Off-Axis Angle Estimation Method and Apparatus Using the Same

• US 20080012752A1
• Filed: 11/12/2004
• Published: 01/17/2008
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Okamura, Atsushi, Hirai, Toshiyuki, Wakayama, Toshio, Hara, Rokuzou
• Granted Patent: US 7,545,313 B2
• Time in Patent Office: Days
• US Class Current: 342/165
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/9325 for inter-vehicle distance regulation, e.g. navigating in platoons
• CPC Class Codes: G01S 2013/9329 cooperating with reflectors or transponders
• CPC Class Codes: G01S 7/4026 Antenna boresight
• CPC Class Codes: G01S 7/403 in azimuth, i.e. in the horizontal plane
• CPC Class Codes: G01S 7/4091 during normal radar operation

Abstract

Without using a traveling velocity of a vehicular object mounted with a radar device, an off-axis angle which is an offset angle between a reference direction of the radar device and a traveling direction of the vehicular object is estimated. An off-axis angle estimation method for estimating an off-axis angle (φ) of a radar device (1) mounted on the vehicular object having a predetermined traveling direction includes that, from among reflection points of which a relative-velocity component (q) along the line of radar sight and an azimuthal angle (θ) are detected by the radar device (1), a plurality of reflection points of which the relative-velocity components in the traveling direction of the vehicular object being approximately equal to one another is selected without using the traveling velocity of the vehicular object; and based on the relative-velocity components along the line of radar sight, and on the azimuthal angles, of the plurality of reflection points having been selected, the off-axis angle (φ) is autonomously calculated solely from the observed values based on radar waves.

Claims

1. An off-axis angle estimation method for estimating an off-axis angle of a radar device mounted on a vehicular object, the off-axis angle estimation method:

with there being reflection points whose relative-velocity components along the line of radar sight and whose azimuthal angles are detected by said radar device, calculating the off-axis angle based on the relative-velocity components along the line of radar sight, and on the azimuthal angles, of a plurality of reflection points whose relative-velocity components in the traveling direction of the vehicular object are approximately equal to one another.

2. The off-axis angle estimation method as set forth in claim 1, wherein

from among the reflection points whose relative-velocity components along the line of radar sight and whose azimuthal angles are detected by said radar device, a plurality of reflection points is selected so that the relative-velocity components in the traveling direction of the vehicular object are approximately equal to one another, to calculate the off-axis angle based on the relative-velocity components along the line of radar sight, and on the azimuthal angles, of the selected reflection points.

3. The off-axis angle estimation method as set forth in claim 2, wherein:

the relative-velocity component, along the line of radar sight, of any one of the reflection points detected by the radar device is specified as a reference velocity;

a plurality of reflection points for which, in a range of values having a predetermined width centering on the reference velocity, the relative-velocity components along the line of radar sight are included is selected; and

the off-axis angle is calculated based on the relative-velocity components along the line of radar sight and on the azimuthal angles of the selected reflection points.

4. The off-axis angle estimation method as set forth in claim 3, wherein

among the reflection points detected by the radar device, a median value in a distribution of the relative-velocity components along the line of radar sight is specified as the reference velocity.

5. The off-axis angle estimation method as set forth in claim 3, wherein

among the reflection points detected by the radar device, a maximum value in a distribution of the relative-velocity components along the line of radar sight is specified as the reference velocity.

6. The off-axis angle estimation method as set forth in claim 3, wherein

in a distribution of the relative-velocity components, along the line of radar sight, of the reflection points detected by the radar device, a relative-velocity range in which the reflection-point frequency is a predetermined number or greater is found, a plurality of the reflection points whose relative-velocity components along the line of radar sight are included in the range of values is selected.

7. The off-axis angle estimation method as set forth in claim 2, wherein

from among reflection points detected in a predetermined time interval by the radar device, a plurality of the reflection points is selected so that the relative-velocity components in the traveling direction of the vehicular object are approximately equal to one another.

8. The off-axis angle estimation method as set forth in claim 2, wherein

among reflection points detected by the radar device, a plurality of the reflection points is selected so that the radar-device off-axis angle being calculated based on the relative velocities along the line of vehicular-object radar-sight and on the azimuthal angles of the reflection points is distributed within a predetermined range of values.

10. For the off-axis angle estimation method as set forth in claim 1,

an off-axis angle estimation apparatus, comprising a reflection-point selection means for, from among the reflection points whose relative-velocity components along the line of radar sight and whose azimuthal angles are detected by said radar device, selecting a plurality of reflection points so that the relative-velocity components in the traveling direction of the vehicular object are approximately equal to one another;

and

an off-axis angle calculation means for calculating the off-axis angle of said radar device based on the relative-velocity components along the line of radar sight and on the azimuthal angles of the plurality of reflection points having been selected by said reflection-point selection means.

11. The off-axis angle estimation apparatus as set forth in claim 10, wherein

the reflection-point selection means specifies the relative-velocity component, along the line of radar sight, of any one of the reflection points detected by the radar device, as a reference velocity;

and selects a plurality of reflection points for which, in a range of values having a predetermined width centering on the reference velocity, the relative-velocity components along the line of radar sight are included.

