Vibration reduction device

Abstract

To improve technology that reduces vibrations perceived by the occupants of a moving vehicle due to the vehicle's vibrations. [Solution] A vibration reduction device for reducing vibrations perceived by the occupants of a moving vehicle comprises a vibration generating device and a control device for controlling the drive of the vibration generating device. The control device detects the direction, amplitude, and phase of the occupant's head movement, sets the sound pressure of the air vibration generated by the vibration generating device based on the direction and amplitude of the movement, sets the phase of the air vibration based on the phase, and controls the drive of the vibration generating device to generate air vibrations based on the set sound pressure and phase.

Description

Technical Field

[0001] The present disclosure relates to a vibration reduction device.

Background Art

[0002] Conventionally, it has been known to actively control noise by generating a sound that cancels out the noise in the vehicle interior.

[0003] For example, Patent Document 1 discloses that when a buffeting event occurs in the vehicle interior, an actuator vibrates the window panel of the vehicle interior to generate a cancellation sound wave that cancels out the buffeting event.

[0004] Further, Patent Document 2 discloses reducing a second noise generated in a vehicle based on a first noise generated from a noise source such as an engine of the vehicle by a third noise as a cancellation noise for the second noise.

Prior Art Documents

Patent Documents

[0005]

Patent Document 上1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Considering only sound waves that cancel out the vibration sound of a vehicle, as in the technologies disclosed in Patent Documents 1 and 2, it is not sufficient to reduce the vibration perceived by the passengers of a moving body such as a vehicle due to the vibration of the moving body.

[0007] In view of such circumstances, an object of the present disclosure is to improve a technique for reducing vibration perceived by passengers of a moving body due to the vibration of the moving body.

Means for Solving the Problems

[0008] A vibration reduction device according to one embodiment of the present disclosure is a vibration reduction device for reducing vibrations perceived by an occupant of a moving body, comprising a vibration generating device and a control device for controlling the drive of the vibration generating device, wherein the control device detects the direction, amplitude, and phase of the occupant's head movement, estimates the sound pressure of the air vibration generated by the vibration generating device based on the direction and amplitude of the movement, sets the phase of the air vibration based on the phase, and controls the drive of the vibration generating device to generate air vibration based on the set sound pressure and phase. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, it is possible to reduce vibrations perceived by the occupants of a moving vehicle due to vibrations of the vehicle. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an example of the configuration of a vehicle equipped with a vibration reduction device according to one embodiment of the present disclosure. [Figure 2] This is a block diagram showing an example configuration of a vibration reduction device according to the first embodiment of the present disclosure. [Figure 3] This is a flowchart illustrating an example of the operation of the control device provided in the vibration reduction device according to the first embodiment of this disclosure. [Figure 4] This diagram illustrates a table showing the relationship between the direction of acceleration and the sound pressure in the occupant's ear canal. [Figure 5] This diagram illustrates the cancellation caused by air vibrations. [Figure 6] This is a block diagram showing an example configuration of a vibration reduction device according to a second embodiment of the present disclosure. [Figure 7] This is a flowchart illustrating an example of the operation of the control device provided in the vibration reduction device according to the second embodiment of this disclosure. [Figure 8] This diagram illustrates masking caused by air vibrations. [Modes for carrying out the invention]

[0011] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0012] <1. First Embodiment> (1-1. Overall structure of the mobile unit) Referring to Figure 1, an example of the overall configuration of a vehicle 1, which corresponds to a mobile body equipped with a vibration reduction device 100 according to one embodiment of the present disclosure, will be described. Note that the mobile body in the present disclosure is not limited to the four-wheeled vehicle 1 shown in Figure 1, but may also be a train or a two-wheeled vehicle, or an aircraft such as an airplane or helicopter.

[0013] Vehicle 1 is a two-wheel drive four-wheeled vehicle that transmits the drive torque output from a drive force source 2, which generates the drive torque, to the left front wheel and the right front wheel. The drive force source 2 may be an internal combustion engine such as a gasoline engine or a diesel engine, a drive motor, or both an internal combustion engine and a drive motor.

