Making driving easier. How cruise control works

Cruise control may seem like a simple function that helps drivers maintain a constant speed. But modern versions can do a lot more. See how cruise control works.

17. 10. 2024 Škoda World

Various solutions for maintaining constant speed are just slightly younger than cars themselves – they first appeared at the start of the 20th century! The kind of modern cruise control we know today have their roots in the 1940s, but they only became widespread in the past decades, when growing emphasis was placed on driver assistance systems. Cruise control systems have recently seen rapid development.

From conventional cruise control, where the car just maintains the set speed, we’ve quickly moved on to adaptive cruise control (ACC), which can use radar or cameras to maintain a distance from the vehicle in front. And from there to the “smarter” predictive adaptive cruise control and other solutions on the horizon.

The first Škoda to come with a cruise control option was the first-generation Octavia.

In Škoda cars, cruise control first appeared in the first-generation Octavia, model year 1999. This optional feature came at a cost of CZK 12,000. Adaptive cruise control, a considerably more complex and expensive device, arrived in 2013, again in the Octavia, this time in its third generation. And the 2019 facelifted Superb was the first car to get predictive adaptive cruise control.

There’s cruise control, and there’s cruise control

As far as cruise control technology is concerned, experts distinguish between the classic and various forms of adaptive cruise control. “Classic cruise control is part of the engine control unit and has a simple function, where the unit controls the engine and tries to keep the car at a constant speed,” explains Ondřej Sychrovský, who works on cruise control development at Škoda. “This classic cruise control system is not linked to the brakes, so if it has to maintain speed downhill, it can only do it through engine braking,” he adds.

Adaptive cruise control maintains a given distance from the car in front without you having to step on the accelerator or brake.

Adaptive cruise control is smarter. Its function is handled by the front radar control unit, which is an essential component of adaptive cruise control. And this unit is linked to the car’s other systems. “It can slow down with the engine and brakes, accelerate, and in the case of an automatic transmission, of course, it takes care of the gear shifting,” Sychrovský says. With these interventions, it not only tries to maintain a constant set speed, but also a constant distance from the car in front. If the car in front is going slower than the set speed, cruise control automatically slows down. When the car in front of you speeds up, so does your car.

Adaptive cruise control uses data from the car’s radar and camera.

Today, it’s common for adaptive cruise control to use not only radar data, but also the car’s camera. “Radar is better at tracking moving objects and calculating distance, while the camera is better for stationary objects and determining angles and assigning objects to lanes,” Ondřej Sychrovský explains, adding that data from both sensors is useful for effective cruise control. It is thanks to this fusion of data that adaptive cruise control systems can now not only handle driving in traffic jams, when the cars frequently come to a standstill, but can also react to stationary vehicles.

Smarter and smarter

It is the camera, together with other data sources, that makes it possible for cruise control to perform other functions. Predictive adaptive cruise control needs image data from the camera, but also map data. It can react to the current speed limits, it knows in advance where a built-up area starts, and where a curve is. The control logic then calculates when it needs to start reducing speed to ensure the car safely negotiates the bend or enters the built-up area at the permitted speed.

Predictive adaptive cruise control cooperates with the navigation system and the camera that reads traffic signs.

Another possible functional extension of cruise control is cooperative adaptive cruise control. This has all the functionality of predictive ACC, but also receives data from the vehicle-to-vehicle and vehicle-to-infrastructure communication systems. As a result, the cruise control can receive a warning of a traffic jam ahead and start slowing down before the vehicle’s sensors see the stationary traffic. It can also handle two vehicles driving comfortably in tandem, if the cars can communicate. There are only a few cars that can do this at the moment – the systems are still being developed and we will see them in Škodas in the future.

This is a testament to how quickly things are now changing in what was previously a relatively stable cruise control landscape. “There is no extra legislation for cruise control, for example, but Euro NCAP is already testing it in detail and assessing how it reacts to specific situations,” Sychrovský points out. This is why carmakers are keen to continue to improve cruise control. “We want to make it more reliable, more robust, easier to use and safer,” he says. Škoda uses the solution that’s part of the Volkswagen Group’s platform, but the Czech carmaker has to deal with both the installation of all the necessary components and rigorous testing. And also the cruise control management system.

Cruise control adjuster in the Škoda Scala

According to Sychrovský, the cruise control future holds both improvements and more reliable functions (for example, the ability to react to red lights or stop and give way signs is in the pipeline). Since predictive adaptive cruise control can already take care of speed on its own and can handle some traffic situations where the car has to slow down or accelerate, less driver intervention is required and there is therefore no need for complex controls,” Sychrovský says, offering a glimpse into the future, where there will be greater use of connectivity and communication between vehicles and autonomous driving in general.

Stop and Go

Most Škodas (Octavia, Karoq and all other higher models, including electric ones) now have adaptive cruise control with Stop and Go, which slows down and even stops before an obstacle or the car in front and then automatically starts again. Ondřej Sychrovský explains how it works in cars with manual gearboxes: “You have to change down and eventually put the car in neutral, but the deceleration is regulated automatically. The driver then takes care of starting, and the cruise control remains active all the time.” The predictive design of this cruise control can also react to junctions. “It slows down, but the cruise control doesn’t yet know if there is a vehicle there that the driver should give way to, so the driver has to judge the situation and stop if necessary,” the developer explains. Modern predictive cruise control reacts to roundabouts in the same way – the car will reduce its speed to negotiate the roundabout safely, but the driver has to pay attention to the traffic on the roundabout, of course.

Travel Assist

Together with the lane-keeping system, the adaptive cruise control in Škoda cars is part of the Travel Assist function, which handles not only speed but also cornering. The interplay between the two systems allows Travel Assist to work more smoothly and reliably. And in the future, this will be the basis for higher levels of autonomous driving.