AS ANY unicyclist knows, balancing on one wheel while staying in one spot is pretty tricky. But a robot that can do just that could be used to squeeze into tight spaces during search and rescue missions, or possibly even as a form of transport.

Most wheeled robots have more than one wheel, but this means they need a chassis – something that gets in the way when trying to squeeze into gaps. Mono-wheeled robots would avoid this problem. But while the same gyroscopic effect that lets a spinning top balance as it spins also helps keep a moving wheel upright as it turns, once the wheel stops, balance and control become much harder.

Previous efforts to create a mono-wheel that is stable when stationary, like the Gyrover, developed by Ben Brown at Carnegie Mellon University in Pittsburgh, Pennsylvania, have a second wheel that spins within the first to act as a gyroscope. But this uses a lot of energy.

So Patryk Cieslak, a PhD student at AGH University of Science and Technology in Cracow, Poland, and colleagues decided to take a different approach. Their robot is packaged within a single wheel: its motor, battery and controls remain stationary in the centre of the wheel while a rubber tyre rotates around the outside.

To keep it upright, the team have placed a weighted lever that can tilt to either side within the body of the wheel (see diagram). If the wheel starts to fall to the right, for example, three sensors will detect the movement: an inclinometer to detect tilt, plus an accelerometer and a gyroscope to detect changes in direction. These then send a signal to a control circuit to move the lever to the left to provide counter-balance. By making constant adjustments, the lever keeps the wheel upright (Robotics and Autonomous Systems, ).

“There are many potential uses for this kind of robot because of its thin body, simple construction, good mobility and traction, and the efficiency of using only one wheel,” says Cieslak. He says that the next step is to set the robot rolling, possibly using the lever to steer the robot as it moves, before equipping it with vision and extra sensors that will let it guide itself.

Eventually the concept could be used for transportation. There are already mono-wheel motorcycles in which the rider sits inside a giant rotating wheel and steers by leaning, says Cieslak, but they can be hard to control. A scaled up version of the mono-wheeled robot could be safer, as it would actively balance itself.

Using a lever to balance a wheel is a valid approach, says Brown. “It simplifies things in some ways. Of course it makes the control a lot more complicated.” The robot will be harder to steer the faster it goes, Brown adds, as the lever has to overcome an increased gyroscopic effect.

Graphene is made up of a single layer of carbon atoms arranged in a hexagonal lattice. It is a promising material for the production of next-generation displays or solar cells because it is flexible, transparent and conductive.

Until last year, though, graphene sheets no larger than 1000 square micrometres had been produced. Then of the University of Texas at Austin and colleagues discovered a way to grow graphene sheets several centimetres wide.

Using a technique called chemical vapour deposition, they heated methane and hydrogen gas to 1000 °C above a flexible copper substrate, causing a reaction that left a layer of graphene deposited on the copper. Once the graphene cooled, they transferred it onto a piece of flexible plastic.

Slick production

Now Jong-Hyun Ahn and Byung Hee Hong of Sungkyunkwan University in Suwon, South Korea, and colleagues, have adapted Ruoff’s approach to produce still larger graphene sheets.

They ran the reactions inside a modified roll-to-roll machine, similar to those used as printing presses, through which they fed the flexible copper sheets. The result was a rectangular graphene sheet with a diagonal diameter of 76 centimetres.

Because the sheets were sometimes damaged during the process, the team experimented with depositing up to four layers of graphene on top of each other. These combined layers had greater strength, but they remained transparent.

Flexible friend

The team built a palm-sized touchscreen with the film and flexed it in a vice, putting its lower surface under compressive strain and the upper surface under tension. The touchscreen was able to withstand up to 6 per cent combined compressive and tensile strain before breaking, compared with only about 3 per cent for touch panels based on indium tin oxide, the most widely used transparent conductor in the display and touchscreen industry.

“From an engineering perspective this is very good work,” says Luigi Colombo, a materials scientist at , a semiconductor and computer technology company based in Dallas. Graphene could be a cheaper and more flexible alternative to indium tin oxide, he says, and this work is a step towards producing commercially useful quantities.

The researchers still have to show that their graphene sheets can be made to a consistently high quality, without introducing tears or discontinuities that could affect performance, Colombo says.

Journal reference: , DOI:

The helicopter in this video may weigh only 30 grams, but it carries a compass and motion sensors, can change course and warn fellow craft of obstacles it bumps into, and could even carry a small camera. It can also resist what might be called a King Kong attack – if swatted out of the air the tiny craft soon recovers and takes off again.

