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2025 International Technical Meeting of The Institute of Navigation, ITM 2025

作者： Jia, Qiongqiong Zhao, Yuchen China Civil Aviation University Tianjin Key Laboratory of Intelligent Signal and Image Processing Tianjin300000 China

ISBN: (纸本)9780936406404

Acquisition is a key step for Global Navigation Satellite System (GNSS) receivers to achieve positioning and other functions, and the acquisition speed directly affects the Time To First Fix (TTFF) of the receiver. The acquisition process typically involves generating local reference signals for all satellite signals and matching them with the received signals. For each satellite signal, this matching involves searching in the unknown Doppler frequency and code phase space. Traditional parallel acquisition methods can only perform parallel processing in either the Doppler frequency dimension or the code phase dimension, and still require linear search in the other dimension. To reduce the computational load and improve the acquisition efficiency, this paper proposes a high-efficiency parallel acquisition method based on A-GPS. This method utilizes the auxiliary information provided by the A-GPS base station to convert the linear search of visible star signals in Doppler frequency into a single parallel search in the Doppler search space, thereby reducing the computational load required for acquisition to 1/N of the conventional method, where N is the total number of frequency bands searched. The paper verifies through theoretical analysis and experimental results that the proposed method can significantly improve acquisition efficiency while ensuring acquisition performance. © 2025 Proceedings of the International Technical Meeting of The Institute of Navigation, ITM. All rights reserved.

关键词： Global positioning system

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Design of Dual-mode DPE Receiver Based on GPS L1/BDS B1C signals

Design of Dual-mode DPE Receiver Based on GPS L1/BDS B1C Sig...

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2025 International Technical Meeting of The Institute of Navigation, ITM 2025

作者： Jia, Qiongqiong Guo, Qiqi Tianjin Key Laboratory of Intelligent Signal and Image Processing Civil Aviation University of China Tianjin300000 China

ISBN: (纸本)9780936406404

With the expanding applications of the Global Navigation Satellite System (GNSS), its operating environment has become increasingly complex, with challenges such as multipath effects, non-line-of-sight (NLOS) propagation, and signal attenuation caused by tall urban buildings and trees. This complexity poses additional challenges for traditional GNSS receivers. Direct Position Estimation (DPE) addresses some of the limitations of traditional receivers by accumulating signals from all visible satellites directly in the navigation domain. However, when severe obstructions result in a reduced number of visible satellites, DPE may fail to function properly. The introduction of multiconstellation satellite signals can help mitigate the issue of insufficient visible satellites in complex environments. Based on this, this paper designs a dual-mode DPE receiver utilizing Global Positioning System (GPS) L1 signals and BeiDou Navigation Satellite System (BDS) B1C signals. © 2025 Proceedings of the International Technical Meeting of The Institute of Navigation, ITM. All rights reserved.

关键词： Global positioning system

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VnDark: iterative enhanced feature learning network for nighttime airfield object detection

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signal, image and Video processing 2025年第7期19卷 1-14页

作者： Luo, Qijun Zhang, Xuerui Fang, Xigao Zheng, Zhiming Zhang, Tao Tianjin Key Laboratory for Advanced Signal Processing Civil Aviation University of China Tianjin China Institute of Shanghai Aircraft Design and Research Commercial Aircraft Corporation of China Shanghai China

Using onboard vision collection and recognition technologies, the visual assistance driving system for civil aviation aircraft captures information about the surrounding threat scenario to assist pilots in making driving judgments. However, nighttime scene images deteriorate, leading to low visual clarity and decreased scene object detection accuracy. Current object detection algorithms are unable to simultaneously enhance nighttime visual clarity and accurately detect scene objects. To address this problem, a convolutional neural network named VnDark based on iterative feature enhancement learning is proposed. A feature enhancement sub-network is designed based on an iterative light enhancement curve mechanism, which employs a U-shaped encoder-decoder structure to produce sharp edge features from nighttime images, enhancing scene visibility. A multi-task feature collaborative optimization strategy is designed, which shares the enhanced features generated by the feature enhancement sub-network with the object detection sub-network and employs a multi-task weight learning algorithm to optimize the weights for nighttime image enhancement, object classification, and localization tasks. This strategy improves the accuracy of scene object detection. A nighttime scene object dataset containing real-world and simulation data is established to validate VnDark’s performance. Experimental results indicate that the network can accurately detect scene objects while simultaneously enhancing the visibility of dark images. In the enhanced images, the original dark area objects are clearly visible, making them easier for human observation. The average precision of object detection reached 78.5%. Additionally, the proposed algorithm achieved an average precision of 69.3% on the public dataset Exclusively Dark, surpassing typical general object detectors such as Faster R-CNN, SSD, YOLOv7, and YOLOv5s. Both precision and speed of the proposed algorithm surpass that of typical nighttim

