• Organisation

Abstract:

Dielectric elastomer actuators (DEA) offer breakthrough functionality in user interfaces by enabling freely programmable surface shapes. Furthermore the technology offers advantages in low energy consumption and costs on the one hand and flexibility on the other. However, DEAs require high driving voltages, which are challenging to realize, especially in mobile devices. The main challenge addressed in this thesis is the development of electronics which generate those high voltages (HV) in an efficient way, based on a battery voltage.

The requirements of the electronics, with respect to both the actuator characteristics and the mobility have been worked out and considered during a systematic design process. Universal building blocks with different functions were used. The final circuit architecture was selected from a shortlist of appropriate concepts based on space, efficiency and cost requirements. The result is a very flexible circuit structure, which can be easily customized to drive different actuator setups. The concept is optimized to drive both multilayer-setups by supplying an alternating voltage (switched DC), as well as single layer actuators with a DC voltage.

The architecture consists of three stages (switched-mode power supply, electromagnetic transformer and multiplier cascade) to increase a battery input voltage of 3.7 V to the needed HV. An H-bridge is integrated to adjust the output voltage amplitude by pulse width modulation. PhotoMOS relays are used to generate the alternating output voltage. The actuators may be driven with a DC signal or a rectangular voltage with variable frequency by controlling the PhotoMOS relays.

Finally, the selected concept has been realized and tested by driving the actuators. For the alternating voltage mode five outputs have been realized. In this mode, the actuators can be driven with a maximum peak voltage of 800 V. Under these conditions the switched-mode power supply provides a current of 166 mA at 5 V. For the DC-mode output, the circuit supplies a maximum voltage of approximately 3.2 kV.

To control the electronics a program in LabVIEW was implemented. The operator can adjust the amplitude and the frequency (AC-mode: 40-400 Hz) of the selected output via a graphical user interface.

An advantageous aspect of the realized concept is the fact that the AC Signal is generated just before the output by switching a DC voltage. As a result, the transformer and the multiplier circuit can be driven with their optimal specific operation frequency, independent of the AC output frequency. The circuit is also expandable to more independently switchable outputs by simply adding switching elements. Furthermore, the supply voltage is not restrained to symmetrical signals. By controlling the switching elements, any kind of rectangular pattern can be supplied. In this way versatile patterns of vibro-tactile stimuli can be offered to the user.

EMK-spezifische Daten:

Lagerort Dokument: Archiv EMK, Kontakt über Sekretariate,

Bibliotheks-Sigel: 17/24 EMKD 1723

Art der Arbeit: Diplomarbeit

Beginn Datum: 01-09-2009

Ende Datum: 16-03-2010

Querverweis: 17/24 EMKS 1712, 17/24 EMKDIS52

Studiengang: Elektrotechnik und Informationstechnik (ETiT)

Vertiefungsrichtung: Mikro- und Feinwerktechnik (MFT)

Abschluss: Diplom (MFT)