Table of Content

31 July 2009, Volume 30 Issue 7

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Paper

Development of Composite Detection System for the Key Parts of Armored Vehicle Chassis

FAN Xin-hai，WANG Zhan-jun, AN Gang,ZHANG Chuan-qing

2009, 30(7):  849-852.  doi:10.3969/j.issn.1000-1093.2009.07.001

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A composite detection system for the key parts of armored venicle chassis was developed by an advanced design thought of integrated measurement and virtual instrument; the software of multi?channel data acquisition, signal analysis and processing, fault diagnosis were programmed, to realize multi-parameter non-disassembly detection on actual vehicle working condition and Key parts technical status analysis. It has important significance to.improve the maintenance support ability of equipment.

Operational Modal Analysis Experimental Technique Used for Self-propelled Gun

WANG Bao-yuan, LIU Peng-ke，HENG Gang,ZHOU Fa-ming, YANG Dong, LI Ming-tao

2009, 30(7):  853-856.  doi:10.3969/j.issn.1000-1093.2009.07.002

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The experimental modal analysis of the selected self-propelled gun was completed with oper?ational modal analysis exoerimental technique; the modal frequencies distribution and modal modes were obtained; the analyzed result by the proposed method was compared with that by the traditional one. The compared result shows that obtained result by the proposed methoa is in agreement with that by the traditional method.

Analysis on the Stochastic Passage Characteristics for Gun Tube Through the Shooting Domain

WANG Jun, LI Yu-shan, ZHANG Xian-chun, GUOZhi

2009, 30(7):  857-861.  doi:10.3969/j.issn.1000-1093.2009.07.003

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Taking aim at a class of weapon system with shooting domain, the stochastic passage char?acteristics for gun tube were studied. On the basis of the exact definition of stochastic passage charac?teristics, the conclusion, in which opportunity-awaiting time, residence time and stochastic passage period obey geometric distribution, was given by the transition probability matrix; their mean's and variances were also derived; the relations between the time indexes and the structure and parameters of weapon control system were established. Finally, the creditability of the results was proved by the test data of weapon system in proving ground.

Numerical Study of Pitching Dynamic Characteristic for Hypersonic Missile

HE Guo-hong, YANG Xiaoliang, ZHAO Hai-yang,LIU Wei

2009, 30(7):  862-866.  doi:10.3969/j.issn.1000-1093.2009.07.004

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The damping-in-pitch characteristic of hyperballistic shape (HBS) at different angles of at?tack was investigated and compared with the results of test and Newtonian method, the influence of reduced frequency, amplitude and base flow on the damping-in-pitch characteristic of HBS were also studied by the unsteady Navier-Stokes equations, which are solved with the tnird-order-in-space PWN- ND scheme constructed with power-limiter and used for describing the unsteady forced oscillating flow field over HBS, under the basis of Etkin’s unsteady aerodynamic model.

An Estimation Method for Submunition Dispersion Uniformity Based on Kernel X2 Test

FANG Yu-jun, JIANG Jian-wei

2009, 30(7):  867-872.  doi:10.3969/j.issn.1000-1093.2009.07.005

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It is one of important subjects to estimate uniformity of submunition dispersion points of fall. The current method using test has two disadvantages, which are that estimated results are sen?sitive to sub area partition, and large sample capacity is required to obtain correct results. The former makes confidence of estimated results decrease, and the latter makes applied scope of the method re?stricted .A modified test method called kernel test based on kernel density estimation and test was presented to improve these disadvantages. SuDmunition dispersion uniformity of a certain cluster warhead was estimated by the modified method and compared with the current method. The estimated results show that the modified method can overcome disadvantages of the current method, and describe submunition dispersion exactly.

