DK202170372A1 - System and method for performing nondestructive scans of a wind turbine blade - Google Patents

Abstract

A robotic device (60) for performing non-destructive test (NDT) scans of a wind turbine blade (20) on a wind turbine (10) is provided. The robotic device (60) includes a main chassis (64) configured to be mounted on the wind turbine blade (20) which is horizontally oriented and pitched to orient a leading edge (22) of the blade (20) to face vertically upward. The main chassis (64) is then positioned adjacent the leading edge (22) of the wind turbine blade (20) and includes a drive (68) that operates to move the device (60) along a longitudinal length of the wind turbine blade (20). The robotic device (60) includes a first and second scanner support arm (90, 94) pivotally connected to the main chassis (64) and positioned on opposing sides of the leading edge (22) when the main chassis (64) is mounted on the wind turbine blade (20). At least one NDT scanning element (92) is mounted on each of the first and second scanner support arms (90, 94) and positioned so as to scan a side (26) of the wind turbine blade (20) longitudinally as the drive (68) moves the main chassis (64) along the longitudinal length of the wind turbine blade (20). The NDT scanning elements (92) are configured to detect whether any delamination conditions are present within the wind turbine blade (20) based on the longitudinal scans from the NDT scanning elements (92).

Description

DK 2021 70372 A1 SYSTEM AND METHOD FOR PERFORMING NON-DESTRUCTIVE SCANS OF A

WIND TURBINE BLADE Technical Field This application relates generally to wind turbines, and more particularly relates to a robotic device and associated method for performing non-destructive scans of a wind turbine blade without necessitating removal of the blade from the tower of the wind turbine.

Background Wind turbines are used to produce electrical energy using a renewable resource and without combusting a fossil fuel. Generally, a wind turbine converts kinetic energy from the wind into electrical power. A conventional wind turbine installation includes a foundation, a tower supported by the foundation, and an energy generating unit positioned atop of the tower. The energy generating unit typically includes one or more nacelles to house several mechanical and electrical components, such as a generator, gearbox, and main bearing, and the wind turbine also includes a rotor operatively coupled to the components in the nacelle through a main shaft extending from the nacelle. Single rotor wind turbines and multi-rotor wind turbines (which may have multiple nacelles) are known, but for the sake of efficiency, the following description refers primarily to single rotor designs. The rotor, in turn, includes a central hub and a plurality of blades extending radially therefrom and configured to interact with the wind to cause rotation of the rotor. The rotor is supported on the main shaft, which is either directly or indirectly operatively coupled with the generator which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator. Wind power has seen significant growth over the last few decades, with many wind turbine installations being located both on land and offshore.

The blades are typically formed from a shell of fiber reinforced plastics, aluminum, or similar material with an outer skin defined by a series of layers of coatings (polymeric elastomers, paint, etc.) surrounding and covering an outer surface of the shell. The shell 1

DK 2021 70372 A1 is connected to internal structures such as reinforcing webs and spars during manufacturing, which results in many components and connection points being located within the closed periphery defined by the shell.

As noted above, blades interact with the wind to generate mechanical rotation of the rotor, which can then be converted into electrical energy.

The blades move at varying speeds through the ambient environment surrounding the wind turbine, but often this movement is at high speed.

Accordingly, forces and strain applied to the blades during use at the wind turbine can be very high, and as such, it is desired to routinely check the blades for any degradation that may adversely affect how the blade carries these forces and strain and ultimately the performance and operation of the blade.

Inspection of wind turbine blades for any degradation is important for ongoing operation of wind turbines, particularly inspection for delamination damage.

In most cases, delamination is very difficult to detect as there is typically no external symptoms visible on the surface of wind turbine blades.

In this regard, inspection methods typically utilize several types of so-called NDT, non-destructive testing, on a blade to evaluate whether any defects are present that require correction.

Conventional NDT detection methods include but are not limited to: visual scanning (with cameras or manually by operators), acoustic scanning, thermography scanning, and ultrasonic inspections.

These NDT detection methods are used to detect various types of potential blade defects such as, for example, web-to-shell adhesive bonds being outside specification, web-to-shell adhesive forming weak "kissing" bonds, trailing edge and leading edge bond deficiencies, delaminations and/or dry spots in laminate construction, incorrect positioning of the blade components, wrinkles caused by non-straight fibers in the laminate, and other core damages.

Such conventional NDT testing for these and other types of potential defects requires a significant amount of labor (including high levels of expertise in reading scans) as well as time investment, each of which increases the cost and time necessary before putting a blade back into operation at the wind turbine.

Moreover, inspection and diagnostic methods leading to more accurate inspection results typically require complex measuring 2

DK 2021 70372 A1 instrumentation and stable measurement conditions. In this regard, it is typical for a wind turbine blade to be removed from the wind turbine and lowered to the ground to provide a stable environment for an accurate inspection. This process not only requires additional labor but creates longer periods of down time for the wind turbine, both of which are undesirable. In recent years, a desire has emerged for more automated inspections of wind turbine blades to thereby improve the speed and/or precision of such a process. More particularly, a desire has emerged to perform a more accurate automated inspection of a wind turbine blade while still attached to the wind turbine to eliminate the need to remove the blade for inspection on the ground. In this regard, several automated or semi- autonomous NDT scanning devices for wind turbine blades are known in the art. One such scanning device is described in U.S. Patent No. 10,953,938, which shows a maintenance apparatus including a cart supporting a plurality of crawler vehicles on cables along opposite sides of a wind turbine blade. The scanning devices provided in the ‘938 Patent necessitate complex control and movement mechanisms, such as to enable scans transversally along a width of the blade, and typically also require post- processing and combinations of scans to confirm damage conditions, which adds significant time and work to the NDT scanning process of these references.

