A noncontact permanent magnet levitation table with electromagnetic control and its vibration isolation method using direct disturbance cancellation combining optimal regulators

A vibration isolation table levitating without contacts by drag-force type electromagnetic actuators is presented. The actuator consists of a permanent magnet connected to an electromagnet. The gravity force of the table is suspended by permanent magnets, and vibrations due to disturbances are controlled by changing magnetic fluxes of the permanent magnets. When the horizontal disturbance applies to the magnetic levitation supports of the table, the location of the magnets moves from the set position. This implies that the magnetic forces in both the horizontal and vertical directions vary due to base disturbances. An analysis of the magnetic levitation force, magnetic stiffness, and control force, is presented first and then a method of vibration control is presented. The control method is based on a disturbance cancellation combining an optimal regulator with consideration of interferences of the magnetic forces between horizontal and vertical motions.<>