Position sensor for magnetically suspended member

Apparatus for providing a signal representative of armature displacement in a magnetic bearing assembly for a magnetic suspension system, of the type having a force sensor (34, 36) applied in a closed loop to provide a linear response with respect to an input force command signal. Signals representative of currents (I,, 12) applied to the magnetising coils (22,24;26,28) and of the sensed force are used to derive the armature displacement signal. The signal so derived is applied to modulate the magnetic flux and obviates the need for proximity devices for sensing armature displacement. A circuit (88) for generating the armature displacement signal is provided.