However, these and other conventional automated devices are not always designed for reliable use on a wind turbine blade still connected to the rotor and hub of a wind turbine, and such systems are very slow in operation. Moreover, such automated devices are typically not configured to perform a longitudinal scan of the entire blade, as may be required to inspect for delaminations. Other devices may require multiple sweeps or passes along the wind turbine blade to inspect the entire blade, which makes the conventional NDT automated scanning too slow for most users. Multiple passes or sweeps adds significant time to the NDT process as well as requires post-scanning analysis to combine the various scans. As a result, previously-developed automated inspection options have not been widely adopted. Further improvements for automated 3

DK 2021 70372 A1 wind turbine blade inspection systems are therefore desired, particularly for detecting delamination within a wind turbine blade.

Summary To these and other ends, embodiments of the invention are directed to a robotic device for performing non-destructive (NDT) scans of a wind turbine blade of a wind turbine for damage. The robotic device includes a main chassis configured to be mounted on the wind turbine blade which is horizontally oriented and pitched to orient a leading edge of the blade to face vertically upward. The main chassis is positioned adjacent the leading edge of the wind turbine blade and includes a drive that operates to move the device along a longitudinal length of the wind turbine blade. The robotic device includes a first and second scanner support arm pivotally connected to the main chassis and positioned on opposing sides of the leading edge when the main chassis is mounted on the wind turbine blade. Atleast one NDT scanning element is mounted on each of the first and second scanner support arms and positioned so as to scan a side of the wind turbine blade longitudinally as the drive moves the main chassis along the longitudinal length of the wind turbine blade. The NDT scanning elements are configured to detect whether any delamination conditions are present within the wind turbine blade based on the longitudinal scans from the NDT scanning elements.

In one embodiment, the first and second scanner support arms of the robotic device are rigid, elongated arm elements that extend between a first end pivotally connected to the main chassis and a second end carrying the at least one NDT scanning element. Ina further embodiment, each individual one of the NDT scanning elements is configured to detect delamination conditions within the wind turbine blade based on an individual longitudinal scan of the wind turbine blade. In another embodiment, the wind turbine blade includes at least one longitudinally extending carbon fiber spar and a shell that is constructed from rows of fiber reinforced plastics. The first and second scanner support arms are positioned with at least one of the NDT scanning elements on the side of the wind turbine blade and in alignment with 4

DK 2021 70372 A1 the at least on carbon fiber spar to move longitudinally along the wind turbine blade to scan the at least one longitudinally extending carbon fiber spar. This configuration advantageously maintains alignment with the spar to scan the entire spar during one sweep by the robotic device. In a further embodiment, one of either the first or second scanner support arms includes a first and a second NDT scanning element. In this embodiment, the first NDT scanning element is configured to detect whether any delamination conditions are present within the shell of the wind turbine blade and the second NDT scanning element is configured to detect whether any delamination conditions are present between the shell and the at least one carbon fiber spar. This can be advantageous where there are multiple layers of the blade requiring inspection for delamination damage, for example. In one embodiment, each of the NDT scanning elements includes an ultrasonic scanner. In yet another embodiment, the first and second support arms are pivotally connected to the main chassis and adjustable such that an exact position of each of the NDT scanning elements can thereby be adjusted along opposing sides of the wind turbine blade for making the longitudinal scans of the wind turbine blade. In one embodiment, the first and second support arms are configured to adjust, in a chordwise direction along opposing sides of the wind turbine blade, a position of each of the at least one NDT scanning elements to maintain alignment with the at least one carbon fiber spar as the robotic device moves along the longitudinal length of the wind turbine blade. In one embodiment, the robotic device further includes an applicator tool connected to the main chassis and configured to perform repair actions on the wind turbine blade.

Embodiments of the present invention are also directed to a method for performing NDT scans of a wind turbine blade on a wind turbine. The method includes operating the wind turbine to move one of the wind turbine blades to a generally horizontal orientation, and pitching the wind turbine blade in the generally horizontal orientation such that a leading edge of the blade is oriented to face vertically upward. The method further includes providing a robotic device onto the wind turbine blade. The robotic device includes a 5

DK 2021 70372 A1 main chassis mounted atop the leading edge, first and second scanner support arms connected to the main chassis on opposing sides of the leading edge, and at least one NDT scanning element mounted on each of the first and second scanner support arms. The method further includes pivoting each of the first and second scanner support arms relative to the main chassis to position each of the NDT scanning elements above a portion of a side of the wind turbine blade, and moving, with a drive connected to the main chassis, the robotic device along a longitudinal length of the wind turbine blade. The method also includes performing longitudinal scans of sides of the wind turbine blade with the NDT scanning elements as the drive moves the robotic device along the longitudinal length of the wind turbine blade, and detecting with the NDT scanning elements whether any delamination conditions are present within the wind turbine blade based on the longitudinal scans performed. In one embodiment, the robotic device includes two NDT scanning elements mounted on each of the first and second scanner support arms. The method further includes moving the first and second scanner support arms to position each of the two NDT scanning elements so as to scan different portions of the sides of the wind turbine blade. In another embodiment, each of the NDT scanning elements includes an ultrasonic scanner. The method includes conducting ultrasonic scans with the NDT scanning elements to detect and identify any delamination conditions within the wind turbine blade. In one embodiment, the method includes detecting delamination conditions within the wind turbine blade based on an individual longitudinal scan of the wind turbine blade by each individual one of the NDT scanning elements.

In one embodiment, the wind turbine blade includes at least one longitudinally extending carbon fiber spar and a shell that is constructed from rows of fiber reinforced plastics. The method step of performing continuous longitudinal scans of the blade further includes moving at least one of the NDT scanning elements longitudinally along the at least one longitudinally extending carbon fiber spar, to thereby perform a longitudinal scan of the at least one longitudinally extending carbon fiber spar. In yet another embodiment, the wind turbine blade includes a plurality of longitudinally extending 6

DK 2021 70372 A1 carbon fiber spars and each of the first and second scanner support arms include at least two NDT scanning elements. The method of this embodiment further includes aligning each of the at least two NDT scanning elements on the corresponding side of the wind turbine blade and in alignment with the at least one carbon fiber spar such that afirst NDT scanning element is configured to detect whether any delamination conditions are present within the shell of the wind turbine blade and a second NDT scanning element is configured to detect whether any delamination conditions are present between the shell and the at least one carbon fiber spar. The method of this embodiment also includes moving the at least two NDT scanning elements longitudinally along the plurality of carbon fiber spars, to thereby detect delamination conditions within the wind turbine blade in one pass of the wind turbine blade by the robotic device.

