A University of New South Wales (UNSW) team of engineers and their robots have defended their RoboCup World Championship title in China, defeating a German team 3-1.

UNSW's five-robot squad defeated the University of Bremen and DFKI (German Research Centre for Artificial Intelligence) in Hefei, west of Shanghai, to win a second consecutive world title.

The teams were locked at 1-1 after the first of two 10 minute halves, but a late second-half goal sealed it for the Australians.

The final was contested using waist high robots on a nine-metre-long soccer field.

Team leader Sean Harris, a PhD student with UNSW's School of Computer Science and Engineering, said it was a close game.

"We only won 3-1, last year we won 4-1 in a more of a one-sided game."

Mr Harris said the UNSW robots had a speed advantage over their German opponents.

"The biggest advantage was our ability to walk faster than everyone else," he said.

"We were able to take off quicker and get to the ball faster, and that really proved the difference for us."

The team were not able to control the robots during the final match, instead relying on programming and software algorithms.

"We've been writing this code base since we started in RoboCup back in 1999," Mr Harris said.

UNSW robot kicks a ball in the RoboCup World Championships ( UNSW )

He said there had been a lot of hard work over many years.

"Everyone builds on the work of previous students and alumni who have participated," he said.

"We code things up and then every week at home we play practice games and [do] little training drills."

The rules for the tournament are changed each year, giving engineers and robots a fresh set of challenges.

Next year competitors will have to use a regular size children's soccer ball.

However, Mr Harris said it may be some time before the robots can imitate their human counterparts on the sporting field.

"Physical motion is very, very challenging," he said.

"We can walk fairly quickly [but] I don't see many robots that can run. Running is the next big step. [That is] a little while off I think."

The next RoboCup will be held in Leipzig, Germany.