Indirect Posture Correction System without Additional Equipment using
Display Content Rotation
Akira Takahashi, Masahiro Inazawa, Yuki Ban and Shin’ichi Warisawa
Development of Human and Engineered Environmental Studies, Frontier Sciences, The University of Tokyo,
Kashiwa, Chiba, Japan
Keywords:
Posture Correction, Display Content Rotation, Behavior Induction.
Abstract:
The poor posture of office workers who engage in PC work is a problem. Poor posture may cause muscu-
loskeletal disorders. In previous studies on the posture correction system, there are some problems. One of
them is that the posture correction system may interfere with the tasks of office workers. There is a posture
correction system which does not interfere with the tasks; however, it requires large equipment. In order to
solve these problems, we proposed a system that corrects the posture of office workers by rotating the content
in the display. This is a method that rotates content in the opposite direction of head movement. We expect
that users unconsciously move their head to look at content. We evaluated our porposed method with 2 user
studies. User study 1 was conducted to verify whether the angle of the spine changed by rotating the display.
It suggested that rotating the dislay induce the head to adjust laterally, not longitudinally. In study 2, we suc-
ceeded in moving the direction of the angle of spine of experimental participants to the right by an average of
1 deg by rotating the content right. Thus, we showed the possibility of posture correction without large-scale
equipment.
1 INTRODUCTION
In the present working environment, many office
workers work with a PC on a desk. It is suggested
that continuing to work while exhibiting poor posture
leads to musculoskeletal disorders (van Die
¨
En et al.,
2001; Lis et al., 2007). Thus, there is a social need to
develop systems to correct posture.
In existing research on the posture correction sys-
tem, there are two methods: direct posture correction
and indirect posture correction. Direct posture cor-
rection is a way to inform office workers of their poor
posture and thus improve it. Indirect posture correc-
tion is a way to change the surrounding environment
of office workers and correct their posture without
them being conscious of their posture.
A typical example of direct posture correction is
a system by notification. Desktop notification of PC
and the vibration of a vibrator mounted on clothes
are used to inform office workers of their poor pos-
ture (Ishimatsu and Ueoka, 2014; Kim et al., 2016;
Tanaka et al., 2015; Ying Zheng and Morrell, 2010;
Salvado and Arsenio, 2016). However, frequent no-
tifications may interfere with work and degrade task
performance (Adamczyk and Bailey, 2004). Some
studies have focused on preventing interference with
work using a flower avatar (Hong et al., 2015a; Hong
et al., 2015b). It is presumed that the effect in the pos-
ture correction is reduced because of less opportunity
to give feedback to office workers. In other words,
workers are less likely to recognize their poor posture
and correct it. Since every time the system corrects
their posture, it interrupts their task performance, and
the degradation of the task performance becomes a
problem. There is eye-head coordination (Morishima
et al., 2016) in human visual characteristics. Eye-
head coordination is the phenomenon where the eye-
ball rotates and the head rotates following it when
what we look at moves parallel to it. That is, the
head rotates following the parallel movement of what
we look at. Similar phenomena can be seen in previ-
ous studies of indirect posture correction (Shin et al.,
2019; Shin et al., 2018). These approaches tried to ad-
just the display gradually when the worker’s posture
becomes poor. The display adjusts in a direction op-
posite to the direction in which the worker’s posture
becomes poor. Then, workers unconsciously follow
the movement of the display. As a result, the work-
ers’posture improves. Their heads follow the parallel
movement of what we look at and move in the same
direction. The behavior of following the display is
induced by changing the surrounding environment of
the workers. Then their posture is corrected. They un-
consciously follow indirect posture correction with-
266
Takahashi, A., Inazawa, M., Ban, Y. and Warisawa, S.
Indirect Posture Correction System without Additional Equipment using Display Content Rotation.
DOI: 10.5220/0008988902660273
In Proceedings of the 13th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2020) - Volume 4: BIOSIGNALS, pages 266-273
ISBN: 978-989-758-398-8; ISSN: 2184-4305
Copyright
c
2022 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
out this interfering with their tasks. The method of
attaching a robotic arm to the back of a display is
used (Shin et al., 2019). In other research, a work dis-
play is displayed in a large display many times larger
than the work display, and this is moved within the
display (Shin et al., 2018). However, these meth-
ods are not suitable for office environments because
they require the introductions of large-scale equip-
ment such as robot arms and huge displays.
