The Tsukuba Challenge is an open experiment of autonomous mobile robots in the real world. In its third stage since 2018, it is now to be held on a new course that starts at the Tsukuba City Hall. New tasks that require functions expected for autonomous travel in the real world have now been added, including passing checkpoints announced a day before the event, starting two vehicles simultaneously, traveling in an unmeasured environment, and strictly observing stop lines in the course. Also, in the spirit of the Tsukuba Challenge, the Nakanoshima Challenge, an open demonstration experiment project, has been held in the city of Osaka since 2018. As the only event in which autonomous mobile robots travel in the urban area of Osaka, the Nakanoshima Challenge is expected to identify new issues peculiar to autonomous navigation in real urban environments and to find solutions to them.

This special issue includes a review paper on the Tsukuba Challenge, four research papers on the results of experiments done in the Tsukuba Challenge, four research papers related to the Nakanoshima Challenge, and three development reports. This special issue provides its readers with the frontline issues and the current status of development of autonomous mobile robots in real-world environments. We hope that the innovative efforts presented in this special issue will contribute to the development of science and industry.