NEX-LMS: A novel adaptive control scheme for harmonic sound quality control

• Published in: Mechanical systems and signal processing Vol. 24; no. 6; pp. 1727 - 1738
• Main Authors: de Oliveira, Leopoldo P.R., Stallaert, Bert, Janssens, Karl, Van der Auweraer, Herman, Sas, Paul, Desmet, Wim
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2010; Elsevier
• Subjects: Acoustics; Active control; Applied sciences; Convergence; Engine noise; Engines; Engines and turbines; Equalization; Exact sciences and technology; Excitation; Filtered x-LMS; Fundamental areas of phenomenology (including applications); Harmonics; Internal combustion engines: gazoline engine, diesel engines, etc; Mathematical models; Mechanical engineering. Machine design; NEX-LMS; Noise: its effects and control; Physics; Sound; Sound quality; Sound quality; Engine noise; NEX-LMS; Active control; Filtered x-LMS; Harmonic; Transient response; Adaptive system; Random excitation; Equalization; Real time; Adaptive control; Noise control; Modeling; Tuning; Standards; Stationary condition; Active system; Filter; Least squares method; Quality control; Convergence rate; Internal combustion engine; Reduced order systems
• ISSN: 0888-3270; 1096-1216
• DOI: 10.1016/j.ymssp.2010.01.004

This paper presents a novel adaptive control scheme, with improved convergence rate, for the equalization of harmonic disturbances such as engine noise. First, modifications for improving convergence speed of the standard filtered-X LMS control are described. Equalization capabilities are then implemented, allowing the independent tuning of harmonics. Eventually, by providing the desired order vs. engine speed profiles, the pursued sound quality attributes can be achieved. The proposed control scheme is first demonstrated with a simple secondary path model and, then, experimentally validated with the aid of a vehicle mockup which is excited with engine noise. The engine excitation is provided by a real-time sound quality equivalent engine simulator. Stationary and transient engine excitations are used to assess the control performance. The results reveal that the proposed controller is capable of large order-level reductions (up to 30 dB) for stationary excitation, which allows a comfortable margin for equalization. The same holds for slow run-ups ( > 15 s ) thanks to the improved convergence rate. This margin, however, gets narrower with shorter run-ups ( ≤ 10 s ).