Laser area sensor

• US 7,760,336 B2
• Filed: 10/23/2008
• Issued: 07/20/2010
• Est. Priority Date: 10/26/2007
• Status: Active Grant

• Current Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Original Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Inventors: Iwasawa, Masashi
• Primary Examiner(s): Alsomiri; Isam
• Application Number:
  US12/289,245
• Publication Number:
  US 20090109421A1
• Time in Patent Office: 635 Days
• Field of Search: 356/4.01, 356/4.07, 356/5.01
• US Class Current: 356/5.01
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4808 Evaluating distance, position or velocity data
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G01S 7/4876 by removing unwanted signals G01S7/495 takes precedence
• CPC Class Codes: G08B 13/181 using active radiation detection systems

Abstract

One embodiment includes: A laser range finder that obtains a distance to an object and a light-reception level of reflected light: a scanning mechanism that changes the measurement direction; a data acquiring portion that periodically performs measurement while changing the measurement direction; a data correcting portion that removes distance information of a portion corresponding to a discontinuous change and corrects light-reception level information of a portion that does not correspond to the discontinuous change after the obtained distance information and light-reception level information are compared with distance information and light-reception level information of preceding and succeeding measurement periods in each direction; a human body judging portion that extracts a portion that is presumed to correspond to a human body, and judges whether or not the extracted portion matches a human body based on a time-series moving status of the extracted portion; and an alert output control portion.

Claims

1. A laser area sensor, comprising:

a first laser range finder that emits pulsed laser light, measures a period of time for light reflected by at least one object that is present in a laser light emitting direction to return thereby to obtain distance information to the object and light-reception level information of the reflected light;

a scanning mechanism portion that changes a measurement direction of the first laser range finder;

an information acquiring portion that defines a detection area and acquires distance information and light-reception level information in each measurement direction in the detection area in a time-series manner, by the first laser range finder periodically performing measurement while the scanning mechanism portion changes the measurement direction;

a first information correcting portion that, if there is a discontinuous change exceeding a predetermined amount when the distance information and light-reception level information acquired by the information acquiring portion in each measurement direction are compared with distance information and light-reception level information of preceding and succeeding measurement periods of the measurement period, removes distance information corresponding to the discontinuous change in the measurement period in the measurement direction and corrects light-reception level information of a portion that does not correspond to the discontinuous change;

a human body judging portion that extracts a portion that is presumed to correspond to a human body, from the distance information corrected by the first information correcting portion, and judges whether or not the extracted portion matches a human body based on a time-series moving status of the extracted portion; and

a human body detection signal output portion that outputs a human body detection signal if the human body judging portion judges that a human body is present.

2. A laser area sensor, comprising:

a first laser range finder that emits pulsed laser light, measures a period of time for light reflected by at least one object that is present in a laser light emitting direction to return thereby to obtain distance information to the object and light-reception level information of the reflected light;

a scanning mechanism portion that changes a measurement direction of the first laser range finder;

an information acquiring portion that defines a detection area and acquires distance information and light-reception level information in each measurement direction in the detection area in a time-series manner, by the first laser range finder periodically performing measurement while the scanning mechanism portion changes the measurement direction;

an information correcting portion that, if there is a discontinuous change exceeding a predetermined amount when the distance information and light-reception level information acquired by the information acquiring portion in each measurement period are compared with distance information and light-reception level information of measurement directions adjacent to the measurement direction, removes distance information corresponding to the discontinuous change in the measurement direction in the measurement period;

a human body judging portion that extracts a portion that is presumed to correspond to a human body, from the distance information corrected by the information correcting portion, and judges whether or not the extracted portion matches a human body based on a time-series moving status of the extracted portion; and

a human body detection signal output portion that outputs a human body detection signal if the human body judging portion judges that a human body is present.

