EP1964107A1

EP1964107A1 - Method and system for actively influencing noise, and use in a motor vehicle

Info

Publication number: EP1964107A1
Application number: EP06763865A
Authority: EP
Inventors: Fabian Evert; Roland Lippold; Rolf Schirmacher; Florian Walter
Original assignee: Mueller Bbm GmbH
Current assignee: MUELLER-BBM ACTIVE SOUND TECHNOLOGY GMBH
Priority date: 2005-12-15
Filing date: 2006-06-23
Publication date: 2008-09-03
Anticipated expiration: 2026-06-23
Also published as: EP1964107B1; WO2007071458A1; US20090205903A1; JP5162469B2; KR20080091438A; US8270628B2; KR101027870B1; JP2009519165A; DE102005060064A1

Abstract

Method for improving the perceived acoustics of an area, comprising the following method steps: recording at least one sound signal using a recording means in the vicinity of at least one sound source in the area; carrying out a respective convolution operation on the recorded sound signal with a respective pulse response function for generating different optimized sound signals, with the respective pulse response function being selected from a range of prespecified pulse response functions for the area; playing-back the optimized sound signals using sound play-back means which are arranged in the area, with a different optimized sound signal being supplied to each sound play-back means, and with the optimized sound signals in each case being supplied to the sound play-back means after a changeover time interval in such a way that the same optimized sound signal is not supplied to any of the play-back means in immediately successive changeover time intervals.

Description

Method and system for active noise control, use in one

motor vehicle

The present invention relates to a method for active noise control, in particular in a motor vehicle. Furthermore, the invention relates to a corresponding system and its use in a motor vehicle.

Systems for active noise control, which are also referred to as ANC systems (active noise control) serve, for example, in a passenger compartment of a motor vehicle to reduce by coupling controlled acoustic signals, the noise level of a source of interference, for example the motor. In this active compensation, the noise is reduced by superposition with additional vibrations, so-called anti-sound. The controlled coupling of secondary sound also any harmonics and / or the root of the primary noise can be amplified. As a rule, harmonious tone sequences, for example, are perceived as pleasant. By selectively suppressing individual frequencies of the engine noise and amplifying other frequencies, for example, a perceived engine noise can be designed specifically. One speaks then also of sound design.

In the following, compensation sound is understood as a secondary sound coupled in addition to the noise sound, which can act both amplifying and damping at specific sound frequencies.

The same principle arises in the compensation of structure-borne noise, by means of actuators

Counter vibrations are coupled into a solid, which cause a noise reduction or noise change.

As a rule, the noise or vibration sources are essentially periodic sound sources. The excitation frequency resulting from the periodicity

Noise source is used as input for an adaptive control of the noise reduction system. If this characteristic for the respective noise source As time changes, adaptive control of the noise mitigation system makes a corresponding adjustment in the compensation sound injection.

An adaptive control for active noise reduction is known for example from DE 196 32 230 C2. There, a reference signal generator is provided which detects an engine speed and generates an electronic reference signal having information about the engine speed. This may be, for example, a pulse signal, which is guided via signal lines to a sine generator provided in the noise reduction system. In the motor vehicle, a corresponding reference signal can also be derived from the ignition coil signal, which is directly related to the engine speed and thus the acoustic excitation frequency of the engine.

In active noise reduction systems, it is necessary to keep the corresponding excitation frequency or an equivalent reference signal for the actuation of the actuators or compensation loudspeakers as continuous as possible in time. In noise reduction systems according to the prior art, therefore, a measuring sensor usually used near the engine is provided, which supplies a corresponding reference signal to the actual control of the noise reduction system. The noise reduction system is usually located in the passenger compartment, so long signal paths and a corresponding wiring are required.

Due to progressive automation and the integration of various control and regulating tasks in modern systems in a digital manner, analog continuous-time monitoring signals are hardly available any more. In modern motor vehicles, data communication takes place, for example, via digital bus systems, such as, for example, the CAN bus (Controller Area Network Bus). In such asynchronous serial bus systems, real-time data communication is no longer possible. For the indication of the engine speed in the fittings of a motor vehicle, e.g. a deployment rate of only 10 per second is sufficient.

