Analysis and Design of a Digital Controller for a Seismically Stable Platform.

摘要

The Seismically Stable Platform (SSP) at the Central Inertial Guidance Facility, Holloman AFB, is a dual reactionary mass isolation platform designed to remove .00000001 g RMS/Hz accelerations and + or - 0.02 arcseconds angular position or tilt disturbances in all axes from a test environment intended for evaluating 'Third Generation Gyro' inertial instruments. Disturbances are removed by two stages of pneumatic isolators comprising a passive isolation system and augmented by an active control system to cover the operational bandwidth from .00000001 Hz to 100 Hz. A dynamic model of the SSP confirmed the passive vibration transmissibilities and identified severe limitations on gain and phase margin to the active controller design. The proposed digital controllers identified the SSP to be weakly controllable. The discrete state representation of the SSP and control law exhibited numerical difficulties detrimental to system stability. This study recommends single stage pneumatic isolation or fluid isolators monitored by disturbance parameter estimation schemes. (Author)