The aim of this study is to propose a novel system that has an ability to detect intra-fractional motion during radiotherapy treatment in real-time using three-dimensional surface taken by a depth camera, Microsoft Ki...The aim of this study is to propose a novel system that has an ability to detect intra-fractional motion during radiotherapy treatment in real-time using three-dimensional surface taken by a depth camera, Microsoft Kinect v1. Our approach introduces three new aspects for three-dimensional surface tracking in radiotherapy treatment. The first aspect is a new algorithm for noise reduction of depth values. Ueda’s algorithm was implemented and enabling a fast least square regression of depth values. The second aspect is an application for detection of patient’s motion at multiple points in thracoabdominal regions. The third aspect is an estimation of three-dimensional surface from multiple depth values. For evaluation of noise reduction by Ueda’s algorithm, two respiratory patterns are measured by the Kinect as well as a laser range meter. The resulting cross correlation coefficients between the laser range meter and the Kinect were 0.982 for abdominal respiration and 0.995 for breath holding. Moreover, the mean cross correlation coefficients between the signals of our system and the signals of Anzai with respect to participant’s respiratory motion were 0.90 for thoracic respiration and 0.93 for abdominal respiration, respectively. These results proved that the performance of the developed system was comparable to existing motion monitoring devices. Reconstruction of three-dimensional surface also enabled us to detect the irregular motion and breathing arrest by comparing the averaged depth with predefined threshold values.展开更多
A visible magnified and simulated nozzle was designed and installed on a winding machine according to the similarity principle of Reynolds number, to study the yarn motion track in hairiness-reducing nozzle. High-spee...A visible magnified and simulated nozzle was designed and installed on a winding machine according to the similarity principle of Reynolds number, to study the yarn motion track in hairiness-reducing nozzle. High-speed photography was used to observe the yam instantaneous motion state in the nozzle. The results show that the yarn motion track seems to be a cylindrical helix which is close to inner wall in the twisting chamber and kept the same with different technical parameters, such as diameter of the twisting chamber and jet pressure in orifices. According to simulation results and reasonable simplification, the motion track equation and the rotational equation of the yarn could be derived. The velocity of the swirl and hairiness is faster than that of the yarn balloon, so there is enough time for hairiness to be wrapped into the main body of yarn and hence the hairiness is reduced.展开更多
Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in m...Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in measuring upper extremity motion from different angles.Ten healthy participants performed elbow and shoulder extension/flexion along frontal and median anatomical planes for ten pace⁃controlled repetitions,during which the spatiotemporal positions of upper extremity joints were concurrently recorded by two sensors from 0°and 45°viewing angles.Reliability between the two sensors were evaluated using Pearson correlation coefficient,intra⁃class correlation coefficients,and 95%limits of agreement and coefficient of variation.Worse reliability was observed when possibility of occlusion was higher.However,better reliability was found when longer observation interval(10 s)was used as elementary measuring unit than shorter observation interval(2 s).The overall angular reliability of activity as displacement or changes in angle was not satisfactory.The results are expected to inform the industry for the extension of MFS to clinic applications.展开更多
To extract and tr ack moving objects is usually one of the most important tasks of intelligent video surveillance systems. This paper presents a fast and adaptive background subtraction alg...To extract and tr ack moving objects is usually one of the most important tasks of intelligent video surveillance systems. This paper presents a fast and adaptive background subtraction algorithm and the motion tracking process using this algorithm. The algorithm uses only luminance components of sampled image sequence pixels and models every pixel in a statistical model. The algorithm is characterized by its ability of real time detecting sudden lighting changes, and extracting and tracking motion objects faster. It is shown that our algorithm can be realized with lower time and space complexity and adjustable object detection error rate with comparison to other background subtraction algorithms. Making use of the algorithm, an indoor monitoring system is also worked out and the motion tracking process is presented in this paper. Experimental results testify the algorithm's good performances when used in an indoor monitoring system.展开更多
