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2016 Vol. 42, No. 6

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Volume 42 Issue62016
2016 Year 42 Volume 6 Issue E-journal
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SVM fault diagnosis of autopilot based on quantum inspired gravitational search algorithm
LI Haitao, HE Yuzhu, SONG Ping
2016, 42(6): 1093-1098. doi: 10.13700/j.bh.1001-5965.2015.0417
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With regard to the lack of the sample of faults in the test of autopilot, a model of fault diagnosis based on support vector machine (SVM) optimized by quantum inspired gravitational search algorithm is put forward. SVM does well in solving the few samples and nonlinear problem, which is suitable for the fault diagnosis of autopilot. To improve the convergence rate and accuracy of parameters optimizing based on gravitational search algorithm (GSA), quantum inspired gravitational search algorithm (QGSA) was applied to optimizing the parameters of SVM. SVM based on QGSA can solve the overfitting and underfitting resulted from the improper parameters. By this way, a model of fault diagnosis with better performance was built. The simulation experiment results show that the accuracy of SVM based on QGSA can achieve 96.530 6% using 50 training samples. However, the accuracy of genetic algorithm (GA)-SVM achieves 92.040 8% and the accuracy of SVM based on GSA achieves 91.632 7%. The simulation experiment results shows that SVM based on QGSA has much better performance than others.
Effect of air cooled spraybar heat insulation sleeve height on performance of mixer and diffuser
LIU Youhong, ZHOU Kaifu, NIU Junjie
2016, 42(6): 1099-1106. doi: 10.13700/j.bh.1001-5965.2015.0425
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For the mixer and diffuser of air cooled spraybar rod, the three-dimensional numerical simulation model based on the Navier-Stokes equation was created. Through numerical simulation, the principle of the effect of different air cooled spraybar heat insulation sleeve heights on the mixer and diffuser integration aerothermodynamic performance of flow fluid, flow resistance characteristics and mixing characteristics was obtained. The results show that air cooled spraybar heat-insulation-sleeve height has little effect on the thermal efficiency of the mixer and diffuser, and that the overall range of variation is less than 0.008. The static-pressure recovery coefficient declines as the air cooled spraybar heat-insulation-sleeve height increases; the flow resistance and pressure loss coefficients of the mixer and diffuser increase with the growing height of air cooled spraybar heat-insulation-sleeve. At the outlet section of the mixer and diffuser, the total-pressure recovery coefficient declines as the air cooled spraybar heat-insulation-sleeve height increases, and the total variation range is small andreduced from 0.991 1 to 0.990 7.
Integrated single X-ray pulsar and starlight navigation based on virtual observation value
YANG Bo, HU Shengman, SUN Hui, XU Fan
2016, 42(6): 1107-1115. doi: 10.13700/j.bh.1001-5965.2015.0422
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Conventional X-ray pulsar navigation satellite system needs to observe 3 to 4 pulsars at the same time, thus the mass and consumption of the payload will increase. Therefore, the technology using single detector is the key measure to realize X-ray pulsar navigation. In order to solve the problem of poor visibility and low accuracy of X-ray pulsar navigation with single detector, we propose a high accuracy navigation integrated with single X-ray pulsar and starlight navigation based on the centralized Kalman filter using virtual observation value of the pulsar navigation. During the long period of detecting X-ray pulsars, the starlight virtual observations observed at the same time will be added when detecting starlight's observations, so that it can achieve high precision using the centralized Kalman filter within shorter period. Meanwhile, this paper proposes a method using neural network to predict the virtual observation, and compared with the prediction using dynamic method, it can achieve a high order magnitude of 10-7. The results of the simulation show that the method can greatly improve the reliability of the single detector navigation by compensating the navigation error caused by the error of detector the navigation positioning error is 259.79 m, and it can effectively reduce the weight of the navigation system. This can provide reference for the engineering implementation of X-ray pulsar navigation.
