Coordinate correction method and coordinate measuring machine

Patent metadata

Field	Value
Publication number	US-10429167-B2
Application number	US-201715682904-A
Country	US
Kind code	B2
Filing date	Aug 22, 2017
Priority date	Aug 26, 2016
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

As a former correction step, a coordinate correction method includes: a step of setting a measuring probe in a drive mechanism; a step of restraining a measurement tip; a step of acquiring a moving amount and a probe output; and a step of generating a former correction matrix including linear correction elements and non-linear correction elements. As a latter correction step, the coordinate correction method includes: a step of setting a measuring probe in a drive mechanism; a step of restraining a measurement tip; a step of acquiring a moving amount and a probe output; a step of generating an intermediate correction matrix including linear correction elements for correcting the probe output; and a step of correcting the probe output with a latter correction matrix. Consequently, correction can be simplified while allowing for correction of a non-linear error of the probe output supplied from the measuring probe.

First claim

What is claimed is:

1. A coordinate correction method of a first coordinate measuring machine, the first coordinate measuring machine including: a first measuring probe having a first stylus with a first measurement tip to be brought into contact with an object to be measured, and a probe body for movably supporting the first stylus and providing a first probe output according to a displacement of the first measurement tip; a first drive mechanism for moving the first measuring probe relative to the object to be measured; and a first processing device for computing shape coordinates of the object to be measured on a basis of the first probe output and a first moving amount of the first measuring probe by the first drive mechanism,
the coordinate correction method comprising,
a former correction process, including:
setting a second measuring probe in a second drive mechanism of a second coordinate measuring machine, the second coordinate measuring machine including the second drive mechanism for relatively moving the second measuring probe including the probe body for movably supporting a second stylus with a second measurement tip, and a second processing device for obtaining, on a basis of a second probe output according to a displacement of the second measurement tip and a second moving amount of the second measuring probe by the second drive mechanism, a former correction matrix for correcting the second probe output with respect to the second moving amount;
restraining a translational displacement of the second measurement tip;
acquiring the second moving amount and the second probe output when the second measuring probe is moved by the second drive mechanism; and
generating the former correction matrix including second linear correction elements and second non-linear correction elements for respectively correcting linear coordinate components and non-linear coordinate components of the second probe output with the second moving amount and the second probe output acquired in each of measurement points in a quantity larger than or equal to a sum of a number of the second linear correction elements and a number of the second non-linear correction elements, and

a latter correction process, including:
setting the first measuring probe in the first drive mechanism;
restraining a translational displacement of the first measurement tip;
acquiring the first moving amount and the first probe output when the first measuring probe is moved by the first drive mechanism;
generating an intermediate correction matrix including first linear correction elements for correcting linear coordinate components of the first probe output with the first moving amount and the first probe output; and
correcting the first probe output with a latter correction matrix generated on a basis of the intermediate correction matrix and the former correction matrix.

2. The coordinate correction method according to claim 1 , wherein
the former correction process further includes generating a former intermediate correction matrix by multiplying the former correction matrix by an inverse matrix of a former linear correction matrix including only the second linear correction elements, and
the latter correction process further includes generating the latter correction matrix with the former intermediate correction matrix.

3. The coordinate correction method according to claim 2 , wherein the correcting the first probe output with the latter correction matrix generated on the basis of the intermediate correction matrix and the former correction matrix includes generating the latter correction matrix by multiplying the former intermediate correction matrix by the intermediate correction matrix.

4. The coordinate correction method according to claim 2 , wherein
the former correction process further includes:
changing forms of the second measuring probe corresponding to a number of different forms of the second measuring probe and repeating from the setting the second measuring probe in the second drive mechanism to the generating the former correction matrix; and
generating a correlation between the second linear correction elements or the forms of the second measuring probe and non-linear correction elements of the former intermediate correction matrix on a basis of the plurality of former correction matrixes, and

the correcting the first probe output with the latter correction matrix generated on a basis of the intermediate correction matrix and the former correction matrix includes:
obtaining the non-linear correction elements of the former intermediate correction matrix corresponding to the first linear correction elements, instead of the second linear correction elements, or corresponding to forms of the first measuring probe, instead of the forms of the second measuring probe, with the correlation; and
generating the latter correction matrix with the first linear correction elements and the non-linear correction elements of the former intermediate correction matrix.

5. The coordinate correction method according to claim 4 , wherein
the number of the different forms of the second measuring probe is based on a number of different forms of the second stylus, and
the forms of the first measuring probe are based on forms of the first stylus.

6. The coordinate correction method according to claim 5 , wherein
the restraining the translational displacement of the second measurement tip includes restraining the translational displacement of the second measurement tip at a reference position where a displacement of the second measurement tip is 0, and not-restraining rotational displacement of a center of the second measurement tip as a center of rotation, and
the acquiring the second moving amount and the second probe output when the second measuring probe is moved by the second drive mechanism, includes acquiring the second moving amount and the second probe output at the time of the movement of the second measuring probe from the reference position to each of the measurement points.

7. The coordinate correction method according to claim 6 , wherein
the restraining the translational displacement of the first measurement tip includes bringing the first measurement tip into contact with a calibration artifact, and
the acquiring the first moving amount and the first probe output when the first measuring probe is moved by the first drive mechanism include:
a pushing drive process of bringing, in a normal direction to a surface of the calibration artifact, the first measurement tip into contact with the surface at a single point, pushing the calibration artifact with the first measurement tip by a predetermined displacement amount, and then moving the first measurement tip in an opposite direction to separate the first measurement tip away from the surface; and
a scanning drive process of reciprocating the first measurement tip on the surface of the calibration artifact while pressing the calibration artifact with the first measurement tip by a constant deflection amount.

8. The coordinate correction method according to claim 7 , wherein
the normal direction to the surface of the calibration artifact corresponds to a total of five directions including: three directions perpendicular to one another; and two directions among the three directions adding a respective inversed direction, and
the pushing drive process is performed in each of the five directions.

9. The coordinate correction method according to claim 8 , wherein
the first measurement tip is pushed by a constant deflection amount on each of three planes perpendicular to one another in the scanning drive process.

10. A first coordinate measuring machine comprising:

Assignees

• Mitutoyo Corp

Inventors

• Nakagawa Hideyuki
• Ishikawa Nobuhiro

Classifications

• G01B5/012 Primary

  Contact-making feeler heads therefor · CPC title

• G01B5/008 Primary

  using coordinate measuring machines · CPC title

• G01B21/047

  Accessories, e.g. for positioning, for tool-setting, for measuring probes · CPC title

• G01B21/045

  Correction of measurements (G01B9/02055 takes precedence) · CPC title

• G01B21/042 Primary

  Calibration or calibration artifacts (G01B3/30, G01B9/02072 take precedence) · CPC title