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Conference on Image Processing - Machine Vision Applications VI

作者： Deng, Fuqin Li, Zhao Chen, Jia Deng, Jiangwen Fung, Kenneth S. M. Lam, Edmund Y. Univ Hong Kong Dept Elect & Elect Engn Imaging Syst Lab Hong Kong Hong Kong Peoples R China

ISBN: (纸本)9780819494344

A high throughput is often required in many machine vision systems, especially on the assembly line in the semiconductor industry. To develop a non-contact three-dimensional dense surface reconstruction system for real-time surface inspection and metrology applications, in this work, we project sinusoidal patterns onto the inspected objects and propose a high speed phase-shift algorithm. First, we use an illumination-reflectivity-focus (IRF) model to investigate the factors in image formation for phase-measuring profilometry. Second, by visualizing and analyzing the characteristic intensity locus projected onto the intensity space, we build a two-dimensional phase map to store the phase information for each point in the intensity space. Third, we develop an efficient elliptic phase-shift algorithm (E-PSA) for high speed surface profilometry. In this method, instead of calculating the time-consuming inverse trigonometric function, we only need to normalize the measured image intensities and then index the built two-dimensional phase map during real-time phase reconstruction. Finally, experimental results show that it is about two times faster than conventional phase-shift algorithm.

关键词： Three-dimensional image acquisition phase-shift algorithm industrial inspection surface measurements profilometry

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Complementary Fourier Single-Pixel Imaging

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SENSORS 2021年第19期21卷 6544页

作者： Zhou, Dong Cao, Jie Cui, Huan Hao, Qun Chen, Bing-kun Lin, Kai Beijing Inst Technol Key Lab Biomimet Robots & Syst Sch Opt & Photon Beijing 100081 Peoples R China Beijing Fisheries Res Inst Beijing 100068 Peoples R China

Single-pixel imaging, with the advantages of a wide spectrum, beyond-visual-field imaging, and robustness to light scattering, has attracted increasing attention in recent years. Fourier single-pixel imaging (FSI) can reconstruct sharp images under sub-Nyquist sampling. However, the conventional FSI has difficulty balancing imaging quality and efficiency. To overcome this issue, we proposed a novel approach called complementary Fourier single-pixel imaging (CFSI) to reduce the number of measurements while retaining its robustness. The complementary nature of Fourier patterns based on a four-step phase-shift algorithm is combined with the complementary nature of a digital micromirror device. CFSI only requires two phase-shifted patterns to obtain one Fourier spectral value. Four light intensity values are obtained by loading the two patterns, and the spectral value is calculated through differential measurement, which has good robustness to noise. The proposed method is verified by simulations and experiments compared with FSI based on two-, three-, and four-step phase shift algorithms. CFSI performed better than the other methods under the condition that the best imaging quality of CFSI is not reached. The reported technique provides an alternative approach to realize real-time and high-quality imaging.

关键词： single-pixel imaging Fourier patterns complementary nature phase-shift algorithm

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Novel Modulation of Isolated Bidirectional DC-DC Converter for Energy Storage Systems

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IEEE TRANSACTIONS ON POWER ELECTRONICS 2019年第2期34卷 1266-1275页

作者： Nguyen Anh Dung Chiu, Huang-Jen Lin, Jing-Yuan Hsieh, Yao-Ching Chen, Hui-Ting Zeng, Bo-Xiang Natl Taiwan Univ Sci & Technol Dept Elect & Comp Engn Taipei 10607 Taiwan Natl Sun Yat Sen Univ Dept Elect Engn Kaohsiung 80424 Taiwan

In this study, a novel modulation of an isolated three-phase bidirectional dc-dc converter is proposed for the high-voltage input power supply to low-voltage output energy storage systems. The wye-delta connection of the transformers is employed to reduce the voltage stress at the high side and the current stress at the low side of the transformers. Frequency control allows the output voltage regulation, and a phase-shift algorithm with a resonant tank is proposed following with the switching frequency to reduce the frequency range with the specific power. Furthermore, the zero-voltage-switching condition for all MOSFETs in the entire power range, which is the major restriction of a single-phase converter, is also discussed in this paper. The three-phase wye-delta converter significantly reduces the ripple of inductor current compared with that of a single-phase converter. A 2 kW prototype converter was built and successfully tested to verify the capability of such control modulation.

