Inter-vehicle control apparatus and distance measurement apparatus

• US 7,496,449 B2
• Filed: 10/06/2006
• Issued: 02/24/2009
• Est. Priority Date: 12/05/2002
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Matsuoka, Keiji, Nozawa, Toyohito, Samukawa, Yoshie, Natsume, Tsutomu, Ohkata, Hiroshi, Hoashi, Yoshiaki, Teramura, Eiji
• Primary Examiner(s): To; Tuan C
• Application Number:
  US11/543,864
• Publication Number:
  US 20070032953A1
• Time in Patent Office: 872 Days
• Field of Search: 359/436, 382/154, 340/435, 340/902, 340/466, 340/465, 340/988, 340/425, 701/301, 701/96, 342/70, 342/104, 342/109, 342/107, 342/118
• US Class Current: 701/301
• 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: B60W 2554/00 Input parameters relating to objects
• CPC Class Codes: B60W 2554/802 Longitudinal distance
• CPC Class Codes: B60W 2554/804 Relative longitudinal speed
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2013/93185 Controlling the brakes
• 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 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section

Abstract

In an object recognition apparatus for a vehicle which uses intensities of reflected waves from reflecting objects to make a recognition on whether a reflecting object is a vehicle or a non-vehicle, a plurality of transmission waves are emitted to receive a plurality of reflected waves from the reflecting objects, and a decision is made as to whether or not the reflecting object producing the plurality of reflected waves is a unitary reflecting object. If the decision shows a unitary reflecting object, the highest intensity of intensities of the reflected waves from the unitary reflecting object is compared with a reference intensity to makes a decision on whether the reflecting object is a vehicle or a non-vehicle. This enables univocally making a decision for each unitary reflecting object as to whether the reflecting object is more likely to be a vehicle or to be a non-vehicle, thus improving the recognition accuracy.

Claims

1. An object recognition apparatus for a vehicle comprising:

radar means for transmitting a plurality of transmission waves throughout a predetermined angular range in a forward direction of the vehicle, receiving a reflected wave of each of the transmission waves from a reflecting object in response to the transmission, and outputting, when each of the reflected waves is received, a reception signal corresponding to an intensity of the reflected wave; and

recognition means for recognizing an object existing in the forward direction of the vehicle on the basis of a result of the transmission/reception by said radar means,

wherein the radar means includes;

distance calculation means for calculating a distance to said reflecting object in a transmission direction of the transmission wave on the basis of a time length from the transmission of the transmission wave to the reception of the reflected wave;

intensity calculation means for calculating an intensity of the reflected wave on the basis of the reception signal, and

the recognition means includes first unification means for, when the radar means receives a plurality of reflected waves in response to the transmission of the transmission waves, unifying a plurality of reflecting objects producing the plurality of reflected waves to recognize the plurality of reflecting objects as the same reflecting object provided that i) a difference between distances calculated by the distance calculation means on the basis of the plurality of reflected waves is shorter than a predetermined distance, ii) the plurality of reflected waves are produced by transmission waves transmitted close to each other from the radar means, and iii) a difference between the intensifies of the plurality of reflected waves calculated by the intensity calculation means is lower than a predetermined value.

2. The apparatus according to claim 1, wherein the intensity calculation means is adapted to classify the reflected waves into a plurality of groups according to their intensity, and when the plurality of reflected waves are classified as the same group, the first unification means is adapted to make a decision that a difference intensity between the reflected waves falls below a predetermined value.

3. The apparatus according to claim 1, wherein, when the distance calculated by the distance calculation means falls below a predetermined distance, the recognition means is adapted to exclude a corresponding reflecting object, which is not unified with another reflecting object, from the object recognition.

4. The apparatus according to claim 1, wherein, when the intensity of each of the reflected waves calculated by the intensity calculation means falls below a predetermined level and the number of reflected objects to be unified falls below a predetermined number, the recognition means excludes the corresponding reflecting object from the object recognition.

5. The apparatus according to claim 1, wherein the first unification means is adapted to increase the predetermined distance, which forms a condition on the difference between the distances calculated on the basis of the plurality of reflected waves by the distance calculation means, as the distance calculated by the distance calculation means becomes longer.

6. The apparatus according to claim 1, wherein, when the number of transmission waves intervening between two transmission waves falls below a predetermined number, the first unification means is adapted to make a decision that the transmission waves are emitted close to each other and decreases the number of transmission waves as the distance calculated by the distance calculation means increases.

7. The apparatus according to claim 1, wherein the radar means is adapted to transmit the plurality of transmission waves along a lateral direction of the vehicle, and the recognition means includes second unification means for, when the plurality of reflecting objects are unified in the first unification means and each of a distance between the plurality of reflecting objects in the lateral direction of the vehicle and a distance therebetween in an emission direction of the transmission wave is shorter than a predetermined unification decision distance, unifying the plurality of reflecting objects to recognize the plurality of reflecting objects as a unitary reflecting object.

8. The apparatus according to claim 7, wherein the second unification means is adapted to increase the unification decision distance as the distance to the reflecting object in the emission direction of the transmission wave becomes longer.

9. The apparatus according to claim 7, wherein the recognition means includes distance/shape calculation means for obtaining a distance to the unitary reflecting object produced by the second unification means and a width of the unitary reflecting object, and the distance/shape calculation means is adapted to obtain a distance to the unitary reflecting object produced by the second unification means on the basis of a distance to the unitary reflecting object having a reflected wave intensity exceeding a predetermined level in the first unification means.

10. The apparatus according to claim 9, wherein, in provided that the second unification means obtains a unitary reflecting object comprising a plurality of reflecting objects, when the reflected wave intensities of the plurality of reflecting objects are different from each other and a width of the unitary reflecting object exceeds a predetermined length, the distance/shape calculation means is adapted to exclude the reflecting object having the lowest reflected wave intensity and obtain the width of the unitary reflecting object.

11. The apparatus according to claim 9, wherein the radar means is adapted to transmit waves plural times throughout a predetermined angular range in a horizontal direction of the vehicle while changing an emission angle in a vertical direction of the vehicle, and each of the first and second unification means performs the unification of the reflecting objects to obtain a unitary reflecting object for each transmission wave emission line in the horizontal direction, and the recognition means further includes targeting means for, when the unitary reflecting objects obtained for each emission line at positions closest to each other and a difference between moving speeds thereof is below a predetermined speed difference, further unifying the unitary reflecting objects to recognize the further unified unitary reflecting object as a target.

12. The apparatus according to claim 11, wherein the moving speed of the unitary reflecting object is calculated as a relative speed in the horizontal direction and a relative speed in the transmission wave emission direction with respect to one'"'"'s vehicle, and the targeting means is adapted to set the plurality of unitary reflecting objects as a unitary target when a difference in both relative speeds of each of a plurality of unitary reflecting objects fall below a predetermined speed difference.

13. The apparatus according to claim 11, wherein, on the basis of a distance to the unitary reflecting object calculated by the distance/shape calculation means, a width of the unitary reflecting object, and a relative speed of the unitary reflecting object, the targeting means is adapted to calculate an estimated area in which the unitary reflecting object exists, at intervals at which detection is carried out in the radar means, and when another unitary reflecting object pertains to the estimated area, the targeting means is adapted to make a decision that the unitary reflecting objects exist at positions close to each other.