NDT FOR WIND TURBINES

NDT techniques for wind turbines

Because mass production of wind turbines is fairly new, no manufacturing standards have been set yet. Efforts are now being made in this area on the part of both the government and manufacturers.

While wind turbines on duty are relied on to work 90 percent of the time, many structural flaws are still encountered, particularly with the blades. Cracks sometimes appear soon after manufacture. Mechanical failure, due to alignment and assembly errors, is common. Electrical sensors frequently fail because of power surges. Non-hydraulic brakes tend to be reliable, but hydraulic braking systems often cause problems

Manufacturing flaws on turbine blades

Manufacturing flaws can cause problems during normal operation. For example, blades can develop cracks at the edges, near the hub or at the tips . Fiberglass rotor blades are regarded as the most vulnerable components of a wind turbine.

Typical manufacturing flaws on the blades may be summarized as delaminations , adhesive flaws and resin-poor areas. Here are some specific flaws at particular locations:

•     Skin/adhesive: this is bad cohesion between the skin laminate and the epoxy or the epoxy is missing.
•     Adhesive/main spar: this is when there is no cohesion between the adhesive and the main spar.
•    De lamination in main spar laminate.

•    High damping in skin or main spar laminate, which could be caused by porosities or change of thickness of laminate.

Manufacturing flaws on the tower

A tubular tower is made of a lot of sheets of iron that are welded together. A flange is welded onto each end of the sections. The welding is checked thoroughly using ultrasonic NDT.

 NDT techniques at manufacture

Visual inspection

Relatively advanced NDT testing methods are used to examine rotor blades. The methods employed include penetrant testing and visual inspection with the use of miniature cameras or endoscopes.

At present, it appears that mechanical components aren’t tested at manufacture but the cause of their damage can be determined. For example, endoscopes are used for the visual inspection of planetary gear transmissions. However, damaged components are usually examined in a materials laboratory.

Ultrasonic NDT

An ultrasonic test can be carried out to investigate if any damage is present in the wind turbine blade. Ultrasonic inspection reveals these flaws quickly, reliably and effectively and is the most often used non-destructive composite inspection method in industry. The main advantage of ultrasound scanning is that it enables us to see

beneath the surface and check the laminate for dry glass fibre and delamination.

Tap test

The tap test can be used to verify some of the results from the ultrasonic test and it is also a good method to discover irregularities in the structure. The method is based on the fact that the sound emitted when knocking on the structure changes when the thickness or material type changes or when porosities are present. It could also be caused when there is a dis bond between the skin laminate and the main spar. There are three types of tap testing equipment; a manual tapping hammer, the ‘Woodpecker’ portable bond tester and the Computer Aided Tap Tester (CATT) system.

All the automated tap methods have the advantage that they can produce a print of the damaged area, which is both useful and a permanent record of the damage found. All the tapping methods work well for thin laminates, honeycomb structures and other sandwich panels but are not so effective on thicker parts.

 Infrared thermography

The adhesive joints are critical points in the blade structure. That is why they are inspected with particular care. Infrared (IR) scanners are used to examine the blade throughout its length, measuring exactly the same points each time. The scanner is able to see through the laminate and check the adhesive joint. It records temperature differences in the adhesive, possibly identifying flaws, and takes a series of pictures. If there are any doubts, a point can be highlighted

and later analyzed using electronic image processing. If flaws are found, they can almost always be repaired immediately.

Flaws and NDT in-service

As the force of the wind is so irregular, the driving mechanism of a wind turbine is subject to much greater dynamic loads. Virtually all components of a wind turbine are subject to damage, including everything from the rotor blades to the generator, transformer, nacelle, tower and foundation.Wind turbines do have regular maintenance schedules in order to minimize failure. They undergo inspection every three months, and every six months a major maintenance check-up is scheduled. This usually involves lubricating the moving parts and checking the oil level in the gearbox. It is also possible for a worker to test the electrical system on site and note any problems with the generator or hook-ups

