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2006 Vol. 32, No. 11

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New approach for swarming aircraft positioning via network information
Feng Peide, Xie Shuxiang, Zhang Jingjuan
2006, 32(11): 1263-1267.
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The swarming aircraft organized by network will become a basic operation mode for the Airforce under network centric warfare(NCW) environment. A new approach for swarming aircraft positioning based on mutual distance measurement data is proposed. Simulation results show that the position accuracy for an individual INS in a swarming aircraft group can be improved up to 5m in 1.5 minutes time period if distance measurement error is 20m (1σ). In the meantime the time synchronization between network nodes can be improved up to 1ms. If 15minutes time period is permitted, the parameters of inertial navigation system(INS) error model can also be estimated. After correction the INS position accuracy can be improved up to 30m (CEP, circular error probability) in the subsequent half an hour, position accuracy can be increased by about 10 times. The periodic positioning via network can not only obviously increases the positioning accuracy for the swarming aircraft but also detects the soft failure of the particular system and isolates it by system reconfiguration.
Unique world coordiantes based global calibration method for multi-vision inspection system
Zhang Guangjun, Wei Zhenzhong
2006, 32(11): 1268-1272.
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An unique world coordiantes based global calibration method is proposed, in which double theodolites system coordinare frame is taken as the general measurment coordiante frame and the system is used to directly sample calibrations points for each vision sensor in the multi-vision inspections system. Thus the whole sensors in the inpection system can finish global calibration by one time, and no medi-coordinate-frame is needed. Therewith, transformation times of coordinate frame decreases and calibration course is facilitized. Measurement accuracy analysis of the image coordinates and object coordinates is performed on the double theodolites system, respectively, and the range of sampling calibration points for gaining high measurement accuracy of theodolite in practice is provided. Finally, global calibration experiment on a real multi-strutured light stripe vision inspection system is conducted with root mean square(RMS) error of not more than 0.24mm.
Autonomous celestial navigation for lunar explorer based on genetic algorithm particle filter
Fang Jiancheng, Ning Xiaolin
2006, 32(11): 1273-1276.
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Autonomous celestial navigation system is a typical nonlinear, non-Gaussian dynamic system. Extended Kalman filter (EKF) is widely used in spacecraft navigation. It only uses the first order terms in the Taylor series expansion. To nonlinear and non-Gaussian system, EKF may introduce large estimation error. Particle filter(PF) is a computer-based method for implementing a recursive Bayesian filter by Monte Carlo simulations. PF is an effective solution at dealing with nonlinear and/or non-Gaussian problems. The performance of PF relies on the choice of importance sampling density and resampling scheme. To overcome the particle degeneration and sample impoverishment problems existing in traditional particle filter method, a new autonomous celestial navigation method for lunar explorer based on genetic algorithm particle filter method is presented. Simulation results demonstrat the validity and feasibility of this new method.
Improved temperature error model of silicon MEMS gyroscope with inside frame driving
Fang Jiancheng, Li Jianli, Sheng Wei
2006, 32(11): 1277-1280.
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Temperature error is one of the main errors for MEMS(micro electronic mechanical system)gyroscopes. For eliminating temperature error of silicon MEMS gyroscope with inside frame driving, the improved temperature error model of gyroscope was presented. Based on the Seebeek theory of silicon material and the distortion depending on temperature of microstructure, the bias error was analyzed. The interferential moment depending on temperature was employed to analyze the error which relates with force and angular acceleration. According to the inherent frequency change depending on temperature, the error of scale factor was analyzed. The experimental results show that the interferential moment which relates with force is primary factor resulting in bias error of gyroscope during temperature change and verified the accuracy of the theories model. The bias stability and scale factor precision of gyroscope compensated by improved temperature error model were improved 53.75 and 19.6 times respectively. The improved temperature error model is applicable to other silicon MEMS gyroscopes.
Fast data fusion method for integrated navigation system and hardware in loop simulation
Cao Juanjuan, Fang Jiancheng, Sheng Wei
2006, 32(11): 1281-1285.
