Photostrictive actuator, which can turn light energy into mechanical energy, is a new promising photoactuation technique for non-contact wireless active control of flexible structures. Optical mirrors, communication antennas, solar/optical reflectors, nozzles, rocket fairings, etc. often have the shape of parabolic shells or shells of revolution, due to their required focusing, aiming, or reflecting performance. In this paper, the active control of flexible parabolic shells using discrete photostrictive actuators is investigated. Parabolic shell of revolution is considered one of the most difficult geometry among all shell and non-shell structures. Because of this, an approximate way to estimate the dynamic behavior and light-induced control forces of a photostrictive coupled parabolic shell is presented. Based on the approximate model, the effects of actuator locations as well as membrane and bending components on the control action are analyzed. The results obtained indicate that the control forces are mode and location dependent. It is also shown by analysis that the membrane control action is much more significant than the bending control action. The validation of the approximate model is done by comparing the light-induced control forces of the photostrictive coupled shells obtained by the approximate equivalent spherical shell model and those obtained by the parabolic shell model.
Optimal sensor location and reduced order observer design for distributed process systems
