Semi-autonomous trucks flock together in platoons
The pivotal achievement in this context is an electronic control unit called Highway Pilot Connected. This is an evolved version of Daimler’s Highway Pilot, introduced two years ago. All trucks that are connected in such a platoon are equipped with the Highway Pilot Connected. Providing linear and lateral guidance through active steering mechanisms, this unit enables each vehicle in the platoon to drive independently as autonomously driving trucks. In contrast to its predecessor, the Highway Pilot Connected however enables the vehicles to communicate with each other and with the infrastructure by means of the V2X technology, an implementation of the IEEE 802.11p radio standard. Safety-critical messages can be passed along within 0.1 seconds.
An important feature of the Highway Pilot Connected is the high-resolution digital road map. Thus, the trucks are always aware of the road topology, knowing when a bend or downslope requires the vehicles to slow down.
The driver, monitoring the system, receives information about the status of the platoon and the traffic situation via an 8-inch monitor in the instrument panel. This displays route information as well as the vehicle’s own position within the platoon. Each driver therefore knows the current number of platoon members and his position within the group. In addition the individual drivers are always kept aware of the traffic situation. A camera in the lead vehicle keeps the situation ahead of the truck under surveillance. Its images are transferred to all the vehicles in the convoy by WLAN, and shown on each monitor.
On motorways the semitrailer combinations form a platoon with a distance of only 15 meters apart. This small distance considerably reduces air resistance, thereby lowering fuel consumption and CO2 emissions by around five percent. On level roads this makes fuel consumption figures of around 25 l/100 km possible for a loaded semitrailer combination with a gross weight of 40 t.
This corresponds to a consumption of only 0.66 l/100 km per tonne, or CO2 emissions of 13.3 g per kilometre per tonne – well below that of any passenger car with an internal combustion engine.
Measuring drives on a level test route with three semitrailer combinations at a constant speed of 80 km/h have even shown a fuel economy advantage averaging seven percent. This advantage is at different levels depending on the position in the platoon: In a three-vehicle platoon the lead vehicle has a fuel advantage of two percent, the middle vehicle eleven percent and the rear vehicle nine percent. These differences are due to the differing aerodynamic effects on the individual vehicles.
The Highway Pilot Connect is currently approved for platoon driving within the German state of Baden-Württemberg, for most of the A81 autobahn from Lake Constance to Würzburg greater Stuttgart area. Daimler has received an additional approval for the A52 in the greater Düsseldorf area, where Daimler demonstrated the technology to the press yesterday.
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Semi-autonomous trucks flock together in platoons
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