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Implementing algorithms purely on digital computing platforms dramatically halts the performance of conventional computing systems. Revolutionary computing systems with extreme energy efficiency and high accuracy are demanded to handle the growing computing tasks. Here, the research on hybrid analog–digital computing platforms enabled by memristor‐based optimization solvers for achieving ultrafast computations is presented. By utilizing tunable memristors as parameters to solve linear programming (LP) and quadratic programming (QP) problems, a real‐time control algorithm for micro air vehicles (MAVs) and a support vector machine (SVM) algorithm for cancer diagnosis are implemented. These experiments demonstrate over 2000x speed‐up compared to conventional digital platforms, with negligible energy consumption, using a memristor‐based system consisting of six memristors. These findings underscore the vast potential of memristor‐based optimization solvers not only in hybrid analog–digital computing platforms but also as a transformative solution for a wide range of modern computing challenges. This approach promises significant advancements in energy efficiency and ultrafast speed, positioning it as a leading contender for next‐generation computing paradigms. [ABSTRACT FROM AUTHOR]

In this work, micro air vehicles (MAVs) equipped with bio-inspired wings are investigated experimentally in wind tunnel. The starting point is that insects such as dragonflies, butterflies and locusts have wings with rigid tubular elements (corrugation) connected by flexible parts (profiling). So far, it is important to understand the specific aerodynamic effects of corrugation and profiling as applied to conventional wings for the optimization of low-Reynolds-number aerodynamics. The present study, in comparison to previous investigations on the topic, considers whole MAVs rather than isolated wings. A planform with a low aperture-to-chord ratio is employed in order to investigate the interaction between large tip vortices and the flow over the wing surface at large angles of incidence. Comparisons are made by measuring global aerodynamic loads using force balance, specifically drag and lift, and detailed local velocity fields over wing surfaces, by means of particle image velocimetry (PIV). This type of combined global–local investigation allows describing and relating overall MAV performance to detailed high-resolution flow fields. The results indicate that the combination of wing corrugation and profiling gives effective enhancements in performance, around 50%, in comparison to the classical flat-plate configuration. These results are particularly relevant in the framework of low-aspect-ratio MAVs, undergoing beneficial interactions between tip vortices and large-scale separation. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive numerical investigation into the nonlinear dynamics of Dipteran-inspired flapping flight systems at low Reynolds numbers, with the goal of advancing micro aerial vehicle (MAV) design. Using a forced Duffing oscillator model to represent the wing's structural dynamics and an in-house Navier–Stokes solver based on the immersed boundary method for aerodynamic forces, we capture the intricate fluid–structure interactions (FSI) of the system. Our results reveal insights into the stability and chaotic behavior of the flapping wing system, emphasizing the critical role of viscous effects. The complex interplay between the wing's nonlinear response and aerodynamic loads leads to diverse oscillatory patterns and transitions to chaos. By varying the actuation force as a bifurcation parameter, the system transitions from periodic behavior to sustained chaos through intermediate quasi-periodic and transient chaotic states. These findings highlight the importance of accurately modeling FSI to enhance MAV performance, providing valuable insights into their design and for stability and maneuverability in bio-inspired flapping flight systems. [ABSTRACT FROM AUTHOR]

Conventional micro aerial vehicles (MAVs) have primarily relied on complex, flapping-wing mechanisms for propulsion, often exhibiting limitations in terms of reliability and efficiency. To overcome these challenges, this study explores the potential of electroaerodynamic (EAD) thrusters as a novel propulsion system. By accelerating air molecules through ion collisions, EAD jet flow generates thrust, offering advantages such as noiseless operation and zero emissions due to its moving-part-free design. This research presents a comprehensive experimental and numerical investigation of a wire-to-two-drop thruster configuration to elucidate its electromechanical performance, plasma flow dynamics, and EAD jet characteristics. Experimental measurements of key parameters, including current, thrust, power, and effectiveness, were correlated with numerical simulations, demonstrating excellent agreement with a maximum error below 5%. These findings align strongly with established theoretical frameworks, revealing an inverse square root relationship between effectiveness and thrust. To optimize thruster performance, optimal operating voltages were identified at approximately 8.2, 9.4, and 11.6 kV for inter-electrode gap distances of 10, 15, and 20 mm, respectively, achieving a balanced trade-off between thrust and effectiveness. Detailed numerical visualizations of the plasma flow field, including velocity distribution, jet morphology, potential distribution, and electric field lines, provided valuable insights into the thruster's operation. Building upon these insights, a proof-of-concept EAD flier was constructed and tested, incorporating a serrated emitter electrode and lightweight materials. This flier achieved a mass of 0.5 g and generated a thrust of 0.77 g at 15 kV, resulting in a thrust-to-weight ratio of 1.54 and successful liftoff. This demonstration highlights the potential of EAD propulsion for practical MAV applications. [ABSTRACT FROM AUTHOR]

Dragonflies exhibit outstanding performance in flight due to their exceptional flying capabilities. However, micro air vehicles developed based on biomimetics principles fall far short of dragonflies in terms of maneuverability. To investigate the ability of dragonflies to change flight states per unit time during synchronized-stroking, this study first takes the dragonfly as the biological observation subject. Based on the acquired biological characteristics, a geometric model required for numerical simulation is established. Combined with the dynamic observation results and flapping patterns of the dragonfly, a systematic analysis of the aerodynamic performance and surrounding flow field structure during maneuvering flight at different flapping frequencies is conducted. The results indicate that changes in the dragonfly's flapping frequency have a significant impact on lift and roll moment, while the impact on pitch moment and lateral force is minimal, varying only within the range of 10%–20% with a frequency increase in 5 Hz. Even with the same flapping frequency in the left and right wings, a residual pitch moment of up to 18.5 mN mm remains, causing the dragonfly's body to oscillate back and forth. By changing the flapping frequency of one wing, the dragonfly can achieve maneuvering turns to the opposite side. During the entire downstroke, the fluid around the wings generates additional circulation due to rotational effects, which is more beneficial for maneuvering takeoff. During the upstroke, the trailing-edge vortices shed significantly, creating a large pressure difference between the forewing and hindwing surfaces, which is more conducive to forward maneuvering flight. [ABSTRACT FROM AUTHOR]

