多环闭链机构偏差传递分析及几何精度建模

Establishing geometric accuracy model is essential to conduct the accuracy prediction and inverse design of multi-closed-loop mechanism. Compared with the open-loop mechanism, accuracy modeling for multi-closed-loop mechanism is much more difficult due to the existence of negative factors like coupling and complex structure. In order to solve the above problems, a novel method of accuracy modeling is developed. First of all, the error sources are analyzed and modeled, and then two new concepts of independent loop and coupled loop are proposed to describe the loop types involved in multi-closed-loop mechanisms. Then, the relationship between loops is illustrated by the new low-layer-loop operator and sequence. Additionally, the deviation propagation principle is obtained according to the relationship. Based on the deviation propagation principle, the geometric accuracy model is built by the positional equation of the multi-closed-loop mechanism and the error space is calculated accordingly by combining the above model with the probability distribution of error sources. Eventually, the method is verified by the extendible support structure of planar SAR antenna.