Dipartimento di Elettronica e Telecomunicazioni (DET), Politecnico di Torino, 10129 Torino, Italy.
Sensors (Basel). 2020 Mar 10;20(5):1535. doi: 10.3390/s20051535.
The analysis of the surface ElectroMyoGraphic (sEMG) signal for controlling the Functional Electrical Stimulation (FES) therapy is being widely accepted as an active rehabilitation technique for the restoration of neuro-muscular disorders. Portability and real-time functionalities are major concerns, and, among others, two correlated challenges are the development of an embedded system and the implementation of lightweight signal processing approaches. In this respect, the event-driven nature of the Average Threshold Crossing (ATC) technique, considering its high correlation with the muscle force and the sparsity of its representation, could be an optimal solution. In this paper we present an embedded ATC-FES control system equipped with a multi-platform software featuring an easy-to-use Graphical User Interface (GUI). The system has been first characterized and validated by analyzing CPU and memory usage in different operating conditions, as well as measuring the system latency (fulfilling the real-time requirements with a 140 ms FES definition process). We also confirmed system effectiveness, testing it on 11 healthy subjects: The similarity between the voluntary movement and the stimulate one has been evaluated, computing the cross-correlation coefficient between the angular signals acquired during the limbs motion. We obtained high correlation values of 0.87 ± 0.07 and 0.93 ± 0.02 for the elbow flexion and knee extension exercises, respectively, proving good stimulation application in real therapy-scenarios.
表面肌电信号（sEMG）分析被广泛应用于神经肌肉障碍的功能性电刺激（FES）治疗中，作为一种主动康复技术。便携性和实时功能是主要关注点，其中两个相关的挑战是嵌入式系统的开发和轻量级信号处理方法的实现。在这方面，考虑到平均阈值穿越（ATC）技术与肌肉力量的高度相关性及其表示的稀疏性，其事件驱动的性质可能是一种最佳解决方案。在本文中，我们提出了一种带有多平台软件的嵌入式 ATC-FES 控制系统，该软件具有易于使用的图形用户界面（GUI）。该系统首先通过分析不同操作条件下的 CPU 和内存使用情况以及测量系统延迟（通过 140ms 的 FES 定义过程满足实时要求）来进行特征描述和验证。我们还通过对 11 名健康受试者进行测试来确认系统的有效性：通过比较在肢体运动过程中采集的角度信号的互相关系数，评估自愿运动和刺激运动之间的相似性。我们分别获得了肘部弯曲和膝盖伸展运动的 0.87 ± 0.07 和 0.93 ± 0.02 的高相关值，证明了在实际治疗场景中良好的刺激应用。
