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Vision-based remote 6-DOF structural displacement monitoring system using a unique marker
Jeon, Haemin,Kim, Youngjae,Lee, Donghwa,Myung, Hyun Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.6
Structural displacement is an important indicator for assessing structural safety. For structural displacement monitoring, vision-based displacement measurement systems have been widely developed; however, most systems estimate only 1 or 2-DOF translational displacement. To monitor the 6-DOF structural displacement with high accuracy, a vision-based displacement measurement system with a uniquely designed marker is proposed in this paper. The system is composed of a uniquely designed marker and a camera with a zooming capability, and relative translational and rotational displacement between the marker and the camera is estimated by finding a homography transformation. The novel marker is designed to make the system robust to measurement noise based on a sensitivity analysis of the conventional marker and it has been verified through Monte Carlo simulation results. The performance of the displacement estimation has been verified through two kinds of experimental tests; using a shaking table and a motorized stage. The results show that the system estimates the structural 6-DOF displacement, especially the translational displacement in Z-axis, with high accuracy in real time and is robust to measurement noise.
Haemin Jeon,Hyuntae Bang,Byeongjun Yu 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.32 No.2
This study proposes an automated assembly performance evaluation method for prefabricated steel structures (PSSs) using machine learning methods. Assembly component images were segmented using a modified version of the receptive field pyramid. By factorizing channel modulation and the receptive field exploration layers of the convolution pyramid, highly accurate segmentation results were obtained. After completing segmentation, the positions of the bolt holes were calculated using various image processing techniques, such as fuzzy-based edge detection, Hough's line detection, and image perspective transformation. By calculating the distance ratio between bolt holes, the assembly performance of the PSS was estimated using the k-nearest neighbors (kNN) algorithm. The effectiveness of the proposed framework was validated using a 3D PSS printing model and a field test. The results indicated that this approach could recognize assembly components with an intersection over union (IoU) of 95% and evaluate assembly performance with an error of less than 5%.
Incremental displacement estimation of structures using paired structured light
Jeon, Haemin,Shin, Jae-Uk,Myung, Hyun Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.3
As civil structures are exposed to various external loads, it is essential to assess the structural condition, especially the structural displacement, in every moment. Therefore, a visually servoed paired structured light system was proposed in the previous study. The proposed system is composed of two screens facing with each other, each with a camera, a screen, and one or two lasers controlled by a 2-DOF manipulator. The 6-DOF displacement can be calculated from the positions of three projected laser beams and the rotation angles of the manipulators. In the estimation process, one of well-known iterative methods such as Newton-Raphson or extended Kalman filter (EKF) was used for each measurement. Although the proposed system with the aforementioned algorithms estimates the displacement with high accuracy, it takes relatively long computation time. Therefore, an incremental displacement estimation (IDE) algorithm which updates the previously estimated displacement based on the difference between the previous and the current observed data is newly proposed. To validate the performance of the proposed algorithm, simulations and experiments are performed. The results show that the proposed algorithm significantly reduces the computation time with the same level of accuracy compared to the EKF with multiple iterations.
Incremental Displacement Estimation (IDE) for Structural Health Monitoring Robot
Haemin Jeon,Jae-Uk Shin,Wancheol Myeong,Hyun Myung 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
To measure 6-DOF displacement, a visually servoed paired structured light system (ViSP) has been introduced which is composed of two sides facing with each other, each with one or two lasers, a camera, a screen, and a 2-DOF manipulator. In the system, the lasers on both two sides project their parallel beams to the screen on the opposite side and 6-DOF relative displacement between two sides can be calculated using the positions of the three projected laser beams and the rotation angles of the manipulators. In the estimation process, extended Kalman filter (EKF) or Newton-Raphson method have been used. However, these aforementioned iterative methods have a drawback that the computation time is relatively long due to the multiple iterations. Therefore, in this paper, incremental displacement estimation (IDE) algorithm which updates the previously estimated displacement using the difference of the previous and the current observed data is introduced. To validate the performance of the newly proposed algorithm, various experimental tests have been performed. The results show that the ViSP with the IDE algorithm estimates the 6-DOF relative displacement between two sides with the same level of accuracy of EKF with multiple iterations in significantly reduced time.