The current study analyzed the piezoelectrically driven mechanism responsible for generating force in both rectangular and hummingbird wings, which mimicked the flapping motion of the micro air vehicles, utilizing a combination of numerical simulation and experimental approaches. Digital image correlation technology was employed within the experimental setup to capture the dynamic deformation pattern of the flapping wing, yielding dynamic deformation data. This dataset was subsequently integrated into the computational fluid dynamics (CFD) simulation software to explain the aeroelastic effects. In this way, the dynamic deformation data played a crucial role in computing inertial forces regarding wing flexibility. In addition, temporal force variations generated by the flapping wing were measured using a load cell. The numerical results provided a full understanding of the flapping wing's unsteady aerodynamics, with an emphasis on vortex formations and pressure distribution. We thoroughly examined the force produced by the piezo-actuated flapping wing system. This analysis was then rigorously compared with the data obtained from the load cell measurements. Our primary emphasis was on the vertical forces along the z-axis. Moreover, a thorough comparison of the combined CFD and experimental data inertial results revealed an overall agreement in the total forces from the load cell. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative approach for optical flow-based control of micro air vehicles (MAVs), addressing challenges inherent in the nonlinearity of optical flow observables. The proposed incremental nonlinear dynamic inversion (INDI) control scheme employs an efficient data-driven approach to directly estimate the inverse of the time-varying INDI control effectiveness in real-time. This method eliminates the constant effectiveness assumption typically made by traditional INDI methods and reduces the computational burden associated with inverting this variable at each time step. It effectively handles rapidly changing system dynamics, often encountered in optical flow-based control, particularly height-dependent control variables. Stability analysis of the proposed control scheme is conducted, and its robustness and efficiency are demonstrated through both numerical simulations and real-world flight tests. These tests include multiple landings of an MAV on a static, flat surface with several different tracking setpoints, as well as hovering and landings on moving and undulating surfaces. Despite the challenges posed by noisy optical flow estimates and lateral or vertical movements of the landing surfaces, the MAV successfully tracks or lands on the surface with an exponential decay of both height and vertical velocity almost simultaneously, aligning with the desired performance. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative autonomous survivor detection pipeline tailored for low‐cost micro aerial vehicles (MAVs) operating in post‐disaster indoor environments. This consists of three main components: (1) a novel pipeline for survivor geotagging, which includes autonomous navigation, mapping, and detection of survivors using thermal images; (2) a navigation strategy to ensure complete thermal scanning coverage for survivor detection using low‐cost commercial grade thermal camera; and (3) robust and accurate survivor detection using YOLOv8x and thermal imaging. To demonstrate the effectiveness of the proposed framework, first, the autonomous navigation algorithm is simulated in Robotic Operating System (ROS) and experimentally validated under different layouts. Second, the YOLOv8x algorithm is pretrained and achieves high accuracy. Finally, a real‐world implementation was conducted with partially covered survivors in a simulated post‐disaster environment. The results demonstrated the proposed pipeline can accurately map the layout of the environment and identify all survivors. This study demonstrates that affordable MAVs with basic thermal cameras can be effectively used to geotag survivors to support rescue missions during post‐disaster events. [ABSTRACT FROM AUTHOR]

A two-dimensional body that moves suddenly in a viscous fluid can instantly generate vortices at its sharp edges. Recent work using inviscid flow theory, based on the Birkhoff–Rott equation and the Kutta condition, predicts that the 'starting vortices' generated by the sharp and straight edges of a body – i.e. the vortices formed immediately after motion begins – can be one of three distinct self-similar types. We explore the existence of these starting vortices for a flat plate and two symmetric Joukowski aerofoils immersed in a viscous fluid, using high-fidelity direct numerical simulations (DNS) of the Navier–Stokes equations. A lattice Green's function method is employed and simulations are performed for chord Reynolds numbers ranging from 5040 to 45 255. Vortices generated at the leading and trailing edges of the flat plate show agreement with the derived inviscid theory, for which a detailed assessment is reported. Agreement is also observed for the two symmetric Joukowski aerofoils, demonstrating the utility of the inviscid theory for arbitrary bodies. While this inviscid theory predicts an abrupt transition between the starting-vortex types, DNS shows a smooth transition. This behaviour occurs for all Reynolds numbers and is related to finite-time effects – there is a maximal time for which the (self-similar) starting vortices exist. We confirm the inviscid prediction that the leading-edge starting vortex of a flat plate can be suppressed dynamically. This has implications for the performance of low-speed aircraft such as model aeroplanes, micro air vehicles and unmanned air vehicles. [ABSTRACT FROM AUTHOR]

In this study, a thermomechanical rigid-flexible coupling vibration model of the rotating pre-twisted porous functionally graded (PP-FG) thick microplate in a thermal environment is established based on the third-order shear deformation theory (TSDT) and modified couple stress theory (MCST). Three thermal distributions are considered. The effects of temperature and porosity on the equivalent material parameters are accounted for in the modified Voigt rule of mixture. The governing equations of motion are derived using the Euler–Lagrange equation and numerically solved through the complex modal analysis method and the Chebyshev–Ritz method. After validating the convergence and accuracy of the proposed model, the effects of temperature, material length scale parameter (MLSP), rotational speed, porosity index, gradient index, presetting angle, and pre-twist angle on the vibration behavior of microplates were examined. The key findings of the study are as follows: (1) The effects of rotational speed on in-plane and out-of-plane frequencies are opposite. Temperature elevation weakens the size effect and centrifugal stiffening effect on the frequencies. (2) The effects of the porosity index on the frequencies are the opposite when the gradient index exceeds a specific critical value. (3) The effects of the presetting angle on the frequencies are periodic and symmetrical at about 0. The frequencies reach an extreme value when the pre-twist angle is approximately 2π/3 for the cantilever microplate. The proposed model is more sophisticated and comprehensive than others reported in the literature. It offers a more thorough analysis and insight into the behavior and performance of micro-electro-mechanical systems (MEMS) and micro air vehicles (MAVs), particularly when operating in challenging conditions. [ABSTRACT FROM AUTHOR]

This study aimed to enhance the stability and response speed of a passive stabilized double-wing flapping micro air vehicle (FMAV) by implementing a feedback-controlled biomimetic tail. A model for flapping wings accurately calculated the lift force with only a 2.4% error compared to the experimental data. Experimental tests established the relationship between control torque and tail area, swing angle, and wing–tail spacing. A stability model for the double-wing FMAV was developed, incorporating stabilizing sails. Linearization of the hovering state facilitated the design of a simulation controller to improve response speed. By adjusting the feedback loops of velocity, angle, and angular velocity, the tail controller reduced the angle simulation response time from 4 s to 0.1 s and the velocity response time from 5.64 s to 0.1 s. In take-off experiments, a passive stabilized prototype with an adjustable tail angle exhibited enhanced flight stability compared to fixed tails, reducing standard deviation by 72.96% at a 0° take-off angle and 56.85% at a 5° take-off angle. The control axis standard deviation decreased by 38.06% compared to the passive stability axis, confirming the effectiveness of the designed tail angle controller in reducing angular deflection and improving flight stability. [ABSTRACT FROM AUTHOR]

