JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Lightweight jammer localization algorithm in wireless sensor networks

2013, 22(2): 143-148.

[Abstract](983) [PDF 376KB](1246)

Abstract:
In wireless sensor networks (WSNs), as the shared nature of the wireless medium, jamming attacks can be easily launched and result in a great damage to the network. How to deal with jamming attacks has become a great concern recently. Finding the location of a jammer is important to take security actions against the jammer, and thus to restore the network communication. After a comprehensive study on the jammer localization problem, a lightweight easy-operated algorithm called triple circles localization (TCL) is proposed. The evaluation results have demonstrated that, compared with other approaches, TCL achieves the best jammer localization accuracy under variable conditions.

Temperature field simulation technology for thermostat electromechanical systems

WANG Ya-bin, YUAN Shuai

2013, 22(2): 149-152.

[Abstract](609) [PDF 1376KB](560)

Abstract:
Temperature field control of electromechanical system with constant temperature is one of the important factors that affects the accuracy of the system. Traditional ways of temperature detection cost a lot but have low responding sensitivity. To solve this problem, temperature field simulation using numerical simulation was done toward the electromechanical system, and the platform temperature field distribution as well as the process of the platform reaching the steady-state was analyzed. The research shows that the system temperature observing parameters are all within normal range and the temperature control structure is rational. In all, the research achievements have some engineering and theoretical values in improving the design of temperature control device and system accuracy.

Weight distribution of sub-munitions fuze design

QIN Dong-ze, FAN Ning-jun

2013, 22(2): 153-157.

[Abstract](819) [PDF 478KB](1016)

Abstract:
In order to explore the unexploded ordnance problem of cluster munitions and find the solutions, an M85 sub-munitions reliability model was established by applying the Monte Carlo method. Simulation and experimental statistics matched the proportion of unexploded ordnance, so the hypothesis was feasible. The causes of failure and influencing factors of the dual-purpose improved conventional munitions M85 were analyzed according to experimental data. The sensitivity of each device in fuze was also analyzed. The sorting of weight of each device influence in M85 sub-munitions fuze was determined. Stabilization device with the maximum weight is the key components of sub-munitions fuze, so these results provide a reference to the analysis and redesign of other sub-munitions fuzes.

Numerical analysis on three dimensional temperature field of the gap between piston and cylinder

YUAN Shi-hua, WANG Zhi-hui, PENG Zeng-xiong

2013, 22(2): 158-162.

[Abstract](868) [PDF 388KB](808)

Abstract:
The three dimensional temperature field of the gap between piston and cylinder was obtained by numerically solving energy equation. The boundary condition of the equation was given in the form of heat transfer coefficient, instead of solving the temperature field of solid parts. The temperature field was calculated both under high speed high pressure condition and low speed low pressure condition. The numerical result was compared to experimental result under low speed low pressure condition and showed good agreement. It was shown that the influence of heat transfer coefficient on film temperature was significant. The adiabatic condition was reasonable under low speed low pressure condition, but invalid under high speed high pressure condition. It was a good way to describe the influence of solid parts on temperature using heat transfer coefficient but avoiding solving the temperature field of solids parts.

System modeling and dynamic analysis of ISG hybrid power shafting

ZHOU Jiu-yan, SUN Feng-chun, CHENG Xi-ming, WANG Zhi-fu

2013, 22(2): 163-170.

[Abstract](1190) [PDF 674KB](870)

Abstract:
A system model is established to analyze the dynamic performance of an integrated starter and generator (ISG) hybrid power shafting. The model couples the electromechanical coupling shaft dynamics, the bearing hydrodynamic lubrication and the engine block stiffness. The model is compared with the model based on ADAMS or the model neglecting the bearing hydrodynamics. The bearing eccentricity and the oil film pressure have been calculated under different hybrid conditions or at the different motor power levels. It’s found that the bearing hydrodynamics decreases the calculation results of the bearing peak load. Changes of the hybrid conditions or the motor power have no significant effect on the main bearing, but have impact on the motor bearing. A hybrid power system composed of a 1.6.L engine and a 45.kW ISG motor can operate safely.

