检索结果-内蒙古大学图书馆

Cycle-slip Detection of GPS Carrier Phase with Methodology of SA4 Multi-wavelet Transform

Chinese Journal of Aeronautics 2012年第2期25卷 227-235页

作者： HUO Guoping MIAO Lingjuan School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Intelligent Control and Decision of Complex Systems Beijing 100081 China

That cycle-slips remain undetected will significantly degrade the accuracy of the navigation solution when using carrier phase measurements in global positioning system （GPS）. In this paper, an algorithm based on length-4 symmetric/anti-symmetric （SA4） orthogonal multi-wavelet is presented to detect and identify cycle-slips in the context of the feature of the GPS zero-differential carrier phase measurements. Associated with the local singularity detection principle, cycle-slips can be detected and located precisely through the modulus maxima of the coefficients achieved by the multi-wavelet transform. Firstly, studies are focused on the feasibility of the algorithm employing the orthogonal multi-wavelet system such as Geronimo-Hardin-Massopust （GHM）, Chui-Lian （CL） and SA4. Moreover, the mathematical characterization of singularities with Lipschitz exponents is explained, the modulus maxima from wavelet to multi-wavelet domain is extended and a localization formula is provided from the modulus maxima of the coefficients to the original observation. Finally, field experiments with real receiver are presented to demonstrate the effectiveness of the proposed algorithm. Because SA4 possesses the specific nature of good multi-filter properties （GMPs）, it is superior to scalar wavelet and other orthogonal multi-wavelet candidates distinctly, and for the half-cycle slip, it also remains better detection, location ability and the equal complexity of wavelet transform.

关键词： satellite navigation cycle-slip detection orthogonal multi-wavelet good multi-filter properties singularity detection

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Disturbance observer based time-varying sliding mode control for uncertain mechanical system

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Journal of systems Engineering and Electronics 2012年第1期23卷 108-118页

作者： Binglong Cong Xiangdong Liu Zhen Chen School of Automation Beijing Institute of Technology Beijing 100081 P. R. China Key Laboratory for Intelligent Control ＆ Decision on Complex Systems Beijing Institute of Technology Beijing 100081 P. R. China

It is now well known that the time-varying sliding mode control （TVSMC） is characterized by its global robustness against matched model uncertainties and disturbances. The accurate tracking problem of the mechanical system in the presence of the parametric uncertainty and external disturbance is addressed in the TVSMC framework. Firstly, an exponential TVSMC algorithm is designed and the main features are analyzed. Especially, the control parameter is obtained by solving an optimal problem. Subsequently, the global chattering problem in TVSMC is considered. To reduce the static error resulting from the continuous TVSMC algorithm, a disturbance observer based time-varying sliding mode control （DOTVSMC） algorithm is presented. The detailed design principle and the stability of the closed-loop system under the composite controller are provided. Simulation results verify the effectiveness of the proposed algorithm.

关键词： mechanical system time-varying sliding mode control （TVSMC） global sliding phase global chattering disturbance observer.

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Graph-based background suppression for scene text detection

Graph-based background suppression for scene text detection

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10th IAPR International Workshop on Document Analysis systems, DAS 2012

作者： Shi, Cunzhao Xiao, Baihua Wang, Chunheng Zhang, Yang State Key Laboratory of Intelligent Control and Management of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China

ISBN: (纸本)9780769546612

Detecting text in video or natural scene image is quite challenging due to the complex background, various fonts and illumination conditions. The preprocessing period, which suppresses the nontext areas so as to highlight the text areas, is the basis for further text detection. In this paper, a novel graph-based background suppression method for scene text detection is proposed. Considering each pixel as a node in the graph, our approach incorporates pixel-level and context-level features into a graph. Various factors contribute to the unary and pair wise cost function which is optimized via max-flow/min-cut algorithm [16] to get a binary image whose nontext pixels are suppressed so that text pixels are highlighted. Furthermore, the proposed background suppression method could be easily combined with other detection methods to improve the performance. Experimental results on ICDAR 2011 competition dataset show promising performance. © 2012 IEEE.

关键词： Edge detection

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A hierarchical networked urban traffic signal control system based on multi-agent

A hierarchical networked urban traffic signal control system...

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2012 9th IEEE International Conference on Networking, Sensing and control, ICNSC 2012

作者： Chen, Cheng Li, Zheng Jiang State Key Laboratory of Intelligent Control and Management of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781467303880

In this paper, we proposed an architecture of a hierarchical networked urban traffic signal control system Based on Multi-agent. With mobile agent technology, traffic control strategies are designed as traffic control agents, which can move from device to device in a network. The system can reconfigure and replace these agents according to inconstant states of traffic environment and performances of agents. By this way, demand-based control is realized in traffic signal control system. Then we described the details and key technologies in the procession of agent-generation, agent-storage and agent-usage. At last, a prototype of the system is developed and basic functions of this system are tested by simulations. These simulations also confirm extensibility and effectiveness of the system. © 2012 IEEE.

关键词： Hierarchical systems

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Adaptive graph cut based binarization of video text images

Adaptive graph cut based binarization of video text images

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10th IAPR International Workshop on Document Analysis systems, DAS 2012

ISBN: (纸本)9780769546612

Interactive image segmentation which needs the user to give certain hard constraints has shown promising performance for object segmentation. In this paper, we consider characters in text image as a special kind of object, and propose an adaptive graph cut based text binarization method to segment text from background. The main contributions of the paper lie in: 1) in order to make the binarization local adaptive with uneven background, the text region image is firstly roughly split into several sub-images on which graph cut is applied, and 2) considering the unique characteristics of the text, we propose to automatically classify some pixels as text or background with high confidence, severed as hard constraints seeds for graph cut to extract text from background by spreading the seeds into the whole sub-image. The experimental results show that our approach could get better performance in both character extraction accuracy and recognition accuracy. © 2012 IEEE.

