DE102009007938A1 - Measuring device for measuring deformations of elastically deformable objects - Google Patents

Abstract

The invention provides a device for measuring deformations of an elastic, elongate support structure which comprises at least one optically detectable marking at a first longitudinal position along the elongated support structure and at least one electronic camera with an objective and a matrix sensor. The lens of the camera is directed onto the at least one optically detectable marking in such a way that the marking is imaged onto the matrix sensor and the camera looks at the marking in the longitudinal direction along the support structure. The image data of the camera are supplied to an image processing device which is set up to determine the position of the marking within the image field on the basis of an image recognition. By means of a computing device, a deviation of the position of the marking from at least one desired value is determined and quantified.

Description

The The invention generally relates to the measurement of elastic deformations. In particular, the invention relates to the measurement of deformations an object, such as an elongate carrier, for example, a windmill wing or a wing.

Around Detecting deformations of carrier elements are in particular Strain gauges (DMS) known. With these strips can be stretching Deformations are recorded. They often form the measuring device of scales of all sizes, of household scales to crane scales. Also deformation measurements in steel construction or can also be realized by DMS measurements. To the deformation by the change in resistance of the strain gauge typically bridge circuits, such as used about a Wheatstone bridge. The mechanical Coupling of the DMS is typically done by sticking.

Also if the DMS-guided measurements are of high accuracy there are still some disadvantages. Are the structures on? which the deformation is to be measured, very long and the deformation even relatively small, would have to be reliable Measurement a very long strain gauges are used. This increases the expenditure on equipment, as well as the weight. It It must also be ensured that the connection of the elastic Support for DMS remains stable in time.

moreover can with a permanent change of the resistance parameters not be concluded, whether about a permanent deformation the actual wearer or possibly an age-related change the resistance values of the strain gauge or the bridge circuit are causal.

Of the Invention is therefore based on the object, the above Problems, especially for longer measuring distances to solve. This task is governed by the subject matter of the independent Claims solved. Advantageous embodiments and further developments of the invention are in the respective dependent Claims specified.

Accordingly, see the invention a device for measuring deformations of a elastically deformable object preferably one, elongated Carrier structure before. This device includes at least an optically detectable marking at a first longitudinal position along the elastically deformable object, and at least one electronic camera with a lens and a matrix sensor, wherein the lens of the camera on the at least one optically detectable Mark is directed, such that the mark on the matrix sensor is pictured and the camera is longitudinally along the elastically deformable object looks at the marker. The Device for measuring deformations further includes a Image processing apparatus which supplies the image data to the camera become. The image processing device is set up to based on an image recognition the position of the marker within of the image field. It is also a computing device provided, which is set up, a deviation of the position the marking of at least one setpoint to determine and quantify.

By means of this device, a method for measuring deformations of the elastically deformable object, such as a support structure is performed, wherein at least one optically detectable mark at a first longitudinal position along the elastically deformable object, and at least one electronic camera with a lens and a matrix sensor is used, wherein the lens of the camera is directed to the at least one optically detectable marker, such that the marker is imaged on the matrix sensor and the camera looks at the marker (for example, longitudinally along an object in the form of an elastically deformable support structure )
wherein an image processing device, the image data are supplied to the camera,
and wherein the image processing device performs an image recognition such that the position of the marking within the image field is determined,
and wherein a deviation of the position of the marking from at least one desired value is determined by means of a computing device and quantified on the basis of the position of the marker within the image field.

The Invention allows a highly accurate detection of deformation of the elastically deformable object even without strain gauges. The installation effort is significantly reduced, as sticking of the strain gauge eliminated.

In Preferred embodiment of the invention, the camera is connected to a from the first longitudinal position in the longitudinal direction spaced second longitudinal position arranged. As well But it is possible, the camera outside the elastic to arrange deformable object. Also in this case, the looks Camera preferably longitudinally along the object, such as in particular an elongated support structure the mark. This can be done in a simple way by an arrangement in extension of the longitudinal direction of the support structure or by an optical deflecting element in the beam path, such as be realized about a mirror or a prism.

Especially it is convenient to have existing cavities in the object exploit by placing the mark inside a cavity is. Such cavities are especially at elongated Carrier structures often present. For example, different ones Carrier, such as tubular or shaft-shaped carrier hollow inside. It is then generally appropriate, the Mark to illuminate by means of a lighting device.

With In particular, it is also possible in a very simple manner for the invention to Trace and quantify deformations in all spatial directions. This can be achieved by at least two along the longitudinal direction provided at different distances from the camera markings be, with the computing device is set up using a Comparison of the positions of the two marks a change in length or an uneven deformation of the support structure or any other object to identify and quantify.

A Such uneven deformation can be measured by the measurement the deformation takes place in two distances. Is there a normal deformation, such as a deflection before, then both marks are on or near a target curve. A deviation of Position of the markings from that known from the structure Curvature curve, for example, by a kink or a local weakening of the structure become. If such a deviation is detected, for example generates a warning signal or the device with the carrier or another elastically deformable object switched off, respectively be driven to a safe state.

following the invention is related to the deformation of an elastically deformable Carrier described. The invention can in the same way each applied to other elastically deformable objects become.

Around distinguish the markings arranged at different distances it may be beneficial to have different ones Shapes of the markers, for example different reflectors to be used, which are then discriminated with image processing can. Other distinctions could different "colors" (wavelengths the reflection) or installation directions. The distinguishing features could also be combined. When different "colors" used These can be through a color camera or through different Illuminations are distinguished. A coding of different Markers may also be advantageously by one or more wavelength-selective filters, in particular color filters on the markings. Then, in further education Invention at different times the different markings illuminated with different wavelengths and selective be evaluated.

