A linear input-varying framework for modeling and control of morphing aircraft

Morphing, which changes the shape and configuration of an aircraft, is being adopted to expand mission capabilities of aircraft. The introduction of biological-inspired morphing is particularly attractive in that highly-agile birds present examples of desired shapes and configurations. A previous study adopted such morphing by designing a multiple-joint wing that represented the shoulder and elbow joints of a bird. The resulting variable-gull aircraft could rotate the wing section vertically at these joints to alter the flight dynamics. This paper extends that multiple-joint concept to allow a variable-sweep wing with independent inboard and outboard sections. The aircraft is designed and analyzed to demonstrate the range of flight dynamics which result from the morphing. In particular, the vehicle is shown to have enhanced crosswind rejection which is a certainly critical metric for the urban environments in which these aircraft are anticipated to operate.;Mission capability can be enabled by morphing an aircraft to optimize its aerodynamics and associated flight dynamics for each maneuver. Such optimization often consider the steady-state behavior of the configuration; however, the transient behavior must also be analyzed. In particular, the time-varying inertias have an effect on the flight dynamics that can adversely affect mission performance if not properly compensated. These inertia terms cause coupling between the longitudinal and lateral-directional dynamics even for maneuvers around trim. A simulation of a variable-sweep aircraft undergoing a symmetric morphing for an altitude change shows a noticeable lateral translation in the flight path because of the induced asymmetry.;The flight dynamics of morphing aircraft must be analyzed to ensure shape-changing trajectories have the desired characteristics. The tools for describing flight dynamics of fixed-geometry aircraft are not valid for time-varying systems such as morphing aircraft. This paper introduces a method to relate the flight dynamics of morphing aircraft by interpreting a time-varying eigenvector in terms of flight modes. The time-varying eigenvector is actually defined through a decomposition of the state-transition matrix and thus describes an entire response through a morphing trajectory. A variable-sweep aircraft is analyzed to demonstrate the information that is obtained through this method and how the flight dynamics are altered by the time-varying morphing.;Also, morphing vehicles have inherently time-varying dynamics due to the alteration of their configurations; consequently, the numerous techniques for analysis and control of time-invariant systems are inappropriate. Therefore, a control scheme is introduced that directly considers a concept of time-varying pole to command morphing. The resulting trajectory minimizing tracking error for either a state response or a pole response.