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Designing a Wheelchair Attachment to Transport Merchandise and Cargo in Less Resourced Settings

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Abstract and Figures

This project is based on a real charity case and has received support from the original design team of SafariSeat (an all-terrain wheelchair). The client from Sierra Leone hopes to design a detachable trailer so that users of SafariSeat can conduct various trades and merchandise sales. Designers need to design the SafariCart from both user experience and engineering aspects, and fully consider localized manufacturing and maintenance. The final design will be tested and mass-produced in Kenya. They will eventually be sent to Sierra Leone to provide jobs to a group of disabled people.
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A Collaborative Design Project with SafariSeat:
Designing a Wheelchair Attachment to Transport
Merchandise and Cargo in Less Resourced Settings
INDD341 Individual Project - FINAL PROJECT REPORT
Sifan Yan – 201448722
May 2021
Supervisor: Dr Farnaz Nickpour PhD, MA, ProBIDA, FHEA, FRSA
Dept. of Industrial Design
School of Engineering
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ABSTRACT
This project is based on a real charity case and has received support from the original design team of
SafariSeat (an all-terrain wheelchair). The client from Sierra Leone hopes to design a detachable trailer so
that users of SafariSeat can conduct various trades and merchandise sales. Designers need to design the
SafariCart from both user experience and engineering aspects, and fully consider localized manufacturing
and maintenance. The final design will be tested and mass-produced in Kenya. They will eventually be sent
to Sierra Leone to provide jobs to a group of disabled people.
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TABLE OF CONTENTS
ABSTRACT 2
TABLE OF CONTENTS 3
LIST OF FIGURES 9
LIST OF TABLES 9
1.0 INTRODUCTION 10
1.1 SafariCart Project 10
1.2 SafariSeat 10
1.3 Bakery in Sierra Leone 11
2.0 DESIGN PROCESS 12
2.1 Model Selection 12
2.2 Proposed Process 12
2.3 Project Time Plan 15
3.0 BACKGROUND 16
3.1 Literature Review 16
3.2 Resources and support 18
3.3 Parallel product 22
4.0 EMPATHIZE 28
4.1 Virtual tour in Sierra Leone 29
4.2 Customer requirements and analysis 31
4.3 User Interaction Map 36
5.0 DEFINE & IDEATE 38
5.1 Define Key Requirements 38
5.2 IDEATE 38
6.0 Embodiment Design 44
6.1 Modification of SafariSeat 44
6.2 Connector 45
6.3 Underpan 45
6.4 Upper frame for bread selling 47
7.0 PROTOTYPE & TEST 48
7.1 Usability Self-Testing Platform 48
7.2 Virtual PrototypeVP49
7.3 Design Refinement & Finite element analysis 53
8.0 FINAL PROPOSAL 56
8.1 Product overview 57
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8.2 Parts, Materials, Processes 58
8.3 Design Details 60
8.4 Final feedback from collaborators 64
9.0 IMPLEMENT 65
9.1 Actual Prototype 66
9.2 Usability testing and ethics 67
9.3 Production & Shipment 68
9.4 Application 68
9.5 Other possibilities of the underpan 68
9.6 SafariCart 2 68
10.0 REFLECT 69
10.1 Methodology 70
10.2 Design 70
10.3 Tool and Resources 70
10.4 Overall Conclusion 71
11.0 REFERENCES 71
12.0 APPENDICES 73
12.1 Gantt Chart 74
12.2 Technical drawings 75
12.3 Virtual Prototype 76
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LIST OF FIGURES
Figure 1.1 SafariSeat project timeline. 15
Figure 1.3.2 Location of the bakery. 16
Figure 1.3.2 Workers in the bakery(Jannah, 2020). 16
Figure 2.1 Design thinking 101 Model (Gibbons, 2016). 17
Figure 3.2.1 Interface of Autodesk fusion 360 (Autodesk, 2020). 24
Figure 3.2.3 The Accessibility Institute Logo. 24
Figure 3.2.4.1 Workers working in the SafariSeat Workshop (Inclusionaries Lab, 2020). 25
Figure 3.2.4.2 A worker welding parts in the SafariSeat Workshop (Kahindi, 2020). 26
Figure 3.2.4.3 A worker using the tube bender in the SafariSeat Workshop (Kahindi, 2020).
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Figure 3.2.4.4 A worker using the circular saw in the SafariSeat Workshop (Kahindi, 2020).
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Figure 3.3.1.1 Tricycle wheelchair (APDK Mobility Aid Workshop, 2020) 28
Figure 3.3.1.2 RoughRider Wheelchair (Whirlwind, 2020) 29
Figure 3.3.1.3 Freedom Chair: 3.0 (Grit freedom chair, 2020) 29
Figure 3.3.1.4.1 SafariSeat (Seers, 2018) 30
Figure 3.3.1.4.2 SafariSeat functions - frame (safariseat.org, 2020) 30
Figure 3.3.2.1 Side view of the APDK tricycle wheelchair(APDK Mobility Aid Workshop,
2020). 31
Figure 3.3.2.2 Bicycle Panniers and rigs (Bikepacking, 2020). 32
Figure 3.3.2.3 Vending Bicycle for able bodied people (Ferla, 2020). 32
Figure 3.3.2.4 Water container cargo platforms (AtomicZombie, 2020). 33
Figure 3.3.2.5 Rollikup Plus Wheelchair Trailer (BikeBEP, 2020). 33
Figure 4.1.1 Freetown - urban area(Google Earth, 2021). 34
Figure 4.1.2 Freetown - rural area(Google Earth, 2021). 34
Figure 4.1.3 Freetown - Hillside(Google Earth, 2021). 35
Figure 4.1.3 Freetown - Seaside(Google Earth, 2021). 35
Figure 4.2.1.1 A lady waiting around ATMs to beg(Jannah, 2020). 36
Figure 4.2.1.2 User Image of SafariCart. 36
Figure 4.2.1.3 User Requirement Statement. 37
Figure 4.3.1. The user interaction map. 42
Figure 5.2.1 The three possibilities. 44
Figure 5.2.1.1 Initial Concept - Front. 45
Figure 5.2.1.2 Initial Concept - Side. 46
Figure 5.2.1.2 Initial Concept - Back. 47
Figure 6.1.1 Center of rotation. 49
Figure 6.1.2 modification of rare beam. 49
Figure 6.2.1 The 2 degrees of freedom. 50
Figure 6.2.2 The early stage T-bar design. 50
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Figure 6.3 The early stage supporting leg design. 51
Figure 6.4 Baking tray. 52
Figure 7.1.1 Usability Self-testing Platform. 53
Figure 7.1.2 Designer working on the Usability Self-testing Platform. 54
Figure 7.2.1 First Generation VP. 55
Figure 7.2.2 Second Generation VP. 56
Figure 7.2.3 Third Generation VP. 57
Figure 7.3 Final finite element analysis result. 61
Figure 8.1 Final rendering 1. 62
Figure 8.2 Final rendering 2. 62
Figure 8.4 Collaborators in the final design review meeting. 69
Figure 9.1.1 Jig system of first generation SafariSeat (Deeble, 2015). 71
Figure 9.1.1 Current version SafariSeat - Using a jig to accurately position frame
components. (O'Sullivan, 2021). 71
Figure 9.5 Modification possibility of SafariCart. 73
Figure 9.6.1 Top view of SafariCart. 74
Figure 9.6.2 Tow Bar. 74
LIST OF TABLES
Table 2.1 Matching design processes with stages in design 101 model. 24
Table 2.3 SafariCart Project gantt chart 4/12/2020 version. 26
Table 3.2.1 Required software and description. 29
Table 3.3.1 Parallel product of SafariSeat. 34
Table 5.1 Define key requirements from five aspects. 49
Table 8.2 Parts, Materials, Processes 71
Table 8.3.1 Extreme loads. 71
Table 8.3.2 bill of cost. 72
Table 8.3.3 Consideration of Terrain adaptability. 73
Table 8.3.4 Consideration of Design for Safety. 74
Table 8.3.5 Consideration of Failure Mode 75
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1.0 INTRODUCTION
1.1 SafariCart Project
The SafariCart project is based on a real charity case and has received support from the original design
team of SafariSeat (an all-terrain wheelchair). The client from Sierra Leone hopes to design a detachable
trailer so that users of SafariSeat can conduct various trades and merchandise sales. Designers need to
design the SafariCart from both user experience and engineering aspects, and fully consider localized
manufacturing and maintenance. The final design will be tested and mass-produced in Kenya. They will
eventually be sent to Sierra Leone to provide jobs to a group of disabled people.
