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2010 Vol. 36, No. 7

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Interaction between lunar rover wheel and simulant lunar soil by experiment
Sun Peng, Gao Feng, Yao Shengzhuo, Li Wen
2010, 36(7): 757-761.
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A tractive performance test-bed for wheel of planetary rover was designed and manufactured. Lunar soil simulation for wheel-soil experiment was prepared. Preparation of the lunar simulation on soil-bin was accomplished and mechanical properties of the in-situ lunar soil were remodeled. Tractive performance experiment for wheel of different lug types was conducted, based on which failure of lunar soil simulant and travelling resistance of wheel were analyzed. The results show that when increasing the wheel load, drawbar pull accordingly increase and the tractive efficiency show downtrend before uptrend. Drawbar pull also increase with the increase of lug height or lug number. In addition, there is little influence on the tractive performance while the wheel rotate speed changes among a lower range.
Quaternion unscented Kalman filtering for ultra-tight integration
Yuan Gannan, Zhang Tao
2010, 36(7): 762-766.
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Concerning the problem of the ultra-tightly coupled global positioning system/strapdown inertial navigation system (GPS/SINS) degraded in high dynamic and weak signal environments for linear filter, a quaternion unscented Kalman filter method was proposed. Firstly, analyzing the relationship between GPS and SINS of the ultra-tightly coupled GPS/SINS navigation system, an algorithm that using the SINS to estimate and correct the carrier signal of the GPS was derived, then the state and measurement equations was built. Secondly, concerning the problems of singularity and frequent parameter transformation for Rodrigus method, based on the multiplicative quaternion error model, a weighted averaging quaternion method that using the quaternion directly was proposed. Finally, the quaternion unscented Kalman filter method was proposed for the ultra-tightly coupled GPS/SINS navigation system. The simulation results indicate that the quaternion unsecured Kalman filter method is more robust to jamming and increases the position accuracy in high dynamic.
Micro-satellite attitude control real-time simulation based on mono-axis air-bearing table
Wang Xinsheng, Han Jianbin, Liang Bin, Li Jiyong
2010, 36(7): 767-770.
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Micro-satellite attitude control real-time simulation was studied based on the mono-axis air-bearing table, which was supported by a micro-satellite project. The hardware structure of the micro-satellite air-bearing table was introduced and the software architecture for the simulation system was described; Real micro-satellite attitude control system was analyzed. According to the mission requirements, the real-time simulation focused on the micro-satellite three-axis attitude stable controlling and the large angle attitude maneuver problem. The simulation results show that the micro-satellite attitude control scheme is implemented and the control precision is satisfied to meet the mission requirements. The feasibility and reliability of the micro-satellite attitude control scheme is also verified.
Torch pose fitting for intersection line welding robot based on fuzzy control
Wang Su, Miao Xingang, Li Xiaohui
2010, 36(7): 771-775.
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Torch pose is very important in welding intersection line which is a kind of complex space curve and needs all position welding. The fuzzy control arithmetic for torch pose fitting on saddle-back coping intersection line welding robot was designed. Weld slope, weld rotation, size of groove, intersecting cylinder thickness and intersected cylinder thickness were input variables. Working angle and walking angle which are determinant factors in torch pose were output variables. A multiple-input multiple-output fuzzy controller was built, the subjection function of input variables was planned, fuzzy control principle was designed by experience induction, and the relevant rule table was built. In order to distinguish the influence on output variables with different input variables, method of weighted was employed in the fuzzy expert system. Torch working angle and walking angle were fitted. Simulation of different diameter cylinder was made. The result shows that the fuzzy control system can achieve torch pose fitting effectively.
Wake vortex effect modeling and simulation in automated aerial refueling
Li Dawei, Wang Honglun
2010, 36(7): 776-780.
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According to the request of automated aerial refueling, the formation and distribution of wake vortex behind a large aerial tanker was discussed. A modified horseshoe vortex model that includes the effect of vortex descent and diffusion over time was given. This model was linearized nearby the mass point of the receiver and an averaging technique was implemented to compute effective wind on the receiver. The effective wind components and gradients were introduced into the nonlinear aircraft equations through aerodynamic equivalent to determine the effect on the receiver’s dynamics. Computer simulation of receiver/wake vortex encounters in aerial refueling was built by Matlab/Simulink. The results show that the wake vortex model can exactly describe the interference between the receiver and the tanker. This behavior is well matched with the feeling of the receiver’s pilot. This model can also be used for the flight safety about large aircraft during taking off and interaction analysis in tight formation flight.
