Real-time Array Shape Estimation Method of Horizontal Suspended Linear Array Based on Non-acoustic Auxiliary Sensors

One of the emerging issues in lightweight aerospace structures is the real-time estimation of the structural shape changes. In order to reconstruct the structure shape based on the measured strain data at multiple points, the displacement-strain transformation (DST) method has been used. In this study, simulation for a 1-D beam model was performed to verify the DST method. Bending displacements for various excitation conditions were successfully estimated using the simulated strain signals. Strain sensor positions were optimized by the minimization of the condition number of the DST matrix for the 1-D beam. We further expanded the shape estimation method to rotating beams. A rotating flexible beam experimental model was constructed and a numerical simulation model was also prepared. Multiplexed four FBG sensors were fabricated and attached to the rotating beam structures to measure strains at four different locations. The experimental device has an optical rotary coupler, and the sensor signals are transmitted through the optical rotary coupler. Bending displacements were estimated based on the FBG signals and compared with directly measured displacement data using photographs taken by a high-speed camera. This shows the validity of the proposed shape estimation technique based on DST matrix for rotating beam structures.

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An Enhanced Data-Driven Array Shape Estimation Method Using Passive Underwater Acoustic Data

Remote Sensing ◽

10.3390/rs13091773 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1773

Author(s):

Qisong Wu ◽

Hao Zhang ◽

Zhichao Lai ◽

Youhai Xu ◽

Shuai Yao ◽

...

Keyword(s):

Time Delay ◽

Narrow Band ◽

Estimation Method ◽

Poor Performance ◽

Data Driven ◽

Shape Estimation ◽

Underwater Acoustic ◽

Acoustic Data ◽

Hydrophone Array ◽

Array Shape Estimation

Beamforming-based signal enhancement technologies in passive sonar array processing often have poor performance due to array distortion caused by rapid tactical maneuvers of the towed platform, oceanic currents, hydrodynamic effects, etc. In this paper, an enhanced data-driven shape array estimation formulation is proposed using passive underwater acoustic data. Beamforming based on a hypothetically ideal array is firstly employed to perform the detection of narrow-band components from sources of opportunity, and the corresponding phases of these detected narrow-band components are subsequently extracted to acquire time-delay differences. Then, a weighted outlier-robust Kalman smoother is proposed to acquire enhanced estimates of the time-delay differences, since the underlying properties of slowly changing time-delay differences in the hydrophone array and diverse signal to interference and noise ratios in multiple narrow-band components are explored; and its Cramer–Rao Lower Bound is also provided. Finally, the hydrophone array shape is estimated based on the estimated time delay differences. The proposed formulation fully exploits directional radiated noise signals from distant underwater acoustic targets as sources of opportunity for real-time array shape estimation, and thus it requires neither the number nor direction of sources to be known in advance. The effectiveness of the proposed method is validated in simulations and real experimental data.

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JOINT ESTIMATION OF THE TRANSMISSIBILITY AND SEVERITY OF EBOLA VIRUS DISEASE IN REAL TIME

Journal of Biological System ◽

10.1142/s0218339017400022 ◽

2017 ◽

Vol 25 (04) ◽

pp. 587-603 ◽

Cited By ~ 2

Author(s):

YUSUKE ASAI ◽

HIROSHI NISHIURA

Keyword(s):

Real Time ◽

Ebola Virus ◽

Virus Disease ◽

Critical Role ◽

Estimation Method ◽

Case Fatality ◽

Ascertainment Bias ◽

Joint Estimation ◽

Ebola Virus Disease ◽

Strong Impact

The effective reproduction number [Formula: see text], the average number of secondary cases that are generated by a single primary case at calendar time [Formula: see text], plays a critical role in interpreting the temporal transmission dynamics of an infectious disease epidemic, while the case fatality risk (CFR) is an indispensable measure of the severity of disease. In many instances, [Formula: see text] is estimated using the reported number of cases (i.e., the incidence data), but such report often does not arrive on time, and moreover, the rate of diagnosis could change as a function of time, especially if we handle diseases that involve substantial number of asymptomatic and mild infections and large outbreaks that go beyond the local capacity of reporting. In addition, CFR is well known to be prone to ascertainment bias, often erroneously overestimated. In this paper, we propose a joint estimation method of [Formula: see text] and CFR of Ebola virus disease (EVD), analyzing the early epidemic data of EVD from March to October 2014 and addressing the ascertainment bias in real time. To assess the reliability of the proposed method, coverage probabilities were computed. When ascertainment effort plays a role in interpreting the epidemiological dynamics, it is useful to analyze not only reported (confirmed or suspected) cases, but also the temporal distribution of deceased individuals to avoid any strong impact of time dependent changes in diagnosis and reporting.

