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School of Computer Science, Engineering & Mathematics
Faculty of Science and Engineering
DESIGNING A NEW ASSISTIVE WALKER FOR CHILDREN
WITH DEVELOPMENTAL DELAY
By
Kim Sim Lee
Supervisors: Mr. David Hobbs and Miss Laura De Palma
June 2013
A thesis presented to the Flinders University of South Australia in partial fulfilment of
the requirements for the degree of Master of Engineering (Biomedical)
ACKNOWLEDGEMENTS
Thanks are extended to my dedicated Supervisors, Mr. David Hobbs, and Miss Laura De
Palma, a paediatric physiotherapist working at Xtra Care Equipment, for their guidance,
support and encouragement throughout my Masters’ project.
Special thanks are also extended to my friends and family for their unconditional support,
encouragement, and care for me throughout my Masters program.
DECLARATIONS
I certify that this work does not incorporate without acknowledgment any material
previously submitted for a degree or diploma in any university; and that to the best of my
knowledge and belief it does not contain any material previously published or written by
another person except where due reference is made in the text.
Signature: ……………………………………. Date: 25th June 2013
Kim Sim Lee
ABSTRACT
The aim of this project was to design a new walker for children with developmental delay.
An engineering design process was used to develop a solution, which began with
understanding what it means for a child to have developmental delay. A market analysis of 23
commercial ‘baby walkers’ was conducted and identified that no mainstream commercial
‘baby walker’ is suitable for children with developmental delay.
An online questionnaire was distributed to professionals working in the field to obtain their
feedback and opinions about the interest and feasibility of a new walker design, specifically
targeted at children with developmental delay. 38 responses were received. 18 of the
participants had more than ten years working experience in the field, and eleven participants
had 3-6 years work experience either in disability, developmental delay, assistive devices or
related fields. Respondents indicated that they couldn’t always provide a suitable ‘off-the-
shelf’ walker for a particular client and that further modifications were often needed.
Moreover, the top 5 desired features of a new walker as identified by the respondents were:
stability/anti-tip, manoeuvrability, variable resistance wheels, height adjustability and a
strong/durable design.
Five conceptual designs were created and critiqued. Design 5 was selected to be the new the
new walker design and a CAD drawing and model was produced. Overall, this project
conducted a thorough market analysis of current commercial options (including a patent
search), sought stakeholder and ‘expert’ feedback, and considered the mechanical design
(function and form) aspect of the design of a new walker. Further work includes Finite
Element Method (FEM) simulation, material selection, a braking mechanism, product testing,
and cost estimation should be done before the new walker can be fully developed.
1
TABLE OF CONTENTS
ABSTRACT …………………………………………………………………………………..i
ACKNOWLEDGEMENT …...…………………………………………………..………….ii
CHAPTER 1 INTRODUCTION ........................................................................................ 3
1.1 Introduction ......................................................................................................... 3
1.2 Problem statement ............................................................................................... 4
1.3 Project aim and scope .......................................................................................... 4
1.4 Project‟s approaches, methodologies and expected outcomes ............................... 4
1.5 Arrangement of report.......................................................................................... 5
CHAPTER 2 LITERATURE REVIEW ............................................................................ 7
2. 1 Introduction ......................................................................................................... 7
2. 2 Introduction to typical childhood development ..................................................... 7
2. 3 Developmental delay ......................................................................................... 11
2. 4 Mobility Walkers ............................................................................................... 12
2.4.1 Commercial “baby walkers”........................................................................... 13
2.4.2 Assistive walker or gait trainer ....................................................................... 15
2. 5 Patent search ...................................................................................................... 17
CHAPTER 3 METHODOLOGY ..................................................................................... 23
3. 1 Introduction ....................................................................................................... 23
3. 2 Identifying design requirements for a new walker for children with DD ............. 23
3. 3 Engineering design process ................................................................................ 23
3. 4 Market analysis .................................................................................................. 25
3. 5 Online questionnaire .......................................................................................... 26
CHAPTER 4 MARKET ANALYSIS AND ONLINE SURVEY ..................................... 28
4. 1 Introduction ....................................................................................................... 28
4. 2 Market analysis results ....................................................................................... 28
4. 3 Online survey results ......................................................................................... 31
2
CHAPTER 5 EARLY CONCEPTUALISATION DESIGN ........................................... 36
5. 1 Introduction ....................................................................................................... 36
5. 2 Design specifications ......................................................................................... 36
5. 3 Design sketches ................................................................................................. 36
CHAPTER 6 RESULTS AND DISCUSSION ................................................................. 46
6.1 Introduction ....................................................................................................... 46
6.2 New walker design in CAD (refer Figure 6.1) .................................................... 46
6.3 Risk analysis ...................................................................................................... 48
CHAPTER 7 FURTHER WORK AND RECOMMENDATIONS ................................. 50
CHAPTER 8 CONCLUSION ........................................................................................... 52
3
CHAPTER 1
INTRODUCTION
1.1 Introduction
This chapter defines the term „Developmental Delay‟ and explains what it means when a
child has the condition, and also identifies that there are no suitable „off-the-shelf‟ ready-
made walking aids or assistive walkers for children with developmental delay currently on
the market.
„Developmental Delay‟ is the clinical term that is used to describe when a child is delayed in
reaching their milestones compared to other children of similar age. Children with
developmental delay may suffer difficulties producing controlled speech, difficulty
controlling breathing and phonation, lacking hand-to-eye coordination, uncoordinated
physical movement, awkward postures and running style, and they also require more time
and extra effort to learn a new skill like to walk or to talk. (Kid Sense Child Development
Corporation Pty Ltd., 2013) In this project, the focus is on Gross Motor (Physical) milestone
particularly standing and walking.
Developmental Delay can be classified as two types: either transient (temporary) or persistent
(permanent). (Raising Children Network (Australia) Limited, 2013) Transient Delay is often
seen in those children who were extremely premature, children that have experienced
prolonged hospital stays due to illness, or children who somehow do not have the opportunity
to learn. Transient Delay means that with the appropriate assistance, the child may be able to
achieve skills according to the physical or intellectual milestones of their age and after that
continue to progress at a normal rate. On the other hand, Persistent Delay may be an
indication of a more disability, such as cerebral palsy or autism. Therefore, this population
would benefit more so than a typically developing child, from an early walking aid that meets
their unique needs in terms of sturdiness, stability, and adjustability, to assist with
independent standing and early walking. However, a suitable commercial option does not
exist.
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Currently, there is no statistical or relevant data available on children with gross motor skills
developmental delay in the age range from 9 months to 2 years because measurement
methodologies are widely debated around the world due to variances in diagnostics and the
many causal health factors that can contribute to developmental delay as a broad term.
1.2 Problem statement
The problem is that current commercial „baby walkers‟ are not suitable for children with
developmental delay. This is because they may not have the unique features that are essential
to cater for children with developmental delay. For example, a multi rung ladder would allow
the child to grab on and pull themselves up from a sitting to standing position. Therefore,
parents of children with developmental delay are unable to purchase ready-made „baby
walkers‟ for their child, because their child may be at high risk of falling down and injuring
themselves because most commercial „baby walkers‟ do not have any assistive ability for
helping children that have delayed gross motor skills.
1.3 Project aim and scope
This project aims to design a novel assistive walker for children with developmental delay
aged between 9 months and 2 years old that would assist these children to be able to achieve
their gross motor (physical) milestones, in particular, standing and walking. Although this
project will be focusing on the needs for children with developmental delay, the outcomes of
the overall design could also lead to benefits for typically developing children who are taller
or heavier than the average toddler.
1.4 Project’s approaches, methodologies and expected outcomes
The supply of an assistive walker for children with developmental delay would significantly
help to achieve their gross motor milestones by providing a stable, height adjustable and a
supportive rung ladder that will improve the child‟s independence, safety and self-confidence.
This project seeks to overcome the difficulty faced by either the parents or physiotherapists to
purchase or prescribe „off-the-shelf‟ assistive walker by identifying the key features of the
needs of children with developmental delay and incorporating them into the new walker
design.
5
The design carried out to achieve this objective involved:
A thorough research on the behaviour and presentation of children with
developmental delay which describe the features, the challenges experienced, and the
intervention of helping and improving the difficulties. Moreover, a review of walking
aids or assistive walkers for children and design patents in this space were researched.
