Noncontact scanning system

• US 8,526,012 B1
• Filed: 04/17/2012
• Issued: 09/03/2013
• Est. Priority Date: 04/17/2012
• Status: Active Grant

• Current Assignee: CyberOptics Corporation (Nordson Corporation)
• Original Assignee: Laser Design Incorporated (Nordson Corporation)
• Inventors: Schuster, C. Martin, Hetzler, Gregory G.
• Primary Examiner(s): NGUYEN, TU T
• Application Number:
  US13/448,598
• Time in Patent Office: 504 Days
• Field of Search: 356/612
• US Class Current: 356/612
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G01B 2210/44 with detectors on both sides of the object to be measured

Abstract

A noncontact object scanning system includes a horizontal table rotatable on a vertical axis, one or more scanners above the table and one or more scanners below the table. The table allows passage of radiant energy therethrough due to its transparency or construction as a nonreflective grid. A controller automatically steps the scanners through a scanning sequence, each scan associated with a segment of the object'"'"'s exterior surface. Surface segments scanned from above the table and from below the table combine to provide a comprehensive scan of the entire exterior surface. Adjacent surface segments overlap one another to provide redundant data used to overcome shadowing effects from the grid and to accurately align and merge the segments into a three dimensional representation of the complete exterior shape of the object. The scanners can incorporate color responsive light detectors whereby the three dimensional representation portrays color and shape.

Claims

1. A non-contact object scanning system, including:

a support structure for maintaining an object completely within a predetermined viewing volume for exposure to radiant energy for surface scanning, wherein the support structure, at least within and proximate the viewing volume, is formed of a material substantially nonreflective of the radiant energy and further is adapted to allow passage of the radiant energy therethrough;

a scanning apparatus comprising a radiant energy source located outside of the viewing volume to direct the radiant energy onto the object maintained in the viewing volume, and a radiant energy sensor adapted to detect the radiant energy reflected by an exterior surface of the object visible from outside the viewing volume;

a controller operatively associated with the scanning apparatus to automatically step the scanning apparatus through a sequence of scans of the object maintained in the viewing volume, wherein each of the scans comprises directing the radiant energy onto a selected segment of the exterior surface associated with the scan, and detecting the radiant energy reflected by the associated segment to generate a surface data set representing a three-dimensional shape of the associated segment, wherein the sequence of scans consists essentially of direct scans of first selected segments disposed to receive the radiant energy directly from the radiant energy source, and indirect scans of second selected segments disposed to receive the radiant energy via passage of the radiant energy through the support structure, and the first segments and second segments in combination comprise substantially the entire visible exterior surface; and

an information processor coupled to receive the surface data sets associated with the scans of the sequence, and adapted to merge and align the surface data sets into a selected three dimensional coordinate space to generate in said space a three dimensional representation of an entire continuous exterior shape of the object.

2. The system of claim 1 wherein:

the support structure comprises a base having a horizontal surface for supporting the object by gravity.

3. The system of claim 2 wherein:

the base is transparent to the radiant energy.

4. The system of claim 2 wherein:

the base comprises a grid absorptive of the radiant energy.

5. The system of claim 4 wherein:

the scanning apparatus comprises a first radiant energy source and a first radiant energy sensor disposed above the base, and a second radiant energy source and a second radiant energy sensor disposed below the base.

6. The system of claim 5 wherein:

each of the radiant energy sources is movable relative to the base to direct the radiant energy onto overlapping surface regions of the exterior surface at different angles with respect to the exterior surface.

7. The system of claim 2 wherein:

the base is rotatable about a vertical axis.

8. The system of claim 1 wherein:

the radiant energy source and the radiant energy sensor are fixed relative to one another and movable in concert with respect to the support structure.

9. The system of claim 1 further including:

a plurality of noncontact position-indicating features disposed within and fixed with respect to the viewing volume.

10. The system of claim 1 wherein:

the radiant energy source comprises a white light projection scanner.

11. The system of claim 1 wherein:

the radiant energy comprises a laser line scanner.

