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2013 Vol. 39, No. 3

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Active vibration control and attitude maneuver of flexible spacecraft via direct adaptive control method
Liu Min, Xu Shijie, Han Chao
2013, 39(3): 285-289.
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An attitude maneuver and active vibration control method was proposed for flexible spacecraft with piezoelectric material as flexible modes active suppression sensors and actuators. Firstly, the almost strict positive real (ASPR) property of flexible spacecraft with collocated sensors and actuators was discussed. Then, the direct adaptive controller was designed to both the attitude maneuver and flexible appendix vibration. Finally, the controller was applied to a flexible spacecraft in different initial conditions. Theoretical analysises and simulation results validate that the controller has strong robustness to spacecraft inertial and flexible model uncertainties, can suppress modes at the same time. Both the attitude maneuver and vibration suppression can be accomplished effectively.
Design of a controller for morphing aircraft based on the LQ/RHO multi-loop technology
Chen Wei, Lu Jingchao, Zhang Weiguo
2013, 39(3): 290-294,314.
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In order to ensure the flight stability of morphing aircraft under the morph state, a multi-loop controller was proposed. The inner-loop controller was designed by the linear quadratic (LQ) output feedback approach, which was used to ensure stability under the fixed-wing state. In the process of morphing, an indeterminate term was introduced to describe the interferences and unmodeled dynamics. The outer-loop controller was designed by the receding horizon optimal (RHO) algorithm, which was used to calculate the real-time control correction value within a finite horizon. The simulation results show that the proposed controller is able to yield a consistent response regardless of morph rate, and that it satisfies the requirements of real-time and robustness.
Multi-degree-of-freedom vibration suppression of space trusses based on multiple dynamic vibration absorbers
Yang Kai, Cui Long, Huang Hai
2013, 39(3): 295-299.
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To implement vibration control of large and light flexible space trusses (LLFST), an adaptive method of suppressing MDOF vibrations of trusses via multiple dynamic vibration absorbers (DVA) was presented. Firstly the single-input and single-output (SISO) control strategy for MDOF vibration control with multiple DVAs was interpreted. Secondly the adaptive control effectiveness of a single DVA subjected to multi-frequency vibrations was proved by simulations. The adaptive algorithm is multi-frequency adaptive disturbance canceller (ADC) which is utilized for suppressing the multi-frequency vibration adaptively without the knowledge of the precise model. The simulation results show that the vibrational attenuations of each frequency component are 62.38 dB and 42.51 dB respectively, compared with passive DVA. Finally, an experiment on the three DOF vibration control of a triangular truss via multiple DVAs was conducted. The experimental results show that the single-frequency vibrational attenuations of each DOF are 95.13%, 93.59% and 95.01%, respectively,and the multi-frequency vibrational attenuations of each DOF are 94.26%, 91.55% and 93.42%, respectively.
Torque control based on torque feedforward and rudder angle compensation
Niu Guochen, Wang Wei, Wei Zhiqiang, Zong Guanghua
2013, 39(3): 300-304.
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In order to provide precise load torque for testing the stiffness of rudder systems, a torque control system with the characteristics of high accuracy and large scale combining torque feedforward and rudder angle compensation was designed. The mathematical models of torque motor, torque motor driver and spring beam were established. Performance of loading torque was influenced obviously by the stiffness coefficient of spring beam, which was analyzed from load target, frequency width and system stability. Because continuous oscillation and large phase lag appear while torque loop controller was adopted, torque feedforward and rudder angle compensation were induced based on invariance theory. The experiment results prove that torque oscillation and phase lag can be suppressed effectively using the approach, and successful completion of stiffness test is ensured.
Probabilistic design for blade-tip radial running clearance of HPT
Fei Chengwei, Bai Guangchen, Zhao Heyang, Han Yanbin
2013, 39(3): 305-309.
