Lunar Exploration and Aerospace Engineering Center

Beijing, China

Lunar Exploration and Aerospace Engineering Center

Beijing, China
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Jiang L.,China Institute of Metrology | He Y.,China Institute of Metrology | Wang D.-W.,China Institute of Metrology | Liu K.,China Institute of Metrology | Wu W.-R.,Lunar Exploration and Aerospace Engineering Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Thermal deformation measurement of the high-speed aircrafts under the high temperature is significant for reliability assessment, life prediction, and safety design for the materials and structures. This paper presents a digital image correlation method to accurately measure the full-field thermal deformation of composites under the environment of high temperature. First, real-time deformation images of experimental objects under different loads are acquired with CCD cameral. Based on the digital speckle correlation theory, the bilinear interpolation algorithm is employed to measure the thermal deformation. Last, the comparative analyses on measurement results by the proposed and traditional methods are conducted, as well as factors impacting measurement errors are analyzed. © 2013 SPIE.


Ning X.,Beihang University | Ning X.,Science and Technology on Inertial Laboratory and Fundamental Science | Liu L.,Beihang University | Fang J.,Beihang University | And 3 more authors.
Aerospace Science and Technology | Year: 2013

Navigation methods of lunar rovers like inertial navigation system (INS), dead reckoning and visual odometry must be provided with the initial navigation parameters such as initial position and attitude. The accuracy of these initial navigation parameters has a significant impact on the overall navigation accuracy. Taking INS as an example, on the Earth, initial position can be obtained from global positioning system (GPS) or other ground facilities, and initial attitude can be obtained through initial alignment. However, there is no GPS on the lunar surface, and the lunar rotation rate is too small to execute alignment. For solving this problem, a new initial position and attitude determination method based on INS/CNS (celestial navigation system) integration is presented in this paper. Star altitude error caused by the biases of accelerometers is considered and its corresponding measurement equation is established accurately for the first time. The horizontal velocity errors, starlight vectors and star altitudes are used to estimate the initial position and attitude by an unscented Kalman filter (UKF). Furthermore, the advantage of this new method is that the INS sensors errors can be estimated accurately. Semi-physical experiments show that higher estimation accuracy is achieved by this new method compared with that of the traditional INS alignment method and INS/CNS initialization methods. These results demonstrate that it is a promising and attractive method to provide the initial position and attitude for lunar rovers. © 2013 Elsevier Masson SAS. All rights reserved.


Wu W.,Lunar Exploration and Aerospace Engineering Center | Wu W.,Beihang University | Ning X.,Beihang University | Ning X.,Science and Technology on Inertial Laboratory | And 2 more authors.
Journal of Systems Engineering and Electronics | Year: 2013

In the future lunar exploration programs of China, soft landing, sampling and returning will be realized. For lunar explorers such as Rovers, Landers and Ascenders, the inertial navigation system (INS) will be used to obtain high-precision navigation information. INS propagates position, velocity and attitude by integration of sensed accelerations, so initial alignment is needed before INS can work properly. However, traditional ground-based initial alignment methods cannot work well on the lunar surface because of its low rotation rate (0.55°/h). For solving this problem, a new autonomous INS initial alignment method assisted by celestial observations is proposed, which uses star observations to help INS estimate its attitude, gyroscopes drifts and accelerometer biases. Simulations show that this new method can not only speed up alignment, but also improve the alignment accuracy. Furthermore, the impact factors such as initial conditions, accuracy of INS sensors, and accuracy of star sensor on alignment accuracy are analyzed in details, which provide guidance for the engineering applications of this method. This method could be a promising and attractive solution for lunar explorer's initial alignment.


