Shape memory alloys and fiber optics for flexible structure control

Abstract

This work investigates the development of Shape Memory Alloy (SMA) actuators and a fiber-optic Mach- Zehnder interferometric dynamic motion sensor as components of an active vibration control system. The test set-up consisted of a graphite-epoxy flexible cantilever beam with distributed SMA wires and optical fibers attached along both sides. A constant amplitude dead-band control algorithm was used to provide a rate feedback force to actively control transient vibrations. The SMA actuators were also used to demonstrate static shape control. The settling time of the beam was reduced by more than a factor of 24 through the use of the SMA actuators and fiber optic dynamic motion sensor. Analytical models were developed for the integrated structure/actuator/sensor system which helped understand the dynamic effects and the results correlated well with the experimental results. This investigation demonstrated the feasibility ofusing SMA actuators and fiber optic dynamic motion sensor for control of flexible structures. The work described in this paper was sponsored by the Astronautics Laboratory AL(AFSC) as a part of the Advanced Composites with Embedded Sensors and Actuators (ACESA) program.