共查询到17条相似文献,搜索用时 140 毫秒
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含有C-C二副杆的空间机构自适应运动综合方法 总被引:1,自引:1,他引:0
提出了用球面像曲线和空间腰曲线来描述空间直纹面的几何性质,进而将含有C-C二副杆的空间机构近似运动综合转化为球面像曲线和空间腰曲线的自适应拟合问题,给出了近似球面像圆点、近似圆柱面腰点等定义,构造了球面像曲线的自适应圆锥拟合和空间腰曲线的自适应圆柱面拟合的统一数学模型,建立了含有C-C二副杆的空间机构近似运动综合的自适应方法,并给出了通用的鞍点规划求解方法,算例表明该优化方法是收敛的、有效的。 相似文献
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讨论了球面四杆机构函数综合中精确点的选择问题,以减小最大综合误差为目标,提出了一种新的精确点优化选择方法。利用球面四杆机构函数综合的封闭形式解,通过引入比例系数,推导了结构偏差的方程式,并构造了精确点选择的优化数学模型。利用数值插值的方法对结构偏差方程式进行了分析,给出了优化模型的初始解,并采用分形算法求得了全局最优解。通过对数值实例的计算和对结果的分析,验证了新方法的有效性。 相似文献
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球面四杆机构函数综合的带修复策略可行性规则差分进化算法 总被引:1,自引:0,他引:1
根据杆长限制条件,建立约束方程,进而得出求解球面四杆机构函数综合问题的非线性方程组,并将该方程组的求解转化为鞍点规划问题。以杆长协调、传动角、避免乱支缺陷等为约束条件,提出球面四杆机构近似函数综合的约束优化模型,再应用差分进化(Differential evolution,DE)算法求解该问题。在定义约束违反度和弱、强不可行解的基础上,提出处理约束条件的改进可行性规则,形成求解约束优化问题的可行性规则差分进化(Feasibility-rule-based DE,FRDE)算法。应用4个benchmark约束优化问题测试FRDE算法的优化性能,结果表明,其可靠性和稳健性指标优于对比算法。面向机构优化综合问题,将修复策略融入FRDE算法,发展为带修复策略的FRDE算法(Feasibility-rule-based DE algorithm with repair strategies,FRRDE)。给出5个函数综合实例。结果显示,优化模型和方法可行有效,且FRRDE算法的优化性能好于对比算法。 相似文献
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渐开线的绘制和加工远不如圆弧方便。齿轮和花键生产技术上的需要,促使人们寻来渐开线齿廓的近似圆弧。本文指出:当今流行于曲线拟合的最小二乘法未必能得到最优拟合。在具体分析二者之间的偏差后,提出一个能使偏差迅速趋于最小的目标函数,从而把拟合精度推进了一大步,找到了最优近似圆弧。文中还给出按电算结果绘制的实用图表和三则应用实例。 相似文献
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用广义逆矩阵进行平面四杆机构的近似函数综合 总被引:1,自引:0,他引:1
提出了平面四杆机构近似函数综合的一种新方法,其基本思路是:首先利用广义逆矩阵将四杆机构的近似函数综合方程组转化为一个二元二次方程组,然后采用消元法得到一个一元三次方程,由此可得机构近似运动综合方程组的所有解。为平面四杆机构近似函数综合提供了高效的实用方法。 相似文献
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球面四杆机构函数综合的傅立叶级数法 总被引:1,自引:0,他引:1
从球面四杆机构的输入角与输出角的函数关系入手,借助傅立叶变换这一数学工具,发现了输入输出函数与基本尺寸型的关系。在此基础上建立了包含148995组曲柄摇杆机构和490545组双曲柄机构基本尺寸型的球面四杆机构输出函数特征参数的数值图谱库。通过建立的球面四杆机构输入输出函数的数值图谱库,实现了球面四杆机构的函数综合。为提高综合所得机构的精度,采用了遗传算法对综合结果进行了优化,并给出了相应的算例证明了本方法的有效性。 相似文献
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球面四杆机构的空间模型及尺寸型 总被引:5,自引:1,他引:5
基于特征球面四杆机构的概念,将球面四杆机构分为三类,并建立机构的尺寸型空间模型。每个空间模型可划分为若干个子区间,每个子区间都对应着一族球面四杆机构。按本文提出的尺寸型表示方法,可在全封闭图面内表示球面四杆机构的尺寸型,并在其上绘制出有工程应用价值的机构性能图谱。 相似文献
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The forward-displacement analysis of spherical parallel robots (SPRs) is revisited. A robust approach, based on the input–output (I/O) equation of spherical four-bar linkages, is proposed. In this approach, the closed-loop kinematic chain of a SPR is partitioned into two four-bar spherical chains, whose I/O equations are at the core of the analysis reported here. These equations lead to a trigonometric equation in the joint angles, which is solved semigraphically to obtain the joint variables for the determination of the moving plate orientation. Examples are included to demonstrate the application of the method. 相似文献
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用快速傅里叶变换进行球面四杆机构连杆轨迹综合 总被引:4,自引:0,他引:4
根据给出的球面四杆机构连杆轨迹的数学模型,借助傅里叶级数这一数学工具,对连杆轨迹的谐波成分进行理论分析,发现连杆轨迹的谐波成分与其相应转角函数谐波特征参数和机构尺寸参数的内在联系。确定球面四杆机构的基本尺寸型,在此基础上建立包含600余万组机构基本尺寸型的球面四杆机构连杆轨迹的谐波特征参数数值图谱库。利用傅里叶级数理论建立球面四杆机构处于空间任意位置时连杆曲线的数学方程,推导出计算机构的实际安装尺寸、连杆上点的位置和机构安装尺寸参数的理论计算公式。利用建立的谐波特征参数数值图谱和推导的理论公式解决了球面四杆机构的轨迹综合问题,最后给出算例证明本方法的可行性。 相似文献
