Research On Active Noise Control Method In Commercial Vehicle

With the improvement of people's living standards,ride comfort has become an important indicator for people to evaluate commercial vehicles.Among them,the size of the noise in commercial vehicles is one of the key factors that affect the ride comfort,and the noise will cause harm to people's physical and mental health,so it is necessary to reduce the noise in commercial vehicles.The traditional methods to reduce the interior noise of commercial vehicles are absorption,sound insulation,noise reduction and other passive noise reduction technologies.These methods can achieve better noise reduction effect for medium and high frequency noise,but they are not suitable for reducing low frequency noise.Active noise reduction technology emerges as the times require.Active noise reduction technology can effectively control low-frequency noise,make up for the shortcomings of passive noise reduction technology,and combine with passive noise reduction technology to achieve comprehensive noise reduction in commercial vehicles.The basic principle of the application of active noise reduction technology is the interference cancellation of sound waves,that is,two lines of sound waves with equal frequency and amplitude and opposite phase,which will make the sound waves cancel each other after superposition.In order to reduce the interior noise of commercial vehicles,it is necessary to use the adaptive controller to send out a sound wave with the same frequency and amplitude and opposite phase as the interior noise of commercial vehicles,which is used to cancel the interior noise of commercial vehicles.After analysis,the low-frequency noise in commercial vehicles is mainly caused by engine vibration,so the active control of the noise in commercial vehicles is transformed into the active control of the engine noise in commercial vehicles.The main frequency of commercial vehicle engine noise is related to engine speed,so engine speed is used to synthesize the reference signal.Based on this,this paper studies the principle and implementation strategy of active noise reduction control in commercial vehicles.In this paper,a control method of active noise reduction system in commercial vehicle is proposed,which combines the traditional active noise reduction control with the prediction algorithm.First of all,the adaptive active control algorithm model is built for simulation experiment,and the cancellation signal database is established.Secondly,predict and estimate the engine speed of commercial vehicles.Thirdly,the reference signal is synthesized from the predicted commercial vehicle engine speed and the relationship between the commercial vehicle engine speed and the reference signal.Finally,according to the synthetic reference signal frequency,the relevant data of the secondary sound source database is automatically retrieved to reduce the noise in commercial vehicles.In this paper,LMS algorithm,secondary path identification,single channel FXLMS algorithm,multi-channel FXLMS algorithm model are built in MATLAB / Simulink,and simulation verification is carried out.Reference signal model,data storage model and data call model based on multi-channel FXLMS algorithm are established,and simulation verification is carried out for the off-line system of active noise reduction of commercial vehicles,and the maximum noise reduction effect can reach 24.2dB.The engine dynamic model is established,and several methods of predicting engine speed(including grey prediction,PID control algorithm,BP neural network algorithm optimized by genetic algorithm)are simulated and compared,which proves that the prediction effect of BP neural network algorithm optimized by genetic algorithm is the best.