Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instabili...Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instability,occur frequently in both experimental and operational data.This infrequency causes events to be overlooked by existing prediction models,which lack the precision to accurately predict inclination attitudes in amphibious vehicles.To address this gap in predicting attitudes near extreme inclination points,this study introduces a novel loss function,termed generalized extreme value loss.Subsequently,a deep learning model for improved waterborne attitude prediction,termed iInformer,was developed using a Transformer-based approach.During the embedding phase,a text prototype is created based on the vehicle’s operation log data is constructed to help the model better understand the vehicle’s operating environment.Data segmentation techniques are used to highlight local data variation features.Furthermore,to mitigate issues related to poor convergence and slow training speeds caused by the extreme value loss function,a teacher forcing mechanism is integrated into the model,enhancing its convergence capabilities.Experimental results validate the effectiveness of the proposed method,demonstrating its ability to handle data imbalance challenges.Specifically,the model achieves over a 60%improvement in root mean square error under extreme value conditions,with significant improvements observed across additional metrics.展开更多
Ideal conductive hydrogels with their mechanical ductility,high conductivity and self-adhesion are es-sential for potential promising application as fascinating sensing materials in wearable electronic devices.Unfortu...Ideal conductive hydrogels with their mechanical ductility,high conductivity and self-adhesion are es-sential for potential promising application as fascinating sensing materials in wearable electronic devices.Unfortunately,due to the inevitable performance degeneration stemming from swelling features in aque-ous conditions,the applicability of hydrogel-based sensors is greatly reduced in aquatic environments.Herein,an amphibious hydrogel with mechanical ductile,self-adhesive,anti-freezing,and high strain sensitivity underwater is developed.The hydrogel produces a rapid self-gelation behavior at ambient conditions(several minutes)through a catechol redox reaction based on lignocellulosic nanofibril-Ag^(+).The tough polymer network by the virtue of strong hydrogen bonding and nano-reinforcement enables the resultant hydrogel with improved mechanical performance.Meanwhile,outstanding properties in-cluding high conductivity(2.12 S/m),strain sensing ability(maximum GF:3.98),good water resistance(equilibrium swelling ratio of 1.2%after 30 d)as well as other solvents,air/underwater adhesiveness,and anti-freezing performance can be obtained simultaneously.A sensor based on such hydrogel can be conveniently conformed and attached to the human limbs for achieving non-invasive,high stability and continuous underwater communications and habits tracking of marine.Briefly,this work provides an innovative route to develop multifunctional integration hydrogel-based flexible devices for information transmission in marine environments.展开更多
Nonlinear amphibious vehicle rolling under regular waves and wind load is analyzed by a single degree of freedom system.Considering nonlinear damping and restoring moments,a nonlinear rolling dynamical equation of amp...Nonlinear amphibious vehicle rolling under regular waves and wind load is analyzed by a single degree of freedom system.Considering nonlinear damping and restoring moments,a nonlinear rolling dynamical equation of amphibious vehicle is established.The Hamiltonian function of the nonlinear rolling dynamical equation of amphibious vehicle indicate when subjected to joint action of periodic wave excitation and crosswind,the nonlinear rolling system degenerates into being asymmetric.The threshold value of excited moment of wave and wind is analyzed by the Melnikov method.Finally,the nonlinear rolling motion response and phase portrait were simulated by four order Runge-Kutta method at different excited moment parameters.展开更多
Owing to the strong coupling among the hydrodynamic forces,aerodynamic forces and motion of amphibious aircraft during the water takeoff process,the water takeoff performance is difficult to calculate accurately and q...Owing to the strong coupling among the hydrodynamic forces,aerodynamic forces and motion of amphibious aircraft during the water takeoff process,the water takeoff performance is difficult to calculate accurately and quickly.Based on an analysis of the dynamics and kinematics characteristics of amphibious aircraft and the hydrodynamic theory of high-speed planing hulls,a suitable mathematical model is established for calculating the hydrodynamics of aircraft during water takeoff.A pilot model is designed to illustrate how pilots are affected by the lack of visual reference and the necessity to simultaneously control the pitch angle,flight velocity and other parameters during water takeoff.Combined with the aerodynamic model,engine thrust model and aircraft motion model,a digital virtual flight simulation model is developed for amphibious aircraft during water takeoff,and a calculation method for the water takeoff performance of amphibious aircraft is proposed based on digital virtual flight.Typical performance indicators,such as the liftoff time and liftoff distance,can be obtained via digital virtual flight calculations.A comparison of the measured flight test data and the calculation results shows that the calculation error is less than 10%,which verifies the correctness and accuracy of the proposed method.This method can be used for the preliminary evaluation of airworthiness compliance of amphibious aircraft design schemes,and the relevant calculation results can also provide a theoretical reference for the formulation of flight test plans for airworthiness certification.展开更多
