Accurate calibration of surgical instruments and ultrasound probes is essential for achieving high precision in image guided minimally invasive procedures.However,existing methods typically treat the calibration of th...Accurate calibration of surgical instruments and ultrasound probes is essential for achieving high precision in image guided minimally invasive procedures.However,existing methods typically treat the calibration of the needle tip and the ultrasound probe as two independent processes,lacking an integrated calibration mechanism,which often leads to cumulative errors and reduced spatial consistency.To address this challenge,we propose a joint calibration model that unifies the calibration of the surgical needle tip and the ultrasound probe within a single coordinate system.The method formulates the calibration process through a series of mathematical models and coordinate transformation models and employs a gradient descent based optimization to refine the parameters of these models.By establishing and iteratively optimizing a template coordinate system through modeling of constrained spherical motion,the proposed joint calibration model achieves submillimeter accuracy in needle tip localization.Building upon this,an N line based calibration model is developed to determine the spatial relationship between the probe and the ultrasound image plane,resulting in an average pixel deviation of only 1.2373 mm.Experimental results confirm that this unified modeling approach effectively overcomes the limitations of separate calibration schemes,significantly enhancing both precision and robustness,and providing a reliable computational model for surgical navigation systems that require high spatial accuracy without relying on ionizing radiation.展开更多
The significant increase in speed of high-speed train will cause the dynamic contact force of the pantograph-catenary system to fluctuate more severely,which poses a challenge to the study of the pantograph-catenary r...The significant increase in speed of high-speed train will cause the dynamic contact force of the pantograph-catenary system to fluctuate more severely,which poses a challenge to the study of the pantograph-catenary relationship and the design of highspeed pantographs.Good pantograph-catenary coupling quality is the essential condition to ensure safe and efficient operation of high-speed train,stable and reliable current collection,and reduction in the wear of contact wires and pantograph contact strips.Among them,the dynamic parameters of high-speed pantographs are crucial to pantograph-catenary coupling quality.With the reduction of the standard deviation of the pantograph-catenary contact force as the optimization goal,multi-parameter joint optimization designs for the high-speed pantograph with two contact strips at multiple running speeds are proposed.Moreover,combining the sensitivity analysis at the optimal solutions,with the parameters and characteristics of in-service DSA380 highspeed pantograph,the optimization proposal of DSA380 was given.展开更多
Due to the different microstructures caused by the heat source effect,welding joints exhibit significant differences in mechanical properties compared to the base material.Precise characterization of the constitutive ...Due to the different microstructures caused by the heat source effect,welding joints exhibit significant differences in mechanical properties compared to the base material.Precise characterization of the constitutive characteristics of the welded joint requires a large number of repetitive experiments,which are costly,inefficient,and have limited accuracy improvements.This paper proposes an integrated experimental-simulation-based inverse calibration method,which establishes a calibration optimization problem based on the corresponding constitutive model and a finite element calculation model built by the distribution of hardness in the weldment.Using the global tensile force-displacement curve of the MIG-welded 6005A-T6 aluminum alloy specimen and the experimental data of local deformation with time change obtained from DIC(Digital Image Correlation),the parameters involved in the constitutive models are optimized accordingly.This method can directly obtain the constitutive characteristics of the weldment under conditions of limited experiments and insufficient data.Additionally,the adaptability of the constitutive model to the calibration method and the influence of optimization results are discussed and analyzed.The results indicate that the global force-displacement response of the non-saturated Ramberg-Osgood(R-O)model is in the best agreement with that of the experimental data,and the energy error is only 2.62%,followed by the MPL model,while the saturation-based Voce model shows the largest simulation error in terms of the presented object.Furthermore,the simulation results of R-O,Voce,and MPL models in the local area are far superior to traditional fitting methods.展开更多
