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Abstract—Mobility of the physically disabled or crippled people is a great concern of the society. It is really difficult to realize the problems
and sorrows of a physically disabled/crippled person who is partially or fully dependent on others or confining himself in a w heel chair with
limited mobility. This paper provides idea of currently available three-wheelers for disabled people and proposes a new improved design of
a solar powered three-wheeler suitable for countries like Bangladesh w hich is an under developed country w ith huge disabled/crippled
people from war, accidents and diseases. This three-wheeler is operated by solar power and suitable for outdoor use. Solar power option
enables the disabled people to use it at any place, even in remote areas where there is no electricity. A general survey had been conducted
on disabled people using wheel chairs and manual three-wheelers and the opinions of the experts working w ith the disabled people are
also taken in to consideration to identify the needs and requirement for designing the solar three-wheeler. The proposed solar threewheeler
is meant to match and exceed the conventional three-wheeler’s facilities w ith a more intelligent and efficient design. A solar panel
to produce solar electricity, a battery system for preserving electric power, an efficient motor, cushion seat, all terrain tires are used for this
solar three-wheeler. Due consideration and attention is given to better maneuverability, effective use of solar energy, biomechanics and
comforts, increased suspensions, all terrain traffic ability, ease of use etc. while designing this solar three-wheeler for physically disabled
people of the country.
INTRODUCTION
lot of difficulties and hassles involved with the mobility
of the physically disabled people in the society. It has
been observed that physically disabled people are basically
using some assistive devices like, crutches, artificial limbs or
legs etc. and manual wheel chairs or three-wheelers for their
day-to-day movements. But, these wheel chairs or threewheelers
are crude or of inefficient in design; not very much
suitable for outdoor use or common terrain in the country like
Bangladesh. Undoubtedly these manual wheel chairs or the
three-wheelers are the blessings for crippled people but in the
question of humanity, it is just “to add insult to injury”. Because,
commonly found manual wheel chair or three-wheeler
has a basic problem that the occupant must use physical force
to turn the wheels. This action is physically stressful, can result
in muscle and joint pain and degradation, torn rotor cuffs, r epetitive
stress injury, and carpal tunnel syndrome; which causes
secondary injury or further disability[3].
Again, Use of conventional energy sources and rapid development
of the present world have some bad impacts on the
surroundings and environment, like depleting limited energy
resource, damage of ecosystem, environment pollution, global warming and so on. As a result, Designing for Environment
(DFE) is the crying need of the time and it is very much necessary
to develop environment friendly equipment or transport
for better living, for better world.
Considering the overall prevailing situation, development of a
solar three-wheeler for disabled people is a vital effort where
solar energy and its advantages are taken into account. A solar
three-wheeler could be a stand-alone system; it will be selfoperated
and independent in nature, using unending solar
energy from the sun. It is powered by solar energy from attached
solar panel at top, exposed to sunlight. It can take us off
the grid; can be used in a place where there is no electricity.
The transport idea concerned here is a solar power operated
three-wheeler with light structure of moderate height-width
and weight, which suits to Bangladeshi terrain. Also due emphasis
is given to biomechanics, comforts, safety etc. while
designing the seat for the solar three-wheeler. These features
give greater stability, better maneuver ability, better mobility
and comforts over the available manual three-wheelers. In a
sense, a solar three-wheeler can be the complete solution for
the transportation of physically disabled people of the country.
Use of available resources (for components such as pipes for
chassis/body, wheels, bearing etc. from the local market) and
simplicity in designing result cost economy. The battery used,
motor and solar panels are also very much available in the
markets. All these features make the solar three-wheeler a very
cost effective and environment friendly transport for the daily
use of the disabled people.
2 PRESENT SCENARIO
Since the liberation war of Bangladesh in 1971, a large number
of people have become disabled and vulnerable to the country.
The prevalence of disability is believed to be high for basic
reasons relating to over population, extreme poverty, illiteracy,
social security, lack of awareness of traffic rules and above all
lack of medical/health care and services. By latest, the numbers
of disabled people are increasing rapidly due to increasing rate
of road accidents and other relevant diseases [1]. In the present
social hardship, other family members often fail to pay proper
attention and care to the disabled people. So, their lifestyle
improvement and independency is very much important and
urgent too.
Although disability is a major social and economic phenomenon
in Bangladesh, there is very little reliable data available on
this issue, especially in the absence of a comprehensive national
survey on disabiled persons. Basing on some data collected
by the prevailing NGOs and international organizations, it is
commonly believed that almost 10% of the total populations of
Bangladesh are disabled and 2.5% of which are crippled or
physically disabled [2]. Presently available wheel chairs are
basically for indoor use or short distance movement and the
manual three-wheelers for outdoor use. But those are not very
suitable for use and having lot of technical drawbacks.
The numbers of crippled/ disabled people are quite alarming
but the numbers of wheel chair or three-wheeler users are not
big and mostly found them in hospitals and residents, especially
in urban areas. It is revealed from the survey that the
numbers of present wheel chair/three-wheeler users are negligible
in all over the country. It happens because the presently
available wheel chairs or three-wheelers are manual and not
very suitable for outdoors use or for the roads around the
country. The roads even in the cities are not very smooth or
there is no lane for wheel chairs/ three-wheelers. Most of the
cases the roads are very rough and narrows with some other
limitations. Commonly Bangladesh has plain land and roads
in the villages are of rough condition where peoples are moving
with their bicycles, rickshaws etc. City roads are better
where people move by rickshaws, auto- rickshaws, busses,
taxi-cabs, cars etc.
