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An independent publication

www.governmenteuropa.euOctober 2018 • Issue 27

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the One Health approach

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The standard inspection method for

quality assurance of the exterior

surfaces of wind turbines is to

employ people trained as rope access or

industrial climbers, but this is not the only

way. This article, by Robert Hörmann of Aero

Enterprise in Austria, outlines (using his

company's products) how drones can

undertake visual inspection of turbines, and

then supporting software and archiving can

be used to analyse the data. As the author

admits, drones and airborne access will

never be a complete substitute for manned

inspection, and there will always be the need

for rope access workers, but he shows that

there are many advantages to drone-based

inspection together with software analysis,

automated reporting and archiving.

Aero Enterprise GmbH, a young company located

in Linz, Austria, is active in the field of airborne

quality assurance. The company was founded in

2013 and provides its service with a

comprehensive system consisting of a helicopter-

type flight-robot (drone) called AERO-SensorCopter,

and a client-based AERO-Software package,

consisting of a free license AERO-View and a fee-

based license, AERO-Lyse. The whole analysis and

reporting software is supported by a database in

the background. Data mining and machine learning

tools enable clients to use the data not only for

statistics about the present state of the turbine but

to predict upcoming demand for maintenance. This

allows customers to review, prioritize and optimize

their repairs campaigns.

Customers are operators of wind farms, service

companies, insurance companies and original

equipment manufacturers, as well as technical

experts in this field. With primary focus in the

wind-energy market the technology can also be

applied to all other kinds of vertical objects and

helps to reduce maintenance and long-term

aftersales costs.

Acquisition of dataWith the proprietary AERO-SensorCopter, the rotor

blades, nacelle and spinner of a turbine can be

inspected visually. On request the drone can take

a closer look at welding seams or at the transition

area from concrete to steel on hybrid towers.

During the company's planned next step into the

offshore market, inspection of the foundation will

also be taken into consideration.

The electronic stabilised and gimballed sensor

head is capable of sweeping up 70, and down 90

degrees each way and is equipped with two

synchronised camera systems running in parallel,

providing infrared and high-resolution images.

Robert Hörmann explains the importance of airborne inspection forproviding quality assurance of wind turbines over a lifetime

Intelligent airborneinspection

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A theoretical resolution of up to 12 pixels per

square millimetre of the object can be achieved

with the 42 megapixel camera and lens, but in

practice the achievable resolution can vary

depending on distance, illumination and vibration

(e.g. caused by strong gusts of wind). The infrared

camera provides real-time temperature data from

the object, which can give extra information about

the situation below the surface. This is very

interesting when looking at the bonding areas of

the upper and lower outer shell of the blade along

the main beam.

The modular concept allows other payloads to be

launched with the system, either standalone or

partially integrated into the flight system

(autopilot). Except for launching and landing, the

whole flight process is fully automated and the

drone generally flies close to the object at a

distance between 5-10m.

Due to the helicopter design inspection can be

done in wind speed conditions up to 14m/s

(50km/h or 27 knots). For best results the rotor

system first has to be set so that the blades are

roughly in a Mercedes-star position, with one

blade looking straight up (no bolting is needed,

only breaking action). Then a complete

flight along the blades from all four sides

is performed.

Analysis of dataAfter some special post-processing works on the

gathered data, the whole data package is

uploaded to the database. Now, the infrared and

normal image data collected are displayed in

Aero Enterprise's self-developed, client based

analysis software called AERO-Lyse. The

customer, the dedicated expert or Aero Enterprise

itself can now identify, classify and document the

existing damaged areas visually with support of

a 3D environment for better orientation. The

damaged areas can easily be marked with the

help of pop-up windows and menus, providing

pre selections and standardised sentences with

respect to the selected damage. Information on

dimensions and area sizes of anomalies are also

available instantly. With the help of infrared

pictures and passive thermography extra

information from temperature differences on the

surface is available and this can be used, for

instance, to detect hot spots which may be an

indication of a delamination of the outer shell

against the main beam.

When the analysis reaches a point on the object

where a damaged area was found from an earlier

inspection, a message comes up asking if you

would like to compare the past and present data.

With this change in detection, which is possible

because of the interaction of the front-end with

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the database in the background, consistent

documentation is assured.

Finally, with the click of a button an automated

report in pdf format can be generated. The whole

process from data acquisition to a ready to use

report takes only 2-3 working days.

On request, it is also possible to produce filtered

data or reports (e.g. only the pictures with

damage information needed for the customer's

enterprise resource planning (ERP) or interface

could be provided).

Storage of dataThe database stores data as a backup, but also,

with the implementation of data mining and

machine learning, can provide statistics and deep

knowledge about future demand for predictive

maintenance. The database is also the source for

customisation of different classifications

standards or changes in language on the front-

end software. Stored data is also the linkage

which closes the quality cycle at the next

inspection period, where old and new data can

be compared. Most of the earlier human-based

subjective interpretation of data can be ignored

as the system provides a more objective

statement. We call the first flight on the turbine

the 'digital birth certificate'. So this changes the

maintenance philosophy from a reactive to a

proactive or even predictive way.

