Active noise control in a luxury vehicle

Zafeiropoulos, Nikolaos

Abstract

Structure-borne road noise is a critical sound attribute for the overall Noise Vibration
& Harshness (NVH) performance of modern luxury vehicles. Current
passive NVH solutions require structural design modifications, in order to control
low frequency sources that cause structure-borne noise. Active Road Noise
Control (ARNC) has been demonstrated to several commercial vehicles as an
alternative solution that does not compromise other performances of the car,
especially vehicle dynamics. Automotive manufacturers of luxury vehicles, such
as Bentley Motors Limited, are expected to build cars that meet high standards
of driving performance and refinement levels. This thesis focuses on the development
of an active sound technology for road noise with the use of NVH
analysis methods, which are a common practice in the vehicle development process.
Modern NVH methods of road noise analysis reveal the locations of the
most predominant structure-borne noise sources. There are significant advantages
in using NVH analysis techniques for the design of ARNC systems, since
they o_er integrated solutions to the automotive industry in terms of time and
cost reduction. A method for defining the accelerometer sensors number and
their locations on the axles has been developed as an alternative to existing
methodologies, which are applied from the early stages of the NVH development.
A physical road noise simulator was developed for replicating road noise.
Four random uncorrelated forces were applied on the tyres for analysing and
evaluating ARNC systems. In terms of feedforward control, a computer model
of a causal adaptive feedforward system was used to investigate the relationship
between the locations, DoF and the performance of the control system.

An adaptive system was installed on a Bentley vehicle for conducting the ARNC
measurements. The adaptive ARNC system was tested on the physical road noise
simulator. The vehicle's tyres were excited by broadband random forces and
maximum 10 dB(A) reduction at the centre frequency of the tyre cavity resonance
was achieved. When the control was focused on the road rumble, then overall
3 dB(A) up to 500 Hz were removed from the noise levels measured at the rear
headrests. In terms of road noise testing, a portable multichannel controller was
integrated with the vehicle electrical system for road noise data acquisition and
real-time ARNC. Finally, the performance of the portable controller is predicted
based on data acquired by the same multichannel system and therefore highlight
the potential use of this system as an ARNC controller.

Citation

Zafeiropoulos, N. (in press). Active noise control in a luxury vehicle. (Thesis). University of Salford

• Thesis Type: Thesis
• Acceptance Date: Dec 12, 2015
• Deposit Date: Feb 22, 2016
• Publicly Available Date: Feb 22, 2016