Robots used to clean Sydney Harbour Bridge

Painting the Sydney Harbour Bridge is no small undertaking: just one coat requires 30,000 litres of paint. So when the Roads and Maritime Service (RMS) needed to strip the bridge of its lead-based paint in order to repaint the bridge for the first time in its history, more than just a team of hard-working painters was required.

Two new members of the team of tradespeople who maintain the bridge could revolutionise the maintenance work - not just on the bridge, but on other large steel infrastructure around the world.

These new team members are two grit-blasting robots developed by the University of Technology, Sydney (UTS). Helping to strip paint from the steel girders, the robots can work unaided in unfamiliar and dangerous environments and can process new information.

They represent a new generation of ‘smart’ robots that could eventually be used in a range of industries, from maintenance and manufacture to aged care. The robots are the culmination of six years of development between UTS researchers and the RMS, which is responsible for the bridge.

Including the robots in the $20 million, two-year maintenance program was a huge undertaking, says UTS Manager for Innovation and Commercial Development Martin Lloyd.

“All credit to the RMS for allowing us to use this technology on what is one of the world’s most iconic bridges,” Lloyd said. “You couldn’t hope for a better case study to prove the technology commercially.”

According to Dikai Lui, Professor of Mechanical and Mechatronic Engineering at UTS, designing a robot that could work in an unstructured environment was a big challenge.

“We needed a really lightweight robot but one that also had a high payload (the force used to blast away paint) and that could work on its own in an unfamiliar environment,” Professor Lui said. “Such a thing didn’t exist.”

The robot is connected to a local power source and placed in position, and then it scans the area it needs to clean. It creates a 3D map of the area and then works out exactly where it needs to position itself and how much force its grit-blasting arm needs before it starts stripping paint from the steelwork. As it works, it moves along on a length of rail line inside one of the scaffolding bays suspended under the bridge.

The risk to workers who do the same job is high, Lloyd says. It is physically demanding, the high-pressure hose can cause injury and workers have to wear full protective gear to protect against dust and lead particulates.

“The whole point of an autonomous system is that you can set it up, press the button and get out of the way. You only go in to touch up bits and pieces the robot may have missed,” Lloyd said.

Professor Lui hopes the next generation of robots will communicate with other robots doing the same work, working back to back on the grit-blasting.

“You will see many different kinds of robots in the future, with different designs but the core technology will be the same, being able to work in an environment they haven’t been in before,” said Professor Lui. “That is the intelligent part.”