Mercedes-Benz Active Safety


Active safety New assistance for drivers Premiere: LED High Performance headlamps with complete light functionality Premiere: Active Blind Spot Assist and Active Lane Keeping Assist Premiere: Active Parking Assist steers when parking Avoiding accidents and reducing the consequences of accidents: this is the comprehensive approach adopted by Mercedes-Benz in its safety research and referred to…

Active safety

New assistance for drivers

  • Premiere: LED High Performance headlamps with complete light functionality
  • Premiere: Active Blind Spot Assist and Active Lane Keeping Assist
  • Premiere: Active Parking Assist steers when parking

Mercedes-Benz Active Safety

Avoiding accidents and reducing the consequences of accidents: this is the comprehensive approach adopted by Mercedes-Benz in its safety research and referred to collectively by the company as “Real Life Safety”.

As part of this, a variety of systems designed to reduce the burden on the driver even further will be making their debut in the new CLS.

These include Active Blind Spot Assist and Active Lane Keeping Assist as well as LED High Performance headlamps offering various light functions. The new features represent a further improvement of so-called “driver-fitness safety” by the company’s engineers. In addition to ride and seating comfort and also quiet running, a significant role is also played by the headlamp and windscreen wiper systems, for example, as well as the easy, safe operation of the vehicle.

On top of this there are also the PRE-SAFE systems which can warn, support and protect the driver when a real risk of an accident has been detected.

LED High Performance headlamps with complete light functionality

The new CLS is the first car in the world to feature optional LED High Performance headlamps, which combine the exciting daylight colour impression of LED technology with the performance, functionality and energy efficiency of today’s bi-xenon light generation.

The new light system features the Intelligent Light System which has already been tried and tested in Mercedes-Benz models with bi-xenon headlamps. Its five light functions – country mode, motorway mode, enhanced fog lamps, active light function and cornering light function – have been specifically designed for typical driving or weather conditions.

In contrast to the first vehicles equipped with LED headlamps, no compromises are now necessary with respect to the functionality and performance of the lighting technology. There are further arguments for the LED-based lighting technology: the average operating life of an LED is around 10,000 hours, around five times longer than that of a xenon light; moreover, LED headlamps most closely approximate to the colour of daylight. This means that LED light is in keeping with the normal human perception patterns. Studies have shown that the closer the colour of artificial light comes to daylight, the less the strain on the eyes. With a colour temperature of 5500 kelvin, LED light is closer to daylight (6500 K) than xenon light (4200 K). The driver’s experience of this effect is that colour impressions at night-time seem close to daylight colours and he or she has the feeling that there is greater brightness on the road.

The light specialists at Mercedes-Benz have also been able to combine LED
technology with the innovative Adaptive Highbeam Assist for the first time,
leading to a completely new level of safety at night. The basic principle behind Adaptive Highbeam Assist is as follows: if the system detects an oncoming vehicle or a vehicle in front with its lights on, the system dims the headlamps and continually adjusts the headlamp range in such a way that the cone-shaped beam of headlamp light does not reach these vehicles. There is, in addition, the Night View Assist Plus system as an option.

But good visibility is not only needed at night – and can also depend on a number of seemingly irrelevant factors. So that the CLS driver’s view when looking forward at an angle is not obscured – despite the angled coupé-like windscreen and A-pillars – the exterior mirrors are not mounted in the window triangle. Instead they have been given a new elevated position on the beltline. This improves all-round visibility, especially when turning into side streets.

Active Blind Spot Assist and Active Lane Keeping Assist

Assistance systems are becoming increasingly important these days, providing support for drivers as they perform a complex activity. In the new CLS, for
example, proven technologies like ABS, ESP® and Brake Assist work alongside
a dozen assistance systems to help prevent accidents and reduce their impact. These range from drowsiness detection to automatic full brake application on
recognising that there is an acute risk of a collision, and from Adaptive Highbeam Assist to traffic sign recognition.

