2002 Vol. 28, No. 3

Display Method:
Research on Global Vision System for BioengineeringOrientedMicromanipulation Robot System
LI Xu-dong, ZONG Guang-hua, BI Shu-sheng, ZHAO Wei
2002, 28(3): 249-252.
Abstract:
A micro-vision system was presented to meet the requirements of micromanipulation in the field of bioengineering. A correlation based pattern matching algorithm and a morphological method, which can be realized in the form of easy-fast-implemented discrete convolution, were employed to track at least 3 targets simultaneously and to calculate their image coordinates. The coordinates were used as feedback message to realize visual-servo control. Testing results proved that the vision-servo control could effectively improve the control quality. This implies that the vision system can meet the stringent needs of real time control.
Actualization of 1/f filter and Analysis of Pleasant Feeling
MAO Xia, ZHU Gang
2002, 28(3): 253-256.
Abstract:
In order to get comfortable and natural wind, a method which make power spectrum of wind-s velocity conforms to 1/f fluctuation is mentioned. Data conforming to 1/f fluctuation by using 1/f fluctuation filter controlled the velocity of motor using a booster. By the comparison among feelings got by wind of the 1/f fluctuation, that of the 1/f2 fluctuation and that of the white noise fluctuation using variance analysis, a conclusion is drawn that humans- feeling of comfort is implemented efficiently by 1/f fluctuation controlled electric fan.
Reconfiguration of Control Surface Faults with Thrust Vectoring Technique
ZHANG Ping, CHEN Zong-ji
2002, 28(3): 257-260.
Abstract:
The compensating effect of thrust vectoring technique on aerodynamics of an aircraft in its pitch and yaw motions was discussed. Attention was focused on how to realize reconfiguration of the control law with thrust vectoring technique when any failure of the control surface appears in flight.Definition of control redundancy and sufficient conditions of Pseudo inverse reconfiguration were given. An example of rudder fault of the aircraft was illustrated, satisfactory reconfiguration results were obtained with the above technique.
Cost Function Based Map Matching Algorithm for GPS/DR Integrated Navigation Systems
PENG Fei, LIU Zhong-kan, ZHANG Qi-shan
2002, 28(3): 261-264.
Abstract:
Map-matching is an effective way of improving location accuracy of vehicle location and navigation systems. By analyzing the application of map-matching method in GPS/DR integrated navigation systems, a GPS/DR/Map-matching integrated system model and a cost function based probabilistic map-matching algorithm are proposed. Emphasis was put on how to eliminate the ambiguity in finding map-matching resolution by evaluating a cost function for each correction over time. Simulation results show that, by introducing this algorithm, the positioning performance of integrated navigation system can be improved significantly.
Method for Structured Light Based 3D Vision InspectionBased on RBF Neural Network
LI Xin, ZHANG Guang-jun, WEI Zhen-zhong
2002, 28(3): 265-268.
Abstract:
Based on Radial Based Function (RBF) neural network, a method for structured light based 3D vision inspection is presented. The method uses RBF ANN (Artificial Neural Network) to establish the mapping relationship between a real object in the wold and its image captured by CCD camera, i.e., the mapping relationship between frame coodinate and its image coodinate. Compared with common methods, the preset approach ignores the vision model error, and allow the existence of optical adjust error. By overcoming disadvantages of common methods efficiently, higher measuring accuracy can be obtain.
Theoretical Model to Predict Reynolds Stresses in Near Wall Region of a Turbulent Boundary Layer
LU Li-peng, GONG Hui-min, ZHANG Jian-qiang, CHEN Ma
2002, 28(3): 269-271.
Abstract:
A symmetric resonant-triad theoretical model was proposed to describe the turbulent coherent structures in the near-wall region of a turbulent boundary layer. Based on this model, the Reynolds-stresses were calculated, their production rates, dissipation rates and transport were evaluated. Consistence of the present results with DNS suggests that the aforementioned theoretical method could reasonably embody the physical mechanism of near wall region turbulence, giving a possibility of modeling the near-wall turbulent flow with the knowledge of coherent structures.
Design and Implementation of Gateway Supporting MultiProtocol and MultiUser for GPS/GSM Supervisory System
TAO Hai-liang, ZHANG Qi-shan
2002, 28(3): 272-275.
