Assembly and method for active control of the rolling noise for a motor vehicle

Abstract

Disclosed is an assembly (1) for active control of the rolling noise for a motor vehicle, comprising a path control device (2), comprising another sensor (22, 22') fastened on the steering knuckle (20, 20'), such as an accelerometer, the path control device (2) being capable of transmitting, to the anti-noise device (3), measurements obtained by the other sensor (22, 22'); the anti-noise device (3) being capable of generating an anti-noise signal depending on the acceleration measurements obtained and controlling its transmission via the loudspeaker (31).

Description

[0001] The invention relates to an assembly and a method for active control of rolling noise for a motor vehicle.

[0002] In the automotive field, it is well known to implement active noise control processes, producing anti-noise signals to reduce noise pollution in the vehicle cabin.

[0003] In particular, the solid-borne noise generated by the rolling of the motor vehicle on the road causes vibrations in the structure and consequently audible noise in the passenger compartment which can be particularly annoying for users.

[0004] In order to generate an active noise control signal to compensate for noise pollution from a motor vehicle, it is known that an anti-noise signal can be generated by a regulation command as a function of a reference signal and an error signal, such as a regulation of type Feedback, or regulation by anticipatory action, generally called by its English name of regulation Feedforward.

[0005] In particular, document EP2239728A2 and document EP2657086A1 are known, which disclose a system for active noise control based on the output of the audio system, in which the system generates an anti-noise signal emitted by the cabin audio system based on a sensor installed on the vehicle, such as an accelerometer.

[0006] However, one problem with such a solution is that it is necessary to install a sensor capable of providing the reference signal, which is relatively expensive and relatively complex to implement on an existing motor vehicle architecture.

[0007] Indeed, adding sensors to a motor vehicle requires, among other things, available installation space, available mounting, and additional wiring. However, obtaining available mountings in a motor vehicle architecture is a relatively significant difficulty.

[0008] Also, there is a need for an active noise control package that can solve the problems stated above.

[0009] To this end, an active rolling noise control assembly is proposed for a motor vehicle, comprising a trajectory control device comprising at least one wheel speed sensor fixed to a steering knuckle of a wheel of the motor vehicle, and an anti-noise device capable of controlling at least one loudspeaker installed in the passenger compartment of the motor vehicle.

[0010] The trajectory control device comprises at least one accelerometer fixed on said rocket carrier, said trajectory control device being adapted to transmit to said anti-noise device measurements obtained by said accelerometer; said anti-noise device being adapted to generate an anti-noise signal as a function of said measurements from said accelerometer and to control its emission via said loudspeaker.

[0011] This provides a high-performance active noise control system that can be adapted to existing vehicle architectures without creating additional bulk and weight.

[0012] In addition, a sensor installed on the steering knuckle provides a very good measurement of the source of rolling noise, with very high consistency, which is the tire / road contact because it is very close to this contact.

[0013] In other words, the sensors mounted on the steering knuckle provide a very good quality signal for rolling noise control according to the consistency criterion, which thus allows a significant gain in noise reduction performance.

[0014] Advantageously and in a non-limiting manner, the trajectory control device comprises for each wheel of the motor vehicle a speed sensor mounted on said steering knuckle associated with said wheel, characterized in that it further comprises for each wheel, another sensor mounted on said associated steering knuckle; said trajectory control device being adapted to transmit to said anti-noise device said measurements obtained by each of said other sensors, said anti-noise device being adapted to command the loudspeakers to emit an anti-noise signal depending on the measurements obtained from each of said other sensors.

[0015] This allows us to take into account the noise created in the passenger compartment by the rolling of each wheel on the passenger compartment, which improves active noise reduction.

[0016] Advantageously and in a non-limiting manner, the accelerometer comprises, for example, a tri-axis accelerometer. The assembly may also comprise an angular velocity sensor, such as a gyrometer, or a laser sensor. This makes it possible to take into account the vibration dynamics of the wheel on the roadway in a relatively complete manner, which makes it possible to obtain relatively robust reference signals.

[0017] According to the invention, said accelerometer is adapted to sample said measurements obtained from said associated stub axles at a frequency greater than or equal to 2000 Hz. Thus, it is possible to avoid implementing an anti-aliasing filter before digitizing the signal. Such an anti-aliasing filter costs in latency and delay on the signal. Thus, better system performance is ensured by this unfiltered sampling. Indeed, a sufficient sampling frequency is obtained to guarantee robust consideration of the vibration dynamics of rolling while having negligible aliasing of the spectrum for noise control up to 300 Hz.

