title: Switched Control of Cadence During Stationary Cycling Induced by Functional Electrical Stimulation.
abstract: Functional electrical stimulation (FES) can be used to activate the dysfunctional lower limb muscles of individuals with neurological disorders to produce cycling as a means of rehabilitation. However, previous literature suggests that poor muscle control and nonphysiological muscle fiber recruitment during FES-cycling causes lower efficiency and power output at the cycle crank than able-bodied cycling, thus motivating the investigation of improved control methods for FES-cycling. In this paper, a stimulation pattern is designed based on the kinematic effectiveness of the rider's hip and knee joints to produce a forward torque about the cycle crank. A robust controller is designed for the uncertain, nonlinear cycle-rider system with autonomous, state-dependent switching. Provided sufficient conditions are satisfied, the switched controller yields ultimately bounded tracking of a desired cadence. Experimental results on four able-bodied subjects demonstrate cadence tracking errors of 0.05 ±1.59 and 5.27 ±2.14 revolutions per minute during volitional and FES-induced cycling, respectively. To establish feasibility of FES-assisted cycling in subjects with Parkinson's disease, experimental results with one subject demonstrate tracking errors of 0.43 ± 4.06 and 0.17 ±3.11 revolutions per minute during volitional and FES-induced cycling, respectively.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Bellman
authors.forename: Teng-Hu
authors.initials: TH
authors.lastname: Cheng
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Downey
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Hass
authors.forename: Warren E
authors.initials: WE
authors.lastname: Dixon
mesh_terms: D000328:Adult; D001642:Bicycling; D003198:Computer Simulation; D004599:Electric Stimulation Therapy / Q000379:methods*; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008954:Models, Biological; D009069:Movement Disorders / Q000503:physiopathology* / Q000534:rehabilitation*; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D005082:Physical Exertion; D013813:Therapy, Computer-Assisted / Q000379:methods