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2016 Vol. 42, No. 7

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Volume 42 Issue72016
2016 Year 42 Volume 7 Issue E-journal
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Two-dimensional layered materials of transition metal dichalcogenides
ZHANG Qianfan, GAO Lei, TIAN Hongzhen, XU Zhongfei, WANG Yapeng
2016, 42(7): 1311-1325. doi: 10.13700/j.bh.1001-5965.2016.0092
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Transition metal dichalcogenides (TMDCs) nanomaterials have become a focus of research for their unique properties. Various remarkable properties of TMDCs materials provide possibility for their applications in nanoelectronics, optoelectronics and spintronics devices. This paper mainly introduces the recent advances of TMDCs in different fields with various excellent properties, and summarizes the preparation method, properties and nanostructure morphology of layered TMDCs materials. The edge states of layered TMDCs materials have important effect on the properties, which leads to superior properties different from bulk materials. In this paper, we emphasize the effects of edge states in low dimensional nanomaterials on the properties (chemical activity, electronic property and magnetic property) and the newest progress in edge states. Especially, the magnetic property in edges of TMDCs materials provides the opportunity for their potential usage in the field of magnetism and spintronics, which have aroused great interest of researchers. This paper summarizes the research achievements in TMDCs materials from theoretical and experimental perspectives, which would be supportive for the development of two-dimensional layered TMDCs materials.
Link awareness-based OLSR routing algorithm for airbonre highly dynamic networks
MA Linhua, ZHANG Song, RU Le, XU Yang, TIAN Yu, YU Yunlong
2016, 42(7): 1326-1334. doi: 10.13700/j.bh.1001-5965.2015.0470
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Due to the high mobility of the unmanned aerial vehicle (UAV) node, quick changes of the network topology structure, the airborne highly dynamic UAV network suffers some problems such as poor stability of the network link, low data delivery ratio and high data congestion information. In order to overcome these problems, a link awareness-based OLSR (OLSR-LA) routing algorithm for airborne highly dynamic networks is proposed. The charactreistics of two received consecutive Hello messages, such as the Doppler shift and the power strength of received Hello messages, can be used to obtain the relative speed and direction of motion between the two adjacent nodes in the airborne highly dynamic UAV network. Then the link connection lifetime is estimated by the relative speed. The OLSR-LA routing algorithm uses the queue length in the buffer of the MAC layer to indicate the local load level. Then the predicted value of the node's load level in the next time can be predicted by the ARIMA-WNN combination forecasting model and passed to neighbor by Hello message. Finally, according to the conditions of link awareness, regional routing load-balancing (RRLB) algorithm is employed to avoid network congestion. The simulation results show that compared to the traditional OLSR algorithm, the proposed OLSR-LA routing algorithm can effectively improve the packet delivery rate, increase the traffic of network, reduce the end-to-end transmission latency and enhance the real-time and effectiveness of the data transmission in the whole UAV networks.
Multicast wireless NoC mapping based on network coding
CHEN Yiou, TAN Fang, LING Xiang
2016, 42(7): 1335-1343. doi: 10.13700/j.bh.1001-5965.2015.0482
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Featured by high bandwidth, QoS guarantee, and broadcasting, wireless network on chip(NoC) can provide an efficient platform for multicore and parallel processing for communication and signal processing systems. In addition, network coding can greatly increase the transmission efficiency at the cost of small power consumption in wireless NoC. On this basis, we proceeded from the features and requirements of communication and signal processing systems, and built proper architectures and mapping models for wireless NoCs. We also proposed a joint optimization method including task mapping and network coding mapping, to meet the specialized constraints and requirements of wireless NoC multicast services, such as maximizing network throughput, data transmission, and minimizing communication latency and power consumption, so as to achieve efficient task paralleling and multi-processor cooperation. Experimental results prove that the proposed architecture and mapping algorithm can achieve at least 6% power consumption saving and 16% throughput gain, with acceptable physical complexity increasement than the traditional methods.
