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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. Source


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. Source


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 Source


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. Source


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. Source

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