ANDECS-MULTICRITERIA OPTIMIZATION OF A FUZZY-LOGIC CONTROLLER FOR AN AERODYNAMICALLY UNSTABLE AIRCRAFT IN COMPARISON TO A LINEAR ROBUST CONTROL DESIGN

Abstract The performance benefits of an aerodynamically unstable aircraft are obtained at the expense of the necessity of an automatic control system. For reliability requirements controllers without gain scheduling are looked for. To achieve this a complex ”robust control” design problem has to be solved. Fuzzy-controllers are claimed to have robustness properties. On the other hand the fuzzy-control methodology can be seen as a systematic way to specify controllers with nonlinear gain surfaces. To properly tune such controllers, computer-aided techniques can be applied provided appropriate models are available such as in more classical design approaches. A fuzzy-controller is developed, which keeps an aerodynamically unstable aircraft stationary for a sufficient long range of time and providing good flying qualities over the entire flight envelope. The results are compared with a completely linear controller design, done earlier.