The Design and Performance of Feedback Controllers for the Attenuation of Road Noise in Vehicles

Abstract

Active noise control systems offer a potential method of reducing the weight of acoustic treatments in vehicles and, therefore, of increasing fuel efficiency. The commercialisation of active noise control has not been widespread, however, partly due to the cost of implementation. This paper investigates the design and performance of feedback road noise control systems, which could be implemented cost-effectively by using the car audio loudspeakers as control sources and low-cost microphones as error sensors. Three feedback control systems are investigated, of increasing complexity: a single-input single-output (SISO) controller; a SISO controller employing weighted arrays of error sensors and control sources; and a fully-coupled multi-input multi-output (MIMO) controller. For each of the three controllers robustness and disturbance enhancement constraints are defined and by formulating the three controllers using an Internal Model Control (IMC) architecture, and using frequency discretisation, the constrained optimisation problems are solvable using sequential quadratic programming. The performance of the three controllers and the associated design methods are first evaluated in a simulated environment, which allows the physical limits on performance to be understood. Finally, to validate the results in the simulated environment, the performance of the three controllers has been calculated using data measured in a car cabin and it has been shown that the fully-coupled MIMO controller is able to achieve significant low frequency road noise control, at the expense of increased implementation complexity compared to the SISO and SISO weighted transducer arrays feedback controllers.

Multichannel control systems for the attenuation of interior road noise in vehicles

“…This corresponds to a reduction in the first longitudinal enclosure mode. Other modal feedback control systems have also been proposed that may be suitable for similar road noise control problems [10,11,12]. To achieve control in vehicles where a single acoustic mode does not dominate the response, however, it has been shown to be necessary to employ a multi-input, multi-output (MIMO) controller [12].…”

“…Other modal feedback control systems have also been proposed that may be suitable for similar road noise control problems [10,11,12]. To achieve control in vehicles where a single acoustic mode does not dominate the response, however, it has been shown to be necessary to employ a multi-input, multi-output (MIMO) controller [12]. A MIMO feedback controller has been investigated in [13] which uses four headrest mounted microphones as error sensors and the four car audio loudspeakers as control sources.…”

Active Control of Broadband Noise Inside a Car Using a Causal Optimal Controller

“…The result of Equation (10) represents the multiple coherence between the undesired noise and the set of reference signals. As we know, a widely accepted expression to estimate the maximal noise reduction is [4,11,21], as follows:…”

“…Belgacem et al used an active structural acoustic control technique to reduce the vibration of suspensions, and a 4.6 dB attenuation was measured in the 50-250 Hz on a quarter-car test bench [9]. Cheer and Elliott show that a multi-input multi-output system was required to have a distinct reduction for the broadband noise [10,11]. Further, Jung et al used a headrest system to reduce interior road noise around a listener's ears with remote microphone technique [12].…”

Acoustic Metamaterials: A Potential for Cabin Noise Control in Automobiles and Armored Vehicles

“…This especially repels consumers away in the purchase consideration of low-and mid-end cars, where extra cost is added into the total purchasing price. A brilliant attempt to reduce the installation cost of feedback control system is proposed by incorporating it into the in-car entertainment system [Cheer and Elliott, 2013]. They developed three different kinds of feedback control systems of varying complexity and validated their performance in a commercial car.…”