Orthogonal Pulse-Width-Modulation for Combined Electromagnetic Actuation and Localization
Denis von Arx, Bradley J. Nelson, Quentin Boehler
AI summary
Problem
Current electromagnetic navigation systems require bulky sensor arrays or high reactive power to simultaneously actuate and localize tethered medical devices, limiting miniaturization and efficiency.
Approach
Each electromagnet is driven at a distinct PWM frequency, creating orthogonal magnetic ripple fields that are measured by compact pickup coils on the device tip to estimate pose via frequency-domain separation and calibration fieldmaps.
Key results
- 6-DoF localization at 77 Hz using only PWM ripple fields
- Mean accuracy below 2 mm in position and 2° in orientation
- Successful catheter navigation in free space and vascular phantom
- Eliminates need for additional Hall sensors or high reactive power
Why it matters
Enables compact, real-time magnetic tracking and control for minimally invasive surgical tools without bulky sensors or excessive power demands.
Abstract
Electromagnetic Navigation Systems can be used to remotely guide medical devices such as magnetic catheters or guidewires, holding potential in a variety of minimally invasive surgical applications. This paper introduces a method to simul- taneously actuate and localize a tethered magnetic device with embedded sensor pickup coils using a single system. Six-degree- of-freedom localization is achieved by driving the electromagnets of the Electromagnetic Navigation System with mutually orthog- onal pulse-width-modulated voltages of different frequencies. The method is demonstrated using a human-scale system composed of three electromagnets to actuate and localize a magnetic catheter prototype with pickup coils embedded at its tip. In this case, the pose is estimated at a rate of 77 Hz, with a typical mean accuracy below 2 mm in position and 2◦in orientation.