Automatic Calibration of Hand-Eye-Workspace and Camera Using Hand-Mounted Line Laser

Abstract

This paper develops a novel calibration method for simultaneously calibrating the intrinsic parameters of a camera and the hand-eye-workspace relationships of an eye-to-hand system using a line laser module. Errors in the parameters of a hand-eye coordination system lead to errors in the position targeting in the control of robots. To solve these problems, the proposed method utilizes a line laser module that is mounted on the hand to project laser beams onto the working plane. As well as calibrating the system parameters, the proposed method is effective when the eye cannot see the hand and eliminates the need for a precise calibration pattern or object. The collected laser stripes in the images must satisfy nonlinear constraints at each hand pose. A closed-form solution is derived by decoupling nonlinear relationships based on the homogeneous transform and parallel plane/line constraints. A nonlinear optimization, which considers all parameters simultaneously without error propagation problem, is to refine the closed-form solution. This two-stage process can be executed automatically without manual intervention. The computer simulation and experiment verify the effectiveness of the proposed method and reveal that using a line laser is more accurate than using a single-point laser.