Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (92)

Search Parameters:
Keywords = VTOL UAVs

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
27 pages, 1880 KiB  
Article
UAV-Enabled Video Streaming Architecture for Urban Air Mobility: A 6G-Based Approach Toward Low-Altitude 3D Transportation
by Liang-Chun Chen, Chenn-Jung Huang, Yu-Sen Cheng, Ken-Wen Hu and Mei-En Jian
Drones 2025, 9(6), 448; https://doi.org/10.3390/drones9060448 - 18 Jun 2025
Viewed by 602
Abstract
As urban populations expand and congestion intensifies, traditional ground transportation struggles to satisfy escalating mobility demands. Unmanned Electric Vertical Take-Off and Landing (eVTOL) aircraft, as a key enabler of Urban Air Mobility (UAM), leverage low-altitude airspace to alleviate ground traffic while offering environmentally [...] Read more.
As urban populations expand and congestion intensifies, traditional ground transportation struggles to satisfy escalating mobility demands. Unmanned Electric Vertical Take-Off and Landing (eVTOL) aircraft, as a key enabler of Urban Air Mobility (UAM), leverage low-altitude airspace to alleviate ground traffic while offering environmentally sustainable solutions. However, supporting high bandwidth, real-time video applications, such as Virtual Reality (VR), Augmented Reality (AR), and 360° streaming, remains a major challenge, particularly within bandwidth-constrained metropolitan regions. This study proposes a novel Unmanned Aerial Vehicle (UAV)-enabled video streaming architecture that integrates 6G wireless technologies with intelligent routing strategies across cooperative airborne nodes, including unmanned eVTOLs and High-Altitude Platform Systems (HAPS). By relaying video data from low-congestion ground base stations to high-demand urban zones via autonomous aerial relays, the proposed system enhances spectrum utilization and improves streaming stability. Simulation results validate the framework’s capability to support immersive media applications in next-generation autonomous air mobility systems, aligning with the vision of scalable, resilient 3D transportation infrastructure. Full article
Show Figures

Figure 1

22 pages, 6442 KiB  
Article
An Efficient SDOF Sweep Wing Morphing Technology for eVTOL-UAV and Experimental Realization
by Palaniswamy Shanmugam, Parammasivam Kanjikovil Mahali and Samikkannu Raja
Drones 2025, 9(6), 435; https://doi.org/10.3390/drones9060435 - 14 Jun 2025
Viewed by 313
Abstract
The presented study demonstrates that UAVs can be flown with a morphing wing to develop essential aerodynamic efficiency without a tail structure, which decides the operational cost and flight safety. The mechanical control for morphing is discussed, where the system design, simulation, and [...] Read more.
The presented study demonstrates that UAVs can be flown with a morphing wing to develop essential aerodynamic efficiency without a tail structure, which decides the operational cost and flight safety. The mechanical control for morphing is discussed, where the system design, simulation, and experimental realization of ±15° SDOF sweep motion for a 7 kg eVTOL wing are detailed. The methodology, developed through a mathematical modeling of the mechanism’s kinematics and dynamics, is explained using Denavit–Hartenberg (D-H) convention, Lagrangian mechanics, and Euler–Lagrangian equations. The simulation and MBD analyses were performed in MATLAB R2021 and by Altair Motion Solve, respectively. The experiment was conducted on a dedicated test rig with two wing variants fitted with IMUs and an autopilot. The results from various methods were analyzed and experimentally compared to provide an accurate insight into the system’s design, modeling, and performance of the sweep morphing wing. The theoretical calculations by the mathematical model were compared with the test results. The sweep requirement is essential for eVTOL to have long endurance and multi-mission capabilities. Therefore, the developed sweep morphing mechanism is very useful, meeting such a demand. However, the results for three-dimensional morphing, operating sweep, pitch, and roll together are also presented, for the sake of completeness. Full article
Show Figures