In one embodiment, the method includes adjusting a pivotal connection of the first and second scanner support arms on the main chassis to thereby adjust an exact position of each of the NDT scanning elements along opposing sides of the wind turbine blade. In a further embodiment, the first and second support arms are configured to adjust, in a chordwise direction along opposing sides of the wind turbine blade, a position of each of the NDT scanning elements to maintain alignment with the at least one carbon fiber spar as the robotic device moves along the longitudinal length of the wind turbine blade. In yet another embodiment, the method further includes moving the robotic device into position using an unmanned aerial vehicle (UAV) secured to the robotic device.

The steps and elements described herein can be reconfigured and combined in many different combinations to achieve the desired technical effects in different styles of wind turbines, as may be needed in the art.

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DK 2021 70372 A1 Brief Description of the Drawings The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.

Fig. 1 is a perspective view of a wind turbine according to one embodiment of the invention.

Fig. 2 is a front view of a wind turbine blade of the wind turbine of Fig. 1.

Fig. 2A is a cross-sectional view of a side of the wind turbine blade shown in Fig. 2, taken along line 2A-2A, illustrating structural layers that form the wind turbine blade.

Fig. 2B is a cross-sectional similar to that of Fig. 2A illustrating delamination damage between the layers that form the wind turbine blade, the delamination damage being shown schematically exaggerated for illustrative purposes.

Fig. 3 is a top perspective view of a robotic device including an inspection system in accordance with embodiments of the present invention, the device being mounted in position on a leading edge of the wind turbine blade to conduct non-destructive test scans of the wind turbine blade.

Fig. 4A is a side view of the robotic device shown in Fig. 3 illustrating a first and a second scanner support arm of the inspection system in a stowed position.

Fig. 4B is a side view of the robotic device shown in Fig. 3 illustrating the first and second scanner support arms in a position for performing non-destructive test scans of the wind turbine blade.

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DK 2021 70372 A1 Fig. 5 is a cross-sectional view of a wind turbine blade being scanned by the robotic device illustrating the scanning operation of each side of the blade by scanning elements located on the first and second scanner support arms.

Fig. 6 is a top perspective view of a robotic device being mounted in position on the leading edge of the wind turbine blade, illustrating the generally continuous scan of the wind turbine blade by the inspection system of the device as it moves along the longitudinal length of the wind turbine blade.

Detailed Description With reference to Figs. 1 through 6, embodiments of a robotic device having an inspection system and a method for automatically scanning a wind turbine blade for damage are shown in detail. The robotic device is equipped with the inspection system to perform inspections of a wind turbine blade attached to the rotor hub at the top of the tower of the wind turbine. More particularly, the robotic device is configured to perform non- destructive test (“NDT”) scans of the wind turbine blade by using the inspection system to scan a longitudinal length of the blade. As will be explained in further detail below, in one embodiment, the inspection system includes at least one NDT scanning element supported from the robotic device by at least one scanner support arm configured to position the NDT scanning element to a side of the wind turbine blade to perform a longitudinal scan of the wind turbine blade as the robotic device moves therealong. These and other aspects will be described in additional detail below, and additional advantages and effects of the embodiments of this invention will be evident from the following description.

Throughout this application, reference is made to the robotic device performing NDT scans of a wind turbine blade to detect any “damage” to the blade. Generally speaking, “damage” means any degradation, structural or otherwise, of the wind turbine blade. For example, in some contexts "damage" may refer to the loss of cohesion between individual fibers (so called fiber splitting/debonding) or between laminate or other composite layers (delamination) that form the blade. In other contexts, “damage” may refer to trailing edge 9

DK 2021 70372 A1 and leading edge bond deficiencies, dry spots in laminate construction, coating cracks, wrinkles caused by non-straight fibers in the laminate, and other similar types of blade defects and/or damage. To this end, it will be understood that within the context of this application, the robotic device, and more particularly the inspection system, is capable of scanning a wind turbine blade for any damage that may adversely affect the performance and operation of the blade. Referring now to Fig. 1, a wind turbine 10 is shown to include a tower 12, a nacelle 14 disposed at the apex of the tower 12, and a rotor 16 operatively coupled to a generator (not shown) housed inside the nacelle 14. The rotor 16 of the wind turbine 10 includes a central hub 18 and a plurality of wind turbine blades 20 that project outwardly from the central hub 18 at locations circumferentially distributed around the hub 18. As shown, the rotor 16 includes three wind turbine blades 20, but the number of blades 20 may vary from one wind turbine to another. The wind turbine blades 20 are configured to interact — with air flow to produce lift that causes the rotor 16 to spin generally within a plane defined by the wind turbine blades 20. As the rotor 16 spins, the wind turbine blades 20 pass through the air with a leading edge 22 leading the respective wind turbine blade 20 during rotation. As shown, the wind turbine blades 20 in use are spaced apart from the ground surface by a significant distance, which normally renders inspection, maintenance and repair actions difficult, particularly with respect to the blades 20. However, the robotic device and inspection system of this invention improves the inspection process of a wind turbine blade 20 to make automated or semi-automated detection of any damage to the blade 20 more efficient, accurate, and reliable as will be set forth in detail below.

