阅读说明：本技术 挖掘机驾驶室结构声和空气声混合主动控制系统及控制方法 (Active control system and control method for mixing structural sound and air sound of excavator cab ) 是由 卢炽华 李晓龙 刘志恩 刘跃吉 单昆 吴锦 陈超 彭辅明 于 2021-06-23 设计创作，主要内容包括：本发明提供了一种挖掘机驾驶室结构声和空气声混合主动控制系统及控制方法,包括功率放大器,以及同时与功率放大器连接的扬声器、作动器和控制器；控制器还通过FIR低通滤波器与振动传感器连接,声压传感器也与控制器连接；所述振动传感器、作动器以及扬声器设置在挖掘机驾驶室上,声压传感器设置在挖掘机驾驶室内。本发明具有易于实现、稳定性好,主动噪声控制效果好,成本低等优点。(The invention provides a structure sound and air sound mixed active control system and a control method for an excavator cab, which comprises a power amplifier, a loudspeaker, an actuator and a controller, wherein the loudspeaker, the actuator and the controller are simultaneously connected with the power amplifier; the controller is also connected with the vibration sensor through an FIR low-pass filter, and the sound pressure sensor is also connected with the controller; the vibration sensor, the actuator and the loudspeaker are arranged on the cab of the excavator, and the sound pressure sensor is arranged in the cab of the excavator. The invention has the advantages of easy realization, good stability, good active noise control effect, low cost and the like.)

1. A structure sound and air sound mixed active control system of an excavator cab is characterized by comprising a power amplifier, a loudspeaker, an actuator and a controller, wherein the loudspeaker, the actuator and the controller are simultaneously connected with the power amplifier; the controller is also connected with the vibration sensor through an FIR low-pass filter, and the sound pressure sensor is also connected with the controller; the vibration sensor, the actuator and the loudspeaker are arranged on the cab of the excavator, and the sound pressure sensor is arranged in the cab of the excavator.

2. The excavator cab structural sound and aeroacoustic hybrid active control system of claim 1 wherein the system includes two modes for active control of the excavator cab structural and control noise simultaneously;

under a system identification mode, the engine of the excavator is not operated, the controller outputs two independent random signals to be applied to the actuator and the loudspeaker, the actuator enables the cab panel to vibrate, and the vibration signals are collected by the vibration sensor and input into the controller; sound signals generated by the loudspeaker are collected by the sound pressure sensor and input into the controller, and the controller obtains the structural sound frequency of the controlled cab panel according to the output actuating force and the input vibration signals; the controller obtains an impulse response function between the loudspeaker and the sound pressure sensor according to the output noise signal and the input noise signal, and the function is used as the compensation of the time delay of the sound pressure sensor when the controller makes the loudspeaker send out the offset noise in the control mode;

in the system control mode, an engine of the excavator is operated, the controller receives vibration signals from the sensor, outputs vibration signals of a target frequency, and applies the vibration signals to the actuator after passing through the power amplifier so as to counteract the vibration of the cab bread board, thereby reducing structural sound; the controller also receives the engine crank angle signal to identify the engine speed so as to obtain the frequency of the noise of the controlled engine, outputs the sound pressure signal of the compensated target frequency, and applies the sound pressure signal to the loudspeaker after passing through the power amplifier so as to counteract the engine noise in the cab and reduce the air noise, thus realizing the mixed control of the structure sound and the air sound of the cab of the excavator.

3. The excavator cab structural sound and aero sound hybrid active control system of claim 1 wherein the controller is configured to calculate the structural sound frequency of the cab panel from the outputs of the actuators and the input signals collected by the sensors in the system identification mode to generate the control signal at the target frequency.

4. The excavator cab structural sound and aero sound hybrid active control system of claim 1 wherein the low pass filter cut-off frequency is adjustable and after obtaining the cab panel structural sound frequency the low pass filter cut-off frequency setting is higher than the cab panel first order structural sound frequency.

