Adaptive Cruise Control General Information: Notes

Requirements For Adaptive Cruise Control Regulation

The Following Information Is Necessary For The ACC:

-- The distance of the vehicle in front.

Fig 1: Cruise Control Regulation (Distance Of The Vehicle In Front)

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The time span between the transmission and the reception of the signal depends on the distance of the object. This means, the further away the object or vehicle is, the longer it takes for the signal to be transmitted and received.

-- The speed of the vehicle in front.

Fig 2: Cruise Control Regulation (Speed Of The Vehicle In Front)

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If the distance to the vehicle in front decreases, the frequency of the signal sent increases. If the distance to the vehicle in front increases, the frequency of the signal decreases.

Distance to the Vehicle in Front	The Time Span Between the Transmission and the Reception of the Signal	Frequency
Remains the same	The time span remains the same	Remains the same
Increases	The time span increases	Decreases
Decreases	The time span gets smaller	Increases

The vehicle electronics monitor this frequency and send the speed value.

-- The position of the vehicle in front.

Fig 3: Identifying Vehicle Electronics Monitor Frequency

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The signal expands like a cone.

The signal strength decreases as the distance of the vehicle in the front increases.

In order to determine of the position of the vehicle in front, it is also necessary to know the angle of the vehicle in front to your vehicle.

Fig 4: Four-Beam Radar

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A four-beam radar is used for this.

The angle information provides the relation of the amplitudes (signal strength) of the received (reflected) signals of the individual radar pulses