Development of offshore wind farms is on the rise – but how do we intend on prolonging the life-cycle of platforms installed in our oceans? This case study spotlights CIRS, a robotics lab at the University of Girona, pioneering solutions for Inspection, Maintenance and Repair (IMR) of floating wind turbines using subsea electric manipulators.
Future-Proofing Offshore Wind Infrastructure
As of 2023, there are reportedly over 11,900 offshore wind turbines in operation around the world1. With growing investment in renewable energies and ongoing development in the offshore wind energy sector, attention turns to future proofing these assets. Being largely comprised of steel and concrete, floating offshore wind platforms face the challenges typically associated with open ocean environments: mooring lines deform, protective coatings wear away and surfaces corrode. Regular, periodic inspection is critical to avoiding platform failure by allowing signs of degradation to be identified early in order to repair and preserve the integrity of an asset.
Subsea Inspection, Maintenance and Repair (IMR) is typically performed by highly skilled commercial divers or by large work-class ROVs and support vessels where necessary. Both approaches have significant costs and risks associated leading commercial industries to seek alternate solutions. One such solution is smaller inspection-class ROVs and AUVs, equipped with electric manipulators for regular, remote inspection.
Robotics Researchers at CIRS Pioneer Autonomous Solutions
Since 2020, the Centre d’Investigació en Robòtica Submarina (CIRS) at the University of Girona, has been working with the Reach Robotics’, Bravo 7 electric manipulator on the ATLANTIS project. Funded by the European Unions, ‘Horizon 2020‘ programme, ATLANTIS attributes 30% of the total cost of energy for offshore wind power to operation and maintenance expense. They aim to reduce this cost by evaluating the effectiveness of subsea robotic technology for IMR applications. This evaluation occurs at a large-scale pilot infrastructure off the coast of Viana do Castelo, Portugal, and is comprised of dedicated positions within a commercial wind farm.
The CIRS Lab, lead by Prof. Pere Ridao, focuses on underwater robotics and underwater vision. Their team have developed three advanced AUVs with varying capabilities from autonomous motion planning to high-resolution image mapping and perception. Now, with the Reach Bravo 7 electric manipulator, CIRS are increasing the capability of their ‘Girona 1000’ AUV to include autonomous inspection tasks for IMR.
Bravo 7 Electric Manipulator used for CP Testing and Surface Cleaning
CIRS’s work with ATLANTIS tackles two primary applications using the Bravo 7 manipulator: Surface Cleaning and Cathodic Protection (CP) testing of floating offshore wind structures. CP is a Non-Destructive Testing (NDT) methodology whereby a probe is used to measure the electrical potential difference between the metal structure and a reference electrode. By measuring this, operators know if a structures protective coating is still providing effective protection from the elements.
The CIRS Team successfully demonstrated and filmed both applications using the Bravo 7 integrated on their Girona1000 AUV in their demo-tank (scroll to see their videos at the end of this article). Following their in-house demonstrations, the system was successfully deployed and tested in real-world conditions at the ATLANTIS offshore wind platform in Portugal. This positive result advances robotic capability for offshore IMR applications and impacts the long term future of renewable wind energy.
What makes the Reach Bravo 7 electric manipulator the right tool for NDT?
Autonomous placement of a CP probe in the right location with a precise amount of force (neither too little, nor too much), while dealing with disturbances such as ocean currents is not simple.
To face this, the Girona team selected the Reach Bravo 7 due to its dexterity, precision, and speed. The accuracy of the Bravo enables the probe to apply and maintain a desired amount of pressure when in contact with the surface being inspected. The ability to customise the force applied during the inspection allows operators to account for external disturbance and adjust pressure as required. This process is simplified with Reach Robotics manipulators due to the accessibility of the control interface (API) that provides flexibility to researchers and integrators.
Talking with Reach Robotics, Roger Pi Roig, PhD Researcher at CIRS, said that the Reach Bravo 7 had “performed very well in this work since it is agile and precise, allowing the system to react very quickly which is necessary for admittance control”.
With positive outcomes from their NDT testing, CIRS are continuing to use Reach Robotics manipulators for their research and have begun integrating a dual Bravo 7 system on their Girona500 AUV. Their future work involves subsea imaging for which they have developed a custom gripper with in-built camera attached to the Bravo end effector module. We look forward to following CIRS research outcomes for their new dual Bravo electric manipulator integration – stay tuned for updates!
References
- US Department of Energy, ‘Offshore Wind Market Report: 2023 Edition Executive Summary’, Office of Energy Efficiency and Renewable Energy, p.10, 2023, https://www.energy.gov/sites/default/files/2023-08/offshore-wind-market-report-2023-edition-executive-summary_0.pdf
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