Vertical Take-off Research Articles

Preliminary Concept of Urban Air Mobility Traffic Rules

Driven by recent technological breakthroughs, the electric vertical take-off and landing (eVTOL) aircraft has gained considerable attention. The widespread demand for eVTOL aircraft can be attributed to their potential use in the commercialisation of urban air mobility (UAM) in low-altitude urban airspaces. However, the urban low-altitude airspace environment is complex. UAM has a high traffic density and the eVTOL aircraft specifications are not uniform. Particularly in commercial scenarios, controlling eVTOL aircraft and ensuring safety in UAMs are the two major problems that should be addressed in future studies. The design of reasonable traffic rules is a potential solution; hence, we organised a UAM traffic rule system and proposed several alternative UAM traffic rules from three perspectives: a single eVTOL aircraft, a certain route, and key control areas. In addition, we validated these traffic rules using multi-rotor and fixed-wing eVTOL aircraft. The results show that designing reasonable traffic rules can facilitate attaining the primary objectives of commercialisation of UAM.

Launching a meteorological rocket as an instructive object of computer simulation in the school informatics course

Since the first Russian school textbook on computer science edited by A. P. Ershov and V. M. Monakhov came out in 1985, the subject of “Computer simulation and computer experiment” has been explored through the simulation of physical processes unfolding in time and accessible to direct observation in many textbooks on Informatics. For such processes, the idea of temporal discretization can be introduced visually with the help of the videotaping metaphor. Russian Informatics textbooks examined a small oscillation of a load on a spring, water flowing out of a cubic tank, a fall of a person without a parachute (“delayed jump”) in the atmosphere considering air resistance as well as the flight of a small object thrown by a person disregarding air resistance as physical processes simulated by computer programs. These examples are informative, but they do not contain any unobvious conclusions that cannot be reached without computer simulation. The article suggests a more attractive simulation object for the school Informatics course, namely the process of vertical takeoff of a one-stage rocket delivering scientific equipment to the upper air of the Earth and the adjacent near-Earth space. Such rockets are called meteorological. The proposed computer simulation object is good because computer experiments with a developed model make it possible to obtain new results. These include designing a rocket whose maximum lift height paradoxically grows with an increase in the payload as well as showing that the lift height of one-stage meteorological rockets could be significantly increased if we only learned to stop the rocket engine for a few seconds during acceleration.

Agile Fixed-Wing UAVs for Urban Swarm Operations

Fixed-wing unmanned aerial vehicles (UAVs) offer significant performance advantages over rotary-wing UAVs in terms of speed, endurance, and efficiency. Such attributes make these vehicles ideally suited for long-range or high-speed reconnaissance operations and position them as valuable complementary members of a heterogeneous multi-robot team. However, these vehicles have traditionally been severely limited with regards to both vertical take-off and landing (VTOL) as well as maneuverability, which greatly restricts their utility in environments characterized by complex obstacle fields (e.g., forests or urban centers). This paper describes a set of algorithms and hardware advancements that enable agile fixed-wing UAVs to operate as members of a swarm in complex urban environments. At the core of our approach is a direct nonlinear model predictive control (NMPC) algorithm that is capable of controlling fixed-wing UAVs through aggressive post-stall maneuvers. We demonstrate in hardware how our online planning and control technique can enable navigation through tight corridors and in close proximity to obstacles.We also demonstrate how our approach can be combined with onboard stereo vision to enable high-speed flight in unknown environments. Finally, we describe our method for achieving swarm system integration; this includes a gimballed propeller design to facilitate automatic take-off, a precision deep-stall landing capability, multi-vehicle collision avoidance, and software integration with an existing swarm architecture.

Investigating the influence of drone flight on the stability of cancer medicines.

