Ryo Shibata, Rei Akasaka, Yuichro Toda, Takayuki Matsuno
{"title":"Pointgng: a deep learning architecture for 3D point cloud recognition using growing neural gas","authors":"Ryo Shibata, Rei Akasaka, Yuichro Toda, Takayuki Matsuno","doi":"10.1007/s10015-025-01097-z","DOIUrl":"10.1007/s10015-025-01097-z","url":null,"abstract":"<div><p>In recent years, there is a strong need for autonomous robots to solve labor shortages and perform tasks in harsh environments. These robots need to avoid obstacles and plan their paths by analyzing data acquired in real environments and generating environmental maps. Unsupervised learning using Growing Neural Gas (GNG) is an algorithm that dynamically constructs a graph structure based on 3D point clouds acquired from sensors. GNG is characterized by its high robustness to downsampling and inhomogeneous data. On the other hand, although clustering based on the constructed topological structure is possible, it is not possible to recognize objects after clustering. To perform a wide range of tasks, the ability to recognize objects is essential, and deep learning methods are effective for this purpose. In particular, PointNet was the first point cloud deep learning model to deal with the irregularity and order invariance of point clouds. In this study, we propose a new deep learning model, PointGNG, which integrates GNG with PointNet++ and extracts local structural features using adjacency-based neighborhood information. Using this method, the proposed method achieved accuracy comparable to PointNet++ on the ModelNet40 benchmark. A slight improvement in accuracy was also observed for other datasets that include background information. This study demonstrates that the integration of unsupervised learning and deep learning with GNG is effective for efficient processing of point cloud data and object recognition. Furthermore, we evaluated the robustness of the proposed model and examined how the choice of training dataset affects its adaptability to real-world environments.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 1","pages":"337 - 346"},"PeriodicalIF":0.8,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147336159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Communication emergence under reward delay: the role of direct utility in temporally extended communication games","authors":"Naoki Inoue, Kei Wakabayashi","doi":"10.1007/s10015-025-01091-5","DOIUrl":"10.1007/s10015-025-01091-5","url":null,"abstract":"<div><p>This study investigates the evolutionary mechanisms of communication emergence by using temporally extended communication games, which are implemented as a multi-agent reinforcement learning environment. Our experimental results provide three key insights: (1) Reward delay is an essential factor that affects the possibility of communication emergence. When the reward delay is large, (2) direct utilities of signaling actions that facilitate the ritualization process become necessary for establishing communication, and (3) the sender’s well-established policy to maintain signaling is more critical than the receiver’s pre-evolved reaction policy. These insights provide a better understanding of the role of direct utilities for signaling, which may stimulate new exploration of the evolutionary origins of communications in nature.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 2","pages":"515 - 527"},"PeriodicalIF":0.8,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147938442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Deep reinforcement learning for multi-agent coordination","authors":"Kehinde O. Aina, Sehoon Ha","doi":"10.1007/s10015-025-01089-z","DOIUrl":"10.1007/s10015-025-01089-z","url":null,"abstract":"<div><p>We address the challenge of coordinating multiple robots in narrow and confined environments, where congestion and interference often hinder collective task performance. Drawing inspiration from insect colonies, which achieve robust coordination through stigmergy—modifying and interpreting environmental traces—we propose a <i>stigmergic multi-agent deep reinforcement learning (S-MADRL)</i> framework that leverages virtual pheromones to model local and social interactions, enabling decentralized emergent coordination without explicit communication. To overcome the convergence and scalability limitations of existing algorithms such as MADQN, MADDPG, and MAPPO, we leverage curriculum learning, which decomposes complex tasks into progressively harder sub-problems. Simulation results show that our framework achieves the most effective coordination of up to eight agents, where robots self-organize into asymmetric workload distributions that reduce congestion and modulate group performance. This emergent behavior, analogous to strategies observed in nature, demonstrates a scalable solution for decentralized multi-agent coordination under crowded environments with communication constraints.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 2","pages":"484 - 494"},"PeriodicalIF":0.8,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10015-025-01089-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147938435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hans Jarett J. Ong, Brian Godwin S. Lim, Renzo Roel P. Tan, Kazushi Ikeda
