SUGISAKAMASANORI

Journal of Robotics, Networking and Artificial Life
Vol. 9(4); March (2023), pp. 363–368
ISSN (Online):2352-6386; ISSN (Print):2405-9021
https://alife-robotics.org/jrnal.html

Noritaka Sato, Kyosuke Ushimaru, Yoshifumi Morita
Department of Electrical and Mechanical Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku,Nagoya, Aichi 466-8555, Japan

Received 25 November 2021
Accepted 05 March 2023

We proposed a new tactile presentation device for a palm to tele-operate a robot hand mounted
on a rescue robot. The proposed device presents a tactile sensation on the back of the operator’s
hand rather than the palm to avoid interference. The required specification for the device weredetermined through subject experiments conducted in our previous studies. In particular, wedeveloped a prototype device through suction stimulation with the required specifications,confirmed that the device can present tactile sensation correctly, and discussed the results.

Rescue robot
Haptic device
Teleoperation© 2022 The Author. Published by Sugisaka Masanori at ALife Robotics Corporation Ltd.
This is an open access article distributed under the CC BY-NC 4.0 license(http://creativecommons.org/licenses/by-nc/4.0/).

Robot hand[5],[6], but we cannot find systems that provide feedbackon the contact state of the palm.
On the other hand, in the field of virtual reality, someresearchers have proposed haptic devices for the palm[7],[8]. However, by using them, the device willinterference the motion of the opening/closing of thehand. Therefore, Okano et al. have proposed methods ofsubstituting the tactile presentation of the palm to otherparts of the body [9]. Their device substituted by the sole
the foot for the tactile presentation of the palm.
In this study, the tactile sensation was substituted by
the back of the hand instead of the palm to avoid
interference between the device and fingers. Moreover,
we assumed that the operator could recognize the tactile
state more accurately because the tactile sensation ispresented just behind the palm.
In our first report [10], the tactile characteristics on theback of a human hand were clarified to obtain thespecifications required to develop the proposed device.
In the second report [11], we found that tactile sensation

1. Introduction
After the Great Hanshin-Awaji Earthquake in 1995, there
has been an extensive research and development ofdisaster-response robots in Japan [1]. Disaster-response
robots that can gather information and perform tasks havebeen in demand in recent years [2]. Therefore, disasterresponse robots equipped with robotic arms and hands
have been developed to achieve human-likecharacteristics, such as removing obstacles andmanipulating valves [3]. Disaster-response robots are
moved and operated in unknown and extreme
environments; therefore, they are tele-operated byhumans in safe areas [4].
It is necessary to provide feedback to the operator on
the contact state between the fingers and palms of therobot hand and the object to be grasped for efficientteleoperation with the robot hand. However, in the fieldof robot teleoperation, there are some systems thatprovide feedback on the contact state of the fingers

Corresponding author’s E-mail: sato.noritaka@nitech.ac.jp, k.ushimaru.884@nitech.jp, morita@nitech.ac.jp363

can be presented as a surface without changing thespecifications. In the third report [12], we changed thestimulation method from pressing to suction to make thedevice small and light. In the fourth report [13], weinvestigated the relationship between the diameter of thesuction pad and correct answer rate, and found that thelarger the diameter, the higher the correct answer rate. In
the fifth study [14], a prototype of the proposed device
was developed based on the results of the fourth report[13]. In this study, its performance was verified anddiscussed through subjective experiments.

Fig. 1. Ideal method

2. Substitute Tactile Presentation Device for theBack of the Hand
Ideally, to correctly convey the state of contact between
the robot hand and grasping objects to the operator, thetactile sensation is presented directly to the palm of thehand, as shown in Fig. 1 and our first report [10].
However, when the robot hand is directly tele-operated
by the operator's hand, the haptic device may interferewith the fingers, because the robot hand is teleoperated
with open-close motion of the operator’s hand and thedevice is mounted on the operator’s palm. Therefore, we
proposed a method to present the tactile sensation on theback of the hand instead of the palm (Fig. 2).

