In recent years, machine-learning applications have been rapidly expanding in the fields of robotics and swarm systems, including multi-agent systems. Swarm systems were developed in the field of robotics as a kind of distributed autonomous robotic systems, imbibing the concepts of the emergent methodology for extremely redundant systems. They typically consist of homogeneous autonomous robots, which resemble living animals that build swarms. Machine-learning techniques such as deep learning have played a remarkable role in controlling robotic behaviors in the real world or multi-agents in the simulation environment.

In this special issue, we highlight five interesting papers that cover topics ranging from the analysis of the relationship between the congestion among autonomous robots and the task performances, to the decision making process among multiple autonomous agents.

We thank the authors and reviewers of the papers and hope that this special issue encourages readers to explore recent topics and future studies in machine-learning applications for robotics and swarm systems.

Control engineering and sensing engineering improve productivity and save resources and energy in industry, and they are also deeply related to the solving greater societal, economic, and environmental problems. Control engineering and sensing engineering have become dynamic forces that enrich various phases of life through interdisciplinary or cross-sectional study. Furthermore, in recent years, due to the development of information technology, as symbolized by terms such as “big data” or “AI,” “sensing and control at a higher level” has become possible, premised by big data processing that is faster by orders of magnitude than conventional data processing. All this has increased the importance of control engineering and sensing engineering.

In response to the development of the fields of control engineering and sensing engineering associated with the advance of the “information society,” education in these fields has also needed to be enhanced. On the national scale, the Ministry of Education, Culture, Sports, Science and Technology will introduce Japanese elementary school computational thinking education into elementary school in fiscal year 2020, and the new Courses of Study for High School Information Education in fiscal year 2022. At the same time, individual companies, educational institutions, etc. have also been experimenting with various forms of education in control engineering and sensing engineering. During these changing times, the most advanced studies related to the development of instruction and evaluation methods for educational materials on control engineering, sensing engineering, and control technology have been collected, and the present special issue was planned.

This special issue is a collection of practical papers related to measurement and control education, including one paper on Model-Based Development education in a company and eight papers on education in an educational institution. These eight papers include two on education using a robot contest in a university, one on introducing measurement and control engineering education in a national institute of technology college, three on introducing it in a junior high school, and two on introducing it in an elementary school.

We hope that this special issue serves to support the readers’ future efforts in control engineering and sensing engineering education, and we thank the authors and reviewers of the papers.

Intelligent mobile robots need self-localization, map generation, and the ability to explore unknown environments autonomously. Probabilistic processing can be applied to overcome the problems of movement uncertainties and measurement errors. Probabilistic robotics and simultaneous localization and mapping (SLAM) technologies are therefore strongly related, and they have been the focus of many studies. As more and more practical applications are found for intelligent mobile robots, such as for autonomous driving and cleaning, the applicability of these techniques has been increasing.

In this special issue, we provide a wide variety of very interesting papers ranging from studies and developments in applied SLAM technologies to fundamental theories for SLAM. There are five academic papers, one each on the following topics: first visit navigation, controls for following rescue clues, indoor localization using magnetic field maps, a new solution for self-localization using downhill simplex method, and object detection for long-term map management through image-based learning. In addition, in the next number, there will be a review paper by Tsukuba University’s Prof. Tsubouchi, who is famous for the Tsukuba Challenge and research related to mobile robotics.

We editors hope this special issue will help readers to develop mobile robots and use SLAM technologies and probabilistic approaches to produce successful applications.

We are pleased to announce that the 11th Journal of Robotics and Mechatronics Best Paper Award (JRM Best Paper Award 2018) has been decided by the JRM editorial committee.

The following paper won the JRM Best Paper Award 2018, severely selected from among all 97 papers published in Vol.29 (2017). The Best Paper Award ceremony was held in Gakushi-Kaikan, Tokyo, Japan, on December 17, 2018, attended by the authors and JRM editorial committee members who took part in the selection process. The award winner will also be announced on the JRM website and was given a certificate and a nearly US$1,000 honorarium.

