Analysis, characterization and accuracy improvement of optical coordinate measurement systems for car body assembly quality control

Abstract

Many car manufacturers are installing in-line car body measurement systems in order to achieve dimensional quality control of the whole production. The geometrical tolerances required by this product are narrowing increasingly; consequently, it is necessary to design these systems to calculate corrections and uncertainties as accurately as possible. This paper studies the error sources and analyzes their influence on measurement results by means of simulation and experimental tests during a nine-month study. The final goal of this work is to describe an optimization procedure for the accuracy improvement of the system. This is achieved mainly by applying a number of corrections designed to minimize the errors detected during the practical tests, and by means of algorithms to eliminate dispersions caused by a lack of stability in the positioning of the car body in the optical measurement system, or by temperature variations to reduce the final error.