Conventional Position Research Articles

Deep-Learning-Based MRI Images for Analysis of Sport-Induced Ankle Joint Injury

This study was to analyze the sport-induced ankle joint injury (AJI) images based on the neural network algorithms using the magnetic resonance imaging (MRI). 20 patients and 20 volunteers were included in the experimental and control groups, respectively. The hybrid diffusion equation (HDE) neural network (HDENN) algorithm was compared with the fully convolutional neural network (FCNN) and the FCNN preprocessing, and the HDE was applied to the MRI analysis of sport-induced AJI. The results showed that the total score of MRI image for the conventional position of the anterior talofibular ligament (ATFL) and posterior talofibular ligament (PTFL) was concentrated in 4 (55%) and 5 (65%), respectively. The number of patients with good prognosis with grade II injury (11 cases) was much higher than that of grade III injury (2 cases), and the number of patients with poor prognosis (4 cases) was lower than that of grade III injury (6 cases) ( P < 0.05 ). Conventional MRI was recommended to observe the ATFL and PTFL, and the valgus position MRI was recommended for the calcaneofibular ligament (CFL); conservative treatment was recommended for patients with grades I and II AJI, but surgical treatment was recommended for patients with grade III AJI.

Mechanics of guided growth of the distal femur for correction of fixed knee flexion deformities: an extra-articular technique.

Anterior distal femoral hemiepiphysiodesis using intra-articular plates for correction of pediatric fixed knee flexion deformities (FKFD) has two documented complications: postoperative knee pain and implant loosening. The aim of this study is to investigate the mechanical properties of a novel extra-articular technique for anterior distal femoral hemiepiphysiodesis in patients with FKFD and to compare them to the conventional technique. Sixteen femoral sawbones were osteotomized at the level of the distal femoral physis and fixed by rail frames to allow linear distraction simulating longitudinal growth. Each sawbone was tested twice: first using the conventional technique with eight plates placed anteriorly just medial and lateral to the femoral sulcus (group A) and then with plates inserted in the proposed novel location at the most anterior part of the medial and lateral surfaces of the femoral condyles with screws in the coronal plane (group B). Gradual linear distraction was performed, and the resulting angular correction was measured. Strain gauges were attached to the plates, and the amount of strain (and equivalent stress) over the plates in response to linear distraction was recorded. The two groups were compared using the Wilcoxon signed-rank test. The amount of angular correction was statistically higher in group B (extra-articular plates) at 5, 10-, and 15-mm of distraction (p < 0.001). As regards stress over the plates, the maximum stress and the area under the curve (sum of all stresses measured throughout the distraction process) were significantly higher when the plates were inserted at the conventional position (group A) (p < 0.001). During anterior distal femoral hemiepiphysiodesis, the fixation of the eight plates in the coronal plane at the anterior part of the femoral condyles may produce a greater amount of correction and a lower degree of stress over the implants as compared to the conventional technique.

Acoustic Target Tracking Through a Cluster of Mobile Agents.

This paper discusses the problem of tracking a moving target by means of a cluster of mobile agents that is able to sense the acoustic emissions of the target, with the aim of improving the target localization and tracking performance with respect to conventional fixed-array acoustic localization. We handle the acoustic part of the problem by modeling the cluster as a sensor network, and we propose a centralized control strategy for the agents that exploits the spatial sensitivity pattern of the sensor network to estimate the best possible cluster configuration with respect to the expected target position. In order to take into account the position estimation delay due to the frame-based nature of the processing, the possible positions of the acoustic target in a given future time interval are represented in terms of a compatible set, that is, the set of all possible future positions of the target, given its dynamics and its present state. A frame-by-frame cluster reconfiguration algorithm is presented, which adapts the position of each sensing agent with the goal of pursuing the maximum overlap between the region of high acoustic sensitivity of the entire cluster and the compatible set of the sound-emitting target. The tracking scheme iterates, at each observation frame, the computation of the target compatible set, the reconfiguration of the cluster, and the target acoustic localization. The reconfiguration step makes use of an opportune cost function proportional to the difference of the compatibility set and the acoustic sensitivity spatial pattern determined by the mobile agent positions. Simulations under different geometric configurations and positioning constraints demonstrate the ability of the proposed approach to effectively localize and track a moving target based on its acoustic emission. The Doppler effect related to moving sources and sensors is taken into account, and its impact on performance is analyzed. We compare the localization results with conventional static-array localization and positioning of acoustic sensors through genetic algorithm optimization, and results demonstrate the sensible improvements in terms of localization and tracking performance. Although the method is discussed here with respect to acoustic target tracking, it can be effectively adapted to video-based localization and tracking, or to multimodal information settings (e.g., audio and video).

