Sobh Khaled Nedal Mahmoud, Abd Razak Nasrul Anuar, Abu Osman Noor Azuan
Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia.
Proc Inst Mech Eng H. 2021 Apr;235(4):419-427. doi: 10.1177/0954411920985753. Epub 2021 Jan 30.
Electromyography signal has been used widely as input for prosthetic's leg movements. C-Leg, for example, is among the prosthetics devices that use electromyography as the main input. The main challenge facing the industrial party is the position of the electromyography sensor as it is fixed inside the socket. The study aims to investigate the best positional parameter of electromyography for transtibial prosthetic users for the device to be effective in multiple movement activities and compare with normal human muscle's activities. DELSYS Trigno wireless electromyography instrument was used in this study to achieve this aim. Ten non-amputee subjects and two transtibial amputees were involved in this study. The surface electromyography signals were recorded from two anterior and posterior below the knee muscles and above the knee muscles, respectively: tibial anterior and gastrocnemius lateral head as well as rectus femoris and biceps femoris during two activities (flexion and extension of knee joint and gait cycle for normal walking). The result during flexion and extension activities for gastrocnemius lateral head and biceps femoris muscles was found to be more useful for the control subjects, while the tibial anterior and also gastrocnemius lateral head are more active for amputee subjects. Also, during normal walking activity for biceps femoris and gastrocnemius lateral head, it was more useful for the control subjects, while for transtibial amputee subject-1, the rectus femoris was the highest signal of the average normal walking activity (0.0001 V) compared to biceps femoris (0.00007 V), as for transtibial amputee subject-2, the biceps femoris was the highest signals of the average normal walking activity (0.0001 V) compared to rectus femoris (0.00004 V). So, it is difficult to rely entirely on the static positioning of the electromyography sensor within the socket as there is a possibility of the sensor to contact with inactive muscle, which will be a gap in the control, leading to a decrease in the functional efficiency of the powered prostheses.
肌电信号已被广泛用作假肢腿部运动的输入信号。例如，C-Leg就是以肌电信号作为主要输入信号的假肢装置之一。产业界面临的主要挑战是肌电传感器的位置，因为它固定在接受腔内。本研究旨在探究经胫截肢者使用假肢时，肌电信号的最佳位置参数，以使该装置在多种运动活动中有效，并与正常人的肌肉活动进行比较。本研究使用DELSYS Trigno无线肌电仪器来实现这一目标。本研究纳入了10名非截肢受试者和2名经胫截肢者。分别在膝关节下方和上方的两块前侧和后侧肌肉记录表面肌电信号：胫骨前肌、腓肠肌外侧头以及股直肌和股二头肌，记录两种活动（膝关节屈伸以及正常行走的步态周期）过程中的信号。结果发现，对于对照组受试者，腓肠肌外侧头和股二头肌在屈伸活动中的信号更有用，而对于截肢受试者，胫骨前肌和腓肠肌外侧头更为活跃。此外，在正常行走活动中，股二头肌和腓肠肌外侧头的信号对对照组受试者更有用，而对于经胫截肢受试者-1，股直肌是正常行走活动平均信号中最高的（0.0001 V），高于股二头肌（0.00007 V），对于经胫截肢受试者-2，股二头肌是正常行走活动平均信号中最高的（0.0001 V），高于股直肌（0.00004 V）。因此，完全依赖肌电传感器在接受腔内的静态定位是困难的，因为传感器有可能接触到不活动的肌肉，这将导致控制方面的差距，从而降低动力假肢的功能效率。
