適応制御を用いた筋の電気刺激 : 膝関節角度の制御

Functional neuromuscular stimulation (FNS) has been studied to reconstruct paralyzed limb functions. FNS means an electrical stimulation to peripheral or intramuscular nerve of paraplegic, hemiplegic and quadriplegic patients caused by spinal cord injury or brain damage. Gait, standing and other many limb functions have been regained using open-loop FNS system, but was limitted by the inaccurate contollred posture in the case with support system. An accurate joint angle and muscle contractile force control system is required especialy for stable standing without support system. For the aim of satisfying this requirement, the application of the feedback controller has been studied. Though these studies made fine joint control possible, feedback controller often brought undesirable oscilatory behavior because of the nonlinearity between stimulus amplitude and joint angle. The smoothness of the evoked movement by FNS as well as human voluntary movement, therefore, has been demanded to the control system. On the other hand, Model Reference Adaptive Control System (MRACS), one of adaptive control systems, can be used with less preparation time than coventional feedback control system because it requires no previous system identification and controller design. But the robustness of MRACS is generally inferior to conventional system while it is applied to a nonlinear subject. Some details of MRACS were modified for nonlinear properties of FNS. 1) LPF was used to suppress high freuency component of identification siganal caused by nonlinear strain. 2) The internal loop of the system was modified, which had poles in the feedback transfer function. In addition, coactivation of agonist and antagonist was applied to attain a smooth bidirectional movement of knee joint. An practical experiment of adaptive joint control with proposed FNS control system was carried out on normal subjects and paraplegic patients. A similar movement in smoothness and accuracy compared with voluntary movement was obtained.Functional neuromuscular stimulation (FNS) has been studied to reconstruct paralyzed limb functions. FNS means an electrical stimulation to peripheral or intramuscular nerve of paraplegic, hemiplegic and quadriplegic patients caused by spinal cord injury or brain damage. Gait, standing and other many limb functions have been regained using open-loop FNS system, but was limitted by the inaccurate contollred posture in the case with support system. An accurate joint angle and muscle contractile force control system is required especialy for stable standing without support system. For the aim of satisfying this requirement, the application of the feedback controller has been studied. Though these studies made fine joint control possible, feedback controller often brought undesirable oscilatory behavior because of the nonlinearity between stimulus amplitude and joint angle. The smoothness of the evoked movement by FNS as well as human voluntary movement, therefore, has been demanded to the control system. On the other hand, Model Reference Adaptive Control System (MRACS), one of adaptive control systems, can be used with less preparation time than coventional feedback control system because it requires no previous system identification and controller design. But the robustness of MRACS is generally inferior to conventional system while it is applied to a nonlinear subject. Some details of MRACS were modified for nonlinear properties of FNS. 1) LPF was used to suppress high freuency component of identification siganal caused by nonlinear strain. 2) The internal loop of the system was modified, which had poles in the feedback transfer function. In addition, coactivation of agonist and antagonist was applied to attain a smooth bidirectional movement of knee joint. An practical experiment of adaptive joint control with proposed FNS control system was carried out on normal subjects and paraplegic patients. A similar movement in smoothness and accuracy compared with voluntary movement was obtained