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Module for wireless powering of micro robots

Result description: In task 2.4 partner Fraunhofer-IBMT has developed a module for wireless powering of micro robots. Details of the results are disclosed in deliverable D2.7. The module for wireless powering consists of two sub-components. The first sub-component is located at the robot and is an integrated power unit. It consists of a miniaturized coil and an electronic circuit. The second sub-component is an external unit (power floor), which wirelessly transmits electrical energy to the integrated power unit by means of an external alternating magnetic field. The external magnetic field is generated by a special arrangement (patent pending) of inductive coils. The coils are fed by two alternating currents with fixed phase shift of pi/2. These currents are generated with a signal generator and two power amplifiers. The special coil arrangement assures that a significant magnetic field is only present within a small vicinity of the power floor. For receiving the inductive power, the robots must be located close to the power floor. The total area of the power floor is 24 x 24cm2. The available working area is about 20 x 22 cm2. The module for wireless powering is able to transmit 330mW power to the robot without heating up the power floor above 37°C. It fully fulfils the defined requirements.

Dissemination and use potential:
Fraunhofer-IBMT has filed a German patent on the power floor entitled "Vorrichtung und Verfahren zur induktiven Energieubertragung" (Translation: "Device and Method for inductive energy transfer") (Number: 103473DE, priority date: 8. June 2004). Additionally two papers covering the topics of MICRON-research have been presented during scientific conferences. A paper dealing with the power floor has been submitted to a scientific journal.

Scientific publications:
J. Brufau, M. Puig-Vidal,, J. Lopez-Sanchez, J. Samitier, N. Snis, U. Simu, S. Johansson, W. Driesen, J.-M. Breguet, J. Gao, T. Velten, J. Seyfried, R. Estana and H. Woern: "MICRON: Small Autonomous Robot for Cell Manipulation Applications". Proceedings of 2005 IEEE International Conference on Robotics and Automation. April 18-22, 2005, Barcelona, Spain

Jianbo Gao: "Inductive Power Transmission for Untethered Micro-Robots", The 31st Annual Conference of the IEEE Industrial Electronics Society, Sheraton Capital Centre, Raleigh, North Carolina, USA, November 6 - 10, 2005, accepted as oral presentation

Jianbo Gao: "Traveling Magnetic Field for Homogeneous Wireless Power Transmission", IEEE Transactions on Power Delivery, submitted on June 30, 2005

Key innovative features:
Usually two coils are used for inductive powering transmission, the sending coil and the receiving coil. The straightforward solution for inductive power transmission is using two circular coils as the sending and receiving coils. This solution has some drawbacks because the sending coil in the power floor is required to be large (24 x 24cm2) and the robot coil must be about 1cm in diameter. In order to induct enough power in the robot coil, the sending coil must produce a strong enough magnetic field. That means there must be a strong current in the sending coil. Consequently, either the voltage between the two ends of the coil would be very high (> 10,000V) or the heat power of the coil is very high. This makes the straightforward solution not feasible.

Therefore, an alternative approach for producing alternating magnetic field on the power floor was developed, which is called parallel coil method and which is described in deliverable D2.7. The innovative design and arrangement of the windings of the power floor allows running the power floor at a reasonable voltage. By transmitting the requested power of 330mW to the robot the temperature of the power floor does not raise above 37°C. In a plane parallel to the surface of the power floor the distribution of the magnetic field is homogeneous. A significant electromagnetic field is present in the close vicinity of the surface of the power floor only. Thus the developed power floor does not influence any (electronic) devices in its neighbourhood.

It is planned to exploit the developed power floor. But up to now no company has been found who is interested in the power floor or at least in the new concept for inductive power transfer. During the next year partner FhG will intensify these efforts. The filed patent presents a good starting point for negotiations with companies.

Current status and use of the result:
At the moment the developed power floor is used to power the developed micro robots

Expected benefit:
It is envisaged to use the power floor for wireless powering of industrial micro robots if such robots are available in the future. It is also possible to use the power floor concept for wireless powering of medical implants.

Informations connexes

Reported by

Fraunhofer-Institute for Biomedical Engineering
Ensheimer strasse 48
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