5. A control method of an excavator cab structural sound and air sound hybrid active control system is characterized in that the working process of the excavator cab structural sound and air sound hybrid active control system is as follows:

step 1, mounting a vibration sensor and an actuator at the position of an anti-node of a panel modal shape; installing an acoustic pressure sensor at a headrest of a driver seat;

step 2, an engine of the excavator is closed, the cab is not subjected to external vibration excitation and noise interference at the moment, the controller is in a system identification mode, white noise is output by the controller and acts on the actuator through the amplifier, and the actuator excites a panel of the cab of the excavator to enable the panel to vibrate;

step 3, collecting a panel vibration signal by a sensor, inputting the panel vibration signal into a controller after passing through an FIR filter, and calculating the structural sound frequency of the driving panel of the excavator by the controller according to the output white noise signal and the input vibration signal; the first-order frequency is the target control frequency of the structural sound; setting the cut-off frequency of the FIR low-pass filter to be higher than the first-order structural sound frequency so as to reserve only the vibration information of the first-order resonance frequency as far as possible;

step 4, keeping the engine of the excavator closed, stopping the controller from outputting a white noise control signal to the actuator, outputting the white noise by the controller, acting the white noise on the loudspeaker through the amplifier, collecting the noise generated by the loudspeaker by the sound pressure sensor and inputting the noise into the controller, calculating an impulse response function from the loudspeaker to the sound pressure sensor by the controller according to the output white noise signal and the input noise signal, wherein the impulse response function is used as the compensation of the time delay of the sound pressure sensor for the loudspeaker to send out the offset noise under the control mode of the controller,

step 5, the excavator engine starts to work, vibration of the excavator engine is transmitted to a cab panel, panel vibration signals are collected by a sensor and are used as input of a controller after passing through a filter, the controller automatically calculates control signals of target frequency, the control signals act on an actuator through a power amplifier, the actuator generates reverse vibration to inhibit the vibration of the cab panel from radiating noise, and therefore control of the structural sound of the excavator cab is achieved; the noise is transmitted into a cab, a noise signal is collected by a microphone and is input into a controller to control and simultaneously receive a crank angle signal of an engine, so that the rotating speed of the engine is obtained, the frequency of the noise of the controlled engine is obtained, the controller automatically calculates a control signal of a target frequency, the control signal acts on a loudspeaker through a power amplifier to send out offset noise, the noise of the engine at the position where the microphone is located is offset, and the control of the air sound of the cab of the excavator is realized.

Technical Field

The invention relates to the field of active noise control, in particular to a structure sound and air sound mixed active control system and a control method for an excavator cab.

Background

With the further acceleration of the urbanization process, the demand of engineering machinery such as an excavator is increasing day by day, and meanwhile, the sustainable development concept of environmental protection is deeply conscious, so that people do not only pay attention to the use performance of the excavator any more, but also put forward higher requirements on the NVH performance of the excavator. When the excavator works, the engine vibrates greatly, and the vibration is transmitted to the frame through the engine suspension and then transmitted to the cab. The excavator cab has a plurality of thin plate structures, and vibration is easily generated under external excitation, so that low-frequency structure noise is radiated. In addition, the cab of the excavator is usually close to the engine, the sound insulation effect of the cab is poor, the noise of the engine cannot be effectively attenuated and is transmitted into the cab, a driver is in a high-noise working environment for a long time, the working efficiency is slightly influenced, and the physical and psychological health is seriously damaged.

In order to reduce the structural sound and the air sound of the cab, the three aspects of an excitation source, namely an engine, a transmission path of the excitation source, namely an engine suspension and a frame, and a receiver, namely a thin-wall panel of the cab can be started. For structural sound, the vibration transmitted to a driving panel can be reduced to a certain extent by optimizing the vibration of an engine, an engine suspension and a frame, and the engine suspension and the frame are required to be matched again, so that the optimization period is long, and the cost is high. Further, even if the vibration transmitted to the cab is reduced, the peak frequency of the engine vibration is correlated with the ignition order and the engine speed, and the peak frequency of the vibration of the main order easily approaches the cab panel resonance frequency during the engine operation, thereby causing the cab panel to vibrate and radiating low-frequency structural sound. For air sound, measures such as enhancing the sealing performance of the cab and designing an acoustic bag for the cab can be improved, but the method not only designs the change of the whole structure of the excavator cab, so that the optimization period is long, the cost is high, and the low-frequency noise effect of the engine is not obvious.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the problems of the prior art, the invention provides 1. an excavator cab structural sound and air sound hybrid active control system, which is characterized by comprising a power amplifier, a loudspeaker, an actuator and a controller, wherein the loudspeaker, the actuator and the controller are simultaneously connected with the power amplifier; the controller is also connected with the vibration sensor through an FIR low-pass filter, and the sound pressure sensor is also connected with the controller; the vibration sensor, the actuator and the loudspeaker are arranged on the cab of the excavator, and the sound pressure sensor is arranged in the cab of the excavator.

In the excavator cab structural sound and air sound mixed active control system, the system comprises two modes, and the active control can be simultaneously carried out on the structural noise and the control noise of the excavator cab.

