With the rapid development of expressway Electronic Toll Collection (ETC) technology in China, the expressway management system is becoming digital and intelligent, which provides a solid foundation for expressway veh...
详细信息
With the rapid development of expressway Electronic Toll Collection (ETC) technology in China, the expressway management system is becoming digital and intelligent, which provides a solid foundation for expressway vehicle infrastructure cooperation and autonomous driving. The gantry position is the key part of the ETC system. However, there are still some problems (e.g. gantry position missing or false), which can seriously affect the intelligent development of expressways. To address these two issues, an ETC gantry positioning method is proposed. First, the ETC transaction data and the GPS data on expressways are preprocessed to remove abnormal data and retrieve missed data. Then, combined with Dead Reckoning (DR) and Median Center, the potential position of the gantry is calculated from ETC transaction data and GPS data. Finally, the switching strategy based on Kalman Filter (KF) is used to capture the final gantry position. By comparing the results of the proposal with the collected gantry position, it is found that the positioning error of the gantry position calculated by this proposal is about 37 m. The positioning accuracy is 98.78% with the threshold of 100 m. The experimental results show that the proposal can effectively locate the expressway gantry.
The false-target echo generation to Inverse Synthetic Aperture Radar (ISAR) is significant in jamming the enemy ISAR and promoting ISAR development. Generally, it requires false-target echo coherent with the radar, re...
详细信息
The false-target echo generation to Inverse Synthetic Aperture Radar (ISAR) is significant in jamming the enemy ISAR and promoting ISAR development. Generally, it requires false-target echo coherent with the radar, real time and fine. However, conventional methods, such as digital image synthesizer (DIS), cannot meet those requirements. Moreover, existing methods do not consider the target's radial moving. To meet those demands, we propose an improved method in this study. We equivalently model echo formation as the synthesizer of two independent parts: (1) echo of remote target with radial moving and (2) echo of nearby extended target. In part one, accuracy is improved by utilising the Inner Pulse Motion (IPM) model and complexity is simplified by deducing it as a frequency offset modulation. In part two, the fine extended target echo is constructed by using convolution filtering whose resources consumption can be greatly reduced by separating it into an offline stage and a real-time stage. Our method is verified by algorithm simulations and actual experiments. The results indicate that it can build the fine false-target echo in real-time and can adapt to the target's radial velocity, different resolution and size. Compared with the conventional DIS method, our method reduces the computational complexity significantly and has more comprehensive functions.
In this study, a real-time high accuracy signal simulation technique for an enhanced Loran (eLoran) signal simulator is proposed, which can be used to verify the performance of the eLoran receiver. The proposed method...
详细信息
In this study, a real-time high accuracy signal simulation technique for an enhanced Loran (eLoran) signal simulator is proposed, which can be used to verify the performance of the eLoran receiver. The proposed method is based on a maximumly flat design of the low-pass filter, and high simulation accuracy can be obtained in the low-frequency band. The simulator structure is based on the variable fractional delay Farrow structure, which can regenerate eLoran signals with high-precision time of arrival (TOA) in real-time based on discrete samples on a hardware platform. By comparison of existing methods and the true TOA data validation, the proposed method has high performance for low-frequency narrow-band eLoran signals and the proposed technology can apply to arbitrary TOA real-time simulations.
The existing adaptive Kalman filters for tracking manoeuvring targets by wireless sensor networks can easily lose robustness when both the measurement and process noises are unknown and time-varying, resulting in larg...
详细信息
The existing adaptive Kalman filters for tracking manoeuvring targets by wireless sensor networks can easily lose robustness when both the measurement and process noises are unknown and time-varying, resulting in large positioning errors. To solve this problem, a wireless sensor network manoeuvring target tracking algorithm using a novel robust adaptive cubature Kalman filter is proposed. This innovative robust adaptive cubature Kalman filter consists of a derived third-order biased noise statistic estimator and conventional cubature Kalman filter. This derived noise statistic estimator can simultaneously sense time-varying and unknown measurement and process noises and ensure that the adaptive cubature Kalman filter's robustness is not lost. The robustness of the novel robust adaptive cubature Kalman filter is strictly proven in this study. Extensive practical experiments and numerical simulations show that the proposed robust adaptive cubature Kalman filter always has higher target tracking accuracy than other existing adaptive Kalman filters, regardless of whether the mobile target is manoeuvring or not, the noise is unknown or time-varying, and the number of anchor nodes is few or many.
The indoor moving target localization based on the received signal strength indicator is studied in this paper. By introducing filtering algorithms, a novel dynamic parameters set-membership filtering (DPSMF) is propo...
详细信息
The indoor moving target localization based on the received signal strength indicator is studied in this paper. By introducing filtering algorithms, a novel dynamic parameters set-membership filtering (DPSMF) is proposed to reduce the interference of the multipath effect and noises. First, the higher-order remainder is included in the bounded range based on the interval mathematics method to improve the linearization accuracy of the Taylor series expansion of the measurement function. Second, the parameters to be determined in the channel model are set to local dynamic parameters, which are obtained by solving a particular semi-definite programming problem. Third, the optimized localization estimations of the target node at each sampling instant and the ellipsoid set containing the real state of the system are obtained based on the DPSMF. Finally, an example is given to verify the effectiveness of the proposed DPSMF algorithm.