Omnidirectional true proportional navigation: Novel guidance law for interception of high-speed targets
BAI Guoyu, SHEN Huairong, LI Yuan, YAN Liang
2016, 42(6): 1116-1125. doi: 10.13700/j.bh.1001-5965.2015.0377
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Aiming at the interception of high-speed targets, a new interception guidance law called omnidirectional true proportional navigation (OTPN) was proposed, which adapted to variable-speed interception and can automatically shift interception mode, possessing both head-pursuit and head-on interception capabilities. This guidance law has a wide capture range and can meet the need of omnidirectional interception guidance of high-speed targets. It is found that there are two crack points which meet success conditions in interception guidance of proportional navigation. The signs of navigation ratio for the two crack points are inverse, which leads to the different intercept modes of head-pursuit or head-on interception. In the proposed guidance law, the initial conditions are relaxed through the sign alternating of navigation ratio, and the acceleration limitation was considered as well. The results of numerical simulation verify the validity and effectiveness of OTPN guidance law. Compared with interception simulation of other guidance schemes, under the same intercept conditions, the parameters of capture region, intercept time and control efforts are all superior to those of classical proportional guidance law and retro-proportional guidance law. The major factors influencing interception and capture capabilities of OTPN, such as the maximum acceleration and the value of navigation gain were also studied through capture ability simulation.
Vertical profile planning method for general aviation flight in complex multi-constraints conditions
WANG Xiaoliang, MA Yabing, WANG Peng, WU Renbiao
2016, 42(6): 1126-1133. doi: 10.13700/j.bh.1001-5965.2015.0450
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A method for trajectory planning based on improved A-star algorithm is presented, which can be used for solving the problem of vertical profile trajectory planning for general aviation aircraft in complex multi-constraints conditions. Firstly, according to the characteristic of low altitude flight for general aviation, a mathematical model is established considering multi-constraints conditions, such as flight mission, terrain information and aircraft performance parameters. Secondly, vertical profile trajectory planning space is constructed, and trajectory cost model is established with a weighted objective function. Finally, the vertical profile planning trajectory is generated through improved A-star algorithm, which can be utilized to satisfy the complex multi-constraints conditions. Experimental results indicate that the improved A-star algorithm has much better performance compared with traditional route planning algorithm and the proposed improved A-star algorithm could solve the vertical profile trajectory planning for general aviation in complex multi-constraints conditions successfully.
SVRM-assisted soil moisture retrieval method using reflected signal from BeiDou GEO satellites
YANG Lei, WU Qiulan, ZHANG Bo, LIANG Yong, HONG Xuebao, ZOU Wenbo
2016, 42(6): 1134-1141. doi: 10.13700/j.bh.1001-5965.2015.0656
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We propose a support vector regression machine (SVRM)-assisted soil moisture retrieval method using the reflected signal from BeiDou geosynchronous orbit (GEO) satellites. This method uses a right hand circular polarization (RHCP) antenna and a left hand circular polarization (LHCP) antenna to gain the direct and reflected signal's power data from the BeiDou GEO satellites, respectively. Furthermore, it uses the direct and reflected signal power, BeiDou GEO satellites' elevation angle and azimuth angle as the input features and uses the soil moisture data which is obtained by oven-drying method as the output target of the ε-SVRM which uses a radial basis function (RBF) kernel function. The collected data is separated into two sets randomly:one as training set and the other as test set. The test results show that the error between retrieval model's prediction and the value of oven-drying method is less than 3%; the regression coefficient of determination is 0.897 9; the root mean square error (RMSE) is 1.492 6%, which proves that this method has good generalization ability and the practical results meet the application requirement.
Sensor placement method based on bond graph models
LING Mu, YUAN Haiwen
2016, 42(6): 1142-1148. doi: 10.13700/j.bh.1001-5965.2015.0400
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In order to study the influence of sensor placement on fault diagnosis, a new sensor placement method based on bond graph model was proposed. A group of virtual sensor test points were set in bond graph model, then the information of bond graph structure and causality constraints were used to deduce a set of analytical redundancy relations, namely system residuals. The relationships among residuals,faults and sensor placement configuration were analysed,and this sensor placement method can meet the requirements of system fault detection and isolation performance. The sensor placement configuration with the minimum number of sensors was chosen under the premise of maximizing system diagnosis performance. Finally, the synchronous generator was used as an example to establish the sensor placement algorithm. Residual analysis was used to derive the structure fault feature matrix and the sensor feature matrix. The proposed sensor placement optimization algorithm was verified by this example, and the experimental results show that the final sensor placement configuration can meet the requirements of maximum parameter fault detection and isolation performance.
