In this paper, we introduce an indoor-positioning system using ultra-wideband radio signals. To enhance the accuracy of indoor positioning, in our study, we propose to use multiple anchors installed at the same locati...
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In this paper, we introduce an indoor-positioning system using ultra-wideband radio signals. To enhance the accuracy of indoor positioning, in our study, we propose to use multiple anchors installed at the same locations to filter positioning error to reduce the instability caused by receiving signals. In addition, we also propose a filtering algorithm referring to the absolute position and moving-direction information of the positioned object and a prediction method to predict the next position of the positioned object based on previous coordinates. When the error values are out of the acceptable range, it can adopt prediction results to conduct calibration using a control object. From the experimental results, our proposed method is effective in enhancing the accuracy of indoor positioning compared to other related works.
We demonstrate optical Nyquist pulse train generation using a wavelength-selective switch (WSS) without an optical multiplexing circuit. The representative approach generating optical Nyquist pulse trains is based on ...
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We demonstrate optical Nyquist pulse train generation using a wavelength-selective switch (WSS) without an optical multiplexing circuit. The representative approach generating optical Nyquist pulse trains is based on spectral filtering with a WSS and optical time-domain multiplexing (OTDM) with an optical circuit. The use of the optical circuit causes difficulties when extending optical Nyquist pulse train technology to the near-infrared band because this band has no well-established OTDM modules. To resolve this problem, we assign the role of multiplexing to the WSS, in addition to spectral filtering. Furthermore, the WSS-only approach is expected to reduce optical losses and increase pulse-train parameter flexibility. Using only the WSS, we successfully generate optical Nyquist pulse trains in the near-infrared band and realize flexible control of pulse number, width, and interval. In the case of a 10-pulse train, optical loss due to multiplexing is improved by 8.0 dB compared with the conventional method.
Mean orbital elements estimation for geostationary (GEO) satellites is important for related studies, including station-keeping, rendezvous and end-of-life disposal. With increasingly limited operational slots in GEO ...
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Mean orbital elements estimation for geostationary (GEO) satellites is important for related studies, including station-keeping, rendezvous and end-of-life disposal. With increasingly limited operational slots in GEO region and the advance of all-electric-propulsion satellites, a fast and accurate mean orbital element estimation tool is necessary. In order to balance estimation precision and mission cost as well as to be independent of the ground station, this paper develops an autonomous onboard estimation method of the mean orbital elements for geostationary electric-propulsion satellites. Natural perturbations in GEO, including Earth's triaxiality, luni-solar attractions, and solar radiation pressure, are considered. Terms of appropriate orders due to these effects are chosen to model the semi-analytical dynamics, where modified short-period variations and differential mean orbital elements are derived. Regarding mean orbital elements as state variables and osculating orbital elements as measurements, a filter as well as analytical Jacobians is formulated to make the accurate estimation. Five scenarios are simulated to validate the accuracy and efficiency of the proposed method in the GEO region. (C) 2019 Elsevier Masson SAS. All rights reserved.
The detection probability of the radar of the vehicle target tracking system is often less than 1 during driving on urban roads, and the measurement data loss problem may occur. In this paper, the stability of the veh...
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The detection probability of the radar of the vehicle target tracking system is often less than 1 during driving on urban roads, and the measurement data loss problem may occur. In this paper, the stability of the vehicle target tracking system is studied and the sufficient conditions are given for the stability of the mean-square exponent under incomplete measurement conditions. When the probability of detection is known, the Cramer Rao Lower Bound (CRLB) of vehicle target motion parameter estimation is given under the statistical significance of the target tracking system under the condition of incomplete measurement.. The simulation part studies the influence of detection probability on CRLB.
This paper considers performance criteria for the identification of sensor error models and the procedure for their calculation. These criteria are used to investigate the efficiency of the identification problem solu...
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This paper considers performance criteria for the identification of sensor error models and the procedure for their calculation. These criteria are used to investigate the efficiency of the identification problem solution, depending on the initial data, and to carry out a comparative analysis of various suboptimal algorithms. The calculation procedure is based on an algorithm that solves the joint problem of hypothesis recognition and parameter estimation within the Bayesian approach. A performance analysis of the models traditionally used to describe errors of inertial sensors is given to illustrate the application of the procedure for the calculation of performance criteria.