It was developed by researchers at in Moffett Field, California. It would make a great toy, but the team’s intentions are deadly serious. They aim to fly squadrons of “Sensorfly” craft that coordinate with each other to explore indoor environments – for instance, to check out buildings after a natural disaster.

The robots are built by adding custom processors, sensors and software to rotors and motors from an off-the-shelf toy helicopter. Each prototype costs only about $200 to build, says , an electrical engineer working on the project with graduate student Aveek Purohit.

Bumping along

Indoor flight requires a craft to be small, light and able to negotiate walls and other obstacles. “Reality bites you a lot more indoors,” says Zhang. But Sensorfly is too small to carry the technology it would need to look for and plan around obstacles. Instead it uses simpler strategies to survive.

Each robot carries a radio, accelerometer, compass and gyroscope. Thanks to the accelerometers it notices if it bumps into something, then backs off and warns fellow copters nearby of the obstacle’s approximate location. Any time two or more of the helicopters are within radio range, they form an improvised data network to share information. Their design is “passively stable”: as long as the twin rotors are spinning, the craft will hover in place. Its shape is such that if it is knocked to the ground, the craft need only keep trying and it should be able to get airborne again.

Squadrons of the craft connect with each other using radio. They pass information between themselves and back to a controller, and use the time delay on the radio signals to track their relative positions.

Team work

The current prototypes can carry only 5 grams of cargo, but that is enough for a small camera or microphone, says Zhang. The networked helicopters are the most lightweight mobile sensor network to date, he says.

However, , who with colleagues at the University of Colorado in Boulder developed a pack of small planes able to collect and share data, points out that the Carnegie Mellon group need to work on their flight times to prove the benefits of their approach. At present they can only sustain flight for 5 minutes. Zhang says he expects better batteries to extend that.

Sensorfly was presented at the in Berkeley, California, earlier this month.

A camera you can wear as a pendant to record every moment of your life will soon be launched by a UK-based firm.

Originally invented to help jog the memories of people with Alzheimer’s disease, it might one day be used by consumers to create “lifelogs” that archive their entire lives.

Worn on a cord around the neck, the camera takes pictures automatically as often as once every 30 seconds. It also uses an accelerometer and light sensors to snap an image when a person enters a new environment, and an infrared sensor to take one when it detects the body heat of a person in front of the wearer. It can fit 30,000 images onto its 1-gigabyte memory.

The ViconRevue was originally developed as the by Microsoft Research Cambridge, UK, for researchers studying Alzheimer’s and other dementias. Studies showed that reviewing the events of the day using SenseCam photos could help some people improve long-term recall.

See some images taken using a SenseCam during trials in Cambridge, UK.

Can’t get enough

Now , based in Oxford, UK, which specialises in motion-capture technology for the movie industry, has licensed the technology for the camera from Microsoft and intends to put it into large-scale production.

Imogen Moorhouse, Vicon’s managing director, says that Microsoft has licensed the technology because it can’t keep up with demand for the gadget. So far, only 500 have been made, most for use by researchers.

Vicon’s version will retail for £500 (about $820) and will also be marketed to researchers at first; it will go on sale in the next few months. A consumer version should be released in 2010.

The gadget will be launched at the Society for Neuroscience meeting in Chicago this weekend, in conjunction with a .

A study described how SenseCam helped a person who had suffered encephalitis that permanently affected their ability to recall recent events. After reviewing SenseCam photos of a significant event every two days for three weeks, the person could remember it substantially better, even after months of not looking at the photos, compared with events that were not reviewed this way or were recorded only in a written diary.

Lifelogging

For consumers, the gadget will provide an easy way to become a “lifelogger” – someone who attempts to electronically record as much of their life as possible. Microsoft researcher has , recording everything from phone calls to TV viewing, and uses a SenseCam wherever he goes.

“What’s great about these kinds of memory technologies is that they can be very usable for ordinary people,” says , a computer scientist at the University of Rochester, New York, who works on technology to assist cognition.

“Once you have that mass market, that brings the prices down.” Eventually, he says, a SenseCam-like device could be part of an artificial memory used by ordinary people, just as they use notebooks and planners as memory aids today.

Journal reference:

Faced with global warming and potential oil shortages, the US navy is experimenting with making jet fuel from seawater.

Navy chemists have processed seawater into unsaturated short-chain hydrocarbons that with further refining could be made into kerosene-based jet fuel. But they will have to find a clean energy source to power the reactions if the end product is to be carbon neutral.

