Scheduling of local nonlinear control laws by exogenous signals—an application to flight control

Abstract

A new scheduling technique is presented for scheduling local nonlinear control laws. This leads to a new nonlinear design method for regulation of flight control systems. First, nonlinear feedback controls are designed using a nonlinear optimal control design method at a number of operating points (i.e. different Mach numbers). Then these nonlinear control laws are scheduled in a particular way according to the forward speed u. The resulting control law still takes the form of a static nonlinear control and is such that deviation in forward speed u (the scheduling variable) from the trim value does not affect control of the short period variables. This nice property can be retained over the entire flight envelope. The well-studied F-8 aircraft is used for this study. Computer simulations are given to show the effectiveness of this nonlinear control design method. Robustness to variations in system parameters is also studied by simulation.