A TRINOCULAR VISION SYSTEM FOR CLOSE-RANGE POSITION SENSING

A machine vision system for obtaining three-dimensional information from a single camera is presented, Stereo and orthogonal views of the test object are imaged onto a CCD (charge coupled device) camera by using a tri-split lens in conjunction with a mirror arrangement. The calibration procedure involves a direct linear transformation resulting in an overdetermined set of equations that are solved to obtain the three-dimensional coordinate position. The position information obtained from the stereo views is used to locate the object in the orthogonal view, thus improving the accuracy of the position sensor. The relative position of a cylinder-head from a reference point, which is of importance in assembly line applications, was measured using the vision system within an accuracy of 0.3% of full scale value.