Rapid modeling of impingement pipe in turbine blade
LI Jixing, XI Ping
2016, 42(6): 1149-1155. doi: 10.13700/j.bh.1001-5965.2015.0386
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Impingement pipe is the core component of the impingement cooling in turbine blade. In order to realize the rapid modeling of impingement pipe in turbine blade with complex cooling structure, a generative rapid modeling method was proposed.Firstly, the body of pipe was created by section curves which suits the shape of channel in blade and generated by curves created by insect-shape method. Then by using envelope surface trimming method and along-curve array method, the modeling stability and efficiency of cooling hole and hump are guaranteed.And the fitting precision between impingement pipe and blade is guaranteed by an iterative formula about protrude position.Finally, a rapid impingement pipe modeling program was developed based on UG Open API, and the modeling result validated the feasibility of the proposed method.
Best position to apply an impulse in a planar swing-by
JIA Jianhua, LYU Jing, WANG Qi
2016, 42(6): 1156-1161. doi: 10.13700/j.bh.1001-5965.2015.0409
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Applying an impulsive thrust during a close encounter with a celestial body can significantly improve the efficiency of the swing-by maneuver. The impulse is usually applied at the periapsis in much literature, but there is no proof that periapsis is the optimal position. In order to study the best position to apply an impulse in a planar swing-by, the powered swing-by is described by the three usual parameters of the standard swing-by maneuver plus the three parameters which specify the magnitude, the direction and the position of the impulse. A set of new analytical equations are derived, including the variation in velocity, energy and angular momentum due to the maneuver as a function of the six parameters. Using these equations, it is possible to find the best position to apply the impulse to maximize the energy change. The results show that periapsis is not the best position, as the application of impulse in the best position is 20% more efficient than the application of impulse at the periapsis in some cases.
SIFs of interfacial crack using generalized extended finite element method
SU Yi, WANG Shengnan, LU Longkun
2016, 42(6): 1162-1168. doi: 10.13700/j.bh.1001-5965.2015.0376
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Generalized extended finite element method (GXFEM) is a new numerical simulation method which combines both the generalized finite element and the extended finite element. The principle of the generalized extended finite element method for analyzing the stress intensity factor (SIF) of bi-material interfacial cracks is proposed. A new enriched function for bi-material interfacial crack tip is proposed, and the twelve crack tip enriched functions are reduced to the six ones. Because of the discontinuity of bi-material interface, enrichment functions based on level set are added in the displacement mode of the conventional finite element method. And the node freedom of the crack element and crack tip element are also generalized. Besides, the calculation precision is improved. A comparison of literature method and GXFEM calculations of numerical examples shows the the accuracy and reliability of the proposed method.
Model providing QoS guarantee for feedback-free MAC in aeronautical Ad Hoc networks
GAO Xiaolin, HAN Feng, YAN Jian, LU Jianhua
2016, 42(6): 1169-1175. doi: 10.13700/j.bh.1001-5965.2015.0384
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In aeronautical Ad Hoc networks,in order to meet the strict quality of service (QoS) requirements of high priority traffic with high dynamics,a modeling method and a corresponding threshold setting method for priority feedback-free media access control (MAC) protocols were proposed to guarante etimeliness and reliability of high priority packets.First,a time constraint model was built at receiving end,with a mapping relation between channel statistics and packet success probability being deduced.Accordingly,the access threshold basedon QoS requirements of different traffic was obtained,while access control of different traffic was accomplished.Simulation results indicate that,in typical aeronautical networks,the QoS requirements of high priority traffic can be guaranteed as the feedback-free MAC based on the proposed method is employed.In particular,packet success probability of high priority traffic is higher than 99%,and end-to-end delay is less than 1 ms.
