Method and system for inspecting a surface area for material defects

Patent metadata

Field	Value
Publication number	US-10656096-B2
Application number	US-201214113917-A
Country	US
Kind code	B2
Filing date	Apr 26, 2012
Priority date	Apr 26, 2011
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A camera assembly arranged on an unmanned and autonomously navigating aerial vehicle is employed to inspect a surface area of for material defects. The vehicle is automatically flown to the surface area from a launch site, wherein it can fly around obstacles using automatic obstacle detection and avoidance methods. A relative position of the aerial vehicle with respect to the surface area with the aid of a position sensor is continuously measured and a sequence of images of the surface area is recorded. Between the individual images, the aerial vehicle is moved along a flight path overlapping image details of the surface area. The images of the sequence are composed into an overall image of the surface area to allow for the surface area to be inspected for defects and the location of defects to be ascertained on the basis of the overall image.

First claim

The invention claimed is:

1. A method for inspecting a surface with a known position for material defects using a camera configuration arranged on an unmanned aircraft which is navigated autonomously, comprising:
automatically flying the unmanned aircraft from a starting location to the surface, wherein during the automatic flying obstacles are avoided using automatic detection of obstacles and avoidance measures;
continuously measuring a distance between the unmanned aircraft and the surface using at least a distance sensor;
recording a sequence of images of the surface, wherein the aircraft is moved along a flight path in relation to the surface in such a way that the images of the sequence have at least partially overlapping image details of the surface in overlap regions;
compiling the recorded sequence of images to form an overall image of the surface; and
inspecting the surface for defects and a localization of defects using the overall image,
wherein the distance between the unmanned aircraft and the surface is regulated continuously so that the unmanned aircraft maintains a predefined distance and a predefined orientation in relation to the surface, and the flight path runs essentially parallel to the surface such that the images of the sequence are recorded approximately from the same perspective,
wherein the camera configuration has a plurality of individual cameras which are used to navigate the unmanned aircraft and for said recording of the sequence of images of the surface, and
wherein the camera configuration is adjustable electrically.

2. The method according to claim 1 , wherein
the automatic detection of obstacles and automatic avoidance of obstacles is controlled by a sense-and-avoid system of the unmanned aircraft,
the sense-and-avoid system is initially in a navigation mode in which in which it flies automatically toward the surface or flies back to the takeoff location, and
after flying toward the surface, the sense-and-avoid system is switched to an inspection mode in which images of the surface are recorded.

3. The method according to claim 1 , wherein the camera configuration includes at least two cameras that record the sequence of images of the surface.

4. The method according to claim 1 , wherein the surface is a rotor blade of a wind turbine.

5. The method according to claim 4 , wherein after recording the sequence of images, the unmanned aircraft is flown back to the takeoff location or another rotor blade is approached in flight to record another sequence of images.

6. A system for inspecting a surface with a known position for material defects, wherein the system comprises:
an aircraft with a control unit configured to fly in a navigation mode automatically toward the surface, starting from a takeoff location and to automatically detect obstacles during the flight and to avoid the obstacles; wherein the aircraft comprises a camera configuration and a distance sensor,
wherein the distance sensor is configured to determine a distance between the aircraft and the surface after flying toward the surface,
wherein the control unit is configured to automatically move the aircraft along a flight path in relation to the surface in an inspection mode and to record a sequence of partially overlapping images of the surface and while doing to measure the distance between the aircraft and the surface corresponding to each image, wherein the images are assembled to form an overall image of the surface in order to permit an inspection of the surface for defects and a localization of defects on the basis of the overall image,
wherein the distance between the aircraft and the surface is regulated continuously so that the aircraft maintains a predefined distance and a predefined orientation in relation to the surface, and the flight path runs essentially parallel to the surface such that the images of the sequence are recorded approximately from the same perspective,
wherein the camera configuration has a plurality of individual cameras which are used to navigate the aircraft and to record the sequence of images of the surface, and
wherein the camera configuration is adjustable electrically.

7. The system according to claim 6 , further comprising:
a memory unit arranged in the aircraft and configured to store images recorded by the camera configuration; or
a radio module arranged in the aircraft that is configured to transmit images recorded by the camera configuration to a radio receiver.

8. A method for inspecting a surface with known position for material defects using a camera configuration arranged on an aircraft, this method comprising:
flying the aircraft from a takeoff location toward the surface;
continuously measuring a distance between the aircraft and the surface using at least a distance sensor;
recording a sequence of images of the surface; and
automatically or visually inspecting the surface for defects and a localization of defects using an overall image created from the sequence of images of the surface,
wherein the distance between the aircraft and the surface is regulated continuously so that the aircraft maintains a predefined distance and a predefined orientation in relation to the surface, and the flight path runs essentially parallel to the surface such that the images of the sequence are recorded approximately from the same perspective,
wherein the camera configuration has a plurality of individual cameras which are used to navigate the aircraft and for said recording of the sequence of images of the surface, and
wherein the camera configuration is adjustable electrically.

9. The method according to claim 8 , wherein the surface to be inspected is the surface of a rotor blade of a wind turbine.

Assignees

• Naderhirn Michael
• Langthaler Peter
• Eads Deutschland Gmbh

Inventors

• Naderhirn Michael
• Langthaler Peter

Classifications

• G01N21/88 Primary

  Investigating the presence of flaws or contamination · CPC title

• G01M5/0091

  by using electromagnetic excitation or detection · CPC title

• G01M5/0016

  of aircraft wings or blades · CPC title

• G01M5/0033

  by determining damage, crack or wear · CPC title

• G01C11/02

  Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures · CPC title