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The main factor in determining the computation time of Kalman filter is the dimension of the model state vector. The number of computations per iteration is direct proportion of n cube. Any reduction in the number of states will significantly decrease the computation time. Since 70 percent of the filtering calculation task is the forecast equation of covariance matrix, the method of reduced-dimension model and matrix product is applied in the micro inertial measurement unit/global positioning system/micro magnetic compass (MIMU/GPS/MMC) integrated navigation system, and the hardware in the loop simulation results based on the micro processor prove that the method not only can provide satisfactory accuracy for aircraft navigation but also can reduce the filtering calculation.
Simulation of a strapdown inertial continuous wellbore survey algorithm
Zhao Jianhui, Kong Qiying, Li Fan
2006, 32(11): 1286-1289.
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To achieve the fast and precise survey goal, a strapdown measuring algorithm which is based on an existing gyrocompass survey algorithm is studied. It offers two survey modes according to the inclination: the gyrocompass survey mode (inclination≤15°) and the continuous survey mode (inclination＞15°). During the gyrocompass survey procedure, wellbore headings are determined at predetermined stations. During the continuous survey procedure, wellbore headings are measured while the tool is continuously moving through the wellbore. The initial heading reference of the continuous mode is determined using gryocompass survey technique. Mathematic modules of the two survey modes are built. Finally, simulation tests are carried out to demonstrate the validity of the continuous survey algorithm. Measurement error is obtained by comparing the designed trajectory and the simulated one. Result indicates that it can take measurements of inclination 0°~90° and azimuth 0°~360°continuously, and enhance the whole survey efficiency greatly.
Circulation edge algorithm in frequency domain to suppress the ringing ripples on the restored image
ZhaoYan, Li Dongxing, Xu Dong
2006, 32(11): 1290-1294.
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A restoration approach of the circulation edge algorithm in frequency domain based on the Wiener filtering is proposed. The effective regularization expression and the estimation method of the signal to noise ratio(SNR) are presented. First, the original supervised image is extended with the reflection symmetry manner to a new supervised image (NSI). Then, the NSI is restored by the Wiener filtering algorithm, and the primary value sequence of the image restored by the NSI is considered as the restored image which is corresponding to the original supervised image. When the NSI is restored in frequency domain, the fast Fourier transform (FFT) technique need to be used and the NSI is extended periodically. Thus the gradient on the extended edges in the orthogonal orientation is zero, and the differential condition is satisfied with the edge smoothness. Therefore, the ringing ripples produced by the sharp changes of the extended edge′s gradient are suppressed. In the restoration process, the ratio of the noise power spectrum to the original image power spectrum is regularized to the function of the SNR of the original supervised image. The experimental results show that the restoration effect using this approach is better than the one using Wiener filtering for the supervised image having large gradient changes on the area near to its edges.
Observer-based steering law design for control moment gyroscopes
Wu Zhong, Wei Kongming
2006, 32(11): 1295-1298.
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Usually, the pseudo inverse of the Jacobian matrix needs to be calculated in the conventional steering laws for single gimbal control moment gyroscopes (SGCMG). However, the steering law does not work when the Jacobian matrix is singular and its pseudo inverse is indefinite. Therefore, the problem of the steering law design for SGCMG is transformed into the state observation of a certain nonlinear system and a new steering law is derived. This algorithm can deal with the singular conditions because it uses the transpose instead of the pseudo inverse of the Jacobian matrix. Theoretical analysis indicates that this algorithm can make the steering error converge to zero asymptotically through the proper choice of the parameters. Compared with the other steering laws, this algorithm has advantages on simple form, little calculation burden, and easy implementation. Finally, the simulation analysis is conducted for a certain SGCMG system mountedon a rigid spacecraft. Simulation results demonstrate that the steering law presented above is feasible.
Gain scheduling cross feedback control approach for magnetic suspending flywheel
Tian Xihui, Fang Jiancheng, Liu Gang
2006, 32(11): 1299-1303.
