Vertical speed command performance improvement of a load factor command based autopilot for automatic landing by shaping the desired command during flare

In this paper the design methods for a flare controller for a general aviation aircraft Diamond DA42 are presented. The flare maneuver utilizes an existing vertical speed command controller, but increases its performance by applying a command filter as well as an additional feed forward command. The approach ensures a significant reduction of the system's rise time by approximately 45% and therefore a better tracking performance in respect to a desired continuous vertical speed command during flare. The advantage of modifying the command input is that the original vertical speed controller is not changed and verification and validation processes have not to be repeated for the existing system. The design process presented in this paper covers the design of a linear vertical speed command filter as well as an additional corresponding feed forward command.