[0018] According to the invention, said trajectory control device communicates with said anti-noise device via a low-latency communication bus, for example a maximum latency of one or two samples. This makes it possible to obtain a rapid transmission of the reference signals in order to allow effective active noise reduction.

[0019] According to the invention, said communication bus is adapted to transmit said measurements obtained by said other sensors at a frequency at least equal to said sampling frequency of said other sensors. This ensures that no new sampling of the data is carried out for the transmission of the data from the trajectory control device to the anti-noise device.

[0020] Advantageously and in a non-limiting manner, the assembly comprises in the passenger compartment of the motor vehicle, at least one microphone capable of capturing the noise to be reduced present in the passenger compartment; said anti-noise device being adapted to control the loudspeakers to emit an anti-noise signal also as a function of said ambient noise captured by said at least one microphone. This microphone thus allows the implementation of a feedback loop control, generally called Feedback, in which the error signal is obtained by the microphone.

[0021] The invention also relates to a method for active control of rolling noise for a motor vehicle according to claim 4 implemented by an anti-noise device of an assembly as described previously.

[0022] Advantageously and in a non-limiting manner, the generation of an anti-noise signal is implemented by an anticipatory action control, also called an anticipatory action control, called Feedforward , in which the reference signal corresponds to all the sampled measurements of said other sensors, and at least one error signal is provided by sampling at least one sound obtained by at least one microphone in the passenger compartment of the motor vehicle. This thus makes it possible to obtain a relatively efficient and robust anti-noise signal.

[0023] The invention also relates to a motor vehicle comprising an assembly as described previously in which the anti-noise device implements the method as described previously.

[0024] Other features and advantages of the invention will emerge from reading the description given below of a particular embodiment of the invention, given for informational purposes but not as a limitation, with reference to the appended drawings in which: There figure 1 is a schematic view of a motor vehicle comprising an assembly according to the invention; The figure 2 is a flowchart of a process implemented by the noise reduction device of the entire figure 1 ; There figure 3 is a diagram of a control by anticipatory action, called Feedforward as implemented by the anti-noise device according to the invention.

[0025] THE figures 1 à 3 relating to the same embodiment of the invention, they will be commented on simultaneously

[0026] A motor vehicle, as shown figure 1 , includes a set 1 of active noise control in the passenger compartment of the motor vehicle.

[0027] In particular, the invention relates to the active control of noise caused by wheel vibrations when driving on the road, vibration which is transmitted to the entire structure of the vehicle and creates noise in the passenger compartment by fluid / structure coupling.

[0028] In order to control and reduce this noise, the assembly 1 comprises on the one hand the trajectory control device 2 of the motor vehicle as well as an anti-noise device 3.

[0029] The trajectory control device 2, also known as ESP , from English Electronic Stability Program , in particular allows the vehicle to remain on a correct trajectory in the event of loss of grip.

[0030] The trajectory control device 2 comprises in particular for each wheel 10, 10' of the motor vehicle a wheel speed sensor 21, 21', generally mounted on the steering knuckle 20, 20' of the corresponding wheel 10, 10'.

[0031] In fact, the installation of speed sensors 21, 21' on the steering knuckles 20, 20' of the drive axle, generally at the front, is consistent with certain solid-borne noises whose source is the powertrain, abbreviated to GMP.

[0032] In fact, the transmissions connect the powertrain and the stub axles 20, 20'; they transmit the engine torque, which is their main function, but also the vibrations of the powertrain. The invention is therefore also effective in reducing certain noises from the powertrain.

[0033] In a motor vehicle of the prior art, the trajectory control device 2 is independent and not connected to the anti-noise device 3 whose function is remote.

[0034] The noise canceling device 3, here is an active noise reduction device, also known as ANC for Active Noise Control.

[0035] Many types of active noise-cancelling devices 3 are known from the prior art.

[0036] The invention does not aim to describe the precise operation of a particular type of active noise control, the principle of which based on interference between two waves is well known to those skilled in the art.

[0037] Various types of noise control are known for such noise-cancelling devices. In particular, open-loop controls are known, which are implemented without an error sensor, but with a reference signal from the source. Also known are noise-cancelling controls. Feedback in which a regulation is carried out with a correction according to an error signal and we also know the controls Feedforward in which the correction is carried out as a function of the error signal and the reference signal.

[0038] As part of an anti-noise control aimed at reducing the solid-borne rolling noise of a motor vehicle, only the control Feedforward allows you to obtain a satisfactory result.