Figure 1

35 pages, 4434 KiB  
Article
MDO of Robotic Landing Gear Systems: A Hybrid Belt-Driven Compliant Mechanism for VTOL Drones Application
by Masoud Kabganian and Seyed M. Hashemi
Drones 2025, 9(6), 434; https://doi.org/10.3390/drones9060434 - 14 Jun 2025
Viewed by 450
Abstract
This paper addresses inherent limitations in unmanned aerial vehicle (UAV) undercarriages hindering vertical takeoff and landing (VTOL) capabilities on uneven slopes and obstacles. Robotic landing gear (RLG) designs have been proposed to address these limitations; however, existing designs are typically limited to ground [...] Read more.
This paper addresses inherent limitations in unmanned aerial vehicle (UAV) undercarriages hindering vertical takeoff and landing (VTOL) capabilities on uneven slopes and obstacles. Robotic landing gear (RLG) designs have been proposed to address these limitations; however, existing designs are typically limited to ground slopes of 6–15°, beyond which rollover would happen. Moreover, articulated RLG concepts come with added complexity and weight penalties due to multiple drivetrain components. Previous research has highlighted that even a minor 3-degree slope change can increase the dynamic rollover risks by 40%. Therefore, the design optimization of robotic landing gear for enhanced VTOL capabilities requires a multidisciplinary framework that integrates static analysis, dynamic simulation, and control strategies for operations on complex terrain. This paper presents a novel, hybrid, compliant, belt-driven, three-legged RLG system, supported by a multidisciplinary design optimization (MDO) methodology, aimed at achieving enhanced VTOL capabilities on uneven surfaces and moving platforms like ship decks. The proposed system design utilizes compliant mechanisms featuring a series of three-flexure hinges (3SFH), to reduce the number of articulated drivetrain components and actuators. This results in a lower system weight, improved energy efficiency, and enhanced durability, compared to earlier fully actuated, articulated, four-legged, two-jointed designs. Additionally, the compliant belt-driven actuation mitigates issues such as backlash, wear, and high maintenance, while enabling smoother torque transfer and improved vibration damping relative to earlier three-legged cable-driven four-bar link RLG systems. The use of lightweight yet strong materials—aluminum and titanium—enables the legs to bend 19 and 26.57°, respectively, without failure. An animated simulation of full-contact landing tests, performed using a proportional-derivative (PD) controller and ship deck motion input, validate the performance of the design. Simulations are performed for a VTOL UAV, with two flexible legs made of aluminum, incorporating circular flexure hinges, and a passive third one positioned at the tail. The simulation results confirm stable landings with a 2 s settling time and only 2.29° of overshoot, well within the FAA-recommended maximum roll angle of 2.9°. Compared to the single-revolute (1R) model, the implementation of the optimal 3R Pseudo-Rigid-Body Model (PRBM) further improves accuracy by achieving a maximum tip deflection error of only 1.2%. It is anticipated that the proposed hybrid design would also offer improved durability and ease of maintenance, thereby enhancing functionality and safety in comparison with existing robotic landing gear systems. Full article
Show Figures

