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2007 Vol. 33, No. 11

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Multivariable robust lateral-directional control design for W-shaped tailless aircraft
Xiao Hua, Wang Lixin
2007, 33(11): 1257-1260.
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With the W-shaped tailless aircraft which is based on forward-swept wing configuration and the integrated design of blended wing-fuselage took as a control object, by the linear quadratic Gaussian with loop transfer recovery (LQG/LTR) method of multivariable robust control, the aircraft′s lateral-directional control system was designed. The inherent instability of this special configuration, the problem of control system′s instability and lack of control accuracy which may be caused by the aircraft motion model′s uncertainty and random disturbance were solved. The simulation results show that the lateral-directional command can be followed accurately, and the control system not only has good robustness, but also has good regulating process, which satisfy the lateral-directional control design requests of the W-shaped tailless aircraft.
New coning error compensation algorithm of strapdown inertial navigation system
Ding Yangbin, Man Shunqiang, Shen Gongxun
2007, 33(11): 1261-1263.
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Increasing the number of sample can improve the accuracy of error compensation while the rotation vector applied in strapdown inertial navigation system coning error compensation, however, limited with the performance of navigation computer, it is impossible to increase the number of sample sharply to gain high compensation accuracy. A new algorithm to improve the error compensation accuracy without adding more navigation computer cost was presented. By using the precurrent and pre-precurrent attitude information of strapdown inertial navigation system to modify the rotation vector, the new algorithm can gain more four order accuracy than the traditional one after analyzed theoretically and proven by an example. And the new algorithm does not cost more navigation computer resource additionally.
Fuzzy control of landing gear based on MR damper
Jia Yuhong, Wu Xiaojuan
2007, 33(11): 1264-1267.
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Basing on rheological dynamics and the real condition of landing gear, the forces that pressed on the landing gear had been simplified and MR (Magneto-rheological or Magnetically Responsive) damper model was applied on landing gear. Annular gap structure was applied on the damper, so the damp force could be easily controlled without changing the area of the gap. As a result, MR damper had many advantages, such as simple structure, small size and easy control. The landing gear system model with fuzzy controller was built and analyzed. Fuzzy controlling method had been chosen and used on the system, and the force influenced by magnetic field strength could be controlled by controlling current. Simulation results show that the energy during landing could be absorbed and consumed quickly by fuzzy control, at the same time, the predominance of applying of the MR damper on landing gear has been showed.
Space debris lifetime algorithm from spacecraft breakup events
Wang Ting, Dong Yunfeng, Han Chao
2007, 33(11): 1268-1272.
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A method to calculate lifetime of debris generated from spacecraft breakup events was presented. Based on NASA standard spacecraft breakup model, a spacecraft breakup algorithm was given, which yields a set of parameters of produced fragments that can serve as input for lifetime calculation. Current space debris lifetime algorithms were summarized and a semi-analytical algorithm was developed. By means of mean element method, rate of change of semimajor axis and eccentricity of fragment were calculated, in which J2 short-period variation was considered. Differentiation-integration method was applied to propagate the semimajor axis and eccentricity forward into time. Besides, calculation step of the algorithm was constrained to cooperate with time-varying atmosphere model. The computational speed and accuracy of the lifetime algorithm was analyzed through comparisons with a numerical orbital propagator. In order to find a suitable atmosphere model for lifetime calculation, three typical atmosphere models: SA76, GOST and MSIS-00 were compared. Finally, P-78 satellite breakup event was applied to test the whole algorithm.
Thermal radiation effects in the Lamilloy interior cooling passage
Tao Zhi, Lü Dong, Ding Shuiting, Cai Yi
2007, 33(11): 1273-1276.
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The heat transfer process of the Lamilly was analyzed, and the formulas for describing the thermal radiation inside the Lamilloy were provided under the suppose of configuration simplifying, for example, the complex surface cutting off and the infinity plate supposition. The thermal radiation and convection heat transfer in interior cooling passage of the Lamilloy with a typical configuration was studied by the method of three dimensional fluid-solid coupled computation. The ratio of thermal radiative to convective heat flux θ was introduced and it was a function of the cooling air inlet Re number and the gas heating power. Analysis was carried out under 4 typical aero-engine working conditions, and correction was performed with exponential fit. A simple method was put forth to evaluate the effect of thermal radiation, and with this method, the importance of thermal radiation could be easily assessed.