Fig. 2. Proposed method

2.1. Parameter Identification
The following parameters are required to design such aback-of-the-hand substituting tactile presentation device.
- Interval between stimulus points (interval: i)- Diameter of the stimulus point (diameter: d)- Force of the stimulus point (force: f)
Human skin sensation has well-known characteristics,
such as a two-point discrimination threshold. In
particular, two close stimulation points are cnsidered as
one point. Therefore, we conducted an experiment on thesubjects to confirm the characteristics of the tactile
sensation on the back of the hand for our proposed device[10]. The combination (i, d, f) = (30 mm, 6 mm, 0.9 kg)
had the highest rate of correct answers.
However, to develop a tactile presentation device,suction stimulation is utilized instead of pressure
stimulation because the device will becomes significantly
large with pressure stimulation. Therefore, we designed
the device as shown in Fig. 3. In the third and fourthreport [12][13], we verified how well the pressure
stimulation position of the palm matched the suction
stimulation position of the back of the hand through aFig. 3. Designed device with parameters obtained byexperimentsubject experiment. We found that the correct answer rate
for suction stimulation was highest when (i, d, f) =(30mm, 15mm, 0.9kgf).
2.2. Developed prototype device
The prototype device shown in Fig. 4 was developed
based on the specifications determined in our previous
studies [12][13]. The device comprises suction pads,suction brackets, and fixtures created by a 3D printer.
According to the determined parameters, the diameter ofthe suction pads was 15 mm and the interval between
each pad was 30 mm.
2.3. Substitutional Tactile Presentation System
Fig. 5 shows the system configuration of the entire tactile
presentation device for the back of the hand, as explainedin Section 2.2. The device provides suction stimulation
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Fig. 4. Prototype device(Left: Top view, Right: Bottom view)Fig. 6. Experimental scene(Control side)

Fig. 7. Experimental scene(Subject’s side)
Fig. 5. Overview of the system for the experiment

to the user. The vacuum pump was GCD-051X(ULVAC), and nine regulators for vacuum pressure
control were ITV2090 (SMC). The vacuum pressure canbe controlled by the input voltage of the regulator, and a
micro-computer (Arduino) outputs the input voltage toeach regulator. Nine surface pressure sensors were used
to convert the contact strengths to voltages, which wereread using the Arduino.
3.

Fig. 8. Number of stimulation point.

Performance Verification Experiment ofTactile Presentation Device

The experimental scenes of the control and subjectside are presented in Figs. 6 and Fig. 7, respectively. In
this experiment, we sequenced the sensors on the desk
instead of the robot hand to simplify the experiment setup as shown on the right side of Fig. 6. Fig. 7 shows thedevices on subject’s side. Only the lightweight prototype
device was mounted on the operator’s hands. The
stimulation positions for the experiment are shown in Fig.
8. There is a one-to-one relationship between the surfacepressure sensor and sucker. Suction stimulation wasapplied to the back of the hand in predetermined orders

3.1. Experimental Methods
In this study, we reported the results (correct answerrates) of an experiment in which five operators answered
the position of a suction stimulation when it was applied
to the back of the operator's hand using the prototype
device. Nine points on their backs of the hand are pressed
one by one (case 1), twenty points two by two (case 2),
and thirty points three by three (case 3). Note that in ourprevious report [14], the number of subjects andstimulation points were two and one, respectively.
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as shown in Tables 1, 2, and 3. Each participant
answered the numbers of the stimulation points.

means that the combination of stimulation points
matched completely.

Table 1. Order of stimulus presentation (Case 1).
Order ofstimulation
12
3
4
5
6
7
8
9Suctionstimulation
27
98
5
1
3
6
4
Fig. 9. Correct answer rate of the experiments.

Table 2. Order of stimulus presentation (Case 2).
3.3. Discussion
Order ofstimulation
12
3
4
5
6
7
8
9Suctionstimulation
3, 6
7, 8
1, 56, 84, 72, 55, 65, 7
2, 3

In our previous study [8], we found that the correct
answer rate of human skin characteristics in the case of
one stimulation was 85 %. We believe that the subjects
recognized the position of the stimulation points almost
correctly even if the proposed device was used because
the rate was almost same between with and without theproposed device. Moreover, the incorrectly answered
positions were located to above or below correct position.
Therefore, we believe that the validity of the proposed
method was confirmed.
Additionally, we measured the response time fromthe start of the stimulus to participant’s answer. In mostcases, the response was completed within 5 s. Therefore,
we believe that the results are reliable because it wasconfirmed that the subjects answered the position without
hesitation.
By comparing the correct answer rates of Cases 1, 2,
and 3, it can be observed that the rate decreased slightly.
However, because the width of the reduction was notlarge, the proposed method was applied to multiple
stimulations.
In this experiment, the pressure of the vacuum pumpis set to constant value (-54 kPa). To improve theseresults, it may be necessary to change the pressure. We
plan to study how to change pressure for appropriatestimulation.

Table 3. Order of stimulus presentation (Case 3).
Order ofstimulation
12
3
4
5
6
7
8
9

Suctionstimulation
2, 5, 81, 2, 37, 8, 93, 5, 73, 6, 91, 5, 92, 3, 6
1, 2, 46, 8, 93.2. Results
In this experiment, five subjects were introduced tothree cases of stimulations as shown in Tables 1, 2, and3. The total number of collected data was 150. A graphof the results for Cases 1, 2, and 3 are shown in Fig. 9.
Average correct answer rates for Cases 1, 2, and 3 are82.2%, 75.6%, and 73.3%. In this experiment, “correct”

4. Conclusion
In this study, we developed a device according to thespecifications determined in our previous studies and366

