Human Factor Validation of Pediatric Mobility Device
Phase: NA
Conditions: Disability Physical
Sponsor: Permobil, Inc.

 
 
 
 
 
Permobil AB 
Title: Human Factor Validation of Pediatric Mobility Device 
NCT03714256 
[Author name] 
Document version: 06 August 2018 
 

 
Human factors validation test protocol, version 06 August 2018 
 
 
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Explorer Mini Human Validation Test Protocol 
 
 
 
 
 
 
 
 
 
 
 

 
Human factors validation test protocol, version 06 August 2018 
 
 
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1 Table of Contents 
2 
Background ..................................................................................................................... 3 
3 
Purpose and Scope ........................................................................................................ 4 
4 
Sample and recruitment .................................................................................................. 5 
4.1 
Eligibility criteria .......................................................................................................... 5 
4.1.1 
Inclusion criteria ...................................................................................................... 5 
4.1.2 
Exclusion criteria ..................................................................................................... 5 
4.2 
Sampling ..................................................................................................................... 6 
4.3 
Recruitment ................................................................................................................ 6 
4.3.1 
Informed consent .................................................................................................... 6 
5 
Study design and conduct ............................................................................................... 6 
5.1 
Methodology ............................................................................................................... 7 
5.1.1 
Screening and enrolment ........................................................................................ 7 
5.1.2 
HF Validation test – Observations ........................................................................... 7 
5.1.3 
HF Validation test – Interviews ................................................................................ 8 
6 
Reporting results ............................................................................................................. 8 
6.1 
Data analysis .............................................................................................................. 8 
7 
References ..................................................................................................................... 9 
8 
Attachments ...................................................................................................................10 
Attachment 1 Observation form .........................................................................................10 
Attachment 2 Interview form ..............................................................................................10 
Attachment 3 Child test form .............................................................................................10 
Attachment 4, Recruitment script ......................................................................................10 
 
 
 

 
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2 
Background 
The theoretical foundations behind early mobility draws its roots from empirical research in the 
1950s where the interplay between physiology and psychology was investigated. A line of 
seminal works showed the cognitive processes that are ‘born’ and nurtured when toddlers 
begin to be mobile. The implications of immobility or inefficient mobility in toddlers with physical 
disabilities were particularly drawn to attention by Butler and colleagues in the 1980s when 
modified power wheelchairs (PWC) were trialed on toddlers. Early trials focused on testing 
whether toddlers can learn to use PMT, but as it became established that toddlers can indeed 
learn to use them, trials moved to measure changes in the child’s overall development, 
particularly their cognitive functioning and social skills. 
 
Over the past 30 years, the negative impact of immobility or inefficient mobility in toddlers with 
physical impairments has been cast under the spotlight. For typically developing toddlers, the 
onset of self-produced locomotion has been recognized to induce positive changes in their 
developmental processes (Campos et al., 2000). Toddlers are observed to learn key skills 
through mobile play and exploration, but in the presence of physical impairment, the same 
need for learning these skills through mobility may be hindered. Conversely, children with 
physical limitations could instead be prone to a condition termed as ‘learned 
helplessness’,(Everland, 1984) where they learn, instead, to be resigned to accept their 
environment and to no longer seek to influence it. 
 
“Children’s mastery of functional mobility skills has been classified and categorized in several 
ways. Hays (1987) examined current existing diagnostic conditions of children without 
locomotion and divided them into four functional groups” (Wright-Ott, 2015, p.564). 
 
1. Children who will never ambulate. 
This category includes children with cerebral palsy with severe involvement and spinal 
muscular atrophy types I and II. Generally, these children have no opportunity for 
independent mobility. 
 
2. Children with inefficient mobility who ambulate but are unable to do so at a  
reasonable rate of speed or with acceptable endurance. 
This category includes children with cerebral palsy with less involvement and 
myelomeningocele with upper extremity involvement. For these children, assisted 
mobility may provide an efficient means of mobility above that which they are capable 
of producing themselves. Warren (1990) uses the term “marginal ambulator” for this 
group. 
 
3. Children who have lost their independent mobility. 
This category includes victims of trauma and children with progressive neuromuscular 
disorders. The developmental implications may be less critical than in the first two 
groups, and the issue is acceptance of assisted mobility as an adaptation to an 
acquired disability, 
 
4. Children who temporarily require assisted mobility and often progress to independent 
mobility with age. 
This category includes many children with osteogenesis imperfecta and arthrogryposis. 
Functional considerations in this group are both developmental and practical. 
 
