2013 IEEE International Conference on Systems, Man, and Cybernetics

Toward augmented reality of textures: Vibrotactile
high-frequency stimuli mask texture perception to berougher or smoother?
Shuhei Asano, Shogo Okamoto, and Yoji Yamada
Department of Mechanical Science and Engineering,
Graduate School of Engineering, Nagoya University, Nagoya, Japan.

Augmented reality can also be applied to percepts of tactile
textures. For example, the perceived roughness of material surfaces is increased by noisy sound cues that synchronize hand
exploratory motions [8]. Increase in the perceived roughnessof materials can also be achieved by applying vibrotactile
stimuli to materials [9]. A vibrotactile display mounted on
nails [10] can be potentially used for similar purposes. Thesestudies have outlined the augmented reality techniques forincreasing roughness percepts of material surfaces. However,techniques to reduce the perceived roughness have yet to bereported. Once such techniques are realized, augmented reality
techniques will be able to both increase and decrease thetactile roughness of textures. To aid in the development of
the underlying technology for augmented reality of texture
perception, this study investigates the effects of vibrotactile
stimuli on the reduction of perceived roughness of material
surfaces.
Because aurally communicating how a texture feels isdifficult, a system that allows us to experience tactile textures
will potentially enhance the process of designing the texturesof products. Fig. 1 shows one possible application of thistechnology in the field of industrial design. We imagine that
two industrial designers discuss the textures of cloths thatare used to cover a certain product. They each are holding
a sample of the cloth, and one of them is attempting to deliver
his desires. However, aurally communicating these desires isdifficult. Augmented reality technology for textures will beof potential benefit in these situations. The two designers canadjust and share tactile experiences of the textures using theaugmented reality tool. Preparing a plethora of cloth samples
is also a practical solution; however, the augmented reality
technology enables users to interpolate those samples. Suchsharing of tactile experiences is more effective when the twoparties are unable to meet in person or talk by phone.

Abstract—Augmented reality technology realizes variable sensory feedback while maintaining a high perceptual quality bysuperposing real and virtual stimuli. In this research, we experimentally verified whether the masking effects of high-frequency
vibrotactile stimulation on fingers is applicable to augmented
reality of the tactile texture of materials. A vibrotactile stimulator
was worn on a finger (ring-vibrating condition) or mounted
on materials (material-vibrating condition). We investigated theeffect of vibratory stimuli on perception of sand-paper roughness
under these two conditions. Under both conditions, participants’performances to discriminate the roughness diminished becauseof the masking effects of the high-frequency vibratory stimuli(experiment 1). Subsequently, we specified how the masking
effects influenced the perceived roughness using Scheffe’s paired
comparison. For the ring-vibrating condition, as accelerationsof the vibrotactile stimuli increased, all participants reported adecrease in the perceived roughness of the sand-paper. For thematerial-vibrating condition, the roughness percepts increased or
decreased depending on the individual (experiment 2). Althoughboth implementation methods affect roughness perception, thering-vibrating condition is recommended for augmented realityof tactile textures because it can steadily control the decrease inperceived roughness of touched materials.
Index Terms—Tactile display, Vibration stimulus, Haptics

I. I NTRODUCTION
Augmented or mixed reality is a concept that was originallydeveloped and has been actively studied for auditory and visualsensations, however, techniques for haptic sensations havealso been developed, recently. For example, some researchgroups demonstrated that force feedback change the perceptsof viscoelasticity of a soft material when touched using haptic
displays [1], [2]. The manipulation of perceived shapes oftouched objects has also been attempted [3]. Robotic surgery
is potentially one of the promising areas where augmented or
mixed reality of haptic sensations could be advantageous [4],[5], [6], [7]. A clear benefit of the introduction of augmented
reality to haptics is the improvement of stimulus quality.
Unlike audio and visual displays, the quality of haptic feedback
represented by haptic stimulators remains unsatisfactory forcommercial use. However, augmented reality allows us tocombine complicated haptic experiences due to real physics
and variable force feedback by haptic displays. The haptic
properties of objects can be partly controllable while maintaining quality feedback from real objects.
978-1-4799-0652-9/13 $31.00 © 2013 IEEE
DOI 10.1109/SMC.2013.93a) Objectives: As shown in Figs. 2 and 3, the implimentation of augmented reality is classified into two types
according to whether the sensory display is installed on the
body or in the environment. In the present research, in one
case, users wear a vibrotactile display on their finger, and in
the other case, the material being touched is mounted on a
vibrotactile display. Based on the principles described later,these two types of approaches potentially have different capa510

