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Robotized Production Methods for Special Electric Machines
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A research project on renewable energy conversion from ocean waves to electricity was started at the Division of Electricity at Uppsala University (UU) in 2001. The Wave Energy Converter (WEC) unit developed in this project is intended to be used in large offshore WEC farms and has therefore been designed with large-scale production in mind. The concept has now also been commercialized by the spin-off company Seabased Industry AB.

An essential part of the UU WEC is the linear direct-drive generator. This thesis presents the pilot work on developing robotized production methods for this special electric machine. The generator design is here investigated and four different backbreaking, monotone, potentially hazardous and time consuming manual production tasks are selected for automation. A robot cell with special automation equipment is then developed and constructed for each task. Simplicity, reliability and flexibility are prioritized and older model pre-owned industrial robots are used throughout the work. The robot cells are evaluated both analytically and experimentally, with focus on full scale experiments. It is likely that the developed production methods can be applied also for other similar electric machines.

The main focus in the thesis is on robotized stator cable winding. The here presented robot cell is, to the knowledge of the author, the first fully automated stator cable winding setup. Fully automated winding with high and consistent quality and high flexibility is demonstrated. Significant potential cost savings compared to manual winding are also indicated. The robot cell is well prepared for production, but further work is required to improve its reliability.

The other three developed robot cells are used for stator stacking, surface mounting of permanent magnets on translators and machining of rubber discs. All robot cell concepts are experimentally validated and considerable potential cost savings compared to manual production are indicated. Further work is however required with regards to autonomy and reliability.

Finally, the thesis presents a pedagogical development work connected to the research on robotized production methods. A first cycle course on automation and robot engineering is here completely reworked, as it is structured around three real-world group project tasks. The new course is evaluated from the examination results, the students’ course evaluations and the feedback from the teachers during six years. The students greatly appreciated the new course. It is indicated that the developed teaching approach is effective in teaching both classical and modern engineering skills.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. , p. 82
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1608
Keyword [en]
Industrial robotics, Assembly automation, Large-scale production, Cable winding, Linear generator, Wave energy converter, Wave power, Engineering education
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
URN: urn:nbn:se:uu:diva-335504ISBN: 978-91-513-0177-8 (print)OAI: oai:DiVA.org:uu-335504DiVA, id: diva2:1163426
Public defence
2018-02-02, Polhemsalen, Lägerhyddsvägen 1, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2018-01-12 Created: 2017-12-07 Last updated: 2018-03-07
List of papers
1. Electromagnetic, Mechanical and Manufacturing Properties for Cable Wound Direct-Drive PM Linear Generators for Offshore Environments
Open this publication in new window or tab >>Electromagnetic, Mechanical and Manufacturing Properties for Cable Wound Direct-Drive PM Linear Generators for Offshore Environments
2012 (English)In: Proceedings of the ASME 31st International Conference on Ocean, Offshore and Arctic Engineering, 2012, VOL 4, 2012, p. 441-447Conference paper, Published paper (Refereed)
Abstract [en]

Renewable energy conversion in offshore environments, such as wave, wind and tidal energy, can potentially give a considerable contribution to the global electric energy demand. These harsh environments require robust generators with minimal need for maintenance at competitive costs. To reduce the generator cost, the electromagnetic design must be done with manufacturing in mind. An optimal design provides high electric efficiency, long device life-time, little need for maintenance and low manufacturing costs. Modern simulation tools can be used to optimize the electromagnetic design of a generator for a specific task and operation mode. Hereby both electromagnetic losses and material stresses can be reduced. Industrial robots might provide new possibilities to automate generator-specific manufacturing tasks. A generator design with a cable wound stator, surface mounted permanent magnets on the translator and direct-drive linear technology is investigated in this article. This concept has a simpler and more robust mechanical design, while both the electromagnetic losses and the need for maintenance are reduced. By reducing the number of generator assembly steps, manufacturing might also be facilitated. Further work is however needed in developing automated assembly methods and comparing them to conventional generator manufacturing.

