Category Archives: Biomimicry
Robo-lobster
Joseph Ayers has a thing for lobsters. He likes to cook them, eat them, and build them. In his book, “Dr. Ayers Cooks With Cognac” he describes several creative lobster recipes from Cajun to Mediterranean and everything in between. His favorite way to eat a lobster is simply dipping the meat in butter accompanied with a glass of chardonnay. And, when it comes to building robot lobsters, he prefers the kind that can wander the sea floor searching for mines.
A biologist and neuroscientist, Dr. Ayers developed his robo-lobster at Northeastern University between 1999 and 2002 with funding from the Office of Naval Research (ONR) and the Defense Advanced Research Projects Agency (DARPA). Working from Northeastern’s Marine Science Center at East Point in Nahant, Massachusetts, Ayers looked to real-life lobsters for inspiration. He notes that lobsters are at the top of the food chain in their environment and so have a good built-in seek-and-destroy mechanism.
His robots are controlled with artificial neural networks, which are used to make subtle decisions such as whether to walk over or around a rock. When it comes to tweaking the design, Ayers always went back to the original, studying the behavior of living lobsters, trying to replicate their behavior. The plastic antennas sense obstacles, the eight legs can propel it in any direction, and the claws and tail keep it stable in turbulent water.
The robo-lobster’s actuators are controlled by Nitinol, otherwise known as “muscle wire”. Nitinol can change shape when a current is passed through it, making it more life-like and less “robotic”. Also, Ayers’ neural networks use Central Pattern Generators (CPGs), specialized neural circuits found in all animal brains that automatically generate a rhythmic patterns. The CPG acts as the source for the robots pattern of locomotion.
The robo-lobster is an excellent example of biomimicry, where ideas from nature are incorporated into robotic designs, however, a practical mission for the robo-lobster has yet to be demonstrated. In addition to finding mines, Ayers notes that it might also be used to measure pollution levels on the ocean floor. The robo-lobster was put on display at the Cooper-Hewitt museum in New York in 2007 as part of its “Design Life Now” exhibit. It was also named one of the Coolest Inventions of 2003 by Time Magazine.
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So Little Brain, So Much Skill
The cheetah is the fastest land animal on earth and can run at astonishing speeds of up to 70mph. Absolute speed, however, is not a fair measure especially when we consider insects and other small animals. A better comparison is relative speed, measured in body lengths per second. Using this measurement, we see that the cheetah can achieve about 13 body lengths per second, whereas cockroaches are about 4 times faster reaching 50 body lengths per second. They are also capable of scurrying over uneven terrain and large obstacles without missing a beat.
Biomimicry is a design discipline that studies nature’s best ideas and then imitates these. The cockroach’s uber-fast running speed makes it of special interest to scientists interested in robot locomotion. Whereas the cheetah has a large brain capable of leg cordination over uneven terrain using a complex visual and neuromotor system, the cockroach somehow achieves this and more with a brain that is 1/1000 the size. If you’re going to build a running robot, that means a lot less programming.
The cockroach’s speed is due to the design of its legs and body. It has a stable posture with a low center of gravity. The legs are essentially blind thrusters, pistons angled just the right way, so it will inevitably scramble over objects in its path, whether it sees them or not.
In 2003, scientists at Stanford University developed biomimetic robots based on the cockroach design called Sprawl Robots. One model, Sprawlita, was 6 inches long and could clock an impressive 15 body-lengths per second. Stealing the clever cockroach design from nature allowed the roboticists to skip the difficult problem of coordinating the legs over uncertain terrain.
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