Designer

DesignerI meansmoothertexture.

vibrotactile stimuli. In particular, receptor units known as FAII
readily adapt to the stimuli, and humans feel materials as
being less rough or smooth while the adaptation remains ineffect [11]. This situation is similar to what we experience
when our hands are chilled and less sensitive to textures in
the winter. FAII units are specifically masked by the frequency
around 250 Hz. These units are selectively influenced when thevibrotactile masking stimuli are small, however, as the stimuli
becomes larger, other receptor units are also adapted [12].
Because of masking effects, the capability to detect vibrotactile
signals is significantly diminished [12]. These facts suggestthat using a masking effect caused by vibrotactile stimuli, willdiminish the material roughness perceived by humans.
p(t) and a(t) denote the magnitude of roughness perceived
by humans and the activity level of cutaneous receptors at timet, respectively. a(t) is a monotonically increasing function of
the mechanical deformation or stimuli applied to a finger pad.
The activity of the receptors increase with external stimuli.
This model is sound as long as there is no significant adaptation
due to long-term exposure to stimuli. In the later experiments,
in order to prevent such long-term exposure, the participants’
exploratory behaviors toward materials are controlled. It is
speculated that human roughness perception is characterized
by the distinction in receptor’s activity levels between before
and after touching materials. Hence, roughness experienced bytouching a material at t is described as

How much?
I can adjust
the smoothness.

Vibrotactile
stimulator
for augmented
reality
Material

Controller ofvibrotactile
stimulatorYes.

I see.

This one!

Fig. 1. Application image of augmented reality technology for tactile textures

Touch
Not - touch

Time

Constant On
vibration Off

Material

More vibration leads tosmaller perceived roughness. Receptor’s
activityp(t) = f (a(t) − a(t0 ))t0Fig. 2.

t1

where t0 is the moment before the material is touched. Function f (·) links the receptor activities and roughness perception,and the following discussion is not restricted as long as it is amonotonically increasing function.
c) Hypothesis 1: Ring vibrotactile stimulator reduces
the perceived roughness of materials: Here, we consider thecase in which a vibrotactile stimulator is worn on a finger, as
shown in Fig. 2. At t0 , there is neither vibratory stimuli nor
contact between the finger and material. At t1 , the ring-type
vibrotactile stimulator produces constant vibratory stimuli.
During this period, a(t1 ) > a(t0 ) because receptor’s activity
is increased by the stimuli. At t2 , the finger contacts andbegins exploring the material. The receptor activity then further
increases, and a(t2 ) > a(t1 ). The perceived roughness isexpressed byp(t2 ) = f (a(t2 ) − a(t1 )).
(2)

t2

Ring-vibrating caseTouch
Not - touchMaterial
More vibration leads tosmaller perceived roughnessorlarger perceived roughness?
Fig. 3.

Time

Constant On
vibration Off
Receptor’s
activity
t0

t1

(1)

t2

Material-vibrating case

The receptors have a maximum activity level: a(t) < amax .
Therefore, when a(t1 ) or a(t2 ) reaches or is close to thislevel, the roughness is barely perceived when touching roughmaterials. For example, with stimuli large enough to saturate
the activity level, a(t1 ) = amax , and a(t2 ) = a(t1 ). Perceived
roughness then becomes zero as p(t2 ) = f (0|a(t1 ), a(t2 ) =amax ). This speculation is consistent with the masking effectpreviously described. Based on these ideas, the first hypothesisis that when the masking effect from the ring-type vibrotactile
stimulator prevails, human perception of the material’s roughness is diminished.

bilities, hence, this study experimentally investigates whether
one or both can effectively decrease the roughness perceptsof material surfaces. We then recommend one approach as asuitable augmented reality technique for tactile textures.
b) Principles: When a human finger contacts an object’s
surfaces, the finger pad deforms. Along with this deformation,
cutaneous receptors are activated, and resultant nervous signals
reach the central nervous system and yield a sense of thematerial’s surface. These receptors are masked or adapted by

511

50 mmd) Hypothesis 2-1: Vibration applied to materials increases the perceived roughness of materials: Here, we consider the case in which material is mounted on a vibrotactile
stimulator, as shown in Fig. 3. At t0 , the finger does not contact
the material. At t2 , the finger contacts and begins exploring
the vibrating material. The perceived roughness is expressedbyp(t2 ) = f (a(t2 ) − a(t0 )).
(3)Z

Sandpaper

X
Direction of vib.

