Figure 3

High level separation of tasks (6 subjects). A scatter plot of the root mean square (RMS) value of the accelerometer data recorded in the antero-posterior direction from the right thigh vs. the mean value of the accelerometer data recorded from the same sensor unit in the up-down direction demonstrates that certain categories of tasks can be easily discriminated using a simple ruled-based approach. In fact, the plane can be divided into three regions containing the samples associated with motor tasks related to ambulation, motor tasks performed in a seated position with legs moving, and motor tasks performed in a seated position with legs stationary respectively.