(Chapter 2);
An online questionnaire targeted at professionals working in field (that is,
developmental delay) or related fields (e.g. paediatric physiotherapy) to obtain expert
feedback and their opinion on the market need for, and the most appropriate design of,
an assistive walker for children with developmental delay. Moreover, market research
was also conducted on commercial „baby walkers‟ on the market by assessing the
features, specifications and manufacturer claims. In addition, conceptual designs were
created by referring to the design requirements. (Chapter 3)
The new walker design was produced and drawn in using Autodesk Inventor, a
Computer Aided Drawing (CAD) package. (Chapter 4)
This project is the initial stage of a potentially long-term collaboration between Flinders
University and Miss Laura De Palma (a paediatric physiotherapist and the Industry
Supervisor for this project) who works at Xtra Care Equipment to design and develop a novel
assistive walker for children with developmental delay. Moreover, the project also has the
prospect of generating a commercial outcome, leading to a new product on the market.
1.5 Arrangement of report
This project is divided into seven chapters. In the first chapter, the introduction of the title
was discussed, including the problem statement of the project and the aim of the study. Lastly,
the overall context of the project was discussed in this chapter.
The next chapter consists of a detailed literature review of the condition developmental delay,
and the current assistive walker designs that are currently available on the market. The
chapter begins with the introduction of typical developmental milestones for young children.
Then, the term „Developmental Delay‟, the features and challenges faced by children with
developmental delay are thoroughly discussed. This chapter continues with a brief description
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of the general approach in conducting an engineering design project. Furthermore, previous
design patterns for assistive walkers are discussed and critiqued.
The third chapter describes the methodology used in conducting this project from the initial
stage until the project is completed. The general engineering design methodology is
explained. Moreover, the requirements of a market assessment on commercial „baby walkers‟
on the market, in order to verify the need of a new walker design for children with
developmental delay is described. Finally, the online survey questionnaire design is discussed.
Chapter 4 begins with conducting a market assessment on commercial „baby walkers‟,
followed by the specific design requirements for such a design. Furthermore, online survey
was conducted and distributed to professionals working in the field or related field to seek
feedback and opinion on the feasibility and importance of each requirement for an assistive
walker for children with developmental delay.
Chapter 5 describes a number of conceptual designs by referring to the design specifications
produced and the advantages and disadvantages of each conceptual design were explained.
The next chapter introduces the design of the new walker, after assessing the conceptual
designs and the outcome of the online questionnaire. Furthermore, Computer Aided Design
(CAD) drawings were produced using Autodesk Inventor software, which shows the overall
design in 3-dimension (3D).
The final chapter is the discussion, conclusions and the future recommendations. Then, the
chapter concludes with a project summary, project findings and further recommendations to
further improve the walker design in the future.
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CHAPTER 2
LITERATURE REVIEW
2. 1 Introduction
This chapter states the literature review for developmental delay and the appropriate design
requirements to be incorporated in the new walker design. It begins with the introduction of
the typical physical developmental milestones of a typically developing child. Then, detailed
research into developmental delay, traditional and assistive walkers, and previous design
patents for assistive walkers and commercial „baby walkers‟ are discussed.
2. 2 Introduction to typical childhood development
Development is a process that each individual goes through throughout their whole life. For
example, motor skills, communications skills and social skills. Outcomes of the development
result in how much a person can perform a given task. Chambers and Sugdent (2006) stated
that age and growth development does not necessary occur in a linear manner. Plateaus and
step changes when comparing age and growth development are also a normal phenomenon.
However, this project is focussing on motor development in young children, in particular
with respect to standing and walking.
Development of a young child from birth to primary school years varies for each child but
they do experience a number of core movements, some reflexive and others more voluntary,
which some of these skills are the fundamental movements that we could observe during the
developing young child‟s first six or seven years of life. For children just after birth, they
would have to dependent on a carer or their parents to change from any position in which
they are placed, but by approximately 24 months of age, they would be expected to be able to
make some other postural adjustments, walk and able to handle many objects. (Chambers
and Sugdent, 2006)
Moreover, young child would have natural reflexes prior to a walking action, for example
sucking, palmar grasp, asymmetrical tonic neck, babinski and walking. Walking reflex would
be stimulated by holding the child upright and place the baby on a flat surface. However
these reflexes normally disappear between 3-6 months old. (See Table 2.1)
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Table 2. 1 : Selected reflexes in young infants
Reflex Stimulus Description Appearance Disappearance
Sucking Touching lips Sucking motion Prenatal 3-4 months
Palmar grasp Touch palm Flexion on object Prenatal 4-6 months
Asymmetrical
tonic neck
Turn head to one
side
Same-side arm
and leg extend Prenatal 4-6 months
Babinski Stoke sole Toes extend Birth 4 months
Walking
Hold upright and
place infant on
flat surface
Walking pattern
in legs Birth 4-5 months
Source: Chambers and Sugden (2006)
Although the reflexes listed in Table 2.1 would be normally followed by babies trying to
walk independently. Chambers and Sugden (2006) described the studies done by McGraw in
1964 that the initial reflexes and the locomotion developmental for young children are not
related, and that reflexive stepping would obstruct with voluntary movement and so inhibited
before the child could proceed to voluntary walk.
There are 2 infant scales available that chronicle the movement behaviours of young infants.
One of them is known as Bayley Scales of Infant Developmental which is described in the
studies of Bayley in 1969b and the Denver Developmental Screening Test which is explained
by Frankenburg and Dodds in 1967. Results from both of the infant scales enabled Keogh and
Sugden (1985) to produce the development of postural control, locomotion and manual
control respectively. (See Figure 2.1 and 2.2) Figure 2.1 shows both data collected using
Bayley Scales of Infant Developmental and also Denver Developmental Screening Test.
9
Figure 2.1 : Development of locomotion. Source: Keogh and Sugden (1985)
In figure 2.2 illustrates the development of locomotion of a child from birth to 24 months old.
For the first 6 months of life, the child generally doesn‟t move much. They can move their
hands and legs which can move their bodies a little along the ground or to change direction
and later to roll over. The, babies would try to bring their knees up under the body by flexing
them, followed by extension giving change in direction but often remain in prone position.
Then, the child would start to change positions, which normally begins with rolling over from
supine to prone position and also vice versa. This continues until the child starts to move
forward in the prone position by crawling or creeping. It shouldn‟t be anything wrong with
impaired development in functions like visual, cognitive or further motor skills, when the
child does not crawl or creep. (Chambers and Sugden, 2006)
10
Figure 2.2 : Development of locomotion. Source: Keogh and Sugden (1985)
Early walkers that are able to walk independently without any assistance start walking from 9
months old, while others can be as late as 17 months old. As long as the babies obtain the
skill of standing up and start walking independently, they tend to also modify it in different
ways, for example by walking sideways and backwards, stopping and changing directions,
and by multitasking while walking. (Chambers and Sugden, 2006)
According to the growth chart produced by the World Health Organisation (WHO) (refer to
Appendix A and B), that the maximum length (97th percentile) of 9 month old girls is 74.9cm,
while the minimum length (3rd
percentile) is 65.9cm. While for girls aged of 2 years old, the
3rd
percentile showed the height of 80.3cm and 97th
percentile displayed 92.5cm. On the other
hand, for growth of boys between 9 months to 2 years, the length of 9 months old showed
minimum length of 68cm and maximum of 76.5cm. Moreover, 2 years old boys displayed
length ranges from 92cm to 93.5cm of length.
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2. 3 Developmental delay
Developmental Delay is a term used by professionals to refer to young children that are
slower to reach milestones compared to other “typically developing” children. Children with
developmental delay tend to take longer to learn new skills, such as walking or talking.
Developmental Delay can affect physically or cognitively. Children that have physical
developmental delay would display poor balance that sometimes may lead them to trip over
while walking and having difficulty picking up objects due to poor muscle tone. Whereas
children that have cognitive developmental delay would have the features of difficulty
producing controlled speech, slow language development and problem with spatial awareness.
(Government of South Australia, 2011)
Developmental delay can be classed as transient (temporary) or persistent (permanent)
depending on the cause. Persistent developmental delays are also called „developmental
disabilities‟. If the serious condition of developmental disabilities continues, it can lead to a
diagnosis of cerebral palsy or autism. (Raising Children Network, 2013) On the other hand,
transient delay is often discovered in young children that lack opportunities to learn because
of prolonged hospital stays due to illness, or those that were extremely premature. On the
positive side, transient developmental delay means that the children will be able to achieve
skills to an age appropriate level with assistance and then continue to progress at a normal
rate.
