Radar data processing for vehicle ego-motion estimation

Patent metadata

Field	Value
Publication number	US-12248053-B2
Application number	US-202217588081-A
Country	US
Kind code	B2
Filing date	Jan 28, 2022
Priority date	Jan 29, 2021
Publication date	Mar 11, 2025
Grant date	Mar 11, 2025

Abstract

Described is a way to process radar data for a radar sensor mounted on a vehicle to generate motion spectrum data for estimating ego-motion information of the vehicle. Data samples of each of a plurality of radar return signals received at each antenna element of the radar sensor are generated for each antenna element. Respective Doppler-processed data including a plurality of data values is calculated for each Doppler bin index. In generating a set of motion spectrum data, which comprises a plurality of data elements each calculated for a respective Doppler bin index and a respective spatial bin index, data values of the Doppler-processed data calculated for the Doppler bin index are selected to calculate a covariance matrix. A spectral estimation algorithm, which uses the covariance matrix, can determine a spatial spectrum value for each spatial bin index.

First claim

What is claimed is:

1. A method, comprising:
processing radar data obtained by a radar sensor having a plurality of antenna elements and being mounted on a vehicle for generating a set of motion spectrum data for estimating ego-motion information of the vehicle, the processing comprising:
receiving the radar data as a respective plurality of data samples for each of a plurality of radar return signals received at each of the antenna elements;
processing the data samples to generate, for each of the antenna elements, respective Doppler-processed data including at least one of:
a plurality of data values each calculated for a respective range bin index of a plurality of range bin indices and for a respective Doppler bin index of a plurality of Doppler bin indices; or
a plurality of data values each calculated for a respective fast-time index of a plurality of fast-time indices and for a respective Doppler bin index of a plurality of Doppler bin indices;

generating a set of motion spectrum data comprising a plurality of data elements each calculated for a respective Doppler bin index of the plurality of Doppler bin indices and for a respective spatial bin index of a plurality of spatial bin indices each indicative of a respective angle of arrival of a radar return signal relative to an axis of the radar sensor; and
determining the ego-motion information of the vehicle based on the set of motion spectrum data;
wherein:
the generating includes performing, for each Doppler bin index of the plurality of Doppler bin indices, each of:
selecting data values of the Doppler-processed data that have been calculated for the Doppler bin index;
calculating a covariance matrix using the data values selected for the Doppler bin index; and
applying a spectral estimation algorithm which uses the covariance matrix to determine, for the Doppler bin index, a respective spatial spectrum value for each of the plurality of spatial bin indices; and

the ego-motion information of the vehicle is used by at least one of an Advance Driving Assistant System (ADAS) of the vehicle or an autonomous driving application of the vehicle to control the vehicle.

2. The method according to claim 1 , wherein:
each of the data values of the Doppler-processed data is calculated for a respective range bin index of a plurality of range bin indices and for a respective Doppler bin index of a plurality of Doppler bin indices, the data values selected for each Doppler bin index define a R×I dimensional matrix include data values calculated for R antenna elements and I range bin indices for the Doppler bin index, and the signal covariance matrix is a R×R dimensional matrix determined from the R×I dimensional matrix using a product of the R×I dimensional matrix and a conjugate transpose of the R×I dimensional matrix; or
each of the data values of the Doppler-processed data is calculated for a respective fast-time index of a plurality of fast-time indices, and a respective Doppler bin index of a plurality of Doppler bin indices, the data values selected for each Doppler bin index define a R×I dimensional matrix that include data values calculated for R antenna elements and I fast-time indices for the Doppler bin index (j), and the signal covariance matrix is a R×R dimensional matrix determined from the R×I dimensional matrix using a product of the R×I dimensional matrix and a conjugate transpose of the R×I dimensional matrix.

3. The method according to claim 1 , wherein generating the set of motion spectrum data further comprises normalizing the spatial spectrum values determined for each Doppler bin index to generate a respective plurality of normalized spatial spectrum values, each of the normalized spatial spectrum values being generated for a respective Doppler bin index of the plurality of Doppler bin indices and for a respective spatial bin index of a plurality of spatial bin indices.

4. The method according to claim 3 , wherein generating the set of motion spectrum data further comprises:
calculating, for each Doppler bin index of the plurality of Doppler bin indices, data indicative of a variance of a probability distribution of the angle of arrival of the radar return signal relative to the axis of the radar sensor among the angles of arrival indicated by the respective spatial bin indices, by using the normalized spatial spectrum values generated for the spatial bin indices as probability values for the spatial bin indices; and
determining a subset of Doppler bin indices of the plurality of Doppler bin indices for which the calculated variance is below a predetermined threshold, the value of each data element of the set of motion spectrum data being based on a respective normalized spatial spectrum value generated for a Doppler bin index in the subset of Doppler bin indices and for a spatial bin index corresponding to the data element.

5. The method according to claim 4 , wherein values of data elements of the set of motion spectrum data are generated for each Doppler bin index in the subset of Doppler bin indices by processing the plurality of normalized spatial spectrum values generated for the Doppler bin index by:
identifying a spatial bin index for which the normalized spatial spectrum value is highest among the normalized spatial spectrum values generated for the plurality of spatial bin indices;
setting the value of a data element for the identified spatial bin index to a non-zero value; and
setting the value of data elements for all other spatial bin indices to zero.

6. The method according to claim 3 , wherein values of data elements of the set of motion spectrum data are generated for each Doppler bin index in the plurality of Doppler bin indices by processing the plurality of normalized spatial spectrum values generated for the Doppler bin index by:
identifying a spatial bin index for which the normalized spatial spectrum value is highest among the normalized spatial spectrum values generated for the plurality of spatial bin indices;
setting the value of a data element for the identified spatial bin index to a non-zero value; and
setting the value of data elements for all other spatial bin indices to zero.

7. The method according to claim 1 , wherein determining the ego-motion information of the vehicle is further based on an equation of motion that relates a variable indicative of a radial velocity of a stationary object relative to the radar sensor, a variable indicative of an angular displacement of the stationary object with respect to the axis of the radar sensor, and a variable indicative of a velocity of the vehicle.

8. The method according to claim 7 , wherein the equation of motion is given by:
d =(− l y cos (θ+θ M )+ l x sin (θ+θ M ))ω+cos (θ+θ M ) v x +sin (θ+θ M ) v y

wherein:
d is indicative of a radial velocity of the stationary object,
θ is indicative of an angular displacement of the stationary target relative to the axis of the radar sensor,
θ M is indicative of a mounting angle of the radar sensor that is an angle between the axis of the radar sensor and an axis of a vehicle coordinate system of the vehicle,
l x is indicative of a mounting position of the radar sensor along an X-axis of the vehicle coordinate system, and l v is indicative of a mounting position of the radar sensor along a Y-axis of the vehicle coordinate system,
v x is indicative of an X-component of a velocity of the vehicle, and v y is indicative of a Y-component of the velocity of the vehicle,
ω is indicative of a yaw rate of the vehicle, and
the ego-motion information comprises values of v x , v y , and ω.

9. The method according to claim 8 , wherein K number of radar sensors each having a plurality of antenna elem

Assignees

• Aptiv Technologies AG

Inventors

• Lessmann Stephanie
• Doerr Wolfgang

Classifications

• G01S13/931

  of land vehicles · CPC title

• G01S2013/93274

  on the side of the vehicles · CPC title

• G01S2013/93272

  in the back of the vehicles · CPC title

• G01S2013/93271

  in the front of the vehicles · CPC title

• G01S13/87

  Combinations of radar systems, e.g. primary radar and secondary radar · CPC title