A MAGNETIC SUSPENSION SYSTEM WITH A LARGE ANGULAR RANGE

In order to explore and develop technology required for the magnetic s uspension of objects over large ranges of orientation, a small-scale l aboratory system, the large-angle magnetic suspension test fixture (LA MSTF) has been constructed at NASA Langley Research Center. This appar atus falls into the category of large-gap, actively stabilized magneti c levitation systems. The hardware comprises five conventional electro magnets in a circular arrangement, each driven from a separate bipolar power amplifier. Electromagnet currents are commanded by a digital co ntrol system, implemented on a microcomputer, which in turn derives th e position and attitude of the suspended element from an infrared opti cal system. The suspended element is a cylindrical, axially magnetized , permanent magnet core, within an aluminum tube. The element is ''lev itated'' by repulsive forces, with its axis horizontal, 0. 1 m above t he top plane of the electromagnet conductor. The element is stabilized in five degrees-of-freedom, with rotation about the cylinder axis not controlled. By mechanical rotation of the sensor assembly, the suspen ded element can be made to undergo a full 360-degrees rotation about t he vertical axis. The controller accommodates the changes in magnetic coupling between the electromagnets and the suspended element by real- time adaptation of a decoupling matrix. This report presents a review of the background to the problem of magnetic suspension over large ran ges of orientation. Next, the design and operation procedures adopted for LAMSTF, and the system hardware are described. Finally, some perfo rmance measurements are shown, together with illustration that the maj or design objective-the 360-degrees rotation, has been accomplished.