Biomedical Engineering Reference
We have shown that head motion occurs during Transcranial Magnetic Stimulation
(TMS) applications and cannot be suppressed completely. Even small changes in
the position and/or orientation of the coil with respect to the target can have a
substantial impact on the stimulus intensity and therefore on the stimulation out-
come. Robotized TMS with active motion compensation, however, effectively
offsets these changes, thus maintaining the initial magnitude and orientation
throughout treatment. Therefore, robotized TMS outperforms hand-held (neuro-
navigated) TMS in terms of accuracy, reproducibility and repeatability.
With the developed extensions, robotized TMS now facilitates safety and
clinical applicability due to the increased usability.
An additional marker is now attached to the robot's third link. With knowledge
of the rigid transform from the robot's third link to the marker, the calibration
between robot and tracking system can be performed in Real-time. By recording
the marker's pose with respect to the tracking system and by using the robot's
forward calculation to the third link (joint four), the calibration can be directly
computed. We have shown that the accuracy of the calibration calculated this way
is only slightly behind the accuracy of a calibration calculated with hand-eye
calibration. In this way, this robust real-time calibration allows for an easy system
setup, as no additional calibration step is required prior to application and it
enhances the system's safety and precision as the calibration is continuously
controlled during operation.
The novel Force-Torque-Acceleration (FTA) sensor is mounted to the robot's
end effector between TMS coil holder and end effector. The main advantage of the
sensor is to guarantee the patient's and user's safety. The sensor operates inde-
pendently from the robot, as it combines acceleration recordings with the force/
torque measurements. The FTA sensor is directly linked to the robot's external
emergency stop and can therefore immediately stop the robot in case of a collision
or an error. Additionally, the FTA sensor greatly enhances the system's usability.
As the sensor's data communication is directly connected to the robot controller,
the user can now use an optimized hand-assisted positioning method. It allows the