Issue 41 Unmanned Systems Technology December/January 2022 PteroDynamics X-P4 l Sense & avoid l 4Front Robotics Cricket l Autonomous transport l NWFC-1500 fuel cell l DroneX report l OceanScout I Composites I DSEI 2021 report

30 higher levels of reliability, customisation and automation,” Dr Petrov says. “We continue to work closely on this with our control partners Applied Navigation, KH Unmanned and Aerial Robotics Australia.” For commercial users, PteroDynamics typically uses Ardupilot systems such as the X2.1 777 board from Mayan Robotics, as it is an open source solution with a large community of developers providing ways to adapt and tune different algorithms to work with the hardware. “The additional code we’ve written on top of Ardupilot’s master branch is actually very minimal. That’s enabled us to fly the aircraft in different ways and leverage the broader Ardupilot ecosystem where we’ve needed to, thereby supporting a wide range of peripheral devices,” Whitehand notes. “It also means our commercial customers can easily make use of other Ardupilot add-ons for whatever niche missions or manoeuvres they want to carry out.” While some among people in the defence services are increasingly interested in open source technology for its community-driven agility, many are still dubious of having such transparency in their subsystems. For those users, including the US Navy, PteroDynamics has integrated Applied Navigation’s Quattro autopilot to operate the X-P4. “Applied Navigation implemented our flight control modules and gain scheduling into the Quattro,” Whitehand says. “What that gets us compared with the very flexible, open source Ardupilot is a far more powerful hardware architecture that can support the kind of peripherals we need in order to deliver the X-P4 to a government or military customer, or easily scale up the aircraft for similar customers who might want to carry more weight. “Applied Navigation also provides the Vigilant Spirit operator interface, which many US defence-sector customers are experienced with. And I understand Applied Navigation was also recently approved for BVLOS operations in Spain, which we feel has further validated our choice to go with the Quattro in the defence market.” The radios and antennas are also installed throughout the fuselage, rather than in the routinely mobile wings. For standard-issue comms, dipole omnidirectional antennas enable data uplinks and downlinks over the 900 MHz and 2.4 GHz bands. “We’ve played a bit with our ground planes and antenna positioning, and we’re confident now that we have solid comms over a 10 mile distance, which is far more range than we need,” Whitehand says. “That said, we have the backbone to accept any IP mesh radios, satcom December/January 2022 | Unmanned Systems Technology One of PteroDynamics’ propulsion testing rigs Velocity HS ESCs from Currawong are installed on the X-P4 to ensure sufficiently reliable operations for its US Navy customer