基于连杆机构旋转法则的平面单环闭链结构装配误差不确定性分析

The link deviation, assembly constraint error and joint clearance are the major error sources, which affect the assembly accuracy of planar single-closed-loop mechanisms. However, the randomness of joint clearance results in the accuracy uncertainty of the planar single-closed-loop mechanism. In order to predict the assembly accuracy and obtain the error bound, two assembly components, single-fixed link and two-connected link, are proposed and their error models are established by analyzing the assembly property of a planar four-bar single-loop mechanism. And accordingly, the error modeling of assembly error of the single-loop mechanism without considering joint clearance is firstly completed. Then the uncertainty analysis model of assembly error of the planar single-loop mechanism is built by introducing the rotatability law of the linkage, in which the joint clearance is regarded as a ‘short link’. In addition, the method of calculating the bound of assembly error is given. At last, the feasibility and utility of the method proposed above are verified by a numerical example of the planar five-bar single-loop mechanism.