Abstract:
Gateway design is crucial for developing a GPS/GSM supervisory system with satisfactory system performance, availability and expandability. Several related key techniques for gateway design were dealt with. After analyzing different Short Message Service Center (SMSC) interface protocols, a protocol manager was introduced to achieve multi-protocol capability. Custom communication instruction format was proposed. The address conversion procedure was discussed in detail. Advantages of multi-thread and message driving in software architecture were also presented. The reliability of the gateway design strategy was proved by a practical implementation with the proposed techniques.
Equation for Grinding Ball Nose Mill in the Five Axis Machine
CHEN You-dong, FAN Rui, CHEN Wu-yi, CHEN Ding-chang
2002, 28(3): 276-279.
Abstract:
Closed form equations for kinematic variables that control motions in a LLLRR five-axis machine were developed using a kinematic closed loop link mechanism model based on the principles of Denavit-Hartenberg 4×4  transformation techniques. These equations developed here can be used to grinding the ball nose mill on the five-axis machine. Details of the equations for grinding the rake face and flank face of the ball nose mill were presented. Conical grinding wheel produces rake face and cylinder face grinding wheel forms flank face. The equations are simply enough to be solved on line with a computer.
Investigation of the Controlling Effect Magnetic Distribution in Electrical Arc Running Channel on Arc Interruption
YUAN Hai-wen, LI An-yun, LI Rong-yuan
2002, 28(3): 280-282.
Abstract:
Plane parts will be powered electrically more and more in the coming future, development of aero-electrical apparatus becomes the basis of this tendency. Three kinds of electrical arc quenching models were designed for uses with 270 voltage direct current network sources. Based on the experimental and calculation results, It was found that the magnetic distribution in electrical arc running channel can be used to control electrical arc interruption effect under serious network source fault.
Design of a Cooling Package for Environmental Control in a Helicopter
YANG Qian, CHANG Shi-nan, YUAN Xiu-gan
2002, 28(3): 283-286.
Abstract:
A simplified air cycle cooling system scheme for environmental control system in a helicopter is presented. Attention is focused on the design and matching of heat exchangers. By constructing the environmental control system and calculating the resistance of the system, the feasibility of the scheme is demonstrated.
Approach for Adaptive Filter of Systems with Random Changing Structures
WU Sen-tang, ZHANG Shui-xiang, CHEN Hai-er
2002, 28(3): 287-290.
Abstract:
An approach was given for adaptive filter of systems with random changing structures containing correlative or non-correlative characteristic parameters. An improved bootstrap filtering algorithm based on random sampling, which adapts quite well to the nonlinear/non-Gaussian problems, was adopted to avoid "basic structure distortion" caused by conventional filtering algorithm and to increase the estimation precision of the total filtering algorithm. Simulation results about missile guidance problems where measurement information is randomly interrupted in "twinkling" noise environment proved the validity of the approach.
Simplification of Reaction Mechanism of Turbulent Combustion
JIANG Xue-li, LIU Tao
2002, 28(3): 291-294.
Abstract:
Chemical reaction mechanisms of turbulent non-premixed carbon monoxide/hydrogen and methanol bluff-body flame were simplified by rate sensitivity analysis method. By identifying the redundant species and unimportant reactions, the reaction kinetics was reduced greatly. Computational results of the reduced mechanisms exhibited good agreement with those of the detailed ones. This proves that the rate sensitivity analysis method can be used to reduce the complicated turbulent reaction mechanisms effectively and at a satisfactory precision.
Numerical Simulations of High Temperature Molten Salt Phase Change Heat Storage System
XING Yu-ming, CUI Hai-ting, YUAN Xiu-gan
2002, 28(3): 295-297.
Abstract:
Numerical calculations were performed for a high temperature phase change thermal energy storage tube system of space station heat receiver ground test demonstration. The output power of sun simulator, the exit temperature of cycle working fluid and the wall temperature of the phase change material containers were calculated. These results showed that the receiving/releasing heat performance of the thermal energy storage tube meet design requirements.
Driving Technology of the Light Source of FOG
ZHANG Xi, WANG Yan, ZHANG Chun-xi, WANG Jin
2002, 28(3): 298-300.
Abstract:
For the purpose of improving precision and practicability of fiber optic gyroscope(FOG) , a current source and a temperature control circuit were designed for driving the light source of FOG. Considering the characteristics of the FOG, a scheme of controlling the driving current by the feed back light from the coupler and detector of FOG was discussed. The testing results indicated that, in a temperature range of -20℃ to 55℃, the present technology can yield a current precision as high as 0.06%, a temperature control precision of 0.1℃, and a variation of light power less than 0.1%.