{"title":"Causal discovery in Additive Noise Models using beam search","authors":"Hans Jarett J. Ong, Brian Godwin S. Lim, Renzo Roel P. Tan, Kazushi Ikeda","doi":"10.1007/s10015-025-01095-1","DOIUrl":"10.1007/s10015-025-01095-1","url":null,"abstract":"<div><p>Causal discovery from observational data is a fundamental challenge. Greedy search algorithms like Regression with Subsequent Independence Test (RESIT), commonly used for learning Additive Noise Models (ANMs), are susceptible to making irreversible errors, especially in high-variance contexts. Such settings can be caused by unmeasured confounders or by high statistical noise from finite samples. To address this, we introduce a novel generalization of RESIT that replaces its local, greedy search with a more robust beam search, framing the task as a path search on a state-space graph. Through extensive simulation experiments, we demonstrate that structural accuracy, measured by Structural Hamming Distance (SHD) and Structural Intervention Distance (SID), consistently improves as the beam width (<i>w</i>) increases. Crucially, we also show that this performance gain comes at a manageable, approximately linear increase in computational cost relative to <i>w</i>. Furthermore, our analysis across different sample sizes shows these gains are most statistically significant in intermediate regimes (<span>(n=250, 500)</span>). This suggests that at these sample sizes, the statistical noise is high enough to mislead the greedy search into a suboptimal ordering, an error our wider beam search corrects, while performance converges at large sample sizes (<span>(n=1000)</span>). Our framework provides a practical, tunable algorithm that bridges the gap between fast but brittle local search methods and computationally infeasible global searches, thereby enhancing the reliability of causal discovery in complex, high-variance settings where such local errors are common.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 1","pages":"317 - 326"},"PeriodicalIF":0.8,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147342303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Self-corrective behavior for turn repetition in pill bugs","authors":"Yuta Miyama, Ayaka Fujimoto, Toru Moriyama","doi":"10.1007/s10015-025-01092-4","DOIUrl":"10.1007/s10015-025-01092-4","url":null,"abstract":"<div><p>Pill bugs (<i>Armadillidium vulgare</i>) demonstrate a behavior called turn repetition. For example, this behavior is seen when they repeat their path choice on successive trials of the T-mazes with long distance between T-junctions. However, sometimes, they stop after turning and change their direction. The function of this directional change has not been investigated for turn repetition. The present paper shows that pill bugs use directional changes to prevent them from turning in the different direction on two successive turns, a behavior called turn alternation. We examined the behavior of 20 pill bugs that each completed 49 successive combinations of L-corner and T-junction trials in an experimental pathway with long distance between the corner and the junction. Directional changes appeared more frequently when they began turn alternations than when they did turn repetitions. These results suggest that pill bugs have an inherent mechanism that acts to maintain turn repetition behavior.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 2","pages":"528 - 535"},"PeriodicalIF":0.8,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147938628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A study on constraint extraction and exception exclusion in care worker scheduling","authors":"Koki Suenaga, Tomohiro Furuta, Satoshi Ono","doi":"10.1007/s10015-025-01082-6","DOIUrl":"10.1007/s10015-025-01082-6","url":null,"abstract":"<div><p>Technologies for automatically generating work schedules have been extensively studied; however, in long-term care facilities, the conditions vary between facilities, making it essential to interview the managers who create shift schedules to design facility-specific constraint conditions. The proposed method utilizes constraint templates to extract combinations of various components, such as shift patterns for consecutive days or staff combinations. The templates can extract a variety of constraints by changing the number of days and the number of staff members to focus on and changing the extraction focus to patterns or frequency. In addition, unlike existing constraint extraction techniques, this study incorporates mechanisms to exclude exceptional constraints. The extracted constraints can be employed by a constraint programming solver to create care worker schedules. Experiments demonstrated that our proposed method successfully created schedules that satisfied all hard constraints and reduced the number of violations for soft constraints by circumventing the extraction of exceptional constraints.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 2","pages":"575 - 584"},"PeriodicalIF":0.8,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147938558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ChatRAD: a robotic animation display system with text-to-image generative AI","authors":"Masahiro Ishikane, Yanchun Li, Yuki Minami, Shinsaku Izumi, Masato Ishikawa","doi":"10.1007/s10015-025-01074-6","DOIUrl":"10.1007/s10015-025-01074-6","url":null,"abstract":"<div><p>A multi-agent system is a system in which multiple agents cooperate to achieve a global objective. Each agent within the system can move independently and exchange information with other agents to collaborate in executing tasks. As an entertainment application of multi-agent systems, previous research has been conducted to realize a mass game in which a group of small robots displays static images. Additionally, with the recent advancements in text-to-image generative models (e.g., stable diffusion), image generative AI has rapidly gained popularity across various fields. In this paper, we propose ChatRAD, a system that integrates image generative AI with a multi-agent system, allowing a group of robots to display animations based on text input from users. We describe the detailed structure and functionality of the system, as well as the control laws governing the robot swarm. Numerical experiments are conducted using multiple target animations to evaluate the system’s performance. Furthermore, to enhance the quality of the displayed animations, we apply Bayesian optimization for gain tuning and verify its effectiveness using image evaluation indices.