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To improve the blade-tip radial running clearance(BTRRC) design of aeroengine high pressure turbine(HPT), the probabilistic analysis of BTRRC was implemented based on deterministic analysis through considering the heat and mechanical loads of objects (disk, blade and casing) and selecting random variables legitimately. The variation of BTRRC and the radial deformations of objects with time were gained and the minimum clearance at t=180 s was regarded as the probabilistic analysis point through the deterministic analysis. In addition, the probabilistic distribution features and failure numbers, failure probabilities and reliabilities under different static clearance δ predetermined were obtained besides the major factors impacting on the deformations and BTRRC through the probabilistic analyses. The results show that δ=1.95 mm is advisable to select as an effective reference for the control and design of BTRRC for satisfying the aeroengine design and engineering.
4D route rapidly planning based on route-segment tree
Zhang Xianfeng, Zhou Qizhong, Wang Changqing
2013, 39(3): 310-314.
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The launch time error and the random difference during flying will influence the arriving time of the unmaned combat aerial vehicles(UCAV). Based on the sparse A* algorithm, a route-segment tree was built with considerations of the moving characteristics of modern UCAV. The best leaf point was found according to the target position, and the route which can eliminate the arriving time error of the target was laid out by route backtracking and velocity optimizing. The 4D (four-dimensional) rapidly route planning algorithm was realized in a case, and the simulation result shows that the UCAV can arrive the target at the designed time.
Aerocaptureperiod under rotating atmospheric environment for Mars vehicle
Lü Jing, Zhang Mingming, Gong Shengping
2013, 39(3): 315-319,375.
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With regard to the human exploration of Mars, based on aerobraking, the dynamics equations for the Mars vehicle were established, both in the static and rotating atmospheric environment. Simulations of the flight databases were generated by a Matlab process based on a three-dimensional dynamic model.A comparative performance analysis of atmospheric models was carried out using details of the duration, aerodynamicloading of the Mars vehicle, and other orbital parameters. The results show that changes of the orbital parameters form are large difference under the rotating and static atmospheric environments on the low periareon, the influence of the rotating atmospheric environment should be considered.
Wing geometric twist design method based on lifting-line theory
Qiao Yuhang, Ma Dongli, Deng Xiaogang
2013, 39(3): 320-324.
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To meet the demand for reducing induced drag in aircraft design, a geometric twist design method for the wing was proposed, based on the research of three-dimensional wing induced drag in lifting-line theory. This method with input parameters of wing total lift, wing planar shape, airfoil aerodynamic characteristics, gives the wing geometric twist result. In low speed situations, a wing with elliptical lift distribution, which had the minimum induced drag,was obtained. Far-field method was used to calculate induced drag, CATIA parametric method was developed for automatic wing generation, script language of ICEM tool was applied for automatic grid generation, symbolic computation capability of MATLAB was carried out to perform the program. This method is suitable for geometric twist design of straight wing in low-speed viscous flow. Examples indicated that the wing designed by this method had an elliptical lift distribution, thereby had lower induced drag.
Coordinated task and resource allocation for multi-UAV based on probability collectives
Di Bin, Zhou Rui, Wu Jiang
2013, 39(3): 325-329.
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For the needs and characteristics of task and resource allocation in the scenario of multiple unmanned aerial vehicles(multi-UAV) collaborative target attacking, considering the constraints of the target value, the amount of ammunition restrictions and UAV payload, flight constraints etc, the mathematical model of multi-UAV collaborative task and resource allocation was established. Probability collectives based collaborative task and resource allocation distributed optimization algorithm was developed and heuristic methods was utilized to simplify problem solving and also improve the computational efficiency. Finally, simulation results show that the optimal solution could be obtained with high efficiency, and the trade-offs between efficiency and solution quality could be achieved by parameter adjustment. The proposed algorithm has good applicability.
Confirmation and analysis on the optimal multiposition alignment of strapdown inertial navigation system
Liu Zhiqin, Wang Xinlong
2013, 39(3): 330-334.