Safe Micro Aerial Vehicle (MAV) navigation requires detecting and avoiding obstacles. For safe MAV navigation, expansion‐based algorithms are effective for detecting obstacles. However, accurate and real‐time obstacle detection is a fundamental challenge. Some traditional methods focus on extracting geometric features from images and applying geometric constraints to identify potential obstacles. Others may leverage machine learning algorithms for object detection and classification, using features such as texture, shape, and context to distinguish obstacles from background clutter. The choice of approach depends on factors such as the specific requirements of the application, the complexity of the scene, and the available computational resources. Since obstacles, in reality, take the form of objects (e.g., persons, walls, pillars, trees, automobiles, and other structures), it is preferable to represent them according to human comprehension and as objects. Therefore, the objective of this study is to reflect on the previous research and address the issues mentioned above by extracting objects from the fisheye image using a panoptic deep‐learning network. The extracted object regions are, then, used to identify obstacles with a novel area‐based expansion rate we developed in a previous study. We compared the accuracy of obstacle detection in our proposed method to the existing method when moving forward and to the right; thus, we improved it between 10% and 18%, respectively. In addition, compared with the existing method, and due to replacing a single object with multiple regions, obstacle‐detection runtime for forward and right direction is 15.71 and 25.5 times faster, respectively, and the required match points have decreased by 49% and 55%. [ABSTRACT FROM AUTHOR]

The benefit of real‐world applicable indicators in resolving robust traffic‐related source contributions was investigated using tunnel measurement. PM2.5/CO was introduced as a metric to present evidence in non‐exhaust identification indirectly in terms of PM2.5 accumulation and dilution scenarios, and the rates (hourly variation of the difference between PM2.5 and PM2.5/CO) were 0.59−1.88 and −0.79 to −0.65, corresponding to peak and off‐peak hours, respectively. Real‐world PAHs indicators were examined, among which the exhaust indicators showed stable applicability from BghiP, and the non‐exhaust indication noted by BkF and DahA in peak hours were largely weakened in off‐peak hours, showing noticeable profile mixing between exhaust, brake and tyre wear. Source contributions were resolved by principal component analysis (PCA) with support of linear discriminant analysis (LDA) on inter‐group centroid diagnosis. The rate of vehicular non‐exhaust (brake and tyre wear) contribution lifted 10.3 times in peak hours compared with off‐peak hours, and its emission factor was noticeably enhanced 16 times, from 0.03 mg/(km·veh) to 0.48 mg/(km·veh). Guided by global vehicle electrification, the contribution of non‐exhaust in vehicular emissions were estimated to increase with larger ratio of emission factor between non‐exhaust and exhaust, and the growing market share of electric vehicles, under each mode of regenerative braking. The monetary impact of non‐exhaust caused by electric vehicles was calculated reaching the exhaust when electric vehicles increase to 50% in busy commuting megacities. The results provide applicable indicators for accurate source apportionment and support data for the refined control of non‐exhaust emission under rapid vehicle electrification. Plain Language Summary: Vehicle emitted non‐exhaust has garnered considerable global attention as source of heavy metals, microplastics and emerging pollutants. Real‐world applicable indicators were gained to characterize the benefits of robust and dynamic apportionment between exhaust and non‐exhaust emissions. This study estimated the contributions of non‐exhaust to total vehicle emissions for varying levels of emission factor ratios between non‐exhaust and exhaust and market share of electric vehicle. Key Points: PM2.5/CO can be used as a metric to present evidence of non‐exhaust identification indirectly in typical traffic environmentAccurate indicators were determined and applicability for recognizing exhaust and non‐exhaust was examined under heavy and low trafficFuture contribution of non‐exhaust to total vehicle emissions was predicted by emission factor ratios and electric vehicle percentages [ABSTRACT FROM AUTHOR]

To understand the locomotory mechanisms of flying and swimming animals, it is often necessary to develop assays that enable us to measure their responses to external gust perturbations. Typically, such measurements have been carried out using a variety of gusts which are difficult to control or characterize owing to their inherently turbulent nature. Here, we present a method of generating discrete gusts under controlled laboratory conditions in the form of a vortex rings which are well-characterized and highly controllable. We also provide the theoretical guidelines underlying the design of gust generators for specific applications. As a case study, we tested the efficacy of this method to study the flight response of freely-flying soldier flies Hermetia illucens. The vortex ring based method can be used to generate controlled gusts to study diverse phenomena ranging from a natural flight in insects to the artificial flight of insect-sized drones and micro-aerial vehicles. [ABSTRACT FROM AUTHOR]

For real-world applications, autonomous mobile robotic platforms must be capable of navigating safely in a multitude of different and dynamic environments with accurate and robust localization being a key prerequisite. To support further research in this domain, we present the INSANE datasets (Increased Number of Sensors for developing Advanced and Novel Estimators)—a collection of versatile Micro Aerial Vehicle (MAV) datasets for cross-environment localization. The datasets provide various scenarios with multiple stages of difficulty for localization methods. These scenarios range from trajectories in the controlled environment of an indoor motion capture facility, to experiments where the vehicle performs an outdoor maneuver and transitions into a building, requiring changes of sensor modalities, up to purely outdoor flight maneuvers in a challenging Mars analog environment to simulate scenarios which current and future Mars helicopters would need to perform. The presented work aims to provide data that reflects real-world scenarios and sensor effects. The extensive sensor suite includes various sensor categories, including multiple Inertial Measurement Units (IMUs) and cameras. Sensor data is made available as unprocessed measurements and each dataset provides highly accurate ground truth, including the outdoor experiments where a dual Real-Time Kinematic (RTK) Global Navigation Satellite System (GNSS) setup provides sub-degree and centimeter accuracy (1-sigma). The sensor suite also includes a dedicated high-rate IMU to capture all the vibration dynamics of the vehicle during flight to support research on novel machine learning-based sensor signal enhancement methods for improved localization. The datasets and post-processing tools are available at: https://sst.aau.at/cns/datasets/insane-dataset/ [ABSTRACT FROM AUTHOR]

Installing multi-camera systems and inertial measurement units (IMUs) in self-driving cars, micro aerial vehicles, and robots is becoming increasingly common. An IMU provides the vertical direction, allowing coordinate frames to be aligned in a common direction. The degrees of freedom (DOFs) of the rotation matrix are reduced from 3 to 1. In this paper, we propose a globally optimal solver to calculate the relative poses and scale of generalized cameras with a known vertical direction. First, the cost function is established to minimize algebraic error in the least-squares sense. Then, the cost function is transformed into two polynomials with only two unknowns. Finally, the eigenvalue method is used to solve the relative rotation angle. The performance of the proposed method is verified on both simulated and KITTI datasets. Experiments show that our method is more accurate than the existing state-of-the-art solver in estimating the relative pose and scale. Compared to the best method among the comparison methods, the method proposed in this paper reduces the rotation matrix error, translation vector error, and scale error by 53%, 67%, and 90%, respectively. [ABSTRACT FROM AUTHOR]