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At high rotational speeds, the gyroscopic effect of flywheel rotor is the major factor that influences rotor stability. The gyroscopic effects will lead to nutation destabilization or procession destabilization. A gain scheduling proportional cross feedback control algorithm based on the rotational speed is accepted to compensate nutation and precession lag in phase by creating the parameter table of cross feedback channel according to different rotational speed interval. The active magnetic bearing-rotor system model based on the gyroscopic technical equation is established. Root locus method of the classical control theory is used to give nutation stability simulation and analysis based on this model. Instruction of setting and optimization of the controlling parameter is presented. Simulation and test prove that this method can improve nutation stability caused by gyroscopic effects effectively. The designed prototype magnetic suspending flywheel can reach its rated design speed (30000r/min) stably.
New permanent magnet biased radial magnetic bearing in magnetic suspending flywheel application
Fang Jiancheng, Sun Jinji
2006, 32(11): 1304-1307.
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To overcome the defects of the present permanent magnet biased radial hybrid magnetic bearing, a new permanent magnet biased radial hybrid magnetic bearing in magnetic suspending flywheel application is reported. The fundamental principle of the radial magnetic bearing is presented. And the radial magnetic bearing are analyzed and calculated by using the equivalent magnet circuit and finite element method (FEM). As a matter of fact, the flux of permanent magnet and electromagnetic occur in any radial plane, so the axial length of the radial magnetic bearing will be less. Therefore, the presented radial magnetic bearing has smaller volume compared to the existing structure. In addition, there is no coupling between X and Y direction so that the control is easier. It is more applied to the high speed or low loss occasions.
Resonant sensor with double resonators
Fan Shangchun, Cai Chenguang, Wang Yingying, Xing Weiwei
2006, 32(11): 1308-1311.
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A new resonant sensor consisting of two resonators of uniform structure and size is presented. The closed loop control system is composed of two amplitude controllers and an inverter. The frequency characteristics of the two resonators in series are analyzed. It is found that the phase shift of the two resonators in series is 180° at the resonator′s nature frequency. Based on the frequency characteristics, the closed loop system of a resonant sensor with double resonators is designed. When the structure and size of the two resonators is not uniform, the frequency characteristics of the two resonators in series are also analyzed. When there is a little difference between the two resonators in series, they can also be used in a resonant sensor. In the closed loop control system, the phase shifter need not be used. The measurement error brought by the phase drift is avoided, and the Q factor of the resonant sensor is effectively increased.
Closed loop systems of resonant small sensors and microsensors based on DSP technology
Zhou Haomin, Zhao Qiaozhuan, Tang Zhangyang
2006, 32(11): 1312-1315.
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In the application of small sensor and micro-sensor, especially silicon resonant micro-sensor, the detection of weak signals with low SNR(signal noise ratio), the miniaturization and the anti-jamming problems of the self-oscillation closed-loop system are quite outstanding. Digital PLL (phase locked loops) closed loop measurement system of the compound tuning fork resonant pressure sensor directly transforms input analog signals (pressure) into the semi-digital signals (frequency) with high precision, which has basically solved the problems of the measurement system such as micro structure parameters, high work frequency and weak amplitude, strong coupling and big disturbance of the effective signals etc. The method can be applied to the silicon resonant micro-sensor directly, which is significant and directive for the application of silicon resonant microsensors.
Design and realization of calibration method of electronic transformer
Qian Zheng, Li Tongjie, Zhang Xiang
2006, 32(11): 1316-1319.
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It is necessary for electronic transformer to make calibration before putting it into practice. A new calibration method is presented in order to solve existent problems of actual calibration course. The frequency of power system is accurately measured according to the combined measurement principle of the limited iteration and the least squares method. The quasi-synchronous algorithm is introduced, some key parameters and steps are especially discussed, and thus the accuracy of the calibration method influenced by the frequency vibration will be significantly improved. The simulation results of new calibration method is achieved, and it is well coincide with the testing results. It shows that the performance and efficiency of new calibration method is satisfied. It will provide the powerful theory support for the development of portable intelligent calibration equipment.
