Research On Thermal Deformation Error Compensation In Laser Tracker Orientation

Laser Tracker is a digital measuring equipment with high precision and efficiency; It has been widely used in the field of aircraft digital assembly. During aircraft digital assembly process, Enhanced Reference System (ERS) is frequently used to orient the equipment using registration algorithms, so that the measure result could be transformed from measurement coordination system to assembly coordinate system.This paper relies on a key research project of model digital assembly; expand research work on improving Laser Tracker orientation measurement accuracy. Then the paper focuses on ERS-points thermal deformation compensation technology in Laser Tracker orientation, and proposes two compensation methods.Chapter Ⅰ describes the aircraft digital assembly measurement technology applications in domestic and international; then explains the research background of Laser Tracker orientation measurement and significance of improving orientation precision; at last, the research content and structural framework are shown.Chapter Ⅱ introduces Leica Laser Tracker system composition, and elaborates the instrument orientation principle and SVD algorithm for coordinate transformation. Then classifies on-site errors into several types, and gives the evaluation of orientation precision and proposes countermeasures to reduce or eliminate some errors.Chapter Ⅲ bases on the object thermal deformation theory, and establishes a compensation model of ERS-points three-dimensional anisotropic thermal deformation to reduce systematic errors due to thermal deformation. Then introduces 3σ criterion to screen ERS-points and eliminates the influence of outliers.Chapter Ⅳ presents a method of unit thermal deformation temperature compensation coefficient matrix λ to reduce orientation thermal error. Finite element simulation and experimental data analysis indicate that the ERS-points thermal deformation on complex tooling changes linearly in a small range of temperature change, and proposed unit thermal deformation temperature coefficient matrix λ. Regression analysis through simulation and experiments shows the consistency, which expresses the coefficient matrix λ obtained from simulation is correct.Chapter V five orientation methods are mentioned in this paper, and the orientation errors and parameters are compared. The occasion and condition of the five methods use are described.