| Resumo : |
The design of flight control laws for a commercial aircraft must guarantee that aeroservoelastic interactions do not hinder performance and continued safe flight in a closed-loop system. Traditionally, notch filters are employed to attenuate the influence of structural dynamics on the flight control system. However, filters add phase lag, degrading performance, making the gain tuning process iterative and expensive, until the desired performance is achieved. Furthermore, the delays caused by the filters can lead to pilot induced oscillations (PIO). This dissertation aims to propose and evaluate a methodology for designing integrated control laws, based on a flight dynamics model that includes the structural dynamics - flight dynamics of flexible aircraft. This way the methodology allows the design to include the influence of such modes in the control laws, achieving closed-loop aeroelastic stability without the inclusion of notch filters. Two different strategies, with feedback of modal variables and measured signals, are compared to the traditional filtered design, in terms of stability margins and handling qualities. At the end of this work, the difficulties found are discussed, along with the necessary modifications required for current commercial aircraft so that the presented integrated control law could be implemented. |