JRM Best Paper Award 2018

Title: Spherical Video Stabilization by Estimating Rotation from Dense Optical Flow Fields

Authors: Sarthak Pathak, Alessandro Moro, Hiromitsu Fujii, Atsushi Yamashita, and Hajime Asama

J. Robot. Mechatron., Vol.29 No.3, pp. 566-579, June 2017

We are pleased to announce that Professor Toshio Fukuda, the second Editor-in-Chief of JRM, has been elected as 2019 IEEE (The Institute of Electrical and Electronics Engineers) President-Elect (2020 President), and Professor Kazuhiro Kosuge, former Deputy Editor-in-Chief of JRM, has been elected as 2019 IEEE Technical Activities Vice President-Elect (2020 IEEE TA Vice President). Congratulations! They have devoted themselves to the development of the Journal of Robotics and Mechatronics.

Prof. Fukuda and Prof. Kosuge will serve as IEEE President and IEEE Technical Activities Vice President, respectively, in 2020. We look forward to their continued success in the future.

The Journal of Robotics and Mechatronics (JRM) is celebrating its thirtieth anniversary since its establishment in June 1989. As the founding Editorin-Chief, I would like to express my heartfelt gratitude to all the people and organizations that have helped in making JRM a success.

Although founded in Japan, our primary objective was to provide a global platform for facilitating the publication of research work comprising outstanding results and novel information regarding robotics and mechatronics. Encouraged by the emphatic support received from several prominent researchers and engineers in numerous countries, including the United States of America and European countries, our team decided to launch JRM.

It is now our aim to develop JRM into a highly ranked international journal. I sincerely hope that more academicians and engineers will participate in JRM’s development process by contributing their valuable feedback, research results, and technical information.

Kazuo Yamafuji

As its first issue was published in 1989, the Journal of Robotics and Mechatronics (JRM) has been in existence for 30 years. Its entrance into its fourth decade this year coincides with the change in the name of the Japanese era, marking a joyous milestone. During the three decades since the JRM was founded, much progress has been made in the areas covered by it, and these areas have expanded to encompass very diverse fields.

It was around 1988, when I was at the Institute of Physical and Chemical Research (RIKEN), that I received a letter from Kazuo Yamafuji, later the first Editor-in-Chief of the editorial board, stressing the need for a journal such as the JRM. I gladly joined the committee to discuss its publication, and after attending a few meetings, I witnessed its successful launch. I served as the Deputy Editorin- Chief of the editorial board.

Prior to that time, robots had mainly inhabited the world of science fiction and were not recognized as a technological subject within an academic discipline, except in the field of factory automation. The robots that did exist were usually thought of in a recreational context. Meanwhile, the general trend in academic and engineering disciplines was toward specialization and segmentation, with engineering splitting into mechanical, electronic, and other branches, each becoming progressively isolated from the others. Yet, those working in areas related to product development and manufacturing were expected not only to have knowledge of several engineering disciplines but also to integrate them in applying them. These engineers/technicians were treated as unoriginal emulators existing outside of the conventional systematized and specialized fields, and they were regarded as heretics with no suitable field to represent in making presentations at professional or academic conferences. Even if they hoped to publicize their research findings, there were no professional/academic journals that could provide a proper peer review.

It was under these circumstances that the word “mechatronics” was coined in Japan, where it gained currency and also came to earn some recognition in the English-speaking world. Founded at just the right time, the JRM contributed to the spread and growth of mechatronics. Subsequently, the term came to denote, in addition to its original meaning of the integration of mechanics, electronics, and information science, the fusion of widely diverse technologies in human sciences, social sciences, and medicine. In this context, it is my ardent hope that the JRM, in its fourth decade, will increase its presence as a journal that remains unconstrained by conventional specialties and accepts papers and articles that deal with as-yet-unestablished areas that cross multiple fields, contributing to their dissemination.

At the time the JRM was founded, Keiji Hayashi was president of Fuji Technology Press Ltd., the organization that annually presents the JRM Best Paper Award. Unfortunately, he passed away at the age of 90 on March 19, 2017, before he could see the JRM’s 30th anniversary. Some time before he passed, he telephoned me to say that he hoped the JRM would continue to widely encompass and nurture as-yet-unknown areas. On this occasion of the 30th anniversary of the JRM, I wish to pay my respects and express my deep gratitude to Mr. Hayashi, who provided his own funds to support its publication. I pray that his soul may rest in peace, and I sincerely hope that the JRM continues to make great strides in the coming decade.

