The GaoFen7(GF7)optical satellite is the first Chinese civilian sub-meter high-resolution stereo mapping satellite and is equipped with a double linear array camera and laser altimeter to achieve large-scale topograph...The GaoFen7(GF7)optical satellite is the first Chinese civilian sub-meter high-resolution stereo mapping satellite and is equipped with a double linear array camera and laser altimeter to achieve large-scale topographic mapping.To improve the accuracy of attitude determination,an attitude determination system comprised of four star sensors is loaded.According to the measurement accuracy and steady performance,the star sensors 1a and 1b is usually used together for satellite attitude calculation,which is called the conventional mode of attitude determination.Then,the combination of star sensors 2a and 2b is called the unconventional mode of attitude determination.Affected by variations in the incident angle of sunlight and solar radiation,thermal deformation occurs in the body and installation structure of the star sensor,which causes Attitude Low-Frequency Error(ALFE)and seriously influences the consistency of attitude determination results of different combination modes for multiple star sensors system.This study proposes an ALFE analysis and calibration approach for the multiple star sensors system of GF7 satellite to ensure the consistency of attitude determination results of different combination modes.Based on the statistical characteristics of the angles of the three axes,the installation parameters of the four star sensors are first calibrated.After analyzing the characteristics of the optical axis angles within 1420 orbit periods over 135 days,the segmented ALFE compensation model between the unconventional and conventional modes is proposed based on the Fourier series model and input parameter of latitude.Based on the on-orbit installation parameters and the ALFE model,the precise attitude determination results of the unconventional mode are calculated.Experimental results show that the attitude determination consistency after compensation is better than 2″.Moreover,the reliable application time range of the compensation model is 30 days to satisfy the requirements for high-precision attitude determination of GF7 satellite.展开更多
This paper is concerned with the recursive filtering problem for a class of discrete-time nonlinear stochastic systems in the presence of multi-sensor measurement delay. The delay occurs in a multi-step and asynchrono...This paper is concerned with the recursive filtering problem for a class of discrete-time nonlinear stochastic systems in the presence of multi-sensor measurement delay. The delay occurs in a multi-step and asynchronous manner, and the delay probability of each sensor is assumed to be known or unknown. Firstly, a new model is constructed to describe the measurement process, based on which a new particle filter is developed with the ability to fuse multi-sensor information in the case of known delay probability.In addition, an online delay probability estimation module is introduced in the particle filtering framework, which leads to another new filter that can be implemented without the prior knowledge of delay probability. More importantly, since there is no complex iterative operation, the resulting filter can be implemented recursively and is suitable for many real-time applications. Simulation results show the effectiveness of the proposed filters.展开更多
Compared to 3D object detection using a single camera,multiple cameras can overcome some limitations on field-of-view,occlusion,and low detection confidence.This study employs multiple surveillance cameras and develop...Compared to 3D object detection using a single camera,multiple cameras can overcome some limitations on field-of-view,occlusion,and low detection confidence.This study employs multiple surveillance cameras and develops a cooperative 3D object detection and tracking framework by incorporating temporal and spatial information.The framework consists of a 3D vehicle detection model,cooperatively spatial-temporal relation scheme,and heuristic camera constellation method.Specifically,the proposed cross-camera association scheme combines the geometric relationship between multiple cameras and objects in corresponding detections.The spatial-temporal method is designed to associate vehicles between different points of view at a single timestamp and fulfill vehicle tracking in the time aspect.The proposed framework is evaluated based on a synthetic cooperative dataset and shows high reliability,where the cooperative perception can recall more than 66%of the trajectory instead of 11%for single-point sensing.This could contribute to full-range surveillance for intelligent transportation systems.展开更多
