Adaptive Cruise Control (ACC) - Simple Explanation

Posted by Kannan G on
Adaptive Cruise Control

The conventional cruise control allows the driver to maintain only the set speed by accelerating or decelerating the vehicle and the driver always has to apply the brake when the preceding vehicle moving at a slower speed. So, in congested traffic conditions where speeds vary widely, these systems are not so effective. But, Adaptive Cruise Control (ACC) automatically adjusts the vehicle speed and maintain a safe distance from the preceding vehicles. In ACC, forward-mounted sensors are used to maintain a safe gap based on the distance and speed of the preceding vehicle.

If the preceding vehicle begins to slow, adaptive cruise control gives the signal to the engine and brakes to slow the vehicle and maintain the preset gap by using the data collected by sensors. Some systems allow the driver to specify longer or shorter following distances. When the preceding vehicle begins to speed up, Adaptive Cruise Control automatically accelerates the vehicle up to the set speed. If the lead vehicle slows below a certain speed, some systems may disengage and warn the driver to brake before other preceding vehicles may bring the vehicle to a complete stop. ACC improves the driver's comfort in steady traffic conditions, free the driver from frequent accelerations and decelerations and also reduces the driver's stress in varying traffic conditions.

Let's say simply the step-by-step working of Adaptive Cruise Control. The steps are,
  • Switch on the ACC
  • Set desirable speed
  • Sensors detect the preceding vehicle's speed
  • Decelerate or accelerate as per preceding vehicle speed.
  • Maintains safe distance

Different Types of Adaptive Cruise Control (ACC) Systems:

  • Laser-Based System 
  • Radar-Based System

Laser-Based System 

A laser scanner (SICK LMS) is mounted in front of the vehicle in order to get a clear obstacle detection in a range that can reach up to 90 m, depending on weather conditions. By using the information collected from the laser scanner, a map of the environment around the vehicle can be created and thus, the vehicle's velocity can be adjusted as per the preceding vehicle's speed. Also, this helps to produce an emergency stop in case of an imminent collision. The laser-based systems are not so effective in adverse weather conditions.

Radar-Based System

This type of system uses radio for obstacle detection. The radar system consists of a transmitter producing electromagnetic waves to detect and find the exact location of a vehicle. The radiated energy into space creates the echo signal reflects from the obstacle that helps to calculate the velocity of the preceding vehicle. Then the speed of the vehicle will be adjusted as per the radar system's signal. Compared to the laser-based ACC system, the radar-based ACC system performance is good even in heavy rain and fog.

Advantages of Adaptive Cruise Control (ACC):

  • It enables stress-free driving.
  • It is very useful for long driving.
  • ACC can avoid unconscious violation of speed limits.
  • Increased fuel efficiency.
  • Accidents can be reduced.

Disadvantages of Adaptive Cruise Control (ACC):

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