Multichannel FES parameterization for controlling foot motion in paretic gait

• Main Authors: Seel Thomas, Ruppel Mirjana, Valtin Markus, Schauer Thomas
• Format: Article
• Language: English
• Published: De Gruyter 2015-09-01
• Series: Current Directions in Biomedical Engineering
• Subjects: Biomedical Engineering; Functional Electrical Stimulation; Neuroprosthetics; Motor Rehabilitation; Drop Foot Syndrome; Systems and Control Engineering; Multivariable Systems; Decentralized Control
• Online Access: http://www.degruyter.com/view/j/cdbme.2015.1.issue-1/cdbme-2015-0115/cdbme-2015-0115.xml?format=INT
• ISSN: 2364-5504

Stroke and other neurological disorders often lead to reduced motor function and to pathological foot motion during gait. We consider Functional Electrical Stimulation (FES) of the shank muscles that control dorsiflexion (related to pitch) and eversion (related to roll) of the foot. We describe the nonlinear domain of stimulation intensities that are tolerated by subjects in combined two-channel FES via surface electrodes. Two piecewise linear parameterizations of this domain are suggested and compared in terms of the cross-couplings between the newly defined stimulation intensity coordinates and the foot motion caused during swing phase in drop foot patients walking on a treadmill. Both parameterizations are found to yield almost monotonous input-output behavior and therefore facilitate decentralized control of the foot pitch and roll angle.