Flexible Calibration Method and Application of Passenger Car HUD Detection Based on Collaborative Robot

Abstract

At present, the HUD calibration of the whole vehicle enterprise adopts the traditional physical calibration frame to calibrate the camera, and the scheme has low flexibility and large space occupation and is unsuitable for the mixed production of different types of vehicles. A flexible calibration approach is presented based on collaborative robots for HUD inspection of passenger cars. They are considering that the virtual image distance of the general HUD (Head-Up Display) is 2-3m. A 2.3-meter hand-eye calibration method is studied. A monocular camera is installed on the cooperative robot. Considering the influence of ambient light on long-distance hand-eye calibration, a customized alumina calibration plate is used and illuminated at an appropriate angle. Camera calibration is performed using an area_scan_polynomial model, and the camera's internal parameters are solved. The average error of camera internal parameters is about 0.15, which shows high calibration accuracy. The hand-eye calibration results show that the Translation part's maximum error is about 1mm, the maximum error of the Rotational position is about 0.1 degree, and the camera calibration error is within 0.08 pixels. For repeatability, the median of Translation RMS was 0.5 with an interquartile range of 0.171, and the median of Translation Maximum was 0.972 with an interquartile range of 0.216. The median of Rotation RMS was 0.0325 with an interquartile range of 0.0125. The median of the Rotation Maximum was 0.059, with an interquartile range of 0.016. The data of Translation is relatively scattered, with an extensive range of change, but still maintains a certain repeatability. The Rotation data is relatively stable, with a small degree of change and good repeatability, further meeting the use requirements in the final inspection HUD scene of the whole vehicle.INDEX TERMS eye-in-hand, hand-eye calibration, HUD, camera calibration, cooperative robot, repeatability .