An optimized contour parallel tool path for 2D milling with flat endmill

Although the conventional contour parallel tool path obtained from geometric information has been successful in making desirable shapes, it seldom considers the physical process concerns like cutting forces and chatters. In this paper, an optimized contour parallel path, which maintains constant MRR (material removal rates) at all times, is introduced and the results are verified. The optimized tool path is based on a conventional contour parallel tool path. Additional tool path segments are appended to the basic tool path in order to achieve constant cutting forces and to avoid chatter vibrations in the entire machining area. The algorithm has been implemented for two dimensional contiguous end milling operations with flat end mills, and cutting tests were conducted to verify the significance of the proposed method.     

A Cross-Coupled Path Precompensation Algorithm for Rapid Prototyping and Manufacturing

A cross-coupled path precompensation (CCPP) algorithm for a rapid prototyping and manufacturing (RPM) system is proposed in this paper in order to reduce the contour error resulting from the dynamic track error in the position control of the RPM system. The input of the CCPP plant is generated by a software interpolator, and the output is the compensated feedrate of the biaxial system. The precompensation amount is computed according to track errors that are estimated by mathematical models of each servo mechanism and the tangent angle at the desired point along the prespecified path. The new point acquired by the precompensation method is located in the normal direction of the original point. Simulation and experiments on the algorithm along a circular path of 200 mm in diameter are implemented. The experimental results demonstrate the advantage of the algorithm for RPM systems.     

改进A*算法的智能车路径规划研究

由于A*算法所规划的路径存在着转折次数多,路径不平滑,路径贴合障碍物和初始时刻转折角度过大等不符合车辆运动学的问题。为了解决上述问题,获得适用于智能车的优化路径,本文通过对车辆运动学建模得到车辆的约束,同时在估价函数中加入车身轮廓代价和障碍物距离代价,并将车辆约束加入到A*算法的启发函数和路径优化中,再使用贝塞尔曲线拟合转折点,使A*算法所生成的路径更加符合车辆的运动学。通过分析改进A*算法可知,改进后的算法所规划的路径更加平滑、合理且符合车辆的运动特性。     

分水岭算法应用于主动轮廓模型能量分割算法的研究

主动轮廓模型(snake模型)被广泛应用于边缘提取、图像分割等领域。该模型能对目标适当初始化,并进行自主收敛,使得能量处于极小值状态,以达到目标分离的效果。当目标初始位置敏感时,需要依赖其他机制对内部能量进行合理初始化,由于模型的非凸性,它有可能收敛到局部极值点甚至发散。将分水岭算法应用于主动轮廓模型的能量分割算法,通过改进的分水岭算法确定主动轮廓模型的初始轮廓,利用迭代完成对轮廓点周围的局部近邻点的检索,以选取更小的轮廓模型,当获得最小值时完成目标轮廓的提取。     

On the mixing flow structure of a turbulent cross jet

An experimental study on the structure of a turbulent cross jet mixing flow is presented. Diffusion rates, two and three dimensional flow structures, mean velocities turbulence intensities and turbulent shear stresses of the mixing flow were measured as varying the velocity ratio. Self-similar forms for the dimensionless mean velocity and turbulent shear stresses was obtained by correlating the measurement data resulting a remarkable agreement. It was found that the deviation gradient(a) is linearly correlated with the velocity ratio(R), and the cross section of the mixing flow is an elliptic form.     

工程图形扫描图像的自动识别

系统地介绍了一种工程图形扫描图像的识别算法,该算法以细化为核心,结合轮廓匹配和智能知识推理,较好地解决了识别中的一些关键问题,取得了较好的识别效果。     

基于轮廓线的三维重建方法的研究

在几何造型系统中引入基于轮廓线的三维重建方法作为造型手段的补充是有意义的。实际应用中得到的轮廓线数据集所具有的不同特点,使得三维重建过程中要处理的问题域被分为轮廓线的二维投影域和三维轮廓线整体信息域两种情况。对于轮廓的二维投影域 可以使用 Ｄｅｌａｕｎａｙ 三 角剖分二维任意域的算法来处理,并且在应用中对于原算法存在的缺陷进行了修正,提高了算法的健壮性;处理三维轮廓线整体信息域时,可以考虑使用基于图论描述的组合优化 的求解方法加以解决,在多个 三维重建结果中选择与定义最接近的解,是比较合理的解决问题的思路,方法中涉及优化目标和准则的选择,优化算法的运用以及三维重建结果向现有的几何造型系统使用的数据结构的转化算法等问题     

凸轮仿形车床靠模设计

通过对凸轮加工过程的数学模拟,利用原始产品凸轮外形来直接设计凸轮仿形车床的靠模。无论所提供的原始凸轮参数是以方程式形式还是列表曲线形式,都能利用计算机辅助设计（ＣＡＤ）计算出靠模实际形线上各点的坐标尺寸并转换成线切割加工机床或其他加工机床所需的加工参数,并直接加工出符合精度要求的靠模。