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Emerald Group Publishing Limited
Copyright © 2001, MCB UP Limited
Calibrating a noncontact sensor
Calibrating a noncontact sensorKeywords: Calibration, Sensors
Applicant: Perceptron Inc. (US)Patent number: US6128585Publication date: 3 October 2000Title: Method and apparatus for calibrating a noncontact gauging sensor with respect to an external coordinate system
The present invention provides a calibration system that can be used in a matter of minutes, instead of hours, and without the need for precisely manufactured master parts or theodolite equipment. One of the major advantages of the invention is that it allows the calibration of sensors to be checked or realigned between line shifts, without requiring the line to be shut down for an extended period. The system employs reference indicia that are disposed in fixed relation to the external reference frame of the manufacturing or assembly zone or gauging station. These reference indicia may be simple light-emitting diodes that are disposed at predetermined fixed locations. A calibration sensor array is positioned at a vantage point, typically above the gauging station, so that the reference indicia are within the sensor array's field of view. If desired, the calibration sensor array can be permanently or semipermanently mounted at a suitable vantage point within the workpiece manufacturing or assembly station. The calibration system further employs a portable reference target that is placed within the observation field of the sensor array and also within the sensing zone of the feature sensor to be calibrated. The presently preferred portable reference target is a tetrahedron framework having light-emitting diodes at the vertices. The system further includes a coordinate translation system for coordinating the readings from the sensor array and from the feature sensor. Using the calibration system of the invention, it is easy to calibrate a feature sensor.