激光跟踪测量系统跟踪转镜的误差分析

激光跟踪测量系统是目前最新型的便携式空间大尺寸坐标测量系统，可对空间运动目标进行跟踪并实时测量其三维空间坐标，具有精度高、范围大、实时快速等特点。然而，激光跟踪测量系统中跟踪转镜的几何误差严重影响了其测量精度；所以激光跟踪测量系统在使用前必须对其进行建模和误差分析。在全面研究了激光跟踪测量系统结构和工作原理的基础上，建立了系统运动学模型和跟踪转镜中心偏移数学模型。详细分析了系统测量中基点位置变动误差、转镜跟踪目标反射器跟踪误差和转镜反射面与激光束不垂直误差等。结果表明跟踪转镜中心偏移、回转轴不对称、基点位置变动、光束反射点与基点不重合是导致测量误差的主要原因。因此，在跟踪转镜结构设计中，为保证激光束反射点与基点位置重合及转镜旋转跟踪目标反射器时基点空间位置保持不变，应尽量减少跟踪转镜旋转点与镜面之间的距离。

Error analysis of tracking mirror for laser tracker system

Laser tracker system (LTS) is one of the latest portable three dimensional large size coordinate measuring machines (CMMs). It can measure moving object coordinates with the advantages of broad range, high speed and high accuracy. However, its measuring accuracy is highly dominated by the geometric errors of the tracking mirror mechanism. Proper modeling and error analysis of LTS is essential prior to use it for metrology. The kinematics model and tracking mirror center offset model of LTS have been developed, based on the research on the structure and working principle of LTS, These models can describe not only the motion but also the geometric variations of LTS. The error of LTS base point position, tracking mirror tracking target retro-reflector and tracking mirror reflective surface out of vertical to laser beam is deeply analyzed. Theoretical analyses have demonstrated that the gimbals axis misalignment, tracking mirror center offset, base point position variation and laser beam reflected point non-coincidence with base point are the key contributors to measuring errors of LTS. In order to ensure the laser beam reflected point position coinciding with base point and the position unchanged in the course of LTS tracking the target retro-reflector, the distance between the tracking mirror surface and rotation point should be minimized in the structure design of tracking mirror.