A rotary position sensor featuring a robust and simply constructed magnetic field assembly which provides a uniform magnetic field in the working air gap for a conventional mangetosensitive device located thereinside. The magnetic field assembly includes a plastic casing having a blind hollow, magnet pocket located at the blind end of the hollow, and a pair of diametrically opposed pole piece pockets oriented in upstanding relation to the magnet pocket. A permanent magnet is snapped into the magnet pocket, and a pole piece is respectively snapped into each of the pole piece pockets. The pole pieces may be rectangular or arc shaped, wherein the space therebetween forms the working air gap into which the magentosensitive device is placed. The magnetic field established in the working air gap is transverse to the axis of the blind hollow, and is generally uniform.

Improved apparatus is disclosed for use in a magnetic suspension system for developing signals representative of the rate of displacement of a magnetically suspended body along one or more axes thereof for use in applying forces to the body to restore it to a desired stable position. Specifically there are provided a plurality of thin, closely-spaced discs of permanent magnet material affixed to the body and a plurality of conductive windings respectively cooperating with the magnetic fields produced by said magnets, pairs of said windings being interconnected so that currents induced therein by the fields of the magnets tend to reinforce each other and so that currents induced therein by stray fields tend to cancel. The resultant currents induced in the windings are representative of rate of displacement of the suspended body and may be combined with separately derived signals representative of displacement of the body for use in applying forces to the body to restore it to its desired stable position. By suitably arranging the permanent magnets and their cooperating windings, signals may be developed representative of rates of displacement along several different axes so as to permit complete control over all possible displacements of the suspended body. In addition, in certain embodiments of the invention, there may be provided means for deriving from the rate-representative signals, signals representative of acceleration of the suspended body which also may be used to control the application to the body of forces to restore it to its desired stable position.

A magnetic bearing including a circular stator member having a plurality of circumferential pole faces and a suspended annular ring member with corresponding number of inward facing circumferential pole faces separated by respective air gaps. A source of DC magnetic flux circulates flux between the circumferential pole faces of the stator and the ring to provide axial stability along a central longitudinal axis. Flux coil means are included on the stator member for providing variable flux density along predetermined radial paths to provide active radial stabilization. Additionally, flux coil means are included on the stator to actively modulate the magnitude of the magnetic forces as well as their direction of differential flux control involving the DC magnetic flux to produce torquing moments about a pair of mutually orthogonal axes which are perpendicular to the central axis.

An actuator is provided with a rotor formed to include teeth at a predetermined pitch and a rotation control coil is wound on each of plural pole pieces formed on a core member opposing the rotor, the coils forming first, second, third and fourth magnetic poles. The rotor is rotatatively driven and angularly positioned by attracting forces between the magnetic poles and the teeth of the rotor. Magnetic flotation coils are wound on the base portion of the magnetic member to form magnetic flotation poles. The rotor is floated magnetically by attracting forces between the magnetic flotation poles and the teeth of the rotor. In an embodiment, the rotor is provided with grooves crossing the teeth to form the teeth into a mesh-like configuration. The mesh-like teeth cooperate with the magnetic poles to provide a holding force in the axial direction, so that a function equivalent to that of a thrust bearing may be performed.

A magnetic road is provided with a series of magnets having the same pole oriented upwards and an upstanding non-magnetic sidewall extending along at least one side. A magnetic object is provided having longitudinally spaced magnets which either have that same pole oriented downwards, or arranged in corresponding annuli having that same pole oriented radially outwards. In the first instance, additional provisions are made to prevent the object from rolling over. Accordingly, the object can translate along the road adjacent the sidewall while floating on mutually repelling magnetic forces.