Typically, several bus systems are kept in current motor vehicles. A first high-speed bus is provided in the engine compartment, which controls the engine network and having an engine speed provision period of the order of 10 to 20 milliseconds. A second slower data bus, coupled via a gateway to the high-speed bus, is used to network control devices for the comfort and interior functions of the motor vehicle, such as speedometer, tachometer, etc.

The motor speed reference variable, which is important for a system for active noise control, is thus only available at a lower provision rate of about 10 times per second, ie every 100 milliseconds on the slower data bus provided in the interior of the motor vehicle. In particular, when accelerating and braking the engine, the only very discretely present discrete reference variable, for example, the engine speed, the operation of the active system in the passenger compartment difficult.

It is therefore an object of the present invention to provide a reliable method for influencing noise. Furthermore, the invention has for its object to provide a system for active noise control.

This object is achieved by a method for influencing noise in accordance with patent claim 1 and by a system for active noise control having the features of patent claim 10.

Further embodiments of the invention will become apparent from the dependent claims.

The invention provides a method for influencing noise, preferably in the event that a reference variable characterizing the respective noise source exists only in time-spaced samples.

According to the invention, the time-discrete characteristic reference variable is extrapolated starting from the respective readout times, wherein at least two temporally preceding readout values of the reference quantity are used in an extrapolation model or a read value of the reference quantity and a change parameter of the reference quantity are used for extrapolation. In the method according to the invention Thus generated reference signal is thus practically continuous time, but at least with a sampling rate, with which a digital system is operated for noise control. This allows a reliable adaptation of the compensation sound injection by the device for active noise control to the time-varying excitation of the noise source.

In this case, it is essentially understood periodically that the excitation frequency can change during the operation of the noise source, as is the case, for example, with a motor during acceleration or deceleration.

In the method according to the invention and the system according to the invention for influencing noise, the current actual excitation, which is characterized by the reference variable, is always taken into account in the compensation of the compensation noise. The invention therefore enables irradiation of secondary sound or compensation sound with particularly high amplitude and phase accuracy.

The inventive method enables the coupling of a system for active noise control directly to a, for example, in-vehicle data bus, which has only a low repetition rate with respect to the characteristic reference variable. This eliminates the need for an additional measuring sensor for recording the reference size and the corresponding cabling.

The proposed method and system for influencing noise according to the invention is particularly suitable for use in a motor vehicle in which, for an improved extrapolation model, further data for the prediction of the engine speed between readings from the data bus can be taken into account. The invention is also easily implemented in programmable digital control devices of the active system for noise control.

Advantageous embodiments and further developments of the invention are subject of the dependent claims and the description with reference to the accompanying figures. In the following the invention will be described in greater detail by means of a preferred exemplary embodiment of an adaptive system for influencing noise in a motor vehicle. It shows:

1 shows a schematic representation of a system according to the invention for influencing noise in a motor vehicle;

2 shows a flow chart of the method according to the invention; and

3 shows a diagram with sound pressure levels as a function of the engine speed.

1 shows an inventive system for influencing noise 1, which is coupled to a data bus 2 in a motor vehicle.

In the engine compartment M of the motor vehicle, a high-speed CAN-BUS 3 is provided, which serves for networking engine control devices 4, 5. One of the engine control devices, for example, a speed sensor 4, which provides information about the speed of the motor 16 to the high-speed bus 3. Another engine control device 5 reads the engine speed and other vehicle operating data from the high speed! 3 and sends corresponding control signals for the motor 16 to the high-speed data bus 3. The motor speed is usually at a supply rate of 10 to 20 milliseconds on the high-speed data bus 3 before.

In the vehicle interior I, which is shown in FIG. 1 on the right side of the dotted line, a low-speed CAN bus 2 is provided, which is coupled via a gateway device 6 to the high-speed CAN bus 3. To the low-speed CAN bus 2, for example, display devices 7 are coupled for speed, speed, tank level or other common monitoring variables or positioners 8 for comfort functions of the vehicle.

On the low-speed CAN bus 2 is the speed information, which is a characteristic reference quantity for the noise source, for example the motor 16, only with a repetition rate of about 100 milliseconds. That is to say at 100 millisecond spaced deployment times are current speed information readable. Furthermore, the signal propagation times between the high-speed CAN bus 3, the gateway 6 and the low-speed CAN bus 2 can result in further delays. The provision times can thus also be present at irregular intervals.