Under a system identification mode, the engine of the excavator is not operated, the controller outputs two independent random signals to be applied to the actuator and the loudspeaker, the actuator enables the cab panel to vibrate, and the vibration signals are collected by the vibration sensor and input into the controller; the sound signal generated by the loudspeaker is collected by the sound pressure sensor and input into the controller. The controller obtains the structural sound frequency of the controlled cab panel according to the output actuating force and the input vibration signal; the controller obtains an impulse response function between the loudspeaker and the sound pressure sensor according to the output noise signal and the input noise signal, and the function is used as the compensation of the time delay of the sound pressure sensor when the controller makes the loudspeaker send out the counteracting noise in the control mode.

In the system control mode, an engine of the excavator is operated, the controller receives vibration signals from the sensor, outputs vibration signals of a target frequency, and applies the vibration signals to the actuator after passing through the power amplifier so as to counteract the vibration of the cab bread board, thereby reducing structural sound; the controller also receives the engine crank angle signal to identify the engine speed so as to obtain the frequency of the controlled engine noise, and the controller outputs a sound pressure signal of the compensated target frequency, and the sound pressure signal is applied to a loudspeaker after passing through a power amplifier so as to counteract the engine noise in the cab and reduce the air noise. Therefore, the mixed control of the structural sound and the air sound of the cab of the excavator is realized.

In the above-mentioned excavator cab structure sound and air sound hybrid active control system, in the system identification mode, the controller can calculate the structure sound frequency of the cab panel according to the output of the actuator and the input signal collected by the sensor, thereby generating the control signal of the target frequency.

In the excavator cab structural sound and air sound mixed active control system, the cut-off frequency of the low-pass filter is adjustable, and after the structural sound frequency of the cab panel is obtained, the set value of the cut-off frequency of the low-pass filter is higher than the first-order structural sound frequency of the cab panel.

In the above described excavator cab structural sound and aeroacoustic hybrid active control system, the working process of the excavator cab structural sound and aeroacoustic hybrid active control system is as follows:

step 1, mounting a vibration sensor and an actuator at the position of an anti-node of a panel modal shape; the sound pressure sensor is installed at the headrest of the driver seat.

And 2, closing the engine of the excavator, wherein the cab is not subjected to external vibration excitation and noise interference. The controller is in a system identification mode, outputs white noise, acts on the actuator through the amplifier, and the actuator excites the panel of the cab of the excavator to enable the panel to vibrate;

and 3, collecting a panel vibration signal by the sensor, passing the panel vibration signal through the FIR filter, and inputting the panel vibration signal into the controller. The controller calculates the structural sound frequency of the driving panel of the excavator according to the output white noise signal and the input vibration signal; the first-order frequency is the target control frequency of the structural sound; setting the cut-off frequency of the FIR low-pass filter to be higher than the first-order structural sound frequency so as to reserve only the vibration information of the first-order resonance frequency as far as possible;

and 4, keeping the engine of the excavator closed. The controller stops outputting the white noise control signal to the actuator. The controller outputs white noise, the white noise is acted on the loudspeaker through the amplifier, and the noise generated by the loudspeaker is collected by the sound pressure sensor and is input into the controller. The controller calculates an impulse response function from the loudspeaker to the sound pressure sensor according to the output white noise signal and the input noise signal, and the function is used as the compensation of the time delay for enabling the loudspeaker to send out the offset noise to be transmitted to the sound pressure sensor under the control mode of the controller.

Step 5, the excavator engine starts to work, vibration of the excavator engine is transmitted to a cab panel, panel vibration signals are collected by a sensor and are used as input of a controller after passing through a filter, the controller automatically calculates control signals of target frequency, the control signals act on an actuator through a power amplifier, the actuator generates reverse vibration to inhibit the vibration of the cab panel from radiating noise, and therefore control of the structural sound of the excavator cab is achieved; the noise is transmitted into a cab, a noise signal is collected by a microphone and is input into a controller to control and simultaneously receive a crank angle signal of an engine, so that the rotating speed of the engine is obtained, the frequency of the noise of the controlled engine is obtained, the controller automatically calculates a control signal of a target frequency, the control signal acts on a loudspeaker through a power amplifier to send out offset noise, the noise of the engine at the position where the microphone is located is offset, and the control of the air sound of the cab of the excavator is realized.

