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A data and physical model dual-driven based trajectory estimator for long-term navigation

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Defence Technology（防务技术） 2024年第10期40卷 78-90页

作者： Tao Feng Yu Liu Yue Yu Liang chen ruizhi chen School of Communications and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong Kong999077China Chongqing Key Laboratory of Autonomous Navigation and Microsystem Chongqing University of Post and TelecommunicationsChongqing400065China State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing(LIESMARS)Wuhan UniversityWuhan430000China

Long-term navigation ability based on consumer-level wearable inertial sensors plays an essential role towards various emerging fields, for instance, smart healthcare, emergency rescue, soldier positioning et al. The performance of existing long-term navigation algorithm is limited by the cumulative error of inertial sensors, disturbed local magnetic field, and complex motion modes of the pedestrian. This paper develops a robust data and physical model dual-driven based trajectory estimation(DPDD-TE) framework, which can be applied for long-term navigation tasks. A Bi-directional Long Short-Term Memory(Bi-LSTM) based quasi-static magnetic field(QSMF) detection algorithm is developed for extracting useful magnetic observation for heading calibration, and another Bi-LSTM is adopted for walking speed estimation by considering hybrid human motion information under a specific time period. In addition, a data and physical model dual-driven based multi-source fusion model is proposed to integrate basic INS mechanization and multi-level constraint and observations for maintaining accuracy under long-term navigation tasks, and enhanced by the magnetic and trajectory features assisted loop detection algorithm. Real-world experiments indicate that the proposed DPDD-TE outperforms than existing algorithms, and final estimated heading and positioning accuracy indexes reaches 5° and less than 2 m under the time period of 30 min, respectively.

关键词： Long-term navigation Wearable inertial sensors Bi-LSTM QSMF Data and physical model dual-driven

Multipath tracking with LTE signals for accurate TOA estimation in the application of indoor positioning

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Geo-Spatial Information Science 2023年第1期26卷 31-43页

作者： Zhaoliang Liu Liang chen Xin Zhou Nan Shen ruizhi chen The State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina

Indoor positioning with high accuracy plays an important role in different application *** a widely used mobile communication signal,the Long-Term Evolution(LTE)network can be well received in indoor and outdoor *** article studies a method of using different reference signals in the LTE downlink for carrier phase time of arrival(TOA)***,a solution is proposed and a multipath tracking Software Defined Receiver(SDR)is developed for indoor *** our SDR indoor positioning system,the pilot signals of the LTE signals are firstly obtained by the coarse synchronization and ***,with the assistance of the pilot signals,the time delay acquisition,the multipath estimating delay lock loop(MEDLL)algorithm,and the multipath anomaly detection are sequentially carried out to obtain navigation observations of received ***,to compare the perfor-mance of different pilot signals,the Secondary Synchronous Signals(SSS)and Cell Reference Signals(CRS)are used as pilot signals for carrier phase-based TOA estimation,***,to quantify the accuracy of our multipath tracking SDR,indoor field tests are carried out in a conference environment,where an LTE base station is installed for commercial *** test results based on CRS show that,in the static test scenarios,the TOA accuracy measured by the 1-σerror interval is about 0.5 m,while in the mobile environment,the probability of range accuracy within 1.0 m is 95%.

关键词： Long-Term Evolution(LTE) indoor positioning multipath estimation delay locked loop(MEDLL) carrier phase time of arrival(TOA)

VNLSTM-PoseNet: A novel deep ConvNet for real-time 6-DOF camera relocalization in urban streets

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Geo-Spatial Information Science 2021年第3期24卷 422-437页

作者： Ming Li Jiangying Qin Deren Li ruizhi chen Xuan Liao Bingxuan Guo State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan UniversityWuhanChina Department of Physics ETH ZurichZurichSwitzerland Department of Land Surveying and Geo-informatics The Hong Kong Polytechnic UniversityHong KongChina

Image-based relocalization is a renewed interest in outdoor environments,because it is an important problem with many *** introduces Convolutional Neural Network(CNN)for the first time to realize the real-time camera pose solution based on a single *** order to solve the problem of precision and robustness of PoseNet and its improved algorithms in complex environment,this paper proposes and implements a new visual relocation method based on deep convolutional neural networks(VNLSTM-PoseNet).Firstly,this method directly resizes the input image without cropping to increase the receptive field of the training ***,the image and the corresponding pose labels are put into the improved Long Short-Term Memory based(LSTM-based)PoseNet network for training and the network is optimized by the Nadam ***,the trained network is used for image localization to obtain the camera *** results on outdoor public datasets show our VNLSTM-PoseNet can lead to drastic improvements in relocalization performance compared to existing state-of-theart CNN-based methods.

