Vibration Reduction For Flexible Machines Subject To External Disturbances

Flexible machines are widely utilized in the field of industrial production, aerospace and military industry. However, the vibrations of flexible systems induced during working process seriously deteriorate the positioning accuracy, efficiency, even the security and fatigue life. The system dynamics will be of more complexity, and control for the systems become more difficult, especially when the systems are suffering from external disturbance. As a consequence, the research for dynamics and vibration control of systems subject to external disturbance has an urgent necessity.The research contents are as follows. 1 dynamics and vibration control for single-mode systems under impulse disturbance, and the verifications are conducted through simulations and laboratory bridge crane. 2 dynamics and vibration control for multi-mode systems under impulse disturbance, and the validations are carried through laboratory liquid slosh test rig. 3 dynamics and vibration control for flexible machines subject to continuous disturbance, and the demonstrations are implemented using a small-scale bridge crane with distributed-mass payload.The scientific contribution of this paper is that, aimed at the influence for flexible machines caused by external disturbance, different open-loop control schemes are proposed to suppress the oscillations induced by different types of flexible systems subject to various external disturbances. The corresponding control strategies are designed, where only the frequency, damping ratio of the system, and the vibration deflection of the system caused by the disturbance are needed. There is no need to measure the system states on-the-fly, and the combined control methods will not disturb the commands given by the human operators. In addition, the combined control technologies have more robustness to the variations of the system parameters.