Zafeiropoulos, Nikolaos 2015, Active Noise Control in a Luxury Vehicle , PhD thesis, University of Salford.
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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.
|Item Type:||Thesis (PhD)|
|Schools:||Schools > School of Computing, Science and Engineering|
|Funders:||Bentley Motors Ltd|
|Depositing User:||N Zafeiropoulos|
|Date Deposited:||22 Feb 2016 13:20|
|Last Modified:||22 Feb 2016 13:20|
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