Method for performing an active profiling of a sound emitted by an engine and corresponding profiling system

Patent metadata

Field	Value
Publication number	US-2016192095-A1
Application number	US-201514977126-A
Country	US
Kind code	A1
Filing date	Dec 21, 2015
Priority date	Dec 24, 2014
Publication date	Jun 30, 2016
Grant date	—

Abstract

A method for performing an active profiling of the sound emitted by a vehicle engine including the steps of injecting second acoustic waves (MW), which are able to combine with the first acoustic waves (EW) in a merge point in said primary propagation path and to generate third resulting acoustic waves (RW); and generating a driving signal for the diffuser by regulating the amplitude of harmonics of the driving signal (SP) as a function of reference acoustic waves and of a workpoint of the engine, calculating equalization coefficients (α 1 , . . . , α M ) to be applied to the amplitudes of said harmonics of the driving signal (SP) via a self-tuning procedure, and comparing the reference acoustic waves (TW) with a simulation (SRW) of the resulting waves. The simulation (SRW) is obtained by applying to a simulation of the second acoustic waves a model of the secondary propagation path.

First claim

1 . A method for performing an active profiling of the sound emitted by a vehicle engine that issues first acoustic waves (EW) along a primary path of propagation of acoustic waves, in particular an exhaust duct,
said method comprising the steps of: injecting, via an acoustic-wave diffuser, into a secondary propagation path that merges in said primary path, second acoustic waves (MW), which are able to combine with said first acoustic waves (EW) in a merge point in said primary propagation path and to generate third resulting acoustic waves (RW); generating a driving signal (SP) for driving said diffuser by regulating the amplitude of harmonics of said driving signal (SP) as a function of reference acoustic waves (TW) and of a workpoint (WP) of the engine; and calculating equalization coefficients (α i , . . . , αm) to be applied to the amplitudes of said harmonics of said driving signal (SP) via a self-tuning procedure, which comprises comparing said reference acoustic waves (TW) with a simulation (SRW) of said resulting waves (RW), said simulation (SRW) being obtained by applying, to a simulation (MSW) of the second injected acoustic waves (MW), a model (H) of the secondary propagation path.

2 . The method as set forth in claim 1 , wherein said method further includes the steps of:
generating basic harmonics (W 1 , . . . , W M ) as a function of the current workpoint (WP) of the engine; obtaining said equalization coefficients (α 1 , . . . , α m ) as a function of the values of workpoint (WP) using respective look-up tables for each harmonic (W i ), which supply, as a function of the value of current workpoint (WP) of the engine, a respective equalization coefficient (α i ).

3 . The method as set forth in claim 2 , wherein said method further includes the steps of obtaining equalized harmonics (EW 1 , . . . , EW M ) as a function of said equalization coefficients (α 1 , . . . , α M );
adding together said equalized harmonics (EW 1 , . . . , EW M ) to obtain a digital driving wave (DW); and
converting said digital driving wave (DW) into an analog signal corresponding to the driving signal (SP).

4 . The method as set forth in claim 2 , wherein said operation of generating basic harmonics (W 1 , . . . , W M ) comprises generating, as a function of the engine r.p.m. (ER), a pre-set number (M) of basic harmonics (W 1 , . . . , W M ) of a sinusoidal signal at the frequency (f) identified by said engine r.p.m. (ER)