Numerical simulation and experiment in high-speed cutting superalloy GH4169
FAN Xiaoliang, WU Xuehua, WANG Jinfeng, KANG Wenli
2016, 42(7): 1344-1351. doi: 10.13700/j.bh.1001-5965.2015.0436
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The finite element modeling technologies of the high-speed cutting superalloy GH4169 were investigated to simulate the cutting process correctly, which include establishing the finite element model, selecting the material constitutive model, and determining the chip separation criteria and contacting friction model, etc. To simulate the chip separation process and research the chip formation mechanism in high-speed cutting GH4169, the two-dimensional orthogonal cutting finite element models were constructed using Johnson-Cook model and isotropic hardening material constitutive model respectively. As a result, two models obtained the similar serrated chip. On this basis, equivalent plastic strain, cutting temperature and cutting force curve were simulated further. To verify the validity of the finite element model, an experiment was carried out by high-speed turning GH4169 on the machine of CA6140, and the serrated chip generated from the turning experiment verifies the validity of two finite element models. The results show that the serrated chip sawtooth degree increases with the increase of cutting speed and the adiabatic shear is the main reason to cause the serrated chip on high-speed cutting superalloy GH4169. The cutting force curve and cutting temperature generated from the experiment accord better with model A, which demonstrates that model A exceeds model B in reflecting the machining characteristics of high-speed cutting GH4169.
Design of dynamic total variance and its fast algorithm
WANG Lixin, LI Can, JIANG Zhou, ZHU Zhanhui, TIAN Ying
2016, 42(7): 1352-1360. doi: 10.13700/j.bh.1001-5965.2015.0488
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There exist two shortcomings in Allan variance approach when it is used to analyze random error. First, the vibration of estimated value is large in long-term correlation. Second it can't follow the dynamic change of signal.This paper integrates the thought and advantage of total variance and dynamic allan variance, and proposes the dynamic total variance approach. Firstly, original data is truncated by window function. Secondly, we continue the data in the window. Then the data after continuation is analyzed by total variance, so that local random characteristic is acquired. With the window sliding, the change of random characteristic of original signal with time is obtained. Through verification, the dynamic total variance can solve the two shortcomings of Allan variance approach. Eventually, linear vibration trial of hemispherical resonator gyro(HRG) is designed to clarify this new algorithm, which indicates that dynamic total variance possesses advantages in analysis accuracy and data quantity that it used. However, this new algorithm has the problem of excessive calculation and low speed of analysis, so we derive recursive formula of it, based on which fast algorithm is provided.
Scheduling method for double-cluster tools with parallel chambers based on capacity constraint resource
ZHOU Binghai, LI Ming
2016, 42(7): 1361-1367. doi: 10.13700/j.bh.1001-5965.2015.0538
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To effectively solve scheduling problems of multiple cluster tools of 450 mm wafer fabrication systems with parallel processing chambers, a scheduling method based on capacity constraint resource (CCR) was proposed. Firstly, with comprehensive consideration of the characteristics of different types of wafers, resources and residency constraints, a mathematical programming model of double-cluster tools with parallel chambers was established to minimize the makespan of the system. Then, to optimize manipulator movements by adopting locking-tightening-loosening (LTL) strategy to the CCR, a piecewise scheduling algorithm was constructed with the CCR．Finally, through the analysis of simulation experiments, the results indicate that the proposed algorithm is valid and competitive.
