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Miniaturization and control of an Unmanned Tiltwing Aircraft

无人系统（英文） 2024年第3期12卷 599-609页

作者： Julian Müller Dieter Moormann Institute of Flight System Dynamics RWTH Aachen University Westfälische 752062 AachenGermany

The objective of this paper is to describe the miniaturization and control of an unmanned tiltwing *** geometric miniaturization and mechanical realization,a lightweight design based on carbon fiber tubes,polystyrene rigid foam and 3D-printed parts is *** attitude controller is adopted from an existing full-scale unmanned tiltwing aircraft and follows the control strategy of Incremental Nonlinear Dynamic Inversion(INDI).The effects of the miniaturization,including low mass inertia combined with comparatively large aerodynamic surfaces,require a re-evaluation of INDI-based *** to the aircraft's rear-positioned center of gravity,the modeled control ability of the main motors is adapted and explicitly considered in the controller *** integrity of both,construction and controller,is validated in simulations and flight tests.

关键词： Miniaturization tiltwing INDI

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Starting procedure of a flying wing for an airborne wind energy system

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CEAS Aeronautical Journal 2025年第1期16卷 307-321页

作者： Fuest, Hendrik Duda, Dominik F. Islam, Tobias Moormann, Dieter Institute of Flight System Dynamics RWTH Aachen University Wüllnerstraße 7 NRW Aachen52062 Germany

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. Besides, the flying wing can take off vertically in a tailsitter configuration for operation within a limited space. 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 required under minimal power consumption and high wind robustness, while considering the tether connection and the limited flight envelope of the flying wing in hover state. This paper conducts a detailed analysis of the stationary trim states of the flying wing during the transition and introduces a lateral yaw-roll transition to allow for a flight within the flight envelope in both high and low wind conditions. 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 build 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. © The Author(s) 2025.

关键词： flight envelopes

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Investigation of the influence of rain on pitot-static measuring systems of unmanned aerial vehicles

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CEAS Aeronautical Journal 2025年第1期16卷 185-195页

作者： Tilmans, Jan Jackisch, Sven Moormann, Dieter Institute of Flight System Dynamics RWTH Aachen University Wüllnerstraße 7 NRW Aachen52056 Germany

For unmanned aerial systems with a maximum take-off mass of up to 25 kg, simple pitot-static tubes are predominantly used to measure the aerodynamic speed. In this work, the influence of rain on this measurement is investigated using representative pitot tubes of different diameters. In wind tunnel tests, water droplets with a diameter of about 3 mm are generated at a flow velocity of 10 m/s, which hit the pitot tubes at the total pressure bore. The observed disturbances sometimes last several hours and are equivalent to a total failure of the measuring system during flight operations. Phenomena are identified that influence the measurement of dynamic pressure in rain. It can be shown that both capillarity and the momentum of the raindrops play a decisive role in the type, severity and duration of the disturbance due to their relative movement to the tube. The further course of the disturbance is also influenced by the evaporation of liquid, both on and in the tube. In flight tests under rain conditions, the findings of the wind tunnel tests were qualitatively confirmed and additional disturbance patterns were observed. © The Author(s) 2024.

关键词： Unmanned aerial vehicles (UAV)

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Development and Implementation of a Safety Gateway for a Medical Evacuation eVTOL Aircraft

Development and Implementation of a Safety Gateway for a Med...