According to the South Australia Government (2011), global developmental delay means a
delay of the order of 25% in the majority of areas of development. For example, fine and
gross motor development, communication, socio-emotional development, cognitive
development and self-care. People with global developmental delay described some of the
challenges experienced, such as lack of hand-to-eye coordination, which could cause issues in
basic skills like throwing and catching, uncoordinated physical movements, awkward
postures and running styles, and also a failure to respond quickly to their surroundings.
Children with gross motor skills developmental delay seem to resemble Developmental
Coordination Disorder (DCD). In the study by Dewey and Wilson (2001) DCD was often
being labelled as minimal cerebral palsy, minimal brain dysfunction, clumsy child syndrome,
12
developmental dyspraxia, sensory integrative and mild motor problems in the recent editions
of the influential diagnostic manuals, Diagnostic and Statistical Manual of Mental Disorders
IV (DSM-IV), published by the American Psychiatric Association (APA) and the World
Health Organization (WHO) respectively. (Dewey and Wilson, 2001) One of the main
criteria for DSM-IV classification of DCD by APA in 1994 is the person‟s performance in
daily activities that need motor coordination is significantly below expectation given the
person‟s chronological age and measure of intelligence. The person may show marked delays
in achieving certain motor milestones like crawling, sitting and walking, dropping things,
„clumsiness‟, poor performance in sports, or poor handwriting.
2. 4 Mobility Walkers
Walkers started appearing in the early 1950s and the first US patent was awarded in 1953 a
William Cribbes Robb of Stretford, England, for a device called “walking aid” (Robb, 1953).
After that another 2 walker designs with wheels were awarded US patents in May 1957. The
first non-wheeled design that was called a “walker” was patented in 1965 by Elmer F. Ries of
Cincinnati, Ohio. (Ries, 1965) One of the more previous designs that resembles the modern
walkers in known as “Invalid Walker” which was patented in 1970 by Alfred A. Smith of
Van Nuys, California. (Smith, 1969)
Walkers were designed as support tools with a frame surrounding their front and sides and
also providing additional support by holding on top of the side frames. Previously, the
walkers were designed without wheels and the user has to pick up and place it a short
distance ahead of themselves. Then the user walks to it and repeat the process. Then, with the
incorporation of glides and wheels, the user no longer needed more effort to lift up the walker,
which is an advantage point for people with little arm strength. (Cooper Medical Supplies
Ltd., n.d.)
Normally, a walker would be prescribed or given to those people that are undergoing
recuperation from leg of back injuries. It is also a good tool for the person having gait issues
or with mild balance problems.
13
2.4.1 Commercial “baby walkers”
The so-called baby walkers were known as early as the 1440s in Europe where a Dutch
manuscript from that time illustrated the infant Jesus in a wooden baby walker (Lamar C,
2012). A baby walker is a device that were intentionally design for young children aged
between 4 – 16 months old that are still unable to walk independently without support, to
move from one place to another. Modern baby walkers generally have a base made of hard
plastic sitting on top of wheels and a suspended fabric seat with 2 leg holes. Moreover, a
baby walker usually has toys or equivalent to entertain the baby in the walker.
Figure 2.1 : Illumination of Jesus in baby walker (Cyriaque, 1440)
There is a common belief by parents that baby walker would help to speed up the walking
ability of their children. However, studies have shown that using baby walkers can actually
delay walking by two to three weeks. The type of baby walkers that have been condemned
are those that suspend the baby and require the baby to sit inside the walker with theie legs in
a crouch position when they touch the floor (refer Figure 2.3). This does not encourage
independent standing. An article from ABC Science (2002), explained current research that
each aggregated 24 hours of baby walker use was associated with a delay of 3.3 days in
walking alone and a delay of 3.7 day in standing alone. The walker that is being designed for
this project will not suspend the child when they use it- it will encourage independent
standing and walking.
14
Moreover, baby walkers may also lead to many injuries. The American Academy of
Paediatrics, U.S. Consumer Product Safety Commission (CPSC) and some other major
organisations have issued warnings to discourage parents from using baby walkers. The sale
of baby walkers, importation and also advertisement regarding baby walkers have been
banned in Canada since 7th
April 2004 which is the first country in the world to undergo this
baby walker prohibition.
Figure 2.2 : An example of baby walker that is banned in Canada
However, there are still many commercial baby walkers available on the market and the
market size for them is still very large worldwide despite all the safety issues. Therefore, in
order to ensure child safety, the Australian Competition & Consumer Commission (ACCC)
made it mandatory for all the baby walkers in Australia to meet the requirements of ASTM
F977-12 „Standard Consumer Safety Specification for Infant Walkers‟. In ASTM F977-12
listed that baby walkers must have a braking mechanism to stop the walker from falling down
steps and stairs. Moreover, baby walkers must comply with performance requirements that
are specified in clauses 6.1 and 6.3 of ASTM F977-12 which include tipping resistance and
providing a braking mechanism. In addition, it is mandatory to display warning labels to alert
the parents not to leave the child with the baby walker unattended and also alert them about
stair hazards as stated in the clause 8.2 of ASTM F977-12 (ACCC, 2005).
One of the commercial baby walkers manufactured by one of the world‟s leading
manufacturer of baby equipment and preschool toys is Fisher-Price. Fisher-Price was founded
by Herman Fisher, Irving Price and Helen Schelle in 1930. They produce various baby
walkers for example, the Fisher-Price Brilliant Basics Stroll Along Walker. (see figure 2.3).
This walker claims to be a sturdy stroller with a wide base and easy-grasp handle to support
15
the child‟s first steps. An additional feature is the stroller styling, aimed that encouraging
early role play and nurturing. Moreover, it also has musical output when a button is pressed.
Fisher-Price also produce other baby walkers such as, Go Baby Go!™, Stride-to-Ride™ Dino,
Scoop & Whirl Popper and Brilliant Basics™ Musical Activity Walker™. There are also
other baby walker manufacturers such as Chicco, Mothercare, Vtech, Love N Care and Micki.
Figure 2.3 : An example of Fisher-Price Brilliant Basics Stroll Along Walker (Model:
M9523) Source: Mattel Fisher-price (2012)
2.4.2 Assistive walker or gait trainer
Assistive walkers, such as rollators, are aimed at helping people with mobility or balance
issue to get around safely. A rollator is a wheeled walker which was invented by Swede Aina
Wifalk in 1978 who suffered from polio herself. Initially it was branded as a „rollator‟ but it
was then trademarked and used for wheeled walkers in many countries. The construction of
the rollator consists of a frame with three or four large wheels, handlebars and a built-in seat,
which would allow the user to stop and rest when required. It is also normally equipped with
a shopping basket. They differ from traditional simple walkers by being more complicated
and built-up with features like height adjustability, hand-braking mechanism, and being light-
weight. (See figure 2.4 (a))
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(a) (b)
Figure 2.4 : An example of a rollater (a) and a traditional walker (b)
The difference between a walker and a rollator is normally walkers have four legs where all
four legs touch the ground providing stability and partial weight bearing while rollators have
three or four wheels and a braking mechanism. In addition, the user has to lift up the walker
before stepping forward and then put it down again with each step. Rollators does not require
to be lift up to move forwards and also benefits users that have weak arm strength due to
minimal effort is needed to push the rollator. However, rollators are only suitable for people
where minimal walking support is required because stability for a rollator is less than the
traditional 4 legged walkers with no wheels. (Refer to figure 2.4) (Cooper Medical, n.d.)
A gait trainer is a wheeled device aimed to assist either adults or children who are unable to
walk independently due to weak gross motor ability caused by physical developmental delay
or motor disability. It would provide the opportunity to improve walking ability by offering
unweighting support and postural alignment to enable gait practice. Compared to the
traditional rollator walker, or other walkers, gait trainers generally offer more assistance for
balance and weight-bearing in a safe, supported position. (See figure 2.5)
Gait trainers are often used during a physical therapy session for gait rehabilitation. Recent
gait trainers are able to be used over a treadmill with improved development of body-weight
support (BWS) systems. Body-weight support systems allow users to walk safely and with
17
less effort that could increase training duration due to reduced therapist‟s strain to care for the
patient. When gait training increases, the potential of gaining motor skills would also increase,
which leads to high opportunity to regain walking ability. (Hesse et.al, 1995)
The idea of developing gait trainers for children also known as paediatric gait trainers, first
appeared in the mid 1980‟s by a special education teacher in California called Linda Bidabe
in collaboration with others at the Blair Learning Center. (Thompson, 2011) Since then,
paediatric gait trainer design has improved over time and many manufacturers have
developed quality gait trainers such as Rifton, R82, Kaye Products Inc., Mulholland
Positioning Systems Inc. and Prime Engineering.
