An Ergonomic Study of Child Seat Comfort Based on Pressure
Distribution
Yaqin Ye
*
and Mei Lv
Design Institute of Art, Shenyang Jianzhu University, Hunan street, Shenyang, China
Keywords: Pressure Distribution, Child Seat, Comfort, Ergonomics.
Abstract: As the living standard improves, users also put forward higher requirements for the comfort of child seats.
This paper studied the comfort of child seats from the perspective of human pressure distribution
characteristics, and the effect of different child seat angles on the human pressure distribution. The X-sensor
pressure distribution test system was used to test the human pressure distribution and the subjective evaluation
of human comfort under different child seat angles. The effect of child seat angle on the pressure of the ischial
tuberosity position of the hip contact surface, mid-thigh position, front-thigh position and the backrest was
analyzed, and then the area values of these three different levels of pressure areas and their respective
percentages of the total contact area were extracted separately, and the effect of the child seat angle change
on them was analyzed. Finally, the most relevant index parameters for human subjective comfort were selected
and the most comfortable child seat angle was solved.
1 INTRODUCTION
1.1 Mics Overview
Ergonomics is a comprehensive applied discipline
that studies the relationship between people,
machines and the environment, and it covers many
fields such as anthropometry, psychology, behavior,
and medicine. Ergonomics has been involved in all
aspects of people's lives, especially in household
products. In this paper, ergonomics-based child seat
comfort evaluation research can effectively improve
the comfort of child seat products. (Li, Zhang, 2021)
1.2 Child Seat Design
The child seat is an indispensable learning facility in
the current home learning and education place, in
order to further improve the learning efficiency of
children and meet the requirements of the learning
and growth stage to provide healthy development, the
seat set for children's learning is being continuously
optimized and designed, and the child seat has now
changed from a traditional seat to a seat set with both
intelligent and entertainment functions. Relevant
designers should pay attention to the following design
principles when carrying out child seat design: First,
safe and comfortable. Provide children with safe
materials and comfortable products. Second, easy to
use. In the case of diverse functions can also be
convenient to operate. Third, the appearance of the
design. The appearance of the child seat design
cannot be boring, and needs to meet the aesthetics of
children.
2 RESEARCH SIGNIFICANCE
ON THE COMFORT OF CHILD
SEATS BASED ON PRESSURE
DISTRIBUTION
The correct sitting posture must be the pressure on
the body is evenly distributed on the intervertebral
discs, and the static load should be evenly distributed
on the muscle tissue.
(Liao, 2021) Nowadays, some
important parts of the well-designed child seats can
be adjusted independently (such as the reclining
angle of the backrest, the reclining angle of the seat
surface, etc.), but there are no specific
recommendations for the appropriate child seat
backrest angle and seat surface angle, resulting in
people still adjusting various parts of the child seat
according to their own preferences in the process of
Ye, Y. and Lv, M.
An Ergonomic Study of Child Seat Comfort Based on Pressure Distribution.
DOI: 10.5220/0011915500003613
In Proceedings of the 2nd International Conference on New Media Development and Modernized Education (NMDME 2022), pages 537-541
ISBN: 978-989-758-630-9
Copyright
c
2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)
537
using the child seat. (He, Ma, Zhang, Ma, Wang, Xu,
Yang, 2017)
Some researchers found that 97.5% of the
participants used the seat angle adjustment function
every day; 70% of them use these features when
resting and relaxing to increase comfort and pain
relief. Researchers studied the use of child seat
features, and the results showed that the participants
used the child seat 11.8 ± 3.4 hours per day; the
average number of times users left the child seat was
5.0±5.3 times/day; the average time for posture
change was 53.6±47.0 minutes; the longest hold
position was 214.68±7.4 minutes; functional use
shows that the use of recline, backrest recline, seat
surface elevation were 11.9±9.4 times/day, 10.9±9.4
times/day, O±7.9 times/day and 4.3±4.5 times/day,
respectively. However, this adjustment may make the
child seat comfortable to use for a period of time but
may not be scientific for a long time. Long-term use
of improperly designed child seats will increase the
pressure on the skeletal muscles, resulting in fatigue
and discomfort, and sometimes numbness in the
lower limbs. In the long term, this can lead to neck
and shoulder pain, lumbago and other spinal diseases,
as shown in Figure 1. In particular, the unreasonable
distribution of sitting body pressure caused by
improper design can lead to decubitus ulcers in
patients with spinal injuries. (Zhao 2020)
Some studies have shown that child seats with
tiltable seats and backrests can be adjusted at an angle
to reduce user fatigue, and placing them at an angle
can help reduce contact pressure and prevent skin
ulcers. However, few studies have studied the comfort
of child seats through the angle of the child seat. Most
people who use child seats are those who cannot take
care of themselves and cannot move independently,
which makes the comfort of child seats especially
important in their view. Furthermore, the
reasonableness of human pressure distribution is an
important factor in determining the comfort of child
seats.
