"I watched Battlebots when I was a student, so when I found out that China also has robot fights, I immediately decided to take part," says Yang Jie, who teamed up with his 12-year-old son to join the Beijing event.

Yang, an engineer who majored in machine manufacturing and automation, created robots for the team, while his son, who is just out of elementary school, controlled the robots.

Typically, there are around 20 to 40 teams in a competition, mostly robot fans and university students and, like boxing, the robots compete in different weight classes, ranging from 13.6 kg to 110 kg.

"A 13.6 kg robot can take a month to build, and larger ones can take up to three months," says Yang.

"We choose the materials and do the designing ourselves."

His robot carries a hammer made from a plastic pipe with a metal joint at the tip as its weapon.

The duo has participated in tournaments in several Chinese cities since last year and was ranked in the top four at one of the events.

"In the past, there were two to three events per year," says Yang, "but now, there are that many held every month."

Lyu Junjie, another contestant, started building fighter robots in 2016.

"Back then, it was just some of my friends building robots, and the designs were quite similar," says Lyu.

"But now the community has grown into thousands, with many more designs to learn from."

Lyu attributes the growth to publicity, funding and exchanges due to the emergence of reality TV shows like King of Bots.

Initially, robot fights were organized as events for university students in related majors to hone their skills and were not open to the public.

Speaking about King of Bots, Zhang Heng, vice-president of The Makers, which runs the show, says: "There is a robot culture in many countries, and we want to bring that to China."

Meanwhile, Zhang's company produced another show called This Is a Fighting Robot, which was broadcast on Chinese video site Youku in April.

The show, which invited celebrities to back teams, had more than 100 million views.

Separately, offline events have also become popular.

At the event during the robot conference, hundreds of spectators lined up to watch the fights. Many of them were parents and their children.

Li Wenxiong, who was waiting in line with his 8-year-old, says: "I think my son will enjoy watching robot fights. It's exciting to watch."

King of Bots' ambition goes beyond producing an entertainment show, as it has signed up top teams from the competition, and plans to run professional matches in Britain, the US and Australia.

And Zhang says: "We see robot fights as a high-tech sport, and we want to run it like a sports league in the future."

Xinhua