Noise reduction system for work machine and noise reduction method for work machine

Abstract

To provide a noise reduction system of a working machine and a noise reduction method of the working machine capable of performing optimum silencing for an operator according to various situations.SOLUTION: The error microphone 22 detects noise inside the cab 5. The operation information sensor 60 detects operation information of the wheel loader 100. The speaker 21 reduces the noise detected by the error microphone 22. The controller 50A determines the state of the wheel-loader 100 based on the operation information detected by the operation information sensor 60, and controls the speaker 21 to reduce the noise inside the cab 5 based on the state of the wheel-loader 100.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a noise reduction system for a work machine and a noise reduction method for a work machine. [Background technology]

[0002] A technique for reducing noise inside the cab of a construction machine is disclosed, for example, in Japanese Patent Laid-Open No. 2001-173018 (Patent Document 1). Patent Document 1 discloses that components in a predetermined frequency band are extracted from noise inside the cab detected by a microphone, and the extracted components are inverted in phase and radiated into the cab by a speaker. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-173018 Summary of the Invention [Problem to be solved by the invention]

[0004] The noise level inside the cab changes depending on various factors, so operators need to find the optimum noise reduction solution for each situation.

[0005] An object of the present disclosure is to provide a noise reduction system for a work machine and a noise reduction method for a work machine that enable an operator to optimally muffle noise depending on various situations. [Means for solving the problem]

[0006] One noise reduction system for a work machine according to the present disclosure includes a cab, a noise detection device, a sensor, a noise reduction device, and a controller. The noise detection device detects noise inside the cab. The sensor detects operation information of the work machine. The noise reduction device reduces the noise detected by the noise detection device. The controller determines the state of the work machine based on the operation information detected by the sensor, and controls the noise reduction device to reduce the noise inside the cab based on the state of the work machine.

[0007] Another noise reduction system for a work machine in the present disclosure includes a noise detection device, an imaging device, a noise reduction device, and a controller. The noise detection device detects noise. The imaging device images an operator of the work machine. The noise reduction device reduces the noise detected by the noise detection device. The controller calculates the position of the operator's ears based on an image of the operator captured by the imaging device, and controls the noise reduction device to reduce noise at the calculated position of the operator's ears.

[0008] One noise reduction method for a work machine disclosed herein is a noise reduction method for a work machine having a cab, a noise detection device that detects noise inside the cab, and a noise reduction device that reduces the noise detected by the noise detection device, and includes the following steps.

[0009] The state of the work machine is determined based on the operational information of the work machine, and the noise reduction device is controlled based on the state of the work machine so as to reduce noise inside the cab.

[0010] Another noise reduction method for a work machine in the present disclosure is a noise reduction method for a work machine that has a noise detection device that detects noise, an imaging device that images an operator, and a noise reduction device that reduces the noise detected by the noise detection device, and includes the following steps.

[0011] The position of the operator's ears is calculated based on the image of the operator captured by the imaging device, and the noise reduction device is controlled to reduce noise at the calculated position of the operator's ears. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to realize a noise reduction system for a work machine and a noise reduction method for a work machine that can provide optimal noise reduction to an operator depending on various situations. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating a configuration of a wheel loader according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing the inside of the driver's cab in FIG. [Figure 3] 1 is a diagram for explaining the principle of canceling noise inside the cab. FIG. [Figure 4] 1 is a functional block diagram of a noise reduction system according to one embodiment of the present disclosure. [Figure 5] FIG. 1 is a flow diagram illustrating a noise reduction method according to one embodiment of the present disclosure. [Figure 6] FIG. 10 is a diagram for explaining a method for determining a transfer function at the position of an operator's ear. [Figure 7] FIG. 10 is a functional block diagram of a noise reduction system according to another embodiment of the present disclosure. [Figure 8] FIG. 10 is a flow diagram illustrating a noise reduction method according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0015] In the specification and drawings, the same or corresponding components are denoted by the same reference numerals, and redundant descriptions are not repeated. Furthermore, in the drawings, configurations may be omitted or simplified for the sake of convenience. Furthermore, at least a portion of one embodiment and another embodiment may be combined with each other in any desired manner.

[0016] <Wheel loader configuration>

[0017] The configuration of a wheel loader 100 will be described as an example of a work machine in this embodiment using Figures 1 and 2. The work machine in this disclosure is not limited to the wheel loader 100, but may be other work machines such as an excavator, bulldozer, or motor grader. While a work machine having a driver's cab is preferred, this disclosure may also be applied to a work machine that does not have a driver's cab and in which the driver's seat is exposed to the outside. While an electrically driven work machine is preferred, this disclosure may also be applied to work machines with other drive systems, such as an engine drive system.

[0018] Fig. 1 is a side view showing the configuration of a wheel loader according to an embodiment of the present disclosure, Fig. 2 is a view showing the inside of the operator's cab in Fig. 1.

[0019] As shown in FIG. 1, the wheel loader 100 in this embodiment has a vehicle body 1. The vehicle body 1 has a traveling body 2 and a work implement 3. The work implement 3 is disposed on the traveling body 2. The traveling body 2 has a body frame 10, a pair of front tires 4, a driver's cab 5, a pair of rear tires 7, and a steering cylinder 9. The wheel loader 100 uses the work implement 3 to perform work such as loading earth and sand.

[0020] The body frame 10 is of a so-called articulated (rotating) type and includes a front frame 11, a rear frame 12, and a connecting shaft 13. The connecting shaft 13 connects the front frame 11 and the rear frame 12 so that they can rotate relative to each other. A pair of front tires 4 are attached to the left and right of the front frame 11. Furthermore, a pair of rear tires 7 are attached to the left and right of the rear frame 12.

[0021] The work implement 3 has a boom 14, a bucket 15, a lift cylinder 16, a bucket cylinder 17, and a bell crank 18. The boom 14 is attached to the front frame 11. The bucket 15 is attached to the tip of the boom 14.