Children with mobility impairments, as categorized by Hays (1987) may benefit from the use 
of a power mobility device for functional mobility (Wright-Ott, 2015, p. 564) Regardless of the 
etiology, pathology or prognosis of the condition that limits mobility, children may be able to 
achieve increased functional mobility, even independent mobility if consideration to other 
factors are taken into account. These factors include but are not limited to “purpose and goals 
for the use of the device, environments for intended use, child’s physical and psychosocial 

 
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abilities and limitations, modifications that may be needed for comfort and control, and cost-
benefit ratio” (Wright-Ott, 2015, p. 564). 
 
There are significant differences among these groups that may have implications for mobility 
and its integration into the child’s overall concept of disability, as well as for evaluation and 
intervention. Group I children may achieve independent mobility through the use of a support 
walker or power wheelchair. Group II children may be able to independently propel a manual 
wheelchair, ambulate in a support walker indoors, and use a power wheelchair for community 
mobility. Children in group III and IV will use a variety of mobility methods during the transition 
period. (Wright-Ott, 2015, p.564). 
 
“Introduction of Power Mobility Devices (PMD) for some therapists focuses on arbitrary age-
based criteria while others look to a set of similarly arbitrary skills that indicate readiness. 
Researchers have been exploring how young children can begin using PMD. Typically 
developing infants aged between 5 and 10 months have been successful using a PMD that 
utilized whole body movement rather than a joystick (Larin, Dennis, & Stansfield, 2012). 
Researchers at University of Delaware have had success with infants with and without 
disabilities initiating movement using joysticks at 7 months (Lynch et al., 2009), 11months 
(Ragonesi & Galloway, 2012) and 14 months-of-age (Galloway et al., 2008). Case studies 
describe children with age-appropriate cognitive skills using PMD competently as young as 17 
months (Zazula & Foulds, 1983), 20 months (Jones, McEwen, & Hansen, 2003), and 22 
months-of-age (Everard, 1984). Jones et al (2012) showed that 14-30-month olds who had 
frequent access to a PMD in the home setting learned successful mobility skills in the presence 
of significant disability.” (Rosen, Plummer, Sabet, Lange, & Livingstone, 2018, p.4). Many 
practitioners believe that provision of a PMD should be considered within the first year of life 
(Wright-Ott, 2015, p.563). However, current research suggests that children as young as 5-7 
months of age are successful at operating a PMD. Infants, at six months of age begin to be 
mobile in their environment. Additionally, at 6 months of age an infant has a strong inner drive 
to reach to midline and engage in bilateral and unilateral reaching, grasping and manipulating 
objects (such as a joystick). They display adequate head and trunk extension to support 
themselves in an upright seated position (Parham & Mailloux, 2015, p. 263). “Growing 
evidence indicates that these early motor experiences not only inform children about their own 
actions, but also the action of others” (Woodward, 2009). For an infant unable to be 
independent in self-initiated mobility, the opportunity to explore their environment by accessing 
a midline-oriented device provides an inherently motivating means of control.  
 
PMD for young children and toddlers has been evolving to provide an efficient option to assist 
mobile play and exploration; however, no PMD has been successfully marketed in large 
volumes before. The testing of the Explorer Mini is an innovative and unique mobility device 
that is well suited to provide an opportunity to assess an infant’s readiness to utilize a 
supported seat and midline control device to demonstrate self-initiated mobility. 
 
3 
Purpose and Scope 
The scope of the human factors validation test is to demonstrate that the device can be used 
safely by the intended users, for its intended use. The preliminary analyses, as described in 
the human factors validation plan, builds the rationale behind the device related tasks included 
in the test and it will be performed on a device and accompanied labelling that represent the 
final design.  
 
The test will be performed in a clinical setting including participating children, their 
parents/guardians and physiotherapists/occupational therapists (PTs/OTs) at three clinical 
sites in the United States of America, post evaluation and approval from applicable Internal 
Institutional Review Board (IRB). A clinical setting, while not fully reflective of a home 

 
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environment is the typical testing area for mobility related assessments as trained 
practitioners (PTs/OTs) have access to a variety of devices, and a means of creating a safe 
environment specific to the child. The clinic is also the place where the child and 
parent/guardian in real world situation would be introduced to and trained on a mobility 
device.  
 
