Adaptive Cruise Control Systems

Basic Description

Adaptive Cruise Control (ACC) extends existing cruise control systems to include a headway sensor that monitors the distance between your vehicle and the vehicle ahead. The system is also sometimes called Active Cruise Control (ACC) and Intelligent Cruise Control (ICC). ACC systems are similar to the conventional cruise control systems in the way they maintain the vehicle preset speed. But, unlike conventional systems, ACC automatically adjusts the speed of the vehicle in order to maintain a safe distance from vehicles ahead in the same lane. The system automatically monitors road traffic patterns, employing a headway sensor capable of detecting vehicles at distances up to 500 ft, and using the throttle and brakes to maintain a pre-set distance behind the vehicle ahead. When the road is clear again, the system re-accelerates to the pre-set velocity.

There are two key types of headway sensors. Radar sensors employ microwave signals (typically at 35 or 76 GHz). Lidar sensors employ a laser diode to produce infrared light signals. Both types of sensors send a signal and monitor the time required for the signal to reflect off the object ahead. Although laser based systems are significantly lower in cost, they have difficulty detecting or tracking vehicles in adverse weather conditions. They can also have difficulty tracking extremely dirty vehicles. ACC, like the conventional cruise control systems, is cancelled when the driver applies the brakes.

Sensors

Headway sensor (radar or lidar), vehicle speed sensor, accelerator pedal position, brake pedal position

Actuators

Throttle, brakes

Data Communications

Control Unit Communication: Typically Control Area Network (CAN) Bus System

Manufacturers

Bendix, Bosch, Continental, Delphi, TRW

For More Information

[1] How Cruise Control Systems Work, HowStuffWorks.com.

[2] Autonomous Cruise Control System, Wikipedia.

[3] New Adaptive Cruise Control by Bendix, Cleveland Plain Dealer Video.

[4] Adaptive Cruise Control Information, Freescale website.

[5] Bendix Wingman ACB on YouTube.com.

[6] BMW Active Cruise Control on YouTube.com.

[7] Adaptive Cruise Control (in Audi A4, 2008 model) on YouTube.com.