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To realize precise alignment, the optimal multiposition alignment conditions and methods of strapdown inertial navigation system(SINS) were investigated. Using an equivalent error model of SINS established by Lyapunov transform, the observability of SINS error states was quantificationally analyzed by rotating IMU around the orthogonal axes. Then, by research on the relationship between inertial instrument errors and IMU attitudes, the rotational modes by quantitative analysis of inertial measurement unit(IMU) were presented, and the IMU optimal rotating angular positions on which the optimum estimation of SINS error states were achieved . Finally, the simulation results verify the correctness of theoretical analysis.
Dynamics modeling and tension analysis for a cable-driven humanoid-arm robot
Chen Weihai, You Xianqiang, Cui Xiang, Yu Shouqian
2013, 39(3): 335-339.
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Compared to the traditional robotic arm, the cable-driven humanoid-arm robot (CDHAR) similar to human muscles parallel drive mode is the hybrid structure of serial-parallel. However, the introduction of cables also increases the difficulty in dynamic analysis. CDHAR can be seen as a four-link serial mechanism including base, upper arm, forearm and end-effector, iteration Newton-Euler method was adopted to establish the recursive form of dynamics equation. Taking into account the redundant actuation and single-direction force for the cable, tension distribution algorithm based on the dynamic minimum pre-tightening force was proposed to calculate driving force of each cable. Compared to the method without conducting tension distribution or based on the static minimum pre-tightening force, the proposed algorithm can make the driving force of each cable real-time adjust by the dynamic minimum pre-tightening force and meet the rigidity requirement in different running condition.
Catastrophe analysis of the water mist fire suppression process
Yang Lijun, Tong Mingxi, Zhao Jianbo
2013, 39(3): 340-343.
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To understand the water mist fire suppression mechanism and find out the extinguishment boundary, the water mist fire suppression process was analyzed with a non-linear catastrophe theory. The expressions of the flame energy potential function and the flame critical extinguishing temperature were deduced. The extinguishment criterion for the n-heptane pool fire was obtained. The extinguishment boundary is verified by conducting the water mist fire suppression experiments on n-heptane pool fire. The effect of oxygen concentration on the flame extinguishing temperature is quicker than that of heat absorption.
Node splitting algorithm of R*-tree based on self-adaptation clustering
Sun Dianzhu, Sun Yongwei, Li Yanrui, Song Yang
2013, 39(3): 344-348.
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A node splitting algorithm of R*-tree based on self-adaptation clustering was proposed to improve the spatial query efficiency of the point cloud, triangle mesh and etc. Picking some data points as reference point set with uniform sampling. The true number of clusters, which made the totality comparability value of nodes to become convergence, was obtained based on the Gap statistical method and k-means algorithm. According to the true number of clusters, the node of R*-tree was split without human intervention. Experiment results prove that the algorithm can solve the node clustering problems for any complex geometric object, reduce the parameters dependence and nodes- coincidence degree of node splitting of R*-tree, and improve the R*-tree spatial query efficiency.
Unknown input observer design based on auxiliary outputs
Zhu Fanglai, Wang Kun, Han Dong
2013, 39(3): 349-354.
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A design method of unknown input observer which is able to estimate simultaneously the system states and the unknown inputs was proposed when the observer matching condition is not satisfied. Based on the concept of relative degree with respect to unknown input, the auxiliary outputs were designed so that the newly-constructed output equation can meet the matching condition. A high-order sliding mode observer was considered to get the exact estimates of both the auxiliary outputs and their derivatives in a finite time based on the system measured outputs. Then a reduced-order observer which can asymptotically track the real states of the system was constructed. A kind of unknown input reconstruction method based on both the state and the auxiliary output derivative estimates was developed. None of system differential information has been used directly when the unknown inputs was reconstructed. The simulation results to a system show that the proposed method is effective.
Random PWM method based on pre-determined carrier frequencies
Wang Tingling, Xiong Junhua, Zhang Jin
2013, 39(3): 355-360.
