Unmanned Systems Technology 005 | Selex ES Falco UAV | Sense and avoid systems | RCV Engines DF70 | DSEI show report | Fuel cells | CUAV Expo, InterDrone and CUAV Show reports | SLAM

60 Show report | DSEI 2015 not due to fatigue or anything, but wear. You get increased radial play, the shaft moves too much and at a certain point the customer decides it has failed. “So it is always recommended to use a lubricant. But if you compare all-steel, hybrid and all-ceramic bearing dry running, the hybrid and the all-ceramic have better properties – lower friction, longer lifetime and less wear,” she said. Working with customers, she explained, enables faster development cycles and the design freedom to incorporate features such as flanges, threads and anti-rotation devices, offering faster installation and easier handling. Developing applications in partnership with customers brings further benefits. “We bring the bearing knowledge, they know their system,” Norta said. German start-up Dedrone has developed a system to detect unmanned aircraft in flight. The system, DroneTracker, combines established graphics processor unit (GPU) technology with microphones and two types of camera, all of which can be connected via Ethernet. Dedrone’s DroneTracker uses a combination of GPUs, microphones and two types of camera The system uses a combination of sensors for detection. An Ultra HD (UHD) camera can pick up images up to 100 m distant, and the image recognition algorithms running on an array of GPUs in a Tegra K1 processor from Nvidia can identify and track objects in the air. This provides four high-performance ARM Cortex-A15 cores running at 2.3 GHz with an array of 192 GPUs for the image processing. A standard HD camera is used to identify areas of the field of view for the UHD camera to analyse for movement by subtracting the background image. The HD camera not only provides real- time video of the incident, but records the video as well, and the system can be configured for 720p resolution for faster UAVs or 1080p for more detail, and also operate in a low-light mode for monitoring at night. Regarding the two microphones, the DroneTracker uses one to pick up the identifying frequencies of a UAV’s brushless dc electric motor, at 13 kHz to 40 kHz, via a fast Fourier transform in the processor. The other microphone monitors the background noise around the tracker itself, and subtracts this from the first signal for more accurate measurements. Dedrone has added tighter integration with existing security monitoring systems via SNMP networking capabilities to notify staff if a UAV is approaching a facility or restricted area. The Ethernet port also connects the DroneTracker to the cloud, which is said to allow the system to learn faster and for detection to improve continuously. The HD camera operates in temperatures from -20 to +70 C and, as it is intended to be mounted on the exterior wall of a prison or stadium, it is housed in an IP54 enclosure made of weather-resistant and dust-proof plastic. Cella Energy’s managing director Stephen Bennington provided more insight at the show into the company’s hydrogen gas generator for UAV fuel cells, on which we reported in our previous issue. The storage material is a chemical hydride in pellet form that releases the gas when heated to about 120 C. When Cella’s gas generator which contains the Cella material is connected to a fuel cell, it can provide three times more electrical energy per kilo than lithium-ion batteries. “We can provide extremely lightweight power,” Bennington said. The gas generator is a pressure vessel containing printed circuit boards with pellet heaters etched onto them. The pellets are embedded in an insulating polyamide foam matrix, and heating them one by one produces a controlled flow of hydrogen. Thermal management is complex, with much work going into minimising heat transfer by radiation, convection and conduction, Bennington said. With no moving parts, there is little to go wrong and, with no hydrogen gas in the system before first use, it is safe to transport. “Our material is not air-sensitive, so if you breach the containment nothing happens,” he added. The generators are sealed, but units can be returned for refilling. Dec 2015/Jan 2016 | Unmanned Systems Technology