System and method for detecting intervehicle distance of two vehicles moving in the same traffic lane

• US 4,786,164 A
• Filed: 07/12/1985
• Issued: 11/22/1988
• Est. Priority Date: 07/13/1984
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kawata, Hiroshi
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US06/754,180
• Time in Patent Office: 1,229 Days
• Field of Search: 356/4, 356/5, 356/151, 356/152, 250/211.5, 180/167-169
• US Class Current: 356/5.05
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2013/9319 Controlling the accelerator
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/9323 Alternative operation using light waves
• CPC Class Codes: G01S 2013/9325 for inter-vehicle distance regulation, e.g. navigating in platoons
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 2013/9329 cooperating with reflectors or transponders

Abstract

The system and method for detecting an intervehicle distance to a preceding vehicle which is moving on the same lane as the vehicle, means for radiating and sweeping an electromagnetic wave such as a laser beam toward the moving direction of the vehicle is provided, with the confirmation of a lane on which the vehicle moves on the basis of a comparison of their sweep angles to reflectors located on both ends of a road on which the vehicle moves from a center axis of the vehicle'"'"'s movement direction, the traffic lane on which a vehicle moving in front of the vehicle moves is determined on the basis of their sweep angles of the electromagnetic wave with respect to the vehicle from the other vehicle moving in front of the vehicle to the reflectors located on both ends of the road and having the same distance to the vehicle as the other vehicle, and the intervehicle distance data is outputted upon determination that both vehicles move on the same traffic lane, a correct intervehicle distance from the vehicle to the preceding vehicle can thus be measured. In addition, the center axis is corrected according to a steering angle of the vehicle'"'"'s steering wheel.

Claims

1. A system for detecting an inter-vehicle distance between first and second vehicles travelling on a road having a plurality of traffic lanes, comprising:

(a) first means for transmitting an electromagnetic wave toward said second vehicle along a direction of forward movement of the first vehicle and sweeping the transmitted electromagnetic wave from the first vehicle forward movement direction to both predetermined left and right direction limits;

(b) second means for receiving a reflected wave from a reflecting object on which the electromagnetic wave transmitted from said first means falls;

(c) third means for calculating and storing a distance to the reflecting object on the basis of a propagation delay time between a time at which said first means transmits the wave and a time at which said second means receives the reflected wave whenever said first means sweeps the transmitted wave at a given angle;

(d) fourth means for determining on which traffic lane of a road the first vehicle moves on the basis of respective sweep angles of the electromagnetic wave transmitted by said first means and received by said second means between a center axis which accords with the first vehicle'"'"'s forward movement direction and wave reflecting objects present on both sides of the road;

(e) fifth means for determining whether the second vehicle is present on the road along a direction area toward which the first vehicle moves from among the wave reflecting objects on the basis of a change in the distance derived for each given sweep angle with respect to time;

(f) sixth means for determining a traffic lane of the road on which the second vehicle determined by said fifth means moves on the basis of sweep angles of the transmitted and reflected wave between the center axis and each reflecting object present on the corresponding side of the road, each reflecting object having the same distance as the intervehicle distance to the second vehicle; and

(g) seventh means for outputting a value of the intervehicle distance from the first vehicle to the second vehicle calculated and stored by said third means upon determination of said sixth means that the second vehicle determined by said fifth means is moving in front of the first vehicle on the same traffic lane of the road as the first vehicle.

2. The system according to claim 1, wherein said fourth means determines the traffic lane on which the first vehicle moves on the basis of magnitudes of their sweep angles of the electromagnetic wave between the center axis which accords with the forward movement direction along which the first vehicle moves and reflectors installed on both sides of the road, the reflectors being those located substantially at the same distance with respect to the first vehicle.

3. The system according to claim 1, wherein said sixth means determines the traffic lane of the road on which the second vehicle moves on the basis of magnitudes of respective sweep angles of the electromagnetic wave between the right-side and left-side reflectors located on both sides of the road at the front portion of the first vehicle derived from both predetermined left and right direction limits and having substantially the same distance as the intervehicle distance to the second vehicle and the center axis.

4. The system according to claim 1, which further comprises eighth means for detecting a steering angle of a steering wheel of the first vehicle with respect to an equilibrium position of the steering wheel and wherein the center axis is corrected according to the steering angle detected by said eighth means.

5. The system according to claim 3, wherein said sixth means determines whether the second vehicle moving in front of the first vehicle is moving on the same traffic lane as the first vehicle depending on whether a ratio of both sweep angle magnitudes derived from said fourth means is substantially equal to a ratio of both sweep angle magnitudes derived from said sixth means.

6. The system according to claim 2, wherein said sixth means determines the traffic lane of the road on which the second vehicle moves on the basis of magnitude of respective sweep angles of the electromagnetic wave between the right-side and left-side reflectors located on both sides of the road at the front portion of the first vehicle derived from both predetermined left and right direction limits and having substantially the same distance as the intervehicle distance to the second vehicle and the center axis.

7. A method for detecting an intervehicle distance between first and second vehicles travelling on a road having a plurality of traffic lanes, comprising the steps of:

(a) transmitting an electromagnetic wave toward a direction along which the first vehicle moves;

(b) sweeping the transmitted electromagnetic wave from a vehicle forward movement direction to both predetermined left and right directions;

(c) receiving a reflected wave from a reflecting object on which the transmitted electromagnetic wave falls;

(d) calculating and storing a distance to the reflecting object on the basis of a propagation delay time between times at which the wave is transmitted and at which the reflected wave is received whenever the transmitted wave is swept at a given angle;

(e) determining on which traffic lane of a road the first vehicle moves on the basis of respective sweep angles of the transmitted and reflected electromagnetic wave between a center axis which accords with the vehicle forward movement direction and wave reflecting objects present on both sides of the road;

(f) determining whether the second vehicle is present on the road along the direction toward which the first vehicle moves from among the wave reflecting objects on the basis of a change in the distance derived for each given sweep angle with respect to time;

(g) determining a traffic lane of the road on which the second vehicle determined in said step (f) moves on the basis of their sweep angles of the transmitted and reflected wave between the center axis and each reflecting object present on the corresponding side of the road, each reflecting object having substantially the same distance as the intervehicle distance to the other vehicle; and

(h) outputting a value of the intervehicle distance from the first vehicle to the reflecting object calculated and stored in said step (d) when the reflecting object is the second vehicle which is moving in front of the first vehicle on the same traffic lane of the road as the first vehicle.