Flexible method for accurate calibration of large-scale vision metrology system based on virtual 3-D targets and laser tracker

Abstract

For the purpose of obtaining high-precision in stereo vision calibration, a large-size precise calibration target, which can cover more than half of the field of view is vital. However, large-scale calibration targets are very difficult to fabricate. Based on the idea of error tracing, a high-precision calibration method for vision system with large field of view by constructing a virtual 3-D calibration target with a laser tracker was proposed in this article. A virtual 3-D calibration target that covers the whole measurement space can be established flexibly and the measurement precision of the vision system can be traceable to the laser tracker. First, virtual 3-D targets by calculating rigid body transformation with unit quaternion method were constructed. Then, the high-order distortion camera model was taken into consideration. Besides, the calibration parameters were solved with Levenberg–Marquardt optimization algorithm. In the experiment, a binocular stereo vision system with the field of view of 4 × 3 × 2 m3 was built for verifying the validity and precision of the proposed calibration method. It is measured that the accuracy with the proposed method can be greatly improved comparing with traditional plane calibration method. The method can be widely used in industrial applications, such as in the field of calibrating large-scale vision-based coordinate metrology, and six-degrees of freedom pose tracking system for dimensional measurement of workpiece, as well as robotics geometrical accuracy detection and compensation.

Design and Simulation Analysis of Trajectory Planning Algorithm for 6-DoF Manipulator Based on Deep Learning

“…Maybe the tracking effect of the first iteration is not very good. However, as the number of iterations increases, it is able to achieve full tracking effect, requiring less prior knowledge [12,13]. (4) Fuzzy control: using the combination of expert experience and control methods, it can be combined with other control methods and does not require an accurate mathematical model of the robotic arm system.…”

Calibration method for binocular vision system with large field of view based on small target image splicing

“…The virtual 3D targets built by numerous single points are also used for calibration. But the location information of points needs to be provided by additional equipment such as unmanned aerial vehicles [15,16] and laser trackers [17], increasing the cost and complexity of calibration. Compared with using 1D and 3D targets, the calibration methods using 2D targets are widely used and have better balanced performance in terms of efficiency, flexibility, and cost.…”