External vibrations as they occur in production halls or caused even just by a person passing interfere with the position of the system. The controller has to be in a position to react to it and to offset the fault. This means that the measuring system registers the fault and the controller reacts faster than the fault itself. A further prerequisite is that the object to be positioned is not caused to vibrate by external faults. The first natural frequency of the load has to be significantly higher than the frequencies occurring during positioning and due to faults. Since it is almost impossible to predict the frequency content of real faults, measures have to be taken in order to limit the highest interfering frequency. This is done with low-pass arrangements such as the heavy granite base positioned on air bellows in a high quality positioning system.