The system for influencing noise 1 has an extrapolation device 9, which is coupled via suitable data lines 10 to the low-speed CAN bus 2 provided in the vehicle interior. A device for active noise control 11 is also provided, which receives a reference signal 12 generated by the extrapolation device 9. The device for influencing noise 11 supplies control signals 13 to one or more actuators 14, which are shown here by way of example as a loudspeaker 14. Further, a noise sensor or a microphone 15 is coupled to the noise control device 11, which receives the noise or a noise sound emitted from the motor 16 as a noise source in the illustrated example, and the compensation signal outputted from the speaker 15 ,

The noise control device 11 regulates the radiation of the compensation noise by the loudspeaker 14 as a function of the reference signal 12, which is assigned to a reference variable characterizing the noise source, for example the engine speed, and the sound level recorded to the microphone such that interference of the noise sound interferes with the incident secondary or compensation sound a noise change occurs. In this case, the changed sound perceived by an occupant, for example, can be designed in such a way that the sound is perceived as pleasant. In this case, derived from the excitation frequency of the noise source, ie the fundamental frequency, derived higher harmonics can be selectively damped or amplified by secondary noise, so that a desired noise color occurs. It is not only integer harmonic excitations by the secondary sound injection changeable, but any harmonics can be influenced to achieve a respective sound design. If the engine speed changes as a reference variable, for example during acceleration or deceleration of the vehicle, the noise-influencing device 11 requires a corresponding actual reference signal 12 in real time in order to adapt the compensatory sound to the changed excitation frequency of the motor 16. However, at the low-speed CAN bus 2, the reference quantity is present only at certain provision times. Therefore, the extrapolation device 9 according to the invention performs the method steps described in more detail in FIG. 2.

The extrapolation device 9 reads in a first step S1 to a first supply time t | the present engine speed Ni, and stores them in a second step S2. The read-out and storage takes place in each case at successive provision times t "which are predetermined by the state and the architecture of the respective data bus, for example the low-speed CAN bus 2.

Using an extrapolation model S4, the extrapolation device 9 extrapolates the values of the read-out and stored rotational speeds in step S3 and generates a corresponding reference signal 12, which is output in step S5. In this case, the reference signal 12 is generated in such a way that the respective values of the reference signal 12 approximate the current reference variable as well as possible between the provision times tj.

A preferred extrapolation model provides for linear extrapolation by means of an excitation frequency / time or motor speed / time gradient. At the delivery times t, and t, _i, the engine speed values Ni and Ni _{-I are} read out. The time difference between the delivery times t "t ,. _! is Δt = Vt _1- ]. Between these two times t ₁₅ t, _i the engine speed changes by ΔN = N ₁ -N _1-1 .

The extrapolation device 9 determines this change of the reference variable or the motor

• ΔN speed and calculates the resulting spin to: N = -. For in the

.delta.t

Essentially arbitrary times t> t, can be linearly extrapolate the speed:

(Eq.) N (t> t.) = Ni + N (H). The extrapolation device 9 supplies this estimated engine speed N (t) as a reference signal 12 to the device for influencing noise. The extrapolation device 9 supplies this reference signal 12 with a reference signal rate that corresponds, for example, to the clock rate of the device for influencing noise 11. Usual rates are for example in the order of 1-5 kHz.

In addition to a linear extrapolation, further modified extrapolation methods are possible. For example, it is possible to take into account a plurality of engine rpm values read out in chronological order and extrapolation polynomials of higher orders can be used.

A refined modeling of the noise source, in the example of application of the engine described here, can also be done by considering other engine-related parameters, such as the current load or changes in engine behavior, which are dictated by a motor control. In this case, the pedal dynamics of accelerator and / or brake pedal, control signals of an anti-lock brake system or electronic stabilization system or other data can be done. The data required for such models is available through the digital data bus systems in the vehicle.

Further preferably used extrapolation models include self-learning models, ie models in which adjustments are made during operation in the respective extrapolation algorithm, for example by changing extrapolation parameters. During extrapolation, known properties can also be incorporated via the noise source or its control, for example a motor control. For example, motors are often automatically decelerated at certain particularly high speeds. Such knowledge is advantageously taken into account in the extrapolation.

