CAT: High- PreCision Acoustic Motion Tracking PowerPoint Presentation

CAT: High- PreCision  Acoustic Motion Tracking PowerPoint Presentation

2018-03-22 39K 39 0 0

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Wenguang Mao, Jian He, Lili Qiu. UT Austin. MobiCom. 2016. Why motion tracking?. Motion-based Games. Virtual Reality. Why motion tracking?. Support motion-based interaction. Smart Appliance. Possible solutions. ID: 661196

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Presentations text content in CAT: High- PreCision Acoustic Motion Tracking

Slide1

CAT: High-PreCision Acoustic Motion Tracking

Wenguang Mao, Jian He, Lili Qiu

UT Austin

MobiCom

2016

Slide2

Why motion tracking?

Motion-based Games

Virtual Reality

Slide3

Why motion tracking?Support motion-based interaction

Smart Appliance

Slide4

Possible solutions

Vision

based approach

Needs extra hardwareDepends on lighting conditionComputationally heavy

Slide5

Possible solutions

RF

based approach

WiFi : limited accuracy (e.g., 10 cm [Chronos16])RFID: limited accuracy (e.g., 4 cm [RF-Idraw])60 GHz waves: extra hardware not widely available 60GHz Antenna

Slide6

Acoustic Signal

Slow propagation – helpful to achieve

high accuracy

Easily available speakers and mics –

widely available

Low sampling rate – feasible for

SW processing

Slide7

CAT

 

 

CAT

Slide8

Key Components

Distributed FMCW

Doppler Shift

Optimization Framework

Audio Samples

Movement Trajectory

Distance

Velocity

CAT

Slide9

FMCWFMCW for propagation delay estimation

Less bandwidth usage than using a sharp pulse

Send a chirp whose freq. changes linearly over time

Estimate the frequency difference

, and

~ distance travelled by the chirp

 

 

 

Slide10

Distributed FMCWSpeaker (sender) and microphone (receiver):Not known when the chirp is sent Two-step distance estimation

Sampling rate offset

Drift compensation

Time

Frequency

Transmitted

Received

Slide11

Two-Step Distance EstimationDecompose distance

into two parts

 

 

Pseudo-transmission time

Reference point

Slide12

Two-Step Distance EstimationDecompose distance

into two parts

 

 

Pseudo-transmission time

Reference point

Slide13

Pseudo-Transmission Time

Time

Frequency

Transmitted

Received

 

Pseudo-Transmitted

 

 

 

 

Slide14

Two-Step Distance EstimationDecompose distance

into two parts

 

 

Pseudo-transmission time

Reference point

Slide15

Reference Point

 

 

Doppler +

Doppler -

Slide16

Drift Compensation

Estimated distance drift over time

Slide17

Drift CompensationDue to imperfect clocks, the sender and the receiver have different the sampling ratesE.g., 44100.1 Hz (sender), 44099.9 Hz (receiver)

1764 samples at the receiver

1764 samples at the sender

Prop. delay

Chirp 1

Prop. Delay

Chirp 2

Chirp diff.

Slide18

Drift Compensation

Slide19

Drift Compensation

Slide20

 

Doppler Shift Measurement

Measure frequency shift

between transmitted and received signals

Velocity is given by

 

 

Slide21

Optimization frameworkFusing distance and velocity measurementsFind position

that fits the measurements best

Efficient algorithm for solving it

Incorporate IMU measurements

 

 

Dist. measurement fitting error

Vel. measurement fitting error

Multiple tracking periods

Smooth the estimated results

No error accumulation

Slide22

Experiments2D tracking with 2 speakers2D tracking with 3 speakers

3D tracking with 4 speakers

Slide23

2D Tracking Accuracy

CAT is accurate and fusing distance/velocity significantly improves the performance

 

6mm

8 cm

2 cm

 

Slide24

3D Tracking

8-9 mm 3D tracking error

Slide25

User Study

(a) CAT

(b)

AAMouse

(Doppler only)

4mm trace error

 easy to use

Red: reference

Blue: traced by users

Slide26

ConclusionDistributed FMCW to support a separate sender and receiverOptimization framework and algorithm to fuse distance and velocity over time

CAT tracking system

Achieves mm-level accuracy on commodity devices

Future work: develop new applications


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