3D scanner and method for measuring heights and angles of manufactured parts

• US 6,501,554 B1
• Filed: 06/20/2000
• Issued: 12/31/2002
• Est. Priority Date: 06/20/2000
• Status: Expired due to Fees

• Current Assignee: Ismeca Semiconductor Holding S.A (COHU Incorporated)
• Original Assignee: PPT Vision, Inc. (Datalogic S.p.A.)
• Inventors: Shi, Xin, Hackney, Joshua J., Malek, Arye, Ma, John, McPherson, Matthew M.
• Primary Examiner(s): Dang, Hung Xuan
• Application Number:
  US09/597,865
• Time in Patent Office: 924 Days
• Field of Search: 356/601, 356/614, 356/625, 356/627, 356/628, 356/630, 356/634, 356/635, 356/327.1, 356/327.2, 356/327.3
• US Class Current: 356/601
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques

Abstract

In the context of a machine-vision system for inspecting a part, a method and apparatus to provide high-speed 3D (three-dimensional) inspection of manufactured parts. Parts are inspected to obtain dimensional and geometric information regarding such characteristics as sag or bow of subportions of the item, the angle of pitch, yaw, and or roll of one portion relative to another, heights of various formations on the part. In some embodiments, an array of height pixels is calculated, and regions of interest (ROIs) are located within the array, and the ROIs are used to determine characteristic geometries of the parts being measured. One measurement system includes a light source, an imager, and a computer. Light source provides projected patterned light on the object useful to obtain 3D geometric information about the object. The imager has a reception optical axis that intersects the object when the machine-vision system is in operation. In some embodiments, imager includes at least three rows of imaging pixels positioned to receive light shone onto the object by the light source. The computer system calculates three-dimensional object-geometry data of the object using signals from the imager, and computes at least a first characteristic plane and a second characteristic plane of the object from the calculated object-geometry data. The method provides a process for obtaining and manipulating image data (e.g., make calculations on ROI data within one or more arrays of height pixels) to determine characteristics of the parts.

Claims

1. A machine-vision system for inspecting an object, comprising:

a light source that provides projected patterned light on the object useful to obtain 3D geometric information about the object;

an imager, wherein the imager has a reception optical axis that intersects the object when the machine-vision system is in operation, and wherein the imager includes at least three rows of imaging pixels positioned to receive light shone onto the object by the light source; and

a computer system that calculates three-dimensional object-geometry data of the object using signals from the imager, and computes at least a first characteristic plane and a second characteristic plane of the object from the calculated object-geometry data.

2. The machine-vision system of claim 1, wherein the computer system further computes at least one angle of the first characteristic plane relative to the second characteristic plane.

3. The machine-vision system of claim 1, wherein the computer system further computes at least a pitch angle and a roll angle of the first characteristic plane relative to the second characteristic plane.

4. The machine-vision system of claim 1, wherein the computer system further computes at least one bump height of an area of the object relative to the first characteristic plane.

5. The machine-vision system of claim 1, wherein the computer system further computes at least one section sag of an area of the object relative to the second characteristic plane.

6. The machine-vision system of claim 1, wherein the computer system further computes a third characteristic plane of the object, and computes an intersection of the first plane and the second plane, and computes an offset distance between the intersection and the third plane.

7. The machine-vision system of claim 1, further comprising:

an inspection station that supports the object;

a scanner mechanism that moves the imager relative to the object at the inspection station such that different portions of the object are successively imaged by the imager;

a machine base that supports the inspection station and the scanner mechanism; and

an isolation mount between the machine base and the inspection station to reduce transmission of vibration between the machine base and the inspection station.

8. The machine-vision system of claim 7, wherein the scanner mechanism and the inspection station are affixed to one another more rigidly than either is to the machine base.

9. The machine-vision system of claim 7, further comprising:

a comparator coupled to the computer, wherein the comparator compares one or more characteristics of the acquired three-dimensional object geometry data with an intended predetermined geometry to produce a signal indicative of any object geometry departure of an actual object geometry from the intended predetermined geometry.

