Control sequence

In an ongoing control operation, the high-pass filter (fast filter) is always used to prevent the controlled height from overshooting the specified setting.

If a low-pass filter (slow filter) were used to calculate the ride height, brief changes of ride height would be "absorbed".

The low-pass filter is used when the vehicle is in motion (see NORMAL MODE ) to filter out vibrations induced by prevailing road conditions on this basis of this method of filtering.

The high-pass filter is used to respond quickly to ride level deviations from setpoint. These take place while the vehicle is stationary in the event of large load changes (see PRE-MODE ).

Both sides of the vehicle are controlled individually, i. e. even the setpoint/actual-value comparison for both sides is carried out individually.

Exception: check for falling below the minimum height in Pre-mode and Kerb mode. The left/right mean values are taken into consideration here. The following stipulations are applicable here:

• Raising or lowering
• All valves controlled with control in the same direction
• Individual wheel deactivation

To ensure reliable closing of the non-return valve in the air drier, the exhaust valve is operated briefly for 200 ms by the EHC control unit after each control sequence.

The permissible ON period is monitored while performing upward adjustment operations.