Method for validating a workpiece measurement in a dimensional metrology hand tool

Patent metadata

Field	Value
Publication number	US-9377282-B2
Application number	US-201314017206-A
Country	US
Kind code	B2
Filing date	Sep 3, 2013
Priority date	Sep 3, 2013
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

A method for validating a workpiece measurement in a hand-held spatial dimension measurement metrology tool comprises vibrating a portion of the metrology hand tool using the vibration excitation element; sensing a vibration signature using the vibration sensor configuration; identifying a valid contact state between the metrology hand tool and the workpiece based on a vibration signature criterion; identifying a valid seating state based on a measurement stability criterion applied to a set of dimensional measurements of the metrology hand tool; and indicating that a dimensional measurement is valid for a dimensional measurement that is obtained when the valid contact state and the valid seating state occur simultaneously.

First claim

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for validating a workpiece measurement in a dimensional metrology hand tool, the
dimensional metrology hand tool comprising a first workpiece contact surface included on a first member and a second workpiece contact surface included on a second member that moves relative to the first member, a dimensional measurement sensor for measuring a separation between the first and second contact surfaces, and a signal processor, the method comprising:
vibrating a portion of the metrology hand tool using a vibration excitation element of the metrology hand tool;
sensing a vibration signature using a vibration sensor configuration of the metrology hand tool;
identifying a valid contact state between the metrology hand tool and the workpiece based on a vibration signature criterion applied to the vibration signature;
identifying a valid seating state of the workpiece as seated against the first and second contact surfaces based on a measurement stability criterion applied to a set of dimensional measurements of the metrology hand tool; and
indicating that a dimensional measurement is valid for a dimensional measurement that is obtained when the valid contact state and the valid seating state occur simultaneously.

2. The method of claim 1 , wherein the dimensional metrology hand tool further comprises a visible measurement validity indicator, and the method comprises activating a display of the visible measurement validity indicator corresponding to a dimensional measurement that is obtained when the valid contact state and the valid seating state occur simultaneously.

3. The method of claim 2 , wherein the method comprises operating the signal processor to perform the operations of identifying the valid contact state, identifying the valid seating state, and determining when the valid contact state and the valid seating state occur simultaneously, and to perform the operation of activating the display of the visible measurement validity indicator.

4. The method of claim 3 , wherein the method further comprises:
identifying an end of the valid seating state based on a measurement stability criterion applied to dimensional measurements of the metrology hand tool obtained after the operation of activating the display of the visible measurement validity indicator; and
continuing the display of the visible measurement validity indicator for dimensional measurements obtained after the operation of activating display of the visible measurement validity indicator until the end of the valid seating state is identified, and then ending the display of the visible measurement validity indicator.

5. The method of claim 4 , wherein the method further comprises:
repeating the vibrating operation and the sensing a vibration signature operation, and identifying an end of the valid contact state based on the vibration signature criterion applied to a vibration signature obtained after the operation of activating the display of the visible measurement validity indicator; and
continuing the display of the visible measurement validity indicator for dimensional measurements obtained after the operation of activating display of the visible measurement validity indicator until the end of the valid seating state is identified or the end of the valid contact state is identified, and then ending the display of the visible measurement validity indicator.

6. The method of claim 1 , wherein:
the vibration signature criterion corresponding to a valid contact state comprises at least one of:
(a) a frequency present in a vibration signature during contact between the metrology hand tool and the workpiece, but not present when there is not contact between the metrology hand tool and the workpiece;
(b) for at least one frequency in a vibration signature, the presence of a lower amplitude of a vibration signal that is present at a higher amplitude when there is not contact between the metrology hand tool and the workpiece;
(c) for at least one frequency in a vibration signature, the presence of a higher amplitude of a vibration signal that is present at a lower amplitude when there is not contact between the metrology hand tool and the workpiece; or
(d) for at least one frequency in a vibration signature, an indication of the presence of increased damping of a vibration signal that is present with less damping when there is not contact between the metrology hand tool and the workpiece, and
identifying a valid contact state comprises determining the presence of at least one of (a), (b), (c), or (d) in the vibration signature using at least one of the signal processor of the hand tool or an external signal processor.

7. The method of claim 6 , wherein identifying a valid contact state comprises determining the presence of at least one of (a) or (b).

8. The method of claim 7 , wherein the at least one sensor is mounted proximate to a compliant element configured such that it has a resonant frequency that is responsive to contact between the metrology hand tool and the workpiece.

9. The method of claim 6 , wherein identifying a valid contact state comprises determining the presence of (c).

10. The method of claim 9 , wherein the vibration excitation element is mounted on the first member and at least one sensor of the vibration sensor configuration is mounted on the second member.

11. The method of claim 6 , wherein identifying a valid contact state comprises determining the presence of (d).

12. The method of claim 11 , wherein the vibration excitation element and at least a first sensor of the vibration sensor configuration are mounted on the same one of the first and second members.

13. The method of claim 1 , wherein the measurement stability criterion comprises a current dimensional measurement differing from a previous dimensional measurement by a difference which is within a stability threshold amount.

14. The method of claim 13 , wherein the stability threshold amount is at most three times an increment of a least significant digit of a digital measurement display of the dimensional metrology hand tool.

15. The method of claim 1 , wherein the vibration excitation element comprises one of an electrically driven element or an element driven through a mechanism deriving power from a manual operation that is an inherent part of operating the metrology hand tool to contact the workpiece.

16. The method of claim 1 , wherein the vibration excitation element provides a momentary impulse that excites a vibration.

17. The method of claim 1 , wherein the vibration signature is a frequency-sampled vibration signature comprising at least one respective signal corresponding to a respective vibration frequency range.

18. The method of claim 1 , wherein the dimensional metrology hand tool is one of a caliper or a micrometer.

19. A dimensional metrology hand tool for obtaining a dimensional measurement of a workpiece, the metrology hand tool comprising:
a first workpiece contact surface included on a first member and a second workpiece contact surface included on a second member that moves relative to the first member;
a dimensional measurement sensor for measuring a separation between the first and second contact surfaces;
a vibration excitation element;
a vibration sensor configuration;
a visible measurement validity indicator; and
a signal processor,
wherein:
the vibration excitation element is configured to vibrate a portion of the metrology hand tool

Assignees

• Mitutoyo Corp

Inventors

• Dockrey Matthew Raymond
• Emtman Casey Edward

Classifications

• G01B21/04

  by measuring coordinates of points · CPC title

• G01B3/205

  provided with a counter for digital indication of the measured dimension · CPC title

• G01B3/18 Primary

  Micrometers · CPC title