In order to apply compressive sensing in wireless sensor network, inside the nodes cluster classified by the spatial correlation, we propose that a cluster head adopts free space optical communication with space divis...In order to apply compressive sensing in wireless sensor network, inside the nodes cluster classified by the spatial correlation, we propose that a cluster head adopts free space optical communication with space division multiple access, and a sensor node uses a modulating retro-reflector for communication. Thus while a random sampling matrix is used to guide the establishment of links between head cluster and sensor nodes, the random linear projection is accomplished. To establish multiple links at the same time, an optical space division multiple access antenna is designed. It works in fixed beams switching mode and consists of optic lens with a large field of view（FOV）, fiber array on the focal plane which is used to realize virtual channels segmentation, direction of arrival sensor, optical matrix switch and controller. Based on the angles of nodes＇ laser beams, by dynamically changing the route, optical matrix switch actualizes the multi-beam full duplex tracking receiving and transmission. Due to the structure of fiber array, there will be several fade zones both in the focal plane and in lens＇ FOV. In order to lower the impact of fade zones and harmonize multibeam, a fiber array adjustment is designed. By theoretical, simulated and experimental study, the antenna＇s qualitative feasibility is validated.展开更多
Textile-based,chip-less,wireless body sensor networks(WBANs)offer continuous,wireless monitoring of physiological signals from passive sensors distributed across body locations,representing a promising solution for da...Textile-based,chip-less,wireless body sensor networks(WBANs)offer continuous,wireless monitoring of physiological signals from passive sensors distributed across body locations,representing a promising solution for daily wearable sensing.Here,we introduce an all-textile,chipless,and battery-free textile-based body sensor network(tBSN)capable of simultaneously monitoring multiple passive sensors across the body.The tBSN is seamlessly integrated into conventional textiles via digital embroidery of flexible conductive fiber electrodes.Single-node tBSN exhibits robust wireless transmission over interconnect up to 40 cm and demonstrates durability under various conditions.By arranging multiple single-node sensor networks into a concentric multi-hub antenna architecture,we extend the system to a multi-node tBSN,enabling simultaneous wireless monitoring of distributed passive sensors within a single frequency scan.A wearable garment incorporating the multi-node tBSN tracked biomechanical signals from the vastus lateralis and knee joint during motion,highlighting its significant potential for personalized rehabilitation,fitness-assistive technologies,and advanced gait analysis.展开更多
As one of the promising human–machine interfaces,wearable sensors play an important role in modern society,which advances the development of wearable fields,especially in the promising applications of electronic skin...As one of the promising human–machine interfaces,wearable sensors play an important role in modern society,which advances the development of wearable fields,especially in the promising applications of electronic skin(e-skin),robotics,prosthetics,healthcare.In the last decades,wearable sensors tend to be capable of attractive capabilities such as miniaturization,multifunction,smart integration,wearable properties such as lightweight,flexibility,stretchability,conformability for wider applications.In this work,we developed a stretchable multifunctional sensor based on porous silver nanowire/silicone rubber conductive film(P-AgNW/SR).Its unique structural configuration,i.e.,an assembly of the P-AgNW/SR with good conductivity,stability,resistance response,the insulated silicone rubber layer,provided the feasibility for realizing multiple sensing capabilities.Specifically,porous microstructures of the P-AgNW/SR made the device to be used for pressure sensing,exhibiting outstanding dynamic and static resistive responsive behaviors and having a maximum sensitivity of 9.062%∙N^(−1) in a continuous compressive force range of~16 N.With the merit of the good piezoresistive property of AgNW/SR networks embedded into the surface of micropores of the P-AgNW/SR,the device was verified to be a temperature sensor for detecting temperature changes in the human body and environment.The temperature sensor had good sensitivity of 0.844%∙℃^(−1),high linearity of 0.999 in the range of 25–125℃,remarkable dynamic stability.Besides,the developed sensor was demonstrated to be a single