Building a Better Robot, Block by Block

Versatility is something that is highly prized, yet rarely seen, in the field of robotics. Due to limitations in existing hardware systems and control algorithms, robots tend to be built very much for a specific application. Unlike the general-purpose robots of science fiction, today’s robots can do one thing and do it well, but they generally cannot do much of anything else.

A team of engineers at Dartmouth and Rutgers recently got together to develop a completely new idea meant to make robots more adaptable. The modular system they created makes it possible to build shape-changing robots that can take on new forms as needed. The building block-like system may be in the early stages of development, but it has been proven that the modules can click together to make everything from walking robots to expanding temporary shelters. And if the structure gets too large for a person to manage, drones can help with the assembly process.

The system is made up of robotic blocks. Each 3D-printed block has eight rigid carbon fiber rods that extend outward from a center joint. Each rod is tipped with a 3D-printed endcap. These endcaps are connected to high-strength strings that can be extended or shortened via motors contained in the blocks. When endcaps are linked to other blocks via latches, this hardware makes it possible to change the shape of a group of linked blocks on command. A battery and onboard electronics, including a Wi-Fi module, inertial sensors, and a Raspberry Pi RP2040 microcontroller, allow the block to operate untethered for more than three hours.

The design is inspired by “tensegrity” structures, which form an architectural framework that combines rigid struts and flexible cables to create lightweight yet strong systems. By varying the length of the strings, each block can compress, stretch, or even grip objects. These small deformations, when multiplied across multiple connected blocks, create large, coordinated motions. That means a line of blocks can crawl like a snake, a cluster can form a tent frame, or a chain can span a gap to act as a bridge.

The endcaps feature a latch-and-magnet system designed for strength, error tolerance, and easy detachment. The magnets guide the blocks into alignment, while mechanical latches that are able to withstand loads more than a hundred times the weight of an individual module lock them firmly in place. A tiny servo unlocks the mechanism with minimal energy, allowing the blocks to disconnect and reconfigure when needed.

The researchers demonstrated a wide range of applications for their technology during field tests. Outdoors, the robots squeezed under logs and slithered through narrow openings. In one example, a board placed across a chain of modules became a stretcher strong enough to carry a human-sized dummy. While the robots cannot yet bear the full weight of a person, the system shows clear potential for emergency response, where rapidly assembled bridges or temporary shelters could make the difference in disaster zones.

Though still in the early development stages, the system has a lot of promise for the future. The team envisions air-droppable kits of robots that can self-assemble into bridges, scaffolds, or shelters, all while adapting to unpredictable terrain. It is, in essence, a toolkit for building whatever machine a situation might call for.