It can in the invention also more than two used markers arranged at different distances from the camera become. For example, several reflectors in a row arranged and viewed with the camera in an axis or at an angle be evaluated, with the lateral and / or axial displacement evaluated becomes.

Farther it is also possible a torsion of the support structure to determine their longitudinal axis. This is in training invention of a marking with at least two lateral to the viewing direction spaced marking elements used, based on a Rotation of the marking elements in the image plane a twist of the elastic, elongated support structure identified and quantified becomes. Due to the torsion, the marking elements rotate a pivot in the image plane. The fulcrum does not have to be there lie within the image field. However, the twist leads then, nevertheless, to a change in the angle of the two Elements connecting route.

A suitable illumination of the marking can be realized by a laser by placing the laser parallel to the viewing direction of the camera the mark is aligned. A cheap, space-saving Possibility is, for example, the laser by means of a Beam splitter paraxial to the line of sight of the camera couple. The coupling can also be within the lens, or within the camera done.

Preferably The invention is to determine deformations on longer Used across distances. The length of the optical path between the matrix sensor and the marking can be at least 4 meters, preferably at least 6 meters. Is the inventive Measuring device installed inside a support structure, is the distance between the mark and the camera, respectively more generally the length of the optical path along the Lengthwise of the support structure substantially only limited by the fact that the mark by a deflection the limiting walls is shadowed.

With the invention, in particular, a control can be constructed, with which deformations of the support structure is counteracted. For this purpose, a control device with a device according to the invention for measuring Verformun provided, wherein the control device comprises an actuating device with at least one actuator, which is counteracted in response to the fact that the calculator a deviation of the mark has been quantified from a desired position, the elastic deformation is counteracted. Adjustment may in particular be made dependent on the deformation exceeding or reaching a predefined limit value.

According to one Another aspect of the invention is an aerodynamic wing provided with a measuring device as described herein having deformations, and a rotor of a wind turbine, wherein the rotor comprises such an aerodynamic wing. It is advantageous, at least the marking of the measuring device to arrange inside the wing and an active lighting to provide the marking.

The Camera can be in the wing, or rotor blade itself be housed. But it is also advisable to use the camera in the Rotor hub to arrange. This can be electrical or electronic Elements inside the rotor blade are avoided.

alternative or additionally, the invention may also be used in the tower of the wind turbine, which carries the rotor can be used.

The Invention can here in a particularly advantageous manner together with a control device as described above are used, wherein the actuator is an actuator for adjusting the angle of attack and wherein the adjusting device changes the angle of attack of the rotor blade. Also, in general, the buoyancy of the wing by means of a or several actuators are changed. Thought is here especially to the flaps on the wings of a Aircraft.

Around an exact quantification of a deformation by position the marking in the field of view of the camera, the knowledge of the distance of the mark to the camera is valuable. in the The simplest case is the marking at a defined distance at the Carrier structure attached. But it is also possible to design the measuring device self-calibrating. Is to according to an embodiment of the invention provided that the length of the optical path from the matrix sensor for marking by a transit time measurement of a light beam or based on the size of one projected onto the marker Pattern is determined. For example, a laser can be a grid project onto the surface of the pattern. Based on the distances The pattern can then make the removal of the camera easier Be determined automatically by triangulation. In appropriate It is also possible, depending on the design of the marker, based the size of the marking or the distance of marking elements to calibrate in the image plane by triangulation.

In The simplest form of the invention may be the marking by points or stripes contrasting with the surroundings of the marking or similar structures.

To at certain frequencies, vibrations of the support structure, like measuring a wing directly. Essential is the Frame rate of the camera. The use of modern digital chips, where a ROI (Region of Interest) can be set and only this range can be read out, allow increased Measuring frequencies. Even if the measurement frequency is limited, can higher frequencies but also in their direction and amplitude be measured by smearing the image of the mark. A direct measurement of the vibrations is for frequencies up to 20 hertz with a refresh rate of at least 50 hertz, preferably at least 60 Hertz readily possible.

For a direct measurement of the vibration of the support structure becomes taken a sequence of images and based on the from the individual images certain course of the change in position of the mark at least one of the parameters amplitude and frequency of the vibration determined by means of the computing device.

According to one Another embodiment of the invention comprises the marking a code in which a location information of the position of the code encoded, the computing means being adapted to to decode the code and thus the location of the field of view of the camera to determine on the object. The code can be the shape of a strip and / or dot pattern or any symbols z. Eg characters, Textures, color markings in which position data are coded, include. Is the information of the code by the image processing device decoded, is directly a location information ready, which for Location of the image field, preferably its center provides.

additionally for location information is preferably a synchronization pattern, as an example, a grid included. For such Code is enough, a very small code snippet with a Light source, z. B. a collimated laser to illuminate and with capture a camera and then the intersection the optical axis of the camera or an optical axis defined shifted point with the code and thus the shift to Raster origin, expressed in a discrete number of To determine raster elements.

When Location information in particular location coordinates are encoded in the code. These do not have the location position in absolute units indicate to a given reference point. A relative indication Rather, it is enough. As a relative indication can therefore in a very simple case, for example, a unique, if necessary also cyclically repeated numbering of the code units as location information suffice. The number of each code unit then corresponds to one specific location on the object.

By Translation and rotation of the surface to be examined changes the captured picture. In addition to a pure shift occur distortions which can be described by an affine transformation. The technical task is inverse, from a measured image the translation and rotation parameters are calculated, i. H. the parameters of the affine inverse transformation, the one Main axis transformation corresponds to an ideal grid.

The Measuring accuracy is among other things of the precision the raster detection determined. Therefore, particularly advantageous fast, preferably subpixel accurate edge detectors as part of Image processing apparatus.

