Abstract
This paper proposed a local active control method for the reduction of road noise inside a vehicle cabin. A multichannel simplified hybrid active noise control (sHANC) system was first developed and applied to the rear left seat of a large sport utility vehicle (SUV). The attenuation capability of the sHANC system was investigated through simulations, using reference signals provided by accelerometers on the suspensions and bodywork of the vehicle and microphones on the floor of cabin, respectively. It was shown that compared to the traditional feedforward system, the sHANC system using either vibrational or acoustical reference signals can produce a significant suppression of the narrowband peak noise between 75 and 80 Hz, but the system lost the control capability in a range of 100–500 Hz when the acoustic signals were used as references. To reduce the practical implementation costs while maintaining excellent reduction performance, a modified simplified hybrid ANC (msHANC) system was further proposed, in which combined vibrational and acoustical signals were used as reference signals. The off-line analyses showed that four reference accelerometers can be substituted by ten microphones without compromising attenuation performance, with 3.7 dBA overall noise reduction being achieved. The effect of delays on the reduction performance of msHANC system was also investigated. The result showed that the msHANC system was more sensitive to the delays compared to the sHANC system if using only vibrational reference signals.
Highlights
The noise, vibration, and harshness (NVH) characteristics of vehicles have attracted great attention from vehicle manufacturers
Using the traditional hybrid active noise control (ANC) system based on the internal model control (IMC) structure as a comparison, the simplified hybrid active noise control (sHANC) system can improve the convergence rate and noise reduction performance by reducing the coupling relationship between the feedforward and feedback structures
These results indicated that if the causality constraint of the control system was not considered, using acoustic signals as references could achieve a similar level of control effect as using vibration signals
Summary
The noise, vibration, and harshness (NVH) characteristics of vehicles have attracted great attention from vehicle manufacturers. Using the traditional hybrid ANC (tHANC) system based on the IMC structure as a comparison, the sHANC system can improve the convergence rate and noise reduction performance by reducing the coupling relationship between the feedforward and feedback structures These conclusions were drawn under the situation that the control system was aimed at a single-input single-output (SISO) problem and the primary path was accurately modeled. U0t (nl )th iserror the output summation of control signalby vector secondary sourcethe and microphone which is modeled an Iinth feedforward order finitestructure impulse and feedback structure and can be expressed as: response (FIR) filter and written as:. R f lMK (n) , and r f lmk (n) represents the kth reference signal which is filtered by the estimated plant response between the mth secondary source and lth error microphone, which is equal to:.
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