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-190222 (URN)000324655900049 ()978-0-7918-4491-5 (ISBN)
Conference
31st International Conference on Ocean, Offshore and Arctic Engineering, Jul 1-6, 2012, Rio de Janeiro, Brazil
Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2017-12-07Bibliographically approved
2. Status Update of the Wave Energy Research at Uppsala University
Open this publication in new window or tab >>Status Update of the Wave Energy Research at Uppsala University
Show others...
2013 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Aalborg, Denmark: , 2013
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-212701 (URN)
Conference
10th European Wave and Tidal Conference (EWTEC)
Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2017-12-07
3. Preparing the Uppsala University wave energy converter generator for large-scale production
Open this publication in new window or tab >>Preparing the Uppsala University wave energy converter generator for large-scale production
Show others...
2014 (English)Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Halifax, Canada: , 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-237554 (URN)
Conference
5th International Conference on Ocean Energy
Available from: 2014-12-03 Created: 2014-12-03 Last updated: 2017-12-07
4. Utilizing cable winding and industrial robots to facilitate the manufacturing of electric machines
Open this publication in new window or tab >>Utilizing cable winding and industrial robots to facilitate the manufacturing of electric machines
2013 (English)In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 29, no 1, p. 246-256Article in journal (Refereed) Published
Abstract [en]

Cable wound electric machines are used mainly for high voltage and direct-drive applications. They can be found in areas such as wind power, hydropower, wave power and high-voltage motors. Compared to conventional winding techniques, cable winding includes fewer manufacturing steps and is therefore likely to be better suited for automated production. Automation of the cable winding production step is a crucial task in order to lower the manufacturing costs of these machines. This article presents a production method using industrial robots for automation of cable winding of electric machine stators. The concept presented is validated through computer simulations and full-scale winding experiments, including a constructed robot-held cable feeder tool prototype. A cable wound linear stator section of an Uppsala University Wave Energy Converter and its winding process is used as a reference in this article. From this example, it is shown that considerable production cycle time and manufacturing cost savings can be anticipated compared to manual winding. The suggested automation method is very flexible. It can be used for the production of cable wound stators with different shapes and sizes, for different cable dimensions and with different winding patterns.

Keyword
Stator winding, Automated production, Industrial robot, Electric machine assembly, Powerformer, Wave energy converter
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-187001 (URN)10.1016/j.rcim.2012.06.005 (DOI)000310116400021 ()
Available from: 2012-12-03 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
5. Six-Degrees-of-Freedom (6-DOF) Work Object Positional Calibration Using a Robot-Held Proximity Sensor
Open this publication in new window or tab >>Six-Degrees-of-Freedom (6-DOF) Work Object Positional Calibration Using a Robot-Held Proximity Sensor
2013 (English)In: Machines, Vol. 1, no 2, p. 63-80Article in journal (Refereed) Published
Abstract [en]

Industrial automation has been recognized as a fundamental key to build and keep manufacturing industries in developed countries. In most automation tasks, knowing the exact position of the objects to handle is essential. This is often done using a positional calibration system, such as a camera-based vision system. In this article, an alternative six-degrees-of-freedom work object positional calibration method using a robot-held proximity sensor, is presented. A general trigonometry-based measurement and calculation procedure, which, step-by-step, adjusts a work object coordinate system to the actual work object position, is explained. For suitable robot tasks and work object geometries, the benefits with the presented method include its robustness, large work area and low investment cost. Some drawbacks can be longer cycle time and its limited capacity to handle unsorted and complicated objects. To validate the presented method, it was implemented in an experimental robot setup. In this robot cell, it was used to calibrate the position of a stator section work object, which is used in the Uppsala University Wave Energy Converter generator. Hereby the function of the positional calibration procedure was validated. Sufficient positioning accuracy for the stator winding task was achieved and theoretically validated based on the experiments.

