平面铰链四杆机构的轨迹综合方法

于红英, 赵彦微, 许栋铭

(哈尔滨工业大学 机电工程学院, 150001 哈尔滨)



摘要:

为提高平面铰链四杆机构轨迹综合的速度与精度,提出基于B样条曲线的综合方法. 采用三次非均匀B样条曲线对连杆曲线进行拟合,将B样条曲线控制多边形各相邻两边的夹角作为连杆曲线的特征参数,将大量连杆曲线特征参数和对应的机构尺寸参数存入计算机以建立电子图谱库；当输入一定数目的有序离散数据点时,通过B样条曲线拟合得到期望曲线,提取期望曲线的特征参数；再利用神经网络将期望曲线的特征参数与电子图谱库中特征参数进行匹配,从而找到满足要求的机构,最终达到轨迹综合的目的. 设计实例表明,该方法可快速实现四杆机构的轨迹综合,综合的精度高且所提取的特征参数与连杆曲线方位、缩放比例无关,减少了图谱库的数据冗余.

关键词:  平面四杆机构  轨迹综合  连杆曲线  B样条曲线  特征参数

DOI：10.11918/j.issn.0367-6234.2015.01.007

分类号:TH112.1

基金项目:



A path synthesis method of planar hinge four-bar linkage

YU Hongying, ZHAO Yanwei, XU Dongming

(School of Mechatronics Engineering, Harbin Institute of Technology, 150001 Harbin, China)

Abstract:

To improve the speed and accuracy of path synthesis of planar hinge four-bar linkage, a path synthesis method based on B-spline curves was proposed. The method adopted cubic non-uniform B-spline curves to fit coupler curves and used angles between the two adjacent sides of the B-spline curve control polygon as characteristic parameters of coupler curves. Characteristic parameters with dimension parameters of the corresponding four-bar linkage were put into computer to establish an electronic atlas. When a certain number of ordered discrete points were given, a desired curve that passed through these points was constructed by B-spline curve fitting. Characteristic parameters of the desired curve were extracted. Then characteristic parameters of the desired curve with characteristic parameters of the electronic atlas were matched by neural networks to find the four-bar linkage which met the requirements. Ultimately the goal of path synthesis was achieved. Calculation examples show that it can quickly realize path synthesis of four-bar linkage and has high accuracy of path synthesis. And the extracted characteristic parameters have nothing to do with location and scale of coupler curve, reducing the atlas data redundancy.

Key words:  planar four-bar linkage  path synthesis  coupler curves  B-spline curves  characteristic parameters