[0022] One end of the lift cylinder 16 is attached to the front frame 11, and the other end of the lift cylinder 16 is attached to the boom 14. The extension and contraction of the lift cylinder 16 causes the boom 14 to rotate up and down. One end of the bucket cylinder 17 is attached to the front frame 11, and the other end of the bucket cylinder 17 is attached to the bucket 15 via a bell crank 18. The extension and contraction of the bucket cylinder 17 causes the bucket 15 to rotate up and down.

[0023] The wheel loader 100 is, for example, an electrically driven work machine. The electrically driven wheel loader 100 has, for example, a battery 6a, an inverter 6b, an electric motor 6c, a hydraulic pump 6d, a main valve 6e, and an HST (Hydro Static Transmission) 6f.

[0024] The battery 6a has a plurality of battery modules. Each of the plurality of battery modules has a plurality of battery cells. The battery 6a is a power source and stores electrical energy obtained from an external power source. The battery 6a extracts the stored electrical energy as electromotive force. The battery 6a supplies power to the inverter 6b through electrical wiring.

[0025] The inverter 6b converts the direct current output from the battery 6a into alternating current with controlled frequency, etc. The inverter 6b supplies the converted alternating current to the electric motor 6c via electrical wiring.

[0026] The electric motor 6c is driven by AC power supplied from the inverter 6b. The rotation speed of the electric motor 6c is controlled by the frequency of the AC power supplied from the inverter 6b. The output shaft of the electric motor 6c is mechanically connected to the input shaft of the hydraulic pump 6d.

[0027] The hydraulic pump 6d is driven by the driving force of the electric motor 6c, and when the hydraulic pump 6d is driven, hydraulic oil is supplied from the hydraulic pump 6d to the main valve 6e.

[0028] The main valve 6e is a switching valve and is configured as an assembly of a number of control valves, pilot valves, etc. The main valve 6e supplies hydraulic oil pumped from a hydraulic oil tank by a hydraulic pump to each of the hydraulic actuators 9, 16, and 17.

[0029] The hydraulic actuators 9, 16, and 17 include a steering cylinder 9, a lift cylinder 16, and a bucket cylinder 17. The hydraulic actuators 9, 16, and 17 are actuated by the supply of hydraulic oil from the main valve 6e, which causes the work equipment 3 to operate and the front frame 11 and the rear frame 12 to rotate relative to each other.

[0030] The HST 6f is a hydraulic continuously variable transmission that allows for multiple speed changes, such as first, second, and third gears. The HST 6f mainly comprises a hydraulic pump, a hydraulic motor, and a hydraulic circuit. The hydraulic circuit connects the hydraulic pump and the hydraulic motor. The driving force generated by the electric motor 6c operates the hydraulic pump of the HST, causing hydraulic oil to be discharged from the hydraulic pump. The hydraulic oil discharged from the hydraulic pump is supplied to the hydraulic motor through the hydraulic circuit, driving the hydraulic motor. The driving force of the hydraulic motor is transmitted to the front tires 4 and rear tires 7 via a transfer case, axles, etc. This allows the wheel loader 100 to travel.

[0031] Although the above description is of a case where a hydraulic actuator is used, an electric actuator (for example, an electric cylinder) may be used instead of a hydraulic actuator. Also, the above description is of a case where an HST is used, but an electric motor for traveling may be used instead of an HST. By using an electric actuator, an electric motor for traveling, etc. as described above, the wheel loader 100 may be fully electric.

[0032] The operator's cab 5 is mounted on the rear frame 12. The operator's cab 5 has an internal space for an operator who operates the wheel loader 100. The internal space of the operator's cab 5 is separated from the outside.

[0033] As shown in Fig. 2, the cab 5 has an openable door 5a, for example, on the side. When the door 5a is opened, the interior space of the cab 5 is connected to the outside. This allows the operator to enter the interior space from outside the cab 5 and to exit from the interior space to the outside. When the door 5a is closed, the interior space of the cab 5 is isolated from the outside.

[0034] The cab 5 has an openable and closable window 5b. The window 5b may be provided in the door 5a, or may be provided in a location in the cab 5 other than the door 5a. When the window 5b is open, the interior space of the cab 5 is connected to the outside. When the window 5b is closed, the interior space of the cab 5 is isolated from the outside.

[0035] A driver's seat 5s is disposed inside the cab 5. The driver's seat 5s is for the operator to sit on. The driver's seat 5s has a seating portion 5sa, a backrest portion 5sb, and a headrest portion 5sc. The driver's seat 5s is disposed on the floor of the cab 5 via a seat suspension 24. The seat suspension 24 serves to absorb and dampen at least vertical vibrations of the driver's seat 5s.

[0036] Inside the operator's cab 5, a speaker 21, an error microphone 22, a camera 23, an accelerator pedal 25, a brake pedal 26, and a work equipment lever 27 are also arranged.

[0037] The error microphone 22 detects noise inside the cab 5. The error microphone 22 is positioned near the operator's ear. The error microphone 22 is attached to the headrest portion 5sc, for example. The error microphone 22 is attached to the front or side of the headrest portion 5sc. The error microphone 22 may be attached to the backrest portion 5sb, or may be attached to a location other than the driver's seat 5s. The error microphone 22 corresponds to an example of a noise detection device of the present disclosure. Furthermore, noise refers to sounds that are unnecessary or obstructive to the operator's purpose of operating the wheel loader 100.

[0038] The speaker 21 is intended to reduce noise inside the driver's cab 5. The speaker 21 is arranged, for example, behind the driver's seat 5s. The speaker 21 is arranged above the rear window 5br. The speaker 21 may be arranged, for example, at the driver's seat 5s or on the ceiling of the driver's cab 5. A plurality of (for example, two) speakers 21 may be arranged. The two speakers 21 are arranged, for example, on either side of the driver's seat 5s when viewed from the front looking rearward (front view). The speaker 21 corresponds to an example of a noise reduction device of the present disclosure.

