The Combined Effect of Missile IMU Shift, Model Following and Add-on SAC on the Autopilot Response

Proper location of the missile's inertial measurement unit renders the transfer function from the control surfaces to the acceleration measurement minimum-phase. Usually the poles and zeros of the missile actuators and rate gyros lie in the open left half plane. In this case the minimum-phase transfer function implies minimum-phase autopilot. Missile autopilots are designed to guarantee stability and performance throughout the flight envelope. The stability and performance are conflicting objectives. The final design is a compromise between stability margins and autopilot agility. In this paper the presented control architecture has the potential to resolve the conflict between robust stability and robust performance. The performance of the missile autopilot resulted from the combined effect of IMU location and reference model following can be further improved by using a simple Add-On adaptive control algorithm. The paper demonstrates the improved performance via example. The simple adaptive control (SAC) algorithm used in the paper involves the synthesis of parallel feedforward which guarantees that the controlled plant is almost strictly positive real (ASPR).