Time filter

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Xiao Q.,Beihang University | Wu Y.,Army Aviation Research Institute | Fu H.,Beihang University | Zhang Y.,Beihang University
IET Signal Processing | Year: 2015

This paper proposed a two-stage robust extended Kalman filter (TREKF) for state estimation of non-linear uncertain system with unknown inputs. In engineering practice, the extended Kalman filter (EKF) with unknown inputs of the non-linear uncertain system may be degraded or even diverged. The optimal two-stage EKF (TEKF) is designed to solve the unknown inputs. The robust EKF (REKF) is considered to solve the non-linear uncertain system for a long time. However, the information about the non-linear uncertain system with unknown inputs is always incorrect. To solve this problem, the TREKF is designed by using the advantages of the TEKF and REKF, furthermore, its stability is proved. Finally, the performances of the TREKF, which are compared with the results of the REKF, TEKF and EKF, are verified by illustrating a numerical example of the powered descent phase of Mars EDL (entry, descent and landing). These also verify that the unfavourable effects of the model uncertainties and the unknown inputs are reduced efficiently by using the TREKF for the miniature coherent altimeter and velocimeter and inertial measurement unit integrated navigation during the powered descent phase of Mars EDL. © The Institution of Engineering and Technology 2015.

Fu H.,Beihang University | Yang Y.,Beihang University | Xiao Q.,Beihang University | Wu Y.,Army Aviation Research Institute | Zhang Y.,Beihang University
Advances in Space Research | Year: 2015

Accurate navigation systems are required for future pinpoint Mars landing missions. A radio ranging augmented inertial measurement unit (IMU) navigation system concept is considered for the guided atmospheric entry phase. The systematic errors associated to the radio ranging and inertial measurements, and the atmospheric mission uncertainties are considered to be unknown. This paper presents the extension of an unbiased minimum-variance (EUMV) filter of a radio beacon/IMU navigation system. In the presence of unknown dynamics inputs, the filter joins the system state and the unknown systematic error estimation of a stochastic nonlinear time-varying discrete system. 3-DOF simulation results show that the performances of the proposed navigation filter algorithm, 100 m estimated altitude error and 8 m/s estimated velocity error, fulfills the need of future pinpoint Mars landing missions. © 2014 COSPAR. Published by Elsevier Ltd. All rights reserved.

Yang H.-Y.,Tsinghua University | You Z.,Tsinghua University | Wang L.,Army Aviation Research Institute
Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science) | Year: 2012

In the accurate tracking of multiple targets in clutter by using a collaborative network system with hierarchical and distributed information processing structure, both the measurement uncertainty and the sensor assignment to the target as well as the local fusion centers must be taken into consideration. In order to solve these problems, a dynamic sensor management method for distributed tracking is proposed. In this method, first, the criteria to evaluate the tracking performance are determined based on the solution to the modified Riccati difference equation, with which the objective function of the dynamic sensor management is constructed. Then, according to a hierarchical optimization strategy and by using the improved ant colony algorithm, an approximate optimal solution is obtained in real time. Finally, the optimal multi-target tracking trajectories are obtained by using a distributed fusion algorithm. Simulated results indicate that, as compared with the two dynamic sensor management methods, namely NN-Clustering and MV-Clustering, the proposed method is of higher multi-target tracking accuracy and higher utilization rate of network resource.

Zheng Z.-G.,Army Aviation Research Institute | Hu Y.-A.,Yantai Naval Aeronautical and Astronautical University | Wu L.,Military Representative Office of Navy in Hefei
Binggong Xuebao/Acta Armamentarii | Year: 2014

The present system multiple fault diagnosis is generally realized by generating a test sequence with minimal average test cost under fixed initial fault ambiguous groups, and then the faults are isolated through the fault diagnosis tree constructed according to the generated test sequence, so the test sequence and fault diagnosis tree are relatively fixed. When the initial faults ambiguous groups change, the test strategy still keep unchanging. To resolve the problem, an on-line strategy for multiple fault diagnosis is proposed, the iterative formulas to calculate the possibility of ambiguity groups are deduced, and the optimal test is selected by evaluation function based on fault isolation degree and information entropy of unit cost. The faulty unit with highest posterior possibility to be repaired is searched by set covering algorithm. Test case shows that the on-line strategy can isolate multiple faults by flexibly utilizing known information. It has the advantages of simple calculation and small storage space, and is feasible for multiple fault diagnosis of complex system.

