will require materials and devices that can control smaller vehicles without using hydraulic systems. Smart structures technologies, such as piezoelectrics and neural networks, can improve load and health monitoring capabilities, as well as alleviate dynamic loads (Geng et al., 1994; Kim and Stubbs, 1995). Neural networks can potentially monitor many locations on an aircraft and reduce the number of sensors required. Piezoelectric-based health monitoring systems have been demonstrated in the laboratory for integrated damage detection of both metallic and composite structures (Lichtenwalner et al., 1997).
Along with a mix of sensors (e.g., accelerometers; pressure transducers; or piezoelectric sensors, actuators, or strain gages) that can sense the environment and determine desired vehicle response, an ideal system would be able to locate and assess damage rapidly on the ground or in the air.
Recommendation. The U.S. Air Force should develop improved health monitoring technologies that take advantage of recent advances in sensors, controls, and computational capabilities. Specific opportunities include the following:
MEMS and mesoscale technologies for integrated sensor-actuationcontrol devices
improved load and condition-monitoring capabilities that use piezoelectric sensors and neural networks for data analysis
active flutter suppression and buffet load suppression systems that link condition-monitoring capabilities with piezoelectric transducers/actuators and intelligent controls