Figure 1

19 pages, 994 KiB  
Article
A Procedure for Developing a Flight Mechanics Model of a Three-Surface Drone Using Semi-Empirical Methods
by Stefano Cacciola, Laura Testa and Matteo Saponi
Aerospace 2025, 12(6), 515; https://doi.org/10.3390/aerospace12060515 - 7 Jun 2025
Viewed by 337
Abstract
Aircraft and fixed-wing drones, designed to perform vertical take-off and landing (VTOL), often incorporate unconventional configurations that offer unique capabilities but simultaneously pose significant challenges in flight mechanics modeling, whose reliability strongly depends on the correct tuning of the inertial and aerodynamic parameters. [...] Read more.
Aircraft and fixed-wing drones, designed to perform vertical take-off and landing (VTOL), often incorporate unconventional configurations that offer unique capabilities but simultaneously pose significant challenges in flight mechanics modeling, whose reliability strongly depends on the correct tuning of the inertial and aerodynamic parameters. Having a good characterization of the aerodynamics represents a critical issue, especially in the design and optimization of unconventional aircraft configurations, when, indeed, one is bound to employ empirical or semi-empirical methods, devised for conventional geometries, that struggle to capture complex aerodynamic interactions. Alternatives such as high-fidelity computational fluid dynamics (CFD) simulations, although more accurate, are typically expensive and impractical for both preliminary design and lofting optimization. This work introduces a procedure that exploits multiple analyses conducted through semi-empirical methodologies implemented in the USAF Digital DATCOM to develop a flight mechanics model for fixed-wing unmanned aerial vehicles (UAVs). The reference UAV chosen to test the proposed procedure is the Dragonfly DS-1, an electric VTOL UAV developed by Overspace Aviation, featuring a three-surface configuration. The accuracy of the polar data, i.e., the lift and drag coefficients, is assessed through comparisons with computational fluid dynamics simulations and flight data. The main discrepancies are found in the drag estimation. The present work represents a preliminary investigation into the possible extension of semi-empirical methods, consolidated for traditional configurations, to unconventional aircraft so as to support early-stage UAV design. Full article
(This article belongs to the Section Aeronautics)
Show Figures

Figure 1

21 pages, 4228 KiB  
Article
Real-Time TECS Gain Tuning Using Steepest Descent Method for Post-Transition Stability in Unmanned Tilt-Rotor eVTOLs
by Choonghyun Lee, Ngoc Phi Nguyen, Sangjun Bae and Sung Kyung Hong
Drones 2025, 9(6), 414; https://doi.org/10.3390/drones9060414 - 6 Jun 2025
Viewed by 885
Abstract
Unmanned tilt-rotor electric Vertical Take-Off and Landing (eVTOL) aircraft face significant control challenges during the transition from hover to forward flight, particularly when using open-source autopilot systems that rely on open-loop tilt control and static control gains. After the transition, the Total Energy [...] Read more.
Unmanned tilt-rotor electric Vertical Take-Off and Landing (eVTOL) aircraft face significant control challenges during the transition from hover to forward flight, particularly when using open-source autopilot systems that rely on open-loop tilt control and static control gains. After the transition, the Total Energy Control System (TECS) becomes active in fixed-wing mode, but its default static gains often fail to correct energy imbalances, resulting in substantial altitude loss. This paper presents the Steepest Descent-based Total Energy Control System (SD-TECS), a real-time adaptive TECS framework that dynamically tunes gains using the steepest descent method to enhance post-transition altitude and airspeed regulation in unmanned tilt-rotor eVTOLs. The proposed method integrates gain adaptation directly into the TECS loop, optimizing control actions based on instantaneous flight states such as altitude and energy-rate errors. This enables improved responsiveness to nonlinear dynamics during the critical post-transition phase. Simulation results demonstrate that the SD-TECS approach significantly improves control performance compared to the default PX4 TECS, achieving a 35.5% reduction in the altitude settling time, a 57.3% improvement in the airspeed settling time, and a 66.1% decrease in the integrated altitude error. These improvements highlight the effectiveness of SD-TECS in enhancing the stability and reliability of unmanned tilt-rotor eVTOLs operating under autonomous control. Full article
Show Figures

