If some car manufacturers are to be believed, the fully self-driving car will be coming to a showroom near you in the next few years. In the meantime, elements of autonomous car technology are filtering out into the cars you can by right now. Autonomous emergency braking is commonplace on new car spec sheets and so is adaptive cruise control. But what is adaptive, or radar, cruise control and is it an option box that new car buyers should be ticking? We explain more below.
Cruise control systems that automatically regulate vehicle speed have been around for donkeys’ years. The earliest version on a motorcar used mechanical governor technology similar to that which prevented steam engines from over-speeding in the 18th century.
Later cruise control systems would count speedometer cable or driveshaft revolutions to calculate road speed (among various other methods), and then use automatic electronic throttle operation to match the speed selected by the driver. Nowadays, everything is controlled by software in the little black ECU boxes under the bonnet.
As well as reducing fatigue by allowing drivers to stretch their legs when spending hours at the wheel, cruise control can slightly improve economy by reducing the amount of throttle input a driver might make when inadvertently slowing down and speeding up.
How to use cruise control
Typically cruise control is engaged with a button once the driver has reached the desired speed, and disengaged instantaneously and automatically when the brake pedal (or clutch on manual cars) is pressed. Using the ‘coast’ button allows speed to reduce more gently without braking, while pressing the ‘resume’ button will allow the car to accelerate back to its set speed automatically.
Cruise control was first popularised in the US where drivers were often faced with vast distances on wide-open, often straight roads. In Europe, where its potential is more limited by traffic congestion and corners, cruise control arrived first as a status symbol on luxury cars. However cruise control has become more common since modern electronics made fitting basic systems much cheaper, and it’s now standard equipment on many ordinary family cars.
How to use Adaptive Cruise Control
Anyone who’s driven with standard cruise control on British motorways will have quickly recognised the fundamental problem. It may be great at 3am when there are no other cars about, but mostly you have to speed up and slow down so often in traffic it makes cruise control redundant. That’s where Autonomous or Adaptive Cruise Control (ACC) comes in.
Using radar or laser technology ACC scans the road ahead, detecting the changing speed of vehicles in front, and adjusting the speed of your own car with both accelerator and brake to automatically maintain a constant distance from the car in front. You use it just like ordinary cruise control, but there’s an extra control that allows you to set (then increase or decrease, within set parameters) the distance to the car in front.
The first radar controlled ACC was launched in the Mercedes S-Class in 1999, but since then the arrival of more advanced technology like Autonomous Emergency Braking and Lane Assist means ACC is part of an ever-expanding suite of advanced driving technologies. The very latest systems use GPS location to further improve intelligence, while future developments in Cooperative Adaptive Cruise Control will see cars communicating with each other by radio signal – vastly improving safety.
While the control systems running ACC systems are becoming increasingly complex, in operation they are all remarkably simple. And as further advances are made, they all point towards the inevitable future of fully autonomous or driverless cars.
What do you think of adaptive cruise control? Do you use the system on your car? Let us know in the comments...