MICRO ELECTRONIC MECHANICAL SYSTEM SENSOR BASED WHEELCHAIR CONTROLLER FOR THE DISABLED

Abstract

The use of powered wheelchairs with high navigational intelligence is one of the great steps towards the integration of severely physically disabled and mentally handicapped people. Driving a wheelchair in domestic environments is a difficult task even for a normal person and becomes even more difficult for people with arms or hands impairment. Tetra pelagic people are completely unable to operate a joystick unless they use the tongue, which is obviously a very tedious task. Simultaneously blind and paraplegic people deal with a very uneasy situation which couples two problems: locomotion and localization. The Rob Chair system is being developed to overcome the problems described above, allowing the end-user to just perform safe movements and accomplish some daily life important tasks.3 Axis Acceleration Sensor (ADXL335) from Analog devices is used for gesture recognition. It is a first generation sensor. User could get acceleration value of X, Y, and Z axis. And it is widely used in shock, slope, and moving detection. Output sensitivity could be select by simply set voltage level on few pins. The output of the sensor is in analog mode. A prototype chair is implemented with a small chair and 60 RPM motors are used to move the chair. A free-wheel is arranged to change the chair direction according to user’s requirement. This is an interesting robot that can be controlled by hand gestures. This can be moved forward and reverse direction using geared motors of 60 RPM. Also this wheel chair can take sharp turnings towards left and right directions. This project uses LPC2148 as its controller. ARM7TDMI is an advanced version of microprocessors and forms the heart of the system. The LPC2148 are based on a 16/32 bit ARM7TDMI-S CPU with real-time emulation and embedded trace support, together with 128/512 kilobytes of embedded high speed flash memory. The project can be extended by controlling the speed of the DC motor by using PWM technique. A pulse width modulator (PWM) is a device that may be used as an efficient DC motor speed controller. One additional advantage of pulse width modulation is that the pulses reach the full supply voltage and will produce more torque in a motor by being able to overcome the internal motor resistances more easily With a wide range of serial communications interfaces, they are also very well suited for communication gateways, protocol converters and embedded soft modems as well as many other general-purpose applications. In this wheelchair controller 3 Axis accelerometer chip, RF Module, LPC2148 Microcontroller, DC Geared motors are used. In this project, L293D H-Bridge is used to drive the geared DC motor. The RF modules used here are STT-315 MHz Transmitter, STR-315 MHz Receiver, RF Encoder and RF Decoder. This project uses 12V (Lead Acid Battery). This project uses two power supplies, one is regulated 5V for modules and other one is 3.3V for LPC2148. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the AC output of secondary of 230/12V step down transformer. Key Words: KMEMS sensor, RPM, ARM&TDMI LPC2148 controller, DC Motor