Figure 1

26 pages, 3839 KiB  
Article
Preliminary Design and Optimization Approach of Electric FW-VTOL UAV Based on Cell Discharge Characteristics
by Cheng He, Yuqi Tong, Diyi Liu, Shipeng Yang and Fengjiang Zhan
Drones 2025, 9(6), 415; https://doi.org/10.3390/drones9060415 - 6 Jun 2025
Viewed by 1326
Abstract
The electric vertical take-off and landing fixed-wing (FW-VTOL) unmanned aerial vehicle (UAV) combines the advantages of fixed-wing aircraft and multi-rotor aircraft. Based on the cell discharge characteristics and the power system features, this paper proposes a preliminary design and optimization method suitable for [...] Read more.
The electric vertical take-off and landing fixed-wing (FW-VTOL) unmanned aerial vehicle (UAV) combines the advantages of fixed-wing aircraft and multi-rotor aircraft. Based on the cell discharge characteristics and the power system features, this paper proposes a preliminary design and optimization method suitable for electric FW-VTOL UAVs. The purpose of this method is to improve the design accuracy of electric propulsion systems and overall parameters when dealing with the special power and energy requirements of this type of aircraft. The core of this method involves testing the performance data of the cell inside the battery pack, using small-capacity cells as the basic unit for battery sizing, thereby constructing a power battery performance model. Additionally, it establishes optimization design models for propellers and rotors and develops a brushless DC motor performance model based on a first-order motor model and statistical data, ultimately achieving optimized matching of the propulsion system and completing the preliminary design of the entire aircraft. Using a battery discharge model established based on real cell parameters and test data, the impact of the discharge process on battery performance is evaluated at the cell level, reducing the subjectivity of battery performance evaluation compared to the constant power/energy density method used in traditional battery sizing processes. Furthermore, matching the optimization design of power and propulsion systems effectively improves the accuracy of the preliminary design for FW-VTOL UAVs. A design case of a 30 kg electric FW-VTOL UAV is conducted, along with the completion of flight tests. The design parameters obtained using the proposed method show minimal discrepancies with the actual data from the actual aircraft, confirming the effectiveness of the proposed method. Full article
Show Figures

Figure 1

42 pages, 9332 KiB  
Article
Design and Validation of a New Tilting Rotor VTOL Drone: Structural Optimization, Flight Dynamics, and PID Control
by Haixia Gong, Wei He, Shuping Hou, Ming Chen, Ziang Yang, Qin Si and Deming Zhao
Sensors 2025, 25(11), 3537; https://doi.org/10.3390/s25113537 - 4 Jun 2025
Viewed by 912
Abstract
This study addresses the gap in the experimental validation of the tilt-rotor vertical take-off and landing (VTOL) UAVs by developing a novel prototype that integrates fixed-wing and multi-rotor advantages. A dynamic model based on the “X” quadrotor configuration was established, and Euler parameters [...] Read more.
This study addresses the gap in the experimental validation of the tilt-rotor vertical take-off and landing (VTOL) UAVs by developing a novel prototype that integrates fixed-wing and multi-rotor advantages. A dynamic model based on the “X” quadrotor configuration was established, and Euler parameters were employed to derive the attitude transformation matrix. Structural optimization using hybrid meshing and inertia release methods revealed a maximum deformation of 57.1 mm (2.82% of half-wingspan) and stress concentrations below material limits (379.21 MPa on fasteners). The landing gear was optimized using the unified objective method, and the stress was reduced by 32.63 MPa compared to the pre-optimization stress. Vibration analysis identified hazardous frequencies (11–12 Hz) to avoid resonance. Stable motor speed tracking (±5 RPM) and rolling attitude control (less than 10% error) are achieved using a dual-serial PID control system based on the DSP28377D master. Experimental validation in low-altitude flights confirmed the prototype’s feasibility, though ground effects impacted pitch/yaw performance. This work provides critical experimental data for future tilt-rotor UAV development. Full article
(This article belongs to the Section Intelligent Sensors)
Show Figures

