International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056

Volume: 03 Issue: 05 | May-2016 www.irjet.net p-ISSN: 2395-0072

Electric Wheelchair for Physically Challenged

P. Swapna 1, Dr. B. Sharmila2, Y. Dharshan3
1 PG Scholar, Dept. of Control and Instrumentation Engineering, swapnashakthi12@gmail.com
2 Professor, Dept. of Electronics and Instrumentation Engineering, sharmila.rajesh@srec.ac.in
3Assistant Professor, Dept. of Electronics and Instrumentation Engineering, dharshan.y@srec.ac.in

Sri Ramakrishna Engineering College, Tamilnadu, India

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Abstract - Mobility of the Physically Challenged people or wheelchairs custom-built. This paper focuses on the
crippled people is a great concern of the society. This Project emerging trend of electric wheelchair. The electric-powered
focuses on designing a mobility aid for the physically wheelchair was invented by George Klein who worked for
challenged people to travel from one place to another. Joystick the National Research Council of Canada, to assist injured
controller based mobility aid wheelchair has been designed for veterans during World War II. Three general styles of
the all possible direction of movements like left, right, straight electric powered chairs exist: rear, center, front wheel driven
and back. Moreover the DC geared motors are used for the or four wheels driven. Each style has particular handling
movement of the wheels for the purpose of lower speed characteristics. Electric powered chairs are also divided by
movement of chair which will be convenient for the physically seat type; some models resemble manual chairs, with a sling-
challenged. As the wheelchair has been named as electric / style seat and frame, whereas others have 'captain's chair'
powered wheelchair, this project utilizes the power from the seating like that of an automobile.
lead acid batteries which are rechargeable, harmless, and
weightless compared to others available. This work also Electric powered chairs are designed for indoor use,
concentrates on integration of GPS and GSM system for outdoor use, or even both. They are generally prescribed for
localization task and also a mobile application with the help of persons who have difficulty in using a manual chair due to
MIT application developer has been developed for the arm, hand, shoulder or more general disabling conditions,
convenience of the care taker in order to know the position of and do not have the leg strength to drive a manual chair with
the person in wheelchair through Google maps. The proposed their foot, which is not generally recommended by most
wheelchair system has the idea to run both in indoor and Health Professionals. They may also be issued to those with
outdoor environments. Moreover the wheelchair has been cardiovascular conditions. EPWs can offer various powered
designed to convert as a stretcher and semi stretcher which functions such as tilt, recline, leg elevation, seat elevation,
will make the physical challenged people to feel better during and others useful or necessary to health and function.
relaxation and night times. This has been brought to live with Electric powered chairs use electric motors to move the
the concept of motorized scissor jack mechanism for the wheels. They are usually powered by 4 or 5 amp deep-cycle
change of wheelchair positions. rechargeable batteries, similar to those used to power
outboard boat engines. These are available in wet or dry
Key Words: Electric wheelchair, Joystick controller, DC options; currently dry cell batteries are more popular. Many
motors, Rechargeable batteries, Motorised Scissor Jack, EPWs carry an on-board charger which can be plugged into a
Stretcher, GPS/GSM. standard wall outlet; older or more portable models may
have a separate charger unit.

1.INTRODUCTION 2. NEED AND THE CONCEPT BEHIND ELECTRIC

WHEELCHAIR
A wheelchair is a wheeled mobility device in which the user
sits. The device is propelled either manually or via various Power wheelchairs are used predominantly by people with
automated systems. Wheelchairs are used by people for both lower and upper extremity impairment resulting from
whom walking is difficult or impossible due to illness, injury, cerebral palsy, high-level spinal cord injury, or muscular
or disability. People walking disability often need to use a dystrophy. The propulsion system of powered wheelchairs
wheel bench. Wheelchairs are often variations on this basic typically consists of a pair of motors, one for each drive
design, but there are many types of wheelchairs, and they wheel, and a drive train consisting of gears, belts that
are often highly customized for the individual user's needs. couples the motor’s shaft to the wheel shaft. Most
The seat size (width and depth), seat-to-floor height, wheelchairs uses the permanent magnet DC motors (PM
footrests/leg rests, front caster outriggers, adjustable motors), with two 12V lead acid batteries providing a 24 V
backrests, controls, and many other features can be supply. PM motors have a linear torque-speed characteristic
customized on, or added to, many basic models, while some making them easy to control.
users, often those with specialized needs, may have