Practical nonlinear control allocation method based on feedback of position of surface
LYU Yongxi, ZHANG Weiguo, SHI Jingping, QU Xiaobo, CAO Yuyan
2016, 42(6): 1176-1184. doi: 10.13700/j.bh.1001-5965.2015.0411
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To focus on the problems of nonlinearity and coupling between the moment coefficients and the surface deflections when the aircraft autonomously takes off,lands and flies with high angles of attack,a practical and novel nonlinear control allocation method based on feedback of position of surface was proposed for tailless flying wing aircraft (TFWA). The nonlinear moment coefficient of the surface deflection in previous sampling interval was removed from the desired three-axis moment coefficients by feedback of position of surface. Thus the nonlinear control problem was transformed into the linear control allocation problem and was solved. Unanimous asymptotic stability of this method was proved and steady state error was zero; the feasibility of this method was also analyzed. Comparisons of digital simulation were done with sequential linear programming,sequential quadratic programming and genetic algorithm,and results prove the high accuracy and fast computing speed of this method. Efficiency of this method to solve nonlinear control allocation problem was verified by the digital simulations of pseudo-inverse method,fixed-point iteration and neighbor search method. Finally,strong generality and good real-time performance of this method for TFWA and F18 were demonstrated on the xPC-DSP semi-physical simulation platform.
Reliability evaluation of radar power amplification system considering epistemic uncertainty
PAN Gang, SHANG Chaoxuan, LIANG Yuying, CAI Jinyan, MENG Yafeng
2016, 42(6): 1185-1194. doi: 10.13700/j.bh.1001-5965.2015.0390
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There is epistemic uncertainty in degradation law of a high-reliability component because it is hard to obtain its adequate performance data within a short time,and system reliability cannot be accurately estimated. For the purpose of accurate estimation of system reliability,assuming that the component performance distribution parameter was the interval variable,a component' performance parameter distribution model was built based on interval parameter variable and a computational method of the interval-valued state probability was provided. The boundary of the state performance interval was compensated,the interval-valued universal generating function and its algorithm were defined,an assessment method of interval-valued reliability of the multi-state system in consideration of epistemic uncertainty was proposed,and the reliability of a power amplification system was analyzed. This method not only avoids the lack of distribution information of the performance parameters,but also accurately builds a distribution model of the performance parameters. Therefore,it is widely used in engineering.
Numerical analysis of unstable combustion developing process in model combustor
FENG Wei, NIE Wansheng, LI Bin, ZHENG Gang
2016, 42(6): 1195-1202. doi: 10.13700/j.bh.1001-5965.2015.0457
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Gas-liquid two-phase unsteady combustion process was simulated with the Euler-Lagrange method to analyze the combustion instability, which was observed in hypergolic propellant combustor. The pressure oscillations amplitude and spectral characteristics agreed with the experimental results. And the variation rule of pressure and heat release in different combustion stages was analyzed. The results indicate that, while the pressure oscillation amplitudes exceed 10% of the average pressure, the pressure oscillation frequency is 9 200 Hz, and the transverse pressure distribution is in accordance with the first-order tangential vibration mode. The generation and developing process of the first-order tangential self-excited high frequency unstable combustion have been reproduced in simulation. At the early stage of the change from stable to unstable combustion, the pressure oscillation obtains energy from part of the combustion heat release fluctuations and the pressure oscillation amplitude increases slowly. With the combustion, the phase and spectral characteristics between the combustion heat release and pressure oscillation tend to be the same, and the pressure oscillation increases sharply. When they are fully coupled, the pressure oscillation amplitude in combustion chamber exceeds 200% of average chamber pressure and reaches the limits of saturation.
Optimized dictionary learning algorithm for compressive data gathering
YI Kefu, WANG Donghao, WAN Jiangwen
2016, 42(6): 1203-1209. doi: 10.13700/j.bh.1001-5965.2015.0375
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To improve the adaptability of compressive data gathering for various classes of sensory data, and to reduce the recovery error caused by environmental noise, an optimized dictionary learning algorithm was proposed to adaptively construct the sparse dictionary in compressive data gathering. Theoretical analysis shows that in compressive data gathering the recovery error caused by environmental noise is positively correlated to the self-coherence of the sparse dictionary. Therefore, in order to alleviate the recovery error caused by environmental noise, the proposed algorithm introduces a penalty term into the dictionary learning procedure to reduce the self-coherence of the learned dictionary. The introduced penalty term can also alleviate the over-fitting on the training data during the dictionary learning procedure, which further improves the sparse representation performance of the learned dictionary. The experimental results verify that the proposed method achieves better sparse representation performance than other dictionary learning methods, and can alleviate the recovery error caused by environmental noise.