Dynamic modeling and flutter analysis of a fin-actuator system
ZHANG Renjia, WU Zhigang, YANG Chao
2016, 42(7): 1368-1376. doi: 10.13700/j.bh.1001-5965.2015.0448
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Dynamics of an actuator has a direct impact on the flutter characteristics of a fin structure. Thus it is important to build the dynamic model of the fin-actuator system precisely before a flutter analysis. A typical fin-actuator system is investigated by constructing its motor model, reducer model and controller model, respectively. Based on the characteristics of the ground vibration test (GVT) data, two nonlinear factors are considered including the contact stiffness between the screw and the balls, as well as the freeplay. Simulation results reproduce what were seen in the test. It is found that the contact stiffness and freeplay dominate the dynamic characteristics of the fin-actuator system. In the flutter analysis, the angular responses of the actuator stimulated by different angular step commands under both contact stiffness assumption and constant stiffness assumption are compared. The results show that a limit cycle ossllation (LCO) domain and an unstable domain exist under the constant stiffness. Its critical velocities do not vary with the freeplays. However, besides the LCO and unstable domains, a stable domain appears under the contact stiffness. At a specific flow velocity, its critical command angle is higher than the one under constant stiffness. But its critical velocity decreases as the freeplay increases, and even reaches a lower level than the critical velocity under constant stiffness. Enough attention should be paid to this issue.
Torque ripple reduction strategy for magnet suspended reactive flywheel brushless DC motor
TANG Jiqiang, WANG Yingxu, ZHOU Xinxiu
2016, 42(7): 1377-1387. doi: 10.13700/j.bh.1001-5965.2015.0451
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Due to its high torque response speed, direct torque control (DTC) without flux feedback makes the torque ripple reduction of magnet suspended reactive flywheel (MSRF) brushless DC motor (BLDCM) possible, which has a small inductance. However, the bang-bang controller of the DTC causes high torque ripples. To solve this problem, the mathematic models of commutation and diode freewheeling of the inactive phase were established and the relationship between torque and phase current was obtained.Then a torque prediction method based on the established models was proposed to reduce the torque ripple effectively, and the stability and robustness were proved. While estimating the back electromotive force of the BLDCM with sliding mode observer (SMO), a smooth and continuous function with one parameter was employed to replace the sign function which leads to a higher back electromotive force estimation accuracy. Simulation and experimental results show that compared to the traditional DTC, the advanced torque control method with torque prediction and advanced SMO can significantly suppress the torque ripples and has almost the same torque response speed.
Route planning algorithm for configuring airborne pseudolites
ZENG Lingchuan, LI Dapeng, QU Yi, REN Aiai, GONG Yingkui
2016, 42(7): 1388-1397. doi: 10.13700/j.bh.1001-5965.2015.0477
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This paper focuses on the airborne pseudolites based on airships and proposes a route planning method to configure airborne pseudolites from the initial position to the target position. First, by analyzing the geometric dilution of precision (GDOP) as the performance of navigation enhancement, a route planning cost function was designed based on the distance and GDOP. Then, on the basis of sparse A* algorithm and analysis of constraint conditions, a route planning algorithm was proposed which can adjust the weights of distance and GDOP adaptively, and the route was smoothed by the Dubins curve. Finally, the route planning algorithm was validated through the simulated experiments. The simulated experimental results show that the route planning algorithm can reduce the GDOP cost effectively and improve user positional accuracy in the subsequent route planning if the GDOP value is severe at current time; on the other hand, while the GDOP approaches its optimal value, the algorithm will increase the weight of distance to make pseudolites move to their destinations as quickly as possible and reduce the time consumption during the subsequent route planning.
Double fuzzy sliding mode control for EHA based on feedback linearization optimal sliding surface
ZHANG Zhen, LI Haijun, ZHU Defang
2016, 42(7): 1398-1405. doi: 10.13700/j.bh.1001-5965.2015.0454
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In order to improve the control performance for electro-hydrostatic actuator(EHA), double fuzzy sliding mode control based on feedback linearization optimal sliding surface was proposed. The nonlinear model of EHA was linearized based on the feedback linearization by establishing linear switching function and adopting optimal control theory. Fuzzy control was introduced into sliding mode control to reduce the chattering, and a fuzzy controller was adopted to estimate the switching control gain based on the characteristics of optimal sliding mode switching function; another fuzzy controller was adopted to adjust the corrective controller based on the principle of the sliding mode control. The simulation results show that the proposed control scheme is effective.
