Electromagnetic Positioning System Research Articles

Quadrupole Electromagnetic Linear Positioning System (QELPS):

In linear motion systems, including linear motors and actuators, precise and controlled linear motion is provided for various applications. However, they have several drawbacks: high costs, complexity, limited stroke length, high energy consumption, speed limitations, heat generation, noise and vibration, limited load capacity, environmental considerations, and integration challenges. High costs are especially significant for applications requiring high precision. The components' complexity and additional control electronics can increase maintenance and trouble-shooting requirements. Ensuring accurate and efficient operation necessitates regular maintenance. The limitation in stroke length, determined by the drive's size and guide length, can pose challenges for applications requiring long strokes. High energy consumption can be a concern, and speed limitations may be challenging. Managing heat generation is crucial to prevent component damage. Noise and vibration can be problematic, particularly in quiet applications. Integration challenges can arise when dealing with complex systems or automation processes. To overcome some of these drawbacks, an innovative coil configuration design for linear positioning system applications is proposed. The proposed design focuses on the Quadrupole Electromagnetic linear Positioning System (QELPS), comprising four coils generating a uniform electromagnetic field to produce a Lorentz force on the slider. The QELPS design is meticulously crafted using 3D modeling in ANSYS software, and the magnetic characteristics indicate the potential for scaling this model to different levels. The power circuit of the QELPS is simulated using ANSYS Simplorer and incorporates silicon-controlled rectifiers (SCR) and a pulse width modulation (PWM) pulse generator. The design achieves a force of 27.6 newtons with the paper presenting current and force plots in comprehensive detail. Furthermore, an interactive design algorithm is introduced, facilitating the customization of this model for various linear track dimensions. This research aims to advance linear drive technology and enhance linear motion applications by developing this new coil configuration design and harnessing the Quadrupole Electromagnetic System.

Electromagnetic Intraoperative Positioning System Is Safe and Effective as a Three-dimensional Imaging Adjunct in Endovascular Aortic Aneurysm Repair: A Safety and Feasibility Study

Electromagnetic Intraoperative Positioning System Is Safe and Effective as a Three-dimensional Imaging Adjunct in Endovascular Aortic Aneurysm Repair: A Safety and Feasibility Study

Research on Intraoperative Organ Motion Tracking Method Based on Fusion of Inertial and Electromagnetic Navigation

The intraoperative movement of target organs is currently a key and difficult problem that restricts clinical surgery diagnosis and treatment, especially radiotherapy. Unexpected posture changes can cause the deviation of the target area during the operation, thereby affecting the treatment effect and even causing severe complications. Therefore, it is necessary to track the movement of target organs in real-time and accurately to improve the effect and safety of the surgical treatment. This paper proposes an intraoperative organ motion tracking method based on the fusion of inertial navigation and electromagnetic navigation., which can directly measure the target organ's movement under non-invasive or minimally invasive conditions using the human natural cavity. The proposed method for identifying the magnetic field's interference state uses the extended Kalman filter to fuse the inertial measurement unit and the electromagnetic positioning information to achieve target organ movement tracking under different interference conditions. It effectively improved the real-time and robustness of intraoperative organ tracking. Simultaneously, based on the 9-axis inertial measurement unit and a 6-DOF electromagnetic positioning system, the catheter-type target organ tracker was developed, and then under the simulated electromagnetic interference environment, dynamic and static verification experiments were carried out, respectively. The maximum tracking error of displacement and attitude is 2.75 mm and 0.127 rad, respectively, under severe electromagnetic disturbance through experiments. Under non-electromagnetic interference conditions, its displacement and attitude's maximum tracking errors are 0.94 mm and 0.011 rad, respectively. The results prove that the target organ tracking method based on the fusion of inertial navigation and electromagnetic navigation is feasible. It can realize the tracking and measurement of the target organ's movement within the clinical permission error range.

