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

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.