DATA PROCESSING
The primary steps involved in our data processing for each
subject’s data is illustrated in Fig. 1 and described in detail in
the following sections.
A. Acquisition and Pre-processing
The tri-axial accelerometer located on the wrist transmits
data along with a time stamp to a host computer using the
Bluetooth wireless transmission protocol and each activity
performed by a subject is marked to record the start and end of
the movement for all trials performed during the training and
testing phases. The raw sensor data is band-pass filtered with a
3rd order Butterworth filter having cut-off frequencies of 0.1
Hz and 12 Hz to respectively attenuate the low frequency
artifacts and high frequency noise components introduced in
the data due to physical effects such as drift [13].