[0014] Vehicle 1 may be a four-wheel drive vehicle that transmits driving torque to the front and rear wheels. Vehicle 1 may also be an electric vehicle equipped with two drive motors, for example, a motor for driving the front wheels and a motor for driving the rear wheels, or an electric vehicle equipped with drive motors corresponding to each wheel. Furthermore, if Vehicle 1 is an electric vehicle or a hybrid electric vehicle, Vehicle 1 may be equipped with a secondary battery that stores the power supplied to the drive motors, a motor that generates the power charged to the battery, or a generator such as a fuel cell.

[0015] Vehicle 1 includes, as devices used for driving control of Vehicle 1, a driving force source 2, an electric power steering device 3, and brake devices 4LF, 4RF, 4LR, 4RR (hereinafter, collectively referred to as "brake device 4" when no particular distinction is required). The driving force source 2 outputs driving torque transmitted to the front wheel drive shaft 6F via a transmission (not shown) and a differential mechanism 5. The driving of the driving force source 2 and the transmission is controlled by a vehicle control unit 7 including one or more electronic control units (ECUs: Electronic Control Unit).

[0016] The electric power steering device 3 includes an electric motor (not shown) and a gear mechanism (not shown). The electric power steering device 3 is provided in Vehicle 1 so that the steering angle of the front wheels can be adjusted by being controlled by the vehicle control unit 7. Note that the vehicle control unit 7 controls the electric power steering device 3 based on the steering angle of the steering wheel 8 by the driver.

[0017] The brake devices 4LF, 4RF, 4LR, 4RR apply braking force to their respective wheels. The brake device 4 may be, for example, a hydraulic brake device. In this case, by controlling the driving of the hydraulic unit 9 by the vehicle control unit 7, the hydraulic pressure supplied to each brake device 4 is adjusted. When Vehicle 1 is an electric vehicle or a hybrid electric vehicle, the brake device 4 is used in combination with regenerative braking by the driving motor.

[0018] The vehicle control unit 7 includes one or more electronic control units (ECUs: Electronic Control Unit) that control the driving of the driving force source 2, the electric power steering device 3, and the hydraulic unit 9. When Vehicle 1 includes a transmission that shifts the output output from the driving force source 2 and transmits it to the wheels, the vehicle control unit 7 has a function of controlling the driving of the transmission.

[0019] (1-2. Vibration Reduction Device) Referring to FIG. 2, the vibration reduction device 100 according to the first embodiment will be described.

[0020] (1-2-1. Configuration Example) The vibration reduction device 100 is a device that reduces vibrations perceived by the occupants of a vehicle 1, which is a moving object. The vibration reduction device 100 comprises a vibration generating device 10 and a control device 20.

[0021] (Vibration generating equipment) The vibration generating device 10 is a pair of headphones that are attached to the head of an occupant (e.g., driver) of a vehicle 1, which is a moving object, and generate air vibrations in the occupant's ear canal, as described later. The headphones are equipped with a vibration sensor S, such as an acceleration sensor or an angular velocity sensor. The vibration sensor S can detect vibrations in the longitudinal direction, the width direction, and the height direction of the vehicle 1, respectively.

[0022] Here, it is preferable that the coordinate axes of the vibration sensor S are calibrated at the moment the occupant puts on the headphones and takes a seat. Specifically, the vertical direction of the vibration sensor S is defined as the Z-axis direction, and calibration is performed so that the Z-axis direction coincides with the direction of gravity. In this case, the X-axis direction is set to be perpendicular to the Z-axis direction and parallel to the speaker surface of the headphones. The Y-axis direction is set to be perpendicular to the Z-axis direction and perpendicular to the speaker surface of the headphones. However, the setting of the coordinate axes in this disclosure is not limited to this and can be set as appropriate.

[0023] (Control device) The control device 20 is installed in the vehicle 1 and is capable of communicating with headphones corresponding to the vibration generating device 10 via wired or wireless communication. The control device 20 may also be integrated into the vehicle control unit 7, which will be described later, or it may be built into the headphones corresponding to the vibration generating device 10.

