When a vessel is moored in severe weather, the forces acting on wires and chains can be extremely high. A mooring system may include several force sensors, each measuring the load on an individual wire or chain. The crew on board needs to know how heavily each mooring point is loaded and be able to act before limits are exceeded. This is one of many situations in which sensors from Norwegian company Scansense are used.

“Our customers place a very strong emphasis on quality. The equipment has to measure correctly and remain reliable for a long time – perhaps as long as 20 years – which places high demands on both robustness and reliability,” says Arve Olsen, Customer Success Manager at Scansense.

Up to 1,200 tonnes

The company has been developing and manufacturing force and torque transducers since the 1980s and primarily supplies the offshore, maritime and energy sectors. Its transducers are used in applications including mooring systems, winches and cranes, with measurement ranges from around 1 tonne up to 1,200 tonnes.

“We may be dealing with loads of hundreds of tonnes, and a measurement error of one or two per cent represents a very significant force. Things can quickly go wrong,” says Arve Olsen.

The sensors are primarily based on strain gauges, in which metal elements deform when subjected to a load. The deformation changes the electrical resistance, which can be measured and converted into a signal. But for the measurement value to be reliable, the transducer needs to be calibrated.

Scansense has its own reference transducers, which are used to calibrate the transducers supplied to customers. These reference instruments must, in turn, be checked against an even more accurate reference. This is where RISE comes in.

“We have twelve reference transducers in total, ranging from approximately 5 to 300 tonnes, which are calibrated by RISE every year,” says Arve Olsen.

This creates an unbroken chain of traceability: from the transducers used by Scansense’s customers, through the company’s own reference transducers, back to the national measurement standards at RISE.

Driving the transducers from Norway to Borås

When Arve Olsen visits RISE in Borås, he follows the calibration process at the Swedish National Laboratory for force and torque. Jan Andersson, TIC Engineer at RISE, mounts Scansense’s reference transducers in a machine capable of generating very high forces, together with RISE’s own reference force transducers.

“The machine can generate forces of up to 6 MN, corresponding to approximately 600 tonnes. The force is generated by a large hydraulic piston pressurised from below. But the quality of the measurement comes from our reference force transducers, which are themselves calibrated against a deadweight machine. During calibration, we compare the readings from our reference transducer with those from Scansense’s equipment,” says Jan Andersson.

Arve Olsen is on site because Scansense transports the reference transducers from Norway to Borås themselves. This makes it possible to limit production downtime to just two or three days.

“RISE takes very good care of us and completes the work within a very short time. We can plan well in advance and book a time that suits our production schedule. But the main reason we have chosen RISE is the high quality and low measurement uncertainty of the calibrations. It shortens the traceability chain and reduces the uncertainty in our own calibrations,” says Arve Olsen.

Creating a chain of trust

Traceability is important all the way from the equipment delivered to the customer back to the national measurement standards at RISE. It is also something required by customers, standards and specifications. But for Arve Olsen and his colleagues, reliable measurements ultimately come down to something much more tangible.

“When our customers are out in the North Sea, the sea is rough and they are lifting something while people are working on deck, they have to be able to trust that the information from the instrument is correct. Traceability creates a chain of trust that is extremely important to us,” says Arve Olsen.

Large parts of Sweden’s water infrastructure were built during the 1950s, 60s, and 70s and are now in need of extensive maintenance. On Tjörn, an island municipality with many scattered holiday homes, the challenge is particularly significant due to the extensive pipeline network in relation to the number of residents. Until 2020–2021, nearly half of the drinking water produced was lost.

– The national average for non-revenue water is around 17 percent, meaning water that is lost before it reaches customers, often through leaks. Our leakage levels were extremely high, and we wanted to bring them down significantly, says Tobias Hansson, Project Manager for IT and Automation at Tjörns Vatten och Avlopp.

