Faculty Profiles - WAGATSUMA Hiroaki

Papers - WAGATSUMA Hiroaki

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Personalized Feedback in Formative Assessment Support System “Key Words Meeting” for Encouraging Motivation of Learners and Monitoring Their Performance in Individual Classrooms Reviewed International journal

Lee Seungshin, Kurishima Kazuhiro, Jahng Doosub, Wagatsuma Hiroaki

ICIC Express Letters ( ICIC International ) 18 ( 7 ) 731 - 738 2024.07

A Quality Analysis of the BiLSTM Encoder Decoder Model with Modified J-Divergence for Sentences with Different Complexities Reviewed International journal

Shrivastava Manu, Wagatsuma Hiroaki

ICIC Express Letters ( ICIC International ) 18 ( 7 ) 721 - 729 2024.07

An ANCF-Based Theoretical Framework to Deal with Large Deformation of Elastic Element Embedded in Human Knee Joint Orthoses Reviewed International journal

Kasai Shintaro, Wagatsuma Hiroaki

ICIC Express Letters ( ICIC International ) 18 ( 6 ) 607 - 614 2024.06

Motor Imagery Classification Using Effective Channel Selection of Multichannel EEG Reviewed

Shiam A.A., Hassan K.M., Islam M.R., Almassri A.M.M., Wagatsuma H., Molla M.K.I.

Brain Sciences 14 ( 5 ) 2024.05

Trigger circuit design and system integration for simultaneous measurement of human EEG, motion, and gaze Reviewed International journal

Fujiwara M., Duc P.H.H., Bougrain L., Hénaff P., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 1047 - 1050 2024.01

An Integration of Contact Force Models with Multibody Dynamics Analyses for Human Joint Mechanisms and Effects of Viscoelastic Ground Contact Reviewed International journal

Kasai S., Batbaatar D., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 994 - 998 2024.01

An image processing mechanism for aerial inspection robots to detect submillimeter-width concrete cracks in social infrastructures Reviewed International journal

Dixit A., Oshiumi W., Shrivastava M., Wagatsuma H.

Advanced Robotics 38 ( 9-10 ) 698 - 714 2024.01

A Computational Approach for Global Trade Analysis Sensitive to Free Trade Agreement Circumstances: A Case Study Focusing on the Great Mekong Subregion Reviewed International journal

Altaweel A., Lee B.Y., Fujiwara M., Yoon J.S., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 1042 - 1046 2024.01

Classification of Motor Imagery Using Trial Extension in Spatial Domain with Rhythmic Components of EEG Reviewed International journal

Molla M.K.I., Ahamed S., Almassri A.M.M., Wagatsuma H.

Mathematics 11 ( 17 ) 2023.09

An Accuracy Evaluation of Multibody Dynamics for the Knee Support Exoskeleton Model with Respect to Implicit Methods for Numerical Integration Reviewed International journal

Kasai S., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 989 - 993 2023.01

A Structure Pattern Extraction by Using Morphological Component Analysis in the Aerial Image Edge Detection Reviewed International journal

Oshiumi W., Dixit A., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 883 - 887 2023.01

A Linear-Time Algorithm to Form a Core Convex Shape from an Arbitrary Non-Convex for Automated Fulfillment in Robotic Manipulation Tasks Reviewed International journal

Altaweel, A., Uehara, K., Almassri, A. M. M., Wagatsuma, H.

International Journal of Engineering Advanced Research (IJEAR) 4 ( 3 ) 1 - 11 2022.09

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

In the field of robotic manipulation, a fully automatic object fulfillment is an important issue in applications not only for high-density warehouse optimization but also for agricultural automation. In the present study, a formulation of the fulfillment of the maximum object into a given non-convex area was proposed. For minimizing redundant space inside a container during a packing task, the optimization problem is inevitable. Even edges of the target area are clearly detected, the best scenario to fill candidate objects sequentially is not apparently calculated. To deal with this problem, the proposed method is composed of two processes as decomposition of the original non-convex shape and reconstruction of a convex shape, based on theories of computational geometry. For example, it is difficult to judge a point either inside or outside of the area if it is non-convex, while it is easy to judge if the area is convex in the sense of the theorem of computational geometry. The proposed method is initiated by a recursive procedure proposed to decompose non-convex parts until it forms a remaining part to be a convex shape, and then it shifts to the reconstruction of a developing convex shape by adding decomposed parts in the first process, which it will be convex with the maximum size to be a subset of the original non-convex shape. It finally provides the right answer to be a filling area for candidate objects. Since the decomposition and reconstruction will be done in the circulation of removal and attachment of decomposed triangle parts, which takes computational costs of N (the number of nodes) steps as maximum in rotation as a linear- time algorithm. Theoretically, a simple detection algorithm of the maximum fulfillment area can be derived from an arbitrary combination of nodes as 2N. In the computer experiment, the reduction of the computational cost was clearly demonstrated in the comparison of the proposed method and the combinatory method. It contributes to the enhancement of the potential of computational geometry in an effective design of optimization units for robotics working in unstable and dynamic environments.

Determining the Elastic Properties of Flexible 3D Printed Beams with Variable Infill Densities and Patterns Reviewed International journal

Bhattacharjee, A., Dachkinov, P., Wagatsuma, H., Bhattacharya, B.

