基于功能性电刺激的腕关节震颤抑制自适应重复控制研究

Adaptive repetitive control of wrist tremor suppression based on functional electrical stimulation

震颤是肢体一种非自主和重复性的摆动动作,在基于功能性电刺激(FES)的震颤抑制系统中可将其视为周期性扰动信号。因此,利用重复控制器调节施加在相应肌肉上的FES强度和时间,从而产生与震颤运动反相的肌肉力矩,是震颤抑制的一种可行手段。目前,大多数基于FES的重复控制系统都假设震颤是固定的单一频率信号,但实际上震颤可能是多频率信号,且震颤频率也会随时间变化。本文从频率角度对意向性震颤患者数据进行分析,提出了内模切换的自适应重复控制器来抑制不同频率的腕关节震颤。仿真和试验结果表明,所提出的并联多内模和串联高阶内模切换的自适应重复控制对多频率和单频率震颤信号可实现平均84.98%的抑制效果,比传统单内模重复控制器和基于滤波的反馈控制器在震颤抑制性能上均有明显提高。因此本文所提基于FES的自适应重复控制方法可以更为有效地解决意向性震颤患者腕部震颤问题,为患者后续运动功能障碍的康复提供有效的技术支撑。

Tremor is an involuntary and repetitive swinging movement of limb,which can be regarded as a periodic disturbance in tremor suppression system based on functional electrical stimulation(FES).Therefore,using repetitive controller to adjust the level and timing of FES applied to the corresponding muscles,so as to generate the muscle torque opposite to the tremor motion,is a feasible means of tremor suppression.At present,most repetitive control systems based on FES assume that tremor is a fixed single frequency signal,but in fact,tremor may be a multifrequency signal and the tremor frequency also varies with time.In this paper,the tremor data of intention tremor patients are analyzed from the perspective of frequency,and an adaptive repetitive controller with internal model switching is proposed to suppress tremor signals with different frequencies.Simulation and experimental results show that the proposed adaptive repetitive controller based on parallel multiple internal models and series high-order internal model switching can suppress tremor by up to 84.98%on average,which is a significant improvement compared to the traditional single internal model repetitive controller and filter based feedback controller.Therefore,the adaptive repetitive control method based on FES proposed in this paper can effectively address the issue of wrist intention tremor in patients,and can offer valuable technical support for the rehabilitation of patients with subsequent motor dysfunction.