Issue 41 Unmanned Systems Technology December/January 2022 PteroDynamics X-P4 l Sense & avoid l 4Front Robotics Cricket l Autonomous transport l NWFC-1500 fuel cell l DroneX report l OceanScout I Composites I DSEI 2021 report

76 C ruising at half a knot on half a watt for months on end while gently rising and falling through the water column is, famously, the modus operandi of the buoyancy-driven glider. After about 20 years of commercial operations, the gliders’ contributions to oceanic science are widely recognised, but the vehicles have yet to be adopted on a scale matching their potential. With its small OceanScout however, start-up Hefring Engineering has set out to change this. “From our experience as users, and from speaking with ocean scientists and marine technologists, the main obstacles to wider adoption have been total mission cost and complication,” says the OceanScout’s programme manager Chris Ordonez. “We are lowering the entire cost of ownership, not just that of the vehicle but the costs of deployment and recovery, personnel and expertise.” Glider challenges Buoyancy-driven gliders are not the first vehicles to use their ability to alter their buoyancy to move up and down in the water column in order to take measurements. That honour arguably belongs to Argo floats, which are drifting profiler vehicles, but gliders are much more capable and inherently more complicated because they manoeuvre freely through the water. Naturally, their navigation and ‘flight’ control systems require significant engineering design effort on their mechanics and electronics as well as embedded software, a challenge that is presented by all gliders and one that is also reflected on the operational side. Among the practical operational challenges presented by traditional gliders are their size and weight, which mean that single-person operations are difficult and that teams of three or four are required to recover them from the water and handle them on land, Ordonez notes. He also observes that their construction tends to render maintenance more difficult than it needs to be, as getting to the components that need care takes numerous delicate steps and presents hazards to the wiring and internal electronics. “Controlling the glider remotely also poses challenges, as the satellite data connections are often inconsistent. The high vehicle cost also means each mistake or setback has more impact on teams with a few or sometimes single vehicles. Hefring has addressed each of these issues, including innovative methods for our satellite comms.” Peter Donaldson finds out how this buoyancy-driven UUV removes the key barriers to widespread scientific research in our oceans Glide path December/January 2022 | Unmanned Systems Technology The OceanScout is a miniature buoyancy-driven glider designed to ‘democratise’ ocean data gathering (Images courtesy of Hefring Engineering)