Cruise control, as applied to automobiles, is a system that will maintain a preselected rate of travel. The driver simply decides how fast they want the car to go, locks in that speed, and the vehicle will continue to travel as such until the system is either disengaged, or the car runs into a tree. Usually, the act of stepping on the brake pedal will disengage the cruise control system. The best ones permit the driver to either slow the car down or speed the car up using secondary controls.
Either a stalk on the steering column, or buttons on the steering wheel typically control the cruise control system. Most designs have buttons for "set", "resume", "accelerate", and "coast" functions. The advantages of cruise control are many; most notably they reduce variations in the speed of the car, enabling the achievement of better fuel economy. They also reduce driver fatigue.
The first known cruise control system applied to a series production car was fitted to the 1958 Imperial. Called “Auto-Pilot”, the system calculated the car’s speed by counting driveshaft rotations. It used a solenoid to vary the throttle position as needed to maintain the driver’s set speed.
In recent years, auto manufacturers have developed technologies enabling the car to determine its own rate of travel, based on traffic conditions. These systems are known as adaptive cruise control.
Imagine driving down the highway with no throttle or braking input whatsoever. This is what adaptive cruise control systems give you the ability to do. Perfectly suited to heavy traffic conditions, cars with adaptive cruise control systems match the speed of a vehicle traveling in front of them. The better systems will even stop the car if the traffic in front of it stops.
Also known as “active”, “dynamic”, and “smart” cruise control systems, with these in place, driving in traffic is considerably less stressful. Further, on long drives, adaptive cruise control systems permit you to concentrate on steering only while the system keeps your car moving with the flow of traffic.
Currently there are two different configurations for adaptive cruise control systems. They can be either radar-based, or laser-based. Both look ahead of the car for traffic or other obstructions and match the speed of the car to moving objects in front of it. If the system detects an immobile object, some will disengage and return throttle control to the driver, while others bring the car to a complete stop under a certain speed.
The first automaker to offer an active cruise control system was Mitsubishi, on the 1995 Diamante for the Japanese market. Two years later, Toyota offered what they called radar cruise control on the Celsior (the car which eventually came to be known as the Lexus LS in other parts of the world). The first car to bring adaptive cruise control to the U.S. market was the model year 2000 Lexus LS 430. For 2006, Mercedes-Benz refined its version of the adaptive cruise control (Distronic in Mercedes-speak) system to completely halt the car if necessary.
The hardware for active cruise control systems is now also being leveraged to provide collision avoidance capabilities. For example, the Volvo S 60s system can detect the presence of pedestrians ahead of the car, and if it looks as though a collision with one of them is imminent it will bring the car to a complete stop. These systems, when used in conjunction with advanced Lane keeping systems now under development will eventually bring us the fully autonomous car.