Sensor position influence on modeling and control of 155mm canard-guided spin-stabilized projectiles

This article explores in detail the influence of the sensor position on the pitch/yaw dynamics modeling and on the autopilot design and performance for a 155mm canard-guided spin-stabilized projectile which incorporates a nose-mounted course correction fuse (CCF) for trajectory correction. A complete and exact nonlinear model is given and used for computing a q-LPV model necessary for the controller synthesis. Using this linearized model, the influence of the sensor position on the load factor-related open-loop dynamics is highlighted. The H_∞ loop-shaping design approach, which permits to obtain a high-performance, robust, fixed structure and fixed order controller for any operating point, is presented. The necessity, for the controller synthesis, of considering the actual sensor position in the projectile nose and of calculating the load factor feedback signals at the center of gravity (CG) using the load factors actually measured at the CCF, in order to cope with this important practical constraint, is demonstrated.