Orthogonal Pulse-Width-Modulation for Combined Electromagnetic Actuation and Localization

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 simultaneously 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 orthogonal 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<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> in orientation.