Optimal Terrain Following Controller for an Optimized Spline Reference Path
AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
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This thesis presents the design of a proposed terrain following flight controller capable of tracking a cubic spline reference path. The controller tracks only the longitudinal motion however, it provides both thrust and elevator control. The controller is based on a nonlinear reference model constructed from an optimized spline path. The spline path altitude and associated derivatives are computed. The longitudinal equations of motion are linearized about the reference trajectory and a truth model of actual aircraft motion is developed. Deviations from the nonlinear reference trajectory to the actual provide a linear system. Optimal control theory is used to solve the resulting linear regulator problem. The feedback gains are calculated from the steady-state Ricatti matrix equation. The two system controls are updated using these feedback gains. Results show the feedback controller to be stable and capable of tracking the cubic spline reference path. The performance index weighting matrices can be adjusted to improve the controller. The resulting controller can provide both good path control and engine control to improve vehicle survivability, engine life and fuel consumption.
- Attack and Fighter Aircraft
- Jet and Gas Turbine Engines