Mercedes-Benz PRE-SAFE Archives

BAS applies maximum braking pressure for shorter stopping distances

Brake Assist (BA) is a feature which is listed among the active safety systems of many cars today but how it works and why it enhances stopping may not be known by most motorists. BA, which appeared in the second half of the 1990s, is a supplementary brake system which can also be considered a driver assistance system.

A simple explanation of BA would be that it boosts braking pressure to the maximum available as this can have a positive effect on the stopping distance, especially with anti-lock braking systems, better known as ABS.

Helping older people brake better
When Toyota first introduced it in 1997 in the Raum model, it said that one of the reasons for developing BA was to help older drivers. These drivers might not apply full pressure on the brake pedal in an emergency, or may not have sufficient strength. Thus, the system will detect when there is emergency braking, eg sudden pressure on the pedal, and boost the pressure to maximum.

*Brake Assist was introduced by Toyota in 1997 with the Raum model (below).*

Emergency braking can save lives. However, many drivers then step on the brake pedal quickly but not forcefully enough – this is what Mercedes-Benz engineers discovered in the early 1990s during tests in the company’s own driving simulator. Their answer was BAS, considered one of the key links in the chain of important Mercedes-Benz safety developments.

BAS evolved from ESP
Mercedes-Benz introduced their version of Brake Assist, which they referred to as BAS, in late 1996. It was standard initially in the S-Class (W 140) and SL (R 129) and built upon the functions of the Electronic Stability Program (ESP), or vehicle stability control as it is also known.

These advanced systems not only use the sensors installed in the car but also state-of-the-art radar technology in order to capture the scene in front of the car and to identify a situation in which an accident is imminent. Mercedes-Benz offers very similar systems for its commercial vehicles known as Active Brake Assist (in the Actros heavy-duty truck).

*BAS was introduced as standard in the 1996 Mercedes-Benz S-Class W 140 (above) and SL (below).*

How well does BAS work?
BAS interprets a certain speed at which the brake pedal is depressed as an emergency situation and builds up maximum brake boost within fractions of a second. This significantly shortens the braking distance – at 100 km/h on dry roads, for example, by up to 45%. Mercedes-Benz investigated its effect in the driving simulator and found that BA was able to mitigate or even prevent rear-end collisions.

It also made an effective contribution to pedestrian protection. In a series of experiments, 55 car drivers drove through a town at 50 km/h when suddenly a child ran onto the carriageway. Only full braking prevented the accident.

*BAS can make the difference between hitting a pedestrian and stopping in time with reduced braking distance due to maximum braking pressure being applied.*

Additional functions with BAS PLUS
The next evolutionary stage by the German carmaker was Brake Assist PLUS which made its debut in the S-Class from the W 221 series in late 2005. Besides warning the driver of an imminent head-to-tail crash by means of visual and acoustic signals, it automatically computes the brake pressure required to prevent the accident.

BAS and BAS Plus are integrated in the PRE-SAFE brake system that is today available in every Mercedes-Benz car. PRE-SAFE can automatically brake the car if a collision is predicted, and the PRE-SAFE brake works together with the BAS PLUS, the latter making its brake boosting effect available as soon as the driver steps on the brake pedal. If the driver does not react to the warning signals emitted by BAS PLUS, the PRE-SAFE brake initiates automatic partial braking to decelerate the car with some 40% of the maximum brake power.

Radar technology made the advanced capability of BAS PLUS possible. It detected the distance to cars ahead, warned the driver of insufficient distance and calculated the necessary braking assistance in the event of an imminent collision. If traffic came to a standstill and the driver actually had to step on the brake pedal, BAS PLUS built up the brake pressure calculated for the respective situation instantly.

BAS PLUS uses two radar systems: a 24-gigahertz short-range radar scanning the surroundings in front of the vehicle with an aperture angle of 80 degrees and a range of 30 metres. In addition, the 77-gigahertz radar of DISTRONIC scans 3 lanes of a motorway up to a distance of 150 metres with an aperture angle of 9 degrees. Tested in the driving simulator, the results were impressive: while the accident rate in tests with conventional braking technology was 44% on average, it dropped by three quarters with the help of BA PLUS.

*Brake Assist is also available for heavy-duty trucks like the Mercedes-Benz Actros… certainly crucial for preventing such a big and heavy vehicle from colliding with a vehicle ahead.*

Braking systems remain essential for road safety. In addition, emergency braking systems triggered on the basis of detecting potential accidents are an important foundation for the highly automated vehicles to come, and thus an essential part of the vision of accident-free driving.