In this paper,we focus on the problem of joint estimation of DOA,power and polarization angle from sparse reconstruction perspective with array gain-phase errors,where a partly calibrated cocentered orthogonal loop an...In this paper,we focus on the problem of joint estimation of DOA,power and polarization angle from sparse reconstruction perspective with array gain-phase errors,where a partly calibrated cocentered orthogonal loop and dipole(COLD)array is utilized.In detailed implementations,we first combine the output of loop and dipole in second-order statistics domain to receive the source signals completely,and then we use continuous multiplication operator to achieve gain-phase errors calibration.After compensating the gain-phase errors,we construct a log-penalty-based optimization problem to approximate`0 norm and further exploit difference of convex(DC)functions decomposition to achieve DOA.With the aid of the estimated DOAs,the power and polarization angle estimation are obtained by the least squares(LS)method.By conducting numerical simulations,we show the effectiveness and superiorities of the proposed method.展开更多
在相机和旋转模块组成的旋转扫描系统中,相机与转轴的位姿关系对于后续数据融合至关重要。现有方法通常需借助辅助传感器来建立转轴与相机的位姿关系。为降低标定成本,本文提出一种基于ChArUco(Chess Augmented Reality University of C...在相机和旋转模块组成的旋转扫描系统中,相机与转轴的位姿关系对于后续数据融合至关重要。现有方法通常需借助辅助传感器来建立转轴与相机的位姿关系。为降低标定成本,本文提出一种基于ChArUco(Chess Augmented Reality University of Córdoba)标定板的转轴位姿标定方法。利用ChArUco标定板图像解算不同转角下的相机光心坐标并拟合光心轨迹,根据轨迹中心可确定转轴所在位置。建立了旋转系统的数学模型,推导了在世界坐标系下转轴位姿的数学表达式,并基于旋转系统的空间约束构建联合优化,计算相机和转轴间最佳位姿。利用所提出方法进行旋转相机系统标定实验,实验结果表明:标定后的转轴与相机光轴夹角的平均绝对误差为0.036°,标定结果能有效消除全景拼接时的重影现象,验证了所提出方法的准确性和可行性。展开更多
In order to evaluate the mineral identification of the hyperspectral data and make a trade-off of the imaging system parameters,a quantitative evaluation approach based on the multi-parameters joint optimization is pr...In order to evaluate the mineral identification of the hyperspectral data and make a trade-off of the imaging system parameters,a quantitative evaluation approach based on the multi-parameters joint optimization is proposed for the hyperspectral remote sensing.In the proposed approach,the mineral identification is defined as the number of the minerals identified and the key imaging parameters employed include ground sample distance(GSD)and spectral resolution(SR).Certain limitations are found among parameters that are used for analyzing the imaging processes.The constraints include the industrial manufacturing level,application requirements and the quantitative relationship among the GSD,the SR and the signal-to-noise ratio(SNR).Regression analysis is used to investigate the quantitative relationship between the mineral identification and the key imaging system parameters.Then,an optimization model for the trade-off study is established by combining the regression equation with the constraints.The airborne hyperspectral image collected by Hymap is applied to evaluate the performance of the proposed approach.The experimental results reveal that the approach can achieve the evaluation of the mineral identification and the trade-off of key imaging system parameters.The error of the prediction is within one kind of mineral.展开更多
基金Support by Sichuan Science and Technology Program[2023YFSY0026,2023YFH0004].
文摘Accurate calibration of surgical instruments and ultrasound probes is essential for achieving high precision in image guided minimally invasive procedures.However,existing methods typically treat the calibration of the needle tip and the ultrasound probe as two independent processes,lacking an integrated calibration mechanism,which often leads to cumulative errors and reduced spatial consistency.To address this challenge,we propose a joint calibration model that unifies the calibration of the surgical needle tip and the ultrasound probe within a single coordinate system.The method formulates the calibration process through a series of mathematical models and coordinate transformation models and employs a gradient descent based optimization to refine the parameters of these models.By establishing and iteratively optimizing a template coordinate system through modeling of constrained spherical motion,the proposed joint calibration model achieves submillimeter accuracy in needle tip localization.Building upon this,an N line based calibration model is developed to determine the spatial relationship between the probe and the ultrasound image plane,resulting in an average pixel deviation of only 1.2373 mm.Experimental results confirm that this unified modeling approach effectively overcomes the limitations of separate calibration schemes,significantly enhancing both precision and robustness,and providing a reliable computational model for surgical navigation systems that require high spatial accuracy without relying on ionizing radiation.
基金the National Natural Science Foundation of China(Grant No.11672297)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB22020200).
文摘The significant increase in speed of high-speed train will cause the dynamic contact force of the pantograph-catenary system to fluctuate more severely,which poses a challenge to the study of the pantograph-catenary relationship and the design of highspeed pantographs.Good pantograph-catenary coupling quality is the essential condition to ensure safe and efficient operation of high-speed train,stable and reliable current collection,and reduction in the wear of contact wires and pantograph contact strips.Among them,the dynamic parameters of high-speed pantographs are crucial to pantograph-catenary coupling quality.With the reduction of the standard deviation of the pantograph-catenary contact force as the optimization goal,multi-parameter joint optimization designs for the high-speed pantograph with two contact strips at multiple running speeds are proposed.Moreover,combining the sensitivity analysis at the optimal solutions,with the parameters and characteristics of in-service DSA380 highspeed pantograph,the optimization proposal of DSA380 was given.
