Robot-sumo (Japanese: ロボット相撲) is an engineering and robotics competition in which two robots attempt to push each other out of a circular arena, in a similar fashion to the sport of sumo. The robots used in this competition are called "sumo robots", "sumobots" or simply "sumos".What is Robot-sumo in FSI All Japan Robot-Sumo Tournament
Competitions typically involve autonomously operated wheeled mobile robots. The engineering challenges are for the robot to find its opponent (usually accomplished with infrared or ultra-sonic sensors) and to push it out of the dohyō. A robot should also avoid leaving the arena, usually by means of a sensor that detects the edge. The most common mechanical design is to use a wedge with a blade at the front to lift the opposing robot and push it more easily.
Robot-Sumo originated in Japan in 1989 when FUJISOFT Inc. [jp] organized an experimental robot-sumo tournament, which would later be established as the All Japan Robot Sumo Tournament [jp](Japanese: 全日本ロボット相撲大会 zen'nippon robotto sumou taikai). Since 1998, FUJISOFT has collaborated with more than 30 countries, and robot-sumo has spread and has been one of the most popular robotics competitions in the world, such as in Europe, Mexico and Brazil, with a total of 80,000 people around the world actively developing sumo robots.
The All Japan Robot-Sumo Tournament has been hailed as the "World Robot-Sumo Championship". In August 2026, however, FUJISOFT announced that it would cease organizing the event, with the 2026 edition being the final tournament.
Robot-sumo competitions still hold amateur status, though high-performance competitions (events contested between technical students, universitarians and graduated engineers hobbyists) require highly complex engineering projects.
Robot-sumo is also often used as an educational tool of engineering, robotics and electronics for simpler protoypes in schools and undergraduate levels. Sumo robots design has also been the subject of studies and research of academic nature as well.
History Robot-Sumo began in Japan with the All Japan Robot Sumo Tournament [jp] organized by FUJISOFT Inc. [jp] for the first time in 1989 as an experimental tournament, with 33 participants. The first official edition was established in 1990, and, since then, this tournament has been held annually in Tokyo. The competition began with an idea from the president of FUJISOFT Inc., Hiroshi Nozawa, whose goal was to promote his company and recruit excellent human resources. But above all, it was because of his desire to give a dream to the younger people who are responsible for the future of his country, and because of the desire to create an environment to improve the quality of "Monozukuri" in Japan. Initially, Robot Sumo only included the class that would be later known as Mega Sumo or Sumo 3 kg class.
In 1992, the FUJISOFT tournament was held at the Ryōgoku Kokugikan, where the tournament is still held today. In 1998, the tournament had 2,929 participants.
Also in 1998, the first Robot-Sumo competition was held outside of Japan, at the ROBOlympics (later renamed RoboGames), one of the largest robotics events at the time, held in the USA. This event helped popularize sumo competitions around the world and led to the creation of categories derived from 3 kg class, such as Mini Sumo (500g class), LEGO Sumo, among others, which further popularized the category as a whole, leading to the emergence of many competitions around the world, such as in Mexico, Europe, and South America. The exact origin of those derived robot-sumo classes is uncertain, however there are footage of Mini Sumo RC from 2002 at the RoboGames.
In 2004, at the 15th edition of the All Japan Robot-Sumo Tournament, the tournament introduced the 10 kg class, but it would be discontinued in 2007.
In 2008, RoboCore organized the first official national robot-sumo tournament in Brazil as part of the expansion of the national robotics competition "Winter Challenge", originally a robot combat focused event mainly contested by universitarian teams from the country. In this competition, Sumo 3 kg Auto, Sumo 3 kg RC and Sumo LEGO classes were held. Until 2019, the Winter or Summer Challenge was the biggest robotics event in Brazil and Latin America, considered the "Brazilian National Robotics Championship" by many.
Also in 2008, with the increasing worldwide popularity of robot-sumo, FUJISOFT held for the first time an edition of the All Japan Robot-Sumo Tournament with international competitors, from United States, Mexico and Singapore. Since then, the All Japan became a world championship, with the participation of overseas competitors as “Overseas Representatives”.
In 2010, the Robochallenge, in Romania, hosted a robot-sumo event for the first time.
In 2013, FUJISOFT held the first official edition of the International Robot-Sumo Tournament (Japanese: 世界大会 sekai taikai), separating from the Japanese national All Japan competition (Japanese: 全国大会 zenkoku taikai), with only the best Japanese (champions, and later runners-up) advancing to the world tournament, with both tournaments being held in the same day, in sequence. In this edition, tournament champions or national representatives from Austria, USA, Baltic States (Estonia, Latvia and Lithuania), Turkey, Mexico and Ecuador participated as overseas representatives. The Auto tournament had 16 robots, and the RC tournament, 8 robots, in 2013.
