Method for detecting a wet road

• US 9,272,676 B2
• Filed: 12/02/2011
• Issued: 03/01/2016
• Est. Priority Date: 12/14/2010
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Heger, Thomas, Helmle, Michael
• Primary Examiner(s): Dager, Jonathan M
• Application Number:
  US13/993,974
• Publication Number:
  US 20130332028A1
• Time in Patent Office: 1,551 Days
• US Class Current: 1/1
• CPC Class Codes: B60Q 1/085 due to special conditions, e.g. adverse weather, type of road, badly illuminated road signs or potential dangers B60Q1/10, B60Q1/12, B60Q1/1423 take precedence
• CPC Class Codes: B60Q 2300/312 Adverse weather
• CPC Class Codes: B60R 16/0237 circuits concerning the atmospheric environment meteorology G01W
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle

Abstract

Methods in a driver assistance system of a vehicle for detecting wetness on a road surface as well as a corresponding driver assistance system having a rearview camera are described. The method may include the following: recording an image of an area located behind the rear end of the vehicle, using the rearview camera; evaluating the recorded image for the presence of a spray trail caused by the vehicle; and selectively outputting, based on the evaluation, a wetness signal for triggering an automatic response by the driver assistance system to the wet road surface.

Claims

1. A method in a driver assistance system of a vehicle for detecting wetness on a road surface, the driver assistance system having a rearview camera, the method comprising:

recording an image of an area located behind a rear end of the vehicle using the rearview camera;

evaluating the recorded image to detect a presence of a spray trail caused by the vehicle; and

selectively outputting, based on the evaluation, a wetness signal for triggering an automatic response by the driver assistance system to a wet road surface;

wherein the recording of the image is initiated in response to the arrival of a signal of a rain sensor.

2. The method as recited in claim 1, wherein the automatic response relates to at least one of the following vehicle components:

windshield wipers, vehicle headlights, vehicle windows, and air-conditioning system.

3. The method as recited in claim 1, wherein the automatic response relates to at least one of the following subsystems of the driver assistance system:

antilock braking system, traction control system, electronic stability program, electronic brake assistant, vehicle dynamic control systems, and electronic stability controls.

4. The method as recited claim 1, wherein the automatic response relates to an output of a warning to the driver that the wetness of the road surface has exceeded a predefined threshold value.

5. The method as recited in claim 1, wherein the recording of the image is initiated in response to a detection of at least one of the following events:

reaching a regular time mark, and detection of a forward movement of the vehicle at a speed greater than a predetermined speed.

6. The method as recited in claim 1, wherein the spray trail caused by the vehicle is detected based on an evaluation of the image or a sequence of chronologically successive images recorded by the rearview camera, based on at least one of the following characteristics of a spray trail:

local extent of the spray trail in contrast with a global influence on the image due to fog or rain, a change in at least one of an extent, shape, and contour over time; and

at least one of an extent, shape, and contour which depend on a speed of the vehicle.

7. The method as recited in claim 1, wherein the output of the wetness signal takes place based on the evaluation of the image recorded by the rearview camera and of a signal of a rain sensor.

8. A non-transitory computer readable storage medium storing a computer program for a vehicle for detecting wetness on a road surface, the program, when executed by a computer unit, causing the computer unit to perform the steps of:

recording an image of an area located behind a rear end of the vehicle using the rearview camera;

evaluating the recorded image to detect a presence of a spray trail caused by the vehicle; and

selectively outputting, based on the evaluation, a wetness signal for triggering an automatic response by the driver assistance system to a wet road surface;

wherein the recording of the image is initiated in response to the arrival of a signal of a rain sensor.

9. A driver assistance system in a vehicle designed to detect wetness on a road surface, comprising:

a rearview camera to record an image of an area located behind a rear end of the vehicle;

a rain sensor to output a signal to initiate the rearview camera;

a component to evaluate the recorded image for presence of a spray trailed by the vehicle; and

a component to selectively output, based on the evaluation, a wetness signal to trigger an automatic response of the driver assistance system to a wet road surface.