Thus, direct posture correction may interfere with
tasks. Though there is no risk of task interference in
previous works of the indirect induction method, there
is the concern that a giant actuator is necessary and
the introduction cost is large. Thus, in this paper, we
propose an indirect posture correction system without
introducing new large equipment.
In order to solve these problems, we proposed a
system that corrects the posture of office workers by
rotating the content in the display which they use in
their office. We expected that by rotating the content,
their head would adjust in the direction of the rota-
tion and the angle of the spine would become better.
It was thought that we could achieve indirect posture
correction without introducing additional large equip-
ment by using displays that are already available in a
general office.
Previous studies have shown that by adjusting the
displays, the head adjusts along with it. However, it
is not clear whether the head rotates when the display
rotates. We considered that the head does not adjust
by rotating content in a display unless the head adjusts
by rotating the display. First, we experimented to ver-
ify whether display rotation causes head adjustments.
Next, we experimented to verify whether content ro-
tation causes head adjustments.
The contributions of this paper are as follows.
• This paper proposes an indirect posture correc-
tion system to change the head position of office
workers by rotating the screen without using large
equipment.
• It is verified that the angle of the spine changed
following the horizontal rotation of the screen and
it is possible to laterally correct posture.
• It was demonstrated that posture correction was
possible even by rotating the content in the dis-
play.
2 PROPOSED METHOD
We proposed to rotate the content in the display to
correct the posture of workers using indirect posture
correction without large equipment. We considered
φx
θx : Viewing angle
φx : Content rocation angle
Display
Content
Head moves right
Content rotates right
θx
Figure 1: Schematic diagram of the proposed method.
When the head moves right, the displayed content rotates
right.
φy
θy : Viewing angle
φy: Content rocation angle
Display
Content
Head moves downward
Content rotates downward
θy
y
Figure 2: Schematic diagram of the proposed method.
When the head moves down, the displayed content rotates
upward.
that when what we look at rotates, the head adjusts
like the eye-head coordination.
A vertical view of worker and their display is
shown in Figure 1. We define θ
x
as the angle between
a plane perpendicular to the display and perpendicu-
lar to the horizontal plane and the viewing direction
of the head of a worker. We define φ
x
as the rotation
angle of content. The rotational direction of φ
x
is the
opposite direction of θ
x
. A side view of worker and
their display is shown in Figure 2. We define θ
y
as
the angle between a plane perpendicular to the display
and parallel to the horizontal plane and the viewing
direction of the head of a worker. We define φ
y
as the
rotation angle of content. The rotational direction of
φ
y
is the opposite direction of θ
y
. It is thought that as
the rotated content is displayed, the head also moves
in the direction of the content rotation. We consid-
ered that controlling the rotation angle of the content
Indirect Posture Correction System without Additional Equipment using Display Content Rotation
267
would move the head position, and the inclination of
the spine of workers would change; thus, posture can
be corrected.
A worker sits on a chair and the spine tilts back-
ward. Then, the entire content in the display rotates
gradually upwards. The worker unconsciously moves
their head upwards to try to look at the content from
the front. As a result, the spine tilts forward and has
better posture. The system detects posture correction,
and the content rotates back to the original orienta-
tion. Using such a control system in the lateral direc-
tion, workers can always continue to work in a good
posture.
First, it was necessary to verify that the spine tilts
by the rotation of the display to realize our proposed
method. The rotation of the content was different
from the rotation of the display. The content was
not actually rotated but was displayed to workers as
if it really rotated. Workers may not be able to rec-
ognize the display change as the rotation of the con-
tent. Therefore, it was considered that the relation
between the rotation of the visual target and the angle
of the spine cannot be verified. To begin, we verified
whether the angle of the spine changes by rotating the
display, not the content. The following should be ver-
ified.
• Rotation of the display causes the spine to tilt.
• Rotation of the content in the display also causes
the spine to tilt.
• Rotation of the content in the display can correct
the worker’s bad posture.
In this paper, we verified the 1st and 2nd items as the
first step of this research.
3 USER STUDY 1
As described in the previous section, we conducted
the user study to verify whether the angle of the spine
of workers changed by rotating the display. And we
also verified whether the rotation of the display did
not reduce the task performance of workers.
This study was conducted with a within-subject
design. Participants were asked to solve a task in the
display while the display itself physically rotated. We
set three conditions for the direction of rotation (right
rotation, up rotation, no rotation). The angle of the
spine was measured. The task result was measured
as task interfere level. These were compared among
conditions. Three participants joined in this study.
