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A Brief Explanation of How Adaptive Cruise Control Really Works

How Adaptive Cruise Control Works
Also known as autonomous or radar cruise control, adaptive cruise control is an added safety and comfort feature in top-end road cars. How it works and the technology used for it is explained in this post.
Malvika Kulur
Last Updated: Sep 25, 2017
How It All Began
Cruise control, speed control, or autocruise is a technology that was invented in 1788 by James Watt and Matthew Boulton initially to control the speed of steam engines.

And Today ...
Adaptive Cruise Control was invented by a group of engineers and was patented in 1991 by General Motors.
Our cars have inbuilt seat belts and air bags, but are they enough to protect us and our car from colliding into the car ahead of us? Not really, because more often than not we tend to get distracted by an ongoing conversation or a nice song. So, we actually fail to notice how close we are getting to the car ahead of us. We end up braking at the nth moment, causing our tires to skid, and we lose control of the car for a few moments. At times like these, we wonder if there is a technology to detect the distance between our car and the one ahead of us, so that our car automatically slows down to avoid a collision. The good news is that there is one such technology, and it's called Adaptive Cruise Control (ACC).

Adaptive Cruise Control is an added feature that is installed when the car is being made, as it is an advanced technology and installation of it is a complex procedure. If you want it to come with the car, you have to pay the company its additional charges. Installation may take a day or two, but this feature is surely worth its price. It is very easy to use and has many advantages to it. There are two types of adaptive cruise control: the automatic braking type and the dynamic set speed type. Given below in this WheelZine article is the explanation for the working of ACC.
Sensing Objects
Smart park assist
A microwave radar unit that does not interfere with police radars and does not trigger radar detectors is attached in the front grill of the vehicle. The radar scans for entities depending on its distance range, which can be from 0.2 meters to about 200 meters. If the radar detects another vehicle, it first gives the driver a notification to slow down, but if there is a chance of collision, then the brakes are automatically set in motion, and the car is brought to a halt. Some ACC systems use cameras, which works only to brake when the car is in low speed. This system works only if the cruise control has been activated, and your top speed and minimum distance between your car and the other car has been entered in.
Manipulating Car Speed
Automatic braking system
The cruise control system adjusts the position of the throttle by using a cable instead of pressing the accelerator pedal. This activates the throttle valve and restricts the amount of air taken in by the engine. When the cruise control is engaged, the cable that is connected to the throttle valve is moved. Simultaneously, another cable that is connected to the gas pedal is pulled. This cable is what actually manipulates the speed of the car. It works only if the adaptive cruise control has been engaged.

Apart from the cable activators, engine vacuums are also used to open and close the throttle. This vacuum has a diaphragm that contains an electronically controlled valve, which works in a similar way like a brake booster by providing power to the vacuum. Once the object in front of the vehicle clears off (this usually happens if the car is maneuvered on a clear lane), the acceleration picks up and tries reaching the maximum speed the car was at, before slowing down. The closer it reaches the maximum speed, the slower is the rate of acceleration.
Is It Worth the Price?
The ACC system is pretty expensive, depending on which one you have opted for. The partial radar system is relatively cheaper than the complete radar with camera setup. This system provides safety and comfort in driving; therefore, it is worth the price, and ACC is available on expensive top-of-the-line cars. So, if you are shelling out around $30,000 on a car, you can put in $1000 and get the adaptive cruise control for your vehicle. At the end of the day, safety and comfort are worth every penny.
Some Key Features
Braking system concept
◆ Vehicle and pedestrian detection
◆ Slowing down to match the speed of the vehicle ahead
◆ Stopping completely to avoid running over the pedestrian
◆ Accelerating, once the car is free from obstacles
◆ Speedy acceleration without giving the driver any discomfort
So, in a nutshell, adaptive cruise control is a system, which helps to slow down a vehicle if it is gaining on the one ahead of it. It was developed to avoid accidents and collisions. Once the vehicle slows down, to adjust to the one ahead of it, the driver can navigate the car on an empty lane. The car will automatically accelerate and return to its original speed, if the road ahead is vacant.