Estimation of the Number of Signal Source in Spatially Nonstationary Noise

YE Zhong-fu，LI Chun-hui, JIA Hong-jiang，LIU Chao

2009, 30(7):  873-878.  doi:10.3969/j.issn.1000-1093.2009.07.006

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A new estimation method of signal source number under the circumstances of spatially non- stationary noise was proposed on the basis of analyzing lack of a method with orthogonality of eigenvec?tor and discussing the existing problem in eliminating the noise with common diagonally matrix. A transform-based covariance differencing algorithm was used to eliminate the noise, and then the num?ber of signal source was determined by combining hypothesis testing with Bootstrap techniques. The algorithm has better estimation performance at low SNR and without assuming noise distribution mod?el, and practical value to a certain extent.

A Correlation Tracking Algorithm Based on Template Partition Motion Estimation

XU Yi-ming, LIU Xiao-Li, LIU Yi-xin

2009, 30(7):  879-884.  doi:10.3969/j.issn.1000-1093.2009.07.007

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A correlation tracking algorithm based on template partition motion estimation was proposed for improving real time performance of the conventional correlation matcnmg algorithms. The imple?mented steps of the method are that target motion trajectory is fitted with least square total interval isometric algorithm to obtain a target prediction point; according to the requirement of a block motion estimation (BME) algorithm, the template is divided into some macro blocks; the searching process is conducted by using a diamond search algorithm for macro blocks around the prediction point, to get optimal motion vectors of all macro block; the point corresponding to the motion vector with the opti?mal matching measurement is set as a rough matching point of the template; the relation of relative po?sition between the block with matching point and the searcnmg area is used to decide whether to con?duct precise matching search or to construct a new search area in the gradient direction. Target track?ing experiment was performed by CCD, image acquisition card of the OK-MIOM type, computer and a controlled automobile remotely. The experimented results show that the calculating time with the proposed method decreases to 3.31 times compared with that of normalized product correlation (NProd) algorithm based on all searching.

Fast Filter Back Projection Algorithm Based on Symmetric Transformation Group

WANG Yi-duo, XI Ping

2009, 30(7):  885-889.  doi:10.3969/j.issn.1000-1093.2009.07.008

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After optimizing the filter back projection (FBP) algorithm of computer tomography (CT) with the theory of symmetric transformation group, a fast reconstruction algorithm was founded to re?duce calculating time cost in the back projection part of FBP.Since the back projection part is the ma?jor time-consuming part of FBP，so the new algorithm accelerates image reconstruction obviously, compared with old algorithm in the same condition, the reconstruction speed of the new one increases to more than twice.

Research of the Read-out Circuit for the Microgyroscope Using Double Modulating Sine Wave

XIAO Ding-bang, WU Xue-zhong, HOU Zhan-qiang,CHEN Zhi-hua, LI Sheng-yi

2009, 30(7):  890-895.  doi:10.3969/j.issn.1000-1093.2009.07.009

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The vibration signals of the microgyroscope’s mass on the driving axis as well as the detect?ing axis were modulated by two sine carrier waves with different high frequencies, so they were distin?guished with the sine driving wave on the frequency spectrum, and finally the coupling noise could be reduced. That mass was exciting to oscillate with fixed amplitude on the driving mode by phase control and DC auto gain control. The oscillations on the driving and detecting axis were picked up by syn?chronous demodulator, and then the angular rate was obtained through secondary demodulation. A mi?crogyroscope with this read-out circuit was tested and the results show that its scale factor is 38 mV/ (°)·s-1, and its linearity is 0.8% .

Simulation Study on No-load Voltage of Military Portable Generator Based on ANSYS

YANGJing, WANG Wei-jun, TU Ya-qing, ZUO Yong-gang

2009, 30(7):  896-899.  doi:10.3969/j.issn.1000-1093.2009.07.010

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The theory and method of analyzing the no-load magnetic field of military portable generator and simulating its no-load voltage based on ANSYS program were explained m detail. The no-load voltage simulation result of a prototype of military portable generator resembles its tested result, this proves the simulation method to be correct and effective. The simulation result can provide theoretical bases and method for engineers in optimizing tne design parameters to improve the power supply quali?ty of military portaole generator.

