A Smart System for Sitting Posture Detection Based on Force Sensors and Mobile Application

Table 1

Description of chair data attributes.

Attribute	Explanation	Type/states
actual_sitting_state	Information about sitting posture.	String {green, orange, red}
avg_deviation	Average standard deviation from the last five measurements for four bottom sensors.	Float
avg_back_deviation	Average standard deviation from the last five measurements for two back sensors.	Float
actual_sitting_time	Current uninterrupted sitting on the chair in seconds.	Integer
back_data_present	It indicates if there are present valid data from back sensors.	Integer {0, 1}
long_sitting	It indicates long uninterrupted sitting on the chair.	Integer {0, 1}
Duration	The elapsed time in second from the login.	Integer
start_time	Login time.	Unix timestamp
sitting_history	History of the sitting states with the Unix timestamp, when the changes occurred.	Array of objects
actual_sitting_status	It indicates if there is somebody sitting in the chair.	Integer {0, 1}

Object “chdata” is added to the message in the node “Chair 1 statistic.” Figure 9 describes the function node flowchart.