12. The system of claim 1 wherein:

adjacent ones of the segments overlap one another whereby the surface data sets representing adjacent surface segments comprise redundant data corresponding to an overlapping surface region common to the adjacent surface segments; and

the processor is adapted to use the redundant data region to align the adjacent surface segments in the selected three dimensional coordinate space.

13. The system of claim 1 wherein:

the processor is adapted to selectively delete a portion of the data in a given surface data set that fails to exceed a predetermined threshold.

14. The system of claim 1 wherein:

the support structure comprises a fixture adapted to suspend the object in the viewing volume through point contact with the exterior surface.

15. The system of claim 1 wherein:

the radiant energy sensor is color responsive whereby each surface data set further represents a color of the associated segment, and the processor is responsive to color-related information when merging and aligning the surface data sets whereby the three dimensional representation of the exterior shape further portrays a color of the object.

16. A process for generating an exterior surface scan of an object, including:

using a support structure to maintain an object completely within a predetermined viewing volume, wherein the support structure at least within and proximate the viewing volume is constructed of a nonreflective material and is configured to allow passage of radiant energy therethrough;

with the object maintained in the viewing volume, scanning the object by directing radiant energy onto an exterior surface of the object from outside the viewing volume automatically in a sequence of scans, wherein each of the scans comprises directing radiant energy onto a selected segment of the exterior surface associated with the scan, wherein the sequence of scans consists essentially of a plurality of direct scans on first selected segments receiving the radiant energy directly from the radiant energy source and a plurality of indirect scans of second selected segments receiving the radiant energy via passage of the radiant energy through the support structure, and wherein the first and second segments in combination comprise substantially the entire visible exterior surface;

detecting the radiant energy reflected by the selected segments to generate with respect to each segment a surface data set describing a three dimensional shape of the associated segment; and

merging and aligning the surface data sets in a selected three dimensional coordinate space to generate in said space a three dimensional representation of an entire continuous exterior shape of the object.

17. The process of claim 16 wherein:

maintaining the object in the viewing volume comprises supporting the object by gravity on a base.

18. The process of claim 17 wherein:

the base comprises a grid absorptive of the radiant energy, and the scanning comprises directing the radiant energy redundantly onto at least the second selected segments at different angles.

19. The process of claim 17 wherein:

directing the radiant energy comprises providing a first radiant energy source above the base, and a second radiant energy source below the base for directing the radiant energy through the base and onto an underside region of the exterior surface.

20. The process of claim 19 wherein:

detecting the radiant energy comprises using a first radiant energy sensor associated with the first radiant energy source and a second radiant energy sensor associated with the second energy source.

21. The process of claim 16 wherein:

scanning the object comprises selectively rotating the base about a vertical axis.

22. The process of claim 16 wherein:

scanning the object comprises directing the radiant energy onto adjacent selected segments that overlap one another whereby the surface data sets representing adjacent segments comprise redundant data corresponding to a region of overlap; and

the merging and aligning of the surface data sets comprises fitting the redundant data to align the adjacent segments in the selected three dimensional coordinate space.

23. The process of claim 22 wherein:

merging and aligning the service data sets comprises deleting redundant data.

24. The process of claim 16 further including:

providing a plurality of noncontact position-indicating features disposed within and fixed with respect to the viewing volume;

wherein merging and aligning the surface data sets comprises locating each of the data sets with respect to the noncontact position-indicating features.

25. The process of claim 16 wherein:

generating the surface data sets comprises generating only the data that exceeds a predetermined threshold.

26. The process of claim 16 wherein:

generating a surface data set with respect to each segment further comprises generating data describing a color of the associated segment.

27. The process of claim 16 wherein:

directing the radiant energy onto the exterior surface comprises using a laser line scanner to project a linear image onto the exterior surface, and selectively moving the scanner with respect to the object to sweep the linear image over a surface area corresponding to the associated segment.

28. The process of claim 16 wherein:

directing the radiant energy onto the exterior surface comprises projecting structured light onto the exterior surface over a surface region corresponding to the associated segment.