Issue 39 Unmanned Systems Technology August/September 2021 Maritime Robotics Mariner l Simulation tools focus l MRS MR-10 and MR-20 l UAVs insight l HFE International GenPod l Exotec Skypod l Autopilots focus l Aquaai Mazu

85 Autopilots | Focus own hardware to serve as high-end autonomy engines and as open platforms for professional unmanned vehicle operators to build upon. Here, high-quality CPUs and microcontrollers typically feature within highly modular designs that come with standardised interfaces for different data links, cloud solutions, video encoders and enterprise applications. That will enable future compatibility with managing unmanned traffic, IoT and other technological systems that might evolve. An open-source software provider also typically undertakes some level of review of new solutions before publishing them for widespread use. That involves a measure of quality assurance testing, simulations in a virtual environment, and potentially going as far as performing manual or automated flight trials to put the new software through its paces. Given the advantages of the open-source model, it is unsurprising that many high- end proprietary autopilot developers offer sets of developer tools to their customers, to enable more hands-on interfacing with their hardware and software. The idea here is to make it far easier for end-users to swap payloads or other mission-relevant subsystems as needed. And for unmanned aircraft manufacturers who want to combine technological agility with assured robustness, some new autopilot products are now emerging that are effectively hybrids of open-source products and certified components. These combine parts tested to well- established standards for avionics, with DO-160G for example laying out clear testing profiles and targets for EMI and environmental tolerances. Also, DO-254 is key for designing certifiable autopilots in terms of hardware and structure, while DO-178 provides guidance on how safety-critical software should perform. At the same time, these autopilots can rapidly incorporate new software solutions from across the open-source world into a platform that is certified and effectively cleared for flight in shared airspace. Hardware design Once the layers, functions, interfaces and other details of an autopilot’s software architecture are clearly defined, a robust hardware design is critical to ensuring reliable management of the unmanned vehicle’s various subsystems and an effective interface for the operator’s GCS and application. How an autopilot design is fleshed out varies according to factors including the type of vehicle, mission application, operating environment and flight durations. Traditionally, autopilots were designed with individual use-cases in mind, but these days modularity and flexibility are taking hold in hardware, just as they have in software. To achieve these qualities, high-end autopilots are increasingly engineered with physically separate layers. This is often manifested as a carrier interface board that contains the I/Os and APIs for communicating with subsystems and GCSs; a smaller, core autopilot module is mounted on the carrier board. The core module tends to encompass the main processor, RAM, flash memory, inertial sensors and other key components such as magnetometers or pressure transducers, if the vehicle architecture calls for them. The carrier might then host multiple autopilot modules for redundancy – although more and more UAV autopilots nowadays already come pre-integrated with triple- redundant IMUs – or serve as a platform for updated autopilots, incorporating newer and more advanced processors or IMUs for example. The acceleration of technological advances in microelectronics and MEMS technology over the past 5 to 10 years means that a UAV hardware engineer can package a huge amount of computer memory along with highly sensitive, Unmanned Systems Technology | August/September 2021 More and more autopilots are designed as separate carrier and core systems, enabling considerable modularity for use in different hardware architectures as technology advances (Courtesy of 3DXR)