One new feature is the Active Blind Spot Assist. It warns the driver when
changing lanes if a risk of collision is detected due to another vehicle in the neighbouring lane being in the so-called blind spot of the exterior mirror. If the driver ignores the warning and nevertheless initiates the lane-changing
manoeuvre, the Active Blind Spot Assist intervenes. By applying braking force
to the wheels on the opposite side of the vehicle, a yaw movement is created which counteracts the collision course.

Active Lane Keeping Assist is now also linked to the ESP® for the first time. This system kicks into action if the Mercedes vehicle inadvertently drifts over a solid line to the right or left of a lane. In such a case, a warning sign in the instrument cluster and vibration of the steering wheel give the driver warning. If the driver does not heed the warning in the case of the solid line, Active Lane Keeping  Assist can use the ESP® to brake the opposite wheels and thereby prevent the  vehicle from crossing the solid line. You can read more about these two assist  systems in the section “Under the Microscope: Assist Systems”.

Active Parking Assist including PARKTRONIC

Active Parking Assist will assist drivers in the chronically congested traffic areas: the CLS can not only detect parking spaces, but also help with the parking itself. This is made possible thanks to a combination of the new electomechanical direct steering (see the section entitled “Suspension”) and a series of ultrasonic sensors. This standard convenience system features the following functions:

  • Measurement of the length and depth of potential parking spaces at a
    vehicle speed of up to 36 km/h

  • Calculation of a suitable parking course based on the current position
    of the vehicle

  • Control of the steering in order to maintain this parking course.

Parking spaces are measured using two enhanced ultrasonic sensors integrated into the right and left sides of the front bumper. Depending on the speed and driving cycle, these sensors are used to measure parking spaces and also to support the PARKTRONIC functionality.

When driving at less than 30 km/h, a “P” symbol is displayed in the instrument cluster to inform the driver that the active parking space search function is  enabled. If a parking space is found, an arrow appears next to the “P” symbol. By default the arrow indicates parking spaces on the front-passenger side. If the turn indicator is set to the driver’s side, parking spaces on the driver’s side will be displayed. It is not necessary to switch on the parking space search function. The ultrasonic sensors only carry out a geometric assessment of the potential parking space, and do not assess whether this free space is actually a parking space.

Responsibility during the parking process also remains with the driver. If the ultrasonic sensors detect a pavement then the vehicle is parked parallel to this.

Automatic steering: this is how the parking process works

The Active Parking Assist parking process begins when the vehicle is in front of the parking space indicated by the arrow, facing the direction of travel, and the driver has engaged reverse gear and confirmed an appropriate warning dialogue with the system via the instrument cluster. The driver continues to control the accelerator and brake pedals whilst manoeuvring into the parking space.

The Active Parking Assist takes over lateral guidance by controlling the electric steering in accordance with the longitudinal dynamics specified by the driver and the parking course.

The maximum speed of this parking process is limited to 10 km/h. If the speed reaches 7 km/h, a warning appears in the instrument cluster – “Parking Assist only functions up to 10 km/h” – accompanied by a warning tone. The familiar PARKTRONIC function can be used without any restrictions being imposed. The system switches off as soon as the driver intervenes in the automatic steering control process, switches off the system via the PTS (Parktronic Sensor) button, both the driver’s seat belt buckle is released and the driver’s door opened, or a system error occurs.

The entire PARKTRONIC and Active Parking Assist system comprises the
following components:

  • Control unit
  • Ten ultrasonic sensors, two of which have an extended range
  • PTS warning elements on the dashboard and in the roof lining at the rear
  • PTS button

A maximum of five manoeuvres are allowed (backwards-forwards-backwards-forwards-backwards). The wheels are then straightened out again. The final
parking manoeuvre is notified in the instrument cluster with the message
“Parking Assist completed”, accompanied by a confirmation tone.