Analysis of vehicle powertrain dynamic performance

LUO Guo-liang, ZHANG Fu-jun, YUAN Hao-jie

2013, 22(2): 171-178.

[Abstract](4961) [PDF 803KB](3853)

Abstract:
To study the vehicle dynamic characteristics under typical cycle conditions, a steady-state simulation model of the engine in GT-Power is established and verified with engine bench test data. A dynamic model of the engine is then established. A co-simulation with the engine dynamic model in GT-Power and the vehicle transmission model in AMESim is conducted based on the technology of HLA/RTI. The parameter changes of vehicle powertrain in the accelerating process of 0-32.km/h, and vehicle typical cycle conditions are studied. The influence laws of the typical parameters influencing vehicle dynamic characteristics are obtained, and a new approach of improving vehicle dynamic characteristics is proposed. The results show that the vehicle powertrain dynamic model can simulate, analyze and predict dynamic changes of vehicle in actual operating conditions and guide powertrain matching and optimization.

Self-adaptive correction of clutch control with proportional valve

PENG Jian-xin, LIU Hai-ou, CHEN Hui-yan

2013, 22(2): 179-184.

[Abstract](635) [PDF 362KB](982)

Abstract:
A new method for self-adaptive correction of the clutch proportional valve by Lyapunov stability function is proposed. Compared with displacement curve of hydraulic control cylinder under standard load, pulse width modulation (PWM) voltage imposed on clutch proportional valve is corrected according to the error to improve the consistency of the clutch control system in the process of clutch engagement. Computer simulations are conducted with this self-adaptive correction method by establishing the clutch control system model and results indicate that the principle of the method is correct. The flow rate variation obtains effective restraint which is caused by clutch control system characteristic of different vehicle under constant PWM voltage.

Roundness error evaluation by minimum zone circle via microscope inspection

JIANG Li, ZHANG Zhi-jing, WU Wei-ren, JIN Xin, JIE De-gang

2013, 22(2): 185-190.

[Abstract](3590) [PDF 353KB](3045)

Abstract:
Utilizing the convex hull theory, a novel minimum zone circle (MZC) method, named improved minimum zone circle (IMZC) was developed in this paper. There were three steps for IMZC to evaluate the roundness error. Firstly, with the convex hull algorithm, data points on the circle contour were categorized into two sets to determine two concentric circles which contained all points of the contour. Secondly, vertexes of the minimum circumscribed circle and the maximum inscribed circle were found out from the previously determined two sets, and then four tangent points for determining the two concentric circles were also found out. Lastly, according to the evaluation using the MZC method, the roundness error was figured out. In this paper, IMZC was used to evaluate roundness errors of some micro parts. The evaluation results showed that the measurement precision using the IMZC method was higher than the least squared circle (LSC) method for the same set of data points, and IMZC had the same accuracy as the traditional MZC but dramatically shortened computation time. The computation time of IMZC was 6.89% of the traditional MZC.

Precise conversion between virtual world and real world in stereoscopic imaging

YAO Xiao-yong, WU Ping-dong, HUANG Man-ling

2013, 22(2): 191-196.

[Abstract](863) [PDF 339KB](935)

Abstract:
A method for precise conversion between virtual world and real world is put forward in this paper. The method aims to precisely establish the connection between the virtual coordinates and the real coordinates with OpenGL. In the virtual world, two virtual cameras are set to capture the left and right perspective planar images, and coordinates of the planar images can be calculated by the perspective projection model. With coordinates of planar images, coordinates of the stereoscopic image synthesized in the real world can be calculated by the binocular observation model. Therefore, the corresponding connection between the two systems is established. Experimental results match data from this method well. Therefore, this method can precisely realize the conversion and the interactivity, laying a solid foundation for further study.

Strategy to control crawling vehicles with automated mechanical transmission

WANG Hong-liang, LIU Hai-ou, WANG Juan

2013, 22(2): 197-201.

