In the presence of frequent inlet flow upsets, tuning of averaging level controllers is typically quite complicated since not only the size of the individual steps but also the time in between the subsequent steps need to considered. One structured way to achieve optimal filtering for such a case is to use Robust Model Predictive Control. The robust MPC controller is, however, quite computationally demanding and not easy to implement. In this paper two linear controllers, which mimic the behavior of the robust MPC are proposed. Tuning guidelines to avoid violation of the tank level constraints as well as to achieve optimal filtering are presented. Abstract: In the presence of frequent inlet flow upsets, tuning of averaging level controllers is typically quite complicated since not only the size of the individual steps but also the time in between the subsequent steps need to considered. One structured way to achieve optimal filtering for such a case is to use Robust Model Predictive Control. The robust MPC controller is, however, quite computationally demanding and not easy to implement. In this paper two linear controllers, which mimic the behavior of the robust MPC are proposed. Tuning guidelines to avoid violation of the tank level constraints as well as to achieve optimal filtering are presented.

This paper is the result of a Master Thesis project performed at Saab AB. The main goal of the project was to design and implement a discrete time L 1 adaptive backup controller in pitch to increase performance for an agile fighter aircraft. A lateral controller was also developed as a secondary goal. A discrete time version of the Modified Piecewise Constant L 1 adaptive control formulation was implemented. Results have shown that augmenting a state-feedback controller with an L 1 adaptive controller increases robustness in the whole flying envelope, with satisfactory flying qualities. A switching scheme between two L 1 controllers based on the extension of the landing gear was used to improve the controller performance throughout the whole envelope. The implemented controllers were flown in a simulator with a nonlinear generic fighter aircraft model with promising results.