Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Richard G. Cobb, PhD.


Control of structural vibrations has been a popular topic. Use of MFC piezoelectric actuators and co-located sensors allows for an active rather than passive control method. The F-16 ventral fin is susceptible to buffet induced vibrations and is a perfect test structure for active vibration control for flight-testing. The research follows the previous ACTIVE FIN project and improves on the design by increasing the number of actuator layers, available actuator power, and using multi-input multi-output (MIMO) control algorithms. The research involved experimental identification of the ventral fin and its principle strain directions, selection of system components, determination of mathematical plant model, and design and test of control algorithms. The research resulted in a control system suitable for flight, a practical controller design process, and comparisons of different control algorithms to include single-input single-output (SISO) positive position feedback (PPF), multivariable PPF, two-input two-output linear quadratic Gaussian (LQG), and two-input fouroutput LQG. Controller effectiveness on target modes, actuator power consumption, and controller robustness were tested in the laboratory. The laboratory results showed that reductions of 7.4 dB, 17.7 dB, 15.7 dB and 3.2 dB in modes one, two, three, and four respectively were achieved using the MIMO LQG controller while maintaining sufficient gain and phase margins.

AFIT Designator


DTIC Accession Number