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For reported random frequency pulse width modulation(PWM) methods, harmonic distortion appears in the output waveform because the relationship between the carrier frequencies and their changing frequency is not carefully considered. To cope with the above obstacle, the effect of carrier changing frequency on the randomized carrier signals was investigated. A fact that phase mismatch of the two changing carrier signals induces the output voltage distortion was subsequently obtained. Then, a proposed approach was to select the switching frequency randomly among a few pre-determined carrier frequencies. Both simulation and experimental results verify that using the proposed PWM technique, the dominant harmonic clusters are effectively reduced while retaining good sinusoidal output waveforms, which are superior to that based on the conventional random PWM methods.
Design of multi-FPGAs processor based system for remote sensing image high-speed compression
Xu Xiaoshen, Jiang Hongxu, Xiao Chaosheng
2013, 39(3): 361-365.
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A design of multi-FPGAs for massive remote sensing image high-speed compression was proposed, which includes a hybrid multi-FPGAs based parallel processor architecture due to light coupling between modules and tight association of a single module; a compression mechanism for balanced data distribution and code stream ordered recycling, which improves parallel efficiency of isomorphic FPGAs and ensures correctness of image compression; a processor failure and link failure supported structure fault-tolerant model, which ensures the reliability of compression; a distributed external storage and high-speed serial bus based communication strategy among multi-FPGAs, which satisfies the communication requirements for massive remote sensing image high-speed compression. Experimental result shows: the parallel efficiency of a single processor achieves 93.5%. In this application system, result of hardware compression is consistent with that of software compression, its throughput reaches 1.6 Gbit/s or more and provides high reliability.
Process of ducile-brittle transition of crystal brittle materials on ultra-precision machining
Wang Minghai, Wang Wei, Gao Lei
2013, 39(3): 366-370.
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By combination of fracture mechanics and dislocation mechanics, the method of simulating the process of ducile-brittle transition of brittle material based on the connection between macromechanics and micromechanics was discussed. The single crystal material mechanical property and crystal geometric structure was given. In press-shear complicated stress condition, interaction mechanism between its internal cracks and dislocation was demonstrated, its process of ducile-brittle transition on ultra-precision machining was illustrated. Considering cutting tool to crystal material press-shear mixed effect, the method of realizing the best tool's rake angle was given and the influence of the tool edge radius on the process of ducile-brittle transition of crystal brittle materials on the ultra precision machining was analyzed. Finally, research results were tested and verified through the experiments.
Dynamical quality in bidirectional associative memory neural network model
Li Xiuling
2013, 39(3): 371-375.
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In order to study for the effect of delay in dynamic behavior of associative memory neural network model, an n+1-dimensional bidirectional associative memory (BAM) neural network model with multi-delay was considered. Sufficient conditions for nontrivial periodic solution were met by the model by taking delay as a parameter, using the global Hopf bifurcation existence theorem of the functional differential equation and the Bendixson non-existent theorem of the ordinary differential equation. These provide important theoretical basis for the design and application of BAM neural network. Finally, numerical simulations were carried out and results show that the proposed conclusion is effective.
Design of evaporator-condenser-separate mechanical vapor compression system
Wu Hong, Li Yulong, Chen Jiang
2013, 39(3): 376-380.
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An evaporator-condenser-separate mechanical vapor compression (MVC) system was presented, and the process of the new system was described. The thermal cycle model was established, and the thermodynamic parameters were optimized. In addition, measures to improve the efficiency of the system were proposed. The results show that the better effect of cleaning and prevention of scale was obtained by the new system. The heat exchange temperature between the evaporator and the condenser should better be 3.7 ℃. The rotating disk evaporator and the hydrophobic tubes of condenser can enhance the heat transfer and improve efficiency.
Dish-Stirling power generation system performance prediction model and simulation analysis
Li Mingzhen, Dong Jinzhong
2013, 39(3): 381-385.
