314 research outputs found
Aerobatic maneuvering of Autonomous Hybrid UAVs: Trajectory Tracking using INDI in the Control Frame
No full textUnmanned Aerial Vehicles (UAVs) are increasingly being used in various applications, which demand longer endurance, extended range, and high maneuverability. These requirements necessitate the development of effective control methods for Hybrid UAVs. In this paper, we propose an outer loop Incremental Nonlinear Dynamic Inversion (INDI) controller for Hybrid UAVs, based on an analytically derived control effectiveness to control the linear acceleration of the UAV. The control effectiveness is derived in a new frame that does not show singularities, technically allowing controlled flight at all attitudes. For trajectory tracking purposes, a Proportional Derivative (PD) controller is added. In simulation the proposed controller shows comparable results to already existing INDI controllers for hover and forward flight. When performing loop the loops it is shown that the proposed control system is able to handle high roll angles, while the already existing INDI controller crashed.Aerospace Engineerin
Hybrid UAV Attitude Control using INDI and Dynamic Tilt-Twist
No full textThe application of Unmanned Aerial Vehicles (UAVs) is increasing, much like the performance of these aircraft. A tailsitter is a type of UAV which is capable of performing vertical take-offs and landings (VTOL) and long endurance flights. During hover, the yaw control is limited due to the dynamics of these tailsitters. The generally used quaternion feedback for the attitude does not compensate for this as it describes a singular rotation. Tilt-twist is a solution to the problem as it splits the tilt (pitch and roll) from the twist (yaw). The axis of the yaw rotation is body fixed. When hovering with a pitch and/or roll angle the twist axis will be aligned with the body z-axis, instead of the desired gravitational force vector (for position control). Previous tilt-twist methods used a PID controller. This paper describes an improvement over previous tilt-twist approaches, the dynamic tilt-twist in combination with INDI. The INDI controller is designed for nonlinear systems. The dynamic tilt-twist compensates for the problem with the normal tilt-twist as test results will demonstrate. Tests are performed in a simulation and a real life test with the NederDrone hybrid tailsitter is done.Aerospace Engineerin
Hybrid UAV Attitude Control using INDI and Dynamic Tilt-Twist
No full textThe increased search for the performance of Unmanned Aerial Vehicles (UAVs) has led to an interest in hybrid concepts like the tail-sitter UAV. A tail-sitter UAV is capable of combining vertical take-offs and landings (VTOL) with efficient long-endurance forward flights. During hover, the wings do not provide lift but instead act as disturbance and limit the yaw response. Attitude control based on direct quaternion feedback does not take the differences in reaction speed for the three axes into account. Tilt-twist control has been proposed to overcome this problem as it splits the faster tilt (pitch and roll) from the slower and less important twist (yaw) and is successfully applied to quadrotor control. This paper proposes a novel tilt-twist controller based on Incremental Nonlinear Dynamic Inversion (INDI). But in tail-sitter UAVs, the lift vector can differ a lot from the tilt angle, especially when partly or fully transitioned to forward flight. To address this, a dynamic tilt-twist controller is proposed that redefines the twist according to the transition angle. Simulations and test flight tests are performed with the Neder- Drone hybrid tail-sitter to show the increased performance.Control & Simulatio
STUDI DETERMINASI KECERDASAN EMOSI, KEPUASAN KERJA, DAN KOMITMEN ORGANISASI TERHADAP ORGANIZATIONAL CITIZENSHIP BEHAVIOUR
No full textTujuan dari penelitian ini adalah untuk menganalisis dan menginvestigasi pengaruh kecerdasan emosi, kepuasan kerja dan komitmen organisasi terhadap organizational citizenship behaviour di Sekretariat Daerah Kota Tasikmalaya. Metode penelitian yang digunakan adalah survey. Alat analisis yang digunakan adalah analisis jalur. Teknik pengumpulan data melalui penyebaran kuesioner dan depth interview. Penelitian ini menggunakan sampel sebesar 72 pegawai Sekretariat Daerah kota Tasikmalaya. Teknik pengambilan sampel menggunakan Proportionate Stratified Random Sampling. Berdasarkan hasil analisis diketahui bahwa kecerdasan emosi, kepuasan kerja dan komitmen organisasi secara simultan maupun parsial mempunyai pengaruh yang signifikan terhadap organizational citizenship behaviour. Oleh karena itu, instansi diharapkan untuk meningkatkan kecerdasan emosi pegawai dari sisi empati agar dapat meningkatkan intensitas komunikasi antar rekan kerja dan atasan dan lebih meningkatkan sense of belonging pegawai dengan cara meningkatkan program benefit and service
Analisis Bibliometrik Dari Sewindu Penelitian Tentang Asset Pricing
No full textABSTRACTThis study aims to present the development of asset pricing models from bibliometric analysis and provide scope and direction for future research. The Scopus database was used to search for research articles on asset pricing from 2016-2023. Out of 8,839 articles, 2,860 were selected for the final bibliometric analysis. Citation analysis, keyword analysis, and author-related analysis were conducted. Based on the results of bibliometric analysis, it is known that the United States is the country that conducts the most research on asset pricing. Keyword analysis was also analyzed to evaluate important areas of research. Financial markets, stock markets, costs, investment, price dynamics, risk assessment, commerce, CAPM, stock returns, asset pricing models, return predictability, risk factors, and profitability are the most frequently used keywords. The year 2021 had the highest number of research articles. The most prominent author in asset pricing research is Zaremba who has the highest citations.
