To improve the efficiency and accuracy of path planning for fan inspection tasks in thermal power plants,this paper proposes an intelligent inspection robot path planning scheme based on an improved A^(*)algorithm.The...To improve the efficiency and accuracy of path planning for fan inspection tasks in thermal power plants,this paper proposes an intelligent inspection robot path planning scheme based on an improved A^(*)algorithm.The inspection robot utilizes multiple sensors to monitor key parameters of the fans,such as vibration,noise,and bearing temperature,and upload the data to the monitoring center.The robot’s inspection path employs the improved A^(*)algorithm,incorporating obstacle penalty terms,path reconstruction,and smoothing optimization techniques,thereby achieving optimal path planning for the inspection robot in complex environments.Simulation results demonstrate that the improved A^(*)algorithm significantly outperforms the traditional A^(*)algorithm in terms of total path distance,smoothness,and detour rate,effectively improving the execution efficiency of inspection tasks.展开更多
The traditional A^(*)algorithm exhibits a low efficiency in the path planning of unmanned surface vehicles(USVs).In addition,the path planned presents numerous redundant inflection waypoints,and the security is low,wh...The traditional A^(*)algorithm exhibits a low efficiency in the path planning of unmanned surface vehicles(USVs).In addition,the path planned presents numerous redundant inflection waypoints,and the security is low,which is not conducive to the control of USV and also affects navigation safety.In this paper,these problems were addressed through the following improvements.First,the path search angle and security were comprehensively considered,and a security expansion strategy of nodes based on the 5×5 neighborhood was proposed.The A^(*)algorithm search neighborhood was expanded from 3×3 to 5×5,and safe nodes were screened out for extension via the node security expansion strategy.This algorithm can also optimize path search angles while improving path security.Second,the distance from the current node to the target node was introduced into the heuristic function.The efficiency of the A^(*)algorithm was improved,and the path was smoothed using the Floyd algorithm.For the dynamic adjustment of the weight to improve the efficiency of DWA,the distance from the USV to the target point was introduced into the evaluation function of the dynamic-window approach(DWA)algorithm.Finally,combined with the local target point selection strategy,the optimized DWA algorithm was performed for local path planning.The experimental results show the smooth and safe path planned by the fusion algorithm,which can successfully avoid dynamic obstacles and is effective and feasible in path planning for USVs.展开更多
An improved version of the sparse A^(*)algorithm is proposed to address the common issue of excessive expansion of nodes and failure to consider current ship status and parameters in traditional path planning algorith...An improved version of the sparse A^(*)algorithm is proposed to address the common issue of excessive expansion of nodes and failure to consider current ship status and parameters in traditional path planning algorithms.This algorithm considers factors such as initial position and orientation of the ship,safety range,and ship draft to determine the optimal obstacle-avoiding route from the current to the destination point for ship planning.A coordinate transformation algorithm is also applied to convert commonly used latitude and longitude coordinates of ship travel paths to easily utilized and analyzed Cartesian coordinates.The algorithm incorporates a hierarchical chart processing algorithm to handle multilayered chart data.Furthermore,the algorithm considers the impact of ship length on grid size and density when implementing chart gridification,adjusting the grid size and density accordingly based on ship length.Simulation results show that compared to traditional path planning algorithms,the sparse A^(*)algorithm reduces the average number of path points by 25%,decreases the average maximum storage node number by 17%,and raises the average path turning angle by approximately 10°,effectively improving the safety of ship planning paths.展开更多
