Motion controlling

Position detection method for processing a movable element acceleration signal and a measured position signal representative of acceleration and position, respectively, of a movable element and for processing reference element acceleration signal representative of acceleration of a reference element to provide an inferred position signal said method comprising:

• differentially combining said movable element acceleration signal and said reference element acceleration signal to provide a differential acceleration signal representative of differential acceleration of said movable element and said reference element;
• low pass filtering said differential acceleration signal;
• and
• additively combining the low pass filtered differential acceleration signal with said measured position signal to provide said inferred position signal.

Closed loop motion control apparatus, comprising:

• a movable element having a position,
• an accelerometer for providing an acceleration signal representative of acceleration of said movable element,
• a combining element, for combining a reference position signal and an inferred position signal to provide an error signal,
• a controller, for providing a control signal responsive to said error signal, an actuator, for applying a force, responsive to said control signal, to said movable element to change said position, said force resulting in said acceleration of said movable element,
• a feedback loop, for providing said inferred position signal, said feedback loop comprising a combining network for providing said inferred position signal, said combining network including
• an acceleration input for receiving said acceleration signal,
• a position input for receiving a position signal representative of position of said movable element, and
• an output for providing an inferred position signal representative of an inferred position of said movable element,
• said network including a first signal processor for processing said acceleration signal to provide a modified acceleration signal, said first signal processor comprising a low-pass filter,
• a second signal processor for processing said position signal to provide a modified position signal, and
• a combiner for additively combining said modified acceleration signal with said modified position signal to provide said inferred position signal.

Open loop position detection apparatus, comprising:

• an accelerometer for providing an acceleration signal representative of acceleration of a movable element,
• a combining network having an acceleration input for receiving said acceleration signal, a position input for receiving a position signal representative of position of said movable element, and an output for providing an inferred position signal representative of an inferred position of said movable element,
• said network including a first signal processor for processing said acceleration signal to provide a modified acceleration signal, said first signal processor comprising a low-pass filter,
• a second signal processor for processing said position signal to provide a modified position signal, and
• a combiner for additively combining said modified acceleration signal with said modified position signal to provide said inferred position signal.

Position detection method for processing a movable element acceleration signal and a measured position signal representative of acceleration and position respectively, of a movable element and for processing a reference element acceleration signal representative of acceleration of a reference element to provide an inferred position signal, said method comprising;

• low pass filtering said movable element acceleration signal to provide a low pass filtered movable element acceleration signal;
• low pass filtering said reference element acceleration signal to provide a low pass filtered reference element acceleration signal;
• differentially combining said low pass filtered movable element acceleration signal and said low pass filtered reference element acceleration signal to provide a differential acceleration signal representative of differential acceleration of said movable element and said reference element;
• and
• additively combining the differential acceleration signal with said measured position signal to provide said inferred position signal.