Automatic Brakes and Brake Support
Automatic brakes and brake support
Automatic brakes and brake support
The brake support function in the event of a collision risk is designed to help the driver to quickly and effectively obtain the necessary brake effect that he/she requests from the vehicle in situations where there is a risk of a collision.
Function automatic brakeBrakes the vehicle automatically at imminent risk of collision with a pedestrian or vehicle in front if the driver does not react in time by braking and/or steering aside. The function automatic brake can prevent a collision, or reduce the speed by up to 35 km/h and thus reduce the collision force. The function automatic brake is active at speeds from 4 km/h and up.
Vehicles equipped with a Forward Sensing Module (FSM) (4/80) have a forward facing camera (27/5) installed by the rear view mirror, and in some vehicles, there is also a Forward Looking Radar (FLR) (7/203) installed in the front (behind the grill). Forward Looking Radar (FLR) is only in vehicles equipped with adaptive cruise control, collision warning, automatic braking/brake support, and distance control.
Forward Looking Radar (FLR) measures the distance and speed to the vehicle ahead that is in its field of view.
The forward facing camera helps to classify the target within its field of view. The Forward Sensing Module (FSM) uses the information from the Forward Looking Radar (FLR) to assess the threat of a collision with the vehicle in front or pedestrian moving in the same direction or are standing still. The Forward Sensing Module (FSM) uses the threat assessment of a collision, together with the assessment of what the driver will do, to react with a warning to the driver. In case of no driver reaction, the function brake support is activated, followed by automatic brake.
Collision warning with automatic brake is designed to be activated as late as possible to avoid unnecessary actions. The collision warning and City Safety system supplement each other.
For more information about City Safety, see; Design and Function -Closing velocity module (CVM).
In the event of an imminent collision the Forward Sensing Module (FSM) can carry out the following:
1. An audible signal and/or a visual warning (See Collision warning Collision Warning ).
2. A low level of self-controlled braking force before the driver has depressed the brake pedal.
3. A reduction of the force that is required to achieve the full braking capacity of the vehicle.
4. Automatic braking to reduce the collision speed.
The required effect of the function is to maximize the braking effect for the driving conditions where there is a risk of a collision with the vehicle in front or pedestrians. The brake system achieves maximum efficiency through an increase of braking torque. This reduces the total braking distance without negatively affecting the driver, passengers or the behavior of the vehicle. In the event of a possible collision the brake assistance function triggers braking to minimize delays in the braking system and increases the driver's ability to brake.
In order to carry out a brake activation, brake support or automatic braking, the Forward Sensing Module (FSM) communicates with the Brake control module (BCM) (4/16), which in turn activates the hydraulic unit.
The main component in the function is the hydraulic modulator, which is integrated with the Brake control module (BCM). The primary function of the hydraulic modulator is to create the required brake pressure, which is based on a control signal. The hydraulic modulator is an electromechanical component that receives control signals from the Brake control module (BCM). The Brake control module (BCM) supplies the hydraulic modulator with sufficient control signals based on the driver's actions, the vehicle's speed and the information from the Forward Sensing Module (FSM). The hydraulic modulator achieves the desired brake pressure/brake torque for each wheel, based on the requested brake effect set using necessary information.
The Forward Sensing Module (FSM) requires, except to be able to control the hydraulic modulator, information from the Brake control module (BCM).
Information that the Forward Sensing Module (FSM) requires:
- stoplamp switch
- brake pedal position switch
- speed
- calculated braking force.
For more information about the Brake control module (BCM), see Design and Function - Brake control module (BCM).
The system cannot detect pedestrians if big parts of the body are not visible to the camera. This means that the system must be able to identify head, arms, shoulders, legs, upper and lower body as well as normal human movement patterns.
- To enable detection of a pedestrian, they must be fully visible and be at least 80 cm tall.
- The system cannot detect pedestrians who carry big objects.
- The camera's ability to see pedestrians at dusk and dawn is limited - just like the human eye.
- The camera's ability to see pedestrians is disabled when driving in the dark and in tunnels - even when the street lights are on.
Note! Collision warning and automatic brake for pedestrians are disabled at vehicle speeds over 80 km/h.
Note! The camera has a limited range for pedestrians and therefore the system gives effective collision warnings and automatic brake at speeds up to 50 km/h. For stationary or slow-moving vehicles collision warnings and automatic brake are effective at speeds up to 70 km/h.
Caution! No automatic system can guarantee 100% correct function in all situations. Therefore, never test the automatic brake system against people - this may lead to severe injuries and fatal dangers.