关键词： Camera relocalization pose regression deep convnet RGB image camera pose

Indoor positioning based on tightly coupling of PDR and one single Wi-Fi FTM AP

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Geo-Spatial Information Science 2023年第3期26卷 480-495页

作者： Yuan Wu ruizhi chen Wenju Fu Wei Li Haitao Zhou Guangyi Guo State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing(LIESMARS)Wuhan UniversityWuhanChina

The indoor positioning system is now an important technique as part of the Internet-of-Things(IoT)*** indoor positioning techniques,multiple Wi-Fi Access Points(APs)-based positioning systems have been researched a *** is a lack of research focusing on the scene where only one Wi-Fi AP is *** work proposes a hybrid indoor positioning system that takes advantage of the Fine-Timing Measurements(FTM)technique that is part of the IEEE 802.11mc standard,introduced back in *** system uses one single Wi-Fi FTM AP and takes advantage of the built-in inertial sensors of the smartphone to estimate the device’s *** explore both Loosely Coupled(LC)and Tightly Coupled(TC)integration schemes for the sensors’data *** results show that the proposed methods can achieve an average positioning accuracy of about 1 m without knowing the initial *** with the LC integration method,the median error accuracy of the proposed TC fusion algorithm has improved by more than 52%and 67%,respectively,in the two experiments we set up.

关键词： Indoor positioning Wi-Fi Fine Time Measurement(FTM)/Round Trip Time(RTT) Tightly Coupled(TC)integration Pedestrian Dead Reckoning(PDR) Extended Kalman Filter(EKF)

An infant monitoring system with the support of accurate real-time indoor positioning

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Geo-Spatial Information Science 2019年第4期22卷 279-289,I0005页

作者： Zhipeng Cao Yifan cheng ruizhi chen Guangyi Guo Feng Ye Liang chen Yuanjin Pan State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina School of Remote Sensing and Information Engineering Wuhan UniversityWuhanChina

This article presents an indoor infant monitoring system based on Android system which employs a low-cost Bluetooth Low Energy(BLE)pseudolite to accurately locate the infants in the activity indoors and timely remind the *** can achieve a positioning accuracy better than 2 m and effectively reduce the risk of injury to infants and young *** performance of the proposed system,using false negative rate,false alarm rate,and alarm response time as indicators,is compared with that of the system using Quuppa as a positioning *** experiment results show that both BLE pseudolite and Quuppa as a positioning source can basically meet the positioning accuracy for the infant monitoring system,but the BLE-pseudolite-based system provides a more cost-efficient solution.

关键词： Indoor positioning Bluetooth Low Energy(BLE) pseudolite infant monitoring

An optimal design of the broadcast ephemeris for LEO navigation augmentation systems

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Geo-Spatial Information Science 2022年第1期25卷 34-46页

作者： Xueli Guo Lei Wang Wenju Fu Yingbo Suo ruizhi chen Hongxing Sun State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina Collaborative Innovation Center for Geospatial Technology WuhanChina

As the deployment of large Low Earth Orbiters(LEO)communication constellations,navigation from the LEO satellites becomes an emerging opportunity to enhance the existing satellite navigation *** LEO navigation augmentation(LEO-NA)systems require a centimeter to decimeter accuracy broadcast ephemeris to support high accuracy positioning ***,how to design the broadcast ephemeris becomes the key issue for the LEO-NA *** this paper,the temporal variation characteristics of the LEO orbit elements were analyzed via a spectrum analysis.A non-singular element set for orbit fitting was introduced to overcome the potential singularity problem of the LEO *** on the orbit characteristics,a few new parameters were introduced into the classical 16 parameter ephemeris set to improve the LEO orbit fitting *** order to identify the optimal parameter set,different parameter sets were tested and compared and the 21 parameters data set was recommended to make an optimal balance between the orbit accuracy and the bandwidth *** the real-time broadcast ephemeris generation procedure,the performance of the LEO ephemeris based on the predicted orbit is also *** performance of the proposed ephemeris set was evaluated with four in-orbit LEO satellites and the results indicate the proposed 21 parameter schemes improve the fitting accuracy by 87.4%subject to the 16 parameters *** accuracy for the predicted LEO ephemeris is strongly dependent on the orbit *** these LEO satellites operating higher than 500 km,10 cm signal-in-space ranging error(SISRE)is achievable for over 20 min prediction.