Algorithm of identifying of AOI for vehicle based on video
Xu Guoyan, Wang Chuanrong, Gao Feng, Wang Jiangfeng
2010, 36(7): 781-784.
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The information of surrounding was gotten by the way of vision technology in intelligent vehicle system. It is very important to detcect other vehicles in front of the ego vehicle on road. The method of vehicle detection was proposed. The method of Ostu threshold was used to realize image binarization. Searching line may be the line of the shadow of vehicle-s bottom as the AOI-s (Area of Interest) bottom boundary. The expanding of the AOI was realized.The symmetry measurement and symmetry measurement of normalized entropy were used to determine whether the region is vehicle or not. The upper boundary was determined by checking the gray mutant line in the gray image. This method was tested, and got good results. The method paves the way for the latter distance measurement between vehicles.
Four-element relaxation matching algorithm of images based on known initial matching pairs
Wang Hua, Hou Xiangshen, Cong Jianting, Sun Jinwei
2010, 36(7): 785-788.
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A four-element relaxation matching algorithm based on known initial matching pairs was proposed. The algorithm with characteristics of anti-rotation and anti-scale of rotating angle of vectors was applied as the optimization criterion of matching pairs. Under the condition of higher initial error matching rate and larger walk errors, the algorithm achieved the matching correctly. The value difference of the rotating angle of vectors was calculated, and the optimal matching pairs was selected by using of the support function and the rules of rejection. Experimental results with large images show that the matching speed and correctness of the algorithm is better than Sangnong relaxation matching algorithm.
Material parameters in 3D finite element analysis of composite structure
Zhao Libin, Qin Tianliang, Li Jiaxi, Fu Yue
2010, 36(7): 789-793.
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The method to determine 3D composite material properties by means of engineering constants of composite lamina was summarized by investigating lots of existed literatures. The effect of uncertain variables in material parameters upon the stiffness prediction was researched by 3D numerical simulation and the corresponding experiments of composite π joint structure. Further, the initial failure of composite π joint structure was assessed by the modified maximum stress and strain, Tsai-Hu and Hashin failure criteria. The damage onset loads with different failure criteria and material parameter model were compared and the influence of material parameter model on the prediction of initial failure load and location was expatiated together with the experimental data. The research provides reference for numerical analysis of general 3D composite laminate structures. Moreover, it offers theoretical support for understanding mechanics behaviors and accurate strength prediction of composite π joint.
Formulation of routing performance based on routing salvage
Luo Xiling, Wang Miao, Liu Rui
2010, 36(7): 794-797.
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In a mobile Ad Hoc network, routing salvage is used to decrease routing overhead and ensure high delivery rate. The ratio of cached routes between the intermediate node and the determination to the total routes in the network was used to estimate the probability of the routing salvage from the breakage. Based on the routing salvage the formula for the routing overhead was advanced with time to live(TTL), and TTL is to eliminate the impact of expired routes. The optimal TTL was used to minimize the routing overhead. The simulation demonstrates: ①the formula for the probability of routing salvage is accurate compared with the simulation; ②routing salvage and TTL can cut down routing overhead and improve the delivery rate nearly 20%.
Helicopter slow switching attitude control based on multiple points inversion models group
Zhao Jia, Shen Gongzhang, Chen Shenggong
2010, 36(7): 798-802.
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Dealing with the deficiency of single point inversion model in traditional helicopter adaptive model inversion attitude control, a slow switching control method based on the multiple points inversion models group was proposed and the asymptotic stability condition was given. In the method, multiple points inversion models group was constructed to replace single point inversion model. Attitude error control system could be transformed into linear switched system, and attitude adaptive control could be achieved via the slow switching using dwelling time. Simulation results show superiorities of proposed method. Work burden of the adaptive element in the control method can be greatly alleviated and controller robustness could be promoted. The flight control system designed based the proposed method can maintain stable well during the switching processes, and also has strong performance robustness.
