研究者詳細 - 我妻　広明

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A Computational Approach for Global Trade Analysis Sensitive to Free Trade Agreement Circumstances: A Case Study Focusing on the Great Mekong Subregion 査読有り国際誌

Altaweel Ahmad, Lee Bo-Young, Fujiwara Masayuki, Yoon Jang-Sok, Wagatsuma Hiroaki

人工生命とロボットに関する国際会議予稿集 ( 株式会社ALife Robotics ) 29 1042 - 1046 2024年02月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In the Global Trade Analysis Project (GTAP), GDP and economic statistical indices can be analyzed for forecasting future trends in multiple countries by using the GTAP database and GEMPACK utilities, which realize the numerical calculation based on the concept of Computable General Equilibrium (CGE) models. Even with such well-prepared tools with the official database, appropriate forecasting is still difficult due to the sensitivity of the Free Trade Agreement (FTA) circumstances. FTA scenarios with a uniform tariff reduction can be assumed in general, while an abrupt and unreasonable change may occur in the simulation depending on the network structure of trading countries and the upper and lower bounds of tariffs in the time course. In the present study, we focused on the Great Mekong subregion (GMS) and explored possible methods to calculate substantially.

DOI： 10.5954/icarob.2024.gs6-2

Trigger circuit design and system integration for simultaneous measurement of human EEG, motion, and gaze 査読有り国際誌

Fujiwara Masayuki, Phan Duc, Bougrain Laurent, Hénaff Patrick, Wagatsuma Hiroaki

人工生命とロボットに関する国際会議予稿集 ( 株式会社ALife Robotics ) 29 1047 - 1050 2024年02月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Simultaneous measurement of EEG, motion, and gaze in humans has the potential to lead to the discovery of new scientific insights. In order to achieve these simultaneous measurements, it is necessary to manage triggers and time information between measurement devices, as well as to correct time offsets. However, the management of accurate triggers and time information requires the design of a dedicated circuit board and the integration of TransistorTransistor Logic signal voltage information. In this study, we report on the building of a trigger circuit and an experimental system using it to solve these problems. We created a home-made trigger circuit board for voltage integration and combined it with a commercially available microcomputer to realize an integrated trigger circuit and measurement system.

DOI： 10.5954/icarob.2024.gs6-3

An Integration of Contact Force Models with Multibody Dynamics Analyses for Human Joint Mechanisms and Effects of Viscoelastic Ground Contact 査読有り国際誌

Kasai Shintaro, Batbaatar Dondogjamts, Wagatsuma Hiroaki

人工生命とロボットに関する国際会議予稿集 ( 株式会社ALife Robotics ) 29 994 - 998 2024年02月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In human movement and rehabilitation analyses, human joint dynamics is a key to consider the incorporation of spring-damper components, flexible bodies and contact forces analytically. In the present study, an analytical method for human gaits were introduced to integrate those essential elements, and viscoelastic properties of musculoskeletal system were modeled with the absolute nodal coordination formula (ANCF) method representing flexible body motions. A contact force model simulates interactions between different body segments and the environment. The proposed system is applied to a slider crank mechanism, demonstrating its capabilities in human joint motion analysis using integrated dynamic model within the framework of multibody dynamics (MBD), which realizes dynamic/inverse dynamics for human biomechanics.

DOI： 10.5954/icarob.2024.gs4-3

Trigger circuit design and system integration for simultaneous measurement of human EEG, motion, and gaze 査読有り国際誌

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

Proceedings of International Conference on Artificial Life and Robotics 1047 - 1050 2024年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Simultaneous measurement of EEG, motion, and gaze in humans has the potential to lead to the discovery of new scientific insights. In order to achieve these simultaneous measurements, it is necessary to manage triggers and time information between measurement devices, as well as to correct time offsets. However, the management of accurate triggers and time information requires the design of a dedicated circuit board and the integration of Transistor- Transistor Logic signal voltage information. In this study, we report on the building of a trigger circuit and an experimental system using it to solve these problems. We created a home-made trigger circuit board for voltage integration and combined it with a commercially available microcomputer to realize an integrated trigger circuit and measurement system.

