Active Driver Assistance

Driver aids
I recently received a brochure for the new Audi A4 which has its UK launch on 23rd February, so I guess Audi must think it’s time for me to trade in my A3, which had its 120,000 mile (190,000 km) service last week. Flicking through the brochure, I noticed a number of new technologies being introduced on the new A4 model. The Audi Drive Select features comfort, auto and dynamic drive modes; Audi Side Assist uses radar sensors to detect vehicles in the car’s blind spots; and Audi Lane Assist warns if the car strays from the marked lane. Back in the 1990’s, I attended a lecture given by Jaguar about the PROMETHEUS research programme (IEEE), which was investigating some of these technologies, as well as others such as Head-Up Display systems (which are now being offered on some executive cars).

However, the feature on the A4’s options list which really got my attention was the Adaptive Cruise Control, which the Audi brochure describes as follows:

The optional adaptive cruise control automatically regulates the
distance from traffic ahead. If a car ahead of you slows down, the
system also reduces your speed
. If the vehicle in front brakes
suddenly, the system first warns the driver acoustically before
applying the brakes briefly if necessary.

I find this rather unnerving, as adaptive cruise control crosses the line between a passive driver assistance system and an active driver assistance system, i.e. one that takes control away from the driver.

Now don’t get me wrong, I’ve got nothing against electronic driver aids, especially as on one occasion if it were not for the Anti-Lock Braking System (ABS) and Emergency Brake Assist (EBA) I wouldn’t have stopped in time for a pedestrian who simply walked out in front me without looking where they were going. Most electronic driver aids take their input from the driver but don’t override the driver’s control (except for Electronic Stabilization Programme, but that’s when the driver has already lost control), and they also usually have a fail-safe mode, reverting to the default behaviour without electronic assistance.

However, I am concerned about the potential for adaptive cruise control to make an incorrect decision and increase the risk of an accident rather than reduce it. For example, if I was approaching a car in front of me, and anticipating a gap in the traffic to change lanes to overtake, if the adaptive cruise control applied the brakes to slow my rate of closing on the car in front, it could put me in danger if there was a car approaching in the overtaking lane. I’m not ready to let a car make this judgment for me.

Now that these systems are capable of taking active control of the vehicle, they must surely be regarded as safety-critical systems. Some of these electronic systems may have undergone ISO/IEC-61508 functional safety certification on the basis that ‘the equipment under control poses a threat to its surroundings’, but how can we be sure that this standard will be applied consistently by different automotive manufacturers and suppliers to the development of the software in these systems, given that there are likely to be different perceptions and interpretations of safety in diverse geographical markets? This is something of which the automotive industry is already aware – see "The Application of IEC61508 in the Automotive Industry" (Ekkehard Pofal, PDF).

I hope that this will lead to the development of automotive domain-specific safety levels which could become the basis for international standardization. The DO-178B / ED-12B avionics software standard defines software levels in relation to the consequences of failure creating increased workload on the pilot and the potential for causing death or injury. There are some similarities here between the aerospace and automotive sectors, as I mentioned in a previous blog, and maybe the automotive industry could benefit from the lessons learned in avionics safety certification?

So, let’s hope that Vorsprung durch Technik is heading in the right direction.