d etecting d river p hone u se l everaging c ar s peakers jie yang, simon sidhom, gayathri...
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DETECTING DRIVER PHONE USE LEVERAGING CAR SPEAKERS
Jie Yang, Simon Sidhom, Gayathri Chandrasekaran, Tam Vu, Hongbo Liu, Nicolae Cecan, Yingying Chen, Marco Gruteser, Richard P. Martin
MobiCom 2011
- Sowhat 2011.10.24
OUTLINE Introduction System design Experiment Results Conclusion Discussion
OUTLINE Introduction System design Experiment Results Conclusion Discussion
INTRODUCTION
MOTIVATION
Cell Phone Distraction
Hands-free Phone Operation
Driving Mode• Route incoming calls to
voicemail• Delay incoming text
notification
Driver? Passenger?
INTRODUCTION
OBJECTIVE Classify phone use @ which seat
Bluetooth + Audio infrastructure
Phone Transmit Signal
Car Head Unit
Speaker Play
Signal
Phone Record
Processing
INTRODUCTION
CHALLENGES Unobtrusiveness
Robustness to Noise and Multipath
Computational Feasibility
OUTLINE Introduction System design Experiment Results Conclusion Discussion
SYSTEM DESIGN
OVERVIEWAcoustic Relative-Ranging System
Avoid InterfereDistinguish speakers
SYSTEM DESIGN
RELATIVE RANGING
SYSTEM DESIGN
BEEP SIGNALUnobtrusivenessRobustness to Noise
Frequency Android developer phone 2 – 16~18kHz iPhone 3G – 18~20kHz
Length – 10ms
SYSTEM DESIGN
PROCESSING
SYSTEM DESIGN
DETECT BEEP Sequential change-point detection
: sequence of recorded audio signal
Requirement: known distribution
Cumulative sum μ : mean value of noise from t0 to t1, time of
transmitting
> Threshold for W samples
SYSTEM DESIGN
PROCESSING
SYSTEM DESIGN
CLASSIFICATION 2-channel
> -5
4-channel if Front
Check Else Back
Check
OUTLINE Introduction System design Experiment Results Conclusion Discussion
EXPERIMENT
PHONES & CARS Phones
Android Developer Phone 2, Phone I iPhone 3G, Phone II
Cars Honda Civic Si Coupe, Car I Acura Sedan, Car II 2 channel sound system with fader system
EXPERIMENT
PROCEDURE Create Beep
4 beep audio files, For { Phone I, Phone II } x { 2 channel, 4 channel } Each file with 4 beeps for each channel
Create uniformly distributed white noise
Bandpass filter {16~18, 18~20} kHz
Transmit Laptop to car’s head unit via Bluetooth
Record Audio recorder app. on phone for offline analysis
EXPERIMENT
SCENARIOS
Phone I, Car I
EXPERIMENT
SCENARIOS
Phone II, Car II
EXPERIMENT
SCENARIOS
Phone I, Car I @ 60 MPH
Highway
OUTLINE Introduction System design Experiment Results Conclusion Discussion
RESULTS
METRICS Accuracy
Detection Rate
False Positive Rate
Measurement Error
RESULTS
DRIVER VS. PASSENGER
2-Channel is OK
RESULTS
POSITION ACCURACY
RESULTS
LEFT VS. RIGHT
RESULTS
FRONT VS. BACK
RESULTS
RELATIVE RANGING
RESULTS
COMPUTATIONAL COMPLEXITY Filtering, Short-time Fourier transform
n recorded samples, moving window size
After filtering,
Average processing time 0.5s for 2-channel 1s for 4-channel
OUTLINE Introduction System design Experiment Results Conclusion Discussion
CONCLUSION Driver mobile phone use detection system
Leverage existing infrastructure of car speaker for ranging via Bluetooth
Acoustic relative-ranging
Over 90% detection rate
OUTLINE Introduction System design Experiment Results Conclusion Discussion
DISCUSSION Strengthens
Clear motivation, system design description Real implement
Weakness Different setting for different hardware
not comparable How to set calibration value
THANKS FOR LISTENING ~