A global calibration method for multi-sensor vision system

Abstract

A global calibration method of multi-sensor vision system based on flexible 3d target is proposed to solve the calibration problem of multi-sensor vision system with a large inspection range. The flexible 3d target is a form of target consisted of several planar targets, called sub-targets, which are placed flexibly according to the sensors' positions. The coordinate frame of one of the vision sensor is selected as the global coordinate frame. Using the invariance of the relative positions between sub-targets in the flexible 3d target, the closed solution of the transformation from the local coordinate frame of each sensor to the global coordinate frame can be computed. The result is refined by the nonlinear optimization method, and maximum likelihood estimation of the translation matrixes can be achieved. Experimental result demonstrates high accuracy of proposed calibration method. The proposed method greatly simplifies the process and reduces the cost of global calibration, for it does not need high-accuracy 3d measuring equipment or special 3d target as most the traditional global calibration methods do, and only needs to combine several planar targets to carry out the global calibration. It is applicable for the global calibration of multi-sensor vision system at working location.