Monoclonal Antibodies (mAbs) are being used in the treatment of both malignant and non-malignant diseases and whilst highly effective, certain products have very short expiry times. Clinical deterioration and supply chain disruption can often lead to wastage and there is a need to reduce this by improving efficiency in logistics practices between manufacturing sites and administration locations. This study aimed to investigate the influence of drone flight on the stability of cancer medicines. Clinically expired, premanufactured monoclonal antibodies (mAbs) were investigated, contained inside instrumented Versapaks, and flown in a Skylift (Mugin) V50 vertical take-off and landing drone through seven phases of flight, (take-off, hover, transition, cruise, transition, hover, and landing). Storage specifications (2-8°C) were met, and any vibrations emanating from the drone and transmitted through the packaging during flight were monitored using accelerometers. Vibration occurred largely above 44 Hz which was consistent with rotor speeds during operation and was significantly greater in amplitude during transition than in forward flight or in hover. Bench experiments validated assurance practices, exploring the edge-of-quality failure by applying extremes of rotational vibration to the mAbs. Aggregation and fragmentation represented a loss of quality in the mAbs and would pose a risk to patient safety. No significant difference was identified in the aggregation and fragmentation of all flown mAbs samples, indicating structural integrity. Flown mAbs in their infusion bags had similar particle sizes compared to controls, (Bevacizumab 11.8±0.17 nm vs. 11.6±0.05 nm, Trastuzumab 11.2±0.05 nm vs. 11.3±0.13 nm, Rituximab 11.4±0.27 nm vs. 11.5±0.05 nm) and aggregate content (Bevacizumab 1.25±0.03% vs 1.32±0.02% p = 0.11, Trastuzumab 0.15±0.06% vs. 0.16±0.06% p = 0.75, Rituximab 0.11±0.02% vs. 0.11±0.01% p = 0.73). The quality of the three mAbs was assured, suggesting that the V50 drone did not induce sufficient levels of vibration to adversely affect their quality.

Rapid Blade Shape Optimization for Contra-Rotating Propellers for eVTOL Aircraft Considering the Aerodynamic Interference

The rising interest in the evolvability of electric vertical takeoff and landing (eVTOL) promises substantial potential in the field of urban air mobility (UAM). Challenges in energy storage density and geometry restriction both emphasize the propeller efficiency for endurance and takeoff weight, whereas the contra-rotating propellers (CRP) advantage is balancing high thrust and efficiency over a single propeller. The aim of this paper is twofold: (i) to present a novel rapid CRP blade shape optimization framework and (ii) to study the impact of the dual propellers revolution speed allocations on the overall CRP power efficiency. The core of the framework is the blade element momentum theory (BEMT)-based blade shape optimization considering the wake effect of the upper propeller by the rotational CFD (computational fluid dynamics) actuator-disc simulation method. The results show that for the same thrust, the optimized CRP at the equal revolution speed is superior to the original (upper-lower-identical) one by 5.9% in thrust-to-power ratio. The overall efficiency can be additionally lifted by 5.3% when the dual propellers share similar torques. By excluding the integral propeller CFD simulation and empirical parameters estimation, the framework enables the swift obtaining of an optimized CRP scheme while maintaining robustness as well.

Thrust Vectoring Control of a Novel Tilt-Rotor UAV Based on Backstepping Sliding Model Method.

In this paper, a control method of a novel tilt-rotor UAV with a blended wing body layout is studied. The novel UAV is capable of vertical take-off and landing and has strong stealth capabilities that can be applied to carrier-borne reconnaissance aircraft. However, the high aspect ratio of blended wing body UAVs leads to a wingtip or oar-tip touchdown problem when adopting the conventional position-attitude control (CPAC) scheme with a large crosswind disturbance. Moreover, when the UAV is subject to interference during reconnaissance, aerial photography, and landing missions, the conventional scheme cannot provide both attitude stability and track accuracy. First, a direct thrust vectoring control (DTVC) scheme is proposed. The control authority of the rotor tilt mechanism was added to enable the decoupling of the attitude and trajectory and to improve the response rate and response bandwidth of the flight trajectory. Second, considering the problems of strong couplings and parameter uncertainties and the nonlinear features and mismatched perturbations that are inevitable in the tilt-rotor, we designed a robust UAV controller based on the backstepping sliding mode control method and determined the stability of the control system through the Lyapunov function. Finally, in the case of crosswire interference during vertical takeoff and landing and the aerial photography missions of the UAV, the numerical simulation of the CPAC scheme and the DTVC scheme was carried out, respectively, and the Monte Carlo random test method was introduced to conduct the statistical test of the landing accuracy. The simulation results show that the DTVC scheme improves the landing accuracy and speed compared to the CAPC scheme and decouples the position control loop from the attitude control loop, finally enabling the UAV to complete the flight control in the VTOL phase.

