Center extraction deviation correction of SMD-LEDs in the target-based vision measurement system

Surface mounted device-type light emitting diodes (SMD-LEDs) are commonly utilized as feature points in target-based vision measurement systems (T-VMSs) due to their high luminance. The non-uniform characteristics of said luminance introduce deviation errors in image center extraction, however, which degrades the positioning precision of the T-VMS. In this study, we first analyzed two factors responsible for deviation errors: The deflection angle between the LED’s normal direction and the observation direction, and the distance between the LED and the observer. We then established a correction method based on a lookup table to compensate for deviation errors according to these two factors. We also analyzed the correction direction of the deviation error. We applied the proposed method in an actual T-VMS to confirm its feasibility and effectiveness, and found that it does indeed correct deviation errors effectively.