Keyboard
HMD
Figure 3: Participants used HMD and a keyboard on the
desk in the experiment.
Figure 4: 24-inch display is placed on the desk. A tetris task
is displayed at the center of the display. Task performance
is displayed next to the play area.
3.1 Experiment Design
The experimental environment was created in Virtual
Reality (VR). Experiment participants attached Head
Mounted Display (HMD)(Figure 3). We used VR to
place objects relevant to the experiment because vi-
sual and auditory information which is unrelated to
the experiment can be blocked from participants. A
desk and a 24-inch display were placed in the virtual
environment (Figure 4). The distance of the display
to the participants is about 55 cm. The position of the
HMD is measured by an infrared camera. The posi-
tion of the head of participants in the VR was changed
according to the HMD position. It was considered
that necessary conditions for verification were real-
ized because participants can see the display and the
visual field changes according to the head position in
VR. VIVE Pro (HTC) was used for HMD. The refresh
rate was 90 Hz.
The flow of the experiment is described below.
Participants sat on a chair in a comfortable position
BIOSIGNALS 2020 - 13th International Conference on Bio-inspired Systems and Signal Processing
268
z
y
x
5RWDWLRQFRQGLWLRQ
5RWDWLRQFRQGLWLRQ
Figure 5: Rotate the display in the direction of the y-axis in
condition 1. Rotate the display in the direction of the x-axis
in condition 2. No rotation in the display in condition 3.
and were told to solve the task shown in the display.
As the task was shown on the monitor, we selected
Tetris (The Tetris Company, ). Tetris is a famous and
easy to operate game. This was chosen because we
thought that participants could concentrate on a task
and see a large area of the display with this task. To do
this Tetris task, participants only used the arrow keys
of the keyboard placed in front of the participants.
First, participants wore HMD and practiced the Tetris
task for two minutes. Next, they solved the Tetris task
for 15 minutes. The display did not rotate for the first
10 minutes to make participants concentrate on the
task. During the last five minutes, the display was
rotated with one of the three conditions described be-
low. After 15 minutes, participants removedthe HMD
and answered the questionnaire about task interfer-
ence.
The experimental conditions were 3 types: pos-
itive y-axis rotation condition (right rotation), nega-
tive x-axis rotation condition (upward rotation), and
no rotation condition (Figure 5). The y-axis negative
rotation (left rotation) was excluded from the condi-
tions considering the symmetry. Negative x-axis ro-
tation (downward rotation) was also excluded from
the conditions because it was considered that it was
not necessary to guide the head downward to correct
the posture. These three conditions were conducted
for each participant. The order of the conditions was
counterbalanced. For each direction, the rotational
speed was 0.1 deg/s, and the maximum rotational an-
gle was 30 deg. The rotation speed was chosen to be
low enough so that participants were unconscious of
the rotation of the display. The maximum rotational
angle was determined so that participants could rec-
ognize the rotation of the display while it rotated at a
low speed.
(a) (b)
Figure 6: (a) We calculated the forward and backward angle
of the spine in the upward display rotation condition. (b)
We calculated the right and left angle of spine in the right
display rotation condition.
Start display rotation
Spine angle [deg]
Upward display rotation
No rotation (control)
Experiment Time [s]
Figure 7: Forward and backward inclination of the spine
with upward display rotation and no rotation conditions.
Red line denotes upward display rotation and blue line de-
notes no rotation.
The head’s position was obtained from the HMD
position measured by the VIVE Pro base station. The
accuracy and precision of position tracking in the
HTC VIVE is under 0.2 mm (Niehorster et al., 2017).
We calculated the angle of the spine from the head
position of the participants. We considered the initial
spine angle was perpendicular to the horizontal plane.
The angle from the initial position was calculated as
shown in Figure 6.
As an objective index of task interference, the
number of deleted rows of the Tetris task for 15 min-
utes was obtained and defined as the task perfor-
mance. In order to obtain a subjectiveindexof task in-
terference, participants were asked to answer a ques-
tionnaire. The method of answering the questionnaire
was the 9-grade evaluation.
3.2 Result
An example of a displacement of the angle of the
spine of a participant with a display rotating upward
Indirect Posture Correction System without Additional Equipment using Display Content Rotation
269
Start display rotation
Spine angle [deg]
Right display rotation
No rotation (control)
Experiment Time [s]
Figure 8: Right and left inclination of spine of right display
rotation and no rotation conditions. Red line denotes right
display rotation and blue line denotes no rotation.
