E0-245: ASP. Lecture 16+17: Physical Sensors. Dipanjan Gope

Transcription

1 E0-245: ASP Lecture 16+17: Physical Sensors

2 Module 2: Android Sensor Applications Location Sensors - Theory of location sensing - Package android.location Physical Sensors - Sensor Manager - Accelerometer - Gyroscope - Magnetometer - Sensor fusion Multimedia - Camera - Microphone NFC 2

3 Coverage Activity Views Intent ContentProvider BroadcastReceiver Service 3

4 References Greg Milette, Adam Stroud: Professional Android Sensor Programing, 2012, Wiley India 4

5 Popular Apps with Physical Sensors MAGNETOMETER APPS GYROSCOPE GAMING ACCELEROMETER FITNESS 5

6 Classification based on source of data 6

7 Raw Sensor Data 7

8 Raw Sensor Data 8

9 Synthetic Sensor Data 9

10 Classification based on application 10

11 Physical Sensors Motion Position - Accelerometer - Gyroscope - Linear acceleration - Gravity - Magnetic field - Proximity - Rotation vector Environment - Light - Barometer - Ambient temperature - Relative humidity 11

12 Smart Watches Today &uact=8&ved=0cacqjrw&url=http%3a%2f%2fwww.slideshare.net%2fleybzon%2f apple-iwatch-android-wear-and-other-wristbased-sensor-platforms&ei=j- EQVe6sDNWdugS84oGwBg&psig=AFQjCNFwN3VY9DQjg7lYqPiWdZqxh0qR8A&ust=

13 Sensor Hardware 13

14 Accelerometer F=mA MEMS Capacitive-based SIP

15 Gyroscope F=-2m Ω x v MEMS Capacitive based SIP Ref: MEMS gyroscopes - A revolutionary way to interface with the real world, STMicroelectronics 15

16 Magnetic Field Lorentz Force Anonymous, 400BC Asahi Kasei: AK8975C Others: Anisotropic Magneto Resistance 16

17 Android Sensor Data Structures 17

18 Class: SensorManager Sensor SensorEvent Android.hardware Interface: SensorEventListener 18

19 Package: Android.location Reads LocationProvider Requirements LocationManager Criteria Enables Notifies with location data LocationProvider LocationListener Produces Consumed Location Greg Milette, Adam Stroud: Professional Android Sensor Programing, 2012, Wiley India 19

20 Package: Android.hardware SensorManager Specifies Sensor SensorEventListener Event Values Produces Consumed SensorEvent 20

21 Manifest File <uses-feature android:name="android.hardware.sensor.accelerometer" android:required="true" /> <uses-feature android:name="android.hardware.sensor.compass" android:required="false" /> 21

22 Manifest File android.hardware.sensor.accelerometer android.hardware.sensor.gyroscope android.hardware.sensor.compass android.hardware.sensor.barometer android.hardware.sensor.light android.hardware.sensor.proximity 22

23 SensorManager private SensorManager sensormanager; sensormanager = (SensorManager) getsystemservice(sensor_service); List<Sensor> sensors = sensormanager.getsensorlist(sensor.type_****); Sensor = sensormanager.getdefaultsensor(sensor.type_***); 23

24 Maximum range Minimum delay Name Power Resolution Type Vendor Version Sensor Class 24

25 Accuracy - SENSOR_STATUS_ACCURACY_HIGH - SENSOR_STATUS_ACCURACY_MEDIUM - SENSOR_STATUS_ACCURACY_LOW - SENSOR_STATUS_ACCURACY_UNRELIABLE Sensor Timestamp Values SensorEvent 25

26 SensorEventListener onaccuracychanged - when the accuracy from the sensor changes onsensorchanged - when the values from the sensor changes 26

27 Sensor Data Reference nsors/sensors_overview.html 27

28 Lets Code 28

29 1. Determine Available Sensors 29

30 Building Block: Intent Move from one screen (activity) to another Can also open other applications 3 main: start an activity/service/broadcast Asynchronous Bound at run-time Explicit or implicit 30

31 Implicit Intent 31

32 Primitive Passing Data: Extras 32

33 Passing Data: Application Persistent Objects 33

34 2. Determine Sensor Range and Resolution 34

35 Units Acceleration: m/s 2 Gyroscope: Deg/s or Rad/s Magnetic Field: ut Min Delay: us Power: ma 35

36 3. Define Sensor Rate SENSOR_DELAY_FASTEST SENSOR_DELAY_GAME SENSOR_DELAY_UI SENSOR_DELAY_NORMAL 0ms 20ms 67ms 200ms 36

37 Sensor Results Display 37

38 4. Register/Unregister SensorListeners 38

39 Signal Processing and Sensor Fusion 39

40 Accuracy and Precision Greg Milette, Adam Stroud: Professional Android Sensor Programing, 2012, Wiley India 40

41 Type of Error Noise Drift Accelerometer Drift Gyroscope Drift Paul Lawitski, Sensor fusion 41

42 Filtering Low-pass filter High-pass filter to filter noise in gravity Kalman filter - systems dynamic model and constraints 42

43 Sensor Fusion 43

44 Acceleration in Earth s axis 44

45 Coverage Activity Views Intent ContentProvider BroadcastReceiver Service 45