Haemin Jeon,Wancheol Myeong,Jae-Uk Shin,Jong-Woong Park,Hyung-Jo Jung,Hyun Myung IEEE 2014 IEEE/ASME transactions on mechatronics Vol.19 No.5
<P>Structural displacement is considered an important indicator to assess structural conditions. To directly measure the displacement in the time domain, a visually servoed paired structured light system was proposed. The system is composed of two sides facing each other, each with one or two lasers that are controlled by a visually servoed two-DOF manipulator, a camera, and a screen. The relative six-DOF displacement between the two sides can be estimated by calculating the positions of the projected laser beams on the screens and the rotation angles of manipulators. To verify the performance of the proposed system, two kinds of field tests were carried out. A prototype of the system was built and installed on a steel frame building structure and a railway bridge, respectively. The estimated displacements were compared with the reconstructed displacement from an accelerometer. The test results verify the performance of the system and its applicability to real structures.</P>
구조물의 6자유도 변위 측정을 위한 비주얼 서보잉 기반 양립형 구조 광 로봇 시스템
전해민(Haemin Jeon),방유석(Yuseok Bang),김한근(Hangeun Kim),명현(Hyun Myung) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.10
This study aims to demonstrate the feasibility of a visual servoing-based paired structured light (SL) robot for estimating structural displacement under various external loads. The former paired SL robot, which was proposed in the previous study, was composed of two screens facing with each other, each with one or two lasers and a camera. It was found that the paired SL robot could estimate the translational and rotational displacement each in 3-DOF with high accuracy and low cost. However, the measurable range is fairly limited due to the limited screen size. In this paper, therefore, a visual servoing-based 2-DOF manipulator which controls the pose of lasers is introduced. By controlling the positions of the projected laser points to be on the screen, the proposed robot can estimate the displacement regardless of the screen size. We performed various simulations and experimental tests to verify the performance of the newly proposed robot. The results show that the proposed system overcomes the range limitation of the former system and it can be utilized to accurately estimate the structural displacement.
실시간 구조물 변위 모니터링을 위한 증분형 변위 측정 알고리즘
전해민(Haemin Jeon),신재욱(Jae-Uk Shin),명완철(Wancheol Myeong),명현(Hyun Myung) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.6
The purpose of this paper is to suggest IDE (Incremental Displacement Estimation) algorithm for the previously proposed visually servoed paired structured light system. The system is composed of two sides facing with each other, each with one or two lasers with a 2-DOF manipulator, a camera, and a screen. The 6-DOF displacement between two sides can be estimated by calculating the positions of the projected laser beams and rotation angles of the manipulators. In the previous study, Newton-Raphson or EKF (Extended Kalman Filter) has been used as an estimation algorithm. Although the various experimental tests have validated the performance of the system and estimation algorithms, the computation time is relatively long since aforementioned algorithms are iterative methods. Therefore, in this paper, a non-iterative incremental displacement estimation algorithm which updates the previously estimated displacement with a difference of the previous and the current observed data is introduced. To verify the performance of the algorithm, experimental tests have been performed. The results show that the proposed non-iterative algorithm estimates the displacement with the same level of accuracy compared to the EKF with multiple iterations with significantly less computation time.
Jeon, Bu-Nam,Kim, Min-Kyeong,Yoon, Jae-Hyeon,Kim, Min-Young,An, Haemin,Noh, Hee-Jin,Choi, Won-Il,Koh, Dong-In,Hur, Man-Wook Oxford University Press 2014 Nucleic acids research Vol.42 No.18
<P>ZNF509 is unique among POK family proteins in that four isoforms are generated by alternative splicing. Short ZNF509 (ZNF509S1, -S2 and -S3) isoforms contain one or two out of the seven zinc-fingers contained in long ZNF509 (ZNF509L). Here, we investigated the functions of ZNF509 isoforms in response to DNA damage, showing isoforms to be induced by p53. Intriguingly, to inhibit proliferation of HCT116 and HEK293 cells, we found that ZNF509L activates <I>p21/CDKN1A</I> transcription, while ZNF509S1 induces <I>RB</I>. ZNF509L binds to the <I>p21/CDKN1A</I> promoter either alone or by interacting with MIZ-1 to recruit the co-activator p300 to activate <I>p21/CDKN1A</I> transcription. In contrast, ZNF509S1 binds to the distal <I>RB</I> promoter to interact and interfere with the MIZF repressor, resulting in derepression and transcription of <I>RB</I>. Immunohistochemical analysis revealed that ZNF509 is highly expressed in normal epithelial cells, but was completely repressed in tumor tissues of the colon, lung and skin, indicating a possible role as a tumor suppressor.</P>