With continued reference to Fig. 1, a transport trailer 24 for storing and transporting the robotic device having the inspection system is shown. In this regard, the transport trailer 24 defines a storage space for holding the robotic device. The transport trailer 24 may be towed by a motorized vehicle (not shown) to transport the robotic device to the site where the wind turbine 10 requiring a blade 20 inspection is located. The robotic device may be unloaded from the transport trailer 24 and lifted into position on the leading edge 22 of the wind turbine blade 20 using a boom crane or flying vehicle, such 10

DK 2021 70372 A1 as an unmanned aerial vehicle (UAV), for example. In other embodiments, the robotic device may be stored in a container within range of the wind turbine 10 and then transported to the wind turbine 10 (such as by the aforementioned UAV) whenever a blade 20 inspection is necessary. As will be described in further detail below, the robotic device moves along the leading edge 22 of the wind turbine blade 20 to perform NDT scans of the blade 20 to check for any damage, such as delaminations. A detailed view of an exemplary wind turbine blade 20 is shown in Fig. 2, and more particularly a side 26 of the wind turbine blade 20, which may be of a known design. In this regard, the wind turbine blade 20 is configured as an elongate structure having an outer airfoil shell 28 that defines an outer surface 30 of the wind turbine blade 20. The outer shell 28 is disposed about an inner support element or spar structure disposed inside a hollow interior of the outer shell 28. The elongate blade 20 includes a root end 32 (shown in Fig. 1) which is configured to be coupled to the central hub 18 when mounted tothe rotor 16, and a tip end 34 longitudinally opposite to root end 32. The outer shell 28 may be optimally shaped to give the blade 20 the desired aerodynamic properties to generate lift, while the spar structure is configured to provide the structural aspects (e.9., strength, stiffness, etc.) to blade 20. As discussed in further detail below, the shell 28 and spar structures may form the layers of the wind turbine blade 20 that are being inspected by the robotic device for delamination damage. Further, each layer of the blade 20 may comprise several individual sub-layers formed from composite layers of material which are integrally formed or bonded to one another to form the structural layers of the blade 20. As such, these structural and sub-layers and their components are particularly vulnerable to loss of cohesion, debonding, and/or delamination damage over the expected lifetime of the wind turbine blade 20. To this end, the robotic device is configured to perform NDT scans the wind turbine blade 20 to inspect for degradation of this sort between and within the different layers of the blade 20, such as the shell 28 and spar structures, for example.

The outer shell 28 of the blade 20 may include a windward shell half and a leeward shell half that are coupled together along the leading edge 22 and a trailing edge 36 located 11

DK 2021 70372 A1 opposite one another across a chord of the blade 20. The outer shell 28 may be formed primarily from glass-fibre-reinforced plastic (GRP), and typically has a laminate structure comprising multiple composite layers or skins. The layers may each comprise a plurality of sub-layers of glass-fibre reinforcing fabric embedded in cured epoxy resin. Core material, such as foam panels, may be provided between the inner and outer skins in regions of the blade 20 where increased stiffness is required. Thus, the outer shell 28 typically comprises a plurality of rows of fibre reinforced plastics, each of which are subject to degradation in the form of loss of cohesion and/or delamination from normal use of the blade 20, for example.

While not shown entirely, the spar structure extends longitudinally along the length of the blade 20 between the root end 32 and the tip end 34, and typically extends a majority of the length of the wind turbine blade 20 (e.g., greater than 80% or 90% of the length of the blade 20). The spar structure includes at least one, and typically a plurality of longitudinally extending carbon fiber spars (e.g., spar caps) associated with respective windward and leeward halves of the shell 28. Typically, a shear web extends between the opposed spars and is designed to carry the shear loads on the blade 20. The spars are generally designed to carry bending loads on the blade 20. In any event, the longitudinally extending spars are typically integrated within the windward and leeward halves of the shell 28 such that the spars form part of the airfoil shell 28 and side 26 of the blade 20. However, the one or more spars may be separate elements adhesively bonded together and further to an inner surface of the shell 28. In another embodiment, one or more spars may be formed from a stack of pultruded fiber-reinforced composite strips, referred to generally as “carbon pultrusions.” Alternatively, the spars may have a laminate composite construction of a plurality of fiber layers, resin, and possibly core material. Turning now to Figs. 2A and 2B, a cross-section of the wind turbine blade 20 taken along line 2A-2A of Fig. 2 is shown. More particularly, Fig. 2A illustrates an exemplary embodiment of the some of the layers that form one side 26 of the wind turbine blade 20. For example, the layers shown may be the shell 28 and spar layers that form one side 26 12

DK 2021 70372 A1 of the blade 20 (e.g., the leeward shell half or the windward shell half), as described above. In this regard, the layers may be considered structural layers of the blade 20. Fig. 2B illustrates damage to those layers in the form of delamination, which the robotic device is configured to detect via NDT scans of each side 26 of the blade 20, as will be described in additional detail below. It is understood that the exemplary side 26 of the wind turbine blade 20 shown in Figs. 2A and 2B is representative of both the leeward and windward sides 26 of the blade 20. Thus, while reference is only made to one side 26 with respect to these figures, it is understood that Figs. 2A and 2B are representative of both sides 26 of the blade 20, including any layers of material that form blade 20, which may be scanned by the robotic device.

As shown in Fig. 2A, the exemplary side 26 of the wind turbine blade 20 includes the outer shell 28 bonded to a spar structure 38. The outer shell 28 may comprise a plurality of rows 40 of fibre reinforced plastics bonded together using a polymer-based resin, for example, along at least one bond line 42. In the embodiment shown, the spar structure 38 is formed of one longitudinally extending carbon fibre spar which includes one or more pultruded fiber-reinforced composite strips 44 in a stack to form the carbon fibre spar and spar structure 38. Alternatively, the spar structure 38 may have a laminate composite construction of a plurality of fiber layers, resin, and possibly core material. The spar structure 38 may include more than one longitudinally extending carbon fibre spar, such as two, three, or more coupled or bonded together. In any event, the spar structure 38 may be adhesively bonded or otherwise integrated with the outer shell 28 along a bond line 46.

Turning with reference to Fig. 2B, an example of delamination damage to the blade 20, and more particularly to one side 26 of the blade 20, is shown in detail. The delamination damage shown is along the bond line 46 between the outer shell 28 and the spar structure

38. As shown, the outer shell 28 has separated from the spar structure 38 to create a void 48 or gap therebetween, resulting in the surface 30 of the shell 28 being raised.