[0024] The control device 20 functions as a device that controls the drive of the vibration generating device 10 by having one or more CPUs (Central Processing Units) or other processors execute a computer program. The computer program is a computer program that causes the processor to execute the operations that the control device 20 should perform, which will be described later. The computer program executed by the processor may be recorded on a recording medium that functions as a memory unit 26, which will be described later, or it may be recorded on a recording medium built into the control device 20 or on any recording medium that can be attached externally to the control device 20.

[0025] The recording medium for storing computer programs may include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs, DVDs, and Blu-ray®; magneto-optical media such as floppy disks; memory elements such as RAM and ROM; flash memory such as USB memory and SSDs; and other media capable of storing programs.

[0026] The control device 20 comprises a processing unit 21 and a storage unit 26.

[0027] (processing) The processing unit 21 is composed of, for example, one or more processors such as CPUs. The processing unit 21 may also include various peripheral components. Part or all of the processing unit 21 may be composed of updatable components such as firmware, or it may be a program module that is executed by instructions from the CPU or the like.

[0028] (Storage part) The storage unit 26 is composed of one or more memories, such as RAM or ROM, that are connected to the processing unit 21 in a communicative manner. However, the type and number of storage units 26 are not particularly limited. The storage unit 26 stores information such as computer programs executed by the processing unit 21, various parameters used in arithmetic processing, detection results, and calculation results.

[0029] (1-2-2. Functional configuration of the processing unit) An example of the functional configuration of the processing unit 21 of the control device 20 is described below. The processing unit 21 comprises an acquisition unit 22, a detection unit 23, a setting unit 24, and a drive control unit 25. Each of the acquisition unit 22, detection unit 23, setting unit 24, and drive control unit 25 is a function realized by the execution of a computer program by one or more processors such as a CPU. However, some or all of the acquisition unit 22, detection unit 23, setting unit 24, and drive control unit 25 may be configured using analog circuits.

[0030] (Acquisition Department) The acquisition unit 22 acquires the sensor signal from the vibration sensor S provided by the headphones, which correspond to the vibration generating device 10.

[0031] (Detection unit) The detection unit 23 detects the direction, amplitude, and phase of the occupant's head movement based on the sensor signals acquired by the acquisition unit 22. Further details will be described later.

[0032] (Settings section) The setting unit 24 sets the sound pressure of the air vibration generated by the headphones corresponding to the vibration generating device 10 based on the direction and amplitude of the head movement detected by the detection unit 23. The setting unit 24 also sets the phase of the air vibration generated by the headphones corresponding to the vibration generating device 10 based on the phase of the head movement detected by the detection unit 23. Further details will be described later.

[0033] (Drive control unit) The drive control unit 25 controls the drive of the headphones, which correspond to the vibration generating device 10, to generate air vibrations based on the sound pressure and phase set by the setting unit 24.

[0034] (1-2-3. Example of Control Device Operation) Referring to Figure 3, an example of the operation of the control device 20 according to this embodiment will be explained with reference to a flowchart.

[0035] This example illustrates a case where a passenger wearing headphones is riding in a vehicle 1, which represents a mobile object. However, this disclosure is not limited to this example.

[0036] In step S10, the acquisition unit 22 acquires the sensor signal from the vibration sensor S of the headphones, which corresponds to the vibration generating device 10. The process then proceeds to step S11.

[0037] In step S11, the detection unit 23 detects the direction, amplitude, and phase of the occupant's head movement based on the sensor signal from the vibration sensor S acquired in step S10. The amplitude may be the amplitude of acceleration, the amplitude of displacement, or both of the amplitudes. The process then proceeds to step S12.