Flaws on turbine blades

In-service flaws have been identified in the following report: Risø-R-1391(EN) ‘Identification of Damage Types in Wind Turbine Blades Tested to Failure’ Christian P. Debel, AFM. ISBN 87-550-3178-1; ISBN 87-550-3180-3  ISSN 0106-2840

Flaws on rotor bearings

Cyclic stresses fatigue the blade, axle and bearing material, and were a major cause of turbine failure for many years. When the turbine turns to face the wind, the rotating blades act like a gyroscope. As it pivots, gyroscopic precession tries to twist the turbine into a forward or backward somersault. For each blade on a wind generator’s turbine, precessive force is at a minimum when the blade is horizontal and at a maximum when the blade is vertical. This cyclic twisting can quickly fatigue and crack the blade roots, hub and axle of the turbine.

Spalling (breaking up into fragments) of rotor shaft bearings can result in cracked rings, and in some cases, revolution of the inner rings around the shaft causes cracks in the shaft that can result in a total loss of the turbine. illustrates what can happen when the rotor bearings fail (in this case the blades landed 1 km away after having crossed a road)

TESTING PROCEDURE

Acoustic emission

A substantial amount of work has gone on in AE since 1993. A fatigue test of a wind turbine blade which was conducted at the National Renewable Energy Laboratory shows that fatigue tests of large FRP wind turbine blades can be monitored by AE techniques and that the monitoring can produce useful information. AE testing procedures, developed during a laboratory blade testing programme, have been applied to an in-service wind turbine blade in 2003. In the Framework of the Non-Nuclear Energy Programme, JOULE III from 1998 to 2002, the partners successfully developed a methodology for the structural integrity assessment of wind turbine blades, either in-service, or during certification testing, based on Acoustic Emission monitoring during static or fatigue loading. Within the framework of JOULE III, specialized pattern recognition software for AE data analysis and wind turbine automatic structural integrity assessment has been developed

Full scale testing of wind turbine blade to failure

A 25 m wind turbine blade was tested to failure when subjected to a flap wise load. With the test setup, it was possible to test the blade to failure at three different locations. The objective of these tests is to learn about how a wind turbine blade fails when exposed to a large flap wise load and how failures propagate. The report also shows results from the ultrasonic scanning of the surface of the blade and it is seen to be very useful for the detection of flaws, especially in the layer between the skin laminate and the load carrying main spar. AE was successfully used as sensor for the detection of damages in the blade during the test.

Wireless detection of internal delamination cracks in CFRP

In this study, a wireless system using a tiny oscillation circuit for detecting delamination of carbon/epoxy composites is proposed. A tiny oscillation circuit is attached to the composite component. When delamination of the component occurs, electrical resistance changes, which causes a change in the oscillating frequency of the circuit. Since this system uses the composite structure itself as a sensor and the oscillating circuit is very small, it is applicable to rotating components. The wireless method is found to successfully detect embedded delamination, and to estimate the size of the delamination.

Structural health monitoring techniques for wind turbine blades

These experiments indicate the feasibility of using piezoceramic

patches for excitation and a Scanning Laser Doppler Vibrometer or piezoceramic patches to measure vibration to detect damage.

Further testing of different smaller damages and types of damage is needed to verify the sensitivity of the methods. The resonant comparison method can be used for operational damage detection while the operational deflection shape method produces non-symmetric contours that are an easily interpretable way to detect damage in a structure that is not moving.

Infrared thermography for condition monitoring of composite wind turbine blades

Infrared thermography has the potential for providing full-field non-contacting techniques for the inspection of wind turbine blades(10). For application to turbine blades, the sensitivity of the thermal imaging has been shown to be suitable for non-destructive examination during fatigue testing; furthermore, it is thought that for blades in situ, the wind loading conditions may be sufficient to create effects detectable by thermal imaging.