However, delamination damage could also occur along the bond line 42 between the rows 40 of fibre reinforced plastics that form the shell 28, for example. Delamination could also 13

DK 2021 70372 A1 occur in the spar structure 38 between the one or more pultruded fiber-reinforced composite strips 44, for example. In any case, the inspection system of the robotic device is configured to detect this and other types of damage within the wind turbine blade 20, as will be evident from the following description.

Fig. 3 provides an overview of one exemplary robotic device 60 that includes an inspection system 62 in accordance with embodiments of this invention. The robotic device 60 is shown in an operation position in this view for conducting NDT scans of the wind turbine blade 20 using the inspection system 62. As shown, the robotic device 60 includes a main chassis 64 (may also be referred to as a main body or frame) having one or more support elements 66 such as wheels or the like extending towards opposite sides of the leading edge 22 of the blade 20 when the robotic device 60 is mounted atop the leading edge 22 of the blade 20 as shown in this Figure. The support elements 66 may interact with or define part of a movement drive 68 that can move the robotic device 60 along the blade 20. In this embodiment, the robotic device 60 further includes an optional applicator tool 70 mounted on the main chassis 64 and configured to apply a coating material over the exterior surface 30 of the blade 20, for example, to perform repair actions to the blade 20, if needed. Although the applicator tool 70 is shown in this Figure to include a spatula- type device for spreading and forming a coating material into a shaped coating that fills in and covers up any damage to the blade 20, it will be understood that alternative types of applicator tools may be provided in other embodiments without departing from the scope of the invention.

The movement drive 68 is located on the underside of the robotic device 60 and is configured to engage with the leading edge 22 of the wind turbine blade 20 (or a portion of the blade 20 proximate the leading edge 22) to move the robotic device 60 along the leading edge 22, as demonstrated by directional arrows A1 in Figs. 4B. In this regard, the movement drive 68 may include one or more continuous tread drives, each having a continuous tread independently driven by at least one motor. Each continuous tread may 14

DK 2021 70372 A1 be generally U-shaped to conform to the shape of the leading edge 22 of the wind turbine blade 20. That way, the treads grip the leading edge 22 to move the robotic device 60. The treads may be formed from rubber, plastics, or other suitable moderate to high friction material for gripping the wind turbine blade 20, for example.

To this end, as the treads are driven, the robotic device 60 is moved at a steady pace along the leading edge 22 of the wind turbine blade 20 during inspection operations.

The robotic device 60 also includes a control system 72 shown schematically in Fig. 3 and implemented on known hardware and software platforms.

The control system 72 is operatively connected to the components of the robotic device 60, including the inspection system 62 and at least the movement drive 68 to thereby operate these elements.

More particularly, the control system 72 is capable of responding to inputs from components of the robotic device 60 and the inspection system 62 and/or from an offsite operator to modify the actions taken by the robotic device 60. The actions of the robotic device 60 and inspection system 62 may be modified based on real-time feedback or inputs detected by the robotic device 60 during inspection operations.

Additionally, a power supply 74 such as a battery pack may be mounted on the robotic device 60 for supplying power to components of the robotic device 60 such as the controller 72, the movement drive 68, and components of the inspection system 62, for example.

The power supply 74 may be configured to power those components and systems so that the robotic device 60 can perform NDT scans of an entire longitudinal length of the wind turbine blade 20 in one pass with the robotic device 60, for example.

Preferably, the power supply 74 is configured to power those components for multiple scans of one wind turbine blade 20, and even more preferably of multiple wind turbine blades 20, if needed.

The power supply 74 is shown schematically in Fig. 3. In the embodiment of the robotic device 60 shown in Fig. 3, the robotic device 60 defines a generally elongate shape defined between a front end 76 and a rear end 78, which typically faces towards the root end 32 of the blade 20 when the robotic device 60 is mounted on the leading edge 22. A central portion 80 is defined between the front and 15

DK 2021 70372 A1 rear ends 76, 78 and includes the center of gravity of the robotic device 60 and components of the inspection system 62, as described in further detail below.

Further examples of robotic devices are, for example, disclosed in DK Application Nos. PA 201970789 and PA 201970790, which are owned by the same Assignee as the present invention, and such robotic devices may be used in other embodiments with the applicator tool of the present invention. Further details of any exemplary robotic device can be understood from those prior patent applications in combination with the description provided herein.

With continued reference to Fig. 3, details of the inspection system 62 will now be described. As shown, the inspection system 62 includes a first support arm 90 operably coupled to one side of the main chassis 64 of the robotic device 60 and configured to support at least one NDT scanning element 92 for scanning one side 26 of the wind turbine blade 20 for damage. The inspection system 62 also includes a second support arm 94 operably coupled to an opposite side of the main chassis 64 of the robotic device 60 and configured to support at least one NDT scanning element 92 for scanning the opposite side 26 of the wind turbine blade 20 for damage. Thus, the first and second scanner support arms 90, 94 are configured to position NDT scanning elements 92 to either side 26 of the wind turbine blade 20 to conduct NDT scans of the blade 20. Preferably, the first and second scanner support arms 90, 92 are configured to place the corresponding NDT scanning elements 92 in an abutting or near abutting relationship with the outer surface 30 of each side 26 of the blade 20 during scanning operations. The NDT scanning elements 92 may be electrically coupled to the robotic device 60, and more particularly to the control system 72, for example. In one embodiment, the NDT scanning elements 92 include an ultrasonic scanner. However, various scanning elements or tools can be used to detect damage to a wind turbine blade and are within the scope of the present invention, such as vibrators for conducting a vibration analysis of the blade 20, thermographic sensors, X-ray imaging devices, and acoustic emission devices for an acoustic analysis of the blade 20. 16

