Issue 40 Unmanned Systems Technology October/November 2021 ANYbotics ANYmal D l AI systems focus l Aquatic Drones Phoenix 5 l Space vehicles insight l Sky Eye Rapier X-25 l FlyingBasket FB3 l GCS focus l AUVSI Xponential 2021

64 allow the Rapier to be landed safely. To help with this, significant redundancies are provided in the primary FCS components, such as a triple- redundant GNSS and INS architecture. For example, in the event of a loss of GPS reception, the three INSs can enable continued flight in line with the mission profile and its safety requirements. Also, in the event of one of the servo controls being blocked, the flight software is programmed to compensate and maintain the desired attitude. It has also been designed with resilience to cyber- attacks such as GNSS jamming and spoofing in its subroutines. Navigation systems Navigation can be performed fully autonomously or semi-autonomously through the use of GNSS waypoints to automate cruising flight, with GNSS antennas installed in the nose of the craft for satnav data. As mentioned, a triple-redundant GNSS/INS is installed for accurate pitch, roll and yaw data outputs, and Lucchesini notes that inspiration from his and his team’s past aircraft projects was key to designing its architecture. For example, their work on the M-346 led to that craft using the first ever quadruple-redundant, full-authority digital drive-by-wire system completely designed and flown in Italy. Schettini adds, “One of our boards in the FCS manages the algorithms for data monitoring, and also for the majority voting between the INSs, as we use triplex voting to identify the correct attitude parameters if one INS is off. “We also have a total of four GNSS antennas. Three give our users a triple- redundant flow of satnav data, with voting logic used to reject a wrong localisation reading, while the fourth provides georeferencing data directly to the payload.” Interestingly, three different GNSS/ INS units are integrated, as a means of avoiding similar failure modes by relying on the same design. SES says one of them is Advanced Navigation’s Spatial product, which uses a u-blox M8P as its GNSS module, and outputs horizontal position accurate to 2 m and vertical position to 3 m (although activating RTK processing will reduce the margin of error of both by 99%). The other two are models from SBG Systems and Lord Microsystems. Schettini says all three were selected for having similarly high performance levels, small form factors and robustness. Lucchesini adds, “If a strike to the front of the aircraft should render the GNSS antennas inoperable, we can rely on those MEMS INSs to provide enough stability for about 20 minutes, so that the GCS operator can perform a controlled return flight to a pre-designated recovery point. “In the event of total data link loss, the UAV can fly automatically towards that recovery point and land there. That’s key for the airworthiness authorities, whose prime concern is to protect people from an aircraft that can no longer be controlled, but the UAV is perfectly capable of continuing its mission autonomously.” GCS The proprietary GCS hardware and software for the Rapier X-25 have also been developed by SES, with an eye towards achieving the same level of assurance as the flight systems. Two fully redundant control and monitoring stations are provided for remote piloting and sensor payload management respectively. If the pilot command and control (C2) station should fail for example, the sensor management station can be switched to October/November 2021 | Unmanned Systems Technology The X-25’s standard payload is an Epsilon 140z from UAV Factory A pneumatic catapult is the standard launch system for the X-25, although another system is available for launching it from the roof of a car