Video: Snail-inspired swarm robots cooperate to build structures on demand

A new video demonstration from researchers at the Robotics and AI Lab at the Chinese University of Hong Kong (CUHK), Shenzhen, shows how a group of spherical, snail-inspired robots can collectively solve a physical transport problem by reconfiguring themselves in real time. 

In the experiment, five identical robots work together to move one unit from a lower platform to a slightly higher one across a gap, without ramps, rails, or predefined structures. Instead of relying on a fixed mechanism, the robots assemble their own temporary structure. Four units stack vertically to form an inclined column between the two tables. 

A fifth robot then climbs onto the stack, adjusting its position as the lower robots subtly shift to redistribute weight and steepness. For a brief moment, the group functions as a single articulated body, creating a living ramp that allows the robot to reach the higher surface. Once the task is completed, the structure can be dismantled, returning each unit to independent motion.

A swarm designed to move and connect

According to the study, the system developed by the CUHK researchers is a 3D terrestrial, self-reconfigurable robotic swarm composed of compact, dome-shaped modules often described as “snail bots.” Each robot can operate independently or physically connect with others to handle obstacles such as steps, gaps, trenches, and ledges.

The demonstration captures key ideas from a recent paper in Nature Communications by the CUHK-Shenzhen research team. How small, mobile robots can combine into larger, functional structures while retaining the ability to separate and move freely.

The paper addresses a common limitation in ground-based robotic swarms. Many systems are either highly mobile but weakly connected, or strongly connected but slow to reconfigure and prone to losing mobility. The snail-inspired swarm attempts to balance both by using a hybrid connection strategy inspired by land snail behavior.

Each robot is equipped with two distinct connection modes. The first, described as a free mode, prioritizes mobility. It relies on a magnet-embedded tracked module that allows the robot to roll forward, rotate in place, and form moderately stable connections suitable for routine movement and quick adaptation. This mode reflects how snails move efficiently under normal conditions.

The second, known as strong mode, prioritizes stability. It uses a vacuum-based suction mechanism enhanced with directional polymer stalks to generate robust adhesion when the swarm needs to support loads, bridge gaps, or climb. In the paper, this mode is compared to a snail’s stronger adhesive response when disturbed. 

By assigning different roles to each mode, the system can switch between fast reconfiguration and high structural stability as conditions demand.

Simple units, collective intelligence

Visually, each robot has a smooth, matte spherical shell with most of its mechanical complexity hidden inside. A single-tracked module runs along the underside, giving the robot steady traction without exposed arms or protrusions. This minimal design allows the robots to slide past obstacles and make clean contact with one another when assembling.

The cooperative transport video highlights how these design choices translate into behavior. Even when stacked and serving as part of a larger structure, no robot becomes passive. Each unit continues to adjust its orientation and contact forces locally, contributing motion, adhesion, and balance. 

The overall structure emerges through coordination rather than rigid assembly, and it exists only as long as the task requires. This gives us a robotic swarm that does not rely on a single body plan, but instead builds one on demand, using simple modules to achieve complex, adaptive behavior.