116 research outputs found
Powered-lift aircraft technology
Powered lift aircraft have the ability to vary the magnitude and direction of the force produced by the propulsion system so as to control the overall lift and streamwise force components of the aircraft, with the objective of enabling the aircraft to operate from minimum sized terminal sites. Power lift technology has contributed to the development of the jet lift Harrier and to the forth coming operational V-22 Tilt Rotor and the C-17 military transport. This technology will soon be expanded to include supersonic fighters with short takeoff and vertical landing capability, and will continue to be used for the development of short- and vertical-takeoff and landing transport. An overview of this field of aeronautical technology is provided for several types of powered lift aircraft. It focuses on the description of various powered lift concepts and their operational capability. Aspects of aerodynamics and flight controls pertinent to powered lift are also discussed
Four Tilting Rotor Convertible MAV: Modeling and Real-Time Hover Flight Control
International audienceThis paper describes the modeling, control and hardware implementation of an experimental tilt-rotor aircraft. This vehicle combines the high-speed cruise capabilities of a conventional airplane with the hovering capabilities of a helicopter by tilting their four rotors. Changing between cruise and hover flight modes in mid-air is referred to transition. Dynamic model of the vehicle is derived both for vertical and horizontal flight modes using Newtonian approach. Two nonlinear control strategies are presented and evaluated at simulation level to control, the vertical and horizontal flight dynamics of the vehicle in the longitudinal plane. An experimental prototype named Quad-plane was developed to perform the vertical flight. A low-cost DSP-based Embedded Flight Control System (EFCS) was designed and built to achieve autonomous attitude-stabilized flight
Neural-Networks Control for Hover to High-Speed-Level-Flight Transition of Ducted Fan UAV With Provable Stability
In this paper, we focus on the transition control of a ducted fan vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV). To achieve a steady transition from hover to high-speed flight, a neural-networks-based controller is proposed to learn the system dynamics and compensate for the tracking error between the aircraft dynamics and the desired dynamic performance. In prior, we derive the nonlinear system model of the aircraft full-envelope dynamics. Then, we propose a novel neural-networks-based control scheme and apply it on the underactuated aircraft system. Key features of the proposed controller consist of projection operator, state predictor and dynamic-formed adaptive input. It is proved and guaranteed that the tracking errors of both state predictor and neural-networks weights are upper bounded during the whole neural-networks learning procedure. The very adaptive input is formed into a dynamic structure that helps achieve a reliable fast convergence performance of the proposed controller, especially in high-frequency disturbance conditions. Consequently, the closed-loop system of the aircraft is able to track a certain trajectory with desired dynamic performance. Satisfactory results are obtained from both simulations and practical flight test in accomplishing the designed flight course
Nonlinear Control of Autonomous Flying Cars with Wings and Distributed Electric Propulsion
Hybrid vertical take-off and landing vehicles (VTOL) with lift production from wings and distributed propulsive system present unique control challenges. Existing methods tend to stitch and switch different controllers specially designed for fixed-wing aircraft or multicopters. In this paper, we present a unified framework for designing controllers for such winged VTOL vehicles that are commonly found in recent flying car models. The proposed method is broken down into nonlinear control of both position and attitude with forces and moments
as inputs, and real-time control allocation that integrates distributed propulsive actuation with conventional control surface deflection. We also present a strategy that avoids saturation of distributed propulsion control inputs. The effectiveness of the proposed framework is demonstrated through simulation and closed-loop flight experiment with our winged VTOL flying car prototype
Trajectory Generation and Tracking Control for Aggressive Tail-Sitter Flights
We address the theoretical and practical problems related to the trajectory
generation and tracking control of tail-sitter UAVs. Theoretically, we focus on
the differential flatness property with full exploitation of actual UAV
aerodynamic models, which lays a foundation for generating dynamically feasible
trajectory and achieving high-performance tracking control. We have found that
a tail-sitter is differentially flat with accurate aerodynamic models within
the entire flight envelope, by specifying coordinate flight condition and
choosing the vehicle position as the flat output. This fundamental property
allows us to fully exploit the high-fidelity aerodynamic models in the
trajectory planning and tracking control to achieve accurate tail-sitter
flights. Particularly, an optimization-based trajectory planner for
tail-sitters is proposed to design high-quality, smooth trajectories with
consideration of kinodynamic constraints, singularity-free constraints and
actuator saturation. The planned trajectory of flat output is transformed to
state trajectory in real-time with consideration of wind in environments. To
track the state trajectory, a global, singularity-free, and
minimally-parameterized on-manifold MPC is developed, which fully leverages the
accurate aerodynamic model to achieve high-accuracy trajectory tracking within
the whole flight envelope. The effectiveness of the proposed framework is
demonstrated through extensive real-world experiments in both indoor and
outdoor field tests, including agile SE(3) flight through consecutive narrow
windows requiring specific attitude and with speed up to 10m/s, typical
tail-sitter maneuvers (transition, level flight and loiter) with speed up to
20m/s, and extremely aggressive aerobatic maneuvers (Wingover, Loop, Vertical
Eight and Cuban Eight) with acceleration up to 2.5g
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