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 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
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A DC-DC converter drives each motor with a high 3. BLOCK DIAGRAM OF THE PROPOSED ELECTRIC
frequency, square wave, pulse train that turn the motors on WHEELCHAIR
and off. Speed and torque generated by each motor is
controlled by modulating the pulse width. Solid state relays
The block diagram of the proposed electric wheelchair is
are used to switch supply voltage polarity to change the
shown in the Figure 1. The block diagram describes the flow
driving direction of DC motors.
of proposed electric wheelchair working. The flow starts
Wheelchairs have both three- and four-wheel with the rechargeable battery which is the heart of the
models using direct or indirect drive systems (belt/chain). system provides power to the whole assembly. It is then
Most wheelchair are rear wheel drive for increasing the followed by the wheelchair controller come joystick module
traction while the front wheel drive systems are lighter and which receives the supply from battery in order to start up
they may result in difficult traction maintaining on with the movement of wheelchair directions choice given by
inclination or rough terrains. No load, PM motors can the person in wheelchair with the help of joystick mounted
provide an efficiency of about 70%. Under loaded condition, on the arm rest assembly. The joystick receives the
typically for power wheelchairs, these motors attain about command from the user which in turn given to the
45% efficient. The wheelchair’s controller module takes the wheelchair controller for the control action according to the
positional information from the joystick and converts into user choice which is already been programmed in the
power signals to the PM motors. Control modules are controller. Once the control action has been taken, the
microprocessor based and have many adjustable control signal is directed towards the DC geared left and
parameters according to the user needs. right motors for the movement of wheelchair in respective
directions.
The drive train is a mechanical system that
transfers rotational power from the propulsion motor to the
wheels shaft. There are two types of drive trains 1) direct
transfer and 2) indirect transfer. In a direct drive transfer
system, the motor shaft is directly connected to the wheel
shaft (through gears for instance). Direct drive transfer
requires a low speed, high torque motor which will be
mechanically efficient. However, the gears in the direct drive
system are prone to wear and/or breakage that make them
expensive to repair or replace.

For an indirect drive transfer system, the motor is

coupled to the drive wheel shaft through a system of gear
train and flexible machine element (belts or chains). The
gear train and belt typically serve to reduce the motor speed Fig -1 Block diagram of proposed electric wheelchair
while proportionately increasing motor torque. They also
act as a “shock absorber” when the drive wheels are stuck or The flow of work then passes on to the wheelchair
under heavy load. Excessive stress on the system can cause position changing i.e as it has been already mentioned that
an increase in noise and misalignment of the drive system. the proposed electric wheelchair will be converted to semi
However, realignment is easily done and the cost of and complete stretcher positions. This action has been
maintaining the system is relatively low if adjustments are brought to live with the scissor jack – motor assembly which
made on a regular basis. receives the power from rechargeable battery in order to
make the motor to run which in turn make the scissor jack to
The torque delivered by motors and drive trains, work i.e to lift or drop the wheelchair plats. This can be
places constraints on the environments that a power made possible with the help of limit switches. A limit switch
wheelchair user can access, work or recreate in. The speed is an electromechanical device that consists of an actuator
and efficiency of motors and drive trains, constrains the mechanically linked to a set of contacts. When an object
travel distance and time between battery recharge. The size comes into contact with the actuator, the device operates the
and configuration of the battery, motors and drive trains contacts to make or break an electrical connection.
constrains the physical dimensions of the wheelchair’s
power base and impacts a user’s ability to access home, Next the GPS and GSM modules play a role for
work, recreational and educational environments. Seat identifying the position of the wheelchair. This idea will be
height impacts a users access to desks and tables. Vans very useful to the person who is taking care of the physically
generally require extensive modification to accommodate challenged. The work is done with the help of arduino which
the seated height of a power wheelchair user. receives the power from battery with voltage regulator
because the arduino, GPS and GSM modules require less
power compared to the motors and other assemblies. Also a

