Helping drivers stay focused on the road
5th January, 2005
SAAB IS HELPING drivers stay focused on the road by developing a safety system that monitors eye and head movements, issuing a warning signal if the attention of the driver strays long enough to risk causing an accident.
“The other car appeared from nowhere! I just didn't see it.” Drivers often make such comments after an accident or a near-miss. In truth, it is an admission that for a brief moment the driver was not concentrating fully on what was happening outside the car.
It’s an experience behind the wheel that most of us would admit to having at one time or another. It is understandable because drivers can sometimes have their attention momentarily distracted for a whole number of reasons. It could be a case of searching around for that favorite CD; looking at an advertising billboard a little too long; 'rubber necking' while passing the scene of an accident, or trying to find a street sign along an unfamiliar road.
Taking into account vehicle speeds – at 100 km/h, a car travels 26.6 metres in just one second – the consequences of such lapses, no matter how innocent or brief, can be extremely serious.
Saab is now pioneering a unique driver attention warning system that is designed to overcome the hazard of driver distraction. It is based on what the driver actually does behind the wheel, instead of what he or she should be doing.
Two miniature cameras with infra-red lenses are installed in the car to monitor the driver's eye and head movement. As soon as the driver's gaze moves away from what Saab calls the 'primary attention zone', the central part of the windscreen in front of the driver, a timer starts counting. If the driver's eyes and head do not return to the straight ahead position within about two seconds, a buzzer will sound. And if there is still no response, a brake pulse will be delivered through the car's ESP system.
The measurement and processing of the infra-red image includes the relationship between eye gaze direction and head movement. It is sufficiently accurate to detect when the driver retains some peripheral vision of the road ahead – such as while looking in the rear-view mirror or turning a corner – and will consequently allow a slightly longer time to elapse before activating the warning buzzer.
The software is speed-sensitive. In this way, the system can distinguish between a busy, city driving environment and more open highway driving at faster speeds.
In low-speed, as in city driving, there is a wide driver attention zone, allowing for plenty of head movement but a shorter time 'buffer', before the warning buzzer is triggered. High-speed mode will revert to a narrower attention zone and a longer time buffer due to reduced traffic densities.
To further distinguish between prevailing traffic conditions, the warning system could also be linked to the satellite navigation system. The buffer time zone would then, for example, go to a short zero tolerance setting when the car is near a school or a hospital.
Infra-red imaging has been chosen as it gives clear reproduction independent of light conditions. For maximum accuracy, two cameras are currently fitted to a 9-3 Sport Sedan test and development car, one at the base of the driver's A-pillar and the other in the centre of the front fascia. In commercial production, these very small, mini lens cameras would be completely hidden behind the main fascia paneling.
“There's no doubt increasing traffic densities and the growth of in-car 'infotainment' systems are putting an increasing workload on the driver,” explains Arne Nåbo, Saab's chief of ergonomics who is leading the development project. “We at Saab, in common with other car manufacturers, have so far focused on managing information inputs for the driver in the safest possible way. Now we think it is time to take a rather less passive approach.
“The fact is, in everyday driving, we know people actually do take their eyes off the road quite a lot and we are now developing a means of helping drivers to help themselves.
“This system will help prevent a dangerous habit we call 'cognitive tunneling”, adds Nåbo. “For example, the driver may have a map book open on the passenger seat and keep glancing between the map and the road. The driver can eventually get too absorbed in trying to overcome the challenge of plotting directions on the map and simply gets distracted for too long.
Apart from its primary driving safety function, there are further potential applications for this technology, such as:
Saab is constantly seeking to minimise the potential for driver distraction. Its ComSense safety strategy includes the use of a 'dynamic workload manager', introduced with the first generation Saab 9-5 sedan in 1997. This enables the brief suppression of dashboard warning messages, or the interception of an incoming call on the integrated telephone, when a moment of high driver workload is detected by the operation of the indicators or heavy braking.
Under the ComSense umbrella, Saab also prefers green, instead of red, for instrument illumination at night because research shows this to be a more restful and less distracting colour for the driver. In the same way, a 'Night Panel' feature on Saab cars allows the driver to minimise distraction by switching off, or dimming, all the main instrumentation illumination at night (expect for the speedometer).
A driver attention warning system could be the next technical step forward for ComSense. It is seen as a natural extension of Saab's traditional 'real-life' approach to safety provision. Just as crash impact protection is optimised through studying the results of real accidents on real roads, this driver warning system is designed to deal with actual, 'real-life' behavior behind the wheel, in everyday conditions.
“The hardware is reliable and relatively inexpensive. We are now concentrating on fine tuning the timing of the buzzer and the nature of the final warning alarm. A brake pulse, which does not engage the rear stop lights, is currently the preferred option,” says Nabo.
Programming and data processing has been carried out in liaison with optical technology specialists SmartEye AB of Gothenburg. Although no decision has been made about taking the system into production, testing and research work at Saab has already demonstrated its feasibility and effectiveness. One day, this technology may be as commonplace in our cars as cruise control.