Scientists have developed innovative objects capable of moving across various terrains, including uphill and over obstacles, as reported in a paper published on March 12 in Nature. The research was conducted by physicists from the University of Amsterdam and the University of Chicago.
These "odd" objects differ from traditional robots as they lack centralized control or a brain. Instead, their movement is driven by interactions between motorized building blocks connected by elastic springs. Colin Scheibner, co-first author of the paper, noted the significance of this approach: “There’s not a complicated algorithm powering its decisions. I feel there’s something powerful about its simplicity, which approaches the question of movement in a different way.”
The concept relies on "odd elasticity," where building blocks exert nonsymmetric and nonreciprocal forces on each other. Jonas Veenstra, another co-first author and PhD student at the University of Amsterdam, explained that this means "a building block A reacts to its neighboring building block B differently than how B reacts to A."
As these objects move, they create a self-reinforcing cycle: terrain deforms them, prompting further deformation and movement forward. This allows them to traverse challenging surfaces like sand piles or ball bearings with ease.
Researchers have created different shapes using these principles. For instance, an 'odd chain' can navigate through tunnels and uneven ground while an 'odd ball' can roll on flat terrain or crawl uphill.
Scheibner expressed surprise at the robustness of these objects: “There was a sense of shock when we discovered how robust they were, given their simplicity.” Even when more than half of their units were turned off, the robots continued functioning.
This research is part of the emerging field known as "active metamaterials," which involves artificial structures made up of motor-powered units with unique capabilities. Vincenzo Vitelli from the University of Chicago highlighted potential applications: “You can imagine many situations where you need a machine to venture into rough territory autonomously.”
The study also raises questions about locomotion evolution in organisms without centralized brains and suggests potential applications in material science and chemistry.
The research received support from various organizations including the European Research Council and Chan Zuckerberg Initiative.
Citation: “Adaptive locomotion of active solids.” Veenstra, Scheibner, Brandenbourger, Binysh, Souslov, Vitelli, and Coulais, Nature, March 12, 2025.
Funding: European Research Council; Netherlands Organisation for Scientific Research; Army Research Office; National Science Foundation; Chan Zuckerberg Initiative; European Union; Simons Foundation.
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