(a) (b)
Figure 2.5 : Rifton pacer gait trainer (K509) paediatric gait trainer (a) and
Wenzelite Gaint Trainers for adult (b)
2. 5 Patent search
In a design project, it is important to prevent any infringement on other designs, so a patent
search was conducted.
18
US 4251105 (1981) – Mobility aid (refer figure 3.1)
This patent described a mobility aid that can assist the disabled and/or infirm to move with a
walking action. It has a four-legged tubular metal frame and it is shaped like the letter „U‟
from above. The opening at the rear of the walker is to allow easy access and standing within
the frame. Before this design had been proposed, most of the walker frame does not have
wheels and the user would have to lift the frame and move it. This can cause exhaustion for
the users when they need to walk a distance. Therefore, this patent design proposed the front
legs of the frame to have wheels for easy movement, but these wheels must also be equipped
with some sort of braking system to prevent movement of the frame upon application of an
appropriate download force to the frame.
This patent also stated that the braking control system they proposed was different than the
conventional braking system that used the principle when a weight is applied to the frame the
wheels move upwardly relative to lugs on the frame legs, engaging these lugs so as to brake
against rotation. For this design, when the frame is pressed down by the user, the wheels are
caused to rotate, causing forward movement with the rear legs dragging as a result. Even
when stumbling arises and uneven loading is applied to the frame, this causes the rear legs to
be raised clear of the ground, there will be no tilting of the frame because the front legs have
stabiliser struts projecting forwardly and downwardly to engage the ground ahead of the
wheel to prevent toppling over.
The similarity of this patent to the new walker design requirements is the anti-tipping and the
braking system. It has a simple and effective anti-toppling system and this patent is designed
to cater for the severely disabled or infirm users that has limited motor coordination and
strength. However, the disadvantage of this patent design is it is not collapsible. (Baker, 1981)
19
Figure 3.1 : Embodiment of US 4251105 Source: US 4251105 (1981)
US 4799700 (1989)-Collapsible walker (refer to Figure 3.2)
This patent describes a collapsible baby walker that is equipped with a base, seat for carrying
load and a frame that connects the base and the seat. It had 2 height options that could be
chosen. The braking system for this design is a pair of eccentrically mounted pivot arms for
lowering the base to a braking position upon movement of a support wheel on one of the
pivot arms over an edge of an underlying surface. Patent US 4799700 also includes rollers
under the base. This design can be folded for storage and when folded, it has a control system
for safety during the process of folding to prevent any accidental or inadvertent folding of the
walker to a fully collapsed storage position.
The features that are similar to the new walker design requirement are it is collapsible and it
has the control system for safety while folding the walker. However, the disadvantage of this
walker is it may need assistance or help from parents or carers getting in and out of the
walker. Therefore, the child cannot independently use the walker if they want to.
20
Figure 3.2 : Embodiment of patent US4799700 (US4799700, 1989)
US 4773639 (1988) - Infant walker (refer to Figure 3.3)
This patent describes a walker design that is used for the training of infants learning to walk.
This patent emphasises a safe walker resulting in a large rectangular base configuration
connected to the upper second smaller ring that confines the torso of the infant. The
connector from the base to the upper smaller ring is an adjustable strut.
This patent criticised that wheeled baby walkers are dangerous and unsuitable because infants
not only can move very fast by pushing against the ground rather than walking, and gave an
example that infants can propel the device towards a stairway before anyone could stop them.
Some wheeled baby walkers also allow infants to sit and discourages the infant from moving
about by walking, where they could merely push against the ground with their foot to propel
themselves about the house.
This patent design provides an improved training device for infants that allow the child to sit
and also encourages them to walk. The device consists of a pair of spaced apart rings
including a lower ring which is large and an upper ring which is smaller. The connector struts
are aligned inwardly connecting the upper and the lower rings. The upper ring is smaller in
diameter so that it can be easily gripped by infants or children. This design arrangement can
also prevent accidental tipping.
21
The similarity of this patent design and the new walker design requirements is stability where
it does not have wheels that could propel.
The disadvantages noticed with this patent design are that size of the device is quite big and it
needs a big space to allow infants to walk around. Moreover, it is not collapsible, possibly
posing a storage problem.
Figure 3.3 : Embodiment of US 4773639 Source: US 477639 (1988)
US 5152730 (1991) – Handless walking aid for preventing falls from loss of balance
(refer to Figure 3.4)
This patent design relates to therapeutic walking aids for helping people to walk alone
without support from a companion or therapist and also eliminating the fear of losing balance
and falling by elderly, injured or disabled walkers. It also described people that do not have
full normal walking capacity, balance can be a critical issue and injuries or accidents may be
more likely to happen.
This patent design consists of a rolling framework for moving along a floor surface with the
walker that does not require the use of the hands to push the framework. Therefore, the
walker can still use a cane or crutch to maintain balance. According to the patent design, the
framework is strong enough to sustain the weight of the walker when the walker loses their
22
balance and therefore able to prevent a fall. A detachable harness is also available for weight
support to the framework.
Similarities of this patent design to the new walker design requirements are that it aims to
encourage the walker to walk independently without the assistance of carer‟s support.
However, this design did not say anything about the braking control system and it is not
collapsible.
Figure 3.4 : Embodiment of US 5152730 Source: Hoffman (1991)
23
CHAPTER 3
METHODOLOGY
3. 1 Introduction
This chapter discusses the design approach for this project. It starts with understanding the
condition known as developmental delay then, reviews current assistive walkers. It continues
with explaining the market research conducted on some of the current baby walkers available
in the market and distribution of an online questionnaire is discussed. The project is followed
by a description of conceptual designs and CAD drawings.
3. 2 Identifying design requirements for a new walker for children with DD
Children with DD have weak gross motors function and experience difficulties walking
independently. Children with DD that have weak gross motor function would benefit from
using a walking aid that provides stability, is portable, light-weight, has gait training ability,
is affordable, and is also safe to use.
3. 3 Engineering design process
From an engineering design point of view, the design process starts with understanding the
needs and market analysis, followed by stating the design requirements and functions needed
for the design. Specifications describe features in more detail, setting a metric and a value for
each requirement. (Refer to figure 2.6) (Haik & Shahin, 2011)
Conceptualisation is the next step in the process, which is about creating new ideas that
would fulfil the design requirements and functions. After that, evaluation of each concept or
idea is done by typically using a decision matrix or other evaluation method like a survey.
The concepts are then put into engineering drawings to simulate the product and conduct
further analysis, like Finite Element Analysis (FEA) modelling. From the engineering
drawing, the number of parts or any potential complications for manufacturing can be
identified, and further amendments can be made before proceeding to make the actual
prototype. (Haik & Shahin, 2011)
24
In the current technology, rapid prototyping can be done using the Computer Aided Design
(CAD) drawings via 3D-printing. After prototyping the design, material selection, cost
analysis and testing have to be done before starting the actual manufacturing process.
Figure 2.6 : Design process source: Haik & Shahin (2011)
Stability
Stability is important for this new walker design because children with DD would put a lot of
weight on the walker especially on the handles in order to stand or walk independently.
25
According to the growth chart produced by the WHO, the maximum weight of a child aged 2
years is less than 16kg. Therefore, applying a safety factor of 1.5 implies new design needs to
withstand a 24kg load on the handles without failing. (Appendix C & D)
Multi-rung ladder
A rung ladder is a rod or bar that forms a step of a ladder. A multi-rung ladder is essential in
the new walker design to enable the child to pull themselves up from sitting to standing
position independently. This allows the child to be more independent and also reduces the
need for parents to bend and manually help the child to stand up.
Height adjustability
The feature of height adjustability is to cater for the height variability of children aged from 9
months to 2 years, which, according to the growth chart produced by the WHO, ranges
between 65.9cm to 93.5cm. Hence, the walker should include height adjustability to provide
room for growth.
Variable Resistance Wheels
This feature is to prevent the walker from running off unintentionally. It is essential for the
safety of the child with development delay to prevent unnecessary injury and also provide
strengthening therapy for the child.
Portability
Portability for the new walker means that it should be lightweight and foldable or collapsible
for easy storage and carrying around.
3. 4 Market analysis
Market research was conducted on 23 current commercial „baby walkers‟ by comparing the
features they offered to the requirements of a walker for developmental delay conditions. The
market research began with identifying the major brands and models of commercial „baby
walkers‟. Each „baby walkers‟ included in the market research consist of the features closest
to the requirements identified for the new walker for children with developmental delay.
