Flight testing of low-order anti-windup compensators for improved handling and PIO suppression

This paper presents the results of recent flight tests of several anti-windup (AW) compensators on the German Aerospace Centre´s (DLR) Advanced Technologies Testing Aircraft (ATTAS). The objectives of the tests were twofold: to demonstrate the potential for rigorously designed low order AW compensators to reduce the pilot-involved-oscillation (PIO) proneness of the aircraft and improve the handling qualities; and to compare a variety of low-order AW compensators to determine the importance of different design parameters. The AW compensators were assessed based on pilot handling qualities ratings (HQRs) and PIO ratings (PIORs). These ratings, and supporting pilot comments and flight data, demonstrate that the AW compensators improved the handling qualities and reduced the PIO proneness of the aircraft, albeit to different degrees. The results also provide a basic understanding of the relationship between design parameters and the response of the piloted aircraft during periods of rate saturation.