Flight simulation from takeoff to yawing of eVTOL airplane with coaxial propellers by fluid-rigid body interaction

In this study, we adopt a coupled fluid-rigid body simulation using the moving computational domain method and multi-axis sliding mesh method for the takeoff, hovering, and yawing flight of an electric vertical takeoff and landing aircraft (eVTOL). The aircraft model has four pairs of coaxial propellers, and the computational domain is divided into three domains to move the aircraft and eight propeller domains to rotate the propellers. As a result, we clarify the behavior and aerodynamic force of the aircraft when the input values are determined by the automatic control. The results in the flow field also show that the downwash spreads in a crisscross pattern on the ground, the wind reaches different ranges on the ground depending on the flight altitude, and that the coaxial propeller causes an asymmetry in the velocity field during yawing. Consequently, we conclude that this method is effective for the flight simulation of an eVTOL.

The MPU RX-4 Project: Design, Electronics, and Software Development of a Geofence Protection System for a Fixed-Wing VTOL UAV

Unmanned aerial vehicles (UAVs) are at the forefront of this century’s technological shift, becoming ubiquitous in research and market areas. However, as a UAV navigates autonomously, there are unanticipated occasions, e.g., collisions with dynamic obstacles or loss of data provided by the global navigation satellite system (GNSS), where the aircraft has to change its mission plans. In particular, to be protected from possible accidents, the platform’s geofence protection system should adjust the trajectory appropriately when obstacles are detected and select the proper ground surface when emergency landing is prompted. As these processes require fast reaction times, utilizing low latency sensors and algorithms is necessary. This article proposes a complete and low-complexity geofence protection system for recognizing moving objects and assessing the ground surface’s suitability using onboard sensing and processing modules. The proposed system is implemented on a novel fixed-wing UAV, designated as MPU RX-4, which features an unconventional flying wing layout and vertical take-off and landing (VTOL) capabilities. Our system is based on a forward-facing laser imaging, detection, and ranging (LIDAR) sensor and three downward-facing laser rangefinders. We take advantage of the high-precision distance measurements and operational speed to identify moving obstacles using the LIDAR module, while the ground’s slope and the existence of any obstacle therein are computed through the rangefinders. First, the article describes the UAV design procedure and its aerodynamic performance characteristics, which allowed us to evaluate our approach on a testbed aircraft. Then, the evaluation protocol shows that our system can perform robustly and under real-time constraints reaching an overall latency of only 165.5 ms, sufficient for reliable detection and avoidance of moving obstacles.

ПОДЗАРЯДКА БЕСПИЛОТНЫХ ЛЕТАТЕЛЬНЫХ АППАРАТОВ С ВЕРТИКАЛЬНЫМ ВЗЛЕТОМ-ПОСАДКОЙ НА КОНТАКТНЫХ ПЛАТФОРМАХ С АДАПТИРУЕМОЙ ШИРИНОЙ КОНТАКТНЫХ ПОЛОС