Mental fatigue characteristics based on EEG analysis
FAN Xiaoli, NIU Haiyan, ZHOU Qianxiang, LIU Zhongqi
2016, 42(7): 1406-1413. doi: 10.13700/j.bh.1001-5965.2015.0428
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By simulating the process of pilots monitoring instrument information during flight,the change characteristics of electroencephalogram (EEG) waves along with mental fatigue were analyzed,which will provide scientific bases for future development of countermeasure to fatigue.Two visual detection tasks of different difficulties were designed to induce fatigue respectively,and many measurements were combined to study the EEG characteristics of fatigue.The EEG parameters [δ,θ,α,β,(α+θ)/β,α/β,(α+θ)/(α+β),θ/β] at the beginning and end sections of the task were compared and analyzed.The results show that there is a significant increase in α activity in the frontal,central,parietal and occipital lobes(P < 0.05),and a decrease in the β activity in the pre-frontal,inferior frontal,posterior temporal and occipital lobes(P < 0.05); there is no significant difference in δ rhythm and θ rhythm in any brain region(all in P > 0.05); The four formulas increase significantly in all brain regions except the temporal(P < 0.05),where only α/β changes clearly(P < 0.05); compared with the task with higher difficulty,the parameters in the task of lower difficulty change more obviously.Therefore,all these characteristic parameters in specific brain regions except for δ and θ can be considered as possible indicators for mental fatigue.It was also verified that adding right amount of task difficulty could counter mental fatigue.
Fault-tolerant control for hypersonic vehicle with system uncertainty
PENG Cheng, WANG Xinmin, XIE Rong, MU Lingxia
2016, 42(7): 1414-1421. doi: 10.13700/j.bh.1001-5965.2015.0462
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For the systems with norm-bounded parameter uncertainty and actuator failure faults, a robust fault-tolerant tracking control method is presented. In this method, the linear matrix inequalities (LMI) which guarantee the stability of the closed-loop system and meet the demand of the robust performance were derived utilizing the bounded real lemma. In order to reduce the conservativeness of the designed controller, the different Lyapunov variables were adopted under different system fault states. An iterative LMI algorithm is developed to solve the resulting non-convex optimization problem caused by the use of different Lyapunov variables. Since the convergence of the iterative algorithm lies on the choice of the initial values, an efficient way to find a good initial value was given after derivation. The method was applied to the design of the hypersonic vehicle X-33 tracking controller. Simulation results show that the proposed method is available and effective.
Threat evaluation of air-targets for key positions air-defense under dynamic fire access
LIU Jingshu, JIANG Wenzhi, LEI Yuyao, DAI Jinjin
2016, 42(7): 1422-1431. doi: 10.13700/j.bh.1001-5965.2015.0475
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Under the background of naval key position air-defense combat, air-targets threat evaluation model is established based on key positions relative value, target attack capability, target attack intent and targetarrival time. Firstly, the key positions air-defense combat system under dynamic access is introduced, and the dynamic access and quit strategy are presented. Secondly, the key positions relative value, air-target number and target killing probabilities are used to quantize the air-target threat capability. Then, air-target attack quantization model is proposed with the target-to-key positions course angle, and the time that targets arrived at key positions is calculated based on different target types. Finally, the threat level order is carried out by comparing the distance between the targets and air-defense system intercept area, and the air-target threat value is obtained. The simulation results show that the quantized method conforms with the ordinary tactics reasoning, and it can develop the air-target threat order results objectively. This paper can provide a decision reference for the key positions defense operation.