Figure 1

18 pages, 13241 KiB  
Article
Experimental Investigation of Aerodynamic Interaction in Non-Parallel Tandem Dual-Rotor Systems for Tiltrotor UAV
by He Zhu, Yuhao Du, Hong Nie, Zhiyang Xin and Xi Geng
Drones 2025, 9(5), 374; https://doi.org/10.3390/drones9050374 - 15 May 2025
Viewed by 596
Abstract
The distributed electric tilt-rotor Unmanned Aerial Vehicle (UAV) combines the vertical take-off and landing (VTOL) capability of helicopters with the high-speed cruise performance of fixed-wing aircraft, offering a transformative solution for Urban Air Mobility (UAM). However, aerodynamic interference between rotors is a new [...] Read more.
The distributed electric tilt-rotor Unmanned Aerial Vehicle (UAV) combines the vertical take-off and landing (VTOL) capability of helicopters with the high-speed cruise performance of fixed-wing aircraft, offering a transformative solution for Urban Air Mobility (UAM). However, aerodynamic interference between rotors is a new challenge to improving their flight efficiency, especially the dynamic interactions during the transition phase of non-parallel tandem dual-rotor systems, which require in-depth investigation. This study focuses on the aerodynamic performance evolution of the tilt-rotor system during asynchronous transition processes, with an emphasis on quantifying the influence of rotor tilt angles. A customized experimental platform was developed to investigate a counter-rotating dual-rotor model with fixed axial separation. Key performance metrics, including thrust, torque, and power, were systematically measured at various tilt angles (0–90°) and rotational speeds (1500–3500 RPM). The aerodynamic coupling mechanisms between the front and rear rotor disks were analyzed. The experimental results indicate that the relative tilt angle of the dual rotors significantly affects aerodynamic interference between the rotors. In the forward tilt mode, the thrust of the aft rotor recovers when the tilt angle reaches 45°, while in the aft tilt mode, it requires a tilt angle of 75°. By optimizing the tilt configuration, the aerodynamic performance loss of the aft rotor due to rotor-to-rotor aerodynamic interference can be effectively mitigated. This study provides important insights for the aerodynamic performance optimization and transition control strategies of the distributed electric tilt-rotor UAV. Full article
(This article belongs to the Special Issue Dynamics Modeling and Conceptual Design of UAVs)
Show Figures

Figure 1

21 pages, 9421 KiB  
Article
Temporal-Sequence Offline Reinforcement Learning for Transition Control of a Novel Tilt-Wing Unmanned Aerial Vehicle
by Shiji Jin and Wenjie Zhao
Aerospace 2025, 12(5), 435; https://doi.org/10.3390/aerospace12050435 - 13 May 2025
Viewed by 513
Abstract
A newly designed tilt-wing unmanned aerial vehicle (Tilt-wing UAV) requires a unified control strategy across rotary-wing, fixed-wing, and transition modes, introducing significant challenges. Existing control strategies typically rely on accurate modeling or extensive parameter tuning, which limits their adaptability to dynamically changing flight [...] Read more.
A newly designed tilt-wing unmanned aerial vehicle (Tilt-wing UAV) requires a unified control strategy across rotary-wing, fixed-wing, and transition modes, introducing significant challenges. Existing control strategies typically rely on accurate modeling or extensive parameter tuning, which limits their adaptability to dynamically changing flight configurations. Although online reinforcement learning algorithms offer adaptability, they depend on real-world exploration, posing considerable safety and cost risks for safety-critical UAV applications. To address this challenge, we propose Temporal Sequence Constrained Q-learning (TSCQ), an offline RL framework that integrates an encoder–decoder with recurrent networks to capture temporal dependencies. The policy is further constrained within an offline dataset collected via hardware-in-the-loop simulation using a variational autoencoder, and a sequence-level prediction mechanism is introduced to ensure temporal consistency across action trajectories, thereby mitigating extrapolation error while preserving data fidelity. Experimental results demonstrate that TSCQ significantly outperforms gain scheduling, Model Predictive Control (MPC), and Batch-Constrained Q-learning (BCQ), reducing the RMSE of pitch angle by up to 53.3% and vertical velocity RMSE by approximately 33%. These findings underscore the potential of data-driven, safety-aware offline RL paradigms to enable robust and generalizable control strategies for tilt-wing UAVs. Full article
(This article belongs to the Section Aeronautics)
Show Figures

