Gain-Scheduled H∞ Loop-Shaping Autopilot Design for Spin-Stabilized Canard-Guided Projectiles

This article is dedicated to the design of a complete guidance & control system for the roll/pitch/yaw-channels of a 155 mm dual-spin projectile equipped with nosemounted trajectory correction canards. The projectile airframe parameter-dependent nonlinear model including aerodynamic and actuator/sensor uncertainty descriptions is given and the subsequently computed linearized models necessary for autopilot design are presented. The pitch/yaw-channel dynamics linearized system is useful for highlighting important properties specific to these dynamics, in particular in relation with the parameter vector dimension and the sensor position. The computation of a linear structured controller for the nose roll-axis and of a gain-scheduled structured compensator for the airframe pitch/yaw-axes, using an H_∞ loop-shaping design approach, is detailed with the assessment of the obtained performance and robustness properties. Finally, various guided flight nonlinear 7DoF simulation results are exposed for the purpose of evaluating over the projectile flight envelope the effectiveness of the proposed guidance & control scheme.