Precision agriculture has long struggled with the surveillance and control of pests. Traditional methods for estimating pest density and distribution through manual reconnaissance are often time-consuming and labor-intensive. To address these challenges, this study proposes a novel farmland detection system utilizing UAVs, yellow sticky traps, and deep learning techniques. The system includes a UAV based on UWB communication and positioning technology to collect picture information of sticky traps arranged in farmland. Moreover, a faster and more accurate Qpest-RCNN model is used to count the number of insects in the collected sticky traps. The bivariate kernel density estimation establishes the pest density distribution map. Regarding the dynamic monitoring of pest density in agricultural fields, it primarily involves four components: reaching the designated area, flight learning, image acquisition, and visual counting of insects and calculation of insect density. Experimental results demonstrate that UAVs require less time to adjust flight posture during image acquisition after undergoing flight learning, resulting in more concise flight trajectories. The Qpest-RCNN model introduces a variety of mechanisms based on the characteristics of the collected sticky trap data set to improve the faster-R-CNN model. We used two data sets separately to train the model, which were collected by sticky traps placed in greenhouses and open-air experimental fields. The data set from the greenhouse is an open-source dataset provided by M. Deserno et. al, map, precision, and recall of model are 0.923, 0.989, and 0.919, respectively. When the data set collected in the experimental farmland is used to train the model, map, precision, and recall of model are 0.781, 0.851, and 0.789, respectively. In the meantime, we explored the effects of species interference on visual insect statistics and the optimization effect of species hypothesis on statistics in two environments. At the same time, the inference speed of the improved model is about a quarter faster than the FPS of the original Faster-RCNN during inference. Through Qpest-RCNN, the number of insects captured on sticky traps can be counted quickly and accurately and the bivariate kernel density estimation is used to draw the pest density distribution map to observe the pest distribution of the whole farmland visually. This pest-density farmland detection system is valuable for agriculture by helping farmers control pests, reduce crop damage, and increase yield and quality. [ABSTRACT FROM AUTHOR]

The beetle, of the order Coleoptera, possesses outstanding flight capabilities. After completing flight, they can fold their hindwings under the elytra and swiftly unfold them again when they take off. This sophisticated hindwing structure is a result of biological evolution, showcasing the strong environmental adaptability of this species. The beetle's hindwings can provide biomimetic inspiration for the design of flapping-wing micro air vehicles (FWMAVs). In this study, the Asian ladybird (Harmonia axyridis Pallas) was chosen as the bionic research object. Various kinematic parameters of its flapping flight were analyzed, including the flight characteristics of the hindwings, wing tip motion trajectories, and aerodynamic characteristics. Based on these results, a flapping kinematic model of the Asian ladybird was established. Then, three bionic deployable wing models were designed and their structural mechanical properties were analyzed. The results show that the structure of wing vein bars determined the mechanical properties of the bionic wing. This study can provide a theoretical basis and technical reference for further bionic wing design. [ABSTRACT FROM AUTHOR]

Deployable hind wings of beetles led to a bio-inspired idea to design deployable micro aerial vehicles (MAVs) to meet the requirement of miniaturization. In this paper, a bionic deployable wing (BD-W) model is designed based on the folding mechanism and elliptical wing vein structure of the Protaetia brevitarsis hindwing, and its structural static and aerodynamic characteristics are analyzed by using ANSYS Workbench. Finally, the 3D-printed bionic deployable wing was tested in a wind tunnel and compared with simulation experiments to explore the effects of different incoming velocity, flapping frequency, and angle of attack on its aerodynamic characteristics, which resulted in the optimal combination of the tested parameters, among which, the incoming velocity is 3 m/s, the flapping frequency is 10 Hz, the angle of attack is 15°, and the lift-to-drag ratio of this parameter combination is 4.91. The results provide a theoretical basis and technical reference for the further development of bionic flapping wing for MAV applications. [ABSTRACT FROM AUTHOR]

Under the impetus of national energy-saving and emission-reduction policies, electric vehicles (EVs) are increasingly entering the mainstream automotive market, signaling the gradual decline of the internal combustion engine era. However, the challenge of extending the range of EVs remains substantial. Addressing this core obstacle necessitates a dual approach: advancing battery technology and optimizing aerodynamic performance through streamlined design to reduce drag and enhance driving stability. This approach is crucial for enhancing the competitiveness of car manufacturers, expanding the market penetration of EVs, and supporting environmental sustainability. This study concentrates on pure EVs, employing three-dimensional, steady-state, incompressible fluid mechanics principles alongside advanced FLUENT simulation tools to systematically evaluate the external flow characteristics and overall aerodynamic efficiency of the vehicle. The research integrates streamlined design concepts, implementing micro-level aerodynamic modifications to the vehicle body structure to maximize driving efficiency. By combining precise computational fluid dynamics (CFD) simulations with empirical wind tunnel testing, the direct impact of design changes on the vehicle's aerodynamic performance is meticulously analyzed. Highlights of the research include the utilization of a 1:25 scale accurately scaled 3D printed vehicle model and comprehensive aerodynamic evaluations conducted in a lowspeed wind tunnel laboratory using a direct-current suction-type wind tunnel device. This methodology robustly verifies the accuracy of simulation predictions, providing scientific evidence and practical guidance for further exploring the application of streamlined design in enhancing the aerodynamic performance of EVs. Consequently, this research is expected to accelerate advancements at the technological frontier of the field. [ABSTRACT FROM AUTHOR]

Purpose: Endurance time is an important factor limiting the progress of flapping-wing aircraft. In this study, this paper developed a prototype of a double-wing flapping-wing micro air vehicle (FMAV) that mimics insect-scale flapping wing for flight. Besides, novel methods for optimal selection of motor, wing length and battery to achieve prolonged endurance are proposed. The purpose of this study is increasing the flight time of double-wing FMAV by optimizing the flapping mechanism, wings, power sources, and energy sources. Design/methodology/approach: The 20.4 g FMAV prototype with wingspan of 21.5 cm used an incomplete gear flapping wing mechanism. The motor parameters related to the lift-to-power ratio of the prototype were first identified and analyzed, then theoretical analysis was conducted to analyze the impact of wing length and flapping frequency on the lift-to-power ratio, followed by practical testing to validate the theoretical findings. After that, analysis and testing examined the impact of battery energy density and efficiency on endurance. Finally, the prototype's endurance duration was calculated and tested. Findings: The incomplete gear facilitated 180° symmetric flapping. The motor torque constant showed a positive correlation with the prototype's lift-to-power ratio. It was also found that the prototype achieved the best lift-to-power ratio when using 100 mm wings. Originality/value: A gear-driven flapping mechanism was designed, capable of smoothly achieving 180° symmetric flapping. Besides, factors affecting long-duration flight – motor, wings and battery – were identified and a theoretical flight duration analysis method was developed. The experimental result proves that the FMAV could achieve the longest hovering time of 705 s, outperforming other existing research on double-wing FMAV for improving endurance. [ABSTRACT FROM AUTHOR]

