Soft Controller Switching with Guaranteed H∞ Performance

Abstract Two methods for soft controller switching are introduced. They both treat static output-feedback control and achieve a prescribed bound on the L2 -gain of the closed-loop over the entire uncertainty range. This L2 -gain can then be used to guarantee tracking performance, disturbance rejection, and stability margins over the entire uncertainty range. The soft switching is performed by continuously changing the controller gain from one of the controllers to a second one over the switching interval. The first method treats the case where the gain may follow any continuous trajectory during the switching interval. The second method treats the case where the soft switching is performed by a linear interpolation between the two control gains over the switching interval. The designer may choose to prescribe any, all or none of the controllers gains. The problem is then formulated as a set of linear matrix inequalities. The conditions are applied to a z-axis control of a quadcopter.