1.2 SafariSeat
Figure 1.1 SafariSeat project timeline.
Figure 1.2 A local kenyan leaving their home in a SafariSeat (Inclusionaries Lab, 2020).
SafariSeat is a low-cost all-terrain wheelchair that has attracted worldwide attention. It has a relatively small
turning radius and good adaptability to rough ground, and can be repaired with bicycle parts. Starting from a
student project, after many iterations, it was successfully applied in Africa, established a local production
base, and has a practical supply chain and distribution methods (Deeble, 2015; Inclusionaries Lab, 2020).
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1.3 Bakery in Sierra Leone
Figure 1.3.2 Location of the bakery.
Figure 1.3.2 Workers in the bakery(Jannah, 2020).
This design project was created in collaboration with a charitable organisation in Sierra Leone who run a
bakery, employing local disabled individuals to make and sell baked goods. The bakery wanted to find a way
for SafariSeat wheelchair users to distribute and sell their baked goods across the city streets.
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2.0 DESIGN PROCESS
2.1 Model Selection
Figure 2.1 Design thinking 101 Model (Gibbons, 2016).
In order to allow the cooperators of diverse backgrounds across five countries to have a unified and in-depth
understanding of the design process. The Design Thinking 101 model is used in the process of project
planning and team communication.
This model plans a series of design stages and return paths, allowing designers to continuously optimize
their design within the specified framework and clearly recognize their progress.
Different from the traditional double diamond model, it puts ‘empathize’ in the beginning of design stages,
which makes it in line with UX and inclusive design theory. Moreover, clear design stages of this model are
conducive to clarify the design process to team members engaged in manufacturing and charity work,
enhancing communication efficiency and obtaining relevant suggestions from them.
2.2 Proposed Process
In order to clearly combine the design work required by this project with the Design Thinking 101 model, a
refined model according to the module brief was produced. It includes a detailed worklist under each of the
six design stages. Completing these tasks will meet the basic requirements of the module.
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STAGE
PROCESS
Empathize
This stage includes the collection of all background information
and the determination of user groups, determining the basic
design specifications and user requirements, and finally
producing a highly general User interaction map.
Background Research
Virtual Tour
Persona & Scenario
PDS & URS
User Interaction Map
Define
Based on the research results summarized in the previous
stage, clear product requirements will be defined from the
aspects of engineering, users, manufacturing, and
implementation.
From User
From Safariseat
From Workshop
From Supplier
From Client
Ideate
At this stage, multi-directional design exploration will be carried
out, and the basic design concept will be obtained after all the
results are reviewed.
Brainstorming & PMI
Modification
Connector
Underpan
Upper frame
Prototype
At this stage, a 1:1 self-testing platform will be built and the
iterative design of the virtual prototype will be started.
1:1self-testing platform
Virtual Prototype*N
Test
At this stage, a series of tests will be conducted on the virtual
prototype machine to verify the mechanical performance and
usability of the design.
Self usability test
Finite element
Design refine
Final Design
Implement
The actual project will come to an end at the Final review
meeting, but subsequent implementation measures will also be
considered in the design stage.
Final review meeting
Actual prototype
Usability test
Production & Shipment
Application
Table 2.1 Matching design processes with stages in design 101 model.
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The six stages are divided into two semesters. The first semester includes Empathize, Define, and Ideate. It
focused on literature review and team interviews to find exact user needs, develop design challenges based
on URS, and get specific design concepts. The second semester includes Prototype, Test, and Implement. It
will mainly be about production-level detailed design, prototype making and testing, and try to commercialize
design concepts.
Figure 2.2 Refined design 101 Model with detailed worklist.
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2.3 Project Time Plan
In order to clarify the tasks that should be completed in each time period of the two semesters, a Gantt chart
of the entire project was created. All times are accurate to the week and have a clear order of completion. It
is important to note that the five main courseworks are also included in the Gantt chart.
Table 2.3 SafariCart Project gantt chart 4/12/2020 version.
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3.0 BACKGROUND
3.1 Literature Review
3.1.1 Necessity of design.
The socio-economic conditions of people with disabilities are often much worse than those of other
populations. A fact that is wide recognized is, disabled people are more likely to be poor and unemployed,
have less education, live in rural areas, and have less access to health care facilities than their non-disabled
peers (Bremer, Cockburn, & Ruth, 2009; Filmer, 2008; Smith et al, 2004; Stein et al, 2009). In extremely
impoverished places, persons with disabilities have more limited access to jobs and services (Elwan, 1999;
Yeo & Moore, 2003). They are likely to fall into a disability-poverty cycle (Banks, Kuper, & Polack, 2017).
Due to limited education and training, it is difficult for people with disabilities to be employed in technical jobs
(Curvers et al, 2016, cited in Rohwerder,2020, p. 22). Changing this phenomenon requires long-term efforts
to establish systematic training and right protection measures.
Job opportunities such as trades, crafts and sales in the street requires less education or training, can
quickly generate income to improve living conditions and reduce the possibility of falling into chronic poverty
(Banks, Kuper, & Polack, 2017). Encouraging these positions can also promote local economic growth,
thereby improving the living conditions of all local people. Memula from Sierra Leone who is engaged in
charity, proposed a concept of helping local disabled people by creating these job opportunities.
In order to create opportunities for the disabled in Sierra Leone to perform trades, crafts and sales. A
measure of storage and transportation is needed. A feasible solution is to design an inclusive wheelchair
attachment to realize the function of storage and transportation. Transforming the wheelchair into an
income-generating tool will also increase the likelihood of individuals securing microcredit financial support
to get access to a SafariSeat, making it a more viable, sustainable and accessible solution for a far wider
group of individuals (Kaboski & Townsend, 2009).
