電刺激對重建偏癱患者手部功能之病人驅使命令控制策略

目前市面上有許多針對恢復病人手部功能的輔具開發，利如功能性電刺激系統就是最好的例子。本論文對於以功能性電刺激系統恢復手部動作的相關部分重要議題進行討論、研究與做更進一步的分析，以期能找出恢復手部功能的最佳策略，這些議題包括了：控制策略的探討、一套標準化的電刺激流程以找出適當的刺激位置、關於功能性電刺激系統的輸入控制源、以及專門針對臨床人員所設計的一套人機介面工具。對於現今輔具的輸入來源或是命令控制之設計，就全身癱瘓的病人而言，是不方便使用且也是很複雜的。如果能藉由一套病人驅使控制迴路的方式，讓他們使用自身的殘存能力來控制這些輔具，例如由肌肉所發出的訊號當作命令；此外，若功能性電刺激系統核心上有一最佳策略控制器的話，這對於他們而言一定是有相當大的助益。針對這些問題，我們嘗試對於功能性電刺激系統提出一最佳策略的方式與研究討論，包括有：如何利用標準化流程尋找最適合刺激位置、病人的選擇與能力評估、以及針對他們殘存功能所設計之病人驅使控制迴路設計。這套提出的概念與策略還可以不僅適用在功能性電刺激上，還可以改良應用於其他復健領域方面。我們選擇最普遍且最易被接受的訊號當作控制輸入來源，也就是肌電訊號。然而，在這之前我們必須要了解對於當使用表面主動式電極和被動式電極，肌電訊號品質以及辨識率結果上的差別。由實驗發現，使用主動式電極與被動式電極，辨識率結果是相同的且都超過83％（使用自回歸係數或是倒頻譜係數為參數）。依據此結果，我們設計了一個利用表面主動式電極的四通道肌電訊號紀錄器；此儀器結合功能性電刺激系統，肌電訊號可以當作系統的起始誘發及調整電刺激參數的依據，以增加系統的表現能力。另一方面，我們利用數位訊號處理器為核心基礎發展一可程式多通道電刺激系統，並針對臨床人員（例如臨床醫師或是物理治療師）比較不熟稔程式語言的問題，提供了使用者介面人性化和方便設計實驗操作的工具箱；工具箱裡面的參數包括了：電流強度、刺激波形設計、刺激頻率大小、以及電刺激時間等。藉由在人機介面上的參數設定，可以調整系統以達到最適合的電刺激模式；相同地，這套使用者介面人性化和方便設計實驗操作的工具箱之概念，也可以應用於其他領域上。最後，由功能性電刺激恢復手部功能的控制策略之結果發現，受試者可以成功地對於電刺激系統產生控制訊號，利用此方式來電刺激肌肉。此外，從復健以及心理學的觀點而言，病人利用他們的殘存功能來驅使輔具系統來達到控制，這對於他們來說是影響深遠地。相信病人驅使命令迴路，以及本論文之最佳策略的討論，依此病人可以對於功能性電刺激系統完成適當的控制。本論文提出的方式對於利用電刺激恢復手部功能，或是應用於其他輔具的控制上，都是有相當大的幫助。

關鍵字

人機介面；電刺激；功能性電刺激；中風；復健工程；肌電訊號；控制策略；病人驅使控制；手部功能；偏癱患者

並列摘要

Functional electrical stimulation (FES) is one of a number of methods utilized in developed assistive devices to restore patients’ lost hand functions. Some important issues about a FES system to restore hand functions have been addressed and investigated in this dissertation, including the control strategies of the system, standard procedures of finding the stimulation sites, the input sources for a FES system, and the man-machine interface designed for the clinical users. For quadriplegics, the input sources or the command controller of assistive devices are inconvenient or complicated to use. With the control strategy of patient-driven loop, they can use their residual capabilities to control these devices, such as the myoelectric signals generated from the muscles. In addition, if there is an optimal control strategy built in the controller of FES system, patients will benefit much from it. Due to the problem that quadriplegics are encumbered with the complicacy or inconvenience of the input sources and the controller commands, we have proposed the optimal strategy for FES system, including the standard procedures for finding the stimulation sites, patients’ selection, and residual capabilities for patient-driven control. This proposed concept and strategy would be useful for patients utilizing a FES system and, in addition, can be modified or applied to different rehabilitation applications. Electromyographic (EMG) signals have been chosen as in put sources to control the system since they are highly common and acceptable signals. However, there is a need to determine the differences of recognition rates and EMG recordings between using active and passive electrodes. Experimental results show that the estimated recognition rates in the passive electrodes are comparable to those in the active ones (averaged recognition rate, 88.5% vs. 85.84% in the autoregressive coefficients, and 84.84% vs. 83.5%, in the cepstral coefficients, respectively). From these findings, a four-channel recording system with the active electrode was designed for detecting EMG signals. Connecting this device with a FES system, the myoelectric signal will be able to serve both as the trigger for the system and as the adjustment of the electrical stimulation parameters to improve system performance. In addition to the recording system, a versatile LabVIEW-based toolbox was also designed for the proposed system. This toolbox can assist clinical researchers (such as the physicians or physical therapists) tune parameters such as waveform types, current intensity, stimulation time, etc, in the proposed system to provide suitable electrical stimulation. The described man-machine interface can also be implemented in other applications. From the results of the control strategy in FES system to restore hand functions, the subjects can use generate suitable control signals for the system so that the muscles will be properly excited by electrical stimulation. Moreover, in the viewpoints of rehabilitation and psychology, there is noticeable benefit from using their residual capabilities to control FES systems. It is believed that patient-driven loop as well as the discussions of optimal control strategy in this dissertation can provide suitable control to FES systems. This is very useful not only for the hand function restoration by electrical stimulation, but also for the control of other assistive devices.

並列關鍵字

Patient-driven control ； Control Strategy ； Hand function ； Electromyographic signal (EMG) ； Rehabilitation Engineering ； Man-machine interface (MMI) ； Hemiplegia ； Stroke ； Functional electrical stimulation (FES) ； Electrical stimulation

參考文獻

Abbas, J. J. (1991). Feedback control of coronal plane hip angle in paraplegic subjects using functional neuromuscular stimulation. IEEE Trans. Biomed. Eng., 38, 687-698.

Abbas, J. J. and Chizeck, H. J. (1995). Neural network control of functional neuromuscular stimulation systems: computer simulation studies. IEEE Trans. Biomed. Eng., 42, 1117-1127.

Alon, G., Dar, A., Katz-Behiri, D., Weingarden, H., and Nathan, R. (1998). Efficacy of a hybrid upper limb neuromuscular electrical stimulation system in lessening selected impairments and dysfunctions consequent to cerebral damage. J. Neuro. Rehab., 12, 73-80.

Andrews, B. J., Baxendale, R. H., Phillips, G. F., Yamazaki, T., Paul, J. P., and Freeman, P. A. (1988). Hybrid FES orthoses incorporating closed loop control and sensory feedback. J. Biomed. Eng., 10, 189-195.

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電刺激對重建偏癱患者手部功能之病人驅使命令控制策略

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