Unmanned Systems Technology 023 I Milrem Multiscope I Wireless charging I Logistics insight I InterGeo, CUAV London & USA show reports I VideoRay Defender I OS Engines GR400U-FI I Ultrabeam Hydrographic Ultra-2 I IMUs

42 Focus | Wireless charging The charging system allows a group of UUVs to operate independently in deep water for up to a year, saving the cost of keeping a ship stationed nearby, which can reach $40,000 per day. The system is to be tested at depths down to 300 m in late 2019, with a version rated for 6000 m – full ocean depth – planned for late 2021. Laser systems Researchers in the US have been testing the use of lasers to charge UAVs, in what is called the Stand-off Ubiquitous Power/Energy Replenishment – Power Beaming Demo (SUPER PBD). This is looking at ways to charge a UAV in flight so that in theory it would never need to land. It uses a laser to shine light onto solar cells mounted underneath the wings of the UAV. The technology has been maturing for several years. In one development, researchers have demonstrated the first optical rectenna, a device that combines the functions of an antenna and a rectifier diode to convert light directly into DC power. It uses multi-wall carbon nanotubes on a conductive substrate with tiny metal- insulator-metal junctions acting as rectifiers fabricated on top. As the light waves hit the antenna it creates an oscillating charge that flows through the rectifiers. The difference of work functions between the nanotubes and the metal substrate provides a potential of about 2 eV, enough to drive electrons out of the carbon nanotube antennas when they are excited by light. The rectifiers switch on and off at petahertz (1000 THz) speeds, creating a small direct current, and the low capacitance, of the order of a few attofarads, enables the 10 nm diameter diode to approach efficiencies of 40%. To boost the delivery of the light to the UAV, researchers in Switzerland have lab-grown a diamond to transmit both power and data to an autonomous craft in the sky or in space. The nano-etched diamond operates with 1500 nm light, generating a collimated, narrow beam of around 30 W over a distance of several hundred metres. These beams could be operated in parallel to provide more power to a UAV in flight. There are many different techniques looking to recharge unmanned vehicles wirelessly and even in flight. All of them though are ahead of changes to the regulatory environment that will see more autonomous systems operating in the air beyond line of sight, greatly extending the range that UAVs can travel. Acknowledgements The author would like to thank Cristian Sobota at Divisek, Ben Waters at Wibotic, Michael Gottlieb at Solace Power and Leonid Plekhanov at GET Corp for their help with researching this article. December/January 2019 | Unmanned Systems Technology AUSTRALIA Lumen + 61 3 8787 1000 www.lumen.com.au CANADA Solace Power +1 709 745 6099 www.solace.ca GERMANY Skysense +49 152 5850 9872 www.skysense.co JAPAN Nichicon + 81 75 231 8461 www.nichicon.co.jp RUSSIA GET Corp +1 360 281 1116 www.getcorp.com SPAIN Divisek +34 660 699 868 www.divisek.es SWITZERLAND BRUSA Elektronik +41 81 758 19 00 www.brusa.biz USA Aerojet Rocketdyne +1 916 355 4000 www.rocket.com Evatran +1 804 918 9517 www.pluglesspower.com Lear +1 248 447 1500 www.lear.com Qualcomm Halo +1 858 587 1121 www.qualcommhalo.com Wibotic +1 650 265 7987 www.wibotic.com Witricity +1 617 926 2700 www.witricity.com Examples of wireless charging system suppliers