4 
Sample and recruitment 
4.1 Eligibility criteria 
 
The test participants represent the two populations of intended users: 
 
Primary users – children with mobility impairments  
Secondary users – care-givers (parents/guardians and PTs/OTs)  
 
4.1.1 Inclusion criteria 
 
Primary users: 
• 
Informed consent signed by parents or guardian 
• 
Aged 6-36 months  
• 
Unable to mobilize independently for exploratory play and peer interaction, as 
cathegorized by Hays (1987) 
• 
Adequate trunk and head control to remain upright in the device, including regain head 
control 
• 
Adequate hand/ arm (distal) control to reach for objects in front of them 
 
Evaluation of children has traditionally focused on achievement of developmental milestones. 
However, underlying impairments cannot fully explain the extent and form of functional 
difficulties seen in children with mobility impairments (Coster, 1998). Additionally, "the tasks 
most relevant for functional mobility have not been well defined in traditional developmental 
milestone test" (Wright-Ott, 2015, p. 564). In this test, all included children have a mobility 
impairment but for reasons described above, no specific diagnosis is set as inclusion criteria 
for the primary user and the mobility impairment of the user will depend on a variety of 
diseases, diagnoses, cognitive or functional disorders.  
 
Secondary users: 
• Signed informed consent 
• PT/OT or parent/guardian of the child included in the test  
 
4.1.2 Exclusion criteria 
 
Primary users: 
• Weight >16 kg/35 Ibs  
• Length >100 cm/39 In 
• Children that lack head control in such a severe manner that they cannot regain control if 
it is lost 
• Children who do not show awareness of or respond to toys, objects, sounds and/or people 
in their environment 
• Any other reason, if in the opinion of the investigator, the individual user is not appropriate, 
or suitable for participation in the test. 
 
 
 

 
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Secondary users: 
• Hearing/vision loss or limited cognitive skills impacting the ability to take instructions and 
perform the tasks of the test 
• Ability to understand oral and written English as product labelling will in this HF validation 
test only be available in English 
• Any other reason, if in the opinion of the investigator, the individual user is not appropriate, 
or suitable for participation in the test 
 
4.2 Sampling 
 
Because successful mastery of a power mobility device has been demonstrated with children 
over the age of 17 months, and children as young as 7 months demonstrate early skills 
necessary for power mobility the testing groups will be set at 6-17 months and 18-36 months. 
It is anticipated that children with supported trunk (proximal) control will have adequate hand/ 
arm (distal) control and inherent motivation and development to operate a midline-oriented 
control.  
 
Enrollment of eligible children will be conducted to ensure 30 per protocol performed tests, 15 
children per age group.  
 
6 months – 17 months 
15 children 
18 months – 36 months 
15 children 
 
Along with the 30 children, their 30 parents/guardians will be actively participating in the study 
as well as their PT/OT. 
 
4.3 Recruitment 
 
Recruitment will be initiated after a favourable decision from the local IRB has been received. 
The study clinics will be participating in this test, recruiting 10 children/parent pairs each. The 
principal investigators will reach out to PTs/OTs, to identify children managed by them who 
would match the inclusion/exclusion criteria of this test. A recruitment script may be used (see 
attachment 4). It is expected that there is an established connection between the child and the 
PT/OT already prior to this test.  
 
4.3.1 Informed consent 
 
Informed consent will be obtained prior to the participants undergoing any activities that are 
specifically for the scope of the test. In the process of gaining informed consent, the child’s 
parents/guardian and PT/OT will receive information about the nature and objectives of the 
study, possible risks associated with their participation, their free choice of participating and 
leaving at any time, both in writing and orally. They will also have the opportunity to ask 
questions and be able to retain the information long enough to make an effective decision.  
 
5 
Study design and conduct  
 
This is a descriptive, cross-sectional study to evaluate users’ interactions with and perceptions 
of the device user interface. This will be done in two major steps: 
• 
Observations of users´ performance of all critical and some non-critical tasks identified 
in the preliminary analyses and evaluations (observational data) 
• 
Debriefing interview to collect the users´ perspective of the device (interview data) 
 
 
 

 
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5.1 Methodology 
 
The introduction of the device to the children and caregivers will, once the product is 
commercially available, be performed by a PT/OT. Supplemental instructions will be given in 
the user’s manual. In order to validate that the device is safe to use also without having 
received any training, the first observational part of the study will be performed in three steps. 
 