Investments Reduced Major Leaks

Between 2018 and 2021, major investments were made in the main distribution network. This reduced leakage and eliminated many of the major leaks.

– Previously, we experienced around 30 major leaks per year. Today, that number is down to five or six minor or medium-sized leaks. The investments made a significant difference, but over time it became more difficult to locate the remaining leaks and determine where maintenance efforts should be prioritized, says Tobias Hansson.

Smart Metering

To take the next step, the municipality launched a project in 2021 together with RISE and other partners. The aim was to use smart water meters and new measurement methods to more easily detect leaks and improve maintenance planning. Since then, the distribution network has been divided into several zones equipped with connected district meters, and around 3,500 of the municipality’s 5,200 properties have been fitted with smart water meters. Olle Penttinen, a researcher at RISE, has played a leading role in the project and subsequent initiatives.

– By collecting measurement data from the water treatment plant, water towers, district meters, and property meters, we can calculate water balances for different parts of the network. This allows us to see how much water is supplied to an area and how much is actually consumed. The difference may, for example, be due to leaks or losses in the production process, says Olle Penttinen.

Open Platform

RISE has worked both on ensuring measurement quality and on developing the platform where data is collected, managed, and presented through a user interface. An important principle has been to ensure that the solution remains open and does not lock the municipality into a specific vendor.

– The municipality retains full ownership of all data and can add new functionality as needed. The platform can also be used for applications beyond water and wastewater management, says Olle Penttinen.

Easier Leak Detection

When the distribution network is divided into smaller zones, it becomes easier to pinpoint problems. By comparing how much water is supplied to an area with how much is actually consumed, deviations and leaks can quickly be identified. The information is presented in a dashboard with maps used for both operational monitoring and maintenance planning.

– Previously, our technicians had to search across the entire island. Now we can quickly narrow the problem down to a specific area where the leak is located. We spend far less time searching and are also able to detect more smaller leaks than before, says Tobias Hansson.

The municipality can also take a more strategic approach to maintenance.

– Emergency repairs are very costly. If we can instead allocate resources to planned maintenance, we may be able to replace several hundred metres of pipeline rather than simply repairing a single leak. This improves the quality of the network and is far more cost-effective.

Reduced Water Production

Today, leakage stands at 3.7 m3 per kilometre of pipeline per day, which is in line with the national average. As leakage levels have decreased, the need for water production has also declined, resulting in lower chemical consumption, a reduced climate footprint, and allowing the municipality to avoid major infrastructure investments.

– Previously, we operated the water treatment plant at full capacity and had no room to increase production. Today, we have greater margins in the system and have been able to avoid investments of up to SEK 80 million, says Tobias Hansson.

Efforts to reduce water losses are continuing, even though the current levels are considered relatively good.

– Especially considering the length of pipeline we have per customer. Not all of it is leakage either, some water losses are a natural part of the production process, says Tobias Hansson.

Can Also Help Property Owners

The smart meters also create new opportunities to detect leaks at individual properties.

– We can identify changes in consumption patterns and detect suspected leaks in buildings. In one case, we noticed unusually high water consumption that turned out to be caused by a leak. We contacted the property owner, who was able to shut off the water before any major damage occurred, says Tobias Hansson.

He emphasizes that even small leaks can become costly over time.

– Today, this process is handled manually, but in the future it could be automated, says Tobias Hansson.

Olle Penttinen at RISE also sees further opportunities going forward. Current regulations require water meters to be replaced every nine years, regardless of whether they are functioning correctly or not.

– With the help of the algorithms we have developed, it may be possible to identify meters that are providing inaccurate readings and replace them only when necessary rather than at fixed intervals. This could save both time and money, and is something we would very much like to explore further in future projects, says Olle Penttinen.

In the MyFab Chalmers cleanroom, the air is extremely clean and free from particles such as dust, pollen and other contaminants. This is a prerequisite for the sensitive processes carried out here. The microchips are so small that a single dust particle can be larger than the components on the chip. Before entering the facility, a careful multi-step procedure is required to put on full protective clothing.