Suppose that a (t2 ) denotes the receptors’ activity caused
by touching the material without vibratory stimuli, a(t2 ) islarger than a (t2 ) because of the effects of vibratory stimuli.
Accordingly, p(t2 ) is larger than p (t2 ), which is the roughness
percept of material without vibration. Thus, we hypothesizedthat the vibrotactile stimuli applied to the material increase theperceived roughness of the material when touched.
e) Hypothesis 2-2: Vibration applied to materials reduces the perceived roughness of the materials: It is possiblethat vibrating the material decreases the perceived roughnessof the material. The material-vibrating condition may affectthe percepts the way the ring-vibrating condition does. Hence,
based on the same interpretation as hypothesis 1, the materialvibrating condition may affect perceived roughness.
As described above, this study experimentally tests thesepartly contradicting hypotheses. It should be noted that wevalue the experimental evidence to establish the augmented
reality techniques as much as or more than the underlying
perceptual mechanisms.
As a third hypothesis, the vibrotactile stimuli may not affectthe roughness perception of materials, mainly because thevibratory stimuli are provided independently from the material
properties and human hand motions. However, as shown inexperiment 1 later, this idea does not hold.

Acrylic plate
Restraint bar
Coil
MagnetAluminum baseFig. 4. Schematic representation of material-type vibrotactile display basedon voice coil motor

Recoil-type
actuator

Fabric band

Fig. 5. Picture of index finger mounted with a ring-type vibrotactile stimulator

bands as shown in Fig. 5. A tactile stimulus was presented
by vibrating the actuator in the longitudinal direction of thefinger. A current driver (Copley Controls, ACJ-090-03, MA)
and function generator were also used to control the vibrationsof the actuator.

II. E XPERIMENTAL S ETUP
We used two types of vibrotactile stimulators. The first one
vibrated the textured surfaces attached on it. The second one
was worn on the human finger and vibrated the finger itself.

III. E XPERIMENT 1: M ASKING EFFECTS OF
HIGH - FREQUENCY VIBROTACTILE STIMULI ON ROUGHNESSDISCRIMINATION

A. Vibrotactile stimuli imposed to materials

A. Objective

The first one presented a tactile stimulus vibration to material by driving a voice coil motor (X-1740, Aoyama Special
Steel Co. Ltd., maximum force: 2.42 N) as an actuator. Fig. 4
shows a schematic representation of this vibrotactile apparatus.
The material, acrylic plate, and coil were combined. These
three parts of the display are colored, and base-restraining bar,magnet and aluminum are displayed transparent. The vibrating
direction was perpendicular (Z axis) to the plane of the tracing
movement (X-Y plane). The textured surfaces were replaceable. The motor was driven using a current driver (Copley
Controls, ACJ-090-03, MA) and function generator.

As described previously, in order to reject the third hypothesis before testing hypotheses 1 and 2, we confirm theeffects of vibrotactile stimuli on roughness perception underboth material- and ring-vibrating conditions. For this purpose,experiment 1 tests the masking effects of vibrotactile stimuli
using roughness discrimination tasks.
B. Tasks and participants
We invited five male volunteers from the authors’ laboratory
to participate in the study. The authors did not participate inany of the experiments. The participants were blindfolded,
wore headphones, and listened to pink noise to mask thesounds generated by the voice coil motors. The participants
compared two types of sand-paper and selected the rougher
one in the following two tasks.

