Fast SMA Motion Project



SMA actuated pantograph robot and accompanying equipment
The SMA Loudspeaker Testbed for SMA force control experiments
Our SMA-actuated 2-DoF pantograph robot
The SMA loudspeaker
Our new testbed for force and motion control experiments

Project Team:
Partners:

Project Description:

Actuators based on shape memory alloys (SMA) can be small, simple, cheap, clean, silent, and have high force-to-weight ratios; but they also have disadvantages, including low efficiency, low speed and low accuracy.  This project aims to improve the speed and accuracy of such actuators, so they can be used in robots, medical devices, consumer electronics, and so on.  Our actuators employ antagonistic pairs of FlexinolTM wires, which are made of a nickel-titanium SMA called nitinol.  These wires can be stretched easily when cool, but contract forcibly to their original length when heated.  The big challenge is to develop control systems that deliver fast and accurate tracking of force and motion command signals.  This is not easy, because SMAs exhibit highly nonlinear behaviour, including substantial hysteresis, which makes them very difficult to control.

Results:

Publications:

  1. Y. H. Teh 2003.  A Control System for Achieving Rapid Controlled Motions From Shape Memory Alloy (SMA) Actuator Wires.  B.Eng. Honours Thesis, Dept. Engineering, The Australian National University.  Full Text.
  2. R. Featherstone & Y. H. Teh 2004.  Improving the Speed of Shape Memory Alloy Actuators by Faster Electrical Heating.  Int. Symp. Experimental Robotics, Singapore, 18-21 June 2004.  Full TextSlides.
  3. Y. H. Teh & R. Featherstone 2004.  A New Control System for Fast Motion Control of SMA Actuator Wires.  Shape Memory And Related Technologies (SMART 2004), Singapore, 24-26 November 2004.  Full TextSlides (powerpoint).
  4. 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 2004), Canberra, Australia, 6-8 December 2004.  Full Text.
  5. Y. H. Teh & R. Featherstone 2005.  Experiments on the Audio Frequency Response of Shape Memory Alloy Actuators.  Australasian Conf. Robotics and Automation (ACRA 2005), Sydney, Australia, 5-7 December 2005.  Full Text.
  6. Y. H. Teh & R. Featherstone 2007.  Accurate Force Control and Motion Disturbance Rejection for Shape Memory Alloy Actuators.  IEEE Int. Conf. Robotics and Automation, Rome, Italy, 10-14 April, pp. 4454-4459.  DOI(Note: the SMA model shown in this paper is not correct.  The correct model appears in publications 7 and 9.)
  7. Y. H. Teh & R. Featherstone 2007.  Frequency Response Analysis of Shape Memory Alloy Actuators.  Int. Conf. Smart Materials and Nanotechnology in Engineering (SMN 2007), Harbin, China, 1-4 July.  Also in Proc. SPIE vol. 6423, p. J4232, 2007.  Full Text.
  8. Y. H. Teh & R. Featherstone 2008.  An Architecture for Fast and Accurate Control of Shape Memory Alloy Actuators.  Int. J. Robotics Research, vol. 27, no. 5, pp. 595-611.  DOIFull Text.
  9. Y. H. Teh 2008.  Fast, Accurate Force and Position Control of Shape Memory Alloy Actuators.  Ph.D. Thesis, Dept. Information Engineering, The Australian National University.  Full Text.
  10. S. Toru 2008.  Fast and Accurate Position Control of Shape Memory Alloy Actuators.  Research Internship Report, Dept. Information Engineering, The Australian National University.  Full Text.

Talks:

  1. Seminar: High Performance Force Control for Shape Memory Alloy (SMA) Actuators
  2. Achieving High Performance from SMA Actuators.  2011.  (30 min)  AbstractSlidesSlides X4.  Presented at IEEE ICRA 2011 Workshop on Biologically-Inspired Actuation.

Useful Links:

Conclusion:

This project was active from 2003 to 2008.  In that time, we developed an entirely new force control system that achieved both excellent speed and ground-breaking accuracy.  Furthermore, it achieved this level of performance while simultaneously protecting the SMA wires from overheating and from mechanical overload.  We also had a bit of fun with the SMA loudspeaker; and we developed a stiffness controller that was almost as good as the force controller.  However, our position controllers were either fast but inaccurate, or accurate but slow.  Many interesting ideas were developed during the course of this project, which are now influencing subsequent research (e.g. see talk 2).


Page last modified:  April 2012
Author: Roy Featherstone