Controller Design for Unstable Aeroelastic Systems

摘要

The main objective of this research was the robust controller design for activeflutter suppression in the presence of time delays and neglected dynamics in the feed back loop. For this purpose we have developed an algorithm (and implemented on the computer) which derives a set of finitely many linear equations and computes the H-infinity optimal and suboptimal controllers for unstable systems with time delays. With this algorithm we can now compute the effect of time delays on the best achievable robustness and performance level in unstable aeroelastic systems. Moreover, all sub optimal H-infinity controllers are computed for a given system with time delay and dynamic uncertainty profile. Our algorithm determines the rational parts of suboptimal H-infinity controllers, such controllers contain an infinite dimensional fixed part which is the given time delay. Therefore, the controller is infinite dimensional. The problem of finding a finite dimensional suboptimal controller is also studied in this project. For the SISO case, it is shown that by approximating the infinite dimensional parts of the optimal controller (with certain interpolation constraints), a rational suboptimal controller can be obtained.