System Used for the Examination of Processing Aircraft Sheet Metal Parts Based on Database
DONG Zhi-ping, LI Xin-jun, WAN Min, ZHANG Ping
2002, 28(3): 301-304.
Abstract:
The importance of using database and computer aided analysis technology in the examination of processing aircraft sheet metal parts was put forward by analyzing the actuality of technology design for aircraft sheet metal parts. The general structure and realizing scheme of the process examination system were analyzed based on the aviation sheet metal forming database (Ashbase), and the key techniques and solution methods in establishing this system were studied. By using this system, forming performance of the sheet metal parts can be examined with high efficiency and precision.
Interference-Free Toolpath Generation of Rotationally Free Surfaces in Four-Axis NC Machining
WU Li-ping, SHI Fa-zhong, CHEN Wei-dong, ZHU Xin-xiong
2002, 28(3): 305-308.
Abstract:
Four-axis NC machine tools with rotation table are most suitable for the machining of rotationally complicated compound free form surfaces. To solve the interference problem in four-axis NC machining, the guard surface concept widely used in 3-axis machining was introduced into four-axis NC machining, corresponding guard surface calculating method was presented. Based on offset surface model, an algorithm of interference-free toolpath generation in four-axis machining was developed. Case study showed that the algorithm works well on PC platform. A brief review on problems to be further studied was also given.
Synthesis of Predictive Directing Signals in Terrain Following Operation Task of Rotorcraft
WANG Liang, WANG Zhan-lin, LIN Yan-zhi
2002, 28(3): 309-311.
Abstract:
In order to improve the pursuit property of flight by pilot and to relax pilot's workload, the structure and realization methods of predictive directing signal synthesis were proposed. With the realization of these methods, pilot can use gain plus time delay control characteristics and fulfill high quality tracking flight task under the display of predictive operation signal. In the predictive directing signal synthesis research for rotorcraft terrain following task, a method to eliminate the coupled effect of airspeed loop through coupled disturbance observer design was also proposed. The validity of these methods were demonstrated by simulations.
Flight Director Signal Synthesis for Landing Approach Operation Based on Optimal FCZPETC
WANG Liang, LIN Yan-zhi, WANG Zhan-lin
2002, 28(3): 312-315.
Abstract:
Features of flight director design were analyzed. Considering the roles of preview information in improving pursuit flight property and compensating pilot's time delay, a new method for flight director signal synthesis with preview information was proposed based on zero phase error tracking control. Application features of the method and the improvement in approaching pursuit were demonstrated through simulation results
Novel Neural Networks Control Approach of Flexible Manipulators
WU Li-cheng, LU Zhen, YU Shou-qian, ZHENG Hong
2002, 28(3): 316-318.
Abstract:
A novel neural networks control approach for manipulator with flexible end link was proposed. The manipulator with flexible end link was regarded as two parts: the flexible latter part that includes the last joint and the last link, and the rigid former part that is composed of the rest elements. In the proposed approach, a conventional model-based controller was used to control the rigid former part, a neural network was used to approximate the dynamic anti-model of the flexible latter part. Combined both together, the proposed approach achieved fine control effect in the emulation of a three links planar manipulator with a flexible last link.
Effect of Drilling Processes on Surface Integrity of 7075Aluminum Alloy Holes
PEI Xu-ming, CHEN Wu-yi, REN Bing-yi, HAN Yu
2002, 28(3): 319-322.
Abstract:
Effect of the five drilling processes on the surface quality of fastening holes of 7075-aluminum alloy plate used in aircraft structures was investigated with the respect of surface integrity. By measuring and comparing of surface roughness, residual stress and micro hardness, it was found that the surface integrity of holes obtained by multiple-step machining with slow feed and byone-step compound machining were superior to that obtained by the other three drilling processes. In addition, factors influencing surface conditions were analyzed, and it was proved that one-step compound machining was an advanced and fast drilling method with high quality.
Stiffness Matrix Method for Displacement Analysis of Fully Spatial Compliant Mechanisms
YU Jing-jun, BI Shu-sheng, ZONG Guang-hua
2002, 28(3): 323-326.
Abstract:
Because of spherical joints existed in some spatial mechanisms, the pseudo-rigid-body model method extensively used in the analysis and design of a compliant mechanism with only revolute flexure joints was very limited in analyzing its kinematics. An expanded pseudo-rigid-body model method named as stiffness matrix method was presented to conduct the displacement analysis of fully spatial compliant mechanisms. Take a 6 RSS mechanism for instance, the stiffness matrix of the general flexure hinge was established by using the displacement matrix method in structural analysis. Through the transformations of a series of coordinate systems, force balance equations of nodes and end effector of the mechanism, deformation cooperation equations and close loop displacement equations of the mechanism were derived. On the above basis, displacement analysis of the mechanism was conducted with the stiffness matrix method, giving a relatively higher accurate solution by considering elastic deformation of all the mechanical members.