Dynamic Electromagnetic Positioning System for Accurate Close-Range Navigation of Multirotor UAVs

An accurate close-range positioning and navigation system is the key to autonomous cruise and the fine operations of multi-rotor UAVs. In this paper, a dynamic electromagnetic positioning system is designed and implemented to accurately navigate a UAV to a very small landing zone. The system is composed of three quasi-static electromagnetic field generators (EGs) installed around the landing zone, and one electromagnetic field sensor (ES) mounted on the UAV. The ES adaptively controls its gain and adjusts the power of the EGs, so it can detect electromagnetic signals under a high SNR (signal-to-noise ratio) condition and has an anti-saturation ability. Consequently, the coordinate and azimuthal angle of the UAV can be measured during the process of the UAV approaching the landing zone. Hardware experiments demonstrate that the prototype system can effectively navigate a UAV to a small landing zone that is slightly larger than the size of the UAV, and the terminal positioning error is less than 2 cm.

Accuracy estimation of a stretch-retractable single section continuum manipulator based on inverse kinematics

Purpose The purpose of this paper is to present a novel stretch-retractable single section (SRSS) continuum manipulator which owns three degrees of freedom and higher motion range in three-dimension workspace than regular single continuum manipulator. Moreover, the motion accuracy was analyzed based on the kinematic model. In addition, the experiments were carried out for validation of the theory. Design/methodology/approach A kinematics model of the SRSS continuum manipulator is presented for analysis on bending, rotating and retracting in its workspace. To discuss the motion accuracy of the SRSS continuum manipulator, the dexterity theory was introduced based on the decomposing of the Jacobian matrix. In addition, the accuracy of motion is estimated based on the inverse kinematics and dexterity theory. To verify the presented theory, the motion of free end was tracked by an electromagnetic positioning system. According to the comparison of experimental value and theoretical analysis, the free end error of SRSS continuum manipulator is less than 6.24 per cent in the region with favorable dexterity. Findings This paper presents a new stretch-retractable continuum manipulator that the structure was composed of several springs as the backbone. Thus, the SRSS continuum manipulator could own wide motion range depending on its retractable structure. Then, the motion accuracy character of the SRSS continuum manipulator in the different regions of its workspace was obtained both theoretically and experimentally. The results show that the high accuracy region distributes in the vicinity of the outer boundary of the workspace. The motion accuracy gradually decreases with the motion position approaching to the center of its workspace. Research limitations/implications The presented SRSS continuum manipulator owns three degrees of freedom. The future work would be focused on the two-section structure which will own six degrees of freedom. Practical implications In this study, the SRSS continuum manipulator could be extended to six degrees of freedom continuum robot with two sections that is less one section than regular six degrees of freedom with three single section continuum manipulator. Originality/value The value of this study is to propose a SRSS continuum manipulator which owns three degrees of freedom and could stretch and retract to expend workspace, for which the accuracy in different regions of the workspace was analyzed and validated based on the kinematics model and experiments. The results could be feasible to plan the motion space of the SRSS continuum manipulator for keeping in suitable accuracy region.

Positioning system on impulse ultrawideband fields

Background: The systems of positioning on the base of radiowaves are widely used both in a global scale and for the exact position-finding of objects indoors. Global systems of positioning usually need valuable high-quality time synchronization, assume substantial errors at improper weather, at falling of radio waves on the earth surface at small angles, shading of transceivers by large obstacles, and at presence of radio electronic interferences of different nature. Objectives Investigation of the new system of positioning on the ultrawideband impulse electromagnetic fields and their analysis by an artificial neural network is proposed. Materials and methods: The phenomenon of the pulse form change on angle of radiation by antenna is used for the determination of the position of ultrawideband receiver. At first, the two-dimensional case of the problem is considered. Exciting two antennas separated at known distance by means of different impulse signals it is possible to define the place of location of receiver if we know the angles of arrival of impulses from each antenna. The ultrawideband bow-tie antennas excited by the Gaussian impulses of different durations are used as irradiators. The forms of the received impulses are calculated by method of Finite Differences in Time Domain (FDTD). The classification of the time forms of the received electromagnetic waves from different antennas at different angles of radiation is carried out by a deep neural network. Results: It is shown that for the classification the artificial neural network pays special attention to the intervals of time where the received impulse changes quickly. The four-layer network faultlessly distinguishes the obtained signals from different antennas. The numerical calculation of the electromagnetic problem and artificial neural network training show the possibility of determination of angles of radiation by the network with the accuracy of one degree excepting some cases. Using the basis between antennas of 50 meters the precision of receiver position determination is not worse than 62 cm in the square domain of 50 meter size eliminating some angles where the accuracy falls to 2 meters. Conclusion: Property of antennas to change the form of radiated ultrawideband impulses for different angles can be used for the construction of the new system of positioning that does not need the time synchronization with transmitters. The proposed system can be effectively employed indoors. The distinctive feature of the impulse electromagnetic wave positioning system is its immunity to the existent narrowband electromagnetic waves.

