Electromagnetic Navigation Systems enable remote actuation of untethered micro and nanorobots, as well as the precise control of magnetic surgical tools for minimally invasive medical procedures. Accurate modeling of the magnetic fields generated by the electromagnets composing these systems is essential for achieving reliable and precise navigation. Existing modeling approaches either neglect nonlinear effects such as electromagnet saturation or fail to ensure that the field predictions are physically consistent. These limitations can lead to significant prediction errors, particularly in the estimation of field gradients, which directly impacts force calculations. As a result, inaccurate gradient predictions degrade force control performance, limiting the precision of magnetic actuation. In this work, we investigate physics-informed and data-driven modeling techniques to improve the accuracy of magnetic field and gradient predictions. Additionally, we introduce an approach for solving the inverse problem, developing models capable of predicting the required electromagnet currents to generate a desired magnetic field and gradient based on this approach. By incorporating physical constraints into the models, we enhance the predictive accuracy and physical consistency of the field estimates. In the experimental section, we demonstrate the benefits of these methods to enable improved force control in open-loop for untethered robots using a small-scale Electromagnetic Navigation System.

In remote magnetic navigation, a magnetic navigation system is used to generate magnetic fields to apply mechanical wrenches to steer a magnetic object. This technique can be applied to navigate untethered micro- and nanorobots, as well as tethered magnetic surgical tools for minimally invasive medicine. The design and characterization of these systems have been extensively investigated over the past decade. The determination of the region in space in which these systems can operate has yet to be formalized within the research community. This region is commonly referred to as the “workspace” and constitutes a central concept for any class of robotic system. We focus on magnetic navigation systems comprised of electromagnets and propose a first set of definitions for a magnetic workspace, a methodology to determine it, and evaluation metrics to analyze its characteristics. Our methodology and tools are illustrated with several examples of planar and spatial electromagnetic magnetic navigation systems for both didactic and realistic navigation scenarios.

The use of magnetic fields and field gradients to move magnetic material and devices within the human body has a surprisingly long history. Over the past two decades, there has been renewed interest in this area with the growth of magnetic medical microrobots. In this article, we focus on the state-of-the-art and future directions for magnetically actuated medical robots from anin vivoperspective. We initially review the history and relevant physics followed by a discussion on the limitedin vivoresearch efforts that investigate magnetically guided devices. Our focus is on magnetically guided tethered probes, untethered devices (microrobots and nanorobots), and magnetic navigation systems that have been or could be utilizedin vivoto provide increased control and safety for the physician and patient.