electrode-triboelectric sensor for active sensing,owing to the unique assembly of the conductive PAgNW/SR electrode and the silicone rubber friction layer.Based on the coupling effect of the triboelectrification and electrostatic induction,the generated electrical signals could be used to sense the human motions,according to the quantitative correlation between the human motions and the features in amplitude and waveform of the output signals.Thus,the developed stretchable sensor successfully achieved the integration of two types of passive sensing capabilities,i.e.,pressure and temperature sensing,and one type of active sensing capability,i.e.,triboelectric sensing,demonstrating the feasibility of monitoring multiple variables of the human body and environment.展开更多
Purpose-This paper aims to describe a recently proposed algorithm in terrain-based cooperative UAV mapping of the unknown complex obstacle in a stationary environment where the complex obstacles are represented as cur...Purpose-This paper aims to describe a recently proposed algorithm in terrain-based cooperative UAV mapping of the unknown complex obstacle in a stationary environment where the complex obstacles are represented as curved in nature.It also aims to use an extended Kalman filter(EKF)to estimate the fused position of the UAVs and to apply the 2-D splinegon technique to build the map of the complex shaped obstacles.The path of the UAVs are dictated by the Dubins path planning algorithm.The focus is to achieve a guaranteed performance of sensor based mapping of the uncertain environments using multiple UAVs.Design/methodology/approach–An extended Kalman filter is used to estimate the position of the UAVs,and the 2-D splinegon technique is used to build the map of the complex obstacle where the path of the UAVs are dictated by the Dubins path planning algorithm.Findings-The guaranteed performance is quantified by explicit bounds of the position estimate of the multiple UAVs for mapping of the complex obstacles using 2-D splinegon technique.This is a newly proposed algorithm,the most efficient and a robust way in terrain based mapping of the complex obstacles.The proposed method can provide mathematically provable and performance guarantees that are achievable in practice.Originality/value-The paper describes the main contribution in mapping the complex shaped curvilinear objects using the 2-D splinegon technique.This is a new approach where the fused EKF estimated positions are used with the limited number of sensors’measurements in building the map of the complex obstacles.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars[grant number 61825103]the Shanghai Aerospace Science and Technology Innovation Fund.
文摘The GaoFen7(GF7)optical satellite is the first Chinese civilian sub-meter high-resolution stereo mapping satellite and is equipped with a double linear array camera and laser altimeter to achieve large-scale topographic mapping.To improve the accuracy of attitude determination,an attitude determination system comprised of four star sensors is loaded.According to the measurement accuracy and steady performance,the star sensors 1a and 1b is usually used together for satellite attitude calculation,which is called the conventional mode of attitude determination.Then,the combination of star sensors 2a and 2b is called the unconventional mode of attitude determination.Affected by variations in the incident angle of sunlight and solar radiation,thermal deformation occurs in the body and installation structure of the star sensor,which causes Attitude Low-Frequency Error(ALFE)and seriously influences the consistency of attitude determination results of different combination modes for multiple star sensors system.This study proposes an ALFE analysis and calibration approach for the multiple star sensors system of GF7 satellite to ensure the consistency of attitude determination results of different combination modes.Based on the statistical characteristics of the angles of the three axes,the installation parameters of the four star sensors are first calibrated.After analyzing the characteristics of the optical axis angles within 1420 orbit periods over 135 days,the segmented ALFE compensation model between the unconventional and conventional modes is proposed based on the Fourier series model and input parameter of latitude.Based on the on-orbit installation parameters and the ALFE model,the precise attitude determination results of the unconventional mode are calculated.Experimental results show that the attitude determination consistency after compensation is better than 2″.Moreover,the reliable application time range of the compensation model is 30 days to satisfy the requirements for high-precision attitude determination of GF7 satellite.
