Research Of Feedforward Control On Maglev Floating Raft Vibration Isolation System

It is a major issue to improve the acoustic stealth performance in current submarine researches. How to achieve the low-frequency vibration isolation of submarines effectively is vital to the improvement of the acoustic stealth ability. The floating raft vibration isolation technology is developed from two_stage isolation technology and it is a new technology, effective vibration isolation performance and great shock requirement, applied in vibration and noise reduction of the ship power equipment. Bearing parameters are adjusted dynanically and energy transmission of the structural vibration is suppressed effectively by active vibration isolators.Hence, the active vibration isolation system has good performance of the low-frequency vibration isolation. The acoustic stealth ability would be improved by the active floating raft vibration isolation system.The adaptive feedforward control is simple and stable, which can effectively suppress the harmonic vibration as long as the frequency of the vibration source was extracted. What’s more, the low-frequency vibration on submarines is mainly the harmonic vibration generated by motors or diesel engines. The floating raft vibration isolation system, which combined the adaptive feedforward control, has great significance in improving the performance of the submarine acoustic stealth.Research in this paper is focused on as follows.Firstly, the principle of the adaptive filter feed-forward control is analyzed. The basic principle of the feedforward control and the characteristics of the adaptive transversal filter are simply summarized. Then the LMS algorithm and the active adaptive feedforward control that based on filtered X-LMS algorithm are proposed. The adaptive filter can adaptively update the weight vector coefficients and adjust the amplitude and phase to make the amplitude of the vibration generated by the actuator or vibration absorber on the target point and control point for an equal and opposite, which can completely eliminate the vibration on the control point. At the same time, the influence of the damping to control performance is considered and the algorithm to increase the damping compensation is proposed.Secondly, the adaptive notch filter system combining with the method of frequency estimation is proposed.The reference signals must be stable and accurate in the adaptive filter feedforward control. However, the vibration of the actual structure is coupled with the vibration source.Secondary acoustic feedback signal have a greater impact on the reference signal, the reference signal is not stable, which make the whole feedforward control system ineffective. The adaptive notch filter is combined with the method of frequency estimation of the mean system is proposed. The frequency of the reference signal could be estimated effectively, and the anti-jamming performance was better.Finally, experiments of the magnetic suspension floating raft active vibration isolation are done. The active feedforward control of the single vibration source floating raft system is realized effectively by using the system model achieved by the off-line identification and combining the magnetic suspension floating raft vibration isolation system. The control algorithm is used in active controlling the main range frequencies of the vibration source that is very effective. The experiment of multiple actuators controlling multiple points is acquired good performance on the vibration. The acceleration of main range frequencies of the control point is decreased by85%. The result is basically accordant to the simulation. The filtered X-LMS algorithm and its improved are used in controlling of floating raft isolation system with the motor’s harmonic vibration and the experiments have a good performance in the main range frequencies of the source’s vibration.