26
In the comparison table, the most left column is listed with the „baby walkers‟ and the top
horizontal row list attributes such as the presence of a rung ladder, non-slip wheels, variable
resistance wheels and multi-axial wheels. Moreover, features such as height adjustable,
foldable/collapsible, lightweight (less than 6kg) and anti-tipping were included. The price
(<$1500) and age range (9 months to 2 years) are also included in the walker assessment.
Then, a letter „Y‟ is placed if the „baby walker‟ meets the requirements listed otherwise a
letter „N‟ appears. However, if the information is unavailable the dash symbol „-„ is used in
the table.
The outcome of the market analysis is to confirm that there is no „off-the-shelf‟ commercial
„baby walker‟ that meets all the features listed in the table.
3. 5 Online questionnaire
An online questionnaire were developed and targeted at to professionals working in the field
or related field. The purpose of the questionnaire was to seek professional feedback and
opinion on the market need for and the most appropriate design of an assistive walker for
children with developmental delay.
The questionnaires included 10 questions, and started by asking basic information of the
participant (such as their job title, years of working experience and how often they work
professionally with children with developmental delay). The questionnaire also included
questions to obtain feedback on the ability to prescribe an „off-the-shelf‟ walker for children
with developmental delay and also ask participants to provide walker models and information
on what they usually prescribe to clients with DD. In addition, participants were asked to rate
the importance of the most desirable features of an ideal walker, such as a study design, being
lightweight and having height adjustability. The final question in the questionnaire asked the
participant to select the price range they thought would be appropriate for the new assistive
walker. (See Appendix E)
27
The online questionnaire was approved by the Social and Behavioural Research Ethics
Committee (SBREC) of Flinders University before it was distributed to the members of
Australian Rehabilitation Assistive Technology Association (ARATA) via their membership
email Listserver, and also to professionals working in the field.
The results of the online questionnaire helped to prioritize the design features included in the
new walker design. It also gave an idea of the problems arising from real situations and gave
a professional view on the design of a new walker for children with developmental delay.
28
CHAPTER 4
MARKET ANALYSIS & ONLINE SURVEY RESULTS
4. 1 Introduction
This chapter discusses the market analysis and the online survey results.
4. 2 Market analysis results
A market analysis was conducted on 23 current commercial „baby walkers‟ and is
summarised in. The market assessment showed that there are no commercial „baby walkers‟
that were reviewed that met all the design requirements. Most of the „baby walkers‟ were able
to meet the age range of 9 months – 2 years, lightweight and price less than $1500. (See
Table 4.1)
The „W12‟ Walker wagon has variable resistance wheels, an anti-tipping feature, was suitable
for age range 9 months – 2 years, and the price is less than $1500. The „W13‟ Classic walker
wagon also has variable resistance wheels and claims to have non-slip wheels that could
prevent freewheeling and also a price under $1500. However, it weighs more than 6kg and
claims not to be for children aged between 9 months and 2 years old. The „W17‟ Giraffe
Walker „N Shape Sorter also has variable resistance wheels and is lightweight, but only
suitable for children from 12 months and above.
In summary, all „baby walkers‟ listed in the table meets the requirements of 9 months –
2years, lightweight, and priced under $1500 except W11, W13, W14, W15, W16, W17, W18,
and W22, which claim to cater different age ranges. Whereas 8 of the „baby walkers‟ that do
not met the lightweight feature are W12, W13, W14,W19, W20, W21, W22, W23. Moreover,
only W12 and W18 claim to have an anti-tipping feature. None of the „baby walkers‟ have
rung ladder support, are height adjustable feature or have multi-axial wheels. The summary
table (see Table 4.1) showed only W13 that claims to have non-slip wheels. The 3 „baby
walkers‟ that have variable resistance wheels are W12, W13 and W17. Lastly, all the „baby
walkers‟ are priced under $1500 except for W15, W16,W17, W18 and W19, for which the
price was unavailable at the time of the analysis.
29
Table 4.1. : Summary table of the baby walkers compared to the design features
30
31
4. 3 Online survey results
During a 5 week period, 38 people participated in the online survey. From the 38
respondents, 23 identified as currently working as a Physiotherapist, 5 as a Senior
Physiotherapist, 5 as in Occupational Therapist, 2 as in Senior Paediatric Physiotherapist, one
as a A/Senior physiotherapist, one as a Community Physiotherapist within a health
department, and a Clinical Lead Physiotherapist. (Refer Table 4.2)
Table 4.2. : Respondent‟s job title
Title Responses
Physiotherapist 23
Senior Physiotherapist 5
A/Senior Physiotherapist 1
Occupational Therapist 5
Community Physiotherapist with health dept 1
Clinical Lead Physiotherapist 1
Senior Paediatric Physiotherapist 2
Total: 38
Moreover, out of the 38 respondents 18 had more than 10 years working in either disability,
developmental delay, assistive devices or related fields. Eleven responded having 3-6 years,
five with less than 3 years, and four with 6-10 working experience. (Refer to Table 4.3) All
the participants responded they have worked professionally with children with developmental
delay. 25 answered the frequency of working with children with developmental delay with
daily, nine replied weekly, two monthly and two answered occasionally. (Refer to Table 4.4)
Table 4.3. : Work experience of the respondents
Work Experience Responses
Less than 3 years 5
3-6 years 11
6-10 years 4
More than 10 years 18
Total: 38
32
Table 4.4. : Frequency working with children with developmental delay
Frequency Responses
Daily 25
Weekly 9
Monthly 2
Occasionally 2
Never (N/A) 0
Total: 38
Question 5 asked whether a safe, new assistive walker that is designed specifically for
children with developmental delay be beneficial to the participants, and 23 answered „Yes‟, 1
answered „No‟, and 14 replied „I‟m not sure‟.
Respondents that answered „Yes‟ in Question 5 provided feedback that the new walker would
be beneficial if it offered different support compared to the existing walkers on market.
Furthermore, one replied that it is important to have a walker that is reasonably priced,
adjustable and maintains the child in a normal posture for walking. Lots of walkers that are
available may allow the child to "walk" but the walking is often done from a semi seated
position and in no way resembles normal alignment for walking. One also responded that the
walker may not benefits all children with developmental delay, because it must depend on the
walker design, parents‟ financial ability, home situation, anticipated use, and the child‟s
motivation, cognition and physical abilities.
Question 6 required participants to answer whether they have ever recommended, prescribed
or provided a walker for children with developmental delay. 31 responded „Yes‟ and seven
answered „No‟.
Question 7 is the continuation from Question 6 (only answered if „Yes‟ is answered for
Question 6). This question asked whether the participants were able to provide an appropriate
„off-the-shelf‟ solution for their client, or if they provided a custom-made solution. Other
33
than the seven participants that answered „No‟ in Question 6, one provided the feedback that
it was difficult to recall the details.
Feedback for question 7 included that the participants have difficulties providing a walker
due to the fact that the child is smaller than the smallest available walkers. Moreover, most of
the responses stated that modifications on the off-the-shelf walkers are needed, like creating
more space for feet to step through when using a TAD block trolley, to suit the child‟s needs.
Question 8 asked participants to provide the list of off-the-shelf walker(s) that they had
provided to their clients with developmental delay if they found a solution. Although there
were a few respondents who didn‟t answer this question, others listed various „off-the-shelf‟
walkers they usually work with. The most popular walkers listed were: Kaye walker, Rifton
Pacer Gait Trainer, Crocodile walker (R28), Mulholland Walkabout Gait Trainer, Meyland
Smith Meywalk and Prime Engineering Kidwalk.
Question 9 asked the participants to rate the importance of the features to be incorporated in
the new walker design. (See Table 4.5) The top 5 features that were selected to be most
important were: stability/anti-tip, manoeuvrability, variable resistance wheels, height
adjustability and a strong/durable design.
Lastly, question 10 asked the participant to select the appropriate price range for the new
walker design. 14 responded that the new walker should be priced between $100 -$500,
twelve selected the price range of $501-$1000, while seven selected price range of $1001-
$1500 and four thought that a price over $1500 is acceptable for the new walker. One
participant skipped this question without giving any reason. (See Table 4.6)
34
Table 4.5. : Results of the design requirements selected by the participants.