Masanori Idesawa

I congratulate the Journal of Robotics and Mechatronics (JRM) on the publication of its 30th anniversary issue. As one of JRM’s past Editors-in- Chief, I am extremely pleased and proud of this great achievement. JRM was the first journal dealing with robotics and mechatronics in the world when it was launched thirty years ago. Since then, the journal has made a strong impact on the robotics and mechatronics field. It has been hard for the journal to provide high quality issues for so many years. I would like to sincerely express my great respect to Mr. Hayashi, founder and former president of Fuji Technology Press Ltd.; former Editors-in-Chief Prof. Yamafuji, Prof. Fukuda, and Prof. Kaneko; the current Editor-in-Chief, Prof. Takita; and our colleagues, including the editorial board and editorial staff, for their hard work. I would also like to express my great appreciation to all the authors, reviewers, and readers for their superb contributions. This grand thirty-year achievement could not have been attained without all their contributions.

I was Editor-in-Chief for seven years ‒ volumes 19 through 25 ‒ beginning in January 2007. I enjoyed my role as Editor-in-Chief, since many young, talented researchers and engineers took part in the editorial process, and I could discuss with them how we would achieve a high-quality journal. I remember clearly how hard they worked to edit superlative volumes by proposing and organizing special issues with up-to-date topics. During that period, we had the good fortune of collaborating with the Japan Society of Mechanical Engineers (JSME). They supported us in providing committee members for our editorial board, and in collecting and reviewing the many excellent papers. I would also express my thanks to JSME for their abundant and generous support. Because of it, JRM achieved a high reputation and contributed to both academia and industry.

Today there are many relevant journals in the world. Competing with them and producing an even higher quality journal than ever before are the most critical issues in the next step of JRM’s advancement. I applaud the current editorial board members and staff and expect JRM to become the very top journal in the field. In conclusion, I hope I can celebrate with you ten and twenty years from now, again and again!

Tatsuo Arai

Congratulations to the Journal of Robotics and Mechatronics (JRM) on its 30th anniversary. I would like to thank all authors and readers who have contributed to the JRM through 30 years.

The JRM started as an English-language journal published to provide articles on robot technologies to the world from Japan. It has been jointly edited by the Robotics and Mechatronics Division (RMD) of the Japan Society of Mechanical Engineers (JSME) and Fuji Technology Press Ltd. Five years ago, when the English-language journal of the JSME was reorganized, the JRM also underwent some changes, and it has since been issued under the editorial direction of Fuji Technology Press Ltd. Immediately after the reorganization, beginning with Vol.26, I was appointed Editor-in-Chief. Now, as five years have passed, the next Editor-in-Chief will take over from Vol.31. Over these five years, the number of submissions and their quality have been our major concern, as we have been seeking to register the JRM with the Science Citation Index (SCI). To achieve this goal, we have published special issues on the robot technologies required as the field has progressed as well as on the mechatronics technologies that underlie them.

The JRM plans to continue providing the world with information on robot technologies, so please keep reading it and submitting your articles to it on a regular basis.

Yoshihiro Takita

A robot is a system integrated with many elements such as actuators, sensors, computers, and mechanical components. Currently, progress in the field of artificial intelligence induced by tremendous improvements in computer processing capabilities has enabled robots to behave in a more sophisticated manner, which is drawing considerable attention. On the other hand, the mechanism that directly produces robot movements and mechanical work sometimes brings out some competencies that cannot be provided solely by computer control that relies on sensor feedback.

This special issue on “Integrated Knowledge on Innovative Robot Mechanisms” aims to introduce a knowledge system for robot mechanisms that bring forth useful and innovative functions and values.

The editors hope that the studies discussed in this special issue will help in the realization and further improvement of the mechanical functions of robots in the real world.

Human work and life support are areas that provide practical applications for robotics and mechatronics technology. There is great expectation from the industry in these fields, and research and development efforts have been actively undertaken with great social impact. To support human work and life accurately, we must understand the complicated sensory, nervous, and motor control systems that enable design and development of appropriate assistive devices.

Therefore, in this mini special issue, we focus on robotics and mechatronics for human sensing, modeling, and augmentation.

The editor hopes that this special issue will attract researchers’ interest and contribute to further developments in this field.

