Portable coordinate measurement machine having a bearing assembly with an optical encoder

• US 9,410,787 B2
• Filed: 10/27/2014
• Issued: 08/09/2016
• Est. Priority Date: 02/14/2002
• Status: Expired due to Term

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Raab, Simon, Barber, Marc M.
• Primary Examiner(s): Bennett, G. Bradley
• Application Number:
  US14/524,073
• Publication Number:
  US 20150192399A1
• Time in Patent Office: 652 Days
• Field of Search: 33/1.PT, 335/03
• US Class Current: 1/1
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G01B 11/005 coordinate measuring machines
• CPC Class Codes: G01B 21/042 Calibration or calibration artifacts G01B3/30, G01B9/02072 take precedence
• CPC Class Codes: G01B 5/008 using coordinate measuring machines
• CPC Class Codes: G01B 7/008 using coordinate measuring machines
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• 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 2219/37193 Multicoordinate measuring system, machine, cmm
• CPC Class Codes: G05B 2219/40233 Portable robot
• CPC Class Codes: G05B 2219/45061 Measuring robot

Abstract

A portable articulated arm coordinate measurement machine having an articulated arm that includes a first arm connected to a second arm segment by a connecting segment. An assembly is provided having a first pair of bearings and a first optical encoder and a second pair of bearings and a second optical encoder The first optical encoder includes a first patterned disk and a first read head. The second optical encoder includes a second patterned disk and a second read head. The first and second patterned disks are both fixed with respect to the connecting segment. An electronic circuit is operably coupled to the first read head and the second read head, the electronics being configured to determine three-dimensional coordinates of the probe based at least in part on a first angle and a second angle measured by the first and second optical encoders.

Claims

1. A portable articulated arm coordinate measurement machine, comprising:

a manually positionable articulated arm having opposed first and second ends, the articulated arm including a plurality of connected arm segments, the plurality of arm segments including a first arm segment connected to a second arm segment by a connecting segment;

a base section connected to the second end;

a probe connected to the first end;

electronics;

a first patterned disk having a first periodic pattern of a measurable characteristic and a first read head in proximity to the first patterned disk;

a second patterned disk having a second periodic pattern of the measurable characteristic and a second read head in proximity to the second patterned disk;

a first pair of bearings including a first bearing and a second bearing which rotate about a first axis; and

a second pair of bearings including a third bearing and a fourth bearing which rotate about a second axis;

wherein the first arm segment rotates about the first axis, the second arm segment rotates about the second axis, and the connecting segment is fixed with respect to the first axis and the second axis;

wherein one of the first patterned disk and the first read head is fixed with respect to the connecting segment, and the other of the first patterned disk and the first read head is fixed with respect to the first arm segment, the first read head producing a first signal, the first signal indicating a first angle of rotation of the first arm segment about the first axis;

wherein one of the second patterned disk and the second read head is fixed with respect to the connecting segment, and the other of the second patterned disk and the second read head is fixed with respect to the second arm segment, the second read head producing a second signal, the second signal indicating a second angle of rotation of the second arm segment about the second axis;

wherein the electronics is operably coupled to the first read head and the second read head, the electronics being configured to determine three-dimensional coordinates of the probe based at least in part on the first angle and the second angle; and

wherein the first arm segment and one of the first patterned disk and the first read head are supported for rotation about the first axis by bearings selected from the group consisting of the first bearing and the second bearing.

2. The portable articulated arm coordinate measurement machine of claim 1 wherein the second arm segment and one of the second patterned disk and the second read head are supported for rotation about the second axis by bearings selected from the group consisting of the third bearing and the fourth bearing.

3. The portable articulated arm coordinate measurement machine of claim 1 wherein the connecting segment is a socket joint configured to receive the first bearing in a first recess and the third bearing in a second recess.

4. The portable articulated arm coordinate measurement machine of claim 1 wherein one of the first axis and the second axis is a hinge axis and the other of the first axis and the second axis is a swivel axis.

5. The portable articulated arm coordinate measurement machine of claim 1 further comprising:

a third read head in proximity to the first patterned disk the third read head producing a third signal, the third signal indicating a third angle of rotation of the first arm segment about the first axis;

wherein the electronics is configured to determine the three-dimensional coordinates of the probe further based at least in part on the third angle.

6. The portable articulated arm coordinate measurement machine of claim 1 further comprising an encoder board that includes an analog-to-digital converter and a serial port, the encoder board being inside the first arm segment.

7. The portable articulated arm coordinate measurement machine of claim 1 wherein the first bearing and the second bearing are preloaded along the first axis.