Enhanced position detection for a CMM

• US 8,099,877 B2
• Filed: 03/26/2010
• Issued: 01/24/2012
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Hexagon Technology Center GmbH (Hexagon AB)
• Original Assignee: Hexagon Metrology AB (Hexagon AB)
• Inventors: Champ, Peter
• Primary Examiner(s): FULTON, CHRISTOPHER W
• Application Number:
  US12/748,267
• Publication Number:
  US 20110107614A1
• Time in Patent Office: 669 Days
• Field of Search: 335/03
• US Class Current: 33/503
• CPC Class Codes: B25J 13/02 Hand grip control means handles or pedals for crane control B66C13/56; for measuring the force applied to control members G01L5/22; hand-held casings for switching devices, e.g. joy-sticks H01H9/0214
• CPC Class Codes: B25J 19/00 Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators safety-devices in general F16P; protection against radiation in general G21F
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G01B 21/04 by measuring coordinates of points
• CPC Class Codes: G01B 5/008 using coordinate measuring machines
• CPC Class Codes: G01B 7/008 using coordinate measuring machines
• CPC Class Codes: G05B 2219/39019 Calibration by cmm coordinate measuring machine over a certain volume
• CPC Class Codes: Y10T 74/20305 Robotic arm

Abstract

A coordinate measurement device comprises an articulated arm and a laser scanner assembly. The articulated arm can have a first end, a second end, and a plurality of jointed arm segments therebetween. Each arm segment can define at least one axis of rotation, and a last axis of rotation can be defined by bearings near a distal end of the arm. The laser scanner assembly can couple to the distal end of the arm. The arm can continuously generate trigger signals that are received by the laser scanner and indicate a time at which the arm'"'"'s position is measured.

Claims

1. A coordinate measurement device comprising:

an articulated arm having a first end, a second end, and a plurality of jointed arm segments therebetween, each arm segment defining at least one axis of rotation, a last axis of rotation being defined by bearings near a distal end of the arm; and

a laser scanner assembly coupled to the distal end of the arm wherein the arm continuously generates trigger signals which are received by the laser scanner and indicate a time at which the arm'"'"'s position is measured,

wherein an arm measurement frequency is higher than a scanner measurement frequency.

2. The CMM of claim 1 wherein the trigger signal is created by a function generator in electronics in the arm.

3. A coordinate measurement device comprising:

an articulated arm having a first end, a second end, and a plurality of jointed arm segments therebetween, each arm segment defining at least one axis of rotation, a last axis of rotation being defined by bearings near a distal end of the arm; and

a laser scanner assembly coupled to the distal end of the arm wherein the arm continuously generates trigger signals which are received by the laser scanner and indicate a time at which the arm'"'"'s position is measured,

wherein the arm position at the time of a scanner image is calculated by interpolating between two arm positions based on times associated with the trigger signals and the time of the scanner image.

4. The CMM of claim 3, wherein the trigger signal is created by a function generator in electronics in the arm.

5. A method of operating a coordinate measurement device comprising:

continuously measuring the position of an articulated arm;

generating a plurality of trigger signals upon each measurement of the position of the articulated arm;

transmitting the trigger signals to a scanner at an end of the articulated arm;

acquiring a scanner measurement from the scanner;

associating the scanner measurement with one or more trigger signals; and

associating an interpolated arm position with the scanner measurement.

6. The method of claim 5, wherein the interpolation is a linear interpolation.

7. The method of claim 5, wherein the interpolation is a higher order polynomial interpolation.

8. The method of claim 5, wherein the step of continuously measuring comprises continuously outputting the angular position of a plurality of rotatable joints.

9. The method of claim 5, wherein the scanner is a laser scanner.

10. The method of claim 9, wherein the scanner measurement comprises coordinate measurements.

11. The method of claim 5, wherein the scanner measurement is associated with a plurality of trigger signals.

12. A method of operating a coordinate measurement device comprising:

continuously measuring the position of an articulated arm;

generating a plurality of trigger signals upon each measurement of the position of the articulated arm;

transmitting the trigger signals to a scanner at an end of the articulated arm;

acquiring a scanner measurement from the scanner; and

associating the scanner measurement with one or more trigger signals;

wherein a frequency of measurement of the position of the articulated arm is higher than a frequency of measurement of the scanner.

13. The method of claim 12, wherein the step of continuously measuring comprises continuously outputting the angular position of a plurality of rotatable joints.

14. The method of claim 12, wherein the scanner is a laser scanner.

15. The method of claim 14, wherein the scanner measurement comprises coordinate measurements.

16. The method of claim 12, wherein the scanner measurement is associated with a plurality of trigger signals.