The accurate assessment of cardiac motion is crucial for diagnosing and monitoring cardiovascular diseases.In this context,digital volume correlation(DVC)has emerged as a promising technique for tracking cardiac motio...The accurate assessment of cardiac motion is crucial for diagnosing and monitoring cardiovascular diseases.In this context,digital volume correlation(DVC)has emerged as a promising technique for tracking cardiac motion from cardiac computed tomography angiographic(CTA)images.This paper presents a comprehensive performance evaluation of the DVC method,specifically focusing on tracking the motion of the left atrium using cardiac CTA data.The study employed a comparative experimental approach while simultaneously optimizing the existing DVC algorithm.Multiple sets of controlled experiments were designed to conduct quantitative analyses on the parameters“radius”and“step”.The results revealed that the optimized DVC algorithm enhanced tracking accuracy within a reasonable computational time.These findings contributed to the understanding of the efficacy and limitations of the DVC algorithm in analyzing heart deformation.展开更多
Motion tracking has attracted great attention in the fields of real-time tracking,nanorobotics,and targeted therapy.For achieving more accurate motion tracking,the highly sensitive position-sensitive detector(PSD)is d...Motion tracking has attracted great attention in the fields of real-time tracking,nanorobotics,and targeted therapy.For achieving more accurate motion tracking,the highly sensitive position-sensitive detector(PSD)is desirable.Here,we demonstrate a meliorated PSD based on graphene-Si heterojunction for motion tracking.The position sensitivity of PSD was improved by employing surface engineering of graphene.Through modulating the transport property of graphene,nearly 20-fold increase of sensitivity was achieved under weak light,and at the same time,the detection limit power was reduced to^2 nW.A motion tracking system was developed based on the improved PSD,and human arm swing was tracked,which demonstrated high sensitivity and real-time tracking capabilities of the PSD.In addition,the PSD can support up to^10 kHz high-frequency tracking.This work provides a new strategy for improving the performance of PSD,and promotes the development of two-dimensional materials in novel optoelectronic devices.展开更多
Motion tracking via Inertial Measurement Units(IMUs)on mobile and wearable devices has attracted significant interest in recent years.High-accuracy IMU-tracking can be applied in various applications,such as indoor na...Motion tracking via Inertial Measurement Units(IMUs)on mobile and wearable devices has attracted significant interest in recent years.High-accuracy IMU-tracking can be applied in various applications,such as indoor navigation,gesture recognition,text input,etc.Many efforts have been devoted to improving IMU-based motion tracking in the last two decades,from early calibration techniques on ships or airplanes,to recent arm motion models used on wearable smart devices.In this paper,we present a comprehensive survey on IMU-tracking techniques on mobile and wearable devices.We also reveal the key challenges in IMU-based motion tracking on mobile and wearable devices and possible directions to address these challenges.展开更多
The aye-aye(Daubentonia madagascariensis)is a nocturnal lemur native to the island of Madagascar with a unique thin middle finger.Its slender third digit has a remarkably specific adaptation,allowing them to perform t...The aye-aye(Daubentonia madagascariensis)is a nocturnal lemur native to the island of Madagascar with a unique thin middle finger.Its slender third digit has a remarkably specific adaptation,allowing them to perform tap-scanning to locate small cavities beneath tree bark and extract wood-boring larvae from it.As an exceptional active acoustic actuator,this finger makes an aye-aye’s biological system an attractive model for pioneering Nondestructive Evaluation(NDE)methods and robotic systems.Despite the important aspects of the topic in the aye-aye’s unique foraging and its potential contribution to the engineering sensory,little is known about the mechanism and dynamics of this unique finger.This paper used a motion-tracking approach for the aye-aye’s middle finger using simultaneous video graphic capture.To mimic the motion,a two-link robot arm model is designed to reproduce the trajectory.Kinematics formulations were proposed to derive the motion of the middle finger using the Lagrangian method.In addition,a hardware model was developed to simulate the aye-aye’s finger motion.To validate the model,different motion states such as trajectory paths and joint angles,were compared.The simulation results indicate the kinematics of the model were consistent with the actual finger movement.This model is used to understand the aye-aye’s unique tap-scanning process for pioneering new tap-testing NDE strategies for various inspection applications.展开更多
The stabilization and trajectory tracking problems of autonomous airship＇s planar motion are studied. By defining novel configuration error and velocity error, the dynamics of error systems are derived. By applying L...The stabilization and trajectory tracking problems of autonomous airship＇s planar motion are studied. By defining novel configuration error and velocity error, the dynamics of error systems are derived. By applying Lyapunov stability method, the state feedback control laws are designed and the close-loop error systems are proved to be uniformly asymptotically stable by Matrosov theorem. In particular, the controller does not need knowledge on system parameters in the case of set-point stabilization, which makes the controller robust with respect to parameter uncertainty. Numerical simulations illustrate the effectiveness of the controller designed.展开更多