International Journal of Engineering Advanced Research (IJEAR) 4 ( 3 ) 12 - 24 2022.09

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

Flexible non-linear 3D printed materials are rapidly gaining popularity in various engineering applications such as soft robotics, actuators, medical devices, etc. Due to their wide applicability, there is an increased research interest in characterization of their mechanical properties and performance. Unlike the conventional manufacturing processes, 3D printing has an additive character and allows for the geometry to be controlled from inside. The internal geometry and density corresponding to a given model can be tuned to a desired stiffness. In this study we investigate the effect of the infill percentage and infill geometry on the mechanical properties of 3D printed samples from flexible material by using a desktop type FDM 3D printer. The analyzed samples have the same shape and geometry – a beam with a square cross-section but the infill percentage is varied from 10 % to a 100 % with an increment of 15 %. The effects of three different types of infill geometries– rectangular, square and honeycomb have also been analytically determined. The approach for the analytical formulation adopts the methodology for calculating the in- plane properties and stiffnesses in cellular solids. The results for the mechanical properties for the different infill densities and infill geometries have been compared for all configurations. Despite the common external geometry of all beams, there is a significant change in their stiffness with the variation of the infill patterns and densities. Finally, a non-linear FEA study for the fully solid beam was conducted and compared with the analytical results. The method, used in this study can be applied for optimization of the stiffness to weight ratio during the design process of flexible 3D printed parts undergoing larger deformations.

A Comparative Study of Vector and Raster Spatial Data for Image Segmentation Focusing on the Position Estimation Accuracy of Vertices to Form Polygonal Shapes Reviewed International journal

Altaweel, A., Almassri, A. M. M., Purev, A., Wagatsuma, H.

International Journal of Engineering Advanced Research (IJEAR) 4 ( 3 ) 25 - 34 2022.09

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

In the field of image processing, raster data is frequently used for image segmentation and shape estimations for general purposes. On the other hand, in the medical field, which aims to help doctors in surgical operations, semi-automatic robotic manipulations such as the da Vinci Surgical Systemto minimize the necessary area to open for the living body. In the present study, a computational geometry-based method was proposed for vector data to treat the rearrangement of extracted points as candidates for edges of the target shape. On the other hand, the Harris-Stephens algorithm was introduced as a well-known method to detect vertices to form polygonal shapes in raster data as the counterpart in the comparative study. Typically, such a raster data method is not robust to perform in noisy conditions without appropriate filtering in the pre-processing. In the Harris-Stephens algorithm, the adding noises were detected as new vertices to form shapes in the area, which is inevitable in the condition without any semantic information about the shape. Since the proposed computational geometry-based method contains geometrical properties in its computation, it can be enhanced to be robust against noisy data. In the sense of designing a part of the system to be a surgical robot, which requires high accuracy of the position estimation of the target, a maximization of extractions of geometrical properties provides a significant benefit for accurate manipulation of robotic arms. It contributes not only to surgical robots but also to the solver of 2D replacement puzzles known as tangram puzzles to be a general scheme for robots in all fields behaving in dynamic environments.

A Three-Dimensional Design of the Multi-material Joint System to Realize a Structural Spring-Damper Compliant Mechanism with Versatility in Engineering Fields Reviewed International journal

Dachkinov Pancho, Bhattacharjee Anirudha, Bhattacharya Bishakh, Wagatsuma Hiroaki

Proceedings of International Conference on Artificial Life and Robotics ( ALife Robotics Corporation Ltd. ) 27 193 - 200 2022.01

A Systematic Geometric Design Method of Flexible Bars Available for Personalized Knee Orthoses with Spring-Damper Functions Reviewed International journal

Dachkinov Pancho, Kasai Shintaro, Tanaka Kohei, Wagatsuma Hiroaki

Proceedings of International Conference on Artificial Life and Robotics ( ALife Robotics Corporation Ltd. ) 27 724 - 730 2022.01

A Drone-Based Concrete Crack Inspection System by Using Morphological Component Analysis and Sub-Pixel Width Estimation Reviewed International journal

Dixit Ankur, Oshiumi Wataru, Wagatsuma Hiroaki

Proceedings of International Conference on Artificial Life and Robotics ( ALife Robotics Corporation Ltd. ) 27 717 - 723 2022.01

A Systematic Analysis of the Knee Support Exoskeleton Based on Multibody Dynamics Toward Personalization with 3D printed Spring-Damper Components Reviewed International journal

Kasai Shintaro, Dachkinov Pancho, Tanaka Kohei, Wagatsuma Hiroaki

Proceedings of International Conference on Artificial Life and Robotics ( ALife Robotics Corporation Ltd. ) 27 712 - 716 2022.01

A Three-Dimensional Design of the Multi-material Joint System to Realize a Structural Spring-Damper Compliant Mechanism with Versatility in Engineering Fields Reviewed International journal

Dachkinov P., Bhattacharjee A., Bhattacharya B., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 193 - 200 2022.01

A Systematic Analysis of the Knee Support Exoskeleton Based on Multibody Dynamics Toward Personalization with 3D printed Spring-Damper Components Reviewed International journal

Kasai S., Dachkinov P., Tanaka K., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 712 - 716 2022.01

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Papers - WAGATSUMA Hiroaki