Single-Position Surgery: Prone Lateral Lumbar Interbody Fusion: 2-Dimensional Operative Video.

Lateral lumbar interbody fusion (LLIF) is a widely used technique for anterior fusion. However, posterior decompression or instrumentation often requires repositioning the patient, which increases operative time. This video describes the prone LLIF as a modification of the standard surgical technique. The prone LLIF facilitates simultaneous decompression and fusion, which avoids the need for repositioning the patient, increasing operative efficiency. Positioning, fluoroscopic considerations, and operative nuances involved in performing the LLIF in the prone position are described, and an illustrative case is presented. The patient provided informed consent for the procedure and videography. LLIF in the prone position can decrease operative time and increase operative efficiency. The prone position is a viable alternative to the conventional lateral decubitus position. Video used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Hands-up! Dealing with Electromagnetic Interference in Maglev LVADs

<h3>Purpose</h3> Electromagnetic interference (EMI) generated by the HeartMate3 (HM3) may disrupt initial "hand-shake" connectivity between an implanted defibrillator (ICD) and its external programmer. As the intensity of EMI is a function of VAD-ICD distance, manipulating this parameter may improve programmer connectivity. <h3>Methods</h3> As the conventional position of ICDs is in the left pectoral muscle, arm movement influences the position of the ICD relative to the fixed intra-thoracic VAD position. Given the different arm positions utilised for CT (above the head) and chest x-ray (in front), we retrospectively analysed chest CT scans and chest X-rays (CXRs) of patients implanted with a VAD between March 2018 and March 2020. <h3>Results</h3> We analysed 32 X-rays and 22 CTs of 22 patients implanted with a VAD (5 HM3 and 17 Heartware). Seventeen patients had both a VAD and an ICD in situ, with majority (14/17) of these devices implanted on the left side. The mean distance between a left implanted ICD and the VAD was 11.7cm (IQR 10.8-13.2) on chest X-ray and 14.7cm (IQR 13.6-16.3) on CT. There was a significant discrepancy between CT and X-ray calculated distances with a median 3.3cm(IQR 2.2-4.0) greater distance when measured by CT (p=0.0003) in the same patient. There was no difference in distance between patients with HW and HM3 devices (p=0.6). In one patient with an HM3 and a Biotronic (Illivia) ICD-device that was unable to be interrogated, raising the arm above the head in supine position allowed reconnection, illustrating the practical application of this manoeuvre. <h3>Conclusion</h3> There is a 3.3cm increase in the VAD-ICD distance when patients raise their arms above the head. This is an easily performed manoeuvre to overcome VAD EMI and needs to be more systematically studied.

A comparison between manual and artificial intelligence\u2013based automatic positioning in CT imaging for COVID-19 patients

