Scale Invariant Feature Transform (SIFT) has been proven to perform better on the distinctiveness and robustness than other features. But it cannot satisfy the needs of low contrast images matching and the matching results are sensitive to 3D viewpoint change of camera. In order to improve the performance of SIFT to low contrast images and images with large 3D viewpoint change, a new matching method based on improved SIFT is proposed. First, an adaptive contrast threshold is computed for each initial key point in low contrast image region, which uses pixels in its 9×9 local neighborhood, and then using it to eliminate initial key points in low contrast image region. Second, a new SIFT descriptor with 48 dimensions is computed for each key point. Third, a hierarchical matching method based on epipolar line and differences of key points’ dominate orientation is presented. The experimental results prove that the method can greatly enhance the performance of SIFT to low contrast image matching. Besides, when applying it to stereo images matching with the hierarchical matching method, the correct matches and matching efficiency are greatly enhanced.
{"title":"Improved SIFT descriptor applied to stereo image matching","authors":"Luan Zeng, You Zhai, W. Xiong","doi":"10.1117/12.2180667","DOIUrl":"https://doi.org/10.1117/12.2180667","url":null,"abstract":"Scale Invariant Feature Transform (SIFT) has been proven to perform better on the distinctiveness and robustness than other features. But it cannot satisfy the needs of low contrast images matching and the matching results are sensitive to 3D viewpoint change of camera. In order to improve the performance of SIFT to low contrast images and images with large 3D viewpoint change, a new matching method based on improved SIFT is proposed. First, an adaptive contrast threshold is computed for each initial key point in low contrast image region, which uses pixels in its 9×9 local neighborhood, and then using it to eliminate initial key points in low contrast image region. Second, a new SIFT descriptor with 48 dimensions is computed for each key point. Third, a hierarchical matching method based on epipolar line and differences of key points’ dominate orientation is presented. The experimental results prove that the method can greatly enhance the performance of SIFT to low contrast image matching. Besides, when applying it to stereo images matching with the hierarchical matching method, the correct matches and matching efficiency are greatly enhanced.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120976715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper studied the effect of curvature on the charge sensitivity of a curved PVDF sensor. The sensor was fabricated by attaching a PVDF film along the X-axis on a group of cylindrical silicon rods to form an outline with several bumps. The open output voltage of a curved sensor was simulated by using ANSYS with a rod curvature of 333 m-1, 400 m-1 and 500 m-1. It was found that the sensitivity was the highest when the curvature was 500 m-1, and the lowest when the curvature was 333 m-1. Curved PVDF sensors were fabricated and tested with a PVDF patch of 30 mm long and 28 μm thick and a radius of silicon rod of 3 mm, 2.5 mm and 2 mm, respectively. A shaker and mass block were used to apply the same dynamic force to the curved sensors and an oscilloscope was used to observe the output charge. The experiment results are not ideal but do show the same tendency as the simulation. The charge sensitivity increased as the curvature of substrate increased.
{"title":"Research on the relationship between the curvature and the sensitivity of curved PVDF sensor","authors":"Lu Shi, Yue Zhang, Weijie Dong","doi":"10.1117/12.2180862","DOIUrl":"https://doi.org/10.1117/12.2180862","url":null,"abstract":"This paper studied the effect of curvature on the charge sensitivity of a curved PVDF sensor. The sensor was fabricated by attaching a PVDF film along the X-axis on a group of cylindrical silicon rods to form an outline with several bumps. The open output voltage of a curved sensor was simulated by using ANSYS with a rod curvature of 333 m-1, 400 m-1 and 500 m-1. It was found that the sensitivity was the highest when the curvature was 500 m-1, and the lowest when the curvature was 333 m-1. Curved PVDF sensors were fabricated and tested with a PVDF patch of 30 mm long and 28 μm thick and a radius of silicon rod of 3 mm, 2.5 mm and 2 mm, respectively. A shaker and mass block were used to apply the same dynamic force to the curved sensors and an oscilloscope was used to observe the output charge. The experiment results are not ideal but do show the same tendency as the simulation. The charge sensitivity increased as the curvature of substrate increased.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116685083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new method based on quadratic programming theory is proposed to determine the regularization parameter. A function whose variable is the derivative with respect to the regularization parameter is formulated. Based on the property that the value of the function is very dependent on the regularization parameter, the optimal parameters can be determined by using quadratic programming theory. A numerical example is utilized to select the parameters through the method. It is concluded that the new method can effectively overcome the ill-posed problems from an ill-conditioned system matrix, and that it can obtain an approximate solution with higher accuracy, fine stability and effective noise resistance.
