Under the microscope: Curve tilting function - Curve artist

Jun 23, 2014
The curve tilting function in the new S-Class Coupé is a world first for series production automobiles. The vehicle leans into bends in a similar way to motorcyclists or skiers.
The lateral acceleration acting upon occupants is reduced in a way akin to when driving in a steep curve, and passengers sit more firmly. On country roads in particular, the new curve tilting function enhances motoring enjoyment and comfort. The aim is not to achieve higher cornering speeds, but a new driving experience: the S-Class Coupé glides elegantly through bends.
With the curve tilting function, the base points of the steel springs integrated into the ABC suspension struts are raised by plunger cylinders on one side of the vehicle, and lowered on the other, depending on the bend being negotiated. This allows the vehicle to incline automatically and continuously in fractions of a second on bends – depending on the road angle and vehicle speed. The effect is felt much more, since the vehicle would normally tilt outwards.
This innovative system recognises bends with the help of the stereo camera behind the windscreen, which registers the curve in the road surface up to 15 metres ahead, and using the ABC suspension's lateral acceleration sensor. The curve tilting function can be selected using the three-position ABC switch, and is active in a speed range of 15 to 180 km/h in "Curve" mode. Further selection options include "Comfort" (MAGIC BODY CONTROL with Road Surface Scan) and "Sport".
Reading the road: MAGIC BODY CONTROL
Like the new S-Class, the new S-Class Coupé is also able to recognise surface undulations in advance when equipped with MAGIC BODY CONTROL. Once ROAD SURFACE SCAN has detected such undulations with the help of the stereo camera, MAGIC BODY CONTROL adjusts the suspension in advance for the upcoming situation and uses the active hydraulics to increase or lessen the load on each individual wheel. The suspension is adapted to the relevant situation within fractions of a second, enabling body movements to be considerably reduced.  The result is unprecedented ride comfort. As ROAD SURFACE SCAN is camera-based, it works in the daytime, in good visibility, with suitable surface structures and at speeds up to 130 km/h.
The ROAD SURFACE SCAN stereo camera scans an area up to 15 metres ahead and provides a precise image of the road surface contours. Using the camera images and vehicle status information, the control unit continuously calculates the best control strategy to cope with uneven stretches such as long undulations.
Excellent foundations: Active Body Control ABC
The new functions are based on the Active Body Control (ABC) suspension. The four suspension struts are equipped with hydraulic cylinders (so-called plungers), in order to adjust the force in each strut individually. This means that the system can almost completely compensate for lifting, rolling and pitching movements of the body. The control unit receives information on the current driving situation from various acceleration sensors, level sensors on the control arms and FlexRay signals (e.g. driving speed). The system then calculates the control signals for the servo-hydraulic valves on the front and rear axle by means of the pressure sensors in the spring struts to ensure suitable proportioning of the oil flows.
Once oil flows into the plunger cylinders, this modifies the tracing point of the steel springs integrated into the spring struts, generating the necessary force to counteract the body movements. Thanks to a constantly available hydraulic pressure of up to 200 bar, ABC is able to stabilise the body within fractions of a second.
The hydraulic all-round self-levelling suspension ensures a constant vehicle level when driving straight ahead, regardless of the vehicle load, maintaining an optimum distance between the wheel and the edge of the wheel cutout on the wing. At high speeds, the level is automatically lowered by up to 15 mm to reduce the wind resistance and to lower the centre of gravity to further improve driving stability. When the engine is running, the level can also be raised at the push of a button, whether the vehicle is stationary or on the move. When the level control switch is operated, the ground clearance for poor surfaces or ramps is increased by 40 mm (30 mm for USA/Canada).
ABC has undergone major modifications for the new S-Class Coupé: the wheel damping is now continuously adjustable and the spring strut response has been improved. A digital interface connects the control unit and the sensors, while the fast FlexRay bus connects the control unit and the vehicle electronics. Processing power is more than double that of the previous system.
Crosswind stabilisation is a further function of Active Body Control. When the control detects a strong gust of wind, the wheel load distribution is changed in fractions of a second. This creates a yawing motion of the vehicle which counteracts the effect of the crosswind.
Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control, curve tilting function
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Mercedes-Benz S-Class Coupé, Active Body Control (ABC) with curve tilting function
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