Author: Madhu Reddy

Robots inspired by cockroaches can use the shape of their bodies — particularly, their distinctive round shells — to maneuver through dense clutter, which could make them useful in search-and-rescue missions, military reconnaissance and even on farms, according to a new study.

Although many research teams have designed robots that can avoid obstacles, these bots mostly do so by evading stumbling blocks. This avoidance strategy typically uses sensors to map out the environment and powerful computers to plan a safe path around the obstacles.

“This approach has been very successful — for example, Google’s self-driving car,” said lead study author Chen Li, a physicist at the University of California, Berkeley.

“However, it does have limitations,” Li told Live Science. “First, when the terrain becomes densely cluttered — where gaps become comparable to, or even smaller than, robot size — a clear path where robots do not hit obstacles cannot be planned, because obstacles are just too close to each other. Second, this approach requires sophisticated sensors and computers, which are often too large or heavy for small robots to carry around.”

Instead, Li and his colleagues wanted to design robots that did not avoid obstacles, but traversed them. They sought their inspiration from discoid cockroaches, which are about 2 inches (4.9 centimeters) long. These roaches usually live on the floor of tropical rainforests, where they frequently encounter a wide variety of clutter, such as grass, shrubs, leaves, tree trunks and mushrooms.

The scientists used high-speed cameras to analyze how the cockroaches moved through artificial obstacle courses with closely spaced, grasslike beams made of card stock. Over the course of hundreds of runs, the insects usually completed the obstacle courses in about 3 seconds. Although the roaches sometimes pushed through the beams or climbed over them, nearly half the time, the insects quickly and effectively slipped past the beams by rolling their bodies to fit through the gaps and using their legs to push off the beams. [See video of the robot cockroach evading obstacles]

Then, the researchers fitted the cockroaches with three artificial shells of different shapes — an oval cone similar to the roaches’ bodies, a flat oval and a flat rectangle — to see what factors influence the insects’ movements. When the glued-on shells made the roaches less round, the insects were less able to perform a roll and maneuver past the obstacles, the researchers found.

Then, the scientists tested a 4-inch-long (10 cm) six-legged robot named VelociRoACH on a similar obstacle course. When it had a rectangular body, the robot had only a 19 percent chance of passing the course, since it frequently got stuck between the grasslike beams. However, when it was fitted with a cockroach-inspired round shell, it had a 93 percent chance of finishing the obstacle course by rolling through the beams, in much the same way real roaches did. This move did not involve any change to the robot’s programming or the addition of any sensors — it was a natural consequence of the shell, the researchers said.

“Robots can take advantage of effective physical interactions with the environment to traverse even densely cluttered obstacles,” Li said.

This research shows how body shapes can help animals and robots traverse terrain, much like how the streamlined body shapes of many birds and fishes (and mimicked by airplanes and submarines) help reduce drag, Li added. “This is why we named this new concept ‘terradynamic streamlining,'” he said.

Terradynamic streamlining may prove especially useful for small, inexpensive robots in applications like search and rescue, precision farming, or military reconnaissance because it allows the bots to traverse obstacles like rubble and vegetation without having to add more sensors and computers, Li said.

“There may well be other body shapes that are good for other purposes, such as climbing up and over obstacles,” Li said. In the future, the researchers plan to analyze how animal and robot body shapes affect other kinds of movement in a variety of environments.

The scientists detailed their findings online June 23 in the journal Bioinspiration & Biomimetics.

References:http://www.livescience.com/

A molecule has become the world’s smallest movie star.

For the first time, scientists have observed a chemical reaction as it was happening at the molecular level, at speeds that previously were too fast to see. The experiment could lead to insights about how complex molecules behave and why they take the shapes they do.

At the SLAC National Accelerator Laboratory, a team of researchers used two laser beams — one in the ultraviolet and another in the X-ray wavelengths — to get a picture of a chemical called 1,3-cyclohexadiene (CHD) as it morphed into another form called 1,3,5-hexatriene. They captured images of the reaction on a scale of femtoseconds, or millionths of a billionth of a second.

“We kind of know what CHD looks like,” Michael Minitti, lead author of the new study and a staff scientist at SLAC told Live Science. “The issue was the steps between one form and another.”

CHD is made of six carbon atoms in a ring with hydrogen atoms on the outside, like spokes. When ultraviolet light of a certain wavelength hits it, one of the carbon bonds breaks, and the CHD turns into 1,3,5-hexatriene. The latter chemical is made of the same chemical elements but is arranged to form a different shape.
Such reactions are called electrocyclic, and they show up in a lot of different places — for example, it’s one of the ways animals synthesize vitamin D from sunlight. Although they’re common, electrocyclic reactions aren’t so well understood. A big question for physical chemists has been what happens to a molecule like CHD after it gets hit by the UV light but before it turns into 1,3,5-hexatriene.

To make their movie, the researchers first put a gaseous form of the CHD into a chamber at very low pressure. Then, they fired the ultraviolet laser at it, breaking one of the carbon bonds. The next step was to use an X-ray laser to zap the molecule. The X-ray laser flashes lasted only a few femtoseconds, as the whole reaction from CHD to hexatriene takes less than 200 femtoseconds to complete.

The X-rays scattered off of the molecules, and by looking at a pattern of light and dark on a detector, the researchers could read the shape of the molecule. Firing the X-ray laser repeatedly over a tiny fraction of a second showed how the shape changed over time.

The technique is similar to X-ray diffraction used when investigating the structure of DNA or crystals. (In fact, the structure of DNA was discovered in just this way in the 1950s.) There are crucial differences, though: X-ray diffraction doesn’t measure anything over time, so the resulting picture is static; the X-rays in this new experiment were generated by a laser; and CHD is a gas, unlike the DNA molecule. “Gas molecules don’t have a structure,” Minitti said. “It looks like someone sneezed on the detector.”

When chemists can see the way the shape changes, it tells them how such chemicals transform in a specific way that wasn’t known before. Molecules tend to go to states of minimum energy, just as a ball rolling between two hills will tend to fall to the bottom and stay there. Regions of high and low potential energy surround the molecule, and when that molecule changes shape, its atoms will tend to stay in the low-energy regions. That means the shapes are specific, and knowing what they are offers insight into the processes that create the final forms.

While the research team was able to see the CHD change, the resolution in time —corresponding to the number of “frames” in an ordinary film — wasn’t quite high enough to see every step, Minitti said. Each “frame” was about 25 femtoseconds, so there would be about eight in the animation. In the next experiment, scheduled for January 2016, he hopes to get a better picture of the changes with smaller intervals. Even so, the new experiment shows that such molecular moviemaking is possible.

References:http://www.livescience.com/