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Browse Prior Art Database

CALIBRATION METHODOLOGY FOR LATERAL RESOLUTION OF STRIPE LASERS

IP.com Disclosure Number: IPCOM000026752D
Original Publication Date: 1993-Jun-30
Included in the Prior Art Database: 2004-Apr-06
Document File: 2 page(s) / 111K

Publishing Venue

Xerox Disclosure Journal

Abstract

Robotic vision systems using laser based sensors to measure height profiles on target objects house a laser light source and a detector array together in one unit. Such two dimensional laser based reflective range sensor systems project a stripe of laser light onto an object which is then reflected onto the detector array. Imaged laser light on the detector array renders a profile which depicts the relative height (or range) of the object for each lateral position (or resolution) along the laser stripe. Often the lateral resolution of a detector array is not precisely known and varies across the range of the sensor. The accuracy of the lateral position along a detector array is important to the precision of applications that require transformations or rotations of sensor data in order to obtain measurements perpendicular to the plane of an object.

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XEROX DISCLOSURE JOURNAL

CALIBRATION METHODOLOGY FOR LATERAL RESOLUTION OF STRIPE LASERS
Mark T. Strang

Proposed Classification
U.S. C1.901/046 Int. C1. B25j 19/00

Robotic vision systems using laser based sensors to measure height profiles on target objects house a laser light source and a detector array together in one unit. Such two dimensional laser based reflective range sensor systems project a stripe of laser light onto an object which is then reflected onto the detector array. Imaged laser light on the detector array renders a profile which depicts the relative height (or range) of the object for each lateral position (or resolution) along the laser stripe. Often the lateral resolution of a detector array is not precisely known and varies across the range of the sensor. The accuracy of the lateral position along a detector array is important to the precision of applications that require transformations or rotations of sensor data in order to obtain measurements perpendicular to the plane of an object.

A method for calibrating a stripe laser sensor of a robotic vision system using a linear function to model inaccuracies or variations in the lateral resolution across the detector array of the laser sensor is disclosed. The following linear function is used to model resolution variations:

L = aR + b, 111

where a and b are coefficients of linear function [l] for a tilted laser sensor. In determining the coefficients a and b for the tilted laser sensor, a constant lateral resolution L, (given by laser specifications) is assumed while measuring the angle theta with respect to the center imaging pixel of the sensor for each range along a calibrated flat surface. The lateral resolution L for each range position along the flat calibrated surface is therefore given by:

L = Lc TAN (thet...