[0039] Rolling noise is random and therefore makes it unpredictable, unlike engine noise, whose harmonics have a slower evolution in phase and amplitude.

[0040] Furthermore, engine noise has a relatively narrow spectrum, whereas rolling noise has a broad spectrum.

[0041] Therefore only a control Feedforward allows a satisfactory result to be obtained in the context of active reduction of solid-borne rolling noise.

[0042] However, control Feedforward requires on the one hand a coherence of the reference signals x and error e, which in the case of a random signal is relatively complex, but also a constraint of measurement time of these signals.

[0043] In a control system Feedforward it is necessary to obtain a reference signal x which corresponds to the source of the generated noise, and an error signal e which corresponds to the noise remaining after processing.

[0044] For this purpose, the assembly 1 comprises at least one 32-32" microphone, for example 3 microphones, for detecting the error signal e.

[0045] These 32-32" microphones are installed in the passenger compartment, and although shown in the upper part on the figure 1 , they can be installed in other places in the passenger compartment, particularly in the lower part, so as to capture persistent noise after noise reduction.

[0046] The reference signal x is the measurement of the vibrations on the vehicle structure that propagate from the wheels.

[0047] The trajectory control device 2 comprises for each wheel, in addition to the speed sensors 21, 21', sensors 22, 22', in this particular embodiment accelerometers 22, 22', in particular tri-axis accelerometers, mounted integrally with the steering knuckles 20, 20' of each wheel 10, 10'.

[0048] In particular, these sensors 22, 22' are integrated into the speed sensors 21, 21', which means that they do not need to be fixed independently, solving the problem of sensor fixing points to the structure of the motor vehicle.

[0049] The invention is however not limited to accelerometers as sensors, but relates to any type of sensor integrated into the trajectory control device and fixed to the rocket carrier 20, 20'.

[0050] In particular, laser sensors that measure the roughness of the road or the relative displacement between the two faces of the wheel bearing also provide particularly relevant reference signals and can be integrated into the wheel speed sensor 21, 21'. The position and shape of the speed sensor 21, 21' make it particularly suitable for carrying such a laser sensor that measures the displacement of the face of the bearing on the rotating side because it is on this face that the magnetic targets used to measure the wheel speed are located. According to a particular implementation of the invention, a gyrometer can also be installed in the trajectory control device for each wheel, this gyrometer being able to be integrated in the speed sensor 21, 21', for example in addition to the accelerometer and / or the radar.

[0051] Each gyrometer provides additional reference signals that can improve active noise reduction. However, adding this additional data requires that the communication bus 5 be adapted to transmit this data sufficiently quickly.

[0052] For this purpose, the trajectory control device 2 comprises for each wheel, in addition to the speed sensors 21, 21', accelerometers 22, 22', in particular tri-axis accelerometers, mounted integrally with the steering knuckles 20, 20' of each wheel 10, 10'.

[0053] Such an installation of accelerometers makes it possible to reliably measure the vibrations of the wheels on the road, while capturing this wave as early as possible before it propagates towards the passenger compartment.

[0054] Indeed, in an ANC system by anticipatory action, called Feedforward, the anti-noise signal is generated by the convolution of the noise measured by the microphone 32,32" and the reference signal obtained by the accelerometers 22, 22'.

[0055] The anti-noise device 3 generating this anti-noise signal and emitting it from a loudspeaker 31 installed in the passenger compartment of the vehicle, this having the effect of causing an attenuation, tending towards the cancellation of the unwanted noise.

[0056] For this purpose, the anti-noise signal must reach the error signal microphone 32.32" earlier than the unwanted noise propagating from the wheels to the passenger compartment.

[0057] Also, in reference to the figure 3 , the total delay of the reference path 300, including the noise controller 302 and the secondary path 303 must be smaller than that of the primary path 301, which corresponds to the propagation of the sound from the wheels to the passenger compartment, the summation 304 corresponding to the error captured by the error microphone 32-32". This is a causality constraint, and if this condition is not satisfied, the ANC system Feedforward cannot adequately reduce unwanted noise.

[0058] In order to ensure this causality constraint, the accelerations measured by the 22,22' accelerometers are sampled at a relatively high frequency, preferably greater than 2000 Hz. Thus, such raw, in other words unfiltered, high-frequency sampling avoids the use of an anti-aliasing low-pass filter which penalizes latency, since a filter always introduces a phase shift and therefore a delay. Indeed, at such frequencies, the aliasing error is negligible for noise control up to 300 Hz.

