Development of soft flat-tube-based actuator for easy dressing andundressing
Ikumi Hayashi, Student member, IEEE, Tetsuyou Watanabe, Member, IEEE

Abstract— Maintaining the shape of clothing without twistingor wrinkling, and ensuring a clear path for the arms, canfacilitate the process of dressing and assisting with dressing. In
this context, this study aims to develop a new device thatincreases the stiffness of clothing to maintain its shape. Flat tube
based new soft actuator is developed for the stiffness incase infabric. Normally, the flat tube actuator straightens and increasesthe stiffness. In this study, by making cuts, the flat tube actuatorcan be bent, resulting in attachment to rounded area of clothing.
In addition, a friction reduction mechanism is installed alongwith the stiffness increased part by air flow mechanism tofurther facilitate dressing and undressing. The validity of thedeveloped mechanism was verified by several experiments
including human evaluation.

Additionally, the function of friction reduction has also notbeen considered.

I. INTRODUCTION
This study presents a novel soft actuator that isincorporated into garments to maintain the garment's shape byadjusting stiffness while reducing the friction between the skinand garment. The daily routine of dressing and undressing isfundamental. However, for individuals with motor disabilities,
this task can be significant challenges. Caregivers assistingsuch individuals must exercise caution to avoid damaging theclothing, injuring the skin, or affecting any body part. During
dressing or undressing, garments often become “twisted,”
complicating the process of rectifying these entanglements.
Preventing such twisting is, therefore, critical to streamline thechanging process [1]. By maintaining the garment's shapewithout inducing twists or wrinkles and ensuring a clear
passage for the arms, the dressing and assistance procedures
can be greatly simplified. This study focuses on upper body
garments and presents a novel device that increases clothing
stiffness, as depicted in Fig. 1, to maintain its shape.
Additionally, the device features mechanisms to reduce
friction during clothing changes, further facilitating theprocess.
Wearable devices capable of varying their stiffness andincorporating fabric have been developed [2][3]. However,there has been limited focus on applications in dressing andundressing. An example is the pneumatic smart adaptive belt
developed by Helps et al. [4], which can loosen the belt
through air pressurization. Unfortunately, they did notconsider the need for expansion and stiffness increase in thearm and leg areas of garments to prevent twisting andwrinkling, aspects crucial for dressing and undressing.

* I. Hayashi is with the Graduated school of Natural science andTechnology, Kanazawa University, Kakuma-machi, Kanazawa, 9201192
Japan.

Figure 1. Whole design of the developed soft flat-tube-based actuator, anddetailed structures of the shape maintenance components in the longitudinal
direction and sleeve cap

II. SOFT ACTUATOR FOR EASY DRESSING AND UNDRESSING
As a first step, we focused on the sleeve area and developeda sleeve equipped with soft actuators along the sleeve cap andin the longitudinal direction of the sleeve. Fig. 1(a) shows theoverall view of the structure. The structure of the soft
actuators positioned along the sleeve cap (Fig. 1(b)) and thelongitudinal direction (Fig. 1(c)) of the sleeve is also shown.
The main components in both components are soft actuators.
T. Watanabe is with the Faculty of Frontier Engineering, Institute ofScience and Engineering, Kanazawa University, Kakuma-machi, Kanazawa
city, Ishikawa, 9201192 Japan (e-mail: te-watanabe@ieee.org)

The soft actuators, designed with cuts in flat tubes, can be bent
flexibly. In the sleeve cap area shown in Fig. 1(c), in addition
to the cuts, the thickness of the top and bottom surfaces isvaried, allowing bending to occur by inflating them. When air
is introduced, the soft actuator expands the garment,maintaining its shape. The expansion of the sleeve cap also
increases the width of the sleeve opening. Along thelongitudinal direction of the sleeve, silicone tubes are added
to the soft actuators, with air flowing out from their outlets toreduce friction between the skin and the garment (see Fig.
1(b)). A notable feature is that all the soft actuators arecontrolled by air flowing through a single channel.
III. EVALUATION OF FEASIBILITY
A. Maintaining of the shape of sleeve cap
Fig.2 shows the experimental setup. The sleeve withstiffness and friction variable soft actuator was fixed on thestand. The load cell (IMADA，ZTS-DPU-50N) attached on
the automatic poisoning stage (Orientalmotor，DRLM42G04A2PM-K) was moved downward along the z-axis at
1.0mm/s, and the sleeve cap of the garment is pushed
downward. The load was measured by force gauge (IMADA，ZTS-i). Measurements were taken three times, both with andwithout air pressurization.

