Misalignment processing for a vehicle radar sensor

Patent metadata

Field	Value
Publication number	US-9500742-B2
Application number	US-201214410155-A
Country	US
Kind code	B2
Filing date	Jun 28, 2012
Priority date	Jun 28, 2012
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

The present invention relates to a vehicle radar system ( 2 ) arranged to detect objects outside a vehicle ( 1 ). The radar system ( 2 ) a radar detector ( 3 ) and a processing unit ( 4 ). The processing unit ( 4 ) is arranged to obtain values for detected target angle (θ err ) and detected target Doppler velocity (v d ) relative the radar detector ( 3 ) for each detected object ( 10 a ′, 10 b ′, 10 c ′, 10 d ′, 10 e ′) during a certain time interval. If there is a zero crossing ( 14 ) for a derivative ( 13 ) of a function ( 12 ) describing the progression of detected target Doppler velocity (v d ) as a function of detected target angle (θ err ), the processing unit ( 4 ) is arranged to detect the zero crossing ( 14 ). This zero crossing ( 14 ) is indicative of a radar system misalignment (θ m ). The present invention also relates to a corresponding method.

First claim

The invention claimed is:

1. A vehicle radar system arranged to detect objects outside a vehicle, the radar system comprising a radar detector and a processing unit, the processing unit being arranged to obtain values for detected target angle (θ err ) and detected target Doppler velocity (v d ) relative to the radar detector for each of the objects during a certain time interval, the processing unit configured such that if there is a zero crossing for a function describing the progression of the detected target Doppler velocity (v d ) as a function of the detected target angle (θ err ), the processing unit is further configured to calculate the zero crossing, the zero crossing being indicative of a radar system misalignment angle (θ m ).

2. A vehicle radar system according to claim 1 , further comprising in that the function describing the progression of detected target Doppler velocity as a function of detected target angle is numerically defined such that the function describing the progression has a progression like a parabola.

3. A vehicle radar system according to claim 2 , further comprising in that the function describing the progression of detected target Doppler velocity (v d ) as a function of detected target angle (θ err ) is defined as:

v
d

=

v
h

·

(

1
-

Θ
err
2

2

)

,

where v h represents vehicle velocity.

4. A vehicle radar system according to claim 1 , further comprising the zero crossing is determined as a derivative of the function describing the progression.

5. A vehicle radar system according to claim 1 , further comprising the radar system misalignment angle (θ m ) represents the difference between the detected target angle (θ err ) and a true target angle (θ ref ), and the processing unit using the system misalignment angle (θ m ) to correct further detected values of the detected target angle (θ err ).

6. A vehicle radar system according to claim 5 , further comprising the difference between the detected target angle (θ err ) and the true target angle (θ err ), is relative to a longitudinal line extending from the vehicle.

7. A method for estimating a vehicle radar system misalignment angle (θ m ), the vehicle radar system being used for detecting objects outside a vehicle, the method comprising the steps of:
detecting a target angle (θ err ) and a target Doppler velocity (v d ) for each of the objects during a certain time interval;
calculating a function describing the progression of the detected target Doppler velocity (v d ) as a function of the detected target angle (θ err );
if there is a zero crossing for the function describing the progression, finding the zero crossing; and
using the zero crossing as an estimation of the vehicle radar system misalignment angle (θ m ).

8. A method according to claim 7 , further comprising in that the function describing the progression of the detected target Doppler velocity (v d ) as a function of the detected target angle (θ err ) is numerically defined as a progression like a parabola.

9. A method according to claim 7 , further comprising in that the function describing the progression of the detected target Doppler velocity (v d ) as a function of detected target angle (θ err ) is defined as:

v
d

=

v
h

·

(

1
-

Θ
err
2

2

)

,

where v h represents velocity of the vehicle.

10. A method according to claim 8 further comprising in that the step of finding the zero crossing comprises the step of:
calculating data Y representing a gradient of the parabola in a center between two data points according to:

Y
⁡

(

i
=

1
⁢

⁢
…
⁢

⁢
n

-
1

)

=

Vd
⁡

(

i
+
1

)

-

Vd
⁡

(
i
)

⁢

(

i
+
1

)

-

⁢

(
i
)

,

where n is the number of data points, and θ is an angle formed between a line extending from the vehicle and a line to the object detected,
modifying the ordinate X according to:

X
⁡

(

i
=

Assignees

• Poiger Walter
• Trompeter Florian
• Klotzbuecher Dirk
• Autoliv Dev

Inventors

• Poiger Walter
• Trompeter Florian
• Klotzbuecher Dirk

Classifications

• G01S2013/93271

  in the front of the vehicles · CPC title

• G01S13/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S13/46) · CPC title

• G01S7/4026 Primary

  Antenna boresight · CPC title

• G01S13/931

  of land vehicles · CPC title

• G01S13/58

  Velocity or trajectory determination systems; Sense-of-movement determination systems · CPC title