Adaptive Cruise Control (ACC) is an automotive feature that allows a vehicle's cruise control system to adapt the vehicle's speed to the traffic environment. A radar system attached to the front of the vehicle is used to detect whether slower moving vehicles are in the ACC vehicle's path. If a slower moving vehicle is detected, the ACC system will slow the vehicle down and control the clearance, or time gap, between the ACC vehicle and the forward vehicle. If the system detects that the forward vehicle is no longer in the ACC vehicle's path, the ACC system will accelerate the vehicle back to its set cruise control speed. This operation allows the ACC vehicle to autonomously slow down and speed up with traffic without intervention from the driver. The method by which the ACC vehicle's speed is controlled is via engine throttle control and limited brake operation.'
The driver interface for the ACC system is very similar to a conventional cruise control system. The driver operates the system via a set of switches on the steering wheel. The switches are the same as for a conventional cruise control system except for the addition of two switches to control the time gap between the ACC vehicle and the target vehicle. In addition there are a series of text messages that can be displayed on the instrument cluster to inform the driver of the state of the ACC system and to provide any necessary warnings. The driver engages the ACC system by first pressing the ON switch which places the system into the 'ACC standby' state. The driver then presses the Set switch to enter the 'ACC active' state at which point the ACC system attempts to control the vehicle to the driver's set speed dependent upon the traffic environment.