Preferably, in the prediction of the rotational speed data, the signal propagation time between, for example, the rotational speed sensor 4 via the high-speed CAN bus 3, the gateway 6 and the low-speed data bus 2 is taken into account. Thus can be achieve a further improvement of the extrapolated engine speed or the values of the reference signal 12 to the actually existing reference size.

In an alternative embodiment of the method according to the invention, the extrapolation of the actual values of the reference variable can also be effected by using a change parameter which characterizes the temporal change of the reference variable and a read-out value of the reference variable, if a corresponding change parameter is used.

ter, such as the spin N, on the data bus is read out. In principle, the invention requires only arbitrary time-readable parameters that allow to perform an extrapolation. Possibly, delivery times for a corresponding change parameter and delivery times for the values of the reference size may be closer in time to each other than the delivery times for the values of the reference size among each other.

In Fig. 3 sound levels using the method and system according to the invention for active noise control and in dependence on an engine speed are shown. The adaptive control as a function of the generated reference signal is explained in more detail, for example, in DE 196 32 230 C2 and serves in the example of noise reduction considered here.

The solid line curve A represents the sound pressure level without an active system for influencing noise in a four-cylinder engine on a microphone in a vehicle interior for the ignition frequency, so twice the engine speed. The engine speed was within 60 seconds of 1000 revolutions per minute to 6000 Raised revolutions per minute.

The dotted curve B represents the sound pressure using an ANC system in which the delivery times for updating the engine speed are at intervals of 100 milliseconds and no extrapolation according to the invention has been carried out. That is, the engine speed was assumed constant between the delivery times. Especially at speeds above about 2000 revolutions per minute After all, this rough update, such as the rate of provision of a low-speed CAN bus, is no longer sufficient to achieve noise reduction with an ANC system.

The dashed line shows the sound pressure level using the method according to the invention for influencing the noise, wherein a linear extrapolation of the engine speed was performed according to the equation I for generating the reference signal. The delivery times t; each 100 milliseconds apart. The inventive method or the use of a system according to the invention for influencing noise considerably improves the active noise reduction over the entire speed range.

The present invention therefore provides a method for reliably influencing noise, in which an active device for influencing noise is provided with accurate information about the actually present excitation frequency of a noise source. Due to the method according to the invention, the system according to the invention provides particularly efficient noise control, although a reference variable characterizing the respective noise source is present only on a random basis.

A particular advantage of the present invention is that no additional sensor must be provided, but that system can be coupled directly to a data bus.

Although the present invention has been explained in more detail with reference to a preferred embodiment, it is not limited thereto, but variously modifiable. The stated delivery rates and data bus protocols are only to be understood as examples. An irregular provision of the reference size is also possible. An irradiation of secondary sound can also take place outside the vehicle interior, for example through loudspeakers in the exhaust system or in the air intake filter.

The invention is not limited to use in a motor vehicle, but may preferably be used whenever there are periodic noise excitations. This may also be the case, for example, with motor-driven fans, pumps, reciprocating compressors or other devices. Also switching frequencies at certain power electronics, which can be queried in a data bus, can be used as a possible reference size.

Furthermore, the method according to the invention or the extrapolation device and the device for influencing noise can be implemented completely computer-implemented. In this respect, for example, a programmable microcontroller device is conceivable, which carries out the erfϊndungsgemäße method in the programmed state.

Although the invention has been described using the example of vibration in-couplings in air as a fluid medium, an application to change structure-borne noise is also possible.

Reference sign list

1 system for active noise control

2 low-speed data bus

3 high-speed data bus

4 speed sensor

5 engine control

6 gateway

7 display device

8 positioner

9 extrapolation device

10 data line

11 Device for active noise control

12 reference signal

13 control signals

14 actor

15 microphone

16 engine

Claims

claims

1. A method for influencing noise, wherein a noise source (16), in particular a motor in a motor vehicle, generates the noise sound with a substantially periodic variable excitation, and wherein a characteristic of the noise source reference variable, in particular an engine speed, to given , consecutive delivery times (t;) is present, with the method steps:

- reading at least a first value (Ni _-1 ) of the reference quantity at a first provision time (tj-i) and a second predetermined value at a second provision time (tj);

- Generating the reference signal (12) at least one time (t) between the second delivery time (ti) and a third provision time (tj ₊ i) in response to the read out first and second values; and

- Providing the reference signal (12) to a device for active noise control (11), which generates depending on the reference signal (12) drive signals (13) for at least one actuator (14), wherein the at least one actuator (14) compensation sound radiates, which interferes with the noise.

