Proposal of Force Measurement Using Series Magnetic Suspension Available to Purchase

Series magnetic suspension is applied to force measurement. In a double series magnetic suspension system, two floators are suspended with a single electromagnet. The attractive force of the electromagnet directly acts on the first floator in which a permanent magnet is installed. The motion of the second floator is controlled indirectly through the attractive force of the permanent magnet. When PID control is applied to the second floator, the first floator displaces proportionally with the external force acting on the second floator even though the second floator does not move in the steady state. Therefore, the force can be estimated for the displacement of the first floator. When the stiffness between the first and second floators is low, even small force leads to large displacement so that the proposed measurement method is suitable for noncontact measurement of micro force. An apparatus was fabricated for experimental study on the proposed measurement method. Its effectiveness was demonstrated experimentally.