Figure 2.

Overview of the Hand Activity estimated by Nonlinear Detection (HAND) count algorithm (A): Distribution of consecutive changes in the differential reading for all axes combined when the magnetic-sensing wrist-band rested on a table away from the ring magnet. 0 means that two consecutive differential readings had different signals (e.g., one positive, one negative), 1 means that there was 1 consecutive differential reading with the same signal, 2 means that there were two consecutive differentials with the same signal, etc. The grey vertical line shows three standard deviations from the mean. (B–D) Show an example of the HAND algorithm applied to data acquired during a wrist extension with the hand open (B), displacement in degrees of the wrist during an extension movement; (C) differential reading for each of the axes (x, y, z); each circle is one data point; dashed lines are the threshold of minimum (positive or negative) change to be counted; empty circles are not counted (within thresholds); filled circles are counted; (D) current count for each of the axes; yellow shaded area is the threshold for two axes together—when two axes are in the yellow area, it is counted; red shaded area is the threshold for one axis to be counted (in this example, the x-axis reached the threshold and the movement was detected). For this figure, LPcutoff = 16 Hz and threshold = 16 differential readings, which results in the standard deviation of 1.2 for the distribution of sample direction count. SDs (2 axes) and + SD (1 axis) were set to 4 and 3, respectively.