[0059] The acceleration signals being first captured by the trajectory control device 2, according to the conventional transmission buses of this device 2, these signals are then sent to the anti-noise device 3.

[0060] In order to ensure fast transmission, a low-latency communication bus 5 is installed between the trajectory control device 2 and the noise reduction device 3.

[0061] For a digital bus as implemented in the invention, low latency means one or at most two latency samples with a frequency greater than or equal to 2000 Hz.

[0062] This communication bus 5 is particularly suitable for transmitting data at a frequency at least equal to the sampling frequency of the accelerometers.

[0063] Furthermore, this communication is optimized by the communication bus 5 by transmitting the unfiltered raw data.

[0064] Each accelerometer 22, 22', being associated with three axes in this embodiment, and the vehicle comprising, in this exemplary embodiment, four wheels 10, 10', this is a total of 12 sampled signals to be transmitted between the trajectory control device 2 and the anti-noise device 3.

[0065] The anti-noise device 3 then implements a method comprising on the one hand the reception 201 of the sampled signals, the generation of an anti-noise signal 202, then the emission 203 of the anti-noise signal by the loudspeaker 31 in the passenger compartment.

[0066] The generation 202 of the anti-noise signal being implemented by the control Feedforward, depending on the signal(s) from the 32-32" error microphone(s) and the received samples of the reference signal x.

Claims

1. Active rolling noise control assembly (1) for a motor vehicle, comprising a trajectory control device (2) comprising at least one wheel speed sensor (21, 21') fixed to a steering knuckle (20, 20') of a wheel (10, 10') of the motor vehicle, and an anti-noise device (3) able to command at least one loudspeaker (31) installed in the passenger compartment of the motor vehicle, the trajectory control device (2) comprising at least one accelerometer (22, 22') fixed to said steering knuckle (20, 20'), said trajectory control device (2) being designed to transmit, to said anti-noise device (3), measurements obtained by said accelerometer (22, 22'); characterized in that said accelerometer (22, 22') is designed to sample said measurements obtained from said associated steering knuckle (20, 20') at a frequency greater than or equal to 2000 Hz; and said trajectory control device (2) communicates with said anti-noise device (3) via a low-latency communication bus (5), for example with a maximum latency of one or two samples; said communication bus (5) being designed to transmit said measurements obtained by said accelerometer (22, 22') at a frequency at least equal to said sampling frequency of said accelerometer; said anti-noise device (3) being designed to generate an anti-noise signal on the basis of said raw measurements obtained from said accelerometer (22, 22') and command the emission thereof via said loudspeaker (31).

2. Assembly (1) according to Claim 1, wherein the trajectory control device comprises, for each wheel (10, 10') of the motor vehicle, a speed sensor (21, 21') mounted on said steering knuckle (20, 20') associated with said wheel (10, 10'), characterized in that it furthermore comprises, for each wheel (10, 10'), an accelerometer (22, 22') mounted on said associated steering knuckle (20, 20); said trajectory control device (2) being designed to transmit, to said anti-noise device (3), said measurements obtained by each of said accelerometers (22, 22'); said anti-noise device (3) being designed to command the loudspeaker (31) to emit an anti-noise signal on the basis of said measurements obtained from each of said accelerometers (22, 22').

3. Assembly (1) according to either one of the preceding claims, characterized in that it comprises, in the passenger compartment of the motor vehicle, at least one microphone (32-32'') able to pick up the noise to be reduced that is present in the passenger compartment; said anti-noise device (3) being designed to command the loudspeakers (31) to emit an anti-noise signal on the basis also of said ambient noise picked up by said at least one microphone (32-32'').

4. Active rolling noise control method (200) for a motor vehicle, implemented by an anti-noise device (3) of an assembly (1) according to any one of the preceding claims, characterized in that it comprises steps of: - Receiving (201) at least one set of sampled values of measurements acquired by said accelerometers (22, 22') of the trajectory control device; - Generating (202) an anti-noise signal on the basis of said received sampled values; and - Emitting (203) said anti-noise signal via said loudspeakers of said anti-noise device.

5. Method (200) according to Claim 4, characterized in that an anti-noise signal is generated (202) by a feedforward command, in which the reference signal corresponds to all of the sampled measurements from said accelerometers (22, 22'), and an error signal is supplied by sampling a sound obtained by a microphone (32-32") in the passenger compartment of the motor vehicle.

6. Motor vehicle comprising an assembly (1) according to any one of Claims 1 to 3 and implementing a method (200) according to Claim 4 or 5.

Images