title: Inverted Pendulum Standing Apparatus for Investigating Closed-Loop Control of Ankle Joint Muscle Contractions during Functional Electrical Stimulation.
abstract: The restoration of arm-free standing in individuals with paraplegia can be facilitated via functional electrical stimulation (FES). In developing adequate control strategies for FES systems, it remains challenging to test the performance of a particular control scheme on human subjects. In this study, we propose a testing platform for developing effective control strategies for a closed-loop FES system for standing. The Inverted Pendulum Standing Apparatus (IPSA) is a mechanical inverted pendulum, whose angular position is determined by the subject's ankle joint angle as controlled by the FES system while having the subject's body fixed in a standing frame. This approach provides a setup that is safe, prevents falling, and enables a research and design team to rigorously test various closed-loop controlled FES systems applied to the ankle joints. To demonstrate the feasibility of using the IPSA, we conducted a case series that employed the device for studying FES closed-loop controllers for regulating ankle joint kinematics during standing. The utilized FES system stimulated, in able-bodied volunteers, the plantarflexors as they prevent toppling during standing. Four different conditions were compared, and we were able to show unique performance of each condition using the IPSA. We concluded that the IPSA is a useful tool for developing and testing closed-loop controlled FES systems for regulating ankle joint position during standing.
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada M5S 3G9; Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON, Canada M4G 3V9.
authors.forename: John F
authors.initials: JF
authors.lastname: Tan
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada M5S 3G9; Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON, Canada M4G 3V9.
authors.forename: Kei
authors.initials: K
authors.lastname: Masani
authors.affiliation: Department of Mechanical Engineering, University of Alberta, 4-9 Mechanical Engineering Building, Edmonton, AB, Canada T6G 2G8; Glenrose Rehabilitation Hospital, Alberta Health Services, 10230-111 Avenue, Edmonton, AB, Canada T5G 0B7.
authors.forename: Albert H
authors.initials: AH
authors.lastname: Vette
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada M5S 3G9; Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON, Canada M4G 3V9.
authors.forename: José
authors.initials: J
authors.lastname: Zariffa
authors.affiliation: Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON, Canada M4G 3V9.
authors.forename: Mark
authors.initials: M
authors.lastname: Robinson
authors.affiliation: Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON, Canada M4G 3V9; Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Lynch
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, Canada M5S 3G9; Toronto Rehabilitation Institute, University Health Network, 520 Sutherland Drive, Toronto, ON, Canada M4G 3V9.
authors.forename: Milos R
authors.initials: MR
authors.lastname: Popovic