Flare longitudinal control for approach and landing of reusable launch vehicle
HAO Xianwei, WANG Yong, YANG Ye, GUO Tao, ZHANG Daibing
2016, 42(7): 1432-1440. doi: 10.13700/j.bh.1001-5965.2015.0441
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To solve the flare longitudinal control problem for approach and landing of reusable launch vehicle (RLV), a compound control strategy based on combined feedback control and feedforward control is proposed. The feedback control law parameters were designed. The feedforward control law parameters were designed and optimized based on the index of time-weighted height tracking error and the integral for square of error change rate. Under the premise of not affecting the stability of the system, according to feedforward control with the input compensation, the tracking precision of RLV for the flare trajectory was improved and the ground distribution of RLV was reduced. The method of control law smooth switching was proposed by initial value of integrator, which realizes the smooth switching between the different control laws of the RLV landing gear before rand after release. Simulation verifies that flare longitudinal compound control law and the method of control law smooth switching are effective.
BLDC motor commutation position optimization strategy based on bus current
ZHANG Qian, FENG Ming
2016, 42(7): 1441-1448. doi: 10.13700/j.bh.1001-5965.2015.0429
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This paper analyzes the relation between commutation position of brushless direct current (BLDC) motors and bus current, builds up their mathematical relation, and proposes a sensorless BLDC motors commutation position optimization strategy. This strategy regulates the commutation position by a proportional integral (PI) adjuster, aiming at regulating the current and the back electromotive force (BEMF) in-phase. The controlled variable of the PI adjuster is the commutation position compensating angle and the deviation value is the ratio of current change over angle. This optimization strategy can revise the detected position signal error and the phase deviation caused by the winding inductance at the same time. The experimental results verify that this optimization strategy can get the best commutation position accurately and fast, and improve the operating efficiency effectively.
Diagnosis method of simultaneous fault with incomplete information
SUN Weichao, XU Aiqiang, LI Wenhai
2016, 42(7): 1449-1460. doi: 10.13700/j.bh.1001-5965.2015.0433
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Test information is often incomplete in the fault diagnosis process of equipment. And simultaneous fault diagnosis process is more difficult at the same time. In response to this situation, the current methods of fault diagnosis with incomplete test information and of simultaneous fault diagnosis are studied firstly. Then we define incomplete fault diagnosis decision system to describe incomplete test information. And it defines incomplete boundary rough entropy to measure the level of uncertainty in the system and assign the importance of each attribute. Meanwhile, the method to calculate frequency of attributes' value under incomplete condition is proposed. In order to diagnose simultaneous fault, the paper constructs the diagnosis model under DSmT framework,and proposes a new combination rule of interval-value belief to overcome the shortcomings of previous methods. Finally, the validity and applicability of the method are proved by two equipment fault diagnosis examples.
Theoretical model for a porous projectile striking on flat rigid anvil
LIU Hu, LIU Hua, YANG Jialing
2016, 42(7): 1461-1468. doi: 10.13700/j.bh.1001-5965.2015.0471
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Taylor impact is often applied to the determination of the dynamic yield stress of materials. For theoretical analysis of the Taylor impact of porous projectiles, the relationship between the density of a compressed porous projectile and the compressive plastic strain is very important. This paper proposes an exact density model for the compressible porous projectile by inducing the plastic Poisson's ratio, and further, an analytical model is established for the compressible porous projectile striking on a flat rigid anvil. As the plastic Poisson's ratio is a constant, the first order Taylor series expansion of the compression density ratio model can be reduced to the existing model. As the plastic Poisson's ratio is a function of the compressive plastic strain and the relative density, the relative density has a major influence on the impact response and the final deformation of the projectile, but the duration of impact-contact process is almost unaffected. The initial velocity of the projectile has considerable effects on both the final deformation of the projectile and the duration of impact-contact process. The present theoretical model is useful in analyzing the dynamic behavior of porous materials.
