Hand-eye calibration of line structured-light sensor by scanning and reconstruction of a free-placed standard cylindrical target

摘要

• A cylinder instead of sphere is used for calibration, which is easy to manufacture and can cover a larger robot workspace . • An unconstrained dimensionality reduction method is proposed to accurately fit the incomplete conic profiles as ellipses. • The calibration error of hand eye parameters is reduced by about 50% compared to feature points col-linearity based method. This paper proposed a hand-eye calibration method for a line structured-light (LSL) scanner mounted on industrial robot. Unlike widely used spherical targets, the target used in our work is a cylinder, which is inexpensive and easy to be manufactured in larger size to cover a wider calibration space. In order to address the profile self-occlusion and drastically shape changing of conic section during calibration, an unconstrained dimensionality reduction method is proposed to fit the scanned profiles. Based on fitted ellipse centers under various robot poses, the hand-eye calibration model is developed based on the difference between cylinder radius and the distance from the profile point to the cylinder axis. Simulation and actual experiments have shown that the proposed ellipse fitting method is more accurate and robust, and the calibration method achieves higher reconstruction accuracy under the same robot positioning error, need less robot operations to obtain more accurate hand-eye parameters.