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Many modern advanced electromagnetic devices use permanent magnets as a source of magnetic field. The strong and reliable magnetic fields of today’s rare-earth permanent magnets increase their force density and are often used to improve force or torque characteristics. Most of them are based on the interaction between the magnetic field of permanent magnets and current-carrying coils, as seen in rotary or linear machines and voice coil actuators. However, some applications, for example magnetic couplings or electromagnetic vibration isolation systems, rely on the strong and position-dependent passive force between permanent magnets instead of an active force resulting from a current. An advanced vibration isolation system has been chosen for demonstration, which, compared to established technologies such as hydraulics, pneumatics or mechanics, a permanent-magnet based vibration isolator, offers a reduction in energy consumption and an increase in isolation bandwidth. The gravity is in such device compensated with permanent magnets, whilst actuators provide the necessary stabilization and may be used to improve the vibration isolation performance. An unexplored application of this technology is the isolation of heavy platforms with weights of hundreds of kilograms, in which a permanent-magnet topology compensates the gravity force. The contradictory requirements of such a system, i.e. a high gravity-compensation force combined with an extremely low stiffness for good floor vibration rejection, put high demands on the design of gravity compensators.