NDT in Aerospace Industry

Non destructive testing in the aerospace industry

The aersopace industry is leading the way in the application of non-destructive testing techniques

The simplest way to find out about a component’s structural or material properties is to quite literally push it to breaking point.
But while destructive testing can be an effective and economical solution for high-volume, low-cost components, it’s clearly undesirable for larger, more expensive systems. If you want to test the limits of a multi-million-pound jet engine, destroying it is a pretty drastic way to advance your knowledge.
Fortunately, there is an alternative. And a range of so-called non-destructive testing (NDT) techniques – which can be used to probe structures and materials either before they enter use or as part of a maintenance programme – are now widely used across a range of engineering sectors.
Such techniques are particularly useful for monitoring and testing the kind of high-value, safety-critical components used in the aerospace industry. Indeed, according to Peter Milligan, compliance manager with the British Institute of Non Destructive Testing (BINDT), NDT is now compulsory for many aerospace firms.’Most, if not all, aerospace manufactures have to have some form of NDT carried out on their products [in particular, rotating parts] as it is a safety-critical part of the production process,’ he told The Engineer. ’NDT is a vital part of the production process from a quality-assurance point of view, as it gives confidence that the parts being tested won’t have defects in them that could cause problems in future life cycles.’
The variety of techniques available can be roughly broken down into two areas: surface techniques, which are used to identify surface defects such as cracks and surface porosity, and sub-surface techniques – such as ultrasonic testing or radiography – that can be used to detect defects that lie under the material’s surface.
One of the most widely used NDT methods is penetrant testing, a technique in which a visible dye solution is used to reveal surface defects.
During this process, test objects are coated with a dye solution, excess dye is removed from the surface and any dye that has penetrated cracks in the surface is then revealed under ultraviolet light. GKN, which specialises in the development of composite components for the aerospace industry, is a major UK user of this technique.
Meanwhile, the most commonly used sub-surface inspection technique is perhaps ultrasonic inspection – a method that uses beams of high-frequency sound waves to detect sub-surface flaws. The sound waves travel through the material and are reflected by cracks or flaws. The reflected beam is then analysed to define the presence and location of flaws or discontinuities.
Ultrasonic testing is used in the aerospace industry to locate voids, cracks and laminations, as well as inspect welds and carry out thickness measurements. One major UK supplier of ultrasonic inspection equipment is Midas NDT, which supplies automated systems for companies including Rolls-Royce and GKN.
Another popular sub-surface technique, which like ultrasonics has its origins in the medical field, is radiography – the use of X-rays or gamma radiation to spot imperfections. Using this technique, radiation is directed through a part and the resulting image indicates imperfections in much the same manner as an X-ray shows broken bones. Used across a range of engineering sectors, industrial radiography is particularly useful for testing and grading welds.
But perhaps one of the most versatile NDT techniques is eddy current testing, which uses induced electrical currents to detect defects. Essentially, the technique uses an alternating current in a test coil to induce an alternating magnetic field in the component to be tested. This causes eddy currents to flow in the components – the flow of which is influenced by the presence of flaws or defects.
Though, in general, the technique is used to inspect relatively small areas and is therefore better suited for inspecting areas where damage is already suspected, it nevertheless has a variety of applications, from measuring material thickness to detecting corrosion damage. As eddy currents are affected by the electrical conductivity of materials, they can also be used to sort materials and determine, for instance, whether a structure has been exposed to high temperatures. The technique is used to make corrosion measurements on aircraft skins and in the walls of tubing for assemblies such as heat exchangers. Eddy current testing is also used to measure the thickness of paints and coatings.
Magnetic particle testing (MT) – another key tool in the non-destructive tester’s armoury – is specifically used for detecting flaws in ferromagnetic materials. During MT, a magnetic field is applied to the specimen and the behaviour of fine magnetic particles applied to the surface of the specimen is used to monitor the magnetic flux. If the material is damaged, flux ’leaks’ from the specimen’s surface, close to the flaw, attracting the magnetic particles to the area.
MT, like ultrasonics, radiography and eddy currents, is a fairly well-established technique. However, a range of other methods promise to provide the world of NDT with an even wider pallet of tools.
For instance, one method showing increasing promise in the aerospace industry is pulsed thermography, in which infrared cameras can be used to detect sub-surface damage. According to Dr Nick McCormick, a materials specialist at the UK’s National Physical Laboratory (NPL), the technique holds particular promise for detecting flaws in sections of composite materials. McCormick explained that a group at NPL has been investigating the use of thermography to probe barely visible impact damage (BVID) – small surface scars that could point to problems deeper beneath a material’s surface. ’You can have something that looks like a dimple on the surface but has actually delaminated some of the layers beneath and has reduced the strength markedly,’ he said.
However, by firing a rapid pulse of heat at the surface of the composite material and using an infrared camera to measure the temperature change over time, it’s theoretically possible to gauge the sub-surface state of the material. ’If there’s a delamination below an area, there’s an air gap,’ explained McCormick. ’If there’s an air gap it’s more insulating and the temperature won’t drop as quickly. You can use that to measure what might be going on below the surface.’
Elsewhere, Peter Milligan’s team at BINDT is working to create a certification scheme for an emerging technique called guided-wave testing – a form of long-range ultrasonic inspection.
Mostly used on long stretches of pipes that could be used to carry liquids or gases, the main purpose for this method is to detect internal defects such as corrosion and liner defects. A row of transducers is wrapped around the pipe, inducing a range of ultrasonic beams into the pipe and causing it to twist, which, in turn, allows the beams to travel the full circumference of the internal wall of the pipe. If there are any defects within the pipe, the ultrasonic wave will strike the defect and send a reflection back to the transducer ring, allowing engineers to calculate the location of the defect. This method also allows tests to be carried in areas that are often inaccessible.
Meanwhile, a non-destructive testing technique based on resonant frequency response is showing great promise in the aerospace industry.
Originally commercialised by US firm Vibrant, but refined for use in the aerospace industry through a partnership at Sheffield’s Advanced Manufacturing Research Centre (AMRC), process compensated resonance testing (PCRT) is said to detect hidden flaws more effectively than other NDT processes.
Talking to The Engineer’s sister title, MWP, Lem Hunter, chief executive officer for Vibrant, said that the technology works by subjecting a part to a range of resonant frequencies and recording its response. By comparing these results with known standard patterns, it’s possible to identify defective parts.
One of the most compelling uses of the technique is in turbine blade inspection. In the US, following Federal Aviation Administration (FAA) approval, the process has been adopted by Delta Airlines as a replacement for destructive sample-based tests. Delta is also using PCRT to probe aircraft wheels, fasteners and engine components.

