CN113272892A

CN113272892A - Feedforward active control system for motor vehicle operating noise with reference sensor adjacent to multimedia system

Info

Publication number: CN113272892A
Application number: CN201980079547.6A
Authority: CN
Inventors: G·博代
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 2018-11-05
Filing date: 2019-10-24
Publication date: 2021-08-17
Anticipated expiration: 2039-10-24
Also published as: FR3088134A1; WO2020094408A1; FR3088134B1; CN113272892B; EP3877972A1

Abstract

An active control system of the running noise of a motor vehicle is disclosed, comprising a multimedia system comprising an electronic board (1) integrated into a casing (2) attached to the motor vehicle. The system comprises at least one error microphone (7) and at least one sensor (12) attached to the passenger compartment of the tyre vehicle, adjacent to the housing (2) of the multimedia system.

Description

Feedforward active control system for motor vehicle operating noise with reference sensor adjacent to multimedia system

Technical Field

The present invention relates to the field of reducing the noise nuisance of motor vehicles, and in particular to reducing the noise generated by running tires on a road or by an engine.

Background

At low frequencies below 400Hz, the contact between the active element, such as the engine, or the tyre, and the road surface introduces a force at some point of the vehicle, generating vibrations that are transmitted to the entire structure of the vehicle, in particular to all the panels (windows, roof, floor, etc.) inside the vehicle. Then, the vibration of these panels generates noise internally.

At high frequencies above 1000Hz, the path of the noise is mainly airborne. This noise passes directly through the vehicle structure.

It is increasingly difficult to find passive solutions for reducing such operational noise, since passive solutions seek to reduce the weight of the motor vehicle.

Furthermore, known active control systems for operating noise are particularly expensive and are not continuously applied in the construction of motor vehicles.

The principle of active noise control (often abbreviated ANC) is to address acoustics and vibrations in the linear domain. Thus, at one or more points of the interior near the passenger's ears, the noise generated by the vehicle is placed in anti-phase with the noise applied by active control to attenuate or even eliminate the noise of the interior.

The noise applied by active control is generated by internal sound generators, which are usually the loudspeakers of the vehicle for the multimedia system.

There are two active control architectures.

An architecture known as "feedback" can be seen in fig. 1a, where only information about the error e (n) is available when one or more microphones are used internally. These signals are referred to as "error signals". However, active control based on feedback is not very effective for operational noise.

An architecture known as "feed forward" can be seen in fig. 1b, where information about the error e (n) can be obtained by a microphone internal (as in the feedback architecture), but there is also information about the source of the noise to be attenuated d (n). The measured signal that provides information about the source is referred to as the "reference signal". For active control to be effective, two constraints related to internal noise must be observed.

The coherency constraint conditions are as follows: the reference signal must be the cause of the internal noise. This causal relationship is mathematically quantified by a coherence function that is between 0 and 1 and represents the proportion of power of one signal that is produced by the other signal. For example, if the coherence between the reference signal and the noise is 0.5, it means that half of the noise power is generated by the reference signal. Furthermore, the control algorithm will only be able to reduce part of the power, thus, in the best case, reducing half the noise power. In the presence of multiple reference signals (to enhance correlation), causal relationships are quantified by a polyphase drying function. The coherence between the reference signal and the noise must be as strong as possible.

The time delay constraint condition is as follows: since the operating noise is random, at any one instant, it is unpredictable what happens at the next instant. Thus, the reference signal from the source must be causally earlier than the internal noise in order to allow the control algorithm to calculate the times of the commands for the speaker and to propagate these commands to the point where the internal noise is being controlled. If the delay required for the computation and command propagation is T, the propagation delay between the reference signal and the internal noise must be greater than T. This delay can be quantified by a correlation function between the reference signal and the noise.

Such active control is very effective if the reference signal obeys both coherence and delay constraints: it allows noise attenuation over a wide frequency band without amplifying other frequencies.