Figure 1

10 pages, 4084 KiB  
Proceeding Paper
Wing Design for Class I Mini Unmanned Aerial Vehicles—Special Considerations for Foldable Wing Configuration at Low Reynolds Numbers
by Eleftherios Karatzas, Eleftherios Nikolaou, Antonis Pitsis, Spiridon Alexopoulos, Vaios Lappas and Vassilis Kostopoulos
Eng. Proc. 2025, 90(1), 96; https://doi.org/10.3390/engproc2025090096 - 11 Apr 2025
Viewed by 816
Abstract
Foldable wing designs are becoming increasingly popular due to their advantages in the rapid deployment and compact packaging of fixed-wing UAVs, particularly when compared to horizontal take-off and VTOL counterparts. However, selecting an appropriate wing design requires the careful consideration of aerodynamic performance [...] Read more.
Foldable wing designs are becoming increasingly popular due to their advantages in the rapid deployment and compact packaging of fixed-wing UAVs, particularly when compared to horizontal take-off and VTOL counterparts. However, selecting an appropriate wing design requires the careful consideration of aerodynamic performance and volume storage constraints. As a result, a trade-off between performance and practicality must be addressed during the conceptual design phase. The primary objective of this study is to identify the optimal wing configuration for a tube-launched foldable wing design. To achieve this, the analysis combine an in-house design tool developed in Excel and XFLR5 v7.01 software. Full article
Show Figures

Figure 1

18 pages, 5575 KiB  
Article
Structural Optimization and Experimental Validation of a Composite Engine Mount Designed for VTOL UAV
by Milica Milić, Jelena Svorcan, Toni Ivanov, Ivana Atanasovska, Dejan Momčilović, Željko Flajs and Boško Rašuo
Aerospace 2025, 12(3), 178; https://doi.org/10.3390/aerospace12030178 - 24 Feb 2025
Cited by 1 | Viewed by 1058
Abstract
Unmanned air vehicles (UAVs) with vertical take-off and landing (VTOL) capabilities, equipped with rotors, have been gaining popularity in recent years for their numerous applications. Through joint efforts, engineers and researchers try to make these novel aircraft more maneuverable and reliable, but also [...] Read more.
Unmanned air vehicles (UAVs) with vertical take-off and landing (VTOL) capabilities, equipped with rotors, have been gaining popularity in recent years for their numerous applications. Through joint efforts, engineers and researchers try to make these novel aircraft more maneuverable and reliable, but also lighter, more efficient and quieter. This paper presents the optimization of one of the vital aircraft parts, the composite engine mount, based on the genetic algorithm (GA) combined with the defined finite element (FE) parameterized model. The mount structure is assumed as a layered carbon composite whose lay-up sequence, defined by layer thicknesses and orientations, is being optimized with the goal of achieving its minimal mass with respect to different structural constraints (failure criteria or maximal strain). To achieve a sufficiently reliable structure, a worst-case scenario, representing a sudden impact, is assumed by introducing forces at one end, while the mount is structurally constrained at the places where it is connected to wings. The defined optimization methodology significantly facilitated and accelerated the mount design process, after which it was manufactured and experimentally tested. Static forces representing the two thrust forces generated by the propellers connected to electric engines (at 100% throttle and the asymmetric case where one engine is at approximately 40% throttle and the other at 100%) and loads from the tail surfaces were introduced by weights, while the strain was measured at six different locations. Satisfactory comparison between numerical and experimental results is achieved, while slight inconsistencies can be attributed to manufacturing errors and idealizations of the FE model. Full article
Show Figures