关键词： Bidirectional converter frequency modulation phase-shift algorithm three-phase wye-delta converter

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phase-shifting of correlation fringes created by image processing as an alternative to improve digital shearography

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OPTICS COMMUNICATIONS 2016年 380卷 114-123页

作者： Braga, Roberto A., Jr. Gonzalez-Pena, Rolando J. Marcon, Marlon Magalhaes, Ricardo R. Paiva-Almeida, Thiago Santos, Igor V. A. Martins, Moises Univ Fed Lavras Dept Engn BR-3037 Lavras MG Brazil Univ Valencia Unidad Biofis & Fis Med Dept Fisiol Fac Med & Odontol Valencia 46010 Spain Inst Fed Minas Gerais Dept Engn & Comp Campus Bambui IFMG Bambui MG Brazil

The adoption of digital speckle pattern shearing interferometry, or speckle shearography, is well known in many areas when one needs to measure micro-displacements in-plane and out of the plane in biological and non-biological objects;it is based on the Michelson's Interferometer with the use of a piezoelectric transducer (PZT) in order to provide the phase-shift of the fringes and then to improve the quality of the final image. The creation of the shifting images using a PZT, despite its widespread use, has some drawbacks or limitations, such as the cost of the apparatus, the difficulties in applying the same displacement in the mirror repeated times, and when the phase-shift cannot be used in dynamic object measurement. The aim of this work was to create digitally phase-shift images avoiding the mechanical adjustments of the PZT, testing them with the digital shearography method. The methodology was tested using a well-known object, a cantilever beam of aluminium under deformation. The results documented the ability to create the deformation map and curves with reliability and sensitivity, reducing the cost, and improving the robustness and also the accessibility of digital speckle pattern shearing interferometry. (C) 2016 Elsevier B.V. All rights reserved.

关键词： phase-shift algorithm Speckle interferometry Piezoelectric transducer Digital speckle pattern shearing interferometry

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Pseudo-Four-phase-shift algorithm for Performance Enhancement of 3D-TOF Vision Systems

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2010年第5期59卷 1175-1181页

作者： Hussmann, Stephan Edeler, Torsten Westcoast Univ Appl Sci Dept Elect Engn & Informat Technol D-25746 Heide Germany

Time-of-flight (TOF) sensors have recently become available at reasonable prices. In comparison with stereo vision systems and laser range scanners, they combine the advantages of active sensors, providing accurate distance measurements, and camera-based systems, recording a 2-D matrix at a high frame rate. Moreover, low-cost 3-D imaging has the potential to open a wide field of additional applications and solutions in markets such as consumer electronics, multimedia, digital photography, robotics, and medical technologies. This paper focuses on the currently implemented phase-shift algorithm in this type of sensors. This paper presents a new approach that doubles the frame rate and thereby enhances the performance of photonic mixer device (PMD) TOF sensors. In the experimental section, detailed measurements are presented, and the advantages and disadvantages of the proposed algorithm in comparison with the state-of-the-art algorithm are discussed.

关键词： Optical distance measurement phase measurement phase-shift algorithm photonic mixer devices (PMDs) time-of-flight (TOF)

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Investigation of different polar to Cartesian coordinate system conversion methods for ToF-cameras in the close-up range

Investigation of different polar to Cartesian coordinate sys...

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32nd Annual IEEE International Instrumentation and Measurement Technology Conference (I2MTC)

作者： Hussmann, Stephan Holtorf, Tim Knoll, Florian West Coast Univ Appl Sci Fac Engn Heide Germany

ISBN: (纸本)9781479961139

In machine vision applications, Time-of-Flight (TOF) sensors like the Photonic Mixer Devices (PMD) became considerable alternatives to common 3D sensing devices. Because of the enormous progress in TOF-vision systems, nowadays 3D matrix cameras can be used for many applications such as robotic, automotive, industrial, medical and multimedia applications. This paper focuses on the range data resolution for machine vision applications in the close-up range. For many applications the 3D information of objects are required in Cartesian coordinates. However TOF cameras normally deliver polar coordinates. In this paper different polar to Cartesian coordinate system conversion methods and their influence of the range resolution in the close-up range of TOF cameras are investigated.