Design Requirement/
Feature
Most
Important
Quite
Important
Less
Important
Not
Important Points
(N *w) Rank
Weight (w) (4) (3) (2) (1)
Stable/ Anti-tipping
design 32 6 0 0 146 1
Manoeuvrable 29 9 0 0 143 2
Variable resistance
wheels (to prevent
the walker from
racing away)
19 19 0 0 133 3
A height adjustable
handle 22 12 4 0 132 4
Sturdy design
(strong /durable) 15 22 1 0 128 5
Affordable 17 17 4 0 127 6
Compact/ foldable 11 21 6 0 119 7
Lightweight 6 28 4 0 116 8
Easy to clean 6 19 13 0 107 9
Trendy
design/aesthetically
pleasing
5 19 14 0 105 10
A supporting ladder
for the child to pull
themselves up to a
standing position
3 13 21 1 93 11
Colourful 3 17 14 4 91 12
35
Table 4.6. : Summarised price range selected by the participants
Price range Responses
Less than $100 0
$100 - $500 14
$501-$1000 12
$1000-$1500 7
More than $1500 4
Total 37
36
CHAPTER 5
EARLY DESIGN CONCEPTUALISATION
5. 1 Introduction
In this chapter describes the design specifications after evaluating the results from market
research and online survey. Each design sketches are criticised and the potential of it
proceeding to the next stage as the new walker design are decided. (Refer to Table 5.1)
5. 2 Design specifications
After understanding the needs of children with developmental delay, the outcome of the
market analysis and the online survey, a set of design specifications had be developed.
Table 5.1 : Design specifications for the new walker design
Requirements Specifications
Lightweight <6kg
Does not tip over Downward loading on handles in range approx. 25kg
Include multi rung ladder 2-4 horizontal bars below the handles
Collapsible/foldable From upright position to height less than 30cm
Non-slip wheels Speed less than 0.5m/s
Variable resistance wheels Drag force range 50-200N
Multi-axial wheels Number of axles: >2
Estimated retail price <$1500 No more than $900
5. 3 Design sketches
Design 1 (refer to Figure 5.1)
Design 1 was mainly based on the basic requirement and the functionality expected of the
walker. The idea was inspired by a basic children push cart which has 3 wheels and some sort
of a handle for the child to grab and support while they were walking.
37
For Design 1, one of the basic requirement for a child walker is it has to be manoeuvred. So,
wheels are essential and included in this design. For a better manoeuvrability, a 3-wheeled
walker concept was introduced in Design 1. Then, a wide base is attached on the 3 wheels
and connected to the handle and rung ladder frame. The wide base has a shape of an up-side-
down U-shape, which the child will be standing inside the walker and surrounded by the
walker base. The up-side-down U-shape would also give sufficient walking leg room for the
child.
Moreover, in Design 1 a rung ladder and a handle which are constructed with 3 horizontal
bars placed on top of each other for the child to push the walker. The horizontal bars are
attached to 2 vertical bars and the vertical bars acts like a supporting frame and attached to
the base. The rung ladder and handle design is sturdy enough to support the child from a
sitting position to a standing position independently and hold the bar with forearms in
pronation (palms down).
In addition, a height adjustable feature was added to cater the height of 9 month to 2 years old
children. Three different heights can be selected according to the child‟s height. Referring to
the growth chart published by the World Health Organisation (WHO), the height range
between lowest and highest percentile for both boys and girls is approximately 30cm.
Therefore, each height segment is about 10cm. The walker can cater for a child‟s height
range of 66cm to 95cm.
38
Figure 5. 1 : Design 1 sketch in isometric view
An additional feature of Design 1 is a row of Light Emitting Diodes (LED) attached on the
front base of the walker. The basic concept is they would light up/flash when the walker is
pushed. The initial idea of the power source of the LEDs is to light up without any batteries
or electric power source. Therefore, one of the methods is to use the friction caused by
turning of the wheels to power up the LEDs when the walker is being pushed. The main
purpose for placing the LED in the location it is in is to attract the attention of the child when
he/she uses the walker. This hopes to encourage the child to use the walker more often.
Advantages
One of the advantages of Design 1 is it fulfilled a few important requirements that were
identified earlier on for designing a walker for children with developmental delay which is
height adjustanility. This is important because the target for this design is to cater children
with developmental delay from 9 months to 2 years old which ranges from 66cm to 95cm.
Moreover, it has a sturdy handle and rung ladder that is able to support the child to pull up
independently from a sitting position to a standing position. The rung ladder bar is also wide
enough for children with developmental delay to hold on. Another additional advantage of
this design is the idea of the flashing LEDs, which are powered mechanically by friction of
39
the turning wheels. This is because children can get bored easily and will not willingly use
the walker often, by integrating the flashing LEDs on the base of the walker this would
encourage and motivate the child to use the walker.
Disadvantages
This design has a 3-wheeled base. Although a 3-wheeled is advantageous in manoeuvrability,
it lacks stability. Stability is one of the most important aspects in designing a walker for
children with developmental delay. Therefore, stability should not be compromised where
children could be at risk of falling down and injuring themselves. In addition, Design 1 is
considered unsatisfactory because it does not meet the requirement of being collapsible for
easy storage.
Is this design acceptable for the new walker?
Design 1 has interesting features like LED flashing lights, height adjustable, sufficient
walking space in between the base and sturdy multi rung ladder with handle. However, it may
need further improvement or modifications to meet the all the required features. Therefore,
Design 1 is not acceptable.
Design 2 (refer to Figure 5.2)
Design 2 is another conceptual design which focused on the height adjustable mechanism and
collapsible feature. The base frame is 2 round bars attached to 4 pneumatic wheels which
forms like a rectangular shape and the 2 long bars is supported and joined by a horizontal bar
placed near to the frontal area of the walker. Two front wheel and 2 back wheels is designed
to be 5 inch diameter. The reason of the vertical T-bar handle and rung ladder is placed near
to the front is because it allows more spaces for the child to stand and walk in the space
between the 2 back wheels and hold on to the T-bar attached on the base.
The rung ladder is constructed with a T-bar and has 4 short round bars attached to the vertical
bar. The rung ladder consists of height adjustable feature which can convert from 2
supporting rung ladder into 4 horizontal different levels ladders.
40
Figure 5. 2 : Design 2 sketch in isometric view
Moreover, there is a pivot joint which attached the T-bar rung ladder handle and the
horizontal supporting bar which allows it to fold 90 degrees inwards to meet the one of the
design requirements which is collapsible or foldable.
Advantages
Design 2 consists of 4 5-inch pneumatic wheels which meets the design requirement of
stability. The 5-inch wheels is bigger than the commercial baby walkers, and bigger wheels
would give better stability to the walker and also able to push over uneven terrain. Moreover,
pneumatic wheels offer a softer ride than the solid tyres. Moreover, it also meets the
collapsible design requirements which enable easy storage and portable to be carry around.
41
Disadvantages
The main issue for Design 2 is the rung ladder design. The ladder width is narrow and the
height adjustable mechanism is unsuitable for children with developmental delay because
higher cognitive ability is needed for grabbing the rung ladder and also to place 1 hand on top
of the other to pull and stand up independently. In addition, the handle is also too narrow and
allows little space allowance for the child to hold on to it. In terms of aesthetically and
outlook, it is not attractive and not visually pleasing because it is constructed with just simple
round bars and pneumatic wheels.
Is this design acceptable for the new walker?
Design 2 has the advantage of bigger pneumatic wheels that allow walk to be pushed over
uneven terrain and softer ride compared to solid tyres. Collapsible feature is also included. By
considering children with developmental delay, the special rung ladder design is not wide
enough and requires a higher cognitive ability to put one hand higher than the other
alternatively. Hence, Design 2 is not acceptable.
Design 3 (refer Figure 5.3)
Design 3 is a 4-wheeled base walker with a thick rope net that acts as the rung ladder. The
rope net design was inspired by the rope net which normally appeared in a children‟s
playground. The base is a U-shaped which resembles Design 1, allows the child to stand in
between the back wheels.
This design consists of 4 vertical bar attached to the base and the handle. The handle follows
the shape of the base which allows the child to stand inside the walker and hold the bar with
half way between pronation and supination (thumbs up to ceiling).
Advantages
The basic structure is stable and have sturdy handle. Aesthetically have a different looks
where flexible rope is used as multi rung ladder.
42
Disadvantage
This design that feature flexible rope ladder was advised by the Industrial Supervisor that it is
inappropriate for the project‟s targeted young children that still doesn‟t have the cognitive
ability to understand the rope pull. In additional, the strength of children with developmental
delay is limited and it will take more strength to pull up on a flexible structure compared to a
rigid one.