The paper aims to perform numerical simulations of flapping flight using Discrete Vortex Method (DVM) scheme. The scheme is suitable for moderately low Reynolds number (< ∼ 1 0 5) and computationally less expensive as the flow domain doesn't need to be discretized at each time step. Flapping of a one-dimensional (1D) flexible filament in a two-dimensional (2D) inviscid flow is simulated. The effect of bending by varying the wing shape along the spanwise length on aerodynamic performance was studied. It is observed that compared to rigid wings, bending wings are found to be better in generating lift. The effect of various bending wing configurations (F 1 , F 2 , F 3 and F 4) and different methods of imposing the bending (W 1 , W 2 and W 3) is studied. It was demonstrated that applying wing bending only during the downstroke phase (W 2) is more effective than imposing bending throughout the flapping cycle (W 1). Moreover, an effort is made to replicate the bending configuration observed in manta ray fish (W 3) to investigate its impact on flow domain characteristics, lift, and thrust forces. Furthermore, the inclusion of a winglet is found to significantly enhance lift generation. In addition to the study of bending effects on aerodynamic performance, the study also seeks to emulate a unique aspect of bat flight kinematics, specifically the dynamic variation in wing span length during flapping. In a comparative analysis of two span length variation strategies, it is discerned that exclusively varying span length during the upstroke phase is the optimal approach for achieving increased lift generation. The study highlights the crucial role of wing bending and span length modulation in achieving elevated lift forces while simultaneously reducing drag. These findings are seen as holding significant promise for the design and optimization of Micro Air Vehicles (MAVs) utilizing flapping-based lift generation mechanisms, contributing substantially to the identification of optimal parameters for enhancing MAVs' aerodynamic performance and operational efficiency. [ABSTRACT FROM AUTHOR]

A flexible wing micro air vehicle and a rigid wing micro air vehicle, both with flying wing designs, were designed and developed, and the aerodynamic characteristics of the flexible micro air vehicle and the rigid micro air vehicle under steady wind and horizontal gust were studied in a wind tunnel. The difference in aerodynamic characteristics between flexible wing and rigid wing micro air vehicles was given. The research results showed that the aerodynamic characteristics of a flexible wing were better than those of a rigid wing under both steady wind and horizontal gust environments, and a flexible wing had the ability to delay stall and mitigate the impact of gust, which was beneficial to stable flight. The particle image velocimetry measurement results showed that due to the deformation of the flexible wing, the flow patterns on the rigid wing and flexible wing surfaces were different, resulting in changes in the aerodynamic characteristics of micro air vehicles. [ABSTRACT FROM AUTHOR]

Traditional oil seals are insufficient for the high-speed and bi-directional rotation of new energy electric vehicles. Therefore, we developed a Python program focusing on micro-groove pump seals and examined the unexplored non-contact oil–air biphasic internal end-face seals. Real gas effects were described using the virial and Lucas equations. We introduced an oil–air ratio to determine the equivalent density and viscosity of the two-phase fluid in the seal. Furthermore, we solved the compressible steady-state Reynolds equation using the finite difference method. Analysing the seal's pumping mechanisms and the effects of operating parameters on sealing performance, we assessed 17 types of hydrodynamic grooves. The results demonstrate that inverse fir tree-like grooves perform well under typical sealing conditions. Under the conditions given in this study, the pumping rate of the optimal groove type compared to other groove types even reached 633.54%. In the oil–air biphasic state, the micro-groove pump seal exerts significant dynamic pressure on the sealing surface. Seal opening force increases with rotational velocity, oil–air ratio, and inlet pressure but decreases with temperature. The pumping rate first increases and then decreases with rotational velocity, increases with oil–air ratio and temperature, and then decreases with inlet pressure. Some special working points require consideration in sealing design. Our results provide insights into designing micro-grooved pumping seals for new energy electric vehicles. [ABSTRACT FROM AUTHOR]

In the design of flapping-wing micro-size air vehicles capable of hovering, wings serve as the primary source of hovering power, making the analysis of aerodynamics and aerodynamic efficiency crucial. Traditional quasi-steady models treat the wings as single rigid plane, neglecting the deformable characteristics of flexible wings. This paper proposes a multi-plane method that, in conjunction with various design parameters of flexible wings in a two-dimensional plane, analyzes their deformation characteristics under the assumption of multiple planes in three-dimensional space, and describes the deformation of wings during flapping. By combining the quasi-steady aerodynamic model, aerodynamic analysis of the deformed wings can be conducted. The relationship between the slack angle, wing flapping position, and wing deformation are analyzed, along with their effects on aerodynamics and aerodynamic efficiency. Experiments validate the deformation patterns of wings during flapping and compare the simulated aerodynamic forces with measured ones. The results indicate that wing deformation can be accurately described by adjusting the parameters in the multi-plane method and that the aerodynamic analysis using this method closely approximates the average lift results. Additionally, the multi-plane method establishes a connection between wing morphology and aerodynamic forces and efficiency, providing valuable insights for aerodynamic analysis. [ABSTRACT FROM AUTHOR]

There is a significant surge in unmanned aerial vehicles' (UAVs) popularity with an ongoing increase in demand due to their multi-functional uses. The capacity of the UAVs to respond to society and industry needs account for their pervasiveness. UAVs can be strategically deployed to enhance network efficiency and support critical missions, including vital tasks like infrastructure monitoring operations. To be effective, a UAV must interact securely with its network's entities, such as ground control stations, other UAVs, air traffic control systems, and navigation satellite systems. UAVs are exposed to a dangerous and costly world of cyber dangers as a result of cyber technology and connections. The UAV and the Ground Control Station (GCS) exchange information using communication lines, which are vulnerable to cyber-attacks. As a result, detective, defensive, and preventative countermeasures are critical. The Micro Air Vehicle Link (MAVLink) protocol is a widely used lightweight communication protocol for enabling communication between UAVs and GCSs. It outlines communication exchanges between a GCS and a UAV. It carries information about the UAV's condition as well as commands for control from the GCS. Although widely used, the MAVLink protocol lacks sufficient security measures and is susceptible to various types of attacks, which can pose significant risks to public safety. UAV data should be encrypted because they are very sensitive. To give a high level of security, complex operation encryption techniques are developed. These mathematical operations bring forth issues with efficiency and power usage, though. One of these methods, the ChaCha cipher, recently gained popularity after Google used it in several applications. In the current study, a new stream cipher method with low-duty cycles is proposed for protecting data in UAVs and is compared with existing security algorithms on the basis of various factors. The research findings show that by including the suggested method in MAVLink, it is possible to maintain both message secrecy and battery life for a resource-constrained UAV. This can be done while using comparable amounts of memory and CPU and without affecting MAVLink's performance. [ABSTRACT FROM AUTHOR]

