查看更多>>摘要：? 2022 Elsevier LtdGeomagnetic aided navigation is an effective approach to eliminate the cumulative error in inertial navigation system (INS). Iterative closest contour point (ICCP) geomagnetic matching algorithm is sensitive to initial error, which will degrade the navigation accuracy greatly. To solve the problem, ICCP and particle swarm optimization (PSO) are improved separately, and an innovative PSO-ICCP geomagnetic matching algorithm is proposed. Firstly, a multi-attribute decision-making problem is introduced to optimize the output of ICCP. Secondly, PSO and ICCP are combined to diminish the sensitive of ICCP to initial error with the global search capability of PSO. Finally, to improve the performance of PSO, a particle initialization strategy is adopted using sliding window and quad-tree. Experimental results verified that PSO-ICCP can effectively reduce INS error. When magnetic measurement noise is 15nT, the position error and heading error are reduced from 1318.83 m, 7.83° to 23.51 m, 2.08°, which is more accurate compared with state-of-art algorithm.
查看更多>>摘要：? 2022 Elsevier LtdQuantitative measurements of spinal curvature can indicate the health of the human musculoskeletal system. However, existing measurement techniques are not feasible for unexposed back. This study used accelerometers to develop a portable, noninvasive, nonradiative, and cost-efficient device to quantitatively measure spinal curvature in real time. The measurement accuracy is approximately 99% when measuring a ?200-mm circle. Compared with the results of the three-dimensional motion analysis system, the device exhibited curvature results that were highly consistent in the Bland-Altman test (cervical lordosis angle (CLA): r = 0.973, thoracic kyphosis angle (TKA): r = 0.993, lumbar lordosis angle (LLA): r = 0.961, and spinal alignment trendline (SAT): r = 0.978). Repeatability test results: CLA = 37.63 ± 2.24°, TKA = 32.48 ± 0.98°, and LLA = 15.64 ± 1.12°. Thus, the proposed device can provide accurate and reliable quantitative measurements and can be used for spinal curvature measurements in the supine position.
查看更多>>摘要：? 2022 Elsevier LtdThe combustion analysis system (CAS) is a highly sophisticated tool for engine combustion supervision, control and diagnosis. The analytic quality of the combustion process is strongly influenced by the accuracy of sensing cylinder pressure. At present, cylinder pressure measurement still faces the challenge of signal contamination by various noises. To improve the analysis quality of CAS, an anomaly identification and reconstruction method for CAS is proposed by combining the trigger-sample principle and the 0D-thermodynamic model. Anomaly identification globally detects sensing data patterns that significantly deviate from the expected behavior, and finely decomposes the raw data into normal and abnormal data. Then, the data is reconstructed by the anomaly reconstruction algorithm. The experimental results show the effectiveness of the anomaly identification and reconstruction algorithm in locating the abnormal cylinder pressure on a crank-angle basis, and in reconstructing the cylinder pressure by rejecting measurement noise without losing valuable sensing information.
查看更多>>摘要：? 2022 Elsevier LtdThe navigation and positioning accuracy of the carrier can be effectively improved through the integrated navigation of GPS and Inertial navigation system (INS). However, signals from GPS satellites are affected by the external environment, which may reduce the positioning accuracy of GPS. More seriously, the GPS receiver may receive spoofing signals, resulting in positioning errors in the integrated navigation. Therefore, an anti-spoofing integrated navigation method is proposed in this paper. The error propagation characteristics of inertial navigation and the prediction estimation value in Kalman filter are used to detect the spoofing. After spoofing detection, credible GPS positioning results are used for Kalman filter as measurements. The method proposed in this paper can effectively improve the accuracy and robustness of integrated navigation. At the same time, it does not need to modify the existing GPS equipment or additional equipment. The effectiveness of the method is verified by simulation and vehicular experiments.
查看更多>>摘要：? 2022 The AuthorsThe development of satellite techniques and the availability of mobile devices with built-in multi-GNSS (Global Navigation Satellite System) receivers allow the determination of position with increasing accuracy. At the same time, the requirements of users as to the accuracy of positioning are increasing, while the low production costs of the device must be maintained. This paper presents a loosely coupled integration of low-cost sensors (GNSS, IMU (Inertial Measurement Unit), and an odometer) with the use of a nonlinear Kalman filter and a dynamic weight matrix. The integration model was developed for horizontal (2D) components with the simultaneous determination of the azimuth of the test platform. The tests were carried out in the conditions of an open horizon, with partial obscuring of the horizon (passage under an open-work steel structure) and along walls. In this way, the working conditions for an autonomous lawn mower, which are now increasingly used by citizens, were simulated. The position accuracy obtained in these tests is better than 5 cm for horizontal components and better than 1 degrees for the azimuth.
