用CAD约束和尺寸驱动技术分析平面机构的运动

提出用CAD约束和尺寸驱动技术分析平面机构的运动。采用CAD的几何约束、尺寸约束、尺寸方程和尺寸驱动技术，构造一些典型平面连杆模拟机构。给定输入件的驱动尺寸，确定输出件被驱动尺寸，求出输出杆件运动点的轨迹。利用CAD软件的记录功能，得到机构输出点轨迹数据；再用Excel软件拟合轨迹数据，得到轨迹拟合曲线和拟合方法；最后求解机构输出运动件的速度和加速度方程。计算机模拟结果表明，文中方法不仅具有简单、快捷、直观、求解精度高和重复性好的优点，而且可以完成复杂机构和多自由度机构的运动分析，为机构的运动分析提供更有效的工具。

Kinematic Analysis of Constraint and Dimension Driven Planar Mechanism

By using the constraint and dimension driven concept in CAD software, some type of simulation for planar mechanisms is created. The given driving dimension of input link is modified, and the driven dimensions of output link are changed automatically. The displacements of output link relative to the motion of input link are recorded and fitted into continuous trajectory by using Excel software. Then the velocity and acceleration are derived from the equation of trajectory. The results of computer simulation and fitted equation show that simulation of constraint and dimension driven mechanism is not only straightforward and highly efficient, but also has the advantages of ensuring accuracy and repeatability.