Maximum entropy method for fault prior probabilities
Meng Xiaofeng, Ji Hong, Wang Guohua, Zhong Bo
2006, 32(11): 1320-1323.
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To solve precision problem of fault prior probabilities, the calculation model of fault prior probabilities based on maximum entropy theory was proposed. Through this model, which could make full use of the given prior information as the constraints of maximum likelihood estimation and based on Lagrange function, the calculation problem of fault prior probabilities was transformed to non-constrained optimization problem. The non-constrained optimization problem was solved rapidly, based on the gradient method mixed by steepest decent method and Newton method. When the faults were overabundant in large scale system, the highly multidimensional fault space could be decomposed by the principle of decomposition of system. The fast calculation method of fault prior probabilities was given in lowly multidimensional space. With the comparison of the result calculated by the maximum entropy method and the MTTF(mean time to failure) method respectively, the maximum entropy method was proved to be more precise.
Comprehensive TPS diagnostic capability assessment methodology based on Dempster-Shafer evidence theory
Meng Xiaofeng, Wang Guohua, Ji Hong
2006, 32(11): 1324-1327.
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The assessment of TPS (test program set) diagnostic capability is one of the key means for TPS quality assurance. According to the comprehensive assessment problem of TPS diagnostic capability, a new knowledge fusion method based on D-S(Dempster-Shafer) evidence theory is developed. The rationale of D-S theory is introduced at first. The mathematical model and framework of TPS diagnostic capability assessment is proposed. The BPAF (basic probability assignment functions) definition and decision of TPS diagnostic capability feature based on K-S test (Kolmogorov-Smimov test) is described in detail. The process of TPS diagnostic capability assessment is given. At last an example is shown to assess an avionic equipment TPS. Result shows that D-S theory can effectively consider multi-features of TPS and decrease the decision uncertainty region.
Speedy calibration of low frequency vibration transducer by using linear frequency modulation signal
Fan Shangchun, Li Xiaolei
2006, 32(11): 1328-1332.
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Aiming at calibration demands of low frequency vibration transducer and characteristics of low frequency vibration calibration system, transducer was inspired by the linear frequency modulation (LFM) signal so that its frequency characteristic could be gotten through once measurement. Calibration time reduces from a score of minutes to less than one minute, therefore its calibration efficiency improves greatly. In order to avoid the imprecise calibration result at high frequency band due to imperfect frequency characteristic of the system, digital compensation filter was designed to instantaneously compensate signal source based on the dynamic frequency characteristic of the system and time-frequency domain characteristic of LFM signal. After signal source was compensated, vibration table might give rise to more ideal LFM signal, and calibration results of transducer are closer to the absolute calibration results as well as advancement in repetition rate. This method also qualifies for calibration efficacy and accuracy, and develops the practicability of calibration system.
Improved independent component analysis applied to classification hyperspectral imagery
Zhao Huijie, Li Na, Jia Guorui, Dong Chao
2006, 32(11): 1333-1336.
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To avoid the disadvantage of getting into local optimum solution with general numerical computation methods in the general independent component analysis and the restriction of neuron activation functions of neural learning algorithm, an improved model of independent component analysis (ICA) based on genetic algorithm was proposed for the unsupervised classification of hyperspectral data. In the proposed algorithm, the maximizing non-Guassianity was used to measure the statistical independence of the components, and the forth-order cumulant, kurtosis, was adopted as fitness function in genetic algorithm. In the application, the global optimum solution can be obtained and the fine plant classification can be implemented without any prior information when the proposed algorithm is applied to the push-broom hyperspectral technique imager (PHI) data. Moreover, compared with the conventional unsupervised classification algorithm of hyperspectral data, the proposed algorithm is more applicable and can obtain the better precision and accuracy.
Basic theory and its principled experiment of non-diffracting interference in aiming system
Wang Zhongyu, Zhou Cong, Zhang Duo
2006, 32(11): 1337-1340.
