A Generalized Flight Control Architecture for Transitioning Flight Vehicles with Flight Test Validation

Abstract

The focus of this dissertation is on the development of a full speed envelope flight control system for common urban air mobility vertical takeoff and landing vehicle configurations that incorporates simplified vehicle operation (SVO) principles. The key challenges include: (i) transitioning VTOL vehicles pose challenging flight control problems, (ii) multiple possible VTOL configurations with differing bare-airframe flight characteristics, and (iii) the SVO paradigm requires that, despite the complex configurations, pilot workload in flying them be substantially reduced, and control responses be standardized. The main configurations considered include lift-plus-cruise, vectored-thrust, and tilt-wing. The flight control system provides vertical takeoff and landing, short takeoff and landing, and conventional takeoff and landing capabilities for each configuration. The flight control system was verified and tested in simulation environments and through subscale flight tests. Flight simulations were be performed using the Modular Aircraft Dynamics and Control Algorithm Simulation Platform (MADCASP). The design of the flight control system ensures configuration-invariant responses involving a SVO-based inceptor mapping strategy. SVO guidelines drove the inceptor layout and cockpit display setup during flight testing. Autonomous flight capabilities were demonstrated, including autonomous takeoff, transition, navigation, and landing. These autonomous flight capabilities aim to reduce pilot workload, allowing pilots to offload some responsibilities to the auto-flight system while retaining manual control over other areas. The control system has been designed to include envelope protection to prevent unintended vehicle transitions and unintended exceedances. The flight control system was optimized across the speed envelope and employs a modern inner-loop control architecture. Handling qualities and robustness criteria were considered during the optimization to ensure adequate controller performance. To verify the simulation results, subscale test vehicles were flight-tested and used to demonstrate representative maneuvers. This dissertation provides a flight control system architecture that is applicable to a multitude of vehicle configurations with several configuration-independent components that are designed to be practical in their implementation. Flight testing is performed on three different VTOL configurations to verify the flight control system performance by the author, a minimally trained pilot.