Fault Prognosis of Hydraulic Pump in the Missile Launcher

LI Hong-ru, XU Bao-hua

2009, 30(7):  900-906.  doi:10.3969/j.issn.1000-1093.2009.07.011

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The fault modes of hydraulic pump in the missile launcher were analyzed, tne vibration sen- sor，s installation site was optimized, the characteristic parameters for fault prognosis of hydraulic pump were extracted by analyzing the vibration signals using time-domain analysis and wavelet packet analysis; the fault prognosis model including fault mapping model and characteristic parameter progno?sis model of hydraulic pump was established in Matlab 6.5 based on support vector machine theory; the typical faults of hydraulic pump were prognosticated by the established model. Effectiveness of the model was verified by comparing the prognosticated results with the tested ones from a real example.

Aerodynamic Performance Simulation of Hypersonic Waverider in Near Space

XIAO Hong, WU Ding-yi, LIU Zhen-xia, LIAN Xiao-chun

2009, 30(7):  907-910.  doi:10.3969/j.issn.1000-1093.2009.07.012

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Aerodynamic performance simulation software system of hypersonic waverider vehicles in near space was developed by using the direct simulation Monte Carlo(DSMC) method based on molec?ular dynamics. Taking a certain aerocraft as an example, the effectiveness of the system was verified. Aerodynamic performances of the vehicle at the height of 70 — 100 km in near space were simulated, the influence of rare gas effect on aerodynamic performance of the vehicle was studied. Collision model and effect collision number of the DSMC method were improved, in order to avoiding a large amount molecule collision calculation caused by DSMC simulation in continuous medium district and. jumpiness district between temperature and velocity at the height of 70 — 100 km in the near space. Ihe studied results show the characteristic of lift-to-drag ratio of the vehicle descends in near space, but it remains high lift-to-drag aerodynamic advantage; the difference of simulation results between the DaMC and NS equation increases with the height increasing and the effect of rare gas increases gradually; it is proved that fifteen effect collision number in every grid is enough to simulate the macrophysical charac?teristic of air in DSMC method.

Confidence Intervals for the Coefficient of Variation for the Normal Distribution

SUN Zhu-Iing

2009, 30(7):  911-914.  doi:10.3969/j.issn.1000-1093.2009.07.013

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A problem of the estimation of the coefficient of variation for the normal distribution was discussed. A new pivotal variable to construct the classical confidence intervals for the coefficient of variation was given. And precision confidence intervals for the coefficient of variation of the normal distribution with a simple expression were also obtained.

Simulation and Analysis of Hydraulic and Balanceable Underwater Weapon Launching System

CHENG Guang-tao, KONG Yan-feng，ZHANG Zhen- shan

2009, 30(7):  915-919.  doi:10.3969/j.issn.1000-1093.2009.07.014

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Based on physical characteristic of an underwater weapon launching system for submarine, the mathematical model of the system was built which is composed of three sub-system models of im?pulsion module, hydraulic pressure conversion module and weapon system dynamics module. Accord?ing to characters balanceable launching system, the parameter of pressure increment was adopted, and taking the water cylinder, the water chamber and the launch tube as three chambers with uniform pressure, the linearity relations among weapon, piston subassemolies and water impelled were given, to reduce the complexity of the mathematical model. Simulation was conducted under the Matlab/ Simulink programing environment. The simulated results are in agreement with the obtained data, which shows that the established, model can be used, for dynamic analysis of the system.

