Improved Control Authority in Flexible Structures Using Stiffness Variation

Abstract

Abstract : This research investigated control authority enhancement in structural systems through methodical stiffness variation. Our early work focused on stiffness variation in a cantilever beam under the application of a buckling-type end force and control designs based on switching of the end force. Towards the end of the project, our modeling, control, and experimental methods were extended to truss-like structures. An important extension of the work was tuning of beam-type MEMS resonators through stiffness variation generated by follower and axial end forces. In addition to structural control using end forces, switching strategies were developed for piezoelectric transducers to enhance controllability and observability of flexible structures. By switching the transducers between actuator and sensor modes, we demonstrated the possibility of reducing control system hardware. A significant portion of our effort focused on modal energy redistribution through stiffness variation with the objective of simplifying control design. The energy flow between modes in different stiffness states was quantified and validated through preliminary experiments.