The measurement of the change in position of the pattern with respect to the reference position can then be carried out as follows by the measuring device and its correspondingly configured image processing and computing device:
The contours are approximated by digital lines, points of intersection of the grid lines are determined. These intersections are stored in ordered order in a matrix Matrix1, where intersections connected by digital links are stored in identical rows or columns of the matrix1, unoccupied points are marked as open (disabled). The principal axis transformation between a matrix 2 learned as a reference position (this does not necessarily have to be orthogonal) and the matrix 1 provides the required 6 transformation parameters, namely three translation parameters x, y, z and three rotation parameters α, β, γ. Particularly advantageous is the use of a CMOS sensor with integrated gradient filter and digital signal processor (DSP). With this hardware can be carried out a very fast and cost-optimal single-chip processing. Thus, the image processing device and the computing device is at least partially or even completely integrated in the camera.

It it is not necessary that the location information of the code in absolute Way corresponds to the location. A relative information is also sufficient when performing a calibration. However, it is also advantageous if it is known in which Spaced along the code the location information is. In this case, directly from the decoding of the location information of Absolute amount of deformation due to the support structure caused lateral displacement of the label. For example, it is known that the location information in certain Distances, for example, filed by one centimeter is, the displacement of the pattern can be compared to the reference position by simple difference formation of the decoded location coordinates to be obtained.

Especially suitable is a two-dimensional code. With such a code can be used to improve the measurement accuracy to simple Way realized several independent measuring fields be, by z. B. with a second camera another position is determined. Likewise it is possible to put the code on one non-planar surface to attach and two from each other to scan distant areas that are at an angle to each other. In such a code as a marker is then location information for the places along two non-parallel, preferably more vertical Encoded directions. Accordingly, by decoding the Codes from the image information by means of the image processing device a shift relative to a reference position along two non-parallel axes are obtained.

As a general rule is it useful to use a code as a marker, a stretch, or in the case of a two-dimensional code, an area with to cover the mark, which are so large that the displacements due to the elastic deformations to be measured within the track, or area lie. With In other words, even with the maximum detectable deformation a Part of the code in the image field, particularly preferably also in the Image center visible.

The Determination of translations and rotations of an object in three Spatial directions by means of a code attached to an object with location information encoded therein is not on elastic deformations limited by objects. Rather, this embodiment is suitable the invention in general for the detection and quantification of Movements of objects in any direction.

According to a further aspect of the invention, therefore, a device for measuring a position change, in particular translation and rotation of an object is provided, which comprises an optically detectable code with code units applied to the object, in which position information, preferably in the form of absolute or encoded relative location coordinates. At least one camera with a matrix sensor is provided, with which the object or the code on the object can be detected. The measuring device in turn comprises an image processing and computing device. In the computing device, an assignment table is stored in which the geometric positions of at least some code units are stored at a reference position. The image processing device is, as described above, arranged to recognize the code and decode and thus to associate the decoded location information of an image position. The computing device is set up to determine the transformation, preferably in the form of a principal axis transformation, which transfers the reference position according to the allocation table into the current position detected by the camera at which the code was decoded at the image position. These transformation parameters describe the change in position of the object.

A particularly suitable for the invention, two-dimensional code is in the EP 1333402 A1 described, which is made in terms of the design and expression of the code fully the subject of the present invention.

• – der Code umfasst ein Muster, welches ein der Synchronisation dienenden Synchronisations-Code und einen positionsabhängigen Code enthält,
• – Positionsdaten sind in Codeeinheiten fester Grösse codiert,
• – der Code umfasst ein Muster, welches einen der Synchronisation dienenden Synchronisations-Code umfasst, wobei dieser Synchronisations-Code variabel ist, nach einer vorbekannten Bildungsvorschrift gebildet wird und geometrisch gleichmäßig auf der Oberfläche verteilt ist,
• – der Code umfasst ein Muster, welches ein der Synchronisation dienenden Synchronisations-Code umfasst, welcher zwei variable Komponenten umfasst, welche jeweils zur Synchronisation entlang zweier nicht paralleler Richtungen auf der Oberfläche dienen,
• – der Code umfasst ein Muster, welches einen der Synchronisation dienenden Synchronisations-Code umfasst, welcher selbst positionsabhängige Daten, vorzugsweise das oder die Least-Significiant-Bits der codierten Positionsdaten enthält,
• – der Code umfasst ein Muster, welches einen der Synchronisation dienenden Synchronisations-Code umfasst, wobei der Synchronisations-Code geometrisch gleichmässig über das Muster hinweg verteilt ist,
• – der Code umfasst ein Muster, welches einen der Synchronisation dienenden Synchronisations-Code, welcher mit zumindest der doppelten Ortsfrequenz im Vergleich zu dem positionsabhängigen Code vorliegt,
• – Positionsdaten sind in Codeeinheiten fester Grösse codiert, wobei die Ortsinformation nicht vollständig in einer Codeeinheit vorhanden ist, wobei ein vollständige Decodierung der Ortsinformation durch Erfassung eines Felds höchstens der sechsfachen Grösse einer Codeeinheit, vorzugsweise höchstens der vierfachen Grösse einer Codeeinheit möglich ist.