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The non-diffracting technique was combined with the traditional Moire fringe interference technique and was applied firstly in the airborne opto-electronics system. A novel airborne aiming method was developed in basic theory and its principled experiment, the relevant aiming and tracking techniques were also proposed. This method could be carried out by adjusting the airborne opto-electronics system according to the deviation and variation of the interference patterns caused between the non-diffracting beam and objective circular gratings.The accurate aiming purpose could thus be completed. The newly developed aiming and its tracking techniques would not only be helpful to improve the dynamic responsibility, tracking accuracy and the reliability of the aiming pods, but also enhance the attacking ability with high accuracy during the offensive process. Therefore it can be used to provide the technical store for the new airborne weapon and its equipment.
Application of HHT analysis in surface roughness
Li Chenggui, Li Baogui, Sun Dan, Xiong Changyou
2006, 32(11): 1341-1344.
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HHT(Hilbert-Huang transform) is a new two-step time-frequency analysis method to analyze the nonlinear and non-stationary signal. The key step of this method is EMD(empirical mode decomposition) method with which any complicated data set can be decompose into a finite and often small number of IMF(intrinsic mode functions). The HHT can decomposed curve of the surface roughness into component with different frequency spectrum. Each component has its own physical meaning. So it can distribute all sorts of factor which had an influence on finished surface. As a consequence, the allsided Hilbert spectrum could be got. Based on this spectrum, it can be know how contributing factor function in workpiece process. HHT is used in the analysis of roughness, and the conclusion is helpful to machining.
Blind image restoration algorithm based on adaptive decision feedback equalizer
Jiang Jie, Lü Bo, Zhang Guangjun
2006, 32(11): 1345-1348.
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ADFE(adaptive decision feedback equalizer ) is derived from transverse equalizer. It uses decision output signal to form a delay line, through which parts of coefficients are added together and are returned to the output. It can compensate for channels with severe intersymbol interference which is like the blurred image. The blur on image can be regarded as perturbation of the pixels, so a kind of ADFE is applied to 2D image restoration. The Lee filter is adopted to reduce noise. There are two adaptive filers in this method, so the forward filter has more flexibility to select its coefficients and not inverse blur only. As a result, the noise enhancement will not happen. Additionally, the support of the object is confirmed by threshold. The experiment proves that this new algorithm is robust under high noises, and that it′s an effective algorithm.
Visual 3D motion estimation of UAV and landing target based on extended Kalman filter
Wang Rui, Yan Peng, Liu Hongying, Zhang Guangjun
2006, 32(11): 1349-1353.
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During the last phase of auto landing an UAV (unmanned aerial vehicle) on the ship, the estimation of the 3D relative motion parameters between UAV and the landing target can be regarded as the planar 3D motion estimation between the camera mounted on the UAV and the deck. An algorithm for visual motion estimation of 3D objects based on extended Kalman filter is presented. First, the camera coordinate with the origin at the camera′s lens and the world coordinate are set up appealing to the principles of perspective projection. Then, the actual 3D camera motion parameters (the three Eulerian angles, transition vectors and their velocities) can be described in terms of the state equation. Furthermore, with the target corner extraction and frame matching, the observation equation is proposed to give the relationship of the feature points in the image and the state vectors. All the 3D relative motion parameters are solved by the stated EKF(extended Kalman filter) method. The presented experimental results of both synthetic data and the real image sequences show that our algorithm is effectively and robust.
Modeling and identification of random drift for FOG
Zhu Kuibao, Zhang Chunxi, Song Ningfang
2006, 32(11): 1354-1357.
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Random drift is a main error of fiber optic gyro (FOG), it is a efficient method to reduce the random drift and improve the accuracy by modeling and compensation from the output of FOG. The static output of FOG is a random project, the steability and randomicity are analysised, the trend and periodicity is suited and compensated. The random drift of FOG is modeled by time series analytical method, the type and ladder are identificied by the autocorrelation function. The coefficient of the model is estimated by the least square, the FOG random drift model is AR(2). The raw data is compensated with the model, and the validity of the model is tested .It is shown that the result is greatly improved, and the random drift is efficiently reduced, the accuracy of the FOG is greatly improved. The model also is as the state of Kalman filter in the inertial navigation system.
