scholarly journals A virtual platform for real-time performance analysis of electromagnetic tracking systems for surgical navigation

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 103
Author(s):  
Mattia Alessandro Ragolia ◽  
Filippo Attivissimo ◽  
Attilio Di Nisio ◽  
Anna Maria Lucia Lanzolla ◽  
Marco Scarpetta
Keyword(s):  
Magnetic Field ◽  
Real Time ◽  
Surgical Navigation ◽  
Surgical Instruments ◽  
Accurate Estimation ◽  
Electromagnetic Tracking ◽  
Tracking Systems ◽  
Virtual Platform ◽  
Magnetic Field Generator ◽  
The Magnetic Field

<p class="Abstract">Electromagnetic Tracking Systems (EMTSs) are widely used in surgical navigation, allowing to improve the outcome of diagnosis and surgical interventions, by providing the surgeon with real-time position of surgical instruments during medical procedures. However, particular effort was dedicated to the development of efficient and robust algorithms, to obtain an accurate estimation of the instrument position for distances from the magnetic field generator beyond 0.5 m. Indeed, the main goal is to improve the limited range of current commercial systems, which strongly affects the freedom of movement of the medical team. Studies are currently being conducted to optimize the magnetic field generator configuration (both geometrical arrangements and electrical properties) since it affects tracking accuracy. In this paper, we propose a virtual platform for assessing the performance of EMTSs for surgical navigation, providing real-time results and statistics, and allowing to track instruments both in real and simulated environments. Simulations and experimental tests are performed to validate the proposed virtual platform, by employing it to assess the performance of a real EMTS. The platform offers a real-time tool to analyze EMTS components and field generator configurations, for a deeper understanding of EMTS technology, thus supporting engineers during system design and characterization.</p>

scholarly journals Distorter Characterisation Using Mutual Inductance in Electromagnetic Tracking

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3059 ◽  
Author(s):  
Herman Jaeger ◽  
Pádraig Cantillon-Murphy
Keyword(s):  
Magnetic Field ◽  
Measurement Errors ◽  
Surgical Navigation ◽  
Sensor Arrays ◽  
Medical Robotics ◽  
Mutual Inductance ◽  
Electromagnetic Tracking ◽  
Novel Method ◽  
Transmitter Design ◽  
The Magnetic Field

Electromagnetic tracking (EMT) is playing an increasingly important role in surgical navigation, medical robotics and virtual reality development as a positional and orientation reference. Though EMT is not restricted by line-of-sight requirements, measurement errors caused by magnetic distortions in the environment remain the technology’s principal shortcoming. The characterisation, reduction and compensation of these errors is a broadly researched topic, with many developed techniques relying on auxiliary tracking hardware including redundant sensor arrays, optical and inertial tracking systems. This paper describes a novel method of detecting static magnetic distortions using only the magnetic field transmitting array. An existing transmitter design is modified to enable simultaneous transmission and reception of the generated magnetic field. A mutual inductance model is developed for this transmitter design in which deviations from control measurements indicate the location, magnitude and material of the field distorter to an approximate degree. While not directly compensating for errors, this work enables users of EMT systems to optimise placement of the magnetic transmitter by characterising a distorter’s effect within the tracking volume without the use of additional hardware. The discrimination capabilities of this method may also allow researchers to apply material-specific compensation techniques to minimise position error in the clinical setting.

scholarly journals Noninvasive muscle activity imaging using magnetography

2020 ◽  
Vol 117 (9) ◽  
pp. 4942-4947 ◽  
Author(s):  
Rodolfo R. Llinás ◽  
Mikhail Ustinin ◽  
Stanislav Rykunov ◽  
Kerry D. Walton ◽  
Guilherme M. Rabello ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Contrast Media ◽  
Electrical Activity ◽  
Real Time ◽  
Human Body ◽  
Muscle Activity ◽  
Muscular Activity ◽  
Exponential Increase ◽  
Somatic Musculature ◽  
The Magnetic Field

A spectroscopic paradigm has been developed that allows the magnetic field emissions generated by the electrical activity in the human body to be imaged in real time. The growing significance of imaging modalities in biology is evident by the almost exponential increase of their use in research, from the molecular to the ecological level. The method of analysis described here allows totally noninvasive imaging of muscular activity (heart, somatic musculature). Such imaging can be obtained without additional methodological steps such as the use of contrast media.