The development of artificial intelligence technology has promoted the rapid improvement of human-computer interaction. This system uses the Kinect visual image sensor to identify human bone data and complete the reco...The development of artificial intelligence technology has promoted the rapid improvement of human-computer interaction. This system uses the Kinect visual image sensor to identify human bone data and complete the recognition of the operator’s movements. Through the filtering process of real-time data by the host computer platform with computer software as the core, the algorithm is programmed to realize the conversion from data to control signals. The system transmits the signal to the lower computer platform with Arduino as the core through the transmission mode of the serial communication, thereby completing the control of the steering gear. In order to verify the feasibility of the theory, the team built a 4-DOF robotic arm control system and completed software development. It can display other functions such as the current bone angle and motion status in real time on the computer operation interface. The experimental data shows that the Kinect-based motion recognition method can effectively complete the tracking of the expected motion and complete the grasping and transfer of the specified objects, which has extremely high operability.展开更多
Target tracking is very important in computer vision and related areas. It is usually difficult to accurately track fast motion target with appearance variations. Sometimes the tracking algorithms fail for heavy appea...Target tracking is very important in computer vision and related areas. It is usually difficult to accurately track fast motion target with appearance variations. Sometimes the tracking algorithms fail for heavy appearance variations. A multiple template method to track fast motion target with appearance changes is presented under the framework of appearance model with Kalman filter. Firstly, we construct a multiple template appearance model, which includes both the original template and templates affinely transformed from original one. Generally speaking, appearance variations of fast motion target can be covered by affine transformation. Therefore, the affine tr templates match the target of appearance variations better than conventional models. Secondly, we present an improved Kalman filter for approx- imate estimating the motion trail of the target and a modified similarity evaluation function for exact matching. The estimation approach can reduce time complexity of the algorithm and keep accuracy in the meantime. Thirdly, we propose an adaptive scheme for updating template set to alleviate the drift problem. The scheme considers the following differences： the weight differences in two successive frames; different types of affine transformation applied to templates. Finally, experiments demonstrate that the proposed algorithm is robust to appearance varia- tion of fast motion target and achieves real-time performance on middle/low-range computing platform.展开更多
Based on previous achievements,a dynamic pressure-sinkage equation for saturated clay is established.First,aquasi-static penetration rate is selected,and the ratio of the dynamic penetration rate to the quasi-static r...Based on previous achievements,a dynamic pressure-sinkage equation for saturated clay is established.First,aquasi-static penetration rate is selected,and the ratio of the dynamic penetration rate to the quasi-static rate is used to characterize the degree of dynamic effect,then theβth power of the ratio is used to quantify the dynamic effect of sinkage.The dynamic effect exponentβis obtained using penetration tests with different penetration rates.Then,a dynamic motion resistance equation for a tracked vehicle is established based on the dynamic pressure-sinkage equation.The equation incorporates both penetration and bulldozing resistance.Finally,a series of simulation experiments with varying travel speeds and slip rates is carried out.The results show that an increase in the speed leads to stronger terrain stiffness,resulting in a decrease in sinkage and motion resistance.However,the enhancement effect becomes weaker with an increase in the travel speed.展开更多
To extract the track parameters of a traffic object in traffic video and identify its motion behavior,a new method is proposed based on CamShift(Continuously Adaptive Mean Shift)and HMM(Hidden Markov Model).First,an o...To extract the track parameters of a traffic object in traffic video and identify its motion behavior,a new method is proposed based on CamShift(Continuously Adaptive Mean Shift)and HMM(Hidden Markov Model).First,an object entering the video scene is located and tracked by the CamShift based algorithm,then its track parameters are obtained.Next,the track parameters are processed to form the observation sequence of HMM,and the motion behavior modeling and probability evaluation are implemented based on HMM.At last,the behavior identification and behavior statistics of the tracked traffic object in video are achieved.Experiments show that this method can be used to sort and recognize the motion behavior of the traffic object by its corresponding behavior track,and to do some statistics or corresponding process schemes.展开更多
To compensate motion errors of images from the parallel-track bistatic synthetic aperture radar（BiSAR）,an improved chirp scaling algorithm（CSA） is proposed.Since velocity vector of the moving aircrafts in the para...To compensate motion errors of images from the parallel-track bistatic synthetic aperture radar（BiSAR）,an improved chirp scaling algorithm（CSA） is proposed.Since velocity vector of the moving aircrafts in the parallel-track BiSAR system can not remain invariant in an aperture,an actual aperture is divided into subapertures so that it is reasonable to assume that the aircrafts move with constant acceleration vector in a subaperture.Based on this model,an improved CSA is derived.The new phase factors incorporate three-dimensional acceleration and velocity.The motion compensation procedure is integrated into the CSA without additional operation required.The simulation results show that the presented algorithm can efficiently resolve motion compensation for parallel-track BiSAR.展开更多
