AAS 96-132

IDENTIFICATION OF SHUTTLE/MIR STRUCTURAL DYNAMICS FOR FLIGHT CONTROL NOTCH FILTERING TUNING

M. Jackson, Charles Stark Draper Laboratory

Abstract

The Space Shuttle Flight Control System includes notch filters in the feedback path to attenuate flexible dynamics and maintain control system stability. An in-flight experiment was conducted on the first Shuttle/Mir docking mission to gauge the accuracy of structural models so that redesigned notch filters could be up-linked if required. Filter design techniques are discussed to highlight tradeoffs between stability robustness and fuel performance. The structural frequency identification process used on STS-71 is covered to show how notch filters can be redesigned in near real-time to reduce conservatism or to correct potential stability problems.