关键词： phase measurement phase-shift algorithm photonic mixer devices (PMD) time-of-flight (TOF) optical distance measurement component high resolution

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Single frame correction of motion artifacts in PMD-based time of flight cameras

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IMAGE AND VISION COMPUTING 2014年第12期32卷 1127-1143页

作者： Jimenez, David Pizarro, Daniel Mazo, Manuel Univ Alcala Geintra Res Grp Madrid 28871 Spain Univ Auvergne ALCoV ISIT F-63001 Clermont Ferrand France

One of the leading time of flight imaging technologies for depth sensing is based on Photonic Mixer Devices (PMD). In PMD sensors each pixel samples the correlation between emitted and received light signals. Current PMD cameras compute eight correlation samples per pixel in four sequential stages to obtain depth with invariance to signal amplitude and offset variations. With motion, PMD pixels capture different depths at each stage. As a result, correlation samples are not coherent with a single depth, producing artifacts. We propose to detect and remove motion artifacts from a single frame taken by a PMD camera. The algorithm we propose is very fast, simple and can be easily included in camera hardware. We recover depth of each pixel by exploiting consistency of the correlation samples and local neighbors of the pixel. In addition, our method obtains the motion flow of occluding contours in the image from a single frame. The system has been validated in real scenes using a commercial low-cost PMD camera and high speed dynamics. In all cases our method produces accurate results and it highly reduces motion artifacts. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Time of flight (ToF) Motion artifacts (MoArt) Photonic mixer devices (PMD) Motion flow phase-shift algorithm

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Real-time classification of industrial products based on the photonic-mixer-device sensor technology

Real-time classification of industrial products based on the...

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9th IEEE Sensors Applications Symposium (SAS)

作者： Hussmann, Stephan Sandner, Joern West Coast Univ Appl Sci Fac Engn Heide Germany

ISBN: (纸本)9781479921805

During the last years, Time-of-Flight sensors achieved a significant impact onto research fields in machine vision. In comparison to stereo vision system and laser range scanners they combine the advantages of active sensors providing accurate distance measurements and camera-based systems recording a 2D matrix at a high frame rate. Moreover low cost 3D imaging has the potential to open a wide field of additional applications and solutions in markets like consumer electronics, multimedia, digital photography, robotics and medical technologies. This paper focuses on the classification task of typical industrial products in the close-up range. A new approach due to the use of the photonic-mixer-device (PMD) sensor technology is presented which achieves a much simpler real-time classification. Experimental results show that the proposed approach is well suited for machine vision applications.

关键词： phase measurement phase-shift algorithm photonic mixer devices (PMD) time-of-flight (TOF) optical distance measurement component k-nearest neighbour classification

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Investigation of different polar to Cartesian coordinate system conversion methods for ToF-cameras in the close-up range

Investigation of different polar to Cartesian coordinate sys...

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IEEE International Instrumentation and Measurement Technology Conference

作者： Stephan Hussmann Tim Holtorf Florian Knoll Faculty of Engineering West Coast University of Applied Sciences Heide Germany

ISBN: (纸本)9781479961153

关键词： phase measurement phase-shift algorithm photonic mixer devices (PMD) time-of-flight (TOF) optical distance measurement component high resolution

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Performance improvement of a 3D-TOF PMD camera using a pseudo 4-phase shift algorithm

Performance improvement of a 3D-TOF PMD camera using a pseud...

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26th IEEE International Instrumentation and Measurement Technology Conference

作者： Hussmann, Stephan Edeler, Torsten Westcoast Univ Appl Sci Dept Elect Engn & Informat Technol D-25746 Heide Germany

ISBN: (纸本)9781424433520

Time-of-Flight sensors have recently become available at reasonable prices. In comparison to stereo vision system and laser range scanners they combine the advantages of active sensors providing accurate distance measurements and camera-based systems recording a 2D matrix at a high frame rate. Moreover low cost 3D imaging has the potential to open a wide field of additional applications and solutions in markets like consumer electronics, multimedia, digital photography, robotics and medical technologies. This paper focuses on the currently implemented phase-shift algorithm in this type of sensors. This paper presents a new approach which doubles the frame rate and thereby increases the performance of PMD TOF sensors. Experimental results show that the proposed algorithm is working effectively.

关键词： phase measurement phase-shift algorithm photonic mixer devices (PMD) time-of-flight (TOF)

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