Method and apparatus to correct for gravitational sag in the articulated mounting of a probe in a coordinate-measuring machine

US5138563A · kind A · utility

Assignee

• Carl Zeiss Stiftung · DE

Inventors

• Rasmus Debitsch · Stuttgart, DE
• Eckhard Enderle · Aalen, DE
• Helmut Muller · Bensberg, DE

Key dates

• Filing date: Jan 16, 1991
• Grant date: Aug 11, 1992
• Expiry date: Jan 16, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B21/045
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The invention contemplates a technique to correct for measurement error which is attributable to gravitational sag of a probe head (6) mounted to a multiple-axis articulating head (2). To this end, a variable (b) is determined which describes the stiffness of the articulating head (2) and/or of a probe extension (5) mounted thereto, said variable being characteristic for the probe configuration in question and being entered into the memory of the computer of the coordinate-measuring machine. The sag B (.alpha., .beta.) which has differing values that depend on actual angular positions (.alpha., .beta.) is then calculated from these angular positions for each of the angular positions, and the calculated sag value is appropriately taken into account in computer-reporting of coordinate-measurement values made by the machine. Calibration of the articulating head in each of the various different angular positions is therefore unnecessary.