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"30 4","pages":"803 - 811"},"PeriodicalIF":0.8,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145529539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Development of a cable-driven four-legged soft robot with wave-like locomotion","authors":"Tomoya Inagaki, Klara Bezha, Kazuyuki Ito","doi":"10.1007/s10015-025-01086-2","DOIUrl":"10.1007/s10015-025-01086-2","url":null,"abstract":"<div><p>In recent years, soft robots composed of flexible materials like silicone rubber have attracted significant attention due to their ability to adapt to unknown environments. These robots are typically inspired by the morphology and behavior of living organisms. In nature, biological species employ various locomotion gaits, with the wave-like motion observed in caterpillars, being one of the most stable examples. This locomotion strategy offers a simple and effective method of movement with minimal control, enabling adaptation to various terrains, making it a promising approach for soft robots. This study focuses on demonstrating the effectiveness of using wave-like motion as a locomotion mechanism in soft robots. This paper presents the development of a prototype four-legged soft robot that utilizes wave-like locomotion for bidirectional movement and clockwise and counterclockwise turning. Experiments confirmed the proposed robot's ability to move at approximately 1 cm/s on flat surfaces, overcome steps and traverse stone-composed terrains.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 2","pages":"495 - 503"},"PeriodicalIF":0.8,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147937730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhancing jumping robot performance through arm swing mechanisms","authors":"Cong Yan, Hinata Kato, Hiroto Ikeda, Yanqiu Zheng, Fumihiko Asano, Isao Tokuda","doi":"10.1007/s10015-025-01087-1","DOIUrl":"10.1007/s10015-025-01087-1","url":null,"abstract":"<div><p>This paper investigates the contribution of arm swing mechanisms to jumping robot performance through mathematical modeling, numerical simulation, and experimental validation. While extensive research has demonstrated the significance of arm swing in human and animal jumping biomechanics, this feature remains underutilized in robotic systems. We address three key questions: how coordinated arm swing affects horizontal jumping distance, what optimal arm swing parameters maximize performance, and how these parameters interact with other jumping variables. Our mathematical model incorporating arm dynamics reveals that optimized arm swing can enhance horizontal jumping distance by up to 35% compared to restricted arm configurations. Parametric analysis identifies optimal ranges for key variables: initial body angles of 0.3–0.65 rad, shorter arm swing durations, and specific arm swing amplitudes that do not necessarily correspond to maximum possible ranges. Experimental validation with our physical prototype achieved a 10% improvement in jumping distance, demonstrating the practical feasibility of this approach despite real-world constraints. These findings advance our understanding of arm-assisted jumping mechanisms and establish design principles for developing legged robots with extended mobility in critical environments.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 1","pages":"119 - 129"},"PeriodicalIF":0.8,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ViT-XAI: vision transformer and XAI enable robust detection and cause localization in swarm anomalies","authors":"Yohei Fukuyama, Masao Kubo, Hiroshi Sato","doi":"10.1007/s10015-025-01084-4","DOIUrl":"10.1007/s10015-025-01084-4","url":null,"abstract":"<div><p>While detecting a decline in collective performance is often straightforward, localizing the root cause can be significantly more challenging—particularly in systems characterized by dynamic relationships and complex interdependencies. To address this challenge, several studies have attempted to utilize explainable AI (XAI) techniques to localize causative agents. However, these approaches have not achieved sufficient accuracy in root-cause localization. This study proposes a method that integrates the Vision Transformer (ViT) with Gradient Self-Attention Maps (Grad-SAM)—an XAI technique—to localize anomalous agents within a swarm system. To evaluate the effectiveness of the proposed approach, we conduct comparative experiments against conventional convolutional neural networks (CNNs) combined with Gradient-weighted Class Activation Mapping (Grad-CAM), using the Boid model as the swarm simulation environment. Our comparative experiments against CNN/Grad-CAM using the Boid model revealed that anomaly detection and cause localization are a dual challenge with different requirements for model architecture. While CNNs demonstrated superiority in anomaly detection, particularly in scenarios with rare anomalies, ViT showed a clear advantage in cause localization. Specifically, ViT’s Grad-SAM generates higher-resolution and more stable saliency maps than Grad-CAM, thereby achieving high robustness with minimal performance degradation under a practical fixed-threshold setting. Furthermore, it outperformed CNNs under more complex situations involving mixed anomalies and background noise, quantitatively demonstrating that the proposed method can be a more practical and reliable technique for cause localization.</p></div>","PeriodicalId":46050,"journal":{"name":"Artificial Life and Robotics","volume":"31 1","pages":"130 - 148"},"PeriodicalIF":0.8,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}