Relevance The article describes one of the modifications of ground charging platforms for electric unmanned aerial vehicles (UAVs) with vertical takeoff and landing (VTOL). It belongs to the class of charging platforms with open pads. The previously described platforms with coplanar band parallel electrodes (CBPE) have multiple parallel strip electrodes with alternating polarity, isolated from each other by narrow dielectric separators. The corresponding on-board electrodes of the multi-rotor UAV with a symmetrical frame are proposed to be arranged at the ends of the support legs under the bearing beams of the engine-propeller groups. Thus, the contact points for the quadrocopter will be at the vertices of the square. With certain geometric relationships between the width of the ground electrodes and the interelectrode distances of the on-board electrodes for any UAV position on the platform, almost 100% different polarities of the on-board electrodes is ensured after landing, and as a consequence, the ability to bring the voltage from the ground DC source to the on-board battery charger. The advantages of such platforms are: relative simplicity of design, independence of maintenance from the accuracy of landing and the ability to charge several UAVs at the same time. However, UAVs may have various sizes and therefore various interelectrode distances, which may violate the condition of different polarities of on-board electrodes after landing. Therefore, it is important to find a solution in which reliable service of the CBPE platform for UAVs of different sizes is possible. Aim of research Finding a technical solution for adaptive band width change of a CBPE landing platform that allows charging UAVs of different sizes. Research methods Prototyping the adaptable CBPE platform and pilot study of its operation. Results The proposed modification of the platform consists in arranging the switching of bands in such a way that alternating groups of bands of one polarity are formed. Bands can be grouped into 1, 2, 3, 4, etc. Such a group works as a single band of appropriate width, which can be changed discretely. In this way, it is possible to adapt the width of the platform stripes depending on the type of vehicle coming for landing. An experimental landing platform for multicopters and a variant of implementing a commuting device for platform adaptive configuration are described.

Robust Adaptive Control with Reduced Conservatism for a Convertible UAV

This work proposes a robust adaptive mixing controller to achieve trajectory tracking throughout the full-flight envelope, with ensured stability, of a quad-tiltorotor convertible plane (CP) vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV), here called QuadCP-VTOL UAV. Accordingly, a nonlinear multi-body dynamic model is obtained using the Euler-Lagrange formalism, from which a linear parameter-varying (LPV) model is derived to describe the dynamics of the QuadCP-VTOL UAV within its flight envelope. The set containing the UAV's flight envelope is partitioned into subsets and, for each subset, a less conservative formulation of the linear robust mixed H2/H∞ candidate controller is proposed. An adaptive mixing scheme is employed to perform a convex combination of the candidate controllers within the subsets intersection. Results of Hardware-In-the-Loop (HIL) experiments are presented to corroborate the efficacy of the proposed control strategy.

Model-Free Distributed Reinforcement Learning State Estimation of a Dynamical System Using Integral Value Functions

One of the challenging problems in sensor network systems is to estimate and track the state of a target point mass with unknown dynamics. Recent improvements in deep learning (DL) show a renewed interest in applying DL techniques to state estimation problems. However, the process noise is absent which seems to indicate that the point-mass target must be non-maneuvering, as process noise is typically as significant as the measurement noise for tracking maneuvering targets. In this paper, we propose a continuous-time (CT) model-free or model-building distributed reinforcement learning estimator (DRLE) using an integral value function in sensor networks. The DRLE algorithm is capable of learning an optimal policy from a neural value function that aims to provide the estimation of a target point mass. The proposed estimator consists of two high pass consensus filters in terms of weighted measurements and inverse-covariance matrices and a critic reinforcement learning mechanism for each node in the network. The efficiency of the proposed DRLE is shown by a simulation experiment of a network of underactuated vertical takeoff and landing aircraft with strong input coupling. The experiment highlights two advantages of DRLE: i) it does not require the dynamic model to be known, and ii) it is an order of magnitude faster than the state-dependent Riccati equation (SDRE) baseline.