1. 
To simulate an initial encounter with the device for a PT/OT where the device may be 
handled without any additional instructions, the child’s PT/OT will first perform the test 
tasks untrained. The PT/OT will be provided with the User’s manual but may not be 
prompted to use it for written information of the product. 
 
2. 
In standard of care, after having learned how to use the device, a PT/OT would show 
the parent/guardian how to operate the device. In step two, the Principal Investigator 
will train the parent/guardian and the PT/OT on the device (standard product training) 
supported by references to the Users’ manual.  
 
3. 
The parent/guardian performs the test tasks, supported with the Users’ manual and 
PT/OT or Principal Investigator.  
 
The Principal Investigator will provide arm’s length supervision throughout all steps of the study 
to ensure the safety of all participants. 
 
5.1.1 Screening and enrolment 
 
After having obtained written informed consent from the participants the Principal Investigator 
will control and ensure that the inclusion and exclusion criteria of this study protocol are met 
(including weight and length measure), and complete the upper part of the child test form, 
attachment 3, covering background information on the child.  
 
The enrolment can, but does not need to, be done on the same day as the actual test. 
 
5.1.2 HF Validation test – Observations 
 
1. The child’s PT/OT is presented to the device and it’s labelling and is asked to: 
• connect the battery charger to the battery charging port, and disconnect it. 
• adjust the seat and table height so that they are appropriate for the child.  
• adjust the speed of the device so that it is appropriate for the child. 
• place the child into the device. 
• if needed, adjust cushion and/or other support to ensure that the child is placed properly 
and safely. 
The PI documents the observations on an observation form, attachment 1. 
 
2. The Principal Investigator presents the device and labelling (including user manual) to the 
parent/guardian and PT/OT and performs a standard product training of the device. 
 
3. The parent/guardian is presented to the device and it’s labelling and is asked to: 
• connect the battery charger to the battery charging port, and release it. 
• adjust the seat and table height so that they are appropriate for the child.  
• adjust the speed of the device so that it is appropriate for the child. 
• place the child into the device. 
• if needed, adjust cushion and/or other support to ensure that the child is placed properly 
and safely. 
The PI documents the observations on another observation form, attachment 1. 

 
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The activities above are derived from the risk-analysis of the device, performed prior to this 
test, and are performed by the secondary users, where the child is needed in order to perform 
them but does not play an active role.  
 
One PT/OT may be the professional care-giver to more than one of the children included in 
the test. Step one above will only be performed once for an individual PT/OT. 
 
4. As the child is placed in the device by the parent/guardian, the child is allowed to explore 
the device for 5 minutes. The child will be instructed to place their hand on the joystick and 
watch how he/she can move it. If the child does not initiate after a verbal prompt the 
Principal Investigator will place the child’s hand on the joystick. The child test form, 
attachment 3, will be used to describe the child’s actions and reactions. 
 
If the child seems interested they may be placed in the device up to two times during the 
visit, with at least five minutes of rest in between. If the child shows signs of distress (such 
as crying) for at least one-minute, then they will be taken out of the device for a five-minute 
rest period. A new attempt will be made to place the child in the device. A maximum of 
three, one-minute attempts will be made to provide an opportunity for the child to use the 
device before this step is ended. 
 
The Principal Investigator will use the observation form for secondary users to document 
observed user problems and use errors during the test, see attachment 1.  
The Principal Investigator will complete two forms per test: 
1. The child’s PT/OT (performing the test without training)  
2. The child’s parent/guardian (performing the test with training) 
 
The Principal Investigator will use a child test form for primary users to document observed 
user problems and user errors during the test as well as the ability to get the device in motion 
and the child’s actions and reactions. 
 
User errors performed during the tasks will be divided into three severity levels: 
1. User experienced difficulties in performing the task but did not lead to harm 
2. User performed an error that could have resulted in harm but never did 
3. User performed an error that resulted in harm.  
Details of the risk analysis performed in the preliminary analysis can be found in the Human 
Factors validation plan ES1692. 
 
5.1.3 HF Validation test – Interviews 
 
After the tasks in 5.1.2 have been performed, the Principal Investigator will interview the child’s 
parent/guardian and PT/OT, in order to collect their perspectives of the tasks, to complement 
the task performance observations. An interview form, attachment 2, will be used. 
 