A safe and reliable path planning algorithm is fundamental for unmanned surface vehicles(USVs)to perform autonomous navigation tasks.However,a single global or local planning strategy cannot fully meet the requirement...A safe and reliable path planning algorithm is fundamental for unmanned surface vehicles(USVs)to perform autonomous navigation tasks.However,a single global or local planning strategy cannot fully meet the requirements of complex maritime environments.Global planning alone cannot effectively handle dynamic obstacles,while local planning alone may fall into local optima.To address these issues,this paper proposes a multi-dynamic-obstacle avoidance path planning method that integrates an improved A^(*)algorithm with the dynamic window approach(DWA).The traditional A^(*)algorithm often generates paths that are too close to obstacle boundaries and contain excessive turning points,whereas the traditional DWA tends to skirt densely clustered obstacles,resulting in longer routes and insufficient dynamic obstacle avoidance.To overcome these limitations,improved versions of both algorithms are developed.Key points extracted from the optimized A^(*)path are used as intermediate start-destination pairs for the improved DWA,and the weights of the DWA evaluation function are adjusted to achieve effective fusion.Furthermore,a multi-dynamic-obstacle avoidance strategy is designed for complex navigation scenarios.Simulation results demonstrate that the USV can adaptively switch between dynamic obstacle avoidance and path tracking based on obstacle distribution,validating the effectiveness of the proposed method.展开更多
Background Automatic guided vehicles(AGVs)have developed rapidly in recent years and have been used in several fields,including intelligent transportation,cargo assembly,military testing,and others.A key issue in thes...Background Automatic guided vehicles(AGVs)have developed rapidly in recent years and have been used in several fields,including intelligent transportation,cargo assembly,military testing,and others.A key issue in these applications is path planning.Global path planning results based on known environmental information are used as the ideal path for AGVs combined with local path planning to achieve safe and rapid arrival at the destination.Using the global planning method,the ideal path should meet the requirements of as few turns as possible,a short planning time,and continuous path curvature.Methods We propose a global path-planning method based on an improved A^(*)algorithm.The robustness of the algorithm was verified by simulation experiments in typical multiobstacle and indoor scenarios.To improve the efficiency of the path-finding time,we increase the heuristic information weight of the target location and avoid invalid cost calculations of the obstacle areas in the dynamic programming process.Subsequently,the optimality of the number of turns in the path is ensured based on the turning node backtracking optimization method.Because the final global path needs to satisfy the AGV kinematic constraints and curvature continuity condition,we adopt a curve smoothing scheme and select the optimal result that meets the constraints.Conclusions Simulation results show that the improved algorithm proposed in this study outperforms the traditional method and can help AGVs improve the efficiency of task execution by planning a path with low complexity and smoothness.Additionally,this scheme provides a new solution for global path planning of unmanned vehicles.展开更多
In the current era of intelligent technologies,comprehensive and precise regional coverage path planning is critical for tasks such as environmental monitoring,emergency rescue,and agricultural plant protection.Owing ...In the current era of intelligent technologies,comprehensive and precise regional coverage path planning is critical for tasks such as environmental monitoring,emergency rescue,and agricultural plant protection.Owing to their exceptional flexibility and rapid deployment capabilities,unmanned aerial vehicles(UAVs)have emerged as the ideal platforms for accomplishing these tasks.This study proposes a swarm A^(*)-guided Deep Q-Network(SADQN)algorithm to address the coverage path planning(CPP)problem for UAV swarms in complex environments.Firstly,to overcome the dependency of traditional modeling methods on regular terrain environments,this study proposes an improved cellular decomposition method for map discretization.Simultaneously,a distributed UAV swarm system architecture is adopted,which,through the integration of multi-scale maps,addresses the issues of redundant operations and flight conflicts inmulti-UAV cooperative coverage.Secondly,the heuristic mechanism of the A^(*)algorithmis combinedwith full-coverage path planning,and this approach is incorporated at the initial stage ofDeep Q-Network(DQN)algorithm training to provide effective guidance in action selection,thereby accelerating convergence.Additionally,a prioritized experience replay mechanism is introduced to further enhance the coverage performance of the algorithm.To evaluate the efficacy of the proposed algorithm,simulation experiments were conducted in several irregular environments and compared with several popular algorithms.Simulation results show that the SADQNalgorithmoutperforms othermethods,achieving performance comparable to that of the baseline prior algorithm,with an average coverage efficiency exceeding 2.6 and fewer turning maneuvers.In addition,the algorithm demonstrates excellent generalization ability,enabling it to adapt to different environments.展开更多
