McKibben Artificial Muscles

Abstract

The McKibben Artificial Muscle is a pneumatic actuator which exhibits many of the properties found in real muscle. Its spring-like characteristics, physical flexibility, and light weight make it ideal for applications such as the Anthroform Biorobotic Arm and Powered Prosthetics Project. The device was first developed for use in artificial limbs in the 1950's and, more recently, was commercialized in the 1980's by Bridgestone Rubber Company of Japan and in the 1990's by the Shadow Robot Group of England for robotic applications. Versions of the actuator are also available from Images Company. Among the more attractive attributes of the actuator is a very high force to weight ratio, making it ideal mobile robots.

Research Activities

Actuator Construction - The device consists of an expandable internal bladder (an elastic tube) surrounded by a braided shell. When the internal bladder is pressurized, it expands in a balloon-like manner against the braided shell. The braided shell acts to constrain the expansion in order to maintain a cylindrical shape. As the volume of the internal bladder increases due to the increase in pressure, the actuator shortens and/or produces tension if coupled to a mechanical load. These actuators can be easily constructed in a variety of sizes or you can buy them ready to use.

Finite Element Models - By using a finite element model approach, we can estimate the interior stresses and strains of the McKibben actuator. Knowledge of these details have lead to improved actuator designs.

Fatigue Properties - A typical application often requires a significant number of repeated contractions and extensions of the actuator. This repeated cycling leads to fatigue and failure of the actuator, yielding a specific life span that is an important design consideration. Our results found that natural latex bladders have a fatigue limit 24 times greater than synthetic silicone rubber bladders.

Performance Characteristics - The force generated by a McKibben Artificial Muscle is dependent on the weave characteristics of the braided shell, the material properties of the elastic tube, the actuation pressure, and the muscle's length.

Artificial versus Biological Muscle - The force-length properties of the McKibben actuator are reasonably close to biological muscle. However, the force-velocity properties are not. We have designed a hydraulic damper to operate in parallel with the McKibben actuator to produce the desired results.

Anthroform Arm Project

Powered Prosthetics Project

(*) Note: Most of the BRL publications are available on-line in a PDF format. You may used the publication's reference number as a link to the individual manuscript.


[064]
C.P. Chou, B. Hannaford, 'Dual Stable Point Model of Muscle Activation and Deactivation,' Biological Cybernetics, vol. 66, pp. 511-523, 1992.

[077]
C.P. Chou, B. Hannaford, 'Static and Dynamic Characteristics of McKibben Pneumatic Artificial Muscles,' Proc. IEEE Intl. Conf. on Robotics and Automation, San Diego, CA, May, 1994.

[080]
C.P. Chou, B. Hannaford, 'Measurement and Modeling of McKibben Pneumatic Artificial Muscles,' IEEE Transactions on Robotics and Automation, vol. 12, pp. 90-102, Feb. 1996.

[091]
B. Hannaford, J.M. Winters, C.P. Chou, P.H. Marbot, 'The Anthroform Arm: A System for the Study of Spinal Circuits,' Annals of Biomedical Engineering: L. Stark Special Issue, vol. 23, pp. 399-408, March 1995.

[116]
G. Klute, B. Hannaford, 'Fatigue Characteristics of McKibben Artificial Muscle Actuators,' Proceedings. IROS-98, pp. 1776-82, Victoria, B.C., Canada, Nov. 1998.

[123]
G.K. Klute, J. Czerniecki, B. Hannaford, 'Development of Powered Prosthetic Lower Limb,' Proc. 1st National Mtg, Veterans Affairs Rehab. R&D Service, Washington, DC, October 1998.

[129]
G.K. Klute, J.M. Czerniecki, B. Hannaford, 'McKibben Artificial Muscles: Pneumatic Actuators with Biomechanical Intelligence,' IEEE/ASME 1999 Intl. Conf. on Advanced Intelligent Mechatronics, Atlanta GA, September 19-22, 1999.

[131]
G.K. Klute, B. Hannaford, 'Accounting for Elastic Energy Storage in McKibben Artificial Muscle Actuators,' ASME Journal of Dynamic Systems, Measurements, and Control, vol. 122, pp. 386-388, June 2000.

[147]
G. Klute, J. Czerniecki, B. Hannaford, 'Artificial tendons: biomechanical design properties for prosthetic lower limbs,' and World Congress on Medical Physics and Biomedical Engineering, vol. 3, pp. 1972-5, IEEE, Chicago, July 24-28, 2000.

[150]
B. Hannaford, G. Klute, K. Jaax, 'Bio-inspired Actuation and Sensing,' Autonomous Robots (Special Issue, Papers from the JPL workshop on Biomorphic Robotics, August 2000), vol. 11, pp. 267-272, Kluwer Academic Publishers, Boston/Dordrecht/London, November 2001.

[Th017]
C.P. Chou, 'Study of Human Motion Control with a Physiologically Based Robotic Arm and Spinal Level Neural Controller,' Ph.D. Dissertation, University of Washington, Department of Electrical Engineering, June 1996.