[0039] The camera 23 captures an image of the operator. The camera 23 captures, for example, an image of the operator's head including the ears. The camera 23 is disposed in front of the operator seated in the driver's seat 5s. The camera 23 is disposed in the driver's cab 5 so as to capture, for example, an image from the front to the rear. However, the camera 23 may also be disposed in the driver's cab 5 so as to capture an image from the rear to the front, or may be disposed anywhere in the driver's cab 5 as long as it can capture an image of the position of the operator's ears. The camera 23 is attached, for example, to the front console, front pillar, etc. in the driver's cab 5. The camera 23 corresponds to an example of an imaging device of the present disclosure. Multiple cameras 23 may be provided as an imaging device.

[0040] The accelerator pedal 25 and the brake pedal 26 are each used to adjust acceleration and deceleration when the wheel loader 100 is traveling. The accelerator pedal 25 and the brake pedal 26 each receive operation from the operator. The accelerator pedal 25 and the brake pedal 26 are each located, for example, in front of the driver's seat 5s and the seat suspension 24, at the feet of the operator seated in the driver's seat 5s.

[0041] The work implement lever 27 is used to operate the work implement 3 of the wheel loader 100. The work implement lever 27 receives operations from the operator. The work implement lever 27 can be used to operate the lifting and lowering operation of the boom 14 and the dumping and tilting operation of the bucket 15.

[0042] The wheel loader 100 has an air conditioner 28. The air conditioner 28 conditions the air inside the cab 5. The air conditioner 28 controls the temperature, humidity, and the like inside the cab 5 by using, for example, a vapor compression refrigeration cycle. The air conditioner 28 has a compressor 28a, a condenser, an expansion valve, and an evaporator. The compressor 28a compresses the refrigerant. The air conditioner 28 may be located inside the cab 5 or outside the cab 5.

[0043] <Noise reduction system and noise reduction method for wheel loader 100>

[0044] Next, the noise reduction system and noise reduction method for the wheel loader 100 in this embodiment will be described with reference to FIGS.

[0045] (Principle of eliminating noise inside the driver's cab 5)

[0046] First, the principle of eliminating noise inside the cab 5 will be explained using FIG.

[0047] Figure 3 is a diagram for explaining the principle of canceling noise inside the cab. As shown in Figure 3, the noise of the wheel loader 100 is canceled by the control sound output from the speaker 21. The noise remaining after the noise has been canceled by the control sound is detected by the error microphone 22. An LMS (Least Mean Square Method) algorithm calculation unit 30 sequentially changes the adaptive filter coefficients w0, w1 of the adaptive filter so as to reduce the detected residual noise. This optimizes the adaptive filter coefficients w0, w1 so as to lower the level of the residual noise detected by the error microphone 22. Specifically, this is as follows.

[0048] First, a reference signal (cos(2πfnT), sin(2πfnT)) corresponding to the noise generated by the wheel loader 100 is generated. The generated reference signal is input to an adaptive filter. The adaptive filter multiplies the reference signal by adaptive filter coefficients w0 and w1, and adjusts the gain, phase, etc., to generate the following control signal y(n).

[0049] y(n)=w0cos(2πfnT)+w1sin(2πfnT)

[0050] The control signal y(n) is an inverted sound signal that has a waveform that is the opposite phase to and has the same amplitude as the waveform of the noise generated by the wheel loader 100. The control signal y(n) is input to the speaker 21. As a result, a control sound z(n) that has a waveform that is the opposite phase to and has the same amplitude as the noise is output from the speaker 21, and the periodic noise d(n) is canceled out by the control sound z(n).

[0051] The residual noise that remains without being canceled by the control sound is detected by the error microphone 22. The residual noise detected by the error microphone 22 is input as an error signal e(n) to the LMS algorithm calculation unit 30. A reference signal r(n) filtered with a transfer function / C in the estimated secondary path from the speaker 21 to the error microphone 22 is also input to the LMS algorithm calculation unit 30.

[0052] The LMS algorithm calculation unit 30 updates the adaptive filter coefficients w0 and w1 of the adaptive filter using an algorithm based on the error signal e(n) and the reference signal r(n) filtered with the transfer function / C. As a result, the noise is canceled out by the control sound obtained by filtering the reference signal with the updated adaptive filter coefficients w0 and w1. In this way, the adaptive filter coefficients w0 and w1 are optimized so that the level of the residual noise detected by the error microphone 22 is reduced.

[0053] When canceling each of the sounds of multiple frequencies contained in noise, the canceling is performed for each sound of each frequency according to the above principle. For example, when canceling multiple order components of noise, a control sound is generated for each order component according to the above principle, and the control sounds for each order component are synthesized to perform the canceling.

[0054] A work machine such as a wheel loader 100 has various operating states, and the noise generated varies depending on the operating state. For example, in an electrically driven wheel loader 100, certain sounds, such as the sound of the electric motor 6c and the sound of the hydraulic pump 6d, which have previously been buried in the engine noise and therefore not been noticed by the operator, become noticeable. Such sounds as the electric motor 6c and the hydraulic pump 6d have frequencies of, for example, 500 Hz or higher. For this reason, in an electrically driven wheel loader 100, it is preferable to muffle sounds with frequencies of 500 Hz or higher. While the present disclosure is applicable to sounds in all frequency bands, it is particularly preferable to apply it to sounds in bands other than low frequencies (for example, 500 Hz or higher). In this way, the present disclosure achieves optimal sound muffling for the operator in various operating states of the work machine.

[0055] Furthermore, the relative positional relationship between the position of the operator's ear and the error microphone 22 may change due to static or dynamic factors. Static factors include, for example, differences in the operator's physique and adjustment of the position of the driver's seat 5s. Dynamic factors include, for example, up and down vibration of the driver's seat 5s caused by the action of the seat suspension 24 while the wheel loader 100 is in operation. Even when the relative positional relationship between the position of the operator's ear and the error microphone 22 changes in this way, the present disclosure achieves optimal sound deadening for the operator.