3.1.2 User needs in Sierra Leone.
Sierra Leone is a West African country with beautiful land and people. But in the 21st century, it is one of the
poorest countries in the world, with a low life expectancy (37 years), a high infant mortality (146 per 1000), a
low literacy rate (31%), and an HIV/AIDS threat to the population (4.9% were known to be infected) which
was expected to increase (Government of Sierra Leone, 2002). Since 1990, the "blood diamond" industry,
armed conflict and warlord rule have greatly increased the number of disabled people in the country.
A study summarized the barriers and needs of local people with limited mobility under 3 typical situations
(Myriam dos SantosZingale & Mary Ann McColl, 2006):
i. When fleeing the conflict their main preoccupation was with mobility and survival and the main facilitator
was the support or barrier they had from people (family, friends or strangers), which often made the
difference as to whether they survived or not.
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ii. When settling in a temporary camp their main challenges were survival and selfcare, with more
examples of lack of social involvement. The support and relationships and the attitudes of people, as
well as the services provided such as the supply lines, the camp registration process, the medical
services, including assistive devices, were the biggest barriers to their participation.
iii. When settling at the end of the war in a more permanent setting, the challenges faced were more within
the major life areas (employment and education) and community and social life domains, although daily
survival did remain a struggle. The main environmental barriers were the services such as
transportation, medical care, assistive devices, and government programmes, the support and the
attitudes of those around.
This project focuses on the needs of the third situation and can also reduce the survival pressure of people
in the first two situations.
3.1.3 Market statistics.
There are currently around 75 million people in need of a wheelchair globally, yet only 5% to 15% of them
have access to one (WHO, 2020). In Sierra Leone, the disabled group faces a more severe situation. If
people with disabilities account for 15-20% of the poor (Elwan, 1999), and Sierra Leone government
statistics (2002) are reliable, and 80% of the population is considered poor, then at least 12% to 16% of the
population are impoverished and disabled, which are the target user of the project.
They are deeply trapped in the disability-poverty cycle, and have little purchasing power for the following
reasons (Elwan, 1999):
i. Disabled persons are discriminated against, are not regarded as equal citizens, and are not given equal
opportunities;
ii. Therefore, their participation is restricted by all levels of society, especially in employment, education or
training, and community activities;
iii. Because they do not have training or work, they have no financial means to conduct business or send
their children to school; because they do not participate in community meetings, they do not participate
in any decision-making related to their village, city or country;
iv. Therefore, they are still very poor and need assistance to survive. They have no right to change
anything because their voices are not heard.
Therefore, donation and microcredit financial support will be the main way to deliver wheelchairs and
accessories to the disabled.
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3.2 Resources and support
3.2.1 Software
Name
Description
Sketchbook (ios)
Produce digital sketches for design communication
Procreate (ios)
Produce digital sketches for design communication
Xmind (ios)
Produce mindmap
Microsoft Excel
Tables
Microsoft Word
Reports
Microsoft Powerpoint
Produce Powerpoint for communication
Microsoft Visio
Flow Chart
Microsoft Project
Gantt Chart
Autodesk Fusion 360
1. CAD modeling
2. Finite element analysis
3. High quality rendering
Adobe PS
Graphic editing (Pixel)
Adobe Ai
Graphic editing (Vector)
Adobe Pr
Video editing
Adobe Xd
Simple 2D animation
3Ds max
Simple 3D animation
Zoom
Online meeting with collaborators
Microsoft Teams
Online meeting with supervisor
Table 3.2.1 Required software and description.
Throughout the design process, the above 16 kinds of software were used to realize the visual output of
each design stage. In particular, it should be pointed out that Autodesk fusion 360 undertakes the main
CAD, finite element analysis, and rendering work.
In order to meet the basic completion conditions of this module, at least one production-level CAD model of
the modular attachment should be designed and built. To achieve this goal, Autodesk fusion 360, an
integrated CAD design software, is recommended by the SafariSeat team.
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Figure 3.2.1 Interface of Autodesk fusion 360 (Autodesk, 2020).
Different from Rhinoceros and CREO, it has accurate and diversified 3D feature generation tools as well as
a logically clear model tree, which made it convenient for designers, engineers and manufacturers. It allows
team collaboration, which means that each member of the SafariSeat team can view the latest progress of
the model at any time and communicate efficiently. The SafariSeat product itself was designed, improved,
and put into production via this platform, which makes it also facilitate the modular docking of the attachment
and SafariSeat in the later design.
3.2.2 Covid Situation
Due to the impact of the Covid-19 epidemic, the university's requirements for this module have changed.
The physical model is no longer needed. Instead, the designer needs to create a virtual prototype.
At the same time, because of the cancellation of flight, the designer can only choose to complete the entire
project at his home in Wuhan, China. This means in the communication of the entire team, the reduction of
communication efficiency caused by time difference is inevitable.
3.2.3 Funder
Figure 3.2.3 The Accessibility Institute Logo.
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The Accessibility Institute(TAI) is a non-governmental organisation based in Sweden, who funds the
manufacture and distribution of high quality, affordable and locally manufactured mobility aids across
developing regions of the world, such as SafariSeat. TAI also manages and funds new research and
development projects such as this one, which was established through their partnership with the bakery in
Sierra Leone.
In this project, the CEO of TAI will participate in the review of the final proposal with the client to determine
whether the project can produce a prototype in Kenya and enter the usability test. If the project passes the
final review and enters the usability test, TAI will fund the production and subsequent improvement costs of
the prototype, and be responsible for the ethics of the usability test.
3.2.4 SafariSeat Workshop
Figure 3.2.4.1 Workers working in the SafariSeat Workshop (Inclusionaries Lab, 2020).
The safariseat workshop is located in Kilifi, Kenya. This labor-intensive workshop relies on local materials
and supply chains to produce SafariSeat wheelchairs in batches. Simple cutting, bending, welding and
painting processes are completely achievable, but there is a lack of heavy machines to achieve complex
processing techniques.
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Figure 3.2.4.2 A worker welding parts in the SafariSeat Workshop (Kahindi, 2020).
Figure 3.2.4.3 A worker using the tube bender in the SafariSeat Workshop (Kahindi, 2020).
Figure 3.2.4.4 A worker using the circular saw in the SafariSeat Workshop (Kahindi, 2020).
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Figure 3.2.4.5 A worker drilling holes on metal parts in the SafariSeat Workshop (Kahindi, 2020).
Taking the final review as the dividing line, the SafariSeat workshop will provide technical support to the
designer in two stages. Before the final review, the workshop manager will participate in monthly design
reviews to provide feedback on the latest design in terms of production process, maintenance difficulty,
price, etc., and provide detailed prices for each component after the design is finalized. After the final review,
the SafariSeat workshop will undertake the manufacturing of the prototype.
3.3 Parallel product
In order to verify the necessity of designing this attachment, a series of similar products of SafariSeat and
the storage attachment were analyzed. It should be noted here that the products mentioned in this section
do not directly constitute a commercial competition relationship with SafariSeat or storage attachment. They
come from the retail industry, other charity projects or medical industry.
