09-05-2010, 01:36 AM
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Adaptive Cruise Control
An ACC system is designed to assist the driver when following a vehicle traveling in the same lane and direction.
Conventional Cruise Control Operation
A typical conventional cruise control system controls the vehicle speed by adjusting throttle position to maintain a speed set by the driver. A control unit compares the actual vehicle speed and the desired set speed. If there is a difference between these two values, a signal is sent to a throttle position actuator to adjust the throttle position to bring the vehicle to the set speed. Depending on vehicle make and model, throttle position is achieved using vacuum-powered or electronically controlled actuators.
Adaptive Cruise Control ACC Overview
ACC is an extension of conventional cruise control systems. An ACC system is a driver convenience feature designed to maintain a set following distance from the vehicle ahead. ACC is not a collision warning or avoidance system. An ACC system is designed to assist the driver and is not a fully independent driving system. As with conventional cruise control systems, manual inputs from the driver, both to the accelerator and brake, take priority over the ACC system.
Adaptive Cruise Control
ACC systems allow for a set following distance or time interval between the ACC vehicle and the forward vehicle, as well as a set speed. Driver convenience is enhanced since fewer accelerating and braking operations are necessary. The set distance (timed in seconds) is the desired distance between the ACC vehicle and the forward vehicle. When a forward vehicle is detected, controlling acceleration and braking operations without driver intervention maintains the set distance between vehicles. The set speed is the desired maximum speed to be regulated by the ACC system on an open road. If no forward vehicle is detected, the set speed is regulated.