Optical radar system with an array of photoelectric sensors

• US 4,634,272 A
• Filed: 03/25/1983
• Issued: 01/06/1987
• Est. Priority Date: 06/02/1982
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Endo, Hiroshi
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): Wallace, Linda J.
• Application Number:
  US06/478,871
• Time in Patent Office: 1,383 Days
• Field of Search: 356/4, 356/5, 356/28, 356/141, 356/152, 250/211 J, 358/213
• US Class Current: 356/5.03
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/486 Receivers

Abstract

An optical radar system includes an optical transmitter which responds to a drive signal to radiate a search light pulse into detection fields arranged in the direction in which the vehicle is moving. An optical receiver includes a plurality of arrayed photoelectric sensitive elements which receive any search light pulses reflected by objects in the detection fields. A distance measuring device determines the respective distances from the system to the objects and the corresponding directions in which the objects lie in accordance with the delay between the drive signal and the reception of the corresponding reflected search light pulses by the individual photoelectric elements.

Claims

1. A system for measuring a distance to an object, comprising:

a. first means responsive to a predetermined drive signal for transmitting a coherent pulsating light to a detection region of predetermined dimensions and orientation with respect to the system;

b. second means including means for collecting a portion of the coherent pulsating light reflected by the object in the detection region and a plurality of arrayed photo-sensitive elements each monitoring a distinct light receiving area of said detection region and receiving the collected coherent light reflected from objects therein; and

c. third means for generating and outputting the drive signal to said first means and determining the distance to the object in the detection region on the basis of the difference in time between an output timing of the drive signal and timing of reception of a received electric signal derived from each said light receiving area of said plurality of arrayed photo-sensitive elements,

said third means comprising means for sequentially processing the received electric signals from each of said plurality of photo-sensitive elements within a sequence of predetermined time periods and

means for measuring a time within each of said predetermined time periods for reception of reflected light by the photo-sensitive elements,

thereby determining a time for transit of said light pulse to an object in said light receiving area monitored by the photo-sensitive elements.

2. The system according to claim 1, wherein said third means includes means for sequentially determining the distance between the system and each object.

3. The system according to claim 2, wherein said plurality of arrayed photo-sensitive elements are aligned horizontally in a single line.

4. The system according to claim 2, wherein said plurality of arrayed photo-sensitive elements are aligned vertically.

5. The system according to claim 2, wherein said plurality of arrayed photo-sensitive elements are arranged in the form of a matrix.

6. The system according to claim 1 wherein said third means is further operable for determining an orientation of the object on the basis of said difference in time.

7. Apparatus as recited in claim 1 wherein said means for sequentially processing includes means for providing outputs of each of said plurality of photo-sensitive elements in a time-multiplexed arrangement to said means for measuring time.

8. Apparatus as recited in claim 7 wherein said means for sequentially processing further includes gating means for sequentially gating said outputs of said plurality of photo-sensitive elements onto a single line thereby to provide a concatenated sequence of signals to said means for measuring time for sequentially measuring time differences between reflected light from sequential ones of said photo-sensitive elements and a reference time corresponding to a transmission time of said pulsating light.

9. An apparatus as recited in claim 8 wherein said gating means comprises a plurality of gates having respective input terminals respectively connected for receiving output signals from said outputs of said photo-sensitive elements and having output terminals, said output terminals connected to said single line, and wide-band amplifying means connected to receive said output signals sequentially from said single line and for shaping said output signals and for providing the shaped signals to said means for measuring time.

10. An optical radar system for a vehicle comprising:

a. an optical transmitter responsive to the pulses of a drive signal to emit corresponding pulses of light;

b. means for directing the propagation of each pulse so as to cover a predetermined detection region;

c. a plurality of photo-sensitive elements, each responsive to incident pulses of light to produce sensor pulse signals;

d. means for focussing light reflected from said emitted light pulses by objects within said detection region onto said photo-sensitive elements such that said detection region is subdivided into a plurality of detection fields, the reflected light from each of said fields being focussed onto exactly one of said photo-sensitive elements; and

e. a processing unit responsive to said drive signal and said sensor signals for sequentially determining whether or not objects capable of reflecting light exist in any of said fields of said detection region and further for sequentially determining the distance and direction to detected objects on the basis of a time delay between pulses of said drive signal and corresponding pulses of said sensor signals.

