Mixed H2/H Infinity Optimization with Multiple H Infinity Constraints
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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A general mixed H2Hoo optimal control design with multiple Hoo constraints is developed and applied to two systems, one SISO and the other MIMO. The SISO design model is normal acceleration command following for the F- 16. This design constitutes the validation for the numerical method, for which boundaries between the H2 design and the Hoo constraints arc shown. The MIMO design consists of a longitudinal aircraft plant short period and phugoid modes with stable weights on the H2 and Hoo transfer functions, and is linear- time-invariant. The controller order is reduced to that of the plant augmented with the H2 weights only. The technique allows singular, proper not necessarily strictly proper Hoo constraints. The analytical nature of the solution and a numerical approach for finding suboptimal controllers which are as close as desired to optimal is developed. The numerical method is based on the Davidon- Fletcher-Powell algorithm and uses analytical derivatives and central differences for the first order necessary conditions. The method is applied to a MIMO aircraft longitudinal control design to simultaneously achieve Nominal Performance at the output and Robust Stability at both the input and output of the plant.
- Flight Control and Instrumentation
- Operations Research