Bionic amphibious robots have important prospects in scientific, commercial, and military fields. Compared with traditional amphibious robots which use propellers/jets for aquatic medium and wheels/tracks for terrestr...Bionic amphibious robots have important prospects in scientific, commercial, and military fields. Compared with traditional amphibious robots which use propellers/jets for aquatic medium and wheels/tracks for terrestrial medium, bionic propulsion method has great advantages in terms of manoeuvrability, efficiency, and reliability, because there is no need to switch between different propulsion systems. To explore the integrated driving technology of amphibious robot, a novel bio-inspired soft robotic fin for amphibious use is proposed in this paper. The bionic fin can swim underwater and walk on land by the same undulating motion. To balance the conflicting demands of flexibility underwater and rigidity on land, the undulating fin adopts a special combination of a membrane fin and a bending spring. A periodic longitudinal wave in horizontal direction has been found generating passively in dynamic analysis. To find the composite wave-driven mechanics, theoretical analysis is conducted based on the walking model and swimming model. A virtual prototype is built in ADAMS software to verify the walking mechanics. The simulation result reveals that the passive longitudinal wave is also periodical and the composite wave contributes to land walking. Finally, an amphibious robot prototype actuated by a pair of undulating fins has been developed. The experiments show that the robot can achieve multiple locomotion, including walking forward/backward, turning in place, swimming underwater, and crossing medium, thus giving evidence to the feasibility of the newly designed undulating fin for amphibious robot.展开更多
Amphibious robots are becoming increasingly important for civilian,scientific,and environmental missions.They are widely used in disaster rescue,ecosystem monitoring,and entertainment.However,some have two different l...Amphibious robots are becoming increasingly important for civilian,scientific,and environmental missions.They are widely used in disaster rescue,ecosystem monitoring,and entertainment.However,some have two different locomotion systems that need to be changed manually to fulfill both swimming in the water and moving on land,which may reduce their efficiency and reliability.Applying bioinspiration and biomimetics,many recently developed amphibious robots can undertake various tasks in complex amphibious environments with high mobility,flexibility,and energy efficiency.This review overviews the latest developments in amphibious robots,emphasizing biomimetic design concepts,backbone driving mechanisms,and typical applications.The performance indices of amphibious robots mimicking 13 different natural sources are compared,based on 10 different propulsion principles/modes,travel speed,working efficiency,maneuverability,and stability.Finally,the current challenges and perspectives of amphibious bio-inspired robots are discussed.This article summarizes the current types of amphibious robots and their movement and behavior solutions.The design concepts and operating mechanisms of amphibious robots reviewed here can be readily applied to other robotic studies.展开更多
A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethox...A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethoxysilane（A-TES） and benzyltetrazole-modified triethoxysilane（BT-TES）.The dual-curing approach including UV-curing and thermal curing was used to obtain the crosslinked membranes.Polyethylene glycol（400） diacrylate（PEGDA） was used as an oligomer to form the polymeric matrix.The molecular structures of precursors were characterized by 1 H,13 C and 29 Si NMR spectra.The thermogravimetric analysis（TGA） results show that the membranes exhibit acceptable thermal stability for their application at above 200 oC.The differential scanning calorimeter（DSC） determination indicates that the crosslinked membranes with the mass ratios of below 1.6 of BT-TES to A-TES and the same mass of H3PO4 doped as that of A-TES possess the-T g s,and the lowest T g（-28.9 ℃） exists for the membrane with double mass of H3PO4 doped as well.The high proton conductivity in a range of 9.4―17.3 mS/cm with the corresponding water uptake of 19.1%―32.8% of the membranes was detected at 90 oC under wet conditions.Meanwhile,the proton conductivity in a dry environment for the membrane with a mass ratio of 2.4 of BT-TES to A-TES and double H3PO4 loading increases from 4.89×10-2 mS/cm at 30 ℃ to 25.7 mS/cm at 140 ℃.The excellent proton transport ability under both hydrous and anhydrous conditions demonstrates a potential application in the polymer electrolyte membrane fuel cells.展开更多
We proposed and implemented a leg-vector water-jet actuated spherical robot and an underwater adaptive motion control system so that the proposed robot could perform exploration tasks in complex environments.Our aim w...We proposed and implemented a leg-vector water-jet actuated spherical robot and an underwater adaptive motion control system so that the proposed robot could perform exploration tasks in complex environments.Our aim was to improve the kinematic performance of spherical robots.We developed mechanical and dynamic models so that we could analyze the motions of the robot on land and in water.The robot was equipped with an Inertial Measurement Unit(IMU)that provided inclination and motion information.We designed three types of walking gait for the robot,with different stabilities and speeds.Furthermore,we proposed an online adjustment mechanism to adjust the gaits so that the robot could climb up slopes in a stable manner.As the system function changed continuously as the robot moved underwater,we implemented an online motion recognition system with a forgetting factor least squares algorithm.We proposed a generalized prediction control algorithm to achieve robust underwater motion control.To ensure real-time performance and reduce power consumption,the robot motion control system was implemented on a Zynq-7000 System-on-Chip(SoC).Our experimental results show that the robot’s motion remains stable at different speeds in a variety of amphibious environments,which meets the requirements for applications in a range of terrains.展开更多
