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Zeng G.,National University of Defense Technology | Hu M.,Academy of Equipment Command and Technology
Acta Astronautica | Year: 2012

The current paper investigates the electromagnetic formation flight control problem using the finite-time control technique. The electromagnetic force model is presented, and the effects of the Earths magnetic field on the EMFF satellites are analyzed. The equations of relative motion and general formation description method are then established. A robust sliding mode controller is designed to achieve trajectory tracking in the presence of model uncertainties and external disturbances. The proposed controller, which combines the advantages of linear and terminal sliding mode controls, can guarantee the convergence of tracking errors in finite time rather than in the asymptotic sense. By constructing a particular Lyapunov function, the closed-loop system is proven globally stable and convergent. Numerical simulations of formation maintenance and reconfiguration are then presented to show the effectiveness of the developed controller. © 2012 Elsevier Ltd. All rights reserved.

Chen G.,Academy of Equipment Command and Technology
Advanced Materials Research | Year: 2012

A dynamic hybrid position/force control method is developed for the coordination of two manipulators of a dual-arm robot to cope with the case of dual-arm tightly cooperate a common rigid object in the presence of environmental constraint. Begin with the definition of a group of generalized motion and force vectors used for task description, and by synthesizing the object dynamics and manipulator dynamics, an object-oriented dynamic equation of the dual-arm rigid coordination system is first derived, where relationships between object motion, internal stress force, and environmental contact force are explicitly presented. Furthermore, this equation and that of single arm dynamics in Cartesian still remain the same form. Based on this definition and description, the dynamic hybrid position/force control scheme for dual-arm symmetric coordination is then designed, and the decomposition and parallel realization of the control algorithm is also discussed. Several experiments have been done on two coordinated PUMA562 robot manipulators, which show that the proposed method works effectively, where the object motion and internal/external force can be simultaneously controlled during cooperation. © (2012) Trans Tech Publications.

Ren Y.,Academy of Equipment Command and Technology | Su D.,Beihang University | Fang J.,Beihang University
IEEE Transactions on Power Electronics | Year: 2013

To intuitively analyze the absolute and relative stability of the forward and backward whirling modes of the high-speed magnetically suspended flywheel rotor with significant gyroscopic effects and bending modes, this paper presents a whirling modes stability criterion based on complex coefficient frequency characteristics method. Through variable reconstruction, the multiple-input multiple-output magnetically suspended rotor system is converted into a single-input single-output (SISO) system with complex coefficients. The stability equivalence of the systems before and after variable reconstruction has been proven. Based on this, the inherent relationships between the distribution of the closed-loop poles of the complex coefficient SISO system and the whirling modes stability are revealed, and the Nyquist stability criterion is further extended by applying the argument principle. All of these lay the foundation for the whirling modes stability theorem, and then, their stability criterion is further developed. Simulation and experimental results prove the effectiveness and correctness of the presented criterion. © 1986-2012 IEEE.

Yang X.,Unit 63892 of PLA | Yang X.,Academy of Equipment Command and Technology | Yan L.,Unit 63892 of PLA | Zeng L.,Academy of Equipment Command and Technology
Information Sciences | Year: 2013

In practice, many practical problems occur in uncertain environments, especially in situations that involve human subjective evaluation such as that in the analytic hierarchy process (AHP). This paper presents a practical multi-criteria group decision-making method for decision making under uncertainty. To handle the randomness and fuzziness of individual judgments, the normal Cloud model, group decision-making technique, and the Delphi feedback method are adopted. In the proposed Cloud Delphi hierarchical analysis (CDHA), experts are asked to express their judgments using interval numbers. Individual fuzziness and randomness are then mined from the interval-value comparison matrices. Subsequently, the interval-value pairwise comparison matrices are converted into the corresponding Cloud matrices, and the one-iteration Delphi process is executed to diminish individual judgment mistakes. The individual Cloud weight vectors are calculated using the geometric mean technique and are finally weighted to form the group Cloud weight vector. A simple case study that involved reproducing the relative area sizes of six provinces in China shows that the CDHA method can effectively reduce mistakes and improve decision makers' judgments in situations that require subjective expertise and judgmental inputs. In addition, a practical decision-making problem in which houses are ranked by home buyers shows that the proposed method is effective when applied to complex, large, multidisciplinary problems with considerable uncertainties. © 2012 Elsevier Inc. All rights reserved.

