Easy Tech: Conditionally automated driving with the DRIVE PILOT

Many people are already used to partially automated driving: At this level of driving automation, the driver always has full control over the vehicle, but can be supported by driver assistance systems. An example for such a system is the Active Distance Assist DISTRONIC, which can regulate the distance to vehicles ahead and automatically brake or accelerate the car within a speed range of 0 to 210 km/h. “Conditional driving automation goes one step further because the DRIVE PILOT system actually takes over driving tasks under certain conditions. However, as a driver, I always have to be ready to take control of the vehicle. Especially when the DRIVE PILOT requests me to retake control of the driving task,” says development engineer Maria Bergmann as she leisurely takes her hands off the steering wheel at a speed of 50 km/h. She then no longer pays attention to the road, but instead concentrates on our interview. She could also communicate with colleagues online via In-Car Office, answer e-mails, surf the Internet, or enjoy a relaxing seat massage.

We are driving a test vehicle on a test track in Immendingen – a normal working day for Maria Bergmann. She’s a function developer and part of the team that is set to achieve a milestone in the development of Mercedes-Benz vehicles. Conditionally automated driving with the DRIVE PILOT is scheduled to go into series production before the end of the year and will be offered to customers as optional equipment for the new S-Class. The DRIVE PILOT will also be available as an option for the EQS, the all-electric luxury sedan from Mercedes-EQ.

The six levels on the way to the self-driving vehicle

Which driving tasks are performed by the driver? And which ones by the vehicle? According to experts, there are six levels of automated driving on the way to the self-driving vehicle.

Level 0 refers to driving with the help of driver assistance systems. This means that the driver assistance system selectively supports the driver when necessary. Such as the Active Brake Assist, which can recognize collision risks and initiate autonomous emergency braking in order to prevent rear-end collisions and accidents with pedestrians.

The situation is different at Level 1: The driver cannot only be supported by driving assistance systems selectively, but continuously. With the Active Distance Assist DISTRONIC, for example, which can regulate the speed to vehicles ahead, adjust the car’s speed to the speed limit, and slow the vehicle down as it approaches curves, intersections, and traffic circles.

Level 2 refers to partially automated driving. Meaning that the driver can be supported continuously for both longitudinal and lateral guidance of the vehicle. An example for partially automated driving is the combination of the Active Distance Assist DISTRONIC (longitudinal guidance) in combination with the Active Steering Assist (lateral guidance), which helps the driver to follow the driving lane at speeds of up to 210 km/h. However, the driver remains in full control of the vehicle at Levels 1 and 2.

This is where conditionally automated driving at Level 3 goes a big step further: Under certain conditions, the vehicle can take over dynamic driving tasks. In Germany, laws currently permit this on suitable motorway sections and where traffic density is high. The top speed is restricted to 60 km/h. When the DRIVE PILOT in the S-Class is activated, the driver can focus on other activities such as work or reading the news on the media display. However, the driver must always be able to take over control of the vehicle. Meaning that the driver, for example, is not allowed to sleep, continuously face backwards, or leave the driver’s seat.

Level 4 refers to highly automated driving and means that the vehicle, under certain conditions, can handle traffic situations on its own. One example is Automated Valet Parking: With the INTELLIGENT PARK PILOT, the S-Class is prepared for driverless highly automated parking. As soon as legal conditions allow, the vehicle will be able to drive to a reserved parking space autonomously – via smartphone command (in a parking space equipped with the necessary infrastructure for automated valet parking and the respective Mercedes me connect Service booked by the customer).

Fully automated driving is reached at Level 5, the highest degree of automation. At this level, the vehicle is able to perform any driving tasks on its own and doesn’t need a human driver, regardless of the type of road, the speed range, or other driving conditions.

Ready for Level 3: Conditionally automated driving with the DRIVE PILOT

When a turquoise light appears on the steering wheel rim’s two DRIVE PILOT buttons, it means that we have activated the conditional automated driving mode. “Initially unfamiliar, you quickly get used to it”, says Maria Bergmann. This was especially easy for the young engineer, as she is familiar with the high safety standards that are a matter of course for the team responsible for Function and Software Driver Assistance. The overall system consists of many individual components. “I work on the driving status. My module uses the data supplied by a variety of sensors to calculate how the vehicle is moving on the road,” she says. This means it can tell whether the car is accelerating or braking and how fast it’s moving. This status must be precisely determined and reliably communicated to the system as a basis for its driving decisions.

“I like to think logically, analyze requirements, come up with ideas, and search for solutions like a detective,” says Maria Bergmann. For the past two years, she has been working on her driving status code for the DRIVE PILOT in the S-Class. “As a developer, I first assess whether the requirements of the overall project are even technically feasible. This essentially depends on the sensors and the data quality. I then write the code and evaluate the program in virtual tests. If the results of the computer simulation are promising, we check to see whether and how it works with the standard components in the vehicle. The code is then sent back to the lab so that it can be improved. Once that is done, it goes back into the testing loop,” she says about the development cycle aiming for a steady improvement and refinement of the algorithm.

