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Journal Articles

Image selection method from image sequence to improve computational efficiency of 3D reconstruction; Analysis of inter-image displacement based on optical flow for evaluating 3D reconstruction performance

Hanari, Toshihide; Kawabata, Kuniaki; Nakamura, Keita

Proceedings of 2022 IEEE/SICE International Symposium on System Integration (SII 2022) (Internet), p.1041 - 1045, 2022/01

This paper describes the image selection method for an efficient three-dimensional (3D) reconstruction computation from an image sequence. Adequate images must be selected from the image sequence to improve the computational efficiency of the 3D reconstruction. Thus, we investigated a threshold based on the displacement among images obtained from a camera mounted on a remotely operated robot. The results confirmed that the proposed method can select adequate images for efficient 3D reconstruction by the threshold based on the optical flow from the image sequence. Therefore, the computational cost could be reduced by eliminating the duplicate and high-similarity images to perform the efficient 3D reconstruction.

Journal Articles

3D reconstruction considering calculation time reduction for linear trajectory shooting

Nakamura, Keita; Hanari, Toshihide; Kawabata, Kuniaki

Proceedings of 27th International Symposium on Artificial Life and Robotics (AROB 27th 2022) (Internet), p.771 - 775, 2022/01

In three-dimensional (3D) reconstruction from images, even if the number of images is small and each image captures the features of the target object for 3D reconstruction, highly accurate 3D reconstruction can be achieved in a short time. Therefore, to select effective images for 3D reconstruction, we consider that test data for image selection can be generated by constructing a virtual space using simulation and changing the shooting conditions. In this study, we focus on the case that a camera moves on a straight rail and obtains images, and investigate and verify the effective image selection conditions considering calculation time reduction for 3D reconstruction in this case by simulation.

Journal Articles

An Image selection method from image sequence collected by remotely operated robot for efficient 3D reconstruction

Hanari, Toshihide; Kawabata, Kuniaki; Nakamura, Keita*; Naruse, Keitaro*

Proceedings of International Workshop on Nonlinear Circuits, Communications and Signal Processing (NCSP 2020) (Internet), p.242 - 245, 2020/02

In this paper, we propose an image selection method to realize efficient three-dimensional (3D) reconstruction from image sequence collected by a remotely operated robot. The proposed method is to select adequate images for reconstruction computation based on optical flow measures. We confirmed that the proposed method can select adequate images for 3D reconstruction from the image sequence recorded by the remotely operated robot that is commanded stop-and-go motions. As a result, we demonstrated a 3D reconstruction could be performed efficiently with relatively few images that were selected by the proposed method.

Journal Articles

Fast in-situ mesh generation using Orb-SLAM2 and OpenMVS

Wright, T.*; Hanari, Toshihide; Kawabata, Kuniaki; Lennox, B.*

Proceedings of 17th International Conference on Ubiquitous Robots (UR 2020) (Internet), p.315 - 321, 2020/00

Journal Articles

Development of a laser chipping technique combined with water jet for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

Yamada, Tomonori; Takebe, Toshihiko*; Ishizuka, Ippei*; Daido, Hiroyuki*; Hanari, Toshihide; Shibata, Takuya; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; et al.

Journal of Nuclear Science and Technology, 56(12), p.1171 - 1179, 2019/12

 Times Cited Count:1 Percentile:23.13(Nuclear Science & Technology)

We describe a new chipping technique combined with a water-jet technique as one of the candidate techniques for the retrieval of fuel debris and support structures as part of the decommissioning of the Fukushima Daiichi Nuclear Power Station. We performed proof-of-principle experiments to demonstrate the removal capability of metal parts, where we focused on the observation of removal processes from a metallic sample using a 5.5-kW continuous wave fiber laser combined with continuous and pulsed water jets.

Journal Articles

Development of a GUI-based operation system for building a 3D point cloud classifier

Tanifuji, Yuta; Kawabata, Kuniaki; Hanari, Toshihide

Proceedings of 2019 IEEE Region Ten Conference (TENCON 2019) (Internet), p.36 - 40, 2019/10

Journal Articles

3D environment reconstruction based on images obtained by reconnaissance task in Fukushima Daiichi Nuclear Power Station

Hanari, Toshihide; Kawabata, Kuniaki

E-Journal of Advanced Maintenance (Internet), 11(2), p.99 - 105, 2019/09

This paper describes our trials on 3-dimensional environment reconstruction from plural images for recognizing the status in the reactor building of Fukushima Daiichi Nuclear Power Station. Structure from Motion is one of photogrammetry techniques to estimate 3-dimensional structure of the objects and the camera's trajectory. We try to apply a Structure from Motion method and a pre-processing to plural images obtained by the reconnaissance task inside Primary Containment Vessel of Unit 3 using remotely operated vehicle. For improving a visibility, Multi-View Stereo is conducted the data obtained by Structure from Motion. In this paper, we report the results of the partial 3D reconstruction using SfM (Structure from Motion) and the visibility improvement of the 3D reconstructed data using MVS.