Clinical feasibility and positional stability of an implanted wired transmitter in a novel electromagnetic positioning system for prostate cancer radiotherapy

PurposeThree aspects of the RayPilot real-time tracking system were investigated: (1) feasibility of the transmitter with respect to implantation and explantation procedures, (2) user and patients’ experiences and (3) quantification of the transmitter positional stability in relation to fiducial markers. Methods and materialsTen prostate cancer patients scheduled for radiotherapy received transmitter implantation in the prostate, concomitantly with fiducial markers. Transmitter and marker positions were assessed in 3D by orthogonal kV-imaging at daily treatment setup in eight patients. ResultsThe transmitter was successfully implanted in all patients. Patients reported mild to moderate discomfort and impact on daily activities due to the implant but overall subjective tolerability was good. One patient had spontaneous explantation of the transmitter after four fractions. One patient had transmitter 3D shifts >9 mm, but also inter-marker shifts >6 mm. The mean inter-marker shift in the remaining patients was <1 mm. In four patients, maximum transmitter 3D shifts were 5–7 mm (mean >2 mm). In three patients, mean transmitter 3D shifts were <2 mm. ConclusionsImplantation and explantation of the transmitter is generally feasible and safe. Patient tolerability is good overall. However, due to interfractional transmitter positional instability in this cohort, use of the system for real-time tracking should be combined with other daily setup techniques.

Identifying the position of the right atrium to align pressure transducer for CVP : Spirit level or 3D electromagnetic positioning?

The central venous pressure, CVP, is an important variable in the management of selected perioperative and intensive care cases and in clinical decision support systems, CDSS. In current routine, when measuring CVP the health care provider may use anatomical landmarks and a spirit level, SL, to adjust the pressure transducer to the level of the tricuspid valve, i.e. the phlebostatic axis. The aim of the study was to assess the agreement in the postoperative setting between the SL method and electromagnetic 3D positioning (EM). CVP was measured with patients in positions dictated by nursing routines. The staff members measured CVP using SL to position the transducer at the perceived phlebostatic level. This position was compared to coordinates based on an electromagnetic field with external sensors at anatomical landmarks and an internal sensor in the CV catheter for 3D determination of the phlebostatic axis. An electronic survey took bearing on the accepted error in measurement among colleagues at the department. There was a clinically relevant difference between the CVP measured by the staff members and the CVP based on the 3D EM positioning. The limits of agreement extended in excess of ±8mmHg and half of the measurements had deviations outside an accepted error range of ±2.5mmHg. There was a large variation in CVP measurements when assessing the agreement with the current method. This may indicate the need for improvement in accuracy, e.g. using the electromagnetic field positioning system, in association with routine monitoring and clinical decision support systems.

Algorithm for calibration of the electromagnetic positioning system

Consideration was given to the problem of relative positioning with the use of variable magnetic field. Preliminary calibration of the positioning system was shown to be necessary to increase precision in determination of the navigation parameters. Various approaches to the calibration experiment were discussed. Efficient calibration algorithms were proposed, and a numerical example of solving a calibration problem was presented.

The first clinical implementation of electromagnetic transponder-guided MLC tracking.

