Damping control of sloshing in liquid container on cart with active vibration reducer having parallel linkage (Damping control without excitation of higher-mode sloshing)

Abstract

This paper presents a control system to damp sloshing in a liquid container during its transfer in a cart equipped with an active vibration reducer having a parallel linkage with six degrees of freedom. Sloshing is generated during the liquid container's transfer. To damp this sloshing, the active vibration reducer tilts and horizontally moves the container. The reducer is controlled by a reference following control and optimal servo control. When a large liquid container is used, higher-mode sloshing that is not modeled in the control system is easily generated and causes spillover. The reference following control was adopted to avoid this phenomenon. The weighting matrix of the quadratic performance index for the optimal servo control is optimized with a genetic algorithm (GA). The amplitude of sloshing is considered for GA fitness. In this study, a cart was driven along a straight path on a horizontal plane, and only (1, 1) mode sloshing was modeled in the control system. When the optimal servo control was used alone in a damping control experiment, the active vibration reducer and liquid container vibrated violently because of spillover. On the other hand, when the optimal servo control and reference following control were used together, the liquid container did not vibrate, and sloshing in the container was damped by the active vibration reducer.