Research on the global calibration of the multi-vision line structured light measurement system based on auxiliary camera

Abstract

<p indent="0mm">To solve the problem of the absence of a common field of view between the cameras in the existing multi-vision line structured light measurement system, which leads to high requirements for calibration tools and complicated global-calibration process, a global-calibration method for the multi-vision line structured light measurement system based on an auxiliary camera is introduced to achieve a large-field-of-view measurement. First, an auxiliary camera is used as an intermediary to acquire an approximately one-half overlapped field of view with the line structured light sensor, which can constitute a binocular subsystem. Then, the spatial geometric relationship between the auxiliary camera and two adjacent line structured light sensors is established based on the different pose images of the calibration plate. Second, the position relationship between the two adjacent line structured light sensors without a common field of view is solved using coordinate transformation. Finally, the transformation matrix from a local to a global coordinate system is solved one at a time to complete the global calibration process. The requirement in terms of calibration tools of the proposed calibration method is low. Further, it does require the use of high-precision measuring equipment and complex targets but only requires a simple chessboard target to complete the global calibration of a multi-vision line structured light measurement system. Meanwhile, the calibration process can achieve high calibration accuracy. Meanwhile, the measurement experiment demonstrates that the global calibration error of this method is <sc>0.067 mm,</sc> which effectively improves the measurement accuracy and can guarantee the required accuracy for the integration of “measurement and machining” of large components using robots.