Artificial hand using embedded system

Microcontroller and microprocessor places an important role in all types of control applications. Embedded system is a combination of hardware using a Microprocessor and the suitable software along with some kind of additional mechanical or other electronic parts designed to perform specific task. The embedded system places a vital role in this prosthetic hand.

The main factors for a loss of an upper extremity are accidents followed by general diseases and injuries from war for the individual the loss of an upper limb results in a drastic restriction of function and cosmoses.

Therefore in the last 3 decades an increasing number of handicapped persons have been provided with prosthetic hands that have the shape of a human hand and that are actuated by a DC motor with reduction gear trains However surveys on using such artificial hands revealed that 30 to50% of the of the handicapped persons do not use their prosthetic hand regularity The main factors for the rejection of conventional prosthetic hands were

Heavy weight:

Although commercial prosthetic hands have about the same mass as human hands they appear to be unpleasantly heavy because a lever arm to the short stump of the amputated arm transmits the mass.

Low functionality:

A human hand can perform a large variety of different grip movements while conventional prosthetic hands can only perform a single pincer-like grip movement Therefore the grasping abilities are restricted, so it is for example impossible to pick up a pinball with the artificial hand

Cost:

The costs of imported motorised hands, however, are prohibitive and it can be more than 3.00 lakhs. We are using the hydraulic pump for exiting the air for specified action The servomotor drives the pump.

EMG Electrodes:

EMG is an acronym of electromagnetic, these electrodes are used to sense the electric field generated on the muscles .The electric fields that occur in living tissue are caused by charge separation electrolytes and not by the movement of electrons using silver chloride electrodes on the skin and couple it with a conducting gels we can sense the voltage at the location

Instrumentation amplifier:

The magnitude of the voltage is related to how much subcutaneous muscle contracts the problem that remains that the electrodes produces a very small signal at best few millivolts The instrumentation amplifier is necessary for providing the high input impedance, high common mode rejection ratio and gain necessary to extract the bio potential signal produced by the contracting muscle

Analogue to digital converter:

Signals from instrumentation amplifier are in the form of analogue for accurate control of artificial hand we need Microcontroller for computations generally microcontrollers are worked only with digital signals. So we need to convert signal from the instrumentation amplifier in to digital form through analogue to digital converter (ADC) in this project we use successive approximation type

of ADC

Microcontroller:

The 8051 is a low cost microcontroller and also it has 4KB of flash memory two-timer and counters, and four ports respectively it just get the binary value from the ADC and generate control signals to the motors and get the feedbacks from the sensors placed in our artificial hand

Servomotors and hydraulic actuators:

A servomotor is an electromechanical device in which an electrical input determines the position of the armature of the motor Servo Motors are used extensively in robotics and cars, airplanes and bowls. Here small size of servomotors is used to give the force to the oil filled hydraulic actuators for specified action the elaborated explanations about hydraulic actuators will be discussed in the following sections

CONTENT BY: ASHUTOSH JADIA [SYBAF-B  8008]

EDITED BY: SHREYA ISHER [SYBAF-B 8001]

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