Design and Analysis of the Experiment of Human Two-Dimension Target-Aiming Movement
LIU Wei, YUAN Xiu-gan, YANG Chun-xin, WANG Li-gang
2002, 28(3): 327-330.
Abstract:
A two-dimension experiment of target-aiming movement was designed and conducted. Valuable data were obtained. On the above basis, a new mathematical model of human two-dimension target-aiming movement was proposed, corresponding experimental coefficients were determined. Experimental data indicated that the new model has an excellent suitability and a higher precision, This model is applicable for one and two dimensions target-aiming movements of hand and other limbs in the air or even under water.
Robust Strict Positive Realness Synthesis for Uncertainty Systems with LMI Approach
ZHANG Gao-min, JIA Ying-min
2002, 28(3): 331-334.
Abstract:
This paper is devoted to synthesizing a stabilizing feedback controller for a linear time-invariant plant with norm-bounded uncertain coefficient matrices so that the corresponding closed-loop system is robustly strictly positive real. Quadratic strict positive real system is defined first. Necessary and sufficient conditions for the system to be quadratic strict positive real are then established. Finally, state-space formulas for the state feedback controller are given in terms of solutions to linear matrix inequalities. The feasibility of the proposed method is confirmed by a numerical example.
Prediction of Axial Longitudinal Shear Modulus of Multiphase Fiber Composites
WANG Xiao-jun, TONG Zhong-hua, JIANG Chi-ping
2002, 28(3): 335-338.
Abstract:
A generalized self-consistent model to predict the effective longitudinal shear modulus of multiphase fiber composites was developed, by considering the effect of fiber section shape. In the model, combined confocal elliptical cylinder unit cells are embedded in an infinite homogenization composite. By using conformal mapping technique and Laurent series expansion, a close form solution was obtained. Further a group of algebraic equations to predict effective longitudinal shear modulus of multiphase fiber composites were obtained by virtue of the averaged stress-strain theorem. When the shear moduli of all fibers are same, the above equations can be reduced to those for single phase fiber reinforced composites. The validity of the proposed model was verified by comparing present theoretical predictions with available experimental results.
Numbering of Finite Element Mesh Nodes
OUYANG Xing, CHEN Zhong-kui, SHI Fa-zhong
2002, 28(3): 339-342.
Abstract:
In finite element analysis, the storage needed by a total stiffness matrix for solving a large-scale system of linear equations is related to the sequenace determined by numbering of mesh nodes. Based on the solutions for both constant and varible bandwidth storages, their relationship is derived. On the above basis, the frontal method and rectangle method are proposed, the relationships between memory spending for both methods and amount of nodes are given. Theoretical analyzing and practical examples have proved that the two methods can efficiently decrease the memory spending of computer.
Physical Meaning of Dyadic Shift in the Theory of Walsh Functions
ZHANG Qi-shan, WANG Gang, JIN Ming-lu
2002, 28(3): 343-345.
Abstract:
The concept of dyadic shift plays an important role in the theory of Walsh functions, its physical meaning is however not get clear. To get a clear understanding of the physical meaning of dyadic shift, some basic concepts of copy theory are briefly introduced first. On the above basis, it is revealed by discussing the position correlation of copy sequences that dyadic shift is in fact a special distance.
Waveform Fuzzy Logic Control Method Used in CO2 Gas Metal Arc Welding
ZHANG Jun-hong, WANG Hong-fang, HUANG Shi-sheng
2002, 28(3): 346-349.
Abstract:
A waveform fuzzy logic control method used in CO2 gas metal arc welding was proposed in order to get stable arc length with constant current output characteristics. Working principle of the waveform control system was presented and designing procedures of a fuzzy logic controller were provided. Experiments with the above method were conducted. The results indicated that the proposed method works satisfactorily, giving rise to an excellent comprehensive technological performance. The performance includes a stable welding process, few spatters and a good bead formation.
Generalized Fracture Constant Life Curve and Two Dimensional Probability Distribution of Fracture Threshold Value
XIONG Jun-jiang, GAO Zhen-tong
2002, 28(3): 350-353.