B. Ring-type vibrotactile stimulator
The second device was a ring-type vibrotactile stimulator.
Participants were fitted with a small recoil-type actuator (Haptuator mark II, A. Berrezag at UPMC, France) on the back of
the index finger between the DIP and PIP joints using adhesive

512f) Task 1: Material-vibrating condition: Participants
compared two types of sand-paper to which vibratory stimuli
were applied. We restricted the participants’ exploratory hand
movements to two reciprocations for each type of sand-paper
to prevent adaptation. As a result, it took as long as 2–
3 s to scan one sheet of sand-paper. As a control condition,
the participants also compared the two types of sand-papers
without vibrating stimuli. In total, twenty trials were conducted
for each participant, with ten trials for each condition. There
was a 10 s rest between trials. The two conditions wererandomly switched.
g) Task 2: Ring-vibrating condition: Participants wore
the ring-type vibrotactile stimulator on their index finger andcompared two sheets of sand-paper. To prevent adaptation to
the vibrotactile stimuli, they were instructed to commence theexploration as soon as the vibration started. Similarly to task
1, the number of reciprocatory hand motions was limited totwo. Therefore, the time required for one trial or comparison
was at most 5 s. The participants also compared two sheets ofsand-paper with no vibrotactile stimuli as a control condition.
Twenty trials, ten for each condition, were conducted for eachparticipant in a random order.

]
%
[
s
r
e
w
s
n
a
t
c
e
r
r
o
c
f
o
e
g
a
t
n
e
c
r
e
P

**

**

100
80
)
0
0
0
2
#
>
0
0
5
1
#
(

60
40
20
0
No

Material-

No

Ring-

vibration

vibratingvibration

vibratingcontrolcondition

controlcondition

condition

condition

Fig. 6. Answer ratios at which participants selected #1500 as rougher than#2000, with and without vibrotactile stimuli. ∗∗ indicates a significance levelof 1%.

From the analysis, we concluded that the application of highfrequency stimuli significantly decreased the percentage ofcorrect answers (F0 (1, 8) = 22.0, p = 1.561 × 10−3 ).
The two graphs on the right in Fig. 6 are the results
for the ring-vibrating condition. The percentage of correct
answers was 88% ± 9.8% when comparing the sand-paper
without vibration. While the percentage of the correct answers
was 56% ± 12% when using the ring-vibrating condition.
From the analysis, we concluded that the application of highfrequency stimuli significantly decreased the percentage ofcorrect answers (F0 (1, 8) = 17.07, p = 3.29 × 10−3 ).
In each of the results, the correct answer rate for conditions
with vibration was lower than that for the control conditions.
Furthermore, these answer ratios were near chance level, whichindicates that the participants could not discriminate the two
types of sand-paper when vibrations were applied to fingers.
Hence, the masking effects on roughness perception wereconfirmed for both the material- and ring-vibrating conditions.

C. Stimuli
We used two types of sand-paper (50 × 50 mm) of#1500 and #2000 roughness. The frequency of vibrations
was set to 250 Hz for both the material- and ring-vibrating
conditions. For the material-vibrating condition, the peak-topeak acceleration of the vibrotactile stimulus was ±3.44 m/s2 ,which corresponded to an amplitude of ±0.697 μm. The
peak-to-peak acceleration was measured by an accelerometer(Analog Devices Corp. ADXL335, MA) attached to the acrylic
plate shown in Fig. 4. During the measurement, the finger
was kept on the plate with the approximate load of 1.5 N.
This load is comparable with the one observed during the
exploratory tasks. For the ring-vibrating condition, the peak-topeak acceleration of the vibrotactile stimulus was ±39.3 m/s2 ,which corresponded to an amplitude of ±15.93 μm. The
accelerometer was glued to the ring-type vibrotactile stimulator
and measured these values. Similar to the material-vibrating
condition, the finger was in contact with the material during
the measurement.

IV. E XPERIMENT 2: S UBJECTIVE RATINGS OF SAND - PAPER
MASKED BY VIBROTACTILE STIMULI

A. Objective
Using roughness rating tasks, experiment 2 investigates
whether vibrotactile stimuli decrease (hypotheses 1 and 2-2)
or increase (hypotheses 2-1) the material roughness perceived
by participants.

