A multidisciplinary flight control development environment and its application to a helicopter

CONDUIT, a computational facility for aircraft flight control design and evaluation, has been developed and demonstrated. CONDUIT offers a graphical environment for integrating simulation models and control law architectures with design specifications and constraints. This tool provides comprehensive analysis support and design guidance to a knowledgeable control system designer. Combining the easy-to-use graphical interface, the preprogrammed libraries of specifications, and the multiobjective function optimization engine (CONSOL-OPTCAD) in a single environment, CONDUIT offers the potential for significant reduction in time and cost of design, analysis, and flight-test optimization of modern flight control systems. A case study application to a complex rotary-wing flight control problem was presented. The baseline RASCAL UH-60 control system, as provided by the flight control contractor, was evaluated versus the ADS-33D handling-quality specifications. The selectable system gains were optimized to meet all system performance and handling-quality specifications. CONDUIT successfully exploited the tradeoff between forward loop and feedback dynamics to significantly improve the expected handling qualities and stability robustness, while reducing crossover frequency and minimizing actuator activity. The tradeoff studies showed the effect of increasing design margin (overdesign) on closed loop performance and actuator activity. Design margins exceeding 7.5% led to rapidly increasing actuator energy and saturation, resulting in shortened fatigue life of rotor control.