Figure 9: Displacement of the forward and backward in-
clination of the spine between last and first 10 seconds of
display rotation.
and right is shown in Figure 7 and 8. In the right
rotation condition, it can be seen that the angle of
the spine is displaced in the positive x-axis direction
(right) as compared with the control condition. On the
other hand, it can be confirmed that in upward rotation
condition, the y coordinate did not change despite the
display’s rotation.
In order to measure the angle displacement due to
display rotation, the displacement between the angle
for 10 s before the end of the display’s rotation and the
head coordinates for 10 s before the start of the dis-
play’s rotation was regarded as the angle of the spine
due to the display rotation. The displacements were
calculated for each conditions for all participants and
their mean and standard errors were calculated (Fig-
ure 9 and 10).
3.3 Discussion
Figure 9 shows that there is no large difference in the
displacement of the forward and backward inclination
of the spine between the upward rotation condition
and the control condition. On the other hand, it can
Figure 10: Displacement of the right and left inclination
of the spine between last and first 10 seconds of display
rotation.
be seen from Figure 10 that the displacement of the
angle of the spine in the right direction was larger in
the right rotation condition than in control condition,
indicating that the head moved to the right. As the
participant’s head moved to the right due to the ro-
tation of the display, it indicated that the rotating dis-
play has a potential to induce the worker’s spine angle
in a lateral rotation.
Then, we discussed the reason why upward an-
gle displacement did not occur with upward display
rotation. The Tetris task was to pile blocks falling
from the top. It was considered that for participants,
the visibility of the display did not get worse in the
upward rotation condition compared to right rotation
condition in the case of the vertical rotation. That’s
why participants did not look at the screen from above
in order to improve it. In actual desk work, informa-
tion such as web pages and documents are displayed
from top to bottom. Therefore, even in actual desk
work, there is a high possibility that head position ad-
justment is not possible by the vertical rotation of a
display.
From the questionnaire and task performance,
there was no large difference in task interference
among all conditions. Therefore, there seemed to be
no task interference by the rotation of the display.
Thus, there is a possibility of inducing the spine
angle displacement with lateral rotation of the dis-
play without interfering with task. In the next chapter,
on the lateral rotation in which the angle of the spine
change was indicated, it was verified whether the an-
gle of the spine can be induced only by the horizontal
rotation of content in a display with a fixed orienta-
tion.
BIOSIGNALS 2020 - 13th International Conference on Bio-inspired Systems and Signal Processing
270
z
x
θ
φ-θ
θ
φ
φ
Figure 11: A vertical view of the display and participants.
Red content indicates the content in condition 1 (right rota-
tion without head-sync). Green content indicates the con-
tent in condition 2 (right rotation with head-sync). Gray
content indicates the content in condition 3 (no rotation).
Figure 12: These are the displays seen by the participants
when θ = 15 deg. (a) no rotation condition. (b) right rota-
tion with head-sync condition when φ = 30 deg. (c) right
rotation without head-sync when φ = 30 deg.
4 USER STUDY 2
In study 1, we verified the possibility of lateral pos-
ture induction by physically rotating the display. This
study verified whether posture can also be changed by
the rotation of the content in the display.
This study was also conducted with participants
with a within-subjects design. Participants were
asked to solve a task located in the display. While
participants solved the task, the content in the display
was rotated to the right. This verified whether the an-
gle of the spine of participants was induced to adjust
in the direction of content rotation. There were three
experimental conditions. Right rotation with synchro-
nization of the head position, without synchroniza-
tion, and no rotation. The head position of partici-
pants was measured to calculate the angle of the spine.
Task results were measured as the task interfere level.
These were compared among the conditions. The
number of participants was 18.
4.1 Experiment Design
The experimental environment and flow of the exper-
iment were almost the same as study 1. The experi-
mental environment was created using VR and partic-
ipants attached HMD. The difference was that the size
of the displayed content was 80% as large as study 1.
This is because if the size is the same as study 1, con-
tent is hidden because of the rotation.The task was
Tetris in the same way as study 1.
There were three experimental conditions.
1. Right rotation without synchronization with the
position of the head (right rotation with head-
sync)
2. Right rotation with synchronization with the posi-
tion of the head (right rotation without head-sync)
3. No rotation.
Similar to study1, the negative rotation of the y-axis
(left rotation) was excluded from the conditions con-
sidering the symmetry. The order of the conditions
was counterbalanced.
