Method for contactless profiling normal to a surface

A method for profiling a model surface by tracing the surface with a distance measuring probe over predetermined sampling times T.sub.S, the distance measuring probe capable of measuring distances without contacting the surface, said method comprising the steps of:

• (a) providing a first, a second and a third contactless distance measuring device for simultaneous distance measurement of at least three points on the model surface;
• (b) juxtaposing the second contactless distance measuring device a predetermined distance from the first contactless distance measuring device in a probe feed direction;
• (c) juxtaposing the third contactless distance measuring device a predetermined distance from the first contactless distance measuring device in a direction perpendicular to the probe feed direction;
• (d) measuring, every of the predetermined sampling times T.sub.S, incremental distances to two points in the probe feed direction and determining an inclination angle increment .sub..DELTA. .theta..sub.x in the probe feed direction in accordance with said measured incremental distances to the two points in the probe feed direction;
• (e) measuring, every of the predetermined sampling times T.sub.S, incremental distances to two points in a direction perpendicular to the probe feed direction and determining an inclination angle increment .sub..DELTA. .theta..sub.y in a direction perpendicular to the probe feed direction in accordance with said measured incremental distances to two points in a direction perpendicular to the probe feed direction;
• and
• (f) determining, every of the predetermined sampling times T.sub.S, incremental quantities required to align a measurement line of the first contactless distance measuring device along a line normal to the model surface in accordance with both the inclination angle increment .sub..DELTA. .theta..sub.x in the probe feed direction and the inclination angle increment .sub..DELTA. .theta..sub.y in the direction perpendicular to the probe feed direction.

An apparatus for profiling a surface of a model by tracing the model surface, said apparatus comprising:

• a distance measuring probe capable of measuring distances, said distance measuring probe including:
• a first distance measuring device capable of measuring a distance along a first measurement line from said first distance measurement device to a first point on the model surface;
• a second distance measuring device arranged a first predetermined distance from the first distance measuring device in a probe feed direction;
• and
• a third distance measuring device arranged a second predetermined distance from the first distance measuring device in a direction perpendicular to the probe feed direction;
• a first servo unit to move the distance measuring probe relative to the model along first, second and third axes of a three-dimensional coordinate system;
• a second servo unit to move the distance measuring probe about fourth and fifth axes of probe rotation;
• and
• a controller to compute an inclination angle increment .sub..DELTA. .theta..sub.x in a probe feed direction using first and second distances measured between said first and second distance measuring devices and the surface, to compute an inclination a angle increment .sub..DELTA. .theta..sub.y in a direction perpendicular to the probe feed direction using first and third distances measured between said first and third distance measuring devices and the surface, to compute incremental quantities along the first, second and third axes of the three-dimensional coordinate system and the fourth and fifth axes of the probe rotation required to align the first measurement line of said first distance measuring device along a line normal to the surface at the first point, and to control simultaneous five-axis control of said first and second servo unit using the incremental quantities along the first, second and third axes and using the incremental quantities about the fourth and fifth axes.

A method for profiling normal to a model surface by tracing the model surface over predetermined sampling times T.sub.S, said method comprising the steps of:

• (a) measuring, every of the predetermined sampling times, first, second and third distances along first, second and third measurement lines, respectively, between a distance measuring probe and at least three points on the model surface;
• (b) computing a first inclination angle increment in a first direction using the first and second distances;
• (c) computing a second inclination angle increment in a direction perpendicular to the first direction using the first and third distances;
• (d) determining, every of the predetermined sampling times, total incremental quantities along first, second and third axes of a three-dimensional coordinate system and fourth and fifth axes of probe rotation required to align the first measurement line of the distance measuring probe along a line normal to the model surface;
• and
• (e) performing simultaneous five-axis control of movement of the distance measuring probe relative to the model, along the first, second and third axes of the three-dimensional coordinate system and about the fourth and fifth axes of probe rotation in accordance with the total incremental quantities.