Methods and systems for detecting adverse road conditions using radar

Patent metadata

Field	Value
Publication number	US-12066571-B2
Application number	US-202117246831-A
Country	US
Kind code	B2
Filing date	May 3, 2021
Priority date	May 3, 2021
Publication date	Aug 20, 2024
Grant date	Aug 20, 2024

Abstract

Example embodiments relate to techniques for detecting adverse road conditions using radar. A computing device may generate a first radar representation that represents a field of view for a radar unit coupled to a vehicle and during clear weather conditions and store the first radar representation in memory. The computing device may receive radar data from the radar unit during navigation of the vehicle on a road and determine a second radar representation based on the radar data. The computing device may also perform a comparison between the first radar representation and the second radar representation and determine a road condition for the road based on the comparison. The road condition may represent a quantity of precipitation located on the road and provide control instructions to the vehicle based on the road condition for the road.

First claim

What is claimed is:

1. A method comprising:
generating, at a computing device coupled to a vehicle, a first radar representation that represents a field of view for a radar unit based on first radar data obtained by the radar unit during navigation by the vehicle on at least a first road in clear weather conditions, wherein the radar unit is coupled to an external surface of the vehicle, is rear-facing and is positioned such that the radar unit is able to detect precipitation kicked up by one or more wheels of the vehicle;
storing the first radar representation in memory;
receiving, at the computing device, second radar data from the radar unit during subsequent navigation by the vehicle on a second road;
determining, by the computing device, a second radar representation based on the radar data;
performing, by the computing device, a comparison between the first radar representation and the second radar representation, wherein the computing device obtains the first radar representation from the memory to perform the comparison;
based on the comparison, determining whether precipitation is being kicked up by one or more wheels of the vehicle and thereby determining a road condition for the second road, wherein the road condition represents a quantity of precipitation located on the second road; and
based on the road condition for the second road, adjusting, by the computing device, a constant false alarm rate (CFAR) detection threshold used when processing radar data received from a forward-facing radar unit coupled to the vehicle and a speed and following distance maintained by the vehicle when another vehicle is traveling in front of the vehicle on the second road.

2. The method of claim 1 , wherein generating the first radar representation comprises:
receiving a plurality of radar data sets from the radar unit during navigation of the vehicle in a plurality of environments;
determining an energy level for each radar data set from the plurality of radar data sets;
determining an average energy level based on a plurality of energy levels corresponding to the plurality of radar data sets; and
generating the first radar representation based on the average energy level.

3. The method of claim 2 , further comprising:
based on determining the energy level for each radar data set, removing one or more radar data sets having a given energy level that exceeds a threshold energy level, wherein the threshold energy level is based on a particular energy level associated with detection of an object; and
wherein determining the average energy level comprises:
determining the average energy level based on removing the one or more radar data sets.

4. The method of claim 1 , wherein generating the first radar representation comprises:
generating a first radar image representing range and Doppler information for the field of view of the radar unit during clear weather conditions.

5. The method of claim 4 , wherein determining the second radar representation based on the radar data comprises:
determining a second radar image representing range and Doppler information for the field of view of the radar unit based on the radar data.

6. The method of claim 5 , wherein performing the comparison between the first radar representation and the second radar representation comprises:
performing the comparison between a first energy from the first radar representation and a second energy from the second radar representation; and
based on the comparison, determining that the second energy from the second radar representation is at least a threshold energy level greater than the first energy from the first radar representation.

7. The method of claim 6 , wherein performing the comparison between the first energy from the first radar representation and the second energy from the second radar representation comprises:
filtering the first energy from the first radar representation and the second energy from the second radar representation; and
wherein determining the road condition for the second road comprises:
determining the road condition for the second road based on determining that second energy from the second radar representation is at least the threshold energy level greater than the first energy from the first radar representation.

8. The method of claim 1 , wherein the field of view of the radar unit covers a portion of a rear environment of the vehicle.

9. The method of claim 1 , wherein storing the first radar representation in memory comprises:
storing the first radar representation in local memory positioned on the vehicle.

10. The method of claim 1 , wherein providing control instructions to the vehicle comprises:
determining that the quantity of precipitation exceeds a threshold precipitation level; and
adjusting a path of the vehicle based on determining that the quantity of precipitation exceeds the threshold precipitation level.

11. The method of claim 10 , wherein adjusting the path of the vehicle comprises:
adjusting a lane of travel of the vehicle.

12. The method of claim 1 , further comprising:
modifying a map based on the road condition of the second road; and
providing the modified map to at least a remote computing device, wherein the remote computing device is configured to provide the modified map to one or more additional vehicles navigating a path that comprises the second road.

13. The method of claim 1 , wherein receiving second radar data from the radar unit during subsequent navigation by the vehicle on the second road comprises:
receiving first additional radar data from a first radar unit and second additional radar data from a second radar unit during subsequent navigation by the vehicle, wherein the first radar unit and the second radar unit are rear-facing radar units configured to measure respective portions of an environment located behind the vehicle;
determining the second radar representation based on the first additional radar data and a third radar representation determined based on the second additional radar data; and
wherein performing the comparison between the first radar representation and the second radar representation comprises:
performing a first comparison between the first radar representation and the second radar representation; and
performing a second comparison between the first radar representation and the third radar representation.

14. The method of claim 13 , wherein determining the road condition for the second road comprises:
determining the road condition for the second road based on both the first comparison and the second comparison.

15. The method of claim 14 , wherein determining the road condition for the second road based on both the first comparison and the second comparison comprises:
determining that a layer of precipitation is located on a portion of the second road positioned proximate to a road boundary; and
wherein providing control instructions to the vehicle comprises:
causing the vehicle to shift position on the second road away from the layer of precipitation that is located on the portion of the second road positioned proximate to the road boundary.

16. The method of claim 1 , further comprising:
adjusting a power level of the radar unit based on the road condition for the second road.

17. A system comprising:
a radar unit coupled to a vehicle, wherein the radar unit is rear-facing and positioned such that the radar unit is able to detect precipitation kicked up by one or more wheels of the vehicle; and
a computing device configured to:
generate a first radar r

Assignees

• Waymo Llc

Inventors

• Fina Michael

Classifications

• B60W2420/408

  Radar; Laser, e.g. lidar · CPC title

• G01S13/931

  of land vehicles · CPC title

• B60W30/18163

  Lane change; Overtaking manoeuvres · CPC title

• B60W30/09

  Taking automatic action to avoid collision, e.g. braking and steering · CPC title

• G01C21/3844

  Data obtained from position sensors only, e.g. from inertial navigation · CPC title