During this process, she always has her sights on the milestones that need to be reached for the creation of a customer-compatible overall system. Stress tests simulate tough situations and the S-Class equipped with the DRIVE PILOT has already driven thousands of kilometers on the test track and in real-life road traffic. “Sometimes, the tests require us to travel together as a group for weeks. This teamwork creates personal bonds and the success unites,” says Maria Bergmann. Our interview during the test drive is suddenly interrupted by a red light on the dashboard. Although the red light initially startles the inexperienced passenger, Maria Bergmann remains calm. “I’m requested to retake control of the vehicle because the traffic congestion begins to flow freely now. I have ten seconds to do this. If I don’t, the vehicle will initiate a controlled emergency stop.”

The S-Class is capable of reliable conditionally automated driving in traffic jams or when traffic density is high. The DRIVE PILOT controls the speed, the distance to the vehicle ahead, and confidently steers the car within its lane. As it does so, it can also recognize unexpected traffic situations and handle them on its own by means of braking or evasive action within the car’s lane. This is the case, for example, when other vehicles move into or out of the lane, an obstacle has to be circumvented, or emergency braking is necessary because of another vehicle.

“However, the DRIVE PILOT is designed to recognize its limits of conditionally automated driving,” says Maria Bergmann about the system’s strict safety concept. This is the case, for example, when traffic is once again traveling faster than 60 km/h, a traffic situation is too complex, or the lane markings are unclear. In such situations, the red light notifies the driver in time to intervene and take control of the vehicle again.

The technical requirements

When the DRIVE PILOT is activated, the system continuously evaluates the route, traffic signs, and occurring traffic incidents. As a layperson it’s hard to imagine how sophisticated the hardware and software of the S-Class is in order to be ready for Level 3. Even the “normal” latest-generation Driving Assistance Package has the following:

• A stereo multi-purpose camera behind the windshield.

• A long-range radar in the radiator grille.

• Four multi-mode radars (one each on the right-hand and left-hand sides at the front and rear bumpers).

The optional parking package additionally includes:

• A 360°-Camera consisting of four cameras in the right-hand and left-hand exterior mirrors as well as in the radiator grille and at the trunk.

• Twelve ultrasonic sensors (six each at the front and rear bumpers).

For the DRIVE PILOT, many additional components are needed besides the sensors of the Driving Assistance Package. The long-range radar in the radiator grille is combined with a LiDAR (light detection and ranging) system. Whereas radar uses radio waves, LiDAR employs pulses of infrared light in order to optically determine an object’s speed and distance and to create a highly precise map of the vehicle’s surroundings. This combines the strengths of both technologies: LiDAR sensors operate with higher precision, while radar is advantageous in bad weather, for example.

The rear window is equipped with a rear multi-purpose camera that scans the area behind the vehicle. In combination with additional microphones, this device can, among other things, detect the flashing lights and special signals of emergency vehicles. The cameras in the driver’s display and MBUX Interior Assist are always directed at the driver so that they can determine if he or she falls asleep, turns around for too long, leaves the driver’s seat, or is unable to retake control of driving for other reasons.

To supplement the sensor data, a high-precision HD map supplies online information about road geometry, route properties, traffic signs, and unusual traffic conditions such as construction sites via a backend connection. Differential GPS (DGPS) enables the vehicle’s position to be precisely determined to within one centimeter. The demanding software functions are implemented by a powerful central control unit. All of the algorithms are calculated twice as part of the sophisticated safety architecture.

Redundant systems ensure safety and comfort

The buttons on the steering wheel once again light up turquoise and our drive at Level 3 continues on the test track. Safety and comfort are the top development priorities. “That’s why we have developed a clear system of communication between the driver and the vehicle. That prevents mistakes. Moreover, our system is cooperative, which means that we don’t want to patronize, but instead involve the driver to make decisions,” explains Maria Bergmann. Confidence is ensured by the fact that the safety-related steering and braking systems have a redundant arrangement, as does the on-board electrical system. As a result, the car remains maneuverable even if one of these systems breaks down. This ensures that the vehicle can safely transfer the driving task back to the driver. As is the case with Level 2 safety and driver assistance systems, conditionally automated driving has clear advantages: The DRIVE PILOT makes driving the S-Class even more relaxing, whether you are stuck in a traffic jam or in slow-moving stop-and-go traffic.

There’s no doubt that you can quickly get used to driving an S-Class. We drive one last lap that gives us time to conclude with the future prospects of automated driving. Maria Bergmann is convinced that automated driving is still at the beginning of its far-reaching development. Initially, the DRIVE PILOT will only be available in Germany, because the country created the legal basis for Level 3 systems in 2017. It will gradually be introduced to other European countries, the United States, and China as soon as the appropriate legal framework has been established there. “We certainly won’t run out of work,” says Maria Bergmann. “The future of driving is almost within our reach. It’s a cool job.” As we say goodbye, we have a great idea: We will meet again shortly before our retirement (i.e. about 30 years from now). At the test track, in an S-Class. Ready for the next but one level.