Waking up dozy drivers

Engineers at Saab have developed a new system they hope will help prevent drivers falling asleep at the wheel.

Saab’s Driver Attention Warning System is a development project designed to counter two of the most common causes of road accidents: driver drowsiness and inattention at the wheel. It alerts the driver by using a combination of text and voice messages, or vibrations in the seat cushion, as soon as the risk of drowsiness or inattention is detected.

Unlike other similar systems, the Driver Attention Warning System does not rely on measuring an erratic change in the steered direction of the vehicle. Instead, it uses two miniature infra-red cameras, one installed at the base of the driver’s A-pillar and the other in the centre of the main fascia, which are focused on the driver’s eyes. The image from the cameras is analysed by software that deploys a series of alerts when the pattern of eye-lid movement indicates the onset of drowsiness, or when the driver is not looking at the road ahead.

To do so, the system measures the rate at which the driver is blinking his or her eyes. When the cameras detect a pattern of long duration eye-lid closures, indicating the potential onset of drowsiness, a series of three warnings is initiated.

In the first instance, a chime sounds and a text warning message 'Tired?' is displayed in the main instrument panel. If the driver’s eye-lid movement does not immediately revert to a normal ‘wide awake’ pattern, a speech message 'You are tired' is then delivered through the car’s audio system. If there is still no response, a stronger warning tone and the message, 'You are dangerously tired – stop as soon as it is safe to do so!' will come over the audio. This can only be cancelled when the driver presses a reset button in the fascia. The system is then immediately reactivated.

The cameras are also able to monitor the driver’s eye-ball and head movement. As soon as the driver's gaze moves away from what is defined as the 'primary attention zone' – the central part of the windscreen in front of the driver – a timer starts counting down.

If the driver's eyes and head do not return to the ‘straight ahead’ position within about two seconds, the driver’s seat cushion will vibrate. This will stop once the position of the driver’s eyes and head are consistent with the vehicle’s direction of travel.

The processing of the infra-red image can also detect when the driver retains some peripheral vision of the road ahead – such as while looking in the rear-view mirror, the door mirror or turning a corner – and will consequently allow a slightly longer time to elapse before activating the seat vibration.

The system, which has been installed in a Saab 9-3 Sport Wagon, is the work of the Human Vehicle Integration team at GME Engineering in Trollhättan, Sweden. It is part of a development programme, Intelligent Vehicle Safety Systems (IVSS), supported by the Swedish government and involving the Swedish National Road and Transport Research Institute (VTI).

The SportWagon development car will now participate in an eight-month field trial programme supervised by the Road and Transport Research Institute in Sweden. The car will be fitted with a wireless GPRS 3G modem that will download data every minute to a web server at Linköping University, where the performance of the system will be analysed.

The trial is part of a development and validation process that could see the system become available in future Saab cars.