracy of of the multi-station measurement,and there may be difference in instrument accuracy,stability and computational speed among different models.This paper gives comparative analysis of common coordinate transformation models,and gives the result that quaternion model is a strict anti-singularity,concise expression,fast computing and easy to implement algorithm.This paper takes the Leica AT901_b laser tracker as an example,to analyze the coordinate measurement accuracy.Multiple stations are taken to obtain data of the same set of targets,and maintain good net-shaped structure of each station and the target points.Firstly exclude gross errors in the data processing and test the reliability,then calculate coordinate conversion parameter by quaternion model,and solve parameters precision and coordinate measurement accuracy by least squares adjustment algorithm.In addition,in order to reflect the relationship between the accuracy of laser tracker coordinate measurement and target distance,the paper takes the Leica AT901_b laser tracker as an example for experiment.In instrument range many times measurents are taken to get data station from far and near,and calculates coordinate measuring accuracy and gives out the curve of the relathionship between the target distance and coordinate precision.