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An Integration of Contact Force Models with Multibody Dynamics Analyses for Human Joint Mechanisms and Effects of Viscoelastic Ground Contact 査読有り国際誌

Kasai S., Batbaatar D., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 994 - 998 2024年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In human movement and rehabilitation analyses, human joint dynamics is a key to consider the incorporation of spring-damper components, flexible bodies and contact forces analytically. In the present study, an analytical method for human gaits were introduced to integrate those essential elements, and viscoelastic properties of musculoskeletal system were modeled with the absolute nodal coordination formula (ANCF) method representing flexible body motions. A contact force model simulates interactions between different body segments and the environment. The proposed system is applied to a slider crank mechanism, demonstrating its capabilities in human joint motion analysis using integrated dynamic model within the framework of multi body dynamics (MBD), which realizes dynamic/inverse dynamics for human biomechanics.

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An image processing mechanism for aerial inspection robots to detect submillimeter-width concrete cracks in social infrastructures 査読有り国際誌

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

Advanced Robotics 38 ( 9-10 ) 698 - 714 2024年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

Inspection robots for early detection of potential risks in severe environments require a high accuracy like human experts. A fine mechanism is crucial for extracting target components from noisy signals. We have proposed a detection system for submillimeter-width cracks in concrete surfaces of social infrastructures, such as bridges, by using morphological component analysis (MCA), for aerial image-inspection robots. Traditional schemes like PCA have relied on linear decomposition for the separation of target signal and noise components. Recent advancement in signal decomposition focuses on the enhancement of linearity in the separation by introducing a set of nonlinear basis functions to represent the raw signal even when multiple factors are mixed in a nonlinear manner. In this sense, MCA is a core technique to be able to isolate target components to represent submillimeter-width cracks from others. We proposed a proper pre- and post-processing operations to attach MCA, which demonstrated a high accuracy yet coarse and fine image components have to be integrated redundantly. In the present study, we successfully found a simpler mechanism to set the single basis function to extract the target by introducing a new thresholding mechanism. It suggests a high potential of MCA for inspection robots for various purposes.

DOI： 10.1080/01691864.2024.2324317

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A Computational Approach for Global Trade Analysis Sensitive to Free Trade Agreement Circumstances: A Case Study Focusing on the Great Mekong Subregion 査読有り国際誌

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

Proceedings of International Conference on Artificial Life and Robotics 1042 - 1046 2024年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

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Conditional checkpoint selection strategy based on sentence structures for text to triple translation using BiLSTM encoder–decoder model 査読有り国際誌

Shrivastava M., Shibata K., Wagatsuma H.

International Journal of Data Science and Analytics 2024年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

Understanding natural languages is one of the primary goals of artificial intelligence. Natural languages contain multiple clauses and long-term dependencies making them difficult for machines to understand, also sentences can have different types of dependency structures such as simple, compound, or complex which makes interpretation further difficult. One alternative way is to represent language using predicate logic which is easier for machines to understand. The task of manually converting language to predicate logic or ontologies can be cumbersome, but it can be automated using machine translation. For these ontologies to be effective the quality of translation should be good. In this research, we focus on analyzing the effect of sentence structure on machine translation quality, i.e., how the model performance is affected if the dataset is structurally skewed meaning it has sentences of similar structure more as compared to other structures. We further investigate the model learning behavior by performing statistical analysis on features learned by these models and understand the effects of sentence structure on these learned features. The statistical analysis helps us understand the distribution followed by the features and based on the insights gained we proposed a conditional checkpoint selection strategy centered on sentence structure along with utilizing Modified J-Divergence as a loss function for optimizing model performance for different sentence structures thus achieving better translation quality.