Chen W.,Academy of Armored force Engineering | Ma D.-J.,Academy of Armored force Engineering | Guo J.-H.,Army Aviation Research Institute | Song Z.-K.,Academy of Armored force Engineering | Wang J.-L.,Academy of Armored force Engineering
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2015

The ratio of the center-to-border distance of Berkovich indentation impression to the nominal center-to-border distance was introduced as an independent instrumented indentation response parameter to describe the extent of pile-up/sink-in around Berkovich indentation impression. Based on the dimensional analysis and finite element simulations, the explicitly dimensionless relationships among three independent instrumented indentation response parameters (the other two parameters extracted from load-depth curve are nominal hardness and the ratio of elastic work to total work) and elastic-plastic properties of metals were established. Further more, a new method based on Berkovich indentation impression was proposed for determining elastic modulus E, strain hardening exponent n, conditional yield strength σ0.2, ultimate strength σb of metals. Finally, the effectiveness of the method was verified by the determination results of four kinds of structural metal. ©, 2015, Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals. All right reserved.

Shen J.,Army Aviation Research Institute | Zhang Y.-H.,Academy of Armored force Engineering
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2013

For the need of dependability evaluation, we give full consideration to the characteristics of reliability and maintainability. Through D-S evidence theory and fuzzy comprehension assessment, we arrival at a conclusion of unreliability based on the state monitoring and forecasting. We combine with unreliability and the related maintenance data to achieve the evaluation of dependability of unit. Finally, the applicability of the method was validated by an example.

Wang W.-G.,Beijing Institute of Technology | Wang W.-G.,Ordnance Engineering College | Sun L.,Army Aviation Research Institute
Binggong Xuebao/Acta Armamentarii | Year: 2014

For gearbox fault feature extraction, a novel method based on ensemble empirical mode decomposition and Choi-Williams distribution for gearbox vibration signal extraction is proposed. Firstly, vibration data are decomposed into several intrinsic mode functions (IMF) with EEMD, and IMFs are sorted by kurtosis criterion, then CWD is applied to the selected IMF which kurtosis is larger than others, the Choi-Williams distribution features in time, frequency and amplitude domains of the original signal can be extracted. On the basis of discussing teeth break and crack vibration fault mechanism of gearbox, the proposed method is used to analyze the vibration signal of the actual fault gearbox. The result shows that this method can efficiently extract the fault information and have great importance for condition recognition and fault diagnosis of gearbox.

Liu L.-S.,Nanjing University of Science and Technology | Yang Y.-H.,Army Aviation Research Institute | Li Z.-Y.,Army Aviation Research Institute | Yu W.,Army Aviation Research Institute
ICQR2MSE 2011 - Proceedings of 2011 International Conference on Quality, Reliability, Risk, Maintenance, and Safety Engineering | Year: 2011

This paper describes a conditon monitoring systems for helicopter main gearbox using wavelet packet transform (WPT) and wavelet neural network (WNN). According to the fault characteristics of main gearbox, a fault diagnosis method that combining WPT and WNN with threshold is proposed. First the noise is removed from vibration signals, then the denoising signals are decomposed by WPT, extract standard deviation coefficients of each level as the input of WNN, the learning rates and momentum factors are used to adjust the network, the method of batch training is applied and it can diagnose fault quickly, which can monitor the condition of main gearbox. Theoretical and practical application shows that this method is effective and feasible, its diagnostic speed is rapid and result is accuracy, which provides a new technical reference for the development of helicopter fault diagnostic systems. © 2011 IEEE.

Liu Y.,National University of Defense Technology | Liu J.,National University of Defense Technology | Bai X.-Z.,Army Aviation Research Institute
Guofang Keji Daxue Xuebao/Journal of National University of Defense Technology | Year: 2011

A new uncoupled algorithm of simulating chemical non-equilibrium flow originally realized by finite difference method was extended to the unstructured finite volume method, which makes the simulation of reaction flow in complex configurations possible. The H 2/Air shock-induced oscillating combustion experiment conducted by Lehr was simulated, and the computed oscillating frequencies conformed well with the ones acquired by experiment, which indicates that the present method is temporally and spatially second order accurate. It is also demonstrated that geometrical configuration plays a definitive role in the combustion regime. If the truncated angle is less or equal to 15 degrees, high frequency oscillating combustion in regular regime occurs, while if the angle is larger or equal to 20 degrees, low frequency oscillating combustion in large-disturbance regime is observed.

Zheng Z.,Army Aviation Research Institute | Wu L.,Yantai University
Proceedings of the 2012 International Conference on Computer Application and System Modeling, ICCASM 2012 | Year: 2012

A method of optimal test frequency selection for analog circuit fault diagnosis is proposed. The method simulates the circuit faulty states only in the bands with highest fault sensitivity and that reduces part of simulation cost. Test frequency selection is considered as a multi-objective optimization problem, discrete particle swarm algorithm is used as a new approach to get optimal test frequency sets. An example shows that the proposed method is effective in frequency selection and works more efficiently compared with genetic algorithm. © the authors.

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