文摘The aim of this study is to propose a novel system that has an ability to detect intra-fractional motion during radiotherapy treatment in real-time using three-dimensional surface taken by a depth camera, Microsoft Kinect v1. Our approach introduces three new aspects for three-dimensional surface tracking in radiotherapy treatment. The first aspect is a new algorithm for noise reduction of depth values. Ueda’s algorithm was implemented and enabling a fast least square regression of depth values. The second aspect is an application for detection of patient’s motion at multiple points in thracoabdominal regions. The third aspect is an estimation of three-dimensional surface from multiple depth values. For evaluation of noise reduction by Ueda’s algorithm, two respiratory patterns are measured by the Kinect as well as a laser range meter. The resulting cross correlation coefficients between the laser range meter and the Kinect were 0.982 for abdominal respiration and 0.995 for breath holding. Moreover, the mean cross correlation coefficients between the signals of our system and the signals of Anzai with respect to participant’s respiratory motion were 0.90 for thoracic respiration and 0.93 for abdominal respiration, respectively. These results proved that the performance of the developed system was comparable to existing motion monitoring devices. Reconstruction of three-dimensional surface also enabled us to detect the irregular motion and breathing arrest by comparing the averaged depth with predefined threshold values.
基金Tianjin Science and Technology Planning Projects,China(No.04310471)
文摘A visible magnified and simulated nozzle was designed and installed on a winding machine according to the similarity principle of Reynolds number, to study the yarn motion track in hairiness-reducing nozzle. High-speed photography was used to observe the yam instantaneous motion state in the nozzle. The results show that the yarn motion track seems to be a cylindrical helix which is close to inner wall in the twisting chamber and kept the same with different technical parameters, such as diameter of the twisting chamber and jet pressure in orifices. According to simulation results and reasonable simplification, the motion track equation and the rotational equation of the yarn could be derived. The velocity of the swirl and hairiness is faster than that of the yarn balloon, so there is enough time for hairiness to be wrapped into the main body of yarn and hence the hairiness is reduced.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51708152)the Science and Technology Innovation Committee of Shenzhen Municipality(Grant No.JCYJ20170811155435737).
文摘Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in measuring upper extremity motion from different angles.Ten healthy participants performed elbow and shoulder extension/flexion along frontal and median anatomical planes for ten pace⁃controlled repetitions,during which the spatiotemporal positions of upper extremity joints were concurrently recorded by two sensors from 0°and 45°viewing angles.Reliability between the two sensors were evaluated using Pearson correlation coefficient,intra⁃class correlation coefficients,and 95%limits of agreement and coefficient of variation.Worse reliability was observed when possibility of occlusion was higher.However,better reliability was found when longer observation interval(10 s)was used as elementary measuring unit than shorter observation interval(2 s).The overall angular reliability of activity as displacement or changes in angle was not satisfactory.The results are expected to inform the industry for the extension of MFS to clinic applications.
文摘To extract and tr ack moving objects is usually one of the most important tasks of intelligent video surveillance systems. This paper presents a fast and adaptive background subtraction algorithm and the motion tracking process using this algorithm. The algorithm uses only luminance components of sampled image sequence pixels and models every pixel in a statistical model. The algorithm is characterized by its ability of real time detecting sudden lighting changes, and extracting and tracking motion objects faster. It is shown that our algorithm can be realized with lower time and space complexity and adjustable object detection error rate with comparison to other background subtraction algorithms. Making use of the algorithm, an indoor monitoring system is also worked out and the motion tracking process is presented in this paper. Experimental results testify the algorithm's good performances when used in an indoor monitoring system.
基金supported by the Australian Research Council(ARC)(Grant No.DP200103492)the National Natural Science Foundation of China(Grant Nos.12172089,12372307,and 61821002)+2 种基金Medical Research Future Fund(Grant Nos.2016165 and 2023977)the CBT Early Career Researcher Grant funded and the Roland Bishop Biomedical Engineering Research Award by Queensland University of Technologythe Springboard Funding and the Global Collaboration Funding by London South Bank University.Computational resources and services used in this work were provided by the High-Performance Computing and Research Support Group,Queensland University of Technology,Brisbane,Australia.
