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Research Student - Yee Harn Teh

Photos of myself together with the current SMA experimental test bed

Our current SMA experimental test bed

The upper part of the test bed

The lower part of the test bed

A closer look at the load cells

Education Background

My name is Yee Harn, Teh. I am currently a Ph. D. candidate at the Department of Information Engineering in the Research School of Information Sciences and Engineering (RSISE) at The Australian National University (ANU). I have graduated with a B. Engineering (Mechatronic System) at ANU in 2003 with First Class Honours.

My research interests include Robotics, Control Theory, Shape Memory Alloys and Human-Computer Interface. My PhD thesis is about Shape Memory Alloys (SMA). Dr. Roy Featherstone and Dr. Zbigniew Stachurski are my supervisors.

Shape Memory Alloys

Imagine a small 1mm-diameter wire that can lift a weight of 15 kg for millions of cycles. Imagine a device that is smaller, lighter and cheaper, and yet produces 1,000 times the work density of an electromagnet motor. These are the characteristics of actuators based on Shape Memory Alloys (SMAs). Actuators are devices which transform an input signal (usually an electrical signal) into motion. These SMA linear actuators can be used in applications ranging from electronics, medical devices, space applications, automotive applications to consumer appliances and toys, where reliable and repeatable motion is required.

Shape Memory Alloys are a group of metallic materials which have the special ability to ‘remember’ or retain their original shape, prior to deforming, by heating. This phenomenon makes them useful for actuator applications. Advantages of SMA actuators include mechanical simplicity and compactness, spark-free and silent operation unlike motors and gears, and high force-to-weight ratio. As an actuator, an SMA wire with a diameter of 1 mm can lift a weight of 15 kg. Few technologies can match that.

Actuating the SMA wires is achieved by passing an electric current through the material. The bigger the current, the faster the heating, and so faster motion is achieved. However, large currents can overheat and damage the actuators. Two of the most common problems of using SMA actuators are its slow speed and inaccuracy. The research objective of my PhD studies is to improve the performance of these actuators by designing and implementing better control systems.

The SMA Experimental Test Bed

This SMA experimental test bed was custom-designed and built in our lab. It has been used for some of our recent experiments such as the frequency response analysis on SMA wire actuators, the force control experiments as well as the motion control experiments of an antagonistic SMA wire pair. Photos of the test bed are on the left.

The test bed can accommodate two SMA wire actuators in an antagonistic setup connected via a pulley on the top. Two drive amplifiers deliver heating currents to the SMA actuators independently and also provide electrical resistance measurements of the SMA. There is a PC that runs Matlab Simulink to implement the control systems which we desire and a dSPACE DS1104 real-time control board that provides the interface between the PC and the test bed.

At the bottom of the test bed, there are two load cells, one for each SMA wire, that provide the force measurements exerted by the SMA. Each load cell has a high bandwidth of 140Hz, a +/- 9N force range and a resolution of 0.3mN.

At the upper part of the test bed, we have a linear slide that can move the pulley and shaft vertical. It allows us to simulate motion disturbances and any strain profile which we desired. The slide has micron precision and a bandwidth of 30Hz. The pulley can be locked mechanically for force control, but it can also be unlocked for motion control experiments. An encoder attached to the pulley and shaft housing measures the rotation. It is also possible to attach an inertial load to the pulley as shown in the photos.

For more information about our SMA research and results, please visit this link .

Departmental Seminar 12 December 2006

Roy and I have recently given a joint departmental seminar on 12 December 2006 on our SMA research and results over the past four years. For further information about the seminar , please visit this link. The site also contains our seminar slides and a video clip (175MB) of the seminar.

Publications

Y. H. Teh & R. Featherstone 2007. Frequency Response Analysis of Shape Memory Alloy Actuators. International Conference on Smart Materials and Nanotechnology in Engineering (SMN'07), Harbin, China, 1-4 July 2007.

Y. H. Teh & R. Featherstone 2007. An Architecture for Fast and Accurate Control of Shape Memory Alloy Actuators. Recently submitted for review in the International Journal of Robotics Research (IJRR).

Y. H. Teh & R. Featherstone 2007. Accurate Force Control and Motion Disturbance Rejection of Shape Memory Alloy Actuators. IEEE International Conference on Robotics and Automation (ICRA'07), Rome, Italy, 10-14 April 2007.

Y. H. Teh & R. Featherstone 2005. Experiments on the Audio Frequency Response of Shape Memory Alloy Actuators. Australasian Conf. Robotics and Automation (ACRA'05), Sydney, Australia, 5-7 December 2005.

Y. H. Teh & R. Featherstone 2004. Experiments on the Performance of a 2-DOF Pantograph Robot Actuated by Shape Memory Alloy Wires. Australasian Conf. Robotics and Automation (ACRA'04), Canberra, Australia, 6-8 December 2004.

Y. H. Teh & R. Featherstone 2004. A New Control System for Fast Motion Control of SMA Actuator Wires.Shape Memory And Related Technologies (SMART'04), Singapore, 24-26 November 2004.

R. Featherstone & Y. H. Teh 2004. Improving the Speed of Shape Memory Alloy Actuators by Faster Electrical Heating. Int. Symp. Experimental Robotics (ISER'04), Singapore, 18-21 June 2004.

Y. H. Teh 2003. A Control System for Achieving Rapid Controlled Motions from Shape Memory Alloy (SMA) Actuator Wires. B. Engineering Honours Thesis, Dept. Engineering, The Australian National University, Australia, 2003.

Contact Information

Address:
Department of Information Engineering,
RSISE, Building 115,
Cnr. Daley and North Road,
ANU, Canberra,ACT 0200,
AUSTRALIA.

Phone:
+61 2 6125 6800

Fax:
+61 2 6125 8660

E-mail:
USERID = yee.teh
DOMAIN = rsise
USERID@DOMAIN.anu.edu.au

Resume

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Page last updated 8 May 2007.

Links

ANU Website
RSISE Website
Dr. Roy Featherstone Dr. Zbigniew Stachurski