Airborne landing with shipboard helicopters gradually replaces surface landing to dominate joint amphibious operations.A problem with shipboard helicopter mission planning is conducted in the context of amphibious ope...Airborne landing with shipboard helicopters gradually replaces surface landing to dominate joint amphibious operations.A problem with shipboard helicopter mission planning is conducted in the context of amphibious operations.First,the typical missions of shipborne helicopters in amphibious operations are analyzed.An Amphibious Operational Mission Planning Model for Shipboard Helicopters(AOMPMSH)is established,with the objectives of minimizing the completion time of the amphibious campaign and minimizing troop and helicopter losses,taking the available operational resources and the order of the mission sub-phases into account.Then,a simulationbased amphibious operations effectiveness assessment model is constructed to calculate the optimization objectives of AOMPMSH by simulating the campaign development with an amphibious objective area situation transfer model and simulating the engagement process with a modified Lanchester model.A reference point based multi-objective optimization algorithm is designed to solve the proposed AOMPMSH.The population iteration mechanism employs an initial population generation method and a local search method to solve the problem of vast definition space.The population ranking selection mechanism employs a population distribution based reference point generation method to solve the problem of population irregular distribution.Finally,a simulation case with the background of a battalion-scaled amphibious campaign is presented.The calculation results verify the rationality of the proposed model and the superiority of the designed algorithm and have some reference value for the operational applications of shipboard helicopters in amphibious operations.展开更多
Upper-lower computer mode is the main architecture design of the amphibious combat simulation system(ACSS)at present.Through continuous improvement of real-time performance,software and hardware infrastructure,the exp...Upper-lower computer mode is the main architecture design of the amphibious combat simulation system(ACSS)at present.Through continuous improvement of real-time performance,software and hardware infrastructure,the exponential growth of operational network data scale is realized,but the availability performance of ACSS declines.The reliability of the working host as the key node has become the bottleneck of the overall availability of network nodes in the ACSS.To optimize the network node architecture of ACSS,this paper presents an effective optimization solution by designing the dual redundancy warm-standby module of the mission computer and I/O port,the algorithm of selecting output path of the mission computer in network nodes,the decision-making algorithm upon the on-duty host and output,and the video output decision-making algorithm upon the upper host.Lastly,the complete process of operational data from the input to output and the opposite is implemented well to guarantee the overall availability of network nodes in the ACSS.It has great advantages of wide applicability,strong reliability and high real-time switching speed.展开更多
With the development of intelligent bionic robots and the improvement of military application,a single robot cannot meet the requirements of the tasks of the current era.The more complex tasks require not only that th...With the development of intelligent bionic robots and the improvement of military application,a single robot cannot meet the requirements of the tasks of the current era.The more complex tasks require not only that the robot be able to pass through the field barriers and the amphibious environment,but also that the robot be able to collaborate in a multi-robot system.Consequently,research on the multi-robot control system of spherical amphibious robots is very important.Presently,the main research on amphibious robots is to improve the functions of a single robot,in the absence of the study of the multi-robot control system.Existing systems primarily use a centralized control methodology.Although the transfer of central node can be achieved,there is still a problem of Byzantine fault tolerance in military applications,that is,when the amphibious multi-robot system is invaded by the enemy.The central node may not only fail to accomplish the task,but also lose control of other robots,with severe consequences.To solve the above problems,this paper proposed a decentralized method of spherical amphibious multi-robot control system based on blockchain technology.First,the point-to-point information network based on long range radio technology of low power wide area network was set up,we designed the blockchain system for embedded application environment and the decentralized hardware and software architecture of multi-robot control system.On this basis,the consensus plugin,smart contract and decentralized multi-robot control algorithm were designed to achieve decentralization.The experimental results of consensus of spherical amphibious multi-robot showed the effectiveness of the decentralization.展开更多