{"title":"A new method for determining the Tikhonov regularization parameter of load identification","authors":"Wei Gao, Kaiping Yu","doi":"10.1117/12.2180739","DOIUrl":"https://doi.org/10.1117/12.2180739","url":null,"abstract":"A new method based on quadratic programming theory is proposed to determine the regularization parameter. A function whose variable is the derivative with respect to the regularization parameter is formulated. Based on the property that the value of the function is very dependent on the regularization parameter, the optimal parameters can be determined by using quadratic programming theory. A numerical example is utilized to select the parameters through the method. It is concluded that the new method can effectively overcome the ill-posed problems from an ill-conditioned system matrix, and that it can obtain an approximate solution with higher accuracy, fine stability and effective noise resistance.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122897068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qian Li, Xiaojun Liu, Zili Lei, Yi Zheng, Liangzhou Chen, Wenlong Lu
Piezoelectric ceramics with a flexible hinge guide was used for fine positioning at nanometer level, while a stepping motor was used for coarse positioning with a resolution at micrometer level, and their combination helped fulfillment of vertical scanning positioning with large range and nanometer resolution. A grating sensor was used for the real-time measurement of scanning displacement for close-loop positioning control. The properties of the flexible hinge guide was analyzed using ANSYS. Experimental results indicated the performance of the system was good. The system had a good application prospect in an optical profiler for surface measurement.
{"title":"A vertical scanning positioning system with large range and nanometer resolution for optical profiler","authors":"Qian Li, Xiaojun Liu, Zili Lei, Yi Zheng, Liangzhou Chen, Wenlong Lu","doi":"10.1117/12.2181351","DOIUrl":"https://doi.org/10.1117/12.2181351","url":null,"abstract":"Piezoelectric ceramics with a flexible hinge guide was used for fine positioning at nanometer level, while a stepping motor was used for coarse positioning with a resolution at micrometer level, and their combination helped fulfillment of vertical scanning positioning with large range and nanometer resolution. A grating sensor was used for the real-time measurement of scanning displacement for close-loop positioning control. The properties of the flexible hinge guide was analyzed using ANSYS. Experimental results indicated the performance of the system was good. The system had a good application prospect in an optical profiler for surface measurement.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123776868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic testing of structures and components is an important area of research. Extensive researches on the methods of using sensors for vibration parameters have been studied for years. With the rapid development of industrial high-speed camera and computer hardware, the method of using stereo vision for dynamic testing has been the focus of the research since the advantages of non-contact, full-field, high resolution and high accuracy. But in the country there is not much research about the dynamic testing based on stereo vision, and yet few people publish articles about the three-dimensional (3D) reconstruction of feature points in the case of dynamic. It is essential to the following analysis whether it can obtain accurate movement of target objects. In this paper, an object with sinusoidal motion is detected by stereo vision and the accuracy with different feature detection algorithms is investigated. Three different marks including dot, square and circle are stuck on the object and the object is doing sinusoidal motion by vibration table. Then use feature detection algorithm speed-up robust feature (SURF) to detect point, detect square corners by Harris and position the center by Hough transform. After obtaining the pixel coordinate values of the feature point, the stereo calibration parameters are used to achieve three-dimensional reconstruction through triangulation principle. The trajectories of the specific direction according to the vibration frequency and the frequency camera acquisition are obtained. At last, the reconstruction accuracy of different feature detection algorithms is compared.
{"title":"3D reconstruction for sinusoidal motion based on different feature detection algorithms","authors":"Peng Zhang, Jin Zhang, Huaxia Deng, Liandong Yu","doi":"10.1117/12.2181388","DOIUrl":"https://doi.org/10.1117/12.2181388","url":null,"abstract":"The dynamic testing of structures and components is an important area of research. Extensive researches on the methods of using sensors for vibration parameters have been studied for years. With the rapid development of industrial high-speed camera and computer hardware, the method of using stereo vision for dynamic testing has been the focus of the research since the advantages of non-contact, full-field, high resolution and high accuracy. But in the country there is not much research about the dynamic testing based on stereo vision, and yet few people publish articles about the three-dimensional (3D) reconstruction of feature points in the case of dynamic. It is essential to the following analysis whether it can obtain accurate movement of target objects. In this paper, an object with sinusoidal motion is detected by stereo vision and the accuracy with different feature detection algorithms is investigated. Three different marks including dot, square and circle are stuck on the object and the object is doing sinusoidal motion by vibration table. Then use feature detection algorithm speed-up robust feature (SURF) to detect point, detect square corners by Harris and position the center by Hough transform. After obtaining the pixel coordinate values of the feature point, the stereo calibration parameters are used to achieve three-dimensional reconstruction through triangulation principle. The trajectories of the specific direction according to the vibration frequency and the frequency camera acquisition are obtained. At last, the reconstruction accuracy of different feature detection algorithms is compared.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126349132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A ranging algorithm based on process measurement was proposed for low-altitude radio fuzes with wide range of action and low request of absolute ranging precision. For those particular applications, a conception of relative burst height was given to control the initiation point of a fuze instead of the absolute burst height. The received echo power was analyzed and its relationship with the relative burst height was derived. The basic principle and implementation of the ranging algorithm were discussed and the simulation results were given including anti-white Gaussian noise performance and anti-active jamming performance. The results proved the feasibility of the ranging algorithm based on process measurement. It could be used to help the further researches of low altitude radio fuzes.
