ADAPTIVE CRUISE CONTROL

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INTRODUCTION
Adaptive Cruise Control (ACC) technology automatically adjust the vehicle speed and distance to that of a target vehicle. ACC uses a long range radar sensor to detect a target vehicle up to 200 meters in front and automatically adjusts the ACC vehicle speed and gap accordingly.
ACC automatically decelerates or accelerates the vehicle according to the desired speed and distance settings established by the driver. As per standard cruise control the driver can override the system at any time.
PRINCIPLE OF ACC
ACC works by detecting the distance and speed of the vehicles ahead by using either a LIDAR system or a radar system the time taken by the transmission and reception is key of the distance measurement while the shift in frequency of the reflected beam by doppler effect is measured to know the speed.
Second generation generation of acc is ‘’stop and go cruise control’’ .whose objective is to offer the customer longitudinal support on cruise control at lower speed or in afrequently stopped and congested.
USING SENSORS
Currently four means of object detection are technically used and applicable in a vehical environment.
RADAR
LIDAR
VISION SENSOR
ULTROSONIC SENSOR
Common Terms In Acc
Response time of the driver (t): time needed by the driver to response safely to any unwanted disturbances (approximately about 2-3 sec)
Safe distance: the distance between vehicle equipped with ACC to the leading vehicle in front where the driver is still able to response safely in case of emergency brake happened to the vehicle in front
Safe distance = Vs * t
Vs = speed of ACC vehicle
t = 2-3 sec
CONTROLLER
Depending on present traffic situation,two types of the controls are possible.
Speed Control
Headway Control
EXAMPLE OF ACC
the motorola ACC Constitutes a dsp module having MGT5200 which prvides a multiply accmulator.
the sensor data such as radar information that from camera and an IR sensor are processed in it,to generate the input data for the controller modules like HC12 and MPC565
MOTOROLA ACC
MPC565
HC12
CAN(Control area network)Bus
Co operative ACC
The CACC system allows the vehicles to communicate and to work together to avoid collision.
ADVANTAGES
The driver is relieved from the task of careful acceleration,de acceleration and braking in congested traffic.
A highly responsive traffic system that adjust itself to avoid accidents can be developed.
Since the breaking and accelerating are done in a systematic way,the efficiency of the vehicle is increased.
CONCLUSION
The accidents caused by automobiles are injuring lakhs of people every year. The safety measures starting from air bags and seat belts have now reached to ACC,SACC,CACC..