Accordingly, in a development of the invention, the two-dimensional code has at least one, preferably all, of the following properties:

• The code comprises a pattern containing a synchronization synchronization code and a position-dependent code,
• - Position data are encoded in fixed-length code units,
• The code comprises a pattern which comprises a synchronization code used for synchronization, this synchronization code being variable, being formed according to a previously known formation instruction and being distributed geometrically uniformly on the surface,
• The code comprises a pattern comprising a synchronization synchronization code comprising two variable components each for synchronization along two non-parallel directions on the surface,
• The code comprises a pattern which comprises a synchronization synchronization code which itself contains position-dependent data, preferably the least significant bit (s) of the coded position data,
• The code comprises a pattern which comprises a synchronization code used for the synchronization, the synchronization code being distributed geometrically uniformly over the pattern,
• The code comprises a pattern which contains a synchronization synchronization code which is at least twice the spatial frequency compared to the position-dependent code,
• - Position data are encoded in fixed-length code units, the location information is not completely present in a code unit, with a complete decoding of the location information by detecting a field at most six times the size of a code unit, preferably at most four times the size of a code unit is possible.

Of the Code can according to still another embodiment of the invention reduced to code units that are one size of at most 10 × 10, preferably at most 8 × 8, even of only 6 × 6 fields, where each of the fields represents a mark representing one bit. In general, the code units may be as described above viewed laterally spaced marking elements of the label become.

Of the The code described above is in terms of its information density optimized. The code can be used with a customized decoding method stably read even with a small field of optional form become.

Around is to allow a measurement of elastic deformations is according to yet another embodiment of the invention, that the code at least partially on an oblique to Viewing direction arranged surface is arranged, wherein the mark with the code is arranged so that from the Camera or even from several cameras simultaneously in different Distances along the longitudinal direction of the support structure arranged code elements in which location information is coded, be recorded. Preferably, the code is at least two to each other applied in angled surfaces.

Of the diagonally opposite the viewing direction of the camera arranged code can have a grid which is equidistant, or is also projection-corrected.

Around a shift in the areas provided with the code a reference position and thus a deformation of the support structure to can determine advantageously in the computing device an allocation table of coordinates, preferably three-dimensional Coordinates to location information of the code are stored. The Allocation table can, as will be described in more detail below, among other things, by projecting a grid onto the one with the code provided areas and a comparison with the decoded location information to be generated.

Out the decoded position data can in a known arrangement of the Codes at the reference position by the computing device a main axis transformation be calculated with which the mark from the reference position transformed into the measured position. From this main axis transformation can then change the position relative to the Reference position are determined and quantified. This allows a recognition of both a rotation and a translation in three directions.

As a general rule The invention can be used to the functionality a support structure, such as a rotor blade to monitor, control and / or regulate a wind turbine. This can also be anticipatory, or extrapolating, by the movement pattern measured by the computing device stored movement patterns are compared. An example is a vibration with still permissible, but aufschaukelnder Amplitude. If, for example, such a movement pattern is detected, can be early by a suitable scheme, such as by amendment the angle of attack are counteracted.

The Invention will be described below with reference to embodiments and with reference to the accompanying drawings explained. The same reference numbers refer to the same or corresponding elements.

It demonstrate:

1 3 a view of a rotor of a wind turbine with parts of a device for measuring elastic deformations of a rotor blade,

2 a cross section through a rotor blade,

3 a camera of the measuring device,

4 a video shot of the camera during a deflection of the rotor blade,

5 a variant of the rotor 1 .

6 a video shot of the camera of the markings in the rotor blade of the in 5 shown example,

7 a diagram with deflection curves of the wing of the rotor,

8th an arrangement of the measuring device with a two-dimensional code as marking,

9 an arrangement with a code with projection corrected raster.

1 shows a wind turbine rotor according to the invention 1 with three wings 5 , Each of the wings 5 forms an elastically deformable support structure. The rotor accommodates parts of a device for measuring deformation of the wings, the principle of which is explained below. The task of the measuring device is now the deflection of the wing 5 to measure the wind turbine in two axes.

The device for measuring deformations is based on at least one optically detectable marking 7 at a first longitudinal position along the wing 5 , as well as an electronic camera 9 with a lens 11 and a matrix sensor, with the lens 11 the camera is directed to the at least one optically detectable mark, such that the mark 7 imaged on the matrix sensor and the camera 9 longitudinally along the wing 5 on the mark 7 The device for measuring deformations further comprises an image processing device to which the image data are fed to the camera, and wherein the image processing device is set up to determine the position of the marking within the image field by means of image recognition, wherein the device for measuring deformations also a computing device which is set up to determine and quantify a deviation of the position of the marking from at least one desired value.

The image processing device and the computing device are in 1 not explicitly shown. However, these facilities can also be found in the camera 9 be integrated, so the camera 9 at an output already outputs the data of the deviation from the target position, for example, the position of the stationary rotor in calm weather.

At the in 1 In the embodiment shown, the camera is in the hub 3 of the rotor 1 built-in. This is beneficial to avoid electronic elements in the rotor blades. The rotor hub can be opposite the wings 5 be more easily shielded from a lightning strike, so that the camera is protected from a lightning-related failure.

If it comes to a deformation of the wing due to the oncoming wind during operation, the position of the marker moves 7 transverse to the longitudinal axis of the wing, which also represents the viewing direction of the camera. This shifts the position of the image of the mark on the matrix sensor of the camera 9 , Is the distance of the camera 9 known for marking, from the shift by means of the computing device, the Defor mation be easily calculated at the location of the label.

The distance of the matrix sensor of the camera 9 for marking is preferably between the matrix sensor and the marking at least 4 meters, more preferably at least 6 meters in order to measure a deflection of the wing with high accuracy can. On the other hand, it is generally favorable to choose the distance not greater than 40 meters, otherwise the wing 5 at the occurring loads quickly bent so far that the mark is no longer in the field of view of the camera, but is covered by the curved walls of the wing.

