Servo - December 2015

bots IN BRIEF

SERVO 12.2015 9

WALK AND ROLL

Anyone who has much in the way of experience with robots is painfully aware of their fragility. Robots like Flyability’s Gimball deal with this through the creative use of roll cages, which have a useful side effect of allowing the robot to dynamically navigate through direct surface contact. Roll cages can protect ground robots too, although it’s a bit more problematic because using a full roll cage makes it difficult for the robot to do anything but roll. However, Japanese researchers Takeshi Aoki, Satoshi Ito, and Yosuke Sei of Japan's Chiba Institute of Technology have designed a robot that can be tossed, roll along the ground, and then pop out four legs when it needs to scramble around.

The big advantage of “QRoSS” is that the shell acts as a passive shock absorber, allowing the robot to the rolled (or, hypothetically, thrown) without damaging it. In a disaster area, for example, a human could chuck the robot like a baseball into a dangerous area from a safe one, and after bouncing a few times, QRoSS simply sprouts legs and starts walking around. Legs are excellent at dealing with very rough terrain, and the design of QRoSS allows you to use legs when necessary without having to always worry about how fragile they are, since any slip and fall just turns into a bouncy roll.

The other advantage of a more or less spherical robot is that it can use rolling as a faster and more efficient method of locomotion, as long as the terrain is favorable.

WHERE RUBBER MEETS THE ROBOT

The adaptability and inherent safety offered by soft robots is pretty great, and we’ve seen lots of examples of all the crazy things that you can do when you don’t have to give your robot structure. Getting soft robots to move is tricky, but turning water into gas and then back into water again may offer a compact, efficient, and clever solution.

Getting these soft robots to do stuff usually means an external air source connected to the robot by tubes, an internal gas generator, a battery powered air compressor, or (and this is by far the best method) explosions. For practical use, most of these things are probably not going to cut it. An air tether is obviously problematic, gas generators and explosions are of limited use, and that backpack air compressor is fragile — especially once you figure in all the tubing and valves and what not.

However, researchers from Okayama University have now developed a “tube-free pneumatic rubber actuator” which offers a simple process which goes like this: Water is cracked by a catalyst to create hydrogen and oxygen gas, then the process is reversed to turn that gas right back into water again over the course of just a few seconds. This results in a pneumatic actuator that’s essentially a gas generator that doesn’t use up any fuel when you run it — only electricity. It’s better than using chemical gas generators because there’s no limit on the number of actuations you can do (assuming the catalyst’s performance doesn’t change), and it’s also better than an air compressor because it has no moving parts, is completely self-contained, and isn’t wasting energy every time it vents compressed air to deflate itself.