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Self-Sensing Electromagnets for Robotic Tooling Systems: Combining Sensor and Actuator
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.ORCID iD: 0000-0001-8315-5523
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2016 (English)In: Machines, ISSN 2075-1702, Vol. 4, no 3, 16Article in journal (Refereed) Published
Abstract [en]

A low-cost method, which integrates distance sensing functionality into a switched electromagnet by using a hybrid switching mode and current ripple measurements, is proposed. The electromagnet is controlled by a micro-controller via a MOSFET H bridge, utilizing a comparator-based current control. Additionally, a method for calculating the inductance of the electromagnet and approximating the magnetic contact between the electromagnet and its target is also presented. The resulting tool is attached to an industrial robot, and the system performance using this setup is evaluated. Distance sensing in the range of 0 mm to 5.2 mm is demonstrated. It is also shown that the relation between magnetic contact, coil current and calculated inductance can be reduced to a predictive look-up table, enabling the quality of the magnetic contact to be estimated using minimal computational effort.

Place, publisher, year, edition, pages
2016. Vol. 4, no 3, 16
Keyword [en]
electromagnet, distance measurement, self-sensing, robotic-tool, current control, current ripple, H bridge, micro-controller
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:uu:diva-305436DOI: 10.3390/machines4030016ISI: 000401524100003OAI: oai:DiVA.org:uu-305436DiVA: diva2:1038354
Funder
VINNOVA
Available from: 2016-10-18 Created: 2016-10-18 Last updated: 2017-10-08Bibliographically approved
In thesis
1. Automated Production Technologies and Measurement Systems for Ferrite Magnetized Linear Generators
Open this publication in new window or tab >>Automated Production Technologies and Measurement Systems for Ferrite Magnetized Linear Generators
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The interest in breaking the historical dependence on fossil energy and begin moving towards more renewable energy sources is rising worldwide. This is largely due to uncertainties in the future supply of fossil fuels and the rising concerns about humanity’s role in the currently ongoing climate changes. One renewable energy source is ocean waves and Uppsala University has since the early 2000s been performing active research in this area. The Uppsala wave energy concept is centered on developing linear generators coupled to point absorbing buoys, with the generator situated on the seabed and connected to the buoy on the sea surface via a steel wire. The motion of the buoy then transfers energy to the generator, where it is converted into electricity and sent to shore for delivery into the electrical grid.

This thesis will mainly focus on the development and evaluation of technologies used to automate the manufacturing of the translator, a central part of the linear generator, using industrial robotics. The translator is a 3 m high and 0.8 m wide three sided structure with an aluminum pipe at its center. The structure consists of alternating layers of steel plates (pole-shoes) and ferrite magnets, with a total of 72 layers per side. To perform experiments on translator assembly and production, a robot cell (centered on an IRB6650S industrial robot) complimented with relevant tools, equipment and security measures, has been designed and constructed. The mounting of the pole-shoes on the central pipe, using the industrial robot, proved to be the most challenging task to solve. However, by implementing a precise work-piece orientation calibration system, combined with selective compliance robot tools, the task could be performed with mounting speeds of up to 50 mm/s. Although progress has been made, much work still remains before fully automated translator assembly is a reality.

A secondary topic of this thesis is the development of stand-alone measurement systems to be used in the linear generator, once it has been deployed on the seabed. The main requirements of such a measurement system is robustness, resistance to electrical noise, and power efficiency. If possible the system should also be portable and easy to use. This was solved by developing a custom measurement circuit, based on industry standard 4–20 mA current signals, combined with a portable submersible logging unit. The latest iteration of the system is small enough to be deployed and retrieved by one person, and can collect data for 10 weeks before running out of batteries. Future work in this area should focus on increasing the usability of the system.

The third and final topic of this thesis is a short discussion of an engineering approach to kinetic energy storage, in the form of high-speed composite flywheels, and the design of two different prototypes of such flywheels. Both designs gave important insights to the research group, but a few crucial design faults unfortunately made it impossible to evaluate the full potential of the two designs.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. 79 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1573
Keyword
industrial robotics, automation, self-sensing, calibration, ferrite, linear generator, wave energy, offshore, measurements, electronics, kinetic energy storage, reluctance motor
National Category
Robotics Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-330866 (URN)978-91-513-0095-5 (ISBN)
Public defence
2017-11-24, Polhemsalen, Lägerhyddsvägen 1, 752 37 Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2017-11-02 Created: 2017-10-08 Last updated: 2017-11-02

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Kamf, TobiasAbrahamsson, Johan

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