In addition to microphones, feed forward active control requires the use of sensors to measure the source of the noise to be controlled. In the case of running noise, these sources are the four points of contact between the tire and the road. The sensors for measuring the source may measure, for example, velocity and acceleration in displacement, rotation, translation or rotation, stress in structural parts, etc.

The known document US 2017330551-a 1 describes a method for optimizing the reference signal selection for so-called feed-forward active control of operational noise. However, the sensors used are close to the wheels in the vehicle sub-frame, involving the use of cables and sensors that are resistant to particularly harsh environments, resulting in significant costs.

Document WO 92/08225-a1 is also known, which describes the acoustic treatment of the noise generated by a motor vehicle by using a sensor of the vibration of the vehicle body arranged inside the vehicle.

There is a need to reduce the operating noise of motor vehicles in a manner that is less costly and continuously applicable to motor vehicles.

Disclosure of Invention

It is therefore an object of the present invention to develop a method and a system which are low-cost, continuously applicable to motor vehicles and which can be configured for attenuating operating noise.

The subject of the invention is an active control system of the running noise of a motor vehicle comprising a multimedia system comprising an electronic circuit board incorporated in a casing fixed inside the motor vehicle.

The active control system of the operating noise comprises a microphone for the error signal and at least one sensor for the reference signal, which is fixed in the vehicle interior close to the housing of the multimedia system, in particular the electronic circuit board of the multimedia system.

Therefore, the system for reducing the operating noise of motor vehicles uses, as reference signals, the measured values from one or more sensors (called "reference sensors") fixed directly on or close to the electronic circuit board of the multimedia system, which already contains most of the components required for active control, such as computers and audio amplifiers. Thus, the elements already present on the vehicle are used in a protected environment requiring little or no use of cables.

Advantageously, the sensor is fixed directly on the electronic circuit board of the multimedia system. This embodiment does not require cables and connectors.

According to another embodiment, the reference sensor is fixed directly to the vehicle structure inside. It is linked to the multimedia system by a single cable that is used for both the sensor and the error microphone. It is a serial data digital bus that allows information to be transferred from all sensors over a single cable. This makes it possible to limit the number of cables and connectors.

For example, in the case of a multimedia housing fixed to a dashboard cross member, the reference sensor can be fixed to a cross member of the dashboard of the motor vehicle.

According to another embodiment, the system comprises at least two sensors fixed to the electronic circuit board at the positions to be selected or to the internal vehicle structure, for example the dashboard crossbeam.

According to a second aspect, the invention relates to a motor vehicle comprising a multimedia system comprising an electronic circuit board incorporated in a casing fixed inside the motor vehicle, and an active control system of the operating noise as previously described.

Tests on vehicles have demonstrated that, as described in the present invention, the reference signal measured by the reference sensor complies with the constraints of coherence and time delay, thus allowing effective control of the operating noise.

Drawings

Other objects, features and advantages of the present invention will become apparent upon reading the following description, given purely by way of non-limiting example and with reference to the accompanying drawings, in which:

figures 1a and 1b illustrate an automation scheme of feedback control and feedforward control, respectively;

figure 2 very schematically depicts a motor vehicle comprising an active control system of the motor vehicle running noise according to an embodiment of the invention;

figure 3 depicts in detail the active control system of the operational noise of figure 2;

figure 4 depicts an active control system of the running noise of a motor vehicle according to a second embodiment of the invention; and

fig. 5 depicts an active control system of the running noise of a motor vehicle according to a third embodiment of the invention.

Detailed Description

Fig. 1 very schematically shows an electronic circuit board 1 of a multimedia system (radio, navigation system) of a motor vehicle, intended to be incorporated in a housing 2, for example fixed to a cross-member 3 of the dashboard (not shown) of the vehicle.

The electronic circuit board 1 of the multimedia system contains many components necessary for active control, such as, in particular, a computer 4 configured for performing active noise control and an audio amplifier 5.

As illustrated, the active control system 10 operating on noise comprises a sensor 12 fixed directly on the electronic circuit board 1. As a variant, it would be possible to provide several sensors fixed on the plate 1.

