One day Dr. David Zaruk was doing a computer simulation of a robot cockroach, as people do. Zaruk, a mechanical engineer at Be’er Sheva’s Ben-Gurion University of the Negev, ordered the simulated robot roach to move.
A robot roach, whether simulated or real, is powered by a single motor. Like genuine members of Blattidae family, they have three legs on either side. Absent other power sources, they should go straight. This one didn’t.
“From the very first step, it deviated from the straight and narrow,” Zaruk told Haaretz in conversation.
He then helpfully explained why a single-engine robot cockroach is expected to go straight. “My car has only one engine,” Zaruk said. “But I have another engine — my hands. Say the only input is the engine, without hands. The car will go straight all the time.”
Zaruk then repeated the experiment with a real robot cockroach, a 12-centimeter-long machine named 1Star that may be elephantine by entomological standards, but is tiny for a machine. He repeated the same instructions as for the ersatz one: Move. He told the legs on either side of the body (three and three) to go at the same speed. 1Star should, by theory, have gone straight. Yet it did the same as the simulated one, and deviated from the path.
Moreover, both genuine and simulated robot roaches did achieve a straight line in time, just not in the direction Zaruk had told them to go.
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Understanding Zaruk’s explanation requires knowing a principle of physics: that by definition, two robot cockroach legs are more rigid than one leg, just as two springs are more rigid than one spring.
Also, at any given moment, said roaches had three legs touching the ground and three in the air. Ergo, on one side of its little body, two legs would be on the ground, but on the other side, only one.
When accelerating (which is what happens with the robot’s very first step), if the two ground-touching legs are on the right side, the robo-roach lurches left. With its next step, two legs descend on the left and it turns right.
Invention or discovery
“We discovered that the difference of rigidity between the sides can be manipulated,” he says. And that led to their “invention,” he calls it, but perhaps it’s more of a discovery: The scientists could use acceleration and deceleration to manipulate the roach’s direction — yes, the robot with only one motor could change direction and even be manipulated into going backward, to turn or even to move in circles. It can, in a word, be maneuvered.
Take 2 miniroaches and call me in the morning
1Star is the baby of the machinery and robotics people at BGU and at Stanford University. It is the first robot to be maneuverable using just one motor. The innovation is tremendously exciting to the scientists, chiefly because of potential future uses. “We want to develop tiny robots for search and rescue missions, so we want to miniaturize the robots as much as possible,” Zaruk says.
Miniaturization requires simplification of the mechanics. It means as few motors as possible. Hence the excitement at creating a robot that can be directed to advance in more than a straight line with just one motor on board.
Zaruk points out another reason to reduce the number of motors: Miniaturized engines tend to be less efficient in their energy use.
Imagine an army of robot cockroaches swarming into areas where man cannot go, for instance that multistory parking garage in Tel Aviv that collapsed last month, with construction workers trapped inside. The robots could scuttle in, scan for life and return to base, and if they don’t, the loss is not great. Or the wee robots could be equipped to bring things to people trapped in places like that collapsed parking garage.
It’s a lovely dream. At the moment the team has no clue with to do with 1Star, but they are confident that it’s a paradigm changer, for all that everybody and their dog in robotics are obsessing over artificial intelligence. What good is it if the robot is smart if it can only move in a straight line and can’t wedge itself into tight spaces?
“We shattered the myth. We proved that one can move forward, backward and turn with just one motor,” Zaruk sums up. “A development like this leads people to think in simpler terms. We believe our discovery will lead robotics in the direction of heightened performance with simpler mechanics.”
Fine. Why a cockroach? Miniature robots that ape insects, rather than robots based on wheels, can go almost anywhere, Zaruk answers. Robots on wheels can only move on flat floors. Okay, again, why a cockroach? Because cockroaches are dynamic, robust and stable, says Zaruk: You can kick the things and they continue to run around, undismayed by your abhorrence. Better hope nobody invents a better shoe.
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