An on-line and flexible visual inspection system for car body-in-white (BIW) based on universal robot and two practical global calibration methods were described. A laser tracker and a measuring arm were used in complexity field environment. The method based on measuring posture realized the coordinate transformation between the sensors coordinates to the system reference coordinate by combining the sensors coordinates and the target coordinates through mechanical constraint. The method based on robot kinematics realized global calibration at arbitrary posture in the presence of robot forward kinematics model

base coordinate frame and hand-eye calibration which was independent of kinematics accuracy. Experimental results show that the standard deviations of repeatability for the measurement equipments and the system are 0.07mm and 0.13mm respectively

which indicates that both of the methods can meet the requirement of monitoring the manufacture dimension changes of BIW. At the same time

the coordinate measuring error of the system are ±0.2mm and ±0.8mm for the two methods respectively.