A new kind of robot can cling to walls and relax its grip. "What's really unique about this is the technology, not the robot," says Harsha Prahlad, senior mechanical engineer at SRI International, a nonprofit research organization based in Menlo Park, CA. There are other robots that can climb walls. But these have usually involved using microscopic fibers designed to mimic the function of the hairlike setae that give geckos their remarkable sticking power, Prahlad says. In contrast, SRI's robot works by inducing electrostatic charges in the surface of a wall. The advantage here is that the adhesive climbing surfaces of the robot can be turned off, making movement much simpler, says Prahlad. It also makes the robot's adhesive surfaces self-cleaning, he says, thereby avoiding any gradual buildup of dust and dirt that would ultimately reduce the adhesion. Tests have shown that the robot is capable of generating 1.5 newtons of sticking force per centimeter square of contact with a wall. Presenting his results at this year'sInternational Conference on Robotics and Automation, in Pasadena, CA, Prahlad showed that the robot was able to scale walls while carrying weights of up to 75 pounds. "It's an interesting and robust approach," says Metin Sitti, a mechanical engineer at Carnegie Mellon University, in Pittsburgh, who has been working on wall-climbing robots for some time. However, he says, the forces generated are just one-tenth as strong as is currently being seen when the gecko-inspired approach is used. On the plus side, however, the simplicity of Prahlad's approach should make it easier to apply to human wall-climbing applications, says Nicola Pugno, a professor of structural mechanics at Turin Polytechnique, in Italy, who has been working on a sort of Spiderman suit using nanotube-covered adhesive surfaces.
Thursday, August 13, 2009
Building a Better Wall Climber :
Upgrading the Prosthetic Hand :
The Fluidhand prototype, developed by a team led byStefan Schulz at the Research Center in Karlsrühe, in partnership with the Orthopedic University Hospital, in Heidelberg, Germany, has flexible drives located in each of its finger joints, enabling the wearer to move each finger independently. Lightweight miniature hydraulics are connected to elastic chambers that can flex the joints of the fingers. As sensors on the fingers and palm close around objects, nerves in the amputation stump pick up muscular sensations so that the amputee can use a weaker or stronger grip. The prosthetic provides five different strengths of grip. "It is so intuitive that learning to use the device only takes about 15 minutes," says Schulz. Last September, 18-year-old Sören Wolf, who was born with only one hand, became the first person to use the Fluidhand. According to German press reports, Wolf was able to type on a keyboard with both of his hands for the first time in his life, and he told reporters that, when he's wearing the Fluidhand, he doesn't feel handicapped anymore. International interest in the Fluidhand peaked late last month, when it was announced that the Orthopedic University Hospital is testing the device in comparison with the i-LIMB Hand. Wolf is the first amputee to use both prosthetics. Produced by the Scottish company Touch Bionics, i-LIMB was the first prosthetic hand that enabled the movement of individual fingers. The prosthetic, released last summer, uses a different technical principle than the Fluidhand. With i-LIMB, movement is enabled by five small, battery-powered motors that are embedded in each finger. Schulz believes that the hydraulic system has some advantages over the motorized fingers. "In contrast to the movement with electric motors and transmissions, the Fluidhand remains soft and flexible," he says. "Articles can therefore be seized more reliably, and the hand feels more natural."
A lightweight hydraulic hand with individually powered fingers could change the lives of amputees, say researchers in Germany. The Fluidhand, according to its developers, is lighter, behaves more naturally, and has greater flexibility than artificial hands that use motorized fingers.
Molten Mirrors :
liquid-mirror telescope could reveal much fainter objects than the Hubble Telescope can, says Ermanno F. Borra, a physics professor at the Université Laval, in Quebec, who is leading the development of the new mirror. The power of a telescope is proportional to the surface area of its mirror. The James Webb telescope, which is scheduled to launch in 2013 and is far more powerful than the Hubble, has a diameter of about six meters. (See "Giant Mirror for a New Space Telescope.") A lunar liquid-mirror telescope could be as large as 20 to 100 meters, says Borra. The liquid mirror, which was funded by NASA, consists of a pool of an ionic liquid coated with a film of silver. Such ionic liquids are carbon-containing salts that freeze only at very low temperatures and have very high viscosity. The salt used in the Laval mirror is liquid down to -150 ºC and does not evaporate below room temperature, even in a vacuum--suggesting that it could withstand the harsh environment of the moon. There are two limitations on cosmologists' observations of the early universe: "The objects you want to observe are incredibly distant and incredibly faint," says Borra. Telescopes in orbit like the Hubble, whose views are unobstructed by Earth's atmosphere, are limited in size and power; telescopes on Earth can be larger and more powerful but produce fuzzier images because of the atmosphere. Liquid mirrors couldn't go into orbit, but they could operate on the moon, which has no atmosphere.
Canadian researchers have developed a liquid mirror that could operate in a future telescope located on the moon, allowing researchers to peer back into the origins of the universe with extraordinary clarity. Telescopes relying on liquid mirrors can be hundreds of times more powerful than those with glass mirrors--for the same cost--and they should be easier to assemble in space.
Robotic Fleas Spring into Action :
Tiny rubber bands can power microrobots that could serve as ultrasmall sensors. An autonomous robotic flea has been developed that is capable of jumping nearly 30 times its height, thanks to what is arguably the world's smallest rubber band. Swarms of such robots could eventually be used to create networks of distributed sensors for detecting chemicals or for military-surveillance purposes, saysSarah Bergbreiter, an electrical engineer at University of California, Berkeley, who developed the robots. The idea is that stretching a silicone rubber band just nine microns thick can enable these microrobotic devices to move by catapulting themselves into the air. Early tests show that the solar-powered bots can store enough energy to make a 7-millimeter robot jump 200 millimeters high. This flealike ballistic jumping would enable these sensors to be mobile, covering relatively large distances and overcoming obstacles that would normally be a major problem for micrometer-sized bots, says Bergbreiter. Such sensors could be scattered from a plane but may not land in the most ideal positions, so making them mobile could allow them to be repositioned, if somewhat haphazardly. "Distributed sensors in general give you the large picture," Bergbreiter says. This is because they can provide a more detailed resolution over a larger area compared with more-traditional nondistributed approaches to sensing. "With miniature robots, hopping is a good option if you're trying to move over uneven terrains," says Metin Sitti, an assistant professor at the nanorobotics lab at the Robotics Institute at Carnegie Mellon University, in Pittsburgh. "At that size, the critical issue is power, so it is a good choice to store energy," he says. The impressive jumping skills of insects such as fleas come from their ability to store energy in an elastomeric protein called resilin. This allows them to store a large amount of energy and then release it very suddenly as movement. But while insects store the energy through compressing an elastomer, Bergbreiter opted for a system that stretches one.