Vulnerability assessment is a systematic process to identify security gaps in the design and evaluation of physical protection systems.Adversarial path planning is a widely used method for identifying potential vulner...Vulnerability assessment is a systematic process to identify security gaps in the design and evaluation of physical protection systems.Adversarial path planning is a widely used method for identifying potential vulnerabilities and threats to the security and resilience of critical infrastructures.However,achieving efficient path optimization in complex large-scale three-dimensional(3D)scenes remains a significant challenge for vulnerability assessment.This paper introduces a novel A^(*)-algorithmic framework for 3D security modeling and vulnerability assessment.Within this framework,the 3D facility models were first developed in 3ds Max and then incorporated into Unity for A^(*)heuristic pathfinding.The A^(*)-heuristic pathfinding algorithm was implemented with a geometric probability model to refine the detection and distance fields and achieve a rational approximation of the cost to reach the goal.An admissible heuristic is ensured by incorporating the minimum probability of detection(P_(D)^(min))and diagonal distance to estimate the heuristic function.The 3D A^(*)heuristic search was demonstrated using a hypothetical laboratory facility,where a comparison was also carried out between the A^(*)and Dijkstra algorithms for optimal path identification.Comparative results indicate that the proposed A^(*)-heuristic algorithm effectively identifies the most vulnerable adversarial pathfinding with high efficiency.Finally,the paper discusses hidden phenomena and open issues in efficient 3D pathfinding for security applications.展开更多
Networked rural electrification is an alternative approach to accelerate rural electrification.Using satellite photos and GIS tools,an electrical distribution network is used to connect villages and properly located g...Networked rural electrification is an alternative approach to accelerate rural electrification.Using satellite photos and GIS tools,an electrical distribution network is used to connect villages and properly located generation facilities together to reduce electrification cost.To design the network,optimal paths connecting all node-pairs are identified,followed by finding a network topology that minimizes cost.Earlier work has illustrated that A*(A-star,an optimal path-finding algorithm)is inefficient for this application due to the complex topography in rural areas.The multiplier-accelerated A*(MAA*)algorithm overcomes key performance issues,but,like A*,produces only one path connecting each node-pair.Relying on one path increases project risk because adverse conditions,such as inaccurate GIS estimation,unexpected soil conditions,land-rights disputes,political issues,etc.can occur during implementation.In this paper,a hybrid path-finding method combining genetic algorithm and A*/MAA*algorithm is proposed.The proposed method provides a family of near-optimal paths instead of a single optimal path for routing.A family of paths allows a project implementer to quickly adapt to unexpected situations as new information becomes available,and flexibly change network topology before or during implementation with minimal impact on project cost.展开更多
Aimed at the safety of helicopter flight in the highly dynamic wind field of urban lowaltitude environment,a wind field simulation and reconstruction method based on unsteady Reynolds-Averaged Navier-Stokes(RANS)and S...Aimed at the safety of helicopter flight in the highly dynamic wind field of urban lowaltitude environment,a wind field simulation and reconstruction method based on unsteady Reynolds-Averaged Navier-Stokes(RANS)and Snapshot Proper Orthogonal Decomposition(Snapshot POD)is proposed in this paper.A comprehensive flight simulation platform is developed,integrating the simulated wind field,a helicopter flight dynamic model,an explicit ModelFollowing Control System(MFCS),and a simplified precision pilot model.Focusing on the issue of airflow disturbances from nearby obstacles in urban environments,a spatiotemporal,dualsource wind-induced threat identification model is established,which fuses turbulence threat and operational exceedance threat,and is incorporated into the construction of safety maps used for trajectory planning.The neighborhood search strategy of the A*algorithm is improved to enhance the trajectory's environmental adaptability,forming an automatic helicopter flight simulation method for complex urban wind environments,integrating wind field prediction,trajectory planning,and flight simulation.Applied to real-world environment flight simulation,the Improved Safety Map-based A*method(I-SM-A*)can reduce the number of path nodes and approach the target faster compared with the Traditional A*method(Trad-A*).The designed trajectory can effectively isolate the wind-induced threat caused by the building airflow.This results in a reduction in pilot workload,as evidenced by decreases of 10.6%and 8.0%in the time and frequency domains,respectively.The flight simulation platform can accurately track the designed trajectory and achieve reliable automatic flight planning in complex urban windy environments.展开更多
