The airport runway frictional coefficient is one of the most important factors which affects
the safety of airplane's landings and take-offs under the rain or snow weather. In this paper, each kind
of factor which affects the precision of frictional coefficient measurement under the bad condition
such as snow and ice covered, rubber pollution and wet runway have been analyzed, and then
establish the model of frictional coefficient measurement. A new strategy which uses variable gain
recursion least square algorithm has been used to eliminate the error caused by the rugged runway in
the high speed measurement process, so as to assure system anti-jamming ability and fast track
capacity. Use the vertical pressure pertinence analysis to eliminate the errors caused by the runway
surfacing joint.
Ceramic matrix composites have complex structures. For exploring the impact factors of machined surface quality and material removal mechanism, its internal structure must be decoupled, and then a unidirectional C/SiC composite was designed and fabricated in this paper. Through a series of representative surface grinding experiments, the machined surface of the composites was characterized by 3D profile test, and the microscopic characteristics and material removal mechanism of the grinding surface were discussed in detail. The results showed that the fiber orientation had a significant effect on the surface quality, and the order of 3D surface roughness was longitudinal > normal > transverse. On the basis of the systematic analysis of the microscopic characteristics of the machined surface, the brittle fracture was the dominant form of material removal in grinding process. Further, combined with 3D surface profile and surface micromorphology, the effect of fiber orientation on the removal mechanism of composites was revealed. The results not only enrich the machinability and improve the surface quality of unidirectional C/SiC composites, but also provide some guidance for grinding of the woven composites.
An optical imaging based fully automatic stereo vision system for aircraft assembly online
measurement is presented and analyzed. In this system, the relative position of the two cameras can
easily calibrated by imaging an optical reference bar in different locations and orientations throughout
the measurement space according to epipolar constraint and the certified distance of the features on
the reference bar. For measurement, the system takes infrared LEDs which attached at measured
object as imaging targets, and makes use of the measurement results of these feature points space
coordinates to calculate the related positions of the assembly aircraft parts. Furthermore, using
automatic infrared LED light intensity and CCD cameras exposure time improve the calibration and
measurement accuracy. The effectiveness of the proposed system has been test by experiments.
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