3. A laser area sensor, comprising:

a first laser range finder that emits pulsed laser light, measures a period of time for light reflected by at least one object that is present in a laser light emitting direction to return thereby to obtain distance information to the object and light-reception level information of the reflected light;

a scanning mechanism portion that changes a measurement direction of the first laser range finder;

an information acquiring portion that defines a detection area and acquires distance information and light-reception level information in each measurement direction in the detection area in a time-series manner, by the first laser range finder periodically performing measurement while the scanning mechanism portion changes the measurement direction;

a first information correcting portion that, if there is a discontinuous change exceeding a predetermined amount when the distance information and light-reception level information acquired by the information acquiring portion in each measurement direction are compared with distance information and light-reception level information of preceding and succeeding measurement periods of the measurement period, removes distance information corresponding to the discontinuous change in the measurement period in the measurement direction and corrects light-reception level information of a portion that does not correspond to the discontinuous change;

a second information correcting portion that, if there is a discontinuous change exceeding a predetermined amount when the distance information and light-reception level information acquired by the information acquiring portion in each measurement period are compared with distance information and light-reception level information of measurement directions adjacent to the measurement direction, removes distance information corresponding to the discontinuous change in the measurement direction in the measurement period;

a human body judging portion that extracts a portion that is presumed to correspond to a human body, from the distance information corrected by the first information correcting portion and the second information correcting portion, and judges whether or not the extracted portion matches a human body based on a time-series moving status of the extracted portion; and

a human body detection signal output portion that outputs a human body detection signal if the human body judging portion judges that a human body is present.

4. A laser area sensor, comprising:

a laser range finder that emits pulsed laser light, measures a period of time for light reflected by at least one object that is present in a laser light emitting direction to return thereby to obtain distance information to the object and light-reception level information of the reflected light and time width information along the time axis of the reflected light;

a scanning mechanism portion that changes a measurement direction of the laser range finder;

an information acquiring portion that defines a detection area and acquires distance information, light-reception level information and time width information in each measurement direction in the detection area in a time-series manner, by the laser range finder periodically performing measurement while the scanning mechanism portion changes the measurement direction;

an information correcting portion that performs correction with a first information correcting function that, if there is a discontinuous change exceeding a predetermined amount when the distance information and light-reception level information acquired by the information acquiring portion in each measurement period are compared with distance information and light-reception level information of measurement directions adjacent to the measurement direction, removes distance information corresponding to the discontinuous change in the measurement direction in the measurement period, and with a second information correcting function that, when a measurement direction range in which an amount of change between adjacent measurement directions all falls within a predetermined range is referred to as a detection angle width when the distance information, light-reception level information and time width information acquired by the information acquiring portion in each measurement period are compared with distance information, light-reception level information and time width information of a plurality of measurement directions adjacent to the measurement direction, removes specific distance information if light-reception level information, time width information and detection angle width that correspond to the specific distance information in the measurement direction satisfies a predetermined relationship;

a human body judging portion that extracts a portion that is presumed to correspond to a human body, from the distance information corrected by the information correcting portion, and judges whether or not the extracted portion matches a human body based on a time-series moving status of the extracted portion; and

a human body detection signal output portion that outputs a human body detection signal if the human body judging portion judges that a human body is present.

5. The laser area sensor according to claim 4,

wherein the information correcting portion also performs correction with a third information correcting function that, if there is a discontinuous change exceeding a predetermined amount when the distance information and light-reception level information acquired by the information acquiring portion in each measurement direction are compared with distance information and light-reception level information of preceding and succeeding measurement periods of the measurement period, removes distance information corresponding to the discontinuous change in the measurement period in the measurement direction and corrects light-reception level information of a portion that does not correspond to the discontinuous change.

6. The laser area sensor according to claim 5,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if time width information corresponding to the specific distance information is not less than a predetermined time width.

7. The laser area sensor according to claim 5,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if a detection angle width corresponding to the specific distance information is not less than a predetermined angle width.

8. The laser area sensor according to claim 5,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if time width information corresponding to the specific distance information is not less than a predetermined time width and a detection angle width corresponding to the specific distance information is not less than a predetermined angle width.