Equivalent modeling method of open thin-walled beam under action of transverse stiffening member
DENG Hao, CHENG Wei
2016, 42(7): 1469-1478. doi: 10.13700/j.bh.1001-5965.2015.0456
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Satellite structures usually have a lot of open thin-walled beams under the action of transverse stiffening member. Transverse member is generally evenly distributed along the axial direction of the beam. Through the study of such structures, it is theoretically proved that the differential equation of vibration of this structure has the same form as the equation of ordinary open thin-walled beam. Therefore, equivalent calculation was carried out using the open thin-walled beam element. Three kinds of mathematical models of open thin-walled beams, finite element model, transfer matrix model and analytical model, were established. The equivalent cross-section parameters were identified using sequential quadratic programming. At the same time, the influence of different objective functions on the identification results was analyzed. And a method for estimating the initial parameters of the cross-section was presented. For the finite element model, the MATLAB and ABAQUS interactive parameters optimization method was proposed. A combination of both full advantages can quickly and efficiently optimize the cross-section parameters and this method has strong versatility. Finally, the correctness and accuracy of the equivalent modeling method are verified by experiments. The proposed equivalent modeling method can reduce more than 90% of the number of elements. By establishing the simplified model, the efficiency of the structural model updating and structure reanalysis can be greatly improved.
Design of solar-powered aircraft configuration for reducing trim loss
QUE Jianfeng, WANG Weijun, WU Yu
2016, 42(7): 1479-1485. doi: 10.13700/j.bh.1001-5965.2015.0464
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The solar-powered aircraft with the static stability generally uses tail trim, which causes the trim loss. To address the problem of the aerodynamic trim loss, a new solar-powered aircraft configuration called "T" configuration was put forward. The general solar-powered aircraft configuration was summarized. The trimming principle by lowing center of gravity in the state of cruise flight was analyzed. The models of energy balance and mass analysis were built. A concept design method which is suitable for the new solar-powered aircraft configuration was introduced, and then the design parameters of the aircraft configuration were optimized. The results show that the solar-powered aircraft of "T" configuration not only has static stability, but also reduces the trim loss. In the state of cruise flight, the solar-powered aircraft of "T" configuration can decrease the flying power required in unit area by 6.2% compared with the normal solar-powered aircraft, which shows obvious application effect.
Automatic learning of Bayesian network structure using graph model and learning algorithm
SHEN Lin, YU Jinsong, TANG Diyin, LIU Hao
2016, 42(7): 1486-1493. doi: 10.13700/j.bh.1001-5965.2015.0445
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In order to improve the accuracy and efficiency of the data-driven approaches in learning Bayesian network structure, expert knowledge is usually implemented in the learning algorithm. To deal with the lack of effective ways to combine the expert knowledge and the data-driven learning approaches in the existing methods, this paper proposes an automatic learning method for Bayesian network structure learning, which combines multi-signal flow graphs and learning algorithm K2. The method inserts expert knowledge into data-driven learning methods, using the information of relationships between signals from multi-signal flow graphs and the structure learning algorithm K2, to achieve automatic learning of Bayesian network structure. Numerical analysis, compared with other typical network structure learning algorithms, proves that the proposed method significantly lowers the structure learning requirements for learning scale and training data size and provides a higher learning accuracy and computation efficiency. The application of the proposed method is illustrated using a real engineering system and verified the practicability of the algorithm at the same time.
Optimal inventory modeling of spare parts multi-indenture multi-echelon under multi-constraints
CAI Zhiming, JIN Jiashan, CHEN Yanqiao
2016, 42(7): 1494-1501. doi: 10.13700/j.bh.1001-5965.2015.0435
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One possible way to improve the efficiency of equipment support and readiness is to optimize spare parts inventory, for the existing studies can't adjust to the demands of multi-indenture multi-echelon spare parts supply modes under multi-constraints and meet the requirements of the engineering practice in the army. Optimizing the spare parts carrying project of the warship formation dispatches to fight pirates in Somalian waters during the mission preparation phase is taken as the study background. The support costs, tonnage and warehouse space of warship are used as constraint conditions, and the minimum expect back order and maximal availability are used as the target function. Optimal spare parts carrying project of the warship formation, multi-indenture multi-echelon is obtained by Lagrange multiplier method and marginal method. The total spare parts support costs, mass and volume of bases and rear warehouse are compared with the constraints index upper limit before and after optimization by example. The analysis of the example shows that the models and methods of this paper can solve the problems of the warship formation carrying spare parts, and at the same time provide the references for dealing with such problems in other areas.
