The document presents a research project focused on converting soft objects into touch input devices using photoreflectivity measurements. Key contributions include a sensor module that measures cotton density, a multi-sensor system for determining touch points, and various application examples such as remote controllers and interactive robots. The limitations of the sensor include size and battery life, but it shows promise for innovative applications in home appliances and gaming.

1. Detecting Shape Deformation of Soft Objects
Using Directional Photoreflectivity Measurement
Keio University / The University of Tokyo
JST ERATO IGARASHI Design Interface Project
Yuta Sugiura, Gota Kakehi, Anusha Withana, Calista Lee, Daisuke Sakamoto,
Maki Sugimoto, Masahiko Inami and Takeo Igarashi

2. Converting Soft Objects
into Interfaces
• Soft objects are common in the home
• This sensor converts them into touch input
devices

4. Using this, we can...
• Use physical actions to control home
appliances and game characters

5. Contributions
1) Measurement of cotton density
using photoreflectors
2) Packaged sensor module
3) Multi-sensor system that
determines the point of contact
4) Example applications

6. Contributions
1) Measurement of cotton density
using photoreflectors
2) Packaged sensor module
3) Multi-sensor system that
determines the point of contact
4) Example applications

7. Measuring the Density of Cotton
• Using photoreflectors
– Infra-red LED
– photo transistor
Photoreflector
Cotton Emitted IR
In low density cotton In high density cotton

8. • フォトリフレクタで綿の密度変化を計測
– ダイナミックな変化量を計測
– 非接触型の計測
– 安価，小型

9. Comparison of Sensing Method
• Sensors attached on the surface (Yagi et
al. SIGGRAPH ’11)
– The soft properties is changed
• Pressure Sensor
– Measuring small area density changes
only
• Photoreflector (Our approach)
– Able to measure wide range of density
changes
Photoreflector

10. Measurement Experiment
• Polyester cotton
• Reduce the height of the lid
by 2mm each time
• Raise the lid
0
1
2
3
4
0.007 0.01 0.013 0.016 0.019 0.022 0.025 0.028
Voltage(V)
Material Density (g/cm3)
Polyester Co on-Push
Polyester Co on-Pull
Push
Pull
Cover
Soft Material
Photoreflector
(Photo Sensor and IR LED)
146 [mm]
104 [mm]

11. Contributions
1) Measurement of cotton density
using photoreflectors
2) Packaged sensor module
3) Multi-sensor system that
determines the point of contact
4) Example applications

12. Sensor Module
• 6 photoreflectors
arranged orthogonally
• Palm-sized
• Each module works
independently
Li-Po battery
ZigBee
microcontroller
photoreflector

13. Contributions
1) Measurement of cotton density
using photoreflectors
2) Packaged sensor module
3) Multi-sensor system that
determines the point of contact
4) Example applications

14. Multi-Sensor System
• Multiple sensors work together to interpolate
the position of touch.

15. Interpolation to Determine Position
• Insert Multiple sensor modules
• Sum of 6 photoreflector values in one
module

16. Calibration of the Sensor's Location
1) User inputs the location directly
2) Use an infra-red camera

17. Contributions
1) Measurement of cotton density
using photoreflectors
2) Packaged sensor module
3) Multi-sensor system that
determines the point of contact
4) Example applications

18. Game Application
• Using different actions to control the character

19. Remote Controller for Home Media
• A cushion as a remote controller

20. Entertainment Candy Floss
• Attach a photoreflector to the top of the stick
• The sound changes according to the density of the
candy floss.

21. Soft Interactive Robot
• Its eyes look towards the human touch

22. Other Possible Applications
• Embedded into a down jacket
– Music player controller
• Embedded into beds and pillows
– Senses the condition of the
sleeping person

23. Limitations
• Sensor module is large
• Battery life is not long
(3 hours)
• Need to cut open
Tradeoff

24. Related Research
PUYO-CON,
Hiramatsu et al.
Digital Foam,
Smith et al.
Balance Ball Interface,
Yasumoto et al.
Photoelastictouch,
Sato et al.

25. Conclusion: Converting Soft
Objects into Touch Devices
• Measurement of cotton density using
photoreflectors
• Packaged sensor module
• Multi-sensor system that determines
the point of contact
• Example applications