[Abstract](834) [PDF 321KB](925)

Abstract:
In order to move vehicles with automated mechanical transmission (AMT) a little bit of distance, such as reversing into or moving in a garage, a control strategy for crawling vehicles was proposed. Based on the dynamic analysis of vehicle starting process and requirements of crawl driving for the vehicle,a control strategy of the clutch was designed. The strategy increased the slipping friction torque first and then decreased it, in order to realize the crawl driving. The speed increased by the engagement of the clutch, and then the clutch turned to disengage to the half disengage point, when the speed met the requirements. Based on the control strategy, a control software was designed. In the end, the software was tested on a vehicle with AMT. The lowest steady vehicle speed was reduced to 40% of the original value, which was set in the control strategy.

Control strategy for hybrid tracked vehicles using fuzzy logic

CHEN Ze-yu, ZHAO Guang-yao, ZHANG Cheng-ning, ZHAI Li

2013, 22(2): 202-206.

[Abstract](708) [PDF 344KB](886)

Abstract:
To solve the problem of power distribution for hybrid tracked vehicles (HTV), a supervisory control strategy is proposed. Firstly, power system integration is analyzed and modeled. Then the control algorithm is given. Two fuzzy logics are used to realize the coordination control over each power unit. One controls power distribution based on the load power and battery state of charge (SOC). The other manage the power during regenerating braking. To validate the presented control strategy, a "driver and controller" in the loop simulation platform is built based on dSPACE system and real-time simulation is made. The simulation results show that the strategy presented can solve the power distribution problem of hybrid tracked vehicles correctly and effectively.

Experimental study on durability fracture behavior and vibration modal sweep for vehicle rear axle

MEN Yu-zhuo, YU Hai-bo, HUO Na

2013, 22(2): 207-212.

[Abstract](4019) [PDF 688KB](2125)

Abstract:
In order to study the fatigue fracture behavior of the rear axle of certain China-made car, the strain loading spectrum near the rear axle fracture location is collected, the modified Neuber rule and the cyclic stress-strain hysteresis loop curve equation are used to convert the nominal strain history into the local stress-strain response. The impact of mean stress on fatigue damage is corrected according to the Manson-Coffin model, and programming calculation of the fatigue damage of the fracture crack is conducted in the INFIELD software, the electromagnetic vibrators are used to sweep the vibration modal frequencies of the rear axle and car body. The enhancement test and frequency sweep results show that the rear axle fatigue damage mainly concentrates on the washboard road, and when the forced vibration excitation frequency is 24.07.Hz, the vibration modal frequency of the rear axle is close to the excitation frequency of the washboard road, leading to resonance and making the rear axle subjected to large strain and fatigue damage, and then vibration fatigue fracture due to high stress concentration.

Robot stereo vision calibration method with genetic algorithm and particle swarm optimization

WANG Shou-kun, LI De-long, GUO Jun-jie, WANG Jun-zheng

2013, 22(2): 213-221.

[Abstract](786) [PDF 839KB](1317)

Abstract:
Accurate stereo vision calibration is a preliminary step towards high-precision visual positioning of robot. Combining with the characteristics of genetic algorithm (GA) and particle swarm optimization (PSO), a three-stage calibration method based on hybrid intelligent optimization is proposed for nonlinear camera models in this paper. The motivation is to improve the accuracy of the calibration process. In this approach, the stereo vision calibration is considered as an optimization problem that can be solved by the GA and PSO. The initial linear values can be obtained in the first stage. Then in the second stage, two cameras’ parameters are optimized separately. Finally, the integrated optimized calibration of two models is obtained in the third stage. Direct linear transformation (DLT), GA and PSO are individually used in three stages. It is shown that the results of every stage can correctly find near-optimal solution and it can be used to initialize the next stage. Simulation analysis and actual experimental results indicate that this calibration method works more accurate and robust in noisy environment compared with traditional calibration methods. The proposed method can fulfill the requirements of robot sophisticated visual operation.

Digital image stabilization system based on inertial measurement module

JIN Feng, LI Tian

2013, 22(2): 222-227.