ObjectiveTo analyze and compare the imaging workflow, radiation dose, and image quality for COVID-19 patients examined using either the conventional manual positioning (MP) method or an AI-based automatic positioning (AP) method.Materials and methodsOne hundred twenty-seven adult COVID-19 patients underwent chest CT scans on a CT scanner using the same scan protocol except with the manual positioning (MP group) for the initial scan and an AI-based automatic positioning method (AP group) for the follow-up scan. Radiation dose, patient positioning time, and off-center distance of the two groups were recorded and compared. Image noise and signal-to-noise ratio (SNR) were assessed by three experienced radiologists and were compared between the two groups.ResultsThe AP operation was successful for all patients in the AP group and reduced the total positioning time by 28% compared with the MP group. Compared with the MP group, the AP group had significantly less patient off-center distance (AP 1.56 cm ± 0.83 vs. MP 4.05 cm ± 2.40, p < 0.001) and higher proportion of positioning accuracy (AP 99% vs. MP 92%), resulting in 16% radiation dose reduction (AP 6.1 mSv ± 1.3 vs. MP 7.3 mSv ± 1.2, p < 0.001) and 9% image noise reduction in erector spinae and lower noise and higher SNR for lesions in the pulmonary peripheral areas.ConclusionThe AI-based automatic positioning and centering in CT imaging is a promising new technique for reducing radiation dose and optimizing imaging workflow and image quality in imaging the chest.Key Points• The AI-based automatic positioning (AP) operation was successful for all patients in our study.• AP method reduced the total positioning time by 28% compared with the manual positioning (MP).• AP method had less patient off-center distance and higher proportion of positioning accuracy than MP method, resulting in 16% radiation dose reduction and 9% image noise reduction in erector spinae.

Enhanced combustion behavior and NOx reduction performance in a CFB combustor by combining flue gas recirculation with air-staging: Effect of injection position

In circulating fluidized bed (CFB) boilers, the flue gas recirculation (FGR) is an important technical means to promote de-NOx combustion. However, the conventional injection position of recycled gas seriously hinders the combustion efficiency and the flexibility of load regulation. To solve this, thermal-state experiments are conducted on a lab-scale CFB combustor to explore the feasibility of adopting novel FGR and air staging technology to achieve low NOx emission and sufficient combustion efficiency. The effects of FGR/supplementary burnout air (SBA) injection positions and operating parameters on temperature profile, combustion efficiency and original NOx emission in the furnace are discussed in detail. The synergistic effect of FGR and SBA on combustion characteristics and NOx reduction is also analyzed. Eventually, a systematic approach to enhance NOx control and combustion efficiency in fluidized bed is proposed. The key results indicate that the NOx reduction rate reaches 46.15% by adopting middle FGR and top SBA, which exceeds the reduction performance of utility boilers with conventional FGR. Also, the furnace outlet temperature and combustion efficiency can be ensured to be over 860 °C and 98.4% respectively, thus to provide new technical basis for enhancing de-NOx combustion in CFB boiler at low load, as well as the prospective guidance for FGR retrofitting of various fluidized bed combustors.

Smart Mandibular Advancement Device for Intraoral Monitoring of Cardiorespiratory Parameters and Sleeping Postures.

Obstructive sleep apnea (OSA), as a highly prevalent sleep disorder, causes several serious health complaints. It has been proved that using intraoral mandibular advancement devices (MADs) during sleep is an efficient treatment for OSA. However, due to limited number of sleep study laboratories, effectiveness of MAD therapy is not regularly monitored. This paper proposes a smart MAD with the capability of continuously monitoring of cardiorespiratory parameters as well as sleeping postures and breathing routes. In this regard, a flexible hybrid wireless sensing platform based on the intraoral photoplethysmography (PPG), temperature and accelerometry monitoring is developed. It is qualitatively and quantitatively discussed that the intraorally captured PPG signals by the smart MAD have similar features as the ones received from the conventional anatomical position, i.e., the left index fingertip. Extensive experimental measurements indicate that the proposed smart MAD can estimate heart-rate (HR), respiration rate (RR) and blood oxygen saturation (SpO2) with the maximum mean-absolute-errors of 2.4 bpm, 2.52 breaths/min, and 0.8%, respectively, in comparison to the reference measurements, while such a capability is not dependent on subject's positions and breathing routes. It is also shown that the smart MAD can readily identify different sleeping postures, namely, supine, left, right, and prone and breathing routes. The reliability and stability of the proposed smart MAD's measurements are proved by examining a group of subjects. The proposed smart MAD has potential to monitor the effectiveness of MAD treatment and eliminate untreated OSA without the requirement of attaching an extra monitoring platform to the patient's body.

