56 a 20 kW Kohler diesel engine at the back, a 120 kW Yasa axial-flux, electricmotor generator mounted forward of the engine via a transfer gearbox, and a 400 V battery pack at the front, which is designed and assembled in-house. By making the pack in-house, IDV-R can select different cells for different advantages. Nickel manganese cobalt chemistry cells are often chosen where energy density is prioritised, while lithiumtitanate oxide cells are increasingly picked when safety takes precedence, including situations where the UGV’s battery must be trusted to sit safely after rough treatment (that is, with minimal chance of combustion). The system can run for just over 20 km on battery power alone, with 250 km endurance in hybrid mode when accounting for the current diesel fuel tank. Having a parallel-hybrid configuration allows the Viking to run in all-electric mode for stealth, in diesel-and-electric hybrid mode for maximum range, or a series-style charging mode for energy and range security. Power can also be run offboard, using the Viking as a generator for powering or recharging soldiers’ equipment and other devices. “The diesel engine and electric motor connect via a custom transfer box from Compact Orbital Gears in Wales,” Maloney says. “The high-performance, axial-flux motor is especially useful for getting a lot of power either into the battery or into the wheels. Yasa’s technology packs a lot of power and torque into a very small form factor, and uses a very unique oil-cooling system to achieve that. Since we have been using them, they’ve been bought by Mercedes because of their leading design.” Cooling As the Viking is designed to operate in not only hot desert environments, but also in cold tundra or Arctic conditions (a couple of units having been recently supplied to the Norwegian Defence Research Establishment), engineering a thermal management system that was capable of thoroughly cooling or heating the temperature-sensitive lithium-ion battery pack was critical. Managing the battery temperature helps to get the best performance from it. “At the back of the vehicle we have a cooling pack with a high-temperature radiator for the diesel engine and a low-temperature radiator for the autonomy electronics, battery pack, inverter and motor. We also integrate chillers and heaters into the liquid cooling loop, depending on the customer’s environment, to manage the battery via refrigerating or warming the water-glycol coolant,” Maloney says. Autonomy sensors While the Viking can be remotely controlled and teleoperated (the former mode intended for when the UGV is in close line-of-sight and the latter adding a low-latency video feed for a GCS operator to see where they are going), full autonomy has been developed since the early days of the project. “Autonomy for us includes modes for following routes, and for intelligently following a person or a vehicle, like in a convoy, as well as a mode for searching or mapping independently across routes and areas,” Davis says. To execute each of these modes, the Viking integrates a central stereo camera at the front for 3D perception ahead of the UGV, as well as Lidar mounted similarly at the front. Lidar is an active system and can risk giving away the Viking’s position in some situations, but it has advantages in range, accuracy at range and night-time functionality over stereo vision that make it valuable. “And then we have a range of different perception cameras we can install, including EO daylight cameras, thermal cameras, and additional stereo cameras or Lidars for the level of situational awareness the mission requires, and its budget and performance targets,” Maloney says. “Wherever possible, we have gone for sensors with the maximum field of view, resolution and update rates we could find, but there’s rarely hard performance requirements from the customer on those. It is currently dictated by autonomy performance requirements and cost.” IDV-R can install different grades of IMU and GNSS receiver, including when end-users want a civil receiver or full military GNSS capability. Around the centre of the vehicle sits the modular autonomous control equipment June/July 2024 | Uncrewed Systems Technology A robust thermal-management system helps Viking operate in hot desert climates, as well as freezing conditions such as the north Norwegian winter
RkJQdWJsaXNoZXIy MjI2Mzk4