混合驱动平面2自由度七杆机构的可动性分析

Mobility Analysis of Hybrid Driven Planar 2-DOF Seven-Bar Mechanisms

提出了单环运动链的可动性条件与其工作空间相结合,分析、求解平面多环、多自由度机构可动性的方法.该方法既适用于手工分析,也适用于计算机编程.利用这种方法详细地分析了混合驱动平面2自由度七杆机构的可动性问题.首先分析了七杆机构中2个五杆闭环运动链对应的2种五杆机构的可动性,得出了每一种五杆机构的2个连架杆成为曲柄的最小尺寸条件;然后分析了2种五杆机构的工作空间,得出了因环路之间的耦合而对于其可动性的进一步限制条件,从而最终得出了混合驱动平面2自由度七杆机构的3个连架杆成为无条件曲柄的可动性充分必要条件.最后给出了实例,并进行了仿真,验证了该方法的正确性.

This paper presented a general method, which is used in solving the mobility condition of planar multiloop and multiDOF mechanisms by the mobility conditions and the workspaces of planar singleloop linkages. The method is suitable for both automated and manual analysis. The mobility of hybrid driven planar 2DOF sevenbar mechanisms was analyzed. Firstly, the mobility of two fivebar mechanisms corresponding to the two fivebar closedloop kinematics chains in the planar sevenbar linkage was analyzed, and the minimum dimension conditions for the existence of the cranks in the two fivebar mechanisms were obtained. Secondly, the workspaces of the two fivebar linkages were analyzed, and the further restriction conditions for the mobility resalting from the coupling between the closed loops were obtained according to the workspace. Consequently, the mobility conditions were derived for the 2DOF planar sevenbar mechanisms with three unconditional cranks. A practical sevenbar mechanism was given and simulated.