Myoelectric Prosthetic

The myoelectic prosthetic project consists of a skin patch myoelectric signal collection module and contactless transmission system providing emulation of the electric signals used to control current elbow, cuff, gripper arms and also supporting additional control functions for future prosthetic arm functionality.
An adhesive patch is applied to the skin at a point where it has been found to have optimum control. These signals are processed and sent over a short distance wireless link to a unit mounted on the prosthetic.

This project sets out to achieve a balance between a flexible, usable hand and a control system using myoelectric pickup. All of the prosthetic motion control we researched uses 'joint' control. The user activates each joint in turn in order to get the 'end point' or 'fingertips' to a desired location. This is in contrast to the normal human movement in which fingertips are moved in three dimensional space without awareness of the specific joint angles to get there.
This method of control is preferred in programming robotic arms. The joint positions of the arm are calculated using inverse kinematics.

A myoelectric  signal, although low voltage and subject to hum and other pickup, is proportional to the intensity of the muscle contraction and present throughout contraction. This renders it very suitable for simple analogue control systems and allows users to apply appropriate force using a combination of learned behaviour and visual feedback. Myoelectic signals are generated for all muscles although only a selection of muscles are on the surface where the signals can be picked up by skin contact.

One of our main aims during this project has been to create a skin patch that would pick up myoelectic control signals  in a reliable manner for more precision in prosthetic control.The pickup of relatively few myoelectric signal channels from selected muscle groups, and the application of robotic control derived techniques, enables a combination of signals from these channels to provide multiple functions.



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