Investigation of temperature fluctuation in loop heat pipe under acceleration fields
XUE Hao, XIE Yongqi, DAI Hua, YU Jianzu, MA Wei
2016, 42(7): 1502-1508. doi: 10.13700/j.bh.1001-5965.2015.0465
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Based on the centrifugal machine system, a test apparatus was set up to investigate the operating characteristics of dual compensation chambers loop heat pipe (DCCLHP) under both gravity and acceleration fields. The ranges of the heat load and the magnitude of acceleration are 25-300W and 3g-9g, respectively. The influences of different heat loads, acceleration directions and magnitudes on temperature fluctuations of loop heat pipe were analyzed. The results indicate that the effect of the acceleration can change the start mode and operating performance of the DCCLHP. The temperature fluctuation at the outlet of the condenser and even around the whole loop can be restrained or wakened. But the operating temperature of the evaporator is nearly the same under the same heat load conditions. The inherent flow instability of the gas-liquid two phase flow can be enhanced by the acceleration effect which reinforces this unstable flow in reverse. Furthermore, the instability of the heat leak from the evaporator to the compensation chamber is enhanced. In addition, the cooling effect of the condenser can weaken the temperature fluctuation of the condensing pipe line.
Damage detection of structures with interval uncertain parameters
YANG Juntan, QIU Zhiping, LI Qi
2016, 42(7): 1509-1517. doi: 10.13700/j.bh.1001-5965.2015.0398
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To deal with structures with uncertain parameter which often lacks sufficient statistical information in damage detection, the uncertain parameters were modeled as interval numbers. The structural strain modal testing method was introduced using finite element method, and the strain modal was further expressed as the function of the interval parameter. Combined with the first order Taylor expansion and interval analysis, the range of each strain modal under parameter uncertainty is estimated, and thus we obtained an approach for structural damage detection considering uncertainty. Comparison between the proposed method and the traditional probabilistic method was conducted. Numerical simulations of a simply supported beam under different damage were performed by investigating the change of strain modes due to different damage levels and uncertainty levels. The influence rules of damage and uncertainty on strain modal were obtained, and a brief discussion of the impact of noise on damage detection was performed. The work of this paper provides a new technique and thought for damage detection of uncertain structures.
Formation flight control method of multiple UAVs based onguidance route
WU Juncheng, ZHOU Rui, DONG Zhuoning, CHE Jun
2016, 42(7): 1518-1525. doi: 10.13700/j.bh.1001-5965.2015.0458
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To solve the problem of formation flight control of multiple unmanned aerial vehicles (UAVs), a coordinated control method based on guidance route was proposed. According to the position error between wingman's current location and desired location and the flight status of leader, guidance route was generated for wingman to track. In view of the sudden obstacles during flight, the method of changing formation configuration was used to avoid obstacles. For possible collisions between UAVs, according to UAVs' position and time of arrival at the collision point, UAV avoided collision from two aspects of height and heading. The simulation results demonstrate that using this method, UAV can maintain stable formations, and meanwhile be able to avoid the obstacles during the flight and avoid the collision between aircrafts.
Adaptive reentry guidance based on on-board trajectory iterations
ZHAO Di, SHEN Zuojun
2016, 42(7): 1526-1535. doi: 10.13700/j.bh.1001-5965.2015.0463
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An adaptive method for on-board generation of entry trajectory is presented to effectively tackle the discontinuity of the input data of the guidance system, as the traditional trajectory-tracking guidance method cannot well adapt to saltatorial conditions such as the switch of navigation modes. By real-time polynomial fitting and iteration, the desired altitude-versus-velocity profiles satisfying the final constraints are determined, and then the corresponding angle of attack and bank angle commands are obtained, which guide the vehicle to safely and accurately reach the terminal area of energy management. This method enables the iterations to be fast-converging, as it takes the advantage of building analytical relations between velocity and the state variables including energy, altitude, flight-path angle and range-to-go. Numerical simulations indicate that this method has a strong adaptability against uncertainties such as the error and the saltation of the input data, as well as a better accuracy than the traditional method under various dispersion conditions. It is also proved that this method significantly enhances the autonomy and adaptability of entry guidance under practical application circumstances, compared to the traditional trajectory-tracking guidance method.
