Obstacle detecting apparatus which employs a laser

• US 5,831,717 A
• Filed: 06/23/1997
• Issued: 11/03/1998
• Est. Priority Date: 12/14/1993
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ikebuchi, Kazuhiro
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): LAUFER, PINCHUS M
• Application Number:
  US08/880,997
• Time in Patent Office: 498 Days
• Field of Search: 356/5.01-5.15, 356/309, 356/3.1, 356/3.11, 356/3.12, 356/3.14, 356/4.01, 356/4.1, 340/903, 340/942, 180/169, 350/141.1
• US Class Current: 356/4.01
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes

Abstract

An obstacle detecting apparatus for ensuring that the transmitted light power is sufficient to detect an obstacle at a long distance, but yet not be harmful to human eyes. The apparatus comprises a light transmitting device for transmitting a pulsed light in a plurality of angular directions, and a light receiving device for receiving the light reflected from an object. The distance to the object is based on the time difference between transmission of the light and reception of the reflected light, and the power of the transmitted light is controlled in each angular direction such that reception intensity of the reflected light in every angular direction can be within a predetermined range.

Claims

1. An obstacle detecting apparatus comprising:

a plurality of light transmitting means, arranged in an array, for transmitting light in a plurality of angular directions;

distance detection means for detecting the presence or absence of an obstacle using reflected light, and for detecting distance to the obstacle in said plurality of angular directions based on a time difference between transmission of the light and reception of the reflected light; and

transmitted light control means for separately controlling intensities of the light transmitted by each of said plurality of light transmitting means such that a reception intensity of the reflected light in each angular direction is between a lower reception intensity limit which is greater than a threshold reception intensity and an upper reception intensity limit, and for controlling the intensities of the light transmitted by each of said plurality of light transmitting means such that the reception intensity of the reflected light in each angular direction is lower than a reception intensity of a previously-reflected light if the previously-reflected light has an intensity greater than the upper reception intensity limit.

2. An obstacle detecting apparatus according to claim 1, wherein said transmitted light control means lowers the power of the light transmitted in the angular directions located to the outside of a center of a direction of vehicle travel to less than the power of the light transmitted in the direction in which the vehicle is travelling.

3. An obstacle detecting apparatus according to claim 2, further comprising a vehicle speed sensor for detecting a speed of the vehicle, wherein the range of obstacle detection increases as vehicle speed increases.

4. An obstacle detecting apparatus comprising:

distance detection means for transmitting light in a plurality of angular directions to detect the presence or absence of an obstacle using reflected light and for detecting distance to the obstacle in said plurality of angular directions based on a time difference between transmission of the light and reception of the reflected light; and

transmitted light control means for separately controlling a power level of the light transmitted in each of said plurality of angular directions;

wherein said transmitted light control means decreases the number of light transmissions transmitted toward the obstacle when the obstacle is detected at a short distance.

5. An obstacle detecting apparatus comprising:

distance detection means for transmitting light in a plurality of angular directions to detect the presence or absence of an obstacle using reflected light and for detecting distance to the obstacle in said plurality of angular directions based on a time difference between transmission of the light and reception of the reflected light; and

transmitted light control means for separately controlling a power level of the light transmitted in each of said plurality of angular directions;

wherein said transmitted light control means reduces the power of the light transmitted in the angular directions corresponding to an area near side portions of the obstacle when the obstacle is detected at a short distance away in certain angular directions.

6. An obstacle detecting apparatus comprising:

distance detection means for transmitting light in a plurality of angular directions to detect the presence or absence of an obstacle using reflected light and for detecting a distance to the obstacle in the plurality of angular directions based on a time difference between transmission of the light and reception of the reflected light;

determination and inference means for determining whether the obstacle is a vehicle on the basis of the data obtained by said distance detection means and for inferring a position and size of said vehicle; and

transmitted light control means for reducing power of the light transmitted only in a predetermined range of the angular directions corresponding to a width of said vehicle when it is determined that the obstacle is a vehicle.

7. An obstacle detecting apparatus comprising:

distance detection means for detecting the presence or absence of an obstacle from reflected light of transmitted light and for detecting distance to the obstacle based on a time difference between transmission of the light and reception of the reflected light; and

transmitted light control means for expanding an angular width of the light transmitted toward the obstacle when reception intensity of the reflected light is equal to or greater than a predetermined value.

8. An obstacle detecting apparatus comprising:

distance detection means for transmitting light in a plurality of angular directions to detect the presence or absence of an obstacle using reflected light and for detecting distance to the obstacle in said plurality of angular directions based on a time difference between transmission of the light and reception of the reflected light; and

transmitted light control means for initially transmitting the light at a low power when detection of an obstacle is initiated, and then gradually increasing power of the transmitted light based on an intensity of the received light signal.