DOI： 10.1007/s41060-024-00672-0

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A MBD-Based Dynamic Analysis Framework with a Viscoelastic Contact Model and Flexible Elements Toward Human Power Assistive Devices 査読有り国際誌

Kasai Shintaro, Batbaatar Dondogjamts, Wagatsuma Hiroaki

Journal of Robotics, Networking and Artificial Life ( 株式会社 ALife Robotics ) 10 ( 4 ) 318 - 322 2024年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

It is important for the analysis of human movement and rehabilitation to incorporate spring-damper components, flexible materials, and contact force into the joint model considering human dynamics. In this study, the absolute nodal coordination formula (ANCF) method is introduced to the analytical model for the viscoelastic properties of the musculoskeletal system which is essential for analyzing human walking motion, and the flexible characteristics of the human body is reproduced. The consideration of a contact force model makes it possible to simulate contact actions between elements of the human body and the interaction with the environment. The proposed integrated framework is applied to multibody dynamics (MBD) based slider-crank mechanisms to demonstrate the dynamics/inverse dynamics analysis of human joint biomechanics.

DOI： 10.57417/jrnal.10.4_318

Classification of Motor Imagery Using Trial Extension in Spatial Domain with Rhythmic Components of EEG 査読有り国際誌

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

Mathematics 11 ( 17 ) 2023年09月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

Electrical activities of the human brain can be recorded with electroencephalography (EEG). To characterize motor imagery (MI) tasks for brain–computer interface (BCI) implementation is an easy and cost-effective tool. The MI task is represented by a short-time trial of multichannel EEG. In this paper, the signal of each channel of raw EEG is decomposed into a finite set of narrowband signals using a Fourier-transformation-based bandpass filter. Rhythmic components of EEG are represented by each of the narrowband signals that characterize the brain activities related to MI tasks. The subband signals are arranged to extend the dimension of the EEG trial in the spatial domain. The spatial features are extracted from the set of extended trials using a common spatial pattern (CSP). An optimum number of features are employed to classify the motor imagery tasks using an artificial neural network. An integrated approach with full-band and narrowband signals is implemented to derive discriminative features for MI classification. In addition, the subject-dependent parameter optimization scheme enhances the performance of the proposed method. The performance evaluation of the proposed method is obtained using two publicly available benchmark datasets (Dataset I and Dataset II). The experimental results in terms of classification accuracy (93.88% with Dataset I and 91.55% with Dataset II) show that it performs better than the recently developed algorithms. The enhanced MI classification accuracy is very much applicable in BCI implementation.

DOI： 10.3390/math11173801

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An Accuracy Evaluation of Multibody Dynamics for the Knee Support Exoskeleton Model with Respect to Implicit Methods for Numerical Integration 査読有り国際誌

Kasai S., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 989 - 993 2023年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Numerical integration takes an important role to analyze models described by ordinary differential equations and it largely contributes to an assurance of the accuracy in displacement analyses of multibody dynamics if the model consists of several bodies especially with dynamic components such as springs and dampers. Exoskeletal assistive devices require flexible materials for absorbing reaction forces from human joints, which implies an inevitable necessity of an accurate evaluation of elastic effects in the model. In the present study, we introduced implicit methods for numerical integration to analyze the model under the formulation of multibody dynamics and computer experiments demonstrated results from explicit and implicit methods for the numerical integration as a comparison analysis. It can improve a degree of accuracy in inverse dynamics even in the theory of flexible Multibody Dynamics (fMBD).

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A Structure Pattern Extraction by Using Morphological Component Analysis in the Aerial Image Edge Detection 査読有り国際誌

Oshiumi W., Dixit A., Wagatsuma H.

Proceedings of International Conference on Artificial Life and Robotics 883 - 887 2023年01月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Automated extraction of areas of interest from aerial images is a central issue for map makers. The road skeleton is one of the most frequent targets, and then the prefiltering of road structures is highly important; however, the isolation of man-made structures from a natural landscape is technically tricky because image parts to represent natural geographical features are not uniform patterns. In the present study, we focused on the function of the Morphological Component Analysis (MCA) method to extract structural patterns when dictionaries were appropriately given and demonstrated the effectiveness of edge detection if the prefiltering was done by using MCA. MCA decomposes the image into two patterns in our computer experiment with Curvelet transform and Local Discrete Cosine Transform (LDCT) dictionaries. This approach will explore extensive possibilities of structural data extraction from complex images as an automated method.