Experimental modal identification of the Mini-Mast CSI testbed

The Mini-Mast is a 20 meter long, 3-dimensional, deployable/retractable truss structure designed to imitate future trusses in space. This structure has undergone various static and dynamic experiments at NASA Langley to identify its modal properties so that control laws can be developed and tested. This paper discusses a robust (with respect to measurement noise sensitivity), time domain, modal identification technique for identifying the modal properties of the Mini-Mast structure even in the face of noisy measurements. Two testing/analysis procedures are considered, they include: (1) sinusoidal excitation near the resonant frequencies of the Mini-Mast, and (2) frequency response function averaging of several modal tests. The modal identification results of these tests are compared with respect to basic filtering techniques and combining identification and state estimation algorithms.