[0056] (Regarding noise reduction in various operating states of the wheel loader 100)

[0057] Next, a noise reduction system and a noise reduction method that can provide optimal noise reduction for the operator in various operating states of the wheel loader 100, such as when the wheel loader 100 is electrically driven, will be described using FIGS.

[0058] Fig. 4 is a functional block diagram of an embodiment for eliminating noise in the cab. Fig. 5 is a flow diagram showing a noise reduction method according to an embodiment of the present disclosure. As shown in Fig. 4, a controller 50A according to this embodiment includes an operation information acquisition unit 501, a work machine state determination unit 502, a reference signal generation unit 503, a control signal generation unit 504, a speaker control unit 505, a memory 506, and a noise acquisition unit 507.

[0059] 4 and 5, the operation information acquisition unit 501 acquires a signal indicating operation information from the operation information sensor 60 (step S1). The operation information sensor 60 detects operation information of the wheel loader 100 (work machine). The operation information detected by the operation information sensor 60 is, for example, information on one or more items selected from the group consisting of the rotation speed of the electric motor 6c, the rotation speed of the hydraulic pump 6d, the rotation speed of the compressor 28a, the opening and closing of the door 5a, the opening and closing of the window 5b, the operation amount of the accelerator pedal 25, the operation amount of the brake pedal 26, the speed gear of the HST 6f, and the operation amount of the work equipment lever 27. The operation information may be any one of these pieces of information alone, or may be any combination of these pieces of information.

[0060] The work machine state determination unit 502 determines the state of the wheel loader 100 based on the operation information acquired from the operation information acquisition unit 501 (step S2). At this time, the work machine state determination unit 502 refers to a table that specifies the relationship between the operation information and the state of the wheel loader 100, which is stored in the memory 506, for example.

[0061] The reference signal generation unit 503 generates a reference signal based on the state of the wheel loader 100 acquired from the work machine state determination unit 502 (step S3). At this time, the reference signal generation unit 503 refers to a table stored in the memory 506, for example, that specifies the relationship between the state of the wheel loader 100 and the reference signal.

[0062] The error microphone 22 detects noise inside the driver's cab 5 (step S4). The noise acquisition unit 507 acquires the noise detected by the error microphone 22 as an error signal.

[0063] The control signal generating unit 504 predicts the virtual sound at the position of the operator's ear (step S5). Specifically, the control signal generating unit 504 determines the adaptive filter coefficients in the adaptive filter using an algorithm based on the error signal acquired from the noise acquiring unit 507 and the reference signal filtered by the transfer function in the estimated secondary path.

[0064] The control signal generator 504 multiplies the determined adaptive filter coefficient by the reference signal obtained from the reference signal generator 503 and synthesizes all order components to generate a control signal (step S6). The control signal is generated so as to become an inverted signal having a waveform in antiphase with the waveform of the noise at the position of the operator's ear.

[0065] Here, the estimated secondary path is the path from the speaker 21 to the position of the operator's ear. When the position of the operator's ear and the position of the error microphone 22 coincide, the estimated secondary path is the path from the speaker 21 to the position of the error microphone 22. Therefore, when the position of the error microphone 22 is set to the position of the operator's ear, the transfer function / C ( FIG. 3 ) of the secondary path from the speaker 21 to the error microphone 22 is used as the transfer function of the estimated secondary path. This transfer function / C is stored in advance in memory 506. Therefore, the control signal generation unit 504 refers to the transfer function / C stored in memory 506 when generating a control signal.

[0066] Furthermore, if the position of the operator's ear is different from the position of the error microphone 22, the transfer function of the secondary path from the speaker 21 to the operator's ear is used as the transfer function of the estimated secondary path. How to obtain the transfer function of the secondary path from the speaker 21 to the operator's ear will be described later.

[0067] The speaker control unit 505 controls the speaker 21 based on the control signal acquired from the control signal generation unit 504. Specifically, the speaker control unit 505 inputs the control signal to the speaker 21, thereby causing the speaker 21 to generate a control sound (step S7). The speaker 21 emits the control sound, which has a waveform in the opposite phase to the waveform of the noise, into the interior of the cab 5. The noise inside the cab 5 is cancelled out by the control sound output from the speaker 21, and is thereby silenced.

[0068] After this, the process from step S1 is repeated. In this repeated process, the adaptive filter coefficients of the adaptive filter are successively updated. This optimizes the adaptive filter coefficients so that the level of residual noise detected by the error microphone 22 is reduced.

[0069] The noise reduction method of this embodiment is carried out as described above. Steps S3 to S7 above correspond to an example of the step of controlling the noise reduction device 21 to reduce noise inside the cab 5 based on the state of the wheel loader 100 in this disclosure.

[0070] In the above-described noise reduction system and noise reduction method, the reference signal generator 503 generates reference signals having frequencies corresponding to the rotation speeds of the electric motor 6c, the hydraulic pump 6d, and the compressor 28a, for example. Alternatively, signals measured by sensors for the rotation speeds of the electric motor 6c, the hydraulic pump 6d, the compressor 28a, etc. may be directly used as reference signals.

[0071] Furthermore, reference signal generator 503 generates a reference signal by switching the transfer function depending on whether door 5a is open or closed, for example. That is, control signal generator 504 generates a reference signal by switching the transfer function depending on whether door 5a is open or closed. Similarly, reference signal generator 503 generates a reference signal by switching the transfer function depending on whether window 5b is open or closed.

[0072] In addition, the reference signal generating unit 503 predicts changes in the rotation speed of the electric motor 6c, the rotation speed of the hydraulic pump 6d, etc. based on, for example, the amount of operation of the accelerator pedal 25, the amount of operation of the brake pedal 26, the speed stage of the HST 6f, and the amount of operation of the work equipment lever 27, and generates a reference signal.