Path planning of amphibious vehicles on military topographic maps is a hot research topic in the field of amphibious tactical training simulation.According to the dynamic characteristics and maneuvering destination re...Path planning of amphibious vehicles on military topographic maps is a hot research topic in the field of amphibious tactical training simulation.According to the dynamic characteristics and maneuvering destination requirements of amphibious vehicles,a three-dimensional simulation model of amphibious vehicles is designed,and a straight-line driving and steering dynamic model is constructed.The optimal maneuvering destination and constraint conditions under the condition of unconnected graph are put forward,and the problems of simulation and maneuvering path planning of amphibious vehicles on unconnected graph are solved by the theory of region partition and shortest path of graph.Compared with Dijkstra algorithm and heuristic algorithm A~*,the experimental results show that the algorithm designed in this paper has superior applicability and time performance.展开更多
To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization efficiency.In the p...To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization efficiency.In the proposed framework,the free-form deformation parametric model of the flat slender body is established and an analytical calculation method for the height constraints is derived.CFD method is introduced to carry out the high-precision resistance calculation and a constrained Kriging-based optimization method is built to improve the optimization efficiency by circularly infilling the new sample points which satisfying the constraints.Finally,the shape of an amphibious robot example is optimized to get the low-resistance shape and the results demonstrate that the presented optimization design framework has the advantages of simplicity,flexibility and high efficiency.展开更多
When the amphibious vehicle navigates in water,the angle of the anti-wave plate and the position of the center of gravity greatly influence the navigation characteristics.In the relevant research on reducing the navig...When the amphibious vehicle navigates in water,the angle of the anti-wave plate and the position of the center of gravity greatly influence the navigation characteristics.In the relevant research on reducing the navigation resistance of amphibious vehicles by adjusting the angle of the anti-wave plate,there is a lack of scientific selection of parameters and reasonable research of simulation results by using mathematical methods,and the influence of the center of gravity position on navigation characteristics is not considered at the same time.To study the influence of the combinations of the angle of the anti-wave plate and the position of the center of gravity on the resistance reduction characteristics,a numerical calculation model of the amphibious unmanned vehicle was established by using the theory of computational fluid dynamics,and the experimental data verified the correctness of the numerical model.Based on this numerical model,the navigation characteristics of the amphibious unmanned vehicle were studied when the center of gravity was located at different positions,and the orthogonal experimental design method was used to optimize the parameters of the angle of the anti-wave plate and the position of the center of gravity.The results show that through the parameter optimization analysis based on the orthogonal experimental method,the combination of the optimal angle of the anti-wave plate and the position of the center of gravity is obtained.And the numerical simulation result of resistance is consistent with the predicted optimal solution.Compared with the maximum navigational resistance,the parameter optimization reduces the navigational resistance of the amphibious unmanned vehicle by 24%.展开更多
The recently published study by Liu et al.(2024)on a high-quality,chromosome-level genome of Eleocharis vivipara provides new insight into the multiple evolution of C_(4)photosynthesis in Cyperaceae and in particular ...The recently published study by Liu et al.(2024)on a high-quality,chromosome-level genome of Eleocharis vivipara provides new insight into the multiple evolution of C_(4)photosynthesis in Cyperaceae and in particular in Eleocharis.The species studied has the rare feature of alternately using C_(3)photosynthesis underwater and C_(4)photosynthesis on land(Ueno et al.,1988),making it an exciting model to better understand the genetic control and evolution of the C_(4)trait and,in particular,the evolutionary challenge to switch from C_(3)to C_(4)photosynthesis from the aquatic to the terrestrial environment.展开更多
The ever-expanding frontier of applications demands that mobile vehicles navigate challenging,complex,and rugged terrains,as well as diverse environments.In this paper,we presented the novel design of an autonomous am...The ever-expanding frontier of applications demands that mobile vehicles navigate challenging,complex,and rugged terrains,as well as diverse environments.In this paper,we presented the novel design of an autonomous amphibious vehicle,driven by Archimedean screw mechanisms.Hydrodynamic simulations were conducted to analyze the propulsive characteristics of screw mechanisms in water.Particularly,an innovative screw-propeller integrated structure was proposed.At a rotation speed of 1000 rpm,the generated thrust of the integrated structure increased by 50% compared with the original screw,indicating a significant improvement in propulsion performance.Simultaneously,we analyzed its contact with the terrain by using the discrete element method.The process was simulated through a co-simulation involving multi-body dynamics,which presented an analytical method for investigating vehicle-terrain contact mechanics.Finally,a series of performance and field experiments were carried out.The vehicle successfully traversed various terrains including sandy,gravel,and grass roads,overcoming a 5 cm high obstacle.Furthermore,it autonomously executed offshore and landing movements,and showcased excellent amphibious trafficability at the coast.Overall,our research provides valuable insights into the development of autonomous screw-driven vehicles,offering a wide range of application prospects.展开更多
基金Supported by the National Defense Basic Scientific Research Program of China.
