Unmanned Systems Technology Dec/Jan 2020 | Phoenix UAS | Sonar focus | Construction insight | InterGeo 2019 | Supacat ATMP | Adelan fuel cell | Oregon tour | DSEI 2019 | Copperstone Helix | Power management focus

6 Mission-critical info for UST professionals Platform one Researchers have added a ‘shape- shifting’ capability to a fleet of autonomous boats (writes Nick Flaherty). The fleet is designed to autonomously separate and reassemble into various configurations to form floating structures in Amsterdam’s canals. The aim is to have the boats transporting goods and people, collecting rubbish or self- assembling into ‘pop-up’ platforms such as bridges or stages to help relieve congestion on the streets. The boats have simple rectangular hulls fitted with sensors, thrusters, microcontrollers, GPS modules, cameras and other hardware, and are part of the Roboat project between MIT and the Amsterdam Institute for Advanced Metropolitan Solutions. The team has developed an algorithm that enables the boats to arrange themselves as efficiently as possible. The algorithm handles all the planning and tracking that enables groups of them to unlatch from one another, travel a collision- free path, then re-attach themselves on the new set configuration. Groups of the linked boats can rearrange themselves into shapes including straight lines, squares or other configurations such as rectangles or ‘L’ shapes in a few minutes. More complex shapes may take longer, depending on the number of units being moved – which could be dozens – and the differences between the shapes. “We’ve enabled the roboats to make and break connections with other roboats, and hope to move activities that take place on the streets of Amsterdam onto the water,” said Daniela Rus, director of MIT’s Computer Science and Artificial Intelligence Laboratory. “A set of boats can come together to form linear shapes as pop-up bridges, if for example we need to send materials or people from one side of a canal to the other. Or, we can create wider pop-up platforms for flower or food markets.” The algorithm includes functions for autonomous planning, tracking and connecting groups of the roboats. This is handled by defining two types of units: coordinators and workers. Workers connect to one coordinator to form a single entity, called a ‘connected vessel platform’ (CVP). All the coordinator and worker units have four propellers, a wireless-enabled microcontroller and several automated latching mechanisms and sensing systems that enable them to link together. The coordinator units also have GPS for navigation and an inertial measurement unit that computes localisation and velocity. Workers only have actuators to help the CVP steer along a path. Each coordinator is aware of and can wirelessly communicate with all connected workers. During shape-shifting, all the connected CVPs in a structure compare the geometric differences between its initial shape and the new shape. Each CVP then determines whether it stays in the same spot or needs to move. Each moving CVP is then assigned a time to disassemble and adopt a new position in the new shape. The CVPs uses a custom trajectory- planning technique to compute a way to reach its target position without interruption, while optimising the route for speed. To do so, they pre-compute all the collision-free regions around it. Surface vessels Canal fleet takes shape December/January 2020 | Unmanned Systems Technology x The boats are designed to rearrange themselves into any shape according to the task in hand