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HEAD MOTION CONTROLLED WHEEL CHAIR

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CONTENTS• OBJECTIVES• INTRODUCTION• EXISTING SYSTEMS• PROPOSED SYSTEM • BLOCK DIAGRAM • BLOCK DIAGRAM EXPLANATION• IMPLEMENTATION PLATFORM• ADVANTAGES• APPLICATIONS• RESULTS• CONCLUSION• REFERENCES 05/03/23 3

OBJECTIVES

• To help the quadriplegic patients to move

independently from one place to another with the help

of wheelchair by tilt movement of their head.

• To alert family members in time of emergencies.

• Avoiding obstacles like edges or staircase.

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INTRODUCTION

• Quadriplegics are persons who are not able to move any of the body parts.

• This may be due to age, stroke, arthritis, high blood pressure, paralysis and birth defects.

• The patients with such disabilities are not able to perform their everyday actions such as feeding, toilette usage and movement through space.

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EXISTING SYSTEMS1. EYE MOVEMENTBASED WHEEL CHAIR

•Eye ball is sensed.

DISADVANTAGES

•100% efficiency cannot be provided in dim environment.•Itching or irritations. Figure1: Eye movement tracking by

camera

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2. TONGUE CONTROLLED WHEEL CHAIR•Tongue is used as the medium. DISADVANTAGES•Tongue needs to be pierced.

•Users should avoid inserting Ferro magnetic objects into their mouth.

•Magnetic tracer should be removed if the user is undergoing MRI.

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Figure 2:Tongue Drive System

3. VOICE RECOGNITION SYSTEM•Controlled by human voice. DISADVANTAGES•5% error.•Individual needs to be trained.•Dumps cannot use.•Not suitable in noisy environment.

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Figure3: Voice Recognizing System

4. BRAIN CONTROLLED WHEELCHAIR

•Brain controls the mechanical device.

DISADVANTAGES

•Brain impulse varies from person to person.

Figure4: Brain Controlled Wheelchair

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PROPOSED SYSTEM

• Proposes a system in which the wheelchair move towards left, right, forward and backward direction with respect to the motion of head.

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BLOCK DIAGRAM

( To microcontroller and other chipsets) ( To motor control unit and motors)

Figure 5 : Block Diagram

Accelerometer (attached to the head

of the patient)Microcontroller

Mechanical actuator Wheelchair

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GSM

Obstacle Sensor

MAX 232 Pulse Oxymeter

Regulated Power

Supply 5V.

Power Supply 12V

BLOCK DIAGRAM EXPLANATION1) ACCELEROMETER

Figure 6: Accelerometer

• An accelerometer is needed to sense the head motion.• 2 axis sensing (+x, -x, +y and –y axis).• X axis for left and right motion.• Y axis for forward and backward motions.• Right and forward are the positive motions.05/03/23 12

Figure7: Internal block diagram

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• 3 axis sensing is possible.

• Z axis can be combined with both of the tilting axis to improve angle/ tilt sense precision and accuracy.

• The output signals are analog voltages.

• The analog output is signal conditioned and given to ac amplifier.

• Phase sensitive modulation techniques are used to determine the magnitude and direction of acceleration.

• The demodulated output is amplified and brought through a resistor of 32Kohms.

• This filtering improves measurement resolution and helps prevent aliasing.

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2) MICRO CONTROLLER (ATmega328)

FEATURES•8 bit RISC architecture.•131 instructions.•20 MIPS.•Low power consumption.•1KB EEPROM.•2KB SRAM.•1.8-5.5V.•0-20MHz.

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Figure8:ATmega328

3) MECHANICAL ACTUATOR DC MOTOR•An electric motor is a machine which converts electrical energy to mechanical energy

•It is based on the principle of Flemings Left Hand Rule.

•When it is supplied by an electric current, it develops a torque which in turn produces mechanical rotation.

•Direction of rotation changed by changing the direction of current.

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Figure9: DC Motor

• Pins 1 and 9 are the enable pins.

• Pins 1 and 9 need to be high for driving the motor.

• Pins 2 and 7 are the inputs for left motor.

• Pins 10 and 15 are the inputs for right motor.

• Left motor connected to output pins 3 and 6 , and right motor to output pins 11 and 14.

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Figure 10: Pin diagram of L293D

Figure11: L293D Logic table for left and right motor

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PIN 2/10 PIN 7/15 DIRECTION

LOGIC 1 LOGIC 0 CLOCKWISE

LOGIC 0 LOGIC 1 ANTICLOCKWISE

LOGIC 1 LOGIC 1 IDLE

LOGIC 0 LOGIC 0 IDLE

4) GSM• Wireless MODEM device.