Robust LPV control design based on HOSVD
SUN Bin, YANG Lingyu, ZHANG Jing
2016, 42(7): 1536-1542. doi: 10.13700/j.bh.1001-5965.2015.0486
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Considering the trade-off between the accuracy and complexity of the linear parameter varying (LPV) modeling of hypersonic vehicles, a novel polytopic LPV modelling technique based on grid tensors and higher-order singular value decomposition (HOSVD) was developed. Firstly, through Jacobian linearization, the grid tensor description of a hypersonic vehicle with large flight envelopes was introduced, and a polytopic LPV model was constructed using HOSVD. The resulting model was described by a linear combination of vertices of linear time invariant (LTI) models and corresponding weighting functions. The discarded singular values were treated as a modeling error index. A robust variable gain controller which combines a robust controller and gain scheduling technique was then designed for the 6 degree-of-freedom nonlinear model of the hypersonic vehicle. Simulation results demonstrate that the proposed method not only reduces the computational complexity, but also guarantees the modeling accuracy. Furthermore, under the proposed controller, the closed loop system can track the attitude commands rapidly, and good stability and robustness are achieved.
Mimetism electric potential energy motion planning algorithm for aircraft
HE Renke, WEI Ruixuan, ZHANG Qirui, XU Zhuofan
2016, 42(7): 1543-1549. doi: 10.13700/j.bh.1001-5965.2015.0430
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Abstract:
Path planning can ensure that the unmanned aerial vehicle (UAV) flies safely and completes mission successfully. In the complex threat environment and high-dimensional space, traditional path planning methods have some limitations in the aspects of the calculation speed, path security and applicability. In order to solve these problems, the electric potential field distribution characteristics and the law of mechanical work driven by electric field force were studied. The mimetism electric potential energy path planning method was proposed, and the environment model based on the electric potential field distribution and path node probability choice mechanism were established. The relationship between threat intensity and distance was described by using electric potential. Combined with electric potential, the path safety evaluation standard was proposed. On this basis, the potential field based sampling-based random path planning method was proposed. The results show that, compared with traditional methods, the method mentioned above can generate optimal path in consideration of non-holonomic differential constraints, significantly shorten the path length and computational time, and improve the path security, which is of great value for application of path planning.
Heavy helicopter-slung-load coupling system flying qualities in closed-loop state
ZHU Xiaoyu, CAO Yihua, CAO Long
2016, 42(7): 1550-1556. doi: 10.13700/j.bh.1001-5965.2015.0442
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Abstract:
Flying qualities of a heavy helicopter augmented with an automatic flight control system (AFCS) and flying with externally slung loads are investigated using the mathematical model of the CH-53A/D helicopter. A nonlinear dynamical model of helicopter-slung-load in closed-loop state was built based on single mass-point hypothesis and a control system model. Under this hypothesis, extra degrees of freedom and constraints were brought in by the consideration of the slung-load, which made the set of equations of motion increased to a 13-order one. The coupling system in closed-loop state was linearized under small-perturbed conditions. After this, the slung-load flight control response characteristics in both time and frequency domain were analyzed. The effect of slung-load mass, slung-load rope length and helicopter velocity on coupling system's flight quality was analyzed according to the handling qualities requirements for military rotorcraft indicated by ADS-33E. The final results show that the slung-load mass, slung-load rope length and helicopter velocity have varying degrees of impact on the time domain features and handling qualities of the coupling system.

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