Development and testing of vertical take-off and landing aerial vehicle with tandem electric ducted fan motor

Development and testing of vertical take-off and landing aerial vehicle with tandem electric ducted fan motor

Optimal Transition Trajectory of a Quadrotor Biplane Tailsitter

This work focuses on transition trajectory generation for a special class of hybrid vertical takeoff and landing (VTOL) vehicles called quadrotor biplane tailsitter. The transition refers to the change of flight modes for a hybrid VTOL vehicle. A transition maneuver is challenging as the vehicle undergoes in low-speed high angle of attack condition which is highly unstable. This work proposes methods to generate an optimal trajectory for the forward transition of the vehicle. A simplified 3-degree-of-freedom (3-DOF) model of the vehicle is considered for generating the transition trajectory. The optimization problem is solved using nonlinear programming with appropriate dynamic and physical constraints. The work considers multiple optimality conditions that include minimal control effort, minimal transition time, and a combination of them. The results of different approaches are compared considering the feasibility of implementation on a physical vehicle.

ՈՒՂՂԱՁԻԳ ՎԵՐԹԻՌՈՎ ԵՎ ՎԱՅՐԷՋՔՈՎ ԱԹՍ-Ի ԿԻՆԵՄԱՏԻԿ ՎԵՐԼՈՒԾՈՒԹՅՈՒՆԸ ԵՎ ԿԱՌԱՎԱՐՄԱՆ ՀԱՄԱԿԱՐԳԻ ՆԱԽԱԳԾՈՒՄԸ MATLAB SIMULINK ՄԻՋԱՎԱՅՐՈՒՄ / KINEMATICS ANALYSIS AND CONTROL SYSTEM DESIGN OF VERTICAL TAKE-OFF AND LANDING UAV IN MATLAB SIMULINK ENVIRONMENT

The kinematic structure was designed for a new type of pitch-decoupled vertical take-off and landing UAV (VTOL UAV), based on which the equations and matrix describing its kinematics were derived. The kinematics equations were derived based on Denavit-Hartenberg’s method for robot manipulators, considering the VTOL UAV as a robotic system and its connections as kinematic connection links of the robot. A reference frame was assigned to each of the separate links, from which the transition to the coordinate system of the next link was described by a homogeneous transformation matrix. For each link, its position with respect to its own reference frame was calculated. Based on that, the kinematics matrix was derived, which allows for calculating the required torques of the UAV. In the MATLAB SIMULINK environment, an UAV control system was designed that is based on the kinematic matrix and linear, rotational motion dynamics equations. To check the system’s operability, a proportional, Integral-Derivative (PID) regulator with pre-selected coefficients was selected as a regulator. System research was carried out with pitch, roll, yaw, and decoupled pitch axes as well as height axis.

О ПРОЕКТИРОВАНИИ И ОРГАНИЗАЦИИ ПРОИЗВОДСТВА БПЛА ГРАЖДАНСКОГО НАЗНАЧЕНИЯ В КНИТУ-КАИ

The article is devoted to the study of issues of organization of research in the field of design and organization of production of civil UAVs. The authors note that the use of UAVs significantly reduces the cost of complex and labor-intensive work. With the development of technologies in this area, it becomes necessary to systematically study and analyze the results of ongoing research. The article focuses on the key problems and factors that determine the success of projects in this area. The authors emphasize that the UAV sector is competitive and dynamic, so the approaches and methods for evaluating the effectiveness of R&D should be adaptable and flexible. Understanding the peculiarities of evaluating the effectiveness of R&D in the field of designing and organizing the production of UAVs is important for making decisions on the allocation of resources and investments. The importance of the scientific school of KNRTU-KAI in the creation of modern Russian UAVs is noted. So, a scientific group consisting of Gainutdinov V.G., Abdullin I.N., Golovina E.S. A.V. a patent for a utility model "Modular design of a vertical takeoff and landing unmanned aerial vehicle with a combined power plant" was obtained. The authors reflected the advantages and disadvantages of existing VTOL UAVs, as well as the problem of lack of piloting skills among potential users. As part of the article, the authors developed a sales plan, a calendar plan, and also calculated the effectiveness of full investment costs over 5 years of project implementation.