• It requires a SIM(Subscriber Identity Module) card to activate communication with the network.

• Interfacing between microcontroller and GSM modem is possible by using RS232 serial port.

• AT commands are sent to interact microcontroller / processor with GSM network.

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Figure12: Block Diagram

• GSM operates in either 900MHz or 1800MHz.

• ARFCN is the unique number given to each radio channel in GSM.

• Within GSM900 band ARFCN 1 to 124 is used.

• Both TDMA and FDMA are used.

• In FDMA the total 25MHz bandwidth is divided into 124 carrier frequencies of 200KHz bandwidth.

• Each of these carrier frequency is further divided in time using TDMA into 8 time slots.

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5) OBSTACLE SENSOR

• Obstacle sensor is used to stop the wheelchair, incase of any obstacle.

• IR beams are produced from the obstacle sensor.

• It is placed at the bottom of the wheelchair.

• Intensity of reflected beam is proportional to distance. Figure 13Obstacle sensor placed in

wheelchair

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6) PULSE-OXIMETER• The sensor unit consists of IR led and photodiode.

• Finger tip placed over the sensor assembly.

• The IR led transmits light into finger tip.

• The photodiode senses the portion of light reflected back.

• The intensity of reflected light depends on the blood volume inside the finger tip.

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Figure14: Pulse-oximeter placed at finger tip

CIRCUIT DIAGRAM

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Figure15: Circuit diagram

1) FLOWCHART FOR ACCELEROMETER AND MOTOR

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Start

Read the voltages on x and y axis

If Vx > 2.5V

If Vx < 2.5V

No

Yes

Yes

Move forward

Move backward

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If Vy > 2.5V

If Vy< 2.5V

No

Yes

YesNo

If Vx=Vy=

2.5V

YesNo

Stop

Move right

Move left

Stop the wheelchair

2) FLOWCHART FOR PATIENT MONITORING SYSTEM

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Start

If Vpo> 70 bpm

YesSend message

StopNo

3)FLOWCHART FOR COLLISION DETECTION

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Start

If obstacle is detected

Stop the wheelchair

Yes

No

IMPLEMENTATION PLATFORM

HARDWARE REQUIREMENTS: ATmega328 microcontroller. Accelerometer. Mechanical Actuator. GSM Module Obstacle sensor.

SOFTWARE REQUIREMENTS: Arduino for Embedded C programming. Eagle software for PCB Design.

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ADVANTAGES

• Enable young disabled children and their families to enjoy ordinary lives.

• Increase the number of disabled people in employment.

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APPLICATIONS

• This automated wheelchair is valuable for the people who could not move independently like: 1. Amputees - missing legs and/or arms.2. People with weak or no upper body movement.3. Paralyzed children.

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RESULTS

• PCB for accelerometer controlling dc motor and pulse

oximeter section has been obtained.

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CONCLUSION

• Automated wheelchair can be used to help handicapped people, especially those who are not able to move.

• The intelligent wheelchair helps the severely disabled people to lead their life in an uncomplicated way.

• The low cost of the assembly of this intelligent robotic wheelchair is really a boon for the general public.

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REFERENCES

[1] Aleksandar Pajkanovic, Branko Dokic: Wheelchair Control by Head Motion, Serbian Journal of Electrical Engineering ,Vol. 10, No. 1, February 2013, 135-151.

[2] S.P. Levine, D.A. Bell, L.A. Jaros, R.C. Simpson, Y. Koren & J. Borenstein: The NavChair assistive wheelchair navigation system, IEEE Transactions on Rehabilitation Engineering, 7(4) pp.443-451,2008

[3] Manju Davy, R.Deepa : Hardware Implementation Based On Head Movement Using Accelerometer Sensor , Int. Journal of Applied Sciences and Engineering Research, Vol. 3, Issue 1, 2014.

[4] Preeti Srivastava, Dr.S. Chatterjee, Ritula Thakur: A Novel Head Gesture Recognition Based Control for Intelligent Wheelchairs , International Journal of Research in Electrical & Electronics Engineering Volume 2, Issue 2, April-June, 2014, pp. 10-17

[5] S.Shaheen & A.Umamakeswari: Intelligent Wheelchair For People With Disabilities, International Journal of Engineering and Technology (IJET), 5(1), pp.391-397,2013.

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