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Evaluating position control for real-time hydrodynamic motion response in a robotized dry test rig with a point-absorber wave energy converter
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2024 (English)In: Proceedings of the ASME 2024 43rd International Conference on Ocean, Offshore and Arctic Engineering: Volume 1: Offshore Technology, Singapore, 2024, Vol. 1Conference paper, Published paper (Refereed)
Abstract [en]

A robotized dry test rig in six degrees of freedom, for emulating the influence of hydrodynamic forces on and the resulting motion response of different types of point absorbing wave energy converters has been developed at Uppsala University. In the past we have investigated and shown that the dry test rig works with both force and position control methods.In this article we further examine the position control method, as we have not been able to use it for rougher wave movements. This is due to the fact that there has been a control lag in the system which contributed to the system becoming unbalanced in some emulation scenarios. A solution for an updated position control method, with significantly reduced control lag, is demonstrated in robot simulations and compared with both hydrodynamic model simulations and physical robot experiments for two buoy sizes in regular waves.

The results show a clear positive solution for avoiding control lag problems, making the position control method fully possible to use in the field. Future work is to implement the updated method on the physical robot test rig.

Place, publisher, year, edition, pages
Singapore, 2024. Vol. 1
Keywords [en]
dry test rig, industrial robot, point-absorber, wave emulator, wave energy converter
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:uu:diva-540698DOI: 10.1115/OMAE2024-121981OAI: oai:DiVA.org:uu-540698DiVA, id: diva2:1906724
Conference
ASME 2024 43rd International Conference on Ocean, Offshore and Arctic Engineering
Available from: 2024-10-18 Created: 2024-10-18 Last updated: 2024-12-10
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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