Flight Control Architecture of a Flying Wing for Vertical Take-Off and Landing of an Airborne Wind Energy System

Fuest, H.; Duda, D.; Islam, Tobias; Moormann, Dieter

doi:10.2514/6.2021-1816

Cited by 3 publications

(4 citation statements)

References 6 publications

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“…In doing so, the nonlinear model is linearized at each trim point and an LQRcontroller is set up that allows to command the velocities of the flight system to follow the given path. We consider within this scope an attitude controlled system, consisting of a cascaded INDI and LQR controller that enables an holistic control of the attitude in all ranges from hover to forward flight, as described in [19,21]. The inputs for the attitude controlled system are thrust (f ) command and the attitude commands in form of quaternions.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…A loss of tether tension corresponds to the loss of controllability during hover, while the tether connection limits control authority during crosswind flight. An active system on the other hand with a variable tether connection point allows to place the tether's point of attack with a desired lever arm to the center of gravity to reset the moment [19]. This however requires a highfrequency motion of the tether's connection point to account for a dynamic wind field and is dependent on a stretched tether connection as well.…”

Section: Starting Procedures Of the Flying Wing For An Airborne Wind ...mentioning

confidence: 99%

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Flight Path and Flight Dynamic Analysis of the Starting Procedure of a Flying Wing for an Airborne Wind Energy System

Fuest,

Duda,

Islam

et al. 2024

Preprint

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Airborne Wind Energy is an emerging technology that harvests wind energy with flight systems connected via a tether to a generator at the ground. A flying wing promises a high energy output during the power generation phase due to its aerodynamic efficiency, while being able to take-off as a tailsitter. Yet not part of the generation phase, the starting procedure raises main challenges to the flight system in general but especially to a flying wing. A fast transition from hover to crosswind flight is striven under minimal power consumption and high wind robustness, while considering the limited trim range of the flying wing in hover state. This paper conducts a detailed analysis of the stationary trim states of the flying wing from thrust-borne to wing-borne flight and introduces a lateral yaw-roll transition to keep the angle of attack in controllable limits at all times. Based on the trim states, different options for the starting procedure are evaluated and an appropriate path is selected that entails a straight-lined transition segment to enter forward flight, followed by curved flight to built up tether tension and to navigate into the power-generation zone. The first part of this transition from hover to horizontal forward flight is demonstrated in the simulation to verify the selected flight path.

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Section: Simulation Resultsmentioning

confidence: 99%

Section: Starting Procedures Of the Flying Wing For An Airborne Wind ...mentioning

confidence: 99%

Flight Path and Flight Dynamic Analysis of the Starting Procedure of a Flying Wing for an Airborne Wind Energy System

Fuest,

Duda,

Islam

et al. 2024

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…This allows a trimmed flight state for all horizontal and upward velocities up to the thrust limit. A further discussion of the trim states of the tethered VTOL as function of the wind velocity and the tether attachment point is given in [13].…”

Section: Discussionmentioning

confidence: 99%

“…It can be noted that alternative flight paths like rotating the flight system with span width in wind direction to reduce the induced pitch moment can be investigated as well. Besides, a corresponding trim tether force corresponding to certain wind velocities can be examined in a further analysis [13].…”

Section: Modifications To Adjust the Flight Envelopementioning

confidence: 99%

Stabilization of the vertical take-off of a rigid flying wing for an airborne wind energy system

et al. 2021

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Airborne wind energy is an emerging technology that harvests wind energy with flight systems connected via a tether to the ground. In the project “EnerGlider”, a flying wing is meant to fly fully automated by its own control units. This contribution discusses the challenges to control and trim this flying wing during vertical take-off and landing under the influence of a horizontal wind velocity. High wind velocities can lead to unstable and untrimmed states concerning the longitudinal motion of the flying wing. The paper analyzes the influence of design modifications of thrust vector and elevon area to enhance the flight envelope of the trimmed states to higher wind velocities. Besides, the tether force as additional control unit is considered for strong wind forces. It is demonstrated that a tether force acting behind the center of gravity can significantly enhance the robustness of the flight system concerning wind velocity. Moreover, the unstable flight states emerging during vertical take-off and landing can be stabilized with a flight control.

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Robust Stability and Performance Analysis of Incremental Dynamic-Inversion-Based Flight Control Laws

Pollack

Kampen

2023

Journal of Guidance, Control, and Dynamics

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Incremental nonlinear dynamic inversion (INDI) is a sensor-based control law design strategy that is based on the principles of feedback linearization. Contrary to its nonincremental counterpart (nonlinear dynamic inversion), this design method does not require a complete onboard model of the airframe dynamics and is therefore more robust against regular perturbations arising from aerodynamic variations. Therefore, INDI brings a natural design approach to desirable flying qualities. However, robustness against singular perturbations, which may arise due to transport delays, elastic airframe effects, or other types of badly modeled or unknown dynamics, is a known challenge for INDI-based control laws. Therefore, this paper addresses the question of robust stability and performance for INDI and its linear form (incremental dynamic inversion [IDI]) in the context of mixed regular and singular perturbations. This is done through analytical insights and by performing quantitative robustness assessments based on the structured singular value framework. Additionally, inversion loop augmentation solutions are investigated using robust synthesis techniques to improve the robustness characteristics of basic IDI designs.

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Flight Control Architecture of a Flying Wing for Vertical Take-Off and Landing of an Airborne Wind Energy System

Cited by 3 publications

References 6 publications

Flight Path and Flight Dynamic Analysis of the Starting Procedure of a Flying Wing for an Airborne Wind Energy System

Flight Path and Flight Dynamic Analysis of the Starting Procedure of a Flying Wing for an Airborne Wind Energy System

Stabilization of the vertical take-off of a rigid flying wing for an airborne wind energy system

Robust Stability and Performance Analysis of Incremental Dynamic-Inversion-Based Flight Control Laws

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