Nonlinear vibration control of smart plates using nonlinear modified positive position feedback approach

In this paper, nonlinear vibration control of a plate is investigated using a nonlinear modified positive position feedback method that is applied through a piezoelectric layer on the plate. Based on the classical theory of displacement and strain relations with von Karman, intended equations of motion for the smart plate have been obtained. In this model, transverse vibrations are studied and stimulations are performed for the primary resonance. Boundary conditions of the smart plate are simply supported. The plate is thickness symmetrical. Using the Galerkin method the temporal nonlinear equations governing the system have been found. Then, the free and forced vibrations of the structure with the nonlinear modified positive position feedback controller have been solved using the Method of Multiple Scales to obtain an analytical solution. Results show that this controller reduces the amplitude of the vibration by inducing an increase in the damping coefficient. In addition, this provides a higher level of suppression in the overall frequency domain response by increasing the compensator gain. Finally, the results of the analytical solution for the closed-loop nonlinear modified positive position feedback controller are presented and compared with the result of the conventional positive position feedback controller and nonlinear integral resonant controller. The results show that the performance of the nonlinear modified positive position feedback controller is better than other controllers and significantly reduces the vibration amplitude.

자속 차폐벽을 갖는 선형 홀센서 BLDC 모터를 이용한 전기식 조종날개 구동장치의 위치 제어

In general, position sensor and velocity sensor are used to design robust controller of the electro-mechanical fin actuator system. However, the use of such a sensor causes problems such as an increase in cost, an additional space for mounting, and a decrease in system reliability due to a sensor failure. To overcome these problems, rotor position sensor of the BLDC motor was replaced with linear type Hall-effect sensor having a magnetic flux shielding wall from the latch type Hall-effect sensor. The conventional position sensor and velocity sensor were removed through a position and velocity implementation algorithm using the analog output of the linear type Hall-effect sensor. In order to prove the validity of the proposed method, various comparison tests were performed with the existing position/velocity sensors. As a result of the test, the method proposed in this paper can obtain the position response similar to the case of applying the conventional position/velocity sensor.

Augmented CWT Features for Deep Learning-Based Indoor Localization Using WiFi RSSI Data

Localization is one of the current challenges in indoor navigation research. The conventional global positioning system (GPS) is affected by weak signal strengths due to high levels of signal interference and fading in indoor environments. Therefore, new positioning solutions tailored for indoor environments need to be developed. In this paper, we propose a deep learning approach for indoor localization. However, the performance of a deep learning system depends on the quality of the feature representation. This paper introduces two novel feature set extractions based on the continuous wavelet transforms (CWT) of the received signal strength indicators’ (RSSI) data. The two novel CWT feature sets were augmented with additive white Gaussian noise. The first feature set is CWT image-based, and the second is composed of the CWT PSD numerical data that were dimensionally equalized using principal component analysis (PCA). These proposed image and numerical data feature sets were both evaluated using CNN and ANN models with the goal of identifying the room that the human subject was in and estimating the precise location of the human subject in that particular room. Extensive experiments were conducted to generate the proposed augmented CWT feature set and numerical CWT PSD feature set using two analyzing functions, namely, Morlet and Morse. For validation purposes, the performance of the two proposed feature sets were compared with each other and other existing feature set formulations. The accuracy, precision and recall results show that the proposed feature sets performed better than the conventional feature sets used to validate the study. Similarly, the mean localization error generated by the proposed feature set predictions was less than those of the conventional feature sets used in indoor localization. More particularly, the proposed augmented CWT-image feature set outperformed the augmented CWT-PSD numerical feature set. The results also show that the Morse-based feature sets trained with CNN produced the best indoor positioning results compared to all Morlet and ANN-based feature set formulations.