As quotidian use of sophisticated cameras surges, people in modern society are more interested in capturing fine-quality images. However, the quality of the images might be inferior to people's expectations due to...
详细信息
As quotidian use of sophisticated cameras surges, people in modern society are more interested in capturing fine-quality images. However, the quality of the images might be inferior to people's expectations due to the noise contamination in the images. Thus, filtering out the noise while preserving vital image features is an essential requirement. Existing denoising methods have assumptions, on the probability distribution in which the contaminated noise is sampled, for the method to attain its expected denoising performance. In this paper, the recent Gramian-based filtering scheme to remove noise sampled from five prominent probability distributions from selected images is utilized. This method preserves image smoothness by adopting patches partitioned from the image, rather than pixels, and retains vital image features by performing denoising on the manifold underlying the patch space rather than in the image domain. Its denoising performance is validated, using six benchmark computer vision test images applied to two state-of-the-art denoising methods, namely BM3D and K-SVD.
With the conventional perturbation and observation (P&O) method, photovoltaic (PV) converters have long maximum power point (MPP) tracking times and three-point oscillations at the steady state that can lead to ou...
详细信息
With the conventional perturbation and observation (P&O) method, photovoltaic (PV) converters have long maximum power point (MPP) tracking times and three-point oscillations at the steady state that can lead to output power losses and inefficiencies in grid connections. To overcome these drawbacks, a fast tracking and steady-state-oscillation-free control strategy is proposed. The strategy first stores four random duty cycle values on the basis of the duty cycle variation characteristics of the PV panel power adjustment, then calculates the odd and even duty cycle difference and judges the steady state by varying the duty cycle difference threshold. The strategy next obtains the MPP duty cycle using a median filtering algorithm (MFA) to suppress the steady-state oscillation and improves the tracking speed by resetting the appropriate duty cycle step according to the slope of the PV curve of the PV panel output and the corresponding adaptive coefficients. The proposed algorithm was simulated and experimentally validated under various irradiance conditions, and the results show that the algorithm can improve the PV panel output efficiency compared to both the conventional P&O and the adaptive P&O methods.
The parameter estimation for transmission systems is important to power flow analysis, planning the expansion of electric power systems, stability, dispatch and economic analysis. This type of task is developed throug...
详细信息
The parameter estimation for transmission systems is important to power flow analysis, planning the expansion of electric power systems, stability, dispatch and economic analysis. This type of task is developed through systems identification methods, being the least squares method and its variations the most common techniques to obtain the transmission line parameters. However, these techniques have some disadvantages, such as non-recursive parameter estimation or the availability of an ideally transposed line, in order to address a problem with symmetric matrices, which simplifies the estimation process. In this paper, a non-linear method (Extended Kalman Filter) is presented to obtain the states of the transmission line terminals jointly with the vectorized matrix of parameters;such approach is strongly affected by the initial conditions;these conditions are usually obtained manually, which requires a lot of time and effort. Therefore, an optimization method (Particle Swarm Optimization) is applied in order to improve the convergence of the EKF, which reduces the time for adjusting the hyper-parameters and improves the estimated results. The proposed method showed accurate results for non-transposed systems, and also in comparison with results obtained from the same EKF-based method without the proposed optimization technique.
This paper is concerned with the recursive fusion estimation-based mobile robot localization (RL) problem by employing multiple energy harvesting sensors (EHSs). In the addressed RL problem, multiple sensors with ener...
详细信息
This paper is concerned with the recursive fusion estimation-based mobile robot localization (RL) problem by employing multiple energy harvesting sensors (EHSs). In the addressed RL problem, multiple sensors with energy harvesting capacity are deployed to produce measurements used for RL. When the sensors own sufficient energy, the sensors can output measurements and then send them to the corresponding local filter. Otherwise, the sensor energy-induced missing measurement phenomenon will occur. In order to obtain the missing measurement rate, at each time instant, the relationship between the totality of the sensor energy and its probability distribution is derived recursively. This paper aims at seeking out a practicable solution to the addressed mobile RL problem. First, in the presence of the sensor energy-induced measurement missing phenomenon, an upper bound (UB) of the local localization error covariance is recursively acquired. Then, such a derived UB is minimized by suitably devising the desired local filter parameter. Subsequently, the covariance intersection fusion method is adopted to achieve the addressed RL problem. In the end, a simulation is conducted to verify the practicability of the developed RL scheme.
This study suggests a dynamic current cut-off frequency-based pole-zero cancellation speed controller for permanent magnet synchronous motors (PMSMs). The proposed self-tuning algorithm automatically increases the cur...
详细信息
This study suggests a dynamic current cut-off frequency-based pole-zero cancellation speed controller for permanent magnet synchronous motors (PMSMs). The proposed self-tuning algorithm automatically increases the current cut-off frequency during only the transient periods and restores it as approaching the steady-state operation. The outer loop control injects the active damping effect, resulting in a closed-loop order reduction by pole-zero cancellation from the particularly structured feedback gain. These two benefits contribute to the following advantages: (a) lowering the steady-state current cut-off frequency to improve the relative stability margin and (b) securing the capability of assigning the desired cut-off frequency to both the inner and outer loops in the first-order low-pass filter form. A 500-W PMSM experimental prototype platform confirms the effectiveness of the proposed controller.
暂无评论