Figure 3. Stiffness vs. displacement of the sleeve equipped with thesoft actuator for maintaining the shape of the sleeve cap, and thedeformation of the sleeve cap with and without air pressurization
Figure 2. Experimental setup for evaluating the developd soft actuator for
maintainng the shape of the sleeve cap

B. ResultFig.3 shows the result of experiment. As shown in Fig. 3(a),when pressurized with air, the shape of the sleeve cap wasmaintained and the reduction in stiffness was suppressed tomore than 10 N/m. On the other hand, when not pressurized,
the shape of the sleeve cap was not maintained and thestiffness dropped to nearly 0 N/m.
Fig. 3(b) shows the deformation of the sleeve cap underapplied load. When the soft actuator is pressurized with air,the shape of the unloaded parts of the sleeve cap is maintainedeven when load is applied. Conversely, if the soft actuator was
not pressurized, applying load to the sleeve cap results in thedeformation of the entire sleeve cap, causing it to collapse.
when the actuator pressed by the load cell, only the pressedpart is deformed. These results show that the developed soft
actuator can increase the stiffness of the sleeve cap andmaintain its shape.

IV. FUNCTIONAL EVALUATION
A. Experimental procedure
The participants were 8 students (6 males and 2 femaleswith an average ag of 22.4 ±1.30). The participants wereinstructed to extend their arm parallel to the ground and towear the developed sleeve from their wrist to their shoulder for
5 seconds each, both with and without air pressurization. Afterremoving the sleeve, the participants respond on a Likert scale
regarding space, discomfort, ease of dressing and undressing,ventilation, and changes in wearing comfort, comparing theconditions with and without air pressurization.
B. Result and discussion
Fig.4 shows the result of the experiment. Significant
differences were observed in terms of space and ease ofdressing and undressing. The results indicate that increasing
stiffness and reducing friction improves the ease of dressing
and undressing. Furthermore, it was found that, as shown inFig. 5, it was found that the sleeve could be undressed without
twisting or wrinkling if pressurizing with air to maintain its
shape.

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Figure 4. Participants' responses on space, sense of restriction, ventilation,and ease of dressing and undressing, comparing the conditions with andwithout air inflation; e.g. a positive score indicates large speciousness whilea negative score indicetes narrow speciousness

Figure 5. Shape of the develoepd sleeve during undressing (Left :without
air pressurization, Right: with air pressurization)

V. CONCLUSION
This study presented a novel soft actuator integrated into agarment to increase its stiffness for shape maintenance, while
simultaneously reducing the friction between the skin andgarment. The improved shape retention in the sleeve cap andalong the sleeve's longitudinal direction, coupled with thefriction reduction, facilitated easier dressing and undressing.
The functionality was confirmed through the evaluation tests
by human subjects. Future work will involve developing an
upper-body garment incorporating the soft actuator andconducting further investigations in more practical situations.
VI. ACKNOWLEDGEMENT
This work was partly supported by JST [Moonshot R&D]
[Grant Number JPMJMS2034] and JSPS KAKENHI Grant
Number JP23H04343.
REFERENCES[1]

C. Sato et al., “RTechnique 6 Rehabilitation Technique and Supportof Dressing and Bathing Activity for Patients with,”
7[4]V, J,R J,“Technology for Soft Robotic and AutonomousG,” Adv. Funct. Mater., vol. 31, no. 6, Feb.
2021, doi: 10.1002/adfm.202008278.
A. Zannat, M. N. Uddin, S. T. Mahmud, P. S. S.
,R M , “R:-based soft,” J.
Mater. Sci., vol. 58, no. 31, pp. 12491–12536, Aug.
2023, doi: 10.1007/s10853-023-08799-4.
T. Helps, M. Taghavi, S. Manns, A. J. Turton, and J.
R, “EUR,”
2018, pp. 79–90. doi: 10.1007/978-3-319-967288_7.