# Development of a Robot-Assisted TMS Localization System Using Dual Capacitive Sensors for Coil Tilt Detection

## TL;DR

A robot-assisted TMS system using a 3D camera and sensors improves coil placement accuracy and safety for brain stimulation.

## Contribution

A cost-effective, markerless robotic TMS system using 3D cameras and textile sensors for coil localization and tilt detection is developed.

## Key findings

- The system reliably targets the C3 motor hotspot with valid MEPs after minimal calibration.
- Balanced sensor readings and moderate contact pressure increase MEP amplitudes, indicating effective coil alignment.
- The system meets safety standards and reduces setup time and operator dependency compared to traditional methods.

## Abstract

What are the main findings?
A robotic-assisted TMS system using a 3D camera to detect facial landmarks can successfully locate the C3 motor hotspot with minimal calibration.Sensor ratio balance and moderate contact pressure result in higher MEP amplitudes, indicating effective coil–scalp alignment and tilt detection.

A robotic-assisted TMS system using a 3D camera to detect facial landmarks can successfully locate the C3 motor hotspot with minimal calibration.

Sensor ratio balance and moderate contact pressure result in higher MEP amplitudes, indicating effective coil–scalp alignment and tilt detection.

What are the implications of the main findings?
Low-cost textile capacitive sensors are able to provide real-time feedback on coil positioning and tilt, enabling safer and more reproducible TMS procedures.Robotic assistance has the potential to reduce setup time and operator dependency compared to traditional manual localization, improving efficiency and consistency in clinical and research settings.

Low-cost textile capacitive sensors are able to provide real-time feedback on coil positioning and tilt, enabling safer and more reproducible TMS procedures.

Robotic assistance has the potential to reduce setup time and operator dependency compared to traditional manual localization, improving efficiency and consistency in clinical and research settings.

Transcranial Magnetic Stimulation (TMS) is a non-invasive technique for neurological research and therapy, but its effectiveness depends on accurate and stable coil placement. Manual localization based on anatomical landmarks is time-consuming and operator-dependent, while state-of-the-art robotic and neuronavigation systems achieve high accuracy using optical tracking with head-mounted markers and infrared cameras, at the cost of increased system complexity and setup burden. This study presents a cost-effective, markerless robotic-assisted TMS system that combines a 3D depth camera and textile capacitive sensors to assist coil localization and contact control. Facial landmarks detected by the depth camera are used to estimate the motor cortex (C3) location without external tracking markers, while a dual textile-sensor suspension provides compliant “soft-landing” behavior, contact confirmation, and coil-tilt estimation. Experimental evaluation with five participants showed reliable C3 targeting with valid motor evoked potentials (MEPs) obtained in most trials after initial calibration, and tilt-verification experiments revealed that peak MEP amplitudes occurred near balanced sensor readings in 12 of 15 trials (80%). The system employs a collaborative robot designed in accordance with international human–robot interaction safety standards, including force-limited actuation and monitored stopping. These results suggest that the proposed approach can improve the accessibility, safety, and consistency of TMS procedures while avoiding the complexity of conventional optical tracking systems.