Some influence factors in aerodynamic heat transfer numerical simulation of jet-interaction flow
LIN Boxi, YAN Chao, LI Yachao
2016, 42(6): 1210-1218. doi: 10.13700/j.bh.1001-5965.2015.0379
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When simulate the aerothermal environment of thrust jet and its interaction flow on an engineering vehicle geometry, people always use some approximate modeling to the full chemical reaction flow,then the influence to the simulation results of an approximate treatment for real gas and the modification to internal geometry of the thruster nozzle must to be manifested. By doing numerical test and compare results of some calculations, two main influence factors were studied to show the laws in approximate numerical simulation. One of which is how the possible modifications to thruster internal geometry influence on wall heat flux distribution of jet-interaction flow field. The second is when using a methodology of ideal gas equivalence to model fuel thruster jet, how different matching methods of the thruster exit boundary thermodynamic parameters influence the exhaust jet morphology and wall heat flux distribution. These computation results reveal the two main influence factors in aerodynamic heat transfer approximate simulation of thrust jet, and could be used to guide engineering applications.
New method of scatterers association and 3D reconstruction based on multi-hypothesis tracking
BI Yanxian, WEI Shaoming, WANG Jun, ZHANG Yaotian, SUN Zhongsheng, YUAN Changshun
2016, 42(6): 1219-1227. doi: 10.13700/j.bh.1001-5965.2015.0380
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Aiming at the problems of associating radar target scattering centers from the unknown perspective of one-dimensional range,in order to associate the radar target scattering centers at unknown radar line of sight,a new scatterers association method based on auxiliary information of scatterers intensity using multi-hypothesis tracking (MHT) is proposed.After using the scattering centers intensity information to associate the scattering centers,the target was 3D reconstructed by sequential factorization method.The sequential factorization method can effectively reduce the burden of the data storage and increase the real-time ability.The simulation results verify that the proposed algorithm is simple and very stable for the complex situations.This method can effectively eliminate the false scattering points derived from the process of target moving in the association process of hypothetical update and management,which is applicable to the target in multiple poses multiple scattering correlation and 3D reconstruction.This method has a good robustness for 3D reconstruction of the target under complex spatial motion.
Multipath mitigation algorithm with hierarchical search based on MEDLL
YE Jinyu, KOU Yanhong
2016, 42(6): 1228-1235. doi: 10.13700/j.bh.1001-5965.2015.0419
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Multipath mitigation techniques using parametric baseband processing, represented by multipath estimating delay locked loop (MEDLL), have attracted widespread attention by estimating the parameters of direct path and multipath signals simultaneously. The improvement of the estimation accuracy for such techniques, however, is at the cost of the increase of complexity. In order to reduce the resource consumption and speed up the search while maintaining the accuracy, this paper proposes a hierarchical search strategy for the maximum likelihood (ML) estimation of MEDLL. The rough estimates obtained by the former stage of search units serve as the priori information for the next-stage search with a narrower range and a smaller step to achieve refined estimates step by step. The expressions of computational complexities of the original MEDLL and the proposed tree MEDLL (T-MEDLL) with different number of stages are derived analytically, which shows that the computational burden of our approach can be reduced to 30%-50% of that of the traditional blind search with the same delay resolution of 0.01 chip in the presence of a single multipath. In addition, a digital intermediate frequency (IF) GPS signal simulator and a software GPS receiver are developed to test the parameter estimation accuracy and the pseudorange multipath errors of the hierarchical search and the blind search under different multipath scenarios. The results demonstrate that the T-MEDLL can maintain the same performance as MEDLL with significantly reduced implementation complexity.