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AIAA Aviation Forum and ASCEND, 2024

作者： Heimsch, Dominik Söpper, Max Speckmaier, Moritz Mbikayi, Zoe Kellringer, Sebastian Holzapfel, Florian Institute of Flight System Dynamics Technical University of Munich Germany

ISBN: (数字)9781624107160

ISBN: (纸本)9781624107160

This paper presents a safety gateway for a medical evacuation eVTOL drone that determines the feasibility of a fully automated mission before uploading the mission to the onboard flight control computer. Software constraints on the flight guidance functions ensure the integrity of the trajectory generation and vertical takeoff and landing system. Furthermore, the gateway considers physical constraints such as the required energy consumption of the vehicle and static atmospheric conditions. As the drone is designed to be operated in non-segregated airspace, missions are also verified to be in compliance with Fly- and No-Fly-Zones. Fully autonomous missions of the evacuation drone have been performed in simulation. The gateway has proven to mitigate failures in mission planning and enhance the safety of the mission and the vehicle. © 2024, American institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Drones

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Synchronizing ADS-B Data with Bayesian Filters and Smoothers for Separation Distance Calculations

Synchronizing ADS-B Data with Bayesian Filters and Smoothers...

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2025 Integrated Communications, Navigation and Surveillance Conference, ICNS 2025

作者： Beller, Lukas Holzapfel, Florian Institute of Flight System Dynamics Technical University of Munich Garching Germany

ISBN: (纸本)9798331534738

This paper investigates how the calculation of sepa-ration distances from ADS-B data received by a single receiver is affected by the asynchronously sent ADS-B data from different aircraft. Therefore, unsynchronized ADS-B data containing 838 arrivals and departures recorded over one day are synchronized using an Extended Kalman Filter and Extended Rauch Tung Striebel Smoother. We calculate pairwise separation distances for all flights based on the unsynchronized and synchronized data. Finally, we compare and statistically evaluate the differences between the unsynchronized and synchronized results. © 2025 IEEE.

关键词： Kalman filters

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Filter and sensor delay synchronization in incremental flight control laws

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Aerospace systems 2023年第2期6卷 285-304页

作者： Steffensen, Rasmus Steinert, Agnes Mbikayi, Zoe Raab, Stefan Angelov, Jorg Holzapfel, Florian Institute of Flight System Dynamics Technical University of Munich Boltzmannstrasse 15 Garching85748 Germany

This paper introduces and investigates several methods of filtering and delay synchronization in incremental control law structures. It is shown that proper filter and delay synchronization is of great importance for both the performance and stability of the control laws. It is derived how to synthesize complementary filters in case of sensor dynamics, sensor delays and internal control law filtering such as roll-off filters and notch filters. The complementary filters are compared to common synchronization approaches previously applied in incremental control laws. It is shown that the proposed methods are beneficial for Multiple Input Multiple Output (MIMO) systems in case that different delays and filtering is present in the different measurement signals. In case of strongly coupled input effectiveness, the synchronization on the actuator feedback may become even unstable, where the complementary filter approach recovers the design closed-loop behavior. In addition, it is derived how to initialize the complementary filters for a transient-free engagement in non-steady-state conditions. The results are compared in simulation with a roll rate control law for a fixed wing aircraft. © 2023, The Author(s).

关键词： MIMO systems

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An Object-Oriented Approach for Developing Standard Operating Procedures for Novel Aerial systems 43

An Object-Oriented Approach for Developing Standard Operatin...

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43rd AIAA DATC/IEEE Digital Avionics systems Conference, DASC 2024

作者： Maly, Markus Hoffelner, Julius Göppner, Christian Holzapfel, Florian Institute of Flight System Dynamics Technical University of Munich Munich Germany

ISBN: (纸本)9798350349610

This paper addresses the need for standard operating procedures in the prototyping phase and final certification of unmanned aerial systems and optionally piloted vehicles. The proposed approach adopts object-oriented principles from software engineering to develop functional and adaptable standard operating procedures. Two paradigms are presented: one focuses on enhancing efficiency, reliability, and safety through an object-oriented approach, and the other emphasizes operations as state spaces. The operations are structured as classes, subdivided into phases, and further broken down into procedures and steps. Constraints are defined based on existing knowledge or testing-generated information to ensure safe state transitions. An initial software tool is developed to enhance procedure validation and verification. While still in progress, this systematic approach promises improved efficiency and reliability in Unmanned Aerial system development. © 2024 IEEE.

