Perth-based Fastbrick Robotics and US-based construction machinery giant Caterpillar have extended their collaboration on the development of Australia's one-armed robot bricklayer.

The deal extends the term of the Memorandum of Understanding signed 12 months ago. Caterpillar, through a wholly owned subsidiary, then invested $2.6 million in Fastbrick Robotics.

Caterpillar now has the option to buy $13.5 million in shares at $0.24 until the end of January 2019. A short time ago, Fastbrick shares were up 2.7% to $0.185. 

Fastbrick CEO Mike Pivac says he's pleased at the continuing relationship with Caterpillar.

"Now that we have completed assembly and commenced commissioning of the Hadrian X, we are looking forward to demonstrating the operational capabilities and potential," Pivac said.

In the original deal, Fastbrick Robotics agreed to deal exclusively with Caterpillar for the development and potential commercialisation of the bricklaying technology. 

Fastbrick is currently testing a commercial version of its robot bricklaying machine, Hadrian X, which will cost about $2 million when it goes into full production in 2019. 

The Hadrian X requires minimal human interaction and works day and night, laying up to 1000 bricks an hour - about the output of two human bricklayers for a day.

The commercial version of the one-armed bricklaying robot is now in the testing phase.