The Study Of Active Vibration Control Technique Based On Mechanical Actuator

Using mechanical actuator in active ship vibration control especially active vibration attenuation is an important research topic in the field of vibration control at present. Active vibration attenuation technique is a method that can reduce or attenuate vibration by calculating or measuring characteristic of bad vibration of vibration sources or objects controlled and generating a vibration which has same magnitude and frequency, contrary phase with bad vibration, using actuator with energy resource. It is proved that active attenuation devices installed on ships is an effective way to reduce ship vibration by a lot of research and application overseas. Some aspects of active ship vibration control, such as vibration attenuation theory, force-adjustable mechanical actuator, control system, control algorithms, etc., ate thoroughly investigated in this dissertation. The main contents are:The basic principles of active attenuation are formulated. The math models of vibration attenuation are founded. Application feasibility of active vibration attenuation technique to ship vibration control is discussed by analyzing characteristic of ship vibration and researching data of testing ships.A force-adjustable mechanical actuator has been firstly developed to reduce ship structural vibration of a single harmonic component of main engine rotating frequency domestic. The actuator generates a unidirectional sinusoidal control force using vectorial sum of centrifugal forces of two counterrotating unbalance masses. The adjustable-force generation during its operation has been embodied by the mechanism to adjust the eccentric distance of the mass using a link system. It can be applied to active vibration attenuation and active vibration absorber.A control system applied to active ship vibration attenuation has been devised based on force-adjustable mechanical actuator. It is composed of QMAC motion controller and industry control computer. It can generate needed control force using force-adjustable mechanical actuator by controlling motions of two servo motors accurately.Based on practical needs of mechanical actuator and its control system, originated from ship vibration theory and autocontrol theory, three creationary control algorithms have been devised to auto- matically detect the optimal phase and eccentric distance of the mechanical actuator. They are called phase adjusting analytic algorithm, dynamic compensating self- optimizing algorithm and neural network algorithm. These algorithms can be applied without prior identification of the dynamitic characteristics of ship structures. Their accuracy and practicality have been proved in Simulation tests of active vibration attenuation using MATLAB. Three algorithms can be used solely or cooperatively in mechanical actuator.A vibration attenuation test-bed has been found based on the characteristics of ship structures vibration. The main parts are manufactured by ourselves, such as structure controlled and electric vibration exciter. After vibration characteristic of the text-bed was measured, a series of active vibration attenuation experiments have been done on the test-bed using force-adjustable mechanical actuator and its control system, phase adjusting analytic algorithm, dynamic compensating self-optimizing algorithm, neural network algorithm. The experimental results proved that it is advanced and effectual for force-adjustable mechanical actuator and its control system, control algorithms.