Special Issue on Real World Robot Challenge in Tsukuba – Technology for the Coexistence with Human Beings –
Authors: Takita Yoshihiro , Yuta Shin’ichi , Tsubouchi Takashi , Ozaki Koichi 
Published: April 2016

Robotics researchers appear to have shifted their focus since the Great East Japan Earthquake. Despite a large-scale national R&D project on Advanced Robots for Hazardous Environments for 8 years from 1983, the technology has not been put to use effectively following the Great Hanshin Earthquake and researchers are starting to look more closely at applications enabling robots to replace human beings, e.g., by rescuing victims of earthquake and flood disasters. A good example is Quince and the remote-controlled heavy equipment used to handle the pyroclastic flow at Unzen volcano in 1991 and then mobilized at the Fukushima Daiichi nuclear power plant following the Great East Japan Earthquake and tsunami in 2011. Robotics researchers of the past only used to describe their dream proposals when asked what robots could accomplish. Since the 2011 disaster event, however, it has become clear that the issues we should be looking at are those of developing robots that are practical and useful. If we are asked what role the real-world competition Tsukuba Challenge plays in this context, would first recommend that those who hope to take part visit the actual site and see for themselves what they must do to field a winning robot. The Tsukuba Challenge site includes public thoroughfares traversed by pedestrians and cyclists. Although there are no cars or motorcycles on these paths, almost anything can happen. From hot summer until cooler fall when the official run is held daily temperature, rain, wind and typhoons, and trees – all of which must be detected for navigation – undergo many changes. These changes require that robots navigate accurately in this real-world environment. In general, robotics research papers are accepted for publication if robots can navigate as planned in a restricted and fixed mobile environment even if they can do so only once. In the Tsukuba Challenge, however, many things can go wrong and robot maneuvers can become unstable or even nonmobile, regardless of successful navigation in laboratory settings. There is no space here to discuss all possible factors, but the established navigation method by one paper is not always successful and responsible in the actual Tsukuba Challenge environment. Robots historically came to be as devices operated by human beings, but those taking part in the Challenge must be controlled by computers instead of human operators. This means that it must be confirmed that robots can operate as required in experiments meeting various conditions. Teams may conduct ten or so trial runs a year on the actual route so that their systems can be adequately adjusted and modified. The total process that competing in the Tsukuba Challenge requires also has an educational effect in grooming new talent in robotics. The Challenge differs from the DARPA Grand Challenge and Urban Challenge, held from 2004 to 2007, in the size – robots must not be too big and must not appear threatening – and the need to take the presence of human beings into consideration. Although the task from 2007 to 2012 had been only to navigate a preset route and reach a final goal, still the percentage of successful runs has declined. From 2013 on, another task has been added – that of locating specific persons (search targets) within given areas – to encourage the use of advanced technology in realizing useful robots. Those interested may see the results on the Tsukuba Challenge website as follow: http://www.tsukubachallenge.jp/tc2013. The selection of articles for this special issue emphasized the following criteria: 1) For robots successfully completing required tasks, describing and discussing the superiority of the control technology and results. 2) For unsuccessful robots, clearly analyzing how the actual run differed from researchers’ expectations and pinpointing the underlying causes of failure. The submitted papers describe technologies that have enabled robots to navigate in spaces shared with human beings, and we hope that a study of these papers will spur readers to accelerate advances in autonomous mobile robots.