Brain controlled wheel chair

Team Odai Abu-Zaid Saeed Anshasi Hani Elshatarat

Supervision : Dr. Nathir Rwashdeh

See the Video

Project description and motivation Control the movement of a motorized

wheel chair using brain waves. Help people with total paralysis to move

without any muscle stress, making their life easier.

Applications Domestic Hospitals Nursing  home intermediate care It Could be very dangerous to use it in

the local street

Conceptual design

Components needed Out of service Wheelchair EPOC Headset Arduino 12 volt Battery Motor drive unit:

Relays, MOSFETs, BJTs, Opt couplers, Fan, fins, resistors.

Cost of the Project Item Quantity Out of service wheel chair

1 150

Epoc Head set 1 550Adruino 1 23Battery 1 35Fixing the wheelchair

1 20

Motor drive unit 2 25

Total Cost 803

EPOC Headset : 16 brain contact sensor Dongle Software :

Control Panel Headset Setup Affective Expressive Cognitive

Emokey

Drive unit Alternatives

Integrate motors to manual wheelchair DC series motors Gears and belt Calculations

Use an out of service wheel-chair Fixing the wheel chair PM DC motor Calculations

Alternative A Use a manual wheel chair Integrate motors with wheels by using

gear and belt drive system

DC series motor Equivalent circuit :

DC series motor Benefits :

o highest starting torqueat no-load speedo Flexibility of Reversing the direction

Transmission unit Gear

to reduce the speed of the motor and increase its torque.

Helical gear : Less noise more gradual engagement High Thrust load

Belt : to transmit power from shaft to another by means of pulleys

Motor sizing : Maximum load of 120 Kg Maximum speed of 0.6 m/s A wheel diameter of 60 cm Maximum acceleration of 0.6 m/s^2 The power supply voltage is 12 V

According to these specification :F = ma F = 72 NT = rF T = 21.6 N.mA chair that provide a 21.6 N.m torque is

needed .Each wheel will carry a 12.5 N.m (after Adding factor of safety )

Power Calculations:  Total Mechanical Power = T * ω   P =  139 wattAdding losses Assuming 12V Motor I = 12.5 AmpTwo 0.2 hp motors were needed .

After searching in the local market : No motors were found.

Alternative B : Use an out of service wheelchair cheap alternative and easy to get PM DC motor Calculation

Alternative B

PM DC Motor

 c

calculation From this data sheet, we find the

followings:

 

Efficiency = Pin = 0.5 Pout = 300 W

Pin = VtIa Ia = = = 12.5 A

Pout = Pin - Plosses

Plosses= 150 W

Motor drive unit Schematic Isolate High voltage from Low Voltage Amplification of current H bridge PWM Reverse Direction Mode of operation

Schematic of motor Drive Dir

PWM

Motor drive unit Schematic Isolate High voltage from Low Voltage Amplification of the current H bridge PWM Reversion of Direction Mode of operation

Isolate high voltage from low voltage

Motor drive unit Schematic Isolate High voltage from Low Voltage Amplification of the current H bridge PWM Reverse Direction Mode of operation

H-Bridge Circuit It looks like the letter H it is used to allow DC motors to operate in two opposite directions i.e. forward ,Backward. The direction of rotation can be changed by changing the polarity of the armature

PWM Pulse width modulation is used to

control the average power that goes a load in a motor.

It operates by changing the average voltage level through generating a constant frequency signal in which the pulse width is manipulated or changed.

PWMDuty cycle and frequency

Forward Direction

+

-PWM

Motor drive unit Schematic Isolate High voltage from Low Voltage Amplification of the current H bridge PWM Reverse Direction Mode of operation

Reverse Direction

+

-PWM

Dir

Reverse Direction

+

-

Dir

PWM

Motor drive unit Schematic Isolate High voltage from Low Voltage Amplification of the current H bridge PWM Reverse Direction Mode of operation

Mode of operationPWM1 PWM2 DIR 1 DIR2

Forward 1 1 0 0Backward 1 1 1 1Right 1 0 0 0Left 0 1 0 0Stop 0 0 X X

Flow chart

Cost optimization Purchasing the EPOC Headset in the

global Brain Awareness Week and getting15% discount.

Use an out of service wheelchair

Use the Car relay instead of normal industrial relay.

Challenges Finding DC motors in the local market To get a good quality signal from the

EPOC Building the motor drive circuit with

acceptable cost.

Future work: Emergency stop system

Physical manual button Current sensors to the motor drive circuit

to limit the load by a specific maximum current

Solar battery charging and can protect the user from the sun.

Vielen Dank

Questions ??