Snapping elastic rods power frog-like robot to outrun rigid legs across six terrains

Researchers at the UCLA Samueli School of Engineering and the University of Michigan have demonstrated a locomotion strategy that uses elastic rods instead of conventional rigid joints. The rods can be bent and twisted until they suddenly snap from one stable shape to another.

Each snap releases stored elastic energy in a rapid burst, enabling small robots to hop, flip, and swim. This mechanism echoes biological systems that store energy slowly and release it quickly to achieve powerful motion.

The team's frog-like robot reportedly uses these snapping rods to traverse six different terrains, outperforming designs with rigid legs. Because the rods can change shape repeatedly without complex motors, the system may offer a lightweight and durable alternative for small-scale locomotion.

Unlike traditional legged robots, the snapping-rod design stores energy in elastic deformation. When a rod is bent or twisted past a critical threshold, it rapidly flips to a new configuration. The researchers can tune the mechanism by adjusting rod geometry and material properties.

The frog-inspired robot coordinates multiple rods to generate fast, versatile movement. Rigid legs often struggle on soft or uneven ground because they cannot store and return energy as efficiently. The snapping rods also simplify control, since each snap is a discrete event.

Potential applications include search and rescue, environmental monitoring, and exploration in cluttered environments. The work suggests that controlled elastic instabilities could become a practical tool for small robots that must cross diverse landscapes.