High accuracy seamless positioning is required to support a vast number of applications in varying operational environments.Over the last few years,the global positioning system(GPS)has become the de facto technology ...High accuracy seamless positioning is required to support a vast number of applications in varying operational environments.Over the last few years,the global positioning system(GPS)has become the de facto technology for positioning applications.However,its performance is limited in indoor and dense urban environments due to multipath as well as signal attenuation and blockage.A number of techniques integrating GPS with other positioning technologies have been developed to address the limitations of standalone GPS in these difficult environments.While most of the developed techniques cover the outages of GPS in such environments,they do not provide acceptable performance,in terms of positioning accuracy,especially for some mission-critical(e.g.safety)applications.This paper proposes a tightly coupled(i.e.in the measurement domain)GPS/WiFi integration method which,in addition to addressing GPS outages,improves the overall positioning accuracy to the meter-level,thus satisfying the requirements of a number of location based services and intelligent transport systems applications.The performance of the proposed GPS/WiFi integration method is assessed for a number of scenarios in a simulation environment for an identified dense urban area in London,UK.展开更多
This article provides a review on X-ray pulsar-based navigation(XNAV).The review starts with the basic concept of XNAV,and briefly introduces the past,present and future projects concerning XNAV.This paper focuses on ...This article provides a review on X-ray pulsar-based navigation(XNAV).The review starts with the basic concept of XNAV,and briefly introduces the past,present and future projects concerning XNAV.This paper focuses on the advances of the key techniques supporting XNAV,including the navigation pulsar database,the X-ray detection system,and the pulse time of arrival estimation.Moreover,the methods to improve the estimation performance of XNAV are reviewed.Finally,some remarks on the future development of XNAV are provided.展开更多
针对即时配送“最后一公里”的问题,综合利用订单取送点、即时配送骑手历史时空轨迹、兴趣面(area of interest,AOI)空间范围与门禁位置等数据,精确预估AOI内部各兴趣点(point of interest,POI)到相应可通行门禁点的时间、距离及路径。...针对即时配送“最后一公里”的问题,综合利用订单取送点、即时配送骑手历史时空轨迹、兴趣面(area of interest,AOI)空间范围与门禁位置等数据,精确预估AOI内部各兴趣点(point of interest,POI)到相应可通行门禁点的时间、距离及路径。在此基础上设计了配套的调用选优策略,获得最优的末端指引方案,以有效提高即时配送路径质量及时间距离预估准确性。展开更多
Multiple Uninhabited Aerial Vehicles(multi-UAVs)coordinated trajectory replanning is one of the most complicated global optimum problems in multi-UAVs coordinated control.Based on the construction of the basic model o...Multiple Uninhabited Aerial Vehicles(multi-UAVs)coordinated trajectory replanning is one of the most complicated global optimum problems in multi-UAVs coordinated control.Based on the construction of the basic model of multi-UAVs coordinated trajectory replanning,which includes problem description,threat modeling,constraint conditions,coordinated function and coordination mechanism,a novel Max-Min adaptive Ant Colony Optimization(ACO)approach is presented in detail.In view of the characteristics of multi-UAVs coordinated trajectory replanning in dynamic and uncertain environments,the minimum and maximum pheromone trails in ACO are set to enhance the searching capability,and the point pheromone is adopted to achieve the collision avoidance between UAVs at the trajectory planner layer.Considering the simultaneous arrival and the air-space collision avoidance,an Estimated Time of Arrival(ETA)is decided first.Then the trajectory and flight velocity of each UAV are determined.Simulation experiments are performed under the complicated combating environment containing some static threats and popup threats.The results demonstrate the feasibility and the effectiveness of the proposed approach.展开更多
Modular construction (MC) is a sound strategy to alleviate global issues such as housing crisis,labor shortage,and stagnant productivity.Project managers are aspired to achieve a Just-in-Time (JIT) delivery of their M...Modular construction (MC) is a sound strategy to alleviate global issues such as housing crisis,labor shortage,and stagnant productivity.Project managers are aspired to achieve a Just-in-Time (JIT) delivery of their MC logistics.However,the efforts often fall short without the presence of a dedicated Estimated Time of Arrival (ETA) model.This study aims to bridge this gap by developing a MC-oriented ETA model.It does so by first identifying critical factors influencing ETA accuracy in general logistics and then developing an ETA model prototype,which is then calibrated using simulations and data collected from the Internet of Things (IoTs) applied in real-life MC projects in Hong Kong,China.Validated through a cross-border MC project in China’s Greater Bay Area,the MC-oriented ETA model achieved 90.6% prediction accuracy (±10 min),reduced transportation delays by 37.5%,and slashed daily planning time from 46.75 to 18.75 min.It is expected that the ETA model can be used in predictive planning of MC logistics delivery in the future.Ultimately,it can lead to the development of smart logistics planning and control systems to expedite MC housing delivery and alleviate urban congestion in high-density cities,offering valuable insights for policymakers,construction stakeholders,and supply chain managers.展开更多
文摘High accuracy seamless positioning is required to support a vast number of applications in varying operational environments.Over the last few years,the global positioning system(GPS)has become the de facto technology for positioning applications.However,its performance is limited in indoor and dense urban environments due to multipath as well as signal attenuation and blockage.A number of techniques integrating GPS with other positioning technologies have been developed to address the limitations of standalone GPS in these difficult environments.While most of the developed techniques cover the outages of GPS in such environments,they do not provide acceptable performance,in terms of positioning accuracy,especially for some mission-critical(e.g.safety)applications.This paper proposes a tightly coupled(i.e.in the measurement domain)GPS/WiFi integration method which,in addition to addressing GPS outages,improves the overall positioning accuracy to the meter-level,thus satisfying the requirements of a number of location based services and intelligent transport systems applications.The performance of the proposed GPS/WiFi integration method is assessed for a number of scenarios in a simulation environment for an identified dense urban area in London,UK.