Particularly preferably, a control device can generally be provided with which the deformations can be counteracted. For this purpose, the regulating device comprises an adjusting device with at least one actuator, with which the elastic deformation is counteracted in response to the fact that the calculating device has quantified a deviation of the marking from a desired position, in particular the exceeding of a limit value. In the case of in 1 shown wind turbine rotor 1 is doing an actuator for adjusting the angle of attack of the wings 5 used, so that the adjusting device changes the angle of attack of the rotor blade in dependence on the measured deformation.

2 shows a cross section through the wing 5 , Typically, wings of wind turbines, as well as other aerodynamic wings, in particular aircraft wings along their longitudinal direction extending cavities. At the in 2 example shown here includes the wing 5 an upper shell 51 and a lower shell 52 between which a spar 54 is arranged. Inside the spar 54 extends a shaft-shaped cavity 56 , Also the other spaces 55 and 57 can be hollow. It is now appropriate that as in 2 shown, at least the mark 7 the measuring device inside the wing 5 is arranged. Exemplary is in 2 the mark in the spar 54 in the shaft-shaped cavity 56 used. So the camera 9 the mark 7 is detected, an active illumination of the mark is provided.

3 shows an example of a suitable camera 9 , This example is about the lens 11 around the case 91 the camera 9 LEDs 92 provided which objects along the line of sight of the camera, when installed so along the longitudinal direction of the wing 5 illuminate. In order to obtain a high contrast in the recorded images, it is then still favorable to form the marker as a reflector. This can be a reflector foil, or, as in 2 represented a mark 7 be used in the form of a cat's eye.

4 schematically shows a camera image 94 from the image sequence, which is typically recorded continuously at the intended image repetition rate during operation. The mark can be seen in the camera image 7 , which are opposite the reference position 70 is moved. The camera 9 and the lighting is controlled or adjusted so that the light signal of the reflector controls the camera well, but preferably not overridden. There is a focal point determination of the reflector image. With the known properties of the lens of the camera, the deflection of the light spot with respect to the reference position 70 determined in two directions. In the case of a grand piano 5 Preferably, the reference position represents the position of the mark 7 at calm, in which no significant forces except the caused by the dead weight moments act on the wing. From the calibrated distance between the marking and the camera and the offset of the mark from the reference position, this shot results in a deflection of 0.543 meters.

5 shows a variant of the rotor 1 out 1 , In this variant, two are along the longitudinal direction of the wing at different distances from the camera 9 spaced marks 7 . 71 intended. Based on the position of these marks 7 . 71 It is then also possible to determine and quantify an uneven deformation of the support structure.

In addition, the markings 7 . 71 each comprise two or more laterally spaced apart from the viewing direction marking elements. Then, based on a rotation of the marking elements in the image plane, a torsion of the elastic, elongated support structure, or in the example of 5 a twist of the wing 5 be determined and quantified.

6 shows a picture from the camera 9 of in 5 shown rotor 1 recorded video sequence.

Each of the marks 7 . 71 includes at the in 6 illustrated example, two laterally spaced marking elements. The marking elements 701 . 702 the mark 7 and the marking elements 704 . 705 the mark 71 are also arranged along mutually transverse, here in particular along mutually perpendicular lines. To the markings 7 . 71 be distinguished from each other, the marking elements discrete properties, such as different color or Shape up. This is in 6 symbolized by the different filling of the here circular marking elements. A coding of the different markings 7 . 71 can advantageously also by one or more wavelength-selective filters, such as in particular color filter on the markings. If different colors are reflected back or reflected back from the markings to the camera, the different markings with different wavelengths can be illuminated and selectively evaluated at different times in a further development of the invention. This can be particularly advantageous if more than two markers are used and are to be discriminated.

It is favorable as in the previous examples, the markings 7 . 71 , or their marking elements 701 . 702 and 7004 . 705 form as reflectors, so as to achieve a high image contrast at the viewing direction paraxial illumination, for example by light-emitting diodes or one or more lasers.

The position of the marks 7 . 71 is now derived from two reflector images. From the distance between the two reflector images can now also the mounting distance of the reflectors, or the markings 7 . 71 measured to the camera and so the measuring arrangement calibrated, since the real distance to a mark 7 . 71 belonging marking elements 701 . 702 , respectively 704 . 705 is known. So is the basis of the recording 94 to recognize that the distance of the marking elements 704 . 705 is smaller than the distance of the marking elements 701 . 702 , The mark 71 is on condition that the real distance is the same, thus further away from the matrix sensor of the camera.

There the distance between the pictured marking elements with their Distance changes can be determined by a distance determination now also in a simple manner a deformation in the longitudinal direction, In particular, an expansion of the wing detected and quantified become. In the wings of large rotors can such strains certainly orders of magnitude in the meter range to reach.

Based on the two each arranged in a line marking elements now the measurement of a rotation of the wing is possible. Kicks in between the camera 9 and mark 7 and or 71 a twist on, the angle of the two changes to a marker 7 . 71 belonging marking elements connecting line in the image plane.

According to one embodiment, the following parameters can be used for the measuring device:
The working distance, or the length of the optical path between sensor and marking is selected within a distance of about 40 meters. The measurement time is 16.6 milliseconds corresponding to a refresh rate of 60 frames per second. Measurable are the magnitudes X-deflection, Y-deflection, rotation, distance of the marking, oscillation amplitude and oscillation frequency up to typically 20 Hertz. With a simple camera sensor can already a measurement accuracy of 1/7000 of the maximum detectable deflection along the X-axis (the direction along the longer side of the in 6 shown image) and 1/4000 of the maximum detectable deflection along the Y-axis.

7 shows an example, as based on a comparison of the positions of the two marks an uneven deformation of the support structure, in particular a non-uniform deflection of the wing 5 can be determined and quantified.