Finally, an eVTOL You Can Buy Soonish: Opener's BlackFly is the first of a radical new class of automated ultralight fliers

If electric vertical takeoff and landing aircraft do manage to revolutionize transportation, the date of 5 October 2011, may live on in aviation lore. That was the day when a retired mechanical engineer named Marcus Leng flew a home-built eVTOL across his front yard in Warkworth, Ont., Canada, startling his wife and several of his friends.

A reference model to visualize and deepen discussions on emergency medical services electric vertical takeoff and landing aircraft

A reference model to visualize and deepen discussions on emergency medical services electric vertical takeoff and landing aircraft

Aerodynamic Study and Design of Fixed Wing and Multi-copter Combination

This project aims to design a hybrid drone with fixed wing for the stable cruising as well as multi-copters for the vertical take-off and landing (VTOL) operations. Drones are utilized for number of applications leading from transportation to the surveillance purposes. Some drones are popular for their stable operation, while other for optimum landing and takeoff. Therefore, numerical analysis was performed on propeller, landing gear as well as on whole structure of the drone. The observed result from CFD analysis show that the velocity distribution had maximum velocity of 40 m/s at the mid span of the drone. In addition, the maximum stress obtained was on the landing gear with approximate value of 185 MPa which is due to the weigh and payload of the drone. The final model was built after the analytical and numerical analysis in order to achieve sustainable and reliable prototype.

Estimation of Airflow Parameters for Tail-Sitter UAV through a 5-Hole Probe Based on an ANN

Fixed-wing vertical take-off and landing (VTOL) UAVs have received more and more attention in recent years, because they have the advantages of both fixed-wing UAVs and rotary-wing UAVs. To meet its large flight envelope, the VTOL UAV needs accurate measurement of airflow parameters, including angle of attack, sideslip angle and speed of incoming flow, in a larger range of angle of attack. However, the traditional devices for the measurement of airflow parameters are unsuitable for large-angle measurement. In addition, their performance is unsatisfactory when the UAV is at low speed. Therefore, for tail-sitter VTOL UAVs, we used a 5-hole pressure probe to measure the pressure of these holes and transformed the pressure data into the airflow parameters required in the flight process using an artificial neural network (ANN) method. Through a series of comparative experiments, we achieved a high-performance neural network. Through the processing and analysis of wind-tunnel-experiment data, we verified the feasibility of the method proposed in this paper, which can make more accurate estimates of airflow parameters within a certain range.

Observer-based controller for VTOL-UAVs tracking using direct Vision-Aided Inertial Navigation measurements

This paper proposes a novel observer-based controller for Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV) designed to directly receive measurements from a Vision-Aided Inertial Navigation System (VA-INS) and produce the required thrust and rotational torque inputs. The VA-INS is composed of a vision unit (monocular or stereo camera) and a typical low-cost 6-axis Inertial Measurement Unit (IMU) equipped with an accelerometer and a gyroscope. A major benefit of this approach is its applicability for environments where the Global Positioning System (GPS) is inaccessible. The proposed VTOL-UAV observer utilizes IMU and feature measurements to accurately estimate attitude (orientation), gyroscope bias, position, and linear velocity. Ability to use VA-INS measurements directly makes the proposed observer design more computationally efficient as it obviates the need for attitude and position reconstruction. Once the motion components are estimated, the observer-based controller is used to control the VTOL-UAV attitude, angular velocity, position, and linear velocity guiding the vehicle along the desired trajectory in six degrees of freedom (6 DoF). The closed-loop estimation and the control errors of the observer-based controller are proven to be exponentially stable starting from almost any initial condition. To achieve global and unique VTOL-UAV representation in 6 DoF, the proposed approach is posed on the Lie Group and the design in unit-quaternion is presented. Although the proposed approach is described in a continuous form, the discrete version is provided and tested.