Moreover, the location of the rope ladder limits the child to only holding the handle with
forearms half way between pronation and supination (thumbs up to ceiling). Adjustable
height and collapsible features was not included in Design 3.
Figure 5. 3 : Design 3 sketch in isometric view
Is this design acceptable for the new walker?
Design 3 uses an unconventional way that is using flexible rope ladder for the child to pull
themselves up. However, the flexible rope placement stands in the way for the child to use
the handle. The child cannot hold the handle with forearms in pronation (palms down).
43
Design 4 (refer Figure 5.4)
Design 4 is a combination of several joints and rod members to fulfil all the required features.
It is a four wheeled walker that is attached to 4 rod members. The member attached to the
back wheels is connected to front wheels member and joint by a pivot point. A hinge is
attached just above the extendable segment to allow the walker to fold up. Moreover, the
lower part of the 4 members can be extended to meet the child‟s height.
Handle is designed to give the freedom of holding the handle. The child can hold any part of
the horizontal bar for support while standing and walking. An unconventional design for
substituting rung ladders is flexible rope for children to pull themselves up.
Figure 5. 4 : Design 4 sketch in isometric view (left) and left side view (right)
Advantages
Overall, Design 4 meets most of the design features required such as height adjustable,
collapsible and stability.
Disadvantages
Industrial Supervisor explained that the ladder may have an issue when it is on a backwards
slope and the child may tip backwards as they climb due to shift of centre of gravity.
44
Moreover, it resembles an aged care walker or the rollator and there is a problem that the
parents would be reluctant to purchase for their young child.
Is this design acceptable for the new walker?
Design 4 is successful in the way that it met most of the design requirements which are height
adjustable, collapsible, stability, and rope ladder for substituting rung ladder. However,
aesthetically it is not attractive and parents may not be willing to purchase this design for
their children as it resembles aged care walker and rollator. Market demand is very important
for a design project, since the parents feel reluctant to accept this design it would means that
there are no demand for this design. Therefore, Design 4 is not acceptable and won‟t proceed
to the next stage of the design process.
Design 5 (refer Figure 5.5)
Design 5 is modified from Design 1 (refer to 5.1) which incorporate a stable walker U-shaped
base, 2 horizontal round bar as rung ladder, and the LED flashing lights that is mechanically
powered. In addition to the features stated in Design 1, this modified Design 5 also improve
the stability to 4-wheeled walker. Moreover, the handles were modified to allow the child to
grab the handle in various ways and the bottom of the vertical bar has a pivot joint for it to
fold or collapse.
Advantages
The advantages of this design are it meets all the design requirements such as stability, rung
ladder, sturdy handle, collapsible and an additional creative idea which is the LED flashing
lights on the base. The wider handle area also benefits the child when they are standing they
can either hold the bar with forearms in pronation (palms down) or half way between
pronation and supination (thumbs up to ceiling).
Disadvantages
The disadvantage of this design is the handle may be too wide for younger child.
45
Is this design acceptable for the new walker?
This design meets all the basic framework requirements of the new walk design such as
height adjustability, stability, multi rung ladder, sturdy handle and collapsible. Therefore,
Design 5 is selected to proceed to the next design stage.
Figure 5. 5 : Design 5 sketch in isometric view
46
CHAPTER 6
RESULTS AND DISCUSSION
6.1 Introduction
This chapter describes the new walker design for children with developmental delay. The
Computer Aided Design (CAD) model is drawn using Autodesk Inventor Software which
shows the new walker design in 3D. Moreover, a basic risk analysis for the new design would
be discussed.
6.2 New walker design in CAD (refer Figure 6.1)
Using the Autodesk Inventor Software, the new walker is drawn with further improvement of
„Design 5‟. The improvements are done on the handle and ladder frame parts, where the
width of the handles is now adjustable according to the child‟s needs. Moreover, the handles
can be folded inwards for collapsibility. Figure 6.1 shows the CAD drawing of the new
walker when the walker is at its maximum height, and maximum width between the handles.
Figure 6.1 : Isometric view of the new walker design
Flashing LEDs
Height adjustable
Pivot point (collapsible)
Adjustable handle width
47
Overall dimension
The dimension of the new walker design is 800mm (W) x 900mm (L) x 550mm -740mm (H).
(refer to Figure 6.2 )When the walker is folded, the dimension is 800mm (W) x 900 (L) x
180mm (H).
(a) (b)
Figure 6.2 : Isometric view of the new walker design a) minimum height and minimum
handle width, b) maximum height and maximum handle width.
Figure 6.3 : Isometric view of the new walker design (Folded)
48
6.3 Risk analysis
The new walker design is targeted at young children; hence, it is essential to undertake a risk
assessment to identify the risks of the new walker design. This would raise some awareness
to the carer and the child‟s parents to monitor their children while the walker is used.
A risk analysis is based on the likelihood of the event occurring. Therefore, the outcome of
the risk analysis is subjective and requires knowledge and experience to obtain a meaningful
risk assessment.
Figure 6.4 : Likelihood and consequence matrix adapted from AS/NZS 4360:2004
For this project, the situations to be analysed are falling, minor injuries such as small cuts and
major injuries caused by walker handle not being unfold properly.
Table 6.1 : Risk analysis for the new walker design.
Description Risk analysis
Falling down High
Minor injuries (cuts from sharp edges) Medium
Major injuries (hit by the walker if the walker is unfold properly) High
Referring to Table 6.1, the risk of falling down is identified as being „High‟ because the
developing young child is still in the middle of mastering how to stand and walk especially
for children with developmental delay. Hence, it is „Possible‟ for the child to fall down and
49
the consequence for this is „Major‟, because the child may be injured if they fall. From Figure
6.4, the risk of falling is „High‟.
Minor injuries such as cuts from sharp edges are „Rare‟ to occur because all the edges of the
new walker are rounded. The consequences of minor injuries happening is „Major‟ which
may require prompt treatment. Therefore, minor injuries are categorised as „Medium‟ risk.
Major injuries that may caused by user error while folding or unfolding the walker is
„Possible‟ to happen and the consequences are „Major‟. This means that major injuries are
„High‟ risk for the child.
50
CHAPTER 7
FURTHER WORK AND RECOMMENDATION
This project addressed the initial market analysis, literature review and assessment, and
subsequent mechanical design aspect of the project, but in order to develop the new walker,
various aspects have to be taken into consideration before aspects of commercialisation can
occur.
Braking mechanism and non-slip wheels
An appropriate braking system is needed to prevent the walker from moving while the child
is trying to pull themselves up from a sitting position. Moreover, it is also essential that the
walker have non-slip wheels or equivalent to prevent the walker from running-off, which may
lead to children falling and causing unnecessary injuries. The development of a braking
system for the new walker is currently the subject of another engineering project within the
School, which began in March this year.
Material Selection
Different materials can be used for this new walker design such as wood or stainless steel for
the rung ladder. The walker base has to be slight heavier to provide stability and some gait
training ability for the children, wood can be a good selection or strong plastic like poly
propylene with stainless steel. Strong plastics are good to be use because it can produce in
various colours and it has strong material properties. The handles of the walker are suggested
to use stainless steel to provide sufficient load bearing strength.
Although the material selection is normally selected according to the material that gives the
highest functionality, the cost of the material will likely affect the final material selection
process.
Finite Element Method (FEM) simulation
FEM is a real-time simulation that uses CAD 3-D drawing, where different parameters can be
applied to determine the stiffness, weight, stress, etc. FEM simulation provides the
51
opportunity to test the design via simulation for different types of materials before the actual
manufacturing. This is important in engineering design because it helps to analyse the design
and reduce time significantly from the design phase to the real production.
For this project, FEM simulation should be done by analysing the stress and strain of the
walker especially on both handles and the ladder structure. Ideally, the handles should be able
to withstand the full load of a typically developing child which is approximately 24kg
(including safety factor of 1.5).
Product testing
Product testing is very important before distributed to the market. This is to ensure the
reliability of the products and to also protect the safety of the consumers. In this project, the
aim of the product testing is to test the durability and stability of the design. Once complete,
it is recommended that the walker be tested to the ACCC recommendation, that is, tested in
accordance with ASTM F977-12 “Standard Consumer Safety Specification for Infant
Walkers”.
Cost estimation
From the online survey results showed that the majority of experts selected the price range of
$100-$500. (Refer Table 4.5) Therefore, the wholesale cost of the walker that includes
materials and manufacturing labour, should not exceed $250 to ensure it is market
competitive.