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Improvement of Reliability Determination Performance of Real Time Kinematic Solutions Using Height Trajectory

Sensors ◽

10.3390/s21020657 ◽

2021 ◽

Vol 21 (2) ◽

pp. 657

Author(s):

Aoki Takanose ◽

Yoshiki Atsumi ◽

Kanamu Takikawa ◽

Junichi Meguro

Keyword(s):

Real Time ◽

Urban Areas ◽

Estimation Method ◽

Tall Buildings ◽

Autonomous Driving ◽

Reliability Estimation ◽

Height Variation ◽

Position Information ◽

Real Time Kinematic ◽

Evaluation Test

Autonomous driving support systems and self-driving cars require the determination of reliable vehicle positions with high accuracy. The real time kinematic (RTK) algorithm with global navigation satellite system (GNSS) is generally employed to obtain highly accurate position information. Because RTK can estimate the fix solution, which is a centimeter-level positioning solution, it is also used as an indicator of the position reliability. However, in urban areas, the degradation of the GNSS signal environment poses a challenge. Multipath noise caused by surrounding tall buildings degrades the positioning accuracy. This leads to large errors in the fix solution, which is used as a measure of reliability. We propose a novel position reliability estimation method by considering two factors; one is that GNSS errors are more likely to occur in the height than in the plane direction; the other is that the height variation of the actual vehicle travel path is small compared to the amount of movement in the horizontal directions. Based on these considerations, we proposed a method to detect a reliable fix solution by estimating the height variation during driving. To verify the effectiveness of the proposed method, an evaluation test was conducted in an urban area of Tokyo. According to the evaluation test, a reliability judgment rate of 99% was achieved in an urban environment, and a plane accuracy of less than 0.3 m in RMS was achieved. The results indicate that the accuracy of the proposed method is higher than that of the conventional fix solution, demonstratingits effectiveness.

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Direct measurement and matched-field inversion approaches to array shape estimation

IEEE Journal of Oceanic Engineering ◽

10.1109/48.544050 ◽

1996 ◽

Vol 21 (4) ◽

pp. 393-401 ◽

Cited By ~ 21

Author(s):

W.S. Hodgkiss ◽

D.E. Ensberg ◽

J.J. Murray ◽

G.L. D'Spain ◽

N.O. Booth ◽

...

Keyword(s):

Direct Measurement ◽

Shape Estimation ◽

Array Shape Estimation ◽

Field Inversion

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High-precision roll attitude estimation of decoupled canards relative to the projectile body using bipolar hall-effect sensors

Journal of Intelligent & Fuzzy Systems ◽

10.3233/jifs-189718 ◽

2021 ◽

pp. 1-9

Author(s):

Tingting Yin ◽

Zhong Yang ◽

Youlong Wu ◽

Fangxiu Jia

Keyword(s):

Hall Effect ◽

Real Time ◽

High Precision ◽

Solution Method ◽

Estimation Method ◽

Estimation Algorithm ◽

Attitude Estimation ◽

Fuzzy Algorithms ◽

Positioning Method ◽

Hall Effect Sensors

The high-precision roll attitude estimation of the decoupled canards relative to the projectile body based on the bipolar hall-effect sensors is proposed. Firstly, the basis engineering positioning method based on the edge detection is introduced. Secondly, the simplified dynamic relative roll model is established where the feature parameters are identified by fuzzy algorithms, while the high-precision real-time relative roll attitude estimation algorithm is proposed. Finally, the trajectory simulations and grounded experiments have been conducted to evaluate the advantages of the proposed method. The positioning error is compared with the engineering solution method, and it is proved that the proposed estimation method has the advantages of the high accuracy and good real-time performance.

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High-Accuracy Real-Time Kinematic Positioning with Multiple Rover Receivers Sharing Common Clock

Remote Sensing ◽

10.3390/rs13040823 ◽

2021 ◽

Vol 13 (4) ◽

pp. 823

Author(s):

Lin Zhao ◽

Jiachang Jiang ◽

Liang Li ◽

Chun Jia ◽

Jianhua Cheng

Keyword(s):

Real Time ◽

Ambiguity Resolution ◽

Temporal Stability ◽

Estimation Method ◽

Satellite System ◽

Integer Ambiguity ◽

Dual Frequency ◽

Kinematic Positioning ◽

Real Time Kinematic ◽

Satellite Visibility

Since the traditional real-time kinematic positioning method is limited by the reduced satellite visibility from the deprived navigational environments, we, therefore, propose an improved RTK method with multiple rover receivers sharing a common clock. The proposed method can enhance observational redundancy by blending the observations from each rover receiver together so that the model strength will be improved. Integer ambiguity resolution of the proposed method is challenged in the presence of several inter-receiver biases (IRB). The IRB including inter-receiver code bias (IRCB) and inter-receiver phase bias (IRPB) is calibrated by the pre-estimation method because of their temporal stability. Multiple BeiDou Navigation Satellite System (BDS) dual-frequency datasets are collected to test the proposed method. The experimental results have shown that the IRCB and IRPB under the common clock mode are sufficiently stable for the ambiguity resolution. Compared with the traditional method, the ambiguity resolution success rate and positioning accuracy of the proposed method can be improved by 19.5% and 46.4% in the restricted satellite visibility environments.

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