Flow field analysis and experimental investigation on gust generator
Liu Xiaoyan, Wu Zhigang, Yang Chao, Chu Longfei
2010, 36(7): 803-807.
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It is necessary to obtain the disturbance flow field characteristic of a gust generator beforehand in order to efficiently arrange experiment and analyze data. A variety of factors that had effects on the intensity and distribution of the gust were discussed based on a certain type of gust device, with emphasis on the vane amplitude, the oscillation frequency, the freestream speed, and the vane lateral spacing. The numerical simulation results show that the mentioned sensitive parameters influence gust intensity measured at points on the centerline more or less. The gust peak values at lateral sections downstream from the vanes have similar distribution shape, and vary linearly with the vane oscillation amplitude within a range of small angle of attack. Therefore, the anticipant gust intensity can be achieved expediently by adjusting the vane oscillation amplitude under the selected freestream speed and frequency. The wind tunnel experiment demonstrates that the performance analysis of the gust generator is of practical value.
Integrated methods for cabin noise control
Luo Guailin, Wang Jinjun
2010, 36(7): 808-811.
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When a domestic propeller aircraft was modified to an aerial testing platform, the cabin noise was too high to suffer. The characteristics of original cabin noise were tested in flight condition. The performance of various advanced noise descending materials were tested and compared in an acoustic laboratory. According to the noise speciality of propeller aircraft, a totally new anti-noise crease plate which can segregate noise and decorate the cabin was developed. To simulate and test the cabin noise of propeller aircraft authentically, a method called sound segregate performance test within noise reverberation chamber-noise elimination chamber was suggested. The combination effect of various noise descending materials was verified in an abandon section of fuselage. Based on the test result, the integrated methods for cabin noise control were determinated. Flight test of the modified aircraft shows that the methods are quite effective.
Friction compensation for hydraulic load simulator based on improved LuGre friction model
Yao Jianyong, Jiao Zongxia
2010, 36(7): 812-815.
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In order to acquire better performance and minimize the trace error, the friction mechanism was analyzed. As a novel friction description, LuGre friction model and its parameter had a few limitations, because this model is only the friction description of a fixed position. Synthesized on lots of friction experience and the characteristic of hydraulic fin actuator, a changeable maximum dynamic and static friction model, which is based on LuGre model, was proposed and identified. Using structure invariance principle, a compensator was designed and verified. Experience results show that the control strategy designed by the new friction model not only works well for rejecting torque trace error, but reveals excellent ability against extraneous torque.
Fuzzy guidance law for interception of exoatmospheric maneuvering targets
Tian Yuan, Wang Junbo, Ren Zhang
2010, 36(7): 816-820.
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The relative motion law between the target and the interceptor was analyzed when the divert thruster was on or off. An estimator of the interception ability was proposed based on the relative motion law. On-off conditions for the divert thruster were designed according to the shortest working interval of the divert thruster and the upper boundary of the line-of-sight rate that could be restrained. A novel terminal guidance law was proposed based on the estimator and the on-off conditions. The guidance law took advantage of the experts- experiences to construct the fuzzy rules and adjusted the on-off conditions of the divert thruster based on the relative range and the interception ability. A relay on-off method was utilized to control the divert thruster. The effectiveness and the performance of the fuzzy guidance law are demonstrated through the simulation in which the guidance law is applied to intercept two kinds of maneuvering targets.
Analysis and test of dynamic reaction of magnetic bearing reaction flywheel
Liu Qiang, Fang Jiancheng, Han Bangcheng
2010, 36(7): 821-825.
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Aimed at the magnetic bearing reaction flywheel rotor system, a novel model was proposed to describe the dynamic reaction of hybrid magnetic bearing (HMB). Based on Lagrange principle, the unbalance mass moments distributed in two planes were equivalent to the positions of two radial HMBs. Incorporated with the effect of centrifugal force caused by its principal axis of inertia, the dynamic reaction of HMB was obtained. Simulation result show that the rotation amplitude of rotor was significantly dependent on the phase difference, angular velocity and unbalance mass moment. When the values of two unbalance mass moments were equal, for the phase difference of 0, the amplitude was high, near 30μm. However, with an increase in the phase difference to π, the amplitude of rotor diminished down to 10μm. In addition, the vibration amplitude of rotor was 5μm at speed of 1000 r/min, which was lower than one at speed of 5000 r/min.Tests had a good agreement with the numerical simulations, which shows how to improve the precision and stability of system, by decreasing the vibration amplitude of flywheel rotor.
