This paper presents the mathematical modeling, controller design, and flight-testing of an over-actuated Vertical Take-off and Landing (VTOL) tiltwing Unmanned Aerial Vehicle (UAV). Based on simplified aerodynamics and first-principles, a dynamical model of the UAV is developed which captures key aerodynamic effects including propeller slipstream on the wing and post-stall characteristics of the airfoils. The model-based steady-state flight envelope and the corresponding trim-actuation is analyzed and the overactuation of the UAV solved by optimizing for, e.g., power-optimal trims. The developed control system is composed of two controllers: First, a low-level attitude controller based on dynamic inversion and a daisy-chaining approach to handle allocation of redundant actuators. Secondly, a higher-level cruise controller to track a desired vertical velocity. It is based on a linearization of the system and look-up tables to determine the strong and nonlinear variation of the trims throughout the flight-envelope. We demonstrate the performance of the control-system for all flight phases (hover, transition, cruise) in extensive flight-tests.
Existing work on design, modeling and control of tiltwing UAV's considers tandem-wing @cite_5 @cite_7 @cite_8 and single-wing vehicles @cite_6 @cite_19 @cite_3 . Employed control systems are either unified @cite_19 @cite_3 or switch between different controllers for hover, transition, and cruise @cite_17 . For both attitude- and velocity control, decoupled PID and full state feedback LQR-architectures are reported @cite_7 @cite_13 @cite_3 . They are typically combined with local linearizations and gain-scheduling to address the strong non-linearities. Examples of @math -based attitude- and cruise control are found as well @cite_10 @cite_5 . A popular non-linear control technique involves DI @cite_4 and is used both for tailsitters @cite_18 @cite_24 and tandem TWV @cite_5 . It enables reference-model following but requires an accurate model to estimate state-dependent moments and forces. High-fidelity models are required to address the complex transition phase and typically consider the prominent propeller slipstream interaction with the wing @cite_13 . Instead of modeling, @cite_3 describes a control system that is based exclusively on state- and control derivatives obtained from wind-tunnel testing, @cite_24 and @cite_18 introduce lumped-parameter models to fit experimental data for a flying-wing tailsitter.
@cite_18 @cite_4 @cite_7 @cite_8 @cite_10 @cite_6 @cite_3 @cite_24 @cite_19 @cite_5 @cite_13 @cite_17
2413000173 2158337616 2099923336 2338554534
This paper addresses the challenges of the design, development and control of a new convertible VTOL tailsitter unmanned aerial vehicle that combines the advantages of both fixed wing and rotary wing systems. Wind tunnel measurements are used to get an understanding of the control allocation and to model the static forces and moments acting on the system. Based on the derived model, a novel controller that operates in SO(3) and handles the dynamics of the vehicle at any attitude configuration, including the rotorcraft and fixed-wing regimes as well as their transitions, is presented. This unified controller allows the autonomous transition of the system without discontinuities of switching, as well as its overall high performance flight control. The capabilities and flying qualities of the platform and the controller are demonstrated and evaluated by means of extensive experimental studies. This paper describes the development of robust, multi-variable H∞ control systems for the conversion of the High-Speed Autonomous Rotorcraft Vehicle (HARVee), an experimental tilt-wing aircraft. Tilt-wing rotorcraft combine the high-speed cruise capabilities of a conventional airplane with the hovering capabilities of a helicopter by rotating their wings at the fuselage. Changing between cruise and hover flight modes in mid-air is referred to as the conversion process, or simply conversion. A nonlinear aerodynamic model was previously developed that captures the unique dynamics of the tilt-wing aircraft. An H∞design methodology was used to develop cruise and hover control systems because it directly addresses multi-variable and robust design issues. The development of these control systems was governed not only by performance specifications at each particular operating point, but also by the unique requirements of a gain-scheduled conversion control system. The cruise and hover control designs form the basis for the conversion control system. The performance of the resulting conversion closed-loop systems is analyzed in the frequency and time domains. A tilt-wing rotorcraft Modeling, Simulation, Animation, and Real-Time Control (MoSART) software environment provides 3D visualization of the vehicle’s dynamics. The environment is useful for conceptualizing the natural rotorcraft dynamics and for gaining an intuitive understanding of the closed-loop system performance. This paper describes the development and analysis of gain-scheduled, multi-variable Hinfin control law for the conversion of a linear parameter varying (LPV) model of a high-speed autonomous rotorcraft vehicle (HARVee), an experimental tilt-wing aircraft. Tilt-wing aircraft combine the high-speed cruise capabilities of a conventional airplane with the vertical takeoff and station keeping abilities of a helicopter by rotating their wings at the fuselage. Changing between cruise and hover flight modes in mid-air is referred to as the conversion process, or simply conversion. A nonlinear aerodynamic model was previously developed that captures the unique dynamics of the tilt-wing aircraft. An Hinfin design methodology was used to develop linear controllers along various operating points of a conversion trajectory. The development of these control systems was governed not only by performance specifications at each particular operating point, but also by the unique requirements of a gain-scheduled conversion control system. The performance of the resulting conversion closed-loop systems is analyzed in the frequency and time domains. Performance robustness with respect to variation in the location of the center of gravity (eg) has been studied. The objective of this paper is to develop a vision-based navigation technique for micro aerial vehicles, quadrotor type, to operate in GPS-denied environment. The navigation method has been developed while using appearance-based Visual-Teach-and-Repeat (VT&R) technique. In a teaching phase, a quadrotor is manually navigated along a desired route to collect a set of reference images. In a repeating phase, the quadrotor is able to autonomously follow the desired route using these reference images. Self-localization is developed to determine the current segment of the desired route by a number of Speeded-Up Robust Features (SURF), matched between the current image and the reference images. In this paper, three methods of self-localization are proposed and compared. After performing self-localization, the quadrotor computes appearance-based motion control commands (desired yaw and height) for the next movement in order to keep track of the desired route. This computation is developed on Funnel Lane theory, which was originally proposed in Chen and Birchfield (IEEE Trans. Robot. 25(3), 749---754 (11)) for 2D navigation of a ground vehicle. The paper extends this theory to 3D navigation of a quadrotor.The proposed self-localization methods are tested with several image databases. Finally, an online experiment of proposed VT&R technique is demonstrated using Ar.Drone quadrotor model.