Uncertainty Set, Design and Performance Evaluation of Centralized Controllers for AMB System

In this paper an industrially recognized modal control approach, a linear-quadratic-Gaussian (LQG) control, and an H8 control designs are compared using automated weights tuning based on a genetic algorithm. The robust stability analysis is carried out based on the uncertainty set, which comprises parametric and nonparametric uncertainties. The uncertainty set is updated to be compliant with the measured frequency responses of the test rig. The studied combination of the uncertainties proves too conservative for the direct application in the H8 control synthesis. However, a robust stability of the controllers synthesized using the nominal plant can be verified using µ-analysis and the very uncertainty set that cannot be used for the controller design directly. It is demonstrated that for the rigid rotor without strong gyroscopic coupling all of the control approaches result in a similar performance. For the more slender rotor with an additional disc and the dynamics dependent on the rotational speed the best results are achieved by the LQG and H8 controllers. When no gain scheduling is applied, the modal control results in the unstable system.