Improving the Performance of INDI Flight Control for a Quadrotor in the Ceiling Effect
No full textAs the application areas of Unmanned Aerial Vehicles (UAVs) keep expanding, new flight areas are encountered more often. Small UAVs, named Micro Air Vehicles (MAVs), even fly in areas like sewage pipes. These areas introduce new difficulties such as aerodynamic effects caused by the ground and/or ceiling. In this paper two main contributions are presented that deal with the aerodynamic effects caused by the ceiling: 1) an adaptive model describing the ceiling effect using onboard measurements, which can be altered to describe other aerodynamic effects that occur when flying in constrained spaces, 2) incorporating the adaptive model into an Incremental Nonlinear Dynamic Inversion (INDI) controller. The controller is implemented and tested onto a MAV (Crazyflie). The results have shown stability improvements for close ceiling flight. Moreover the minimal distance the MAV can fly from the ceiling is decreased using the new controller.Aerospace Engineerin
INDI Control for the ObliqueWing-Quad Plane Drone
No full textA type of UAV sharing the advantages of rotorcraft and fixed wing vehicles is the hybrid vehicle. Hybrid UAVs can take-off and land vertically and fly fast and efficient in forward flight due to the presence of a wing generating lift. However, combining the fixed wing and rotorcraft concept ends up in a multi-rotor with large dimensions when landed, and catching a lot of gust when hovering. Therefore, the oblique wing-quad plane drone has been developed which can rotate its quad arm and wing such that the wing can be aligned with the fuselage in hover. The wing can be rotated to fixed wing position during fast forward flight, stowing away one quad-arm. An INDI inner and outer loop controller has been implemented for this platform. Successful flight tests proved the feasibility of this controller and drone concept which is patent pending NL 2031701, Aeronautical Vehicle and Method of Transitioning between Flight Modes for an Aeronautical Vehicle, April 26th 2022,Control & Simulatio
Flight Control Law Design using Hybrid Incremental Nonlinear Dynamic Inversion
No full textIncremental Nonlinear Dynamic Inversion (INDI) is a sensor-based control strategy, which has shown robustness against model uncertainties on various aerospace platforms. The sensor-based nature of the method brings attractive properties, which has made it popular in the last decade. INDI globally linearizes the system by making use of control input and state derivative feedback. Despite the enhanced robustness against parametric system uncertainties compared to traditional NDI, mitigating the effects of time lag between the control input and state derivative feedback paths represents an important challenge for INDI. Past research has shown that this can be addressed by synchronizing these feedback signals, although the method remains vulnerable to unexpected measurement delays. This paper proposes a hybrid INDI approach based on complementary filtering to further mitigate this robustness issue. The approach fuses the system model and sensor measurement to generate an estimate of the angular acceleration of the system. The estimation responds rapidly to the system input thanks to the on-board model, whereas adequate accuracy in the low-to-medium frequency range is maintained by the sensor measurement. The control law is found to retain good performance in case of model mismatches and measurement delays. To demonstrate the method, a hybrid INDI-based attitude control law is designed for a nonlinear F-16 aircraft model. The robustness properties of the resulting control system are analyzed using time-domain simulations.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Control & Simulatio
Quadrotor Fault Tolerant Incremental Sliding Mode Control driven by Sliding Mode Disturbance Observers
No full textThis paper proposes an Incremental Sliding Mode Control driven by Sliding Mode Disturbance Observers (INDI-SMC/SMDO), with application to a quadrotor fault tolerant control problem. By designing the SMC/SMDO based on the control structure of the sensor-based Incremental Nonlinear Dynamic Inversion (INDI), instead of the model-based Nonlinear Dynamic Inversion (NDI) in the literature, the model dependency of the controller and the uncertainties in the closed-loop system are simultaneously reduced. This allows INDI-SMC/SMDO to passively resist a wider variety of faults and external disturbances using continuous control inputs with lower control and observer gains. When applied to a quadrotor, both numerical simulations and real-world flight tests demonstrate that INDI based SMC/SMDO has better performance and robustness over NDI based SMC/SMDO, in the presence of model uncertainties, wind disturbances, and sudden actuator faults. Moreover, the implementation process is simplified because of the reduced model dependency and smaller uncertainty variations of INDI-SMC/SMDO. Therefore, the proposed control method can be easily implemented to improve the performance and survivability of quadrotors in real life.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Control & Simulatio
Discrete-time Design and Stability Analysis for Nonlinear Incremental Fault-tolerant Flight Control
No full textIncremental control, including incremental nonlinear dynamic inversion (INDI) and incremental backstepping (IBS), is a sensor-based control framework that enhances the control robustness by exploiting sensor measurements. Although its effectiveness has been demonstrated on various aerospace systems, the explicit and quantifiable expression for the ultimate bound of the tracking error, as a function of the sampling frequency and perturbation bound, has not been presented. This issue is addressed by the discrete-time domain stability analysis of the incremental control in this paper, which allows convenient yet realistic performance assessment and parameter tuning before performing real-world flight tests. Another challenge faced by the incremental control is that its stability criterion can be violated in severe aircraft fault scenarios, such as the control reversal. Therefore, this paper proposes a discrete-time control-direction-based incremental sliding mode control, denoted as D-INDI-SMC, which has broader applicability than the state-of-the-art incremental control methods. The robustness of D-INDI-SMC against control reversal, sensing errors, model uncertainties, actuator faults, and structural damage has been theoretically proved and numerically demonstrated.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Aerospace Structures & Computational Mechanic
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