Adaptive versus Conventional Positive Position Feedback Controller to Suppress a Nonlinear System Vibrations

The nonlinear vibration control of a nonlinear dynamical system modeled as the well-known Duffing oscillators is investigated within this article. The conventional Positive Position Feedback (PPF) controller is proposed to mitigate the considered system nonlinear vibrations. The whole system mathematical model is analyzed by applying the multiple time scales perturbation method. The slow-flow modulation equations that govern the oscillation amplitudes of both the main system and controller are derived. The stability analysis is investigated based on Lyapunov’s first method. The effects of the different control parameters on both the main system and controller are explored. The obtained analytical and numerical results illustrated that the PPF controller can eliminate the main system nonlinear vibrations once the controller natural frequency is tuned to be the same value as the external excitation frequency, otherwise, the controller adds excessive vibrational energy to the main system rather than suppressing it. In addition, the PPF controller can destabilize the main system motion when excited by strong excitation force. Therefore, a modified version of the PPF controller named the Adaptive Positive Position Feedback (APPF) controller is proposed to overcome the main drawbacks of the conventional PPF controller. The idea is to track the external excitation frequency using an adaptive frequency measurement technique to update continuously the PPF controller natural frequency to become the same value of the excitation frequency. Based on this strategy, the system mathematical model is analyzed again by making the controller’s natural frequency equal to the external excitation frequency. The obtained analytical and numerical simulations showed that the adaptive positive position feedback controller can suppress the main system nonlinear vibration close to zero regardless of the excitation force amplitude and excitation frequency.

Magnetic modeling of actively shielded rotating MRI magnets in the presence of environmental steel

Rotating MRI systems could enable novel integrated medical devices such as MRI-Linacs, MRI-xray-angiography systems, and MRI-proton therapy systems. This work aimed to investigate the feasibility of rotating actively shielded superconducting MRI magnets in the presence of environmental steel—in particular, construction steel in the floor of the installation site. Two magnets were investigated: a 1.0 T split bore magnet, and a 1.5 T closed bore magnet. Each magnet was scaled to emulate field strengths of 0.5, 1.0, and 1.5 T. Finite Element Modeling was used to simulate these magnets in the presence of a 3 × 4 m steel plate located 1250 mm or 1400 mm below the isocenter. There are two possible rotation directions: around the longitudinal (z) axis or around the transverse (x) axis. Each model was solved for rotation angles between 0 and 360° in 30° intervals around each of these axes. For each simulation, a 300 mm DSV was extracted and decomposed into spherical harmonics. For the closed-bore magnet, total induced perturbation for the zero degree rotation angle was 223, 432, and 562 μT peak-to-peak (pk–pk) for the 0.5, 1.0, and 1.5 T models respectively (steel at 1250 mm). For the split-bore magnet, the same numbers were 1477, 16747, and 1766 μT. The substantially higher perturbation for the split-bore magnet can be traced to its larger fringe field. For rotation around the z-axis, total perturbation does not change as a function of angle but is exchanged between different harmonics. For rotation around the x-axis, total perturbation is different at each rotation angle. For the closed bore magnet, maximum perturbations occurred for a 90° rotation around the transverse axis. For the split-bore magnet, the opposite was observed, with the same 90° rotation yielding total perturbation lower than the conventional position. In all cases, at least 95% of the total perturbation was composed of 1st and 2nd order harmonics. The presence of environmental steel poses a major challenge to the realization of an actively shielded rotating superconducting MRI system, requiring some novel form of shimming. Possible shimming strategies are discussed at length.

Simultaneous Localization of Multiple Unknown Emitters Based on UAV Monitoring Big Data

The increasing of illegal radiations, which are either artificial or unintentional, has seriously influenced the reliable communication and operation of industrial facilities. In this article, we discuss the simultaneous localization of multiple emitters based on big data monitored by a moving unmanned aerial vehicle. Conventional direct position determination (DPD) method suffers from the non-homogeneity of the observation error and is sensitive to the environment, so we develop the weight DPD methods. First, we consider to strengthen the spectrums obtained at slots with higher signal-to-noise ratio, which is blindly calculated. Thereafter, an improved weight is designed to further enhance the localization accuracy, and it can obtain the asymptotically optimal performance under the general Gaussian noise model, which is proved theoretically. Numerical simulations demonstrate that the proposed weight DPD methods outperform the conventional two-step methods and subspace data fusion DPD method in terms of localization accuracy and resolution.

