Optimization of control laws for damage detection in smart structures

摘要

A prevalient method of damage detection is based on identifying changes in modal characteristics due to damage induced variations in stiffness or mass along a structure. It is known that modal frequencies can be insensitive to damage, and the open-loop sensitivity itself depends on modal properties and damage location. Here, we develop methods of designing control laws that enhance the sensitivity of modal characteristics to damage. Sensitivity enhancing control exploits the relationship between control gains and closed-loop dynamics in order to increase the observability of damage. The design methods are based on optimization of cost functions that involve the dependence of classic measures of sensitivity on design variables, which include placement of sensors and actuators and state feedback control gains. Due to the size of the design space and the unknown nature of the ocst surface, genetic algorithms are used to find control laws designed for sensitivity enhancement of stiffness damage in a cantilevered beam are demonstrated by numerical simulation.