D. Results
Fig. 6 shows the results of experiment 1. The percentagesof correct answers illustrated on the vertical axis are means
and standard deviations for five participants. The two graphson the left are the results for the material-vibrating condition.
The percentage of the correct answers was 82% ± 9.8% whencomparing the sand-paper without vibration. The percentage
of correct answers was 38% ± 16% when using the materialvibrating condition. The statistical relevance of the differences
between the percentage of correct answers was tested using
one-way analysis of variance. The presence of vibrotactile
stimuli or the lack of it was used as a factor for the analysis.

B. Tasks and participants
The experiment was performed by the method of Scheffe’s
paired comparison. The participants compared the surface
roughness of paired stimuli that were a sheet of sand-paperwith constant vibrations of different amplitude levels applied
to it or their finger. Sand-paper without applied vibrations was
also included in the stimuli set. Participants responded with
one of four answers: much rougher, rougher, slightly rougher,
and the same. To prevent adaptation, the movement of the513

TABLE I
P ERCEIVED ROUGHNESS VALUES UNDER MATERIAL - VIBRATING
CONDITION . L ARGER SCORES INDICATE ROUGHER PERCEPTS .

index finger was limited to two reciprocations for each stimulus. The five participants from experiment 1 participated inexperiment 2. They performed comparisons under the material
and ring vibrating conditions. Two of the five participants
tested the material-vibrating conditions first, followed by thering-vibrating conditions. The other participants tested theconditions in the opposite order. Similarly to experiment 1,
aural and visual stimuli were masked during the tasks.

P1
P2
P3
Ave.
P4
P5
Ave.

G1

C. Material
G2

The material was a sheet of sand-paper (#500). Basically,
the participants compared this sand-paper under different vibration levels, and our main interest was in the effects ofvibrations on ratings of perceived roughness. However, we also
used #600 with no vibrations such that the participants would
not easily guess that a single type of sand-paper was used forall stimuli, and only the vibration levels varied. According to
introspective reports after the experiments, all the participants
were unaware that most of the stimuli were based on sandpaper of a single roughness grade.

#500
no
vib.
-12
-3
3
-4
3
15
9

#500
weak
vib.
-2
6
6
3.3
-10
-2
-6

Stimuli#500
middle
vib.
2
7
3
4
-9
0
-4.5

#500
strong
vib.
-2
12
4
4.6
-12
1
-5.5

#600
no
vib.
-14
-9
-6
-9.6
-2
5
1.5

TABLE IIP ERCEIVED ROUGHNESS VALUES UNDER RING - VIBRATING CONDITION .
L ARGER SCORES INDICATE ROUGHER PERCEPTS .

P1
P2
P3
P4
P5
Ave.

D. Vibration
Material-vibrating condition: Three levels of vibrations at
250 Hz were prepared. They were 1.68, 1.72, and 2.17 m/s2 inpeak-to-peak acceleration. These values corresponded to peakto-peak amplitudes of 0.68, 0.70, and 0.88 μm, respectively. In
total, five types of stimuli were compared. They were #500
and #600 with no vibration and #500 with three vibrationlevels. Ten pairs formed from the five stimuli were tested with
two repetitions for each pair. For the second trial of each pair,the order of presentation of paired stimuli was inverted. Hence,twenty trials were conducted for each participants.
Ring-vibrating condition: The peak-to-peak accelerationsof three vibration levels were 30.11, 39.32, and 48.53 m/s2 .
These values corresponded to the peak-to-peak amplitudes of
12.16, 15.94, and 19.67 μm, respectively. As for the materialvibrating condition, five types of stimuli were used. They
included #500 and #600 without vibration and #500 with theabove three levels of vibrations. Twenty trials were performed
similarly to those for the material-vibrating conditions.

#500
no vib.
13
21
6
12
10
12.4

#500
weak vib.
-7
-1
-4
0
-1
-2.6

Stimuli#500
middle vib.
-6
-2
-10
-4
-6
-5.6

#500
strong vib.
-8
-7
-8
-8
-7
-7.6

#600
no vib.
14
10
7
6
10
9.4

As shown in Fig. 7 and Table II, in the ring-vibrating
condition, the most participants agreed that the perceived
roughness monotonically decreased in accordance with theacceleration of the vibrotactile stimuli.
V. D ISCUSSION AND C ONCLUSION
To aid in the development of augmented reality technology
for tactile texture perception, we examined the effect of
decreasing the perceived roughness of the material surface
using constant high-frequency vibrotactile stimuli (250 Hz).
We prepared two methods for presenting vibrotactile stimuli toparticipants: ring- and material-vibrating conditions. Under the
ring-vibrating condition, a vibrotactile stimulator worn on the

