Adaptive Observers for Structural Health Monitoring of High-Rate, Time-Varying Dynamic Systems

Safe and reliable operation of hypersonic aircraft, space structures, advanced weapon systems, and other high-rate dynamic systems depends on advances in state estimators and damage detection algorithms. High-rate dynamic systems have rapidly changing input forces, rate-dependent and time-varying structural parameters, and uncertainties in material and structural properties. While current structural health monitoring (SHM) techniques can assess damage on the order of seconds to minutes, complex high-rate structures require SHM methods that detect, locate, and quantify damage or changes in the structure's configuration on the microsecond timescale. This paper discusses the importance of microsecond structural health monitoring (mu SHM) and some of the challenges that occur in development and implementation. Two model-based parameter estimators are examined for estimating the states and parameters of an example time-varying system consisting of a two degree of freedom system with a sudden change in a stiffness value that simulates structural damage. The ability of these estimators to track this stiffness change, the role of measurement noise, and the need for persistent excitation are examined.