 

More than 8. 3 billion tons of plastics made: Most has now been discarded

This is an infographic on plastic pollution.

Humans have created 8.3 billion metric tons of plastics since large-scale production of the synthetic materials began in the early 1950s, and most of it now resides in landfills or the natural environment, according to a study published in the journal Science Advances.

Led by a team of scientists from the University of Georgia, the University of California, Santa Barbara and Sea Education Association, the study is the first global analysis of the production, use and fate of all plastics ever made.

The researchers found that by 2015, humans had generated 8.3 billion metric tons of plastics, 6.3 billion tons of which had already become waste. Of that waste total, only 9 percent was recycled, 12 percent was incinerated and 79 percent accumulated in landfills or the natural environment.

If current trends continue, roughly 12 billion metric tons of plastic waste will be in landfills or the natural environment by 2050. Twelve billion metric tons is about 35,000 times as heavy as the Empire State Building.

"Most plastics don't biodegrade in any meaningful sense, so the plastic waste humans have generated could be with us for hundreds or even thousands of years," said Jenna Jambeck, study co-author and associate professor of engineering at UGA. "Our estimates underscore the need to think critically about the materials we use and our waste management practices."

The scientists compiled production statistics for resins, fibers and additives from a variety of industry sources and synthesized them according to type and consuming sector.

Global production of plastics increased from 2 million metric tons in 1950 to over 400 million metric tons in 2015, according to the study, outgrowing most other human-made materials. Notable exceptions are materials that are used extensively in the construction sector, such as steel and cement.