“It takes some getting used to if you’re not familiar with it, but for those of us who work here and go in and out several times a day, it’s quite straightforward,” says Hans He, researcher at RISE.

He is in the cleanroom together with fellow researcher Naveen Shetty to manufacture so-called quantum Hall elements and quantum Hall arrays in graphene. The chips are produced using lithography, a method in which an electron beam is used to draw extremely small structures onto the material – in this case graphene of the highest quality.

“Right now we are inspecting the graphene samples before continuing with the rest of the production process. They must be completely defect-free for everything to work. From graphene sample to finished chip takes about a week here in the cleanroom,” says Hans He.

Precision measurements at the National Laboratory for Electrical Quantities

Resistance and voltage are the cornerstones of electrical measurements. To ensure reliable measurement results, calibrated measurement instruments are required, and the quantum Hall chips serve as the reference point at the top of the calibration chain for resistance. Once the chips are completed, they are transported to the National Laboratory for Electrical Quantities at RISE in Borås. There, precision measurements are carried out for several weeks before they are ready to be used.

'“We have worked for several years on the realization of the resistance unit using the quantum mechanical phenomenon of the quantum Hall effect and graphene, and have, among other things, published our successes in Nature Communications,” says Hans He.

The classical Hall effect occurs when an electric current passes through a material in a magnetic field. A voltage is then generated transversely across the material. The stronger the magnetic field, the larger the voltage becomes. In ordinary materials, this relationship is linear. But in extremely thin materials – two-dimensional systems – at very strong magnetic fields and low temperatures, something unexpected happens. For certain magnetic field values, the transverse resistance takes on exactly defined values that depend only on fundamental constants of nature. This quantum mechanical phenomenon is called the quantum Hall effect.

“With the quantum Hall effect, we obtain resistance values that are extremely stable and well defined, which makes them perfectly suited for the realization of the unit of resistance,” says Hans He.
 

Graphene opens new possibilities

The quantum Hall effect has been used for a long time. What is new is the use of graphene, which makes it possible to create quantum Hall elements that can operate at higher temperatures, higher currents, and lower magnetic fields, together with the ability to connect many quantum Hall elements into so-called arrays.

“With a single quantum Hall element in graphene we obtain an exact resistance level close to 12.9 kΩ. But resistance values used in industry can be several orders of magnitude lower or higher. To reach other resistance levels, several steps of secondary calibrations are required, and each step increases the measurement uncertainty. To get around this, we have developed methods to connect many elements into arrays, making it possible to choose an arbitrary resistance level for the realization,” says Hans He.

Development in three steps

Hans He describes three steps for the development. The first step is individual quantum Hall elements made from graphene, which are now moving toward international standardization and are already used today in comparison measurements between national metrology institutes. The second step is quantum Hall arrays.

“So far we are almost alone in the world in achieving the stability and quality required for the arrays, so it will take some time before this can become an internationally standardized method,” says Hans He.

One limitation of quantum Hall arrays is that the resistance level is determined during manufacturing (for example fixed to 100 Ω). The third step is therefore programmable arrays, where the user can set the desired resistance level in real time using a single chip.

“This is a long-term goal and requires extensive research, but it has the potential to become the ultimate resistance standard. Voltage standards based on another quantum phenomenon, the Josephson effect, have already completed this journey and are today programmable,” says Hans He.

Strong international interest

The technology is already used internationally. RISE collaborates with and supplies the world-leading chips to national metrology institutes in countries such as the United States, France, Canada and South Korea, and sells chips commercially to the Canadian measurement instrument manufacturer Measurements International Ltd.

“The interest in the technology is growing. We receive many enquiries, we are invited to an increasing number of research collaborations, and the technology we have developed is actively used both in research and in commercial activities,” says Hans He.