2. The method according to claim 1, characterized

in that as the second predetermined value, a change parameter (N) of the reference quantity or a second value (Nj) of the reference variable is read out and the reference signal (12) is extrapolated in dependence on the first value (Nj-)) of the reference variable and the second value.

3. The method according to claim 1, characterized that is provided as a further method step:

- determining the change (ΔN) of the reference quantity between the first (tj.i) and the second delivery time (tj);

wherein the reference signal (12) is extrapolated in dependence on the value (Nj) of the reference quantity read out at the second delivery time (ti) and on the change (ΔN) of the reference quantity.

4. The method according to any one of the preceding claims, characterized in that linear extrapolation.

5. The method according to any one of the preceding claims, characterized in that the reference signal (12) is further extrapolated depending on further values of the reference variable to further provisioning times.

6. The method according to any one of the preceding claims, characterized in that the reference signal (12) is further extrapolated in dependence on further characteristic variables for the noise source.

7. The method according to any one of the preceding claims, characterized in that the reference variable is an engine speed or an exciting frequency, in particular of a motor.

8. The method according to any one of the preceding claims, characterized in that when extrapolating a delay time between a time of a change in the reference variable and a respective provision time, in particular by signal processing Times between a measuring sensor (4) and the reference size providing data bus (2), is taken into account.

9. The method according to any one of the preceding claims, characterized in that the compensation sound is emitted in such a way that from the periodic excitation derived harmonics of the noise source (16) are at least partially amplified and / or attenuated.

10. A system for active noise control (1), in particular in a motor vehicle, for altering noise, which is generated by a noise source (16), in particular a motor, with a substantially periodic variable excitation frequency, comprising:

a) a data bus (2), at which a reference variable, which characterizes the respective excitation frequency of the noise source (16), can be read out at predetermined provision times (tj);

b) an extrapolation device (9) coupled to the data bus (2) which generates a reference signal (12) associated with the reference magnitude, wherein respective values of the reference signal (12) extrapolate the reference magnitude between the provision times (t;); and with

c) a device for active noise control (11), which in response to the reference signal (12) generates control signals (13) for at least one actuator (14), wherein the at least one actuator (14) radiates compensation sound, which interferes with the noise.

11. System (1) according to claim 10, characterized in that a change parameter (N) of the reference variable can furthermore be read on the data bus (2), the extrapolation device (9) determining the reference variable as a function of at least one

_* Extrapoliert least one read value (Ni) of the reference size and the change parameter (N).

12. System (1) according to claim 10 or 11, characterized in that the extrapolation device (9) is arranged such that it carries out a method according to at least one of claims 1-9.

13. System (1) according to any one of claims 10 to 12, characterized in that in the generation of the reference signal further signal propagation times by the reading of the reference variable and / or a delay by providing the reference variable on the data bus (2) are taken into account.

14. System (1) according to any one of claims 10 to 13, characterized in that the data bus (2) is designed as a CAN bus, in particular in a vehicle.

15. System (1) according to one of claims 10 to 14, characterized in that the extrapolation device (9) and / or the device for active noise control (11) is designed as a digital signal processing device / s.

16. System (1) according to any one of claims 10 to 15, characterized in that the means for active noise control (11) generates the control signals such that derived by the compensation sound from the periodic vibration excitation harmonics of the noise source (16) at least partially amplified and / or be steamed.

17. The use of an active noise control system (1) according to any one of claims 10 to 16 in a motor vehicle, wherein the noise source is a motor, the reference quantity is an engine speed, and the data bus (2, 3, 6) as a CAN bus for an engine control (5) and for monitoring an engine condition.

18. Use according to claim 17, characterized in that as the further noise source characterizing quantities of data for the engine control (5), in particular acceleration values, pedal positions, pedal movements and / or circuit parameters are used.

19. Use according to claim 17 or 18, characterized in that in the motor vehicle a first, in an engine compartment reproached, high-speed CAN bus (3) and a second, held in a passenger compartment, low-speed CAN bus (2) are provided, wherein the reference variable and / or the further variables characterizing the noise source are read from the low-speed CAN bus (2).