THREE-AXIS PEDESTAL HAVING MOTION PLATFORM AND PIGGY BACK ASSEMBLIES

A rotationally-stabilizing tracking antenna system includes a three-axis pedestal, a drive assembly rotating a vertical support assembly relative to a base assembly, a cross-level driver pivoting a cross-level frame assembly relative to the vertical support assembly, and an elevation driver pivoting an elevation frame assembly relative to the cross-level frame assembly, a motion platform assembly affixed to the elevation frame assembly, three orthogonally mounted angular rate sensors disposed on the motion platform assembly sensing motion about X, Y and Z axes, a three-axis gravity accelerometer mounted on the motion platform assembly to determine a true-gravity zero reference, and a control unit determining the actual position of elevation frame assembly based upon sensed motion about X, Y, and Z axes and the true-gravity zero reference, and controlling the azimuth, cross-level and elevation drivers to position the elevation frame assembly in a desired position.