Optimal design of the needle bar and thread take up lever mechanism using a multi-objective imperialist competitive algorithm

This work deals with the multi-objective design optimization of a needle-bar-and-thread-take-up-lever (NBTTL) mechanism used in sewing machines. Two criteria are considered simultaneously, i.e., vibration (evaluated through the needle jerk) and the quality of the stitch formation given by the coupler tracking error. Indeed, the needle jerk and the coupler tracking error are minimized in order to reduce the sewing machine vibration and ensure a proper stitch formation. For this purpose, the multi-objective imperialistic competitive algorithm (MOICA) is used to find the optimal link lengths of the NBTTL mechanism. The obtained results show that the optimized mechanism has 73% less needle Jerk than the one for the Juki 8700, while keeping a low coupler tracking error (less than 7%).