70
order to simplify the remaining equations. A rad is defined as a length equal to the radius of the cylindrical stimulus screen and, although designed to be 80 cm, has been empirically found to be 77 cm (see section 2.3.2). The generalized expression of these four equations for a coordinate value in rads is then
(6) CV = ((CA)2 (CB)2 + 351(CB CA))/12498510 where CA and CB are sp-mic pair raw position data that are picked by the SCS software based on its error checking and correcting functions. See Table 1, section 2.1.2.
The next four equations are used to calculate the
stimulus position for the normalized case of unity feedback gain. This case corresponds to the stimulus moving with the subject's head so that it appears stationary to the subject. Referring to Figure 4, section 2.1.2, the intent is to calculate the stimulus angle e such that the stimulus projection line (L3) intersects the subject's line of sight (a segment of line L2) at the surface of the screen. A subject standing at the center of the screen (on the axis of rotation) and facing straight ahead (along the Y axis in its positive direction) would result in e = 00. The equation of the line that includes the subject's line of sight (L2) is defined as
(7) x = mY + b
meaning that m = 0 corresponds to the subject facing straight ahead (parallel to the Y axis). Line L2 is assumed
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