Nowadays, trajectory control is a significant issue for unmanned micro aerial vehicles (MAVs) due to large disturbances such as wind and storms. Trajectory control is typically implemented using a proportional–integral–derivative (PID) controller. In order to achieve high accuracy in trajectory tracking, it is essential to set the PID gain parameters to optimum values. For this reason, separate gain values are set for roll, pitch and yaw movements before autonomous flight in quadrotor systems. Traditionally, this adjustment is performed manually or automatically in autotune mode. Given the constraints of narrow orchard corridors, the use of manual or autotune mode is neither practical nor effective, as the quadrotor system has to fly in narrow apple orchard corridors covered with hail nets. These reasons require the development of an innovative solution specific to quadrotor vehicles designed for constrained areas such as apple orchards. This paper recognizes the need for effective trajectory control in quadrotors and proposes a novel neural network-based approach to tuning the optimal PID control parameters. This new approach not only improves trajectory control efficiency but also addresses the unique challenges posed by environments with constrained locational characteristics. Flight simulations using the proposed neural network models have demonstrated successful trajectory tracking performance and highlighted the superiority of the feed-forward back propagation network (FFBPN), especially in latitude tracking within 7.52745 × 10−5 RMSE trajectory error. Simulation results support the high performance of the proposed approach for the development of automatic flight capabilities in challenging environments. [ABSTRACT FROM AUTHOR]

A tandem flapping-fixed airfoil configuration with a narrow gap can be found in insects and micro air vehicles (MAVs). Compared to a single flapping airfoil, the interaction between the two airfoils can bring about a thrust enhancement, whereas it is not sure whether this thrust enhancement can be transformed into an improved lifting capacity via some trade-offs. In this paper, the idea of inclining the stroke plane is adopted, and the aerodynamic performance of this tandem configuration at different stroke plane angles is investigated numerically using the lattice Boltzmann method. Results show that most of the extra thrust is converted into the lift increment at the 75° stroke plane, which proves the feasibility of a trade-off between lifting and propulsion capacity. In addition to the contributions of geometric projection and effective incoming flow, the lift increment also originates from an extra transient lift peak when the flapping airfoil and the fixed airfoil are near their closest locations. This lift peak is attributed to the enlarged low-pressure and high-pressure regions at the rear end of the upper and lower surfaces of the flapping airfoil, the underlying flow physics of which is the formation of a reversed horizontal flow and an upwash between two airfoils. These findings introduce a novel interaction mechanism between an inclined flapping airfoil and a fixed airfoil. Further analysis shows that this mechanism is valid at multiple plunging amplitudes and thus it may be utilized to enhance the lift in a three-dimensional (3D) scenario. Our findings reveal a novel lift-enhancing mechanism by tilting the stroke plane and may promote the design of MAV in this configuration. [ABSTRACT FROM AUTHOR]

This study presents a model experiment method that can accurately reproduce the flapping motion of insect wings and measure related unsteady aerodynamic data in real time. This method is applied to investigate the aerodynamic characteristics of inclined hovering, which distinguishes it from normal hovering by having asymmetric wing rotation during the two half strokes. In the study of the aerodynamic influence of the downstroke rotational angle, it is found that the rotational angle affects lift generation by changing the angle between the wing surface and the horizontal plane in the mid-downstroke. When the wing is almost parallel to the horizontal plane in the mid-downstroke, the vortex structure can maintain structural integrity and a large magnitude, which is conducive to the generation of high lift. In the study of the aerodynamic effect of the upstroke rotational angle, the windward conversion mechanism is proposed to explain the influence of the upstroke rotational angle on the direction and magnitude of thrust. Obtaining the rotational angle that is most conducive to maintaining the flight state of hovering in the present study can provide guidance for the structural design and kinematic control of micro aerial vehicles. [ABSTRACT FROM AUTHOR]

Innovative electric vertical take-off and landing (eVTOL) aircraft designs and operational concepts, driven by advancements in battery and electric motor technologies, seek to achieve superior safety records with increased system redundancy. Validating safe flight operations within the prescribed flight envelope for passenger flights in densely populated urban environments remains a primary challenge. This paper establishes a framework for applying Hamilton-Jacobi reachability analysis to the full six-degree-of-freedom (6-DOF) dynamics of the NASA Tiltwing vehicle, verifying the flight envelope during the flight mode transition between near-hover and cruise flight, which prevents loss of control of the vehicle and ensures recoverability to safe trim conditions. This involves first verifying the nominal flight mode transition path as a series of trim points, defining the safe flight envelope using reachability, and decomposing the system dynamics into longitudinal and lateral subsystems. Our formulation guarantees the computed envelope's robustness against modeling errors and uncertainties, and the usage of state decomposition significantly improves the tractability of the reachability computation. The result is validated through Monte Carlo 6-DOF nonlinear simulation of vehicle dynamics, demonstrating that the vehicle states within the flight envelope can successfully recover to trim states and continue the flight mode transition safely. [ABSTRACT FROM AUTHOR]

This study investigates the aerodynamic behavior of a high-performance vehicle and the interaction with its rear wing in straight-line and steady-state cornering conditions. Analyses are performed with Reynolds-averaged Navier–Stokes based computational fluid dynamics simulations using a moving reference frame and overset mesh technique, validated against moving ground wind tunnel experiments. The results indicate a significant 20% decrease in downforce and 35% increase in drag compared to straight-line conditions at the smallest considered corner radius of 2.9 car-lengths. Downforce losses primarily stem from performance deficits on the underbody and rear wing, alongside elevated upper body lift. Drag penalties mainly result from additional pressure drag induced by a recirculation wake vortex generated behind the vehicle's inboard side. The vehicle's lateral pressure distribution is also affected, introducing a centripetal force that increases with smaller corner radii. Additionally, analyses of the rear wing reveal alternations of its aerodynamic characteristics in cornering, particularly impacting vortical flow and suction on the lower surface. Throughout the operating conditions, the rear wing's individual downforce contribution falls off beyond its stall angle. At higher angles of attack, the rear wing primarily generates downforce by pressurizing the vehicle's upper surfaces, but its interaction with the near-wake leads to a substantially increased pressure drag. Overall, these findings provide crucial insights into the intricate aerodynamic interactions of high-performance vehicles in diverse operating conditions as well as form an essential foundation for future research on static and active aerodynamic designs in the pursuit to optimize vehicle performance in dynamic driving conditions. [ABSTRACT FROM AUTHOR]

The rapid growth of drone use in urban areas has prompted authorities to review airspace regulations, forcing drone manufacturers to anticipate and reduce the noise emissions during the design stage. Additionally, micro air vehicles (MAVs) are designed to be aerodynamically efficient, allowing them to fly farther, longer and safer. In this study, a steady aerodynamic code and an acoustic propagator based on the non-linear vortex lattice method (NVLM) and Farassat's formulation-1A of the Ffowcs Williams and Hawkings (FW-H) acoustic analogy, respectively, are coupled with pymoo, a python-based optimization framework. This tool is used to perform a multi-objective (noise and aerodynamic efficiency) optimization of a 20 cm diameter two-bladed rotor under hovering conditions. From the set of optimized results, (i.e., the Pareto front), three different rotors are 3D-printed using a stereolithography (SLA) technique and tested in an anechoic room. Here, an array of far-field microphones captures the acoustic radiation and directivity of the rotor, while a balance measures the aerodynamic performance. Both the aerodynamic and aeroacoustic performance of the three different rotors, in line with what has been predicted by the numerical codes, are compared and guidelines for the design of aerodynamically and aeroacoustically efficient MAV rotors are extracted. [ABSTRACT FROM AUTHOR]