DK 2021 70372 A1 The first and second scanner support arms 90, 94 are each pivotally connected to one side of the robotic device 60 and configured to articulate the supported NDT scanning elements 92 in a chordwise direction along the sides 26 of the blade 20. More particularly, each support arm 90, 94 includes at least two rigid arm elements 96 connected between a support plate 98 for supporting the NDT scanning elements 92 and an interface 100 on the corresponding side of the main chassis 64 of the robotic device 60. As shown, a first end of each rigid arm element 96 is connected to the interface 100 on the main chassis 64 at a first joint 102 and a second end of each rigid arm element 96 is connected to the support plate 98 at a second joint 104. The interface 100 may include a drive configured to articulate or pivot the arm elements 96 about joints 102 to thereby adjust the exact position of the NDT scanning elements 92 along the side 26 of the wind turbine blade 20 for scanning operations. In this regard, each interface 100 may be located on the chassis 64 at a location where the chassis 64 has a width that is wider than the leading edge 22 of the blade 20. That way, the first and second scanner support arms 90, 94 can pivot the corresponding NDT scanning elements 92 a distance down the side 26 of the blade without much interference from the outer surface 30 of the blade, for example. However, the arm elements 96 may deflect to allow a certain degree of bow or flex so that the support plates 98 and NDT scanning elements 92 have some lateral adjustability relative to the side 26 of the blade 20 to conform to the shape and size of the blade 20, 20 and to further accommodate for larger or smaller wind turbine blades 20. To this end, each interface 100 may be configured to pivot the corresponding support plates 98 and NDT scanning elements 92 towards or away from the side 26 of the blade 20 to adjust spacing of the NDT scanning elements from or towards the outer surface 30 of the blade 20 during scanning operations.

The arm elements 96 are configured to maintain a parallel arrangement as they are pivoted about the chassis 64 of the robotic device 60. The arm elements 96 may be connected to the corresponding support plate 98 at joints 104 by joint pins, for example, to allow the support plate 98 to freely move as the arm elements 96 are moved up or down at the interface 100 to adjust positioning of the NDT scanning elements 92. This configuration allows the support plate 98, and more particularly the NDT scanning 17

DK 2021 70372 A1 elements 92, to maintain vertical alignment along the side 26 of the wind turbine blade 20 during scanning operations. As shown, the support plate 98 for each of the first and second scanner support arms 90, 94 is configured to support two NDT scanning elements 92 in a vertical arrangement for scanning different portions of one side 26 of the wind turbine blade 20. However, it is within the scope of the invention for the plates 98 of the first and second scanner support arms 90, 94 to support fewer or more NDT scanning elements 92 as desired. In any event, each support plate 98 includes vertically aligned retainers, such as apertures, configured to receive corresponding NDT scanning elements 92 therein for coupling to the support plate 98. To this end, positioning of the NDT scanning elements 92 in the retainers may be adjustable. The NDT scanning elements 92 are arranged vertically, or in a stacked arrangement, on each corresponding support plate 98 so that the scanning elements 92 may scan different portions of the wind turbine blade 20. This allows the inspection system 62 to perform multiple NDT scans at different locations of one or multiple layers that form the blade 20, which can be accomplished in one sweep or pass of the robotic device 60 along the length of the blade. To this end, by one sweep or pass, it is meant that the robotic device 60 moves along the longitudinal length of the blade 20 from a first end to a second end.

Turning now to Figs. 4A-6, a series of operational steps are illustrated in accordance with one embodiment for inspecting for a wind turbine blade 20 for damage, particularly in the form of delaminations. In Fig. 4A, the robotic device 60 described in detail above is shown positioned on the leading edge 22 of the wind turbine blade 20 to be inspected. As shown, the robotic device 60 is positioned on the leading edge 22 proximate to the tip end 34 of the blade 20. In this regard, it is preferable to position the robotic device 60 at one end of the blade 20 (e.g., the tip end 34 or the root end 32) so that the robotic device 60 can perform an inspection of the entire length of the blade 20 in one pass by moving from one end of the blade 20 to the other. However, the robotic device 60 may be placed anywhere along the length of the wind turbine blade 20 to inspect only a section of the blade 20 or specific points along the blade 20 for damage, for example. 18

DK 2021 70372 A1 As shown in Figs. 4A and 4B, the wind turbine blade 20 is horizontally oriented and pitched to orient the leading edge 22 of the blade 20 to face vertically upward. Orientation of the blade 20 in this manner is preferable as it provides a relatively stable and relatively level environment so that the blade 20 may be accurately inspected by the robotic device

60. In Fig. 4A, the first scanner support arm 90 is shown in a stowed position with the NDT scanning elements 92 and arm elements 96 positioned alongside the chassis 64 of the robotic device 60. While not shown, the second scanner support arm 94 is similarly positioned. The first and second scanner support arms 90, 94 are positioned in the stowed position while the robotic device 60 is being transported to the wind turbine 10 or being mounted on the leading edge 22 of the wind turbine blade 20, for example.

In Fig. 4B, the first scanner support arm 90 is shown pivoted or articulated to a downward position along the side 26 of the wind turbine blade 20 to position the NDT scanning elements 92 over the outer surface 30 of the blade 20. While not shown, the second scanner support arm 94 is similarly positioned. In this regard, the robotic device 60 may be configured to align the support plates 98 and corresponding NDT scanning elements 92 of the first and second scanner support arms 90, 94 over a longitudinally extending carbon fibre spar of the spar structure 38, for example. The NDT scanning elements 92 for each of the first and second scanner support arms 90, 94 may then be used to conduct NDT scans of the blade 20 such as for any delamination damage to the spar structure 38 or between the spar structure 38 and the outer shell 28, for example. The inspection system 62 is programmed to maintain alignment with the longitudinally extending spar of the spar structure 38 as the robotic device 60 moves along the leading edge 22 by adjusting (e.g., pivoting or articulating) the first and second scanner support arms 90, 94 upwards or downwards in the chordwise direction along each side 26 of the blade 20, as demonstrated by directional arrows A2. This tracking ability allows the spar structure 38 and/or shell 28 to be inspected in one sweep of the robotic device 60. As will be described in further detail below, each NDT scanning element 92 may be configured to scan a different layer of the wind turbine blade 20 for delamination damage such that multiple 19

