d etecting d river p hone u se l everaging c ar s peakers jie yang, simon sidhom, gayathri...
Post on 21-Dec-2015
215 views
TRANSCRIPT
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
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
SYSTEM DESIGN
BEEP SIGNALUnobtrusivenessRobustness to Noise
Frequency Android developer phone 2 – 16~18kHz iPhone 3G – 18~20kHz
Length – 10ms
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
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
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
CONCLUSION Driver mobile phone use detection system
Leverage existing infrastructure of car speaker for ranging via Bluetooth
Acoustic relative-ranging
Over 90% detection rate
DISCUSSION Strengthens
Clear motivation, system design description Real implement
Weakness Different setting for different hardware
not comparable How to set calibration value