3.3.1 Parallel product of SafariSeat
Name
APDK tricycle
wheelchair
RoughRider
Wheelchair
Freedom Chair:
3.0
SafariSeat
(control group)
Appearance
Terrain
adaptability
Normal
Good
Very Good
Very Good
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Maintenance
difficulty
Easy
Easy
Almost impossible
Easy
Additional
functions
luggage carrier
(50KG)
N/A
N/A
Side luggage rack
Price
$160
$450
$2995
$250
Table 3.3.1 Parallel product of SafariSeat.
This is a comparison between safariseat and the other three parallel products. They were compared from
four aspects: Terrain adaptability, maintenance difficulty, additional functions, and price. A more detailed
description of each product is as follows.
3.3.1.1 APDK tricycle wheelchair
Figure 3.3.1.1 Tricycle wheelchair (APDK Mobility Aid Workshop, 2020)
A cheap and affordable tricycle wheelchair designed by APDK Mobility Aid Workshop. It is equipped with a
strong luggage carrier at the rear which carries weight up to 50 kgs. Subsequently the users can also
operate a small business to empower them economically. This wheelchair is widely used in Kenya.
Price: $160
Terrain adaptability: Normal, the front-wheel-drive tricycle has a good performance on flat ground,
but it has a large turning radius and is not easy to deal with rugged terrain or steep slopes.
Maintenance difficulty: Easy, It can be repaired by any technician even in the rural areas.
Additional functions: luggage carrier (50KG),need to twist the upper body by almost 180° to reach,
not very user friendly.
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3.3.1.2 RoughRider Wheelchair
Figure 3.3.1.2 RoughRider Wheelchair (Whirlwind, 2020)
The RoughRider wheelchair is manufactured with local materials and standard bicycle parts. It can be
repaired by any Technician even in the rural areas. The wide front wheel is made of solid rubber which has a
long life span, is puncture free and designed specifically to cope with the African terrain.
Price: $450
Terrain adaptability: Good, the four-wheel rear-wheel drive mode has a good performance on flat
ground and slopes, but when encountering rugged ground, a certain wheel may be off the ground.
Maintenance difficulty: Easy, It can be repaired by any technician even in the rural areas.
Additional functions: N/A
3.3.1.3 Freedom Chair: 3.0
Figure 3.3.1.3 Freedom Chair: 3.0 (Grit freedom chair, 2020)
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A competition level wheelchair suited for riders who want to ride over grass, unpaved trails, mud, and sand.
Price: $2995
Terrain adaptability: Very good, the rear-wheel-drive tricycle has a good performance on rugged
terrain or steep slopes.
Maintenance difficulty: Almost impossible, all parts should be shipped with a high price.
Additional functions: N/A
3.3.1.4 SafariSeat
Through comparison, it can be found that SafariSeat has outstanding terrain adaptability and relatively low
price. There is also a large space on the back to accommodate accessories. But compared with the tricycle
wheelchair, it has no practical storage and transportation functions, which limits the possibility of users to
develop small businesses. Therefore, it is necessary to design an accessory with storage, transportation,
and display functions to encourage income generation.
Figure 3.3.1.4.1 SafariSeat (Seers, 2018)
Figure 3.3.1.4.2 SafariSeat functions - frame (safariseat.org, 2020)
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Price: $250
Terrain adaptability: Very good, the four-wheel front-wheel drive mode combined with an ingenious
chassis structure, it has good maneuverability on flat or steep slopes, while keeping four wheels on
the ground on rugged terrain(Deeble, 2015).
Maintenance difficulty: Easy, It can be repaired with bicycle parts (Inclusionaries Lab, 2020).
Additional functions: Luggage rack on the side.
3.3.2 Parallel products of the storage attachment.
For the storage attachment, the definition of similar products has become even more vague. As an
accessory of an unconventional structure wheelchair, there is no direct competitor product, so in this section,
several products that provide inspiration for subsequent design will be listed.
3.3.2.1 Luggage carrier of the tricycle wheelchair
Figure 3.3.2.1 Side view of the APDK tricycle wheelchair(APDK Mobility Aid Workshop, 2020).
There are not many products with similar market positioning to this attachment, one the closest is the
luggage carrier of the tricycle wheelchair. It is cheap, easy to manufacture, large in volume (compared with
the SafariSeat luggage rack), waterproof and dustproof, and has high structural strength. Its disadvantage is
that it cannot display goods and is not user friendly - the user needs to rotate the upper body nearly 180° to
open it.
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3.3.2.2 Bicycle Panniers and rigs
Figure 3.3.2.2 Bicycle Panniers and rigs (Bikepacking, 2020).
Bicycle Panniers and rigs are a series of modular storage systems on mountain bikes. They are made of
canvas or similar materials and fixed to the bicycle frame. They can be installed and removed independently
and have good waterproof performance. But they have insufficient capacity, no display function, and
irregular shapes.
3.3.2.3 Vending Bicycle for able bodied people
Figure 3.3.2.3 Vending Bicycle for able bodied people (Ferla, 2020).
This bicycle provides solutions for storage, transportation and display of goods for able bodied people. Allow
them to start their own small business through financing. It can be used in many scenarios: selling fruit,
candy, grocery, delivery packages, beverages, etc.
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3.3.2.4 Water container cargo platforms in Africa
Figure 3.3.2.4 Water container cargo platforms (AtomicZombie, 2020).
This is a simple-made transportation platform with exaggerated carrying capacity. The disadvantage is that
with the super long body, the turning radius becomes very large, which makes it unsuitable for passing on
narrow streets.
3.3.2.5 Rollikup Plus Wheelchair Trailer - pivots to side of user
Figure 3.3.2.5 Rollikup Plus Wheelchair Trailer (BikeBEP, 2020).
Similar to the desired modular attachment, Rollikup Plus Wheelchair Trailer is an inclusive wheelchair
attachment. It uses a simple rotating structure to achieve a more user-friendly reaching method. It can't
display anything inside, and the price is $1,063, relatively expensive.
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4.0 EMPATHIZE
4.1 Virtual tour in Sierra Leone
To have a preliminary understanding of the local terrain and street conditions, the designer visited Freetown,
where the bakery is located, through Google Earth. The author collected some typical landforms and
environments through screenshots as an important reference for subsequent design.
Figure 4.1.1 Freetown - urban area(Google Earth, 2021).
Figure 4.1.2 Freetown - rural area(Google Earth, 2021).
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Figure 4.1.3 Freetown - Hillside(Google Earth, 2021).
Figure 4.1.3 Freetown - Seaside(Google Earth, 2021).
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4.2 Customer requirements and analysis
4.2.1 User Image
Figure 4.2.1.1 A lady waiting around ATMs to beg(Jannah, 2020).
The user Image was created based on the client’s street photography in Sierra Leone. These works were
very generously shared on the team’s Google Drive.
Figure 4.2.1.2 User Image of SafariCart.
It is particularly important to point out that in the scenario, the user needs to buy daily necessities nearby
after the goods are sold on the day of sale, and load them home with SafariCart. This part needs to
correspond strictly to the UIM mentioned above.
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4.2.2 User Requirement Specification (URS)
Figure 4.2.1.3 User Requirement Statement.
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4.2.3 Product Design Specification (PDS)
1. Performance
Speed: 5 -10 kph or lower – the same speed with SafariSeat
Maximum load: 30-50 kg, 50kg would be best to compete with the
tricycle wheelchair.