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Volume: 03 Issue: 05 | May-2016 www.irjet.net p-ISSN: 2395-0072

mobile application has been created in order to view the Assembling of wheelchair plays a major role in this
disabled position through the google maps. proposal. It’s very important to note that the assembling
should be perfect so that the working of wheelchair will lost
4. HARDWARE SPECIFICATIONS long. It’s a known fact that joystick cum wheelchair
controller module is the heart of the system. The following
As for concern the specifications are the important part in discussion shows the connection of joystick controller with
this work. The DC motors are the heart of the system for the battery and motor to form a electric wheelchair. The overall
purpose of wheelchair propulsion. They have been chosen as flow diagram of electric wheelchair is shown in the Figure 2.
DC geared motor of 24 V, 120 rpm. The batteries have
chosen as lead acid rechargeable batteries of 12V, 17 Ah. The
Joystick controller which is joystick position based
wheelchair controller of 24 V supply. The material used for
the construction of wheelchair is mild steel whose properties
well suit the environmental and other conditions. The
Motorised Scissor Jack which is utilized for the conversion of
wheelchair into stretcher is of two types one is 1000Kg and
the other is 700 Kg capacity of lifting, the motors attached to
the jack are DC motor of 10 Amps and 12V. The GPS/GSM
module used is of model SIM808A for the purpose of
tracking the wheelchair. Arduino UNO board has been used
for implementing the same.
Fig -2 Flow diagram of electric wheelchair
5. FABRICATING AND ASSEMBLING OF
WHEELCHAIR The power module is the heart of the system. It contains
connection provisions for all other modules like battery,
As the proposed wheelchair should withstand for all the motor, joystick, control input etc.,. By following the flow
circumstance and adopt for all the environments, should shown above the wheelchair can be easily made and tested.
withstand for all stress and strains. To meet all these
requirements, the basement of the wheelchair should be
very strong. So it is necessary to focus on the material to be 6. CONVERSION OF WHEELCHAIR INTO
used for the formation of wheelchair. The material selected STRETCHER
must possess the necessary properties for the proposed
application. The material selected for the particular Jack is a mechanical device used to lift heavy loads. A
application is mild steel. The various requirements to be mechanical jack employs a square thread for lifting heavy
satisfied can be weight, surface finish, rigidity, ability to equipment. The most common form is a car jack, floor jack or
withstand environmental attack from chemicals, service life, garage jack which lifts weights so that needed task can be
reliability etc. The following four types of principle performed. Mechanical jacks are usually rated for a
properties of materials decisively affect their selection maximum lifting capacity of 1.5 tons to 3 tons. Scissor jacks
Physical, Mechanical, From manufacturing point of view, are mechanical devices and have been in use since 1930s. A
Chemicals. scissor jack is a device constructed with a cross-hatch
mechanism, much like a scissor, to lift up a vehicle for repair.
The various physical properties concerned are
It typically works in a vertical manner. The jack opens and
melting point, thermal conductivity, specific heat, coefficient
folds closed, applying pressure to the bottom supports along
of thermal expansion, specific gravity, electrical conductivity,
the crossed pattern to move the lift. When closed, they have
magnetic purposes etc. The various Mechanical properties
a diamond shape. Scissor jacks are simple mechanisms used
Concerned are strength in tensile, Compressive shear,
to handle large loads over short distances. The power screw
bending, tensional and buckling load, fatigue resistance,
design of a common scissor jack reduces the amount of force
impact resistance, elastics limit, endurance limit, and
required by the user to drive the mechanism.
modulus of elasticity, hardness, wear resistance and sliding
properties. The various properties concerned from the Motorised Scissor Jack play a vital role in the
manufacturing point of view are Cast ability, Weld ability, proposed wheelchair. It has already been mentioned that the
Surface properties, Shrinkage, Deep drawing etc. From proposed work focuses on the idea of converting the
considering all the factors mentioned above, the material wheelchair into the semi cum complete stretcher model. It
chosen for the wheelchair fabrication is mild steel flat rod of has been made possible through the concept of motorised
gauge 1.25 inch. scissor jack. Here the Jack has been fitted at the back plate as
well as in the leg plate in order to lift and drop the same
according to the user choice and convenient. As the design
prototype discussed in chapter 2 has been brought to live

