Systems and methods for object detection using beam widening optics

• US 5,313,262 A
• Filed: 09/30/1992
• Issued: 05/17/1994
• Est. Priority Date: 09/30/1992
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Leonard, Carl D.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US07/953,250
• Time in Patent Office: 594 Days
• Field of Search: 180/169, 356/1, 356/4, 356/5, 356/141, 356/152
• US Class Current: 356/4.01
• CPC Class Codes: B60T 1/16 by increasing air resistance, e.g. flaps
• CPC Class Codes: B60T 7/22 initiated by contact of vehicle, e.g. bumper, with an external object, e.g. another vehicle , or by means of contactless obstacle detectors mounted on the vehicle
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4814 of transmitters alone

Abstract

In exemplary embodiments, a diffraction grating is placed in the beam path of the generated light source. The grating expands the beam'"'"'s field of view by distributing the transmitted radiation into plural sub-fields. Sub-fields associated with distant objects are set to a greater intensity to ensure reflection of the sub-fields back to the receiver. Sub-fields directed to closer objects have a lesser intensity to avoid detection of false objects.

Claims

1. System for detecting an object comprising:

means for generating a beam of light;

means for separating said beam of light into a plurality of sub-fields, each of said sub-fields being transmitted with a different intensity, each different intensity being proportional to a distance from said light beam generating means to an expected location of said object; and

means for receiving portions of at least one of said sub-fields to detect said object.

2. The system of claim 1 wherein each of said sub-fields is directed at an angle which is proportional to the expected location of one of a plurality of objects along a path.

3. The system of claim 1, wherein said object is detected for controlling a vehicle by generating said beam of light from said vehicle, said receiving means being located on said vehicle for receiving portions of at least some of said transmitted sub-fields of different intensity to control the vehicle.

4. The system of claim 3 further including means, responsive to said receiving means, for guiding said vehicle based on each of said received portions.

5. The system of claim 4 wherein said separating means is a grating for separating said beam of light into at least three diffracted sub-fields which are each directed at a different angle with respect to said vehicle, each different angle being proportional to an expected location of one of a plurality of objects along a path of said vehicle.

6. The system of claim 5 wherein said objects located along the path of said vehicle are retro-reflectors for reflecting said diffracted sub-fields toward said receiving means.

7. The system of claim 6 wherein each of said objects are spaced a predetermined distance from one another along said path.

8. The system of claim 7 wherein said diffracted sub-field of light with a first intensity is directed toward a first one of said objects, and said diffracted sub-field with a second intensity greater than said first intensity is directed toward a second one of said objects located a greater distance from said generating means than said first one of said objects.

9. The system of claim 5 wherein said grating is a transmission ruled grating.

10. The system of claim 5 wherein said grating is a low frequency holographic grating.

11. The system of claim 5 wherein said light generating means is a diode laser.

12. The system of claim 1, wherein said light beam generating means is a single laser diode.

13. A system for controlling a moving vehicle comprising:

means for generating a beam of light from said vehicle;

means for separating said beam of light into plural transmitted sub-fields, a first of said transmitted sub-fields being oriented toward an expected location of a first object while a second of said transmitted sub-fields is oriented toward an expected location of a second object wherein said first and second sub-fields are transmitted with different intensities of light, each of said different intensities being proportional to different expected distances from said light beam generating means to said first and second objects;

means on said vehicle for simultaneously receiving reflected portions of at least two of the transmitted sub-fields; and

means, responsive to said receiving means, for controlling said vehicle position relative to said first and second objects.

14. The system of claim 13, wherein said generating means is a diode laser, said separating means is a diffraction grating, and wherein each of said plural transmitted sub-fields is transmitted with a different intensity.

15. The system of claim 14 further including at least three markers spaced along a path of said vehicle, a first one of said markers being a first distance from said vehicle for reflecting a first one of said sub-fields with a first intensity, and a second one of said markers being at a second distance from said vehicle for reflecting one of said sub-fields with a second intensity greater than said first intensity, said first distance being less than said second distance.

16. The system of claim 15 wherein each of said markers is spaced a predetermined distance from an adjacent one of said markers.

17. The system of claim 13, wherein said light beam generating means is a single laser diode.

18. A method of detecting an object, said method comprising the steps of:

generating a beam of light;

separating said light beam into plural sub-fields and transmitting the plural sub-fields of view using said beam, each sub-field being of a different intensity, each different intensity being proportional to a different expected distance to said object; and

receiving portions of said plural sub-fields for detecting said object.

19. The method of claim 18 wherein a portion of said object is detected for controlling a moving vehicle, said method comprising the steps of:

detecting said portions of said sub-fields which are reflected from a plurality of markers located along a vehicle path and controlling said vehicle based on said detected reflected sub-fields.

20. The method of claim 19 wherein said step of separating includes separating said beam into at least three sub-fields.

21. The method of claim 20 wherein a sub-field with a first intensity is directed to a first one of said markers and a sub-field with a second intensity greater than said first intensity is directed to a second one of said markers.

22. The method of claim 21 wherein a sub-field of a first intensity is reflected by one of said markers at a first distance from said vehicle and a sub-field of a second intensity greater than said first intensity is reflected by one of said markers at a second distance from said vehicle, wherein said second distance is greater than said first distance.

23. The method of claim 18, wherein said step of generating a beam of light is performed using a single laser diode.