Fixed structure robust control design for the 155mm canard-guided projectile roll-channel autopilot

This article details a robust control procedure for the design of the roll-channel autopilot of a 155mm fin-guided projectile. A coaxial motor is used in order to control the roll rate and position of its nose throughout the flight. Both the nonlinear and linearized dynamics of the system are given and are also extended to take into account uncertainty into several of its parameters. For the design of the rate and position control loops a combined H_∞ disturbance rejection and model matching procedure is followed leading to 2DoF controllers of fixed structure. Results are compared to 1DoF as well as 2DoF full order H_∞ controllers. Finally the autopilot proposed is tested for robust stability using structured singular value analysis and implemented on a nonlinear projectile dynamics simulator. Extensive simulation results are given to demonstrate the effectiveness of the proposed solutions.