激光跟踪仪坐标测量精度分析

激光跟踪仪是目前精度最高的移动式坐标测量系统,其实际测量精度是否符合标称精度,直接决定了测量精度能否满足需求精度,因此对仪器坐标测量精度的分析显得十分重要。坐标转换模型是反应多站测量坐标精度的理论基础,不同模型在反应仪器精度的准确性、精确性、稳定性和计算速度等方面有较大差别。本文对常用的坐标转换模型进行了对比分析,得出结论是四元数模型具有算法严谨、抗奇异性、表达简洁、运算快速和易于实现等优点,适用于计算坐标转换精度。本文以Leica AT901_b激光跟踪仪为例,进行坐标测量精度分析。多次设站获取同一组目标点数据,每测站与目标点保持良好网形结构,数据处理时首先排除粗差并检验可靠性,然后采用四元数模型计算坐标转换参数,并通过最小二乘平差算法解算参数精度及坐标测量精度。另外,为了反应激光跟踪仪的坐标测量精度与目标点距离的关系,本文以Leica AT901_b为例进行实验,在测程内由远及近多次设站获取数据,计算坐标测量内符合精度并给出了目标点距离与坐标精度的关系曲线。

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 in- strument 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 ex- ample, to analyze the coordinate measurement accuracy. Multiple stations are taken to obtain data of the same set of tar- gets, 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 parame- ters 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 Lei- ca ATg01_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 be- tween the target distance and coordinate precision.