USE Network launch I UAV Works VALAQ l Cable harnesses l USVs insight l Xponential 2020 update l MARIN AUV l Suter Industries TOA 288 l Vitirover l AI systems l Vtrus ABI

63 degrees of freedom in the prototype mAUV’s control system. Having designed it from a blank sheet ourselves, we have complete freedom to alter the software and hardware in ways that would be impossible with a closed system. “As we can modify and test out the vehicle as we please, we can rapidly improve our simulated model [or ‘digital twin’] of the mAUV, to increase the accuracy of how we predict it will behave, such as when operating near structures or how currents or waves influence its motion.” Egbert Ypma, the team leader for autonomy and decision support, adds, “We’ve developed common components for use on the mAUV and our previous autonomy platforms, such as our small, sailing wavebuoy or our 6 m RHIB. This, and the way the mAUV is designed, make it quite easy to test or demonstrate new application payloads, different actuator configurations and so on.” ROV control, AUV speed The availability of six degrees of movement control came from a few key project requirements that had been decided from the outset. One was a desire to combine the accurate hovering and orientation control of an ROV with the high forward speed and range of torpedo-shaped AUVs. This flexibility in vehicle control enables an AUV capable of manoeuvring in confined spaces (providing that the space allows for the mAUV’s length and diameter in the first place of course). It also means potentially major improvements in acoustic sensor data quality, as the body of the AUV can always be tilted to point its scanning sonar in the optimal direction (and hold that position and orientation over the required duration) for gathering close imagery of subsea assets or other survey targets. Hans Cozijn, MARIN senior project manager, says, “Our approach was to start development with a full six degrees of freedom in control. Later on, depending on the application or end- user’s requirements, it will be reasonably easy to reduce the number or power of the thrusters, or remove one or more degrees of freedom, to simplify the system according to a given need.” Haite Van Der Schaaf, principal project manager for measurement systems, adds, “As the vehicle design is modular, we can add passive fins or active rudders to investigate how it performs using alternative design configurations used across different ROVs, AUVs, glider-type vehicles and so on – all using the same baseline of hardware and software.” In its current form, the AUV has no need for fins or rudders (aside from just one fin on top of the hull, which also acts as a wi-fi antenna housing). As MARIN’s research has noted, relying on fins and rudders means having no orientation control when forward motion is zero – a problem that the mAUV has neatly avoided. As mentioned, the mAUV uses 12 thrusters in total. Control in the vertical and transverse directions is achieved via eight of these: two pairs of tunnel- mounted thrusters near the front (one pair pointing vertically and one pointing horizontally), and two more identical pairs near the back. The MARIN team installed thrusters in pairs rather than singularly, so that the mAUV could roll in each axis as well as move sideways as needed. Also, if one thruster breaks down during a mission, the mission can still continue, albeit with lower overall thrust in the direction of the thruster concerned. Forward propulsion comes from four backward-facing thrusters MARIN modular AUV | Digest Unmanned Systems Technology | June/July 2020 The mAUV has been designed for indoor basin experiments, to trial and advance MARIN’s UUV technologies The mAUV’s main propulsion section is at the rear, with batteries and control systems in the middle and a sensor dome at the front