Wireless ad hoc network is generally employed in military and emergencies due to its flexibility and easy-to-use.It is suitable for military wireless network that has the charac-teristics of mobility and works effecti...Wireless ad hoc network is generally employed in military and emergencies due to its flexibility and easy-to-use.It is suitable for military wireless network that has the charac-teristics of mobility and works effectively under severe environment and electromagnetic interfering conditions.However,military network cannot benefit from existing routing protocol directly;there exists quite many features which are only typical for military network.For example,there are several radios in the same vehicle.This paper presents a new metric for routing,which is employed in A*algorithm.The goal of the metric is tochoose a route of less distance and less transmission delay between a source and a destination.Our metric is a function of the distance between the ends and the bandwidth over the link.Moreover,we take frequency selection into account since a node can work on multi-frequencies.This paper proposed the new metric,and experimented it based on A*algorithm.The simulation results show that this metric can find the optimal route which has less transmission delay compared to the shortest path routing.展开更多
The efficient design of arrival and departure routes in the terminal maneuvering area plays a key role in increasing airport capacity and reducing traffic congestion.In our study,we establish an arrival and departure ...The efficient design of arrival and departure routes in the terminal maneuvering area plays a key role in increasing airport capacity and reducing traffic congestion.In our study,we establish an arrival and departure route planning model in the terminal maneuvering area,taking into account the airspace environmental constraints and aircraft operational constraints.Then the three-dimensional environment modeling method with a high degree of dimensionality reduction is introduced to improve the efficiency of route planning,and routes are planned sequentially using the A^(*)algorithm in a dimensionally reduced environment.Numerical simulation tests,performed on the terminal maneuvering area of Chengdu Shuangliu Airport in China,show the effectiveness of the proposed method.Each route is given two planning schemes considering the maximum and minimum takeoff or descent slope,and a total of seven routes is generated.展开更多
文摘To improve the efficiency and accuracy of path planning for fan inspection tasks in thermal power plants,this paper proposes an intelligent inspection robot path planning scheme based on an improved A^(*)algorithm.The inspection robot utilizes multiple sensors to monitor key parameters of the fans,such as vibration,noise,and bearing temperature,and upload the data to the monitoring center.The robot’s inspection path employs the improved A^(*)algorithm,incorporating obstacle penalty terms,path reconstruction,and smoothing optimization techniques,thereby achieving optimal path planning for the inspection robot in complex environments.Simulation results demonstrate that the improved A^(*)algorithm significantly outperforms the traditional A^(*)algorithm in terms of total path distance,smoothness,and detour rate,effectively improving the execution efficiency of inspection tasks.
基金Supported by the EDD of China(No.80912020104)the Science and Technology Commission of Shanghai Municipality(No.22ZR1427700 and No.23692106900).
文摘The traditional A^(*)algorithm exhibits a low efficiency in the path planning of unmanned surface vehicles(USVs).In addition,the path planned presents numerous redundant inflection waypoints,and the security is low,which is not conducive to the control of USV and also affects navigation safety.In this paper,these problems were addressed through the following improvements.First,the path search angle and security were comprehensively considered,and a security expansion strategy of nodes based on the 5×5 neighborhood was proposed.The A^(*)algorithm search neighborhood was expanded from 3×3 to 5×5,and safe nodes were screened out for extension via the node security expansion strategy.This algorithm can also optimize path search angles while improving path security.Second,the distance from the current node to the target node was introduced into the heuristic function.The efficiency of the A^(*)algorithm was improved,and the path was smoothed using the Floyd algorithm.For the dynamic adjustment of the weight to improve the efficiency of DWA,the distance from the USV to the target point was introduced into the evaluation function of the dynamic-window approach(DWA)algorithm.Finally,combined with the local target point selection strategy,the optimized DWA algorithm was performed for local path planning.The experimental results show the smooth and safe path planned by the fusion algorithm,which can successfully avoid dynamic obstacles and is effective and feasible in path planning for USVs.