文摘Amphibious vehicles are more prone to attitude instability compared to ships,making it crucial to develop effective methods for monitoring instability risks.However,large inclination events,which can lead to instability,occur frequently in both experimental and operational data.This infrequency causes events to be overlooked by existing prediction models,which lack the precision to accurately predict inclination attitudes in amphibious vehicles.To address this gap in predicting attitudes near extreme inclination points,this study introduces a novel loss function,termed generalized extreme value loss.Subsequently,a deep learning model for improved waterborne attitude prediction,termed iInformer,was developed using a Transformer-based approach.During the embedding phase,a text prototype is created based on the vehicle’s operation log data is constructed to help the model better understand the vehicle’s operating environment.Data segmentation techniques are used to highlight local data variation features.Furthermore,to mitigate issues related to poor convergence and slow training speeds caused by the extreme value loss function,a teacher forcing mechanism is integrated into the model,enhancing its convergence capabilities.Experimental results validate the effectiveness of the proposed method,demonstrating its ability to handle data imbalance challenges.Specifically,the model achieves over a 60%improvement in root mean square error under extreme value conditions,with significant improvements observed across additional metrics.
基金supported by the National Natural Science Foundation of China(No.52203148)the Zhejiang A&F University Scientific Research Training Program for Undergraduates(Nos.2024kx0026 and 2024kx0027)the Research Foundation of Talented Scholars of Zhejiang A&F University(No.2020FR070)。
文摘Ideal conductive hydrogels with their mechanical ductility,high conductivity and self-adhesion are es-sential for potential promising application as fascinating sensing materials in wearable electronic devices.Unfortunately,due to the inevitable performance degeneration stemming from swelling features in aque-ous conditions,the applicability of hydrogel-based sensors is greatly reduced in aquatic environments.Herein,an amphibious hydrogel with mechanical ductile,self-adhesive,anti-freezing,and high strain sensitivity underwater is developed.The hydrogel produces a rapid self-gelation behavior at ambient conditions(several minutes)through a catechol redox reaction based on lignocellulosic nanofibril-Ag^(+).The tough polymer network by the virtue of strong hydrogen bonding and nano-reinforcement enables the resultant hydrogel with improved mechanical performance.Meanwhile,outstanding properties in-cluding high conductivity(2.12 S/m),strain sensing ability(maximum GF:3.98),good water resistance(equilibrium swelling ratio of 1.2%after 30 d)as well as other solvents,air/underwater adhesiveness,and anti-freezing performance can be obtained simultaneously.A sensor based on such hydrogel can be conveniently conformed and attached to the human limbs for achieving non-invasive,high stability and continuous underwater communications and habits tracking of marine.Briefly,this work provides an innovative route to develop multifunctional integration hydrogel-based flexible devices for information transmission in marine environments.
基金The Pre-research Project of the General Armament DepartmentThe Science Fund of North University of China(No.20130105)
文摘Nonlinear amphibious vehicle rolling under regular waves and wind load is analyzed by a single degree of freedom system.Considering nonlinear damping and restoring moments,a nonlinear rolling dynamical equation of amphibious vehicle is established.The Hamiltonian function of the nonlinear rolling dynamical equation of amphibious vehicle indicate when subjected to joint action of periodic wave excitation and crosswind,the nonlinear rolling system degenerates into being asymmetric.The threshold value of excited moment of wave and wind is analyzed by the Melnikov method.Finally,the nonlinear rolling motion response and phase portrait were simulated by four order Runge-Kutta method at different excited moment parameters.
文摘Owing to the strong coupling among the hydrodynamic forces,aerodynamic forces and motion of amphibious aircraft during the water takeoff process,the water takeoff performance is difficult to calculate accurately and quickly.Based on an analysis of the dynamics and kinematics characteristics of amphibious aircraft and the hydrodynamic theory of high-speed planing hulls,a suitable mathematical model is established for calculating the hydrodynamics of aircraft during water takeoff.A pilot model is designed to illustrate how pilots are affected by the lack of visual reference and the necessity to simultaneously control the pitch angle,flight velocity and other parameters during water takeoff.Combined with the aerodynamic model,engine thrust model and aircraft motion model,a digital virtual flight simulation model is developed for amphibious aircraft during water takeoff,and a calculation method for the water takeoff performance of amphibious aircraft is proposed based on digital virtual flight.Typical performance indicators,such as the liftoff time and liftoff distance,can be obtained via digital virtual flight calculations.A comparison of the measured flight test data and the calculation results shows that the calculation error is less than 10%,which verifies the correctness and accuracy of the proposed method.This method can be used for the preliminary evaluation of airworthiness compliance of amphibious aircraft design schemes,and the relevant calculation results can also provide a theoretical reference for the formulation of flight test plans for airworthiness certification.