Wake up: ATTENTION ASSIST issues warning on detecting drowsiness

Studies have shown that around a quarter of all serious motorway accidents are caused by drowsy drivers, making this factor an even bigger cause of accidents than driving under the influence. With ATTENTION ASSIST, fitted as standard, Mercedes-Benz is therefore making another important contribution towards helping to avoid accidents: it employs high-resolution sensors to observe driver behaviour and can recognise whether the driver is tired or not paying attention, based primarily on steering wheel movements.

The ATTENTION ASSIST system developed by Mercedes-Benz measures more than 70 parameters which are analysed to detect fatigue. This continual monitoring is important in order to recognise the gradual transition from alertness to tiredness and give the driver plenty of warning. Based on a variety of data, ATTENTION ASSIST creates an individual driver profile during the first few minutes of each journey and compares this with sensor data and the driving situation as recognised by the vehicle’s electronic control unit. Alongside values such as the steering behaviour of the driver, the Mercedes-Benz system also measures driving conditions such as speed, longitudinal/lateral acceleration, indicator and pedal usage, as well as external factors such as the unevenness of the roads.

DISTRONIC PLUS: now with enhanced functions

The radar-based DISTRONIC PLUS proximity control supports the driver at speeds between zero and 200 km/h by automatically adjusting the distance to the vehicles in front. In doing so it is able to apply the brakes to bring the vehicle to a complete standstill and also accelerate it again. As a result, the system is also particularly convenient in stop-and-go traffic. If the system detects that the distance is being reduced too quickly, it warns the driver with both visual and audible signals.

With the introduction of the new generation of the CLS, the functionality of DISTRONIC PLUS has been enhanced even further. It now reacts earlier to vehicles which cut in, and the vehicle accelerates quicker when the vehicle is changing lanes and where the overtaking lane is clear. Thanks to the incorporation of information from digital maps (navigation mode), automatic control has also been further refined.

Additional assistance: from the ADAPTIVE BRAKE to the PRE-SAFE® Brake

  • ADAPTIVE BRAKE: this Mercedes-Benz brake system offers assistance functions for greater safety and comfort, such as a HOLD function when waiting at traffic lights, and Hill-Start Assist which can help prevent
    rolling backwards when moving off on a slope. (standard)
  • Adaptive Highbeam Assist: when vehicles are detected ahead of or
    oncoming to the vehicle, this system automatically dips the beams and adjusts the range of the headlamps appropriate to the distance. (standard)
  • Brake Assist PLUS: this system is able to recognise an impending
    rear-end collision using radar sensors. It calculates the necessary degree of braking assistance and makes it available immediately when the driver presses the brake pedal. (option)
  • Headlamp Assist: a sensor on the windscreen detects the lighting
    conditions. As a result, the headlamps can be turned on automatically when darkness falls. (standard)
  • Night View Assist PLUS: The display in the dashboard shows a realistic grey-scale image from an infrared camera that monitors the road ahead of the vehicle. Any pedestrians detected are additionally highlighted in the display with so-called photo corners. (optional)
    • PARKTRONIC: ultrasonic sensors assist the driver when parking. (standard)
  • PRE-SAFE® Brake: autonomous braking if acute danger of an accident is detected. At first the driver is given both an acoustic and an optical warning if the system identifies there is a danger of collision. If the driver does not react to this, the system brakes the vehicle autonomously. This occurs in two stages: around 1.6 seconds before the calculated impact point the system decelerates the car with around 40 percent (approx. four m/s²) of the maximum braking power, gives the driver an additional, haptic warning of the impending impact and as a precaution activates the reversible PRE-SAFE® occupant protection system. If the driver still fails to react, the PRE-SAFE® Brake activates the maximum braking power around 0.6 seconds before the now unavoidable collision – this emergency braking can greatly reduce the severity of the impact. The system therefore acts like an “electronic crumple zone”, offering the car occupants even greater rotection. The PRE-SAFE® Brake is active at speeds of between 30 and 200 km/h when moving vehicles are detected in front of the car. The system also reacts if the car approaches a stationary queue of traffic, providing its speed is below 70 km/h. (standard)

Under the microscope: new assist systems for active safety

Protection against the blind spot, help when changing lanes

Active Blind Spot Assist warns the driver if it detects a risk of collision when changing lanes. Short-range radar sensors housed on both sides of the rear bumper monitor the areas directly alongside and behind the car.