文摘The accurate assessment of cardiac motion is crucial for diagnosing and monitoring cardiovascular diseases.In this context,digital volume correlation(DVC)has emerged as a promising technique for tracking cardiac motion from cardiac computed tomography angiographic(CTA)images.This paper presents a comprehensive performance evaluation of the DVC method,specifically focusing on tracking the motion of the left atrium using cardiac CTA data.The study employed a comparative experimental approach while simultaneously optimizing the existing DVC algorithm.Multiple sets of controlled experiments were designed to conduct quantitative analyses on the parameters“radius”and“step”.The results revealed that the optimized DVC algorithm enhanced tracking accuracy within a reasonable computational time.These findings contributed to the understanding of the efficacy and limitations of the DVC algorithm in analyzing heart deformation.
基金China Postdoctoral Science Foundation,Grant/Award Number:2018M632197Funding of Natural Science Research Projects in Colleges and Universities of Jiangsu Province,Grant/Award Number:18KJD140003+3 种基金National Natural Science Foundation of China,Grant/Award Numbers:11704068,61774034the Fundamental Research Funds for the Central Universities,Grant/Award Number:2242019R20025The National Key Research and Development Program of China,Grant/Award Number:2017YFA0205700the Strategic Priority Research Program of Chinese Academy of Sciences,Grant/Award Number:XDB30000000。
文摘Motion tracking has attracted great attention in the fields of real-time tracking,nanorobotics,and targeted therapy.For achieving more accurate motion tracking,the highly sensitive position-sensitive detector(PSD)is desirable.Here,we demonstrate a meliorated PSD based on graphene-Si heterojunction for motion tracking.The position sensitivity of PSD was improved by employing surface engineering of graphene.Through modulating the transport property of graphene,nearly 20-fold increase of sensitivity was achieved under weak light,and at the same time,the detection limit power was reduced to^2 nW.A motion tracking system was developed based on the improved PSD,and human arm swing was tracked,which demonstrated high sensitivity and real-time tracking capabilities of the PSD.In addition,the PSD can support up to^10 kHz high-frequency tracking.This work provides a new strategy for improving the performance of PSD,and promotes the development of two-dimensional materials in novel optoelectronic devices.
基金part supported by the National Key R&D Program of China(No.2018YFB1004800)the National Natural Science Foundation of China(No.61932013)。
文摘Motion tracking via Inertial Measurement Units(IMUs)on mobile and wearable devices has attracted significant interest in recent years.High-accuracy IMU-tracking can be applied in various applications,such as indoor navigation,gesture recognition,text input,etc.Many efforts have been devoted to improving IMU-based motion tracking in the last two decades,from early calibration techniques on ships or airplanes,to recent arm motion models used on wearable smart devices.In this paper,we present a comprehensive survey on IMU-tracking techniques on mobile and wearable devices.We also reveal the key challenges in IMU-based motion tracking on mobile and wearable devices and possible directions to address these challenges.
基金supported by the National Science Foundation,United States(ECCS-1542015)as part of the National Nanotechnology Coordinated Infrastructure(NNCI).
文摘The aye-aye(Daubentonia madagascariensis)is a nocturnal lemur native to the island of Madagascar with a unique thin middle finger.Its slender third digit has a remarkably specific adaptation,allowing them to perform tap-scanning to locate small cavities beneath tree bark and extract wood-boring larvae from it.As an exceptional active acoustic actuator,this finger makes an aye-aye’s biological system an attractive model for pioneering Nondestructive Evaluation(NDE)methods and robotic systems.Despite the important aspects of the topic in the aye-aye’s unique foraging and its potential contribution to the engineering sensory,little is known about the mechanism and dynamics of this unique finger.This paper used a motion-tracking approach for the aye-aye’s middle finger using simultaneous video graphic capture.To mimic the motion,a two-link robot arm model is designed to reproduce the trajectory.Kinematics formulations were proposed to derive the motion of the middle finger using the Lagrangian method.In addition,a hardware model was developed to simulate the aye-aye’s finger motion.To validate the model,different motion states such as trajectory paths and joint angles,were compared.The simulation results indicate the kinematics of the model were consistent with the actual finger movement.This model is used to understand the aye-aye’s unique tap-scanning process for pioneering new tap-testing NDE strategies for various inspection applications.