Fiber micro-vibration readout sensor based on MOEMS
Xiao Wen, Li Rui, Liu Dewen, Yi Xiaosu
2006, 32(11): 1358-1361.
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To measure the vibration of micro-structure, a scheme of sensor basedon micro-optic-electro-mechanical system(MOEMS) with fiber-optic readout was proposed,and its mathematical model was deduced. The single-fiber readout structure and a micro-structure fixed in the front of the sensor were used. The micro-structure vibrated as the measured object moved, and its vibration caused the change of light intensity. The sensor detected vibration displacement by receiving the light intensity. As a result of the single-fiber structure and the parameters optimization of micro-structure, compared with other fiber readout structures, this system has the advantages of high sensitivity and miniaturization which is easier to match with fiber system. The response behaviors of the system to the piezoelectric ceramics excitation were studied through the experiments. And it could detect the vibration displacement of 0.18nm.
Reflection polarization maintaining optical fiber temperature sensor
Yang Yuanhong, Liu Bo, Li Li
2006, 32(11): 1362-1364.
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A reflection polarization maintain optical fiber temperature sensor was proposed based on the polarization mode interference theory in polarization maintain optical fiber and the sensing equation was derived. Analyses prove this sensor can achieves high accuracy and the measurement range can be adjusted easily by changing the polarization maintaining optical fiber sense probe length. For the demand of field temperature monitoring of huge power transformers, a prototype with special high temperature polarization maintain optical fiber sensing probe and sealed package was made and the sensor probe can stand the harsh environment of hot oil and high voltage. With this prototype, the temperature within range 0℃~180℃ was measured and the linear output was obtained after model linearized and date processed. Long time measurement was investigated in 0℃ environment formed with mixer of ice and water, the result shows the sensor stability and accuracy were both better than 0.15℃.
Broad bandwidth signal detection scheme for high precision fiber optic gyroscope
Wu Zhanjun, Zhang Xi, Wang Xiaxiao, Li Chen
2006, 32(11): 1365-1368.
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Good static and dynamics environment performance of the signal detection scheme is necessary to meet the practice application of the high precision fiber optic gyroscope (HPFOG). All-digital closed-loop signal detection procedure of HPFOG was analyzed. Closed-loop transfer function of the detection system was derived. The general eigen frequency modulation caused the long sample period and low bandwidth. The feedback can not null high frequency noise signal caused by the dynamics environment. The closed-loop system was destroyed, and unacceptable dynamic error was caused. The signal detection scheme based on triple eigen frequency modulation/demodulation was designed. The sample period was 1/3 that of the eigen frequency modulation, and the system bandwidth was increased effectively. The dynamics environment and static experiment results of the two schemes were compared. It shows that the triple eigen frequency signal detection scheme improved the dynamics environment adaptability of the HPFOG effectively, and the static performance is not infected. This can satisfy the application needs.
Design and simulation of sensor of differential fiber Bragg grating accelerometer
Liu Huilan, Feng Lishuang, Teng Li, Lin Heng
2006, 32(11): 1369-1372.
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A differential fiber Bragg grating (FBG) accelerometer was designed to solve the conflict of sensitivity and natural frequency for the conventional accelerometer with cantilever-mass structure. The system model was established and the measurement precision was theoretically calculated and analyzed. The sensor structure combined central beam and tiny beam was designed, which is an improved style of conventional cantilever-mass structure. The finite element simulation and analysis on static and dynamic characteristics proved that the system accuracy was 0.0105g and the natural frequency was 270Hz, which was 2.7 times of the natural frequency of a conventional cantilever-mass FBG accelerometer under same precision. Results also proved that the natural frequency could be increased without decreasing the sensitivity in this new differential FBG accelerometer.
Resonator design for MOEMS gyroscope
Feng Lishuang, Liu Huilan, He Bin, Wang Guanglong
2006, 32(11): 1373-1376.
