BMW Dynamic Damping Control (DDC)


The next stage of evolution is the automatic adjustment of suspension elements to diverse operating conditions like varying road surfaces or certain manoeuvres. BMW Motorrad will be realising this in the near future in the form of dynamic damping control (DDC). DDC is a semiactive suspension system that reacts automatically to manoeuvres like braking, accelerating, and cornering on various road surfaces and analyses the situational parameters provided by sensors to set the correct level of damping at electrically actuated proportional EDC valves. DDC is linked to the traction control system DTC and ABS via the CAN bus. The system recognises the control activities by the other systems and adapts the damping as the situation requires. The adjustments to damping depend on whether the springs are compressing or rebounding, with each process being controlled separately. The damping is adjusted at an electrically actuated, proportional EDC valve that features a variable ring gap and therefore variable flow cross section for the damper oil. The inversely proportional adjustment to flow rate and pressure adjusts the damping force within milliseconds to the new conditions. Unlike ESA II, the dynamic damping control system DDC does not make use of characteristic curves, but characteristic maps that provide the optimal damper tuning within a defined range. Selected at the press of a button, three characteristic maps for the basic configurations “Comfort”, “Normal”, and “Sport” let the rider realise his own preference on this system too. As known from ESA II, the selected configuration is displayed on the instrument cluster. Analogously to ESA II, also the DDC presents a variable spring rate. A number of examples are to provide some insights into the advantages in certain riding situations. Before the rider sets off, activating the ignition first initiates the system check and the flow of information from the engine control, ABS control unit, sensor box (DTC), and the spring travel sensors to the DDC control unit. This appears on the display in the instrument cluster. When the motorcycle sets off, the valves in the front and rear dampers are actuated only marginally (supplied with power) when the speed exceeds a definable value. When the rider accelerates, e.g. when leaving the city limits, the valve in the rear strut is actuated more strongly owing to the changes in dynamic wheel load distribution and in the drive torque. Once the target speed has been reached, valve actuation drops back to its original level (less power supply than setting off). Information flows from the throttle grip via engine control to the DDC control unit, and from there to the EDC valves. When the rider takes a series of corners, both EDC valves are actuated more strongly with increasing inclination – starting from the low power supply – until the vertex is reached. When the vehicle returns upright between two corners, the actuation of the two EDC valves constantly drops to the original power level with decreasing inclination. When the motorcycle turns into the second corner, valve actuation again rises proportionally to the angle of inclination and again drops from the vertex value. Information flows from the sensor box (DTC) to the DDC control unit, and from there to the damper valves. When the motorcycle brakes, e.g. at a rail crossing, the actuation of the front EDC valve increases proportionally to the deceleration, and the damping forces and therefore riding stability increase as a result. In this case, dynamic damping control DDC analyses both the dynamic phase of braking, to the point of constant deceleration and wheel load distribution, and the subsequent static phase. Once the adjusted speed has been reached (here for passing over the rail crossing), the power supply and therefore the actuation return to their original values. At the same time, information flows from the hand brake pump on the handlebar to the ABS, and from there via the DDC control unit to the valves. When the motorcycle is passing over the rail crossing (here representing all types of uneven road surfaces), the valves in the front and rear dampers are actuated (powered) proportionally to the compression travel. In this case, information flows from the front and rear spring travel sensors via the DDC control unit to the valves. When the motorcycle is finally brought to a stop, the valves are first actuated as in the braking process described above. As soon as the motorcycle is stationary, the power to the valves and therefore their actuation are deactivated. The advantages of the dynamic damping control system DDC are obvious. Within the shortest of times the system evaluates a huge amount of information and selects the high precision suspension configuration best suited to the situation. This provides a considerable boost to active riding safety, operating comfort, and – not least of all – to riding fun. The suspension damping system DDC will be introduced to the first BMW Motorrad series models in the near future.