MIT has unveiled the latest version of the robotic boats it is developing for the city of Amsterdam that are intended to autonomously move passengers, goods and maybe garbage along the city's 165 canals in the near future. The new iteration of these "Roboats" has been given the ability to locate and dock with one another, even in difficult conditions.

For centuries, Amsterdam's canals have been famous for their quiet beauty, the wonderful architecture along their banks, and the crushed pigeons under the drawbridges. Though they cover a quarter of the city's surface, they've largely fallen out of practical use in recent times. Now, MIT and the Amsterdam Institute for Advanced Metropolitan Solutions (AMS Institute) are working on developing a fleet of robotic boats that use sensors, cameras, thrusters, micro-controllers, and GPS to autonomously navigate the canals.

The purpose of the Roboats is not only to cut down congestion on Amsterdam's streets by moving some of the traffic to the canals, but also to combine on command to form temporary work barges, bridges, stages, or food markets. In addition, they can act as roving monitors of the city's infrastructure and air and water quality.

So far, MIT tested simple prototypes on the Amsterdam canals in 2016, and in 2018 the team developed a quarter-scale version with a 3D-printed hull, power supply, Wi-Fi antenna, GPS, Inertial Measurement Unit (IMU), minicomputer, and microcontroller, as well as advanced trajectory-tracking algorithms.

The latest version is still quarter-scale, but now has LIDAR, cameras, and computer image algorithms for navigating the canals. It also has more advanced algorithms and sensors that allow the Roboats to locate one another in a swimming pool at MIT and in the Charles River in Massachusetts, and latch onto one another with a precision measured in millimeters.

The robotic boats managed this using a ball and socket mechanism installed on each of the four sides of the vessels. The ball looks like a shuttlecock with a cone-shaped rubber body and a round metal head, while the socket component has a funnel to guide the ball to the locking mechanism by means of a laser beam that detects the ball and activities three arms that reach out and grasp it.

This is aided by AprilTags, which are sheets of paper imprinted with a QR-like augmented reality tag that enables the barges to calculate their positions relative to each other. With one Roboat sitting stationary, a second homes in on the tag that allows it to work out its position and orientation. When it comes within a meter of the target, the docking boat builds up a 2D map that allows the computer to navigate and properly line up the two vessels for docking.

The funnel mechanism can compensate for wave actions, but if the winds and waters are too rough, the Roboat can stand off and try again. MIT says that the vessels can dock in about 10 seconds if they don't decide to have another go.

The hope is that the new locking mechanism will not only allow the Roboats to form platforms, but also to act as roving trash collectors that can patrol the canals at night, collecting Roboats holding trash containers and dragging them to garbage collection facilities. However, the more immediate goal will be to build a full-sized version of the boats that will be more stable and will include tentacle-like rubber grippers that will allow the docking funnel to latch on more securely and with better control.

"The aim is to use Roboat units to bring new capabilities to life on the water," says Daniela Rus, director of the Computer Science and Artificial Intelligence Laboratory (CSAIL). "The new latching mechanism is very important for creating pop-up structures. Roboat does not need latching for autonomous transportation on water, but you need the latching to create any structure, whether it's mobile or fixed."

The research was presented in a paper at the 2019 International Conference on Robotics and Automation.

Source: MIT