But while steel and cement are used primarily for construction, plastics' largest market is packaging, and most of those products are used once and discarded.

"Roughly half of all the steel we make goes into construction, so it will have decades of use -- plastic is the opposite," said Roland Geyer, lead author of the paper and associate professor in UCSB's Bren School of Environmental Science and Management. "Half of all plastics become waste after four or fewer years of use."

And the pace of plastic production shows no signs of slowing. Of the total amount of plastics produced from 1950 to 2015, roughly half was produced in just the last 13 years.

"What we are trying to do is to create the foundation for sustainable materials management," Geyer said. "Put simply, you can't manage what you don't measure, and so we think policy discussions will be more informed and fact based now that we have these numbers."

The same team of researchers led a 2015 study published in the journal Science that calculated the magnitude of plastic waste going into the ocean. They estimated that 8 million metric tons of plastic entered the oceans in 2010.

"There are people alive today who remember a world without plastics," Jambeck said. "But they have become so ubiquitous that you can't go anywhere without finding plastic waste in our environment, including our oceans."

The researchers are quick to caution that they do not seek the total removal of plastic from the marketplace, but rather a more critical examination of plastic use and its end-of-life value.

"There are areas where plastics are indispensable, especially in products designed for durability," said paper co-author Kara Lavender Law, a research professor at SEA. "But I think we need to take a careful look at our expansive use of plastics and ask when the use of these materials does or does not make sense."

Source- Materials provided by University of Georgia. Original written by James Hataway.

20-Story Earthquake-Safe Buildings Made From Wood

Researchers are testing a two-story wooden structure this week at the UC San Diego shake table.

A two-story wooden structure endured four different earthquake simulations on July 14, 2017 on the world's largest outdoor shake table here in San Diego. And it's still standing before more tests in the coming weeks.

The goal of the tests is to gather enough data to design wood buildings as tall as 20 stories that do not suffer significant damage during large earthquakes. That is, not only can occupants leave the building unharmed, but they can come back and resume living in the building shortly after a temblor.

"Designing buildings that are safe even during large earthquakes is hugely important. We are doing that -- and we are going further. We are working to minimize the amount of time buildings are out of service after large earthquakes. We are also focused on cutting the costs required to repair them," said professor Shiling Pei, an Assistant Professor at Colorado School of Mines who is leading the tests funded by the National Science Foundation (NSF) and a variety of industry sponsors.

Based on the insights gleaned from this current set of tests and related research, the team will return to San Diego in 2020 to build, shake, and ultimately burn an earthquake-resilient 10 story timber building on the UC San Diego shake table.

In the current tests of the two-story, 22-foot-tall structure, the researchers are studying the behavior of full-scale seismic safety systems made from advanced wood materials -- including rocking walls, which can rock during a temblor and then re-center back by itself, and a mass timber floor designed to withstand strong earthquakes. The wood is primarily cross-laminated timber (CLT), which is a relatively new, high-performance material made from layers of wood laminate.

"With the arrival of cross-laminated timber, we can start thinking about timber skyscrapers," said Pei. "CLT and mass timber more generally are part of a massive trend in architecture and construction, but the seismic performance of tall buildings made from these kinds of wood is uncharted waters."

During the July 14 test, the building and its seismic safety systems seemed to do well. Researchers first put the two-story structure through a simulation of the 6.4-magnitude Imperial Valley earthquake, which took place in 1979 near the U.S.-Mexico border. That test was followed within a few minutes by two back-to-back simulations of the the 1994 Northridge earthquake. After inspecting the building without finding significant damage, researchers then put the structure through simulations of the 1989 Loma Prieta earthquake and the 6.6 magnitude Superstition Hills earthquake, which took place in 1987 near the Salton Sea.

More shakes will follow in the next few weeks as researchers test different seismic safety designs and systems.