文摘The stabilization and trajectory tracking problems of autonomous airship＇s planar motion are studied. By defining novel configuration error and velocity error, the dynamics of error systems are derived. By applying Lyapunov stability method, the state feedback control laws are designed and the close-loop error systems are proved to be uniformly asymptotically stable by Matrosov theorem. In particular, the controller does not need knowledge on system parameters in the case of set-point stabilization, which makes the controller robust with respect to parameter uncertainty. Numerical simulations illustrate the effectiveness of the controller designed.
文摘The development of artificial intelligence technology has promoted the rapid improvement of human-computer interaction. This system uses the Kinect visual image sensor to identify human bone data and complete the recognition of the operator’s movements. Through the filtering process of real-time data by the host computer platform with computer software as the core, the algorithm is programmed to realize the conversion from data to control signals. The system transmits the signal to the lower computer platform with Arduino as the core through the transmission mode of the serial communication, thereby completing the control of the steering gear. In order to verify the feasibility of the theory, the team built a 4-DOF robotic arm control system and completed software development. It can display other functions such as the current bone angle and motion status in real time on the computer operation interface. The experimental data shows that the Kinect-based motion recognition method can effectively complete the tracking of the expected motion and complete the grasping and transfer of the specified objects, which has extremely high operability.
基金Supported by the National Science Foundation of China(61472289)Hubei Province Science Foundation(2015CFB254)
文摘Target tracking is very important in computer vision and related areas. It is usually difficult to accurately track fast motion target with appearance variations. Sometimes the tracking algorithms fail for heavy appearance variations. A multiple template method to track fast motion target with appearance changes is presented under the framework of appearance model with Kalman filter. Firstly, we construct a multiple template appearance model, which includes both the original template and templates affinely transformed from original one. Generally speaking, appearance variations of fast motion target can be covered by affine transformation. Therefore, the affine tr templates match the target of appearance variations better than conventional models. Secondly, we present an improved Kalman filter for approx- imate estimating the motion trail of the target and a modified similarity evaluation function for exact matching. The estimation approach can reduce time complexity of the algorithm and keep accuracy in the meantime. Thirdly, we propose an adaptive scheme for updating template set to alleviate the drift problem. The scheme considers the following differences： the weight differences in two successive frames; different types of affine transformation applied to templates. Finally, experiments demonstrate that the proposed algorithm is robust to appearance varia- tion of fast motion target and achieves real-time performance on middle/low-range computing platform.
基金Supported by the National Natural Science Foundation of China(51005018)
文摘Based on previous achievements,a dynamic pressure-sinkage equation for saturated clay is established.First,aquasi-static penetration rate is selected,and the ratio of the dynamic penetration rate to the quasi-static rate is used to characterize the degree of dynamic effect,then theβth power of the ratio is used to quantify the dynamic effect of sinkage.The dynamic effect exponentβis obtained using penetration tests with different penetration rates.Then,a dynamic motion resistance equation for a tracked vehicle is established based on the dynamic pressure-sinkage equation.The equation incorporates both penetration and bulldozing resistance.Finally,a series of simulation experiments with varying travel speeds and slip rates is carried out.The results show that an increase in the speed leads to stronger terrain stiffness,resulting in a decrease in sinkage and motion resistance.However,the enhancement effect becomes weaker with an increase in the travel speed.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2004AA742209)
文摘To extract the track parameters of a traffic object in traffic video and identify its motion behavior,a new method is proposed based on CamShift(Continuously Adaptive Mean Shift)and HMM(Hidden Markov Model).First,an object entering the video scene is located and tracked by the CamShift based algorithm,then its track parameters are obtained.Next,the track parameters are processed to form the observation sequence of HMM,and the motion behavior modeling and probability evaluation are implemented based on HMM.At last,the behavior identification and behavior statistics of the tracked traffic object in video are achieved.Experiments show that this method can be used to sort and recognize the motion behavior of the traffic object by its corresponding behavior track,and to do some statistics or corresponding process schemes.
文摘To compensate motion errors of images from the parallel-track bistatic synthetic aperture radar（BiSAR）,an improved chirp scaling algorithm（CSA） is proposed.Since velocity vector of the moving aircrafts in the parallel-track BiSAR system can not remain invariant in an aperture,an actual aperture is divided into subapertures so that it is reasonable to assume that the aircrafts move with constant acceleration vector in a subaperture.Based on this model,an improved CSA is derived.The new phase factors incorporate three-dimensional acceleration and velocity.The motion compensation procedure is integrated into the CSA without additional operation required.The simulation results show that the presented algorithm can efficiently resolve motion compensation for parallel-track BiSAR.