基金Supported by the Tianjin University of Technology Graduate R esearch Innovation Project(YJ2281).
文摘An improved version of the sparse A^(*)algorithm is proposed to address the common issue of excessive expansion of nodes and failure to consider current ship status and parameters in traditional path planning algorithms.This algorithm considers factors such as initial position and orientation of the ship,safety range,and ship draft to determine the optimal obstacle-avoiding route from the current to the destination point for ship planning.A coordinate transformation algorithm is also applied to convert commonly used latitude and longitude coordinates of ship travel paths to easily utilized and analyzed Cartesian coordinates.The algorithm incorporates a hierarchical chart processing algorithm to handle multilayered chart data.Furthermore,the algorithm considers the impact of ship length on grid size and density when implementing chart gridification,adjusting the grid size and density accordingly based on ship length.Simulation results show that compared to traditional path planning algorithms,the sparse A^(*)algorithm reduces the average number of path points by 25%,decreases the average maximum storage node number by 17%,and raises the average path turning angle by approximately 10°,effectively improving the safety of ship planning paths.
基金supported by the National Nature Science Foundation of China(62203299,62373246,62388101)the Research Fund of State Key Laboratory of Deep-Sea Manned Vehicles(2024SKLDMV04)+1 种基金the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(SL2023MS007)the Startup Fund for Young Faculty at SJTU(24X010502929)。
文摘A safe and reliable path planning algorithm is fundamental for unmanned surface vehicles(USVs)to perform autonomous navigation tasks.However,a single global or local planning strategy cannot fully meet the requirements of complex maritime environments.Global planning alone cannot effectively handle dynamic obstacles,while local planning alone may fall into local optima.To address these issues,this paper proposes a multi-dynamic-obstacle avoidance path planning method that integrates an improved A^(*)algorithm with the dynamic window approach(DWA).The traditional A^(*)algorithm often generates paths that are too close to obstacle boundaries and contain excessive turning points,whereas the traditional DWA tends to skirt densely clustered obstacles,resulting in longer routes and insufficient dynamic obstacle avoidance.To overcome these limitations,improved versions of both algorithms are developed.Key points extracted from the optimized A^(*)path are used as intermediate start-destination pairs for the improved DWA,and the weights of the DWA evaluation function are adjusted to achieve effective fusion.Furthermore,a multi-dynamic-obstacle avoidance strategy is designed for complex navigation scenarios.Simulation results demonstrate that the USV can adaptively switch between dynamic obstacle avoidance and path tracking based on obstacle distribution,validating the effectiveness of the proposed method.
基金Supported by the Natural Science Foundation of Jiangsu Province (BK20211037)the Science and Technology Development Fund of Wuxi (N20201011)the Nanjing University of Information Science and Technology Wuxi Campus District graduate innovation Project。
文摘Background Automatic guided vehicles(AGVs)have developed rapidly in recent years and have been used in several fields,including intelligent transportation,cargo assembly,military testing,and others.A key issue in these applications is path planning.Global path planning results based on known environmental information are used as the ideal path for AGVs combined with local path planning to achieve safe and rapid arrival at the destination.Using the global planning method,the ideal path should meet the requirements of as few turns as possible,a short planning time,and continuous path curvature.Methods We propose a global path-planning method based on an improved A^(*)algorithm.The robustness of the algorithm was verified by simulation experiments in typical multiobstacle and indoor scenarios.To improve the efficiency of the path-finding time,we increase the heuristic information weight of the target location and avoid invalid cost calculations of the obstacle areas in the dynamic programming process.Subsequently,the optimality of the number of turns in the path is ensured based on the turning node backtracking optimization method.Because the final global path needs to satisfy the AGV kinematic constraints and curvature continuity condition,we adopt a curve smoothing scheme and select the optimal result that meets the constraints.Conclusions Simulation results show that the improved algorithm proposed in this study outperforms the traditional method and can help AGVs improve the efficiency of task execution by planning a path with low complexity and smoothness.Additionally,this scheme provides a new solution for global path planning of unmanned vehicles.