11. Apparatus as recited in claim 10 wherein said processing unit comprises means for sequentially enabling passage of said sensor signals to a means for measuring a time of reception of said respective sensor signals within respective predetermined time periods thereby determining a time for transit of said light pulse to an object within said fields of said detection region to identify a distance between said object and the vehicle.

12. Apparatus for determining longitudinal distances to objects in a plurality of transverse detection areas in a zone, comprising:

transmitter means for transmiting a coherent light pulse longitudinally to said zone,

a plurality of detecting means each operable for detecting presence of an object in a corresponding one of said transverse direction areas, each of said plurality of detecting means comprising photo-sensitive means; and

distance measuring means for determining respective longitudinal distances to objects detected in corresponding detection areas,

said distance measuring means comprising means for sequentially processing the reflected signals detected by said plurality of photo-sensitive means within a sequence of predetermined corresponding time periods and

means for measuring a time within each of said predetermined time periods for reception of reflected light by the photo-sensitive means,

thereby determining a time for transit of said light pulse to an object in said detection area monitored by the photo-sensitive means.

13. Apparatus as recited in claim 12 wherein said plural photo-sensitive means are disposed in the vicinity of said transmitter means.

14. Apparatus as recited in claim 12 wherein said means for sequentially processing includes means for providing outputs of each of said plurality of photo-sensitive means in a time-multiplexed arrangement to said means for measuring time.

15. Apparatus as recited in claim 14 wherein said means for sequentially processing further includes gating means for sequentially gating said outputs of said plurality of photo-sensitive means onto a single line thereby to provide a concatenated sequence of signals to said means for measuring time for sequentially measuring time differences between reflected light from sequential ones of said photo-sensitive means and a reference time corresponding to a transmission time of said coherent light pulse.

16. An apparatus as recited in claim 15 wherein said gating means comprises a plurality of gates having respective input terminals respectively connected for receiving output signals from said outputs of said photo-sensitive means and having output terminals, said output terminals connected to said single line, and wide-band amplifying means connected to receive said output signals sequentially from said single line and for shaping said output signals and for providing the shaped signals to said means for measuring time.

17. Apparatus as recited in claim 12 wherein said distance measuring means comprises a delay measuring means for determining a time delay between transmission of said signal by said transmitter means and detection of a reflected signal by any of said plurality of detecting means to determine a distance to an object in the corresponding detection area.

18. Apparatus as recited in claim 17 wherein said delay measuring means comprises means for detecting delays between transmission of said signal and detection of a reflected signal by each of said plurality of detecting means to compute longitudinal distances to each of a plurality of objects detected in a plurality of said transverse detection areas.

19. A system for measuring a distance to an object, comprising:

a. first means responsive to a predetermined drive signal for transmitting a sequence of timed coherent light pulses to a detection region of predetermined dimensions and orientation with respect to the system;

b. second means including means for collecting a portion of the coherent light pulses reflected by the object in the detection region and a plurality of arrayed photo-sensitive elements each respectively monitoring a distinct light receiving area of said detection region and receiving the collected coherent light reflected by said object;

c. third means for generating and outputting the drive signal to said first means and determining the distance to the object in the monitored areas of said detection region on the basis of the difference in time between timing of the drive signal and timing of reception of a received electric signal derived from each of said respective arrayed photo-sensitive elements monitoring said respective light receiving areas, and

d. synchronizing means for gating each of said arrayed photo-sensitive elements for a predetermined time period in respective synchronization with said timed light pulses and for measuring a time duration within each predetermined time period, said time duration indicative of a time between transmission of said light pulse and collection of said portion of said light pulse from an object in said respective light receiving areas monitored thereby.