snow walking_english

Snow Walking: Motion-Limiting Device that Reproduces the Experience

of Walking in Deep Snow

School of Fundamental Science and Engineering, Waseda University

Tomohiro YOKOTA, Motohiro OHTAKE, Yukihiro NISHIMURA,

Toshiya YUI, Rico UCHIKURA, and Tomoko HASHIDA

BACKGROUND

- There are infrequent situations that

limit our body sensation.

- simulating these situations by VR system

enable us to effectively deal with the same

situations in the real.

- In this study, we reproduce

the field of deep snow.

- The novel point is reproducingthe motion-limited sensation and the tactile sensation

on the same device.

RELATED WORKSReproducing the specific field for the foot

Multimodal floor[2] Viscose force display[3]

[1] Iwata, H., et al. 2000. The GaitMaster : Locomotion Interface for Uneven Virtual Surface. In Transactions of the Virtual Reality Society of Japan 5(2), VRSJ '00, 863-866. [2] ] Law, A.W., et al. A Multi-modal Floor-space for Experiencing Material Deformation Underfoot in Virtual Reality. In Proceedings of IEEE International Workshop on Haptic Audio Visual Environments and Games (Ottawa, Canada, Oct 18-19, 2008). HAVE '08, IEEE. 126-131.[3] Ando, H., et al. 1998. Viscose Force Display to the human leg. In Transactions of the Virtual Reality Society of Japan 3(4), VRSJ '98, 245-248.

the tactile sensation the motion-limited sensation

Snow surface Deep paddy fieldIrregular surface

GaitMaster[1]

Breakdown of the experience“Walking in the deep snow”

①

②③

⓪

Breakdown of the experience“Walking in the deep snow”

STEP.1 Lowering a foot into deep snow

STEP.2 Crunching the bottom of deep snow

STEP.3 Raising a foot out from deep snow(The foot is opposite to ②)

Design of Snow Walking

< Reproducing sensation >

(1) the motion-limited sensation by the depth(depth of the snow: about 15 cm)

(2) the tactile sensation by crunching the bottom

■Slider-magnet mechanism

reproduces motion-limited sensation by depth of snow.

■Starch-moving mechanism

reproduces tactile sensation by crunching the bottom of snow.

STEP.1 Lowering a foot into deep snow

STEP.3 Raising a foot out from deep snow

STEP.2 Crunching the bottom of deep snow

System Overview

< Instance >

Size of long boot : 25.5 cm (= 255 mm)

↓

W : 180 mm

D : 305 mm

H : 323 mm

Weight : 1874 g

(one side of the devices)

Slider-magnet mechanismSliders:• limit the movable direction of the

foot

• reproduce the deep snow resistance by two attachments.

Electromagnets:• stick to the iron plate and limit to

step forward the foot.

Iron plates• are laid on the floor to stick magnet.

Distance sensor: • measures the height of the foot.

Vibration speaker (with amplifier):

• reproduces the sound and tactile by lowering the foot into deep snow

Slider-magnet mechanism

ElectromagnetStick

Under15 cm

Height of the foot < 15 cm(Depth of snow: about 15 cm.)

• Electromagnets stick to the iron plate.

• Motion of the foot is limited except raising or lowering along the slider.

• Vibration speaker works on the sole when lowering the foot.

Distancesensor

Slider

Slider

Distancesensor

15 cmand over

Electromagnets: OFF


Height of the foot ≥ 15 cm(Depth of snow: about 15 cm.)

• Electromagnets stop working.

• The foot becomes free and user be able to step forward.

Electromagnets: ON


Limiting the motion of the foot except to upper direction by sliders and magnets.

Snow

Reproduced experience


Limiting the motion of the foot except to upper direction by sliders and magnets.

slide

StickSnow

××


Snow


Electromagnets: OFF

150mm

When the foot reached 150 mm, the electromagnets stop working and user becomes able to step forward.



Ground

Bottom of the snow

Speaker reproduces the sound and small tactile getting before crunching the bottom.