Establishing a model equation with high accuracy and high computational efficiency is very important for the estimation of battery state of charge (SOC). To ensure better SOC estimation results, most studies have focu...
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Establishing a model equation with high accuracy and high computational efficiency is very important for the estimation of battery state of charge (SOC). To ensure better SOC estimation results, most studies have focused on the improvement of the algorithm, while the impact of the model equation which may offset the benefits of advanced algorithms has been overlooked. To address this problem, this paper studies the widely used model equations and presents a new model equation based on a Gaussian function that improves the SOC estimation accuracy and computational efficiency. With the Worldwide harmonized Light Vehicles Test Cycle (WLTC) which is highly dynamic and more realistic than any other driving cycles, the proposed model equation is applied to different filtering algorithms to validate its performance in SOC estimation. The results indicate that the proposed model equation can greatly improve the accuracy of SOC estimation without an increase of computation. In addition, for the traditional polynomial-based model equations, the 6th-order power function polynomial has better performance in SOC estimation than polynomials with other orders.
A point clouds filtering algorithm is presented based on Grid Partition using Dynamic Quad Tress and Moving Least Squares. First, points are partitioned reasonably and corresponding Dynamic Quad Trees indices are esta...
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A point clouds filtering algorithm is presented based on Grid Partition using Dynamic Quad Tress and Moving Least Squares. First, points are partitioned reasonably and corresponding Dynamic Quad Trees indices are established. Second, points in grids are utilized to fit a DEM reference plane using moving least squares technology. Finally, ground points are separated from those non-ground ones if they are positioned above the reference plane and have a distance to the plane exceeding threshold value. Experiments show that this filtering algorithm is of high precision and identify ground points effectively without losing detailed topography information. (c) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Society for Resources, Environment and Engineering
With an increasing number of artificial satellites and spacecraft launched in the last few years, ground based orbit determination systems, such as normally used Satellite User Ranging(SLR) is encountering with overlo...
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With an increasing number of artificial satellites and spacecraft launched in the last few years, ground based orbit determination systems, such as normally used Satellite User Ranging(SLR) is encountering with overload work and rapidly growing cost, GPS based autonomous orbit determination is playing a more and more important role, especially for Low Earth Orbit (LEO) satellites in Terrestrial Service Volume (TSV). However, GPS is not able to be utilized in Space Service Volume (SSV) because of the fact that available GPS satellites would be deficient in many conditions. In order to realize GPS based autonomous orbit determination in SSV for High Earth Orbit (HEO) and Geosynchronous (GEO) satellites, an autonomous orbit determination method with deficient GPS measurement complemented with orbital dynamics and altitude measurements from other sensors is proposed in this study. A simulation demonstrates that this approach is able to provide hundred-meter level positioning precision with only two available satellites, whereas, the satellite position would diverse beyond more than 10,000 m if only utilizing orbit dynamics, which authenticates a satisfactory performance of the proposed method. The proposed autonomous orbit determination approach is expected to be able to provide services to HEO and GEO satellites as well as other deep space exploration spacecraft in GPS SSV.
In the modern technology warfare, infrared weak target detection technology occupies a very important position. In civil use, the infrared weak target detection technology has also been widely applied and developed. T...
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In the modern technology warfare, infrared weak target detection technology occupies a very important position. In civil use, the infrared weak target detection technology has also been widely applied and developed. The application and research status of infrared weak targets are briefly analyzed. The characteristics of infrared weak targets are introduced. The principles and steps of some classic improved methods for infrared small target detection methods in recent years are summarized. Finally, the differences of several classical algorithms such as Gauss filtering, mean filtering, median filtering, morphology and adaptive Wiener filtering are compared. This paper lays a foundation for the learning of infrared small target detection algorithm and is helpful to the research of improved algorithm for infrared small target detection.
The detection probability of the radar of the vehicle target tracking system is often less than 1 during driving on urban roads, and the measurement data loss problem may occur. In this paper, the stability of the veh...
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The detection probability of the radar of the vehicle target tracking system is often less than 1 during driving on urban roads, and the measurement data loss problem may occur. In this paper, the stability of the vehicle target tracking system is studied and the sufficient conditions are given for the stability of the mean-square exponent under incomplete measurement conditions. A suboptimal estimation algorithm for vehicle target tracking motion parameters under incomplete measurement conditions is given when the detection probability is known. The simulation results show that the proposed filtering algorithm is effective.
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