Emergency brake assistant
An emergency brake assistant is a predictive driver assistance system for motor vehicles or trams that warns the driver in case of danger, supports emergency braking ( brake assistant ) or brakes automatically. This is to avoid the collision with an obstacle or to reduce the collision speed. Some emergency braking assistants can take additional safety measures.
function
Vehicles with emergency brake assist usually have sensors for determining distances, acceleration, steering angle , steering wheel angle and pedal positions. From the measured values of these sensors, the on-board computer calculates whether there are any indications of a dangerous situation and / or a critical driving condition. The data from some sensors are also used for other purposes. For example, ABS and vehicle dynamics control (also known as ESP or ESC) use the data from the sensors on the wheels. Many emergency brake assistants warn the driver e.g. B. before too little distance to the vehicle ahead before they automatically throttle and brake the fuel supply.
designation
These systems are called differently depending on the vehicle manufacturer or automotive supplier:
- Audi: pre sense
- BMW: intelligent brake (iBrake)
- Bosch: Predictive Safety System (PSS)
- Daimler: Pre-Safe Brake
- Ford: Active City Stop
- Honda: Collision Mitigation Brake System
- Volkswagen: Front Assist (identical for SEAT and Škoda)
- Volvo: City Safety
Collision warning
A collision warning system detects the distance to other vehicles or obstacles by means of a camera or radar or lidar sensor and warns the driver if there is a risk of a collision. A collision warning does not affect the braking of the vehicle. Such a system was first introduced in Germany in 2003.
Emergency brake assistant
With the emergency brake assistant, sensors monitor the surroundings and first warn the driver of critical situations in order to give him the opportunity to react. If the system detects that a collision is imminent, it calculates how hard the vehicle has to be braked to avoid the collision. When the driver then brakes, the system increases the brake pressure by the required amount.
At slow speeds, for example in city traffic, emergency braking assistants recognize vehicles driving ahead or stationary and automatically prepare the braking system for emergency braking. If the driver does not react to the situation, the emergency brake assistant can trigger an emergency braking so that a collision does not even occur. If a collision is unavoidable, the emergency braking assistant reduces at least the strength of the impact and thus also the risk of injury to the occupants of the vehicles involved.
Many newer systems react not only to other vehicles, but also to other road users such as pedestrians or cyclists. In this way, frontal collisions are avoided or weakened and safety for pedestrians and cyclists is significantly increased.
During the truck rampage at the Berlin Christmas market , such a system, which responded and braked the vehicle after the first victims hit the truck, prevented an even greater bloodbath.
Often a better camera is combined with sensors for the pedal positions. The assistant is thus able to better assess the driver's behavior according to the situation and to support the driver in coping with difficult situations. For example, if the emergency brake assistant detects a critical situation for emergency braking due to a quick release of the accelerator pedal and a forcefully depressed brake pedal , the full brake pressure required for maximum deceleration is built up immediately. In addition, depending on the system, further measures for occupant protection can be taken.
Autonomous emergency braking
An autonomous emergency braking system is an extension of the emergency braking assistant. Here, too, there are usually more and more precise sensors available compared to the emergency brake assistant. For example, a radar sensor is often installed for reliable detection of the distance to the vehicle in front and its speed, which is not required for the simpler systems. The validity of the forecasts allows the initiative to be reversed: it is not the driver who actively triggers the system, as is the case with the emergency braking assistant, but the driver can override the system. If the driver does not take any action, the system is automatically activated and brakes the vehicle.
When a critical situation is recognized, for example because the distance to the vehicle in front is becoming too small too quickly and the risk of a rear-end collision , the driver is warned visually and acoustically in a first stage. If the driver does not react, the system initially initiates a significant reduction in speed (partial braking). If the calculated distance is too short and the driver has still not reacted, emergency braking is triggered in order to avoid a collision with an obstacle or at least to minimize the force of the impact. If the system detects the obstacle or the vehicle in front too late, e.g. B. by driving over a hilltop , the system can also immediately initiate partial or, if necessary, full braking, without warning the driver beforehand. These measures are usually accompanied by other occupant protection measures. Such a system was first introduced in Germany in 2006.
Trucks
According to the legal requirements for trucks over 8 tons, the emergency brake assistant must reduce the speed by 10 km / h. In the future, the requirement is to be tightened to 20 km / h.
The assistant is regularly switched off by truck drivers due to too frequent error detection.
According to ADAC, “the emergency braking assistance function should be permanently available . As the current ADAC investigation shows, manually switching off the emergency braking assistance system is unnecessary and should not be permitted. A situation-related interruption should only be possible for a short time, whereby an automatic restart is to be provided here. "
In the case of heavy trucks, the emergency brake assistant is often combined with the adaptive cruise control .
Multi-collision brake
If the airbag control unit detects an accident and the vehicle continues to drive afterwards, the multi-collision brake triggers braking of the vehicle with 0.6 g in order to avoid further collisions or at least to reduce the kinetic energy of the vehicle as much as possible. In addition to the airbag control unit, depending on the system, other vehicle sensors, such as structure-borne noise sensors or pressure sensors in the doors, can be taken into account when deciding whether to activate the multi-collision brake.
Occupant protection system
An occupant protection system recognizes potentially dangerous situations such as skidding, excessive oversteer or understeer or too little distance. It reacts to this by reversibly pre-tensioning the mechanical belt tensioners, bringing the seats into an upright, optimal position and closing the windows and sunroof before a possible emergency. Depending on the equipment of the vehicle, folding headrests can also be set up or massage systems can be used in seats for better support.
literature
- Trucker Technik Lexikon 2008, page 4. Magazine: Trucker.
Individual evidence
- ↑ https://www.knorr-bremse.com/de/medien/pressemitteilungen/mehr-verkehrssicherheit-kiepe-electric-integriert-kollisionswarnsysteme-in-hannoveraner-stadtbahnen.json
- ↑ ureko.de: Accident Reconstruction
- ↑ Radar-based pre-crash safety system PCS in the Lexus LS
- ↑ bester-beifahrer.de. An initiative of the German Road Safety Council on driver assistance systems. Retrieved July 18, 2017 .
- ↑ Truck on-board computer prevented even more deaths in Berlin - News. Retrieved March 5, 2020 .
- ↑ Pre-Safe brakes with partial braking in the Mercedes-Benz C 216 and with full braking in 2009 in the Mercedes-Benz 212 series
- ^ ADAC: Laws for emergency brake assistants must be tightened
- ↑ [1] The state government of Lower Saxony states in the justification for their application: “With the increasing AEBS equipment of heavy goods vehicles, the field experience with such systems also increases. Control bodies u. a. determine that vehicle drivers switch off the emergency brake assistant permanently, for example so as not to be supposedly 'disturbed' by the collision warnings. " the manufacturer of which could not have come about untruthfully, has led to the opinion that these systems must not be able to be switched off.
- ^ ADAC: Study on truck emergency braking assistance systems. In: adac.de. ADAC, 2017, accessed October 16, 2018 .
- ↑ [2] Multi-collision brake