| 1. |
- Hultman, Erik, et al.
(författare)
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A robotized 6-DOF dry test rig for wave power
- 2023
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Ingår i: Sustainable Energy Technologies and Assessments. - : Elsevier. - 2213-1388 .- 2213-1396. ; 59
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Tidskriftsartikel (refereegranskat)abstract
- Wave power has the potential to contribute significantly to sustainability by reducing our global dependence on fossil fuels. Due to harsh conditions and high costs associated with offshore testing, lab experiments are favourable for resource-efficient validation and optimization in developing Wave Energy Converter (WEC) technologies. The limited scale and availability of existing wave tanks, and the limited flexibility of existing dry test rigs does however put significant restraints on such experiments. In this paper we introduce an alternative novel robotized dry test rig concept for wave power, evaluate its performance and discuss its potential. A full-scale robotized dry test rig demonstrator is constructed and used for experiments with a WEC prototype device. High motion flexibility and accuracy is thereby validated, also for repeating recorded wave and buoy motions. Compared to other dry test rigs, no special components were used and the motion trajectories were defined in full 6-Degrees-Of-Freedom. Two real-time hydrodynamic motion response methods are also demonstrated in the test rig, enabling emulation of actual offshore operation as well as development of advanced WEC control strategies. With a larger industrial robot manipulator, the introduced test rig concept could achieve realistic scaled force and power experiments with most point absorber WECs.
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| 2. |
- Hultman, Erik, et al.
(författare)
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Learnings from the rapid online transition of a real-world project task-based engineering course
- 2022
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Ingår i: 2022 IEEE Frontiers in Education Conference (FIE). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665462457 - 9781665462440
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Konferensbidrag (refereegranskat)abstract
- This Innovative Practice Full Paper presents the results and learnings from a rapid and forced transition to online teaching of a campus-based and practical lab exercise intense course in robot engineering. Founded in previous pedagogical development work, we continued with activating and varied teaching methods connected through integrated project tasks. The online transition is evaluated from student course evaluations, examination results and the teachers’ experiences from ten campus course occasions and four online course occasions during ten years. The paper focuses specifically on the combination of an innovative online lecturing format and fully virtual robot lab exercises. Our aim is to present learnings of interest for the engineering education community. The results highlight a successful and appreciated online course transition, with possibly improved student learning. In particular the prerecorded video lectures were praised, the virtual labs was similarly appreciated as campus labs and it was demonstrated that online robot programming can be performed virtually, while practical lab exercises and study visits were still missed.
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| 3. |
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| 4. |
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| 5. |
- Hultman, Erik, et al.
(författare)
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Robotized Surface Mounting of Permanent Magnets
- 2014
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Ingår i: Machines. - : MDPI AG. - 2075-1702. ; 2:4, s. 219-232
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Tidskriftsartikel (refereegranskat)abstract
- Using permanent magnets on a rotor can both simplify the design and increase the efficiency of electric machines compared to using electromagnets. A drawback, however, is the lack of existing automated assembly methods for large machines. This paper presents and motivates a method for robotized surface mounting of permanent magnets on electric machine rotors. The translator of the Uppsala University Wave Energy Converter generator is used as an example of a rotor. The robot cell layout, equipment design and assembly process are presented and validated through computer simulations and experiments with prototype equipment. A comparison with manual assembly indicates substantial cost savings and an improved work environment. By using the flexibility of industrial robots and a scalable equipment design, it is possible for this assembly method to be adjusted for other rotor geometries and sizes. Finally, there is a discussion on the work that remains to be done on improving and integrating the robot cell into a production line.
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| 6. |
- Leijon, Jennifer, 1990-, et al.
(författare)
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Variable renewable energy sources for powering reverse osmosis desalination, with a case study of wave powered desalination for Kilifi, Kenya
- 2020
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Ingår i: Desalination. - : Elsevier BV. - 0011-9164 .- 1873-4464. ; 494:114669
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Tidskriftsartikel (refereegranskat)abstract
- An analysis of reverse osmosis powered by ocean wave power is provided. A commercially available desalination system is connected via a DC/AC converter to a variable DC source and the input voltage is altered to emulate the response of a renewable energy system. Specifically, wave data from Kilifi in Kenya during 2015 is used. The wave resource variations provide variations in estimated power output from a wave energy converter, as well as in estimated freshwater production from a wave powered desalination system. Up to three wave energy converters for desalination are investigated for Kilifi. Also, a hybrid system including solar and wave power is proposed. The experiments show that reverse osmosis desalination systems can function at power levels below the rated values, but with lower freshwater flowrates. It is concluded that wave power, or wave power combined with PV systems, may be considered as power sources for desalination, with or without battery storage.