We report on the clinical process, quality assurance, and geometric and dosimetric results of the first clinical implementation of electromagnetic transponder-guided MLC tracking which occurred on 28 November 2013 at the Northern Sydney Cancer Centre. An electromagnetic transponder-based positioning system (Calypso) was modified to send the target position output to in-house-developed MLC tracking code, which adjusts the leaf positions to optimally align the treatment beam with the real-time target position. Clinical process and quality assurance procedures were developed and performed. The first clinical implementation of electromagnetic transponder-guided MLC tracking was for a prostate cancer patient being treated with dual-arc VMAT (RapidArc). For the first fraction of the first patient treatment of electromagnetic transponder-guided MLC tracking we recorded the in-room time and transponder positions, and performed dose reconstruction to estimate the delivered dose and also the dose received had MLC tracking not been used. The total in-room time was 21 min with 2 min of beam delivery. No additional time was needed for MLC tracking and there were no beam holds. The average prostate position from the initial setup was 1.2 mm, mostly an anterior shift. Dose reconstruction analysis of the delivered dose with MLC tracking showed similar isodose and target dose volume histograms to the planned treatment and a 4.6% increase in the fractional rectal V60. Dose reconstruction without motion compensation showed a 30% increase in the fractional rectal V60 from that planned, even for the small motion. The real-time beam-target correction method, electromagnetic transponder-guided MLC tracking, has been translated to the clinic. This achievement represents a milestone in improving geometric and dosimetric accuracy, and by inference treatment outcomes, in cancer radiotherapy.

High precision transponder localization using a novel electromagnetic positioning system in patients with localized prostate cancer

Background and purpose The Micropos 4DRT system is being developed to provide accurate, precise, objective, and continuous target localization during radiotherapy. This study involves the first in vivo use of the system, aiming to evaluate the localization accuracy of this electromagnetic positioning technique compared with radiographic localization and to assess its real-time tracking ability. Material and methods An active positioning marker was inserted in the prostatic urethra of 10 patients scheduled to receive radiotherapy for localized prostate cancer. A receiving sensor plate (antennae system) was placed at a known position in the treatment tabletop. Initial in vivo system calibrations were performed in three subjects. Ten additional patients were then enrolled in a study arm that compared radiographic transponder location to radiotransponder location simultaneously acquired by the Micropos 4DRT system. Frontal and side radiographs were taken with the radiopaque transponder located at three different positions within the prostatic urethra. Results The transponder insertions were all successful and without complications. Comparison of the transponder location as per the Micropos 4DRT system with the radiographic transponder localization showed an average (±SD) absolute and relative 3D difference of 2.7 ± 1.2 and 1.7 ± 1.0 mm, respectively. Continuous transponder tracking capability was also demonstrated. Conclusions Electromagnetic positioning using the Micropos transponder system is feasible in vivo. Evaluation of this novel non-ionizing localization system, in this study using a transponder positioned in the prostatic urethra, indicates transponder localization accuracy to isocenter comparable with X-ray localization of a radiopaque marker.

Towards an EMG-Controlled Prosthetic Hand Using a 3-D Electromagnetic Positioning System