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A solar dish-Stirling system model was developed for design, optimization, control, and systems development of dish-Stirling systems. It modeled the energy transfer in parabolic concentrator and receiver, cycle thermodynamics and mechanical dynamics in Stirling engine and so on. The model's scope extends from the solar energy to thermal, mechanical, and electrical energy out, helping to study complex system interactions among subsystems. It can be used to simulate the entire range of system operation from start-up to full power conditions. The model details were discussed and the simulation results were given for steady and dynamic phenomena. According to the constant hot-end temperature control strategy, the system output power changes parabolicly with the direct normal insolation and the system efficiency changes slightly in a day. During the feeding process which causing a pressure jump, the hot-end temperature decreases in case of engine speed unchanged, and the output power increases firstly and then decreases to a steady value.
Robust consensus approach to high-order multi-agent systems based-on tree-type transformation
Cui Yan, Jia Yingmin
2013, 39(3): 386-390.
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Robust consensus control problem was studied for high-order multi-agent systems with the network under switching topologies by the tree-type transformation approach, through which the systems were turn into the reduced-order systems. After defining an appropriate controlled output, the consensus problem was reformulated as a robust L2-L∞ control problem. For the systems with uncertain time-delays, a consensus condition in terms of linear matrix inequalities (LMIs) is obtained, which could provide the allowable upper bound of delays. Furthermore, a sufficient condition is derived for the robust consensus with the desired disturbance attenuation performance of the systems subject to external disturbances. A simulation example of formation control for multi-agent systems is provided to validate the theoretical results.
High accuracy method of ultrasonic gas leak direction detection　based on time delay estimation
Liao Pingping, Cai Maolin
2013, 39(3): 391-395.
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In order to solve the low accuracy problem in current gas leak detection, a new ultrasonic leak detection method based on time delay estimation (TDE) was proposed.Three ultrasonic sensors arranged in an equilateral triangle and received the ultrasound generated by a gas leak and the leak direction can be determined according to time delays between the outputs of every two sensors.A TDE algorithm based on cubic spline interpolation was adopted to overcome the accuracy limit caused by sampling interval.For each kernel window length, delay estimates of 100 sets of experimental data were obtained and their mean squared errors (MSE) were calculated.Comparison between MSE of experimental data and Cramér-Rao lower bound showed that their changing tendency was accordant.Influences of MSE, the space between sensors and the distance between leak and sensor on direction accuracy were analyzed.Results show that the direction error increases with MSE, decreases with the space between sensors, and increases with distance between leak and sensor.The direction detection accuracy is improved by 7～10 times compared with detection method with single ultrasonic sensor.
Fiber-optic perimeter location system based on wavelet transformation
Zhong Xiang, Zhang Chunxi, Lin Wentai, Liang Sheng
2013, 39(3): 396-400.
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In order to improve the location accuracy of dual Mach-Zehnder interferometic based fiber-optic perimeter location system, the influence of signal frequency range and signal noise ratio (SRN) was analyzed and emulated. Basing on these, a fiber cable, which combines the high-sensitivity to vibration and the adaptability to complex environment, was adopted to ensure the reliability and extend the signal frequency range. The wavelet de-noising algorithm was employed to extract the effective frequency component, filter the noise and advance the SNR. Finally, a field test with 31 km monitoring length was carried out to justify the excellent performance of the proposed fiber cable and the effectiveness of the wavelet de-noising algorithm.
Motion performance analysis of Rabbit rover with retractable-claw wheels
Yue Ronggang, Song Lingjun, Wang Shaoping
2013, 39(3): 401-405.
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To improve the climbing obstacles capability of a robot, a rover prototype named as Rabbit whose motion is based on 4 retractable-claw wheels was designed. Principle of the wheel, mobile system and control system of Rabbit were presented respectively, and some experiments were finished to test its performance. The experimental results show that the Rabbit rover can move freely in various terrain conditions, such as step, slope, multiple-obstacle, and simulated lunar soil, etc. Experiment results demonstrate that the retractable-claw wheels enable the rover to traverse over steps whose height is 1.4 times of the wheel radius, over sloped terrains up to 40° tilt angle, which is much larger than conventional robots can do. The rover with retractable-claw wheels is proved to be suitable for planetary or field exploration.
