Given the worldwide desire to reduce road accident fatalities, it seems likely that the first applications of autonomous driving technologies will appear on heavy commercial vehicles. There are a number of barriers to overcome before that could happen, including legal issues, but since advanced driver-assistance systems can already warn and take avoiding action if the driver does not respond, the technologies needed for autonomous driving are already evolving.
Daimler recently demonstrated how it could develop such technologies in its Mercedes-Benz Future Truck 2025 study, which will make its global debut at the IAA International Commercial Vehicle Show at Hanover in September.
The vehicle is based on a 2014 442-hp (330-kW) Mercedes-Benz Actros 1845, equipped with Mercedes’ automated 12-speed PowerShift3 transmission. The tractor unit will be coupled to the company’s aerodynamically optimized Aerodynamics Trailer. This semi-trailer was shown at the IAA show two years ago, but it has been further developed to incorporate the changes permitted in the European Union to overall truck/trailer length for improved aerodynamics and safety.
To enable autonomous driving, the vehicle is equipped with a range of camera and radar systems, which Mercedes-Benz has named “Highway Pilot.” A stereo camera is fitted behind the windshield, in the position where the Actros would carry a standard camera if the optional Lane Keeping Assist system were fitted.
The camera scans the area ahead of the truck up to 100 m (328 ft) ahead and through an area of 45° to the horizontal and 27° to the vertical. The camera is programmed to identify single and double lanes, pedestrians, moving and stationary objects, all other objects in the scanned area, and the condition of the road surface. Mercedes-Benz claims that the camera recognizes everything that contrasts with the background and can therefore measure clearances precisely. This camera is also programmed to register information on traffic signs. Lane markings are recognized so that the vehicle can be kept in lane when driven autonomously.
In addition to the front-mounted camera, radar sensors installed in the sides of the truck monitor the road surface to either side of the vehicle. These are mounted on each side ahead of the tractor unit rear axle; they have a range of 60 m (197 ft) and scan through an angle of 170°.
The camera and radar sensors are networked to provide a continuous “view” of the area around the truck. A 3-D digital road map is also included in the network, which would be used for the Actros Predictive Powertrain Control system. The data is analyzed by a multi-core processor. Mercedes-Benz claims that the system can recognize the edges of the road by the marker lines and the course of the surface according to roadside features—for instance, guard rails or vegetation. The system is active from rest to a maximum speed of 80 km/h (50 mph).
The system uses many existing technologies such as lane keeping assist, active cruise control, Mercedes Stop and Go Assist to keep a truck running in traffic queues, and autonomous emergency braking systems.
Mercedes-Benz has designed the Highway Pilot to be used with vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) networks. This capability means that every Highway Pilot-equipped vehicle in the near future would continuously transmit information to its surroundings, in the form of a Corporate Awareness Message (CAM), which would include vehicle position, model, dimensions, the direction of travel, speed, acceleration and braking maneuvers, and the radius of any curve negotiated. The frequency of information transmission varies between one message per second at cruising speed to 10 messages per second when there are many changes.
In Europe, the system would transmit via WLAN technology using the standard, Europe-wide G5 frequency of 5.9 gigahertz. Following an agreement among a consortium of vehicle manufacturers, suppliers, public organizations, and research institutions, communications between vehicles would also be standardized. The transmission range of the CAM would be around 500 m (1640 ft) in all weather conditions. This would enable vehicles to react to the movement of other vehicles automatically, such as when a vehicle joins a highway or when it is approaching standing traffic.
The CAM also could be overlaid with secondary messages or Decentralized Environmental Notification (DEN). These messages would warn of unusual events, which could include emergency braking, the activation of hazard warning lights, or the activation of fog lamps. V2I data transmission means that information would also be sent to recipients such as traffic control centers, which could respond by changing speed limits. Data relating to things such as road repairs could also be transmitted.
The system has to be activated by the driver and is designed for use on highways, as the name suggests. Once activated, the driver can turn the driver’s seat through 45° where he or she can carry out other work, or rest. Mercedes has designed a new driver environment to be like an office workstation; here, the driver can use a removable tablet computer. The onboard system will provide information regarding the destination and also what is going on around the truck. The Highway Pilot could, for instance, move the vehicle over autonomously to permit the passage of an emergency vehicle. Otherwise, the system is not programmed for overtaking maneuvers, which would have to be carried out manually.
Since the driver must always be able to resume control of the vehicle, the cab is monitored by two cameras and a sensor in the driver’s seat. The driver is given both an audible and visual warning before the system is turned off and the driver resumes control.
Vehicles would act as relay stations when the next V2I is out of transmission range. If there is no WLAN network, other mobile transmission systems such as UMTS or GPRS could be used. Daimler predicts that average transport speed would increase, simply because of the improved traffic flow, which should also help to reduce fuel consumption.