In 7 are diagrams of the deflection .DELTA.x of the wing as a function of the distance D to the hub shown. The mark 7 is at position d1 and the mark 71 arranged at the position d2.

The solid curve shows an example of a normal, uniform Deflection of an intact wing. Indicates the wing a kink, or for example, a crack on, to weakening the structure of the wing leads, it comes behind the Crack or kink to increased deflection. Such an exemplary deflection curve is shown in dashed lines. Accordingly, the ratio of the deflections .DELTA.x bigger here. Is based on the measurement data from the computing device found that such an abnormal deflection is permanent, or a permanent deviation from the bevy of deflection curves an intact wing is present, for example, a Shut down the wind turbine or start a safe State initiated. This safe state can be, for example can be achieved by neutral position of the wings, wherein the defective wing points downwards.

By the attachment of two reflector pairs in the depth of the wing The bending can be measured in two distances. This is It is possible to check if the wing is even is bent, or if there is a kink, because the two Points no longer on the known from the structure curvature curve lie.

It is also possible according to a further embodiment of the invention, in addition or al to provide a marking in the form of a code, in which location information is coded, to determine the position of marking elements. This offers, inter alia, the advantage that the deformation of a carrier structure can always be determined on the basis of the imaged and decoded information relating to the image center or any other reference point in the image plane. This eliminates measurement errors that can be caused by distortion of the lens.

Accordingly, includes the marker a code in which location information of the local Position of the code is coded, the computing device to is set up to decode the code and thus the location of the field of view to determine the camera.

When using the 1 to 7 described measuring device can be detected and quantified a shift of the markers in all directions in the image plane, thus in two dimensions transverse to the viewing direction of the camera. If a code with location information is used, it is therefore advantageous to choose according to a two-dimensional code in which location information for the locations along two non-parallel, preferably vertical directions is coded.

following is a preferred code and its arrangement as a marker in or described in more detail on the support structure.

As in the case of the exemplary embodiments described above, a camera is again present in a volume of the carrier structure 9 and one or more markers in the form of labels arranged with the code.

The or the labels are not just on a single planar surface, but on at least two mutually angled surfaces or surface elements, for example, on a curved Surface arranged.

An exemplary arrangement with inclined surfaces 76 . 77 , which is provided with a mark in the form of a two-dimensional code, shows 8th The grid can be equidistant or projection-corrected, so that the resolution and thus measurement accuracy for the directions considered is approximately constant.

Shows a code with projection-corrected grid 9 , The grid width of the matrix, or the grid of the code on the substantially perpendicular to the viewing direction 95 the camera 9 standing area 76 has a value α, while the grid width of α at an angle to the viewing direction 95 the camera 9 standing area 77 in the direction of view is increased by a value a / sin (α).

The individual grids 710 represent individual bits of the code. In order to recognize the fields and to be able to decode the code, the fields are formed differently contrasting depending on the bit value. For example, dark and light, or absorbing and reflective fields may be used. The bit values are in 9 represented by different fillings of the grids. For example, the hatched fields may represent logical zeros and the non-hatched fields may represent logical ones or vice versa.

The code can - in contrast to a simple grid - ensure an absolute reference point. It is possible to endlessly print or otherwise produce an appropriate code by distributing the information in a particular way two-dimensionally so that the global positioning can be fully calculated from a maximum of 4 6x6 grid environments. Such a two-dimensional code as is preferred for the invention is known from the EP 1333402 A1 known.

The arrangement of the code on multiple surfaces or surface elements that are at different distances from the camera, such as the exemplary arrangement of the surfaces 76 . 77 serves according to the in 5 shown arrangement to detect a deformation along the line of sight. For this purpose, code units are decoded on a plurality of area elements arranged at different distances and their location information is evaluated. If there is a shift in the longitudinal direction, the location information at certain assigned image parts also change relative to one another. Instead of evaluating different image parts, it is also possible to use a plurality of cameras which detect different surface elements. As well as in 5 Codes can also be applied to a plurality of surfaces arranged one behind the other in the direction of view of the camera, so that nonlinear deformations can be detected with a plurality of measuring points, and / or to increase the measuring accuracy.

A printed with such a code slide (or similar Structure) is now stuck to the object to be measured or on attached to another way. Due to the special structure of the information arrangement can determine the phase and frequency of the local grid (similar to large 2D barcodes, FFT or chain processing). Here, a codeintern used scrambling a ensure high local contour density.

After finding the grid by the Bildver processing device, the code content is binarized and entered into a matrix. From this, the global position can then be decoded in the (de facto infinite) grid. Also, the method of decoding is in the EP 1333402 A1 described, the content of which is fully made in this respect also the subject of the present application.

If the geometry of the surface is already known, defined points P _i (x, y, z) of the grid can be assigned to 3D coordinates.

One obtains a precisely assigned table of the form: P i (x, y, z) ← → angle i (α, β, γ).

These Table can then be used in the computing device to calculate the current Position, or the deformation of the support structure stored become.

The Angles result from the central projection of the camera image through the aperture of the lens. From the set {P, angle} can conclude by matching while determining the parameters of a major axis transformation the displacement of the labeled object with respect to a Reference Positon be issued. Measurable are the displacement vector (X0, Y0, Z0) as well as the rotation in three angles (α0, β0, γ0).

