A Benchmark Problem for Development of Autonomous Structural Modal Indentification

This paper summarizes modal identification results obtained using an autonomous version of the Eigensystem Realization algorithm on a dynamically complex, laboratory structure. The benchmark problem uses 48 of 768 free-decay responses measured in a complete modal survey test. The true modal parameters of the structure are well known from two previous, independent investigations. Without user involvement, the autonomous data analysis identified 24 to 33 structural modes with good to excellent accuracy in 62 seconds of CPU time (on a DEC alpha 4000 computer). The modal identification technique described in the paper is the baseline algorithm for NASA''s Autonomous Dynamics Determination (ADD) experiment scheduled to fly on International Space Station assembly flights in 1997-1999.