This paper proposes a novel method of using electromyographic (EMG) potentials generated by the forearm muscles during hand and finger movements to control an artificial prosthetic hand worn by an amputee. Surface EMG sensors were used to record a sequence of forearm EMG potential signals via a PC sound card and a novel 3-D electromagnetic positioning system together with a data-glove mounted with 11 miniature electromagnetic sensors used to acquire corresponding human hand pose in real time. The synchronized measurements of hand posture and associated EMG signals stored as prototypes embody a numerical expression of the current hand shape in the form of a series of data frames, each comprising a set of postures and associated EMG data. This allows a computer generated graphical 3-D model, combined with synthesized EMG signals, to be used to evaluate the approach. This graphical user interface could also enable handicapped users to practice controlling a robotic prosthetic hand using EMG signals derived from their forearm muscles. We believe this task might be made easier using a dictionary of stored task-specific prototype data frames acquired from able-bodied users. By comparing the resulting EMG data frames with stored prototypes, the most likely data frame sequence can be identified and used to control a robotic hand so that it carries out the user's desire. We explore the feasibility of this approach by applying frequency analysis on the signal derived from a multichannel EMG measurement device and identify pattern recognition techniques in the time and frequency domains to determine plausible hand shapes. This approach offers several advantages over existing methods. First, it simplifies the classification procedure, saving computational time and the requirement for the optimization process, and second, it increases the number of recognizable hand shapes, which in turn improves the dexterity of the prosthetic hand and the quality of life for amputees. The database of EMG prototypes could be employed to optimize the accuracy of the system within a machine learning paradigm. By making a range of EMG prototype databases available, prosthetic hand users could train themselves to use their prosthesis using the visual reference afforded by the virtual hand model to provide feedback

Multi-institutional clinical experience with the Calypso System in localization and continuous, real-time monitoring of the prostate gland during external radiotherapy

To report the clinical experience with an electromagnetic treatment target positioning and continuous monitoring system in patients with localized prostate cancer receiving external beam radiotherapy. The Calypso System is a target positioning device that continuously monitors the location of three implanted electromagnetic transponders at a rate of 10 Hz. The system was used at five centers to position 41 patients over a full course of therapy. Electromagnetic positioning was compared to setup using skin marks and to stereoscopic X-ray localization of the transponders. Continuous monitoring was performed in 35 patients. The difference between skin mark vs. the Calypso System alignment was found to be >5 mm in vector length in more than 75% of fractions. Comparisons between the Calypso System and X-ray localization showed good agreement. Qualitatively, the continuous motion was unpredictable and varied from persistent drift to transient rapid movements. Displacements > or =3 and > or =5 mm for cumulative durations of at least 30 s were observed during 41% and 15% of sessions. In individual patients, the number of fractions with displacements > or =3 mm ranged from 3% to 87%; whereas the number of fractions with displacements > or =5 mm ranged from 0% to 56%. The Calypso System is a clinically efficient and objective localization method for positioning prostate patients undergoing radiotherapy. Initial treatment setup can be performed rapidly, accurately, and objectively before radiation delivery. The extent and frequency of prostate motion during radiotherapy delivery can be easily monitored and used for motion management.

Electromagnetic Emission of High-Energy Extracorporeal Shockwave Lithotripsy to the Shoulder does not Cause Disruption of Bispectral Index Monitoring of Propofol or Sevoflurane Anesthesia