Zeng D.,Academy of Equipment Command and Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

A mathematical model of space target illumination characteristics is established based on the basic theory of radiation by considering geometry, background, and material characteristics of the space target. Using the model, the spatial distribution of scattering light intensity from the space target is calculated with the modeling and blanking technique of target when being illuminated by the sun. The relations of specular reflection with the position, geometry, materials and other attributes of the space target are analyzed. Furthermore, the effect of specular reflection on space target detecting is discussed. A method of characteristic simulation of space target is presented. The simulation result indicates that polyhedral structure, mirror surface, or solar sail is easy to cause specular reflection. It shows the effect of specular reflection is helpful for space target detection and identification. © 2016 SPIE.

Hong Y.,Academy of Equipment Command and Technology
Shiyan Liuti Lixue/Journal of Experiments in Fluid Mechanics | Year: 2014

Tunable diode laser absorption spectroscopy (TDLAS), a line-of-sight technology, is used to measure the temperature, velocity, concentration and other parameters in the flow field. As a fast and efficient diagnostic tool, TDLAS sensors have wide applications in the development of the combustion and propulsion system. TDLAS sensors play more and more important role in the improvement of the system performance. When new concept propulsion appears, the sensors face new challenge, at the same time, relevant technology have been improved. The development of the TDLAS technique, applications in the combustion diagnosis and enormous potential have been summarized. This review can provide enlightenment and help for the researchers in this field.

Zhang F.,Academy of Equipment Command and Technology
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

Through research on the test of coating corrosion damage, this paper finds out that the temperature-time (T-H) curve of coating corrosion and the T-H curve of metallic corrosion are consistent, and they have the same service environment spectrum. Since the calculation formula of metallic calendar life is deduced from the distribution regularities and service environment spectrum of T-H curve, the calculation formula of coating's calendar life is the same as that of the metallic calendar life. It is also revealed that metallic coating is sensitive to test temperature with some regularities. Hence, an effective test method to have the calendar life of coating is to increase the temperature of the test. To verify the above-mentioned conclusion, a comparative study of theoretical calculation and test of the calendar life of aluminum coating is also conducted. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.

Zhang F.,Academy of Equipment Command and Technology
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

This paper studies the scatter factor of calendar life, and through research on the distribution regularities of the test data of metallic corrosion, a calculation model of scatter factor which is in consistence of the regularities is determined. Standard deviation is calculated through the corrosion test data. Scatter factor value used in corrosion test is calculated by the given standard deviation. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.

Zhang F.,Academy of Equipment Command and Technology
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

This paper has developed a principle and method of the 3D damage environment spectrum of metallic calendar life, which is made through the operating temperature, humidity and time. It contains actual measurement and statistics of the original parameter of the operating temperature; the formation principle of equal corrosion damage spectrum; 3D spectrum formation method made of the random combination of 3 parameters (temperature, humidity and time) of operating environment. Then cases of various 3D spectrum of two regions, namely, Hai Nan and Chong Qing are provided. This 3D spectrum can form a multi-layer humidity and multi-layer temperature spectrum on the basis of calendar life calculation and test demand. Meanwhile, 3D spectrums of one-layer humidity with multi-layer temperature spectrum or 3D spectrums of any other random combination can be formed. Theoretically, since these different spectrums are under equal damage, the calendar lives of final calculation and test are the same. In this way, the inaccurate “equivalent conversion” phase in the field of corrosion can be eradicated, making the determination of calendar life more reliable. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.

Zhang F.,Academy of Equipment Command and Technology
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

This paper, through research on damage value of fatigue load spectrum, finds out that the fatigue life of metallic material is linear with the damage value of fatigue test load spectrum, namely, the fatigue life of metallic material is linear with the weight of fatigue test load spectrum. Life factor can be deduced from the regularities, and the fatigue test time of full-scale component can be reduced from life factor. From what is displayed in the life factor of existing fatigue test data research, when adding damage value on the basis of average spectrum (fatigue damage value is 50%), 58.3% damage spectrum can reduce 11% of the full-scale component fatigue test time, 75% damage spectrum can reduce 36% and 91.5% damage spectrum can reduce 50%. It comes to the conclusion in this paper as follows: for the purpose of reducing full-scale fatigue test time, load spectrum enhancement is to be employed in full-scale fatigue test, which renders the life in load spectrum enhancement. Then the life factor of sample is used to revert it to the average life under average load spectrum. This average life is then divided by the standard fatigue dispersion coefficient, which renders service life. This method reduces the fatigue test time without violating the standard fatigue dispersion values, making the determination of aircraft life economical and reliable. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.

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