Wayne Vanhaaften

Virtual Secondary Path Algorithm for Multichannel Active Control of Vehicle Powertrain Noise

An enhanced multiple-input multiple-output (MIMO) filtered-x least mean square (FXLMS) algorithm using improved virtual secondary path is proposed as the basis for an active noise control (ANC) system for treating vehicle powertrain noise. This new algorithm is developed to overcome the limitation caused by the frequency-dependent property of the standard FXLMS algorithm and to reduce the variation of convergence speed inherent in multiple-channel cases, in order to improve the overall performance of the control system. In this study, the convergence property of the proposed algorithm is analyzed in the frequency domain in order to yield a better understanding of the physical meaning of the virtual secondary path. In practice, because of the arrangement and sensitivities of the actuators (speakers), transducers (microphones), and physical environment, the magnitude response of the main secondary paths can be very different from each other. This difference will cause difficulty in the overall convergence of the algorithm, which will result in minimal attenuation at some of the channels. The proposed channel equalized (CE) virtual secondary path algorithm is designed to tackle this difficulty by equalizing the mean magnitude level of the main secondary paths and by adjusting other secondary paths correspondingly to keep the coupling effects among the control channels unchanged. The performance of the proposed algorithm is validated by analyzing a twoinput two-output active powertrain noise control system. [DOI: 10.1115/1.4023815]

Active Control of Vehicle Transient Powertrain Noise Using a Twin-FXLMS Algorithm

Powertrain noise is a major component of vehicle interior noise and thus has a significant effect on the overall sound quality. It is typically dominated by harmonics in the lower audible frequency range, which are directly related to the engine firing orders. In order to achieve a more comfortable environment and pleasing driving experience, an active noise control (ANC) applying advanced filtered-x least mean squares (FXLMS ) algorithm is employed to reduce the vehicle interior noise by targeting these harmonics. The proposed ANC system is designed to control multiple orders of the engine noise response simultaneously. It is also uniquely formulated with a twin-FXLMS algorithm to prevent harmonic interference that often resulted in overshoot at some adjacent orders, especially at low engine speed range where the reference sinusoids are close together. In fact, the interference issue is one of the critical problems that previously plagued the use of the conventional FXLMS algorithm. The basic design of the twin-FXLMS algorithm splits the adaptive filter into two sets. This allows different sum of reference sinusoids to be fed into each adaptive filter in order to widen the frequency separation between two adjacent harmonics. Finally, the performances of proposed twin-FXLMS are validated by numerical simulations.

An active noise control system for tuning steady-state and transient responses within a vehicle compartment

Traditional vehicle active noise control (ANC) is designed to suppress unwanted vehicle response. In this study, an ANC system is proposed for tuning rather than suppressing vehicle interior response. The proposed concept is studied numerically, utilizing simulated control input speakers inside the passenger compartment. The proposed control algorithm is adapted from the basic filtered-x least mean squares (FXLMS) algorithm. In this case, instead of using the FXLMS algorithm to minimize the resultant sound pressure level, a set of target functions is added to the controller for shaping the vehicle interior response. The proposed computer simulation can incorporate either measured or predicted cavity acoustic transfer functions. Using this analysis model, the proposed approach is demonstrated using a powertrain noise example in which individual engine firing orders are targeted for shaping either by reducing or enhancing the spectral content

A fast numerical formulation for simulating vehicle compartment acoustics

Vehicle noise, vibration and harshness (NVH) problems can be analyzed using numerical methods such as finite element and boundary element analyses that are generally complex and time consuming. In order to reduce the analysis time and calculation burden, this paper discusses the development, use and verification of an enhanced, simplified numerical acoustic cavity formulation for the analysis of vehicle NVH problems. The proposed simplified vehicle model can incorporate multiple acoustic cavities, such as an engine compartment, passenger compartment, and connecting bulkhead compartment, joined by several flexible panels. The damping matrix of the model is constructed from measured acoustic absorption data and panel properties. Utilizing this approach, both single-cavity and three-cavity models are created, different floor panel configurations are investigated, and transfer functions predicted by these models are compared with corresponding transfer functions from measured data. The comparison results show that the proposed simplified model can provide reasonable accuracy for the analysis and simulation of vehicle compartment acoustics.