There are some NGOs like, Centre for Disability Development
(CDD), Centre for Rehabilitation of the Paralyzed (CRP) etc.
working for the physically disabled people and producing
some manual wheel chairs and three-wheelers, somehow suitable
for outdoor use. But again the problems remain, as the
users need to use the physical force to drive it. Photographs of
the presently available wheelchairs and three-wheelers in Bangladesh
are shown in Figure 1.
PROSPECT OF SOLAR THREE-WHEELER
Scarcity of energy is a common problem in all over the globe
due to lack of conventional energy sources. So, Eco-friendly
renewable energy like solar power can be the alternative and
solve the power problem to some extent. Availability of solar
energy radiation is the most vital consideration for designing
and development of a solar system or solar equipment at any
location on the earth. Rated solar radiation power received by
the earth surface is (global radiation flux) 1000 W/m² (AM 1.5,
sun at about 48 from overhead position). Availability of solar
energy radiation in all over the country is very much encouraging
for developing a solar three-wheeler for disabled people
in Bangladesh. The geo-location of Bangladesh is in favor of
receiving highest amount of solar radiation round the year. It
is situated between 20.30-26.38 degrees north latitude and 88.04 - 92.44 degrees east, which is an ideal location for solar
energy utilization. Solar radiation mapping shows that the
daily average solar radiation varies between 4-6.5 kWh/m².
Maximum amount of radiation is available on the month of
March-April and minimum on December-January [5].
The researches have been going on to produce solar car, solar
plane and so on. In the transportation sector, the use of solar
energy faces different problems, such as the limited space for
panel, batteries, transmission problems etc. Many in the world
attempted to carry out the idea of a solar car, jointly forming as
association and establishing a yearly race for solar powered
cars, in different county each year. These works show the design
parameters for a solar car only and no significant
achievement yet for a suitable solar three-wheeler for disabled
people.
Since the solar power system suits well with the minimal power
consumption, the development of the solar three-wheeler
would be very much feasible as it as mini transport needs
comparatively smaller power for the power system. A 100 W
solar panel is good enough to support the daily power requirement.
However, the most challenging part of the solar
three-wheeler project is to use the limited solar energy effectively,
maximize its efficiency and ensure suitability/traffic
ability on our terrain. Successful implementation of the project
will depend on how successfully and exactly the problems are
indentified.
4 DESIGNING THE SOLAR THREE-WHEELER
Designing of the solar three-wheeler has two major
parts/aspects. Firstly, Designing the three-wheeler and it’s
components from mechanical and biomechanics point of view
and secondly, incorporation of solar power system to the improved
manual three-wheeler to achieve automation. Drawbacks
of the available manual three-wheelers as well as needs
and requirements from the disabled people (users) are seriously
considered while making definite improvement in designing.
Effective use of limited solar energy (due to limited
space/module), energy storage and power requirement (load)
are also seriously considered to balance and optimize the solar
power system of the solar three-wheeler.
4.1 DESIGN PHASES
The overall designing of the solar three-wheeler is done
through different phases as: recognition of the needs, definition
of problem, synthesis, analysis and optimization, evaluation
and presentation Firstly, the demand or requirements
from the disabled people are identified. Then the human r equirements
are translated to technical requirements, which include all the specifications or characteristics for the solar
three-wheeler to be designed. Then the solar three-wheeler
under design has been analyzed to whether it complies with
specifications. Once complied, then it was optimized and
leaded to a successful design. Sometimes, the analysis may
reveal that the system is not an optimum one. In evaluation
phase, testing of the solar three-wheeler is done and finally it
is presented to others.
4.2 USER’S NEEDS AND REQUIREMENTS
A general survey had been conducted among disabled people
who are using wheel chairs and manual three-wheelers. They
had been interviewed on some specific questions and their
problems/needs had been investigated and identified. They
came out with their problems, requirements, opinions as well.
Basically these are the requirements from the physically disabled
persons using manual wheel chair/three-wheelers. The
opinions and advices of the experts working with the disabled
people are also taken in to consideration. Their overall needs
and requirements can be described as: the three-wheeler
should be power driven to avoid physical force, it can be used
at any time either in day or night, having lighter weight with
better safety and stability, easy to control and better maneuverability
in case of narrow space/roads, comfortable, all terrain
traffic ability/mobility and suitable for indoor as well as outdoor
use, having available solar power to drive the threewheeler
in average15~20 km distance per day, able to protect
the user from the adverse environment like sunshine, rain etc.,
having availability of spares, ease of maintenance and finally
cheaper price.
4.3 DESIGN CONSIDERATIONS
Design considerations refer to some characteristics, which influence
the design of the element or, perhaps the entire system.
The strength of each element, its dimension and geometry are
important design consideration from the mechanical point of
view. As a transport for the physically disabled people the
overall safety, stability, reliability, control, comforts etc are a
very much important and taken in to consideration while designing
it. However, the general points of consideration during
the designing of the solar three-wheeler are: simplicity,
strength, stability, safety, corrosion and wear, weight, size,
flexibility, ease of control, modularity, efficient extraction of
solar energy, effective use of solar energy and energy storage,
all terrain tires for all terrain traffic ability/mobility, increased
suspensions, biomechanics and comforts and cost.