Maximum volume: 30-50L, One or two gas/water tanks can be
transported
It must be able to navigate rough terrain, overcoming obstacles as
large as 15cm.
Loaded goods can be displayed.
The add-on should be customizable to suit the users’ size.
Storage space shall be airtight to a certain extent to prevent
contamination of the cargo.
Storage space should have anti-theft measures.
Must have a turning circle small enough when attached on SafariSeat
to make it manageable indoors.
2. Product Lifespan
Usage Frequency: Every day, for at least 14 hours
Service life: 5-7 years, without significant and costly mechanical
failure.
3. Environment (during manufacture, storage and use)
In general, it should conform to the tropical monsoon climate of Sierra
Leone.
Temperature: mainly 26-36°C, when cool, dry winds blow in off the
Sahara Desert and the night-time temperature can be as low as 16 °C
Humidity: 80%-100% for most time
Risk of corrosion and contamination: Sulfur-containing particles and
gases produced by burning wood, gasoline, kerosene. Heavy metal
particles, dust, sewage produced by the mining industry.
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4. Target product cost
Device must cost less than £60 to manufacture.
Device must retail to end-users for no more than £125 - half of the
current price of SafariSeat
The prototype must not cost more than £160 to produce.
5. Competition
Most direct competitor: the luggage rack of the tricycle wheelchair.
Uniqueness in competition: Reasonable price, terrain adaptability,
inclusiveness and user-friendliness of the product and SafariSeat.
6. Quantity and manufacture
It should be made in batches in the SafariSeat workshop, Kenya.
The frame can be quickly manufactured with a jig system.
The overall assembly can be completed by a single person
independently.
Parts that require precision machining can be found in the local
supply chain.
7. Materials
The frame and main structure will use the same steel pipe and iron
sheet as SafariSeat to simplify the supply chain.
20L plastic drinking water barrels will be considered. It will be simply
cut and fixed on the frame if selected.
8. Quality and consistency
The market hopes that such products have the longest service life if
possible, and they will be used continuously until they cannot be
repaired.
9. Standards
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The product must meet the standards of the Sierra Leone
government for unpowered transport vehicles (if existed).
Must conform to the British standard BS ISO 7176-8:1998 for
strength and reliability.
10. Patents
The overall form of the product and the connection with SafariSeat
will have the possibility of registering a utility model patent. The use
of patents will be uncharged to encourage subsequent localized
production.
11.Packaging, shipping and distributing
The product may be transported short distances without packaging.
Batches of the products will be packed and shipped in batches in
containers for sea transportation, or transported by road over 7,000
kilometres to reach Sierra Leone.
Products will be distributed by authorized charitable organizations,
or become part of a small loan project.
A manual should accompany the add-on detailing the correct
maintenance procedures.
12. Aesthetics and ergonomics
The appearance of the product should be in harmony with the style
of SafariSeat.
Products should try to achieve the best terrain adaptability,
inclusiveness and user-friendliness.
13. Market constraints
Our users are over 15 years old with lower limb disability, who can
manually self propel a wheelchair.
A small and immature market has been created by the tricycle
wheelchairs. Our products need to expand this market to benefit
more disabled people.
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The product will be designed in the 2020-2021 academic year, and
subsequent production and commercialization work may last for a
year or more.
Users want products as durable as possible.
14. Company constraints
The product should fit in with the company image of SafariSeat.
Material or process choice is strictly limited by local production
capacity and supply chain.
Propaganda and distribution should focus on the life of the disabled
and economic needs. Sensitive political or ideological topics should
be avoided.
4.3 User Interaction Map
According to PDS, URS, and further literature collection, a user interaction map (UIM) was created to clearly
outline the three levels facilitated by this product, as well as the corresponding stakeholders, services, and
people. First of all, users need to get a job through this product, and interactions within this range should be
fully considered. Secondly, users need to improve their quality of life through this product, and extreme
situations such as oversized and heavy loads need to be considered within this range. Finally, this product
will bring users a new social life and enhance their sense of dignity. At this level, new possibilities need to be
paid attention to, such as other potential employers. The practical significance of this project will depend on
whether the various interactive scenarios, load, and interest relationships in this map can be fully
considered.
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Figure 4.3.1. The user interaction map.
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5.0 DEFINE & IDEATE
5.1 Define Key Requirements
According to URS, PDS and UIM, the key requirements are broken down into five parts to further clarify the
focus of the design: from User, from SafariSeat, from workshop, from supplier, from client.
From user
The user can independently complete the connection and
disconnection of the trailer, the retracting and placing of the supporting
legs (if any), the opening and closing of the cargo door (if any), and the
taking out and putting back of the cargo. In addition, the trailer needs
to be capable of transporting at least one 25-liter gas tank.
From SafariSeat
Suspension system
The trailer needs to retain the terrain adaptability of SafariSeat and be
firmly connected to the body under the premise that the suspension
system can move normally.
Casters
All parts of the trailer should try to avoid the sweeping area of the
SafariSeat casters
From workshop
Most parts of the trailer should use the same raw materials and
processing techniques as SafariSeat.
From Suppliers
Any other materials or ready parts need to be confirmed with the
workshop manager if they are available.
From Client
The trailer should have room for subsequent modifications.
Table 5.1 Define key requirements from five aspects.
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5.2 IDEATE
5.2.1 Concept generation
Figure 5.2.1 The three possibilities.
In the initial stage of concept generation, the relative position of the accessory and SafariSeat is first
considered. As shown in Figure 5.2.1, the accessory may be located in front of the wheelchair or on the
side. Of course, the most traditional way is to pull on the back of the wheelchair. In response to these three
situations, the designer conducted a preliminary sketch deduction around the basic frame and put forward
three proposals.
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5.2.1.1 Front
Figure 5.2.1.1 Initial Concept - Front.
If the accessory is located in the front, it will most likely be connected to the two front pillars. Since the front
cart may block the view, its volume cannot be too large. On the premise that the steering form of the
wheelchair does not change, this form of attachment needs to use casters to adapt to the changing direction
of movement. Considering that the accessory needs to remain standing when connected and disconnected,
at least four fixed or ground contact points as shown in the figure are required, so that when the user
disconnects any connection point, Fujian can maintain a stable three-point support structure.
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5.2.1.2 Side
Figure 5.2.1.2 Initial Concept - Side.
If the accessory is on the side, the luggage rack mentioned above is the most likely fixing point, but loading
tens of kilograms of goods on one side will seriously affect the center of gravity of the wheelchair, and
loading on both sides will have a large impact on the width of the wheelchair, so It is not practical to rely
solely on the existing structure of the luggage rack.
Therefore, the concept of this initial proposal was converted to "accessories located on the side of the
wheelchair when in use" and proposed a tow bar connection structure as shown in Figure 5.2.1.2. When
moving, the accessory is pulled to the back of the wheelchair through a tow bar, and when the user needs to
operate on the accessory, the user reverses to the side to rotate the accessory to the side of the wheelchair.
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5.2.1.3 Back
Figure 5.2.1.2 Initial Concept - Back.