Advantages of airborne inspectionTime and costsOne of the biggest advantages of this system lies

in the saving of time for the inspection. The

positioning of the ground station and the wind

turbine rotor, calibration, inspection and data

transfer takes about two hours in total. The

complete scan of the rotor system, nacelle and

spinner takes only 25-40 minutes. This is

significantly faster than a review by industrial

climbers, especially for offshore turbines. As a

result, the downtime for a wind turbine can be

reduced on average by approximately 3 hours

onshore or up to 14 hours offshore. Depending

on distances, two to four wind turbines can be

inspected per day.

Quality and traceabilityWith a repeated airborne inspection, a

continuous documentation of the system status

can be made, since the recorded images can be

viewed and compared at any time. With the exact

determination of the damage locations, the year-

by-year changes in points affected are

monitored. The extra digital information and data

on earlier (or already known) problems on the

blades, which can be related to factors such as

production year, batch, site location or wind

levels, increases the type and level of evaluation

quality and improves traceability.

Accessibility and efficiencyThe ability to inspect the rotor systems of

turbines faster and the more convenient

collection and evaluation of data makes the

whole process more efficient and comparable.

In addition, the capability to operate at wind

speeds up to 14m/s and a minimum flight time

of 30 minutes opens extra room for

accessibility, especially in the time-consuming

offshore business.

TechnologyWith the digitalised collection of data, it is easy to

connect different work steps to other automated

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processes. Not only can the collected data

interface with the customer's ERP system

but there is also the potential to connect the

visual-based knowledge with vibration and

metrological-based information to generate deep

system knowledge and provide the next step into

the future in the direction of deep learning and

big data.

Health and safety and planningThe weather may limit when humans can

undertake inspections. But there are also other

limiting human factors like subjective decisions,

work time frames, illness, simple mistakes or

even casualties or fatalities which can cause a

chain of inefficiency in planning.

Although no one likes to mention it, inspections

by climbers may cause damage to the structure

because of inattention or accidents. We have

seen a lot of damage obviously caused by

industrial climbers such as bent and chopped

vortex generators damaged by someone

stepping on them or slightly loose gurney flaps

ripped off with the rope during the climb along

the blades. The bigger and more efficient

turbines become in the future, the more

sophisticated their aerodynamic features and

attachments. Think of the harm it could cause (to

both the person and the structure) when a rope

worker has to fight with the wind and hits against

the dino-tails at the edge of a rotor blade.

Finally, there are costs in the form of cash, time

or even reputation. An airborne inspection can

help increase the yearly maintenance output and

simultaneously helps to minimise the physically

exhausting hands-on work on the blades in harsh

weather conditions.

Drones and airborne access alone will never be a

complete substitute for manned inspection and

there will always be the need for rope workers.

But airborne inspection can be a cost-reducing

and supporting aftersales element to provide

quality assurance over the lifetime of a plant.

However, to benefit from the advantages a change

in paradigm may be needed, as the wind energy

sector can sometimes be very conservative and

not always open to innovation. Future orientated

companies who are open for new developments

are welcome to contact us. We are looking

forward to testing partners and further potential

cooperation partners in both business fields,

onshore and offshore wind.

Robert Hörmann is CEO/CTO and Founder of Aero

Enterprise. His roots are in aviation as an aircraft

mechanic, officer and military pilot with the

German Air Force. After military service he worked

in several companies in Europe in the field of

technical sales and business development before

he became self-employed in 2013.

Robert HörmannFounder & CEOAero Enterprise GmbH+43 7435 21110 100office@aero-enterprise.com

What is the partner programme?The partner model is based on a division of labour between you as a co-operation partner and AeroEnterprise. The on-site inspection will not be conducted by Aero Enterprise, but by you with the helpof your own conventional DJI consumer drone.

Aero Enterprise assists you in finding a recommended drone and the right equipment and helpsyou in theory and practice in the beginning and aids in teaching you how to use the AERO softwarepackage for evaluation, interpretation and automatic reporting.

Process flow:For the condition detection of the rotor blades1) Data collection with consumer drone and data upload to the Aero Enterprise Server

The data collection is done with a consumer drone (e.g., DJI Inspire 2 or Matrice) by you as adrone pilot. Aero Enterprise supports you regarding flight procedures on the object, process,data handling through training, webinars and documents.

2) Data preparation by Aero Enterprise & Provisioning for you as a partnerThe preparation of the data or the post-processing is carried out by Aero Enterprise. These arespecific activities such as: exact height determination, positioning in space, image nameadjustments, pre-classification of the pictures regarding extra tags like leading edge, trailingedge, rotation angle calculations, allocation of sheet numbers in depending on the rotor position,etc. Then the data for you is customised, secured and ‘ordered’ to be provided to our server.These are encrypted directly via VPN tunnels. The data is therefore not in a cloud.

3) Analysis, qualification and classification of the data by Aero Enterprise or you as a partnerWith the AERO-Lysis license software developed by Aero Enterprise you can examine the data,mark, measure, document and classify defects. At the end you will get after a short timedocumentation of the overall condition of the plant ‘by mouse click’ via an entire status report indigital and/or physical form (PDF). This includes the evidence of the damage to the correspondingpositions, as well as the footage of the entire plant. The report can feature your branding in theform of logos and sub-information.

Requirements for Cooperation Partnersn You need to have a drone license for the respective country.

n Drone (type DJI Inspire 2 or Matrice) – flight certificated to use in the respective country.

n Flight system needs to have an insurance.

n Ideally, first practical model flight experience and/or familiar with DJI products for more than a year.

n NOTE: For the wind-turbine Experts it might also make sense to partner with a local drone-pilot or vice-versa

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