Optimal trajectory formation and control of human arm point-to-point movement
Sun Pengwei, Wang Shimin, Wang Qi, Fang Jie
2010, 36(7): 826-829.
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Optimal human arm trajectory formation was investigated on the basis of physiological characteristics of skeletal muscles and dynamic properties of contracting muscles, and a minimal effort criterion prescribed by isometric muscle contraction was proposed. The dynamic properties of contracting muscles were discussed and the dynamics of human arm was modeled. The arm point-to-point movement problem was converted to an optimal control problem by using the proposed criterion. According to optimal control theory, the iterative algorithm used to obtain the optimal trajectory was designed. The control laws and the time history of human arm movement were found. The results of numerical simulation indicate that the proposed criterion for the prediction of optimal arm movement trajectories is effective.
Temperature measurement and surface burn out in grinding 1Cr11Ni2W2MoV high-temperature stainless steel
Li Xun, Liu Jia, Chen Zhitong, Chen Wuyi
2010, 36(7): 830-835.
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The measuring method for the internal instant temperature and average temperature of grinding contact zone, as well as the correlation of the average temperature and burn extent in workpiece surface in the grinding process of high-temperature stainless steel (1Cr11Ni2W2MoV) were investigated, and the impact of the burn extent on the metallographic structure of workpiece surface was analyzed. In the process of grinding 1Cr11Ni2W2MoV using vitrified bond CBN grinding wheel, the internal instant temperature of grinding zone was obtained, the average temperature of grinding area proves to be direct influencing factor of the surface burn. Sufficient experiments under various grinding parameters prove that surface burn out only occurs when the average temperature exceeds 540℃, slight burn with yellow appearance occurs at 540℃ and gets more severe as the temperature increases. Meanwhile, surface burn out makes martensitic lattice turned into tiny annealing microcrystalline texture, and the thickness of microcrystal increases as the burn phenomena becomes more severe.
Effect of envelop thermal radiative properties on the stratospheric super-pressure LTA vehicle helium temperature
Liu Dongxu, Yang Yongqiang, Lü Mingyun, Wu Zhe
2010, 36(7): 836-840.
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Environmental radiations acting on a stratospheric super-pressure sphere lighter-than-air (LTA) vehicle were analyzed, including radiation heat and convection heat. LTA vehicle thermal model was established. Based on the thermal model, the thermal effects on the vehicle were analyzed which include sun radiation, earth albedo and radiation. The effect of thermal pertormance caused by different thermal radiative properties of envelope materials, such as absorptivity, emissivity and the ratio of absorptivity to emissivity was detailedly studied. The result shows that the material which has low ratio of absorptivity to emissivity is the better choice for the vehicle. If two materials have the same ratio, the material which has low absorptivity has better thermal control effect. The conclusion is significantly useful for stratospheric LTA vehicle design and material selection.
SAR image segmentation using level set evolution without prior information
Wang Xiaoliang, Li Chunsheng
2010, 36(7): 841-844.
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An SAR image segmentation method based on level set evolution without employing any prior information was proposed. The method was a statistical geometric active contour model in which region information was used. The step function was utilized to estimate the probability distribution function (PDF), so it was avoid to suppose a probability distribution model of images in advance, which required additional prior information. Further, a penalty term was introduced into the energy functional minimized by the level set evolution, then the costly re-initialization of level set function, which was also difficult to be implemented, was removed effectively. In addition, an iterated numerical scheme and the parameters setting were suggested, as well as the condition of terminating iteration was improved. Experiments demonstrate correct segmentation with proposed method and suggested parameters. For a few images whose segmentation is not well, correct segmentation can be achieved only by tuning one parameter simply.