The researchers from a consortium of U.S. universities, with collaborators from industry and the public sector, are performing the tests on the UC San Diego shake table, the largest outdoor shake table in the world.The facility is part of NHERI@UCSD, an experimental facility at UC San Diego funded by the National Science Foundation as part of its Natural Hazard Engineering Research Infrastructure (NHERI) program. The facility is located at the Englekirk Structural Engineering Center at the UC San Diego Jacobs School of Engineering.

While some tall wood buildings have been constructed in recent years, they have either been built in areas thought to be seismically inactive or they have been constructed with seismic safety systems made from non-wood-materials such as concrete and steel.

Beyond Safety: Designing for Resiliency

Current seismic safety building codes aim to ensure human safety in large earthquakes, allowing buildings to stand long enough for occupants to leave unharmed. The building codes, however, don't necessarily ensure that occupants will actually have a building to return to. Designing buildings that are expected to be back in service soon after a large earthquake, and with minimal repair costs, is known as designing for earthquake resiliency.

"In a large earthquake, the people inside a building may be safe, but if the building frame is crushed, they won't have a building to return to. We want to improve on that situation," said Pei.

Resiliency is one of the key tenants of this multi-year research project focused on tall wood buildings using mass timber materials.

"Building owners want to know, after a large earthquake, 'How many months am I out?'" said Pei. "We want to be able to say to building owners, 'You'll be out for a week, and the building will likely just need repairs to a few systems that are designed to be damaged."

The 22-foot structure being tested this month is a minimalist system aimed at collecting the information required to design tall timber buildings that have this kind of earthquake resilience.

One of the key goals is to study how the different seismic safety systems interact with each other during realistic earthquake simulations.

"We have tested the rocking walls by themselves in the lab, but as structural engineers, we know that the system is not equal to the sum of its parts. There are interactions between the parts. That's why NHERI projects funded by the NSF are so critical. We are finally going to be able to get data on how the different components function as a system during strong earthquakes," said Pei.

The data the researchers collect during the two-story tests will be crucial for developing the design methodology for the 10-story building.

"It's exciting to see our earthquake shake table facility being used to design, test and validate resilient seismic safety systems made from innovative, renewable materials," said UC San Diego structural engineering professor Joel Conte, who is the principal investigator on the NHERI NSF grant that funds the shake table operations. "Our shake table enables researchers to test structural specimens at full-scale for severe earthquake ground motions, which is crucial for making the kinds of structural engineering advances that save lives and enhance the resilience of communities after natural disasters."

The researchers working on the two-story building are collecting data through more than 300 sensor channels in three phases of testing. Data is generated at pre-selected points to measure how the cross-laminated timber (CLT) panels bend and how the panels move relative to each other. Researchers are particularly interested in a system that allows the building to rock in response to an earthquake and on how the walls and floors interact during shaking.

In rocking wall systems, vertical, mass timber walls are connected to the foundation by post-tensioned rods that run up through the floor and special U-shaped steel energy dissipaters. The rods allow the wall to rock during an earthquake and snap back into its original upright position, minimizing the deformation and the resulting structural damage.

A consortium of universities is collaborating on this NSF project, including Colorado School of Mines, Colorado State University, University of Washington, Washington State University, Oregon State University, Lehigh University, University of Nevada Reno, and University of California San Diego.

The two-story investigative testing also received support from multiple industrial partners including Katerra; Simpson Strong-Tie; Tallwood Design Institute; DR Johnson Lumber Co.; the Forest Products Laboratory; City of Springfield, Oregon; the Softwood Lumber Board; and MyTiCon Timber Connectors.

Source- Materials provided by University of California San Diego. Original written by Ioana Patringenaru

INNOVATED WELDING TECHNOLOGY

FSO - Innovative welding technology helps to reduce weight

 The latest innovation from Scansonic makes it possible to implement fillet welds (using our "RLW-A" product) and also edge welds ("FSO"). The welding thus occurs on the facing sides of the sheet pair (the edges of two metal sheets that are lying adjacent to each other). A clever technology uses optical sensors to detect the sheet metal stack. Compensating movements from the integrated scanner systems are then able to precisely position the laser light on the union between the sheets.