Journal Articles

Test facility for robots Naraha Center for Remote Control Technology Development

Hanari, Toshihide; Kawabata, Kuniaki

Kinzoku, 89(7), p.582 - 588, 2019/07

no abstracts in English

Journal Articles

3D structural reconstruction based on images obtained by survey task for decommissioning

Hanari, Toshihide; Kawabata, Kuniaki

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

In this paper, we propose a method for improving a visibility of a reconstructed 3D model from images that were photographed at Fukushima Daiichi Nuclear Power Station (NPS). The process of the proposed method consists of pre-processing for correcting a quality of the images, Structure from Motion (SfM) and post-processing for generating a 3D model. We describe the results of the 3D structural reconstruction utilizing plural images recorded by an underwater Remotely Operated Vehicle (ROV) inside the Primary Containment Vessel (PCV). We discussed about the experimental results and confirmed that the proposed method reconstructed major structure in the PCV based on the images.

Journal Articles

Towards enhancement of test facilities for supporting nuclear decommissioning by remote technology

Kawabata, Kuniaki; Mori, Fumiaki*; Shirasaki, Norihito; Tanifuji, Yuta; Hanari, Toshihide

Proceedings of 2017 IEEE/SICE International Symposium on System Integration (SII 2017), p.450 - 455, 2018/02

This paper describes the test facilities and experimental environments for supporting the decommissioning of the nuclear facilities especially Fukushima Daiichi Nuclear Power Station by remote operation. Naraha Remote Technology Development Center of Japan Atomic Energy Agency is an institution for such purpose. Mock-up staircase, robot testing pool and motion capture arena are already installed and full service and support began from April, 2016. We are also designing and developing some experimental environment for remotely operated robots for nuclear decommissioning. In this paper, we describe current status and development of test facilities of Naraha Remote Technology Development Center, Japan Atomic Energy Agency.

Journal Articles

Demonstration of laser processing technique combined with water jet technique for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

Hanari, Toshihide; Takebe, Toshihiko*; Yamada, Tomonori; Daido, Hiroyuki; Ishizuka, Ippei*; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; Sakai, Hideaki*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 3 Pages, 2017/04

In decommissioning of Fukushima Daiichi Nuclear Power Station, a retrieval process of fuel debris in the Primary Containment Vessel by a remote operation is one of the key issues. In this process, prevention of spreading radioactive materials is one of the important considerations. Furthermore, an applicable technique to the process requires keeping of reasonable processing-efficiency. We propose to use the combined technique including a laser light and a water jet as a retrieval technique of the fuel debris. The laser processing technique combined with a repetitive pulsed water jet could perform an efficient retrieval processing. Our experimental result encourages us to promote further development of the technique towards a real application at Fukushima Daiichi Nuclear Power Station.

JAEA Reports

Research on removal technologies of fuel debris and in-vessel structures using laser light (II); Research activities on FY2013

Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Nguyen, P. L.; Matsunaga, Yukihiro

JAEA-Research 2014-018, 41 Pages, 2014/09

JAEA-Research-2014-018.pdf:42.21MB

In decommissioning works of the Fukushima Daiichi Nuclear Power Plants, it is required that fuel debris solidifying mixed materials of fuels and in-vessel structures should be removed. The fuel debris is considered to have characteristics, such as indefinite shapes, porous bodies, multi-compositions, higher hardness, etc. from the knowledge in the U.S. and the Three Mile Island nuclear power plant. Laser lights are characterized by higher power density, local processability, remote controllabilitiy, etc. and can be performed thermal cutting and crushing-up for various materials which does not depend on fracture toughness. This report describes a research program and research activities in FY2013 aiming at developing removal system of fuel debris by the use of laser lights.

JAEA Reports

Research on removal technologies of fuel debris and in-vessel structures using laser light (I); Research plan and research activities on FY2012

Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro

JAEA-Research 2013-024, 49 Pages, 2013/08

JAEA-Research-2013-024.pdf:6.63MB

In decommissioning works of the Fukushima Daiichi Nuclear Power Plants, it is required that fuel debris solidifying mixed materials of fuels and in-vessel structures should be removed. The fuel debris is considered to have characteristics, such as indefinite shapes, porous bodies, multi-compositions, higher hardness, etc. from the knowledge in the U.S. and the Three Mile Island nuclear power plant. Laser lights are characterized by higher power density, local processability, remote controllabilitiy, etc. and can be performed thermal cutting and crushing-up for various materials which does not depend on fracture toughness. This report describes a research program and research activities in FY2012 aiming at developing removal system of fuel debris by the use of laser lights.

Oral presentation

Study on standardization of laser cutting technologies for reactor plants, 5; Evaluation of an assist gas flow characteristics in a thin slit plate

Hanari, Toshihide; Sugihara, Kenta; Ogawa, Takemitsu; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on standardization of laser cutting technologies for reactor plants, 7; Influence evaluation of an assist gas inlet flow rate by kerf width difference

Hanari, Toshihide; Sugihara, Kenta; Muramatsu, Toshiharu; Yamashita, Masanori*; Sakakibara, Jun*

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 1; Outline of the study

Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 3; Evaluation of ceramics crushing characteristics by laser light pulse irradiations

Matsunaga, Yukihiro; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 4; Evaluation of laser cutting and crushing characteristics by an XYZ triaxial robot

Takebe, Toshihiko; Matsunaga, Yukihiro; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 2; Characteristic evaluation of metal cutting by laser continuous irradiation and assist gas flow

Hanari, Toshihide; Matsunaga, Yukihiro; Takebe, Toshihiko; Yamada, Tomonori; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

65 (Records 1-20 displayed on this page)