Articulated arm coordinate measurement machine having a 2D camera and method of obtaining 3D representations

• US 9,628,775 B2
• Filed: 04/06/2015
• Issued: 04/18/2017
• Est. Priority Date: 01/20/2010
• Status: Active Grant

• Current Assignee: Faro Technologies Incorporated
• Original Assignee: Faro Technologies Incorporated
• Inventors: Bridges, Robert E., Atwell, Paul C.
• Primary Examiner(s): FULTON, CHRISTOPHER W
• Application Number:
  US14/679,580
• Publication Number:
  US 20150229907A1
• Time in Patent Office: 743 Days
• Field of Search: None
• CPC Class Codes: G01B 11/2509 Color coding
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 21/047 Accessories, e.g. for positioning, for tool-setting, for measuring probes
• CPC Class Codes: G01B 2210/58 Wireless transmission of information between a sensor or probe and a control or evaluation unit
• CPC Class Codes: G01B 5/008 using coordinate measuring machines
• CPC Class Codes: G01B 5/012 Contact-making feeler heads therefor
• 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
• CPC Class Codes: H04N 13/204 using stereoscopic image cameras stereoscopic photography G03B35/00
• CPC Class Codes: H04N 23/51 Housings

Abstract

A portable articulated arm coordinate measuring machine includes a noncontact 3D measuring device that has a projector that is manually movable by an operator from a first position to a second position. The projector is configured to emit a first pattern of light onto an object. The noncontact 3D measuring device further includes a scanner camera and an edge-detecting camera. The scanner camera is arranged to receive the first pattern of light reflected from the surface of the object. The edge-detecting camera arranged to receive light reflected from an edge feature of the object. The articulated arm coordinate measurement machine includes a processor configured to determine first 3D coordinates of an edge point of the edge feature based on electrical signals received from the scanner camera and the edge-detecting camera.

Claims

1. A method for measuring an edge point with a portable articulated arm coordinate measuring machine (AACMM), the method comprising:

providing the AACMM, the AACMM including a base, a manually positionable arm portion having an opposed first end and second end, the arm portion being rotationally coupled to the base, the arm portion including a plurality of connected arm segments, each arm segment including at least one position transducer for producing a position signal, a processor, an electronic circuit, a probe end coupled to the first end, a noncontact 3D measuring device coupled to the probe end, the noncontact 3D measuring device having a projector and a scanner camera, the AACMM further including and an edge-detecting camera coupled to the probe end, the edge-detecting camera being one of the scanner camera or a second camera different than the scanner camera;

moving by an operator the noncontact 3D measuring device from a first position to a second position, the second position being adjacent an object;

receiving by the electronic circuit the position signal from the at least one position transducer in each arm segment in response to the noncontact 3D measuring device being moved by the operator;

sending from the electronic circuit a first electrical signal to the processor in response to the position signal;

activating by an operator the noncontact 3D measuring device;

emitting from the projector a first pattern of light onto the object in response to the operator activating the noncontact 3D measuring device;

receiving with the scanner camera the first pattern of light reflected from the object and sending a second electrical signal to the processor in response;

receiving with the edge-detecting camera a second light reflected from an edge feature of the object and sending a third electrical signal to the processor in response, the edge feature having an edge point, the edge point being a point on the edge feature;

determining with the processor a first set of 3D coordinates of first points on a surface of the object, the first set of 3D coordinates based at least in part on the first pattern of light from the projector, the first electrical signal, and the second electrical signal;

further determining with the processor a first ray from the edge-detecting camera to the object, the first ray based at least in part on the first electrical signal and the third electrical signal;

further determining with the processor a second set of 3D coordinates of the edge point based at least in part on an intersection of the first ray with the first set of 3D coordinates of the surface; and

storing the second set of 3D coordinates of the edge point.

2. The method of claim 1 wherein the step of emitting the first pattern of light includes generating the first pattern of light in the form of a line of light.

3. The method of claim 1 wherein the step of emitting the first pattern of light includes generating the first pattern of light in the form of a coded structured light pattern.

4. The method of claim 1 wherein the step of receiving the second light reflected from the object includes receiving the second light in response to ambient light falling on the object.

5. The method of claim 1 further comprising:

emitting from a light source coupled to the probe end a third light onto the object; and

wherein the second light reflected from the object is at least a portion of the third light.

6. The method of claim 5 wherein the step of emitting the third light includes emitting a substantially uniform light over a surface of the object.

7. The method of claim 1 wherein the projector has a projector perspective center and the scanner camera has a scanner camera perspective center, rays of light from the projector passing through the projector perspective center, rays from a second pattern of light reflected off the object passing through the scanner camera perspective center, a baseline distance being a distance from the projector perspective center to the scanner camera perspective center, wherein the step of determining the first 3D coordinates includes determining the first 3D coordinates based at least in part on the baseline distance.

8. The method of claim 1 further comprising moving by an operator the noncontact 3D measuring device from the second position to a third position before determining the second set of 3D coordinates.