Studies in Dynamic Characterization and Control of a Flexible Structure and Optical Beampath
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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The dynamic characterization and control of a flexible structure and optical beampath is explored. The experiment is motivated by the expanding demand for structurally mounted space based laser pointing and tracking systems. The setup of the cantilevered UWAA planar truss is based on a similar setup at the Air Force Academy. An existing finite element model is modified to reflect the characteristics of the UWAA truss and experimentally validated. A reduced order truss model suitable for simulation is developed and validated with the hardware. The formulation of linear and non-linear models for the AJT and tilting mirror actuators are explored. The design and implementation of the mirror and structural control is manifested in the form of proportional-integral PI feedback to a tilting control mirror to actively reject line of sight disturbances and velocity feedback to on-off AJT actuators to supress large amplitude low frequency lateral structural vibrations. Good like of sight disturbance rejection is demonstrated for the first four lateral modes of the flexible truss structure. The AJT velocity feedback controller was used to supress large amplitude low frequency oscillations to bring structural vibrational motions to within limited range of the tilting mirror platform. A baseline theoretical model of the reduced order truss and control actuators was constructed in SIMULAB and thoroughly validated. The simulation model provides a theoretical basis for future work on the UWAA planar truss. Theoretical design and practical implementation issues are explored and future research possibilities suggested.
- Lasers and Masers