If the attachment is at the back, in order to distinguish it from the side proposal, a proposal that the
attachment is bound to the orientation of the wheelchair is proposed. Through some kind of hinge structure,
the accessory is fixed on the back of the wheelchair. It should have an independent supporting leg and
user-friendly connection mechanism, which can be quickly disconnected after the user reaches the
destination. Under this concept, the structure shown in Figure 5.2.1.2 is proposed. Although the use of fixed
wheels lacks rationality, its general concept is reasonable, so it is used as the third proposal in the
evaluation.
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5.2.1.4 Concept Evaluation (PMI)
Table 5.2.1.4 Plus-Minus-Interesting .
After introducing and obtaining feedback with the CTO, a round of PMI (Plus-Minus-Interesting) analysis was
conducted for these three initial proposals. Although there are no specific design details, at this stage, it is
possible to predict and analyze the advantages, disadvantages, and interesting points of these three
proposals, and list subjective weights for each item based on feedback from the CTO.
The results are shown in Table 5.2.1.4. Unexpectedly, the back proposal got the highest score (it should be
noted that the fixed wheels of this proposal were changed to casters during communication). For the first two
proposals, the most noteworthy thing is the distribution of degrees of freedom(DoF) of side proposals. At this
level, more efforts are needed to explore an even more reasonable solution.
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6.0 Embodiment Design
6.1 Modification of SafariSeat
Figure 6.1.1 Center of rotation.
The frame on both sides of SafariSeat rotates relative to the rear beam as the axis to achieve the four-wheel
landing even when the ground is uneven. This structure is also known as the suspension system of
SafariSeat.
Figure 6.1.2 modification of rare beam.
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Since the frames on both sides frequently rotate relative to each other, it is unrealistic to fix the trailer on
both sides at the same time. At the same time, if the trailer is only connected to one side frame, the load on
one side will be too large. Therefore, in order for the trailer to be firmly connected to the SafariSeat, it is the
best choice to fix it directly on the rear beam.
6.2 Connector
Figure 6.2.1 The 2 degrees of freedom.
The connector needs to provide the trailer with at least two degrees of freedom as shown in the figure, so
that the two casters of the trailer can touch the ground at any time. But if you follow this design directly, the
connection is blocked by the seat, which means that the user will not see the connection when connecting.
This brought very poor usability.
Figure 6.2.2 The early stage T-bar design.
In order to solve this problem, the connection between the wheelchair and the trailer should be moved within
the range that the user can see. In order to solve this problem, the connection between the wheelchair and
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the trailer should be moved within the range that the user can see when turning around. The original two
degrees of freedom are still retained, but they are concentrated in a small part, which is the T-bar.
6.3 Underpan
Figure 6.3 The early stage supporting leg design.
The underpan of SafariCart should be compatible with the same casters of SafariSeat to simplify the supply
chain. At the same time, he should have some kind of supporting leg so that he can stand independently
when disconnected. At the same time, the straight line passing the connecting point of the two casters
should be as close as possible to the center of gravity of the trailer, so that the casters can bear most of the
load and avoid the overload and deformation of the SafariSeat rear beam.
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6.4 Upper frame for bread selling
Figure 6.4 Baking tray.
The upper frame should be compatible with the bakery's workflow, that is, it has a certain disassembly and
cleaning function, just like a baking tray.
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7.0 PROTOTYPE & TEST
7.1 Usability Self-Testing Platform
As mentioned above, the designer has no choice but to complete the tasks for the entire school year at
home, which means that the designer will not have access to the department workshop. And this design
involves many complex actions beyond the standard anthropometric actions, so it is very necessary to
conduct a 1:1 simulation test in the middle of the design.
Obviously, in the designer's home, there is no large-scale processing equipment such as a sewing machine,
and there is no large area to test terrain adaptability. Therefore, from the consideration of feasibility, it is
more realistic to use a ready-made wheelchair and household appliances of different sizes to simulate the
size and position of different components and test their usability.
Figure 7.1.1 Usability Self-testing Platform.
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Fortunately, China has a large number of low-cost wheelchair products for designers to choose from, and
their prices are usually hundreds of RMB (tens of pounds). Therefore, after confirming the SarariSeat size
data, the designer purchased a wheelchair from Taobao at his own expense.
Although this wheelchair has a different layout of driving wheels from the SafariSeat and no suspension
system, it has almost the same seat height and width, and has very similar back handle features. This
makes it very suitable for the preliminary usability testing involved in this project. The designer also used
tennis trainers, electric fans, air purifiers and other household equipment to simulate the positions of various
components.
Figure 7.1.2 Designer working on the Usability Self-testing Platform.
This platform simulates the SafariSeat using scenario well and plays a key role in subsequent design
iterations.
7.2 Virtual PrototypeVP
After determining the basic back traction mode, the design entered the virtual prototype stage. A total of
three generations of virtual models were produced, of which the last generation carried out detailed design
and simulation, and turned into the final proposal.
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7.2.1 First Generation VP
Figure 7.2.1 First Generation VP.
The first generation of virtual prototypes includes connectors and underpan. It is used to discuss the
allocation of degrees of freedom and basic operating modes with the CTO and the workshop manager.
As shown in the figure 7.2.1, a dual-degree-of-freedom design is proposed in this generation of virtual
models. The support legs cannot be moved, and there is a handle on both sides with a limited rotation angle
to facilitate the connection and disconnection of the trailer and the wheelchair.
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7.2.2 Second Generation VP
Figure 7.2.2 Second Generation VP.
The second-generation prototype was optimized for production and usability, and the specific structure of the
connector appeared. The handle is bent at a certain angle to improve usability, and the shape of the
connecting leg is modified to avoid collision with the casters.
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7.2.3 Third Generation VP
Figure 7.2.3 Third Generation VP.
After having the creation experience of the first two generations VP, the third generation VP also considered
material selection, design details and surface treatment.
The rotary handle and the fixed support leg are integrated into a support leg that can move up and
down, and at the same time it plays the role of a handle when connecting and disconnecting.
The upper structure with storage and display functions is designed, and the main features are a
stable frame structure and aluminum partitions.
The surface of the mild steel frame uses the same powder layer as SafariSeat to prevent corrosion.
For the key iteration process of the three generations of VP, please see Chapter 7.3.
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7.3 Design Refinement & Finite element analysis
This part will focus on the important changes in the iterative process of the three generations of models. The
first two generations mainly made adjustments in terms of concept and usability, based on feedback from
the 1:1 test platform and the workshop manager. Finite element analysis is applied to the third-generation
VP to test the strength of key components and the overall structure.
Component / Feature
Refine
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Table 7.3 Design Refinements.
The above are the main visible design refinements. Many other details of the design have been fine-tuned in
size and position, but are not listed here due to word limitations.
Figure 7.3 Final finite element analysis result.
The final finite element analysis result of the main structure (steel) is shown in Figure 7.3. When 500N load
is applied to each layer and its own weight is taken into account, the maximum stress in the frame is
134.4MPa, and there is no obvious stress concentration.
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8.0 FINAL PROPOSAL
8.1 Product overview
Figure 8.1 Final rendering 1.
Figure 8.2 Final rendering 2.
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8.2 Parts, Materials, Processes
Part / Component / Feature
Description
Material / Process
Modification of SafariSeat
Minimize modification of the
original SafariSeat structure.
Little change on the workflow
and then new batches could
be produced. The old version
also could be easily modified.