To the Editor: Hemmerling et al. (1,2) in a recent series of case reports appearing in Anesthesia & Analgesia displayed disruptions of bispectral index (BIS) monitoring (Aspect Medical Systems Newton, MA) with a shoulder shaver device (1) and with the use of an otorhinolaryngology electromagnetic positioning system (2). We examined the effect on BIS monitoring of an electromagnetic emitter of a high-energy extracorporeal shockwave therapy (ESWT) lithotripter applied to the shoulder. After Graz Medical University ethics committee approval, and written informed consent, 6 adult patients underwent shoulder ESWT lithotripsy for symptomatic rotator cuff calcareous tendinopathy under propofol general anesthesia (group 1, 3 patients) or sevoflurane-nitrous oxide (N2O) (group 2, 3 patients). BIS “Quattro” sensors were placed on patients’ foreheads and connected to a BIS XP monitor (version 3.4). Data were captured from the Serial Port onto a laptop computer every 5 s, after verifying a signal quality index of >95% and electrodes impedance of <5 kΩ. The smoothing window was set at 30 s. Anesthesia was induced with fentanyl 1.5 μg/kg and propofol 2–3 mg/kg, followed by rocuronium 600 μg/kg to facilitate tracheal intubation. Anesthesia was maintained with either propofol 100–150 μgkg−1min−1 and remifentanil 0.1–0.3 μgkg−1min−1 (group 1) or sevoflurane 1 MAC with 60% N2O in oxygen (group 2). All patients underwent electromagnetic induction of high-energy shockwave lithotripsy to the shoulder (Minilith SL1; Storz Medical, Kreuzlingen, Switzerland). The energy flux density in the therapy focus was 0.5 mJ/mm2 of a total of 2000–3000 impulses. In all 6 patients, BIS tracings indicated a signal quality index of >95%. With induction of anesthesia the mean ± sd BIS value declined to 28.4 ± 2.7. Anesthesia was maintained at BIS 36.7 ± 3.1 before the start of ESWT. The mean BIS value during ESWT was 37.2 ± 2.7, whereas the BIS value in the 10 min after the switching the ESWT off remained at 37.9 ± 3.4 before starting to increase with termination of anesthesia (Fig. 1). During the anesthesia maintenance phase, using the paired Student’s t-test there was no statistically significant difference between mean BIS values before and during (P = 0.2384) ESWT or between during and after (P = 0.2198) switching the ESWT off. There was no significant difference in electromyelogram values before, during, and after ESWT.Figure 1.: Mean Bispectral Index (BIS) and electromyography (EMG) during extracorporeal shockwave therapy (ESWT) in six patients.The literature reports demonstrating artifactual increases in BIS give the impression that electric devices applied to the shoulder “similar” to the shoulder shaver (1), or devices generating an electromagnetic field (2), are likely to result in erroneous BIS readings. In the former case, BIS suddenly increased from 40 to 60 during the activity of endoscopic shoulder shaver oscillations and decreased equally abruptly after the end of the use of the shaver device (1). Our modest study suggests that the new BIS algorithm is properly shielded against shoulder vibrations caused by the electromagnetic shock wave emitter. In the latter report, switching a three-dimensional otorhinolaryngology electromagnetic positioning device increased the BIS from 40 to 60–90 despite increased anesthetic drug doses, during both propofol and sevoflurane maintenance of anesthesia. We failed to find any suggestion that outside electromagnetic field generated during ESWT altered the BIS. This may reflect further refinement of the BIS to exclude such artifacts or may reflect a difference in the electromagnetic fields between that generated by the ESWT device compared with the electromagnetic positioning device. Despite these negative findings, the electroencephalogram (EEG) waveform is easily altered by artifacts. The possibility of artifact should always be considered when evaluating the information obtained from computerized EEG monitors. Ashraf A. Dahaba, MD, MSc, PhD Helmar Bornemann, MD Department of Anaesthesiology and Intensive Care Medicine [email protected] Peter H. Rehak, PhD Biomedical Engineering and Computing Unit of the Department of Surgery Helfried Metzler, MD Department of Anaesthesiology and Intensive Care Medicine Graz Medical University Graz, Austria

電磁式管路位置測量システムの開発

It is useful to employ jacking method for construction of lifelines. We have developed an electromagnetic positioning system of underground pipes at the depth between 10 and 15 m. This system consists of a receiver coil on the ground surface and a transmitter coil in the subsurface pipe. The used frequency is approximately 1 kHz and the magnetic moment of the transmitter coil is around 50 ATm2.The prototype system estimates a transmitter position as a cross point of detected magnetic lines at some receiver points. The estimation error of 0.5∼2.0 m resulted from the field tests is higher than the requested one. The improved system synchronizing a receiver clock with a transmitter and limiting a search area small over the transmitter was developed. This system has two measuring modes of rough and detail search. In the first mode, the maximum voltage induced in the vertical receiver coil indicates the transmitter position roughly. In another mode, an exact position is found as a point indicating zero voltage in the horizontal receiver coil. An exact point is shown visibly and easily in the graphic screen on the receiver.Results obtained in some jacking pipe sites proved that the improved system achieved the tolerance below 5 cm horizontally.

Reconnaissance Soil Mapping of a Small Watershed Using Electromagnetic Induction and Global Positioning System Techniques

Reconnaissance Soil Mapping of a Small Watershed Using Electromagnetic Induction and Global Positioning System Techniques