A Modified Orthogonal Transform Domain Blind Equalization Algorithm for Underwater Acoustic Channel

ZHANG Yin-bing，ZHAO Jun-wei, GUO Ye-cai,LI Jin-ming

2009, 30(7):  920-924.  doi:10.3969/j.issn.1000-1093.2009.07.015

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To deal with the disadvantage of slow convergence rate of the traditional constant modulus algorithm (CMA), blind cnannel equalization in orthogonal transform domain was performed by trans?forming the equalizer input signal orthogonally. A modified transform domain CMA (MTDCMA) was proposed by using constellation match error (CME) item of the equalizer output, oimulation with un?derwater acoustic channel shows that the proposed algorithm has faster convergence rate than those of CMA and traditional transform domain CMA (TDCMA) at the same residual inter-symbol interfer-ences (ISIs).

An Improved Formula for Calculating Radiation Efficiency of Plate Around the Cut-off Frequency

LEI Ye, SHENG Mei-ping, XIAO He-ye, REN Jie-an

2009, 30(7):  925-929.  doi:10.3969/j.issn.1000-1093.2009.07.016

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While using the classical radiation efficiency formula of plate, discontinuity exists around the cut-off frequency. The phenomenon doesn’t consist with the reality. The reason of discontinuity was explained fully and an improved formula was proposed. The simulated results were compared with those of the classical formula and the FEM and BEM analyzed results. The compared results show that the improved formula has better precision around the cut-off frequency, its calculated result agrees with that of the FKM and BEM analyses, so the improved formula is effective and feasible.

Passive Directional Method Based on Arbitrary Four-sensor Vector Sound Intensity Array and ItsExperimental Investigations

SHI Jie, ZHANG Xiao-min, HAN Peng,YU Yang

2009, 30(7):  930-934.  doi:10.3969/j.issn.1000-1093.2009.07.017

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Vector sound intensity array can realize nigh precise passive direction of a low frequency source even in small scale, but its fixed structure restricts its engineering application to a certain ex?tent. A uniform direction model used for arbitrary vector sound intensity array with four sensors was proposed, and its directional estimation errors caused by finite difference approximation error(FDAE), instrumentation phase mismatch error(IPME) were analyzed systematically. Directional experiment on a typical array was done in a semi-anechoic chamber to verify the model. After compensating the FD/ml, the IPME and the random error caused by averagely reducing isotropic ambient noise based on the error analysis, the precision of DOA estimation comes closer to 1° by using 0.1m size non-typical vector sound intensity array. The experimented and analyzed results show that the model and its error analysis are correct.

Research of the Denoising the line spectrum signal of the ship-Radiated Noise Based on the WaveletInter-scale Dependency

HOU Tie-shuang, XIANG Jing-lin, HAN Peng

2009, 30(7):  935-939.  doi:10.3969/j.issn.1000-1093.2009.07.018

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The low-frequency line spectrum of ship-radiated noise is an important characteristic quanti?ty wiiich plays an important part in the signal detection, recognition and classification of acoustical fuze. With the decreasing of ship, especially submarine radiated acoustic energy and the increasing of ambient noise in the sea, the distance to detect targets based on using the line spectrum signal is get?ting shorter and shorter year by year. In order to denoise and detect the snip ’ s line spectrum signal submerged in ocean noise, a mathematic model of inter-scale joint distribution of wavelet coefficients for the noise and the signal was establisned, and an analytical expression of the maximum a posteriori (MAP) was deduced, on the basis of decomposing the noise and the signal by the dual tree complex wavelet transform (DT-CWl) and analyzing the inter-scale joint distribution of wavelet coefficients. The denoised results show that the proposed algorithm can evidently weaken the continuous spectrum disturbance component and improve detecting effect of the ship ’ s line spectrum signal.