9. The laser area sensor according to claim 5,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if the ratio between time width information corresponding to the specific distance information and detection angle width corresponding to the specific distance information is not less than a predetermined ratio.

10. The laser area sensor according to claim 4,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if time width information corresponding to the specific distance information is not less than a predetermined time width.

11. The laser area sensor according to claim 10,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period only when the average of light-reception level information in the detection angle width corresponding to the specific distance information is not greater than a predetermined value.

12. The laser area sensor according to claim 4,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if a detection angle width corresponding to the specific distance information is not less than a predetermined angle width.

13. The laser area sensor according to claim 4,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if time width information corresponding to the specific distance information is not less than a predetermined time width and a detection angle width corresponding to the specific distance information is not less than a predetermined angle width.

14. The laser area sensor according to claim 4,

wherein the second information correcting function of the information correcting portion removes the specific distance information in the measurement direction in the measurement period if the ratio between time width information corresponding to the specific distance information and detection angle width corresponding to the specific distance information is not less than a predetermined ratio.

15. A laser area sensor, comprising:

a laser range finder that emits pulsed laser light, measures a period of time for light reflected by at least one object that is present in a laser light emitting direction to return thereby to obtain distance information to the object and light-reception level time integration information in which the light-reception level of the reflected light is time-integrated;

a scanning mechanism portion that changes a measurement direction of the laser range finder;

an information acquiring portion that defines a detection area and acquires distance information and light-reception level time integration information in each measurement direction in the detection area in a time-series manner, by the laser range finder periodically performing measurement while the scanning mechanism portion changes the measurement direction;

an information correcting portion that, when a measurement direction range in which an amount of change between adjacent measurement directions all falls within a predetermined range is referred to as a detection angle width when the distance information and light-reception level time integration information acquired by the information acquiring portion in each measurement period are compared with distance information and light-reception level time integration information of a plurality of measurement directions adjacent to the measurement direction, removes first distance information of the measurement period if first light-reception level time integration information and a first detection angle width that correspond to the first distance information of the measurement direction satisfies a predetermined relationship;

a human body judging portion that extracts a portion that is presumed to correspond to a human body, from the distance information corrected by the information correcting portion, and judges whether or not the extracted portion matches a human body based on a time-series moving status of the extracted portion; and

a human body detection signal output portion that outputs a human body detection signal if the human body judging portion judges that a human body is present.

16. The laser area sensor according to claim 15,

wherein the information correcting portion removes the first distance information of the measurement period if the first detection angle width is not less than a predetermined angle width.

17. The laser area sensor according to claim 15,

wherein the information correcting portion removes the first distance information of the measurement period if the first detection angle width is not less than a predetermined angle width and other distance information that includes at least one of a plurality of measurement directions included in the first detection angle width as a corresponding detection angle width exists further away.

18. The laser area sensor according to claim 15,

wherein the information correcting portion removes the first distance information of the measurement period if a first average of the first detection angle width of the first light-reception level time integration information is greater than an average of respective detection angle widths or an average of all detection angle widths of light-reception level time integration information corresponding to other distance information that includes at least one of a plurality of measurement directions included in the first detection angle width as a corresponding detection angle width by a predetermined amount or more.

19. The laser area sensor according to claim 15,

wherein the information correcting portion removes the first distance information of the measurement period if the first detection angle width is greater than respective detection angle widths corresponding to other distance information that includes at least one of a plurality of measurement directions included in the first detection angle width as a corresponding detection angle width by a predetermined amount or more.

20. The laser area sensor according to claim 15,

wherein the information correcting portion removes the first distance information of the measurement period if a first average of the first detection angle width of the first light-reception level time integration information is greater than an average of respective detection angle widths or an average of all detection angle widths of light-reception level time integration information corresponding to other distance information that includes at least one of a plurality of measurement directions included in the first detection angle width as a corresponding detection angle width by a predetermined amount or more, and the first detection angle width is greater than respective detection angle widths corresponding to other distance information that includes at least one of a plurality of measurement directions included in the first detection angle width as a corresponding detection angle width by a predetermined amount or more.