Control strategies for integration of electric motor assist and functional electrical stimulation in paraplegic cycling: Utility for exercise testing and mobile cycling

Hunt, K.J., Stone, B., Negard, N.O., Schauer, T., Fraser, M.H., Cathcart, A.J., Ferrario, C., Ward, S.A. and Grant, S. (2004) Control strategies for integration of electric motor assist and functional electrical stimulation in paraplegic cycling: Utility for exercise testing and mobile cycling. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 12(1), pp. 89-101. (doi: 10.1109/TNSRE.2003.819955)

Abstract

<b>Aim:</b> The aim of this study was to investigate feedback control strategies for integration of electric motor assist and functional electrical stimulation (FES) for paraplegic cycling, with particular focus on development of a testbed for exercise testing in FES cycling, in which both cycling cadence and workrate are simultaneously well controlled and contemporary physiological measures of exercise performance derived. A second aim was to investigate the possible benefits of the approach for mobile, recreational cycling.<p></p> <b>Methods:</b> A recumbent tricycle with an auxiliary electric motor is used, which is adapted for paraplegic users, and instrumented for stimulation control. We propose a novel integrated control strategy which simultaneously provides feedback control of leg power output (via automatic adjustment of stimulation intensity) and cycling cadence (via electric motor control). Both loops are designed using system identification and analytical (model-based) feedback design methods. Ventilatory and pulmonary gas exchange response profiles are derived using a portable system for real-time breath-by-breath acquisition.<p></p> <b>Results:</b> We provide indicative results from one paraplegic subject in which a series of feedback-control tests illustrate accurate control of cycling cadence, leg power control, and external disturbance rejection. We also provide physiological response profiles from a submaximal exercise step test and a maximal incremental exercise test, as facilitated by the control strategy.<p></p> <b>Conclusion:</b> The integrated control strategy is effective in facilitating exercise testing under conditions of well-controlled cadence and power output. Our control approach significantly extends the achievable workrate range and enhances exercise-test sensitivity for FES cycling, thus allowing a more stringent characterization of physiological response profiles and estimation of key parameters of aerobic function. We further conclude that the control approach can significantly improve the overall performance of mobile recreational cycling.<p></p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: UNSPECIFIED
• Authors: Hunt, K.J., Stone, B., Negard, N.O., Schauer, T., Fraser, M.H., Cathcart, A.J., Ferrario, C., Ward, S.A., and Grant, S.
• Subjects: R Medicine > R Medicine (General)
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: IEEE Transactions on Neural Systems and Rehabilitation Engineering
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)
• ISSN: 1534-4320
• Copyright Holders: © Copyright IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
• First Published: First published in IEEE Transactions on Neural Systems and Rehabilitation Engineering 12(1):89-101
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
32244	1	The development of systems for paraplegic cycling: improving health after spinal cord injury	Kenneth Hunt	Engineering & Physical Sciences Research Council (EPSRC)	GR/R92462/01	SCHOOL OF ENGINEERING