Absolute measurement has consistently been the primary focus in the development of precision linear and angular displace-ment measurements.The scheme design of binary zero position codes is an important factor for abs...Absolute measurement has consistently been the primary focus in the development of precision linear and angular displace-ment measurements.The scheme design of binary zero position codes is an important factor for absolute measurement.Designing and optimizing high-bit zero position codes with over 100 bits face considerable challenges.Simultaneously,the working parameters of zero position codes[unit code width(b),distance(d),and yaw angle(α)]remarkably affect their post-installation performance,particularly in absolute positioning and limit code application in multi-degree-of-freedom measurement schemes.This study addresses these challenges by proposing a design method for zero position codes that considers diffraction based on generative adversarial networks and aims to explore a design with increased efficiency and accuracy as well as optimization for high-bit zero position codes.Additionally,the tolerance range of zero positioning per-formance for each working parameter is examined.By leveraging the adversarial network structure,this study generates the optimization of a 150-bit code and processes the tests of the zero position code by using simulation results.The following working parameter ranges for code design are recommended on the basis of theoretical and experimental results:b greater than 10μm,d andαwithin 1000μm and 3490μrad,and avoidance of intervals with sharp changes in the full width at half maximum.The proposed code design and parameter optimization lay a solid foundation for research and engineering appli-cations in absolute measurement field and have considerable potential for generalization and wide applicability.展开更多
The integration of an inertial navigation system(INS) and a celestial navigation system(CNS) has the superiority of high autonomy. However, its reliability and accuracy are permanently impaired under poor observation ...The integration of an inertial navigation system(INS) and a celestial navigation system(CNS) has the superiority of high autonomy. However, its reliability and accuracy are permanently impaired under poor observation conditions. To address this issue, the present paper proposes a tightly coupled INS/CNS/spectral redshift(SRS) integration framework based on the spectral redshift error measurement. In the proposed method, a spectral redshift error measurement equation is investigated and embedded in the traditional tightly coupled INS/CNS integrated navigation system to achieve better anti-interference under complicated circumstances. Subsequently, the inaccurate redshift estimation from the low signal-to-noise ratio spectrum is considered in the integrated system, and an improved chi-square test-based covariance estimation method is incorporated in the federated Kalman filter, allowing to deal with measurement outliers caused by the inaccurate redshift estimation but not influencing the effect of other correct redshift measurements in suppressing the error of the navigation parameter on the filtering solution. Simulations and comprehensive analyses demonstrate that the proposed tightly coupled INS/CNS/SRS integrated navigation system can effectively handle outliers and outages under hostile observation conditions, resulting in improved performance.展开更多
Purpose–The purpose of this paper is to demonstrate the effectiveness and advantages of using perceptual tolerance neighbourhoods in tolerance space-based image similarity measures and its application in content-base...Purpose–The purpose of this paper is to demonstrate the effectiveness and advantages of using perceptual tolerance neighbourhoods in tolerance space-based image similarity measures and its application in content-based image classification and retrieval.Design/methodology/approach–The proposed method in this paper is based on a set-theoretic approach,where an image is viewed as a set of local visual elements.The method also includes a tolerance relation that detects the similarity between pairs of elements,if the difference between corresponding feature vectors is less than a threshold 2(0,1).Findings–It is shown that tolerance space-based methods can be successfully used in a complete content-based image retrieval(CBIR)system.Also,it is shown that perceptual tolerance neighbourhoods can replace tolerance classes in CBIR,resulting in more accuracy and less computations.Originality/value–The main contribution of this paper is the introduction of perceptual tolerance neighbourhoods instead of tolerance classes in a new form of the Henry-Peters tolerance-based nearness measure(tNM)and a new neighbourhood-based tolerance-covering nearness measure(tcNM).Moreover,this paper presents a side–by–side comparison of the tolerance space based methods with other published methods on a test dataset of images.展开更多
基金supported by the National Natural Science Foundation of China with No.62275142the Basic and Applied Basic Research Foundation of Guangdong Province with No.2021B1515120007.
文摘Absolute measurement has consistently been the primary focus in the development of precision linear and angular displace-ment measurements.The scheme design of binary zero position codes is an important factor for absolute measurement.Designing and optimizing high-bit zero position codes with over 100 bits face considerable challenges.Simultaneously,the working parameters of zero position codes[unit code width(b),distance(d),and yaw angle(α)]remarkably affect their post-installation performance,particularly in absolute positioning and limit code application in multi-degree-of-freedom measurement schemes.This study addresses these challenges by proposing a design method for zero position codes that considers diffraction based on generative adversarial networks and aims to explore a design with increased efficiency and accuracy as well as optimization for high-bit zero position codes.Additionally,the tolerance range of zero positioning per-formance for each working parameter is examined.By leveraging the adversarial network structure,this study generates the optimization of a 150-bit code and processes the tests of the zero position code by using simulation results.The following working parameter ranges for code design are recommended on the basis of theoretical and experimental results:b greater than 10μm,d andαwithin 1000μm and 3490μrad,and avoidance of intervals with sharp changes in the full width at half maximum.The proposed code design and parameter optimization lay a solid foundation for research and engineering appli-cations in absolute measurement field and have considerable potential for generalization and wide applicability.
基金supported by the National Natural Science Foundation of China(Grant Nos.42004021&41904028)the Shenzhen Science and Technology Program(Grant No.JCYJ20210324121602008)the Shaanxi Natural Science Basic Research Project,China(Grant No.2022-JM313)。
文摘The integration of an inertial navigation system(INS) and a celestial navigation system(CNS) has the superiority of high autonomy. However, its reliability and accuracy are permanently impaired under poor observation conditions. To address this issue, the present paper proposes a tightly coupled INS/CNS/spectral redshift(SRS) integration framework based on the spectral redshift error measurement. In the proposed method, a spectral redshift error measurement equation is investigated and embedded in the traditional tightly coupled INS/CNS integrated navigation system to achieve better anti-interference under complicated circumstances. Subsequently, the inaccurate redshift estimation from the low signal-to-noise ratio spectrum is considered in the integrated system, and an improved chi-square test-based covariance estimation method is incorporated in the federated Kalman filter, allowing to deal with measurement outliers caused by the inaccurate redshift estimation but not influencing the effect of other correct redshift measurements in suppressing the error of the navigation parameter on the filtering solution. Simulations and comprehensive analyses demonstrate that the proposed tightly coupled INS/CNS/SRS integrated navigation system can effectively handle outliers and outages under hostile observation conditions, resulting in improved performance.
基金supported by the Natural Sciences and Engineering Research Council of Canada grant 185986.
文摘Purpose–The purpose of this paper is to demonstrate the effectiveness and advantages of using perceptual tolerance neighbourhoods in tolerance space-based image similarity measures and its application in content-based image classification and retrieval.Design/methodology/approach–The proposed method in this paper is based on a set-theoretic approach,where an image is viewed as a set of local visual elements.The method also includes a tolerance relation that detects the similarity between pairs of elements,if the difference between corresponding feature vectors is less than a threshold 2(0,1).Findings–It is shown that tolerance space-based methods can be successfully used in a complete content-based image retrieval(CBIR)system.Also,it is shown that perceptual tolerance neighbourhoods can replace tolerance classes in CBIR,resulting in more accuracy and less computations.Originality/value–The main contribution of this paper is the introduction of perceptual tolerance neighbourhoods instead of tolerance classes in a new form of the Henry-Peters tolerance-based nearness measure(tNM)and a new neighbourhood-based tolerance-covering nearness measure(tcNM).Moreover,this paper presents a side–by–side comparison of the tolerance space based methods with other published methods on a test dataset of images.
