Unmanned Systems Technology 001 | UAV Factory Penguin C | Real-time operating systems | Hirth S1218 two-stroke twin | Base stations | ASV C-Enduro | Composites | Datacomms

conditions. The 5.6 GHz wireless links will operate over a range of 300 m but only with other vehicles using the GM technology, although GM is part of the standardisation groups in the US. Publish Subscribe There are different datacomms strategies for other unmanned systems such as UAVs. These are using the Publish Subscribe architecture that allows subsystems to be put together and communicate securely and reliably without having to know whether they are nearby or part of a wider network. The architecture has been defined by the Object Management Group as the Data Distribution Service (DDS), and it is the only open standard for messaging that supports the unique needs of both enterprise and real-time systems across a system’s lifecycle, from initial development and integration through ongoing maintenance and upgrades. DDS is based on the idea of loosely coupled, modular and open architecture systems. It sits on top of the operating system and was designed from the start to support any programming language – as well as C and C++, it also supports Java, C#, Ada, JMS, WSDL/SOAP and REST/HTTP interfaces. The DDS Real-Time Publish Subscribe (RTPS) protocol acts as middleware to provide interoperability across implementations, platforms and programming languages regardless of whether they are connected by wires or radio. It provides high-performance real- time messaging for distributed control systems and sensor data distribution, even over wireless links that can be unreliable, intermittent and with high latency and low bandwidth. It does so by defining a set of network scheduling policies such as the end-to-end network latency budgets, timeliness policies such as time- based filters to control data delivery rate, and temporal policies to determine the refresh rate for periodic data such as the deadlines for data samples to arrive. All of these are then used to define the connections throughout the system. This is independent of the processing hardware, operating system and link technology, so it can be used across all the different subsystems. For example, Airbus Defence and Space (formerly Cassidian) is using DDS for its next-generation ground control station for unmanned air systems that will be deployed in hostile conditions or overflying populated areas, while the Atlantida consortium of 34 organisations, which is designing an air traffic management system for Europe, is also using DDS, both in the ground station and to connect to unmanned vehicles. The DDS middleware is used to 71 DDS sits on top of the operating system and is designed to support any programming language The DDS architecture can be used in enterprise and vehicle-to-infrastructure designs as well as real-time vehicle comms systems Unmanned Systems Technology | November 2014