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14/05/2007
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Advances in technology – and falling costs – are expanding the capabilities of remotely operated and autonomous mobile robots. Tom Shelley reports
The ever-falling cost of digital electronics and motors and drives, coupled with advances in mechanisms, is now moving mobile robots way out beyond the research and military areas of application and into mainstream markets.
Inspection of pipes and drains, searching for lost or hidden objects, maintenance and even fire-fighting are becoming mainstream for machines that can make their way into dangerous, difficult to access and sometimes very restricted spaces.
So far, manufacturing is still undertaken by robots that are fixed in one place. However, there are plenty of research studies into using robots that can take themselves to the task in hand as well. And while none of them looks remotely like Arnold Schwarzenegger – or the NS-5 in the film ‘I, Robot’ – most of the latest machines are a lot more useful, and without any likelihood of causing trouble.
Machines are being developed worldwide, according to Geoff Pegman, managing director of RU Robots in Manchester.
“A robot is a nice, compact example of a fusion between mechanics, electronics and software,” he stated at a DTI Global Watch seminar on ‘Mechatronics in Russia’.
Referring specifically to his own company, he singled out the development of a robot that works alongside people in the food industry and has to learn by example.
From an international perspective, while Russia had many years’ experience in space robotics, “field robotics was spurred on by the Chernobyl accident”, Pegman pointed out. He made particular mention of a scissor action parallel mechanism robot and machine tools developed at Moscow State Technological University Stankin, in conjunction with the Technical University of Chemnitz, Germany. Industrial robots have also been modified by Moscow State Industrial University to perform physiotherapy rehabilitation and massage, including massage of pets, while tiny machines developed by the SAS Institute for Problems in Mechanics in Moscow can crawl up the insides of pipes as small as 10mm in diameter. These are pneumatically actuated machines using asymmetric vibrations to both pull and push them along. The actuation sections are only about 10mm long; however, by linking several of these with flexible connections, it is apparently possible to get the robot to transverse quite a tight radius of curvature. The same institute has also developed a linked device equipped with suckers that can make its way from ground to wall, and wall to ceiling, and potentially perform even more complicated manoeuvres (see diagram). The massage robots were regulated by force control, although “the aspects relating to patient safety were not entirely clear,” Pegman added.
Remote tracking
A number of Russian institutions have developed wheeled and tracked remotely operated vehicles to cope with various problems and hazards. Particularly worthy of note, according to Bob Chesterfield, group leader of the Novel Systems Group at MBDA in Bristol, are the MRK 26 and MRK-27VU developed by Bauman Moscow State Technical University. The MRK 26 was specifically designed for RosAtom to enter nuclear power stations with high, wide, building thresholds. It is unusual, in that it uses four tracks, two mounted tandem on each side, which it can turn down about the drive axles near the centre of the vehicle. This enables it to stand up on the tracks to get a better view or ford through water. Alternatively, they can be turned up to help the vehicle climb out of a ditch, for example.
The MRK27VU has only one track on each side, but each can be made to change its geometry from linear to triangular, using what appears to be an ingenious linkage mechanism. This can be used to swing up the track tensioning sprocket at the front of the track. Like the tandem tracks, the ability to change geometry helps the vehicle get over obstacles. The track shape-changing configuration was originally developed for a machine that was used to assist during an accident in 1997 at the Russian Federal Nuclear Center in Sarov. “A large number of these machines have been supplied to FSB, Ministry for Emergency Situations, Interior Ministry and RosAtom,” said Chesterfield.
A different type of machine, with all four wheels driven by wheel motors, was developed by the Russian State Technical Center for Robotics and Technical Cybernetics (RTC) in St Petersburg, which has a reputation for its capabilities with space robotics. One of its machines was used to search for, and recover, a source of radiation that had been buried in woodland in Grozny in Chechnya in July 2000. Designing to cope with radiation hazards was learned the hard way. Chesterfield observed that the original machines used at Chernobyl had working lives of only minutes or hours. The latest version of the machine has six wheels. RTC has also developed robotic snakes made of modular elements that can simulate a seal snake’s movements.
Fighting fire
It is not just in Russia that tracked mobile robots have been developed to deal with catastrophes. John and Fiona Ryland run a small business in Bordon, Hants, which produces the ‘Firemote’ Remote Controlled Fire Fighting Machine.
John Ryland learned how to make robots resistant to damage by taking part in the television programme Robot Wars as one of the Plunderbird Team, entering a machine called ‘Terminal Velocity’, equipped with steerable chainsaws.
Rather than cause damage, the Firemote is intended to avoid it, and is unique among fire-fighting robots, in that it includes a coil of fire hose. The idea is to connect the robot to the hose reel of a fire appliance, or other source of water, and then drive it into a building under conditions considered too dangerous for human fire fighters, guided with the help of a thermal imaging camera. Should the hose become snagged or too heavy to pull, more is released from the on-board reel to allow the robot to continue its journey to the seat of the fire, paying out hose behind it as it goes. Features include a sufficiently narrow width to allow it to enter through a standard doorway, the ability to climb stairs and get over obstacles, waterproof, on-board cooling to prevent overheat near the fire and a simple-to-operate wireless control system. “We have secured a DTI research grant and are currently building a new prototype, which is larger, more stable and of higher capacity than its predecessor, with a new telemetry system with multiple camera video monitoring”, says Ryland. Meanwhile he is developing a prototype for a Canadian company, with interest expressed for possible remote washing for biohazard contamination control and from the Iranian Fire Service for post-earthquake searches.
Getting it together
Another area where research is underway on a wide scale concerns the development of small robots that can be used in swarms. At the Thayer School of Engineering at Dartmouth, New Hampshire, US, robots are being used for a study of distributed cooperative control, in which they communicate information about their state to each other. The purpose is said to be to “assist community first responders in assessing potentially dangerous situations rapidly and safely”, with reduced risks to themselves. “This approach eliminates the need for the one soldier per robot control procedure currently required with highly specialised military use robots”, the school of engineering adds.
The same institution is also researching micro robots 250 microns long and 10 microns high. Presently, they are powered by the insulated, interdigitated electrode array on which they move around, which transmits both power and control signals. They can take 12nm steps 16,000 times a second and do so for more than half an hour without any sign of fatigue.
Pointers
* Mobile robots have proved themselves up to the task in various instances of disaster management, including situations where humans are unlikely to survive or where it is too restricted for them to enter, and also show promise for civilian fire-fighting. Sizes mostly range from large dog size, down to 10mm across.
* Control can be by cable, but is more commonly by wireless
* Mobility is being assisted by advances in track design
* Research is underway into using low cost co-operating swarms of mobile robots, which can potentially be made very small indeed
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Author
Tom Shelley
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