150mm

vibrate

Electromagnets: ON

slide



Snow

Stick


Crunching the bottom of deep snow

Attachment 2:

Hook and loop fastener

Inner rail jostles through the hook and loop fastener on the outer rail of the slider, and 5.54- N friction drag like snow is reproduced.

Attachment 1:

Simple air damper

air damper moves together with the slider as pushing or pulling air. It reproduces about 6.19-N resistance.


jostlejostle

Starch-moving mechanism

Potato starch (packed in a bag):

• reproduces the tactile sensation by crunching the bottom of snow to the sole of the foot.

Motor box and Caterpillar:• moves the bag of starch alternate

back or forth after each steps.

(packed in a bag)


When the user put down the foot on the floor,

• User crunch the bag of the starch by the sole of the foot and get tactile like the bottom of snow.

• The bag of starch moves back or forth under the soleafter being crunched. Potato Starch Caterpillar

Crunch

it is crunched different spot per step

it is not compressed in the bag.

it moves back or forth after be crunched.

< Bag of starch >



crunch


rotate

rotate


move

System control

• These two mechanisms are controlled by Firmataprotocol with an Arduino board.

• The total power consumption is about 300 W.

250 W

16 W

10 W

×2

One device for each foot.

■ IVRC2014 Final (International collegiate Virtual Reality Contest)

in MIRAICAN, Tokyo, JAPAN from October 23 to October 26, 2014.

EXHIBITION

( Appearance of exhibition )

• Date: October 26

• The number of participants: 75

(male: 58, female: 17)

• Sides of the boots : 25.5 cm or 28.0 cm

USER STUDY

(Questionnaire)

• Users put this device on only the right foot.

• Users walked at least 5 or 6 steps on the right foot.

Question 1:“How did you feel when you were standing

in deep snow when using this device?”

■Choices■5 - Extremely Satisfied ■4 - Satisfied■3 - Neither ■2 - Dissatisfied ■1 - Extremely Dissatisfied

Number of answers: 72Average score: 4.17Variance: 0.81

37.50%

52.78%

0.00%8.33

%

1.39%

“Quality of experience given by Snow Walking.”

■Choices(multiple answers allowed)

1- the feel of pulling your foot up : 53.52%

2 - the feel of putting your foot down : 29.58%

3 - the feel of crunching across the bottom : 40.85%

4 - N/A.” : 1.41%

■Choices (multiple answers allowed)

Number of answers: 71

Question 2:“If you feel as if you are standing in deep

snow, what makes you think so? ”

1 - the feel of raising your foot up.

2 - the feel of lowering your foot down.

3 - the feel of crunching across the bottom.

4 - N/A

Question 3:“what, if at all, depth of deep snow have

you experienced?”

■Choices (multiple answers allowed)

1 - 0 ~ 3 cm

2 - 3 ~ 10 cm

3 - 10 ~ 30 cm

4 - 30 cm ~

Number of answers: 74

68.92%

31.08%

“About the experience walking in deep snow more than 10-cm depth”

■ Having the experience

■ Never having the experience

(forgot to make the choice “never have”)

CONCLUSION

- We proposed the device reproducing the infrequent

experiment that limit our body sensation,

particularly that of deep snow.

- Snow Walking is configured with two types of

mechanism, Slider-magnet mechanism and Starch-

moving mechanism.

- We had exhibition and user study at the IVRC2014.

FURURE WORK

For improving the experience of this device,

- Having the experiment about the resistance of actual

deep snow and adjust the device based on it.

- Changing attachments of slider to fluctuate resistance

between raising the foot and lowering it.

For improving the usability of this device,

- shortening the time to wear and becoming wearable on

any size of the foot.

FURURE WORK

- Having the experiment about the resistance of actual

deep snow and adjust the device based on it.

- Changing attachments of slider to fluctuate

resistance between raising the foot and lowering it.

Thank you for your listening.

[email protected]

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