刺绣机含间隙针杆机构的运动稳健性分析与优化设计

Position robust analysis and design optimization of needle bar mechanism with joint clearance of automatic embroidery machine

建立了平面连杆机构运动副间隙的分析模型,分析了回转副的偏心对机构位移的影响,导出了考虑间隙时构件有效杆长的计算公式。同时考虑杆长误差和运动副间隙对针杆位移精度的影响,用极值法和随机模拟方法对针杆位移误差进行了计算,得出了考虑间隙时针杆位移的波动区间。以极小化针杆位移误差和位移标准差为目标,建立了针杆机构的稳健优化设计模型,并用遗传算法进行了求解。结果表明,在不增加制造成本的前提下,优化后针杆机构的运动误差和位移的均方差明显减少,运动精度的稳健性得到明显改善。

The revolute joint with clearance of planar linkage mechanism is modeled to analyze the impact of revolute-joint eccentricity on the position of mechanism.The calculating formula of equivalent length of planar linkage mechanism with revolute-joint clearance is derived.The worst case method and the random simulation method are used to calculate the position error of needle bar when the length error of component and kinematical pair clearance are taken into account.The variation intervals of the needle bar position are obtained and compared with other solutions.The mathematical model for the robust design optimization of needle driving mechanism is established to minimize the variation and the standard deviation of needle bar position.This model is solved by using genetic algorithm.The results show that the variation and standard deviation of needle bar position are obviously reduced without increasing the cost of manufacture,and the robustness of the needle bar position of needle driving mechanism is obviously improved.