[0073] (Sound suppression that follows the position of the operator's ears)

[0074] Next, a noise reduction system and a noise reduction method that can achieve optimal noise reduction for the operator even when the relative positional relationship between the position of the operator's ear and the error microphone 22 changes will be described with reference to FIGS.

[0075] Fig. 6 is a diagram for explaining a method for determining a transfer function at the position of the operator's ear. Fig. 7 is a functional block diagram of a noise reduction system according to another embodiment of the present disclosure. Fig. 8 is a flow chart showing a noise reduction method according to another embodiment of the present disclosure.

[0076] 2 and 6, the relative positional relationship between the position P0 of the error microphone 22 and the position of the operator's ear may change due to the static or dynamic factors described above. In such a case, in this embodiment, the transfer function G y is derived, and this transfer function G y The sound pressure at the position of the operator's ear is calculated based on the above equation, and sound is muted at the position of the operator's ear. This will be explained below.

[0077] In this embodiment, the position P0 of the error microphone 22 and a plurality of other points (for example, points P1 to P 15 ) the transfer functions G1 to G 15 In order to simplify the diagram, a map showing the transfer functions G1 to G6 and G8 to G 10In preparing this map, the first microphone 22 and the points P1 to P2 are previously determined. 15 The error microphone 22 and the second microphone located at the coordinates of the plurality of points P1 to P 15 Transfer functions G1 to G 15 This map is stored in, for example, the memory 519 (FIG. 7) of the controller 50B. In this map, the transfer functions G1 to G 15 Each of these points P1 to P 15 is associated with.

[0078] Multiple points P1~P 15 are virtual points arranged in a matrix in space, and may be set as intersections (lattice points) of a virtual grid in space. 15 The intervals between adjacent points in the column direction (for example, points P0, P1, P2, and P3) may all be equal, and the intervals between adjacent points in the row direction (for example, points P0, P4, P8, and P 12 ) may be spaced equally, or the spacing between adjacent points may be different.

[0079] Here, the sound pressure SP at any point away from the error microphone 22 can be calculated by SP=G×SP0, where G is the transfer function of the path between the point and the error microphone 22. SP0 is the sound pressure at the location of the error microphone 22.

[0080] In this embodiment, the positions of the operator's ears are calculated by the controller 50B based on an image of the operator captured by the camera 23 (for example, two cameras 23). The controller 50B calculates the positions of the operator's ears based on a plurality of points P1 to P 15 At this time, the controller 50B selects a point that is closest to the position of the operator's ear from among the points P1 to P2. 15 It is determined whether it matches any of the following.

[0081] The operator's ears are positioned at multiple points P1 to P 15 If the position of the operator's ear coincides with any of the points G and SP0, the sound pressure SP at the coincident point (the point where the ear is located) is calculated as SP = G × SP0 as described above. For example, if the position of the operator's ear coincides with point P 10 If the error microphone 22 position P0 and the operator's ear position are matched, the transfer function of the path between them is G 10 and point P 10 Sound pressure SP 10 SP 10 =G 10 ×SP0.

[0082] In addition, the position of the operator's ears is determined by multiple points P1 to P 15 If it is different from any of the points P1 to P 15 Among these, four points (e.g., points P5, P6, P9, P 10 ) corresponding to each of the transfer functions (for example, G5, G6, G9, G 10 ) the transfer function G in the path between the ear position and the error microphone 22 y is predicted by interpolation. As a result, the transfer function in the path between the position P0 of the error microphone 22 and the position of the operator's ear is G y and the sound pressure SP at the ear position is y SP y =G y ×SP0.

[0083] The controller 50B outputs a control signal to the speaker 21 to emit a controlled sound of the calculated sound pressure. As a result, the speaker 21 emits a controlled sound of sound pressure that cancels out the noise at the position of the operator's ear, and this controlled sound cancels out the noise at the position of the operator's ear. In this way, even if the relative positional relationship of the position of the operator's ear with respect to the position P0 of the error microphone 22 changes, it is possible to muffle the sound by following the position of the operator's ear.

[0084] Note that the multiple points P1 to P 15The points P1 to P2 may be arranged in a plane extending up and down and left and right, or may be arranged in a plane extending front and back and left and right, or may be arranged in a plane extending up and down and front and back, or may be arranged in any other plane. 15 The points P1 to P2 may be arranged in a plane or in a three-dimensional manner. 15 may be placed at the lattice points of a cubic lattice, for example.

[0085] As shown in FIG. 7, the controller 50B in this embodiment has an image acquisition unit 511, a position calculation unit 512, an estimated secondary path acquisition unit 513, a sound estimation unit 514, a noise acquisition unit 515, a reference signal generation unit 516, a control signal generation unit 517, a speaker control unit 518, and a memory 519.

[0086] 7 and 8, the camera 23 captures an image of the operator operating the wheel loader 100 inside the cab 5. The camera 23 captures an image of the operator's head, including the ears, for example.

[0087] The image acquisition unit 511 acquires an image of the operator captured by the camera 23. The position calculation unit 512 calculates the position of the operator's ears based on the image of the operator acquired from the image acquisition unit 511 (step S101).

[0088] The estimated secondary path acquisition unit 513 refers to the map stored in the memory 519 and acquires a transfer function in the estimated secondary path corresponding to the ear position acquired from the position calculation unit 512 (step S102). The transfer function in the estimated secondary path corresponding to the ear position is acquired by the method described in FIG. 6. The map includes the position P0 of the error microphone 22 and a plurality of points P1 to P 15 The transfer functions G1 to G2 on the paths between each of the positions 15 This is a map showing the above.

[0089] Meanwhile, error microphone 22 detects noise (step S103). Noise acquisition unit 515 acquires the noise detected by error microphone 22 as an error signal.

[0090] The sound estimation unit 514 estimates the virtual sound at the position of the ear (step S104). Specifically, the sound estimation unit 514 filters the reference signal generated by the reference signal generation unit 516 with the transfer function of the estimated secondary path acquired from the estimated secondary path acquisition unit 513. The sound estimation unit 514 determines adaptive filter coefficients of the adaptive filter using an algorithm based on the LMS method, based on the reference signal filtered with the transfer function of the estimated secondary path and the error signal acquired from the noise acquisition unit 515.

