Fig. 3: Back EMF constant depends on servomotor axle orientation and distance from MRI scanner isocenter.

The servomotor back EMF constant (\({k}_{{{\mbox{E}}}}\)) with respect to the servomotor axle orientation \((\theta)\) is shown in (a). All measurements in (a) were performed with the servomotor located at the MRI scanner isocenter. Dotted line in (a) is the value of \({k}_{{{\mbox{E}}}}\) (measured at \(\theta =90^\circ\)) multiplied by \({{\sin }}(\theta )\). Agreement between measurement data (solid circles) and dotted line confirms the angular dependence predicted by Eq. (2) The back EMF constant with respect to the distance between the servomotor location and the MRI scanner isocenter is shown in (b). All measurements in (b) were performed for \(\theta =90^\circ\). Error bars in (a) and (b) denote the standard deviation of 9 measurements obtained for each scenario.