查看更多>>摘要：? 2022 Elsevier LtdIn this paper, a curvature sensor based on 2-core fiber offset structure is proposed. Firstly, the curvature sensing principle of this sensor is qualitatively analyzed. It is concluded that this sensor has the ability to identify one-dimensional bending direction. This is proved by the following experiments. Considering that there can be two offset modes, experiments are carried out on sensors with different offset modes. Through experiments, it is concluded that the sensor in positive offset mode has better sensing performance. The sensors with different offset value are also tested. It is found that the sensor has better curvature sensing performance when its offset value is + 6 μm. The experiments show that the sensitivity of this sensor bending along different directions can reach ?14.19 nm/m?1 and + 16.58 nm/m?1. Meanwhile, it has a large measurement range and good linearity. The sensor is also insensitive to strain and twist. This sensor has a wide application prospect in the fields of industry, architecture and structural health monitoring.
查看更多>>摘要：? 2022 Elsevier LtdBlind deconvolution (BD) methods are very popular in noise reduction. Generally, the setting of parameters directly affects the filtering effect of BD methods. To avoid this flaw, an adaptive method called iterative Morlet wavelet filter (IMWF) is proposed in this paper. In IMWF, the traditional Morlet wavelet filter is optimized to process the signal matrix which is adaptively constructed by the power spectral density. The lifted correlation kurtosis with autocorrelation-closing analysis is adopted as the objective function to search the optimal parameter in IMWF. After that, the SOSO (i.e. strengthen, operate, subtract, operate) boosting strategy is supplemented to enhance the IMWF through an iterative algorithm. Finally, simulation and experimental cases are analyzed to demonstrate the feasibility and superiority of the IMWF for fault identification. Some popular typical methods are utilized for comparisons. The final analysis results show that IMWF is an efficient method.
查看更多>>摘要：? 2022 Elsevier LtdRemaining useful life prediction (RUL) is critical in predictive maintenance for components or systems prone to deterioration. However, direct RUL prediction methods have difficulties tracking health trends and realizing online prognostics. To address this issue, this paper proposes a novel health index (HI) based adaptive prognostics method by leveraging the advantages of both data fusion to handle multi-dimensional data and the adaptive extended Kalman filter (AEKF) algorithm for parameter identification in the diffusion process. A fitness metric is proposed for feature selection, and then the composite HI sequence is constructed via data fusion using the genetic algorithm. Furthermore, a diffusion process model is built to characterize HI degradation while considering multi-source uncertainties. Model parameters are then updated using the fitting-based AEKF method. Finally, the proposed method is validated on a real-world dataset of solid-state drives in data centers, and prediction results and comparative studies verify its superiority.
查看更多>>摘要：? 2022In this paper, a three-dimensional (3-D) lumped parameter thermal network (LPTN) model is presented for the first time for a rotor-excited axial-field flux-switching permanent magnet (RE-AFFSPM) machine. The 3-D LPTN predicts the steady-state temperature of different parts in various operating conditions. To enhance the LPTN accuracy and comprehensiveness, (i) the convection heat transfer in the internal and external areas, as well as radiation from the end-windings, (ii) core material anisotropic thermal conductivity, (iii) the equal thermal conductivity of the winding in the slot, and (iv) contact thermal resistances are all considered. Heat transfer coefficients are obtained mathematically to be applicable for the RE-AFFSPM machines with different parameters. A 3-D finite element method (FEM) is established to calculate the electromagnetic losses and thermal analysis with high accuracy. Eddy current losses in the stator core, rotor core, permanent magnets (PMs), and carriers, along with hysteresis losses in the stator and rotor cores, are calculated by 3-D FEM then coupled to the thermal analysis to predict the temperature distribution. By comparing the temperature results of the 3-D LPTN and 3-D FEM at various speeds, air–gap lengths, loading levels, and simultaneous variation of the current density and speed, the performance of the proposed 3-D LPTN is further investigated and verified. Results indicate that by the proposed 3-D LPTN, components temperature can be approximated with high accuracy in a lesser time than the 3-D FEM.
查看更多>>摘要：? 2022 Elsevier LtdA parallel-structured Fabry-Perot interferometers (FPIs) gas pressure sensor with ultraviolet glue sensitization based on dual Vernier effect has been proposed and experimentally investigated, which was fabricated based on the FPI coated with ultraviolet glue film and the FPI fully filled with ultraviolet glue. Owing to the unique features of the parallel-structured FPIs, the reflective spectra of them shift to opposite directions as ambient gas pressure varies. Two FPIs serve as sensing reference for each other in gas pressure sensing, generating the dual Vernier effect to enhance Vernier effect. The proposed gas pressure sensor exhibits a high sensitivity of 131.88 nm/MPa and provides new strategies and ideas for fiber-optic sensing filed.
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