Marine Diesel Vibration Isolation using an RLS Based Harmonic Control Algorithm with Frequency Tracking

摘要

In a variety of engineering systems there is often a requirement to isolate the supporting foundation from periodic machinery vibration sources. In such cases the vibration is mainly transmitted at the fundamental excitation frequency and its multiple harmonics. Due to the often limited performance of passive approaches at low frequencies, a number of active control technologies have been developed over recent decades that particularly target harmonic or tonal disturbances. A recently proposed algorithm consists of a classical Exponential Forgetting Recursive Least Squares (ExF-RLS) estimator, which is used to extract gain and phase information from the error signal and a gradient descent algorithm to update the control input based on the latest RLS estimates. It has previously been shown that, remarkably, the ExF-RLS estimator, can be approximated by a fixed parameter filter, and that as a result, the whole harmonic control algorithm can be represented by a linear time-invariant (LTI) feedback compensator. In this paper it is shown that the ExF-RLS algorithm can be extended to additionally provide an estimate of the dominant frequency in the error signal. The performance of the algorithm is demonstrated through its application to the isolation of vibration in a marine diesel installation. With frequency tracking enabled, the algorithm is shown to produce a high degree of reduction in excess of the passive performance at the three dominant harmonics of the below mount acceleration response.