Active Control Of Vehicle Interior Noise Combined With Virtual Microphone

The vehicle interior noise is an important index to judge the performance of the vehicle.The primary vehicle interior noise,such as the noise of engine,transmission system,tire and air friction,propagate inside vehicles by means of airborne transmission and structure borne transmission.Although the noise sources distribute dispersedly and their mechanisms are different,the frequency of noise is in low-frequency range.Since the passive noise control method has inherent defect for controlling low-frequency noise,the active noise control method is adopted widely to implement low-frequency noise control.Meanwhile,Consumers have higher and higher requirement on vehicle acoustic comfort.The sound quality raises the concern of researchers as the main content of acoustic comfort.Some researches show that the sound pressure level of order sound of vehicle engine is a significant index of sound quality.In active noise control,the adaptive structure is employed generally for dealing with the change of sound field environment.The error signals are required as feedback signals in adaptive control system.In a typical local active noise control system,the region of noise control is limited so the error sensors need to be placed near the target control point,and there may be a problem of interfering with the movement of passengers.For solving this problem,the sound field control technique combined the active noise control with virtual microphone is proposed in this paper.The technique and implementation of active noise control combined with virtual microphone method are mainly studied in this paper.The two-channel feedforward adaptive local active noise control model is built,and the performance of some typical adaptive control algorithms is analyzed.The two-channel active noise control test platform is established inside vehicle and utilized to implement control tests under steady state condition and instantaneous condition.The effects that the structure parameters exert on the control results are studied.According to the nonlinearity of vehicle interior sound field,an estimation method of virtual microphone signal on the basis of neutral network is proposed.The estimate and control of signal at target control point are achieved using this virtual microphone method combined with active noise control model.The performance comparison of this model with some other virtual microphone estimate methods is conducted,and the test results show that the active noise control system combined with this estimation method has better control performance.The two-channel parallel active order sound equalization control method is proposed for the need of adjusting the engine order sounds and improving the sound quality.The validity of this method is illustrated using simulation analysis and several tests of different control modes are carried out under steady state condition and accelerating condition using the active noise control test platform.The test results show that all the test of different control modes can achieve the expected objectives.Then the virtual microphone is also combined with the active noise equalization method,and a variety of order sound equalization tests with different control modes are completed in the context of remote placement of error microphones.