The well-established "I (square-groove) weld on a lap joint" method is most typically used for laser welding. The very high power of the laser is concentrated on a small surface, so that economically feasible deep-penetration welding is possible.  Until now, other weld geometries were hardly feasible because of inaccuracies in the handling and clamping systems commonly employed, and because of the workpiece's dimensional tolerances.

The FSO processing optics enable reliable, front-face laser beam exposure, regardless of the robot's actual positioning accuracy, the workpiece, or the clamps in use. This self-guiding system is also equipped with oscillation technology (laser spot oscillation in the X and Y directions with up to 1 kHz) so that materials which are difficult to weld can nonetheless be welded together.

The FSO, with its facing surface welding technique, thus provides the economical application option which many users have longed required.  This is because the unique seam geometry enables  particularly short connecting flanges to be used. The result is reduced weight and less material for the component. The FSO also features an outstanding integrated clamping system which presses together the workpieces locally with up to 700 N. It is even possible to join together three metal sheets in one process step – thanks to our "Millistep" process, developed in cooperation with Volkswagen.

Test results from Scansonic's laser application centre indicate that this innovative aluminium-aluminium bond can be welded together with no hot cracking. The lab results also show that, owing to the beam oscillation technology used, the galvanized sheets can be joined together with no gap and almost no welding splatter. Mixed compound bonding, the tests show, is also possible.

Robotic Farm Completes 1st Fully Autonomous Harvest

Hands Free Hectare is an experimental farm run by researchers from Harper Adams University, in the United Kingdom.

It's harvest season in many parts of the world, but on one farm in the United Kingdom, robots — not humans — are doing all the heavy lifting. 

At Hands Free Hectare, an experimental farm run by researchers from Harper Adams University, in the village of Edgmond in the U.K., about 5 tons (4.5 metric tons) of spring barley have been harvested from the world’s first robotically tended farm. Everything from start to finish — including sowing, fertilizing, collecting samples and harvesting — has been done by autonomous vehicles on the farm, according to the researchers.

The team behind the project thinks that robotic technology could improve yields in agriculture, which is necessary if the world's growing population is to be fed in coming years.

The researchers tackled this problem by using commercially available agriculture machines and open-source software that is used to guide hobbyists’ drones.

"In agriculture, nobody has really managed to solve the problem of autonomy," said Jonathan Gill, mechatronics researcher at Harper Adams University, who led the project."We were like, Why is this not possible? If it's possible in drone autopilots that are relatively cheap, how come there are companies out there that are charging exorbitant amounts of money to actually have a system that just follows a straight line?"

The researchers purchased several small-size agricultural machines, including a tractor and a combine, a machine for harvesting grain crops. They then fitted the machines with actuators, electronics and robotic technology that would allow them to control the machines without the presence of a human operator.

"The first stage was to make it radio controlled," Gill said. "This was our first step towards autonomy. From that point, we moved on to preprogram all the actions that need to be performed into the autopilot system."

Gill's collaborator, Martin Abell, who works for Precision Decisions, an industrial agricultural company that partners with the university, explained that the system follows a certain trajectory with preprogrammed stops to perform certain actions.

"The vehicles navigate entirely based on the GPS, and they are just essentially driving towards targets that we predetermined," Abell said. "At different GPS targets, there are different actions designed to be carried out."

Abell said the researchers struggled to make the machines follow a straight line, which initially resulted in quite a lot of crop damage. However, the scientists think they will be able to fix the problem in the coming years and will eventually achieve better yields than a conventionally maintained farm of the same size could produce.

To monitor the field and take samples of the plants, the researchers developed special grippers attached to drones. As the drone flies above the field, the grippers can cut off some samples and deliver them to the researchers.

The scientists said that the robotic technology could enable future farmers to more precisely distribute fertilizers and herbicides, but could also lead to improvements in soil quality. Currently, to achieve all the required tasks in a reasonable amount of time, farmers rely on very large and heavy machines. In the future, they could use flocks of smaller robotic tractors and harvesters, the researchers said.