Jiang L.,Beijing Institute of Technology | Wu W.-R.,Beijing Institute of Technology | Wu W.-R.,Lunar Exploration and Aerospace Engineering Center | Zhang Z.-J.,Beijing Institute of Technology | And 2 more authors.
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2013

As Micro Processing Technology Matching based Micro Image Edge Detection method (MPTM-MIED) developed by previous research can not automatically detect the micro image edges of micro accessories in real time, this paper designs the MPTM-MIED based on BP neural network again. Then, it proposes a novel Automated Micro Image Edge Detection method (AMIED) to extract edges of micro images automatically. To verify the feasibility of the proposed method, the edges of micro images from micro accessories fabricated by four different methods are extracted by AMIED and the sizes of micro accessories by line cutting are measured. Obtained results show that the detected edges by AMIED and MPTM-MIED are almost the same, and the AMIED has better edge-connectivity as compared with some common detection algorithms. Furthermore, the analysis results indicate that the measured sizes by AMIED are almost equal to those measured by MPTM-MIED and they are more close to those measured by the universal tool measuring microscope as compared with that of the Canny algorithm. Because the method has no more need of selecting edge transition region, it improves the detection speed and can measure the sizes of micro accessories in real time.


Liu Z.-Q.,China Academy of Space Technology | Liu Z.-Q.,Beijing Institute of Technology | Wang L.-L.,Beijing Institute of Technology | Wu W.-R.,Beijing Institute of Technology | And 2 more authors.
Yuhang Xuebao/Journal of Astronautics | Year: 2015

Based on the analysis of resistance forces and driving torque of spiral drill bit and lunar failure field, mechanical models of drill bit are established, models which are not only considered with pressure and friction between the lateral surfaces of cutter and lunar soil, but also considered with the effect of the surface load of lateral failure surface on circumferential torque, total power consumption of drill bit and failure distance of lunar soil. The models are validated by simulation results and experiment results. Mohr-Coulomb model suitable for deep lunar soil is applied to simulation process, which is better consistent with the real situation that internal friction angle is greater than 22℃. The rules of effect of drill bit structure parameters on power consumption and failure distance of cutter are obtained by models above. Minimal power consumption of drill bit is selected as an optimization object, and structure parameters of the drill bit are optimized by using genetic algorithm. Optimizations results reduce the risk of drilling failure. Present paper provids an approch for design of drill bit of automatic drill sampling mechanism. © 2015, Editorial Dept. of JA. All right reserved.


Liu Q.,Beijing Institute of Technology | Wu W.-R.,Beijing Institute of Technology | Wu W.-R.,Lunar Exploration and Aerospace Engineering Center | Zhang Z.-J.,Beijing Institute of Technology | Jin X.,Beijing Institute of Technology
Journal of Beijing Institute of Technology (English Edition) | Year: 2014

A new profile model based on multi-scale asperities is developed and contact error is calculated. After stratified sampling, the model can get the distribution law of entity points on each cross section. Asperity radius of curvature is estimated by the relationship between circle radius and the section interval. Contact error is related to surface form error. A model equation of contact error plane is calculated through a method based on static equilibrium theory. Three contact asperities which determine the contact error plane on the rough surface are studied. The simulation results show that contact error can be accurately calculated according to the profile error model. © Copyright


Wang L.-L.,Beijing Institute of Technology | Wang L.-L.,China Academy of Space Technology | Liu Z.-Q.,Beijing Institute of Technology | Liu Z.-Q.,China Academy of Space Technology | And 3 more authors.
Yuhang Xuebao/Journal of Astronautics | Year: 2015

Based on the analysis of the output of lunar soil principle and the (resistance moment) output of lunar soil resistance of spiral drill stem, the impact of lunar soil in the spiral groove regolith on drill stem driving torque, the valued field of helix angle and axial drilling power drill stem are considered, and models of drill stem driving torque, axial loading force and power consumption model are established, then effects of structural parameters such as the outer diameter of drill stem, the depth of spiral groove, groove width ratio and helix angle on the driving torque and the axially loading force of drill stem are analyzed by using the above models, and the rule of effect of structure parameters on the driving torque and the loading axially force of drill stem is obtained. Both mass and power consumption of drill stem are selected to be two-objective optimization, outer diameter of drill stem, depth of spiral groove, groove width ratio, helix angle and other parameters are taken as design variables, and the structure parameters of drill stem are optimized by using genetic algorithm. The power consumption is reduced by 31.8% and the mass of drill stem is reduced by 23.3% after optimizations, thus reducing the risk of drilling and providing a theory basis for the design of automatic drill sampling mechanism. ©, 2015, China Spaceflight Society. All right reserved.


