Inductive position sensor signal gain control for coordinate measuring machine probe

Patent metadata

Field	Value
Publication number	US-11644299-B2
Application number	US-202017139592-A
Country	US
Kind code	B2
Filing date	Dec 31, 2020
Priority date	Dec 31, 2020
Publication date	May 9, 2023
Grant date	May 9, 2023

Abstract

A scanning probe for a coordinate measuring machine with inductive position sensor signal gain control is provided. The scanning probe includes a stylus position detection portion with field generating and sensing coils, and for which corresponding output signals are indicative of a position of the probe tip of the stylus. Signal processing and control circuitry is configured to implement different operating regions, such as a central high gain operating region which corresponds to a central probe tip position range, as well as other lower gain operating regions, and for which transition operations may be performed for adjusting the gain. In various implementations, transition operations for adjusting a gain may include operations such as: adjusting power to a field generating coil configuration; adjusting a gain of a front end amplifier; altering characteristics of sensing coils; adjusting an input range of an analog to digital converter, etc.

First claim

The invention claimed is:

1. A scanning probe for a coordinate measuring machine, the scanning probe comprising:
a stylus suspension portion that is coupled to a frame of the scanning probe, comprising:
a stylus coupling portion that is configured to be rigidly coupled to a stylus with a probe tip; and
a stylus motion mechanism that is configured to enable axial motion of the stylus coupling portion along an axial direction, and rotary motion of the stylus coupling portion about a rotation center;

a stylus position detection portion arranged along a central axis that is parallel to the axial direction and nominally aligned with the rotation center, comprising:
a field generating coil configuration comprising at least one field generating coil;
a top axial sensing coil configuration comprising at least one top axial sensing coil;
a bottom axial sensing coil configuration comprising at least one bottom axial sensing coil; and
N top rotary sensing coils and N bottom rotary sensing coils, where N is an integer greater than 3;

a disruptor configuration comprising a conductive disruptor element that provides a disruptor area, wherein the disruptor element is located along the central axis in a disruptor motion volume and the disruptor element is coupled to the stylus suspension portion by a coupling configuration, wherein the disruptor element moves in the disruptor motion volume relative to an undeflected position in response to a deflection of the stylus suspension portion, the disruptor element moving over operating motion ranges +/Rz−along the axial direction in response to the axial motion, and over respective operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions that are orthogonal to the axial direction in response to the rotary motion, the field generating coil configuration generating a changing magnetic flux generally along the axial direction in the disruptor motion volume in response to a coil drive signal; and
signal processing and control circuitry that is operably connected to the coils of the stylus position detection portion to provide the coil drive signal and configured to input signals comprising respective signal components provided by the respective rotary and axial sensing coils, and output signals indicative of an axial position and a rotary position of the probe tip, and for which an output signal change correspondingly indicates a change in at least one of an axial or rotary position of the probe tip, wherein the signal processing and control circuitry is configured to operate over a plurality of operating regions, the plurality of operating regions comprising:
a central high gain operating region which corresponds to a central high gain probe tip position range; and
a first pair of lower gain operating regions which corresponds to respective lower gain probe tip position ranges, wherein the central high gain operating region is between the operating regions of the first pair of lower gain operating regions, and wherein the gain of each operating region corresponds to a ratio of a magnitude of output signal change to probe tip position change for the respective operating region, for which the first pair of lower gain operating regions has lower respective gains than the gain of the central high gain operating region; and

wherein the signal processing and control circuitry is configured to perform a transition operation in response to a determination that the probe tip has moved from a position in the central high gain probe tip position range of the central high gain operating region to a position in a lower gain probe tip position range of a respective operating region of the first pair of lower gain operating regions, the transition operation resulting in the signal processing and control circuitry transitioning from operating in the central high gain operating region with the high gain to operating in the respective operating region with the lower gain.

2. The scanning probe of claim 1 , wherein:
the plurality of operating regions further comprise a second pair of lower gain operating regions which corresponds to respective lower gain probe tip position ranges, wherein the operating regions of the first pair of lower gain operating regions are between the operating regions of the second pair of lower gain operating regions, and the second pair of lower gain operating regions have lower respective gains than the gains of the first pair of lower gain operating regions; and
the signal processing and control circuitry is further configured to perform a transition operation in response to a determination that the probe tip has moved to a position in a lower gain probe tip position range of a respective operating region of the second pair of lower gain operating regions, the transition operation resulting in the signal processing and control circuitry transitioning to operating in the respective operating region of the second pair of lower gain operating regions with the lower gain.

3. The scanning probe of claim 2 , wherein the plurality of operating regions further comprise a pair of saturation operating regions which corresponds to respective saturation probe tip position ranges, wherein the second pair of lower gain operating regions is between the pair of saturation operating regions, and the pair of saturation operating regions corresponds to a saturation state in which nominally no output signal change results from probe tip position change and for which there is nominally no corresponding gain.

4. The scanning probe of claim 3 , wherein the signal processing and control circuitry comprises one or more amplifiers configured to amplify signals from coils of the stylus position detection portion, and the saturation state corresponds to a saturation of at least one of the one or more amplifiers.

5. The scanning probe of claim 1 , wherein:
the central high gain operating region which corresponds to the central high gain probe tip position range also corresponds to a central high gain element position range, which corresponds to an angular position range of the disruptor element, and is configured to be utilized in combination with a stylus of a first stylus length; and
for a stylus of a second stylus length, the central high gain element position range is configured to be modified to be at least one of:
shorter, as configured to be utilized with a second stylus length that is longer than the first stylus length; or
longer, as configured to be utilized with a second stylus length that is shorter than the first stylus length.

6. The scanning probe of claim 1 , wherein the signal processing and control circuitry is further configured to perform a zeroing operation to adjust a zero position of the central high gain operating region.

7. The scanning probe of claim 1 , wherein the signal processing and control circuitry is further configured to have at least a position range of the central high gain operating region increased to at least one of:
encompass manufacturing tolerances during factory calibration; or
encompass variations that may occur due to an orientation of the scanning probe during measurement operations.

8. The scanning probe of claim 1 , wherein the transition operation comprises reducing a power of the field generating coil configuration so as to reduce the ratio of the magnitude of output signal change to probe tip position change so as to correspond to the lower gain.

9. The scanning probe of claim 8 , wherein reducing the power of the field generating coil comprises reducing the coil drive signal.

10. The scanning probe of claim 1 , wherein the signal processing and control circuitry comprises one or more variable gain amplifiers configured to a

Assignees

• Mitutoyo Corp

Inventors

• Hamner Christopher Richard
• Harsila Scott Allen
• Hemmings Scott Ellis
• Patzwald Andrew Michael

Classifications

• G01B7/001 Primary

  Constructional details of gauge heads (G01B7/012 takes precedence) · CPC title

• G01B7/008

  using coordinate measuring machines · CPC title

• G01B7/012 Primary

  Contact-making feeler heads therefor · CPC title

• G01D5/2053

  by a movable non-ferromagnetic conductive element · CPC title