[Abstract](1073) [PDF 802KB](1014)

Abstract:
In order to stabilize the video image sequence, a method of using inertial measurement module to build digital image stabilization system is proposed. Through applying real-time attitude information of the camera that obtained by high-precision attitude sensor to estimate the image motion vector and then to compensate for image, the purpose of stabilizing the image sequence can be achieved. Experiments demonstrate that this method has a high image stabilization precision, and the up to 16 frame/s video output rate completely meets the real-time requirements.

Trajectory synchronization of multi-cylinder electrohydraulic lift system with huge load

HE Yu-dong, WANG Jun-zheng, LI Jing, ZHAO Jiang-bo

2013, 22(2): 228-234.

[Abstract](813) [PDF 428KB](850)

Abstract:
A kind of four degree-of-freedom (DOF) electrohydraulic lift system is studied in this paper, after analyzing the motion characteristics and the mathematic model of the hydraulic cylinders, a cross-coupled synchronization method with load force and synchronization error feedback had been proposed to solve the synchronization problem encountered when realizing the needed roll and pitch attitude of the lift system. In this paper, mathematic model of asymmetric hydraulic cylinder was established and the lift system had been simplified to a dual-cylinder system. By incorporating the load force and the displacement of each cylinder, a cross-coupled synchronized control method was proposed to fit each cylinder’s tracking performance and multi-cylinder’s trajectory synchronization property. The proposed method not only solved the synchronization problem when multi-cylinder had a same trajectory, but also could fit the coordinated synchronization need when different trajectories of multi-cylinder were desired. Simulations and experiments on a four DOF electrohydraulic lift system with load of 100 tons verified the effectiveness of the proposed method.

Output neighboring-extremal and NCO tracking control in the optimal operation of CSTR

XU Xiang-yang, SHI Jin-feng, DAI Ya-ping

2013, 22(2): 235-240.

[Abstract](736) [PDF 341KB](694)

Abstract:
A new optimizing framework of process operation is proposed to deal with optimizing operation of continuous stirred tank reactor (CSTR). The optimization framework includes two layers: the first layer, necessary condition of optimally (NCO) tracking controller, calculates the optimal set-point of the process; and the second layer, output neighboring-extremal controller, calculates the input values of the controlled plant. The algorithm design and convergent analysis of output neighboring-extremal controller are discussed emphatically, and in the case of existing parametric uncertainty, the approach is shown to converge to the optimum atmost in two iterations. At last the approach is illustrated by simulation results for a dynamic CSTR.

DOA estimation of coexisted noncoherent and coherent signals via sparse representation of cleaned array covariance matrix

LIU Wei, XU You-gen, LIU Zhi-wen

2013, 22(2): 241-245.

[Abstract](1621) [PDF 321KB](878)

Abstract:
A new direction finding method is presented to deal with coexisted noncoherent and coherent signals without smoothing operation. First the direction-of-arrival (DOA) estimation task is herein reformulated as a sparse reconstruction problem of the cleaned array covariance matrix, which is processed to eliminate the affection of the noise. Then by using the block of matrices, the information of DOAs which we pursuit are implied in the sparse coefficient matrix. Finally, the sparse reconstruction problem is solved by the improved M-FOCUSS method, which is applied to the situation of block of matrices. This method outperforms its data domain counterpart in terms of noise suppression, and has a better performance in DOA estimation than the customary spatial smoothing technique. Simulation results verify the efficacy of the proposed method.

Multiple-impairment monitoring for optical duobinary system based on delay-tap asynchronous sampling

LAI Jun-sen, YANG Ai-ying, SUN Yu-nan

2013, 22(2): 246-249.

[Abstract](1805) [PDF 339KB](949)

Abstract:
A technique using artificial neural networks trained with parameters derived from delay tap plots for optical performance monitoring in 40.Gbit/s duobinary system is demonstrated. Firstly, the optical signal is delay tap sampled to obtain two-dimensional histogram, known as delay tap plots. Secondly, the features of delay tap plots are extracted to train the feed forward, three-layer preceptor structure artificial neural networks. Finally, the outputs of trained neural network are used to monitor optical duobinary signal impairments. Simulation of optical signal noise ratio (OSNR), chromatic dispersion (CD), and differential group delay (DGD) monitoring in 40.Gbit/s optical duobinary system is presented. The proposed monitoring scheme can accurately identify simultaneous impairments without requiring synchronous sampling or data clock recovery. The proposed technique is simple, cost-effective and suitable for in-service distributed OPM.

