ALPS: A Bluetooth and Ultrasound Platform for Mapping and - PowerPoint PPT Presentation

SenSys 2015 ALPS: A Bluetooth and Ultrasound Platform for Mapping and Localization Patrick Lazik, Niranjini Rajagopal, Oliver Shih, Bruno Sinopoli, Anthony Rowe Electrical and Computer Engineering Department Carnegie Mellon University http://wise.ece.cmu.edu

SenSys 2015 Localization Approaches Range-Based (Distance) Kinect RADAR WiFi RFID Ultrasonic GPS Cellular VLC Audio LIDAR Range-Free (Landmarks) Magnetic Bluetooth IMU Field Low-Energy 2

SenSys 2015 ALPS – Smartphone Acoustic Ultrasonic Ranging for Mobile Devices Localization • Uses near-ultrasound communication • Commodity mobile hardware • Provide accurate indoor localization – Sub-meter, confined to rooms • Time Difference of Arrival (TDOA) 3

SenSys 2015 System Architecture Speaker Phone 4

SenSys 2015 Challenges • Transmitting omnidirectional ultrasonic signals is difficult with standard speakers • Installation and setup • Obstructions (bodies) can block transmitters – TDOA to TOF (RTAS 2015) • Multipath signals cause measurement errors 5

SenSys 2015 Introducing ALPS • Easily Deployable Ultrasonic Localization • BLE, 802.15.4, Ultrasonic SenSys 2012 Come see our Demo! 6

SenSys 2015 ALPS Enhancements • Embedded beacons – Hardware – Ultrasonic Horn Design • Improved data transmission • Simplified system setup • Tracking with IMU data • Multipath Detection 7

SenSys 2015 Original Hard-Wired Setup 8

SenSys 2015 The ALPS Platform 802.15.4 Antenna BLE Antenna Piezo Bullet Driver Horn Battery Pack Microphone Back Front 9

SenSys 2015 The ALPS Platform TLV320 Audio Microphone Atmega256RFR2 RF Codec SoC Amplifier 10

SenSys 2015 Omnidirectional Sound Dispersion • Ideally ALPS beacons should disperse ultrasound in omnidirectional manner • Directivity pattern of speakers becomes more narrow as frequency increases 11

SenSys 2015 Omnidirectional Sound Dispersion 12

SenSys 2015 Omnidirectional Horn Design • Horns increase the overall efficiency of driving elements • A rotated horn will disperse sound omnidirectionally 13

SenSys 2015 Omnidirectional Sound Dispersion 14

SenSys 2015 Omnidirectional Horn Performance • Evaluation criteria: – Directional distortion: deviation from omnidirectionality – Frequency distortion: flatness of frequency response 15

SenSys 2015 Omnidirectional Horn Performance 16

SenSys 2015 ALPS Enhancements • Embedded beacons • Improved data transmission – Integration with BLE • Simplified system setup • Tracking with IMU data • Multipath Detection 17

SenSys 2015 Transmitter Identification • Originally modulated transmitter ID onto ultrasound carrier – Long packet length, limited robustness – Ultrasound is good for ranging – BLE is better for data 18

SenSys 2015 System Architecture Beacon BLE Data Phone 19

SenSys 2015 The ALPS Platform 802.15.4 Antenna CC2460 SoC BLE Antenna 20

SenSys 2015 BLE TDMA Slot Synchronization Slot 0 Slot 1 τ tx0 a) τ tx1 τ tx2 τ tx3 τ tx4 . . . b) τ rx0 c) 21

SenSys 2015 BLE Synchronization Performance • Typical TDMA slot length of 100ms 100ms advertisement 50ms advertisement 20ms advertisement interval interval interval 22

SenSys 2015 ALPS Enhancements • Embedded beacons • Improved data transmission – Integration with BLE • Simplified system setup • Tracking with IMU data • Multipath Detection 23

SenSys 2015 User Assisted Mapping and Setup • Precise positioning of beacons, even in small installations is difficult • Developed automated setup procedure for determining beacon locations and floorplan 24

SenSys 2015 User Assisted Mapping and Setup Beacon 25

SenSys 2015 Inter-beacon Ranging Inter-Node Beacon Ranging 26

SenSys 2015 Synchronize Receiver to Transmitters Inter-Node Beacon Ranging 27

SenSys 2015 Define Z Axis Inter-Node Beacon Ranging Beacon Ultrasound z Phone 28

SenSys 2015 Define X and Y Axis Inter-Node Beacon Ranging Beacon Ultrasound Phone y z x 29

SenSys 2015 Draw Floorplan Inter-Node Beacon Ranging Phone Beacon Ultrasound y z x 30

SenSys 2015 User-Assisted Mapping Performance 31

SenSys 2015 ALPS Enhancements • Embedded beacons • Improved data transmission – Integration with BLE • Simplified system setup • Tracking with IMU data • Multipath Detection 32

SenSys 2015 Tracking Use Case – Insufficient Beacons Beacons blocked

SenSys 2015 ALPS Localization Performance Localization True path 12 Localization 10 8 y (m) 6 4 2 0 -6 -4 -2 0 2 4 6 8 10 x (m) 34

SenSys 2015 ALPS and PDR Performance Localization, PDR, both, with no obstacles True path 12 Dead Reckoning Localization Localization + Tracking 10 8 y (m) 6 4 2 0 -6 -4 -2 0 2 4 6 8 10 x (m) 35

SenSys 2015 ALPS with Obstacles Performance Localization True path 12 Localization 10 8 y (m) 6 4 2 0 -6 -4 -2 0 2 4 6 8 10 x (m) 36

SenSys 2015 ALPS with Obstacles and PDR Performance Localization and Loc+PDR True path 12 Localization Localization + Tracking 10 8 y (m) 6 4 2 0 -6 -4 -2 0 2 4 6 8 10 x (m) 37

SenSys 2015 ALPS and PDR Performance 38

SenSys 2015 ALPS Enhancements • Embedded beacons • Improved data transmission – Integration with BLE • Simplified system setup • Tracking with IMU data • Multipath detection 39

SenSys 2015 Multipath Detection Ultrasonic BLE True range Multipath range • Signal propagation different • Attenuation characteristics different 40

SenSys 2015 SVM Classifier Features and Accuracy Ratio of received ultrasound RSSI to TOF distance Ratio of received BLE RSSI to BLE distance RMS delay spread of received ultrasound signal 41

SenSys 2015 Impact of Training Samples of F iB and F us Performance 42

SenSys 2015 Conclusion • Indoor localization systems need to be: Precise, cheap and simple to install – ALPS has cheap hardware and supports a user- assisted setup procedure • Range based localization systems suffer from multipath ranging error – ALPS incorporates a machine learning based LOS/ NLOS filtering approach 43

SenSys 2015 Questions 44