12. The off-axis angle estimation apparatus as set forth in claim 11, wherein

the reflection-point selection means, among the reflection points detected by the radar device, specifies a median value in a distribution of the relative-velocity components along the line of radar sight as the reference velocity.

13. The off-axis angle estimation apparatus as set forth in claim 11, wherein

the reflection-point selection means, among the reflection points detected by the radar device, specifies a maximum value in a distribution of the relative-velocity components along the line of radar sight as the reference velocity.

14. The off-axis angle estimation apparatus as set forth in claim 11, wherein

the reflection-point selection means finds, in a distribution of the relative-velocity components, along the line of radar sight, of the reflection points detected by the radar device, a relative-velocity range in which the reflection-point frequency is a predetermined number or greater;

and selects a plurality of the reflection points whose relative-velocity components along the line of radar sight are included in the range of values.

15. The off-axis angle estimation apparatus as set forth in claim 11, wherein

the reflection-point selection means, from among the reflection points whose relative-velocity components along the line of radar sight and whose azimuthal angles are detected by said radar device, selects a first reflection point, a second reflection point, and a third reflection point, so that the relative-velocity components in the traveling direction of the vehicular object are approximately equal to each other;

the off-axis angle calculation means calculates not only a first off-axis angle based on the relative-velocity components along the line of radar sight and on the azimuthal angles of the first and the second reflection points, but also a second off-axis angle based on the relative-velocity components along the line of radar sight and on the azimuthal angles of either the first or the second reflection point and the third reflection point; and

in addition,

an off-axis angle true-value estimation means for estimating a true value of the off-axis angle of said radar device based on the first and the second off-axis angles having been calculated by said off-axis angle calculation means.

16. The off-axis angle estimation apparatus as set forth in claim 11, wherein

the reflection-point selection means specifies the relative-velocity component, along the line of radar sight, of any one of the reflection points detected by the radar device, as a first reference velocity and a second, different reference velocity, and selects respective pluralities of reflection points for which, in a range of values having a predetermined width centering on the first and the second reference velocities;

the off-axis angle calculation means calculates a first off-axis angle based on the relative-velocity components along the line of radar sight and on the azimuthal angles of the plurality of reflection points having been selected from a range of values centering on the first reference velocity, and also a second off-axis angle based on the relative-velocity components along the line of radar sight and on the azimuthal angles of the plurality of reflection points having been selected from a range of values centering on the second reference velocity; and

, the apparatus comprises

an off-axis angle true-value estimation means for estimating a true value of the off-axis angle of said radar device based on the first and the second off-axis angles having been calculated by said off-axis angle calculation means.

17. The off-axis angle estimation apparatus as set forth in claim 10, wherein

the reflection-point selection means, from among reflection points detected in a predetermined time interval by the radar device, a plurality of the reflection points is selected so that the relative-velocity components in the traveling direction of the vehicular object are approximately equal to one another.

18. The off-axis angle estimation apparatus as set forth in claim 10, wherein:

the reflection-point selection means, at a first time-interval and a second time-interval both predetermined for a time duration, from among the reflection points detected by the radar device having the relative-velocity components and azimuthal angles, selects a plurality of the reflection points so that the relative-velocity components in the traveling direction of the vehicular object are approximately equal to one another;

the off-axis angle calculation means, based on the relative-velocity components along the line of radar sight and on the azimuthal angles of the plurality of reflection points having been selected by said reflection-point selection means, calculates an off-axis angle for the first time-interval and an off-axis angle for the second time-interval; and

, the apparatus comprises

an off-axis angle true-value estimation means for estimating a true value of the off-axis angle based on the off-axis angle having been calculated for the first time-interval and the off-axis angle having been calculated for the second time-interval.

9. An off-axis angle estimation apparatus for estimating an off-axis angle of a radar device mounted on a vehicular object,

with there being reflection points whose relative-velocity components along the line of radar sight and whose azimuthal angles are detected by said radar device;

the off-axis angle estimation apparatus, comprising an off-axis angle calculation means for calculating the off-axis angle based on the relative-velocity components along the line of radar sight, and on the azimuthal angles, of a plurality of reflection points whose relative-velocity components in the traveling direction of the vehicular object are approximately equal to one another.

19. An off-axis angle estimation apparatus for estimating an off-axis angle of a radar device mounted on a vehicular object, comprising:

an off-axis angle calculation means for calculating the off-axis angle based on the relative-velocity components along the line of radar sight, and on azimuthal angles, of reflection points having been detected by said radar device;

a reflection-point selection means for selecting a plurality of the reflection points used for calculating the off-axis angle in a case that the off-axis angle having been calculated by said off-axis angle calculation means is included within a predetermined range of values; and

an off-axis angle true-value estimation means for estimating a true value of the off-axis angle of said radar device from the off-axis angle having been calculated by applying the plurality of the reflection points selected by said reflection-point selection means.