The long-term optical activity of the propellers AE Aquarii and AR Scorpii

2020 ◽  
Vol 72 (2) ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Magnetic Field ◽  
Real Time ◽  
Optical Activity ◽  
White Dwarf ◽  
Transient Decrease ◽  
Mass Outflow ◽  
Orbital Modulation ◽  
The Magnetic Field

Abstract This analysis of the long-term optical activity of the propellers AE Aqr and AR Sco uses data from the Catalina Real-time Transient Survey, DASCH, and AAVSO. The site and character of the emissions from the phenomena caused by the magnetic field of the white dwarf (WD) vary from system to system. The histogram of intensities of the ensemble of flares of AE Aqr suggests that the long-term activity consists of a large variety of the peak magnitudes of the flares, with the probability of their detection gradually decreasing with increasing intensity. Any increase of activity only leads to an increase of the number of blobs of the transferring matter. We also detected a season with a transient decrease or even a cessation of the mass outflow from the donor to the lobe of the WD. The very strong orbital modulation of AR Sco is most stable in the phases of the extrema of brightness for about a century; its minor changes suggest that the trailing side of the synchrotron-emitting region is more unstable than the leading side.

scholarly journals MHD simulation of flare situation above the active region AR 10365 in the real time scale.

2020 ◽  
Author(s):  
A.I. Podgorny ◽  
◽  
I.M. Podgorny ◽  
A.V. Borisenko ◽  
◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Real Time ◽  
Time Scale ◽  
Rapid Change ◽  
Field Configuration ◽  
Mhd Simulation ◽  
The Real ◽  
Real Time Scale ◽  
The Magnetic Field

Since the configuration of the magnetic field in the corona, where solar flares appear, cannot be determined from observations, to study the flare situation, a numerical magnetohydrodynamic (MHD) simulation is carried out above the active region. MHD simulation performed in a greatly reduced (10 000 times) time scale permit to obtain results on the study of the solar flare mechanism, but the magnetic field configuration was distorted, especially near the photospheric boundary, due to the unnaturally rapid change in the field on the photosphere. For a more accurate study of the flare situation, MHD simulation in the real time scale was performed above the active region of AR 10365, which was made possible through the use of parallel calculations. The MHD simulation in the real scale of time above the AR 10365 during the first day of evolution showed the appearance of current density maxima with singular X-type line and plasma flow, which have to cause to the formation of a current sheet.

scholarly journals Real-time 3-D hybrid simulation of Titan's plasma interaction during a solar wind excursion

2009 ◽  
Vol 27 (9) ◽  
pp. 3349-3365 ◽  
Author(s):  
S. Simon
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Real Time ◽  
Plasma Flow ◽  
Time Scale ◽  
Hybrid Simulation ◽  
The Moon ◽  
Plasma Interaction ◽  
Plasma Environment ◽  
The Magnetic Field

Abstract. The plasma environment of Saturn's largest satellite Titan is known to be highly variable. Since Titan's orbit is located within the outer magnetosphere of Saturn, the moon can leave the region dominated by the magnetic field of its parent body in times of high solar wind dynamic pressure and interact with the thermalized magnetosheath plasma or even with the unshocked solar wind. By applying a three-dimensional hybrid simulation code (kinetic description of ions, fluid electrons), we study in real-time the transition that Titan's plasma environment undergoes when the moon leaves Saturn's magnetosphere and enters the supermagnetosonic solar wind. In the simulation, the transition between both plasma regimes is mimicked by a reversal of the magnetic field direction as well as a change in the composition and temperature of the impinging plasma flow. When the satellite enters the solar wind, the magnetic draping pattern in its vicinity is reconfigured due to reconnection, with the characteristic time scale of this process being determined by the convection of the field lines in the undisturbed plasma flow at the flanks of the interaction region. The build-up of a bow shock ahead of Titan takes place on a typical time scale of a few minutes as well. We also analyze the erosion of the newly formed shock front upstream of Titan that commences when the moon re-enters the submagnetosonic plasma regime of Saturn's magnetosphere. Although the model presented here is far from governing the full complexity of Titan's plasma interaction during a solar wind excursion, the simulation provides important insights into general plasma-physical processes associated with such a disruptive change of the upstream flow conditions.

