Final Report.dvi

Tension-aligned structures have been proposed for space-based antenna applications. The structure uses a compression member to impart tension on the antenna, thus helping to maintain shape and facilitate disturbance rejection. These structures can be large and are therefore sensitive to low-frequency excitation. Three energy-based control strategies have been proposed for vibration suppression. The first strategy uses stiffness variation to funnel vibration energy from low-frequency modes to high-frequency modes of the structure, where it is dissipated naturally due to internal damping. The second control strategy uses a sliding mechanism to apply a moving constraint; the constraint force is measured in real time and is used to prescribe the motion of the slider. Energy of the structure is reduced continuously by doing negative work from the slider. The third strategy models the antenna as a thin plate and controls the tension on the boundary of the plate to suppress vibration. The Rayleigh-Ritz method was used to model the plate structure and an observer was used to estimate the modal amplitudes. For the second and third strategies, Lyapunov stability theory was used to show vibration suppression. Practical issues related to actuator bandwidth were also addressed.