• 1. mit einem Lasergitterprojektor (z. B. einem Laser mit diffraktivem Element) wird von einer bekannten Position aus (z. B. auf dem Gehäuse gestiftet ) auf das Raster eine Punktwolke bzw. ein zweites Gitter projiziert. Hierzu kann zweckmäßig eine Komplementärfarbe verwendet werden, z. B. wird das Raster rot gedruckt, der Laser erzeugt seine Struktur ohne Kontrastfehler. Für die Inspektion kann dann der blaue Spektralbereich benutzt werden. Es ist dem Fachmann ersichtlich, dass hierzu noch viele weitere Möglichkeiten existieren.
• 2. Die Laserstruktur wird vermessen, die Passpunkte werden zugeordnet. Durch einfache Triangulation (der Abstand Laserblende zur Objektivblende ist bekannt, die Winkel sind bekannt) werden kalibrierte 3D Koordinaten auf dem Raster ermittelt.
• 3. Abschließend wird das Set der so gemessenen 3D-Punkte dem Referenzraster zugeordnet, man erhält einen Set von 3D-Referenzpunkten auf dem Raster. Der Laser kann dann entfernt werden.

If the reference position is not known, for example if the exact shape to which the grid has been stuck, or the distance of the code to the camera is not determined, the following can be carried out according to an embodiment of the invention:

• 1. With a laser lattice projector (eg a laser with a diffractive element), a point cloud or a second lattice is projected onto the grid from a known position (for example, on the housing). For this purpose, a complementary color can be used suitably, for. For example, the grid is printed in red, the laser creates its structure without contrast errors. The blue spectral range can then be used for the inspection. It will be apparent to those skilled in the art that there are many more possibilities for this.
• 2. The laser structure is measured, the control points are assigned. By simple triangulation (the distance laser aperture to the lens aperture is known, the angles are known) calibrated 3D coordinates are determined on the grid.
• 3. Finally, the set of 3D points measured in this way is assigned to the reference grid, giving you a set of 3D reference points on the grid. The laser can then be removed.

Becomes If a non-projection-corrected code is used, calibration may be used both the distance, as well as the location of the Area also based on a comparison of the known grid width with the grid width detected in the camera is made.

• – der Code umfasst ein der Synchronisation dienenden Synchronisations-Code und einen positionsabhängigen Code enthält, wobei die Positionsdaten in Codeeinheiten fester Grösse codiert sind. Dabei ist der Synchronisations-Code variabel und geometrisch gleichmäßig auf der Oberfläche verteilt. Der Synchronisationscode ermöglicht ausserdem mittels zweier variabler Komponenten die Synchronisation in X- und Y-Richtung. Im Speziellen ist der Synchronisationscode dergestalt variabel, dass er selber positionsabhängige Daten, vorzugsweise das oder die Least-Significiant-Bits der codierten Positionsdaten enthält. Möglich ist auch, das nur langsam veränderliche Most-Significant Bit einzusetzen. Um die Synchronisation besonders zuverlässig zu machen, kann der Synchronisations-Code mit zumindest der doppelten Ortsfrequenz im Vergleich zum positionsabhängigen Code vorliegen. Um besonders kleine Code-Einheiten zu erhalten, ist es dann auch noch möglich, die Ortsinformation nicht vollständig in einer Codeeinheit zu codieren. Die vollständige Ortsinformation kann dann durch Erfassung eines Felds höchstens der sechsfachen Grösse einer Codeeinheit, vorzugsweise höchstens der vierfachen Grösse einer Codeeinheit durchgeführt werden. Dabei können die Daten so aufgeteilt werden, dass fehlende Bits eines Positionsdatums aus benachbarten Code-Einheiten ergänzt werden.

The preferred code will be described in more detail below. The two-dimensional code has the properties:

• - The code comprises a synchronization synchronization code and a position-dependent code contains, wherein the position data are encoded in code units of fixed size. The synchronization code is variable and geometrically evenly distributed on the surface. The synchronization code also allows the synchronization in the X and Y directions by means of two variable components. In particular, the synchronization code is variable such that it itself contains position-dependent data, preferably the least significant bit (s) of the coded position data. It is also possible to use the only slowly changing Most-Significant Bit. In order to make the synchronization particularly reliable, the synchronization code can be present at least twice the spatial frequency compared to the position-dependent code. In order to obtain particularly small code units, it is then also possible not to completely encode the location information in a code unit. The complete location information can then be carried out by detecting a field at most six times the size of a code unit, preferably at most four times the size of a code unit. In this case, the data can be divided so that missing bits of a position data from adjacent code units are added.

The above embodiments relate to the, or the wings of a wind turbine. The invention may also be appropriate for aircraft wings be used. Here it makes sense, not the angle of attack the wing depending on the deformation unless the wings are generally are rigid. But it is possible here, the buoyancy means one or more rudders and flaps, such as the ailerons and Regulate spoilers or flaps.

There the deformation of the wing typically a change in position preceded by the aircraft can be controlled by a control device, which the flaps and / or rudder on the basis of the measurement of the deflection and / or twisting of the wing controls, among others the attitude is stabilized.

Also in the fuselage can advantageously be an inventive Measuring device are provided to here loads the support structure to be able to recognize.

It It will be apparent to those skilled in the art that the invention is not limited to the above limited embodiments described is, but can be varied in many ways. In particular, the invention can also be applied to other carrier structures and elastically deformable objects are applied.

