Search Results (20)

Flying cars are envisioned as key components of the Future Comprehensive Transport Network System. Current flying car designs struggle to balance ground maneuverability with aerial agility, which means they cannot operate on standard roads (3.5 m width). Additionally, the low energy density of existing aviation batteries limits their operational range. Therefore, a high lift-to-drag ratio (L/D) improves efficiency by reducing drag and extending the operational range. This leads to more economical and efficient flight performance, making it particularly beneficial for flying cars. This paper addresses the challenges of the land–air amphibious design and high-L/D configuration design of flying cars, and Computational Fluid Dynamics (CFD) simulations were conducted to optimize the overall configuration of a flying car, followed by creating a 1:4-scale model and validating its aerial posture. The results confirmed the structural integrity of the tilting and folding wing design for amphibious flying cars, achieving a fixed-wing mode L/D of 11. This design effectively addresses the traditional flying car issue of neglecting ground travel requirements by focusing solely on the flight capabilities of simulated aircraft or drones. Full article

Due to irregular hydrodynamic–aerodynamic coupling, the modeling and simulation of near-surface flight are extremely complex. For the present study, a practical dynamic model and a complete motion simulation method for the solution of such problems were established for engineering applications. A discrete non-linear time-varying dynamics model was employed in order to ensure the universality of the method; thereafter, force models—including gravity, aerodynamic, hydrodynamic, control, and thrust models—were established. It should be noted that a non-linear approach was adopted for the hydrodynamic model, which reflects the influences of waves in real-world situations; in addition, a Proportional–Integral–Derivative (PID) control law was added to realize closed-loop simulation of the motion. Considering a take-off flight as a study case, longitudinal three Degrees of Freedom (DoF) motion was simulated. The velocity, angle of attack, height, and angular velocity were selected as the state vectors in the state–space equations. The results show that, with the equilibrium state as the initial setting for the motion, reasonable time–history curves of the whole take-off phase can be obtained using the proposed approach. Furthermore, it is universally applicable for aircraft operating under hydrodynamic–aerodynamic coupling scenarios, including amphibious aircraft, seaplanes, Wing-in-Ground-Effect (WIGE) aircraft, and Hybrid Aerial–Underwater Vehicles (HAUVs). Full article

Amphibious robots have broad prospects in the fields of industry, defense, and transportation. To improve the propulsion performance and reduce operation complexity, a novel bionic amphibious robot, namely AmphiFinbot-II, is presented in this paper. The swimming and walking components adopt a compound drive mechanism, enabling simultaneous control for the rotation of the track and the wave-like motion of the undulating fin. The robot employs different propulsion methods but utilizes the same operation strategy, eliminating the need for mode switching. The structure and the locomotion principle are introduced. The performance of the robot in different motion patterns was analyzed via computational fluid dynamics simulation. The simulation results verified the feasibility of the wave-like swimming mechanism. Physical experiments were conducted for both land and underwater motion, and the results were consistent with the simulation regulation. Both the underwater linear and angular velocity were proportional to the undulating frequency. The robot’s maximum linear speed and steering speed on land were 2.26 m/s (2.79 BL/s) and 442°/s, respectively, while the maximum speeds underwater were 0.54 m/s (0.67 BL/s) and 84°/s, respectively. The research findings indicate that the robot possesses outstanding amphibious motion capabilities and a simplistic yet unified control approach, thereby validating the feasibility of the robot’s design scheme, and offering a novel concept for the development of high-performance and self-contained amphibious robots. Full article

Unmanned vehicles (UVs) have become increasingly important in various scenarios of civil and military operations. The present work aims at the conceptual design of a modular Amphibious Unmanned Ground Vehicle (A-UGV) that can be easily adapted for different types of land and/or water missions with low monetary cost (EUR < 5 k, without sensors). Basing the design on the needs highlighted in the 2021 review of the Strategic Directive of the Portuguese Navy, the necessary specifications and requirements are established for two mission scenarios. Then, a market research analysis focused on vehicles currently available and their technological advances is conducted to identify existing UV solutions and respective characteristics/capabilities of interest to the current work. To study and define the geometry of the hull and the configuration of the A-UGV itself, preliminary computational structural and fluid analyses are carried out to ensure it complies with the specifications initially established. As a result, one obtains a fully electric vehicle with approximate dimensions of 1050 × 670 × 450 mm (length–width–height), enabled with 6 × 6 traction capable of reaching 20 km/h on land, which possesses amphibious capabilities of independent propulsion in water up to 8 kts and an estimated autonomy of over 60 min. Full article

