Wearable Haptics for DirectingComparing the feasibility of the Head Mounted tactile display with the

Waist Mounted tactile display

Apurva Gupta, Shashank Jagirdar, Manasvi Lalwani, Thad Starner, Clint Zeagler

BACKGROUND RESEARCH

Van Erp et. al [1] demonstrated that tactile feedback on the torso immediately leads to a percept of external direction. This effect is called ‘tap-on-the-shoulder’ effect, and is akin to a person’s reflex action to look in the direction they have been tapped on their shoulder.

We hypothesized that a similar effect could be produced on the head, since it has similar affordances.

Further research revealed that while a lot of work has been done in exploring Torso-mounted tactile displays and Head-mounted displays, there was a gap in literature comparing the two.

1. Van Erp, J.B.F. (2001). Tactile navigation display. In: S. Brewster, R. Murray_Smith(Eds.): Haptic Human Computer Interaction. Lecture notes in computer science Vol.2058, pp. 165-173. Berlin Heidelberg: Springer Verlag.

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DESIGN

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1. The forehead, occipital, and temple regions of the head are most sensitive to vibrationstimulation. Therefore, these regions should be considered for purposes related to headtactile communication.

2. A four-tactor, circular head array is recommended for an HMTD design (alongside).

3. The vertex (CZ) and the temples (T3, T4) are head locations that are most suitable for BCvibrator placement. The temples (T3, T4) are also suitable head locations for vibrationstimulation or head tactile communication.

Myles, K., & Kalb, J. T. (2010). Guidelines for head tactile communication (No. ARL-TR-5116). ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD HUMAN RESEARCH AND ENGINEERING DIRECTORATE.

GUIDELINES FOR HEAD TACTILE DISPLAY

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4-tactor display design

Abdomen-mounted tactile display belt

Head-mounted tactile display belt

Conveys point-to-point information:

Right motor buzzing indicates- Turn RightLeft motor buzzing indicates- Turn Left

Front motor buzzing indicates- Move forwardBack motor buzzing indicates- Move Backward

Vibration Motors

Velcro

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Feasibility Study

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Keyboard

Simulation

Band/Belt

Arduino

Within Subject design with 10 participants where they navigate through a simulation based on feedback provided by the band/belt by pressing arrow keys on the keyboard.

Measures- Completion Time, Comfort, User Preference

Experiment 1

Schematic of the Experiment 1

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Magnetometer + Bluetooth

Band/Belt

Arduino

Within Subject design with 5 participants where the tactors orient the n in a particular direction form the starting point. The participants had their eyes shut.

Measures - Completion Time, Comfort, User Preference

Experiment 2

Schematic of the Experiment 2

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Participants asked to orient themselves(with eyes shut) based on feedback from the band.

Demo Video: https://vimeo.com/125433621

Magnetometer mounted to sense Current Orientation

Experiment 2

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Results

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• There was no difference in understanding the stimulus from either of the bands though head band had a slightly higher rating while using the stimulus in the task (Head: M = 4.2, SD= 0.7; Waist: M=3.8, SD=0.6)

• All the participants found Waist belt more comfortable and subtle in response.

• 60% participants found Headband to be better for clear feedback whereas 40% of them found it annoying.

• Some participants suggested to use pulses rather than continuous buzzes since over a period of time they seemed to get numb to the vibrations

Experiment 1

Average Response Time (Waist Belt) Average Response Time (Head Band)

154.21 ms 140ms

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USER PREFERENCE

Those who preferred Head:•Preferred wearing Head gear

•Deemed performance important than comfort

•Indicate the stomach area to be more private

for such interactions

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5 participants took part in the study, all of whom were Male with an average age of 22.6 years

Comfort Ratings (Head: M = 4.8, SD= 0.4; Waist: M=4.4, SD=0.489 )

ALL the participants reported that they found the headband better to navigate but found the waistband more comfortable.

Other user insights:

Some users reported that they felt the feedback felt “natural” and even “reflexive”

Experiment 2

5 participants performed the task for 4 different orientations(45, 90, 135, 270)

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Mean N Std. Deviation

Pair 1 HeadTimes

WaistTimes

4.8595

7.3970

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20

1.583

4.198

Head vs Waist Plots for Experiment 2

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Conclusion

• Waist band was found to be more comfortable than Headband

• Head band was found to be more prompt than Waistband

• User preference was based on the dimension of:• Comfort• Performance

• Suggestion were made to have different vibration pulses rather than a continuous stream.

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