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Micro-opto-electro-mechanical systems(MOEMS) gyroscope is one of the most potential development directions of micro-optical gyroscope. MOEMS resonator design is the key technique of MOEMS resonator gyroscope. A novel MOEMS spatial resonator based on micro-nano machining technology was put forward. The principle and structure of the resonator were introduced. The mathematical model was established. Important parameters of the resonator were calculated and analyzed with MATLAB. The in-out mirror of the resonator was optimized to increase the finesse of the resonator and the sensitivity of the gyroscope. The micro-fabrication technics of resonator was designed. Results demonstrate that the finesse of the resonator can be 346, the sensitivity of the gyroscope reaches 0.25(°)/h, and noise induced by Kerr effect, backscattering and so on can be overcome effectively.
Timing for miniaturized three-cluster fiber optic gyro
Pan Xiong, Song Ningfang, Jin Jing, Tian Haiting
2006, 32(11): 1377-1379.
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Eigen frequency of fiber optic gyro (FOG) is determined by the length of fiber coil. Since the length cannot be controlled accurately while winding, timing generator should trace the eigenfrequency expediently without modification of hardware. The influences of veracity and stabilization of modulation-demodulation signal on the scale factor of FOG was analyzed through the theory of correlation-based measurement. One chip of field programmable gate arrays (FPGA) was used to generate three timings of miniaturized three-cluster FOG within resourceconstraints, and the capacity of frequency tracing was calculated within the eigenfrequency range of middle precision FOG. Experimental results indicate that the timing scheme satisfied the requirement of miniaturized three-cluster FOG to modulation-demodulation signal.
Design of high precision fiber optic gyro strapdown system
Song Ningfang, Zhang Chunxi, Zhu Kuibao
2006, 32(11): 1380-1384.
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Referring to the object of high precision fiber optic gyro (FOG) strapdown inertial navigation system, the overall system design method based on the simulation is put forward. The key technology of FOG strapdown system design is analyzed. The design of body movement trajectory , the choose rule of Kalman filter variable state , the management of external assistant information and the application of Kalman filter in the initial ground alignment are emphasized to study. The simulation example of different filter variable state, the different integrated navigation time, one position ground alignment and two position ground alignment are compared. The result indicates that the topic of the system design is Kalman filter which ties up the dynamic characteristic, the integrated navigation mode and the inertial instrument accuracy level.
Three-cluster fiber-optic gyroscope for satellite
Jin Jing, Song Ningfang, Li Min, Tian Haiting
2006, 32(11): 1385-1389.
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Effects of space environment upon fiber-optic gyroscope(FOG) performance were studied, and a new-style assemble of 3-axis fiber optic-gyroscope used in satellite was designed. Simulation experiment was finished to analyze the effects of space radiation, vacuum environment and temperature cycle upon FOG. And the main mechanism of the effects of space environment upon FOG was obtained by analyzing the experimental data. A bias error model was developed by using least squares filtering, and a scale factor error model was developed by using look-up table. Both models were implemented in field programmed gate array (FPGA) for compensation of bias stability, which reduces the bias stability to 0.1(°)/h. The reasons for dead band in space are analyzed, and the error of dead band is to be suppressed by using the cycle phase modulation. During the design of the fiber optic gyroscope, the technology of multiplexing and redundancy of the light source, and the protective measures in space as well as the fault diagnosis in orbit are designed and implemented.
Fiber-optic network architecture and technology for avionics systems
Zhang Chunxi, Shi Jieqin, Duan Jingyuan, Yang Yusheng
2006, 32(11): 1390-1394.
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In advanced avionics systems, the date communication system requires high speed and hybrid traffic. A scheme of distributed fiber-optic network system was presented based on the design consideration of distributed control, real-time access and fault-tolerance. Along with designing the architecture and choosing the protocol, the critical technology points of the scheme were analyzed emphatically, including fiber-optic links, media access control(MAC) protocol, fault- tolerance, topology technology and network management software. The analysis result indicates that the distributed fiber-optic network based on IEEE 1394b bus can provide deterministic and reliable communication in which the Gb/s fiber-optic link can meet the necessary of bit error rate (BER) with abundant link margin of 13dB. Therefore it has advantages of high bandwidth, low delay and flexible expandability.

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