The Brake Assist, abbreviated BAS, can be found in almost every newly registered motor vehicle today. This article shows how a brake assistant works and what advantages it offers for road safety.
What is the function of brake assist?
Brake Assist was originally developed by Mercedes-Benz and was initially installed as standard in 1996 in vehicles of the S-Class 140 series and the SL Coupés of the R 129 series. The abbreviation BAS is a registered trademark of Daimler AG. The system was developed on the basis of an evaluation of numerous rear-end collisions. The analysis of the accidents had shown that the main reason for rear-end collisions is too little distance to the vehicle in front and a speed that is not adapted to the traffic situation. Another result of this analysis was that drivers brake too timidly and too hesitantly in an emergency situation.
The drivers of the accident vehicles did not even come close to using the braking power of their car. Internal investigations by Mercedes-Benz have shown that the average braking distance at a speed of 100 km/h is 70 m. This was despite the fact that the drivers stated that they braked with full force. However, it turned out that the braking force was actually so low that the ABS was not activated.
Many drivers do not dare to step on the brakes courageously and with all their strength in emergency situations. Overall, about a third of all drivers do not use the full braking power of their vehicle during emergency braking. These findings ultimately led to the development of Brake Assist. Brake Assist detects dangerous situations and supports emergency braking. This significantly shortens the braking distance. According to Mercedes, to only 40 m with emergency braking from 100 km per hour.
How does Brake Assist BAS work?
Brake Assist uses various sensors to detect the relationship between the speed being driven and the speed at which the brake pedal is being pressed. In addition, the system detects how quickly the driver switches from the accelerator pedal to the brake pedal. The Brake Assist BAS uses this sensor data to detect whether emergency braking is taking place. In addition, other data is collected and evaluated, for example by the ABS. In practice, a brake assistant works as follows.
If you as a driver quickly release the accelerator pedal of your car and step on the brake pedal within a short time, the BAS assumes emergency braking. If they do not press the brake pedal hard enough, the brake assistant increases the brake pressure via the brake booster. The brake pressure is increased until the ABS is activated. This means that the brake assistant increases the brake pressure for emergency braking to the maximum.
The brake pressure is increased automatically and regardless of how hard you press the brake pedal. Only when you, as the driver, reduce the pressure on the brake pedal again does Brake Assist also reduce the brake pressure. The brake pressure then corresponds to the value it must have at this brake pedal position. Introduced in 1996, Brake Assist does not react automatically to a traffic situation, but to the driver's behavior. Only the BAS Plus brake assistant, introduced in 2005, can react autonomously.
Mercedes first introduced the extended brake assistant BAS Plus in 2005 in vehicles of the S-Class (221 series). BAS Plus is a predictive brake assist. It supports Mercedes drivers even more effectively in dangerous situations. The system uses the radar technology of Mercedes' Distronic. The radar system continuously measures the distance to the vehicle in front. It warns Mercedes drivers visually and acoustically of too small a distance. At the same time, BAS Plus also continuously calculates the required braking assistance in the event of an imminent rear-end collision.
Combination of BAS with other security systems
Mercedes-Benz is continuously developing Brake Assist BAS and combining it with other safety systems such as Mercedes Pre-Safe. In conjunction with Pre-Safe, as soon as BAS Plus detects a dangerous situation, the backrests are erected to ensure optimal protection by the seat belts and the sunroof is closed. According to Mercedes, the new systems remove the separation between active and passive safety when driving for the first time. Nevertheless, as Mercedes emphasizes again and again, even a state-of-the-art brake assistant cannot circumvent the rules of physics. If you drive with too little distance at too high a speed, even Brake Assist will not be able to prevent a rear-end collision.
The standard equipment of light commercial vehicles and passenger cars with brake assist was mandatory in the EU for the first time from 24 November 2009. Since 24 February 2011, all motor vehicles must be equipped with a brake assist system ex works in order to be registered in the EU.