Analysis of dynamic model of a top-loading laundry machine with a hydraulic balancer

Abstract

This paper analyzes the vibration characteristics of a top-loading-laundry machine with a hydraulic balancer. For numerical simulation of the laundry machine dynamics, its dynamic model is introduced, where ball models are employed to represent the dynamics of a hydraulic balancer. For verification and validation of the established dynamic model, the accelerations of an actual laundry machine are obtained from three-axis accelerometers attached at the upper part and the lower part of a tub respectively. Since the signal-to-noise ratio of the measured acceleration data is small due to the electric noise induced by the driving motor, and a wavelet de-noising method is applied for low-pass filtering without a phase shift. The dynamic model of a top-loading-laundry machine is developed by Newtonian mechanics. From the extensive simulation studies, it turned out that the number of balls, gyration radius of a ball, and damping coefficient between a ball and the basket are the most important three design parameters. The accuracy of the proposed dynamic models is verified based on root-mean-square error and the three design parameters were analyzed. Gyration radius of a ball, which is the most critical parameter, is estimated by the relationship with positions of the unbalanced masses and the dynamic model with the estimated gyration radius of a ball is validated by experiment.