Combining active control and synchrophasing for vibration isolation of a floating raft system: An experimental demonstration

Abstract

Vibration isolation of a floating raft system typically found in a marine application is of concern in this paper. Housed on the raft are electrical motors each driving two counter rotating shafts with eccentric masses attached. An experimental study is described in which vibration transmitted to a large-scale, laboratory-based hull-like structure is attenuated by using three measures. They are, the use of vibration isolators between the raft and the hull-like structure, adjustment of the phase of the electrical supply between the motors to minimize vibration transmitted through the isolators, and the application of an active vibration control system using hydraulic actuators placed in parallel with the isolators. The results show that this combination of measures is extremely effective at reducing the vibration transmission to the hull-like structure, and consequent reduction the sound radiation. It is more effective than the application of any of the vibration control measures applied by themselves.