0
Research Papers

Gait Phase-Based Control for a Rotary Series Elastic Actuator Assisting the Knee Joint

[+] Author and Article Information
Joonbum Bae1

Department of Mechanical Engineering,  University of California, Berkeley, CA 94720 e-mail: jbbae@me.berkeley.eduDepartment of Mechanical Engineering,  Sogang University, Seoul, Korea 121-742 e-mail: kckong@sogang.ac.krDepartment of Mechanical Engineering,  University of California, Berkeley, CA 94720 e-mail: tomizuka@me.berkeley.edu

Kyoungchul Kong, Masayoshi Tomizuka

Department of Mechanical Engineering,  University of California, Berkeley, CA 94720 e-mail: jbbae@me.berkeley.eduDepartment of Mechanical Engineering,  Sogang University, Seoul, Korea 121-742 e-mail: kckong@sogang.ac.krDepartment of Mechanical Engineering,  University of California, Berkeley, CA 94720 e-mail: tomizuka@me.berkeley.edu

1

Corresponding author.

J. Med. Devices 5(3), 031010 (Aug 23, 2011) (6 pages) doi:10.1115/1.4004793 History: Received December 31, 2010; Revised July 18, 2011; Accepted July 26, 2011; Published August 23, 2011; Online August 23, 2011

Actuators for physical human-robot interaction (pHRI) such as rehabilitation or assistive systems should generate the desired torque precisely. However, the resistive and inertia loads inherent in the actuators (e.g., friction, damping, and inertia) set challenges in the control of actuators in a force/torque mode. The resistive factors include nonlinear effects and should be considered in the controller design to generate the desired force accurately. Moreover, the uncertainties in the plant dynamics make the precise torque control difficult. In this paper, nonlinear control algorithms are exploited for a rotary series elastic actuator to generate the desired torque precisely in the presence of nonlinear resistive factors and modeling uncertainty. The sliding mode control smoothed by a boundary layer is applied to enhance the robustness for the modeling uncertainty without chattering phenomenon. In this paper, the rotary series elastic actuator (RSEA) is installed on the knee joint of an orthosis, and the thickness of the boundary layer is changed by gait phases in order to minimize the torque error without the chattering phenomenon. The performance of the proposed controller is verified by experiments with actual walking motions.

FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 9

Experimental results with actual walking motions

Grahic Jump Location
Figure 8

Desired knee joint torque profile in one stride

Grahic Jump Location
Figure 7

The RSEA and Smart Shoes installed on the orthosis

Grahic Jump Location
Figure 6

Experimental results: the desired torque is set as a sinusoidal wave

Grahic Jump Location
Figure 5

Varying boundary layer as gait phases

Grahic Jump Location
Figure 4

Saturation function, sat(SΦ)

Grahic Jump Location
Figure 3

Schematic plot of the human joint and the RSEA

Grahic Jump Location
Figure 2

Experimental results for the motor friction test [5]

Grahic Jump Location
Figure 1

A rotary series elastic actuator (RSEA) [5]

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In