Qiao D.,Beijing Institute of Technology | Cui P.,Beijing Institute of Technology | Wang Y.,Beijing Institute of Technology | Huang J.,China Academy of Space Technology | And 2 more authors.
Advances in Space Research | Year: 2014

Chang'E-2 (CE-2) has firstly successfully achieved the exploring mission from lunar orbit to Sun-Earth L2 region. In this paper, we discuss the design problem of transfer trajectory and at the same time analyze the visible segment of Tracking, Telemetry & Control (TT&C) system for this mission. Firstly, the four-body problem of Sun-Earth-Moon and Spacecraft can be decoupled in two different three-body problems (Sun-Earth + Moon Restricted Three-Body Problems (RTBPs) and Earth-Moon ephemeris model). Then, the transfer trajectory segments in different model are computed, respectively, and patched by Poincaré sections. The full-flight trajectory including transfer trajectory from lunar orbit to Sun-Earth L2 region and target Lissajous orbit is obtained by the differential correction method. Finally, the visibility of TT&C system at the key time is analyzed. Actual execution of CE-2 extended mission shows that the trajectory design of CE-2 mission is feasible. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved.


Wu W.-R.,Lunar Exploration and Aerospace Engineering Center | Wu W.-R.,Beijing Institute of Technology | Jiang L.,Beijing Institute of Technology | Zhang Z.-J.,Beijing Institute of Technology | Jie D.-G.,Lunar Exploration and Aerospace Engineering Center
Yuhang Xuebao/Journal of Astronautics | Year: 2012

In order to improve accuracy and efficiency for Roundness Error Evaluation (REE) in micro part measurements, a novel algorithm based on Computational Geometry is developed in this paper. In the algorithm the convex theory hull of Computational Geometry is used to identify relevant data for the following REE. Compared with traditional REE methods, the identification process can improve computational performance significantly. Based on the identification process, three optimized algorithms, Minimum Circumscribed Circle (MCC), Maximum Inscribed Circle (MIC) and Minimum Zone Circle (MZC), are also designed. Simulation results of REE show that the efficiency of REE is enhanced obviously.


Wang L.,Beijing Institute of Technology | Wang L.,China Academy of Space Technology | Liu Z.,Beijing Institute of Technology | Liu Z.,China Academy of Space Technology | And 3 more authors.
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

In respect of the sampling process of the hollow-external-screw drill stem for automatic drilling sampling mechanism, the mathematical models between the cohesive force, friction coefficient of lunar-soil and the lunar-soil depth are built separately; the relationships between drill stem kinematic parameters (drill stem drilling speed and rotary speed) and the structural parameters (drill stem spiral angle, outside diameter, groove width ratio and spiral grooved depth in the drilling process) are also established. These models take into account not only the characteristics of lunar-soil physical and mechanical parameters changing with drilling depth and drill stem drilling convected velocity, but also the shear resistance among lunar-soil infinitesimals. Such approach subjects the drill stem's parameters to the job requirement of lunar drilling sampling. The effectiveness of the model is validated and the analysis of the influence of the drill stem structural parameters on its kinematic parameters is conducted with the models. As a result, the influence law of the drill stem structure parameters on its kinematic parameters is revealed, and the best value range of drill stem structure parameters is obtained. Taking the minimum value of the ratio between the drill stem rotary speed and drilling speed as optimal object and the structural parameters as design variables, based on genetic algorithm, the structural parameters of drill stem are optimized. Before and after optimization, the ratio of drill stem rotary speed to drilling speed is reduced by 13.8%. The research results will reduce the energy consumption and improve the efficiency, which provide a theoretical basis for the design of automatic drilling sampling mechanism. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.

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