关键词： Multi-task learning

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Improving Integrality of Detected Moving Objects Based on image Matting

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Chinese Journal of Electronics 2025年第4期23卷 742-746页

作者： Liang Zhang Haili Wang Tao Deng Xiaomei He Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China Tianjin China Training Center of Engineering Technology Civil Aviation University of China Tianjin China

The integrality of moving objects is the basis for video-based object tracking and action analysis. But it often becomes unreliable as a result of shadow elimination when the object has similar properties with real shadow. The proposed methods manage to improve the integrality of detected moving objects as much as possible, by image matting operated on candidate shadow regions. Existing approaches for image matting require manual labeling of foreground and background. Considering the moving feature points in shadow may cause classification errors, we propose automatic scribbling methods based on Scale invariant feature transform (SIFT) and Speeded-up robust feature (SURF) respectively. Experiments demonstrate that our methods eliminate real shadow effectively and improve object segmentation in the case of object parts and shadows presenting similar characteristics.

关键词： Object segmentation Transforms Manuals Object tracking labeling

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Contractive Difference-of-Convex Algorithms

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Journal of Optimization Theory and Applications 2025年第1期206卷 1-21页

作者： He, Songnian Dong, Qiao-Li Rassias, Michael Th. Tianjin Key Laboratory for Advanced Signal Processing and College of Science Civil Aviation University of China Tianjin300300 China Department of Mathematics and Engineering Sciences Hellenic Military Academy Vari Attikis16673 Greece Institute for Advanced Study Program in Interdisciplinary Studies 1 Einstein Dr Princeton08540 United States

The difference-of-convex algorithm (DCA) and its variants are the most popular methods to solve the difference-of-convex optimization problem. Each iteration of them is reduced to a convex optimization problem, which generally needs to be solved by iterative methods such as proximal gradient algorithm. However, these algorithms essentially belong to some iterative methods of fixed point problems of averaged mappings, and their convergence speed is generally slow. Furthermore, there is seldom research on the termination rule of these iterative algorithms solving the subproblem of DCA. To overcome these defects, we firstly show that the subproblem of the linearized proximal method (LPM) in each iteration is equal to the fixed point problem of a contraction. Secondly, by using Picard iteration to approximately solve the subproblem of LPM in each iteration, we propose a contractive difference-of-convex algorithm (cDCA) where an adaptive termination rule is presented. Both global subsequential convergence and global convergence of the whole sequence of cDCA are established. Finally, preliminary results from numerical experiments are promising. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.

关键词： Conjugate gradient method

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Autonomous Path Planning via Sand Cat Swarm Optimization With Multi-Strategy Mechanism for Unmanned Aerial Vehicles in Dynamic Environment

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IEEE Internet of Things Journal 2025年

作者： Deng, Wu Feng, Jiayi Zhao, Huimin Civil Aviation University of China College of Electronic Information and Automation Tianjin300300 China Civil Aviation University of China Tianjin Key Lab Intelligent Signal and Image Processing Tianjin300300 China State Key Laboratory of Rail Transit Vehicle System of Southwest Jiaotong University Chengdu610031 China

Unmanned Aerial Vehicles (UAVs) face critical challenges in path planning in dynamic environment. Sand Cat Swarm Optimization (SCSO) algorithm has demonstrated promise in addressing complex optimization challenges. However, SCSO is limited by slow convergence, susceptibility to local optima, and insufficient adaptability. To overcome these shortcomings, an enhanced SCSO with the spiral search, Livy flight, tent chaotic mapping, and adaptive sparrow alert mechanism, namely TSLS-SCSO is developed to propose an autonomous path planning method for UAVs in dynamic environment. In TSLS-SCSO, a new population initialization strategy with tent chaotic mapping is designed to achieve a large dynamic range and coverage capability. Then a new spiral search strategy is designed to broaden the search range in the search phase. And a new Livy flight strategy is employed to enrich the diversity of population in the attacking prey phase. A new sparrow alert mechanism with integrating the sand cat group with the sparrow alert is designed to obtain faster convergence speed and accuracy. The experiment results on CEC 2017 and CEC 2022 show that the TSLS-SCSO obtains higher accuracy and more stable solutions and exhibits better competitiveness. Furthermore, the proposed UAV path planning method successfully found effective paths with an obstacle avoidance effectiveness of 95.5%. The obtained results validate the effectiveness and competitiveness of TSLS-SCSO in UAV path planning in the dynamic environment. © 2014 IEEE.