文摘In the current era of intelligent technologies,comprehensive and precise regional coverage path planning is critical for tasks such as environmental monitoring,emergency rescue,and agricultural plant protection.Owing to their exceptional flexibility and rapid deployment capabilities,unmanned aerial vehicles(UAVs)have emerged as the ideal platforms for accomplishing these tasks.This study proposes a swarm A^(*)-guided Deep Q-Network(SADQN)algorithm to address the coverage path planning(CPP)problem for UAV swarms in complex environments.Firstly,to overcome the dependency of traditional modeling methods on regular terrain environments,this study proposes an improved cellular decomposition method for map discretization.Simultaneously,a distributed UAV swarm system architecture is adopted,which,through the integration of multi-scale maps,addresses the issues of redundant operations and flight conflicts inmulti-UAV cooperative coverage.Secondly,the heuristic mechanism of the A^(*)algorithmis combinedwith full-coverage path planning,and this approach is incorporated at the initial stage ofDeep Q-Network(DQN)algorithm training to provide effective guidance in action selection,thereby accelerating convergence.Additionally,a prioritized experience replay mechanism is introduced to further enhance the coverage performance of the algorithm.To evaluate the efficacy of the proposed algorithm,simulation experiments were conducted in several irregular environments and compared with several popular algorithms.Simulation results show that the SADQNalgorithmoutperforms othermethods,achieving performance comparable to that of the baseline prior algorithm,with an average coverage efficiency exceeding 2.6 and fewer turning maneuvers.In addition,the algorithm demonstrates excellent generalization ability,enabling it to adapt to different environments.
基金supported by the fundings from 2024 Young Talents Program for Science and Technology Thinking Tanks(No.XMSB20240711041)2024 Student Research Program on Dynamic Simulation and Force-on-Force Exercise of Nuclear Security in 3D Interactive Environment Using Reinforcement Learning,Natural Science Foundation of Top Talent of SZTU(No.GDRC202407)+2 种基金Shenzhen Science and Technology Program(No.KCXFZ20240903092603005)Shenzhen Science and Technology Program(No.JCYJ20241202124703004)Shenzhen Science and Technology Program(No.KJZD20230923114117032)。
文摘Vulnerability assessment is a systematic process to identify security gaps in the design and evaluation of physical protection systems.Adversarial path planning is a widely used method for identifying potential vulnerabilities and threats to the security and resilience of critical infrastructures.However,achieving efficient path optimization in complex large-scale three-dimensional(3D)scenes remains a significant challenge for vulnerability assessment.This paper introduces a novel A^(*)-algorithmic framework for 3D security modeling and vulnerability assessment.Within this framework,the 3D facility models were first developed in 3ds Max and then incorporated into Unity for A^(*)heuristic pathfinding.The A^(*)-heuristic pathfinding algorithm was implemented with a geometric probability model to refine the detection and distance fields and achieve a rational approximation of the cost to reach the goal.An admissible heuristic is ensured by incorporating the minimum probability of detection(P_(D)^(min))and diagonal distance to estimate the heuristic function.The 3D A^(*)heuristic search was demonstrated using a hypothetical laboratory facility,where a comparison was also carried out between the A^(*)and Dijkstra algorithms for optimal path identification.Comparative results indicate that the proposed A^(*)-heuristic algorithm effectively identifies the most vulnerable adversarial pathfinding with high efficiency.Finally,the paper discusses hidden phenomena and open issues in efficient 3D pathfinding for security applications.