基金the National Natural Science Foundation of China(No.61703413)the Science and Technology Innovation Program of Hunan Province,China(No.2021RC3078).
文摘This article provides a review on X-ray pulsar-based navigation(XNAV).The review starts with the basic concept of XNAV,and briefly introduces the past,present and future projects concerning XNAV.This paper focuses on the advances of the key techniques supporting XNAV,including the navigation pulsar database,the X-ray detection system,and the pulse time of arrival estimation.Moreover,the methods to improve the estimation performance of XNAV are reviewed.Finally,some remarks on the future development of XNAV are provided.
文摘针对即时配送“最后一公里”的问题,综合利用订单取送点、即时配送骑手历史时空轨迹、兴趣面(area of interest,AOI)空间范围与门禁位置等数据,精确预估AOI内部各兴趣点(point of interest,POI)到相应可通行门禁点的时间、距离及路径。在此基础上设计了配套的调用选优策略,获得最优的末端指引方案,以有效提高即时配送路径质量及时间距离预估准确性。
基金supported by the Natural Science Foundation of China(Grant no.60604009)Aeronautical Science Foundation of China(Grant no.2006ZC51039,Beijing NOVA Program Foundation of China(Grant no.2007A017)+1 种基金Open Fund of the Provincial Key Laboratory for Information Processing Technology,Suzhou University(Grant no KJS0821)"New Scientific Star in Blue Sky"Talent Program of Beihang University of China
文摘Multiple Uninhabited Aerial Vehicles(multi-UAVs)coordinated trajectory replanning is one of the most complicated global optimum problems in multi-UAVs coordinated control.Based on the construction of the basic model of multi-UAVs coordinated trajectory replanning,which includes problem description,threat modeling,constraint conditions,coordinated function and coordination mechanism,a novel Max-Min adaptive Ant Colony Optimization(ACO)approach is presented in detail.In view of the characteristics of multi-UAVs coordinated trajectory replanning in dynamic and uncertain environments,the minimum and maximum pheromone trails in ACO are set to enhance the searching capability,and the point pheromone is adopted to achieve the collision avoidance between UAVs at the trajectory planner layer.Considering the simultaneous arrival and the air-space collision avoidance,an Estimated Time of Arrival(ETA)is decided first.Then the trajectory and flight velocity of each UAV are determined.Simulation experiments are performed under the complicated combating environment containing some static threats and popup threats.The results demonstrate the feasibility and the effectiveness of the proposed approach.
基金supported by the Innovation and Technology Fund(ITF)(Grant No.ITP/029/20LP)the Public Sector Trial Scheme(PSTS)Fund(Grant No.ITT/004/24LP)of the Innovation and Technology Commission(ITC)of Hong Kong,China.
文摘Modular construction (MC) is a sound strategy to alleviate global issues such as housing crisis,labor shortage,and stagnant productivity.Project managers are aspired to achieve a Just-in-Time (JIT) delivery of their MC logistics.However,the efforts often fall short without the presence of a dedicated Estimated Time of Arrival (ETA) model.This study aims to bridge this gap by developing a MC-oriented ETA model.It does so by first identifying critical factors influencing ETA accuracy in general logistics and then developing an ETA model prototype,which is then calibrated using simulations and data collected from the Internet of Things (IoTs) applied in real-life MC projects in Hong Kong,China.Validated through a cross-border MC project in China’s Greater Bay Area,the MC-oriented ETA model achieved 90.6% prediction accuracy (±10 min),reduced transportation delays by 37.5%,and slashed daily planning time from 46.75 to 18.75 min.It is expected that the ETA model can be used in predictive planning of MC logistics delivery in the future.Ultimately,it can lead to the development of smart logistics planning and control systems to expedite MC housing delivery and alleviate urban congestion in high-density cities,offering valuable insights for policymakers,construction stakeholders,and supply chain managers.
