Three-dimensional vision system

• US 4,731,853 A
• Filed: 03/21/1985
• Issued: 03/15/1988
• Est. Priority Date: 03/26/1984
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Okada, Takushi, Hata, Seiji, Okabe, Takafumi, Ariga, Makoto
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US06/714,455
• Time in Patent Office: 1,090 Days
• Field of Search: 356/17, 356/18, 356/376, 356/394, 382/58, 382/50, 250/202, 250/560, 358/96, 358/101, 414/730, 901/35, 901/47, 364/513, 364/559
• US Class Current: 382/153
• CPC Class Codes: G06V 20/64 Three-dimensional objects

Abstract

The present invention consists in a three-dimensional vision system comprising a three-dimensional vision sensor which projects slit-like light on an object to-be-handled and which reads out a resulting slit image, an image input portion which controls the slit-like light to be lit up and put out and also controls the read-out of the slit image and which performs extraction processing of differential signals as to image signals read out, and an image processor which performs required controls concerning said image input portion and which processes image data of said image input portion; an image with the projected slit-like light and an image without it being sequentially sampled on an identical scanning line of the read-out image so as to obtain the differential image between them, thereby to extract a light segmentation line based on the projected slit-like light.

Claims

1. A three-dimensional vision system, comprising:

three-dimensional vision means for projecting slit-like light onto an object to-be-handled over each of a plurality of scanning lines and for reading image signals representing both a resulting slit image of the object while the slit-like light is projected over one of said plurality of scanning lines and a background image of the object along the same one of said plurality of scanning lines while no slit-like light is projected,

an image input portion which controls illumination of the slit-like light to cause said vision means to sequentially project said slit-like light over each of said plurality of scanning lines, and also controls the reading of image signals representing both the slit-image and the background image along each of said scanning lines, and which performs extraction processing for each one of said plurality of scanning lines to obtain differential signals from the image signals representing a resulting slit image of the object along a scanning line and the image signals representing the background image of the object along the same scanning line to obtain said differential signals for each one of said scanning lines from the image signals read out, and

means including means for extracting a position corresponding to a maximum value among said differential signals occurring along each of said scanning lines, for extracting a light segmentation line from each one of said differential signals,

whereby an image processor can recognize a three-dimensional shape of the object on the basis of a plurality of said light segmentation lines extracted from said differential signals and the positions corresponding to the maximum value of each of one of said differential signals.

2. A three-dimensional vision system according to claim 1, wherein said image input portion comprises an image memory which stores the image without the projected slit-like light.

3. A three-dimensional vision system according to claim 1, wherein said image input portion further comprises peak position detection means for detecting and storing said position corresponding to a maximum value from among each one of the differential signals for each of said scanning lines.

4. The vision system of claim 1, wherein said image input portion comprises:

control means for sequentially driving said vision means between a first state wherein said vision sensor projects slit-like light on the object while providing a first image of the object and a second state wherein said vision means projects no light on the object while providing a second image of the object.

5. The vision system of claim 1, wherein said vision means includes scanning means for providing said vision sensor with view of progressively varying perspective of the object along successive scanning lines.

6. The vision system of claim 4, wherein said vision means includes scanning means for providing said vision means with views of progressively varying perspective of the object along successive scanning lines during said first and second states.

7. The vision system of claim 1, wherein said image input portion comprises circuit means for receiving image signals from a first image provided by said vision means while said image input portion controls illumination of the object to effect a first state of illumination and for receiving image signals from a second image provided by said vision means while said image input portion controls illumination of the object to effect a second state of illumination, and for comparing said image signals from said first and second images to provide said differential signals.

8. The vision system of claim 4, wherein said image input portion comprises circuit means for simultaneously receiving and comparing image signals from said first and second images to provide said differential signals.

9. The vision system of claim 5, wherein said image input portion comprises circuit means for simultaneously receiving and comparing image signals from said first and second images to provide said differential signals.

10. The vision system of claim 1, wherein said image input portion comprises means responsive to generation of said differential image for detecting and storing a first value for the position of the maximum signal level occurring along said scanning line, and wherein said system further comprises means for calculating a second value for the position of said maximum signal level from said first value and differential signals occurring along said scanning line in the vicinity of the position defined by said first value.

11. The vision system of claim 4, wherein said image input portion comprises means responsive to generation of said differential image for detecting and storing a first value for the position of the maximum signal level occurring along said scanning line, and wherein said system further comprises means for calculating a second value for the position of said maximum signal level from said first value and differential signals occurring along said scanning line in the vicinity of the position defined by said first value.

12. The vision system of claim 5, wherein said image input portion comprises means responsive to generation of said differential image for detecting and storing a first value for the position of the maximum signal level occurring along said scanning line, and wherein said system further comprises means for calculating a second value for the position of said maximum signal level from said first value and differential signals occurring along said scanning line in the vicinity of the position defined by said first value.

13. The vision system of claim 7, wherein said system further comprises means for calculating a second value for the position of said maximum signal level from said first value and differential signals occurring along said scanning line in the vicinity of the position defined by said first value.