Novel inertial stellar compass based on gyroscope-free micro inertial measurement unit
Qin Jie, Fang Jiancheng, Sheng Wei
2007, 33(11): 1277-1280.
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Micro/nano spacecrafts need an attitude determination system performance in high accuracy, compact size, small mass and low power consumption. A novel inertial stellar compass (ISC) was designed to meet these requirements, which based on the gyroscope-free micro inertial measurement unit (GFMIMU) and integrated a star camera. The theory about how GFMIMU works to measure attitude angle was established. The state equation for ISC was modeled based on such theory, and the estimation equation was built up using measure information of the star camera. A Kalman filter approach was constructed to compensate the GFMIMU error in long-term working conditions, and the stability of the filter was proved using the observability analysis theory. A simulation of ISC was introduced finally, and the simulation results verify the proposed ISC can be used in micro/nano spacecrafts.
Numerical analysis on the flow and heat transfer in a rectangular passage with sub-scale fins
Xu Guoqiang, Wang Meng, Tao Zhi, Wu Hong
2007, 33(11): 1281-1285.
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Numeration analysis was made to simulate the flow and heat transfer in a rectangular passage with different configuration of sub-scale fins,the velocity fields, temperature fields and the average Nu were obtained, the enhancements of heat transfer were compared. The calculated results show that: the lower the sub-scale fin fixed on the main fin, the more heat emanated from the hot surface transfers to the fluid; in the region far from the hot surface, the higher specific surface area of the sub-scale fins, the better enhancement of heat transfer, with the same patulous area, the bigger fin length-to-width ratio, the better effect of heat transfer; numerical simulation result and analysis reveals the universal principle that the generalized temperature gradient uniformity principle, which can controls the best configuration of sub-scale fin. The better configuration of sub-scale fin which can enhance heat transfer has been conformed. Analyze shows that generalized temperature gradient uniformity principle can control the enhancement of heat transfer in the convective heat transfer process.
Triplex-redundancy control system for direct-drive-valve
Guo Hong, Yu Yongqiang, Xing Wei
2007, 33(11): 1286-1290.
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The design and implementation of a triplex-redundancy control system for direct-drive-valve (DDV) were presented. The total structure of the system was built up. The schemes of triplex-redundancy brushless DC motor, transducer and cross channel data link (CCDL) were analyzed. Meanwhile, the strategies of servo control based on variable-structure PID and redundancy management based on CCDL were researched. Experiment results suggest that the proposed system possesses well steady and dynamic performance, and maintains good operation characteristics after first or second electrical failure. Main characteristics of the system are that the range of angle is from -10° to 10°, the precision is less than 4′, and the bandwidth is up to 20Hz for dual redundancy and 15Hz for single redundancy. The system satisfies the DDV actuator of airplane.
Errors of antenna factor and improved method for NSA test
Su Donglin, Dai Fei, Xie Shuguo, Gao Wanfeng
2007, 33(11): 1291-1294.
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The normalized site attenuation (NSA) was studied during the test process. The measurement errors were mainly brought by the antenna factor, with the mutual impedance analysis. The standard method of measuring antenna factors was introduced and the mutual impedance effect was found to be neglected. The equations of traditional method were proved to be no solution. The conditions were analyzed to decrease the errors of the mutual impedance between antennas. The antenna factor was replaced by the antenna gain, and the mutual impedance effect can be avoided in the antenna gain measurement. The equivalent conditions were proved between the new method and the original method. The validity of the new method was proved by the real test results.
Artificial-neural-network adaptive control of compound actuator
Wen Zhaodong, Wang Zhanlin, Qi Xiaoye, Bao Lina
2007, 33(11): 1295-1298.