Weld a steel structure
on the front beam and
cut the left half of the
rear beam to the
same length as the
right half.
Connector
The connector was designed
to minimize the modification
of the SafariSeat structure.
Steel
Cutting & welding
Underpan
Other upper structure could
be also built or fixed on the
underpan for different
purpose.
e.g. water tank, tool box,
electric generator…
Steel
Cutting & welding
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Supporting Leg
The support leg is fixed by a
pin, its height is adjustable.
It also act as a handle to lift
and connect the trailer with
the SafariSeat.
Steel
Cutting, welding,
drilling
Upper frame
For bread selling
The aluminum chequered
plates can be drawn out for
customization and cleaning.
Steel
Cutting & welding
Acrylic Sheets
Those transparent sheets are
directly glued on the upper
frame. They ensure each
layer of goods can be
displayed to passers-by.
Acrylic
glued
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Door
Users can easily open the
door with one hand or lock the
door with both hands
Steel
Cutting, welding,
drilling
Table 8.2 Parts, Materials, Processes
8.3 Design Details
8.3.1 Finite Element analysis
Theoretical
maximum load:
200kg
Theoretical
maximum torque
on connector:
1000Nm
Table 8.3.1 Extreme loads.
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8.3.2 Costing / Pricing
*The team is still looking for ways to further reduce costs.
Required Material / Parts
Unit Price
Total Price
ROUND PIPES 25mm x 1.5mm =0.1m
ksh.936/5990mm
ksh.15.6
SQUARE TUBE 25mm x 25mm x 2mm =1.2m
ksh.1398/5990mm
ksh.233
SQUARE TUBE 20mm x 20mm x 1.5mm =7.7m
ksh.920/5990mm
ksh.1183
SQUARE TUBE 12mm x 12mm x 1.5mm
ksh.200
BRIGHT MILD STEEL SHAFT 16mm =0.5unit
ksh.1618/1
ksh.809
BRIGHT MILD STEEL SHAFT 6mm=0.1m
ksh.261/1
ksh.26.1
Plastic tube bearing (PPR PN16 pipe)=0.06m
ksh.200/3650mm
ksh.3.3
Plastic handle =1
USD 0.12
ksh.13
Washals 5/8” =7
ksh.13
ksh.91
Door hinge =2
ksh.100
ksh.200
Door latch =1
ksh.200
ksh.200
Caster (in assembly) =2
ksh.2000
ksh.4000
Bicycle reflectors =1
ksh.400
ksh.400
4mm thick steel plate (metal sheet) =0.4m2
ksh.13,681/2440mm x
1220mm
ksh.1824
5mm Aluminium chequered plates =0.45m2
ksh.2500
632mm x 365mm x 2 Perspex =3
ksh.1950
ksh.5850
365mm x 365mm x 2 Perspex =1
ksh.1450
ksh.1450
CP Lock nuts 14mm x 1
ksh.30
ksh.30
A 5kg box of welding rods
ksh. 800
ksh. 800
silicon sealant (glass cement) Silicon glue
ksh.250
ksh.250
Total
ksh.20078(£132
Table 8.3.2 bill of cost.
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8.3.3 Consideration of Terrain adaptability
The T-bar design at the connection
provides sufficient terrain adaptability.
As shown by the orange dotted line,
when turning, SafariCart & SafariSeat
always remain in the same direction,
only the casters are rotating.
The T-bar design also ensures that the
trailer can move normally when the
height difference between the two
casters is within a certain range.
In this way, the trailer is suitable for
most terrain that SafariSeat can pass.
Table 8.3.3 Consideration of Terrain adaptability.
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8.3.4 Consideration of Design for Safety
Design of top handles protects the
user's head from hitting sharp corners.
Installing a bicycle reflector behind the
SafariSeat improves safety in urban
environments.
Table 8.3.4 Consideration of Design for Safety.
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8.3.5 Consideration of Failure Mode
The design of the support leg has
taken into account the failure
mode-only when the support leg is put
down and fixed with a bolt, it can act
as a handle to lift the trailer. This
prevents the disconnected trailer from
tipping over because the support legs
are not lowered.
Table 8.3.5 Consideration of Failure Mode
8.4 Final feedback from collaborators
Figure 8.4 Collaborators in the final design review meeting.
Memuna, Director at the bakery, Sierra Leone - "It's a very well thought through design. What I really like
about it is the potential it has for other applications and that you've created something that a wheelchair user
can use easily and safely. It brings more utility to the SafariSeat wheelchair which was already a fantastic
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design but can now offer real opportunities for livelihood to users. I can imagine this design on the streets in
my head. As a concept and a product it looks fantastic; to see the idea come alive like this is very
impressive, you really got the brief."
Ken, Workshop manager for SafariSeat wheelchair production, Kenya - "I'm just excited to work on it and
see how the physical prototype turns out. Obviously our next steps will be to build and test the design with
users and we may make some refinements based on optimising the manufacture and usability, but I don't
have any doubts about it at the moment."
Isabella, CEO at The Accessibility Institute, Sweden - "From your presentation the design seems very
effective - It meets the brief well and I'm looking forward to having it in production. It's a very big step in not
only having a wheelchair for mobility but in really changing the lives of these people, which is what we
ultimately care about and what's central to our philosophy."
Cara, CTO and project supervisor at The Accessibility Institute, UK - "The adaptability of the design can offer
value to SafariSeat wheelchair users and stakeholders, on multiple personal, social and economic levels.
Suitability for the SafariCart to be used and manufactured in the given context has been deeply considered
and reflected in final design decisions and details. It will be interesting now to hear feedback on the design
from SafariSeat users, once they've tested it out for themselves."
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9.0 IMPLEMENT
9.1 Actual Prototype
Figure 9.1.1 Jig system of first generation SafariSeat (Deeble, 2015).
Figure 9.1.1 Current version SafariSeat - Using a jig to accurately position frame components. (O'Sullivan, 2021).
In the two to three months after graduation, the designer will maintain close contact with the workshop
manager, make further adjustments to the design on various production details, participate in the design of
the related jig system and determine the production process of each component. Finally, a SafariCart
prototype will be produced, and it will be properly connected to a SafariSeat.
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9.2 Usability testing and ethics
Figure 9.1 Usability test of SafariSeat (O'Sullivan, 2021).
During the manufacturing of the SafariCart prototype, TAI will organize a series of usability tests near the
factory. The test site, procedures and recording methods will be consistent with the usability test of
SafariSeat. The specific test process will be consistent with the designer's design process:
The first stage is to test the usability of SafariSeat after the connector is installed, and compare this
combination with the original design.
In the second stage, after confirming that the connector has no major usability problems, connect
SafariSeat with the underpan of SafariCart to test the performance of this design on actual terrain.
In the third stage, after the prototype is completed, the entire prototype will be fully tested to
eliminate potential usability problems.
TAI will be responsible for the ethical issues of this series of usability tests.
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9.3 Production & Shipment
After the design meets all the design specifications, the first batch (less than ten) of SafariCart will be
produced in the workshop and shipped to Sierra Leone. The specific transportation method has not been
determined, but whether it is container shipping or road transportation, SafariCart will first be disassembled
into parts and loaded into creates. Design optimization for this aspect will also be considered during the
prototype testing phase.
