Portable coordinate measurement machine with pre-stressed bearings

• US 6,606,539 B2
• Filed: 01/15/2002
• Issued: 08/12/2003
• Est. Priority Date: 02/23/1993
• Status: Expired due to Fees

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Raab, Simon
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): Rao, Sheela S.
• Application Number:
  US10/053,210
• Publication Number:
  US 20020087233A1
• Time in Patent Office: 574 Days
• Field of Search: 700/245, 700/262, 700/195, 335/03
• US Class Current: 700/245
• 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: G05B 19/401 characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes G05B19/19 takes precedence
• CPC Class Codes: G05B 19/4207 in which a model is traced or scanned and corresponding data recorded
• CPC Class Codes: G05B 2219/37193 Multicoordinate measuring system, machine, cmm
• CPC Class Codes: G05B 2219/39028 Relative to base calibrated 6-DOF device, cmm connected between wrist and base
• CPC Class Codes: G05B 2219/40233 Portable robot
• CPC Class Codes: G05B 2219/41176 Compensation control, position error with data from lookup memory
• CPC Class Codes: G05B 2219/45061 Measuring robot

Abstract

A portable coordinate measuring machine comprises a multijointed manually positionable articulated measuring arm for accurately and easily measuring a volume. The articulated arm includes a plurality of bearing arrangements comprising at least a pair of spaced bearings, the spaced bearings being pre-stressed such that, under an applied load, any motion of the arm is limited to axial motion and wherein the mechanical stability of the arm is increased.

Claims

1. A portable three dimensional coordinate measurement machine for measuring the position of an object in a selected volume comprising:

a manually positionable articulated arm having opposed first and second ends, said arm including a plurality of arm sections interconnected by joints whereby said arm sections and said joints together provide at least six degrees of freedom within a selected volume, said articulated arm further including at least six position transducers, each of which produce a position signal;

said articulated arm further including a plurality of bearing arrangements, each of said bearing arrangements comprising at least a pair of spaced bearings, said pair of spaced bearings being preloaded such that, under an applied load, any motion of said arm is limited to axial motion and wherein said preloaded bearings increase mechanical stability of said articulated arm;

a measurement probe attached to a first end of said articulated arm;

an electronic circuit which receives the position signals from the transducers and provides a digital coordinate corresponding to the position of the probe in a selected volume.

2. The three dimensional coordinate measuring machine of claim 1 wherein:

said preloaded bearings comprise roller bearings.

3. The three dimensional coordinate measuring machine of claim 2 wherein:

said roller bearings comprise conical roller bearings.

4. The three dimensional coordinate measuring machine of claim 1 wherein:

compression forces on said spaced bearings provides said preloading.

5. The three dimensional coordinate measuring machine of claim 4 wherein:

a compression nut provides said compression forces.

6. The three dimensional coordinate measuring machine of claim 1 including:

at least one thrust bearing in said articulated arm to provide mechanical stiffening.

7. The three dimensional coordinate measuring machine of claim 1 including:

a base attached to said second end of said arm.

8. The three dimensional coordinate measuring machine of claim 1 wherein:

said position transducer comprise encoders.

9. A portable three dimensional coordinate measurement machine for measuring the position of an object in a selected volume comprising:

a manually positionable articulated arm having opposed first and second ends, said arm including a first arm section jointedly attached to a second arm section, said second arm section jointedly attached to a third arm section whereby said arm sections and said joints together provide at least six degrees of freedom within a selected volume, said articulated arm further including at least six position encoders, each of which produce a position signal;

said articulated arm further including a plurality of bearing arrangements, each of said bearing arrangements comprising at least a pair of spaced roller bearings, said pair of spaced bearings being preloaded such that, under an applied load, any motion of said arm is limited to axial motion and wherein said preloaded bearings increase mechanical stability of said articulated arm;

a base attached to said first arm section;

a measurement probe jointedly attached to said third arm section;

at least two joints between said first arm section and said second arm section and at least two joints between said second arm section and said third arm section;

an electronic circuit which receives the position signals from said encoders and provides a digital coordinate corresponding to the position of the probe in a selected volume.

10. The three dimensional coordinate measuring machine of claim 9 wherein:

said roller bearings comprise conical roller bearings.

11. The three dimensional coordinate measuring machine of claim 9 wherein:

compression forces on said spaced bearing provide said preloading.