Figure 1. Spinal deformation caused by poor sitting posture
3 RESEARCH METHODS ON
THE COMFORT OF CHILD
SEATS BASED ON HUMAN
PRESSURE DISTRIBUTION
3.1 Sample Selection
20 healthy and normal children aged 4-8 years with
body weight less than 25 kg were selected as
subjects, including 10 males and 10 females. The
subjects were required to have no history of
musculoskeletal disorders, no sports injuries and no
physical discomfort in the past 6 months. The test
was completed under the guidance of the
experimenter. At the same time, the tested children
were able to think logically, had their own subjective
sense of things, and were able to distinguish between
good and bad and give advice. Some of the data were
collected with the informed consent of the tested
children and their parents. For the accuracy of the
experimental data and in consideration of the low
temperature in winter, the subjects were asked to
wear no more than two layers of clothes, and some
test data are shown in Table 1.
Table 1. Data of some tested children
Subject
data
S1 S2 S3 S4 S5 S6 S7 S8
Mean
±standard
deviation
Min Max
Sex Male Female Male Female Male Male Female Female - - -
Age/year 6 5 8 6 7 6 4 8 6.25±1.39 4 8
Height/cm 113 96 115 116 100 109 103 126 109±10 96 126
Weight/kg 20.95 12.61 21.00 20.05 16.00 17.05 11.00 21.65 17.53±4.43 11.00 21.65
Shoulder
width/cm
31 24 36 31 25 26 21 28 28±5 21 36
NMDME 2022 - The International Conference on New Media Development and Modernized Education
538
Waist
width/cm
20 18 25 21 18 19 16 20 20±2 16 25
Hip
width/cm
22 20 24 24 23 21 18 21 22±2 18 24
Thigh
length/cm
19 15 17 18 16 16 12 20 16±3 12 20
3.2 Otal Pressure Distribution Test
This test is conducted under normal driving or riding
conditions using a pressure test mat laid on the seat of
the vehicle to be measured. The subject rides on the
seat in a normal sitting position, and the pressure
distribution on the seat should be uniform, with no
pressure peaks. The pressure distribution cloud map
should not show red areas except for the ischial
tuberosity position, and the backrest should not show
red areas. Pressure distribution can not appear clamp
change phenomenon.
4 STUDY ON PRESSURE
DISTRIBUTION
CHARACTERISTICS OF HIP
CONTACT SURFACE OF
CHILD SEAT
This chapter mainly studies the pressure distribution
characteristics of the contact surface of child seat and
human hip, that is, the contact surface between the
human hip and the child seat, because the pressure
distribution on the contact surface of the human hip
in a sitting position has an important influence on the
human comfort. According to the anatomical
characteristics of the human body, the locations
where the human body is under pressure in a sitting
position are selected, i.e., the contact surface of the
ischial tuberosity, the mid-thigh and the front-thigh
positions. Pressure contact area which is how the
pressure distribution also has an important role in
comfort. The whole hip contact area was divided into
low pressure area, medium pressure area and high-
pressure area according to the pressure range, and the
area values of these three different levels of pressure
areas and their respective percentages of the total
contact area were extracted and analyzed.
The pressure distribution cloud diagram of the
pressure test mat was divided into three equal
positions: the position of the ischial tuberosity, the
middle of the thigh and the front of the thigh, as
shown in Figure 2.
Figure 2. Pressure distribution cloud output example
The pressure distribution cloud map of the
backrest is divided into three equal parts: the pressure
curves of the corresponding areas in the upper
backrest position, the middle backrest position and
the lower backrest position. The maximum pressure
(N), the average pressure (N) and the contact area
(cm) are analyzed. See Figure 3.
An Ergonomic Study of Child Seat Comfort Based on Pressure Distribution
539
Figure 3. Pressure distribution diagram
5 CONCLUSION
(1) From the experimental data processing, it can
be seen that with the increase of the child seat angle,
the overall trend of the average pressure on the back,
the maximum pressure on the back and the back
contact area are increasing. In the meantime, the
overall trend of the average pressure on the hip, the
maximum pressure on the hip and the hip contact area
are decreasing. The reason is that the child seat angle
increases, the subject as a whole tilts backward, and
the force on the back of the human body increases
and takes up part of the force on the human body's
hip. Therefore, an appropriate increase in the seat
angle can effectively reduce the force on the human
body's hip.
(2) The average back pressure, maximum back
pressure, back contact area, average hip pressure,
maximum hip pressure and hip contact area were
obtained by measuring the human pressure
distribution under different child seat angles. The
regression analysis of the index parameters and the
child seat angle was conducted to obtain the variation
law of the index with the seat angle and its
polynomial regression equation.
Based on the results of the study, the following
laws were obtained: the contact area is larger to fit
the human-computer morphology, and the comfort is
higher, which verifies the point made by previous
researchers - one factor affecting comfort or
discomfort is the pressure distribution of the body or
the body-object contact part; comparing the pressure
trend after the contact surface, the riding experience
of children before 30CM is more comfortable. By
extracting time points and plotting the trend, it proves
that children's ride comfort has a certain pattern with
time, which is effective and feasible; children's
comfort of the seat depends on the size of the contact
area. This provides a new innovation point for future
child safety seat design, which can help companies
further improve the comfort and enhance the
experience of their products. (Yuan, Yu, Zhong,
2017)
Examples taken from published papers:
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