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-212667 (URN)10.3390/machines1020063 (DOI)
Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2017-12-07
6. A cable feeder tool for robotized cable winding
Open this publication in new window or tab >>A cable feeder tool for robotized cable winding
2014 (English)In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 30, no 6, p. 577-588Article in journal (Refereed) Published
Abstract [en]

Cable winding is an alternative technology to create stator windings in large electrical machines. Today such cable winding is performed manually, which is very repetitive, time-consuming and therefore also expensive. This paper presents the design, function and control system of a developed cable feeder tool for robotized stator cable winding. The presented tool was able to catch a cable inside a cable guiding system and to grab the cable between two wheels. One of these wheels was used to feed cable through the feeder. A control system was integrated in the tool to detect feeding slippage and to supervise the feeding force on the cable. Functions to calculate the cable feed length, to release the cable from the tool and for positional calibration of the stator to be wound were also integrated in the tool. In validating the function of the cable feeder tool, the stator of the linear generator used in the Wave Energy Converter generator developed at Uppsala University was used as an example. Through these experiments, it was shown that the developed robot tool design could be used to achieve automated robotized cable winding. These results also complied with the cycle time assumptions for automated cable winding from earlier research. Hence, it was theoretically indicated that the total winding cycle time for one Uppsala University Wave Energy Converter stator could be reduced from about 80 h for manual winding with four personnel to less than 20 h in a fully developed cable winding robot cell. The same robot tool and winding automation could also be used, with minor adjustments, for other stator designs.

Keyword
Cable feeder, Cable winding, Stator assembly, Powerformer, Wave Energy Converter
National Category
Robotics Computer Sciences
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-230907 (URN)10.1016/j.rcim.2014.04.003 (DOI)000340219600001 ()
Available from: 2014-09-04 Created: 2014-09-01 Last updated: 2018-01-11Bibliographically approved
7. Automated Cable Preparation for Robotized Stator Cable Winding
Open this publication in new window or tab >>Automated Cable Preparation for Robotized Stator Cable Winding
2017 (English)In: MACHINES, ISSN 2075-1702, Vol. 5, no 2, article id 14Article in journal (Refereed) Published
Abstract [en]

A method for robotized cable winding of the Uppsala UniversityWave Energy Converter generator stator has previously been presented and validated. The purpose of this study is to present and validate further developments to the method: automated stand-alone equipment for the preparation of the winding cables. The cable preparation consists of three parts: feeding the cable from a drum, forming the cable end and cutting the cable. Forming and cutting the cable was previously done manually and only small cable drums could be handled. Therefore the robot cell needed to be stopped frequently. The new equipment was tested in an experimental robot stator cable winding setup. Through the experiments, the equipment was validated to be able to perform fully automated and robust cable preparation. Suggestions are also given on how to further develop the equipment with regards to performance, robustness and quality. Hence, this work represents another important step towards demonstrating completely automated robotized stator cable winding.

Keyword
cable winding, industrial automation, industrial robot, electric machine assembly, wave energy converter
National Category
Robotics
Identifiers
urn:nbn:se:uu:diva-324239 (URN)10.3390/machines5020014 (DOI)000401525400004 ()
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2017-12-07Bibliographically approved
8. An updated cable feeder tool design for robotized stator cable winding
Open this publication in new window or tab >>An updated cable feeder tool design for robotized stator cable winding
2018 (English)In: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 49, p. 197-210Article in journal (Refereed) Published
Abstract [en]

We have previously suggested a method for robotized stator winding of cable wound electric machines and demonstrated the method successfully in full-scale experiments. The cable feeder tool used to handle the cable during the complete winding process is an essential component of this robot cell. To take the robot winding method to the next level, into an industrial product, require further developments regarding durability, independency, flexibility and implementability. In this paper, we present an updated cable feeder tool design. This tool is designed to be used in a robot cell for cable winding of the third-generation design of the Uppsala University Wave Energy Converter generator stator. In this work, three cable feeder tool prototypes have been constructed, experimentally evaluated and validated for the intended application. Key performance parameters are presented and discussed, including suggestions for further developments. We completed a durable, compact, high performance tool design, with fully integrated control into industrial robot controllers. The experimental results presented in this article are very promising and hence, the updated cable feeder tool design represents another important step towards an industrial solution for robotized stator cable winding.

