Magnetic suspension and pointing system

DETAILED DESCRIPTION This invention includes two assemblies with each having a separate function.
The first assembly is attached to a carrier vehicle and consists of an azimuth gimbal and an elevation gimbal which provide coarse pointing of the instruments by allowing two rotations of the instruments relative to the carrier vehicle.
The second, or vernier pointing assembly, is made up of magnetic suspension and fine pointing actuators, roll motor segments, and an instrument mounting plate around which a continuous annular rim is attached which provide appropriate magnetic circuits for the actuators and the roll motor segments.
The vernier pointing assembly is attached to the elevation gimbal and provides vernier attitude fine pointing and roll positioning of the instrument as well as six degree-of-freedom isolation from carrier motion disturbances.
In addition, the second assembly has a rim centering mode in which axial and radial rim position sensors located at each actuator station are used to center the rim axially and radially between actuator pole faces.
This mode allows coarse gimbal slewing for re-targeting, for earth pointing or for backup coarse gimbal pointing.
The vernier pointing system includes electromagnets working in opposed pairs axially and either singularly or in opposed pairs radially to provide fine pointing forces on the rim of the instrument mounting plate.
The command forces originate from rim position sensors while in the rim centering mode or from instrument pointing error sensors for the axial actuators while in the vernier pointing mode.
The radial actuators can be controlled in a manner to reduce the effects of translations of the carrier in the radial direction.
Roll positioning is provided by a linear non-contacting roll torque motor which produces forces tangential to the rim.
Roll angle is determined from a linear sensor located along the periphery of the rim.
Also, roll could be controlled, in a fine pointing mode, from signals generated by a roll sensor on board the experiment package