Autonomous driving in the tracks of Bertha Benz.
In August 1888, Bertha Benz set off on her famous first long-distance automobile journey from Mannheim to Pforzheim. In doing so, the wife of Carl Benz demonstrated the suitability of the Benz Patent Motor Car for everyday use and thus paved the way for the worldwide success of the automobile. Precisely 125 years later, in August 2013, Mercedes-Benz recorded a no less spectacular pioneering achievement following the same route. Developed on the basis of the new Mercedes-Benz S-Class*, the S 500 INTELLIGENT DRIVE research vehicle autonomously covered the approximately 100 kilometres between Mannheim and Pforzheim, while negotiating dense traffic and complex traffic situations.
“This S-Class spells out where we’re headed with ‘Intelligent Drive’ and what tremendous potential there is in currently available technology,” says Dr. Dieter Zetsche, Chairman of the Board of Management at Daimler and Head of Mercedes-Benz Cars. For the Mercedes-Benz S 500 INTELLIGENT DRIVE research vehicle was equipped with production-based sensors for the project. Based on a further development of the sensor technologies already in use in the new S-Class, the developers taught the technology platform to know where it is, what it sees and how to react autonomously. With the aid of its highly automated “Route Pilot”, the vehicle is able to negotiate its own way through traffic.
“With our successful test drives, we have demonstrated that highly automated driving is possible without the luxury of specially closed-off sections of road and relatively straightforward traffic situations,” says Thomas Weber, member of the Board of Management at Daimler with responsibility for Group Research and Head of Mercedes-Benz Cars Development. “In line with the goal of the project, we have gained important insights into the direction in which we need to further develop our current systems in order to enable autonomous driving not just on motorways, but also in other traffic scenarios. Even we ourselves were quite surprised at just how far we have got using our present-day sensor technology. But now we also know how much time and effort is needed to teach the vehicle how to react correctly in a host of traffic situations – because every part of the route was different,” adds Weber.
This experience will now be incorporated into the engineering of future vehicle generations to be equipped with such innovative, further-developed functions. Thomas Weber stresses: “With the new S-Class, we are the first to drive autonomously during traffic jams. We also want to be the first to provide other autonomous functions in series production vehicles. We are expecting to reach this goal within this decade.” Partially automated driving is already available to drivers of new Mercedes-Benz E- and S-Class models: the new DISTRONIC PLUS with Steering Assist and Stop&Go Pilot is capable of steering the vehicle largely autonomously through traffic jams. This system thus forms the core of “Mercedes-Benz Intelligent Drive”, the intelligent networking of all safety and comfort systems on the way to accident-free and, ultimately, autonomous driving. The now successfully conducted autonomous test drives along the Bertha Benz route allowed the Daimler researchers to gather important information on the challenges that remain to be addressed on the way to highly and fully automated driving and what, for example, still needs to be done to enable a car to navigate safely in highly complex situations. Unnoticed by the public, yet authorized by appropriate official exemptions and certificates, testing of the “Route Pilot” on the Bertha Benz route began in early 2012 with a total of three technology platforms based on the Mercedes-Benz E-Class** and S-Class, which are equipped with all available active and passive safety systems.
PRE-SERIES SENSOR TECHNOLOGY
These test vehicles employed only those sensor technologies that are already today used in similar form in Mercedes-Benz standard-production vehicles. This is because those technologies are already affordable and suitable for everyday use, which facilitates a possible transfer to subsequent standard-production models. However, improvements were made to the number and arrangement of the sensors in order to achieve comprehensive coverage of the vehicle’s surroundings in every direction, and to obtain additional information on the area around the vehicle. Examples of specific technical modifications compared with the standard-production version of a Mercedes-Benz S-Class are the enhancement of the base width (distance between the eyes) of the stereo camera to allow more-distant objects to be detected not only by the radar system, but also by the camera, and a new colour camera for the monitoring of traffic lights.
Based on these sensor data and determination of the vehicle’s own position with reference to information from a digital map, an autonomously driving vehicle analyses the available free area for driving and plans its own route. The required algorithms were developed by the Mercedes-Benz research team in collaboration with the Institute for Measuring and Control Technology at the Karlsruhe Institute of Technology (KIT). For the trip along the Bertha Benz route, Mercedes-Benz collaborated with KIT and HERE, a division of Nokia specialized in the production of digital maps and location-specific services, to produce a 3D digital map of the route that was specifically adapted to the requirements of an autonomous vehicle. In addition to the road layout, this map – which must meet special requirements with regard to accuracy – includes information on the number and direction of traffic lanes and traffic signs as well as the positions of traffic lights. Digital maps of this kind are a key prerequisite for autonomous driving.
The autonomously driving S-Class was monitored during the tests by specially trained safety drivers who, whenever the system made an incorrect decision, were able to intervene immediately and take over control of the vehicle. As real traffic is unpredictable – which means that no driving situation is exactly the same as an earlier one – a record was made each time it became necessary for the safety driver to take over control of the vehicle. This information was then evaluated by the development team, thus making it possible to extend the vehicle’s repertoire of manoeuvres. This advances the development of the technology platform, enabling it to cope with more and more traffic situations.
The test drives deliver important information for further development of the technology and the product. For Daimler, the success of the autonomous road tests lies above all in having identified those areas on which the development team needs to concentrate in the future. “We now know where we can make further improvements and refinements to the vehicle’s repertoire of programmed manoeuvres, for example how to autonomously negotiate a roundabout,” reports Ralf Guido Herrtwich, head of driver assistance and suspension systems at Daimler Group Research and Advance Development, a role in which he initiated the autonomous driving project. A further challenge is to correctly locate the vehicle on the road, in order to determine, for example, precisely where a vehicle should stop at a junction while at the same time having a view of cross-traffic.
A particular challenge for autonomous vehicles is the way in which they communicate and interact with other road users. Coming to an agreement with an oncoming vehicle on who should proceed first around an obstruction is something that requires a very great deal of situational analysis. “Where a human driver might boldly move forward into a gap, our autonomous vehicle tends to adopt a more cautious approach,” says Herrtwich. “This sometimes results in comical situations, such as when, having stopped at a zebra crossing, the vehicle gets waved through by the pedestrian – yet our car stoically continues to wait, because we failed to anticipate such politeness when we programmed the system.”
*(Fuel consumption, combined cycle: 10,3-5,5 l/100 km, CO2 emissions, combined: 242-146 g/km, energy efficiency class: F-A) **(Fuel consumption, combined cycle: 10,3-4,1 l/ 100 km, CO2 emissions, combined: 242-107 g/km, energy efficiency class: F-A+) The figures are provided in accordance with the German PKW-EnVKV and apply only to the German market. They do not concern an individual vehicle and are not part of the offer; they are provided solely for the purposes of comparison between different types of vehicles.
HISTORIC ROUTE ON THE WAY INTO THE FUTURE
In August 1888, Bertha Benz started off on the first long-distance automotive drive in history in the Patent Motor Car of her husband Carl Benz, thus paving the way for the worldwide success of the automobile. The route, which ran southward from Mannheim to Pforzheim for around 100 km, was used by Mercedes-Benz developers as the real test track for another pioneering achievement in mobility exactly 125 years later: proof of the suitability of autonomous drive systems for everyday use in the highly complex environment of overland and urban traffic.
The autonomous research vehicle records the entire sensory data collected by the vehicle, which flows in at a rate of 300 gigabytes per hour from the images of the stereo camera alone.