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Emulating Wave Energy Converter operation in irregular waves using a robotized dry test rig
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity. (Robotic)ORCID iD: 0000-0003-3028-4887
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.ORCID iD: 0000-0002-2031-8134
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity. (Robotic)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Wave Energy Converter (WEC) technology has for a long time captured the interest of researchers, in the strive to increase and diversify the share of renewables in our global energy system. The development of WECs is however challenging due to the time-consuming and expensive open sea experiments required. Controlled wave tank testing is therefore often used, but suffer from the limited availability, scale and wave conditions that can be achieved. Another option is dry test rigs, utilizing a mechanical actuator to emulate WEC operation in ocean waves. Achieving realistic tests is however a challenge.

This work focuses on a robotized dry test rig, providing a cost-effective, industrial and flexible test concept for one-body and two-body emulation of point-absorber WECs in in all six degree of freedom. A numerical linear potential flow hydrodynamic force model for simulating the motions in irregular waves is presented and evaluated against wave tank experiments, before being implemented on the robot controller. Test rig experiments based on a simulated WEC damping force and assuming a one-body system acting purely in heave are presented.

We successfully demonstrated WEC operation emulation in irregular waves with the robot test rig, and were also able to evaluate its accuracy. It can be concluded that the robot performs well in relation to the numerical model, while the numerical model performs satisfying mainly for smaller and non-steep waves. Further work is therefore suggested on expanding the emulation to several degrees of freedom and also to include a physical WEC power take-off unit.

Keywords [en]
Dry test rig, Industrial robot, Wave Energy Converter, Hydrodynamic modelling, Irregular waves
National Category
Robotics and automation
Research subject
Engineering science with specialization in Applied Mechanics; Engineering Science with specialization in industrial engineering and management
Identifiers
URN: urn:nbn:se:uu:diva-544284OAI: oai:DiVA.org:uu-544284DiVA, id: diva2:1917632
Note

Artikeln har inlämnats/submitted

Available from: 2024-12-03 Created: 2024-12-03 Last updated: 2025-02-09
In thesis
1. Industrial robot as main equipment for testing and production of Wave Energy Converters
Open this publication in new window or tab >>Industrial robot as main equipment for testing and production of Wave Energy Converters
2025 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Since 2001, research and development on the conversion of ocean wave energy into electricity has been conducted at the Division of Electricity at Uppsala University. Different Wave Energy Converter (WEC) technologies has been developed, such as the point-absorber linear Uppsala University WEC (UU-WEC) and the Low-RPM Torque Converter WEC (LRTC-WEC). 

This thesis focuses primarily on the development of a robotized dry test rig, to facilitate assessment of different WEC technologies in house. An existing industrial six degrees of freedom robot system is used to emulate buoy movement on the sea surface, with regard to the impact of hydrodynamic forces in real time. Two different methods for integrating a hydrodynamic model to the robot controller are presented: the force control and the position control methods. Both methods are evaluated and validated across various regular and irregular wave climates, as well as for different theoretical buoy shapes.  

The secondary focus in this thesis is the development of robotized production methods for the UU-WEC. The surface mounting of Neodymium Iron Boron (Nd2Fe14B) magnets and the cutting of rubber discs are investigated, resulting in viable solutions that include development and validation of robot tooling and robot cell proposals. 

A smaller segment of the thesis examines the use of robotics in teaching a course for bachelor engineering students. At the outbreak of the COVID-19 pandemic a challenging task was imposed: a swift shift to online distant education. A major task was to replace physical lab exercises with video recordings, detailed instructions and simulated laboratory environments. The results indicated that the upgraded online education successfully meet the course objectives.

The final part of the thesis investigates the use of WECs for powering a desalination plant. Desalination presents a viable solution for islands or coastal regions deficient in freshwater resources, but is also an energy intensive process. Practical experiment evaluated the possibility of utilizing the UU-WEC as power source for desalination plants.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2025. p. 78
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 2485
Keywords
Dry test rig, Industrial robotics, Manufacturing automation, Large-scale production, Linear generator, Wave energy converter, Engineering education, Desalination
National Category
Robotics and automation Other Electrical Engineering, Electronic Engineering, Information Engineering Communication Systems Control Engineering
Research subject
Engineering Science with specialization in Science of Electricity; Engineering Science with specialization in Electronics; Engineering science with specialization in Applied Mechanics; Engineering Science with specialization in industrial engineering and management; Electrical Engineering with specialization in Automatic Control; Engineering Science with specialization in industrial engineering and management
Identifiers
urn:nbn:se:uu:diva-544285 (URN)978-91-513-2337-4 (ISBN)
Public defence
2025-02-10, Polhem, Lägerhyddsvägen 1, 75237 Uppsala, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2025-01-17 Created: 2024-12-10 Last updated: 2025-02-05

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Salar, DanaEngström, Jens

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