1

Wind turbine rotor

3

Hub of 1

5

Wings of 1

7, 71

mark

9

camera

11

Lens of 9

51

Upper shell of 5

52

Lower shell of 5

54

Holm

55, 57

Spaces between 51 . 52

56

shaft-shaped cavity in 54

76 77

With a two-dimensional code provided surfaces

91

Housing of 9

92

LEDs

95

Viewing direction of 9

701 702

704 705

markers

710

grid

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1333402 A1 [0039, 0091, 0094]

Claims (24)

Device for measuring deformations of a elastically deformable object, preferably an elongated Carrier structure comprising at least one optically detectable Marking at a first longitudinal position along the elastic deformable object, as well as at least one electronic camera with a lens and a matrix sensor, with the lens of the Camera directed to the at least one optically detectable marker is such that the mark imaged on the matrix sensor and the camera looks at the marker, with the device for measuring deformations further comprises an image processing device, which the image data is supplied to the camera, and wherein the image processing device is arranged based an image recognition the position of the marker within the image field to determine, with the device for measuring deformations also includes a computing device which is set up is a deviation of the position of the mark of at least one Setpoint to determine and quantify. Device according to the above Claim, wherein the camera at one of the first longitudinal position longitudinally spaced second longitudinal position is arranged. Device according to one of the preceding claims, characterized in that the mark within a cavity the elastically deformable object is arranged and by means of a Lighting device is illuminated. Device according to one of the preceding claims, characterized by at least two along the longitudinal direction at different distances from the camera spaced marks, wherein the computing device is set up based on a comparison the positions of the two markers a change in length or an uneven deformation of the elastically deformable object to identify and quantify. Device according to one of the preceding claims, characterized in that the tag comprises a code, in which a location information of the position of the code is encoded, wherein the computing means is adapted to decode the code and thus determine the location of the field of view of the camera. Device according to the above Claim, characterized in that the code is a two-dimensional Code includes in which location information for the places along is encoded in two non-parallel, preferably perpendicular directions. Device according to the above Claim, characterized in that the code at least one, preferably has all of the following properties: - of the Code includes a pattern which is for synchronization Synchronization code and a position-dependent code contains - Position data is in code units fixed size coded, - the code includes a pattern comprising a synchronization code serving synchronization, this synchronization code is variable, according to a previously known Education provision is made and geometrically uniform is distributed on the surface, - the code includes a pattern containing a synchronization synchronization code comprising two variable components each for synchronization along two non-parallel directions serve the surface, - the code includes a pattern comprising a synchronization code serving synchronization, which itself position-dependent data, preferably the or contains the least significant bits of the coded position data, - of the Code includes a pattern which is for synchronization Includes synchronization code, where the synchronization code is geometric evenly distributed across the pattern, - of the Code includes a pattern which is for synchronization Synchronization code, which is at least twice the spatial frequency in the Compared to the position-dependent code, - Position data are coded in code units of fixed size, the Location information not completely in a code unit is present, with a complete decoding of the location information by detecting a field at most six times the size of a field Code unit, preferably at most four times the size a code unit is possible. Device according to one of the two preceding claims, characterized in that the Code at least partially on an oblique to the viewing direction arranged surface is arranged, wherein the mark with the code arranged so that from the camera or from multiple cameras at the same time at different distances along one direction the elastically deformable object arranged code elements, in which location information is encoded are detected. Device according to one of the three preceding claims, characterized in that in the computing device an assignment table of coordinates, preferably three-dimensional coordinates stored to location information of the code is. Device according to one of the four preceding claims, characterized in that the computing device is adapted to a main axis transformation from decoded position data to calculate with which the mark from the reference position transformed into the measured position and based on the main axis transformation the position change with respect to the reference position to identify and quantify. Device according to one of the preceding claims, characterized by a laser for illuminating the marking, the laser being parallel to the viewing direction of the camera the mark is aligned. Device according to one of the preceding claims, characterized in that the length of the optical path between the matrix sensor and the marking at least 4 meters, preferably at least 6 meters. Control device with a device for measuring deformations according to one of the preceding Claims, wherein the control device is an adjusting device comprising at least one actuator, with which under response that the calculator deviates from the mark was quantified from a target position, the elastic deformation counteracted. Aerodynamic wing, characterized by a device for measuring deformations according to a of the preceding claims. Aerodynamic wing according to the preceding claim, characterized in that at least the Marking the measuring device arranged inside the wing is, with an active illumination of the mark is provided. Wind turbine rotor with an aerodynamic Wing according to the preceding claim. Wind turbine rotor according to the preceding claim, characterized in that the camera in the rotor hub is arranged. Wind turbine rotor according to the preceding claim, characterized by a control device according to claim 13, wherein the actuator is an actuator for adjusting the angle of attack, and wherein the adjusting device changes the angle of attack of the rotor blade. Method of measuring deformations of an elastic deformable object, in particular an elastic, elongated Carrier structure, wherein at least one optically detectable Marking at a first longitudinal position along the elastically deformable object, and at least one electronic camera with a lens and a matrix sensor is used, with the lens of the camera on which at least one optically detectable marking is directed, in such a way that the mark is imaged on the matrix sensor and the Camera looks at the marker, wherein an image processing device the image data is fed to the camera, and where the image processing device performs image recognition, such that the position of the marker within the frame is determined becomes, and wherein by means of a computing device, a deviation the position of the mark of at least one setpoint determined and quantified by the position of the mark within the image field becomes. Method according to the above Claim, characterized in that the deformation of an aerodynamic Wing is detected and quantified and by means of at least an actuator in dependence of the deformation of the angle of attack the wing or its buoyancy is changed. Method according to one of the two preceding claims, characterized in that a Marking with at least two laterally spaced from the viewing direction Marking elements is used, based on a rotation of the Marking elements in the image plane a twist of the elastic, elongated support structure identified and quantified becomes. Method according to one of the three preceding claims, characterized in that the length of the optical path from the matrix sensor to the mark by a Runtime measurement of a light beam or by size a pattern projected onto the marker. Method according to one of the four preceding claims, wherein a measurement of the vibration the elastically deformable object is performed, wherein taken a sequence of images and based on the from the individual images certain course of the change in position of the mark at least one of the parameters amplitude and frequency of the vibration determined by the computing device. Method according to one of the five preceding claims, characterized in that measured Movement pattern by the computing device with stored Motion patterns are compared.