Research on the Statistical Modeling and Simulation Method for Seafloor Reverberation

GUO Xi-ye，SU Shao-jing, WANG Yue-ke

2009, 30(7):  940-944.  doi:10.3969/j.issn.1000-1093.2009.07.019

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Taking the seafioor reverberation as a studied object, an uniform model for calculating rever?beration was deduced. In order to overcome the calculation complexity caused by calculating each of scatterers, a statistic model for reverberation was presented, which numerical calculation intensity is still considerable. A normal-mode model for calculating the reverberation excitated by the narrowband signal was got, in the narrowband aoproximation, numerical calculation of frequency became easy. The analyses of normal-mode model show that the reverberation excited by narrowband and high fre?quency signal can be expressed as a discrete convolution of the input signal and a group of random se?quence approximately; statistic characteristics of the reverberation signal vary with distribution of the scatters. A simulation method was designed, in which the scatter cell was divided by equal interval rule in range. The simulated results show effectiveness of the method.

Rudder/Fin Roll Stabilization with Energy Optimization Using a Lower-speed Steering Gear

JIN Hong-zhang, WANG Fan

2009, 30(7):  945-950.  doi:10.3969/j.issn.1000-1093.2009.07.020

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Taking aim at the requirement of the high-speed steering gears in most integrated rudder/fin roll stabilization systems, an integrated rudder/fin roll stabilization method using a lower-speed steer?ing gear was developed, to avoid the rapid wear of the steering gear and excessive fuel consumption due to frequent rudder actions. According to the rule for rudder commands, the original commands of au?topilot and fin stabilizer controllers were corrected on line, to realize the integrated rudder/fin system within permissible heading errors. The key factor of integrated rudder/fm controlling was optimized by the genetic algorithm based on analyzing resistance and energy loss of the ship. Finally, the validity of this approach was proved by comparing with original rudder and fin systems in different sea-condi?tions .The method, which is different from other ruader/fin roll stabilization methods, doesn’t need to improve or replace existing steering gears and fin stabilization systems, and has the better applica?tion value.

A New Magnetic Field Extrapolation Method in Magnetic Silencing of ships

ZHOU Guohua，XIAO Chang-han, LIU Sheng-dao, WEI Yan-Iin

2009, 30(7):  951-957.  doi:10.3969/j.issn.1000-1093.2009.07.021

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Extrapolation of the underwater magnetic field distribution below ships can provide neces?sary theoretical basis for the implementation of magnetic silencing technique. In order to effectively overcome the difficulties, which are often met in magnetic field extrapolation by traditional continua?tion methods, a direct model for magnetic field extrapolation based on equivalent surface magnetic charge intensity was derived from the boundary theory. Then an inverse model was given based on the measured magnetic field to calculate surface magnetic charge density. Due to lack of the enough mea?sured physical information, the inverse model is always ill posed. The inverse problem was solved by Tikhonov regularization method, which can suppress the disturbance of measurement error to the cal?culated equivalent surface magnetic charge intensity and improve the stability of the inversed results. Based on the direct model and the inverse model, the magnetic field of ships can be extrapolated, ri- nally, a numerical example ana a scale model ship experiment were given to verify the effectiveness and practicality of the magnetic field extrapolation. The verified results show that the proposed method is satis- iying for magnetic field extrapolation of ships, and has some military value in practical engineering.

Analysis for Traction Characteristics of HKD Aviation Lubricating Oil in Rolling/ Sliding Contacts

WANG Yan-shuang, DENG Si-er, YANG Hai-sheng,SUBing

2009, 30(7):  958-961.  doi:10.3969/j.issn.1000-1093.2009.07.022

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The tests of traction property for lubricating oil HKD were performed at various conditions by a self-made ball-disk traction rig. The variable rules of traction coefficient, the maximum traction coefficient and the slope of traction curve versus load, oil inlet temperature, rolling speed and slide-to- roll ratio for the oil were analyzed. Two equations for calculating the maximum value of traction coeffi?cient and the slope of traction curve were presented. The results show that traction coefficient increases with the load increasing and decreases with the rolling speed and oil inlet temperature increasing. The equations have high precisions.