[0091] The control signal generation unit 517 acquires the adaptive filter coefficient from the sound estimation unit 514 and acquires the reference signal from the reference signal generation unit 516 (step S105). The control signal generation unit 517 generates a control signal by multiplying the adaptive filter coefficient acquired from the sound estimation unit 514 by the reference signal acquired from the reference signal generation unit 516 (step S106). The control signal is generated so as to have a waveform that is in antiphase with the waveform of the noise at the position of the ear.

[0092] The speaker control unit 518 controls the speaker 21 based on the control signal acquired from the control signal generation unit 517. Specifically, the speaker control unit 518 controls the speaker 21 to generate a control sound by inputting the control signal to the speaker 21 (step S107). The speaker 21 emits the control sound having a waveform that is in the opposite phase to the waveform of the noise at the position of the ear. The noise at the position of the ear is canceled out by the control sound output from the speaker 21.

[0093] After this, the processes from step S101 onwards are repeated. During this repeated process, the adaptive filter coefficients of the adaptive filter are successively updated to follow changes in the position of the ear. This makes it possible to mute sound in accordance with the position of the ear, even if the position of the ear changes relative to the error microphone 22.

[0094] (others)

[0095] 4 and 7, the controllers 50A and 50B include a processor, a main memory, and a storage. The processor is, for example, a central processing unit (CPU). The main memory includes, for example, a nonvolatile memory such as a read-only memory (ROM) and a volatile memory such as a random access memory (RAM).

[0096] Each of the controllers 50A and 50B reads a program stored in a storage device, loads it into a main memory, and executes a predetermined process in accordance with the program. The program may also be distributed to each of the controllers 50A and 50B via a network.

[0097] Each of the controllers 50A, 50B may be mounted on the wheel loader 100, or may be located remotely outside the wheel loader 100. When each of the controllers 50A, 50B is located remotely outside the wheel loader 100, each of the controllers 50A, 50B may be wirelessly connected to the operation information sensor 60, speaker 21, error microphone 22, camera 23, etc. Each of the controllers 50A, 50B may be stored in a server located remotely from the wheel loader 100.

[0098] <Effects>

[0099] Next, the effects of this embodiment will be described.

[0100] In one embodiment, as shown in Fig. 4, the controller 50A controls the speaker 21 to reduce noise inside the cab 5 based on the state of the wheel loader 100. This makes it possible to appropriately reduce various noises that occur depending on the state of the wheel loader 100. This allows the operator to achieve optimal sound damping depending on various situations. The states of the wheel loader 100 include traveling operations such as starting, accelerating, and climbing, and work equipment operations such as excavation and loading. In these operating conditions, when the load on the motor, pump, etc. increases, noise (for example, 500 Hz or higher) that is unpleasant to the operator is likely to occur. For this reason, the effects of the present disclosure are particularly likely to be achieved in these operating conditions.

[0101] 4, in one embodiment, the controller 50A generates a sound wave of an opposite phase to the waveform of the noise detected by the error microphone 22 and controls the speaker 21 to emit the sound wave of the opposite phase. As a result, the noise is canceled out by the sound of the opposite phase emitted from the speaker 21.

[0102] In one embodiment, as shown in Figure 1, a work machine such as a wheel loader 100 is an electrically driven work machine. In an electrically driven work machine 100, certain sounds such as the sound of the electric motor 6c and the sound of the hydraulic pump 6d that are drowned out by the engine sound of an engine-driven work machine and go unnoticed by the operator become more noticeable, but in this embodiment, noise is reduced based on the state of the work machine 100. As a result, certain sounds such as the sound of the electric motor 6c and the sound of the hydraulic pump 6d can be effectively reduced.

[0103] 4, in one embodiment, the controller 50A controls the speaker 21 to reduce noise of frequencies equal to or greater than 500 Hz inside the cab 5. Since specific sounds of frequencies equal to or greater than 500 Hz are reduced in this way, specific sounds such as the sound of the electric motor 6c and the sound of the hydraulic pump 6d in the electrically driven work machine 100 can be effectively reduced.

[0104] 4, in one embodiment, the operation information of the work machine 100 detected by the operation information sensor 60 is information related to one or more selected from the group consisting of the rotation speed of the electric motor 6c, the rotation speed of the hydraulic pump 6d, the rotation speed of the compressor 28a, the opening and closing of the door 5a, the opening and closing of the window 5b, the operation amount of the accelerator pedal 25, the operation amount of the brake pedal 26, the speed stage of the HST 6f, and the operation amount of the work implement lever 27. This enables the operator to achieve optimal sound deadening in accordance with various situations.

[0105] 6 and 7, in another embodiment, the controller 50B calculates the position of the operator's ear based on an image of the operator captured by the camera 23, and controls the speaker 21 to reduce noise at the calculated position of the operator's ear. This makes it possible to reduce noise at the position of the operator's ear by following the movement of the operator's ear, even if the position of the operator's ear changes relative to the error microphone 22.

[0106] In yet another embodiment, as shown in FIGS. 6 and 7, the controller 50B calculates the transfer function G in the path between the calculated operator's ear position and the error microphone 22. y and calculate the sound pressure at the operator's ear position using its transfer function G y This effectively reduces noise at ear level.

[0107] In another embodiment, as shown in FIGS. 6 and 7, the controller 50B determines the position P0 of the error microphone 22 and a plurality of points P1 to P 15 The transfer functions G1 to G2 on the paths between each of the positions 15 , the transfer function G in the path between the calculated operator's ear position and the error microphone 22 is calculated by referring to the map showing y This effectively reduces noise at the ear position.

