Issue 39 Unmanned Systems Technology August/September 2021 Maritime Robotics Mariner l Simulation tools focus l MRS MR-10 and MR-20 l UAVs insight l HFE International GenPod l Exotec Skypod l Autopilots focus l Aquaai Mazu

27 Maritime Robotics Mariner | Dossier The system has been proven in offshore operations in various vessels, including the Mariner, over the past 10 years. A typical combination of navigation sensors consists of a GNSS compass, which combines a satellite navigation receiver with an RTK correction capability, and a multi-axis IMU in a closely integrated package. This can be supported by a survey-grade INS, which would normally be part of the support system for one of the payloads. Other elements of the navigation system include a solid-state compass, a wind sensor and a depth transducer. There are three packaging options for the vehicle control station (VCS), the most elaborate being a containerised multi-monitor system. This has a chair and a joystick for the operator, along with interfaces for sensors such as radars and video cameras as well as maritime staples such as an electronic chart display and information system and an automatic identification system (AIS). Equivalent functionality can also be provided in more compact forms, such as a rack-mounted computer and monitor, and even a single laptop for field use. In each case, only one person is needed to operate the Mariner. As long as there is a functioning comms link, the vessel’s status and any alarms – both visual and audible – are transmitted to the operator. Hovstein says the level of supervision required is highly dependent on the risk analysis for the mission and the area in which the ASV is working; normally though the operator will stay in the loop for safety, while operating the payload in parallel. Although a Mariner operator does not have to be a fully certified mariner, such a qualification or simply having a maritime background helps, he says. Collision avoidance relies on the alarms and suggested evasive manoeuvres generated by the vehicle control software, which is programmed to implement maritime collision risk reduction rules. These ‘COLREGs’ are used as the basis for the weightings in the collision avoidance algorithms. The system is programmed to suggest emergency course changes as early as is practical, calling for ‘substantial action’ to provide a wide margin of safety. Inputs that the system uses to compute a collision risk come from the radar, the AIS and camera detections processed in Maritime Robotics’ own fusion engine. The company developed its collision avoidance algorithms partly through its participation in the Autosea programme, an effort run during 2017 that involved cooperation with the Norwegian University of Science and Technology, the classification society DNV GL and Kongsberg Maritime, and which focused on automated situational awareness through sensor fusion. Maritime Robotics’ activity within Autosea also included full- scale experiments in the use of radar tracks as inputs to closed-loop decision- making. This same consortium is now conducting a new project known as Autosit, which is focused more on the fusion of multiple sensors to help generate the situational awareness picture in uncrewed operations and which builds on the work done in Autosea. Hovstein says, “The collision avoidance algorithms developed in Autosea are built into our autonomy framework, and are used to give suggestions for safer navigation. The operator stays in the loop for legislative reasons.” Formation control Patented in 2010, the formation control is software-driven and relies on real- time comms between a lead USV and a group of followers, with the original vision for such multi-USV operations being managed from a manned survey vessel. “A mother ship typically has a crew of 20 or 30 people, but with two, three or four USVs in a sweep you can multiply the amount of data gathered without adding more crew,” Hovstein says. In the simplest type of operation, the user merely defines a range and bearing the follower USV needs to maintain in relation to the mother ship and presses the start button. However, the system has more advanced capabilities. For example, a swarm of USVs equipped with multi-beam echo sounders can be commanded to overlap their swathe widths by a given amount, say 20%; then, as the swathe width on the seabed varies with the depth of the water, the USVs automatically adjust their lateral separation to keep the overlap constant. A recording of a recent at-sea demonstration of the capability using three Mariners showed the operator’s moving map view of the formation in which the lead vessel turned, and Unmanned Systems Technology | August/September 2021 Suitable for laptops or multi-screen consoles, the Mariner’s vehicle control station enables single-person, multi-vessel operations with a high level of sensor fusion and collision avoidance automation