Fixed structure ℋ∞ Control for a canard-guided projectile pitch/yaw dynamics autopilot design

This article deals with the design of the pitch/yaw-channels autopilot for a 155mm dual-spin canard-guided projectile at one single operating point, using a signal-based ℋ_∞ control method. The proposed concept is composed of a course correction fuse which incorporates the trajectory correction modules and two pairs of rotating canards. This fuse is nose-mounted and roll-decoupled from the aft part which contains the payload and is rapidly-spinning in order to provide the projectile airframe with gyroscopic dynamic stability. Complete and exact nonlinear and linearized dynamics are given and extended to consider parametric uncertainties. A 1DoF ℋ_∞ controller of fixed order and fixed structure is synthesized, for which the actual sensor position is taken into account, closed-loop performance is optimized and the lowest possible complexity is sought. This controller is then compared to a 1DoF full order ℋ_∞ controller. Finally, robust stability is assessed using structured singular value and Monte Carlo analyses.