Development and Accuracy Evaluation of Augmented Reality-based Patient Positioning System in Radiotherapy: A Phantom Study.

To develop and evaluate the accuracy of augmented reality (AR)-based patient positioning systems in radiotherapy. AR head-mounted displays (AR-HMDs), which virtually superimpose a three-dimensional (3D) image generated by the digital imaging and communications in medicine (DICOM) data, have been developed. The AR-based positioning feasibility was evaluated. Then, the setup errors of three translational axes directions and rotation angles between the AR and the conventional laser-based positioning were compared. The AR-based pelvic phantom positioning was feasible. The setup errors of AR-based positioning were comparable to laser-based positioning in all translational axis directions and rotation angles. The time necessary for AR-based positioning was significantly longer than that for laser-based positioning (171.0 s vs. 47.5 s, p<0.001). AR-based positioning for radiotherapy was feasible, and showed comparable positioning errors to those of conventional line-based positioning; however, a markedly longer setup time was necessary.

The Boundary Problem of Rights Restoration

By conditioning the restoration of felons’ political rights on the repayment of legal financial obligations, states have kept millions of potential voters from participating politically—profoundly altering the shape of the American electorate. Courts have upheld the practice by treating the conferral of political rights to non-members of the political community as an exercise of legislative grace subject to few constraints. Critics argue that the practice conditions political participation on wealth status and is therefore subject to heightened review. This Essay traces the disagreement back to a first-order question overlooked by both sides: how should the juridical status of a disenfranchised citizen’s “lost” rights be understood? The conventional position, which I call the “expulsion” view, imagines that a sentence of disenfranchisement casts a citizen outside the democratic community, thereby voiding all prospective constitutional interests predicated on political membership. However, disenfranchisement is better characterized as the subordination—not the wholesale elimination—of a citizen’s constitutional interests in voting or otherwise participating politically, just as incarceration suppresses but does not eliminate a person’s constitutional interest in physical liberty. From this it follows that disenfranchised citizens retain a stake in political participation and suffer cognizable harm when return to full political membership is inflected by wealth status. Redescribing the disenfranchisement-to-restoration process in this way aligns with the Richardson Court’s reading of Section 2 of the Fourteenth Amendment and sharpens the constitutional symmetry between fee-based restoration and paradigmatic forms of wealth discrimination like poll taxes. By framing re-enfranchisement as a constitutional default and drawing attention to disenfranchised citizens’ enduring claim to political presence, this account may also be of use in popular restoration efforts currently underway outside the courts.

Supine Versus Prone Percutaneous Nephrolithotomy – A Randomised Comparative Study

Percutaneous Nephrolithotomy (PCNL) is the standard procedure for large renal stones. This study was conducted to compare the conventional Prone position PCNL with the newer concept of Supine PCNL. A prospective, randomised controlled, double blind study was conducted in 100 patients planned for PCNL. They were randomised into 2 groups with 50 patients each and PCNL was performed either in the prone or supine position. The patient groups were compared for the length of hospital stay, duration of surgery, postoperative and intra operative complications, postoperative stone free status, and requirement of adjunctive procedures. Stone free rates were significantly better for the supine PCNL group. Post operative complications such as fever was more for Prone PCNL group. The other parameters that were not statistically significant were mean operating time which was less for the supine group and duration of hospital stay which was less for the supine group. There was no difference in the other complication rates between the two procedures. The requirement of additional procedures for stone clearance were also same between both the groups. To conclude, Our study demonstrates that supine PCNL is a better technique than prone PCNL in terms of stone free rates, post-operative complications such as fever, lesser number of punctures required for stone clearance and more tubeless procedures.