Analysis of Assembly Error Affecting on Directing Precision of Spherical Gear Attitude Adjustment Mechanism

LI Ting, PAN Cun-yun，LI Qiang, ZHANG Li-jie

2009, 30(7):  962-966.  doi:10.3969/j.issn.1000-1093.2009.07.023

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Spherical gear is a gear-driven mechanism with a douole degree of freedom, wmch can be used for a satellite borne antenna attitude adjustment mechanism with characteristics of compact struc?ture, big carrying capacity, and assembly error of effecting on directing precision of spherical gear pointing mechanism. Based on the movement analysis and the meshing models of the mechanism, the directing error model of the mechanism was established. Influence of assemoly error on directing error of output shaft of the mechanism was analyzed and calculated. The studied results have guiding signifi?cance theoretically in practical application to the mechanism.

FEM Simulation on New Deep Drawing Process to Blank with Technique Holes

SHI Yu-qing, LI Ling-feng

2009, 30(7):  967-972.  doi:10.3969/j.issn.1000-1093.2009.07.024

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The new technique to improve forming property of sheet metal by a big margin was put for?ward. Mechanical characteristics of blank with holes during deep drawing were deeply analyzed, and the technical key to improve forming property of sheet metal was proposed, lading rectangular box with flange as example, the four finite element models (FEM) were established by ANSYS/LS-DY- NA software, the finite element simulations were performed by SHELL 163 element and Belystchko- Wong-Cmang algorithm, simulated results were compared among the four models. The compared re?sults show that the drawn forming by new process with the model (a) is very ideal.

Life Prediction of Spiral Bevel Gears for Starved Elastohydrodynamic Lubrication

YAN Yu-tao, SUN Zhi-Ii, WANG Yan-zhong

2009, 30(7):  973-977.  doi:10.3969/j.issn.1000-1093.2009.07.025

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Taking aim at starved elaslohydrodynamic lubrication (SEHL) of spiral bevel gears, the analyses of loaded tooth contact track, main curvature of contact point, and load distribution between teeth were performed by differential geometry and space surface mesh theory. By the theory of SEHL at elliptical contact system, the mathematic model and life predication model of SEHL for spiral bevel gears were established. By the analysis on the aviation spiral bevel gears concerning a certain helicopter transmission system, it was proved that the life predication model on SEHL of spiral bevel gears is valid, to provide an effective method for the life prediction.

Digital Finite Element Simulation of Gear Box Based on Explicit Dynamics

LI Chang, HAN Xing

2009, 30(7):  978-983.  doi:10.3969/j.issn.1000-1093.2009.07.026

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A precise parametric three-dimensional finite element model of some speed reducer was cre?ated based on involute profile equation and dedendum transition curve equation of master gear adopting APDL language. Digital simulation of the whole speed reducer working process was carried out in AN- SYS/LS-DYNA using contact impact algorithm to get accurate stress-strain variety and pressure distri?bution map of the gear-box during contact process. Rationality of the method was verified by compar?ing the calculated result of the method with that of the traditional Hertz one. Prediction and evaluation of dynamic characteristic of the gear box were realized by the method winch considers dynamic charac?teristic and interaction of every decelerator part comprehensively from systemic view. On the basis of the mentioned above consideration, influence of various original manufacturing errors on the gear box dynamic performance was considered to provide reliable theoretical basis for whole dynamic optimum design of the gear box.

Study on the Dynamic Characteristics of Spare Inventory Based on Markov Process

WANG Nai-chao，KANG Rui, CHENG Hai-Iong

2009, 30(7):  984-988.  doi:10.3969/j.issn.1000-1093.2009.07.027

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The dynamic characteristics of spare inventory under nonstationary demand were re?searched .The Markova state transition equation of spare consume distribution function was formulated and the function derivations of expectation ana variance of consumed spares with respect to time were obtained. On the base of above mentioned analysis result, the methods of calculating the expectation, variance and distribution function of consumed spares were given at arbitrary time point. Curves of the expected consumed spares (E(t)) and the expected back orders (EBO(t)) vs. time were plotted by numerical integral, influences of the demand rate and the turnaround time rate of the spares on E(t), EBO(t) were analyzed.