Assessing the safety of amphibious aircraft hinges significantly on two key factors: wave-added resistance and motion stability during takeoff and landing on water surfaces. To tackle this, we employed the Reynolds-averaged Navier–Stokes (RANS) equations solved via the finite volume method. We utilized the volume fraction method to accurately capture the free surface and employed the overset grid technique to manage the relative motion between the aircraft and the liquid surface. Our approach involves establishing a numerical simulation scheme to investigate the water-planing motion of amphibious aircraft across varying wave heights, wavelengths, speeds, and center-of-gravity positions. The computational findings demonstrate a close match between calculated forces and aircraft motion compared to experimental values. Notably, we observed pronounced nonlinearity in wave-added resistance. Under high sea conditions, operating in a short-wavelength environment or with a rearward center-of-gravity position proves advantageous for reducing wave-added resistance. Conversely, poor longitudinal stability is evident during planing in long waves. Full article

In this study, a portable magnetic adsorption amphibious robot which can operate on and below the waterline is developed for special curved environments, such as the pile legs of offshore platforms and the outer walls of ships. An open robot integrated control system based on a domestic chip is developed, and two operating modes of local control operation and remote wireless operation are realized. A permanent magnet adsorption scheme combining a magnetic adsorption track and a synchronous belt wheel is designed, static and dynamic analysis of the wall-climbing operation of the robot is carried out, and a kinematic model of the underwater robot is established. The experimental results show that the robot can effectively complete amphibious tasks and can realize the accurate control of attitude in water, proving it to be an effective tool for amphibious tasks, such as operating on the pile legs of offshore platforms and the outer walls of ships. Full article

Amphibious buildings use the buoyancy principle in the design of their foundation systems to mitigate flood impact. In some cases, amphibious buildings are fitted with mechanical systems that further aid the buoyancy element to temporarily raise the building and guide its descent to natural ground level. These mechanical systems require external operation, preventing the amphibious building from passively responding during flood events as is one of the requirements of a robust flood mitigation measure. Additionally, buildings in flood environments are often left with stains on the exterior facade from floodwater contamination from sewage and chemicals, among others. This paper distinguishes three main components of an amphibious foundation: the buoyancy element, vertical guidance post, and structural sub-frame, and discusses their functionality. The natural world provides solutions to tackling environmental issues such as flooding. When systematically studied and transferred, nature can inspire innovative ideas for functional and sustainable designs for the built environments. Although there are many existing designs and a small number of constructed amphibious buildings, there are very few studies that discuss how the designs are derived, and even fewer on a framework emulating natural systems for transfer into amphibious building design. In that context, this research uses the biomimetic transfer process to abstract relevant biological systems, illustrating their potential for transfer into amphibious foundation design. The aim is to understand how these biological systems passively and continuously respond and adapt to their environment. Organisms such as the Venus flower basket, giant kelp, and red mangrove, among others, are discussed, to understand how they perform the identified functions. The steps of the biomimetic transfer process are used to integrate functions of amphibious buildings and processes of the studied biological systems. The final output of this paper is a discussion of the ways in which these derived relationships can be adopted in amphibious building design. Full article

Amphibious (air and water) drones, capable of both aerial and aquatic operations, have the potential to provide valuable drone applications in aquatic environments. However, the limited range of wireless data transmission caused by the low antenna height on water and reflection from the water surface (e.g., 45 m for vertical half-wave dipole antennas with the XBee S2C^TM, estimated using the two-ray ground reflection model) persists as a formidable challenge for amphibious systems. To overcome this difficulty, we developed a wireless data relay system for amphibious drones using the mesh-type networking functions of the XBee^TM. We then conducted field tests of the developed system in a large marsh pond to provide experimental evidence of the efficiency of the multiple-drone network in amphibious settings. In these tests, hovering relaying over water was attempted for extension and bypassing obstacles using the XBee S2C^TM (6.3 mW, 2.4 GHz). During testing, the hovering drone (<10 m height from the drone controller) successfully relayed water quality data from the transmitter to the receiver located approximately 757 m away, but shoreline vegetation decreased the reachable distance. A bypassing relay test for vegetation indicated the need to confirm a connected path formed by pair(s) of mutually observable drones. Full article