Partially parallel decoder structure of multi-rate RS codes
Hou Yi, Liu Rongke, Zhao Ling
2010, 36(7): 845-848.
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To meet the requirement of using multi-rate RS(Reed-Solomon) codes in the communication system, a multi-rate partially parallel RS codes decoder architecture was presented. This decoder can be divided into three major blocks by its function: the syndrome computation block, the key-equation solver block and the Chien search and error evaluator block. According to the characteristic of the two RS codes specified in CCSDS standards, the syndrome computation cells of different code rates which have the same factor share the same hardware resources. A novel partial parallel architecture was used in solving the key-equation, which makes multiplexed units and non-multiplexed units operate concurrently, so as to reduce the waiting time in computation as well as improve decoding efficiency. In Chien search and error evaluator block, look-up tables were used to realize the multiply operation in Forney algorithm. Besides, multiplexed structures were used in inverse operation cells and Chien search cells in order to reduce the hardware resources. Using pin selection, two decoding modes, namely, RS(255,223) and RS(255,239) were supported. The synthesis result which is implemented in Altera-s FPGA devices indicates that the proposed multi-rate RS code decoder using 2981 logic elements and 9472 memory bits.
Error analysis of frequency estimation algorithm based on frequency offset correction
Wang Jiqiang, Ou Pan, Zhang Chunxi, Lin Zhili
2010, 36(7): 849-852.
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The principle of the frequency estimation algorithm based on frequency offset correction was presented. The computation formula of the frequency estimation-s standard deviation of a complex sinusoidal signal in white Gauss noise was obtained. The value of parameter m was optimized when the data length was  N, The algorithm can reach the minimum standard deviation when  m was the integer closest to  N/3. The Monte Carlo simulation results demonstrate that the algorithm based on frequency offset correction as the integer m is closest to  N/3 has lower standard deviation than the interpolation method with Hanning window and the phase difference method, while retaining a flat profile in the frequency range away from the fast Fourier transforms(FFT) discrete spectral line. The m-optimized algorithm-s standard deviation is less and closer to the Cramer-Rao lower bound(CRLB) than the one as m is the integer closest to N/2 when signal noise ratio(SNR) is higher.
Yield surface of transversely isotropic foams under axisymmetric loadings
Chen Wei, Lu Zixing
2010, 36(7): 853-856.
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The effective stress and mean stress description method for two-dimension (2D) materials was applied to obtain the formulae of characteristic mean stress, characteristic stress, and characteristic strain of three-dimension (3D) transversely isotropic materials under proportional axisymmetric loadings. Then the yield surface model expressed by characteristic mean stress and characteristic stress was established. Through the analysis of transversely isotropic face-centered cubic unit cell model by using finite-element method (FEM), the impact of cell aspect ratio on the elastic properties and the yield surface for transversely isotropic foams was also investigated. The results show that the increase of cell aspect ratio leads to the augment of longitudinal modulus, the decrease of transverse modulus and the anticlockwise rotation of yield surface. The model corresponds well with the modified Gurson-s model and the FEM results, and thus provides a new description for 3D transversely isotropic foams- yield surface.
Infrared LEO constellation design by GDE 3 algorithm
Wang Chunming, Chen Xi, Deng Yong
2010, 36(7): 857-861.
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Some guidelines about the design of infrared LEO(low earth orbit) constellation were analyzed and presented which involved location precision, space coverage and the constellation cost. And some indexes were defined to measure the performance of the constellation, such as the average efficient location precision, the N geometric coverage percentage and the N valid coverage percentage. Certain indexes could be used as some objective functions. The GDE 3 algorithm proposed could design and optimize the constellation. This method was based on Pareto optimal and could obtain a set of optimal solutions, thus it was adapted to solve the multi-object optimization problems. The simulation experiment was made by establishing the constellation model and designing the objective functions. Finally a constellation was selected from the results via a kind of multi-attributes decision. Compared with other constellation, much better performance was observed.
Design of optical-effectiveness analysis tool for satellite optical sensors
He Heng, Deng Jiati
2010, 36(7): 862-866.
