Learn about miniature robots that dance automatically

In January 2020, a lab on the second floor at Northwestern University filled with the shy knocks of three pushing robots Around each other. The trio was in a small ring beating each other, even though the little robots weren’t rock-hard, they were variety. These were active smart particles – “smart particles” – with two paddle-like armhole covers, extending less than 6 inches from end to end, and topped with markers to track their position and direction. The young subjects went through unexpected and unfamiliar moves of chaos until, every now and then, they gracefully transitioned into clearly coordinated movements: a dance.

Smart magazines were not programmed with specific instructions, nor were they required to interact with each other. The robots have been described with motors, or movement patterns, for their panels, which surprisingly give way to dance-like sequences. The patterns and the physics on which they are based are described in a paper Published today in Science. The research was funded by the National Science Foundation, the James S McDonnell Foundation, and the Army Research Office.

Thomas Beer said that when the smart elements weren’t in sync, there was “a mess of throbbing and collisions throughout the episode, which was charming to watch, but definitely not organized.”Stta, a robotics scientist at Northwestern University and co-author of the paper, on a video call. But in collaboration with Pavel Chvikov, a physicist at the Massachusetts Institute of Technology, and Jeremy England, a former physicist at MIT and now at Georgia Tech, the research team programmed smart particles to perform the driving pattern at the same time.

“Suddenly, they were doing this lovely whirling procession,” BearEuropean UnionTa said. “As someone who has smarticles and hasn’t done that before, I felt like [Chvykov] He came and did a magic trick with my own tools. “

The system is present in many places in the natural world – the flow of birds, for example, or water crystallizing into ice – but its prediction is a beast in conditions of imbalance, where there are external forces at play. (And to be clear, the world of imbalance is the big and vast world outside your window – a vast world compared to the inimitable feats that can be achieved in a predictable laboratory environment.) In the 1870s, a Swiss physicist named Charles Soret conducted experiments that showed how a salt solution in a tube subjected to heat from one side could cause a larger arrangement of particles on the cooler side. Since the particles move more violently on the hot side of the tube, many of them end up moving to the cooler side; The cooler particles, with their gentle movements, don’t end up traveling very quickly. What this means is that the particles eventually end up accumulating on the cold side of the tube. The principle, called thermoprophylaxis, was typical of England and Schwartzof in seeing the promise of things in so-called low-cracked states.

Rift occurs when a substance uses the energy flowing to it to move. According to England, the higher the clink, the more random or spastic the movement was, and the lower the clink, the more intentional or increased the movement. Both can also be true.

“The idea is that if your material and power source allows for the possibility of a low-vibration state, it will randomize the system until it finds that state and then crash there,” England said in a statement from Georgia Tech. “If you supply energy through forces of a certain pattern, then this means that the chosen state will discover a way to transfer the material so that it perfectly matches that pattern.”

In this case, the pattern was the flutter movement described, and the material moving to match that pattern was the robots slapping each other in a spin and translating around the ring that surrounded them. These little paddles were a great testing ground for the idea that low-roughness situations would lead to stable, self-regulating dances. Contrary to other beliefs, smart particles did not have a molecular source for self-ordering behavior (such as how water turns into ice at a certain temperature). Other variables that play a role in crystals give way to alternative interpretations of arrangement, messing up the low-impact idea the research team wanted to test.

Since smart objects only move through contact with one another (they can’t take steps or roll), there are also fewer unknowns about where the objects’ movement comes from, England said, which is a problem you would face if all smart objects had small drives that push them in Their dance. When robots can only move by propelling each other, you know that the movement you see is the result of group behavior.

Arvind Murugan, a physicist at the University of Chicago and not affiliated with the recent paper, said in an email: “This paper proposes a general principle that complex systems are naturally attracted toward behavior that reduces“ vibration. ”The current application of robots shows that the idea is She survived her first contact with reality. But future work should show whether this principle is a good approximation of other complex systems – from molecules to cells to human crowds at a rock concert (after COVID of course). “

Morgan adds that the principle is not always true, and “it is nearly true when it is true.” But the idea the robots implemented shows that, given that momentum, they’ll dance in a low-pitched state.

“Once you have a bunch of robots that interact with each other and interact with people … the idea in this paper is that they’ll be syncing for some time.” Said Todd Murphy, a robotics scientist at Northwestern University and co-author of the paper: “When they synchronize, it will be There is an emerging behavior, but you cannot necessarily know what that emergent behavior will be. ”“ If we are unwilling to talk about the emerging behavior as a basic consequence we should always expect it to a sufficiently complex system in imbalance, then we will miss things that could reasonably happen. “

The implications of robotic motions go beyond improving your DDR technique. Although there are three great alternatives in circulation, the smart icons showed a principle that could be applied to self-driving cars or even the human beings inside them.