e
r
o
c
s
s
s
e
n
h
g
u
o
r
d
e
v
i
e
c
r
e
P

E. Results
We assigned scores ranging from 3 to 0 to the four answers,
with 3 being “much rougher” and 0 being “the same.” Thescores from each stimulus were then summed. Tables I and II
show the averaged scores for each stimulus. By definition, thelarger scores represent larger perceived roughness. The smalleror negative scores represent smoother percepts.
For both conditions, #500 with no vibration was perceived
rougher than #600 with no vibration, which indicates the consistency of the experiments. In the material-vibrating condition(Table I), three participants responded the perceived roughness
increased (Group 1), and the others responded that perceived
roughness decreased (Group 2) as the magnitudes of vibration
increased. In other words, the effect on the perceived roughness
was dependent on the individual.

20
15
10
5
0
-5
-10

)
r
e
h
g
u
o
r
e
h
t
,
r
e
h
g
i
h
e
h
T
(

No vib.
Weak
Vib. Middle
Vib.

0StrongVib.
30.11 39.32 48.53

Stimuli Based on the acceleration (m/s2)
Fig. 7. The effects of vibrotactile stimuli on perceived roughness of sandpaper (#500) under ring-vibrating condition.

514

index finger vibrated the finger. Under the material-vibrating
condition, material mounted on voice coil motor was vibrated.
These two conditions are considered typical configurations foraugmented reality.
In experiment 1, we presented a high-frequency vibrotactile
stimulus to the participants. It was difficult for them to discriminate the perceived roughness of sand-paper, nevertheless, they
could do so under the non-vibrating condition. Hence, in either
vibrating condition, the tactile vibration stimulus affected theperceived roughness. These results did not support the third
hypothesis that presenting constant vibrotactile stimuli to thefinger does not affect the perceived roughness of a material.
In experiment 2, we investigated whether the perceived
roughness of sand-paper increases or decreases under the two
types of vibrating conditions using roughness rating tasks toverify the hypotheses 1 and 2. For the ring-vibrating condition,
as the acceleration of the vibration increased, the perceived
roughness of sand-paper decreased for all participants. For
hypothesis 1, the perceived roughness of the materials wasdiminished by the masking effect of the ring-vibrating condition.
For the material-vibrating condition, as the acceleration of
the vibration increased, three of the five participants reported
an increase in the perceived roughness (consistent with hypothesis 2-1), and the others reported a decrease in the perceived
roughness (consistent with hypothesis 2-2). Thus, individual
differences in the effect on the perceived roughness wereobserved under the material-vibrating condition.
One of the reasons that individual differences occurred may
be the difference in the speed at which participants traced thesand-paper. Normally, the tracing speed leads to differences invibratory frequency occurring at the skin, and it contributes
to the perceived roughness of fine textures. As the tracing
speed increases, the frequency of the skin vibration increases.
However, the stimulator presents a constant stimulus at 250 Hz,
and it does not depend on the speed at which the sand-paper
is traced. In this case, the participant whose tracing speed isrelatively slow feels a higher spatial frequency of the sandpaper surface. As the spatial frequency increases or the spatial
wavelength of the sample surface decreases, the perceived
roughness decreases [13], [14]. Consequently, the differencein tracing speed might lead to these reported individual differences. Unfortunately, because we were unable to record the
tracing movements of the participants, we cannot compare theresults between tracing speeds and reported roughness.
Another possibility is that differences in the way to trace thesand-paper led to individual differences. It is likely to establish
the interpretation of the hypothesis 2-1, when tracing smoothly
the sand-paper. On the other hand, in the case of the hand
movement is not smooth and intermitted, participants felt thevibrotactile stimuli in the material-vibrating condition despite
their hand hardly moving. Because this is closer to the ringvibrating condition, the interpretation of the hypothesis 2-2 willbe established. Consequently, there may be individual differences in the material-vibrating condition because of differencesin the way to trace the sand-paper of participants.

