Position Estimation of Vehicle Based on Magnetic Marker: Time-Division Position Correction

During the automatic driving of a vehicle, the vehicle’s positional information is important for vehicle driving control. If fixed-point land markers such as magnetic markers are used, the vehicle’s current position error can be calculated only when a marker is detected while driving, and this error can be used to correct the estimation position. Therefore, correction information is used irregularly and intermittently according to the installation intervals of the magnetic markers and the driving speed. If the detected errors are corrected all at once using the position correction method, discontinuity of the position information can occur. This problem causes instability in the vehicle’s route guidance control because the position error fluctuates as the vehicle’s speed increases. We devised a time-division position correction method that calculates the error using the absolute position of the magnetic marker, which is estimated when the magnetic marker is detected, along with the absolute position information from the magnetic marker database. Instead of correcting the error at once when the position and heading errors are corrected, the correction is performed by dividing the errors multiple times until the next magnetic marker is detected. This prevents sudden discontinuity of the vehicle position information, and the calculated correction amount is used without loss to obtain stable and continuous position information. We conducted driving tests to compare the performances of the proposed algorithm and conventional methods. We compared the continuity of the position information and the mean error and confirmed the superiority of the proposed method in terms of these aspects.

Magnetically Guided Localization Using a Guiding-Marker System® and a Handheld Magnetic Probe for Nonpalpable Breast Lesions: A Multicenter Feasibility Study in Japan

Accurate pre-operative localization of nonpalpable lesions plays a pivotal role in guiding breast-conserving surgery (BCS). In this multicenter feasibility study, nonpalpable breast lesions were localized using a handheld magnetic probe (TAKUMI) and a magnetic marker (Guiding-Marker System®). The magnetic marker was preoperatively placed within the target lesion under ultrasound or stereo-guidance. Additionally, a dye was injected subcutaneously to indicate the extent of the tumor excision. Surgeons checked for the marker within the lesion using a magnetic probe. The magnetic probe could detect the guiding marker and accurately localize the target lesion intraoperatively. All patients with breast cancer underwent wide excision with a safety margin of ≥5 mm. The presence of the guiding-marker within the resected specimen was the primary outcome and the pathological margin status and re-excision rate were the secondary outcomes. Eighty-seven patients with nonpalpable lesions who underwent BCS, from January to March of 2019 and from January to July of 2020, were recruited. The magnetic marker was detected in all resected specimens. The surgical margin was positive only in 5/82 (6.1%) patients; these patients underwent re-excision. This feasibility study demonstrated that the magnetic guiding localization system is useful for the detection and excision of nonpalpable breast lesions.

An experimental study on characterizing damage and fracture of a rock-like material based on three-dimensional magnetic field imaging

Purpose The results showed that the use of a magnetic marker could relatively accurately reflect the fracture pattern inside the rock-like material (RLM). Design/methodology/approach This study investigated the internal structure and fracture pattern of a fractured RLM. Magnetized iron oxide powder, which was used as a magnetic marker, was mixed with water and glue to form a magnetic slurry, which was subsequently injected into a fractured RLM. After the magnetic slurry completely filled the cracks inside the RLM and became cemented, the distribution and magnitude of the magnetic field inside the RLM were determined using a three-dimensional (3D) magnetic field imaging system. Findings A model for determining the magnetic field strength was developed using MATLAB. Originality/value This model of 3D magnetic will further be used as a finite element tool to simulate and image cracks inside the rock.

Magnetic Seed (Magseed) Localisation in Breast Cancer Surgery: A Multicentre Clinical Trial

<b><i>Introduction:</i></b> The aim of this study was to evaluate the accuracy and reliability of the Magseed magnetic marker in breast cancer surgery. <b><i>Methods:</i></b> Thirty-nine patients with 41 implanted Magseeds undergoing surgical treatment in 3 surgical oncology departments were included in the retrospective trial to study pilot use of the Magseed magnetic marker in the Czech Republic for localisation of breast tumours or pathological axillary nodes in breast cancer patients. <b><i>Results:</i></b> Thirty-four breast cancer and 7 pathological lymph node localisations were performed by Magseed implantation. No placement failures, or perioperative detection failures of Magseeds were observed (0/41, 0.0%), but one case of Magseed migration was present (1/41, 2.4%). All magnetic seeds were successfully retrieved (41/41, 100.0%). Negative margins were achieved in 29 of 34 (85.3%) breast tumour localisations by Magseed. <b><i>Conclusion:</i></b> Magseed is a reliable marker for breast tumour and pathological axillary node localisation in breast cancer patients. Magseed is comparable to conventional localisation methods in terms of oncosurgical radicality and safety.