The process involves extracting carbon dioxide dissolved in the water and combining it with hydrogen – obtained by splitting water molecules using electricity – to make a hydrocarbon fuel.

Syngas process

It uses a variant of a chemical reaction called the process, which is used commercially to produce a gasoline-like hydrocarbon fuel from syngas, a mixture of carbon monoxide and hydrogen often derived from coal.

Robert Dorner, a chemist in Washington DC and first author of a new paper on the technique, says that CO₂ is rarely used in the Fischer-Tropsch process because of its chemical stability.

But CO₂‘s abundance, combined with concerns about global warming, make it an attractive potential feedstock, Dorner says. Although the gas forms only a small proportion of air – around 0.04 per cent – ocean water contains about 140 times that concentration, he says.

Iron catalyst

The navy team have been experimenting to find out how to steer the CO₂-producing process away from producing unwanted methane to produce more of the hydrocarbons wanted.

In the conventional Fischer-Tropsch process, carbon monoxide and hydrogen are heated in the presence of a catalyst to initiate a complex chain of reactions that produce a mixture of methane, waxes and liquid fuel compounds.

Dorner and colleagues found that using the usual cobalt-based catalyst on seawater-derived CO₂ produced almost entirely methane gas. Switching to an iron catalyst resulted in only 30 per cent methane being produced, with the remainder short-chain hydrocarbons that could be refined into jet fuel.

Heather Willauer, the navy chemist leading the project, says the efficiency needs to be much improved, perhaps by finding a different catalyst.

Appealing source

“The idea of using CO₂ as a carbon source is appealing,” says , a chemist at Queen’s University in Kingston, Ontario, Canada.

But to make a jet fuel that is properly “green”, the energy-intensive electrolysis that produces the hydrogen will need to use a carbon-neutral energy source; and the complex multi-step process will always consume significantly more energy than the fuel it produces could yield. In addition, each step in the process is likely to add cost and problems.

“It’s a lot more complicated than it at first looks,” Jessop says.

on the navy research was presented at the American Chemical Society annual meeting in Washington DC on Sunday.

Today’s RFID tags can only broadcast fixed data back to a reader device, whether that’s details of your passport or of an endangered bird. Researchers are now working to add brains to the tags in the form of microcomputers, opening the way for much smarter applications.

Because RFID tags lack batteries and scavenge all their power from the radio transmissions from their readers, limited power makes computation a challenge. But that also has the advantage of making so-called computational RFID tags – CRFIDs – cheap, robust and long-lasting.

Batteries not included

“Ten years ago we would have thought this was science fiction – doing programming without a battery,” says , who works on CRFIDs at the University of Massachusetts Amherst.

Fu and his colleagues are working on CRFIDs using hardware from Intel called . Intel’s smarter tags use a 16-bit microcontroller and can store programs up to 32 kilobytes in size. They can also store small amounts of electricity picked up from a reader for short periods in a capacitor.

Because power, computational capacity and memory are all so limited, researchers have to write their code cleverly to accomplish anything useful. In fact, Fu says, they sometimes use algorithms written in the 1970s for inspiration.

Tight fit

“It’s those tight constraints that make the research so interesting,” says , a computer scientist at RSA Laboratories in Cambridge, Massachusetts, who is collaborating with Fu.

The Massachusetts groups have been investigating energy-efficient ways for CRFIDs to store data – a big challenge that further limits the amount of computing the tags can do.

Because they rely on external power, CRFIDs need a way to back up their computations frequently so they don’t have to start again from scratch if the power is lost. That requires flash memory unaffected by power outages, like that used in memory cards – but the memory systems in such cards are power-hungry, taking the CRFID designers back to square one.

Fu and his colleagues have developed a strategy to sidestep flash memory. They have shown it can be less energy-intensive to back up a computation by sending it back to a reader for storage, even when extra work must be done to encrypt the data first.

The technique “enables long-running computations to make progress despite continual power interruptions”, the researchers explain.

“I think that their approach to the problem is absolutely correct,” says an engineer at Intel Research Seattle who leads development of WISP. “That is one of the interesting things about using RFID technology: a lot of the system-design issues turn out to be very different.”

Concrete data

CRFIDs are too new to have ventured far from the lab bench yet. But Juels says enabling them to encrypt and decrypt data could make chips in passports or credit cards more secure.

Adding sensors is another possibility. Fu’s team has tried embedding CRFIDs into concrete to report moisture content, which could give engineers early warning of structural faults.

on the team’s efficient data transmission techniques was presented today at the in Montreal, Canada.