A vertical view of the display and content rota-
tion is shown in Figure 11. In condition 1, content
(green content in Figure11) was rotated at 0.3 deg/s
like study 1. The maximum rotational angle was
30 deg. We defined the rotational angle of content in
condition 1 as φ. In condition 2, if participants moved
their head with the content’s rotation, the visibility of
the content was improved. The angle between the z-
axis (forward) and the viewing direction of a partici-
pant is defined as θ (viewing angle) θ was calculated
from the head position of the participants (x, z). Using
these, the rotation angle of content in the display was
presented in φ− θ (red content in Figure11). For ex-
ample, if a head was always perpendicular to the con-
tent, the rotation angle of a content is always 0 deg.
Task seen by the participants is shown in Figure 12.
The method of measuring the angle of the spine
and the task performance of participants was also the
same as study 1.
4.2 Result
An example of the angle of the spine of a participant
in every condition is shown in Figure 13 and 14. It can
be seen that in right rotation with head-sync condi-
tion, the angle of the spine changed in the positive x-
axis direction (Right) compared with no rotation con-
dition.
The results of all 18 participants is shown. The
displacements of the angle of the spine were calcu-
lated for all participants and the mean and standard
errors of these displacements were calculated. A com-
parison of the displacement in all three conditions is
shown in Figure 15.
Indirect Posture Correction System without Additional Equipment using Display Content Rotation
271
Start content rotation
Spine angle [deg]
Right content rotation with head sync
No rotation (control)
Experiment Time [s]
Figure 13: Right and left inclination of spine with right con-
tent rotation with head sync and no rotation conditions. Red
line denotes right content rotation with head sync and blue
line denotes no rotation.
Start content rotation
Right content rotation without head
No rotation (control)
Experiment Time [s]
Spine angle [deg]
Figure 14: Right and left inclination of spine of right con-
tent rotation without head sync and no rotation conditions.
Purple line denotes right content rotation without head sync
and blue line denotes no rotation.
4.3 Discussion
It can be seen that the head position significantly ad-
justed in the positive x-axis direction (Right) in both
the right rotation with and without head-sync condi-
tions. Based on this, there is an indication of the pos-
sibility of inducing the angle of the spine by the ro-
tation of the content. There was no significant dif-
ference in induced head displacement in rotation with
or without head-sync. The displacement of the angle
was smaller than that of physical display rotation in
study1.
Next, the reason why there was no difference be-
tween the displacement of the angle with and without
head-sync is discussed. In this study, φ− θ is almost
same as φ because head displacement is no more than
10 mm. Accordingly, it was considered that there was
no difference in the displacement of head regardless
of the synchronization of the rotation with head.
The displacement of the angle of the spine in this
Spine angle [deg]
Right rotation with
head sync
Right rotation without
head sync
No rotation
n.s.
*
**
: p<0.05, : p<0.01, n.s. :not significant
Figure 15: Displacement of the right and left inclination of
the spine between the last and first 10 seconds of display
rotation.
study was smaller than the physical display rotation
in study 1. This is thought to be because participants
were not motivated to look at the display. The visibil-
ity of the content was not improved because if partic-
ipants displaced their head and looked at the display.
From the questionnaire and task performance,
there were no large difference in task interference
among all conditions. Therefore, there seems to be
no task interference by rotating the display.
In study 1, by rotating the display laterally, the
possibility of inducing the head to adjust laterally
without interfering task performance was indicated.
In study 2, by rotating content in a display laterally,
the possibility of inducing the head to adjust laterally
without interfering task performance was also indi-
cated. In addition, it was suggested that the head in-
duction did not depend on whether the rotation syn-
chronized with head position.
5 CONCLUSION
In this paper, we proposed content rotation as means
of indirect posture correction without large-scale
equipment. This is a method that rotated content in
the opposite direction of the direction of head move-
ment. We expected that users would unconsciously
move their head to look at the content.
To realize the proposed method, we conducted
two user studies. First, we verified whether the head
followed the display rotation. As a result, the direc-
tion of the spine tilted to the right at an average of
5 deg against display right rotation. However, the
spine did not tilt against display upward rotation. Sec-
ond, we verified whether the angle of the spine also
followed the content’s right rotation. As a result, the
direction of the spine tilted to the right at an average
1 deg against content right rotation. Therefore, we
showed the possibility of inducing the spine to the left
BIOSIGNALS 2020 - 13th International Conference on Bio-inspired Systems and Signal Processing
272
and right directions by rotating the content shown in
the display.