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To solve time-varying and nonlinear problem of the compound actuator ,the neural-network adaptive control principle was proposed. Establish the dynamic model of compound actuator using nonlinear auto-regressive moving average model, multi-layer perception neural network was used to identify the nonlinear model. The controller was based on the theory of generalized inverse and the network weights were deduced with respect to the error between the object and the identified model. The self-turning control was realized in combination with control-algorithm modify online. The simulation results show that this control scheme has good effect on the control of compound actuator under the model having time-varying and nonlinear character.
Algorithm of constructing reduced-order H∞ controller for nonsingular plants in explicit form
Zhong Ruilin, Cheng Peng
2007, 33(11): 1299-1302.
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Algorithms of constructing reduced-order H∞ controllers in explicit form are only applied to singular H∞ control case. In order to apply these algorithms to nonsingular case, the matrix A of a generalized plant was divided into two parts A 0 and Δ A , then ( A 0, B 2, C 1, D 12) or ( A 0, B 1, C 2, D 21) had unstable invariant zeros. Those algorithms could be used to the changed system to get a solution ( X , Y ) that could be used to construct a reduced-order controller. Since one of three linear matrix inequalities of the initial generalized plant was changed by the change of the system matrix A , the solution ( X , Y ) must be used in the linear matrix inequality that was changed with the variation of A for the initial generalized plant to see whether it could still hold or not. If it was holden, the solution ( X , Y ) could be used to construct a reduced-order controller for the initial generalized plant. Effectiveness of the algorithm was shown by numerical examples.
Design of control systems for missiles based on dynamic inversion and decentralized control
Zeng Xianfa, Zhang Lei, Shen Gongzhang
2007, 33(11): 1303-1307.
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Based on the nonlinear six degree-of-freedom missile model, the missile system was separated into four loops according to time-scale separation principle. Taking account of the fast loop and the relatively slow loop, the dynamic inversion controllers were designed in both of the two loops for decoupling control, and the robust decentralized controller was designed in the relatively slow loop to compensate the uncertainty and disturbances of the whole system. The robust decentralized controller has a simple structure and does not rely on the accurate mathematical model. Finally, the simulation results show that the closed-loop control system which is designed according to the approach achieves both good steady performance and dynamic performance, and its robust performance is also excellent.
Multiple access protocol with QoS support for mobile Ad Hoc networks
Wang Dapeng, Liu Kai
2007, 33(11): 1308-1312.
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Based on the concept of random contention and collision resolution, a QoS-based multiple access (QMA) protocol for Ad Hoc networks was proposed to support multimedia service and multi-hop architecture. The traffic was divided into two groups with different requirements on delay, namely real-time traffic and data (or non real-time) traffic. According to the protocol, nodes contend to access channel, and the node broadcasting the most forecast bursts (FBs) get right to access the channel according to its packet delay and the earliest deadline first (EDF) principle. Meanwhile, the nodes with real-time traffic have higher priority to access channel than those with data traffic by broadcasting FBs in earlier contention slots. Through simulations in OPNET modeler, it is shown that the QMA protocol outperforms the carrier sensing multiple access with collision avoidance (CSMA/CA) protocol in terms of throughput, message discard rate and average packet delay, and the QMA protocol can provide differentiated QoS guarantees for traffic in multi-hop networks.
Vision-based runway obstacle detection scheme for unmanned combat aerial vehicles
Chen Lei, Chen Zongji
2007, 33(11): 1313-1316.
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A computer-vision-based runway obstacle detection scheme for an unmanned combat air vehicle (UCAV) was presented. The scheme combined the advantages of the feature-based and the flow-based obstacle detection algorithms. Instead of using gradient-based method, a multi-scale optical flow estimation method based on feature point matching was adopted, which make it possible to calculate sparse optical flow field directly from image sequences. Under some relative hypothesis, obstacle on the runway could be detected even with certain navigation errors. The detection sensitivity and the stage applicable for obstacle detection were also discussed. The obstacle detection scheme can run properly on the real-time simulation system for autonomous landing of the UCAV.
Novel model of active vibration isolation based on giant magnetostrictive actuator
Zhang Xuhui, Liu Yongguang, Fu Yongling
2007, 33(11): 1317-1320.
