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Lane-departure systems

27 March 2018

Automotive safety has evolved incredibly over the last decade. Here we look at a modern system that is becoming increasingly common: lane-keep assist.

The introduction of active cameras to vehicles has changed the nature of on-road safety dramatically. Thanks to these cameras, the driver is no longer solely responsible for checking surroundings. Cameras can now monitor things like lane markings, blind spots and traffic conditions directly in front of a vehicle.

This, in turn, has led to systems that can greatly reduce accidents. It’s now possible, for example, for a vehicle to detect that traffic in front of it has come to a sudden standstill and vigorously apply the brakes. It can also warn you when a vehicle is cruising in your blind spot and prevent you from moving to that lane when there is danger.

Certain vehicles, like those produced by Mercedes-Benz, will send a vibration through the steering wheel to let you know when you are drifting out of your lane.

Lane-departure warning
One of the most popular of these new technologies is the lane-departure warning/lane-keep assist system. A lane-departure warning system (or lane monitoring system) is a simpler set-up that merely warns a driver that he his moving out of his lane, while a lane-keep assist system adds active intervention.

As mentioned earlier, the system relies on cameras, usually mounted behind the windshield, near the rear-view mirror. These cameras continuously monitor lane markings to check that the vehicle is travelling safely in the centre of a lane. If a driver crosses the line on either side of his or her vehicle, a lane-departure warning system will notify the driver that this is happening. A warning will usually appear on the dashboard, often accompanied by a sound. Other manufacturers, meanwhile, rely on a vibration in the seat or steering wheel (called haptic feedback) to inform the driver. If the driver has turned on an indicator, the system will do nothing, since it realises that the vehicle is crossing a line intentionally.

Some systems will not only inform the driver when the vehicle is venturing outside its lane, but it will also indicate when it is drifting dangerously inside its own lane. The Subaru Eye Sight system has this feature, called Lane Sway Warning.

A lane-keep system (Kia’s in this case) monitors the road markings to keep the vehicle in its lane.

Lane-keep assist
As its name suggests, lane-keep assist takes things even further by actively keeping a vehicle in its lane. Once the system detects that the vehicle is drifting out of its lane, a warning is given – as in the case with a lane-departure warning system – but the system also nudges the vehicle gently back into its lane. This is usually done in two ways. The system either brakes the opposite front wheel to send the vehicle back into its lane, or it actually steers the vehicle back into its lane via the steering wheel.

Importantly, a good lane-keep system isn’t overly obtrusive or forceful. The driver should be able to overcome it with relatively ease, and should never feel as if the system is overpowering. Still, some drivers don’t like these systems, despite the obvious benefits, which is why they can almost always be switched off.

A warning often appears on the dash when your vehicle drifts out of its lane.

Lane-centring assist
Thanks to the many semi-autonomous driving systems now finding their way into vehicles, lane-keep assist is now replaced by lane-centring assist. Instead of intervening only when the vehicle starts to drift, lane-centring keeps the vehicle in its lane. For safety reasons, the system wants you to have your hands on the steering wheel, but the vehicle is really what’s positioning you within the lane. It’s a rather odd feeling when you first encounter this sort of system – and it requires a certain leap of faith to fully place your trust in it – but it is nevertheless very impressive.

The future is coming
Systems like lane-centring assist are paving the way for fully-autonomous driving. When combined with adaptive cruise control, a vehicle can drive itself for long stretches on the highway when it has these systems installed. For those who are used to being in control behind the steering wheel, having the vehicle beneath you take charge can be disconcerting, but there’s no denying that systems like this increase safety and reduce accidents.

Text: GG van Rooyen