Toward Subtle Intimate Interfaces for Mobile Devices Using an EMG Controller

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Toward Subtle Intimate Interfaces for Mobile
Devices Using an EMG Controller
Enrico Costanza Media Lab Europe now at MIT
Media Lab
Samuel A. Inverso Media Lab Europe

• Rebecca Allen
• Media Lab Europe

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Outline

• Motivation Subtle and hands-free interaction
• EMG as a solution
• An EMG-based controller
• Design approach
• Formal user study
• Conclusion

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Importance of Subtlety in Mobile Interfaces

• Mobile interaction is often in public spaces
• Subtle interfaces do not disrupt the
  environment
• Intimate interaction only for the user
• Ringing vs. vibrating alert

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Importance of Subtlety in Mobile Interfaces

• Speech recognition and evident gesturing
• can be inappropriate

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Design for Hands-free Interaction
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Design for Hands-free Interaction
Eyeglass displays
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Electromyogram (EMG) as a Novel Solution

• Electrical signal from muscle activity
• Can measure isometric activity subtle or no
  movement
• Surface Electrodes (EKG-like)
• Non-contact sensing (future)

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EMG in CHI (Related Work)

• Prosthesis control
• Input devices for disabled users
• Affect sensing
• Music expression

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EMG and MovementLimitation or Advantage?

• EMG and movement are not always related
• Tanaka Knapp report this as a limitation
• We think it is an advantage!

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Motionless Gestures

• EMG greatest potential for mobile HCI
• Sense subtle gestures
• Example brief contraction of the bicep

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EMG-based Controller

• Self-contained in armband
• Integration with Bluetooth devices
• (e.g. Phones and PDAs)
• No calibration for individual users

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Design Process

• The gesture should be
• Natural to perform
• Different from normal muscle activity
• User centered iterative approach
• 1. Select muscle generic gesture definition
• (non-detailed description to subjects)
• 2. Definition refinement, model and algorithm
• 3. Tuning

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Formal User Study

• Realistic controlled environment subjects
  walked
• around obstacles in trafficked walkway
• 10 subjects
• Audio stimuli and feedback
• Is training avoidable? (minimal feedback)
• Push the limit short and long contractions

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Results

• 96 correct recognition
• No false positives
• No training necessary in 7 out of 10 cases
• Cannot distinguish short and long contractions
• across different subjects

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Discussion

• EMG can be successfully used (96)
• Generally no training required
• No calibration across users

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Discussion

• Cannot distinguish short and long contractions
• Subjective definition of short and long

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Future Work

• Test in more complex scenarios
• Measure subtleness
• Improve algorithm
• Use more muscles (alphabet definition)

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Summary and Conclusion

• Subtle interaction for mobile devices
• New reason to use EMG in CHI
• Motionless gestures
• It works (96 correct recognition no false
  positives)