PROSTHETIC LEG PRESENTED BY:-AWAIS IJAZ HASNAT AHMED KHAN

PROSTHESIS Prosthesis is an artificial device extension that replaces a missing body part. It is the science of using mechanical devices with human muscle, skeleton, and nervous systems to assist or enhance motor control lost by trauma, disease, or defect.

BASIC REQUIREMENTS The prosthesis must support body weight of amputee like a normal limb Body is supported such that undesirable socket or stumps interface pressures and gait abnormalities due to painful socket/stumps contacts are prevented. Prosthesis should duplicate as nearly as possible the kinematics and dynamics of the normal gait.

THE ROBOTIC LEG: A robot in the shape of a leg capable of performing almost all the task that can be done using a normal leg. But robotic leg is far too bulky to be attached to the human body. It can perform all the work like walking, running and climbing. But it cannot be attached to the body if it is heavier. Recently interfacing between the brain and robotic leg is trying to be established and is termed as brain computer interface.

BLOCK DIAGRAM FOR WORKING OF MYOELECTRIC LEG :

W HAT IS EMG? Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle cells when these cells contract.

EXTRACTION OF EMG SIGNAL: Electromyographic (EMG) signals, collected at the skin surface, have been used for the control of upper limb prosthetic devices since 1948; because they provide easy and noninvasive access to physiological processes that cause the contraction of the muscles. At present, the process of EMG signals is the most common approach used for the control of active prosthetic parts.

ACQUISITION AND PROCESSING OF EMG SIGNAL The formal scheme for the acquisition and analysis of the EMG signal for the control of prosthetic devices is composed of several modules: signal conditioning and preprocessing feature extraction pattern recognition

EMG ELECTRODE PLACEMENT : Location and orientation of the electrode: The electrode should be placed between a motor point and the tendon insertion or between two motor points, and along the longitudinal midline of the muscle. NOT on or near the tendon of the muscle NOT on the motor point NOT at the outside edges of the muscle

Control of prosthetic leg using EMG Replicating the performance of the human leg is beyond current technical capabilities. Commercial Leg prostheses have a limited number of degree of freedoms (one or two for knee movements and ankle)

Leg

ACTUATORS AND SENSORS: The function of actuators is to trigger the myoelectric arm in accordance with the EMG which carries the information of the brain. The sensors do the vice versa. They sense the activity of the outside world and inform the brain.

ELECTRODE AND AMPLIFIER DESIGN The design of the electrode unit is the most critical aspect of the electronics apparatus which will be used to obtain the signal. The fidelity of the EMG signal detected by the electrode influences all subsequent treatment of the signal. It is very difficult (almost impossible) to improve signal-to-noise ratio of the signal beyond this point. Therefore, it is important to devise an electrode unit that provides minimal distortion and highest signal-to-noise ratio.

CONSTRUCTION OF LEG

FUTURE ENHANCEMENT: neural sensing control systems power storage & distribution neural control sensory feedback transmission design signal processing information science

CONCLUSION : Technology never puts a full stop. It is always finding new ways to improve the existing devices. It is totally justified to conclude that the myoelectric arm have surely made the life of amputee easier and convenient.