Figure 1

25 pages, 4799 KiB  
Article
Optimized Structural Design of a Reciprocating Wing for the Reciprocating Airfoil (RA)-Driven Vertical Take-Off and Landing (VTOL) Aircraft
by Johnson Imumbhon Okoduwa, Osezua Obehi Ibhadode and Yiding Cao
Actuators 2025, 14(3), 104; https://doi.org/10.3390/act14030104 - 20 Feb 2025
Viewed by 1078
Abstract
The development of unconventional and hybrid unoccupied aerial vehicles (UAVs) has gained significant momentum in recent years, with many designs utilizing small fans or rotary blades for vertical take-off and landing (VTOL). However, these systems often inherit the limitations of traditional helicopter rotors, [...] Read more.
The development of unconventional and hybrid unoccupied aerial vehicles (UAVs) has gained significant momentum in recent years, with many designs utilizing small fans or rotary blades for vertical take-off and landing (VTOL). However, these systems often inherit the limitations of traditional helicopter rotors, including susceptibility to aerodynamic inefficiencies and mechanical issues. Additionally, achieving a seamless transition from VTOL to fixed-wing flight mode remains a significant challenge for hybrid UAVs. A novel approach is the reciprocating airfoil (RA) or reciprocating wing (RW) VTOL aircraft, which employs a fixed-wing configuration driven by a reciprocating mechanism to generate lift. The RA wing is uniquely designed to mimic a fixed-wing while leveraging its reciprocating motion for efficient lift production and a smooth transition between VTOL and forward flight. Despite its advantages, the RA wing endures substantial stress due to the high inertial forces involved in its operation. This study presents an optimized structural design of the RA wing through wing topology optimization and finite element analysis (FEA) to enhance its load-bearing capacity and stress performance. A comparative analysis with existing RA wing configurations at maximum operating velocities highlights significant improvements in the safety margin, failure criteria, and overall stress distribution. The key results of this study show an 80.4% reduction in deformation, a 43.8% reduction in stress, and a 78% improvement in safety margin. The results underscore the RA wing’s potential as an effective and structurally stable lift mechanism for RA-driven VTOL aircraft, demonstrating its capability to enhance the performance and reliability of next-generation UAVs. Full article
(This article belongs to the Special Issue Aerospace Mechanisms and Actuation—Second Edition)
Show Figures

Figure 1

24 pages, 8468 KiB  
Article
Robust Position Control of VTOL UAVs Using a Linear Quadratic Rate-Varying Integral Tracker: Design and Validation
by Omer Saleem, Muhammad Kazim and Jamshed Iqbal
Drones 2025, 9(1), 73; https://doi.org/10.3390/drones9010073 - 19 Jan 2025
Cited by 3 | Viewed by 1049
Abstract
This article presents an optimal tracking controller retrofitted with a nonlinear adaptive integral compensator, specifically designed to ensure robust and accurate positioning of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs) that utilize contra-rotating motorized propellers for differential thrust generation. The baseline [...] Read more.
This article presents an optimal tracking controller retrofitted with a nonlinear adaptive integral compensator, specifically designed to ensure robust and accurate positioning of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs) that utilize contra-rotating motorized propellers for differential thrust generation. The baseline position controller is synthesized by employing a fixed-gain Linear Quadratic Integral (LQI) tracking controller that stabilizes position by tracking both state variations and pitch-axis tracking error integral, which adjusts the voltage to control each coaxial propeller’s speed accurately. Additionally, the baseline tracking control law is supplemented with a rate-varying integral compensator. It operates as a nonlinear scaling function of the tracking-error velocity and the braking acceleration to enhance the accuracy of reference tracking without sacrificing its robustness against exogenous disruptions. The controller’s performance is analyzed by performing experiments on a tailored hardware-in-the-loop aero-pendulum testbed, which is representative of VTOL UAV dynamics. Experimental results demonstrate significant improvements over the nominal LQI tracking controller, achieving 17.9%, 61.6%, 83.4%, 43.7%, 35.8%, and 6.8% enhancement in root mean squared error, settling time, overshoot during start-up, overshoot under impulsive disturbance, disturbance recovery time, and control energy expenditure, respectively, underscoring the controller’s effectiveness for potential UAV and drone applications under exogenous disturbances. Full article
Show Figures

