Hierarchical switching for active disturbance attenuation with fine controller tuning

In this paper, a novel adaptive disturbance attenuation algorithm is proposed combining switching and tuning. A two-level hierarchical switching logic is developed, which first selects in a short time the potentially best controller among a finite pre-designed family and then performs a local refinement of its attenuation capability. Thanks to the controller fine tuning, the proposed technique is able to provide a substantial performance improvement in terms of attenuation level as compared with a pure adaptive switching control scheme; at the same time, it retains the positive features of switching-based approaches, in particular, concerning the possibility of rapidly achieving a satisfactory behavior. Further, an arbitrary attenuation level is ensured in the presence of particular classes of disturbances and provided that it is compatible with robust stability requirement. Simulation results are shown to underline the potential of the approach as a solution to the problem.