This process enables them to see if there is another vehicle in the next lane –
in the so-called blind spot. In such situations, the system informs the driver by
illuminating a red warning signal in the glass of the exterior mirror. If the driver fails to see this warning and indicates to change lanes, a warning signal sounds as well.

In an innovation from the latest stage of development, if the driver ignores warnings and the vehicle comes dangerously close to the next lane, Active Blind Spot Assist will intervene. Applying braking force to the wheels on the opposite side of the vehicle via the Electronic Stability Program ESP® creates a yaw movement which counteracts the collision course.

The system intuitively deactivates as soon as the driver steers against the effects of the braking intervention or the vehicle accelerates.

If an accident can no longer be avoided in spite of correcting the direction, Active Blind Spot Assist can mitigate the consequences of a collision through course correction. Where the system detects vehicles or obstacles just a short distance away on the opposite side, it will adapt its braking intervention accordingly.

To do so, Active Blind Spot Assist also uses data from the front sensors for DISTRONIC PLUS proximity control.

Brake actuation to correct the course occurs between 30 and 200 km/h. The effect is limited to longitudinal and latitudinal deceleration of 2 m/s2. When ESP® is in OFF mode, Active Blind Spot Assist is switched off. Visible warning in the exterior mirror is active up to a speed of 250 km/h.

Active Lane Keeping Assist with ESP® support

Active Lane Keeping Assist is now also linked to the ESP® for the first time. This system kicks into action if the Mercedes vehicle inadvertently drifts over a solid line to the right or left of a lane. In this case, Active Lane Keeping Assist uses the ESP® to brake the wheels on the far side in order to prevent the vehicle from crossing the line and to bring the vehicle back on course.

A display on the instrument cluster warns the driver at the same time. If broken lane markings are crossed, the system controls an electric pulse generator in the steering wheel which generates vibrations for a short time – a discreet but highly effective cue to countersteer immediately. Before the braking system intervenes, the steering wheel always vibrates to provide a haptic warning.

Active Lane Keeping Assist is based around a camera on the inside of the windscreen. It is able to recognise lane markings by analysing the difference in contrast between the road surface and the boundary lines. The image processing solution informs an electronic control unit which determines and detects the position of the vehicle if it drifts out of this lane to the left or right. For maximum reliability, the new generation of Lane Keeping Assist also evaluates radar signals in addition to image processing. Only when both lane algorithms concur is braking force applied to correct the course. Unlike conventional systems of this type, the Mercedes assistance system also assesses the behaviour of the driver and is therefore able to determine whether the vehicle is leaving the registered lane intentionally or unintentionally.

Braking intervention to correct the course occurs between 60 and 200 km/h.
It does not materialise if:

  • ESP® is deactivated,
  • the radius of the bend is less than 150 metres,
  • the vehicle is driving on tyres in emergency run-flat mode, when braking or accelerating by more than 2 m/s², on bends with lateral acceleration of over 2 m/s² (sporty driving style).

The steering wheel will not vibrate if the driver:

  • is accelerating before overtaking or joining the highway,
    • brakes sharply,
    • steers into a bend,
    • cuts a corner intentionally,
    • uses the indicators,
  • is moving back into the original lane after overtaking,
    • actively countersteers.

Furthermore, Lane Keeping Assist is deactivated immediately if ABS, ESP®, Brake Assist or another active safety system intervenes.

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