52
CHAPTER 8
CONCLUSION
In conclusion, this project utilised an engineering design process methodology, which began
by understanding the conditions for children with developmental delay, researching and
analysing the current market options, determining the problem statement, and identifying that
no commercial „baby walker‟ is suitable for children with developmental delay.
An online questionnaire that obtained professional‟s feedback and opinions about the
feasibility of a new walker design, the important features and also the desired price range was
then undertaken. Then, conceptualisation of the walker was produced by referring to the
design requirements. From the sketches produced, Design 5 met most of the design
requirements and has been nominated as the initial new walker design. The final design of the
new walker that included some improvements from Design 5, which allows handle width
adjustability and the ability to fold.
Overall, this project focused on the mechanical design of the walker. There are still various
aspects have to be taken into account, such as material selection, FEM simulation, product
testing and cost estimation. Moreover, for future considerations, an appropriate braking
mechanism and non-slip wheels should be included in this walker for better functionality.
This aspect is currently being investigated by another engineering student.
53
REFERENCES
Australian Competition & Consumer Commision 2005, Baby walkers: product safety a
mandatory standard guide, viewed 24 June 2013. <
http://transition.accc.gov.au/content/item.phtml?itemId=724223&nodeId=fcf5de058faca5f
9c51efef0b269d5c2&fn=Product+safety+guide:+baby+walkers.pdf >
Barker, AW 1979, Mobility aid, US Patent 4251105.
Chambers,M & Sugden,D 2006, Early Years Movement Skills: Description, Diagnosis and
Intervention, Wiley.
Coopers Medical Supplies Ltd n.d., The difference between a walker and a rollator, viewed
24 June 2013, < http://coopermedical.ca/2139/the-difference-between-a-walker-and-a-
rollator/>
Dewey, D & Wilson, BN 2001, „Developmental coordination disorder: what is it?‟, Physical
& Occupational Therapy in Pediatrics , The Haworth Press, vol 20. No.2/3, pp. 5-27.
Government of South Australia 2011, Developmental Delay, viewed 23 June 2013,
<http://sa.gov.au/subject/Community+Support/Disability/Disability+types/Developmental
+delay>
Graves, KM 1987, Infant walker, US Patent 4773639
Haik,Y & Shahin TM 2011, Engineering Design Process, 2nd Edition, Cengage Learning.
Hesse, S, Bertelt, C, Jahnke, MT, Schaffrin, A, Baake, P, Malezic, M, Mauritz, KH 1995,
"Treadmill training with partial body weight support compared with physiotherapy in
nonambulatory hemiparetic patients". Stroke 26 (6): 976–81
Hoffman, RE 1991, Handless walking aid for preventing falls from loss of balance, US
Patent 5152730.
Kid Sense Child Development Corporation Pty Ltd. 2013, Developmental Delay, viewed 25
June 2013 <http://www.childdevelopment.com.au/areas-of-
concern/diagnoses/developmental-delay>
Kingsley, D (ABC Science) 2002, Baby walkers delay baby’s walking, viewed 24 June 2013
Knoedler, RE, Morton, KP & Schroer, CE 1989,Collapsible walker, US Patent 4799700
Lamar, C 2012), Behold, the divine baby walker of Jesus Christ,.viewed 20th June
2013, <http://io9.com/5953846/behold-the-divine-baby-walker-of-jesus-christ >
Raising Children Network (Australia) Limited 2013, Developmental delay, viewed 24 June
2013 < http://raisingchildren.net.au/articles/developmental_delay_d.html>
Ries, EF 1961, Walker or walker aid, US Patent 3165112.
54
Robb, WC 1949, Walking aid, US Patent 2656874.
Sadowsky, CL & McDonald, J 2009, „Activity-based restorative therapies: Concepts and
applications in spinal cord injury-related neurorehabilitation‟, Developmental Disabilities
Research Reviews 15 (2): 112–6.
Smith, AF 1969, Invalid walker, US Patent 3517677.
Thomson, G 2011, Children with Severe Disabilities and the MOVE Curriculum:
Foundations of a Task-oriented Therapy Approach. Chester, NY: East River Press. pp.
255–256.
55
APPENDIX A
56
APPENDIX B
57
APPENDIX C
58
APPENDIX D
AP
PE
ND
IX E
6/25/13 6023 SBREC - Final approval (10 May 2013)
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6023 SBREC - Final approval (10 May 2013)Human Research Ethics [[email protected]]Sent: Wednesday, 15 May 2013 2:35 PMTo: [email protected]; David Hobbs [[email protected]]Importance:High
Dear Kim Sim,
The Chair of the Social and Behavioural Research Ethics Committee (SBREC) at Flinders University
considered your response to conditional approval out of session and your project has now been
granted final ethics approval. Your ethics final approval notice can be found below.
FINAL APPROVAL NOTICE
Project No.: 6023
Project Title: Designing a new assistive walker for children with a developmental delay
Principal Researcher: Miss Kim Sim Lee
Email: [email protected]
Address: School of Computer Science, Engineering and Mathematics
Approval Date: 10 May 2013 Ethics Approval Expiry
Date:20 June 2013
The above proposed project has been approved on the basis of the information contained in the
application, its attachments and the information subsequently provided.)
RESPONSIBILITIES OF RESEARCHERS AND SUPERVISORS
1. Participant Documentation
Please note that it is the responsibility of researchers and supervisors, in the case of student
projects, to ensure that:
· all participant documents are checked for spelling, grammatical, numbering and formatting
errors. The Committee does not accept any responsibility for the above mentioned errors.
· the Flinders University logo is included on all participant documentation (e.g., letters of
Introduction, information Sheets, consent forms, debriefing information and questionnaires –
with the exception of purchased research tools) and the current Flinders University letterhead
is included in the header of all letters of introduction. The Flinders University international
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logo/letterhead should be used and documentation should contain international dialling codes
for all telephone and fax numbers listed for all research to be conducted overseas.
· the SBREC contact details, listed below, are included in the footer of all letters of introduction
and information sheets.
This research project has been approved by the Flinders University Social and Behavioural Research Ethics
Committee (Project Number ‘INSERT PROJECT No. here following approval’). For more information regarding
ethical approval of the project the Executive Officer of the Committee can be contacted by telephone on 8201
3116, by fax on 8201 2035 or by email [email protected].
2. Annual Progress / Final Reports
In order to comply with the monitoring requirements of the National Statement on Ethical Conduct
in Human Research (March 2007) an annual progress report must be submitted each year on
the 10 May (approval anniversary date) for the duration of the ethics approval using the annual
progress / final report pro forma. Please retain this notice for reference when completing annual
progress or final reports.
If the project is completed before ethics approval has expired please ensure a final report is
submitted immediately. If ethics approval for your project expires please submit either (1) a final
report; or (2) an extension of time request and an annual report.
Your first report is due on 10 May 2014 or on completion of the project, whichever is the earliest.
3. Modifications to Project
Modifications to the project must not proceed until approval has been obtained from the Ethics
Committee. Such matters include:
· proposed changes to the research protocol;
· proposed changes to participant recruitment methods;
· amendments to participant documentation and/or research tools;
· change of project title;
· extension of ethics approval expiry date; and
· changes to the research team (addition, removals, supervisor changes).
To notify the Committee of any proposed modifications to the project please submit a Modification
Request Form to the Executive Officer. Download the form from the website every time a new
modification request is submitted to ensure that the most recent form is used. Please note that
extension of time requests should be submitted prior to the Ethics Approval Expiry Date listed on
this notice.
Change of Contact Details
Please ensure that you notify the Committee if either your mailing or email address changes to
ensure that correspondence relating to this project can be sent to you. A modification request is
not required to change your contact details.
4. Adverse Events and/or Complaints
Researchers should advise the Executive Officer of the Ethics Committee on 08 8201-3116 or
[email protected] immediately if:
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· any complaints regarding the research are received;
· a serious or unexpected adverse event occurs that effects participants;
· an unforseen event occurs that may affect the ethical acceptability of the project.
Andrea Fiegert
Executive Officer
Social and Behavioural Research Ethics Committee
c.c Mr David Hobbs
Miss Laura De Palma
----------------------------------------------------------------------------------------------
Andrea Fiegert
Executive Officer, Social and Behavioural Research Ethics Committee
Research Services Office |Union Building Basement
Flinders University
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GPO Box 2100 | Adelaide SA 5001
P: +61 8 8201-3116 | F: +61 8 8201-2035 |Web: Social and Behavioural Research Ethics Committee
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