Comparison of Flight Control System Design Methods Using the CONDUIT Design Tool

Optimization and comparison of several alternative control system design methods against a common extensive set of dynamics response criteria is demonstrated using the Control Designer’s UniŽ ed Interface (CONDUIT® ). The alternative methods considered are classical, linear quadratic regulator, dynamic inverse, and H-inŽ nity as applied to the design of lateral/directional control laws for a transport aircraft. From poor initial guesses for the design parameters of each alternative method, CONDUIT Ž rst achieved a feasible design space that satisŽ ed the stability and handling qualities to the best (level 1) criteria. Final controller tuning was accomplished to minimize the performance metrics of crossover frequency and actuator activity, while maintaining level 1 design criteria. An important Ž nding of this research is that the alternative design methods optimized against a common set of design requirements yield controllers whose performance and stability robustness characteristics are quite similar to one another. A stronger discriminator than design method is the controller architecture (one or two degree of freedom), which plays an important role in determining the achievable design space. This research demonstrates the feasibility andemphasizes the need to analyzeandoptimize prospective control designsagainsta comprehensive set of design requirements. CONDUIT has proven to be an especially effective environment for this task.