文摘Networked rural electrification is an alternative approach to accelerate rural electrification.Using satellite photos and GIS tools,an electrical distribution network is used to connect villages and properly located generation facilities together to reduce electrification cost.To design the network,optimal paths connecting all node-pairs are identified,followed by finding a network topology that minimizes cost.Earlier work has illustrated that A*(A-star,an optimal path-finding algorithm)is inefficient for this application due to the complex topography in rural areas.The multiplier-accelerated A*(MAA*)algorithm overcomes key performance issues,but,like A*,produces only one path connecting each node-pair.Relying on one path increases project risk because adverse conditions,such as inaccurate GIS estimation,unexpected soil conditions,land-rights disputes,political issues,etc.can occur during implementation.In this paper,a hybrid path-finding method combining genetic algorithm and A*/MAA*algorithm is proposed.The proposed method provides a family of near-optimal paths instead of a single optimal path for routing.A family of paths allows a project implementer to quickly adapt to unexpected situations as new information becomes available,and flexibly change network topology before or during implementation with minimal impact on project cost.
基金supported by the National Natural Science Foundation of China(No.11972190)。
文摘Aimed at the safety of helicopter flight in the highly dynamic wind field of urban lowaltitude environment,a wind field simulation and reconstruction method based on unsteady Reynolds-Averaged Navier-Stokes(RANS)and Snapshot Proper Orthogonal Decomposition(Snapshot POD)is proposed in this paper.A comprehensive flight simulation platform is developed,integrating the simulated wind field,a helicopter flight dynamic model,an explicit ModelFollowing Control System(MFCS),and a simplified precision pilot model.Focusing on the issue of airflow disturbances from nearby obstacles in urban environments,a spatiotemporal,dualsource wind-induced threat identification model is established,which fuses turbulence threat and operational exceedance threat,and is incorporated into the construction of safety maps used for trajectory planning.The neighborhood search strategy of the A*algorithm is improved to enhance the trajectory's environmental adaptability,forming an automatic helicopter flight simulation method for complex urban wind environments,integrating wind field prediction,trajectory planning,and flight simulation.Applied to real-world environment flight simulation,the Improved Safety Map-based A*method(I-SM-A*)can reduce the number of path nodes and approach the target faster compared with the Traditional A*method(Trad-A*).The designed trajectory can effectively isolate the wind-induced threat caused by the building airflow.This results in a reduction in pilot workload,as evidenced by decreases of 10.6%and 8.0%in the time and frequency domains,respectively.The flight simulation platform can accurately track the designed trajectory and achieve reliable automatic flight planning in complex urban windy environments.
文摘Wireless ad hoc network is generally employed in military and emergencies due to its flexibility and easy-to-use.It is suitable for military wireless network that has the charac-teristics of mobility and works effectively under severe environment and electromagnetic interfering conditions.However,military network cannot benefit from existing routing protocol directly;there exists quite many features which are only typical for military network.For example,there are several radios in the same vehicle.This paper presents a new metric for routing,which is employed in A*algorithm.The goal of the metric is tochoose a route of less distance and less transmission delay between a source and a destination.Our metric is a function of the distance between the ends and the bandwidth over the link.Moreover,we take frequency selection into account since a node can work on multi-frequencies.This paper proposed the new metric,and experimented it based on A*algorithm.The simulation results show that this metric can find the optimal route which has less transmission delay compared to the shortest path routing.
基金financially supported in part by the National Natural Science Foundation of China(U1333119)National Science and Technology Major Project(2017-VIII-0003-0114,2017-VIII-0002)Fundamental Research Funds for the Central Universities(56XBA18201,XBC20018,56XBC18206).
文摘The efficient design of arrival and departure routes in the terminal maneuvering area plays a key role in increasing airport capacity and reducing traffic congestion.In our study,we establish an arrival and departure route planning model in the terminal maneuvering area,taking into account the airspace environmental constraints and aircraft operational constraints.Then the three-dimensional environment modeling method with a high degree of dimensionality reduction is introduced to improve the efficiency of route planning,and routes are planned sequentially using the A^(*)algorithm in a dimensionally reduced environment.Numerical simulation tests,performed on the terminal maneuvering area of Chengdu Shuangliu Airport in China,show the effectiveness of the proposed method.Each route is given two planning schemes considering the maximum and minimum takeoff or descent slope,and a total of seven routes is generated.