Accuracy improvement of 6-UPS Stewart forward kinematics solution based on self-aggregating MFO algorithm

In this paper, a Stewart’s positive solution optimization model is proposed, for obtaining the complex solution to a Stewart’s forward kinematics problem, considering the existence of multiple solutions. The model converts the positive kinematics problem into an optimization problem, in which the value of the objective function is used to represent the precision of Stewart’s positive solution. A self-aggregating moth–flame optimization algorithm (SMFO) is used to improve the accuracy of Stewart’s forward kinematics solution. Two features were added to the conventional MFO algorithm to obtain a more stable balance between global and local explorations. First, Gaussian distribution was used for the flame population to select suitable individuals for Levy Flight operation, increase the diversity of the population, and enhance the algorithm’s ability to jump out of a local optimum. Second, in the middle and late iterations, the positions of the flames were periodically adjusted using the light intensity-attraction characteristic (LIAC) to strengthen the connection between individual flames and enhance the local exploration ability of the algorithm. The proposed SMFO algorithm is compared with three classic meta-heuristic algorithms for eight benchmark functions. Experimental results indicate that the SMFO algorithm is significantly better than the other three algorithms in terms of solution quality and convergence rate. To verify the effectiveness of the SMFO algorithm in solving the Stewart positive kinematics optimization model, values of eight sets of conventional position and posture parameters as well as limiting position and posture parameters were randomly obtained, and values of 16 sets of position and posture parameters were obtained using four algorithms. The results indicate that the SMFO algorithm can improve the accuracy of the forward kinematics solution to 4.05E-09 mm.

Proposing New Planar-Type Search Coil for Permanent Magnet Synchronous Motor: Design and Application for Position Estimation

Conventional position sensors for permanent magnet synchronous motor, such as optical encoder, resolver, or hall sensor, can get fault by the stress. The fault of the motor position sensor may cause serious accidents. Thus, to prevent damages by the position sensor failure, adding a redundancy sensor such as wound search coil is recommendable. In this paper, a new planar search coil design that can be used as a position sensor for permanent magnet synchronous motor is proposed. This new design is a planar coil based on a flexible-printed circuit board that converts airgap flux to a back-electromotive force signal. Unlike the wound search coil design, the proposed design is advantageous for manufacturing and slot-space preservation. Also, this new design is distant from the motor main winding. As a result, the exposure of the electrical and thermal stresses to the sensing coil can be decreased. This research shows the mathematical model for the design of the new planar-shaped airgap flux search coil design. In addition, the position estimation algorithm based on the new search coil design is shown. Finally, the position estimation using the new search coil design is presented.

Investigation on total adjustment of the transducer and seafloor transponder for GNSS/Acoustic precise underwater point positioning

Global navigation satellite system/acoustic (GNSS/A) underwater positioning technique has drawn increasing attention in the fields of marine scientific research and engineering application. The conventional positioning strategy of GNSS/A is to fix the positions of sea-surface transducer, in other words, the positions of the transducer determined by GNSS positioning at different epochs are regarded as accurate and unbiased, and then estimate the underwater transponder's coordinate with acoustic ranging data. However, there inevitably exists bias in the estimation of transducer's positions, and the precision varies at different epochs. Ignoring precision differences of the transducer's positions will lead to a worse estimation of the transponder's coordinate. In this contribution, we propose a total adjustment (TA) method, where the positions of both sea-surface transducer and seafloor transponder are treated as unknown parameters, and the transducer's positions determined by GNSS positioning at different epochs are introduced as virtual observations. In order to reduce the computation load caused by large increase of estimation parameters, an equivalent transformation is applied to observation equations to remove estimation parameters for the transducer's positions at different epochs. To evaluate the performance of the proposed total adjustment method, a series of simulation tests and a sea-trail experiment were carried out. Testing results show that, as compared with the traditional method, the positioning accuracy with the proposed method can be improved by about 10%–33% in the simulation tests and 15% in the field test.