关键词： LEO broadcast ephemeris orbit fitting leo navigation augmentation orbit prediction

Signal acquisition of Luojia-1A low earth orbit navigation augmentation system with software defined receiver

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Geo-Spatial Information Science 2022年第1期25卷 47-62页

作者： Liang chen Xiangchen Lu Nan Shen Lei Wang Yuan Zhuang Ye Su Deren Li ruizhi chen State Key Laboratory Of Information Engineering In Surveying Mapping And Remote SensingWuhan UniversityWuhanChina

Low Earth Orbit(LEO)satellite navigation signal can be used as an opportunity signal in the case of a Global Navigation Satellite System(GNSS)outage,or as an enhancement by means of traditional GNSS positioning *** matter which service mode is used,signal acquisition is a prerequisite for providing enhanced LEO navigation *** with the medium orbit satellite,the transit time of the LEO satellite is ***,it is of great significance to expand the successful acquisition time range of the LEO *** studies on LEO signal acquisition are based on simulation ***,signal acquisition research based on real data is *** this work,the signal characteristics of LEO satellites:power space density in free space and the Doppler shift of LEO satellites are individually *** unified symbolic definitions of several integration algorithms based on the parallel search signal acquisition algorithm are *** verify these algorithms for LEO signal acquisition,a Software Defined Receiver(SDR)is *** performance of these integration algorithms on expanding the successful acquisition time range is verified by the real data collected from the Luojia-1A *** experimental results show that the integration strategy can expand the successful acquisition time range,and it will not expand indefinitely with the integration *** performance of the coherent integration and differential integration algorithms is better than the other two integration algorithms,so the two algorithms are recommended for LEO signal acquisition and a 20 ms integration duration is *** detection threshold of 2.5 is not suitable for all integration algorithms and various integration durations,especially for the Maximum-to-Mean Ratio indicator.

关键词： Coherent integration differential coherent integration Low Earth Orbit(LEO) non-coherent integration navigation augmentation signal acquisition

LEO navigation augmentation constellation design with the multi-objective optimization approaches

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Chinese Journal of Aeronautics 2021年第4期34卷 265-278页

作者： Yi HAN Lei WANG Wenju FU Haitao ZHOU Tao LI Beizhen XU ruizhi chen State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430079China Collaborative Innovation Center for Geospatial Technology Wuhan 430079China

Low Earth Orbit(LEO)satellite for navigation augmentation applications can significantly reduce the precise positioning convergence time and attract increasing attention recently.A few LEO Navigation Augmentation(LEO-NA)constellations have been proposed,while corresponding constellation design methodologies have not been systematically *** LEO-NA constellation generally consists of a huge number of LEO satellites and it strives for multiple optimization *** is essentially different from the communication constellation or earth observing constellation design *** this study,we modeled the LEO-NA constellation design problem as a multi-objective optimization problem and solve this problem with the MultiObjective Particle Swarm Optimization(MOPSO)*** objectives are used to strive for the best tradeoff between the augmentation performance and deployment efficiency,namely the Position Dilution of Precision(PDOP),visible LEO satellites and the orbit altitude.A fuzzy set approach is used to select the final constellation from a set of Pareto optimal solutions given by the MOPSO *** evaluate the performance of the optimized constellation,we tested two constellations with 144 and 288 satellites and each constellation has three optimization schemes:the polar constellation,the single-layer constellation and the two-layer *** results indicate that the optimized two-layer constellation achieves the best global coverage and is followed by the single-layer *** MOPSO algorithm can help to improve the constellation design and is suitable for solving the LEO-NA constellation design problem.

关键词： LEO-augmented multi-GNSS LEO constellation design MOPSO Multi-objective optimization Orbit optimization

Improvement of Outdoor Microclimate Comfort of Rural Residence in Southwest Mountainous Area through Plant Application

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Journal of Landscape Research 2016年第4期8卷 39-41页

作者： chen ruizhi LI Min School of Architecture and Design Southwest Jiaotong University

Improvement of microclimate comfort is good to save energy,and create and improve communication space,and promote sustainable development of *** is an important factor that influences outdoor microclimate and plant is an economic,high-efficiency and healthy choice to improve wind *** article discussed technical strategies of improving the microclimate comfort of rural residence in southwest mountainous areas,by taking use of native *** strategy is to set up the wind-guide or wind-break plant landscape system through site planting,courtyard planting and residence planting.

关键词： Country settlements Microclimate comfort Plant