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Maintaining something several miles out at sea and hundreds of metres tall is not easy. Getting technicians and engineers to the turbines is tricky, requiring specialist vessels to tackle frequent rough weather. Turning turbines off during inspections is a headache, especially given concerns about interrupted power supplies.
Engineers are increasingly looking to robots to do some of the work instead. In September, the Offshore Wind Growth Partnership announced £1m funding for seven British firms developing technologies to improve offshore wind infrastructure. Among them is Leeds firm Acuity Robotics, whose Squirrel robot is designed to climb steel structures and inspect them for defects that could otherwise go unnoticed.
The technology could help solve a growing problem, according to founder and chief operating officer Rob Richardson: many wind turbines have been operating for decades, and welds are deteriorating alongside corrosion taking hold. “We’re getting very much into the ageing effects,” Richardson says. That necessitates more frequent inspections, but “the inspection itself is very disruptive,” he says. Because of the way wind turbines are networked, taking a single device offline for maintenance can mean turning others off.
Avoiding that issue, and the long list of safety checks for human workers, requires a solution. Acuity’s answer is a small, six-wheeled robotic platform called Squirrel. Weighing about 4kg, it uses magnetic adhesion to cling to steel surfaces, climbing structures that humans would be unable to without specialist equipment and a no-go zone or power turnoff.
Squirrel’s sensors allow it to establish where it is on the structure, while interchangeable inspection equipment can examine the metal beneath the surface – carefully checking the weld seams that keep sections of steel together. The robot can travel around these surfaces, collecting information about the condition of welds so asset owners can determine whether further attention is necessary.
Getting to that point meant overcoming some engineering challenges. “One of the things I think that's often underestimated is how hard it is to reliably move around these structures and not fall off,” Richardson says. “Can you stick to them all the time? Can you guarantee that they’re not going to fall off?” The magnetic adhesion that Squirrel uses works fine on large sections, but it becomes less effective when turbines are painted or covered with branding stickers.
Acuity is developing a successor to Squirrel, called Mag Nine, which promises improved manoeuvrability. Both bots are untethered, without cables or hoses that could get caught up in an operating turbine. “It doesn’t need to be turned off, which is a massive thing,” Richardson says.
The company is operating its technology semi-autonomously, but wants to progress towards inspections that can be completed with much less human involvement.
The Leeds business is not alone in trying to take people out of dangerous offshore maintenance work. London robotics company BladeBug, which was acquired by Australian engineering firm Nexxis Technology in September, has developed a six-legged robot that uses suction to move across turbine blades. Unlike Acuity's magnetic machines, it is designed to operate on composite surfaces.
In 2020, BladeBug demonstrated its robot walking along an offshore turbine blade at a test facility in Scotland. After its demonstration, the Offshore Renewable Energy Catapult estimated the technology could reduce blade inspection costs by 30% compared with traditional methods.
Other projects have looked at using robots to measure bolt tension, potentially removing the need for technicians to manually loosen and retighten thousands of fixings. And another project is developing autonomous drone inspections that could be conducted from vessels already visiting wind farms for maintenance.
Many of these projects are in their early stages, and still need plenty of work to become commonplace. But if wind power is to play an even bigger role in our energy mix, Richardson says, we will need to make routine inspections quicker and less disruptive, while giving operators better information about the condition of their equipment.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.