Experimental Implementation of Automatic Control of Posture-Dependent Stimulation in an Implanted Standing Neuroprosthesis

Figure 4

The sample CoP profiles of the subject (blue) and the moving circle (red) of the two consecutive leaning movements during the tracking task. The top panel displays the CoP profiles in the AP direction, while the bottom panel displays the CoP profiles in the ML direction. Each movement is considered a separate repetition, which consists of a movement onset, dwell period, and movement offset. Movement onsets are indicated as the time point in which the moving circle initiates movement from the nominal starting position to the end of the specified path. Upon reaching the end of the specified path, the moving circle dwells there for 3 seconds. When the dwell period ends, the moving circle returns to the nominal position and remains there until it initiates travel along the next path. The first time point at which the moving circle acquires the nominal starting position on the return is the movement offset. Based on the orientation of the laboratory coordinate system, postural adjustments in the forward direction are indicated as CoP_AP increasing from the nominal starting position. The postural shifts towards the left are indicated as CoP_ML increasing from the nominal. Thus, in both repetitions, the subject was tracking the moving circle in the forward-left direction.