Method and apparatus for calibrating a non-contact gauging sensor with respect to an external coordinate system

A sensor calibration system for calibrating a non-contact sensor with respect to an external reference frame, the non-contact sensor of the type having a sensing zone associated with a sensor reference frame comprising:

• a reference indicia disposed in fixed relation to said external reference frame;
• at least two photogrammetric cameras having a calibration field of observation associated with a photogrammetric reference frame, said at least two photogrammetric cameras being positionable at two or more vantage points such that said reference indicia is within the calibration field of observation;
• a reference target for placement within the observation field of said at least two photogrammetric cameras and within the sensing zone of said non-contact sensor;
• a coordinate transformation system being adapted for coupling to said at least two photogrammetric cameras for collecting data from said reference indicia and for establishing a first relationship between the photogrammetric reference frame and the external reference frame;
• said coordinate transformation system further being adapted for coupling to said at least two photogrammetric cameras and to said non-contact sensor for collecting data from the reference target and for establishing a second relationship between the photogrammetric reference frame and the sensor reference frame;
• and
• said coordinate transformation system determining a third relationship between the external reference frame and the non-contact sensor reference frame, and calibrating said non-contact sensor with respect to said external reference frame based upon said first. second, and third relationships.

A method for calibrating a non-contact sensor with respect to an external reference frame using a photogrammetric measurement system, the photogrammetric measurement system having a fixed position with respect to the external reference frame according to a first relationship, comprising the steps of:

• providing a reference target for placement within the observation field of said photogrammetric measurement system and within a sensing zone of said non-contact sensor, where said reference target is further defined as a spherical target affixed to a tetrahedron framework;
• determining a second relationship between said reference target and said external reference frame through use of the photogrammetric measurement system and said reference target, said second relationship defining the position of said reference target with respect to the external reference frame;
• determining a third relationship between said reference target and said non-contact sensor through use of said non-contact sensor and said reference target, said third relationship defining the position of said non-contact sensor with respect to the position of said reference target;
• and
• calibrating said non-contact sensor with respect to said external reference frame based upon said first, second, and third relationships.