06-10-2012, 05:52 PM
ADAPTIVE CRUISE CONTROL
Abstract
In the recent scenario where the numbers of accidents per day are increasing due to negligence on the part of the drivers and due to the stark increase in traffic population, Adaptive Cruise Control becomes an effective way of keeping the accidents in check. Adaptive Cruise Control(ACC) is an autonomous 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 slow 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’s vehicle path, the ACC system will accelerate the vehicle back to its set control speed. This operation allows the ACC vehicle to autonomously slow down and speed up with traffic without intervention from the driver.
The driver interface to the ACC machine is very similar to a conventional cruise system thus making it extremely user friendly. The driver operates the system via a set of switches on the steering wheel. The ACC operates mainly in two modes-ACC Speed Control and ACC Time Control mode. ACC Speed Control mode is equivalent to that of conventional speed control where the vehicle’s speed is maintained at the target speed. The engine control system controls the engine output via throttle control to maintain the vehicle speed at the target speed. The ACC system enters ‘ACC Time Gap Control’ mode if the radar detects a forward vehicle at or within the clearance distance. Here the ACC system sends a target speed to the Engine Control Module and deceleration commands to the Brake Control module to maintain the set time gap between the vehicles. Communication to the Engine Control and the Brake Control modules is done via Controller Area Network(CAN). It is an automative standard network that utilizes a 2 wire bus to transmit and receive data.