基金Supported by National Natural Science Foundation of China(Grant Nos.52202431,52172353)Talent Fund of Beijing Jiaotong University of China(Grant No.2024XKRC044).
文摘Due to the different microstructures caused by the heat source effect,welding joints exhibit significant differences in mechanical properties compared to the base material.Precise characterization of the constitutive characteristics of the welded joint requires a large number of repetitive experiments,which are costly,inefficient,and have limited accuracy improvements.This paper proposes an integrated experimental-simulation-based inverse calibration method,which establishes a calibration optimization problem based on the corresponding constitutive model and a finite element calculation model built by the distribution of hardness in the weldment.Using the global tensile force-displacement curve of the MIG-welded 6005A-T6 aluminum alloy specimen and the experimental data of local deformation with time change obtained from DIC(Digital Image Correlation),the parameters involved in the constitutive models are optimized accordingly.This method can directly obtain the constitutive characteristics of the weldment under conditions of limited experiments and insufficient data.Additionally,the adaptability of the constitutive model to the calibration method and the influence of optimization results are discussed and analyzed.The results indicate that the global force-displacement response of the non-saturated Ramberg-Osgood(R-O)model is in the best agreement with that of the experimental data,and the energy error is only 2.62%,followed by the MPL model,while the saturation-based Voce model shows the largest simulation error in terms of the presented object.Furthermore,the simulation results of R-O,Voce,and MPL models in the local area are far superior to traditional fitting methods.
基金the National Natural Science Foundation of China under Grant 61171137.
文摘In this paper,we focus on the problem of joint estimation of DOA,power and polarization angle from sparse reconstruction perspective with array gain-phase errors,where a partly calibrated cocentered orthogonal loop and dipole(COLD)array is utilized.In detailed implementations,we first combine the output of loop and dipole in second-order statistics domain to receive the source signals completely,and then we use continuous multiplication operator to achieve gain-phase errors calibration.After compensating the gain-phase errors,we construct a log-penalty-based optimization problem to approximate`0 norm and further exploit difference of convex(DC)functions decomposition to achieve DOA.With the aid of the estimated DOAs,the power and polarization angle estimation are obtained by the least squares(LS)method.By conducting numerical simulations,we show the effectiveness and superiorities of the proposed method.
文摘在相机和旋转模块组成的旋转扫描系统中,相机与转轴的位姿关系对于后续数据融合至关重要。现有方法通常需借助辅助传感器来建立转轴与相机的位姿关系。为降低标定成本,本文提出一种基于ChArUco(Chess Augmented Reality University of Córdoba)标定板的转轴位姿标定方法。利用ChArUco标定板图像解算不同转角下的相机光心坐标并拟合光心轨迹,根据轨迹中心可确定转轴所在位置。建立了旋转系统的数学模型,推导了在世界坐标系下转轴位姿的数学表达式,并基于旋转系统的空间约束构建联合优化,计算相机和转轴间最佳位姿。利用所提出方法进行旋转相机系统标定实验,实验结果表明:标定后的转轴与相机光轴夹角的平均绝对误差为0.036°,标定结果能有效消除全景拼接时的重影现象,验证了所提出方法的准确性和可行性。
基金supported by the National National Natural Science Foundation of China(Grant Nos.61177008 and 61008047)the China Geological Survey(Grant No.1212011120227)+2 种基金the National High Technology Research and Development Program("863"Program)(Grant Nos.2012AA12A30801 and 2012YQ05250)the Program for Changjiang Scholars and Innovative Research Team(Grant No.IRT0705)the National Public Foundation of China(Grant No.201311036)
文摘In order to evaluate the mineral identification of the hyperspectral data and make a trade-off of the imaging system parameters,a quantitative evaluation approach based on the multi-parameters joint optimization is proposed for the hyperspectral remote sensing.In the proposed approach,the mineral identification is defined as the number of the minerals identified and the key imaging parameters employed include ground sample distance(GSD)and spectral resolution(SR).Certain limitations are found among parameters that are used for analyzing the imaging processes.The constraints include the industrial manufacturing level,application requirements and the quantitative relationship among the GSD,the SR and the signal-to-noise ratio(SNR).Regression analysis is used to investigate the quantitative relationship between the mineral identification and the key imaging system parameters.Then,an optimization model for the trade-off study is established by combining the regression equation with the constraints.The airborne hyperspectral image collected by Hymap is applied to evaluate the performance of the proposed approach.The experimental results reveal that the approach can achieve the evaluation of the mineral identification and the trade-off of key imaging system parameters.The error of the prediction is within one kind of mineral.