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An optical-effectiveness analysis tool for satellite optical sensors was developed based on SolidWorks platform to improve efficiency and accuracy of the analysis. The tool was used to exam whether and when the sensors would fail due to optical problems during the satellite mission. Considerations about the optical-effectiveness analysis included: three levels of sensor effectiveness judgment: system effectiveness, group effectiveness and individual effectiveness; blinding: sensor would be blinded by satellite components or targets; light reflecting: sensor would be interfered by light reflected from planets or satellite components; motions: motions of targets, satellite body, satellite components and sensors. Software design solutions for these issues were proposed. The implementation principle for the effectiveness analysis function was introduced. And a five-step analysis process was presented: defining mission time, defining targets, defining component motions, defining sensors, and doing analysis. An example was used to demonstrate and validate the function of the tool.
Relativity between simulated and accelerated corrosion and natural environment corrosion
Li Xiaofei, Zhang Qi, Xiang Min
2010, 36(7): 867-870.
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On the basis of the Г.M. Gunyaev’s equation of average aging life, a study of the relativity between the simulated and accelerated corrosion and the natural environment corrosion for the carbon fiber/epoxy composite was carried out by using regression analysis method. The equation of average aging life of the residual interlaminar shear strength of the natural environment corrosion specimens was determined, and the equivalent relation between the simulated and accelerated corrosion and the natural environment corrosion was obtained. The analysis of the surface and fracture morphologies of the carbon fiber/epoxy composite specimens further reveals that the corrosion mechanism of the simulated and accelerated corrosion is similar to the natural environment corrosion.
Weighted Q control chart based on difference-declining weight parameters
Zhu Lingxian, Zhou Bosheng, Luo Wenjie
2010, 36(7): 871-874.
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To solve the problem that the ARL (average run length) of Q control chart was much longer than the ARL of control chart with known distribution parameters, the weighted Q control chart was proposed. The method to deal with one-volume-sample metric and the method to deal with multiple-volume-sample metric were both given. The mathematical justification of the method to deal with one-volume-sample metric was given. The Q statistic that the weighted Q control chart used was established by difference-declining weight parameters. The simulation shows that the ARL of the weighted Q control chart is shorter than the ARL of Q control chart and is comparably short to the ARL of control chart with known distribution parameters. Because distribution parameters can not be known in most processes, the weighted Q control chart is better than Q control chart and also better than control chart with known distribution parameters when both of practicability and sensitivity are considered.
Ambient occlusion in screen-space for mesostructure objects
Liu Duoli, Wang Lili, Yang Zheng, Zhao Qinping
2010, 36(7): 875-878.
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The objects with mesostructure surfaces have complex model structures, which result in low efficiency of ambient occlusion algorithms. To improve the rendering speed, a screen-based ambient occlusion method was proposed. By using off-screen technique, only the points which can be seen were to determine the occlusion. The algorithm has two render passes: First, the depth texture of the whole scene was obtained; At second pass, the effect of ambient occlusion could be quickly computed by finding the maximum of the block angle. The ambient occlusion of the whole scene could be rendered by the deferred shading technology. The algorithm runs entirely in image space, and uses graphics pipeline to show the ambient occlusion effect of deformable objects in dynamic scenes. Experimental results show that the proposed method is more efficient than the available methods, as this method doesn-t need any pre-processing, and the time used for ambient occlusion determination is less.
Disturbance modeling and parameters identification of reaction wheel assembly on spacecraft
Zhang Pengfei, Cheng Wei, Wang He, Zhao Yu
2010, 36(7): 879-882.
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An improved disturbance model was proposed to predict the effects of reaction wheel assembly (RWA) micro-disturbance on the spacecraft. Because the disturbance amplification by excitation of the structure modes was the most dominating effect on spacecraft attitude accuracy by RWA, the improved model expressed the effect of the structure-s nature frequency to disturbance by introducing amplification coefficients. As the nonlinear characteristic of improved model, simulated annealing genetic algorithm was used to identify the parameters of improved model. A rigid six-axis test bed was designed, and the disturbance of RWA was measured. The improved model as well as the results of parameters identification was validated by experimental data. The experimental results show that the improved model captures the disturbance characteristic precisely, and simulated annealing genetic algorithm can improve the identification accuracy.

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