Sensitivity analysis of the factors affecting robot closed-chain positioning error
Qi Lizhe, Chen Lei, Wang Wei, Yu Leibin
2013, 39(3): 406-410.
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Aiming at the problem that is difficult to calibrate the robot positioning error accurately as many affecting factors, the closed-chain mathematical model for robot's positioning error was established based on Jacobian matrix firstly. Secondly, the formulas of single factor differential positioning error (SFDPE) and relative single factor differential positioning error (RSFDPE) were given to analyze the single point sensitivity (SPS) of each factor. Next, the sampling space of robot was designed by the orthogonal experiment design method which can fully reflect the robot position error distribution and then the formulas of the single factor comprehensive differential positioning error (SFCDPE) and relative single factor comprehensive differential positioning error (RSFCDPE) was depicted based on the interval probability density. Finally these factors' single point sensitivity and more points comprehensive sensitivity (MPCS) were simulated. This is a foundation work for robot positioning error calibration further.
Globality-based uncorrelated linear extension of graph embedding for fault feature extraction
Tang Diyin, Yu Jinsong, Chen Xiongzi, Wang Honglun
2013, 39(3): 411-415.
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Systematic approach to extract the most effective information from original features is of great importance and efficiency for fault detection where physical modeling is highly difficult and the original features are highly dimensional and nonlinear. An algorithm named globality-based uncorrelated linear extension of graph embedding for fault feature extraction was therefore proposed. Supervised learning was used to establish the relationship between original features, and the linear extension of graph embedding was adopted as the feature extraction framework. Great efforts were taken to combine the locality-preserving properties inside the classes and global distribution between different classes, in order to discover both the local and global structure of original features. Information redundancy was greatly reduced by eliminating the statistic correlation between extracted features. Experimental results on standard dataset demonstrate the superiority of this proposed algorithm to many classical feature extraction methods. Thus, a better efficiency in the convergence of training network and in the fault detection can be achieved.
Application of mixed-simulation for development of rolling resistance measurement system
Zhang Shaoguo, Gao Feng, Xu Guoyan, Cui Ying
2013, 39(3): 416-420.
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To ensure test data precision for rolling resistance, the key factors affecting equipment performance were assessed and predicted. Based on the equipment measuring principle, numerical simulation model for tire rolling resistance was established. Physical output quantity of sensor was collected and processed. Furthermore, rolling resistance test properties were obtained by finite element analysis. The difference in test data was contrasted by changing the relative reference position between the drum and the axle. Linear regression orthogonal was adopted for error-correction. Compared with the laboratory data, trend test shows that the test model can reflect the response relationship between rolling resistance and controlling parameters, so the test model has high reliability. The replicate test shows that the error-correction model for rolling resistance can reduce the equipment system error and improve the measurement accuracy. The simulation results provide practical basis for equipment development.
Memory optimized parallel LDPC decoder architecture design on GPU
Ge Shuai, Liu Rongke, Hou Yi
2013, 39(3): 421-426.
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An optimized decoding architecture was proposed for low-density parity-check (LDPC) codes layered decoding algorithm based on Nvidia's Fermi graphic processing unit (GPU). In accordance with the parallelism characteristics in GPU hardware structure, inter-frame and intra-layer parallelization processing were adopted to fully utilize the resource of streaming multiprocessors (SM) and mitigate the decoding parallelism limitation in layered decoding algorithm. Secondly, by compressed storing parity-check matrix in on-chip constant memory and coalescing access the exchange information in off-chip global memory, the memory access latency was reduced, and hence the decoding throughput was improved. Simulation results show that 14.9x to 34.8x speed-up for decoding throughput is obtained by using multi-frame processing and memory access optimization on GPU platform.

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