Low Cost Myoelectric Prosthetic Arm

The disposable surface electrodes are secured over the relevant muscles on the body surface, after initial skin preparation. These electrodes pick up the voltages produced by the contracting muscles.

The threshold value for control of the prosthetic hand was set at 300 by taking the average of maximum and minimum values. The prosthetic hand is activated when the sEMG signal exceeds the threshold value that is fixed while the muscles are contracted.

Actuation of the arm is done by comparing varying EMG signals with a set EMG threshold value.

Two force sensing resistors (FSR) are placed on the tip of fingers, one each for the index finger and thumb. A threshold FSR value is set.

• • When the value of these two FSR becomes greater than the threshold value, i.e. the arm is holding an object with a firm grip, the motors are programmed to stop its rotation. Thus, it is achievable to detect grasps. Hence the hand is capable to achieve a stable grasp.

A delay of 10 seconds is set to check if the EMG value is more than the EMG threshold value.