Figure 2.

Sensor position illustration for different types of HAR system; (a) is the applied scene; (b) shows several effective isolated sensor points (such as the wall and significant joints of the body); and (c) is the predefined numbered position in the position space. For nonwearable types, one numbered sensor position can indicate several sensors (e.g., the figure shows six sensors at one position). For the wearable type, one sensor position indicates one sensor.