关键词： Image segmentation

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Backstepping based adaptive sliding mode control for spacecraft attitude maneuvers

Backstepping based adaptive sliding mode control for spacecr...

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2012 UKACC International Conference on control, control 2012

作者： Cong, Binglong Liu, Xiangdong Chen, Zhen Key Laboratory for Intelligent Control and Decision of Complex Systems School of Automation Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9781467315609

This paper aims to address the robust control problem of rigid spacecraft attitude maneuvers in the presence of inertia matrix uncertainty and external disturbance. A back-stepping based adaptive sliding mode control (B-ASMC) design is proposed as a solution, where the upper bounds of the parametric uncertainty and disturbance are not required in advance. Compared to current adaptive sliding mode control (ASMC) design, the B-ASMC design has two advantages. Theoretically, the asymptotical stability of the attitude states rather than the sliding function is guaranteed. Practically, the over-adaptation problem in current ASMC design is alleviated and the system performance is improved. Detailed design principle and rigorous closed-loop system stability analysis are provided. A large angle attitude maneuver is employed in the numerical simulation to verify the effectiveness of the proposed algorithm. © 2012 IEEE.

关键词： Backstepping

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Adaptive sliding mode control for spacecraft attitude maneuvers with reduced or eliminated reaching phase

Adaptive sliding mode control for spacecraft attitude maneuv...

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2012 UKACC International Conference on control, control 2012

作者： Cong, Binglong Liu, Xiangdong Chen, Zhen Key Laboratory for Intelligent Control and Decision of Complex Systems School of Automation Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9781467315609

This paper aims to present an improved adaptive sliding mode control (ASMC) design for rigid spacecraft attitude maneuvers. An adaptive scheme is proposed for the switching gain calculation when the upper bound of the system uncertainty is unknown in advance. Unlike existing ASMC design, which may result in an over-adaptation of the upper bound when the initial system trajectory is located far from the sliding surface, this paper presents a novel ASMC strategy by introducing a decay term in the sliding function to reduce or eliminate the unrelated factor in the adaptation scheme. Consequently, a lower-chattering control signal is achieved. Simulation results are presented to illustrate the effectiveness of the proposed strategy. © 2012 IEEE.

关键词： Sliding mode control

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Rotation Estimation for Mobile Robot Based on Single-axis Gyroscope and Monocular Camera

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International Journal of automation and computing 2012年第3期9卷 292-298页

作者： Yang, Ke-Hu Yu, Wen-Sheng Ji, Xiao-Qiang School of Mechanical Electronic and Information Engineering China University of Mining and Technology Beijing 100083 China Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai 200062 China State Key Laboratory of Intelligent Control and Management of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing 100190 China

The rotation matrix estimation problem is a keypoint for mobile robot localization, navigation, and control. Based on the quaternion theory and the epipolar geometry, an extended Kalman filter (EKF) algorithm is proposed to estimate the rotation matrix by using a single-axis gyroscope and the image points correspondence from a monocular camera. The experimental results show that the precision of mobile robot s yaw angle estimated by the proposed EKF algorithm is much better than the results given by the image-only and gyroscope-only method, which demonstrates that our method is a preferable way to estimate the rotation for the autonomous mobile robot applications.

关键词： Rotation matrix estimation quaternion extended Kalman filter (EKF) monocular camera gyroscope.

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Correction to "Attitude coordination control for a group of spacecraft without velocity measurements" [Sep 12 1146-1159]

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IEEE Transactions on control systems Technology 2013年第3期21卷 1044-1044页

作者： An-Min Zou Krishna Dev Kumar Zeng-Guang Hou Department of Aerospace Engineering Ryerson University Toronto ON Canada Institute of Automation Chinese Academy of Sciences State Key Laboratory of Intelligent Control and Management of Complex Systems Beijing China

Some errors in the above titled paper (ibid., vol. 20, no. 5, Sep. 2012, pp. 1146-1159) are corrected here.

关键词： Attitude control Space vehicles Observers Neural networks Adaptive control Aerospace engineering

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Fitting a functional structural plant model based on global sensitivity analysis

Fitting a functional structural plant model based on global ...

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2012 IEEE International Conference on automation Science and Engineering: Green automation Toward a Sustainable Society, CASE 2012

作者： Lin, Yubin Kang, Mengzhen Hua, Jing National Key Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Management and Control for Complex Systems Beijing Engineering Research Center of Intelligent Systems and Technology Chinese Academy of Sciences Beijing 100190 China

ISBN: (纸本)9781467304283

Calibration of a functional structural plant model is a challenging task because of the complexity of model structure. Parameter estimation through gradient-based optimization technique was highly dependent on initial parameter values. This motivated the use of global sensitivity analysis technique to choose parameter subset in fitting the data sequence. Global sensitivity indices were computed using the source sink ratio as the output of interest, which regulates all organ growth. By fitting on chrysanthemum data from nine sampling dates, it is shown that sensitivity analysis method helps to identify the influential parameters for a given sampling date. As a result, fitting process is less dependent on the initial parameter values. Current work provides a new method of calibrating a plant growth model with multiple outputs. © 2012 IEEE.

关键词： Sensitivity analysis

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