In this article, we present a method to position the tool in a micromachine system based on\na camera-LCD screen positioning system that also provides information about angular deviations\nof the tool axis during its running. Both position and angular deviations are obtained by reducing\na matrix of LEDs in the image to a single rectangle in the conical perspective that is treated by a\nphotogrammetry method. This method computes the coordinates and orientation of the camera with\nrespect to the fixed screen coordinate system. The used image consists of 5 Ã? 5 lit LEDs, which are\nanalyzed by the algorithm to determine a rectangle with known dimensions. The coordinates of the\nvertices of the rectangle in space are obtained by an inverse perspective computation from the image.\nThe method presents a good approximation of the central point of the rectangle and provides the\ninclination of the workpiece with respect to the LCD screen reference system of coordinates. A test\nof the method is designed with the assistance of a Coordinate Measurement Machine (CMM) to\ncheck the accuracy of the positioning method. The performed test delivers a good accuracy in the\nposition measurement of the designed method. A high dispersion in the angular deviation is detected,\nalthough the orientation of the inclination is appropriate in almost every case. This is due to the small\nvalues of the angles that makes the trigonometric function approximations very erratic. This method\nis a good starting point for the compensation of angular deviation in vision based micromachine\ntools, which is the principal source of errors in these operations and represents the main volume in\nthe cost of machine elementsâ?? parts.
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