Design of altitude control loops relating to different autopilots for air-to-ground missiles' midcourse guidance

An altitude control loop based on the attitude autopilot inner loop was designed by using frequency method and root locus method. Also a comparing study was made between the altitude control system combined with attitude autopilot and the altitude control system combined with acceleration autopilot. The results indicate that the performance of these two altitude control systems is the same in essence. Then the effect of switching the autopilot inner loops on the transition from midcourse guidance to terminal guidance was analyzed. It is found that the effect is little, so it is feasible to switch the inner autopilots and the guidance loops simultaneously.