This week I tried using the angles of the acceleration as new features to the SVM. I decided to use the angle between the xy-plane and the z-axis because that would be the angle that changes the most when a person falls. However, I should think more about which axis to use after collecting some data from our device as the orientation of the accelerometer in our device and the phone would be different. I should also consider that the device will be placed inside a pocket, which can also change the orientation.
The angle was defined as: atan(az/(ax^2+ay^2)^0.5) The graph below shows that the angle fluctuates a lot for a fall, while it stays mostly constant for walking.
In terms of schedule, we are on track. For next week, I would really need to start collecting and using the data from our actual device as the RPi will be ready to use. All the data that I collected this week and last week were all done in the same position, but I should also try collecting them from different positions and see if they make any difference.