Safe, comfortable and greener driving is at the heart of the development of highly automated vehicles. Thanks to a multitude of systems and sensors, automated and connected technology warns drivers of imminent dangers, helps them avoid highly congested roads and provide traffic-sign information. What’s more, it communicates safety-critical information to other vehicles such as their speed and heading and whether they are braking or accelerating. Cooperative, connected and automated technology is highly valued both in cars and heavy trucks, yet the architecture differs due to the large size of the truck-trailer combination. In light of this, the EU-funded project ROADART successfully unveiled a new wireless communication platform for trucks that considerably increases drivers’ safety and efficiency, while helping to reduce harmful emissions. ROADART worked on several possible paths to make truck-to-truck (T2T) and truck-to-infrastructure (T2I) systems a reality within a few years. Multiple antennae, multiple gains Researchers investigated various antenna array designs that can be easily integrated in the side mirrors of trucks or installed in infrastructure towers. “The antennae implemented in ROADART’s platform are electronically switched parasitic arrays (ESPARs). Their design demonstrates low cost, reduced complexity and compact size, making them excellent candidates for T2T and T2I links,” notes project coordinator Dr Christos Oikonomopoulos. ESPAR antennae allow dynamic adaptation of their radiation pattern to increase the link quality. To further improve the reliability of a message, researchers used the antenna diversity technique coupled with a novel beam pattern selection scheme known as open-loop beamforming. “Another major advantage of ESPAR antennae is their ability to support various digital communication techniques such as pattern diversity,” adds Dr Oikonomopoulos. Successful proof of concept Improving the robustness of wireless communications with respect to data packet loss and latency increases the availability of communication applications. Reliable T2T communications are especially relevant for safety and time-critical cooperative driving applications. ROADART successfully demonstrated a use case involving cooperative adaptive cruise control (CACC) – a cooperative ITS function that allowed two trucks to drive close one behind the other. “Platooning allows for shorter inter-vehicle distances, which reduces fuel consumption and helps avoid 10 % of all accidents on motorways”, notes Dr Oikonomopoulos. Effective communications can also help truck platoons find the best possible route in situations where other communication modes may not be available such as in long-distance tunnels. ROADART’s localisation engine is based on an extended Kalman filter that fuses data from various heterogeneous sources including the GPS, truck sensors, positioning information from cooperative vehicles and openly available map data. During demonstration of the two trucks driving for two kilometres in a tunnel, the accumulated localisation error did not exceed two metres. Platform design The newly developed ROADART platform handles the entire signal processing. It consists of a set of software-defined radio modules and two ESPARs mounted on the outer side of each side mirror, as well as a corresponding communication unit installed inside the truck cabin. The implemented software for the selected diversity techniques and the localisation algorithm are also executed in the communication unit. Overall, use of diversity/multi-antenna techniques extended coverage and increased throughput by 50 %. High throughput combined with low data packet errors reduced latency by 900 % compared to conventional antennae systems. The architecture concepts developed so far by ROADART should cope with changing traffic levels and provide a solid foundation for continued research.
ROADART, electronically switched parasitic arrays (ESPARs), truck-to-truck (T2T), truck-to-infrastructure (T2I), intelligent transport systems technology (ITS), platoon, localisation, software-defined radio, cooperative adaptive cruise control (CACC)