Multi-input multi-output feedforward control of multi-harmonic gearbox vibrations using parallel adaptive notch filters in the principal component space

Rotating mechanical systems such as gearbox are known to generate vibrations at specific frequencies. The generation of asymmetric frequency sidebands around gear meshing frequencies is typical of rotating systems, and often results in amplitude-modulated disturbances. In addition, when the angular speed of such systems exhibits small time variations, a frequency-modulation of the disturbance tones is observed. Such conditions may result in difficulties for feedforward active control systems based on short, finite impulse response control filters, as was observed by previous researchers. This is mainly due to the fact that the reference signal may not provide all the gear meshing frequencies and sidebands found in the disturbance. This work investigates adaptive notch filters in the principal component space to cancel multi-harmonic gearbox vibrations. Experimental results obtained with these adaptive notch filters show good control attenuations at targeted gearbox tones, without amplification of other closely located, unreferenced tones.

► Short FIR active control filters may not successfully cancel multi-tonal vibration and sound produced by rotating mechanical systems.
► This is due to a nonlinear response of such filters in the adaptation process.
► An alternative structure based on adaptive notch filters that satisfies the synchronous sampling condition shows better control results than short FIR filters.
► The concept was applied to active control of noise produced by a helicopter transmission.