Between 2013 and 2017, without a massive number of Japanese robots (and with a higher number of non-Japanese robots, with some editions reaching more than 100 robots in a single class), non-Japanese international competitors achieved greater results in the International Tournament. European teams achieved significant results in the 3 kg Auto class, including top places and championship titles. In 2017, the last edition of the International Robot-Sumo Tournament was marked by Mexican dominance in the Mega Sumo RC class, taking the first three positions and ahead of the Japanese champions.In 2018, FUJISOFT reunified the Japanese All Japan competition with the International Tournament into a single tournament, as it was before 2013, retaining the All Japan Robot-Sumo Tournament name and labeling the final stage as the "Grand Final". In 2019, the competition was in its 31st edition, and had the participation of more than 20 countries, 104 autonomous robots and 78 radio-controlled robots in the Grand Final. With the competition unified again, robots from Japan once again dominated the top positions of the competition in 2018 and 2019.
In 2019, FUJISOFT also organized the first Mini-Sumo event in Japan, as a test event (called pre-tournament) in All Japan, only for Auto category.
In 2020, due to the COVID-19 pandemic in Japan, the 2020 edition (32nd edition) of the All Japan Robot-Sumo Tournament was cancelled.
In Brazil, due to the COVID-19 pandemic, competitions were also canceled. In response, many teams began organizing remote competitions, in which participants controlled ready-made prototypes provided by the organization remotely through the internet. For the Robot Sumo category, the most popular was the Remote Mini Sumo RC class, in which participants controlled ready-made robots just like in a conventional competition, but remotely through the internet with a mobile phone application. These competitions attracted not only Brazilian competitors, but also international competitors such as Argentines and Indians.
In 2021 and 2022, FUJISOFT organized an alternative competition for the 32nd and 33rd editions remotely for high school competitors (Japanese: 高校学校 koukougakkou), which consisted of a sumo robot design contest.
In 2022, RoboCore from Brazil remodeled its main and largest robotics competition, the "Winter Challenge", into the "RoboCore Experience" (RCX), the largest robot combat event in Latin America. The competition hosts the Mega Sumo, Mini Sumo and LEGO Sumo tournaments, jointly with the Robot Combat, Line Follower, Robot Hockey, Robot Trekking, ArtBot and Robot Soccer competitions. The RoboCore Experience is held together with Campus Party Brazil. The 2023 RCX had 1330 registered competitors and almost 700 robots in all robotics categories.
In 2022, with the end of the COVID-19 pandemic, FUJISOFT once again organized the All Japan Robot-Sumo Tournament (34th edition), but only for local competitors. In the same event, a new pre-tournament for Mini Sumo class was organized by FUJISOFT.
In 2023, All Japan, in its 35th edition, returned qualifying participants from overseas competitions for Mega Sumo class, for the first time since 2019. This year, the Mini Sumo tournament was officially added to the All Japan, but only for Japanese competitors.
In 2024, the robot Senju, from the Sumozade-Era Robotics team from Turkey, became the first non-Japanese Mega Sumo champion of the All Japan Robot-Sumo Tournament since the reunification in 2018, winning in the Auto category. Also in 2024, the Mini Sumo of All Japan started qualifying overseas competitors as well. Brazilian teams achieved great success, making the Mini Sumo Auto final, and also taking 2nd and 3rd places in Mini Sumo RC in that year, with the first place being notably won by a Mexican team. .
In April 2025, FUJISOFT announced that they "will primarily concentrate on the 500g class robots and will reduce participation in the 3kg class for both international and domestic teams", shifting the focus of the All Japan Robot-Sumo Tournament 2025 edition from the Mega Sumo class to the Mini Sumo class. They also announced that "in the future, country representative invitations may not be sent; only teams recognized in official tournaments will qualify for the Grand Final". In June 2025, FUJISOFT announced that the 2025 edition will host the Mini Sumo as an official tournament, rather than a Pre-Tournament as it has been until last year.
In August 2026, FUJISOFT announced that it would end the tournament after the 38th edition, stating that it had fulfilled a certain role as a social contribution initiative based on its activities to date. The 38th edition, scheduled for 2026, will therefore be the final tournament.
Rules and Classes The principle of a robot-sumo fight consists of two robots competing to push the opponent out of the dohyō. The arena is usually painted with a main color with a contrasting color used to paint a line in the edge (usually, black as the main color and white as the border line color).
Robot-sumo is usually divided in Autonomous (Auto) category, for robots that operate autonomously, and Radio-controlled (RC) category, for robots operated by a person.
In general, the rules may vary in some details from tournament to tournament (arena specifications, starting positioning, handling of exceptions, ...) especially in tournaments of a more educational nature, held in educational institutions as a didactic activity. High level competitions tend to follow standardized rules, such as the rules from All Japan Robot Sumo Tournament [jp].