Optical micro-scanning location calibration of thermal microscope imaging system

GUAN Cong-rong, GAO Mei-jing, JIN Wei-qi, WANG Ji-hui

2013, 22(2): 250-255.

[Abstract](1258) [PDF 987KB](868)

Abstract:
A method of micro-scanning location adaptive calibration was proposed, which was realized by the digital image micro-displacement estimation. With geometric calculation, this calibration method used the displacement estimation of two thermal microscope images to get the size and direction of each scanning location calibration angle. And each location calibration process was repeated according to the offset given by the system beforehand. The comparison experiments of sequence oversampling reconstruction before and after the micro-scanning location calibration were done. The results showed that the calibration method effectively improved the thermal microscope imaging quality.

Fault tolerant control for a robot collaborative system

YAO Li-na, CAO Wei, WANG Ai-ping

2013, 22(2): 256-262.

[Abstract](734) [PDF 365KB](1084)

Abstract:
A new fault-tolerant control scheme is proposed for a nonlinear collaborative system that contains two robot subsystems. When fault occurs in one subsystem, the fault-free subsystem is used to compensate the fault influence of the faulty one on the whole collaborative system. When the faulty subsystem could not repair itself or the repair process needs a long time, the controller of the fault-free subsystem is reconfigured using the fault diagnosis information and other measured information, leading to the fault tolerant control of the robot collaborative system. Simulations of fault tolerant control for the robot collaborative system show the effectiveness of the proposed method.

Delay-dependent static output feedback control of nonlinear system

ZHANG Guo, ZHUANG Shu-jun

2013, 22(2): 263-270.

[Abstract](1003) [PDF 345KB](612)

Abstract:
The static output feedback control problem for time-delay nonlinear system is studied based on T-S fuzzy bilinear model. The objective is to design a delay-dependent static output feedback controller via the parallel distributed compensation (PDC) approach such that the closed-loop system is delay-dependent asymptotically stable. A sufficient condition for the existence of such a controller is derived via the linear matrix inequality (LMI) approach and the design problem of the fuzzy controller is formulated as an LMI problem. The simulation examples show the effectiveness of the proposed approach.

Self-diagnosis method for faulty modules on wireless sensor node

ZHAO Jun, CHEN Xiang-guang, LI Zhi-min, WU Lei

2013, 22(2): 271-277.

[Abstract](1612) [PDF 497KB](773)

Abstract:
In order to diagnose the working status of each module on sensor node and make sure the wireless sensor networks (WSN) work properly, the components of sensor node and their working characteristics are studied. An on-line fault self-diagnosis method for sensor node is proposed. First, a flexible fault sensing circuit is designed as a state detection module on sensor node. Second, a self-diagnosis algorithm is proposed based on the hardware design and the failure analysis on sensor node. Finally, in order to ensure the WSN reliability, the voltage changes of each module working statuses can be observed using the state detection module and the faulty module will be found out timely. The experimental results show that this self-diagnosis method is suitable to sensor nodes in WSN.

Fabrication and characterization of copper-diamond particles

NIAZI A R, LI Shu-kui, WANG Ying-chun, LIU Jin-xu, HU Zhi-yu, Usman

2013, 22(2): 278-284.

[Abstract](880) [PDF 2667KB](1020)

Abstract:
The electroless copper deposition on both pure and Cr-coated diamond particles was studied to produce copper/diamond composites for electronic packaging materials. The particles were characterized and the mechanism of product formation was investigated through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). The particle coating thickness was measured using optical micrographs. The diamond particles got uniform coating thickness of copper crystals layers. This method provided an excellent base for the fabrication of metal-based composites using cheap equipments, and was less time consuming, nature friendly and economical compared with other methods of diamond surface metallization.

2013 Vol. 22, No. 2