刺绣机针杆机构运动精度的灵敏度分析

Sensitivity analysis on kinematic accuracy of needle bar mechanism in embroidery machine

为提高刺绣机针杆机构的运动精度及其稳健性,采用Sobol'方法对该机构的运动精度进行全局灵敏度分析,并在此基础上对针杆机构进行优化设计。首先,同时考虑杆长的制造误差和运动副间隙对针杆位移的影响,建立了针杆机构运动精度的数序模型。然后,采用Sobol'方法求出该模型中14个随机变量的总灵敏度,并根据灵敏度的排序确定出4个重要因素和1个关键因素,其中连杆长度是关键因素。通过减少关键因素的制造误差,进一步优化针杆机构的运动精度。结果表明,优化后针杆机构位移误差的均方差明显降低,运动精度的稳健性得到了提高。

In order to improve the kinematic precision and its robustness of the needle bar mechanism in the embroidery machine,the global sensitivity analysis on the kinematic accuracy of this mechanism was carried out by using the Sobol′method.On the basis of global sensitivity analysis,the optimum design of the needle bar mechanism was carried out.Firstly,considering the effect of rod manufacturing error and kinematic pair clearance on the needle bar displacement,a numerical model for kinematic accuracy analysis of needle bar mechanism was established.Then,the total sensitivity of 14 random variables was obtained by using the Sobol′global sensitivity analysis method,and 4 important factors and 1 key factor were determined according to the order of sensitivity,in which the length of the connecting rod is the key factor.By reducing the manufacturing error of the key factor,the kinematic accuracy of the needle bar mechanism was further optimized.The results show that the standard deviation of the displacement error of the needle bar mechanism is reduced obviously,and the robustness of the motion accuracy is improved.