Causes and contributing factors of amphibious airplane accidents are examined by comparing the proportion of fatal accidents for different causes of accidents, with a focus on landings on water and low-level flying maneuvers. A set of 183 accidents involving amphibious planes from 2005 to 2020 was extracted from the National Transportation Safety Board’s online database. Amphibious airplane accidents are reported to be fatal in 34% of cases, which is higher than the average of 20% for general aviation. Logistic regression analysis shows that the maneuvering flight phase and decision-making factors are significantly more often associated with fatal accidents than other flight phases and causes. In addition, the number of accidents associated with decision-making factors significantly increased during the studied time period. Amphibious airplanes benefit from accident analysis despite the absence of denominator data and the limitations of most general aviation accident reports. Intentional low-level flying is shown to be a central area of concern that may be addressed at the operational as well as the training level. Landing accidents could be avoided by introducing additional warning systems and training regarding (retractable) landing gear as well as general awareness training of decision-making during landings on water. Full article

To address the issue of current garbage cleanup vessels being limited to performing garbage cleaning operations in the ocean, without the capability of transferring the garbage from the ocean to the land, this paper presents a spiral-propulsion amphibious intelligent robot for land garbage cleaning and sea garbage cleaning. The design solution is as follows. A mechanical structure based on a spiral drum is proposed. The interior of the spiral drum is hollow, providing buoyancy, allowing the robot to travel both on marshy, tidal flats and on the water surface, in conjunction with underwater thrusters. Additionally, a mechanical-arm shovel is designed, which achieves two-degrees-of-freedom movement through a spiral spline guide and servo, facilitating garbage collection. Our experimental results demonstrated that the robot exhibits excellent maneuverability in marine environments and on beach, marsh, and tidal flat areas, and that it collects garbage effectively. Full article

Maritime unmanned systems (MUS) have gained widespread usage in a diverse range of hydrographic survey activities, including harbor/port surveys, beach and coastline monitoring, environmental assessment, and military operations. The present article explains a validated, rapid, and reliable technique for processing hydrographic data that was obtained via an autonomous hydrographic survey, and which was executed by a prototype unmanned surface vessel (USV) belonging to the Unmanned Survey Solutions (USS) corporation. The experimentation was part of the annual Multinational Exercise Robotic Experimentation and Prototyping that was augmented by Maritime Unmanned Systems 22 (REPMUS22), which was held in the national waters of Portugal. The main objective of this experimentation was to assess the underwater environment over an ocean beach for an amphibious landing exercise. Moreover, the integration of the multibeam system with the autonomous prototype vessel was assessed. A short comparison between the USV survey and a traditional vessel multibeam survey is presented, whereby the advantages of performing an autonomous survey operation near the coastline is emphasized. A correlation between a known multibeam processing technique and the dissemination of a rapid but consistent product for operational use is described, highlighting the applicability of the technique for the data collected from small experimental platforms. Moreover, this study outlines the relationship between the particular errors observed in autonomous small vehicles and in conventional data processing methods. The resultant cartographic outputs from the hydrographic survey are presented, emphasizing the specific inaccuracies within the raw data and the suitability of distinct hydrographic products for various user domains. Full article

A computational fluid dynamic (CFD) simulation is performed to evaluate the resistance performance of a self-propelled amphibious vessel with caterpillars to be operated as a marine debris collection vessel at hard-to-reach areas. This study focuses on the influence of the addition of caterpillars on the vessel to the resistance performance. To capture the free surface model, the volume of fluid (VOF) method was adopted, and to express the sinkage and trim acting on the ship the Dynamic Fluid-body Interaction (DFBI) model was applied. A series of numerical simulations for resistance performance were carried out in the range of Froude number (Fn) of 0.12–0.32 for the vessels with and without caterpillars. A model test was carried out independently to verify the numerical simulation of resistance, and it indicated that the present simulation is valid with relative errors of less than 2% over the entire speed range. In subsequence, the resistance performance of the ship due to the addition of the caterpillars was evaluated, and an increase of nearly 40% at the design speed of Fn = 0.27 could be observed. In addition, in the present amphibious vessel, it was found that the ratio of the pressure resistance occupied in the total resistance was dominant, reaching around 81~92% for both cases. Full article

