Design and flight test of a linear parameter varying flight controller

Abstract

AbstractFuture aircraft generations require improved performance and efficiency to enable a reduced environmental footprint. To acquire this goal, for example new material and wing concepts are perused at the moment by the aircraft industry. These developments, which include aspects such as over-actuation and lowly damped flexible modes, give rise to more complex, multi-objective control problems. One candidate method, which delivers a solution to these problems for the whole flight envelope, is linear parameter varying (LPV) control. It naturally incorporates the controller scheduling in the synthesis process, guarantees stability and robustness over the entire parameter envelope, and enables intuitive multi-objective, multiple-input multiple-output (MIMO) controller designs. This paper proves the concept of LPV control in practice: The paper presents and discusses the LPV controller design process, simulation results, motion simulator test and finally, the in-flight validation of the control system on a Cessna Citation II aircraft. The developed inner loop controller structures are inspired by classical flight controllers used on state-of-the-art fly-by-wire airliners. The longitudinal aircraft motion is augmented with load-factor command and the lateral motion controller features a roll rate command with attitude hold behavior. The control laws are validated in flight by automated and actual pilot inputs with respect to functionality, flying and handling qualities. Test results are encouraging with the provided key findings and lessons learned aiming to provide a simplification for future LPV flight controller development and testing campaigns.