ABSTRACT:

Microelectromechanical systems (MEMS) (also written as micro-electro-mechanical, Micro Electro Mechanical or microelectronic and microelectromechanical systems) is the technology of very small mechanical devices driven by electricity and it merges at the nano scale into nano electromechanical systems (NEMS) and nanotechnology.

MEMS are separate and distinct from the hypothetical vision of molecular nanotechnology or molecular electronics. MEMS are made up of components between 1 to 100 micrometers in size (i.e. 0.001 to 0.1 mm) and MEMS devices generally range in size from 20 micrometers (20 millionths of a meter) to a millimeter. They usually consist of a central unit that processes data, the microprocessor and several components that interact with the outside such as micro sensors.

The main aim of this project is to control the wheel chair using MEMS. The MEMS will be fixed to the hand. Whenever the hand moves in any direction, the mechanical movement of the hand will be recognized by MEMS. MEMS convert this mechanical hand movement into equivalent electrical signals(X, Y, Z coordinates) and send it to the microcontroller. The communication between microcontroller and MEMS is i2c protocol. In this protocol microcontroller acts as a master and MEMS acts as a Slave.  The master receives signals and controls the wheel chair with respective directions.

Wheel chair has two D.C gear motors. These motors move in 2D direction according its input signals. These motor moves with the help of L293D driver. This driver acts as a H-bridge.This project uses regulated 5V, 500mA power supply. Unregulated 12V DC is used for relay. 7805 three terminal voltage regulator is used for voltage regulation. Full wave bridge rectifier is used to rectify the ac output of secondary of 230/12V step down transformer.

TECHNICAL SPECIFICATIONS:

HARDWARE:

Micro controller         :           AT89x series                                        

Crystal                        :           11.0592 MHz                         

DC gear motor

Driver IC                     :           L293D                     

MEMS sensor

Power supply

Transformer: 12V step down 

Filter: 1000uf/25V

Voltage Regulator: 7805, 7812

SOFTWARE:

Keil IDE

UC flash

Proteus

APPLICATIONS

• Industrial applications
• Automatic control systems
• Hospital management