Development of a Real-Time Tunable Spring - Toward Independent Control of Position and Stiffness of Joints -

Takuya Umedachi; Yasutake Yamada; Akio Ishiguro

doi:10.20965/jrm.2007.p0027

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JRM Vol.19 No.1 pp. 27-33

doi: 10.20965/jrm.2007.p0027

(2007)

Paper:

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Development of a Real-Time Tunable Spring - Toward Independent Control of Position and Stiffness of Joints -

Takuya Umedachi^*, Yasutake Yamada^**, and Akio Ishiguro^*

^*Department of Electrical and Communication Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan

^**Logistic & Automation Division, Murata Machinery, Ltd., 2 Nakajima, Hashizume, Inuyama, Aichi 484-8502, Japan

Received:

October 26, 2005

Accepted:

July 18, 2006

Published:

February 20, 2007

Keywords:

independent control of position and stiffness, real-time tunable spring, antagonistic mechanism, artificial muscle

Abstract

Traditionally, robot control has been done typically by “highly precise control algorithms”: their joint angle trajectories are accurately determined at any time with vast amount of computation. This, however, causes serious problems, particularly in terms of adaptability and energy efficiency. On the other hand, an extreme approach has been gaining a lot of attention recently. A good instantiation is the passive dynamic walker, driven only by exploiting the intrinsic dynamics of its mechanical system. However, mechanical system is not everything as well as control system is not everything: “well-balanced” coupling between control and mechanical systems should be considered. In addition, the “meeting point” between the two systems should be varied according to the environment encountered. In light of these facts, this study particularly focuses on the stiffness of robots’ joints, since this strongly contributes to tuning the dominance relationship between control and mechanical systems. More specifically, the aim of this study is to develop a “Real-time tunable spring” that can smoothly change its elasticity without changing its natural length, allowing robot’s joints to change their position and stiffness independently.

Cite this article as:

T. Umedachi, Y. Yamada, and A. Ishiguro, “Development of a Real-Time Tunable Spring - Toward Independent Control of Position and Stiffness of Joints -,” J. Robot. Mechatron., Vol.19 No.1, pp. 27-33, 2007.

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References

[1] T. Morita and S. Sugano, “Mechanical Softness and Compliance Adjustment,” JRSJ, Vol.17, No.6, pp. 790-794, 1999.
[2] K. Koganezawa and Y. Shimizu, “Mechanical Stiffness Control of Tendon Driven Multi-DOF joint by the Actuator with Non Linear Elastic System,” JRSJ, Vol.22, No.8, pp. 1043-1049, 2004.
[3] T. Shirai, S. Tanaka, and T. Ito, “Control of Joint Stiffness, Torque and Joint Angle by Using Non-Linear Spring SAT,” Proceeding of the 2005 JSME Conference on Robotics and Mechatronics, 1A1-N-075, 2005.
[4] J. W. Hurst, J. E. Chestnutt, and A. A. Rizzi, “An Actuator with Physically Variable Stiffness for Highly Dynamic Legged Locomotion,” Proceedings of the 2004 IEEE International Conference on Robotics and Automation, 2004.
[5] G. Tonietti, R. Schiavi, and A. Bicchi, “Design and Control of Variable Stiffness Actuator for Safe and Fast Physical Human/Robot Interaction,” Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 2005.
[6] S. A. Migliore, E. A. Brown, and S. P. DeWeerth, “Biologically Inspired Joint Stiffness Control,” Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 2005.
[7] T. Matsuda and S. Murata, “Antagonistic Variable Stiffness Joint Using Noncircular Gears,” Proceedings of the 23rd Annual Conference of the Robotics Society of Japan, 2005.

This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.

[1] [1] T. Morita and S. Sugano, “Mechanical Softness and Compliance Adjustment,” JRSJ, Vol.17, No.6, pp. 790-794, 1999.

[2] [2] K. Koganezawa and Y. Shimizu, “Mechanical Stiffness Control of Tendon Driven Multi-DOF joint by the Actuator with Non Linear Elastic System,” JRSJ, Vol.22, No.8, pp. 1043-1049, 2004.

[3] [3] T. Shirai, S. Tanaka, and T. Ito, “Control of Joint Stiffness, Torque and Joint Angle by Using Non-Linear Spring SAT,” Proceeding of the 2005 JSME Conference on Robotics and Mechatronics, 1A1-N-075, 2005.

[4] [4] J. W. Hurst, J. E. Chestnutt, and A. A. Rizzi, “An Actuator with Physically Variable Stiffness for Highly Dynamic Legged Locomotion,” Proceedings of the 2004 IEEE International Conference on Robotics and Automation, 2004.

[5] [5] G. Tonietti, R. Schiavi, and A. Bicchi, “Design and Control of Variable Stiffness Actuator for Safe and Fast Physical Human/Robot Interaction,” Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 2005.

[6] [6] S. A. Migliore, E. A. Brown, and S. P. DeWeerth, “Biologically Inspired Joint Stiffness Control,” Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 2005.

[7] [7] T. Matsuda and S. Murata, “Antagonistic Variable Stiffness Joint Using Noncircular Gears,” Proceedings of the 23rd Annual Conference of the Robotics Society of Japan, 2005.

Development of a Real-Time Tunable Spring - Toward Independent Control of Position and Stiffness of Joints -

Takuya Umedachi*, Yasutake Yamada**, and Akio Ishiguro*

Takuya Umedachi^*, Yasutake Yamada^**, and Akio Ishiguro^*