瞬心无穷远直线导向机构通用综合方法研究

General Synthesis Method of Straight-Line Mechanism With Instant Center at Infinity

为了解决瞬心无穷远这一类特殊直线导向机构的综合问题,提出一种通用的设计方法,适用于铰链四杆机构、滑块机构和摇块机构。给出了机构综合推导公式和综合示例。给定理想直线和机架一定铰点,设计变量两两组合,可以得到无穷多机构解,将其表示在解域中,并绘制出设计者需要的机构运动学属性图。通过施加对机构及连杆曲线的约束,计算可行解域,最后设定寻优目标,就可自动筛选出最优直线机构。该方法不仅解决了瞬心趋于无穷远时铰链四杆直线导向机构综合的问题,而且推广至含移动副机构综合。由示例表明,综合过程较为直观便捷,实用性强,可为设计者提供更多种选择。

A universal design method for synthesis problems of mechanisms with an instant center at infinity is presented in this paper,including the synthesis of the four-bar linkage,slider linkage and rocking-block linkage.In addition,the synthesis formulas are derived and an example of the mechanism optimization is given.Given the expected straight line and a fixed point,an infinite number of mechanism solutions can be obtained by combining design variables in pairs,which can be expressed in the solution region.The kinematic properties of the mechanism that are of interest to the designer are drawn.The kinematic constraints on the mechanism and coupler curve are imposed,all feasible solution mechanisms are calculated.Finally,the optimal solution can be screened by setting an optimization aim automatically.This method not only solves the synthesis problem of the four-bar linkage in special case,but also extends to the synthesis of mechanism with sliding pairs.The example shows that the synthesis process is convenient and practical,which can provide more choices for designers.