National Category
Robotics Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-334553 (URN)10.1016/j.mechatronics.2018.01.006 (DOI)
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2018-04-26Bibliographically approved
9. Robotized stator cable winding
Open this publication in new window or tab >>Robotized stator cable winding
2018 (English)In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 53, p. 197-214Article in journal (Refereed) Published
Abstract [en]

Automated stator winding assembly has been available for small and medium sized conventional electric machines for a long time. Cable winding is an alternative technology developed for medium and large sized machines in particular. In this paper we present, evaluate and validate the first fully automated stator cable winding assembly equipment in detail. A full-scale prototype stator cable winding robot cell has been constructed, based on extensive previous work and experience, and used in the experiments. While the prototype robot cell is adapted for the third design generation of the Uppsala University Wave Energy Converter generator stator, the winding method can be adapted for other stator designs. The presented robot cell is highly flexible and well prepared for future integration in a smart production line. Potential cost savings are indicated compared to manual winding, which is a backbreaking task. However, further work is needed to improve the reliability of the robot cell, especially when it comes to preventing the kinking of the winding cable during the assembly.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-334554 (URN)10.1016/j.rcim.2018.04.009 (DOI)
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2018-04-26
10. Robotized stacking of the Uppsala University wave energy converter generator stator
Open this publication in new window or tab >>Robotized stacking of the Uppsala University wave energy converter generator stator
2014 (English)In: 33Rd International Conference On Ocean, Offshore And Arctic Engineering, 2014, Vol 9A: Ocean Renewable Energy, 2014Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-237544 (URN)000363499000001 ()978-0-7918-4553-0 (ISBN)
Conference
33rd International Conference on Ocean, Offshore and Arctic Engineering
Available from: 2014-12-03 Created: 2014-12-03 Last updated: 2017-12-07
11. Robotized Surface Mounting of Permanent Magnets
Open this publication in new window or tab >>Robotized Surface Mounting of Permanent Magnets
2014 (English)In: Machines, Vol. 2, no 4, p. 219-232Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-237449 (URN)10.3390/machines2040219 (DOI)
Available from: 2014-12-02 Created: 2014-12-02 Last updated: 2017-12-07
12. Robotized manufacturing of rubber components for commercialization of the Uppsala University wave energy converter concept
Open this publication in new window or tab >>Robotized manufacturing of rubber components for commercialization of the Uppsala University wave energy converter concept
2016 (English)Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Glasgow, UK: , 2016
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-334547 (URN)
Conference
2nd International Conference on Offshore Renewable Energy
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2017-12-07
13. Integration of real-world project tasks in a course on automation and robot engineering
Open this publication in new window or tab >>Integration of real-world project tasks in a course on automation and robot engineering
(English)In: European Journal of Engineering Education, ISSN 0304-3797, E-ISSN 1469-5898Article in journal (Refereed) Submitted
Abstract [en]

The modern engineering profession requires classical technical skills combined with creativity and a high proficiency in cooperation and sustainable development. Research indicates that the engineering education should adapt better to this. This paper presents and evaluates the integration of open-ended real-world project group tasks in an introduction course on automation and robot engineering. We used extensive written student course evaluations, the students’ examination results and the teachers’ experience for evaluation. Six occasions of the updated course are evaluated against the previous classical course. Both the students and the teachers greatly appreciated the new course. There was a strong indication that the students’ theoretical knowledge and understanding of the subject had improved, both with regards to the technical depth and to the increasingly important non-technical engineering skills. This was achieved without increasing their work load. It is likely that the presented teaching approach can be used also in other engineering courses.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-334555 (URN)
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2017-12-07

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