Abstract:
Based on fatigue constant life curve, the concept and the universal expression of a generalized fracture constant life curve are presented to determined the two-dimensional probability distribution of the fracture threshold value,by victue of the clear physical significance of the expression and the reasonable relation between the mean and the amplitude of the fracture threshold value. With the optimization method of the correlation coefficient, the parameter estimation formulas of the constant life curve are induced,the generalized fracture constant life p-ΔKth-Kmth curve with the reliability level p is given. From p-ΔKth-Kmth curve, the two-dimensional probability distribution of the fracture threshold value is derived. Then, LY11 and 40CrNiMoA are respectively tested under three different average stress, the aforementioned method is applied to analyze the test results,and it is found that a high precision is obtained with the above approaches.
Operational Effectiveness Analyses of AirtoGround Strike for BattlePlane
HUANG Jun, SUN Yi-dong, WU Zhe, HUAI Jin-peng
2002, 28(3): 354-357.
Abstract:
Taking advantage of Markov process theory and considering synthetically a good many elements of an air-to-ground striking mission, the battle scenario and the mathematical models for the air-to-ground strike actualized by a battle-plane were set up. Through analyses on the combat survivability, the striking capability and the employed tactics of the thrown out battle-plane, alongwith the analysis on the physical characteristics and damage mechanism of various air defense weapon systems in the battle field, the time related operational effectiveness measurements of mission success rate, target killing rate and battle-plane loss rate were evaluated. The optimal combat time was also correlated to the cost. An example calculation for the operational effectiveness of a battle-plane in the postulated air-to-ground scenario was presented. The results indicated that the established models and the associated analysis efforts can objectively describe the essential of an air-to-ground strike combat.
Control Strategy and Implementation for Acquiring C/A Code of High Dynamic GPS Signals
LUO Xing-yu, ZHANG Qi, CHANG Qing
2002, 28(3): 358-361.
Abstract:
It is necessary to design acquisition and tracking system for code loop and carrier loop in order to detect high dynamic GPS signals. Acquiring signal quickly and shortening acquisition time in the cold case are the key technologies of high dynamic GPS receiver. Moreover, fast acquisition of C/A code is the base of code tracking and carrier acquisition and tracking. This paper describes elements and implementation of parallel search precept and sequential search precept to acquire C/A code of high dynamic GPS signal. And combined with a 12-channel correlator named GP2021 produced by GEC Co., the arithmetic implementation to acquire C/A code of high dynamic GPS signal used sequential search precept based on DSP technology is also given.
Analysis on Droplet Trajectories of an Engine Inlet
YANG Qian, CHANG Shi-nan, YUAN Xiu-gan
2002, 28(3): 362-365.
Abstract:
Trajectories of water droplets were studied to provide information for anti-icing system design of inlet of an engine. Based on the calculation of flowfield around the inlet, numerical results of the motion equations for the droplets were presented by using difference method, and the droplet trajectories were obtained for a variety of flight conditions. Then, the impact range on the inlet surface, the total collection efficiency, and the local collection efficiency were determined. In addition, the effects of flight height, flight velocity, and radius of water droplet on droplet trajectories were also investigated. It was found that the impact range, the total collection efficiency and the local collection efficiency all increase with decreasing of flight velocity, increasing of droplet size or flight height. At the same time, the reasons of these results were analyzed.
Structure Optimization of Finned Tube Lubricate Heat Exchangers Used in Helicopters
LI Lin, YU Jian-zu, ZHU Qi-zhao, CHANG Li
2002, 28(3): 366-369.
Abstract:
Basing on numerical optimization principles and thermodynamic performance design, efforts were made to optimize the design of finned-tube lubricate heat exchangers used in helicopters. By taking the weight of the lubricate heat exchangers as an objective function, using the sine method to deal with design constrains, and selecting the simplex accelerated method to search optimization results, optimization design program was developed for the exchangers. An example was given to show that optimum design requirements can be realized by coupling the structure optimization program with the thermodynamic performance design program.
Method to Get the Forward Solution of a 6-SPS Parallel Manipulator Based on Position Tracking Principle
HAN Xian-guo, CHEN Wu-yi, CHEN Ding-chang
2002, 28(3): 370-372.
Abstract:
A predictor-corrector method to get the forward solution of a 6-SPS parallel manipulator was presented based on the principle of position tracking. By solving the initial value problem of the positional differential equation of the parallel manipulator, not only the position of platform can be determined when the lengths of six legs were specified, but also the transition positions between the two specified leg lengths can be determined. Effectiveness and speediness of the proposed method was demonstrated by simulation results.