Robust Linear-Parameter Varying Autopilot Design for a Tail/Thrust Vector Controlled Missile

Abstract

A robust autopilot design methodology using linear parameter varying transformations is presented and applied to a high-agile surface launched air defence missile, which is currently developed by Diehl-BGT-Defence. The lateral dynamics of the tail/thrust vector controlled missile are modelled as a second-order quasi-linear parameter varying (LPV) system. The incidence angle is used as exogenous variable, which is assumed to be estimated during missile flight. Decoupled lateral dynamics are assumed because of the application of a bank-to-turn manoeuvre plane angle control approach. Lateral single channel flight controllers are designed via H_∞-optimal control and μ-synthesis with the LPV lateral dynamics, which are extended by uncertain models of control actuating system, time-delay and body bending model. The flight controllers for lateral dynamics are designed at a number of operating points described by the LPV model over the MACH flight envelope. The controllers are implemented using a gain scheduling approach, where an altitude dependent gain loss in the control loop is compensated with the inverse normalised air density. The flight controllers were implemented in the nonlinear simulation environment and tested in extreme flight manoeuvres. All flight controllers showed good damping and acceleration tracking performance and were stable during nonlinear simulations.