Extended nonlinear flight controller design for aircraft

In this paper, we consider the problem of control of a high performance aircraft at large angle of attack using a new method of scheduling local nonlinear control laws designed at different equilibrium points. This approach, referred to here as the extended nonlinear flight control (ENFC), extends the well-known concept of gain scheduling and the methods of extended linearization and pseudo-linearization. First, local nonlinear feedback controls are designed at a number of operating points, using a nonlinear optimal control design method. Then these local nonlinear control laws are scheduled using the proposed ENFC approach. The scheduled nonlinear control law is such that, at any equilibrium operating point, the Taylor-series-expansion of the control law matches exactly that of the local nonlinear control law designed for that operating point. Simulation results are presented to show the effectiveness of this design methodology.