Gain-Scheduled Flight Controller Using Bounded Inexact Scheduling Parameters

Abstract

This brief designs gain-scheduled output-feedback (GSOF) model-matching controllers for the lateral-directional motions of an airplane. In our design, equivalent airspeed is used as the scheduling parameter, but its values are affected by measurement errors due to the location of the airplane's Pitot tube (so-called “position error”) and the finite resolution of the measurement system. Furthermore, the generalized plant for our problem has structured exogenous inputs and performance outputs to represent model-matching performance as well as actuator modeling errors. In order to accommodate these two different kinds of uncertainties, we propose a design method for GSOF controllers in which inexact but bounded scheduling parameters are supposed to be provided. We design two GSOF flight controllers: one using our proposed method, and the other using a conventional design method incorporating constant scaling matrices without consideration of the uncertainties in provided scheduling parameters. We demonstrate the effectiveness of our method by comparing the control performance of these two GSOF controllers in a posteriori analysis and in flight tests.