Modulating Fine Roughness Perception of Virtual Textured Surfaces using Pseudo-haptic Effect @ IEEE VR 2019 -Y. Ujitoko (Hitachi, Ltd.) -Y. Ban (The University of Tokyo) -K. Hirota (The University of Electro-Communications)

1. Modulating Fine Roughness Perception of
Vibrotactile Textured Surface
using Pseudo-haptic Effect
Y. Ujitoko
Y. Ban
K. Hirota
Hitachi, Ltd.
The University of Tokyo
The University of Electro-Communications
IEEE VR 2019 OSAKA

2. Proposed Method
• visual oscillation enhances vibrotactile roughness perception
Brief Summary
Findings
1. visual oscillation enhances roughness at high probability
2. as visual oscillation’s size is larger, users feel texture rougher

3. Background
Wide-spread vibrators can provide virtual
vibrotactile surface feeling (e.g. roughness)
Vibrators in smartphones
How to Design Vibrotactile Surface Experience
is becoming important.
Vibrators in
touchpen or touchpad

4. Software-side
Design
Hardware-side
Design
Vibrotactile Surface Design
Design Process Example
Vibrator Design
Case Design
Vibration Design Experience
Test

5. Software-side
Design
Hardware-side
Design
Vibrotactile Surface Design
Design Process Example
Vibrator Design
Case Design
Hardware constraints
narrow vibration design space
■ Controllability
Frequency
Amplitude
■ Latency
■ Mechanical
coupling between
case and finger
■ Mass
Vibration Design Experience
Test

6. Software-side
Design
Hardware-side
Design
Vibrotactile Surface Design
Design Process Example
Vibrator Design
Case Design
■ Controllability
Frequency
Amplitude
■ Latency
■ Mechanical
coupling between
case and finger
■ Mass
Vibration Design
presents a variety of roughness feeling
with limited kind of vibration
Our Pseudo-haptic
based Vibrotactile
Display
Hardware constraints
narrow vibration design space

7. Related work: Pseudo-haptics
• Pseudo-haptics [Lécuyer 2001]
• Illusory haptic feeling when the pointer speed changes

8. Related work: Pseudo-haptics with vibration
However, there is no study targeting on roughness
Simulating vibrotactile stiffness [Hachisu et al. 2011]

9. Pattern 1 Pattern 2
Concept
visual oscillation Enabledvisual oscillation Disabled
• Enhancing vibrotactile roughness by visual oscillation
Same
Vibrotactile
stimulus
Different
Visual
stimulus
Square wave vibration
Surface felt rougher?
Square wave vibrationHAPTICTM
Reactor
Amplifier
Conductive nib Conductive sheet

10. Pattern 1 Pattern 2
Concept
visual oscillation Enabledvisual oscillation Disabled
• Enhancing vibrotactile roughness by visual oscillation
Same
Vibrotactile
stimulus
Different
Visual
stimulus
Square wave vibration
Surface felt rougher?
Square wave vibrationHAPTICTM
Reactor
Amplifier
Conductive nib Conductive sheet
We conducted 2 user studies to test hypotheses:
H1
H2
Visual oscillation could enhance vibrotactile roughness
Larger size of visual oscillation makes users feel surface
rougher

11. User Study 1
• Participants compared vibrotactile roughness between 2 areas
• Vibrotactile stimulus are the same
• Visual oscillation was enabled in one area and
was disabled on the other area
H1 Visual oscillation could enhance vibrotactile roughness
• Objective is to test hypothesis
Area 1 Area 2
visual oscillation Enabledvisual oscillation Disabled
Same
Vibrotactile
stimulus
Different
Visual
stimulus
Square wave vibration
Surface felt more rough?
Square wave vibrationHAPTICTM
Reactor
Amplifier
Conductive nib Conductive sheet

12. Trials in User Task

13. User Study 1
• Used Vibrator
HAPTICTM
Reactor
Amplifier
Conductive nib Conductive sheet
• Experimental
Appearance

14. User Study 1
virtual textured surface is controlled by visual oscillation is controlled by

15. User Study 1: Results
In all conditions, participants felt vibrotactile texture rougher
with visual oscillation (evidenced by Chi-square fitness test)
3
(low frequency)
1.5
2
2.5
3
1.5
2
2.5
3
1.5
2
2.5
3
83
78
1
1
1
85
84
67
84
86
87
75
84
86
85
43.6
31.4
49.0
46.2
11.6
46.2
51.8
54.8
25.0
46.2
51.8
49.0
4.1e-11
2.1e-8
2.6e-12
1.1e-11
6.7e-4
1.1e-11
6.0e-13
1.4e-13
5.7e-7
1.1e-11
6.0e-13
2.6e-12
5
(mid frequency)
7
(high frequency)
signal frequency
parameter
λ: α: visual oscillation
parameter of
oscillatory area
The # of oscillatory
area was selected df χ2
p

16. User Study 2
• Objective is to test hypothesis
as size of oscillation is larger,
felt vibrotactile roughness is larger.
H2
• Participants adjusted amplitude of vibration of area without visual oscillation
so that the felt roughness will be the same.
Area 1 Area 2
visual oscillation Enabledvisual oscillation Disabled
Vibrotactile
stimulus
Different
Visual
stimulus
Square wave vibration
After the adjustment, same roughness should be felt
Square wave vibrationHAPTICTM
Reactor
Amplifier
Conductive nib Conductive sheet
Amplitude
(adjustment variable)
Fixed
amplitude

17. User Study 2
Participants adjusted the perceptual roughness
by changing amplitude of vibration of area without visual oscillation

18. User Study 2: Results
When size of visual oscillation was larger,
users felt as if the vibrational amplitude was larger
→It suggests the fine-tunability of vibration using only visual info.
size of visual oscillation
The amount of
adjusted amplitude
=effect of visual oscillation

19. • Need for pointer
Limitation

20. Proposed Method
• visual oscillation enhances vibrotactile roughness perception
Conclusion
Findings
1. visual oscillation enhances roughness at high probability
2. as visual oscillation’s size is larger, users feel texture rougher

21. Modulating Fine Roughness Perception of
Vibrotactile Textured Surface
using Pseudo-haptic Effect
Y. Ujitoko
Y. Ban
K. Hirota
Hitachi, Ltd.
The University of Tokyo
The University of Electro-Communications
IEEE VR 2019 OSAKA