DK 2021 70372 A1 layers of the blade 20 may be inspected for damage in one sweep of the robotic device

60. Turning now with reference to Fig. 5, a detailed cross-sectional view of the wind turbine blade 20 being inspected by the robotic device 60 is shown. During inspection operations by the robotic device 60, the inspection system 62 is configured to position the first and second scanner support arms 90, 94, and more particularly the corresponding NDT scanning elements 92, to either side 26 of the leading edge 22 to inspect the blade 20. As shown, the NDT scanning elements 92 are positioned in a near abutting relationship with the outer surface 30 of the blade 20. The NDT scanning elements 92 may be abutting the outer surface 30 of the blade 20. In either case, the NDT scanning elements 92 are configured to inspect one or more portions or layers that form each side 26 of the blade 20 for delamination damage. The layers may be, for example, the outer shell 28 and its sub-layers and/or the spar structure 38 and any of its sub-layers, including the bonds 42, 46 or sub-bonds therebetween. In this regard, each of the first and second scanner support arms 90, 94 may include at least one, and preferably multiple NDT scanning elements 92 corresponding to each layer within the blade 20 to be inspected for damage. In the embodiment shown, each of the first and second scanner support arms 90, 94 includes two NDT scanning elements 92. Thus, a first NDT scanning element 92 may be configured to scan one side 26 of the blade 20 to a first depth D1 for delamination damage while a second NDT scanning element 92 is configured to scan the same side 26 of the blade 20 to a second depth D2 for delamination damage. Each scan depth D1, D2 may correspond to a different layer of the blade 20, such as the outer shell 28 and the spar structure 38, or the bond 46 between the two layers 28, 38. However, the same layer of the blade 20, such as the shell 28, for example, may be inspected at two different depths with two separate NDT scanning elements 92. Each of the first and second scanner support arms 90, 94 may include fewer or less NDT scanning element 92 as desired to detect delamination conditions present in any or all layers for each side 26 of the blade 20 in one pass by the robotic device 60. Thus, any individual one of the NDT scanning elements 92 is configured to detect delamination conditions within the wind turbine blade 20 based on an individual longitudinal scan of the wind turbine blade 20. To this end, 20

DK 2021 70372 A1 delamination damage may be detectable as voids 48, for example, within the detectable range or depth D1, D2 of each NDT scanning element 92. However, the NDT scanning elements 92 may be configured to identify other non-conformities or deformations within the blade 20, as set forth above.

As set forth above, the inspection system 62 is configured to detect whether any delamination conditions are present within the wind turbine blade 20 based on the longitudinal scans of each side 26 of the blade 20 from the one or more NDT scanning element 92. As shown in Fig. 6, this is completed by moving the robotic device 60 along the entire longitudinal length of the wind turbine blade 20, as demonstrated by directional arrow A3, to perform NDT scans 106 of the blade 20 for damage. The NDT scans 106 of the wind turbine blade 20 performed by the one or more NDT scanning elements 92 may be generally continuous longitudinal scans on each side 26 of the blade 20 or, alternatively, point or sectional scans.

The robotic device 60 which includes the inspection system 62 and the associated inspection method described in these embodiments allows for NDT scans of a wind turbine blade 20 to be performed without requiring human operators, rope access technicians on the wind turbine blade 20 itself, or removal of the wind turbine blade 20 from the wind turbine 10. Thus, the automated inspection of the wind turbine blade 20 performed by the robotic device 60 minimizes operational downtime needed for the wind turbine 10 to receive the appropriate inspections for blade 20 damage. Further, the inspection system 62 is capable of scanning an entire longitudinal length of the blade 20 for damage in one pass, including multiple structural layers that may for the blade 20, reducing overall inspection time. Thus, the inspection system 62 and method achieves several technical advantages and improves the maintenance field as it relates to wind turbines and wind energy generation. While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended 21

DK 2021 70372 A1 claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Thus, the various features of the invention may be used alone or in any combination depending on the needs and preferences of the user.

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Claims (17)

DK 2021 70372 A1 Claims

1. A robotic device (60) for performing non-destructive test (NDT) scans of a wind turbine blade (20) on a wind turbine (10), the device (60) characterized by: a main chassis (64) configured to be mounted on the wind turbine blade (20), which is horizontally oriented and pitched to orient a leading edge (22) of the blade (20) to face vertically upward, the main chassis (64) positioned adjacent the leading edge (22) of the wind turbine blade (20) and including a drive (68) that operates to move the device (60) along a longitudinal length of the wind turbine blade (20); first and second scanner support arms (90, 94) pivotally connected to the main chassis (64) and positioned on opposing sides of the leading edge (22) when the main chassis (64) is mounted on the wind turbine blade (20); and at least one NDT scanning element (92) mounted on each of the first and second scanner support arms (90, 94), each positioned so as to scan a side (26) of the wind turbine blade (20), characterized in that the NDT scanning elements (92) scan the wind turbine blade (20) longitudinally as the drive (68) moves the main chassis (64) along the longitudinal length of the wind turbine blade (20), the NDT scanning elements (92) being capable to detect whether any delamination conditions are present within the wind turbine blade (20) based on the longitudinal scans from the NDT scanning elements (92).

2. The robotic device (60) of claim 1, characterized in that the first and second scanner support arms (90, 94) are rigid, elongated arm elements (96) extending between a first end pivotally connected to the main chassis (64) and a second end carrying the at least one NDT scanning element (92).

3. The robotic device (60) of claim 1 or 2, characterized in that the wind turbine blade (20) includes at least one longitudinally extending carbon fiber spar (38) and a shell (28) that is constructed from fiber reinforced plastics, and characterized in that the first and second scanner support arms (90, 94) position at least one of the NDT 23

DK 2021 70372 A1 scanning elements (92) on the side (26) of the wind turbine blade (20) and in alignment with the at least on carbon fiber spar (38) to move longitudinally along the wind turbine blade (20) to scan the at least one longitudinally extending carbon fiber spar (38).

