Title: Model-based position control of shape memory alloy actuators

Authors: Reimund Neugebauer; Kenny Pagel; Andre Bucht; Welf-Guntram Drossel

Addresses: Department of Adaptronics and Acoustics, Fraunhofer Institute for Machine Tools and Forming Technology, Nöthnitzer Straße 44, 01187 Dresden, Germany. ' Department of Adaptronics and Acoustics, Fraunhofer Institute for Machine Tools and Forming Technology, Nöthnitzer Straße 44, 01187 Dresden, Germany. ' Department of Adaptronics and Acoustics, Fraunhofer Institute for Machine Tools and Forming Technology, Nöthnitzer Straße 44, 01187 Dresden, Germany. ' Department of Adaptronics and Acoustics, Fraunhofer Institute for Machine Tools and Forming Technology, Nöthnitzer Straße 44, 01187 Dresden, Germany

Abstract: Shape-memory-alloys (SMAs) are easy to integrate into mechanical structures and capable of handling high specific workloads. Therefore, SMAs possess an outstanding potential to serve as positioning devices in various applications. We present here the multi-domain modelling of an electrically heated SMA wire which includes changes of electrical parameters in conjunction to mechanical parameters. Due to the correlation between electrical resistance and mechanical stroke, it was possible to implement a resistance-based position control without the necessity of an external positioning sensor. In order to design a linear position controller by common rules, the highly complex and non-linear model was simplified. Controller development yielded a PID algorithm that was implemented on a rapid prototyping system as part of an SMA wire test bench. The models accuracy was verified by various measurements with different wires and multiple loads. Based on that, it was possible to design an actuator which utilises a flexible socket instead of fixed mountings.

Keywords: mechatronics; shape memory alloys; heated SMA wire; model-based control; actuators; length-resistance correlation; resistance-based position control; modelling; controller design; rapid prototyping; flexible sockets.

DOI: 10.1504/IJMMS.2012.046521

International Journal of Mechatronics and Manufacturing Systems, 2012 Vol.5 No.2, pp.93 - 105

Received: 26 Jan 2011
Accepted: 30 Aug 2011
Published online: 20 Aug 2014 *

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