基金supported by the National Natural Science Foundation of China(Grant No.52075537 and Grant No.52105289).
文摘Bionic amphibious robots have important prospects in scientific, commercial, and military fields. Compared with traditional amphibious robots which use propellers/jets for aquatic medium and wheels/tracks for terrestrial medium, bionic propulsion method has great advantages in terms of manoeuvrability, efficiency, and reliability, because there is no need to switch between different propulsion systems. To explore the integrated driving technology of amphibious robot, a novel bio-inspired soft robotic fin for amphibious use is proposed in this paper. The bionic fin can swim underwater and walk on land by the same undulating motion. To balance the conflicting demands of flexibility underwater and rigidity on land, the undulating fin adopts a special combination of a membrane fin and a bending spring. A periodic longitudinal wave in horizontal direction has been found generating passively in dynamic analysis. To find the composite wave-driven mechanics, theoretical analysis is conducted based on the walking model and swimming model. A virtual prototype is built in ADAMS software to verify the walking mechanics. The simulation result reveals that the passive longitudinal wave is also periodical and the composite wave contributes to land walking. Finally, an amphibious robot prototype actuated by a pair of undulating fins has been developed. The experiments show that the robot can achieve multiple locomotion, including walking forward/backward, turning in place, swimming underwater, and crossing medium, thus giving evidence to the feasibility of the newly designed undulating fin for amphibious robot.
基金supported by the National Key R&D Program of China(No.2018YFC2001303)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20190030)+1 种基金the Innovation Research Foundation of the National University of Defense Technology(No.ZK19-33)the International Postdoctoral Introduction Project Foundation,China。
文摘Amphibious robots are becoming increasingly important for civilian,scientific,and environmental missions.They are widely used in disaster rescue,ecosystem monitoring,and entertainment.However,some have two different locomotion systems that need to be changed manually to fulfill both swimming in the water and moving on land,which may reduce their efficiency and reliability.Applying bioinspiration and biomimetics,many recently developed amphibious robots can undertake various tasks in complex amphibious environments with high mobility,flexibility,and energy efficiency.This review overviews the latest developments in amphibious robots,emphasizing biomimetic design concepts,backbone driving mechanisms,and typical applications.The performance indices of amphibious robots mimicking 13 different natural sources are compared,based on 10 different propulsion principles/modes,travel speed,working efficiency,maneuverability,and stability.Finally,the current challenges and perspectives of amphibious bio-inspired robots are discussed.This article summarizes the current types of amphibious robots and their movement and behavior solutions.The design concepts and operating mechanisms of amphibious robots reviewed here can be readily applied to other robotic studies.
基金Supported by the National Natural Science Foundation of China(No.50973100)
文摘A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethoxysilane（A-TES） and benzyltetrazole-modified triethoxysilane（BT-TES）.The dual-curing approach including UV-curing and thermal curing was used to obtain the crosslinked membranes.Polyethylene glycol（400） diacrylate（PEGDA） was used as an oligomer to form the polymeric matrix.The molecular structures of precursors were characterized by 1 H,13 C and 29 Si NMR spectra.The thermogravimetric analysis（TGA） results show that the membranes exhibit acceptable thermal stability for their application at above 200 oC.The differential scanning calorimeter（DSC） determination indicates that the crosslinked membranes with the mass ratios of below 1.6 of BT-TES to A-TES and the same mass of H3PO4 doped as that of A-TES possess the-T g s,and the lowest T g（-28.9 ℃） exists for the membrane with double mass of H3PO4 doped as well.The high proton conductivity in a range of 9.4―17.3 mS/cm with the corresponding water uptake of 19.1%―32.8% of the membranes was detected at 90 oC under wet conditions.Meanwhile,the proton conductivity in a dry environment for the membrane with a mass ratio of 2.4 of BT-TES to A-TES and double H3PO4 loading increases from 4.89×10-2 mS/cm at 30 ℃ to 25.7 mS/cm at 140 ℃.The excellent proton transport ability under both hydrous and anhydrous conditions demonstrates a potential application in the polymer electrolyte membrane fuel cells.
基金National Natural Science Foundation of China(61773064,61503028).