Similarity-based remaining useful life prediction method under varying operational conditions
LI Qi, GAO Zhanbao, LI Shanying, LI Baoan
2016, 42(6): 1236-1243. doi: 10.13700/j.bh.1001-5965.2015.0396
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Remaining useful life (RUL) prediction is the core task of prognostic and health management (PHM). A similarity-based RUL prediction method under varying operational conditions was presented. Similarity-based RUL prediction method does not need to build a model for entire complex system but can provide reasonable results, which is promising in engineering practice. However, the operational conditions such as different working loads and environmental conditions are not considered for degradation modeling. Therefore, this method combines basic similarity-based method and the effect of operational conditions to achieve better RUL prediction accuracy. Degradation models with different operational conditions were built by training units, and the RUL prediction was achieved by matching corresponding model using the real-time operational conditions of the running unit. The proposed degradation models describe the degradation process more precisely by taking the differences of operational conditions into account. According to the same accuracy standard, multi-group numerical experiments were finished by basic similarity-based method and the proposed method. The result shows the proposed method has a higher accuracy in RUL prediction.
Influence of primary swirl offset on downstream flowfield of dual-swirl cup
LIU Chengchuan, XU Quanhong, YU Bowen
2016, 42(6): 1244-1249. doi: 10.13700/j.bh.1001-5965.2015.0402
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Dual-swirl cup has been widely used in aero-engine combustor because of excellent comprehensive combustion performance. But it is inevitable that there will be slight misalignment during its assembly, and in order to examine whether these subtle errors will affect combustion performance, more detailed study of the effect of local structure and aerodynamic characteristics on the downstream flow field in a double swirl cup is required. Therefore, we tested downstream cold flow field of the dual-swirl cup using particle image velocimetry (PIV) technology under normal temperature and pressure conditions to explore the impact law of the offset distance of the primary swirl on downstream flow field of the reverse double swirl cup. The results show that with the increase of the offset distance, in a small non dimensional offset area, downstream flow field does not change, and when the offset distance continues to increase, downstream flow field will apparently shift with excellent symmetry, which provides a reference for swirl cup installation.
Effects of RP-3's wall coke deposition on flow resistance under supercritical pressure
WANG Yue, GUO Jun, DENG Hongwu, HUANG Haoran, JIA Zhouxia
2016, 42(6): 1250-1255. doi: 10.13700/j.bh.1001-5965.2015.0403
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The effect of the jet fuel RP-3 coking deposition in stainless micro-tube on flow resistance and heat transfer characteristics under long heating condition is analyzed based on experimental results. In the experiment, fuel flowing through miniature tube was heated from 130℃ to 450℃ under the pressure 5 MPa when dissolved oxygen in fuel saturated. The whole experiment lasted 36 h with the mass flow rate maintained at 3 g/s. The experimental results show that with the growth of time, coking amount in the tube increases along time. The results also show that the effect of coke deposition on flow resistance and heat transfer is significant. As more and more coke particles adhere, the heat transfer resistance increases rapidly in the early stage of the test and gradually stabilizes, while the flow resistance along the miniature tube increases as the experiment continues. As time grows, the flow resistance in the tube presents a "rapid growth to steady growth, then to exponential growth" process. Besides, based on the test results, an influence coefficient used as an engineering model to value the impact of the coke deposition on single tube of the heat exchanger is proposed.
New moving target monitoring mode with Hybrid-TOPS of spaceborne SAR
WANG Yamin, CHEN Jie, YANG Wei, ZHAO Songtao
2016, 42(6): 1256-1262. doi: 10.13700/j.bh.1001-5965.2015.0420
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Conventional synthetic aperture radar (SAR) has the problems of limited targets' velocity boundary and low accuracy. To solve the problem, this paper introduces a new mode Hybrid-TOPS to detect moving target. Firstly, the SAR imaging mode was represented quantitatively through hybrid factor. Employing hybrid factor, a new mode for moving target detection was proposed by the combination of TOPS and inverse TOPS. This mode can not only realize repeated observations in the same area, but also has the ability of continuous observation in azimuth. Moreover, sequential SAR images were able to be obtained by taking advantages of hybrid TOPS combination. Secondly, through image registration and parameter inversion based on the new mode, moving target's azimuth information can be obtained. Finally, the simulation results justify the superiority of the new mode and the extracting accuracy in movement information.
