Damping control of sloshing in liquid container on cart with active vibration reducer having parallel linkage (Running on an uneven road by using both disturbance suppression control and frequency-dependent optimal servo)

In this paper, we consider transporting a liquid container on a cart containing an active vibration reducer, which has a parallel linkage mechanism with six degrees of freedom. Sloshing in the liquid container is generated by the movement of the cart running on an uneven road. To damp the sloshing, the liquid container is tilted and moved horizontally by using the active vibration reducer. The damping control system consists of both disturbance suppression control (DS) and a frequency-dependent optimal servo (FS). The acceleration added to the container while the cart is running on uneven roads is reduced by using DS. The residual sloshing is suppressed by using FS. In this study, only (1, 1) mode sloshing is modeled as a pendulum-type sloshing model in the control system. When a suddenly changing acceleration is added to the liquid container, higher-mode sloshing that is not modeled in the control system is easily generated and causes spillover. DS is also useful to avoid this phenomenon. The weighting matrix of the quadratic performance index for FS is efficiently determined using a genetic algorithm (GA). The amplitude of sloshing is considered for GA fitness. Further, the usefulness of the proposed control system is verified through an experiment. Using both DS and FS, the damping performance improves by approximately 79% compared to without control, and 18% compared to using FS alone.