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.

The assessment techniques used for people who experience muscular issues, regardless of the cause, are crucial to resolve the issue and fill the gap left by the deficiency in their muscles. The amputees' demands in their rehabilitation process are made more evident by evaluating the residual limb muscles. The time-varying muscle activity of the amputees weakens the efficiency of using these fixed positions inside the socket, which leads to a great challenge for them to continue using the prosthesis in this case. Depending on the daily motion activity or routine of the amputees, a change in the level of muscle activation may occur because every motion activity has its dynamic that depends on muscle activity. For this purpose, a new reliable cuff system using a simple, non-invasive sensor based on a force-sensitive resistor (FSR) which can measure muscle contraction, is presented in this study. The cuff system was designed by Autodesk Inventor software and used Cura for slicing functions. This design was printed by Creator-Pro 3D printer as an FDM type. The cuff includes 8 FSR sensors printed with TPU and APL for the cube. Applying FSRs on the skin senses the mechanical force exerted by the underlying contracting muscles. Regarding FSR signals and data collection and display, Datastreamer by Microsoft Excel was used for this purpose. Five male non-amputee subjects were involved in this study to do two activities (strength muscles and gait cycle). Each activity was subjected to two tests, the first conducted above the knee, while test 2 was below the knee. Rectus femoris (RF) and tibialis anterior (TA) muscles were targeted as a positioning reference for above and below the knee tests, respectively. Through the experiments, there was no complaint from the subjects about the surface of the cuff touching the skin. Still, the issue revolved around the tightness of the cuff, especially at the aboveknee level for both activities. As thigh circumference, the cuff stretching efficiency was achieved over maximum stretch capability at 63 cm. After more than 50 trials with the two activities mentioned above, there was no change in the cuff dimensions either for maximum or minimum size, i.e., without stretching occurring. F1-all individuals for both activities displayed no appreciable signal variations and began with high levels of values, according to the signals data. That results from the tightness of the cuff on the limb. As a result of its site being unfavorable to any muscle activity, F2 presented poor signals in both activities for all participants. The cuff size needs to be reevaluated to prevent the problem of cuff tightness. The findings of the trials generally demonstrated the muscles' active locations and the change of activity taking place in those positions. On the other hand, the findings of the experiments also presented the inactive positions.