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Through analyzing the constitutive relation of the giant magnetostrictive material, the main controllable factor constituting the output displacement for giant magntostrictive actuator was discussed. Upon which to investigate the key factors of single layer and one degree of freedom isolation platform based on giant magntostrictive actuator, a model with the displacement responding to acting force of the platform as its reference input was presented. Through analyzing the vibration isolation principle with the model, the conclusion was drawn that both acting force frequency and the maximum displacement of actuator are crucial to the effect of the system, in that the system vibration isolation capacity is direct ratio to the square of acting force frequency and maximum displacement of actuator. In time-domain, simulations based on Matlab platform with adaptive LMS (least mean square) algorithm were carried out to verify the conclusion. Thus it is theoretically instructive to design a vibration isolation system with giant magnetostrictive actuator, and the model is suitable to the system with giant magnetostrictive actuators as well to the system with other kinds of actuators.
Application of improved BP algorithm in fuzzy neural networks
Fang Zhenyong, You Wenhu, Feng Rupeng
2007, 33(11): 1321-1324.
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Improved BP algorithm——momentum factor-adapted learning rate algorithm was cited. Based on BP algorithm, the adaptability was realized by momentum factor adjust and the learning rate to improve the learning speed and stabilization. By useing the algorithm in multilayer forward fuzzy neural networks of serial structure, the fuzzy mapping relation and the fuzzy malfunction diagnosis of the object were obtained. When the fuzzy neural network was used in malfunction diagnosis, the inspected malfunction sign connected with the import layer of networks to put the import vector into network. Then the fuzzy subjection limit vectors of the defined sign which belongs to the malfunction sign by dealing with fuzzy were achieved. By counting with the neural networks forward, the fuzzy subjection vectors of the malfunction cause were gained. The type of malfunction cause was analyzed and ensured, and this fuzzy neural network in diagnosing the malfunction of air still press axletree has been applied. The result proves that the method is effective.
Design of an innovative vehicle intelligent collision warning model
Wang Jiangfeng, Gao Feng, Wang Jian
2007, 33(11): 1325-1328.
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According to the shortcoming of present single threshold intelligent vehicle collision warning model that it has single response time, a innovative collision warning model was designed based on multi-grade warning rules, which offers a gradual response time for driver, and can increase more react time for the driver to avoid collision in an emergency. Driver′s information perception character in the course of vehicle traveling was analysed, and that offers corresponding theory foundation for the establishment of the following collision warning model. The collision warning model was designed based on multi-grade warning rules, and the design process was discussed in detail. The model is verified using the actual measurement data, and result shows that driver can drive more comfortably in this multi-grade warning model. Meanwhile, it presents good model foundation reference for intelligent collision warning system in future.
Analysis of the error of tuned gyroscope with fixing tilt angle
Luo Yufeng, Xu Chao, Fan Yaozu, Zhang Hai
2007, 33(11): 1329-1333.
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The gimbal ring and drive axis is impossible to coincide with the centre axis of gyroscope completely during the assembly process. The movement equation of the dynamically tuned gyroscope considering of the disturbing of fixing tilt angle with the theoretical mechanics was set up based on the analysis of pressure on the rotor and the gimbal ring, and the discussion were also carried out. The analysis results indicate that fixing tilt angle of gyroscope and gimbal ring have influence on the tuned condition of dynamically tuned gyroscope (DTG), and the disturbing torque is unrelated with the state of motion however it is related with the active force of torquer to rotor. Thus, it is better to have the centre axis of gyroscope coincided with the gimbal ring and drive axis to reduce the influence to the dynamically tuned gyroscope.
Symmetric control of asymmetric cylinder
Zhang Xiaoning, Wang Yan, Fu Yongling
2007, 33(11): 1334-1339.
