CAPE TOWN, South Africa – I’m parked comfortably in the passenger seat of a Mercedes-Benz S-Class while an engineer from the German firm sits behind the steering wheel, rarely touching the leather-clad item, as we make our way around the Cape Peninsula. This is an autonomous driving test mule that forms part of the Mercedes-Benz Intelligent World Drive to gather road and traffic information on various continents as well as validate the autonomous system. The rare opportunity to be part of an automotive development project afforded me the chance to ask the questions we are all concerned about…
The car
The facelifted S-Class (launched next year locally) is fitted with several additional cameras (for extra visual data capturing) as well as a central display screen to inform the driver exactly which road markings, traffic signs, pedestrians and even wildlife the combination of standard radar and cameras are picking up. In the boot sits all the equipment to record the data that is streamed at 6 Gb every 30 seconds!
According to Mercedes, no additional sensors apart from the standard S-Class units are used by the autonomous driving control system. The only change was to deactivate the time-based warning (around 15 seconds) to inform the driver that their hands needed to be on the steering wheel. This gives the test mule level three autonomous capability compared to the level two that is currently available. The driver is still required to take control on short notice, in contrast to level five autonomous driving, which is essentially a vehicle shuttle not requiring a steering wheel.
How capable is the standard system now?
It’s strange sitting in a vehicle that follows the road ahead by itself in traffic and even obeys the speed limits. The current calibration values favour comfort over speed so do not expect any sporty responses or acceleration.
A limit is set on the steering torque that the system applies around bends, equating to between 0,2 and 0,3 G lateral acceleration. Therefore the vehicle does not round sharp bends by itself and the driver does need to take over regularly as we head through Chapmans’ Peak.
Interestingly, the vehicle can change lanes by itself if the driver activates the indicator and there is no vehicle in the adjacent lane or blind spot.
South African challenges
The engineers found that pedestrians posed a major risk in autonomous driving locally as their behaviour can be erratic and unpredictable. This applies to city driving as well as motorways and is backed up by our road deaths statistics on pedestrians.
Another issue was red lines painted on our roads (no parking restriction), which is difficult for the cameras to distinguish from the black road surface.
Lastly, wildlife is another challenge, as we experience when the driver needs to conduct a manual swerving manoeuvre to avoid hitting a small tortoise (not picked up by the autonomous system) crossing the road. In short, unexpected events are the most challenging to autonomous driving systems.
Swerving to avoid crashes?
The engineer explained that swerving to avoid a crash is technically feasible if there is road space available, but the company found during testing that drivers did not appreciate the car completing the manoeuvre by itself and would resist the system’s actions and make the situation worse. A better solution was found where the system still assists the driver with the swerving manoeuvre, but with the driver triggering the movement initially. Without any steering movement from the driver, the car would just complete an emergency braking event in a straight line.
What if the driver loses consciousness?
Various systems track the condition of the driver. If it determines that the driver may not be ready to intervene if needed, then warnings are sounded with increasing urgency. If the system fails to get the attention of the driver, it will slow down the vehicle to a complete stop, with hazard lights flashing, unlock the doors and contact emergency services automatically. At this stage, the system cannot park the car off the road.
Over-trusting danger?
Autonomous driving is very much under development and there exists a danger that drivers can “over-trust” the system before levels four and five are reached. Currently, all systems may require a quick intervention from the driver in some circumstances and this is not possible while they are attending to emails or drinking coffee…
Will steering wheels disappear?
Not for the time being, explained the engineer. And, according to him, even in level five autonomous driving a retractable steering wheel should be present to allow the driver to take over and experience the thrill of driving at will…
