RAC Cars News


What is Adaptive Cruise Control?

By raccars Published


Do you remember when standard cruise control seemed so sophisticated and modern?

Well things have moved on somewhat since then. Standard cruise control is still a more relaxing way to drive, taking some of the strain by keeping you at a constant speed, but modern or adaptive cruise control is far smarter than that.

Autonomous driving technology

More and more autonomous driving technology is being fitted to new cars and we all know that the day is coming when the driver will be pretty much redundant. The goal is to keep us all safer by preventing human errors which are the most common cause of collisions. Among the autonomous driving features most commonly found on modern cars is autonomous emergency braking. Sensors anticipate a collision and automatically brake the car if the driver doesn't do so in time. The system is usually confined to lower speeds.

Adaptive cruise control is similar in that it sees the car take control to avoid a crash. Adaptive cruise control or ACC has been available on premium brand models for some years but is now becoming a popular or even standard feature on lower priced models.

Standard cruise control

Basic cruise control maintains a vehicle at a set speed without the need for any acceleration from the driver. In fact an early form of cruise control was in use as far back as 1900 and was mechanically operated. Modern cruise control systems are electronic but work on much the same principle.

Cruise control makes for a more relaxing and comfortable drive and almost invariably returns better fuel economy because it avoids the constant small accelerations and decelerations associated with human input. All of us make small accelerator pedal movements without even realising we're doing so.

In most systems you can deactivate the cruise control system with only light pressure on the brake pedal and use a 'resume' button to return the car to the previous set speed. You usually have the option of making incremental adjustments up and down using buttons or a column stalk. On motorways, where you spend longer periods of time at a steady speed, this allows the driver to relax a little. In town or on busy roads it's less helpful, because the driver has to intervene in order to adjust the speed.

Cruise control is also a useful way of ensuring that you don't accidentally exceed the speed limit.

Adaptive cruise control

While cruise control is very useful on long, empty roads, its use tends to be routinely interrupted by traffic congestion, so that drivers have to keep dis-engaging and re-engaging the system as they adjust their speed to negotiate traffic.

With ACC that's not necessary because the car is fitted with sensors which analyse the road ahead and automatically brake or accelerate to maintain a set distance between you and the car in front of you. You switch it on and off in the same fashion as standard cruise control with the added option of increasing or decreasing the space between you and the car ahead of you.

Early ACC

Mercedes-Benz was the first manufacturer to offer adaptive cruise control on the S-Class in 1999. Since then ACC has joined a number of other autonomous driving technologies including autonomous emergency braking and lane keeping assist to assist the driver with a number of basic functions, with the ultimate aim of preventing collisions.

GPS technology is invaluable in enabling these technologies to become ever more accurate, sensitive and reliable, so you can expect to see co-operative cruise control allowing cars to communicate via radio signals to maintain safe distances automatically.

While the theory behind cruise control hasn't changed since it was first invented, the technology that makes it happen is increasingly complex and really leads in one obvious direction - towards full automation or driverless cars.

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