文摘We proposed and implemented a leg-vector water-jet actuated spherical robot and an underwater adaptive motion control system so that the proposed robot could perform exploration tasks in complex environments.Our aim was to improve the kinematic performance of spherical robots.We developed mechanical and dynamic models so that we could analyze the motions of the robot on land and in water.The robot was equipped with an Inertial Measurement Unit(IMU)that provided inclination and motion information.We designed three types of walking gait for the robot,with different stabilities and speeds.Furthermore,we proposed an online adjustment mechanism to adjust the gaits so that the robot could climb up slopes in a stable manner.As the system function changed continuously as the robot moved underwater,we implemented an online motion recognition system with a forgetting factor least squares algorithm.We proposed a generalized prediction control algorithm to achieve robust underwater motion control.To ensure real-time performance and reduce power consumption,the robot motion control system was implemented on a Zynq-7000 System-on-Chip(SoC).Our experimental results show that the robot’s motion remains stable at different speeds in a variety of amphibious environments,which meets the requirements for applications in a range of terrains.
文摘Airborne landing with shipboard helicopters gradually replaces surface landing to dominate joint amphibious operations.A problem with shipboard helicopter mission planning is conducted in the context of amphibious operations.First,the typical missions of shipborne helicopters in amphibious operations are analyzed.An Amphibious Operational Mission Planning Model for Shipboard Helicopters(AOMPMSH)is established,with the objectives of minimizing the completion time of the amphibious campaign and minimizing troop and helicopter losses,taking the available operational resources and the order of the mission sub-phases into account.Then,a simulationbased amphibious operations effectiveness assessment model is constructed to calculate the optimization objectives of AOMPMSH by simulating the campaign development with an amphibious objective area situation transfer model and simulating the engagement process with a modified Lanchester model.A reference point based multi-objective optimization algorithm is designed to solve the proposed AOMPMSH.The population iteration mechanism employs an initial population generation method and a local search method to solve the problem of vast definition space.The population ranking selection mechanism employs a population distribution based reference point generation method to solve the problem of population irregular distribution.Finally,a simulation case with the background of a battalion-scaled amphibious campaign is presented.The calculation results verify the rationality of the proposed model and the superiority of the designed algorithm and have some reference value for the operational applications of shipboard helicopters in amphibious operations.
基金Supported by the National Natural Science Foundation of China(61401496)
文摘Upper-lower computer mode is the main architecture design of the amphibious combat simulation system(ACSS)at present.Through continuous improvement of real-time performance,software and hardware infrastructure,the exponential growth of operational network data scale is realized,but the availability performance of ACSS declines.The reliability of the working host as the key node has become the bottleneck of the overall availability of network nodes in the ACSS.To optimize the network node architecture of ACSS,this paper presents an effective optimization solution by designing the dual redundancy warm-standby module of the mission computer and I/O port,the algorithm of selecting output path of the mission computer in network nodes,the decision-making algorithm upon the on-duty host and output,and the video output decision-making algorithm upon the upper host.Lastly,the complete process of operational data from the input to output and the opposite is implemented well to guarantee the overall availability of network nodes in the ACSS.It has great advantages of wide applicability,strong reliability and high real-time switching speed.
基金supported in part by the National Natural Science Foundation of China under Grant 61703305in part by the Key Research Program of the Natural Science Foundation of Tianjin under Grant 18JCZDJC38500in part by the Innovative Cooperation Project of Tianjin Scientific and Technological under Grant 18PTZWHZ00090.
文摘With the development of intelligent bionic robots and the improvement of military application,a single robot cannot meet the requirements of the tasks of the current era.The more complex tasks require not only that the robot be able to pass through the field barriers and the amphibious environment,but also that the robot be able to collaborate in a multi-robot system.Consequently,research on the multi-robot control system of spherical amphibious robots is very important.Presently,the main research on amphibious robots is to improve the functions of a single robot,in the absence of the study of the multi-robot control system.Existing systems primarily use a centralized control methodology.Although the transfer of central node can be achieved,there is still a problem of Byzantine fault tolerance in military applications,that is,when the amphibious multi-robot system is invaded by the enemy.The central node may not only fail to accomplish the task,but also lose control of other robots,with severe consequences.To solve the above problems,this paper proposed a decentralized method of spherical amphibious multi-robot control system based on blockchain technology.First,the point-to-point information network based on long range radio technology of low power wide area network was set up,we designed the blockchain system for embedded application environment and the decentralized hardware and software architecture of multi-robot control system.On this basis,the consensus plugin,smart contract and decentralized multi-robot control algorithm were designed to achieve decentralization.The experimental results of consensus of spherical amphibious multi-robot showed the effectiveness of the decentralization.
