Hand-assisted positioning and contact pressure control for motion compensated robotized transcranial magnetic stimulation.

Purpose: In Transcranial Magnetic Stimulation (TMS), the principle of magnetic induction is used to stimulate the brain non-invasively. Currently, robotic TMS systems are developed to guarantee precise coil placement on the head and in this way achieve the repeatability of stimulation results. However, usability concerns such as the complicated coil positioning are still unsolved for motion compensated robotized TMS. In this paper, we demonstrate the integration of a force-torque control into a robotic TMS system to improve usability, safety, and precision.

Methods: We integrated a force-torque sensor between robot effector and TMS coil. Coil calibration and gravity compensation have been developed. Based on them, we have implemented hand-assisted positioning for easy and fast coil placement. Furthermore, we have enhanced the existing motion compensation algorithms with a contact pressure control.

Results: The positioning time for an experienced user decreased up to 40% with the help of hand-assisted positioning in comparison with not hand-assisted robotized positioning. It also enabled an inexperienced user to use the system safely.

Conclusion: Integration of a force-torque control into the motion compensated robotized TMS system greatly enhances system's usability, which is a prerequisite for integration in the clinical workflow and clinical acceptance.