The excavator cab structural sound and air sound hybrid active control system provided by the invention can automatically identify the structural sound frequency of a cab panel. During the working process of the excavator, the vibration signal and the sound pressure signal are collected through the sensor, the controller generates corresponding output according to the input vibration signal and the input sound pressure signal and applies the output to the actuator and the loudspeaker to respectively offset structural sound generated by vibration of the cab panel and air sound transmitted into the cab by the engine, and therefore mixed active control of the structural sound and the air sound of the cab of the excavator is achieved. Compared with the prior art, the mixed active control system of the structural sound and the air sound of the cab of the excavator, provided by the invention, does not need to change the original structure of the excavator, so that the optimization period and the optimization cost are greatly reduced; meanwhile, the system has the advantages of easiness in implementation, good noise control effect, low cost and the like, and is very suitable for application of engineering machinery such as an excavator and the like.

Drawings

FIG. 1 is a schematic diagram of a structural sound and air sound hybrid active control system of an excavator cab.

FIG. 2 is a block diagram of a system identification and active control system for structural acoustic control according to the present invention.

FIG. 3 is a block diagram of the system identification and active control system for aero-acoustic control according to the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1, in the preferred embodiment, the excavator cab structure sound and air sound hybrid active control system comprises a vibration sensor, a sound pressure sensor, an FIR low-pass filter, a controller, a power amplifier, an actuator and a loudspeaker.

The excavator cab structure sound and air sound mixed active control system has the working process that:

(1) mounting a vibration sensor and an actuator at the position of an anti-node of a panel modal shape; the sound pressure sensor is installed at the headrest of the driver seat.

(2) The engine of the excavator is turned off, and the cab is not affected by external vibration excitation and noise interference. The controller performs system identification of the structural sound active control module, and a structural sound control and system identification schematic block diagram is shown in fig. 2. White noise signal v with 1024Hz output bandwidth of controller_aActing on the actuator via the amplifier, the actuator excites the panel of the cab of the excavator, causing the panel to generate a vibration signal v_s；

(3) The sensor collects panel vibration signals, and the panel vibration signals are input into the controller after passing through the FIR filter (at the moment, the cut-off frequency of the FIR filter is set to be 1024 Hz). Controller for outputting white noise signal v_aAnd an input vibration signal v_sPerforming a fast Fourier transform and calculating v_s/v_aAnd outputting a curve by using the calculation result, wherein the frequency f corresponding to the first peak value of the curve is the first-order structural sound frequency.

(4) Keeping the excavator engine off. The controller stops outputting the white noise control signal to the actuator. The controller performs system identification of the aero-acoustic active control module, and a schematic block diagram of the aero-acoustic control and system identification is shown in fig. 3. The controller outputs white noise with bandwidth of 1024Hz, the white noise is acted on the loudspeaker through the amplifier, and the noise generated by the loudspeaker is collected by the sound pressure sensor and is input into the controller. The controller automatically calculates the impulse response function h from the loudspeaker to the sound pressure sensor according to the output white noise signal and the input noise signal_s，h_sThe time delay compensation device can be used as a time delay compensation device for enabling the loudspeaker to emit cancellation noise to be transmitted to the sound pressure sensor under the control mode of the controller.

(5) The excavator engine starts working, the vibration is transmitted to the cab panel, and the panel vibration signal v_sThe sensor collects the signals, the signals pass through a filter (the cut-off frequency setting value of the filter is larger than f at the moment) and are used as the input of the controller, and the transfer function of a structural sound control module in the controller is as follows:where g is the amplification factor and ζ is the damping ratio. The controller automatically calculates and outputs a structural sound control signal according to the target frequency f, the structural sound control signal acts on the actuator through the power amplifier, the actuator generates reverse vibration to inhibit the vibration of the driving panel from radiating noise, and therefore the control of the structural sound of the cab of the excavator is achieved; the noise of the engine is transmitted into the cab, the noise signal is collected by the microphone and input into the controller, the control receives the crank angle signal of the engine at the same time, so as to obtain the rotating speed n of the engine and further obtain the frequency f of the noise of the controlled engine₀，f₀N in relation to：Where i is the number of engine cylinders. The controller is according to the target frequency f₀The control signal of the air sound is automatically calculated and output, the control signal acts on a loudspeaker through a power amplifier to send out offset noise, and engine noise at the position where a microphone is located is offset, so that the control of the air sound of the cab of the excavator is realized.

The above description is only for the preferred embodiment of the present invention and is not intended to limit the scope of the present invention, and all equivalent structural changes made by using the contents of the present specification and the drawings, or any other related technical fields, are intended to be covered by the scope of the present invention.