Tsukuba Challenge, which started in 2007, has contributed to the development of novel control technologies for autonomous navigation. The second stage of this challenge was completed in 2017, and now, the time is ripe for exploring new ideas and avenues. This is the fifth Special Issue on Real World Robot Challenge in Tsukuba, and it seems that the technological elements required for autonomous navigation are almost complete. However, it is obvious that such navigation capabilities are still at a significantly lower level of development compared to human capabilities. The need for automatic and self-driving vehicles has increased rapidly in recent years; many companies and researchers have been making great strides in research and development in the field of automatic driving. The Tsukuba Challenge pursues and encourages both student education and advanced research and development, focusing on automatic driving as an application technology. The essential capabilities required for a robot to reach the designated goal in the Tsukuba Challenge are self-localization and obstacles avoidance, and many studies have been conducted on these features. To complete the designated task, unification of these technologies and other qualities such as searching for persons, traveling on crosswalks, and recognizing traffic signals is required.

This special issue concentrates on control technologies of autonomous mobile robots and expects to contribute toward future studies and development in this field.

Currently, drones have reached the stage of practical application, business, and social contribution from the stage of research and development. In fact, drones are now opening up a new market not only in the field of aerial photography and agricultural chemical spraying, which had traditionally been on the market, but also in the field of surveying. Furthermore, new markets are expected to be formed within several years in the field of infrastructure inspection and logistics.

Under these circumstances, research on drone application is becoming significant, along with research on drone design and control, which have been done conventionally. However, there are still only a few studies and journals focusing not only on drone development and design but also drone application. Therefore, in this special issue, we invited papers with comprehensive contents, including research focusing on drone application, and created a space to present cutting-edge research results.

By reading this special issue, we hope that readers will understand the latest information about the applications of drones and their cutting-edge technology. Furthermore, we also hope that readers will be able to proactively promote the use of drones in their own research and work, based on the information obtained from this special issue.

The importance of primary industries, agriculture, forestry and fisheries, is obvious and needless to mention, however, the reduction of the working population and the aging problem make the situation of primary industry more sever. To compensate for the issues, the advanced technology in robotics has attracted attentions and expected the contributions in terms of productivity, cost effectiveness, pesticide-less, monitoring of the growth and harvesting, etc. Recently, robotic technologies are gradually being used in primary industry and their application area will expand more in the near future. This special issue’s objectives include collecting recent advances, automation, mechanization, research trends and their applications in agriculture, forestry and fisheries to promote a deeper understanding of major conceptual and technical challenges and facilitate spreading of recent breakthroughs in primary industries, and contribute to the enhancement of the quality of agricultural, forestry and fisheries robots by introducing the state-of-the-art in sensing, mobility, manipulation and related technologies.

In this special issue, twelve papers are included. The first paper by Noguchi is the survey paper of the state-of-the-art in the agricultural vehicle type robots and discusses the future scope of agriculture with robotics. The next three papers are on tomato-monitoring system, and Fukui et al. propose a tomato fruit volume estimation method using saliency-based image processing and point cloud and clustering technology, Yoshida et al. do the cutting point identification for tomato-harvesting using a RGBD sensor and evaluate in the real farm experiments, and Fujinaga et al. present an image mosaicking method of tomato yard based on the infrared images and color images of tomato-clusters in the large green house. The fifth paper by Sori et al. reports a paddy weeding robot in wet-rice field to realize the pesticide-free produce of rice, and the sixth paper by Shigeta et al. is about an image processing system to measure cow’s BCS (Body Condition Score) automatically before milking cows and analyzes the two months data by CNN (Convolutional Neural Network). The seventh paper by Inoue et al. reports on an upper-limb power assist robot with a single actuator to reduce the weight and cost. The assist machine supports the shoulder and elbow movements for viticulture operations and upper-limb holding for load transport tasks. In the next paper, Tominaga et al. show an autonomous robotic system to move between the trees without damaging them and to cut the weeds in the forest for the forest industry. The last four papers are for the fishery industry, and Komeyama et al. propose a methods for monitoring the size of fish, red sea bream (RSB) aquaculture by developing a stereo vision system to avoid the risks of physical injury and mental stress to the fish. Nishida et al. report on a hovering type underwater robot to measure seafloor for monitoring marine resources whose sensor can be replaced depending on missions as the open hardware system. Yasukawa et al. propose a vision system for an autonomous underwater robot with a benthos sampling function, especially, sampling-autonomous underwater vehicles (SAUVs) to achieve a new sampling mission. The last paper by Han et al. is for gait planning and simulation analysis of an amphibious quadruped robot in the field of fisheries and aquaculture.