[0108] In another embodiment, as shown in FIGS. 6 and 7, the controller 50B determines whether the calculated positions of the operator's ears are located at a plurality of points P1 to P 15 If it is different from any of the points P1 to P 15 From the transfer functions corresponding to each of the four points surrounding the calculated position of the operator's ear, the transfer function G y This predicts the transfer function G y can be derived by interpolating the transfer functions of the four coordinates.

[0109] <Additional Notes>

[0110] The above description includes the following additional features.

[0111] (Appendix 1) A noise reduction system for a work machine, comprising: The driver's cab and a noise detection device for detecting noise inside the cab; a sensor for detecting operational information of the work machine; a noise reduction device that reduces the noise detected by the noise detection device; a controller that determines a state of the work machine based on the operation information detected by the sensor, and controls the noise reduction device to reduce noise inside the cab based on the state of the work machine.

[0112] (Appendix 2) 2. A noise reduction system for a work machine as described in Appendix 1, wherein the controller generates a sound wave of an opposite phase to a waveform of the noise detected by the noise detection device and controls the noise reduction device to emit the sound wave of the opposite phase.

[0113] (Appendix 3) 3. The noise reduction system for a work machine according to claim 1 or 2, wherein the work machine is an electrically driven work machine.

[0114] (Appendix 4) 4. A noise reduction system for a work machine according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the controller controls the noise reduction device to reduce noise having a frequency of 500 Hz or higher inside the cab.

[0115] (Appendix 5) 5. A noise reduction system for a work machine according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the operation information of the work machine detected by the sensor is information relating to one or more selected from the group consisting of the rotation speed of an electric motor, the rotation speed of a hydraulic pump, the rotation speed of an air conditioner compressor, the opening and closing of a door of the driver's cab, the opening and closing of a window of the driver's cab, the amount of operation of an accelerator pedal, the amount of operation of a brake pedal, a gear ratio, and the amount of operation of a work equipment lever.

[0116] (Appendix 6) A noise reduction system for a work machine, comprising: a noise detection device for detecting noise; an imaging device that images an operator of the work machine; a noise reduction device that reduces the noise detected by the noise detection device; a controller that calculates the position of the operator's ears based on an image of the operator captured by the imaging device, and controls the noise reduction device to reduce noise at the calculated position of the operator's ears.

[0117] (Appendix 7) 7. A noise reduction system for a work machine as described in Appendix 6, wherein the controller derives a transfer function for a path between the calculated position of the operator's ear and the noise detection device, and calculates the sound pressure at the position of the operator's ear from the transfer function.

[0118] (Appendix 8) 8. A noise reduction system for a work machine as described in Appendix 7, wherein the controller derives a transfer function for a path between the calculated position of the operator's ear and the noise detection device by referring to a map indicating a transfer function for a path between the position of the noise detection device and the position of each of a plurality of points.

[0119] (Appendix 9) Appendix 9. A noise reduction system for a work machine as described in Appendix 8, wherein, when the calculated position of the operator's ear is different from any of the plurality of coordinates, the controller predicts a transfer function of a path between the calculated position of the operator's ear and the noise detection device from transfer functions corresponding to four coordinates among the plurality of coordinates that surround the calculated position of the operator's ear.

[0120] (Appendix 10) A noise reduction method for a work machine having a cab, a noise detection device that detects noise inside the cab, and a noise reduction device that reduces noise detected by the noise detection device, comprising: determining a state of the work machine based on operation information of the work machine; and controlling the noise reduction device to reduce noise inside the cab based on the state of the work machine.

[0121] (Appendix 11) the step of controlling the noise reduction device to reduce noise inside the cab includes: generating a sound wave having an opposite phase to the waveform of the noise detected by the noise detection device; and controlling the noise reduction device to emit the generated sound waves in opposite phase.

[0122] (Appendix 12) 12. The noise reduction method for a work machine according to claim 10 or 11, wherein in the step of controlling the noise reduction device to reduce noise inside the cab, the noise reduction device is controlled to reduce noise inside the cab having a frequency of 500 Hz or higher.

[0123] (Appendix 13) 13. The noise reduction method for a work machine according to any one of Supplementary Note 10 to Supplementary Note 12, wherein the operation information of the work machine is information relating to one or more selected from the group consisting of the rotation speed of an electric motor, the rotation speed of a hydraulic pump, the rotation speed of an air conditioner compressor, the opening and closing of a door of the driver's cab, the opening and closing of a window of the driver's cab, the amount of operation of an accelerator pedal, the amount of operation of a brake pedal, a gear ratio, and the amount of operation of a work equipment lever.

[0124] (Appendix 14) A noise reduction method for a work machine having a noise detection device that detects noise, an imaging device that images an operator, and a noise reduction device that reduces noise detected by the noise detection device, comprising: calculating the position of the operator's ears based on the image of the operator captured by the imaging device; and controlling the noise reduction device to reduce the noise at the calculated position of the operator's ear.

[0125] (Appendix 15) 15. The noise reduction method for a work machine as described in Appendix 14, wherein the step of controlling the noise reduction device to reduce noise includes the step of deriving a transfer function of a path between the calculated position of the operator's ear and the noise detection device, and calculating the sound pressure at the calculated position of the operator's ear from the transfer function.

[0126] (Appendix 16) A noise reduction method for a work machine as described in Appendix 15, wherein the step of calculating from the transfer function includes a step of deriving a transfer function for a path between the calculated position of the operator's ear and the noise detection device by referring to a map indicating transfer functions for paths between the position of the noise detection device and the positions of each of a plurality of points.

[0127] (Appendix 17) Appendix 17. The noise reduction method for a work machine described in Appendix 16, wherein, in the step of calculating from the transfer function, if the calculated operator's ear position is different from any of the plurality of points, a transfer function for a path between the calculated operator's ear position and the noise detection device is predicted from transfer functions corresponding to four points among the plurality of points that surround the calculated operator's ear position.