基金Supported by the National Natural Science Foundation of China(61401496)。
文摘Path planning of amphibious vehicles on military topographic maps is a hot research topic in the field of amphibious tactical training simulation.According to the dynamic characteristics and maneuvering destination requirements of amphibious vehicles,a three-dimensional simulation model of amphibious vehicles is designed,and a straight-line driving and steering dynamic model is constructed.The optimal maneuvering destination and constraint conditions under the condition of unconnected graph are put forward,and the problems of simulation and maneuvering path planning of amphibious vehicles on unconnected graph are solved by the theory of region partition and shortest path of graph.Compared with Dijkstra algorithm and heuristic algorithm A~*,the experimental results show that the algorithm designed in this paper has superior applicability and time performance.
基金financially supported by the National Natural Science Foundation of China(Grant No.52372356).
文摘To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization efficiency.In the proposed framework,the free-form deformation parametric model of the flat slender body is established and an analytical calculation method for the height constraints is derived.CFD method is introduced to carry out the high-precision resistance calculation and a constrained Kriging-based optimization method is built to improve the optimization efficiency by circularly infilling the new sample points which satisfying the constraints.Finally,the shape of an amphibious robot example is optimized to get the low-resistance shape and the results demonstrate that the presented optimization design framework has the advantages of simplicity,flexibility and high efficiency.
基金supported by the National Natural Science Foundation of China(52174154).
文摘When the amphibious vehicle navigates in water,the angle of the anti-wave plate and the position of the center of gravity greatly influence the navigation characteristics.In the relevant research on reducing the navigation resistance of amphibious vehicles by adjusting the angle of the anti-wave plate,there is a lack of scientific selection of parameters and reasonable research of simulation results by using mathematical methods,and the influence of the center of gravity position on navigation characteristics is not considered at the same time.To study the influence of the combinations of the angle of the anti-wave plate and the position of the center of gravity on the resistance reduction characteristics,a numerical calculation model of the amphibious unmanned vehicle was established by using the theory of computational fluid dynamics,and the experimental data verified the correctness of the numerical model.Based on this numerical model,the navigation characteristics of the amphibious unmanned vehicle were studied when the center of gravity was located at different positions,and the orthogonal experimental design method was used to optimize the parameters of the angle of the anti-wave plate and the position of the center of gravity.The results show that through the parameter optimization analysis based on the orthogonal experimental method,the combination of the optimal angle of the anti-wave plate and the position of the center of gravity is obtained.And the numerical simulation result of resistance is consistent with the predicted optimal solution.Compared with the maximum navigational resistance,the parameter optimization reduces the navigational resistance of the amphibious unmanned vehicle by 24%.
基金supported by LabEx TULIP (ANR-10-LABX-0041) and CEBA (ANR-10-LABX-25-01) both managed by the French Agence nationale de la recherche.
文摘The recently published study by Liu et al.(2024)on a high-quality,chromosome-level genome of Eleocharis vivipara provides new insight into the multiple evolution of C_(4)photosynthesis in Cyperaceae and in particular in Eleocharis.The species studied has the rare feature of alternately using C_(3)photosynthesis underwater and C_(4)photosynthesis on land(Ueno et al.,1988),making it an exciting model to better understand the genetic control and evolution of the C_(4)trait and,in particular,the evolutionary challenge to switch from C_(3)to C_(4)photosynthesis from the aquatic to the terrestrial environment.
基金supported by the National Natural Science Foundation of China(52071131)the Marine Science and Technology Innovation Project of Jiangsu Province(HY2018-15)the National Key Research and Development Program of China(2022YFC2806002,2021YFC2801604,and 2022YFB4703401).
文摘The ever-expanding frontier of applications demands that mobile vehicles navigate challenging,complex,and rugged terrains,as well as diverse environments.In this paper,we presented the novel design of an autonomous amphibious vehicle,driven by Archimedean screw mechanisms.Hydrodynamic simulations were conducted to analyze the propulsive characteristics of screw mechanisms in water.Particularly,an innovative screw-propeller integrated structure was proposed.At a rotation speed of 1000 rpm,the generated thrust of the integrated structure increased by 50% compared with the original screw,indicating a significant improvement in propulsion performance.Simultaneously,we analyzed its contact with the terrain by using the discrete element method.The process was simulated through a co-simulation involving multi-body dynamics,which presented an analytical method for investigating vehicle-terrain contact mechanics.Finally,a series of performance and field experiments were carried out.The vehicle successfully traversed various terrains including sandy,gravel,and grass roads,overcoming a 5 cm high obstacle.Furthermore,it autonomously executed offshore and landing movements,and showcased excellent amphibious trafficability at the coast.Overall,our research provides valuable insights into the development of autonomous screw-driven vehicles,offering a wide range of application prospects.