Experimental study on flight performance of dragonfly during climbing
GAO Qian, ZHENG Mengzong, LI Zhiping, LI Qiushi
2016, 42(6): 1271-1278. doi: 10.13700/j.bh.1001-5965.2015.0374
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The flight performances of insects in free flight are very important for the research of the bionic fluid mechanics. The movement law and dynamic characteristics of dragonfly Pantala flavescens during climbing flight in two different flying angles are investigated using high-speed videography. We induced the dragonfly climbing according to the phototaxis of the fliers. Two high-speed cameras with orthogonal axes are used. The body and wings kinematics of dragonflies are captured accurately by feature points matching and three-dimensional reconstruction and the flight performance is studied. The experimental results show that the lift of the flier is lager than the thrust during high-incidence climbing and maximum flapping amplitude of the dragonfly during high-incidence climbing is 40% bigger than that during low-incidence climbing; the flapping frequency of high-incidence climbing is 3.3 Hz more than that of low-incidence climbing and the phase difference of high-incidence climbing is 20° smaller than that of the other. The pitch angle of the body during high-incidence climbing is larger than normal, which is controlled by the front inclination angle of forewing. This body attitude can generate larger lift force.
Path tracking for visual navigation based on H2/H∞
WU Chengliang, CAO Yunfeng, ZHUANG Likui, XIE Ye, DING Meng
2016, 42(6): 1279-1285. doi: 10.13700/j.bh.1001-5965.2015.0370
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Visual navigation system was physically divided into sensors (camera and laser rangefinder) and computer vision processing, so as to study the characteristics of visual navigation system theoretically. And then visual measurement model was established, which was based on the above computer vision processing. The uncertainties of visual position measurement model were divided into parameter uncertainties and input interference. The sensitivity degrees triggered by different kinds of model uncertainties in visual position estimation were analyzed in detail by simulation. Finally, based on the introduction of visual measurement model uncertainty, visual measurement model perturbation ranges, under the constraint conditions of both track control system stability and tracking performance, were given in the study of the H2/H∞ hybrid robust control application to trajectory tracking, which is of certain guiding significance to computer vision algorithm.
Task planning for CE-3 rover's manipulator to probe in place based on SA* algorithm
ZHANG Tao, JU Hehua
2016, 42(6): 1286-1294. doi: 10.13700/j.bh.1001-5965.2015.0382
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This paper focuses on the shortage of past researches which do not satisfy the conditions that CE-3 lunar rover is required to satisfy the constraints of imaging, light detection, obstacle avoidance, and number of manipulator switching. A new approach based on SA* algorithm is presented for task planning of lunar rover's manipulator. The algorithm searches the manipulator work space and calculates the sun light based on the ephemeris to satisfy the lighting constraint, and manipulator and environment collision are avoided by an effective method of collision detection based on hierarchical bounding box. Moreover, motion sequence generated by this algorithm according to cost cuts satisfies the constraints:Minimum number of transformation of manipulator. The feasibility of SA* algorithm for manipulator are verified by the result of on-orbit mission.
Airship's longitudinal motion impact analysis based on coupling ballonet
YOU Yingjie, MI Panpan, LYU Mingyun, LIU Wending
2016, 42(6): 1303-1310. doi: 10.13700/j.bh.1001-5965.2015.0427
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Large high-altitude airship has a high volume ratio which even exceeds 90%, so it will induce significant impact on airship's motion because of the ballonets dynamics. Considering one large-scale airship whose cruise altitude is 6 000 m, ballonets dynamics based on the cylindrical container was established and airship longitudinal motion equations containing ballonets were further formulated. Finally, numerical simulation of airship longitudinal motion was performed and results were compared with that of airship model without ballonet dynamics. Results indicate that ballonets dynamics will make a difference to airship's pitch motion, easily inducing motion divergence and ballonets' coupling impacts reduce when the airship rises. In the meantime, the smaller the diameter of ballonets is, the smaller the dynamic coupling effect is when ballonets' volume is unchanged. In addition, the controllability of airship will be weakened because of ballonets, which should be taken into account during airship design.

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