Research Notes

The Application of Active Disturbance Rejection Controller to Estimating Maneuvering Target States for Tank

QIU Xiao-bo, DOU Li-hua, HAN Jing-qing, ZHOU Qi-huang

2009, 30(7):  989-993.  doi:10.3969/j.issn.1000-1093.2009.07.028

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A new maneuvering target state estimating method was used in tank fire control system by using active disturbance rejection control (ADRC) theory. The target palstance is contributed to un?known disturbance, and ADRC was used to estimate the target state, compensate the disturbance and control the system to eliminate the influence of disturbance. The target state is estimated by extend state observer (ESO) and tracking differentiator (TD) of ADRC. Experiment shows that the method has better precision and rapidity performance than the old method which used palstance sensor and. Kalman filter.

The Application of Multi-Scale Sensor Fusion Algorithm to MEMS Gyroscope Data Processing

KE Xi-zheng, REN Ya-fei

2009, 30(7):  994-998.  doi:10.3969/j.issn.1000-1093.2009.07.029

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The people pay more attention to MEMS gyroscope for its low cost and convenience. How?ever, its zero-bias stability is still under development. It is steps of the multi-scale multisensor fusion algorithm that output signals of the gyroscopes are processed by the Kaman filtering; wavelet trans?forms of output data of the gyroscopes are performed, wavelet transform coefficients of output data are fused on the corresponding scale to obtain the wavelet transform coefncients of an integrated gyro?scope ;output signals of the integrated gyroscope can be reconstructed by using inverse wavelet trans?form. Fused results show that after doing multi-scale data fusion on the measurement result of N gyro-scopes, the zero-bias stability improves by one quantity level.

Real-Time Detection of Ship Hydrodynamic Pressure Field Signal Based on Autoregressive Model Filtering

JIANG Run-xiang, SHI Jian-wei, LIN Chun-sheng,GONG Shen-guang

2009, 30(7):  999-1003.  doi:10.3969/j.issn.1000-1093.2009.07.030

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On the basis of deeply analyzing large amount of the ship hydrodynamic pressure field signals and the sea wave hydrodynamic pressure field signals, the ship hydrodynamic pressure field signal was detected in real-time, effectively, from sea wave background by the autoregressive (AR) model filter?ing. It is detecting steps that an AR model of ocean wave hydrodynamic pressure iieid is established; the received signal is filtered by prewhitening filter structured with the AR model coefficients; the pre?diction error output from the prewhitening filter is smoothed and extracted as the characteristic value; the target signal is detected in real-time by a sliding detection method; the parameters of prewhitening filter are updated automatically if the target signal isn’t detected in a short time.The effectiveness of the method was verified by comparing the measured data with the simulated data. The verified result shows that the method is simple and easy to realize and can detect the target signal effectively in low signal-to-noise ratio.

Robust Attitude Control for Micro Air Vehicle Based on Sliding Adaptive Algorithm

DUAN Hong-jun, SHI Xiaoping

2009, 30(7):  1004-1008.  doi:10.3969/j.issn.1000-1093.2009.07.031

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Taking aim at a class of uncertain nonlinear systems, a sliding mode adaptive control algo?rithm based on Lyapunov ’ s stability theory was proposed. It is essence that ： the system is divided into nominal model and lumped disturbance term which is composed of modeling error, parameter uncer?tainties, disturbances and unmodeled dynamics. Coefficient of the system input with uncertain charac?ter is approached in real time by adaptive control, the lumped disturbance is reduced to an acceptant bound within finite time by robust control, the tracking errors of the uncertain nonlinear system are el- eminated ultimately by sliding mode control. The scheme has a good robustness for the uncertain non?linear system and overcomes the chattering in the control input of conventional sliding mode control. The attitude control of micro air vehicle was simulated. Simulation result shows the validity of the pro?posed method.