Longest-running robot sumo tournament

The longest-running robot sumo contest is the All Japan Robot-Sumo Tournament, which has been hosted by Japanese technology firm Fujisoft every year since March 1990. The finale of the most recent edition of the event was held on 7–8 December 2024.

Robot sumo is a contest loosely based on the traditional Japanese sport of Sumo. The "ring" is a 1.54-metre-diameter (5-foot) circular platform, and the "wrestlers" are small robots measuring 20 x 20 centimetres (7.8 x 7.8 inches). To win, a robot must push the other robot out of the ring, or allow the other robot to fall out of the ring by accident.

Robot sumo differs from western robot contests in two key ways. The first is that the aim is not to damage or destroy the opposing robot (all entrants must be confirmed as "harmless" before the event). The second is that the robots are all autonomous, meaning that the bouts take place at lightning speed (typically ending within a few seconds). Creativity and adversarial design is very much encouraged, with robots often sporting features designed purely to confuse the opponent's AI – such as fold-out panels, fast-waving flags and deployable tripwires.

The sport of robot sumo was developed for the All-Japan event, with rules devised by Fujisoft founder Hiroshi Nozawa in collaboration with students and faculty from Waseda University and the Shibaura Institute of Technology (all Japan). The first tournament took place in August 1989, but this was only a test event, designed to make sure the rules worked. The first proper edition of the All-Japan Robot-Sumo Tournament took place in March 1990.

The first robot sumo tournament proved popular, and within a few years similar events were being held in North America and Europe. Today, robot sumo is an international sport, drawing teams from high schools, universities and even corporate robotics labs.