Modeling and Self-calibration of Laser Tracker System Using Planar Constraints

A kinematics model that describes not only the motion but also the geometric variations of LTS is developed. Through error analysis of the proposed model, it is claimed that gimbals axis misalignments and tracking mirror center offset are the key contributor to measuring errors of LTS. A self-calibration method is presented to calibrate LTS with planar constraints. Various calibration strategies utilizing plane constraints are proposed for different situations. For each calibration strategy, issues about the error parameter estimation of LTS are exploded to find out in which conditions these parameters can be uniquely estimated. These conditions reveal the applicability of the planar constraints to LTS self-calibration. Intensive experimental studies are conducted to check the validity of the theoretical results. The results show that the measuring accuracy of LTS has been increased by 5 times after using the proposed technique for calibration.