[0128] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0129] 1 vehicle body, 2 running body, 3 work equipment, 4 front tire, 5 driver's cab, 5a door, 5b window, 5br rear window, 5s driver's seat, 5sa seating area, 5sb backrest, 5sc headrest, 6a battery, 6b inverter, 6c electric motor, 6d hydraulic pump, 6e main valve, 7 rear tire, 9 steering cylinder, 10 vehicle frame, 11 front frame, 12 rear frame, 13 connecting shaft, 14 boom, 15 bucket, 16 lift cylinder, 17 bucket cylinder, 18 bell crank, 21 speaker, 22 error microphone, 23 camera, 24 seat suspension, 25 accelerator pedal, 26 brake pedal, 27 work equipment lever, 28 air conditioner, 28a compressor, 30 algorithm calculation unit, 50A, 50B controller, 60 Operation information sensor, 100 wheel loader, 501 operation information acquisition unit, 502 work machine state determination unit, 503, 516 reference signal generation unit, 504, 517 control signal generation unit, 505, 518 speaker control unit, 506, 519 memory, 507, 515 noise acquisition unit, 511 image acquisition unit, 512 position calculation unit, 513 estimated secondary path acquisition unit, 514 sound estimation unit.

Claims

1. A noise reduction system for a work machine, comprising: The driver's cab and a noise detection device for detecting noise inside the cab; a sensor for detecting operational information of the work machine; a noise reduction device that reduces the noise detected by the noise detection device; a controller that determines a state of the work machine based on the operation information detected by the sensor, and controls the noise reduction device to reduce noise inside the cab based on the state of the work machine.

2. 2. The noise reduction system for a work machine according to claim 1, wherein the controller generates a sound wave having an opposite phase to a waveform of the noise detected by the noise detection device and controls the noise reduction device to emit the sound wave having the opposite phase.

3. 2. The noise reduction system for a work machine according to claim 1, wherein the work machine is an electrically driven work machine.

4. The noise reduction system for a work machine according to claim 1 , wherein the controller controls the noise reduction device to reduce noise at frequencies equal to or greater than 500 Hz inside the cab.

5. 2. A noise reduction system for a work machine according to claim 1, wherein the operation information of the work machine detected by the sensor is information related to one or more selected from the group consisting of an electric motor rotation speed, a hydraulic pump rotation speed, an air conditioner compressor rotation speed, opening and closing of a door of the operator's cab, opening and closing of a window of the operator's cab, an accelerator pedal operation amount, a brake pedal operation amount, a gear ratio, and an operation amount of a work implement lever.

6. A noise reduction system for a work machine, comprising: a noise detection device for detecting noise; an imaging device that images an operator of the work machine; a noise reduction device that reduces the noise detected by the noise detection device; a controller that calculates the position of the operator's ears based on an image of the operator captured by the imaging device, and controls the noise reduction device to reduce noise at the calculated position of the operator's ears.

7. 7. The noise reduction system for a work machine according to claim 6, wherein the controller derives a transfer function of a path between the calculated position of the operator's ear and the noise detection device, and calculates the sound pressure at the position of the operator's ear from the transfer function.

8. 8. The noise reduction system for a work machine according to claim 7, wherein the controller derives the transfer function of the path between the calculated position of the operator's ear and the noise detection device by referring to a map indicating a transfer function of the path between the position of the noise detection device and the position of each of a plurality of points.

9. 9. The noise reduction system for a work machine according to claim 8, wherein, when the calculated position of the operator's ear is different from any of the plurality of points, the controller predicts a transfer function of a path between the calculated position of the operator's ear and the noise detection device from transfer functions corresponding to four points among the plurality of points that surround the calculated position of the operator's ear.

10. A noise reduction method for a work machine having a cab, a noise detection device that detects noise inside the cab, and a noise reduction device that reduces noise detected by the noise detection device, comprising: determining a state of the work machine based on operation information of the work machine; and controlling the noise reduction device to reduce noise inside the cab based on the state of the work machine.

11. the step of controlling the noise reduction device to reduce noise inside the cab includes: generating a sound wave having an opposite phase to the waveform of the noise detected by the noise detection device; and controlling the noise reduction device to emit the generated sound waves in opposite phase.

12. 12. The noise reduction method for a work machine according to claim 11, wherein in the step of controlling the noise reduction device to reduce noise inside the cab, the noise reduction device is controlled to reduce noise inside the cab at a frequency of 500 Hz or higher.

13. 11. The noise reduction method for a work machine according to claim 10, wherein the operation information of the work machine is information related to one or more selected from the group consisting of an electric motor rotation speed, a hydraulic pump rotation speed, an air conditioner compressor rotation speed, opening and closing of a door of the operator's cab, opening and closing of a window of the operator's cab, an accelerator pedal operation amount, a brake pedal operation amount, a gear position, and an operation amount of a work equipment lever.

14. A noise reduction method for a work machine having a noise detection device that detects noise, an imaging device that images an operator, and a noise reduction device that reduces noise detected by the noise detection device, comprising: calculating the position of the operator's ears based on the image of the operator captured by the imaging device; and controlling the noise reduction device to reduce the noise at the calculated position of the operator's ear.

15. 15. The method for reducing noise in a work machine according to claim 14, wherein the step of controlling the noise reduction device to reduce noise includes the step of deriving a transfer function of a path between the calculated position of the operator's ear and the noise detection device, and calculating the sound pressure at the calculated position of the operator's ear from the transfer function.

16. 16. The noise reduction method for a work machine according to claim 15, wherein the step of calculating from the transfer function includes a step of deriving a transfer function for a path between the calculated position of the operator's ear and the noise detection device by referring to a map indicating transfer functions for paths between the position of the noise detection device and the positions of each of a plurality of points.

17. 17. The noise reduction method for a work machine according to claim 16, wherein, in the step of calculating from the transfer function, if the calculated position of the operator's ear is different from any of the plurality of points, a transfer function for a path between the calculated position of the operator's ear and the noise detection device is predicted from transfer functions corresponding to four points among the plurality of points that surround the calculated position of the operator's ear.

Images