Six-Degree-of-Freedom Localization of an Untethered Magnetic Capsule Using a Single Rotating Magnetic Dipole

Popek, Katie M.; Schmid, Thomas; Abbott, Jake J.

doi:10.1109/lra.2016.2608421

Cited by 73 publications

(38 citation statements)

References 22 publications

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“…The resulting capsule had a length of 60mm and diameter of 18mm which is approximately 2.3 times times the size of commercially available capsule endoscopes. Similarly, Popek et al (2017) used the Allegro A1392 Hall effect sensors and the CC2530 in their capsule. The resulting capsule had a length of 42mm and diameter of 13.5mm which is approximately 1.4 times the size of commercially available capsule endoscopes (Popek et al 2017).…”

Section: System and Software Environmentmentioning

confidence: 99%

“…Furthermore, we note that any source of magnetic field that, for the purpose of actuation, can be sufficiently approximated by the point-dipole magnetic field model exhibits the singularity described in Section 3. This affects any pose estimation method that uses a single source of magnetic field with the exception of methods that make multiple measurements while rotating or translating the magnet, such as the one used by Popek et al (2017). Therefore, the methods described herein can be adopted in other systems with different schemes of magnetic actuation.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced real-time pose estimation for closed-loop robotic manipulation of magnetically actuated capsule endoscopes

Taddese

Slawinski

Pirotta

et al. 2018

The International Journal of Robotics Research

111

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Pose estimation methods for robotically guided magnetic actuation of capsule endoscopes have recently enabled trajectory following and automation of repetitive endoscopic maneuvers. However, these methods face significant challenges in their path to clinical adoption including the presence of regions of magnetic field singularity, where the accuracy of the system degrades, and the need for accurate initialization of the capsule's pose. In particular, the singularity problem exists for any pose estimation method that utilizes a single source of magnetic field if the method does not rely on the motion of the magnet to obtain multiple measurements from different vantage points. We analyze the workspace of such pose estimation methods with the use of the point-dipole magnetic field model and show that singular regions exist in areas where the capsule is nominally located during magnetic actuation. Since the dipole model can approximate most magnetic field sources, the problem discussed herein pertains to a wider set of pose estimation techniques. We then propose a novel hybrid approach employing static and time-varying magnetic field sources and show that this system has no regions of singularity. The proposed system was experimentally validated for accuracy, workspace size, update rate and performance in regions of magnetic singularity. The system performed as well or better than prior pose estimation methods without requiring accurate initialization and was robust to magnetic singularity. Experimental demonstration of closed-loop control of a tethered magnetic device utilizing the developed pose estimation technique is provided to ascertain its suitability for robotically guided capsule endoscopy. Hence, advances in closed-loop control and intelligent automation of magnetically actuated capsule endoscopes can be further pursued toward clinical realization by employing this pose estimation system.

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Section: System and Software Environmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced real-time pose estimation for closed-loop robotic manipulation of magnetically actuated capsule endoscopes

Taddese

Slawinski

Pirotta

et al. 2018

The International Journal of Robotics Research

111

View full text Add to dashboard Cite

show abstract

“…position and orientation along all axes. These localization noise magnitudes were selected as they are near the upper boundary of uncertainty observed in physical systems [9], [12], [16], [35]- [37]. Each set of experiments consisted of both "static" and "dynamic" trials.…”

Section: B Simulation Studymentioning

confidence: 99%

Sensitivity Ellipsoids for Force Control of Magnetic Robots With Localization Uncertainty

et al. 2019

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The navigation of magnetic medical robots typically relies on localizing an actuated, intracorporeal, ferromagnetic body and back-computing a necessary field and gradient that would result in a desired wrench on the device. Uncertainty in this localization degrades the precision of force transmission. Reducing applied force uncertainty may enhance tasks such as in-vivo navigation of miniature robots, actuation of magnetically guided catheters, tissue palpation, as well as simply ensuring a bound on forces applied on sensitive tissue. In this paper, we analyzed the effects of localization noise on force uncertainty by using sensitivity ellipsoids of the magnetic force Jacobian and introduced an algorithm for uncertainty reduction. We validated the algorithm in both a simulation study and in a physical experiment. In simulation, we observed reductions in estimated force uncertainty by factors of up to 2.8 and 3.1 when using one and two actuating magnets, respectively. On a physical platform, we demonstrated a force uncertainty reduction by a factor of up to 2.5 as measured using an external sensor. Being the first consideration of force uncertainty resulting from noisy localization, this work provides a strategy for investigators to minimize uncertainty in magnetic force transmission.

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“…161,162 The localization algorithm generally consists of minimizing the error between a point dipole field approximation and the measurements. 163,164 Recent developments include algorithms for 6-DOF localization, 165 multiobject tracking, 166 and the use of body attached permanent magnets as field references to compensate for unpredictable patient movements. 167 Motilis Medica SA (Switzerland) offers a commercial localization system, which employs an array of external field sensors to detect the position and orientation of a magnetic capsule.…”

Section: B6 Capsule Localization and Imagingmentioning

confidence: 99%

Magnetically guided capsule endoscopy

et al. 2017

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Wireless capsule endoscopy (WCE) is a powerful tool for medical screening and diagnosis, where a small capsule is swallowed and moved by means of natural peristalsis and gravity through the human gastrointestinal (GI) tract. The camera-integrated capsule allows for visualization of the small intestine, a region which was previously inaccessible to classical flexible endoscopy. As a diagnostic tool, it allows to localize the sources of bleedings in the middle part of the gastrointestinal tract and to identify diseases, such as inflammatory bowel disease (Crohn's disease), polyposis syndrome, and tumors. The screening and diagnostic efficacy of the WCE, especially in the stomach region, is hampered by a variety of technical challenges like the lack of active capsular position and orientation control. Therapeutic functionality is absent in most commercial capsules, due to constraints in capsular volume and energy storage. The possibility of using body-exogenous magnetic fields to guide, orient, power, and operate the capsule and its mechanisms has led to increasing research in Magnetically Guided Capsule Endoscopy (MGCE). This work shortly reviews the history and state-of-art in WCE technology. It highlights the magnetic technologies for advancing diagnostic and therapeutic functionalities of WCE. Not restricting itself to the GI tract, the review further investigates the technological developments in magnetically guided microrobots that can navigate through the various air-and fluid-filled lumina and cavities in the body for minimally invasive medicine.

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Six-Degree-of-Freedom Localization of an Untethered Magnetic Capsule Using a Single Rotating Magnetic Dipole

Cited by 73 publications

References 22 publications

Enhanced real-time pose estimation for closed-loop robotic manipulation of magnetically actuated capsule endoscopes

Enhanced real-time pose estimation for closed-loop robotic manipulation of magnetically actuated capsule endoscopes

Sensitivity Ellipsoids for Force Control of Magnetic Robots With Localization Uncertainty

Magnetically guided capsule endoscopy

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