基金supported by the National Natural Science Foundation of China(6147322711472222)+3 种基金the Fundamental Research Funds for the Central Universities(3102015ZY001)the Aerospace Technology Support Fund of China(2014-HT-XGD)the Natural Science Foundation of Shaanxi Province(2015JM6304)the Aeronautical Science Foundation of China(20151353018)
文摘This paper is concerned with the recursive filtering problem for a class of discrete-time nonlinear stochastic systems in the presence of multi-sensor measurement delay. The delay occurs in a multi-step and asynchronous manner, and the delay probability of each sensor is assumed to be known or unknown. Firstly, a new model is constructed to describe the measurement process, based on which a new particle filter is developed with the ability to fuse multi-sensor information in the case of known delay probability.In addition, an online delay probability estimation module is introduced in the particle filtering framework, which leads to another new filter that can be implemented without the prior knowledge of delay probability. More importantly, since there is no complex iterative operation, the resulting filter can be implemented recursively and is suitable for many real-time applications. Simulation results show the effectiveness of the proposed filters.
基金the National Natural Science Foundation of China(No.61873167)the Automotive Industry Science and Technology Development Foundation of Shanghai(No.1904)。
文摘Compared to 3D object detection using a single camera,multiple cameras can overcome some limitations on field-of-view,occlusion,and low detection confidence.This study employs multiple surveillance cameras and develops a cooperative 3D object detection and tracking framework by incorporating temporal and spatial information.The framework consists of a 3D vehicle detection model,cooperatively spatial-temporal relation scheme,and heuristic camera constellation method.Specifically,the proposed cross-camera association scheme combines the geometric relationship between multiple cameras and objects in corresponding detections.The spatial-temporal method is designed to associate vehicles between different points of view at a single timestamp and fulfill vehicle tracking in the time aspect.The proposed framework is evaluated based on a synthetic cooperative dataset and shows high reliability,where the cooperative perception can recall more than 66%of the trajectory instead of 11%for single-point sensing.This could contribute to full-range surveillance for intelligent transportation systems.
基金supported by the National Natural Science Foundation of China(61372069)and the"111"Project(B08038)
文摘In order to apply compressive sensing in wireless sensor network, inside the nodes cluster classified by the spatial correlation, we propose that a cluster head adopts free space optical communication with space division multiple access, and a sensor node uses a modulating retro-reflector for communication. Thus while a random sampling matrix is used to guide the establishment of links between head cluster and sensor nodes, the random linear projection is accomplished. To establish multiple links at the same time, an optical space division multiple access antenna is designed. It works in fixed beams switching mode and consists of optic lens with a large field of view（FOV）, fiber array on the focal plane which is used to realize virtual channels segmentation, direction of arrival sensor, optical matrix switch and controller. Based on the angles of nodes＇ laser beams, by dynamically changing the route, optical matrix switch actualizes the multi-beam full duplex tracking receiving and transmission. Due to the structure of fiber array, there will be several fade zones both in the focal plane and in lens＇ FOV. In order to lower the impact of fade zones and harmonize multibeam, a fiber array adjustment is designed. By theoretical, simulated and experimental study, the antenna＇s qualitative feasibility is validated.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2021-NR061513,RS-2025-16071089)supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(RS-2025-25420118)+1 种基金supported by the Council of Science&Technology(NST)grant by the Korea government(NSIT)(No.GTL25041-000)the DGIST R&D Program of the Ministry of Science and ICT(2025010373,25-IRJoint-06).
文摘Textile-based,chip-less,wireless body sensor networks(WBANs)offer continuous,wireless monitoring of physiological signals from passive sensors distributed across body locations,representing a promising solution for daily wearable sensing.Here,we introduce an all-textile,chipless,and battery-free textile-based body sensor network(tBSN)capable of simultaneously monitoring multiple passive sensors across the body.The tBSN is seamlessly integrated into conventional textiles via digital embroidery of flexible conductive fiber electrodes.Single-node tBSN exhibits robust wireless transmission over interconnect up to 40 cm and demonstrates durability under various conditions.By arranging multiple single-node sensor networks into a concentric multi-hub antenna architecture,we extend the system to a multi-node tBSN,enabling simultaneous wireless monitoring of distributed passive sensors within a single frequency scan.A wearable garment incorporating the multi-node tBSN tracked biomechanical signals from the vastus lateralis and knee joint during motion,highlighting its significant potential for personalized rehabilitation,fitness-assistive technologies,and advanced gait analysis.