关键词： Unmanned aerial vehicles (UAV)

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Intelligent checking model of Chinese radiotelephony read-backs in civil aviation air traffic control

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Chinese Journal of Aeronautics 2018年第12期31卷 2280-2289页

作者： Guimin JIA Fangyuan CHENG Jinfeng YANG Dan LI Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China

Federal aviation Administration(FAA) and NASA technical reports indicate that the misunderstanding in radiotelephony communications is a primary causal factor associated with operation errors, and a sizable proportion of operation errors lead to read-back errors. We introduce deep learning method to solve this problem and propose a new semantic checking model based on Long Short-Time Memory network(LSTM) for intelligent read-back error checking. A meanpooling layer is added to the traditional LSTM, so as to utilize the information obtained by all the hidden activation vectors, and also to improve the robustness of the semantic vector extracted by LSTM. A MultiLayer Perceptron(MLP) layer, which can maintain the information of different regions in the concatenated vectors obtained by the mean-pooling layer, is applied instead of traditional similarity function in the new model to express the semantic similarity of the read-back pairs quantitatively. The K-Nearest Neighbor(KNN) classifier is used to verify whether the read-back pairs are consistent in semantics according to the output of MLP layer. Extensive experiments are conducted and the results show that the proposed model is more effective and more robust than the traditional checking model to verify the semantic consistency of read-backs automatically.

关键词： Air traffic control Chinese radiotelephony read-backs LSTM Mean pooling MLP Semantic checking

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image edge detection based on adaptive weighted morphology

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Chinese Optics Letters 2007年第2期5卷 77-78页

作者：蒋立辉郭艳颖 Tianjin Key Laboratory for Advanced Signal Processing Civil Aviation University of ChinaTianjin 300300

A novel morphological edge detector based on adaptive weighted morphological operators is presented. It judges image edge and direction by adaptive weighted morphological structuring elements （SEs）. If the edge direction exists, a big weight factor in SE is put; if it does not exist, a small weight factor in SE is put. Thus we can achieve an intensified edge detector. Experimental results prove that the new operator＇s performance dominates those of classical operators for images in edge detection, and obtains superbly detail edges.

关键词： Detectors image processing Mathematical operators Morphology

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A two-stage approach for managing actuators redundancy and its application to fault tolerant flight control

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Chinese Journal of Aeronautics 2015年第2期28卷 469-477页

作者： Zhong Lunlong Félix Mora-Camino Tianjin Key Laboratory for Advanced Signal and Image Processing Civil Aviation University of China Automation Research Group of MAIAA ENAC Toulouse University

In safety-critical systems such as transportation aircraft, redundancy of actuators is introduced to improve fault tolerance. How to make the best use of remaining actuators to allow the system to continue achieving a desired operation in the presence of some actuators failures is the main subject of this paper. Considering that many dynamical systems, including flight dynamics of a transportation aircraft, can be expressed as an input affine nonlinear system, a new state repre- sentation is adopted here where the output dynamics are related with virtual inputs associated with the intended operation. This representation, as well as the distribution matrix associated with the effectiveness of the remaining operational actuators, allows us to define different levels of fault tol- erant governability with respect to actuators＇ failures. Then, a two-stage control approach is devel- oped, leading frst to the inversion of the output dynamics to get nominal values for the virtual inputs and then to the solution of a linear quadratic （LQ） problem to compute the solicitation of each operational actuator. The proposed approach is applied to the control of a transportation air- craft which performs a stabilized roll maneuver while a partial failure appears. Two fault scenarios are considered and the resulting performance of the proposed approach is displayed and discussed.

关键词： Actuator allocation Fault tolerant control Flight control Linear quadratic （LQ）problem Nonlinear control

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A novel strategy for fine-grained semantic verification of civil aviation radiotelephony read-backs

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Chinese Journal of Aeronautics 2022年第12期35卷 266-277页

作者： Guimin JIA Junxian LI Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of ChinaTianjin 300300China College of Electronic Information and Automation Civil Aviation University of ChinaTianjin 300300China

During the flight of the aircraft,the pilot must repeat the instruction sent by the controller,and the controller must further confirm these read-backs,in this way to further ensure the safety of air ***,fatigue,tension,negligence and other human factors may prevent the controller from realizing read-back errors in time,which is a huge hidden danger for the safety of civil aviation *** paper proposes a novel strategy to implement fine-grained semantic verification of radiotelephony read-backs by introducing interaction layer and attention mechanism at the output of BiLSTM *** with the traditional twochannel verification strategy,the interaction layer is added to obtain fine-grained semantic matching relation representation,rather than connecting the BiLSTM output vectors to obtain the overall semantic representation of the *** by adding attention layer,the new strategy can capture the potential semantic relation between the read-backs and the instructions,which is applicable to non-standard diction and abbreviated read-backs in real radiotelephony *** experiments are conducted and the results show that the proposed new strategy is more effective than the traditional method for read-backs checking,and the average test accuracy of the new strategy based on the Chinese ATC radiotelephony read-backs corpus can reach 93.03%.

关键词： Attention mechanism BiLSTM Interaction layer Radiotelephony read-backs Semantic verification

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