In this study, we could not induce the spine to tilt
in the upward direction. Future studies may investi-
gate the cause. In addition, we did not verify whether
content rotation can induce the improvement of poor
posture to good posture. Furthermore, we need to de-
velop a system that can be embedded to the office en-
vironment.
We expect that our proposed method will promote
the low-cost prevention of musculoskeletal disorders
in office workers.
REFERENCES
Adamczyk, P. D. and Bailey, B. P. (2004). If not now, when?
In Proceedings of the 2004 conference on Human fac-
tors in computing systems - CHI ’04, pages 271–278,
New York, New York, USA. ACM Press.
Hong, J.-K., Koo, B.-C., Ban, S.-R., Cho, J.-D., and
Bianchi, A. (2015a). BeuPo:A Digital Plant that You
Can Raise and Customize with Your Current Posture.
In Proceedings of the 2015 ACM International Joint
Conference on Pervasive and Ubiquitous Computing
and Proceedings of the 2015 ACM International Sym-
posium on Wearable Computers - UbiComp ’15, pages
1015–1020, New York, New York, USA. ACM Press.
Hong, J.-k., Song, S., Cho, J., and Bianchi, A. (2015b). Bet-
ter Posture Awareness through Flower-Shaped Ambi-
ent Avatar. pages 337–340.
Ishimatsu, H. and Ueoka, R. (2014). BITAIKA - Develop-
ment of self posture adjustment system. In Proceed-
ings of the 5th Augmented Human International Con-
ference on - AH ’14, pages 1–2, New York, New York,
USA. ACM Press.
Kim, J., Lee, N. H., Bae, B.-C., and Cho, J. D. (2016). A
Feedback System for the Prevention of Forward Head
Posture in Sedentary Work Environments. In Proceed-
ings of the 2016 ACM Conference Companion Pub-
lication on Designing Interactive Systems - DIS ’16
Companion, pages 161–164, New York, New York,
USA. ACM Press.
Lis, A. M., Black, K. M., Korn, H., and Nordin, M. (2007).
Association between sitting and occupational LBP.
European Spine Journal, 16(2):283–298.
Morishima, K., DAIMOTO, H., CHIHARA, T., and YA-
MANAKA, K. (2016). The relation between eye-
head coordination and useful field of view. Jour-
nal of Japan Industrial Management Association,
67(3):252–260.
Niehorster, D. C., Li, L., and Lappe, M. (2017). The accu-
racy and precision of position and orientation tracking
in the HTC vive virtual reality system for scientific
research. i-Perception, 8(3):1–23.
Salvado, L. and Arsenio, A. (2016). Sleeve sensing tech-
nologies and haptic feedback patterns for posture
sensing and correction. International Conference on
Intelligent User Interfaces, Proceedings IUI, pages
74–78.
Shin, J., Choi, W., Lee, U., and Saakes, D. (2018). Actuat-
ing a Monitor for Posture Changes. pages 1–6.
Shin, J.-G., Onchi, E., Reyes, M. J., Song, J., Lee, U., Lee,
S.-H., and Saakes, D. (2019). Slow Robots for Un-
obtrusive Posture Correction. In Proceedings of the
2019 CHI Conference on Human Factors in Comput-
ing Systems - CHI ’19, pages 1–10, New York, New
York, USA. ACM Press.
Tanaka, K., Ishimaru, S., Kise, K., Kunze, K., and Inami,
M. (2015). Nekoze!-Monitoring and detecting head
posture while working with laptop and mobile phone.
Proceedings of the 2015 9th International Conference
on Pervasive Computing Technologies for Healthcare,
PervasiveHealth 2015, pages 237–240.
The Tetris Company, L. Tetris. http://www.tetris.com (ref-
erence date, October 24th ,2019).
van Die
¨
En, J. H., De Looze, M. P., and Hermans, V. (2001).
Effects of dynamic office chairs on trunk kinemat-
ics, trunk extensor EMG and spinal shrinkage. Er-
gonomics, 44(7):739–750.
Ying Zheng and Morrell, J. B. (2010). A vibrotactile feed-
back approach to posture guidance. In 2010 IEEE
Haptics Symposium, pages 351–358. IEEE.
Indirect Posture Correction System without Additional Equipment using Display Content Rotation
273