What is active cruise control?

So, you have probably heard of – and most likely used – cruise control when driving. The ability to maintain a set speed without keeping your foot on the throttle or brakes is a great way to relax your legs and let you focus on other things on the road.

Conventional cruise control adjusts the throttle, maintaining the car’s speed on both flat stretches as well as on hills. The throttle is adjusted by fuel being injected into the combustion chambers to produce more torque – speed is set from switches usually located on the steering wheel. While older systems allow the vehicle to creep about the chosen speed, newer systems come fitted with a speed limiter – ensuring that you are kept within a range of your chosen speed.

Mercedes-Benz made this idea popular almost 20 years ago with its radar-based Distronic system. This system lay the foundation for autonomous motoring and became a useful labour-saving device.

But what about the ability to also maintain a set distance from the car in front?

Distronic and other ACC systems added computer processing power to adjust the set speed up – or down – thereby matching the varying pace of the car ahead. This ability to read traffic and observe speeds is done from input via one or more sensors.  

While distronic systems rely on radar, there are other systems including LiDAR – which is essentially a laser system, bouncing a laser off the back of the car in front of you.