Object detection system using TOF sensor

{
  "publication_number": "US11328442B2",
  "country": "US",
  "kind": "B2",
  "title": "Object detection system using TOF sensor",
  "abstract": "The object detection system includes a TOF sensor which outputs an image of a target space on the basis of a phase difference between reference light emitted toward the target space and reflected light from the target space, an object detection section which detects a position of an object present in the target space on the basis of the output image, an imaging conditions calculation section which calculates imaging conditions including at least one of an integration time and a light emission period of the TOF sensor on the basis of an image of the detected object, and an imaging conditions changing section which changes a configuration of the TOF sensor to the calculated imaging conditions, and the object detection section detects a position of the object on the basis of the image output under the changed imaging conditions.",
  "claims": [
    "1. An object detection system, comprising: a TOF sensor which outputs an image of a target space on the basis of a phase difference between reference light emitted toward the target space and reflected light from the target space, an object detection section which detects a position of an object present in the target space on the basis of the output image, an imaging conditions calculation section which calculates imaging conditions including at least one of an integration time and a light emission period of the TOF sensor on the basis of an image of the detected object, and an imaging conditions changing section which changes a configuration of the TOF sensor to the calculated imaging conditions, wherein the object detection section detects a position of the object on the basis of the image output under the changed imaging conditions.",
    "2. The object detection system according to claim 1, wherein the imaging conditions calculation section calculates the light emission period on the basis of a distance to the detected object or the specific portion of the object.",
    "3. The object detection system according to claim 1, wherein the imaging conditions further include a necessary imaging repetition count of the TOF sensor, and the image is a composite image in which a plurality of images captured at the necessary imaging repetition count are combined.",
    "4. The object detection system according to claim 1, wherein the imaging conditions further include a luminous intensity of the TOF sensor, and the imaging conditions calculation section calculates the luminous intensity on the basis of an image of the detected object.",
    "5. The object detection system according to claim 1, wherein the imaging conditions calculation section calculates the integration time on the basis of a reflected intensity of the reference light of the detected object or a specific portion of the object.",
    "6. The object detection system according to claim 5, wherein the imaging conditions calculation section calculates the integration time in consideration of a reflected intensity of external light of the detected object or the specific portion of the object.",
    "7. The object detection system according to claim 5, wherein the imaging conditions calculation section calculates the integration time in consideration of a distance to the object or the specific portion of the object.",
    "8. The object detection system according to claim 1, further comprising an imaging position/posture calculation section which calculates at least an imaging position on the basis of the image of the detected object, and a movement mechanism which changes at least a position of the TOF sensor or the object to the calculated imaging position, wherein the object detection section detects the position of the object on the basis of the image output under at least one of the changed imaging position and the changed imaging conditions.",
    "9. The object detection system according to claim 8, wherein the imaging position/posture calculation section calculates the imaging position so that the detected object or a characteristic portion of the object is captured larger in the image.",
    "10. The object detection system according to claim 8, wherein the imaging position/posture calculation section specifies a surface of an object which exerts multi-path influence on the detected object, and calculates the imaging position so that the reference light emitted by the TOF sensor is not emitted onto the surface of the object.",
    "11. The object detection system according to claim 8, wherein the movement mechanism is a robot which supports the TOF sensor or a robot which supports the object.",
    "12. The object detection system according to claim 8, wherein the object detection section further calculates an evaluation value representing a degree of similarity of the object on the basis of the output image and pre-stored reference data of the object or a characteristic portion of the object, and when the calculated evaluation value is less than a predetermined threshold, the imaging conditions calculation section calculates the imaging conditions or the imaging position/posture calculation section calculates the imaging position.",
    "13. The object detection system according to claim 12, wherein the imaging position/posture calculation section calculates at least one of the imaging position and the imaging posture so that the detected object or the characteristic portion of the object is imaged in at least one of a preset imaging position and imaging posture with respect to reference data of the object or the characteristic portion of the object.",
    "14. An object detection system, comprising: a TOF sensor which outputs an image of a target space on the basis of a phase difference between reference light emitted toward the target space and reflected light from the target space, an object detection section which detects a position of an object present in the target space on the basis of the output image, an imaging position/posture calculation section which calculates at least an imaging position of the TOF sensor on the basis of the image of the detected object, and a movement mechanism which changes at least a position of the TOF sensor or the object to the calculated imaging position, wherein the object detection section detects a position of the object on the basis of the image output at the changed imaging position."
  ],
  "description_excerpt": "The present invention relates to an object detection system, and in particular, relates to an object detection system using a TOF sensor.\n\nAs a distance measuring device which measures the distance to an object, TOF (time of flight) sensors which output distance on the basis of the time-of-flight of the light are known. TOF sensors often employ a phase difference method (a so-called “indirect method”) in which a target space is irradiated with reference light which is intensity modulated over predetermined cycles, whereby the distance to the target space is calculated based on the phase difference between the emitted reference light and the reflected light from the target space. This phase difference is obtained from the amount of received reflected light. As prior art related to such TOF sensors, the following literature is known.\n\nJapanese Unexamined Patent Publication (Kokai) No. 2012-123781 discloses that in order to estimate the position and posture of a target object with high accuracy while reducing the influence of noise in a distance image caused by multi-path reflection or the like, image features are detected from a two-dimensional image corresponding to the distance image, and the coordinates of the image features are calculated from the distance image.\n\nJapanese Unexamined Patent Publication (Kokai) No.",
  "cpc": [
    "G01S 17/36",
    "B25J 19/023",
    "G01S 17/06",
    "G01S 17/08",
    "G01S 17/88",
    "G01S 17/89",
    "G01S 17/894",
    "G01S 7/4911",
    "G01S 7/4918",
    "G06F 18/22",
    "G06K 9/6215",
    "G06T 2200/04",
    "G06T 2207/10024",
    "G06T 2207/10028",
    "G06T 2207/20081",
    "G06T 2207/20084",
    "G06T 7/70",
    "G06T 7/74",
    "G06V 10/25",
    "G06V 20/64",
    "G06V 2201/06",
    "H04N 23/54",
    "H04N 23/60",
    "H04N 23/71",
    "H04N 23/73",
    "H04N 23/74",
    "H04N 5/2253",
    "H04N 5/2351"
  ],
  "ipc": [
    "G01S 17/89",
    "G06T 7/70",
    "G06V 10/25",
    "H04N 5/225",
    "H04N 5/235"
  ],
  "assignees": [
    "Fanuc Corp"
  ],
  "inventors": [
    "Minoru Nakamura",
    "Yuuki Takahashi",
    "Atsushi Watanabe"
  ],
  "filing_date": "2020-09-23",
  "publication_date": "2022-05-10",
  "grant_date": "2022-05-10",
  "priority_date": "2019-11-25",
  "application_number": "US-202017029037-A",
  "family_id": "75784678",
  "cited_by_count": 3,
  "citations": [
    "JPH10197635A",
    "JP2011064498A",
    "JP2012123781A",
    "JP2013101045A"
  ]
}