New Method Determines Optimized Reference SDM for MIMO Testing
The paper presents a new method for vibration testing of articles such as satellites, aerospace subsystems, transportation subsystems, civil structures, or articles whose reliability in operation may be evaluated using either mechanical or acoustic vibration testing. The method can be used for direct field or reverberant acoustic test facility testing (acoustic) systems or multiple-exciter (mechanical) testing systems to perform vibration testing. The method improves the ability of Multiple-Input-Multiple-Output (MIMO) acoustic testing systems to create diffuse or other types of acoustic fields and MIMO mechanical testing systems to produce vibration responses conforming to an initial reference Spectral Density Matrix (SDM) specification in the least mean-square error (LMSE) sense. It provides an updated positive definite or semi-definite reference SDM that enables such tests to run with less error, using minimum required drive power, as a function of the initial definition of the reference SDM, by modifying its coherence and phase off-diagonal terms, to approximate initially defined off-diagonal terms in the LMSE sense, but maintaining its initially defined diagonal terms exactly, while accounting for physical limitations existing in the overall MIMO testing system.Abstract
Contributor Notes
Biography:
Marcos A. Underwood has a Ph.D. in Electrical Engineering, with specialization in control and communication systems, and a Masters in Mathematics, both from the University of California in Los Angeles. He also has a Masters in Structural Engineering from San Jose State University. His Bachelors, in Mathematics and Physics, is from the California State University in Los Angeles. Dr. Underwood worked with Philco-Ford Aeronutronic, Rockwell International Space Div. on the Space Shuttle project, and Hughes Helicopters on Structural Dynamics and Acoustics, early in his career, developing the use of digital vibration and acoustic control and analysis systems. Later, he also worked with SD, GenRad, STI, and again with SD as their systems architect, designer of their vibration and acoustic control and analysis systems over the years. Afterwards, he held the positions Chief Engineer, V.P of Engineering, and Chief Scientist at STI and SD. During the three phases, he developed some of the fundamental digital technology now used for vibration and acoustic control and analysis. He has been involved in the use, design, and development of digital control and analysis systems for vibration and acoustics for almost 50 years and holds many key patents in the field. He has authored many publications, is a Fellow of the IEST, and the chair of the recommended practices IEST-RP-DTE 022 working group committee on Multi-Shaker Testing and Control. He currently works, from his consulting firm Tu’tuli Enterprises, with MSI DFAT as their Chief Scientist.
Contact: Marcos A. Underwood, Ph.D., dr.marcos.a@icloud.com, Tu’tuli Enterprises, 33741 S. Highway 1, Gualala, CA, 95445, USA