We hope that this special issue can contributes to find solutions in primary industries, agriculture, forestry and fisheries.

This is the 2nd special issue on education of robotics & mechatronics on Journal Robotics & Mechatronics. Six years have passed since the previous issue (Vol.23, No.5) was published. This special issue includes nine research papers and two review papers, among which four research papers focus on the utilization of robots in STEM education, which has been spotlighted recently, and programming education for the young. Five research papers propose educational methods with novel, unprecedented ideas, and the two review papers overview technology education in Japan. The review papers focus on STEM education that utilizes a variety of manufacturing methods that have become familiar, and they present a variety of efforts being made in STEM education, programming education in today’s Japan.

At present, Germany’s Industry 4.0, Japan’s Robot Strategy, and many other initiatives are being undertaken in the world to promote development technology as it relates to production automation and efficiency. The development of human resources that are capable of working with these new technologies has also gathered public attention, with each educational institution now required to enrich its STEM education. As part of this movement, in 2020, programming education will be added to Japan’s elementary school curriculum, with robots being the focus of the education. This situation indicates that the importance of educational robotics is likely to continue to increase in the future. We expect that this special issue will contribute to the development of educational robotics communities and of human resources that are well prepared in the field of robotics.

We would like to express our sincere gratitude to all contributors and the reviewers for making this special issue possible.

Many missions have been launched to explore the Moon, Mars, asteroids, and comets, and many researchers are studying and developing lunar and planetary rovers for unmanned planet exploration, and further cooperative missions targeting human lunar exploration are under discussion. A key technology in these missions and orbital services is space robotics, including Al and automation. Space robotics is expected to support external vehicular activities (EVA) and internal vehicular activities (IVA), which will include constructing, repairing, and maintaining orbiting satellites and space structures.

This special issue presents the updated mission results and advanced research activities of space organizations, institutes, and universities, although it does not include all. We hope that this special issue will be useful to readers as an introduction to advanced space robotics in Japan, and that more robotics and Al researchers and engineers will become interested in space robotics and participate in space missions.

We thank the authors for their fine contributions and the reviewers for their generous contributions of time and effort. In closing, we also thank the Editorial Board of the Journal of Robotics and Mechatronics for helping to make this issue possible.

In this fourth of the “Special Issues on Real World Robot Challenge in Tsukuba,” we feature the control technology of autonomous robots. There is no guarantee that it will operate perfectly in a real-world environment even with the method already revealed. Participating robots in Tsukuba Challenge are required to carry out the assigned tasks under the prevailing weather conditions on the day of the events. Robots avoid oncoming pedestrians and obstacles in their path. In order to share the novel technology of the autonomous control method, this special issue presents a summary of the results of robots that participated in past Tsukuba Challenges.

It is only thanks to the ongoing efforts of the organizers of Tsukuba Challenge and the enthusiasm on the part of the participants that we are able to present an issue such as this, and we are truly thankful to them. We also wish to thank the authors who submitted papers and articles for this issue, as well as our reviewers.

Legged locomotion, including walking, running, turning, and jumping, strongly depends on the dynamics and biological characteristics of the body involved. Gait patterns and energy efficiency, for example, are known to be greatly affected by not only travel velocity and ground contact conditions but also by body configuration, such as joint stiffness and coordination, as well as foot sole shape. To understand legged locomotion principles, we must clarify how the body’s dynamic and biological characteristics affect locomotion. Effort must also be made to incorporate these characteristics inventively to improve locomotion performance, such as robustness, adaptability, and efficiency, which further refine the legged locomotion. This special issue on “Dynamically and Biologically Inspired Legged Locomotion,” studies on legged locomotion based on dynamic and biological characteristics, covers a wide range of themes, such as a rimless wheel, a design method for a biped based on passive dynamic walking, the analysis of biped locomotion based on passive dynamic walking and dynamically inspired walking, an analysis of gait generation for a triped robot, and quadruped locomotion with a flexible trunk. Since there are interesting papers on legged robots with different numbers of legs, we basically organized the papers based on the number of legs. Studies on “Dynamically and Biologically Inspired Legged Locomotion” are expected to not only realize and improve legged locomotion as engineering, but also to reveal the locomotion mechanism of various creatures as science.

