ALPS: A Bluetooth and Ultrasound Platform for Mapping and Localization

Transcription

1 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

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

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

4 System Architecture Speaker Phone 4

5 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

6 Introducing ALPS Easily Deployable Ultrasonic Localization BLE, , Ultrasonic SenSys Come see our Demo!

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

8 Original Hard-Wired Setup 8

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

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

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

12 Omnidirectional Sound Dispersion 12

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

14 Omnidirectional Sound Dispersion 14

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

16 Omnidirectional Horn Performance 16

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

18 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

19 System Architecture Beacon BLE Data Phone 19

20 The ALPS Platform Antenna CC2460 SoC BLE Antenna 20

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

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

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

24 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

25 User Assisted Mapping and Setup Beacon 25

26 Inter-beacon Ranging Beacon Inter-Node Ranging 26

27 Synchronize Receiver to Transmitters Beacon Inter-Node Ranging 27

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

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

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

31 User-Assisted Mapping Performance 31

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

33 Tracking Use Case Insufficient Beacons SenSys 2015 Beacons blocked

34 ALPS Localization Performance Localization 12 True path Localization 10 8 y (m) x (m) 34

35 ALPS and PDR Performance Localization, PDR, both, with no obstacles True path Dead Reckoning Localization Localization + Tracking 8 y (m) x (m) 35

36 ALPS with Obstacles Performance 12 True path Localization 10 8 y (m) x (m) 36

37 ALPS with Obstacles and PDR Performance 12 True path Localization Localization + Tracking 10 8 y (m) x (m) 37

38 ALPS and PDR Performance 38

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

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

41 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

42 Impact of Training Samples of F ib and F us Performance 42

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

44 Questions 44