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56 Four such mechanisms in total bring both batteries flush with the edges of the backbone and bring the power and data connectors securely together. Payloads will include those carried in an underslung position, so Griff has developed a quick-release system that can be operated remotely. A related system enabling the vehicles to pick up loads remotely is a planned future development. Payloads are powered by a 12 V supply through the SAL connectors, whose pin-outs also include data connections either directly to the autopilot or the payload’s own computer. Those integrated so far, in addition to the radar, include Lidars, EO/IR cameras and the underslung load carriage and release mechanism. Griff is also working on the prototype of an agricultural spraying unit, which flew for the first time in March 2018. With a capacity of 30 litres, the unit was built as a test platform to give an insight into spray boom and tank design, and their effects on endurance, flight behaviour and spray patterns. The plan is for this to lead to a production-standard 50 litre unit for use on vehicles built on the Griff 2.0 architecture, making use of the SAL system and a fast refill design to minimise turnround times. This combination will, for example, be able to spray about 4 hectares per hour with a coverage of 25 litres per hectare. Radar integration While the navigation system can be customised to suit the needs of the operator and the mission, the baseline installation uses a combination of GNSS, barometric pressure sensors and Lidars. For more advanced operations it can, for example, include a micro-radar and a 360° Lidar for precision navigation and take-offs and landings in conjunction with a digital terrain map. To develop specific mission-focused systems and projects, Griff works with a variety of partners. In the civil sector, for example, it is working with autonomous flight specialist Near Earth Autonomy. It is also working with UK radar specialist Plextek DTS to integrate the latter’s new low size, weight and power Clarus electronically scanned terrain-following and avoidance radar for military applications. Griff got to know Plextek when they were both on contract to support the UK Ministry of Defence’s Autonomous Last Mile Resupply project run by the Defence and Security Accelerator and the Defence Science & Technology Laboratory (DSTL). The radar can measure a UAV’s height above ground level, detect obstacles including thin wires and will also measure the complexity of the terrain. This assessment feeds into the process by which the system decides whether it is safe to land in a particular area, a mode that is still at the experimental stage. Working independently, the radar needs no data feed from the aircraft but provides input to the autopilot via a UART connection. The autopilot interprets the radar as a range-finding sensor. “We can also provide data from other sensors via an Ethernet port to the radar, and then the radar creates a fusion with the IMU, Lidar or other sensors,” Forde explains. That is enough for the autopilot when flying the UAV at a fixed height above the ground. At the moment, he says, a technology demonstrator is flying on an off-the- shelf DJI S-1000 and is providing data; the next step is to integrate the Clarus system onto the Griff 135. The combination should start flying in July in support of the UK MoD/DSTL Innovation Autonomy Challenge, which is focused on difficult and congested environments. February/March 2020 | Unmanned Systems Technology With the batteries removed, the mechanism that secures the battery boxes to the backbone can be seen (Courtesy of Griff Aviation) We can provide sensor data via an Ethernet port to the radar, then the radar creates a fusion with the IMU, Lidar or other sensors