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Presented in this article is the method of optimum synthesis of mechanisms satisfying derivatives of the generated displacements along with the displacements at a discrete set of design positions. Although the method is illustrated for the synthesis of four-bar function generators, where the first and second derivatives of the generated functions are also generated at all or some of the design positions in order to increase the efficiency of approximating the generated function, the method is readily applicable for the synthesis of mechanisms to generate paths and rigid-body positions satisfying path velocities, path accelerations, and rigid-body angular velocities. Mechanisms of precision control units, vibratory feeders and conveyors, transfer robots and mechanical arms, and linkages replacing noncircular gear drives require the application of such synthesis techniques involving derivatives of the generated displacements. 相似文献
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W Meyer zur Capellen 《Mechanism and Machine Theory》1976,11(4):277-284
In discussing the laws of motion of a specific linkage with variable parameters, the limiting or exceptional cases where a change-point position becomes possible is frequently of interest. In this paper it is explained how to obtain the ratios of velocities for spherical four-bar linkages with change-point positions. The positions of the relative pole axes 31 and 20 (i.e. motion of the input link with respect to the output link or motion of the coupler with respect to the fixed link) are of special interest. Passing to the limit leads to the corresponding plane four-bar linkages. Two examples, one linkage from the plane and one from spherical kinematics, conclude the paper. 相似文献
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M. Khorshidi M. SoheilypourM. Peyro A. AtaiM. Shariat Panahi 《Mechanism and Machine Theory》2011,46(10):1453-1465
Responding to an increasing demand for mechanism synthesis tools that are both efficient and accurate, this paper presents a novel approach to the multi-objective optimal design of four-bar linkages for path-generation purposes. Three, often conflicting criteria including the mechanism's tracking error, deviation of its transmission angle from 90° and its maximum angular velocity ratio are considered as objectives of the optimization problem. To accelerate the search in the highly multimodal solution space, a hybrid Pareto genetic algorithm with a built-in adaptive local search is employed which extends its exploration to an adaptively adjusted neighborhood of promising points. The efficiency of the proposed algorithm is demonstrated by applying it to a classical design problem for one, two and three objective functions and comparing the results with those reported in the literature. The comparison shows that the proposed algorithm distinctly outperforms other algorithms both quantitatively and qualitatively (from a practical point of view). 相似文献