Longitudinal autopilot design for agile turn using mixed H2 / H∞ control

In this paper, we propose a missile pitch autopilot design for a high angle-of-attack maneuver using multi-objective control via linear matrix inequality (LMI) approach. For 180° heading reversal maneuver for an agile missile after launch phase, angle-of-attack controller is considered to achieve a fast response. The proposed autopilot can satisfy the mixed H₂ / H_∞ performance conditions for multi-models that are derived from local linearization at different operating angle-of -attack points with a certain Mach number. Therefore, we can find one controller that can guarantee a tracking performance and robustness with respect to aerodynamic variation and uncertainty that occur during agile turn phase. To also compensate variation of Mach number, we use a set of controllers, each satisfying H₂ / H_∞ performance criteria and robustness for a specified operating Mach number, with a command blending method. Numerical simulation results show the validity of the proposed controller.