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8 Platform one December/January 2018 | Unmanned Systems Technology Remotely operated vehicles (ROVs) are normally controlled from a ship, but now Rolls-Royce Marine in Norway has applied for a patent covering a system that consists of an unmanned surface vessel (USV) configured to operate ROVs either autonomously, according to pre-programmed instructions, or by remote control by personnel on land – or even an offshore platform (writes Peter Donaldson). Stored in a hold amidships in the USV, the tethered ROV would be lowered into and lifted out of the water via a moon pool (as used for marine drilling) by an automated launch and recovery system. A vessel control unit manages that Researchers at NASA are testing an adaptive algorithm that will be used in the latest heavy lifting space systems (writes Nick Flaherty). The Adaptive Augmenting Controller is designed to learn and respond to unexpected differences between an actual flight and pre-flight predictions, and make real-time adjustments to the autopilot system. It is being tested on Earth in an experiment called Launch Vehicle Adaptive Control (LVAC) by turning an F/A- 18 Hornet aircraft into an analogue of the Space Launch System (SLS). The software will be ready to run on the first test flight of the SLS, in 2019, and will be NASA’s first use of an adaptive control concept on launch vehicles. There are 20 test cases for the LVAC experiment to simulate abnormal conditions such as higher thrust than anticipated or the presence of wind gusts, to see if the algorithm responds as intended. procedure as well as the movements of the USV itself. The USV will also feature a dynamic positioning system (DPS) that will be programmed to prioritise the position of the ROV when controlling the USV, using both the USV and ROV control systems to keep the ROV in its desired position. The USV control computer will process a range of parameters, including the paid-out length of the tether, the tension in it between the ROV and the USV, and the tether management system. Through its comms system, the USV control computer will receive data on surface traffic, weather and other environmental data, along with information from its navigation system The SLS has a 70 tonne lift capacity and will carry an unmanned Orion spacecraft beyond low-Earth orbit to test the performance of the integrated system. As the SLS evolves, it will provide a lift capability of 130 tonnes to enable missions to Mars. “With an adaptive algorithm, we can be a little more responsive to anomalies in flight, like unpredictable winds, to ensure the vehicle stays on its trajectory,” about the USV’s own location and movements, enabling it to plot its position on electronic navigation charts. Rolls-Royce drawings show a propulsion system with two steerable azimuth thrusters for redundancy, one at the bow and one at the stern, and optional symmetrically positioned stabilising fin keels. A conventional set-up comprising a propeller and rudder could be used however. To allow for deployment of the system from a larger support vessel or from shore installations, the DPS could optionally include a docking module to interpret inputs from positioning sensors on the USV, such as a docking radar and navigation systems. researcher Jeb Orr explained. Fellow researcher Tannen Van Zwieten added, “It isn’t immediately clear how the aircraft could match important dynamic features of SLS, but it does. “We’re flying a similar trajectory on the aircraft as we have with the rocket, but the aircraft’s rotational dynamics are ‘slowed down’ to match the manoeuvring characteristics of a heavy- launch vehicle.” Choice of control for ROVs Heavy-lift system code tests Unmanned vessels Space vehicles NASA is using an F/A-18 Hornet to evaluate the algorithm