6 
Reporting results 
 
The test data will consist of: 
1. Completed observation forms 
2. Completed interview forms 
3. Completed child test forms 
 
6.1 
Data analysis 
 
After completion of the human factors validation testing, the results of the observations and 
interviews will be analyzed qualitatively and quantitatively to determine if the design of the 

 
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device can be used by the intended users without serious use errors or problems. The 
results will be summarized in a human factors validation report.  
 
7 
References 
 
Everard, L. (1984). The wheelchair toddler. Health Visitor, 57(8), 241–242. Retrieved from 
http://www.ncbi.nlm.nih.gov/pubmed/6565681  
 
Campos JJ, Anderson DI, Barbu-Roth MA, Hubbard EM, Hertenstein MJ, Witherington D. 
(2000) Travel broadens the mind. Infancy. 1(2):149–219. 
 
Galloway, J., Ryu, J.-C., & Agrawal, S. (2008). Babies driving robots: Self-generated mobility 
in very young infants. Intelligent Service Robotics, 1(2), 123–134. 
http://doi.org/10.1007/s11370-007-0011-2 
 
Hays RM. (1987). Childhood motor impairments: clinical overview and scope of the problem. 
In J. KM (Ed.), Childhood Powered Mobility: Developmental, Technical and Clinical 
Perspectives (pp. 1–10). Seattle, Washington: RESNA. 
 
Jones, M., McEwen, I., & Hansen, L. (2003). Use of power mobility for a young child with 
spinal muscular atrophy. Physical Therapy, 83(3), 253–62. Retrieved from 
http://www.ncbi.nlm.nih.gov/pubmed/12620089 
 
Jones, M., McEwen, I., & Neas, B. (2012). Effects of power wheelchairs on the development 
and function of young children with severe motor impairments. Pediatric Physical Therapy, 
24(2), 131–140. http://doi.org/10.1097/PEP.0b013e31824c5fdc 
 
Larin, H. M., Dennis, C. W., & Stansfield, S. (2012). Development of robotic mobility for 
infants: rationale and outcomes. Physiotherapy, 98(3), 230–7. 
http://doi.org/10.1016/j.physio.2012.06.005 
 
Lynch, A., Ryu, J.-C., Agrawal, S., & Galloway, J. (2009). Power mobility training for a 7-
month-old infant with spina bifida. Pediatric Physical Therapy, 21(4), 362–8. 
http://doi.org/10.1097/PEP.0b013e3181bfae4c 
 
Parham, L.D. & Mailloux, Z. (2015). Sensory Integration. In  J. Case-Smith and J., C. O’Brien 
(Eds) Occupational Therapy for children and adolescents, (7th ed. Pp. 258-303) St. Louis: 
Elsevier. 
 
Ragonesi, C., & Galloway, J. (2012). Short-term, early intensive power mobility training. 
Pediatric Physical Therapy, 24(2), 141–148. http://doi.org/10.1097/PEP.0b013e31824c764b  
 
Rosen, L., Plummer, T., Sabet, A., Lange, M., & Livingstone, R. (2018) RESNA position on 
the application of power mobility devices for pediatric users. Assistive Technology, Vol.00 1-
9, doi: 10.1080/10400435.2017.1415575 
 
Warren, C. G. (1990). Powered mobility and its implications. Journal of Rehabilitation 
Research and Development. Clinical Supplement, 27, 74-85. 
 
Woodward, A.L. (2009). Infants grasp of others. Current Directions in Psychological Science, 
18 (1), 53-57. 
 
Wright-Ott. (2015) Mobility. In J. Case-Smith and J., C. O’Brien (Eds) Occupational Therapy 
for children and adolescents, (7th ed. Pp. 560-594) St. Louis: Elsevier. 

 
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Zazula, J., & Foulds, R. (1983). Mobility device for a child with phocomelia. Archives of 
Physical Medicine and Rehabilitation, 64(3), 137–139. Retrieved from 
http://www.ncbi.nlm.nih.gov/pubmed/6830425 
 
8 
Attachments 
 
 
Attachment 1 Observation form 
Observation form, HF validation test protocol 06 August 2018  
 
Attachment 2 Interview form  
Interview form, HF validation test protocol 06 August 2018 
 
Attachment 3 Child test form  
Child test form, HF validation test protocol 06 August 2018 
 
Attachment 4, Recruitment script  
Recruitment script, HF validation test protocol 06 August 2018