FT-Control - Robotized Transcranial Magnetic Stimulation - page 95

Table 5.2 Calculated force and torque errors at rest for each coil used
MCF-75 MC-B35 70 mm C-B60 MCF-P-B65 MC-125 MC-B70 MCF-B65

Forces (N)
Mean 2 : 40 1 : 98 1 : 07 2 : 17 1 : 81 1 : 36 2 : 80 1 : 54

0 : 21 0 : 61 0 : 18 0 : 29 0 : 39 0 : 31 0 : 19 0 : 52 SD

Torques (Nm)
Mean 0 : 31 0 : 33 0 : 17 0 : 46 0 : 39 0 : 20 0 : 25 0 : 36

SD 0 : 22 0 : 25 0 : 12 0 : 25 0 : 29 0 : 08 0 : 06 0 : 19

The mean error (mean) with its Standard Deviation (SD) are listed

(in coil coordinates) is required for coil placement. The z-directed error has been
below the threshold of 2 N in all the measurements.

5.3.2 Hand-Assisted Positioning

As an indicator for the increased usability with the hand-assisted positioning
method, we have evaluated the positioning time for a hot-spot search. We have
compared the required positioning time when using the hand-assisted positioning
with the time needed for positioning using the current robotized TMS control
software and the robot controller.
The positioning time needed for an experienced user is summarized in
Table 5.3 . The measured times show that on average between 03:00 and
03:20 min are needed when using hand-assisted positioning. When using the
robotized TMS software between 04:00 and 04:20 min are required on average if
no manual robot pre-positioning is needed (setups 1 and 2). However, an addi-
tional manual robot pre-positioning requires more than one minute extra-time for
an experienced user (setup three). Thus, almost 40 % saving of time can be
achieved by hand-assisted positioning—even for experienced users.
For an inexperienced user, manual robot pre-positioning is even more inter-
esting as they are typically not skilled in robot control mechanisms. For the first
run of positioning with the robot controller, the user hits the head phantom with the
coil when trying to pre-position the robot. For the other two runs the pure pre-
positioning time was approximately five minutes. In contrast, pre-positioning the

Table 5.3 Mean positioning time for an experienced user for hot-spot search based on nine
stimulation points and five single runs using the control software of the robotized TMS system
and the presented hand-assisted positioning
Setup FT control TMS software

1 03:05 min ( 24 s) 04:04 min ( 22 s)

2 03:07 min ( 16 s) 04:15 min ( 24 s)

3 03:20 min ( 21 s) 05:24 min ( 54 s)

The standard deviation is displayed in brackets