Rain detection apparatus and method

• US 8,903,121 B2
• Filed: 02/22/2012
• Issued: 12/02/2014
• Est. Priority Date: 07/16/2002
• Status: Active Grant

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Heenan, Adam John, Hazelden, Roger John, Thompson, Martin John, Buchanan, Alastair James
• Primary Examiner(s): TUCKER, WESLEY J
• Application Number:
  US13/402,496
• Publication Number:
  US 20120169878A1
• Time in Patent Office: 1,014 Days
• Field of Search: 382/100, 382104-106
• US Class Current: 382/100
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0844 including a camera
• CPC Class Codes: B60S 1/485 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/603 the operation of at least a part of the cleaning means being controlled by electric means
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle

Abstract

A rain detection apparatus includes a camera that views a surface and a processor that captures an image from the camera. The processor generates a signal indicative of rain on the surface from information contained in the captured image and optionally drives a surface cleaning apparatus in response thereto. The apparatus captures images focused at a plurality of distances. The processor includes an edge detector that detects edges visible in the captured image and a difference structure that calculates the difference between the number of edges visible between differing images. The edge detector disregards edges close to areas of light larger than the largest raindrop that is desired or expected to be detected. The apparatus optionally includes a backlight, and the difference in numbers of edges between frames with and without the backlight illuminated are used to distinguish between background features and rain on the surface.

Claims

1. A rain detection apparatus comprising:

a camera adapted to view a surface being a window of a vehicle;

a processor adapted to capture at least one image from the camera, and

edge detection means arranged to detect edges visible in the at least one captured image,

wherein the processor is adapted to generate at least one signal indicative of the presence of rain on the surface from information contained in the at least one captured image, and

wherein the processor is arranged count the edges visible in the at least one captured image to generate a number of edges and to determine from the at least one captured image when a wiper of the vehicle has wiped the window should a sudden decrease occur in the number of edges.

3. The apparatus of claim 1 wherein the processor is arranged to reset a total number of edges that have been counted to zero when the processor has determined that a wiper of the vehicle has wiped the window.

2. A method of determining whether a wiper of a vehicle has wiped a window of a vehicle comprising the steps of:

using a camera to capture images of the surface; and

using a processor to determine the presence of rain on the surface from the captured images and whether a wiper of the vehicle has wiped the window, wherein the processor detects edges visible in the at least one captured image, counts a number of edges visible in the at least one captured image, and determines that the wiper has wiped the window should a sudden decrease occur in the number of edges visible in the at least one captured image.

4. The method of claim 2 wherein the processor resets a total number of edges that have been counted to zero when the processor has determined that a wiper of the vehicle has wiped the window.

5. A rain detection apparatus comprising:

a camera that generates an image of a window of a vehicle; and

a processor that;

(1) captures the image of the window of the vehicle from the camera,

(2) detects edges visible in the captured image,

(3) counts a number of visible edges,

(4) adds the number of counted visible edges to a previous number of counted visible edges to provide a total number of counted visible edges, and

(5) resets the total number of counted visible edges to zero when the processor has determined that a wiper of the vehicle has wiped the window.

6. The apparatus of claim 5 wherein the processor determines that a wiper of the vehicle has wiped the window when the number of counted visible edges decreases relative to the previous number of counted visible edges.