The effects of digital control on longitudinal autopilots for bank-to-turn and skid-turn missiles.

Abstract

This work addresses the design and analysis of the discrete longitudinal autopilot for application to the bank-to-turn (BTT) missiles. In the development the classical design and analysis were reviewed using the continuous uncoupled pitch channel autopilot for circular airframe. Then,applying analog-to-digital conversion, the corresponding discrete autopilot was designed. The performance of both continuous and discrete open loop systems was analyzed according to the desired requirements. In the following section, utilizing modern control design techniques for the discrete pitch channel autopilot, the control law was designed, assuming availability of all the states and taking the desired poles to be at the same place as in the classical design. Therefore the discrete state-feedback autopilot was obtained and analyzed. The next step was the design of an estimator which estimates the entire state vector, given measurements of the portion of the state. The performance of the estimator was analyzed too. Finally coupling the discrete pitch and roll channel autopilots the overall performance of the discrete system was obtained and analyzed. The resulting design was also proved to be robust.