As life expectancy has become longer, the number of those who have some handicaps or diseases as well as the families, caregivers and medical staff who support them has been also increasing. While modern medical science has rapidly advanced by adopting the innovation of engineering technology especially in the fields of mechanical and electric engineering, the support for nursing, care and assistance by making use of engineering technology has only just begun. This special issue on “Nursing Engineering,” a combination of nursing and engineering, covers a wide range of themes such as the measuring equipment characterized by non-invasiveness, unconstraint and real-time for the purpose of helping patients and healthcare professionals and the development of the related technology; the development of the technology for the equipment to support recuperation, rehabilitation or convalescent life of patients; and active introduction of information technology and user interface technique into nursing study and its case studies. “Nursing Engineering” is expected to play increasingly important role to support medical treatment and everyday life of patients along with the highly professional medical staff by making practical use of the technology of robotics and mechatronics and incorporating rehabilitation science, welfare engineering and technology for assistance.

Robot audition, the ability of a robot to listen to several things at once with its own “ears,” is crucial to the improvement of interactions and symbiosis between humans and robots. Since robot audition was originally proposed and has been pioneered by Japanese research groups, this special issue on robot audition technologies of the Journal of Robotics and Mechatronics covers a wide collection of advanced topics studied mainly in Japan. Specifically, two consecutive JSPS Grants-in-Aid for Scientific Research (S) on robot audition (PI: Hiroshi G. Okuno) from 2007 to 2017, JST Japan-France Research Cooperative Program on binaural listening for humanoids (PI: Hiroshi G. Okuno and Patrick Danès) from 2009 to 2013, and the ImPACT Tough Robotics Challenge (PM: Prof. Satoshi Tadokoro) on extreme audition for search and rescue robots since 2015 have contributed to the promotion of robot audition research, and most of the papers in this issue are the outcome of these projects. Robot audition was surveyed in the special issue on robot audition in the Journal of Robotic Society of Japan, Vol.28, No.1 (2011) and in our IEEE ICASSP-2015 paper. This issue covers the most recent topics in robot audition, except for human-robot interactions, which was covered by many papers appearing in Advanced Robotics as well as other journals and international conferences, including IEEE IROS.   This issue consists of twenty-three papers accepted through peer reviews. They are classified into four categories: signal processing, music and pet robots, search and rescue robots, and monitoring animal acoustics in natural habitats.   In signal processing for robot audition, Nakadai, Okuno, et al. report on HARK open source software for robot audition, Takeda, et al. develop noise-robust MUSIC-sound source localization (SSL), and Yalta, et al. use deep learning for SSL. Odo, et al. develop active SSL by moving artificial pinnae, and Youssef, et al. propose binaural SSL for an immobile or mobile talker. Suzuki, Otsuka, et al. evaluate the influence of six impulse-response-measuring signals on MUSIC-based SSL, Sekiguchi, et al. give an optimal allocation of distributed microphone arrays for sound source separation, and Tanabe, et al. develop 3D SSL by using a microphone array and LiDAR. Nakadai and Koiwa present audio-visual automatic speech recognition, and Nakadai, Tezuka, et al. suppress ego-noise, that is, noise generated by the robot itself.   In music and pet robots, Ohkita, et al. propose audio-visual beat tracking for a robot to dance with a human dancer, and Tomo, et al. develop a robot that operates a wayang puppet, an Indonesian world cultural heritage, by recognizing emotion in Gamelan music. Suzuki, Takahashi, et al. develop a pet robot that approaches a sound source. In search and rescue robots, Hoshiba, et al. implement real-time SSL with a microphone array installed on a multicopter UAV, and Ishiki, et al. design a microphone array for multicopters. Ohata, et al. detect a sound source with a multicopter microphone array, and Sugiyama, et al. identify detected acoustic events through a combination of signal processing and deep learning. Bando, et al. enhance the human-voice online and offline for a hose-shaped rescue robot with a microphone array.   In monitoring animal acoustics in natural habitats, Suzuki, Matsubayashi, et al. design and implement HARKBird, Matsubayashi, et al. report on the experience of monitoring birds with HARKBird, and Kojima, et al. use a spatial-cue-based probabilistic model to analyze the songs of birds singing in their natural habitat. Aihara, et al. analyze a chorus of frogs with dozens of sound-to-light conversion device Firefly, the design and analysis of which is reported on by Mizumoto, et al.   The editors and authors hope that this special issue will promote the further evolution of robot audition technologies in a diversity of applications.