Penguins require vision that is adequate for both subaerial and submarine environments under a wide range of illumination. Here we provide a structured overview of what is known about their visual system with an emphasis on how and how well they achieve these goals. Amphibious vision is facilitated by a relatively flat cornea, the power in air varying from 10.2 dioptres (D) to 41.3 D depending on the species, and there is good evidence for emmetropia both above and below water. All penguins are trichromats with loss of rhodopsin 2, a nocturnal feature, but only deeper diving penguins have been noted to have pale oil droplets and a preponderance of rods. Conversely, the diurnal, shallow-diving little penguin has a higher ganglion cell density (28,867 cells/mm²) and f-number (3.5) than those that operate in dimmer light. In most species studied, there is some binocular overlap, but this reduces upon submergence. However, gaps in our knowledge remain, particularly with regard to the mechanism of accommodation, spectral transmission, behavioural measurements of visual function in low light, and neural adaptations to low light. The rarer species also deserve more attention. Full article

This paper proposes a distributed turbo-electric hybrid propulsion system (TEHPS) architecture for high-power and large-load air–ground aircraft (AGA). The composition of the turboshaft engine, hybrid energy storage system (HESS) as the power unit, distributed electric drive ducted fans, and wheels as the propulsion unit is determined. Firstly, the modeling of each component in the TEHPS is carried out, and system power, energy, and weight analysis are conducted under the different operating modes. Sizing parameters of main components are selected based on a genetic algorithm to obtain the optimal total weight and propulsion efficiency, and the energy management framework from the upper level to the lower level is completed by adopting an equivalent consumption minimum strategy and fuzzy logic control. Under the air–ground amphibious mission profile, the simulation results indicate that the TEHPS can achieve a 21.80% fuel consumption and ${\mathrm{CO}}_2$ emission optimization rate at the cost of 10.53% increase in the whole aircraft mass compared to the oil-only powertrain. The HESS can account for up to 29% and 33.56% of the energy and power ratios in the TEHPS, and reduce mass by 8.1% and volume by 3.77% compared to the single energy storage, which may provide theoretical insights for the powertrain composition form, sizing, and energy management of future hybrid air–ground aircraft. Full article

Recent large-scale operations, including frequent maritime transportation and unauthorised as well as unlawful collisions of drainage wastes, have polluted the ocean’s ecology. Due to the ocean’s unsuitable ecology, the entire globe may experience drastic aberrant conditions, which will force illness onto all living things. Therefore, an advanced system is very necessary to remove the undesired waste from the ocean’s surface and interior. Through the use of progressive unmanned amphibious vehicles (UAV), this study provides a dynamic operational mode-based solution to damage removal. In order to successfully handle the heavy payloads of ravage collections when the UAV reveals centre of gravity concerns, a highly manoeuvrable-based design inspired by nature has been imposed. The ideal creatures to serve as the inspiration for this piece are tropical birds, which have a long tail for navigating tricky situations. The design initialization was carried out by focusing on the outer body of tropical birds. Following this, special calculations were conducted and the full design parameters of the UAV were established. This study proposes a unique mathematical formulation for the development of primary and secondary design parameters of an UAV. The proposed mission profile of this application is computationally tested with the aid of sophisticated computational methodologies after the modelling of this UAV. The computational methods that are required are one-way coupling-based hydro-structural interaction assessments and computational hydrodynamic analyses. Computing is used to determine the aerodynamic and hydrodynamic forces over the UAV, the lightweight materials to withstand high fluid dynamic loads, and the buoyancy forces to complete the UAV components. These computational methods have been used to produce a flexible and fine-tuned UAV design for targeted real-time applications. Full article