9.4 Application
About half a year after the designer graduated, this batch of SafariSeat & SafariCart combinations will arrive
at the bakery in Sierra Leone. Two of them will be used for the initial publicity of the bakery project. After all
the facilities are complete, a group of local disabled people will be hired, and they will be responsible for
distributing the prepared bread to nearby residents.
This will be their first formal job. Through wages and micro-loan services, they will gradually pay off the cost
of wheelchairs and trailers and improve their quality of life. Through work, their social image will be improved
and their social circle will be expanded.
9.5 Other possibilities of the underpan
Figure 9.5 Modification possibility of SafariCart.
As mentioned in UIM, this project also considered the modification of SafariCart in other potential
applications and scenarios. Keeping the connector and underpan unchanged, the upper storage structure
can be redesigned in a shorter design cycle to adapt to new applications and scenarios, such as water
transportation.
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9.6 SafariCart 2
Figure 9.6.1 Top view of SafariCart.
In the design phase of SafariCart, in order to maintain the same wheel track as the original design, the T-bar
dual-degree-of-freedom solution was adopted. But this design also limits its size. The current design can
transport 12 sliced bread, but as the business develops, a larger capacity trailer may be required.
In order to meet this demand, a new generation of SafariCart may be designed. The new trailer may use
fixed wheels and be connected to the wheelchair via a tow bar. It will have a larger wheel track and ground
contact area to achieve larger load.
Figure 9.6.2 Tow Bar.
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10.0 REFLECT
10.1 Methodology
The designer adopted the design 101 model as the main design process of this project. During the design
process, this model exposed some problems:
This process derived from service design cannot match every stage to product design, especially the
empathize stage. Its vague description has caused some confusion for designers in the early stages
of design.
Although this design process describes the review route, it does not clearly indicate the output of
each stage. In the actual design process, the designer needs a lot of subjective judgment to decide
whether to enter the next stage.
But apart from the above two points, just like other design models, it has played a clear guiding role for the
entire design.
10.2 Design
This project is the designer's largest design project during the epidemic. Although it does not have
macroscopic statistical significance, this project, as a personal case, proves the feasibility of multi-person
co-creation under the influence of physical distance and time zone. In future design projects, the experience
of this project will be a great reference for the designer himself.
10.3 Tool and Resources
In this project, as the most important design tool, Autodesk Fusion 360 proved its superiority in remote
collaboration. Server storage and cloud rendering service reduce the hardware requirements for designers.
In other words, through this platform, CAD models and high-quality renderings can be produced without the
need for high-performance graphics cards and CPUs. At the same time, the model can be shared through
links and viewed on the web page, which makes the communication between the designer and the
collaborator much easier.
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10.4 Overall Conclusion
At this time, the project produced a SafariSeat wheelchair attachment that meets the client's needs and can
theoretically be produced. The design includes a connector, a customizable underpan, and a bread transport
rack on it. The designer reviewed the key points of the development and design of the project, and designed
the product from both user experience and engineering side.Through finite element analysis, full-scale
testing and other methods, the load-bearing performance and usability of the design have been theoretically
verified, but the project still needs to wait for the manufacturing and testing of the physical model, and further
optimize the production efficiency and safety before entering Mass production.
This design result has been approved by the funder. In the next few months, the designer will continue to
follow up on the project, optimize the design from the above-mentioned aspects, and remotely participate in
the prototype testing in Kenya. About half a year later, a batch of SafariSeat & SafariCart sets will be sent to
a newly built bakery in Sierra Leone, and several disabled people will get their first job. Through this
opportunity, they will improve their quality of life, expand their social circle, and live with dignity.
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11.0 REFERENCES
AtomicZombie. (2020). Water container cargo platforms. [Online] Available at
https://atomiczombie.wordpress.com/2012/02/07/cargo-bikes-in-africa/ [Accessed 30 November 2020].
Autodesk. (2020). Offitial page of fusion 360. [Online]Available at
https://www.autodesk.com.cn/products/fusion-360/features [Accessed 30 November 2020].
Banks L. M., Kuper H., Polack S., (2018). Correction: Poverty and disability in low- and middle-income
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12.0 APPENDICES
12.1 Gantt Chart
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12.2 Technical drawings
Technical drawings of some key parts of SafariCart.
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12.3 Virtual Prototype
Please click on the link below to check the virtual prototype on fusion360.
You can choose to view it on the web or open it in fusion360 after downloading: https://a360.co/2PYcPij
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Supplementary resource (1)

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Conference Paper
Full-text available
Developing appropriate assistive technology to be manufactured and maintained within the local context of a low-resource setting, requires alternative design principles and designerly ways to those used when designing in, or for, more resourced regions of the world. This case study offers an empirical account of the design of SafariSeat, an all-terrain wheelchair which has been designed, tested, manufactured and turned into a sustainable enterprise in East Africa. The wheelchair was developed with intentions to reduce inequality and help alleviate poverty in low-resource communities by improving users' health, wellbeing and participation in society, whilst creating and facilitating local jobs to support communities. Having developed SafariSeat with a human-centred design approach, a local mindset, and prioritisation of usability and affordability, this case study is used to reflect on the applied design principles, practices and processes whilst providing contextual insights for other designers seeking to work in a similar way. The study discusses challenges encountered whilst designing in a low-resource setting, and highlights how local collaboration and partnerships can help lead to the creation of a more sustainable solution.
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Introduction Disability and poverty are believed to operate in a cycle, with each reinforcing the other. While agreement on the existence of a link is strong, robust empirical evidence substantiating and describing this potential association is lacking. Consequently, a systematic review was undertaken to explore the relationship between disability and economic poverty, with a focus on the situation in low and middle income countries (LMICs). Methods Ten electronic databases were searched to retrieve studies of any epidemiological design, published between 1990-March 2016 with data comparing the level of poverty between people with and without disabilities in LMICs (World Bank classifications). Poverty was defined using economic measures (e.g. assets, income), while disability included both broad assessments (e.g. self-reported functional or activity limitations) and specific impairments/disorders. Data extracted included: measures of association between disability and poverty, population characteristics and study characteristics. Proportions of studies finding positive, negative, null or mixed associations between poverty and disability were then disaggregated by population and study characteristics. Results From the 15,500 records retrieved and screened, 150 studies were included in the final sample. Almost half of included studies were conducted in China, India or Brazil (n = 70, 47%). Most studies were cross-sectional in design (n = 124, 83%), focussed on specific impairment types (n = 115, 77%) and used income as the measure for economic poverty (n = 82, 55%). 122 studies (81%) found evidence of a positive association between disability and a poverty marker. This relationship persisted when results were disaggregated by gender, measure of poverty used and impairment types. By country income group at the time of data collection, the proportion of country-level analyses with a positive association increased with the rising income level, with 59% of low-income, 67% of lower-middle and 72% of upper-middle income countries finding a positive relationship. By age group, the proportion of studies reporting a positive association between disability and poverty was lowest for older adults and highest for working-age adults (69% vs. 86%). Conclusions There is strong evidence for a link between disability and poverty in LMICs and an urgent need for further research and programmatic/policy action to break the cycle.
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