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49 results on '"Tamura, Yusuke"'

2. Optimization of Detector Movement Algorithm Using Decision Trees Analysis for Radiation Source Identification Based on 4π Gamma Imaging

Author

Mukai, Atsushi, primary, Hara, Shintaro, additional, Yamagishi, Keita, additional, Terabayashi, Ryohei, additional, Shimazoe, Kenji, additional, Tamura, Yusuke, additional, Woo, Hanwool, additional, Kishimoto, Takuya, additional, Kogami, Hiroki, additional, Zhihong, Zhong, additional, Uenomachi, Mizuki, additional, Nurrachman, Agus, additional, Takahashi, Hiroyuki, additional, Asama, Hajime, additional, Ishida, Fumihiko, additional, Ebi, Hidetake, additional, Takada, Eiji, additional, Kawarabayashi, Jun, additional, Tanabe, Kosuke, additional, Kamada, Kei, additional, and Tomita, Hideki, additional

Published
2022
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8. Gamma-ray Source Identification by a Vehicle-mounted 4π Compton Imager

Author

Tomita, Hideki, primary, Mukai, Atsushi, additional, Kanamori, Kotaro, additional, Shimazoe, Kenji, additional, Woo, Hanwool, additional, Tamura, Yusuke, additional, Hara, Shintaro, additional, Terabayashi, Ryohei, additional, Uenomachi, Mizuki, additional, Nurrachman, Agus, additional, Takahashi, Hiroyuki, additional, Ebi, Hidetake, additional, Ishida, Fumihiko, additional, Takada, Eiji, additional, Kawarabayashi, Jun, additional, Tsuchiya, Ken'ichi, additional, and Iguchi, Tetsuo, additional

Published
2020
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12. Acoustic Camera-Based Pose Graph SLAM for Dense 3-D Mapping in Underwater Environments.

Author

Wang, Yusheng, Ji, Yonghoon, Woo, Hanwool, Tamura, Yusuke, Tsuchiya, Hiroshi, Yamashita, Atsushi, and Asama, Hajime

Subjects
DENSE graphs, UNDERWATER exploration, SONAR imaging, ROBOT vision
Abstract

In this article, a novel dense underwater 3-D mapping paradigm based on pose graph simultaneous localization and mapping (SLAM) using an acoustic camera mounted on a rotator is proposed. The demands of underwater tasks, such as unmanned construction using robots, are growing rapidly. In recent years, the acoustic camera, which is a state-of-the-art forward-looking imaging sonar, has been gradually applied in underwater exploration. However, distinctive imaging principles make it difficult to gain an intuitive perception of an underwater environment. In this study, an acoustic camera with a rotator was used for dense 3-D mapping of the underwater environment. The proposed method first applies a 3-D occupancy mapping framework based on the acoustic camera rotating around the acoustic axis using a rotator at a stationary position to generate 3-D local maps. Then, scan matching of adjacent local maps is implemented to calculate odometry without involving internal sensors, and an approximate dense global map is built in real time. Finally, based on a graph optimization scheme, offline refinement is performed to generate a final dense global map. Our experimental results demonstrate that our 3-D mapping framework for an acoustic camera can achieve dense 3-D mapping of underwater environments robustly and accurately. [ABSTRACT FROM AUTHOR]

Published
2021
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16. Temporal Features of Muscle Synergies in Sit-to-Stand Motion Reflect the Motor Impairment of Post-Stroke Patients.

Author

Yang, Ningjia, An, Qi, Kogami, Hiroki, Yamakawa, Hiroshi, Tamura, Yusuke, Takahashi, Kouji, Kinomoto, Makoto, Yamasaki, Hiroshi, Itkonen, Matti, Shibata-Alnajjar, Fady, Shimoda, Shingo, Hattori, Noriaki, Fujii, Takanori, Otomune, Hironori, Miyai, Ichiro, Yamashita, Atsushi, and Asama, Hajime

Subjects
MUSCLES, OLDER people, MOTION, DISABILITIES, MOTORS
Abstract

Sit-to-stand (STS) motion is an important daily activity, and many post-stroke patients have difficulty performing STS motion. Previous studies found that there are four muscle synergies (synchronized muscle activations) in the STS motion of healthy adults. However, for post-stroke patients, it is unclear whether muscle synergies change and which features primarily reflect motor impairment. Here, we use a machine learning method to demonstrate that temporal features in two muscle synergies that contribute to hip rising and balance maintenance motion reflect the motor impairment of post-stroke patients. Analyzing the muscle synergies of age-matched healthy elderly people ($n = 12$) and post-stroke patients ($n = 33$), we found that the same four muscle synergies could account for the muscle activity of post-stroke patients. Also, we were able to distinguish post-stroke patients from healthy people on the basis of the temporal features of these muscle synergies. Furthermore, these temporal features were found to correlate with motor impairment of post-stroke patients. We conclude that post-stroke patients can still utilize the same number of muscle synergies as healthy people, but the temporal structure of muscle synergies changes as a result of motor impairment. This could lead to a new rehabilitation strategy for post-stroke patients that focuses on activation timing of muscle synergies. [ABSTRACT FROM AUTHOR]

Published
2019
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25. Adaptive Motion Planning Based on Vehicle Characteristics and Regulations for Off-Road UGVs.

Author

Ji, Yonghoon, Tanaka, Yusuke, Tamura, Yusuke, Kimura, Mai, Umemura, Atsushi, Kaneshima, Yoshiharu, Murakami, Hiroki, Yamashita, Atsushi, and Asama, Hajime

Abstract

In this paper, we propose a novel motion planning method for off-road unmanned ground vehicles, based on three-dimensional (3-D) terrain map information. Previous studies on the motion planning of a vehicle traveling on rough terrain dealt only with a relatively small environment. Furthermore, unique vehicle characteristics were not considered, and it was also impossible to incorporate regulations, such as maintaining driving speed and suppressing posture change. The proposed method enables vehicles to adaptively generate a path by considering vehicle characteristics and the regulations, in a large-scale environment, with rough terrain. A random sampling based scheme was applied to carrying out global path planning, based on a 3-D environmental model. Experimental results showed that the proposed off-road motion planner could generate an appropriate path, which satisfies vehicle characteristics and predefined regulations. [ABSTRACT FROM AUTHOR]

Published
2019
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49. A comparative study of dynamical sequential and global optimal task reallocation methodology for distributed multi-robot system.

Author

Li, Guanghui, Tamura, Yusuke, and Asama, Hajime

Abstract

We firstly consider a kind of dynamical mobile task assignment problem, which allows the condition of tasks and robots to be time dependent before assigned robots accomplish the relational tasks. For such new domain, we propose two methods, one is called dynamical sequential task allocation and reallocation, and another is global optimal task allocation and reallocation, for the distributed multi-robot coordination system. The former approach implements multi-round negotiation and body expansion behavior for mobile tasks selection. To utilize body expansion behavior, we set two distance thresholds for robot decision making. The latter method is extended from combinatorial optimization and market-based task allocation. Robots bid tasks and transmit the costs to other robots. Then robots select tasks from the combinatorial cost table based on the objective function. This paper is a comparative study of the mentioned methods above. The simulation results show that minimal executed costs and maximal accomplished efficiency are obtained by global optimal task allocation and reallocation method, while this method consumes numerous communication costs and computation times. Reversely, dynamical sequential task allocation and reallocation is an approximative global optimal assignment approach. Otherwise it expends acceptable communication costs and computation times. [ABSTRACT FROM PUBLISHER]

Published
2011
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