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

 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:

REFERENCES

Li M L, Zhang Z F. (2021). Research on the design of desks

and chairs based on the behavior of preschool children.

D. Central South Forestry University.

Liao P P. (2021). Ergonomics research on collaborative

integration of realistic and digital environments. .J.

Computer Applications. 7,76-78.

NMDME 2022 - The International Conference on New Media Development and Modernized Education

540

He J H, Ma Z K, Zhang J H, Ma X L, Wang J, Xu S C,Yang

X. (2017).Digital modeling of children's human body

and its application in school bus seat design. J. China

Science Paper, 10,1103-1108.

Zhao L L. (2020). Multifunctional modular children's table

and chair design and practice. D. Qilu University of

Technology.

Yuan M Y, Yu N, Zhong S L. (2017). Humanized design of

children's learning chairs. J. Products, 11,106-107.

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