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The open loop gain and some parameters are different on the two moving directions of symmetric valve controlling asymmetric cylinder system. This difference leads to dynamic performance asymmetry on the two moving directions. The natural nonlinear and asymmetric system is difficult to control. The last three joints of PБ-211 robot are controlled by symmetric valve controlling asymmetric cylinder system. To make the robot moving smoothly and improve the control precision, the control system must have proper compensation. After analyzing the asymmetric cylinder and taking the difference of protrusion and retraction into account, a new control algorithm, model reference self-tuning gain adaptive algorithm, was put forward. The new algorithm includes adaptive single neuron PID, model reference adaptive algorithm and self-tuning output gain. Simulations and experiments illustrate that the new control algorithm can compensate the asymmetric cylinder system, which is better than the command PID algorithm.
LS-SVM method for dynamic weighing velocity compensation about loaders
Wang Tianmiao, Wang Wei, Wei Hongxing, Chen Diansheng
2007, 33(11): 1340-1344.
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Whether or not to compensate the oil pressure because of lift crane velocity reasonably, i.e., the velocity compensation was thought to be the key to obtain accurate dynamic weighing about loaders. After the method of dynamic weighing was given, the parameter inferring course of least square support vector machines (LS-SVM) within Bayesian evidence framework was introduced. Then the frame model of velocity compensation based on LS-SVM was given, and the means of velocity compensation and the course of weight computing were introduced in detail. Test results indicate that using LS-SVM within Bayesian evidence framework for solving velocity compensation, a relative measuring error within 1% can be obtained, which verifies that the validity of the method.
Set-membership algorithm for identification of structural parameters based on ARMA time-series model
Wang Xiaojun, Qiu Zhiping, Wu Zhe
2007, 33(11): 1345-1348.
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Identification of structural parameters by using observation data with noise in time domain was studied. Autoregressive moving-average (ARMA) model of a vibrating structure was established, and the identification problem of structural parameters was transformed into the identification problem of parameters of ARMA model. Based on the assumption of the unknown-but-bounded (UBB) noise, an interval algorithm for set-membership identification of parameters of linear time-invariant system was used to seek the minimal hyper-rectangle (or interval vector) of parameters, which is compatible with the measurements and the bounded noise, so that the structural parameters can be obtained. The numerical example illustrates its feasibility and effectiveness in comparison with the least squares algorithm.
Surface free energy of basalt and glass fibers by contact angle method
Deng Rui, Li Min, Zhang Zuoguang, Jia Jingjing
2007, 33(11): 1349-1352.
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The surface free energies and their dispersion/polar components of basalt and glass fiber were investigated using dynamic contact angle analysis. According to Fowkes′ and Good′s theory,by making use of the contact angle values for monofiber surfaces and standard liquids with known values of surface energy,surface free energy values as well as their components of both fibers were evaluated. It was found that the surface free energy of sized basalt fiber was higher than sized S-2 glass fiber while the polar component of both fibers tended to decrease without sizing; the liquid polarity also influenced the quantity of polar interactions as well as the quantity of dispersion interactions. These results indicate that sizing on the fiber improves wettability and interface adhesion between fibers and resin in fiber reinforced composites.
Variable-fidelity optimization system for turbine blade preliminary design
Han Qianpeng, Guo Li, Deng Jiati
2007, 33(11): 1353-1357.
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Variable-fidelity and multidisciplinary optimization approaches were presented and an automatic design system was developed for turbine blade preliminary design to improve design efficiency. The system integrated analysis tools and design teams, as well as data management system, which enabled performing variable-fidelity and multidisciplinary turbine blade optimization design automatically. Low-fidelity model consisted of experiential formulation was used in the initial phase, and high-fidelity model consisted of accurate computational fluid dynamics analysis and structural analysis was used in three-dimensional simulation of optimization phase. According to fidelity of analysis model, design process was divided into three stages to attain the optimum solution gradually, and both design point and off-design point were considered during optimization. As design space was narrowed gradually and researched by design of experiment, computational cost associated with high-fidelity analysis was reduced. Finally, preliminary design for blades of an axial-flow turbine with two stages was performed to validate the system.
Application of electrochemical methods to corrosion resistance evaluation for carbon fiber/epoxy composites
Lü Xiaojun, Xiaojun Zhang, Qi Diao, Peng Xiang
2007, 33(11): 1358-1361.
