SLIDE 1 Battery ry-Free Id Identifi fication Token for Touch Se Sensing Devices
Phuc Nguyen, Ufuk Muncuk, Ashwin Ashok, Kaushik R Chowdhury, Marco Gruteser, and Tam Vu
SLIDE 2 Touch Sensing Technology
Phone & Laptop Smart vehicle Smart appliances Payment Home security Medical Devices
Existing touch surfaces serve as an interface between human and the devices itself Can an object interact with the touch surface?
SLIDE 3 Collaborative Applications
02
01
User ID Logging
001 Windows design 002 Front door design 001 Roof design 002 Roof coloring 001 Back yard design 002 Back door design … …
Associating user ID to collaboration activities
SLIDE 4
Gaming Applications with Touchscreen
Role-playing Games Multiplayer Games
There is a need for associating identity to touch interactions Associating real-world token to digital world
SLIDE 5
Token Artifact Touch Surface
Idea:
Send data (e.g. Identifier) to the mobile device by varying capacitance on the of touch surface
System Overview
Transmitter Receiver
SLIDE 6 Artifact Token Touch-enabled device
Time Capacitance
Micro-controller (token ID encoded as bits) Control switch to vary capacitance
Transmitter Design
SLIDE 7
‘0’ ‘1’ ‘0’ ‘1’ ‘1’ ‘1’ ‘0’ ‘0’ 1 2 3 4 5 6 7 8 Time slot Capacitance
Modulation
How do we vary capacitance efficiently?
SLIDE 8
Touch surface
tprob tprob tpress Objective: min(tpress - tprob) How do we obtain tprob?
Capacitance Time Touch sensor
SLIDE 9
Enable th the token to profile th the touch surface
SLIDE 10
Probing Frequency (fprob=1/ tprob)
SLIDE 11
- Autocorrelation is used to find probing frequency
Finding Probing Frequency
tprob tprob
SLIDE 12 62 62.36 108.16 103.62101.2 96 109.8 84.33 124.52 100 118.8 130.04 20 40 60 80 100 120 140
Probing frequency (Hz)
Finding Probing Frequency
SLIDE 13 Artifact Token Touch-enabled device
Timestamp Event Type Pointer ID XY coordinate Touch size Touch Amplitude Touch Events
Time in ms Touch’s location
Receiver Design
SLIDE 14
Harvesting Energy fr from Touch Surfaces
SLIDE 15
ADC reading
Energy Harvesting
SLIDE 16
Challenges
0 – 100 Hz
Flicker noise
SLIDE 17
Proposed Approach
SLIDE 18 Harvesting Module
Touch sensor
Electrode
C1 D1 C2 D2 Rectifier
Band Pass Filter (Fcut-off, Bandwidth)
CS Micro- controller
Storage Capacitor
Energy Harvesting Module
2"
SLIDE 19
Prototype Im Implementation
SLIDE 20
Detection Rate
Goal: Evaluate the object identification accuracy Experiment: Calculate token detection rate (fraction of
total number of times the token is correctly identified)
SLIDE 21
Power Consumption
Goal: Evaluate the power consumption
Experiment: Calculate the energy consumption when sending data at different size Power ~ time to open & close switch
SLIDE 22 Im Impact of f Profiling Technique
Goal: Evaluate the impact of profiling technique Experiment: Calculate event generation rate between
- ur approach and strawman approach
SLIDE 23
User Study
SLIDE 24
- 1. Associating IDs to tokens for touch interactions
- 2. Enabling the token to profile the touch surface
- 3. Harvesting energy from the touch surfaces
Conclusion
SLIDE 25 Battery ry-Free Id Identification Token for Touch Sensing Devices
Phuc Nguyen, Ufuk Muncuk, Ashwin Ashok,
Kaushik R Chowdhury, Marco Gruteser, and Tam Vu
