【作者】 顾新春；

【导师】 朱家诚；

【作者基本信息】 合肥工业大学 ， 机械设计制造及自动化， 2007， 硕士

【摘要】 由于四连杆曲线类型的复杂性,数学上几乎无法准确给出连杆曲线的公式,而四连杆曲线在机械工程领域的应用几乎无处不在,因此对于四连杆曲线的研究历来受到许多学者的关注。目前采用人工神经网络算法对连杆曲线的研究受到了广泛关注,本文将引入神经网络算法中的BP网络算法来对四连杆曲线进行分析。本文首先描述了四连杆曲线的分类,然后针对不同分类的连杆曲线进行了分析,得出了连杆曲线与四杆参数存在着一定的非线性关系。借助Delphi编制的软件可将四连杆参数准确地绘制出对应分类的连杆曲线,再利用matlab.提取了连杆曲线的数字化特征值——不变矩,建立了四连杆参数数值与对应的连杆曲线不变矩之间的样本库。通过样本库,以不变矩作为输入量,利用BP网络算法得出了连杆曲线与四杆机构参数之间的权值系数。最终借助权值系数得到一条待分析曲线对应的四杆机构参数。由于不变矩具有放大,缩小的不变性,所以,当待分析的曲线与BP计算后得到的曲线形状相似时,则可根据对应的比例获得相应的四连杆参数。本文以卵圆形曲线和8字形曲线等两条待求四连杆曲线为例,采用上述方法对曲线进行了处理,所得四连杆曲线的相对误差一般能满足设计,从而验证了BP网络算法对于卵圆形曲线和8字形曲线与四连杆参数之间均具有较好的非线性关联,也就验证了本方法在连杆曲线综合方面具有一定的可行性、实用性。更多还原

【Abstract】 The formula of coupler curve almost can’t be accurately given because of the complex of types of Four-bar coupler curver, while the application of Four-bar coupler curver in mechanical engineering is widely used. So the study to Four-bar coupler curver is noticed by many experts all through the ages. Now analyses of the Four-bar coupler curve based on the algorithm of artificial neural networks is widely noticed. The study of this paper on Four-bar coupler curver will bring the algorithm of BP neural network(NN).At first this paper gives the types of Four-bar coupler curver, and then analyses against the different classifications of the curve. We can conclude there is a certain nonlinear relationship of Four-bar linkage curves and the parameters of Four-bar linkage. With Delphi software compiled the Four-bar linkage parameters can accurately draw a corresponding link curve, and with Matlab software digital characteristics (non-moment) of Four-bar linkages can be extracted, the sample database are built by the parameters of Four-bar linkages and the the corresponding characters (non-moment)of the Four-bar coupler cures. By this sample database, and characters of Four-bar coupler curve as the input, power coefficient of the parameters of Four-bar linkages and the corresponding characters can be get. At last the parameters of Four-bar linkages corresponding characters (non-moment)of the Four-bar coupler cure can be calculated. As the non- moment zoom invariance, therefore, when the question curves and the Four-bar coupler curve which be calculated by the algorithm of BP neural networks are similar, the parameters of Four-bar linkages can be get by corresponding proportion.Oval shaped curve and 8-type curve for two Four-bar linkages that curve will be used for the example of this paper. The curves are dealt with by using the methods which have been given before. The relative error of Four-bar linkage curves meet with the requirements of design in a general way. This method verifies better nonlinear by using the BP network algorithm to the 8-type curve (or oval shaped curve) and Four-bar linkage. At the same time this method also proved this way has a comprehensive feasibility, practicality.更多还原