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The influence of different kinds of solution immersion on the properties of carbon fiber reinforced plastics was studied by means of cyclic voltammetry curves (CV) and electrochemical impedance spectroscopy (EIS). The relationship between electrochemical parameters and corrosion degradation of composites was discussed. Results show that the reaction resistance decreases and double layer capacitance increases with the increase of immersion time. The electrochemical parameters changes obtained from the acidic and alkaline probe solutions are more obviously than those obtained from the neutral probe solutions. Results indicate that the change of electrochemical parameters can reflect the corrosion degradation of composites, and electrochemical parameters can be used to evaluate the corrosion resistance of carbon fiber reinforced epoxy composites.
Three-dimensional geological modeling based on hydro sections
Cheng Dan, Yang Qin, Zhang Yongbo, Jin Maozhong
2007, 33(11): 1362-1366.
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Since section is a common and valuable data model, a novel modeling method based on sections was proposed, namely "section information extraction", and modeling steps were presented. The matter to which attention should be paid and necessary preprocessing before modeling based on sections were analyzed. Methods of section generalization, section mapping from the space of two-dimension to that of three-dimension, building background grid of section information and correcting error section information were introduced. A novel method of "top surface-pinch out line-lens" was applied to reconstructing lens model, which converted the complex multiple-valued modeling to single-valued modeling. Then modeling algorithms of single-valued layer and lens were described respectively. At last, an application example was shown, which proved the efficiency of the modeling method based on hydro geological sections.
Electronic-police system architecture based on Web Service
Zhao Hongtao, Li Chao, Sheng Hao, Xiong Zhang
2007, 33(11): 1367-1370.
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The traditional electronic-police system cannot adapt well to the requirements of enormous data in terms of compute speed, network-transport speed and storage capacity due to its excessive dependence on single server. Based on Web Service technology, the E-Police system architecture contained cluster-servers of peer-to-peer industrial computers and single back-end client. The compute service, storage service and query service were introduced. The implement of three services was the core of incompact E-Police system, which carried out the work by cluster-servers to increase the resource utilization. A integrated management scheme of assignment, resource and data flow was implemented depending on the preparation, release and establishment of Web Service, which resolved the imbalance among system compute performance, storage capacity and quality of the image.
Physical topology discovery algorithms based on inear dependency of traffics in IP network
Jin Yi, Shen Zengwei, Zhou Gang
2007, 33(11): 1371-1377.
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In IP network, general physical topology discovery algorithms are based on the network devices- AFT (address forward tables) which are obtained through SNMP (simple network management protocol). Unfortunately, the results of such algorithms are usually not exact or correct in practical networks for many factors. To solve this problem, a new physical topology discovery algorithm based on the traffics- characteristic was proposed. First, interface-s input rate and output rate were considered as random variables, and the linear correlation function of two rates was difined. Secondly it was proved that the correlation function of the rates of two interfaces which connect each other directly had the max value. Then the topology discovery algorithm was proposed based on the previous conclusion. The algorithm could achieve a most likelihood result based on the rates- linear correlation. At last, the algorithm was tested in a practical network.
Ring artifact correction for industrial CT images
Li Junjiang, Hu Shaoxing, Li Baolei, Yang Min
2007, 33(11): 1378-1382.
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Ring artifacts in computed tomography (CT) images are introduced by imperfect pixel channel in a detector. Ring artifacts degrade the CT image, hamper post processing and prohibit quantitative analysis. A set of algorithms that enable virtually complete ring artifact correction were proposed. Correction for pixel channel response nonuniformity was that offset and gain correction were done to compensate for response nonuniformity in the detector. Correction for projection sinogram data was that the vertical line artifacts in the sonogram were removed by a computationally efficient filter. Correction for already-reconstructed images was that the ring artifacts in the Cartesian coordinate were transformed into the vertical line artifacts in the polar coordinate and removed as sonogram correction. The procedures were created to deal with data acquired from an YXLON XRS232 9″ image intensifier. Ring artifacts were reduced significantly with minimal to negligible contamination of the underlying data.

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