The aerodynamic performance of wings degrades severely at low Reynolds number; lift often becomes non-linear, while drag increases significantly, caused by large extents of separation. Consequently, a non-conventional wing design approach is implemented to assess its ability to enhance performance. The design methodology is that of wing segmentation, where the wing is divided into spanwise panels that can be separated, thereby yielding small gaps between the panels. A moderate aspect ratio wing comprised of four separate wing panels was manufactured and wind tunnel tested through a Re range from 40,000 to 80,000. Force balance data and surface flow visualization were used to characterize performance. The results indicate that segmentation is effective in significantly augmenting efficiency at Reynolds numbers at which the fused wing (i.e., no gaps) shows large extents of open separation. Drag is greatly reduced, while lift is increased, and stall is delayed. The benefit of segmentation was noted to diminish at higher Re where the fused wing's performance improves markedly. Wing segmentation could find application in micro-unmanned-aerial-vehicle and drone design. Further study would entail the effects of AR and the number of spanwise panels on performance. [ABSTRACT FROM AUTHOR]

Tilt-duct Unmanned Aerial Vehicles (UAV) combine the high-speed efficiency of fixed-wing aircrafts with vertical takeoff and landing (VTOL) and the hover capabilities of rotary-wing aircrafts while maximizing the advantages of ducted fans in terms of noise reduction, efficiency, and safety, making it a pivotal direction for the future of aviation such as urban air mobility. This paper concentrates on the design and optimization of the primary structures of a laboratory-designed reference tilt-duct UAV. Firstly, the general data of the reference tilt-duct UAV are presented. According to the load conditions, the overall structural layout design for the wing, fuselage, and empennage is carried out, where special attention has been paid to account for the requirements of VTOL/hover and cruise flight modes. Based on the structural layout, finite element models (FEM) are established and static analyses are performed. The results indicate that the design can fulfill the structural requirements during a flight mission. Furthermore, based on the Method of Feasible Directions (MFD) algorithm, we have carried out the optimization of the composite wing box that incorporates manufacturing constraints. Via optimization, the total mass of the wing box is reduced by 38.6%, i.e., from 3.73 kg to 2.29 kg. The results indicate that the combination of composite materials with a tilt-duct configuration holds significant potential for future high-efficiency and environmentally friendly aviation. [ABSTRACT FROM AUTHOR]

The tilt-wing aircraft has attracted widespread attention due to its excellent performance. However, its aerodynamic characteristics during the tilt transition section are characterized by unsteadiness, nonlinearity, and strong coupling, making it difficult to control. Using computational fluid dynamics (CFD) methods and moving overset grids to control the tilt-wing motion, the momentum source method is employed to replace actual propellers. The influence of the propeller on the aerodynamic characteristics of the tiltrotor at different tilt angles is investigated under incoming flow velocities of 8 m/s and 45 m/s in steady conditions. Additionally, the differences between steady and unsteady calculations of the tilt transition section are investigated at incoming flow velocities of 8 m/s, 15 m/s, 30 m/s, and 45 m/s in unsteady conditions. The research results indicate the following information: 1. the slipstream from the propellers significantly enhances the lift, drag, and stall angle of attack of the tilt-wing aircraft but reduces the lift-to-drag ratio; 2. there are noticeable differences in the forces acting on the tilt-wing aircraft between steady calculations with fixed tilt angles and unsteady calculations with continuous tilting. [ABSTRACT FROM AUTHOR]

The mechanoreception system in bionic micro air vehicles, akin to insect sensory neurons, handles internal and external stimulus information. However, current onboard mechanoreception methods add weight and necessitate additional power. Employing the embodied energy design paradigm, a lightweight intelligent membranous wing is proposed, mimicking the scarab beetle's hindwing morphology and kinematics. This wing serves multiple functions, including aerodynamic load‐bearing, flight piezo‐mechanoreception, and power supply. The beetle's semi‐tubular costa structure is replicated, featuring a compliant leading edge for upstroke aerodynamic load resistance. Inspired by beetle hindwing veins and membranes, the bionic wing with three membranous fields: anal, medial, and apical, using heat lamination of multilayer materials is fabricated. The bionic wing's aerodynamic performance closely mirrors that of a real beetle hindwing, enabling various flight maneuvers and validating its real‐flight potential. As a piezo‐mechanoreception receptor for micro air vehicles, the bionic intelligent wing senses flapping frequency, wing deformations, and collisions through voltage signals from piezoelectric materials in the three membranous fields. Energy harvested from flapping‐wing motion powers onboard light intensity and ultraviolet sensors for mobile 3D environmental monitoring. This integration of aerodynamics, mechanoreception, and power supply via embodied flapping energy offers a novel approach for designing future intelligent flapping‐wing micro air vehicles. [ABSTRACT FROM AUTHOR]

The inertial navigation system (INS) and global satellite navigation system (GNSS) are two of the most significant systems for land navigation applications. The inertial measurement unit (IMU) is a kind of INS sensor that measures three-dimensional acceleration and angular velocity measurements. IMUs based on micro-electromechanical systems (MEMSs) are widely employed in vehicular navigation thanks to their low cost and small size, but their magnitude and noisy biases make navigation errors diverge very fast without external constraint. The zero-velocity update (ZVU) function is one of the efficient functions that constrain the divergence of IMUs for a stopped vehicle, and the key of the ZVU is the correct stationary detection for the vehicle. When a land vehicle is stopped, the idling engine produces a very stable vibration, which allows us to perform frequency analysis and a comparison based on the fast Fourier transform (FFT) and IMU measurements. Hence, we propose a stationary detection method based on the FFT for a stopped land vehicle with an idling engine in this study. An urban vehicular navigation experiment was carried out with our GNSS/IMU integration platform. Three stops for 10 to 20 min were set to analyze, generate and evaluate the FFT-based stationary detection method. The FFT spectra showed clearly idling vibrational peaks during the three stop periods. Through the comparison of FFT spectral features with decelerating and accelerating periods, the amplitudes of vibrational peaks were put forward as the key factors of stationary detection. For the consecutive stationary detection in the GNSS/IMU integration process, a three-second sliding window with a one-second updating rate of the FFT was applied to check the amplitudes of peaks. For the assessment of the proposed stationary detection method, GNSS observations were removed to simulate outages during the three stop periods, and the proposed detection method was conducted together with the ZVU. The results showed that the proposed method achieved a 99.7% correct detection rate, and the divergence of the positioning error constrained via the ZVU was within 2 cm for the experimental stop periods, which indicates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, we explore a nonlinear interactive network system comprising nodalized flapping-wing micro air vehicles (FMAVs) to address the distributed H ∞ state estimation problem associated with FMAVs. We enhance the model by introducing an information fusion function, leading to an information-fusionized estimator model. This model ensures both estimation accuracy and the completeness of FMAV topological information within a unified framework. To facilitate the analysis, each FMAV's received signal is individually sampled using independent and time-varying samplers. Transforming the received signals into equivalent bounded time-varying delays through the input delay method yields a more manageable and analyzable time-varying nonlinear network error system. Subsequently, we construct a Lyapunov–Krasovskii functional (LKF) and integrate it with the refined Wirtinger and relaxed integral inequalities to derive design conditions for the FMAVs' distributed H ∞ state estimator, minimizing conservatism. Finally, we validate the effectiveness and superiority of the designed estimator through simulations. [ABSTRACT FROM AUTHOR]

