What is the basis for establishing the spatial domain of the force corridor for a visual-haptic interface?

Updated: Aug 20, 2019
  • Author: Morris Steffin, MD; Chief Editor: Jonathan P Miller, MD  more...
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The spatial domain (ie, the region of body part positioning needed to achieve the movement) is computed from the initial position of the patient's body part (in this case, the wrist) and the position of the target. Position data are available from the videospace of the patient and the target.

A rough corridor is delineated below.

Patient with cerebellar tremor showing free trajec Patient with cerebellar tremor showing free trajectory of wrist and hand movement. Force corridor is represented by 3 regions of interest (ROIs) as corridor limits. Graphs indicate degree of encroachment on ROIs as an attempt is made to reach the target.

The 3 spatial regions of interest (ROIs), which are overlaid in blue, are the lateral boundaries of the corridor. Encroachment by the wrist and fingers into the ROIs represents deviation from the desired trajectory of the wrist and hand. Degrees of encroachment for each of the 3 ROIs are plotted in graphs below each panel. The corresponding fast Fourier transforms of the encroachment functions are plotted to the left of the panel, and the lowest fast Fourier transforms graph is the coherence of the upper 3 (for quantitative methods, see Steffin 1997 [9] and Steffin, 1999 [10] ). These encroachment levels can be used to control a haptic device that provides counterforce for correction of aberrant wrist movements. For simplicity, only 3 ROIs are shown as limit points on the force corridor; in practice, at least 20 ROIs would be necessary for accuracy.

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