THREE-AXIS PEDESTAL HAVING MOTION PLATFORM AND PIGGY BACK ASSEMBLIES

摘要

A rotationally-stabilizing tracking antenna system suitable for mounting on a moving structure includes a three-axis pedestal for supporting an antenna about a first azimuth axis, a second cross-level axis, and a third elevation axis, a three-axis drive assembly for rotating a vertical support assembly relative to a base assembly about the first azimuth axis, a cross-level driver for pivoting a cross-level frame assembly relative to the vertical support assembly about the second cross-level axis, and an elevation driver for pivoting an elevation frame assembly relative to the cross-level frame assembly about the third elevation axis, a motion platform assembly affixed to and movable with the elevation frame assembly, three orthogonally mounted angular rate sensors disposed on the motion platform assembly for sensing motion about predetermined X, Y and Z axis of the elevation frame assembly, a three-axis gravity accelerometer mounted on the motion platform assembly and configured to determine a true-gravity zero reference, and a control unit for determining the actual position of elevation frame assembly based upon the sensed motion about said predetermined X, Y, and Z axes and said true-gravity zero reference, and for controlling the azimuth, cross-level and elevation drivers to position the elevation frame assembly in a desired position. Instead of or in addition to the motion platform assembly, the antenna system may include primary and secondary antenna affixed relative to the cross-level frame assembly and a control unit for selecting operation of a selected on of the primary and secondary antennas, determining the actual position of elevation frame assembly based upon the sensed motion about said predetermined X, Y, and Z axes, and for controlling the azimuth, cross-level and elevation drivers to position the selected one of the primary and secondary antennas in a desired position for tracking a communications satellite, Methods of using the three-axis pedestal having motion platform assembly is also described.