Integrated Real-Time Calibration of Electromagnetic Tracking of User Motions for Engineering Applications in Virtual Environments

2002 ◽  
Vol 124 (4) ◽  
pp. 623-632 ◽  
Author(s):  
Uma Jayaram ◽  
Roglenda Repp
Keyword(s):  
Virtual Environments ◽  
Real Time ◽  
Virtual Environment ◽  
Physical World ◽  
Electromagnetic Tracking ◽  
Tracking Systems ◽  
Calibration System ◽  
Time Calibration ◽  
Calibration Accuracy ◽  
Mathematical Techniques

A real-time integrated calibration system for virtual reality environments has been developed that enables accurate electromagnetic tracking of user motions. Electromagnetic tracking systems suffer degradation in accuracy due to the presence of metals and other electromagnetic distortions in the environment. Calibration of the virtual environment to account for these distortions is essential for VR applications in engineering where correlation between the virtual environment and the physical world is important. The major contribution of the paper is the presentation of a comprehensive methodology for calibrating the VR space, the numerical/mathematical techniques proposed for the calibration, and case studies for calibration accuracy and execution time to enable using these techniques in real time in an integrated setup.

scholarly journals Autofocus Entropy Repositioning Method Bioinspired in the Magnetic Field Memory of the Bees Applied to Pollination

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6198
Author(s):  
Daniel de Matos Luna dos Santos ◽  
Ewaldo Eder Carvalho Santana ◽  
Paulo Fernandes da Silva Junior ◽  
Jonathan Araujo Queiroz ◽  
João Viana da Fonseca Neto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Feature Extraction ◽  
Real Time ◽  
Unsupervised Method ◽  
Color Characteristics ◽  
Magnetic Declination ◽  
Positioning Method ◽  
The Magnetic Field ◽  
Robust Response

In this paper, a bioinspired method in the magnetic field memory of the bees, applied in a rover of precision pollination, is presented. The method calculates sharpness features by entropy and variance of the Laplacian of images segmented by color in the HSV system in real-time. A complementary positioning method based on area feature extraction between active markers was developed, analyzing color characteristics, noise, and vibrations of the probe in time and frequency, through the lateral image of the probe. From the observed results, it can be seen that the unsupervised method does not require previous calibration of target dimensions, histogram, and distances involved in positioning. The algorithm showed less sensitivity in the extraction of sharpness characteristics regarding the number of edges and greater sensitivity to the gradient, allowing unforeseen operation scenarios, even in small sharpness variations, and robust response to variance local, temporal, and geophysical of the magnetic declination, not needing luminosity after scanning, with the two freedom of degrees of the rotation.

scholarly journals Single Pulse Calibration of Magnetic Field Sensors Using Mobile 43 kJ Facility

2015 ◽  
Vol 15 (5) ◽  
pp. 244-247 ◽  
Author(s):  
Audrius Grainys ◽  
Jurij Novickij ◽  
Tomaš Stankevič ◽  
Voitech Stankevič ◽  
Vitalij Novickij ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
High Power ◽  
Pulse Shaping ◽  
Single Pulse ◽  
Reverse Voltage ◽  
Magnetic Field Sensors ◽  
Pulse Calibration ◽  
Magnetic Field Generator ◽  
The Magnetic Field

Abstract In this work we present a mobile 43 kJ pulsed magnetic field facility for single pulse calibration of magnetic field sensors. The magnetic field generator is capable of generating magnetic fields up to 40 T with pulse durations in the range of 0.3-2 ms. The high power crowbar circuit is used for the reverse voltage protection and pulse shaping purposes. The structure, the development challenges and the implemented solutions to improve the facility for the calibration of the magnetic field sensors are overviewed. The experimental data of the application of the proposed generator for the calibration of manganite magnetic field sensors are presented.

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