System for determining position of an element in relation to another element using magnetic fields

A system comprising:

• a sensor assembly comprising one or more sensors each measuring position by measuring a magnetic field using a 3D magnetometer corresponding to three axes (X, Y, Z) arranged perpendicularly relative to each other,
• a moveable element moveable relative to the sensor assembly by a combined axial and rotational movement corresponding to a pre-defined axis, the rotational movement having a pre-determined relationship to the axial movement,
• a magnet mounted to the moveable element and moving together therewith, the magnet configured to generate a spatial magnetic field which relative to the sensor assembly varies corresponding to both the axial and rotational movement of the magnet and thus the moveable element, thereby generating a spatial magnetic field which varies uniquely relative to each sensor, and
• a processor configured to determine on the basis of measured values an axial position of the moveable element, wherein,
• the processor, on the basis of the measured values:
• determines an initial axial position of the moveable element using 3D magnetometers,
• determines a rotational position of the moveable element using 3D magnetometers, and
• calculates a corrected axial position of the moveable element,
• wherein the calculation is based on the determined initial axial position, the determined rotational position, and the pre-determined relationship between the rotational and the axial movement.