Whether either reason above is correct, a constrained tracing
method is necessary to decrease the perceived roughness
for the material-vibrating condition. It is not preferable foruser to demand such a limitation in augmented reality technique. In addition, individual differences observed under thematerial-vibrating condition were not confirmed under the
ring-vibrating condition. Thus, the ring-vibrating condition isrecommended as an augmented reality technique to decrease
the perceived roughness of materials.
ACKNOWLEDGMENT
We thank Mr. Amir Berrezag at ISIR in UPMC for discussing the research. This study was supported in part supported by Shitsukan (23135514 and 25135717).
R EFERENCES[1] S. Jeon, S. Choi, and M. Harders, “Rendering virtual tumors in realtissue mock-ups using haptic augmented reality,” IEEE Transactions on
Haptics, vol. 5, no. 1, pp. 77–84, 2012.
[2] Y. Kurita, A. Ikeda, K. Nagata, and T. Ogasawara, “Haptic augmentation
utilizing the reaction force of a base object,” Journal of Robotics andMechatronics, vol. 20, no. 1, pp. 72–79, 2013.
[3] Y. Ban, T. Narumi, T. Tanikawa, and M. Hirose, “Modifying an identified
size of objects handled with two fingers using pseudo-haptic effects,”
Proceeding of the Joint Virtual Reality Conference of ICAT - EGVE EuroVR EG Symposium, pp. 1–8, 2012.
[4] G. Brandt, A. Zimolong, L. Carrat, P. Merloz, H.-W. Staudte, S. Lavallee,
K. Radermacher, and G. Rau, “Crigos: a compact robot for image-guided
orthopedic surgery,” IEEE Transactions on Information Technology inBiomedicine, vol. 3, pp. 252–260, 1999.
[5] M. Jakopec, S. J. Harris, F. R. y Baena, P. Gomes, J. Cobb, and B. L.
Davies, “The first clinical application of a “hands-on” robotic knee
surgery system,” Computer Aided Surgery, vol. 6, no. 6, pp. 329–339,
2001.
[6] L. Moody, A. Waterworth, A. D. McCarthy, P. J. Harley, and R. H. Smallwood, “The feasibility of a mixed reality surgical training environment,”
Virtual Reality, vol. 12, pp. 77–86, 2008.
[7] V. Francoise, A. Sahbani, and G. Morel, “A comanipulation device fororthopedic surgery that generates geometrical constraints with real-timeregistration on moving bones,” Proceedings of the IEEE International
Conference on Robotics and Biomimetics, pp. 38–43, 2011.
[8] Y. Suzuki and Y. Kawachi, “Modulation of tactile motion by intraand inter-modal manipulation,” Proceedings of the IEEE World Haptics
Conference, pp. 49–52, 2011.
[9] S. Asano, S. Okamoto, Y. Matsuura, H. Nagano, and Y. Yamada,“Vibrotactile display approach that modifies roughness sensations of realtextures,” Proceedings of the 2012 IEEE International Symposium on
Robot and Human Interactive Communication, pp. 1001–1006, 2012.
[10] M. Niwa, T. Nozaki, T. Maeda, and H. Ando, “Fingernail-mounted
display of attraction force and texture,” Proceeding of the EuroHaptics,
pp. 3–8, 2010.
[11] G. A. Gescheider, S. J. Bolanowski, T. G. Greenfield, and K. E.
Brunette, “Perception of the tactile texture of raised-dot patterns: A
multidimensional analysis,” Somatosensory and Motor Research, vol. 22,
no. 3, pp. 127–140, 2005.
[12] G. A. Gescheider, R. T. Verrillo, and C. L. van Doren, “Predictionof vibrotactile masking ffunctions,” Journal of Acoustical Society ofAmerica, vol. 72, pp. 1421–1426, 1982.
[13] C. E. Connor, S. S. Hsiao, J. R. Phillips, and K. O. Johnson, “Tactile
roughness: Neural codes that account fo psychophysical magnitude
estimates,” Journal of Neuroscience, vol. 10, pp. 3823–3836, 1990.
[14] E. M. Meftah, L. Belingard, and C. E. Chapman, “Relative effects ofthe spatial and temporal characteristics of scanned surfaces on humanperception of tactile roughness using passive touch,” Experimental Brain
Research, vol. 132, pp. 351–369, 2000.

515