So-called structure-borne operating noise can cause vibrations of the entire structure of the vehicle, including the housing of the electronics containing the multimedia system (such as radio and navigation systems). The housing is rigidly fixed to a cross member below the dashboard of the motor vehicle.

Thus, the source of the noise can be measured using sensors directly mounted on the motherboard of the multimedia system, which has been masked from the processor executing the Active Noise Control (ANC) program.

In the case of conventional systems where the reference sensor is fixed near the wheel, the transmission of physical information from the noise source occurs through a vibrational path rather than an electronic path.

Thus, standard, inexpensive sensors may be used without the use of special cables and connectors, as it is the circuitry etched on the electronic circuit board that sends the measured signals to the ANC processor.

Preferably, one to six reference acceleration signals are measured, for example at one or two points on the electronic circuit board.

The active control system 10 of operational noise further comprises one or more microphones 7 fixed inside the vehicle. These microphones 7 may provide error signals.

Thus, information about the error can be obtained by an internal microphone (as in the feedback architecture), but also information about the source of the noise to be attenuated, i.e. about the source of the reference signal.

The noise applied by active control is generated by internal sound generators, which are usually the vehicle's speakers 8 for the multimedia system.

The embodiment illustrated in fig. 2 differs from the embodiment illustrated in fig. 1 only in the installation of the sensor 12 of the active noise control system 10. In fact, if it is not possible to mount the sensor on the plate of the multimedia system, for example because it cannot be modified, it is possible to envisage mounting the sensor 12 on a vehicle structure inside as close as possible to the casing of the multimedia system, for example on the cross-member 3 of the dashboard. Thus, the sensor 12 remains in a protected environment and the necessary wiring is relatively short.

Two sensors a few centimeters apart may also be used.

The embodiment illustrated in fig. 3 differs from the embodiment illustrated in fig. 2 only in the installation of the sensor 12 of the active noise control system 10. In the present embodiment, the sensor 12 is directly fixed to the vehicle structure inside. The sensor is linked to the multimedia system by a cable 6 linking the multimedia casing 2 to an error microphone 7 present inside the vehicle.

It is also contemplated that the embodiments may be combined together.

Thus, by means of the invention, the measured values of the sensors fixed on the electronic circuit board of the multimedia system, which already contains most of the components necessary for active control, such as a computer and an audio amplifier, are used as reference signals. Thus, the elements already present on the vehicle are used in a protected environment requiring little or no use of additional cables.

Furthermore, such an active noise control system uses a reference signal that obeys both coherence constraints and delay constraints, which makes it particularly effective. It indeed allows noise attenuation over a wide frequency band without amplifying other frequencies.

Claims

1. Active control system of the running noise of a motor vehicle comprising a multimedia system comprising an electronic circuit board (1) incorporated in a casing (2) fixed inside the motor vehicle, characterized in that it comprises at least one error microphone (7) and at least one reference sensor (12) fixed inside the vehicle, close to the casing (2) of the multimedia system.

2. The system of claim 1, wherein the sensor (12) is directly fixed on an electronic circuit board (1) of the multimedia system.

3. The system of claim 1, wherein the sensor (12) is linked to a computer (4) fixed on the electronic circuit board (1) and configured to perform active noise control.

4. The system as claimed in claim 1, wherein the sensor (12) is fixed to a cross-member (3) of the dashboard of the motor vehicle.

5. The system of claim 1, wherein the sensor (12) is secured directly to an internal vehicle structure. The sensor is linked to the multimedia system by a cable (6) linking the multimedia casing (2) with a microphone (7) present inside the vehicle.

6. The system of any one of the preceding claims, comprising at least two reference sensors (12).

7. The system of any one of the preceding claims, wherein at least one sensor (12) is an accelerometer.

8. A motor vehicle comprising an active control system of the operating noise according to any one of the preceding claims and a multimedia system comprising an electronic circuit board (1) incorporated in a casing (2) fixed inside the motor vehicle.