Unmanned Systems Technology 036

30 they wish, while the other runs Saab’s core control system and is highly protected. The computers communicate with each other and with the Sabertooth’s sensors and effectors over a Gigabit Ethernet backbone, although there are also RS- 232 and RS-485 serial interfaces. “Sometimes we have open interfaces that allow some of our more qualified customers to tap into that and send high-level commands to the system, depending on what their onboard equipment needs,” Siesjo says. That allows such customers to give the vehicle advanced behaviours that they have developed themselves, interfacing with Saab’s control system in a recognised and carefully managed way. While Saab’s software supports a range of sensors, the Sabertooth’s computers can also run third-party data collection software for sensor-intensive operations such as surveys. Packages in the Q-Suite from QPS, for example, come with drivers for sensors of many kinds. “We don’t necessarily get involved in integrating those unless the sensor needs to affect the vehicle’s behaviour in some way,” Siesjo points out. “Otherwise, you mount the sensor on the vehicle, hook it up to the Ethernet backbone and configure the software to make it aware that it has the sensor, and off you go.” Seabed docking stations The Sabertooth can be supplied with a docking station that can be installed on the sea floor. It’s a facility that acts as a protective shelter and provides power and data connections, both of which are wireless to avoid the use of physical connectors that would have to be coupled and uncoupled under water. “You could certainly order a vehicle with that sort of inductive connector, and we can also supply a docking station,” Siesjo says. “So far we haven’t delivered any commercially operational docking stations, but we have provided equipment for trials to our high-end customers.” Saab is a member of the Subsea Wireless Group, an oil and gas industry organisation whose purpose is to define standards that enable interoperability between wireless technologies including radio frequency, acoustic, inductive, optical and hybrid systems. Other members include offshore operators such as Equinor, sensor manufacturers and rival unmanned vehicle builders. Siesjo says these standards are now being finalised, an effort that is essential to developing resident vehicles and their supporting infrastructure. He emphasises that it is very much a work in progress. Equinor, for example, is looking to build infrastructure including docking stations and other facilities. An important piece of this infrastructure, he adds, is likely to be an underwater equivalent of the Automatic Identification System that is used to track surface vessels. Maintenance and resident ops With the prospect of resident operations for long periods on the sea floor, Saab is looking at the implications for maintenance and overhaul requirements. “That is something we are now getting into,” Siesjo says. “Current vehicles are built to the high-end ROV standard, which enables them to stay on the sea floor for weeks at a time, so the main concern there is corrosion. When we move more February/March 2021 | Unmanned Systems Technology Dossier | Saab Sabertooth AUV Docking stations will be a key element of the infrastructure required to support long-term resident AUVs on the seabed (Courtesy of Saab) Part of the demonstration in the NASA Neutral Buoyancy Laboratory involved connecting up to an optically enabled docking station (Courtesy of Sonardyne)