Flapping-wing micro air vehicles (FWMAVs) have gained much attention from researchers due to their exceptional performance at low Reynolds numbers. However, the limited understanding of active aerodynamic modulation in flying creatures has hindered their maneuverability from reaching that of their biological counterparts. In this article, experimental investigations were conducted to examine the effect of the bilateral amplitude asymmetry of flexible flapping wings. A reduced bionic model featuring bat-like wings is built, and a dimensionless number Δ Φ * is introduced to scale the degree of bilateral amplitude asymmetry in flapping motion. The experimental results suggest that the bilateral amplitude–asymmetric flapping motion primarily induces maneuvering control forces of coupling roll moment and yaw moment. Also, roll moment and yaw moment have a good linear relationship. To achieve more efficient maneuvers based on this asymmetric motion, it is advisable to maintain Δ Φ * within the range of 0 to 0.4. The magnitude of passive pitching deformation during the downstroke is significantly greater than that during the upstroke. The phase of the peak of the passive pitching angle advances with the increase in flapping amplitude, while the valleys lag. And the proportion of pronation and supination in passive pitching motion cannot be adjusted by changing the flapping amplitude. These findings have important practical relevance for regulating turning maneuvers based on amplitude asymmetry and help to understand the active aerodynamic modulation mechanism through asymmetric wing kinematics. [ABSTRACT FROM AUTHOR]

The article considers the problem of processing measurement data under the changing status of measurement results from micromechanical sensors used in the intelligent onboard measurement system of a small unmanned aerial vehicle. While an aircraft is in the air, the status of measurement results changes from confirmed to indicative (for example, due to sensor defects, measuring channel degradation, false output measurement signals from micromechanical sensors due to vibrations and shocks caused by movement of air masses). As a result, the probability of stability loss in a small unmanned aerial vehicle increases, requiring improved accuracy of its orientation estimation under changes in the measurement result status. In the study, a Kalman measurement procedure was synthesized, with its equations defined with accuracy to the parameters of transition and state noise matrices characterizing the measurement process, as well as the disturbance vector. The parameters were determined by the mathematical model of measurement data transformation relying on a dynamic mathematical model, which distinguishes the developed measurement procedure from that with the classical transition matrix. In order to find unknown parameters, a neural network was applied. A multilayer perceptron was chosen as the basis for the neural network, which was trained using the error backpropagation algorithm. The mathematical modeling and measurement experiment revealed that the accuracy of the measurement procedure synthesized using a dynamic mathematical model is higher than that of the measurement procedure using the Kalman filter with a classical transition matrix. The study results can be used in the development of intelligent measurement procedures for onboard measurement systems operating under changes in the measurement result status. [ABSTRACT FROM AUTHOR]

The accuracy of aerodynamically controlled guided projectile simulations is largely determined by the aerodynamic model employed in flight simulations which impacts vehicle interaction with the surrounding air. In this work, the performance of projectile path following with two distinct aerodynamic models is examined for their possible influence on trajectory following accuracy. The study incorporates the path following guidance algorithm, which enables the object to navigate along a predefined path. The simulation mathematical model is developed in the MATLAB/Simulink environment. In addition, by integrating the path-following algorithm with the two aerodynamic models, the dynamic behaviour of the aerodynamically controlled projectile can be compared. This allows for a more comprehensive analysis of the trajectory and the effects of each model on the desired flight path. Further research can explore the differences between the two models in greater detail and quantify their impact on unmanned projectile trajectory predictions, in addition to further exploring the specific characteristics and limitations of each model. This will involve analysing their assumptions, computational methods, and inputs to identify potential sources of error or uncertainty in the simulations. Moreover, these results have important implications for the design of aerodynamically controlled projectiles as well as a deeper understanding of aerodynamic mathematical modelling in flight simulation. [ABSTRACT FROM AUTHOR]

In the near future, urban air mobility (UAM) will let an old dream of human society come true: affordable and fast air transportation for almost everyone. Among the various existing designs, the multicopter configuration best combines the advantages of compactness, simplicity, and maturity. These aspects are important for actual use, particularly during the early stage of this market. This study elaborates on the design principles of UAM multicopters by examining existing models in terms of their configuration, weight, and range specifications. In particular, the weights of the different components are estimated based on empirical models, aerodynamic fundamentals for the analysis of UAM multicopters are derived from momentum theory, and the power and energy requirements for hovering and cruise flight are evaluated, thereby enabling estimation of the maximum hovering time and flight range. Finally, a sizing method is introduced and validated against an actual UAM design. [ABSTRACT FROM AUTHOR]

The tail-sitter VTOL UAV boasts not only high-speed cruising and air hovering capabilities, but also its unique tail-sitting vertical takeoff and landing and hovering attitude enable aerial operations with an exceptionally small cross-sectional area. This feature effectively broadens the scope of application for the UAV in intelligent agriculture, encompassing tasks such as agricultural inspection, production monitoring, and topographic mapping. Given the necessity for frequent modal transitions, this paper is grounded in a thorough examination of the typical structural characteristics of the tail-sitter VTOL UAV. A comprehensive technical solution for tail-sitter VTOL UAVs, based on the free-tail configuration, is proposed in this paper. The free-tail structure is utilized to address the limitations of traditional tailless layout and fixed landing gear in terms of flight stability and takeoff/landing performance of tail-sitter VTOL UAVs. However, the implementation of this solution necessitates the addition of a new maneuvering unit. Consequently, this paper delves into the aerodynamic coupling characteristics and laws between the layout parameters such as tail number, tail length, and tail area and the tail-sitter VTOL UAV fuselage. To optimize the free-tail configuration, a multi-objective optimization is performed by integrating the overall UAV dynamics, landing dynamics, and modal transition trajectory constraints. The results of stability modeling simulations and flight tests demonstrate that the tail-sitter VTOL UAV equipped with this technical solution exhibits enhanced maneuverability and flight efficiency compared to the conventional tailless layout. [ABSTRACT FROM AUTHOR]