14. The vision system of claim 1, wherein said three-dimensional image vision means comprises means controllable by said image input portion for independently projecting a pair of slit-like light beams onto the object, and said image portion comprises memory means for storing said image occurring along each said scanning line without said slit-like light.

15. The vision system of claim 2, wherein said three-dimensional image vision means comprises means controllable by said image input portion for independently projecting a pair of slit-like light beams on the object.

16. A process for recognizing the three-dimensional shape of an object, comprising:

projecting a beam of slit-like light upon an object during a first operational state and projecting no slit-like light upon the object during a second operational state;

generating first and second image signals representative of images of the object formed along a scanning line during each of said first and second operational states;

simultaneously processing said first and second image signals taken along said scanning line to provide differential signals representative of differences in amplitude between said first and second signals, whereby a light segmentation line based on the projected slit-like light beam is extracted from said images.

17. The process of claim 16, further comprised of detecting the position of the maximum signal level occurring along each said scanning line.

18. The process of claim 16, further comprised of detecting a first value for the position of the maximum signal level occurring along each said scanning line, and calculating a second value for the position of said maximum signal level from said first value and the differential signals occurring along each said scanning line in the vicinity of said position defined by said first value.

19. A three-dimensional vision system, comprising:

three-dimensional vision means having a projector for projecting slit-like light defining a plane onto an object during a first operational state and projecting no slit-like light upon the object during a second operational state, having an image sensor including an array of pixels for detecting images of the object from a direction inclined against the plane and coverting the images of the object into image signals, and sensor signal reading means for reading the image signals, said images of the object including a slit image resulting from illumination of the object with the slit-like light during said first operational state and a background image occurring while no slit-like light is projected by aid projector onto the object;

scanning control means for sequentially controlling over each of a plurality of scanning lines, the presence of said slit-like light emanating from the projector during said first operational state and the absence of said slit-like light during said second operational state, and for controlling the reading of image signals from said sensor signal reading means to provide image signals representing one of said images detected during said first operational state and one of said images formed during said second operational state for each of said plurality of scanning lines;

converter means for converting the image signals into digital signals;

memory means for storing the digital signals read-out from the sensor signal reading means;

differential signal extracting means controlled by said scanning control means and coupled to said converter means and said memory means, for sequentially sampling the digital signals formed from said image signals for each of said scanning lines during both of said operational states, and for extracting a differential image signal for each of said scanning lines from the digital signals formed for each of said scanning lines;

light segmentation line extracting means including means for extracting a position corresponding to the maximum value of said differential image signal along each of said scanning lines for extracting a light segmentation line from each said differential image signal obtained by the differential signal extracting means; and

an image processor for recognizing the three-dimensional shape of the object in accordance with the light segmentation line extracted by the light segmentation line extracting means.

20. A three-dimensional vision system according to claim 19, wherein said memory means stores the digital signals resulting from conversion of image signals occurring during said second operational state.

21. A three-dimensional vision system, comprising:

three-dimensional vision means for projecting planar light beams on objects to-be-handled and for reading from an array of pixels, image signals representing resulting images of the objects occurring over a plurality of scanning lines, with a first one of said images in each of said scanning lines being a resulting image occurring during illumination of the objects with projected slit-like light and a second one of said images being a background image occurring in the same scanning line during the absence of illumination of the objects with said slit-like light;

an image input portion which sequentially controls illumination of objects by the light beams to provide one image of the objects during the first operational state and another image of the object during the second operational state for each one of said scanning lines, controls the reading of the images, and which performs extraction processing to obtain differential signals for each of said scanning lines from the image signals read representing a resulting slit image of the object along said scanning lines and representing the background image of the object along corresponding scanning lines;

means for extracting a position corresponding to a maximum value among said differential signals for each of said scanning lines;

means for determining a light segmentation line from each one of said differential signals extracted by said input portion; and

an image processor can recognize a three-dimensional shape of the object on the basis of a plurality of said light segmentation line extracted from said differential signals and the positions corresponding to the maximum value of each one of said differential signals.

22. A three-dimensional vision system according to claim 21, wherein said determining means comprises peak position detection means for detecting and storing said position from among the differential signals for each one of said scanning lines.

23. The vision system of claim 22, wherein said image input portion comprises:

control means for sequentially driving said vision means between a first state wherein said vision sensor projects planar light beams on objects along a series of scanning lines while alternately providing said first images of the objects along each one of said scanning lines and a second state wherein said vision means projects no light on the objects while providing said second images of the object along the same ones of said scanning lines.

24. The vision system of claim 21, wherein said vision means includes scanning means for providing said vision sensor with view of progressively varying perspective of the objects along successive scanning lines.

25. The vision system of claim 21, wherein said image input portion comprises circuit means for receiving said differential signals from a first image provided by said vision sensor while said image input controls illumination of the object to effect a first state of illumination and for simultaneously receiving said differential signals from a second image provided by said vision sensor while said image input controls illumination of the object to effect a second state of illumination, and for comparing said differential signals from said first and second images to provide said differential image.