Uncrewed Systems Technology 043 l Auve Tech Iseauto taxi l Charging focus l Advanced Navigation Hydrus l UGVs insight l MVVS 116 l Windracers ULTRA l CES 2022 show report l ECUs focus I Distant Imagery

44 Focus | Battery charging proper coil alignment has been achieved, to initialise the subsystems for wireless charging, ramp up to full power, perform active wireless power transfer, and terminate the charging session. All of this can be fully automated. Foreign object detection The key area for safety for wireless charging is foreign object detection (FOD). With large amounts of energy passing between the coils, a metal object such as a coin or a can on the charging pad can heat up and cause problems, for example melting the pad and damaging the coil. FOD can be achieved in a number of ways. Capacitive sensors in the pad can be used to monitor the performance of the coils. A metal object on the pad changes the capacitance, allowing its presence to be detected. That does not necessarily detect organic objects, such as an animal on the pad in a garage, though. Optical sensors around the edge of the plate using infrared LEDs and photodiode detectors or even Lidar can be used to detect both metal and organic objects on the pad and switch off the charging process if an obstruction is detected. For a street-based system, an object such as a coin on the pad might get hot if there is current in the pad. Opportunity charging needs to avoid this, and so will probably require FOD. A depot is a more controlled environment, and even if there is a coin or metal object on the pad it won’t damage the ground coil or the vehicle. The FOD is achieved with an array of sensors in the ground pad. This has to be isolated from the power transfer field and is achieved using a combination of filtering and monitoring the voltage induced in the coil by a metal object. Monitoring the charging pads for foreign objects will be part of determining whether a vehicle can use the charging system. If not, it will be directed to another charging site. Lidar imaging is being explored to map the underside of a vehicle as it moves over a charging pad, to automatically register the type of vehicle and modulate the power accordingly to provide a higher level of charging to a system that could support it. The Lidar would also be used for FOD and other applications such as surveillance and security. Autonomous trucks and ships will require higher levels of power for fast charging, which requires different coil designs for a three-phase supply. Opportunity charging One system for opportunity charging is for an autonomous bus that would be charged for 7-10 minutes every hour while waiting at stops. It can be used for up to 16 hours a day, maintaining a 75% state of charge throughout the day, and nearly doubles the useable power from the bus’ battery pack. The system is modular and consists of four charging pads connected in parallel on the vehicle, with each pad capable of delivering 50 kW of power to the battery. The ground side of the system is ruggedised and installed in the roadway. The charging electronics cabinet is located near a bus stop, and the first system has been installed in the US. Wireless systems are also suitable April/May 2022 | Unmanned Systems Technology A BlueHalo Intense Eye V2 UAV charging from a wireless power pad (Courtesy of WiBotic) EVs in Austria taking advantage of opportunity charging (Courtesy of Easelink)