Motion controlling includes a combining network having an acceleration input for receiving an acceleration signal representative of acceleration of a movable element and a position input for receiving a position signal representative of position of the movable element and an output for providing an inferred position signal representative of an inferred position of the movable element. The network includes a first signal processor for processing the acceleration signal to provide modified acceleration signal, a second signal processor for processing the position signal to provide a modified position signal and a combiner for combining the modified acceleration signal with the modified position signal to provide the inferred position signal.