MIT’s ‘roboats’ autonomously form bridges across bodies of water

Need to bridge a wide pond or canal in a pinch, or perhaps a backyard pool? Robots pioneered by researchers at MIT and the Amsterdam Institute for Advanced Metropolitan Solutions (AMS Institute) might fit the bill. Dubbed robotic boats, or roboats, they’re autonomous platforms designed to “shapeshift” at will by reassembling into different configurations.

As MIT’s Rob Matheson explains in a blog post, the roboats — rectangular hulls packing sensors, thrusters, microcontrollers, GPS modules, cameras, and other hardware — are the fruit of the ongoing Roboat joint project between MIT and the AMS Institute. Its longstanding goal is to create structures capable of ferrying goods and people along Amsterdam’s over 160 canals, and of self-assembling into bridges that could help reduce pedestrian congestion.

This latest development — a novel algorithm handles planning and tracking, enabling groups of roboats to travel a path while avoiding collisions — is the culmination of three years’ worth of work. According to director of MIT CSAIL Daniela Rus, it builds on 3D-printed prototypes that could move along predetermined routes with latching mechanisms that targeted and clasped onto each other. “We’ve enabled the roboats to now make and break connections with other roboats, with hopes of moving activities on the streets of Amsterdam to the water,” said Rus.

The roboats consist of two basic components — coordinators and workers — sporting four propellers, a wireless microcontroller, and automated latching mechanisms and sensing systems. Coordinators, which are aware of and can communicate with all connected workers, additionally have GPS for navigation and inertial measurement units responsible for computing localization, pose, and velocity.

Connected roboats compare the differences between their initial shape and new shapes before figuring out whether they should remain still or move. Then, they’re assigned a time to disassemble and a new position, at which point they precompute collision-free regions and find the shortest trajectory to their final destinations. Thanks to a battery of optimization techniques, the researchers say it takes less than 100 milliseconds to identify safe paths before the coordinator estimates the poses and velocities to move each roboat into the target locations.

In real-world experiments staged in an MIT pool, the paper’s coauthors managed to get the roboats to rearrange themselves from a connected straight line, where they were latched together at their sides, into a straight line connected at front and back, as well as an “L.” They leave to future work scaling the algorithm to roboats up to 4 meters long and 2 meters wide (the prototypes were 1 meter long and half a meter wide), and ensuring the system is robust enough to contend with severe weather (such as heavy rain) and connect to slippery structures like the walls of canals.

Within a year, the team hopes to deploy a dynamic bridge across a 60-meter canal between the NEMO Science Museum in Amsterdam’s city center and an area that’s under development, as part of a project called RoundAround. If all goes according to plan, roboats will sail in a continuous circle across the canal, picking up and dropping off passengers at docks and stopping or rerouting when they detect anything in the way.

“This will be the world’s first bridge comprised of a fleet of autonomous boats,” said MIT professor Carlo Ratti. “A regular bridge would be super expensive, because you have boats going through, so you’d need to have a mechanical bridge that opens up or a very high bridge. But we can connect two sides of canal [by using] autonomous boats that become dynamic, responsive architecture that float on the water.”