5 . The method as set forth in claim 1 , wherein said self-tuning procedure comprises:
applying an FFT (Fast Fourier Transform) to the reference acoustic waves (TW), which in particular are originated by a reference vehicle, to obtain a reference spectrum (TTW), and extrapolating from said reference spectrum (TTW) amplitudes (TA 1 , . . . , TAM) of reference harmonics; injecting a simulation (MSW) of the second acoustic waves (MW) into the model (H) of the secondary path and obtaining corresponding simulated resulting waves (SRW), in particular for different values of equalization coefficients (α 1 , . . . , αm) that model the amplitudes of the second injected waves (MW); adding the resulting waves (RW) to the reference waves (TW) and applying a transform (FFT) to a resulting sum wave (SW), to obtain a transformed sum wave (TSW); evaluating and minimizing a cost function (CF) as a function of the amplitudes (TA 1 , . . . , TA M ) of reference harmonics and of amplitudes (SA 1 , . . . , SA M ) of the transformed sum wave (TSW), in particular as a function of their difference calculated as sum of the errors between the amplitudes (TA 1 , . . . , TA M ) of reference harmonics and amplitudes (SA 1 , . . . , SA M ) of the transformed sum wave (TSW), supplying as values of equalization coefficients (α 1 , . . . , α M ) for a given value of workpoint (WP) the values that minimize said cost function (CF).

6 . The method as set forth in claim 1 , wherein said method further includes an identification procedure for identifying said model (H) of the secondary path, said procedure comprises calculating the parameters of a FIR (Finite Impulse Response) filter.

7 . The method as set forth in claim 1 , wherein said calculation of the parameters of a FIR filter comprises:
generation and injection, via the diffuser, white noise (WN) into the secondary path, keeping the engine turned off, both acquiring the driving signal (SP) associated to the white noise (WN) as input signal (u) of the model (H) and acquiring the corresponding resulting waves (RW) at output from the primary path as output signal (y) of the model (H), repeating said operation of injection a plurality of times with different amplitudes of white noise (WN) at input, to obtain different instances of output signal (y); and calculation of values of parameters of the FIR filter of the model (H) of the secondary path, applying a regression as a function of said plurality of instances of inputs (u) and outputs (y), in particular applying an LMS (Least Mean Square) procedure.

8 . The method as set forth in claim 1 , wherein said workpoint (WP) comprises a value of engine r.p.m. (ER) and a value of gas-pedal percentage (GP), which are, in particular, issued by an electronic control unit of the vehicle.

9 . A system for active profiling of the sound emitted by a vehicle engine that issues first acoustic waves (EW) along a primary path of propagation of acoustic waves, in particular an exhaust duct, said system comprising a secondary path, which merges in said primary path, in which an acoustic-wave diffuser injects second acoustic waves (MW), which are able to combine with said first acoustic waves (EW) in a merge point in said primary propagation path and to generate third resulting acoustic waves (RW), an active-sound-profiling unit configured for generating a driving signal (SP) for said diffuser by regulating the amplitude of harmonics of said driving signal (SP) as a function of reference acoustic waves (TW) and of a workpoint (WP) of the engine, said active-sound-profiling unit acting to carry out said operation of regulation.

10 . The system as set forth in claim 9 , wherein said active-profiling unit comprises a harmonic-generation module, configured for generating, as a function of the engine r.p.m. (ER), a pre-set number (M) of basic harmonics (W 1 , . . . , W M ) of a sinusoidal signal at a frequency (f) identified by said engine r.p.m. (ER), and a plurality of look-up tables, each look-up table, for a specific corresponding harmonic (W i ), associating to a value of workpoint (WP) a respective equalization coefficient (α i ).

11 . The system as set forth in claim 9 wherein said engine is an internal-combustion engine or an electric engine.

12 . The system as set forth in claim 9 , wherein said system acts to carry out said self-tuning procedure and/or said identification procedure for identifying the model (H) of the secondary path on one or more processors that implement simulation environments.

Assignees

• Magneti Marelli Spa

Inventors

• Marcelli Antonio
• Armeni Saverio
• Nesci Walter

Classifications

• F01N9/00

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F01N1/065

  by using an active noise source, e.g. speakers · CPC title

• H04R2499/13

  Acoustic transducers and sound field adaptation in vehicles · CPC title

• G10K2210/3025

  Determination of spectrum characteristics, e.g. FFT · CPC title

• G10K2210/3032

  Harmonics or sub-harmonics · CPC title