Gain-scheduled bank-to-turn autopilot design using linear parameter varying transformations

A gain-scheduled autopilot design for a bank-to-turn missile is presented. The approach follows previous work for a longitudinal missile autopilot. The method is novel in that the gain-scheduled design docs not involve linearizations about operating points. Instead, the missile dynamics are brought to a linear parameter varying form via a state transformation. A linear parameter varying system is defined as a linear system whose dynamics depend on an a priori unknown but measurable exogenous parameter. This framework is applied to the design of a coupled longitudinal/lateral bank-to-turn missile autopilot. The pitch and yaw/roll dynamics are separately transformed to linear parameter varying form, where the cross axis states are treated as exogenous parameters. These are actually endogenous variables, and so such a plant is called quasilinear parameter varying. Once in quasilinear parameter varying form, a family of robust controllers using μ synthesis is designed for both the pitch and yaw/roll channels, using angle of attack and roll rate as the scheduling variables. The closed-loop time response is simulated using the original nonlinear model and also using perturbed aerodynamic coefficients.