Teleoperation of Robot Hand, K. Ushimaru et al, Haptic
Device that Presents Sensation Corresponding to Palm on
Back of Hand for Teleoperation of Robot Hand -Report 5:
Verification of development device specifications-, Proc.
of International Conference on Artificial Life and Robotics,
GS6-3, 2021.
12. K. Ushimaru et al., Experimental Consideration onRequirements Specification of Haptic Device that PresentsSensation Corresponding to Palm on Back of Hand for
Teleoperation of Robot Hand, Tokai-Section Joint
Conference on Electrical, Electronics, Information, andRelated Engineering, E2-2, 2021. (in Japanese).
13. K. Ushimaru et al., Haptic Device that Presents Sensation
Corresponding to Palm on Back of Hand for Teleoperationof Robot Hand -Report 4: Consideration of the Detection
Error of the Stimulus Position between the Palm and theBack of the Hand-, Proc. of International Symposium on
Socially and Technically Symbiotic Systems, STSS-35,2021.
14. K. Ushimaru et al, Haptic Device that Presents Sensation
Corresponding to Palm on Back of Hand for Teleoperationof Robot Hand -Report 5: Verification of development
device specifications-, Proc. of International Conferenceon Artificial Life and Robotics, pp.201-204, 2022.

then performed subjective experiments to verify itsperformance. Accordingly, we obtained approximately
80% of the correct answers. Therefore, we believe that
this device has the potential to be used in theteleoperation of robotic hands.
In the future, we plan to increase the number ofstimulation points. Subsequently, we plan to confirm
whether the users can recognize accurately when thepressure of the vacuum pump is controlled. Finally, theproposed device will be applied in the teleoperation task
and verify the effectiveness of the proposed method.
Acknowledgements
This work was supported by the JSPS Grant-in-Aid for
Scientific Research (JP19K04309).

References
1. S. Tadokoro, et al., Rescue Robotics: DDT Project on
Robots and Systems for Urban Search and Rescue,
Springer-Verlag London, 2009.
2. S. Tadokoro, Disaster robotics, Advances in Cooperative
Robotics, p. 3, 2017.
3. S. Tadokoro, Overview of the ImPACT Tough Robotics
Challenge and Strategy for Disruptive Innovation in Safetyand Security, Disaster Robotics, pp. 3-22, 2019.
4. N. Sato et al., User Interface Technology for Rescue Robot
Teleoperation, Journal of the Robots Society of Japan, Vol.
28, Issue 2, pp. 156-159, 2010. (in Japanese).
5. K. Mima, et al., Tele-Manipulation with Humanoid Robot
Hand/Arm via Interne, Proc. of the Japan Joint AutomaticControl Conference, Vol. 54, 2K303, 2011. (In Japanese)
6. K. Negishi, et al., i-MarioNET: Remote Operated
Humanoid Robot System Controlled by Telexistence FST(Robotics for Hazardous Fields), The Proc. of JSME
annual Conference on Robotics and Mechatronics, 1A1R14, 2013. (In Japanese)
7. K. Minamizawa, et al., A PalmWorn Haptic Display for
Bimanual Operations in Virtual Environments, Proc.
International Conference on Human Haptic Sensing andTouch Enabled Computer Applications, pp 458-463, 2008.
8. T Taniguchi, et al., Multi-Point Pressure Sensation
Display using Pneumatic Actuators, Proc. of EuroHaptics
2019, LNCS 10894, 58-67, 2018.
9. T Okano, et al., Haptic Feedback for Foot Sole Using
Pneumatic Pressure Device, Proc. of ASIAGRAPH2016,pp. 3-6, 2016.
10. N. Sato, et al., Haptic Device that Presents Sensation
Corresponding to Palm on Back of Hand for Teleoperationof Robot Hand Report 1: Clarification of Required
Specifications by Subject Experiment”, Proc. of The 38th
Annual Conference of the RSJ, 2I3-03, 2020. (in Japanese).
11. K. Ushimaru et al., Experimental Consideration onRequirements Specification of Haptic Device that PresentsSensation Corresponding to Palm on Back of Hand forAuthors Introduction
Dr. Noritaka Sato
He is an assistant professor at Nagoya
Institute of Technology. He received
his Ph.D degree of Engineering fromtheUniversityofElectroCommunications in 2009. His
research interests include humanrobot interaction for rescue robots
and rehabilitation-assist robots
Mr. Kyosuke Ushimaru
He received his M.S. degree inEngineering in 2022 from Nagoya
Institute of Technology. His researchinterests include virtual reality, haptic
interface, and rescue robots.

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Prof. Yoshifumi Morita
He is a professor at Department ofElectricalandMechanicalEngineering, Graduate School ofEngineering, Nagoya Institute ofTechnology, Japan. His researchinterests include robot motion
control, support control forhuman-machine
cooperative
system, and rehabilitation support
robot.

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