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here. Two types of jack has been used which differ in their A doubt arises at the time of conversion of wheelchair to
capability to lift weights i.e 1000Kg and 700Kg capability stretcher mode, i.e when the wheelchair is in chair mode, the
Jack has been used here. 1000Kg jack has been used for jack will be in expanded condition, when the user choice is to
lifting the whole back body weight and 700 Kg jack has been switch to stretcher mode, the back resting plate should be
used for lifting the legs. As the weight of legs are less when dropped down and the leg resting plate should be raised up
compare to the back body weight, less capacity 700Kg jack with the control of corresponding jacks provided under the
has been used here. As the 12V, 10 Amps motor has been wheelchairs. When the back resting plate is dropped down,
fitted to these jack, once it get energised from the battery, with the lack of balance the wheelchair / person may slip
the Scissor shaped jack starts to expand and contract its ‘Z’ down. In order to avoid this, a concept called “Saddle
shape through the gear mechanism in order to convert the wheels” has been fixed at the side bars of the wheelchair as
rotational motion of motor into the mechanical motion of shown in the Figure 5 which will move the sitting plate in
levers and screw threads for the purpose of lifting the front to certain position which in turn the plate gets seated
weights of wheelchair. in a balanced position so that the weight is balanced. The
heart of the propulsion system is the battery and the motor
7. RESULT ANALYSIS which are to be fitted at the basement as shown in the Figure
6. The whole system is tested by driving the chair with the
As discussed earlier the wheelchair has been constructed help of joystick position.
with the material of mild steel. The basement of wheelchair
is provided in order to balance the weight of the patient and
other components assembled. The length of the basement
provided is of 3 feet. It covers the half length of the total
wheelchair length. The Figure 3 shows the full top view of
the wheelchair with three plates

Fig -5 Saddle wheels provided at the side bars of

wheelchair

Fig -3 Top view of wheelchair at initial stage

The total length of the wheelchair is 6 feet. It contains three
steel plates, sitting, leg resting and back resting plates with
the basement at the bottom. The next Figure 4 shows the
motorised jack fitted at the back side of wheelchair for the
stretcher conversion.
Fig -6 Base of the wheelchair with motor and battery
assembled
As the person who is taking care of the physically
disabled give their request to know the current location of
wheelchair and ensure whether disabled is in safe premise. A
mobile application has also been created for this task to
happen in a successful manner. The screen shots of the
mobile application and its results are shown in the Figure 7.

Fig -4 Motorised scissor jack attached at the back of

wheelchair

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Engineering and Technology, Vol.2, No. 1, 2012, pp.

211-214

[2]. Arvind Prasad , Snehal Shah, Priyanka Ruparelia, Ashish

Sawant, ‘Powered Wheelchair’, International Journal of
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[3]. Chi-Sheng Chien, Tung-Yung Huang, Tze-Yuan Liao,

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The application has been developed with the help of MIT
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It has been named as ‘Locate me’ and some bars have been B.M. Fahimid Jahur Shuvo, K.B.M. Nasiruzzaman and
developed for the user interface with the arduino. On seeing Rahman MD. Moshior, ‘ Design and implementation of
the application, when the user touch the ‘check status’ bar, it an Electric Wheel- Chair to Economize it with Respect
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the GSM. The application has been designed to receive the Motivated Tricycle for the Physically Challenged
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[6]. Kohei Arai, Ronny Mardiyanto, ‘Eye Based Electric
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solar panel for the power supply. Here the solar energy will eefficient electronic wheelchair seat balancing
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[9]. Shahidul Islam Md, Azheed Bin Rahman, Nafis Ahmad,
our brain thinking, that automatically grabs the direction we
‘Designing Solar Three- Wheeler for the Disable People’,
need to move. The path required to travel can also be guided
International Journal of Scientific & Engineering
with the help of google map through voice controller. These
Research, Vol. 3, No. 1, 2012, pp. 1-7
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