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为解决数控系统进行微小直线段平稳加工的问题,提出了一种拟合方法.综合了误差限制下的微小直线段长度、拐角、直线段相交点单调性等判定条件,将连续的微小直线段分割成若干区域.使用非线性最小二乘法将每一个区域内的点拟合成PH曲线,并通过模拟退火方法调整切矢量来控制拟合误差.根据区域的连接情况,将切矢量分为单向和双向两种调节方法.在模拟退火算法中,将微小直线段的斜率作为切矢量的初始值,利用细分直线的方法逐点计算弓高误差,并将此误差作为目标函数来快速进行切矢量的调整.结果表明,对微小直线段进行区域划分可以提高拟合效率.在控制弓高误差的情况下,此方法可以形成具有良好精度的光滑曲线,可以获得平稳的速度轨迹. 相似文献
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《中国航空学报》2020,33(8):2189-2203
This paper presents a novel design method of the Mission Success Space (MSS) for the evaluation on aircraft contribution effectiveness. MSS concept was proposed for giving success criterion of a mission and judging the success by conventional mission effectiveness with regards to the aircraft capabilities. This space is created by the Mission Success Function (MSF) and the original Effectiveness Index Space (EIS) where empirical equations are usually assumed to be MSFs. Based on this MSS concept, this paper firstly defines the MSS-based evaluation, then further summarizes the evaluation process of the Contribution to System-of-Systems (CSS). More importantly, based on the thought of Inverse Design (ID), a new design method of MSF is presented comprehensively analyzing aircraft’s CSS in a combat mission without using any empirical MSF. The definition of MSS based ID is given and the design procedure is sequentially introduced. Two different confrontation cases are depicted with many details as the simulation validation: Air-to-ground and Penetration. There are two design variables considered for designing MSS in the latter case while only one for the former. However, in both cases, the best design is given by evaluating the Gaussian fitting performance of CSS. 相似文献
75.
电磁式跟踪器可以测量物体的位置和姿态,但其测量精度也容易受金属环境干扰。本文根据电磁跟踪器的工作原理,给出了电磁式跟踪器姿态校正的模型,讨论了两种不同的姿态校正实现方法:插值法和拟合法,比较了两种方法的优缺点。最后,对某一金属环境进行了畸变姿态校正的试验,给出了3个不同的姿态实际值和在此金属环境下的畸变和校正结果。试验结果表明本文提出的姿态校正算法能很好地补偿金属环境引起的电磁式跟踪器姿态的畸变。 相似文献
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方汝瑢 《北京航空航天大学学报》1991,(1):61-69
针对过盈螺纹的疲劳寿命估算进行了工作,求解应力是寿命估算的第一步。为减少求解自由度,节省机时,提高效率,文章根据螺纹配合的特点,提出二次子结构法,消去内部节点,只留下配合点、加载点和边界约束点。 文章推导了子结构公式及过盈配合公式,给出了程序流程图及有限元计算结果,由结果可知,随过盈量增加,齿间应力差减小;而随过盈量增加,危险点相当应力增大。这些结果,对过盈量的选择也有参考价值。 相似文献
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Shridhar D. Jawak Alvarinho J. Luis 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
An enhanced digital elevation model (DEM) of the Larsemann Hills region, east Antarctica, is constructed synergistically by using highly accurate ground-based GPS measurements, satellite-derived laser altimetry (GLAS/ICESat) and Radarsat Antarctic Mapping Project (RAMPv2) DEM-based point elevation dataset. Our DEM has a vertical accuracy of about 1.5 times better than RAMPv2 DEM and seven times better than GLAS/ICESAT-based DEM. The accuracy is improved by validating the RAMPv2 DEM elevation by supplementing with GLAS/ICESat and DGPS survey data, when compared to that of DEM constructed by using GLAS/ICESat or RAMPv2 alone. With the use of accurate GPS data as ground control points reference elevations, the DEM extracted is much more accurate with least mean RMSE of 34.5 m than that constructed by using a combination of GLAS/ICESat and RAMPv2 as true reference. The newly constructed DEM 7 achieves highest accuracy with the least average elevation difference of 0.27 m calculated using 46 ground reference points. Available DEMs of Antarctic region generated by using radar altimetry and the Antarctic Digital Database indicate elevation variations in the range of 50–100 m, which necessitates the generation of local DEM and its validation by using ground truth. This is our first attempt of fusing multi-temporal, multi-sensor and multi-source elevation data to generate a DEM of any part of Antarctica, in order to address the ice elevation change to infer the ice mass balance. Our approach focuses on the strengths of each elevation data source to produce an accurate DEM. 相似文献