The farmer would, for example, be able to apply fertilizer only to the plants that are doing poorly and wouldn’t waste it on those that don't need it, the researchers explained.

"At the moment, the machines used in agriculture are large, they operate quickly, they cover large areas of ground quickly, but with it comes inaccuracy," Abell said. "Small machines working with smaller working widths would provide a means to bring the resolution down. Instead of a 100-foot (30 meters) sprayer, you would have a 20-foot (6 m) sprayer, and that’s just the beginning of making things smaller."

The Harper Adams team plans to use the robotically harvested spring barley to make a limited batch of "hands-free" beer that will be distributed to the project’s partners as a token of thanks.

In the coming years, they want to focus on improving the precision of the procedures and quantify the effects of the robotic technology on the yields.

Source- https://www.livescience.com

Suits That Turn Robots into Real-Life 'Transformers'

These exoskeletons could help robots perform a variety of missions. Clockwise from the top: Glider-bot, Walk-bot, Wheel-bot & Boat-bot

Just as one might don a wet suit to work underwater or a spacesuit to work in space, researchers are designing exoskeletons for robots so the machines can wear a variety of outfits tailored to different missions.

In experiments, self-folding, heat-activated origami suits created for robots could help the machines walk, roll, sail and glide, according to the new study.

"Imagine future applications for space exploration, where you could send a single robot with a stack of exoskeletons to Mars," study co-author Shuguang Li, a postdoctoral fellow at MIT's Computer Science and Artificial Intelligence Laboratory, said in a statement"The robot could then perform different tasks by wearing different outfits."

Unlike the shape-shifting robots in the "Transformers" films, in real life, existing bots are typically much less adaptable. Each part of a robot usually has a fixed structure and a single, defined purpose, making it difficult for robots to perform a wide variety of actions, the researchers said.

In contrast, animals can often change their shapes to adapt to their environments. For instance, caterpillars undergo metamorphosis to become butterflies, and hermit crabs can switch their shells.

The scientists drew inspiration from nature to develop a robot that could transform itself with different outfits that enable it to perform different tasks.

"If we want robots to help us do things, it's not very efficient to have a different one for each task," study senior author Daniela Rus, director of MIT's Computer Science and Artificial Intelligence Laboratory, said in a statement. "With this metamorphosis-inspired approach, we can extend the capabilities of a single robot by giving it different accessories to use in different situations."

The researchers used a small magnetic cube that they called "Primer." They placed the cube in an arena where they could use magnetic fields to make Primer move like a robot.

In experiments, the scientists had Primer move onto various plastic origami sheets mounted on hot plates. Turning on the hot plates could then make the heat-activated sheets fold around the cube into various shapes in roughly 3 minutes.

Each of the exoskeletons Primer could wear had its own advantages. For example, "Wheel-bot" had wheels that helped it to move twice as fast as "Walk-bot." "Boat-bot" could float on water and carry nearly twice its weight. And "Glider-bot" could soar through the air.

Primer can even don multiple outfits at once, like a Russian nesting doll, according to the study. It could add one exoskeleton to become "Walk-bot," and then interface with another, larger suit that allows it to carry objects and move two body lengths per second. After Primer was finished with a task, it could step into water to dissolve any exoskeleton the device wore in less than 1 minute, the researchers said.

Now that the scientists have shown that Primer can wear a variety of exoskeletons, future research could show that similar suits could be developed for motorized robots as well, said study lead author Shuhei Miyashita, director of the microrobotics group at the University of York, in England. Potential applications could include ingestible robots that could use several exoskeletons to perform a number of tasks in the body, such as removing objects and patching wounds, he said.

Future research will also aim to create even more functional exoskeletons, to perform tasks ranging "from burrowing in sand to driving through water," Miyashita told Live Science. The scientists would also like "to make these robots smaller and more intelligent, and potentially use different types of biomaterials" so they can perform long-term operations in the body, he said.

Miyashita and his colleaguesdetailed their findings online Sept. 27 in the journal Science Robotics.

Source- https://www.livescience.com