Data for Road Safety initiative in Europe provides advance warning of dangers ahead

All-new Mercedes-Benz S-Class set to be a pioneer in safety features again (w/VIDEOS)

Mercedes-Benz will be launching its all-new S-Class (W223) next month and typical of the company when it comes to the prelude to a new model, information usually trickles out to highlight the innovations that the new model will introduce. In the case of the new S-Class, the company has released details of its enhanced PRE-SAFE system which has been constantly evolving since first being introduced in the 2003 S-Class (W220).

A new function is PRE-SAFE Impulse Side, which sees augmented measures in the pre-impact phase: when a side impact is likely, the car’s body can be raised up to 80 mm by the E-ACTIVE BODY CONTROL suspension (an optional feature) within a few tenths of a second. This directs the impact forces towards particularly resistant structures in the lower area of the bodywork.

There are also new occupant protection measures which are derived from many of the innovations in the ESF2019 Experimental Safety Vehicle. Firstly, the rear occupants will have the additional protection of airbags and this is the world’s first frontal airbag for the two passengers on the outer rear seats.

2019 Mercedes-Benz Experimental Safety Vehicle — *ESF 2019 – the first Experimental Safety Vehicle from Mercedes-Benz that also presents concepts for the special challenges of automated driving.*

Its design with an innovative, tubular structure is unique. The cylindrical structures are inflated with compressed gas and deploy a wing-shaped structure. A large, tent-like airbag then deploys between the two wings and this is inflated by the surrounding air via specially patented valves in the skin. These valves are designed so that the air cannot escape when the rear passenger is immersed in the airbag.

The comparatively small volume of the tubes allows rapid deployment of a relatively large airbag volume. This takes place with comparatively low force and a low risk of injury, as the tubular wings give way to obstacles. The airbag enhances the restraining effect of the belt system, and can support the head and neck to decrease the loads on them significantly. In combination with a beltbag and the inflatable seatbelt, the S-Class will set new standards for rear seat occupant safety.

Also new is a centrally located airbag (availability depends on country) between the driver and front passenger seat. During a severe side impact, the airbag positions itself between the driver and front passenger seat, reducing the risk of their heads making contact. It is integrated into the driver’s seatback in the middle of the car. The airbag is triggered when a severe side collision is recognised, and certain conditions are met.

There will also be new illuminated designer belt buckles (also optional) which are easy to locate. It’s a small touch which some may say is unnecessary cost, but it should make attaching the seatbelt easier.

In combination with the MBUX Interior Assistant, a camera can now be used to detect a childseat on the front passenger seat for the first time. A belt fastening message for the childseat appears in the central display before the driver moves off. Until now, and in many cars, the presence of a childseat is usually determined by a sensor in the front passenger’s seat.

2021 Mercedes-Benz S-Class W223 — *Occupants will get a warning as they open the door if there is a vehicle or cyclist approaching from the rear.*

The new S-Class will have the latest generation of the Driving Assistance Package with new and numerous improved functions. One of the two examples which Mercedes-Benz is revealing now is Active Blind Spot Assist to prevent opening of the door when another vehicle is coming up along the side of the car. The exit warning function now will give a warning as soon as the driver or front passenger reaches for the door. The MBUX Interior Assistant will recognise when a hand approaches the door handle and a visual warning is given by a red warning triangle in the exterior mirror and via the active ambient lighting.

2010 Mercedes-Benz S-Class W223Meet the S-Class DIGITAL: „Innovation by Intelligence“: Fahrvergnügen auf höchstem Niveau: geschützt und unterstütztMeet the S-Class DIGITAL: "Innovation by Intelligence": Driving enjoyment at the highest level: protected and supported — In a traffic jam on the highway, at speeds not more than 60 km/h, the car adjusts its movements to the surrounding vehicles as if part of a swarm, helping the driver to create an emergency corridor by moving to one side. This will allow emergency vehicles to proceed past more easily to reach an accident site ahead.

Active Steering Assist is another example and this will assist the driver in forming an emergency corridor, and encourage other drivers to form a corridor as well. Thanks to improved environmental sensors and integration into MBUX, the parking systems give the driver even better support when manoeuvring at low speed. 12 ultrasonic sensors at the front and rear provide improved performance so the positions of road-users and objects can be registered reliably and highly precisely.

Mercedes-Benz starts preview of next S-Class with details of new MBUX

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