This is a toy Android application I wrote to get some experience with:
- Kotlin with Android
- Android's accelerometer
- GraphView library
- Writing data to a file that can be uploaded from the Android device for analysis
The app collects accelerometer sensor data and plots the X,Y,Z acceleration components along with a shake detector signal which rises to a "shake state" when the device is subjected to an acceleration of more than 2 gs. Sensor data is collected about 5 times per second.
The shake detect signal is computed using a high-pass filter approximation which subtracts the average of each accleration component from every new sample. The Y-axis graph units are g's and do correspond to the acceleration components.
The detector signal clamps to 20g's when a shake is detected. (The magnitude of the shake signal is arbitrarily set to 20g.)
Here is a picture:
Accelerometer sensor reading is covered by Android documentation.
See GraphView library for information on the graphing library.
The data file created by the app is written to the app's storage. I used Handshaker to upload the signal data to my Mac to play with filtering algorithms.