给定两连杆运动面的Watt-I六杆机构空间解域综合方法

针对运动生成Watt-I型六杆机构综合问题,给出了一种基于空间解域的综合方法。该型机构中作为末端执行构件的连杆和一个四杆机构的连杆运动面相连,因此需要给出这个连杆运动面的位置。该方法首先综合四杆机构,然后将二杆组添加到四杆机构上。对于四位置问题,四杆机构综合可得到无穷多机构解,而对于任意四杆机构又有无穷多种添加二杆组的方法。本文以四杆机构的平面解域为基础,将综合所得无穷多六杆机构在一个有限的空间区域内表示出来,还给出一种能有效判断Watt-I型六杆机构回路和分支缺陷的方法。通过对综合所得无穷多机构解进行判断,建立六杆机构去除回路分支缺陷的空间可行域。空间解域的应用使设计者能够从整体上把握六杆机构的可行解的全部解空间,从而使获得附加更多条件的最优机构成为可能。

Synthesis of WattI Six-bar Linkage Based on Spatial Solution Region for Given Two Coupler Planes

This paper addresses the synthesis problem of Watt-I six-bar linkage motion generation, and introduces a novel and convenient synthesis approach. The coupler link used as end-effector of Watt-I is connected to a coupler plane of a four-bar linkage, so that the designers need to give the task positions of these two coupler planes. With the method, a four-bar linkage is synthesized firstly, and then a dyad is attached to this four-bar linkage to obtain a six-bar linkage. For four-precision-position problems, four-bar motion generation can produce infinite number of solutions. And for any selected four-bar linkage, we can present an equation of pivot curve that each point on this curve can generate a satisfactory dyad. Based on the planar solution region of four-bar linkage, an infinite number of synthesized six-bar linkage solution can be expressed in a finite spatial region. In addition, the paper still puts forward a circuit and branch defects distinguish method for Watt-I six-bar linkage. The feasible spatial mechanism solution regions without any defects are obtained by using the distinguish method. Application of the spatial solution regions makes designers to be able to understand the information of the synthesized six-bar linkages on the whole, and makes it possible to get the optimal solution that attached more design requirements.