{"title":"Ranging algorithm based on process measurement for low-altitude radio fuzes","authors":"Xiaolu Chen, Tao Xu, Biao Chen, Ronghua Tao","doi":"10.1117/12.2181245","DOIUrl":"https://doi.org/10.1117/12.2181245","url":null,"abstract":"A ranging algorithm based on process measurement was proposed for low-altitude radio fuzes with wide range of action and low request of absolute ranging precision. For those particular applications, a conception of relative burst height was given to control the initiation point of a fuze instead of the absolute burst height. The received echo power was analyzed and its relationship with the relative burst height was derived. The basic principle and implementation of the ranging algorithm were discussed and the simulation results were given including anti-white Gaussian noise performance and anti-active jamming performance. The results proved the feasibility of the ranging algorithm based on process measurement. It could be used to help the further researches of low altitude radio fuzes.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131260013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The flow rate is calculated via ultrasonic flow meter (UFM), which is through measuring the difference of time transmitting flow between flow direction and reverse direction. This paper describes the uncertainty analysis for the method of time difference which is commonly used in ultrasonic flow measurement, and the analysis of error source of uncertainty components as well as the general method of elimination. Based on the technique of pseudo random sequence, this paper presents a precise time difference method based on digital correlation technology, and its principle, realization way and uncertainty evaluation are introduced. On the DSP and FPGA system platform, an ultrasonic flow meter scheme based on the digital correlation technology is suggested.
{"title":"Investigating of precision measurement on ultrasonic flow","authors":"F. Jiang, Q. Ji, D. Zhai, Yibo Dong, Chun Dong","doi":"10.1117/12.2181965","DOIUrl":"https://doi.org/10.1117/12.2181965","url":null,"abstract":"The flow rate is calculated via ultrasonic flow meter (UFM), which is through measuring the difference of time transmitting flow between flow direction and reverse direction. This paper describes the uncertainty analysis for the method of time difference which is commonly used in ultrasonic flow measurement, and the analysis of error source of uncertainty components as well as the general method of elimination. Based on the technique of pseudo random sequence, this paper presents a precise time difference method based on digital correlation technology, and its principle, realization way and uncertainty evaluation are introduced. On the DSP and FPGA system platform, an ultrasonic flow meter scheme based on the digital correlation technology is suggested.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"7 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132927291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jingzhi Huang, T. Sun, Wei Gu, Zhong Wen, Tenghui Guo
With the fast development of the advanced equipment manufacturing toward precision and ultra-precision trend, especially with the continuously improving of the aviation engine’s performance, the problem of high displacement resolution for the large-load two-dimension adjusting and positioning worktable used for the aeroengine assembling become evident. A method was proposed which is based on the invariable restoring force, and the adjusting and positioning physical model was established. The experiment results indicate that under the occasion of a load with 508 kilogram, the worktable has got a displacement resolution of 0.3μm after using the improved method compared to 1.4μm of the traditional method. The improved method could meet the requirements of aviation engine assembling worktable.
