Researchers have developed a robotic material that can synchronize the movement of 37 connected units, turning small vibrations into a coordinated rhythm without an external timing signal.
The international team built a two-dimensional honeycomb structure containing 37 active units and a separate elastic ring with 24 motorized units. Both structures developed repeating patterns of movement through interactions between their components.
The researchers describe the behavior as a form of time crystallization, in which a system develops a repeating pattern in time. Unlike conventional crystals, whose atomic structures repeat in space, these experimental materials also display organized movement over time.
The work involved researchers from the universities of Amsterdam, Leiden, Birmingham and other European institutions. It could eventually help engineers develop robotic materials capable of changing shape and coordinating movement without relying on a central controller.
Vibrations merge into rhythm
The experimental material combines elastic structures, sensors, electronics and actuators. Actuators convert electrical energy into physical movement, allowing individual components to move and influence their neighbors.
The researchers designed the interactions to be nonreciprocal. This means that when one component influences another, the second does not necessarily produce an equal response in return.
That difference proved important. In the honeycomb structure, individual units initially oscillated at approximately 30 hertz, or 30 times per second. Over time, the vibrations combined into larger patterns, with longer wavelengths and periods, until the structure moved collectively.
The researchers call this process “wave coarsening.” Instead of requiring an external signal to synchronize each component, the system develops an organized rhythm through the interactions built into the material.
The team also tested a ring-shaped structure containing 24 motorized units. Higher-frequency deformation patterns initially appeared around the ring before gradually merging into larger movements. Eventually, the ring settled into a slower, repeating cycle.
The experiments showed that the collective patterns could remain stable despite random disturbances. The researchers also used mathematical modeling to examine how the ordered movement behaves as the size of the system increases.
Materials coordinate their movements
The findings suggest a possible approach to building robotic structures that coordinate their movements through their physical design rather than through instructions issued to every component.
“Our research provides a striking example of spontaneous organization—tiny vibrations organizing themselves until an entire material moves in a coordinated way,” said Jack Binysh, a co-lead author from the University of Birmingham.
The experimental structures incorporated more than 100 sensors and actuators, along with 3D-printed components and custom-built Lorentz actuators that use electromagnetic forces to generate mechanical motion.
Researchers envision future materials that could switch between different stable movement patterns. Such structures might eventually change shape or move in different directions without requiring separate mechanical systems for every function.
However, the experiments demonstrated coordinated oscillations, not a robot capable of performing multiple practical tasks. The researchers have yet to demonstrate controlled switching between different movement modes for useful robotic operations.
The team plans to investigate three-dimensional structures that could support more complex movements, including bending, twisting, and shearing.
The findings were published in the journal Nature.