In 1998 a long-held dream for many drivers was fulfilled with the Mercedes-developed DISTRONIC proximity control system: an electronic co-pilot which keeps the car at a set speed and at a set distance from the vehicle ahead – for more convenience and less stress. Mercedes-Benz has now developed this highly efficient support system even further, hence the name DISTRONIC PLUS.
By combining the previous DISTRONIC radar (77 GHz) with a newly developed close-range radar (24 GHz), which is also used for Brake Assist PLUS, Mercedes engineers have been able to extend the working range of the proximity control system even further, so that it can now scan a distance of anything from 0.2 to 150 metres. While the 77-Gigahertz radar monitors the road ahead over a long distance, the signals from the 24-Gigahertz sensors have a range of around 30 metres and monitor the immediate vicinity of the vehicle. The electronic control unit analyses the information received from both radar systems and calculates the engine, automatic transmission and braking parameters required for proximity control.
In addition, the speed range for this control function has been increased from the previous 30 - 180 km/h to zero - 200 km/h. This means that when the traffic tails back, DISTRONIC PLUS automatically brakes the CL-Class to a standstill and accelerates back to the set speed as soon as the traffic situation allows. To move off automatically, the driver only needs to operate the DISTRONIC stalk on the steering column or briefly depress the accelerator.
As before, the required interval can be set according to the traffic flow and density: using a control function on the DISTRONIC stalk, the driver is able to variably adjust the time lapse between one and two seconds if required by the traffic situation. The medium setting corresponds to a time lapse of 1.5 seconds, representing a gap of around 42 metres at a speed of 100 km/h. The target and actual distances between the CL-Class and the vehicle ahead are shown in the central display of the instrument cluster.
Automatic braking to a standstill
As more dynamic proximity control intervention is often required at lower speeds, i.e. in stop-and-go traffic with frequent starting and braking, the acceleration and deceleration values of the system have been reconfigured. Depending on the speed, automatic deceleration of up to four m/s² (previously two m/s²) is now possible. If DISTRONIC PLUS detects that heavier braking is required, a warning light appears in the instrument cluster. This is accompanied by an intermittent, audible warning which tells the driver to watch the traffic situation and apply the brakes himself if necessary.
The electronic proximity control system can be activated independently of DISTRONIC PLUS. In this case too, the system continuously monitors the distance from the vehicles ahead and gives the driver an audible warning if he is approaching another vehicle too rapidly at a speed of more than 30 km/h, and lights up a warning lamp if the gap is too small.
Parking guidance system: radar technology shows the way into a parking space
A newly developed parking guidance system is celebrating its series production debut in the CL-Class. This uses radar technology to help the driver find a suitable parking space and park the vehicle. When driving past at a speed of up to around 40 km/h, side-mounted radar sensors in the front and rear bumpers of the new luxury Coupé measure whether the parking spaces on the driver and front passenger sides are sufficiently large for the vehicle. Once the system has found a suitable parking space on the front passenger side, a blue "P" symbol appears in the instrument cluster if the vehicle speed is below 16 km/h. Parking spaces on the driver’s side are shown if the indicator on that side is operated.
Once the driver has stopped the Coupé in the position shown on the display and engaged reverse gear, the display shows a symbolic, bird’s-eye-view representation of the parking situation. Coloured guide lines show the driver how best to park: a red line indicates the current steering angle, while a blue line shows the steering angle required for parking. The driver now turns the steering wheel until the two lines coincide, and can then begin to reverse slowly.
As soon as the ideal and actual steering angles coincide, the guide lines on the display change to green. When reversing, an acoustic signal informs the driver when it is time to countersteer.
During the parking manoeuvre, the guidance system continuously monitors the steering angle and vehicle position. If the driver stops before reaching the recommended position, for example, the system automatically recalculates the ideal steering angle for smooth parking.
The new, radar-based parking guidance system, which will be optionally available for the new CL-Class from the end of 2006, works in tandem with the Parking Assist feature familiar from the S-Class. This system uses radar to measure the distance to obstacles in front of and behind the car, informing the driver by means of the display and an intermittent acoustic warning.
The system uses the four close-range sensors at the front and two radar sensors in the rear bumper to assist the driver when parking or warn him of obstacles when reversing. The newly developed system operates with a much greater range and coverage than PARKTRONIC, which is based on ultrasound technology. The radar sensors of Parking Assist operate up to a distance of eleven metres and have a scanning angle of 40 degrees, which means that the driver is warned of an impending collision much sooner. This is an advantage which becomes particularly obvious when reversing over a longer distance. In this case the system is active from a speed of seven km/h, and warns the driver with an audible signal if a collision threatens. This allows enough time to prevent the collision with firm operation of the brake pedal.
When parking the vehicle, the system assists the driver within a speed range from zero to 16 km/h. When moving forward, the colour display in the instrument cluster shows two segments which indicate the distance from an obstacle within the range of the radar sensors on the left and right sides. When the first red segment lights up an intermittent warning is also sounded. A constant warning note is sounded when the second red segment is reached, informing the driver that the minimum distance has been reached. When reversing, a display in the rear roof liner is switched on and indicates the distance from any obstacles – once again for each side of the vehicle and with an acoustic warning over the last few centimetres.
Reversing camera: electronic eye in the boot lid
The new CL-Class can also be supplied with the proven PARKTRONIC ultrasound-based parking system, which assists the driver when parking. A special reversing camera provides further assistance. The reversing camera, mounted in the boot lid above the licence plate, is activated automatically when the driver engages selector position "R". It projects an image of the area behind the vehicle onto the COMAND display. Based on the vehicle dimensions, speed and steering angle, a control unit calculates the optimal path the vehicle should take into the parking slot. Coloured lines are superimposed on the camera image to guide the driver.
LINGUATRONIC: voice control for radio, audio, telephone and navigation
For a number of years now, this Mercedes-Benz-developed voice control system has been establishing itself as an important support system which enhances both safety and convenience. In the new CL-Class, the driver can use LINGUATRONIC (optional) to control the telephone, audio system and navigation system. After activating LINGUATRONIC using a button on the steering wheel, all the driver has to do is say the word - or words - and the radio will search for or store another station, switch to the next track on a CD or enter the desired destination in the navigation system. In this way LINGUATRONIC reduces driver stress, allowing him to devote more attention to the road and traffic conditions.