{"title":"Adjusting and positioning method with high displacement resolution for large-load worktable based on the invariable restoring force","authors":"Jingzhi Huang, T. Sun, Wei Gu, Zhong Wen, Tenghui Guo","doi":"10.1117/12.2181818","DOIUrl":"https://doi.org/10.1117/12.2181818","url":null,"abstract":"With the fast development of the advanced equipment manufacturing toward precision and ultra-precision trend, especially with the continuously improving of the aviation engine’s performance, the problem of high displacement resolution for the large-load two-dimension adjusting and positioning worktable used for the aeroengine assembling become evident. A method was proposed which is based on the invariable restoring force, and the adjusting and positioning physical model was established. The experiment results indicate that under the occasion of a load with 508 kilogram, the worktable has got a displacement resolution of 0.3μm after using the improved method compared to 1.4μm of the traditional method. The improved method could meet the requirements of aviation engine assembling worktable.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"9446 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130486721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Energy harvesting systems are interesting for use in remote power supplies. Many such systems utilize the motion or deformation associated with vibration, converting the mechanical energy to electrical energy, and supplying power to other electronic devices. In terms of energy harvesting from mechanical vibrations, piezoelectric conversion has received much attention as it can directly convert applied strain energy into useable electric energy and easily be integrated into a microsystem. The removal of mechanical energy from a vibrating structure necessarily leads to a damping effect. This paper addresses the damping associated with a piezoelectric energy harvesting system which is called the adaptive synchronized switching harvesting (ASSH) technique. Furthermore, a self-powered circuit which implements the technique (ASSH) is proposed, which validates that the new technique can be truly self-powered. Experimental results show that the vibration amplitudes of the first two modes are reduced by about 9.27 dB and 0.96 dB in the case of the exciting signal of same amplitude ratio (3:3), respectively. Compared with other self-powered vibration damping technique, this technique not only shows its robustness, but also harvests the energy and supply power to other electronic circuits.
{"title":"Multimode vibration damping as a result of piezoelectric energy harvesting","authors":"Hui Shen, Fengsheng Zhang, J. Qiu, Yixiang Bian","doi":"10.1117/12.2181515","DOIUrl":"https://doi.org/10.1117/12.2181515","url":null,"abstract":"Energy harvesting systems are interesting for use in remote power supplies. Many such systems utilize the motion or deformation associated with vibration, converting the mechanical energy to electrical energy, and supplying power to other electronic devices. In terms of energy harvesting from mechanical vibrations, piezoelectric conversion has received much attention as it can directly convert applied strain energy into useable electric energy and easily be integrated into a microsystem. The removal of mechanical energy from a vibrating structure necessarily leads to a damping effect. This paper addresses the damping associated with a piezoelectric energy harvesting system which is called the adaptive synchronized switching harvesting (ASSH) technique. Furthermore, a self-powered circuit which implements the technique (ASSH) is proposed, which validates that the new technique can be truly self-powered. Experimental results show that the vibration amplitudes of the first two modes are reduced by about 9.27 dB and 0.96 dB in the case of the exciting signal of same amplitude ratio (3:3), respectively. Compared with other self-powered vibration damping technique, this technique not only shows its robustness, but also harvests the energy and supply power to other electronic circuits.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115238433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The failure of rectangular clutch spring of automatic slack adjuster directly affects the work of automatic slack adjuster. We establish the structural mechanics model of automatic slack adjuster rectangular clutch spring based on its working principle and mechanical structure. In addition, we upload such structural mechanics model to ANSYS Workbench FEA system to predict the fatigue life of rectangular clutch spring. FEA results show that the fatigue life of rectangular clutch spring is 2.0403×105 cycle under the effect of braking loads. In the meantime, fatigue tests of 20 automatic slack adjusters are carried out on the fatigue test bench to verify the conclusion of the structural mechanics model. The experimental results show that the mean fatigue life of rectangular clutch spring is 1.9101×105, which meets the results based on the finite element analysis using ANSYS Workbench FEA system.
{"title":"Finite element fatigue analysis of rectangular clutch spring of automatic slack adjuster","authors":"Chengxin Xu, Zai Luo, Xiao-feng Hu, Wensong Jiang","doi":"10.1117/12.2180757","DOIUrl":"https://doi.org/10.1117/12.2180757","url":null,"abstract":"The failure of rectangular clutch spring of automatic slack adjuster directly affects the work of automatic slack adjuster. We establish the structural mechanics model of automatic slack adjuster rectangular clutch spring based on its working principle and mechanical structure. In addition, we upload such structural mechanics model to ANSYS Workbench FEA system to predict the fatigue life of rectangular clutch spring. FEA results show that the fatigue life of rectangular clutch spring is 2.0403×105 cycle under the effect of braking loads. In the meantime, fatigue tests of 20 automatic slack adjusters are carried out on the fatigue test bench to verify the conclusion of the structural mechanics model. The experimental results show that the mean fatigue life of rectangular clutch spring is 1.9101×105, which meets the results based on the finite element analysis using ANSYS Workbench FEA system.","PeriodicalId":380636,"journal":{"name":"Precision Engineering Measurements and Instrumentation","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115777031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：