32 Dossier | Applied EV Blanc Robot UGV software stack, they also have some logic subroutines to help perform arbitrations; for instance, when there is slightly different sensor readings coming in from doubled- or tripled-up sensors,” Broadbent says. Assuming dual fail-operational redundancies has been a key part of the Digital Backbone architectural philosophy, going back to the original safety cases guiding Applied EV’s earliest engineering forays, which indicated to the company that compliant vehicles must, by design, have multiple power supplies going to each processor card. “You’ve got to make sure any one power connection could go down and the system would keep on running,” Broadbent explains. Above the CCU is a large connector board, which carries the autonomous driving inputs via two large, 50-pin rectangular connectors, and two main bus connectors, which are also 50-pin devices. A variety of smaller connectors are also present on this board. Below the CCU is the body control module (BCM), designed for managing vehicle ancillary systems – such as headlamps, infotainment and other cabin features, and locking devices – with about 200 I/Os designed into that board for such application-specific components. “The BCM can be programmable. It’s where our partners have full, open access to write their own functions – whether that’s for their own connectivity features, customer-facing content or for interfacing with some traditional vehicle components,” Broadbent adds. In addition to these boards within the Digital Backbone, Applied EV routinely assembles test boards, mounting electronics to perform automated tests, such as for electromagnetic radiation, extreme temperatures, vibration and other variables. “At an architectural level, TÜV SÜD has certified the Digital Backbone as representing a suitable foundation for fulfilling the requirements of ASIL-D per standard ISO 26262. We’re therefore continuing subsequent design and implementation phases towards mass production,” Broadbent says. Peering across the boards, one finds a heavy diversity of semiconductor types, from high-current switching transistors for the motor controllers to low-voltage network controllers for driving signal buses throughout the module, with the network carried from component to component by a wide array of rectangular and circular connectors. Rectangular connectors do, however, make up the majority, given their generally thinner shape than the circular ones, and automotive- and mining- grade connectors have been used to guarantee the Digital Backbone’s survival in the event of heavy exposure to the elements. “We recently moved to NXP’s S32G family of vehicle network processors, which are designed to accelerate the shift to simplified domain and zonal-based vehicle architectures,” Broadbent notes. Low-latency autonomous driving The pertinent performance metric targeted throughout the development of the Digital Backbone’s CAN and Ethernet buses has been latency. “The main highlevel principle guiding our engineering has been the safety rating of our by-Wire functionality,” Broadbent comments. A typical, commercially available road car with the bare minimum of modifications for autonomous driving is likely to experience latencies of up to 100 ms between the command being submitted by the ECU and that being executed at the tyre. Applied EV, by contrast, is targeting a latency of less than 20 ms. “Engineering a lower latency into your autonomous driving system corresponds to a faster response time. This is very important for performance and safety, because it frees up processes and bandwidth for addressing other tasks, so achieving that realises a tangible April/May 2024 | Uncrewed Systems Technology The company has strenuously combed through its algorithms to target a latency of below 20 ms in the Digital Backbone’s software Engineering a lower latency into your autonomous driving system corresponds to a faster response. This is very important for performance and safety
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