Indcutive absolute angular position sensor

The need for angular position sensors is not to be proved: it is general in industry. But for some applications, like tools machines, they have to be very precise, whatever the mechanical plays are. We propose a structure insensitive to every kind of play: radial, axial and precession play. The rotor has no windings and is ferromagnetic. The stator is non magnetic, except for a U shaped ferromagnetic core supporting a coil and straddling the rotor (fig 1). The reluctance of the magnetic circuit varies through the rotation of the rotor, depending on the shape of the rotor. The inductance of the coil also varies. The shape of the rotor depends on the way we want to make the measurement and on the form of signal we want to have.