System for automatically detecting presence or absence of a preceding vehicle and method therefor

• US 4,716,298 A
• Filed: 05/30/1985
• Issued: 12/29/1987
• Est. Priority Date: 06/01/1984
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Etoh, Yoshiyuki
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Cooper, Crystal D.
• Application Number:
  US06/739,152
• Time in Patent Office: 943 Days
• Field of Search: 356/5, 180/169, 180/167, 250/561, 250/221, 250/222.1
• US Class Current: 250/559.38
• CPC Class Codes: G01S 17/931 of land vehicles

Abstract

A system for detecting the presence or absence of a vehicle in front of a subject vehicle and method therefor, wherein a plurality of wave transmitters transmit distance measuring media such as laser beams or electromagnetic waves over a front detection area toward which the distance measuring media are transmitted in mutually different directions and through respectively predetermined angles with respect to a longitudinal axis of the subject vehicle. In the detecting system and method, the presence of the preceding vehicle is determined on the basis of propagation delay between the times at which at least one of the waves is transmitted and at which the reflected waves are received. The lateral progress of the vehicle in front of the subject vehicle from detection area to detection area is monitored to maintain contact with the detected vehicle even around curves or during steering adjustments.

Claims

1. A system for detecting the presence or absence of a vehicle present in a detection area of a subject vehicle on which the system is mounted, comprising:

(a) first means for transmitting measuring media over the detection area toward which the measuring media are simultaneously transmitted in mutually different directions and through respectively predetermined angles with respect to a longitudinal axis of the subject vehicle;

(b) second means for outputting a first signal upon receipt of any one of the measuring media from the first means reflected by an object which is present in the detection area the subject vehicle, said first signal indicating the direction of propagation of the reflected measuring media toward the object, for calculating a distance between the subject vehicle and the object on the basis of the propagation delay between transmission of the measuring media from the first means and reception of the reflected wave from the object and outputting a second signal indicating the calculated distance between the subject vehicle and the object; and

(c) third means for recognizing whether the object is a vehicle present in the detection area on the basis of the first and second signals outputted from said second means.

2. The system according to claim 1, wherein said third means recognizes the object as the vehicle present in the detection area if both the distance and direction to the object are within predetermined limits of distance and direction for a vehicle previously present in the detection area.

6. The system according to claim 1, wherein the measuring media comprise a plurality of laser beams.

7. The system according to claim 1, wherein said first means is located substantially at a center position of a front surface of the subject vehicle and directed toward the detection area in front of the vehicle.

8. The system according to claim 7, wherein said first means comprises three laser beam transmitters, a first transmitter for transmitting a first laser beam having a predetermined spread angle oriented symmetrically about the longitudinal axis of the subject vehicle, second and third transmitters for transmitting second and third laser beams, each of said second and third laser beams having predetermined spread angles equal to said first laser beam spread angle, said second and third laser beams aligned symmetrically about either side of said first laser beam wherein adjacent spread angles overlap.

3. A system for detecting the presence or absence of a vehicle in front of a subject vehicle on which the system is mounted, comprising:

(a) a plurality of transmitters directed toward a front detection area of the subject vehicle for transmitting measuring media so as to cover a plurality of partially overlapping direction areas forward of the subject vehicle;

(b) first means for detecting an angular position of a steering wheel of the subject vehicle and outputting a first signal indicative thereof;

(c) second means for outputting a second signal upon receipt of any measuring media from any of the detection areas reflected by an object present in front of the subject vehicle, said second signal indicating in which detection area or areas the object lies, for calculating a distance between the subject vehicle and the object on the basis of a propagation delay between transmission of the measuring media and reception of the reflected measuring media and for outputting a third signal indicating the calculated distance between the subject vehicle and the object; and

(d) third means for recognizing whether the detected object is a vehicle in front of the subject vehicle on the basis of the first, second and third signals outputted from said first and second means.

4. The system according to claim 3, wherein said third means recognizes the detected object as the vehicle in front of the subject vehicle if (1) values of the second and third signals for the detected object are within predetermined limits of corresponding values for a vehicle previously in front of the subject vehicle and (2) a present value of the first signal derived from the first means statisfies conditions specified by said second and third signal values.

5. A method for detecting the presence or absence of a vehicle in front of a subject vehicle, comprising the steps of:

(a) transmitting measuring media over a front detection area toward which the measuring media are simultaneously transmitted in mutually different directions and through respectively predetermined angles with respect to a longitudinal axis of the subject vehicle

(b) outputting a first signal upon receipt of at least one of the measuring media transmitted in step a) and reflected by an object, said first signal indicating a direction of propagation of the reflected measuring media;

(c) calculating a distance between the subject vehicle and the object on the basis of a propagation delay between transmission of the measuring media and reception of the reflected measuring media;

(d) outputting a second signal indicating the distance calculated in step (c); and

(e) determining whether the object is the vehicle in the front detection area on the basis of the first and second signals outputted in steps (b) and (d).