关键词： Software testing

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Smooth free-cycle dynamic soaring in unspecified shear wind via quadratic programming

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Chinese Journal of Aeronautics 2022年第7期35卷 19-29页

作者： Haichao HONG Benedikt GRüTER Patrick PIPREK Florian HOLZAPFEL Institute of Flight System Dynamics Technical University of MunichGarching D-85748Germany

Harvesting wind energy is promising for extending long-endurance flights,which can be greatly facilitated by a flight technique called dynamic *** presented study is concerned with generating model-based trajectories with smooth control histories for dynamic soaring maneuvers exploiting wind *** desired smoothness is achieved by introducing a trigonometric series parameterization for the controls,which are formulated with respect to the normalized ***,the periodicity of the trigonometric functions is leveraged to facilitate the connection of cycles and streamline the problem *** relying on a specified wind profile,a freefinal-time quadratic programming-based control strategy is developed for the online correction of the flight trajectory,which requires only the instant wind *** and online numerical studies show the trade-off to achieve the smoothness and demonstrate the effectiveness of the proposed method in a varying wind field.

关键词： Dynamic soaring Optimal control Quadratic programming Trajectory generation Trigonometric series

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Runtime Monitoring of flight control with Incremental Nonlinear Dynamic Inversion 43

Runtime Monitoring of Flight Control with Incremental Nonlin...

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43rd AIAA DATC/IEEE Digital Avionics systems Conference, DASC 2024

作者： Hofsäß, Hannes Holzapfel, Florian Institute of Flight System Dynamics Technical University of Munich Munich Germany

ISBN: (纸本)9798350349610

Runtime monitoring of flight control is an alternate approach for safety assurance, if the absence of design errors in the software of a nominal control law is not fully assured during design. A backup controller is engaged by the system after a failure of the nominal controller has been detected. Due to a lack of experience with novel aircraft configurations, the backup controller may be engaged due to unforeseen disturbances or system failures. As the backup controller provides only degraded flight control, its engagement then imposes an additional risk. In this paper, a novel concept for monitoring of a nominal controller's outputs is proposed. It allows the nominal controller to retain actuator control authority if the aircraft leaves the safety envelope of the backup controller due to exogenous disturbances. The design bases on barrier function theory, while model dependency is reduced through an incremental formulation of the correlation between the envelope's boundary and the control limits. Validation is provided by analysis of missed detections and false alarms in a simulative use case. © 2024 IEEE.

关键词： Aircraft plants

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Optimal trajectory design accounting for the stabilization of linear time-varying error dynamics

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Chinese Journal of Aeronautics 2022年第7期35卷 55-66页

作者： Patrick PIPREK Haichao HONG Florian HOLZAPFEL Institute of Flight System Dynamics Technical University of MunichGarching D-85748Germany

This study is dedicated to the development of a direct optimal control-based algorithm for trajectory optimization problems that accounts for the closed-loop stability of the trajectory tracking error dynamics already during the ***,the trajectory is designed such that the Linear Time-Varying(LTV)dynamic system,describing the controller’s error dynamics,is stable,while additionally the desired optimality criterion is optimized and all enforced constraints on the trajectory are *** is achieved by means of a Lyapunov stability analysis of the LTV dynamics within the optimization problem using a time-dependent,quadratic Lyapunov function *** care is taken with regard to ensuring the correct definiteness of the ensuing matrices within the Lyapunov stability analysis,specifically considering a numerically stable formulation of these in the numerical *** developed algorithm is applied to a trajectory design problem for which the LTV system is part of the path-following error dynamics,which is required to be *** main benefit of the proposed scheme in this context is that the designed trajectory trades-off the required stability and robustness properties of the LTV dynamics with the optimality of the trajectory already at the design phase and thus,does not produce unstable optimal trajectories the system must follow in the real application.

关键词： LTV error dynamics LTV stability Optimal control-based LTV stabilization Path-following error controller Trajectory generation Trajectory optimization

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