4 The robotic device (60) of claim 3, characterized in that one of either the first or second scanner support arms (90, 94) includes a first and a second NDT scanning element (92), and characterized in that the first NDT scanning element (92) is configured to detect whether any delamination conditions are present within the shell (28) of the wind turbine blade (20) and the second NDT scanning element (92) is configured to detect whether any delamination conditions are present between the shell (28) and the at least one carbon fiber spar (38).

5. The robotic device (60) of any of the preceding claims, characterized in that each of the NDT scanning elements (92) includes an ultrasonic scanner.

6. The robotic device (60) of any of the preceding claims, characterized in that a pivotal connection of the first and second support arms (90, 94) to the main chassis (64) is adjustable such that an exact position of each of the NDT scanning elements (92) can thereby be adjusted along opposing sides (26) of the wind turbine blade (20) for making the longitudinal scans of the wind turbine blade (20).

7. The robotic device (60) of claim 6, characterized in that the first and second support arms (90, 94) are configured to adjust, in a chordwise direction along opposing sides (26) of the wind turbine blade (20), a position of each of the at least one NDT scanning elements (92) to maintain alignment with the at least one carbon fiber spar (38) as the robotic device (60) moves along the longitudinal length of the wind turbine blade (20).

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DK 2021 70372 A1

8. The robotic device (60) of any of the preceding claims, characterized in that each individual one of the NDT scanning elements (92) is configured to detect delamination conditions within the wind turbine blade (20) based on an individual longitudinal scan of the wind turbine blade (20).

9. A method for performing non-destructive test (NDT) scans of a wind turbine (20) blade on a wind turbine (10), the method characterized by: operating the wind turbine (10) to move one of the wind turbine blades (20) to a generally horizontal orientation, and pitching the wind turbine blade (20) in the generally horizontal orientation such that a leading edge (22) of the blade (20) is oriented to face vertically upward; providing a robotic device (60) onto the wind turbine blade (20), the robotic device (60) including a main chassis (64) mounted atop the leading edge (22), first and second scanner support arms (90, 94) connected to the main chassis (64) on opposing sides of the leading edge (22), and at least one NDT scanning element (92) mounted on each of the first and second scanner support arms (90, 94); pivoting each of the first and second scanner support arms (90, 94) relative to the main chassis (64) to position each of the NDT scanning elements (92) above a portion of a side (26) of the wind turbine blade (20); moving, with a drive (68) connected to the main chassis (64), the robotic device (60) along a longitudinal length of the wind turbine blade (20); performing longitudinal scans of sides (26) of the wind turbine blade (20) with the NDT scanning elements (92) as the drive (68) moves the robotic device (60) along the longitudinal length of the wind turbine blade (20); and detecting with the NDT scanning elements (92) whether any delamination conditions are present within the wind turbine blade (20) based on the longitudinal scans performed. 25

DK 2021 70372 A1

10. The method of claim 9, characterized in that two NDT scanning elements (92) are mounted on each of the first and second scanner support arms (90, 94), and the method is further characterized by: moving the first and second scanner support arms (90, 94) to position each of the two NDT scanning elements (92) so as to scan different portions of the sides (26) of the wind turbine blade (20).

11. — The method of claim 10, characterized in that the wind turbine blade (20) includes at least one longitudinally extending carbon fiber spar (38) and a shell (28) that is constructed from fiber reinforced plastics, and the step of performing longitudinal scans is further characterized by: moving at least one of the NDT scanning elements (92) longitudinally along the at least one longitudinally extending carbon fiber spar (38), to thereby perform a longitudinal scan of the at least one longitudinally extending carbon fiber spar (38).

12. — The method of claim 11, characterized in that the wind turbine blade (20) includes a plurality of longitudinally extending carbon fiber spars (38) and each of the first and second scanner support arms (90, 94) include at least two NDT scanning elements (92), and the step of performing longitudinal scans is further characterized by: aligning each of the at least two NDT scanning elements (92) on the corresponding side (26) of the wind turbine blade (20) and in alignment with the at least one carbon fiber spar (38) such that a first NDT scanning element (92) is configured to detect whether any delamination conditions are present within the shell (28) of the wind turbine blade (20) and a second NDT scanning element (92) is configured to detect whether any delamination conditions are present between the shell (28) and the at least one carbon fiber spar (38); and moving the at least two NDT scanning elements (92) longitudinally along the plurality of carbon fiber spars (38), to thereby detect delamination conditions within the wind turbine blade (20) in one pass of the wind turbine blade (20) by the robotic device (60). 26

DK 2021 70372 A1

13. The method of any of claims 10 through 12, characterized in that each of the NDT scanning elements (92) includes an ultrasonic scanner, such that the step of performing longitudinal scans is further characterized by: conducting ultrasonic scans with the NDT scanning elements (92) to detect and identify any delamination conditions within the wind turbine blade (20).

14. The method of any of claims 10 through 13, further characterized by: adjusting a pivotal connection of the first and second scanner support arms (90, 94) on the main chassis (64) to thereby adjust an exact position of each of the NDT scanning elements (92) along opposing sides (26) of the wind turbine blade (20).

15. — The method of any of claims 11 through 14, further characterized by: adjusting the first and second support arms (90, 94) in a chordwise direction along opposing sides (26) of the wind turbine blade (20) to maintain alignment of each of the NDT scanning elements (92) with the at least one carbon fiber spar (38) as the robotic device (60) moves along the longitudinal length of the wind turbine blade (20).

16. The method of any of claims 10 through 15, wherein the step of detecting with the NDT scanning elements (92) whether any delamination conditions are present is further characterized by: detecting delamination conditions within the wind turbine blade (20) based on an individual longitudinal scan of the wind turbine blade (20) by each individual one of the NDT scanning elements (92).

17. The method of any of claims 10 through 16, wherein the step of providing the robotic device (60) onto the wind turbine blade (20) is further characterized by: moving the robotic device (60) into position using an unmanned aerial vehicle (UAV) secured to the robotic device (60).

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