10. The machine-vision system of claim 1, further comprising:

a comparator coupled to the computer, wherein the comparator compares one or more characteristics of the acquired three-dimensional object geometry data with an intended predetermined geometry to produce a signal indicative of any object geometry departure of an actual object geometry from the intended predetermined geometry.

11. A method of measuring a three-dimensional geometry of an object having at least one surface to be measured, comprising:

(a) receiving image signals representing a three-dimensional geometry of the object into a computer;

(b) calculating with the computer object-geometry data representing three-dimensional geometry of the object; and

(c) calculating with the computer values representing at least a first characteristic plane and a second characteristic plane of the object from the calculated object-geometry data.

12. The method of claim 11, further comprising:

(d) calculating at least one angle of the first characteristic plane relative to the second characteristic plane.

13. The method of claim 11, further comprising:

(e) calculating at least a pitch angle and a roll angle of the first characteristic plane relative to the second characteristic plane.

14. The method of claim 11, further comprising:

(f) calculating at least one bump height of an area of the object relative to the first characteristic plane.

15. The method of claim 11, further comprising:

(g) calculating at least one section sag of an area of the object relative to the second characteristic plane.

16. The method of claim 11, further comprising:

(h) calculating a third characteristic plane of the object, and computes an intersection of the first plane and the second plane, and computes an offset distance between the intersection and the third plane.

17. The method of claim 11, further comprising:

(i) supporting the object at an inspection station;

(j) moving an imager relative to the object at the inspection station such that different portions of the object are successively imaged by the imager;

(k) supporting the inspection station on a machine base; and

(l) mechanically isolating the inspection station from the machine base to reduce coupling of vibration between the machine base and the inspection station.

18. The method of claim 11, further comprising:

(m) projecting patterned light onto the object, the light having a spatial-modulation pattern;

(n) scanning the object within the spatial-modulation patterned light to create a first reflected light; and

(o) receiving the first reflected light into at least three linear imager regions and generating resulting image signals.

19. The method of claim 11, further comprising:

(p) comparing one or more characteristics of the acquired three-dimensional object geometry data with an intended predetermined geometry; and

(q) producing a signal indicative of any object geometry departure of an actual object geometry from the intended predetermined geometry.

20. A machine-vision system for inspecting an object, comprising:

a light source that provides projected light on the object;

an imager, wherein the imager generates signals from the light representative of three-dimensional object-geometry data of the object;

means for determining at least a first characteristic plane and a second characteristic plane of the object from the image signals.

21. A machine-vision system for inspecting an object, comprising:

a light source that provides projected light on the object;

an imager, wherein the imager generates signals from the light representative of three-dimensional object-geometry data of the object;

means for determining an angle between a first characteristic plane and a second characteristic plane of the object from the image signals.

22. A machine-vision system for inspecting an object, comprising:

a light source that provides projected light on the object;

an imager, wherein the imager generates signals from the light representative of three-dimensional object-geometry data of the object;

means for determining a distance between a first feature of the object and a first characteristic plane and the distance between a second feature of the object a second characteristic plane of the object from the image signals.

23. A method for measuring relative measurements of a part in a three-dimensional representation of part measurements comprising:

obtaining three-dimensional data points representing a geometry of the part;

successively examining a plurality of data points along each of a plurality of radial directions in the three-dimensional data points in order to locate at least one distinctive part feature along each of the plurality of radial directions;

fitting a predetermined geometric model to the distinctive part features to obtain a representation of the part; and

performing a linear transformation based on the geometric model to align representation of the part to a standard orientation.

24. The method of claim 23, further comprising:

calculating at least one angle a portion of the part relative to the standard orientation.

25. The method of claim 23, further comprising:

calculating at least a pitch angle and a roll angle of a portion of the part relative to the standard orientation.

26. The method of claim 23, further comprising:

calculating a height of a portion of the part relative to the standard orientation.

27. The method of claim 23, wherein the geometric model is a plane, and the linear transformation rotates the representation of the part to align the plane to the standard orientation.