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Proceedings Paper

Control of electro-rheological fluid-based torque generation components for use in active rehabilitation devices
Author(s): Jason Nikitczuk; Brian Weinberg; Constantinos Mavroidis
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Paper Abstract

In this paper we present the design and control algorithms for novel electro-rheological fluid based torque generation elements that will be used to drive the joint of a new type of portable and controllable Active Knee Rehabilitation Orthotic Device (AKROD) for gait retraining in stroke patients. The AKROD is composed of straps and rigid components for attachment to the leg, with a central hinge mechanism where a gear system is connected. The key features of AKROD include: a compact, lightweight design with highly tunable torque capabilities through a variable damper component, full portability with on board power, control circuitry, and sensors (encoder and torque), and real-time capabilities for closed loop computer control for optimizing gait retraining. The variable damper component is achieved through an electro-rheological fluid (ERF) element that connects to the output of the gear system. Using the electrically controlled rheological properties of ERFs, compact brakes capable of supplying high resistive and controllable torques, are developed. A preliminary prototype for AKROD v.2 has been developed and tested in our laboratory. AKROD's v.2 ERF resistive actuator was tested in laboratory experiments using our custom made ERF Testing Apparatus (ETA). ETA provides a computer controlled environment to test ERF brakes and actuators in various conditions and scenarios including emulating the interaction between human muscles involved with the knee and AKROD's ERF actuators / brakes. In our preliminary results, AKROD's ERF resistive actuator was tested in closed loop torque control experiments. A hybrid (non-linear, adaptive) Proportional-Integral (PI) torque controller was implemented to achieve this goal.

Paper Details

Date Published: 11 April 2006
PDF: 12 pages
Proc. SPIE 6174, Smart Structures and Materials 2006: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, 61742C (11 April 2006); doi: 10.1117/12.659576
Show Author Affiliations
Jason Nikitczuk, Northeastern Univ. (United States)
Brian Weinberg, Northeastern Univ. (United States)
Constantinos Mavroidis, Northeastern Univ. (United States)

Published in SPIE Proceedings Vol. 6174:
Smart Structures and Materials 2006: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems
Masayoshi Tomizuka; Chung-Bang Yun; Victor Giurgiutiu, Editor(s)

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