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| 7. |
- Salar, Dana, et al.
(författare)
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Demonstrating real-time hydrodynamic motion response in force control for regular waves in a robotized dry test rig with a point-absorber WEC
- 2023
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Ingår i: Proceedings of the 15th European Wave and Tidal Energy Conference, Bilbao, 3-7 September 2023.. - Bilbao : European Wave and Tidal Energy Conference.
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Konferensbidrag (refereegranskat)abstract
- A 6-Degrees-Of-Freedom robotized dry test rig has been developed at Uppsala University to test point absorbing WECs (Wave Energy Converters). Using a six joint industrial robot as a buoy movement emulator, the robot's outermost point (joint 6) is connected to the wire from the generator concept WEC PTO (Power Take-Off). The robot's movement in joint 6 thus corresponds to the buoy movement on the sea surface. The test rig can be used for various point absorbing WEC PTO units. In this project, the test rig has been used with a WEC-PTO prototype. The point absorbing WEC-LRTC concept is being developed at Uppsala University. The generator concept is made up of two identical rotating generators. A wire is used as a connection between the generator concept at the seabed and a buoy on the sea surface. The goal of this article is to demonstrate and evaluate how the test rig interacts with the LRTC-WEC PTO in regular waves. In the presented experiments, a hydrodynamic model with force control method has been used. The results show a clear difference in the use of the hydrodynamic model with different sizes of the buoy. The test rig with the force control model can be used easily to test different theoretical buoys and different load settings for WEC PTOs. Effective experiments can be performed with real PTO forces instead of simplified simulations. Future work is to experiment with the position control method and also experiments with irregular waves.
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| 8. |
- Salar, Dana, 1985-, et al.
(författare)
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Low-RPM torque converter (LRTC) with Integrated direct shaft flywheel
- 2023
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Ingår i: International Marine Energy Journal. - 2631-5548. ; 6:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- The low-RPM Torque Converter (LRTC) is a rotating generator concept for use on the seabed with the driving force from sea waves motion on the sea surface. This concept is built up of two identical generators connected opposite each other via a spring drum with a built-in ball bearing clutch. The drum is connected to a buoy on the sea surface via a wire, the wire is rolled around the spring drum. With sea waves, the buoy moves either upwards or downwards and pulls the wire upwards or downwards. This movement causes the generators to spin.This article presents an upgrade of the LRTC generator concept and upgraded measurement system, both hardware and software.A flywheel system of the thin-disc type has been designed for direct connection to the generator's rotor shaft and an electronic measuring system has also been developed for more accurate measurements and minor disturbances.More detailed tests have been performed both for the purpose of comparing the systems and to explore the performance of the generator concept in more detail.Three different experiments have been done in this article. The first two experiments were performed to investigate the performance of the flywheel and to see the performance of the LRTC system with and without flywheel.The third experiment investigated the optimization of the flywheel mass by increasing the mass of the flywheel with the addition of more thin discs.All movements are simulated with a six-joint industrial robot. Several sinusoidal types of wave motions have been simulated with different time periods and also several real wave climate motions (data taken from fields) have been simulated with the robot. The experiments show that the addition of the flywheel in the LRTC system provides advantages in increasing both peak power, average output power and also softens the output power oscillation.
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| 9. |
- Savin, Andrej, et al.
(författare)
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Low-RPM Torque Converter (LRTC)
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:16
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Tidskriftsartikel (refereegranskat)abstract
- The concept concerned in this paper is based on energy conversion of the ocean waves via rotational generators. The objective of this research is to develop a new type of slow-motion converter. The LRTC device consists of a drum that is connected via wire to a floating buoy. The drum is connected to rotary generators. The generators are heavily braked when the direction of movement changes (up/down); this is because the generators have been charged the maximum load in order to obtain maximum output power. For upcoming improvement, the generators should have some power storage as flywheel. In the future experiments, the torque converter can even be tuned to rotate in resonance with the incoming waves, strongly increasing power absorption. Constant force springs are applied for this purpose. The focus of this project is, therefore, a new generation of wave power device for utility-scale energy conversion offering a cost of energy that can compete with established energy resources.
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