基金the National Natural Science Foundation of China(Nos.62074029,61905035,61971108,62004029,and 51905554)the Key Research and Development Program of Sichuan Province(Nos.2022JDTD0020,2022YFG0163,and 2020ZHCG0038)+1 种基金the Sichuan Science and Technology Program(No.2020YJ0015)the Fundamental Research Funds for the Central Universities(No.ZYGX2019Z002).
文摘As one of the promising human–machine interfaces,wearable sensors play an important role in modern society,which advances the development of wearable fields,especially in the promising applications of electronic skin(e-skin),robotics,prosthetics,healthcare.In the last decades,wearable sensors tend to be capable of attractive capabilities such as miniaturization,multifunction,smart integration,wearable properties such as lightweight,flexibility,stretchability,conformability for wider applications.In this work,we developed a stretchable multifunctional sensor based on porous silver nanowire/silicone rubber conductive film(P-AgNW/SR).Its unique structural configuration,i.e.,an assembly of the P-AgNW/SR with good conductivity,stability,resistance response,the insulated silicone rubber layer,provided the feasibility for realizing multiple sensing capabilities.Specifically,porous microstructures of the P-AgNW/SR made the device to be used for pressure sensing,exhibiting outstanding dynamic and static resistive responsive behaviors and having a maximum sensitivity of 9.062%∙N^(−1) in a continuous compressive force range of~16 N.With the merit of the good piezoresistive property of AgNW/SR networks embedded into the surface of micropores of the P-AgNW/SR,the device was verified to be a temperature sensor for detecting temperature changes in the human body and environment.The temperature sensor had good sensitivity of 0.844%∙℃^(−1),high linearity of 0.999 in the range of 25–125℃,remarkable dynamic stability.Besides,the developed sensor was demonstrated to be a single electrode-triboelectric sensor for active sensing,owing to the unique assembly of the conductive PAgNW/SR electrode and the silicone rubber friction layer.Based on the coupling effect of the triboelectrification and electrostatic induction,the generated electrical signals could be used to sense the human motions,according to the quantitative correlation between the human motions and the features in amplitude and waveform of the output signals.Thus,the developed stretchable sensor successfully achieved the integration of two types of passive sensing capabilities,i.e.,pressure and temperature sensing,and one type of active sensing capability,i.e.,triboelectric sensing,demonstrating the feasibility of monitoring multiple variables of the human body and environment.
文摘Purpose-This paper aims to describe a recently proposed algorithm in terrain-based cooperative UAV mapping of the unknown complex obstacle in a stationary environment where the complex obstacles are represented as curved in nature.It also aims to use an extended Kalman filter(EKF)to estimate the fused position of the UAVs and to apply the 2-D splinegon technique to build the map of the complex shaped obstacles.The path of the UAVs are dictated by the Dubins path planning algorithm.The focus is to achieve a guaranteed performance of sensor based mapping of the uncertain environments using multiple UAVs.Design/methodology/approach–An extended Kalman filter is used to estimate the position of the UAVs,and the 2-D splinegon technique is used to build the map of the complex obstacle where the path of the UAVs are dictated by the Dubins path planning algorithm.Findings-The guaranteed performance is quantified by explicit bounds of the position estimate of the multiple UAVs for mapping of the complex obstacles using 2-D splinegon technique.This is a newly proposed algorithm,the most efficient and a robust way in terrain based mapping of the complex obstacles.The proposed method can provide mathematically provable and performance guarantees that are achievable in practice.Originality/value-The paper describes the main contribution in mapping the complex shaped curvilinear objects using the 2-D splinegon technique.This is a new approach where the fused EKF estimated positions are used with the limited number of sensors’measurements in building the map of the complex obstacles.