Figure 1

29 pages, 1017 KiB  
Article
Comparative Analysis of Deep Reinforcement Learning Algorithms for Hover-to-Cruise Transition Maneuvers of a Tilt-Rotor Unmanned Aerial Vehicle
by Mishma Akhtar and Adnan Maqsood
Aerospace 2024, 11(12), 1040; https://doi.org/10.3390/aerospace11121040 - 19 Dec 2024
Cited by 2 | Viewed by 1909
Abstract
Work on trajectory optimization is evolving rapidly due to the introduction of Artificial-Intelligence (AI)-based algorithms. Small UAVs are expected to execute versatile maneuvers in unknown environments. Prior studies on these UAVs have focused on conventional controller design, modeling, and performance, which have posed [...] Read more.
Work on trajectory optimization is evolving rapidly due to the introduction of Artificial-Intelligence (AI)-based algorithms. Small UAVs are expected to execute versatile maneuvers in unknown environments. Prior studies on these UAVs have focused on conventional controller design, modeling, and performance, which have posed various challenges. However, a less explored area is the usage of reinforcement-learning algorithms for performing agile maneuvers like transition from hover to cruise. This paper introduces a unified framework for the development and optimization of a tilt-rotor tricopter UAV capable of performing Vertical Takeoff and Landing (VTOL) and efficient hover-to-cruise transitions. The UAV is equipped with a reinforcement-learning-based control system, specifically utilizing algorithms such as Deep Deterministic Policy Gradient (DDPG), Trust Region Policy Optimization (TRPO), and Proximal Policy Optimization (PPO). Through extensive simulations, the study identifies PPO as the most robust algorithm, achieving superior performance in terms of stability and convergence compared with DDPG and TRPO. The findings demonstrate the efficacy of DRL in leveraging the unique dynamics of tilt-rotor UAVs and show a significant improvement in maneuvering precision and control adaptability. This study demonstrates the potential of reinforcement-learning algorithms in advancing autonomous UAV operations by bridging the gap between dynamic modeling and intelligent control strategies, underscoring the practical benefits of DRL in aerial robotics. Full article
(This article belongs to the Section Aeronautics)
Show Figures

Figure 1

19 pages, 5454 KiB  
Article
Design and Modeling of a High-Peak-Power Distributed Electric Propulsion System for a Super-STOL UAV
by Jia Zong, Zhou Zhou, Jinhong Zhu, Zhuang Shao and Sanya Sun
Drones 2024, 8(12), 761; https://doi.org/10.3390/drones8120761 - 16 Dec 2024
Viewed by 1553
Abstract
Electric short takeoff and landing (eSTOL) aircraft utilize the slipstream generated by distributed propellers to significantly increase the effective lift coefficient and reduce the takeoff and landing distances. By utilizing the blown lift, eSTOL UAVs can achieve similar takeoff and landing site requirements [...] Read more.
Electric short takeoff and landing (eSTOL) aircraft utilize the slipstream generated by distributed propellers to significantly increase the effective lift coefficient and reduce the takeoff and landing distances. By utilizing the blown lift, eSTOL UAVs can achieve similar takeoff and landing site requirements as electric vertical takeoff and landing (eVTOL) UAVs, while having lower takeoff and landing energy consumption and thrust requirements. This research proposes a high-peak-power distributed electric propulsion (DEP) system model and overload design method for eSTOL UAVs to further improve the power and thrust of the propulsion system. The model considers motor temperature factors with the throttle input, which is solved through three-round iterative calculations. The experimental and simulation results indicate that the maximum error of the high-peak-power propulsion unit model without considering temperature is 19.52%, and the maximum error when considering temperature is 1.2%. The propulsion unit ground test indicates that the main factors affecting peak power are the duration of peak power and the temperature limit of the motor. Finally, the effectiveness of the propulsion system model is verified through ground tests and UAV flight tests. Full article
Show Figures

Figure 1

Back to TopTop