[0038] In step S12, the setting unit 24 sets the sound pressure of the air vibration generated by the headphones corresponding to the vibration generating device 10 based on the direction and amplitude of the head movement detected in step S11. It is preferable that the air vibration generated by the headphones has a frequency in the inaudible range that is lower than the audible range, and more preferably a frequency within the range of 5 Hz to 20 Hz. This is because the relative air vibration with respect to the air around the head, which is generated due to the movement of the occupant's head caused by the vibration of the vehicle body 1, typically has a frequency in the inaudible range that is lower than the audible range.

[0039] Specifically, the setting unit 24 uses the direction and amplitude of head movement detected in step S11 to estimate the sound pressure generated by the compression and expansion of air in the occupant's ear canal. The setting unit 24 then sets the estimated sound pressure as the sound pressure of the air vibration generated by the headphones corresponding to the vibration generating device 10. The method for estimating sound pressure will be explained in more detail below.

[0040] For estimating sound pressure, a table T may be used, for example, as shown in Figure 4, which shows the relationship between the direction of acceleration and the sound pressure in the ear canal for each magnitude of acceleration. Table T is pre-stored in the memory unit 26 and can be referenced as appropriate by the setting unit 24 when estimating sound pressure.

[0041] Table T can be created using any device capable of measuring the magnitude and direction of acceleration, as well as the sound pressure in the ear canal. Examples of such devices include known or arbitrary earphone microphones or acceleration sensors. That is, the air vibrations in the ear canal of the occupant caused by the direction and amplitude of the occupant's head movement are confirmed in advance and stored in the storage unit 26 as Table T. Table T may also be created by learning data from multiple occupants using deep learning such as DNN (Deep Neural Network) via an external server that can communicate with the control device 20.

[0042] In Figure 4, "front" refers to the front side of Vehicle 1 in the longitudinal direction, and "rear" refers to the rear side of Vehicle 1 in the longitudinal direction. "up" refers to the upper side of Vehicle 1 in the height direction, and "down" refers to the lower side of Vehicle 1 in the height direction. "left" refers to the left side of Vehicle 1 in the width direction, and "right" refers to the right side of Vehicle 1 in the width direction. "pitch front" refers to the front side of Vehicle 1 in the pitch direction, and "pitch rear" refers to the rear side of Vehicle 1 in the pitch direction. "yaw left" refers to the left side of Vehicle 1 in the yaw direction, and "yaw right" refers to the right side of Vehicle 1 in the yaw direction. "roll left" refers to the left side of Vehicle 1 in the roll direction, and "roll right" refers to the right side of Vehicle 1 in the roll direction. "compression" refers to the compression of air in the ear canal. "expansion" refers to the expansion of air in the ear canal. The magnitude of the sound pressure (Pa) is appropriately determined according to the magnitude of the acceleration.

[0043] For example, if the direction of acceleration corresponding to the direction of the occupant's head movement is aligned with the roll direction of the vehicle 1, the setting unit 24 may identify the change in sound pressure in the ear canal linked to the roll direction of the vehicle 1 from the table T according to the magnitude of the acceleration corresponding to the amplitude of the head movement. In this way, the setting unit 24 may estimate the changes in sound pressure that occur due to the compression and expansion of air in the ear canals of the occupant's left and right ears, respectively.

[0044] However, instead of using Table T, the above-mentioned estimation of sound pressure may use a transfer function that shows the relationship between the direction and amplitude of the occupant's head movement and the air vibration. This transfer function can be appropriately calculated using any device capable of measuring the magnitude and direction of acceleration, as well as the sound pressure in the ear canal.

[0045] In this way, the setting unit 24 can estimate the sound pressure of the air vibrations generated around the head due to the shaking of the occupant's head caused by the vibration of the vehicle body 1. The setting unit 24 then sets the sound pressure estimated in this way as the sound pressure of the air vibrations to be generated by the headphones corresponding to the vibration generating device 10. The process then proceeds to step S13.

[0046] In step S13, the setting unit 24 sets the phase of the air vibration generated by the headphones corresponding to the vibration generating device 10, based on the phase of the head movement detected in step S11.

[0047] Specifically, the setting unit 24 sets the phase of the air vibration generated by the headphones corresponding to the vibration generating device 10 to be the opposite phase to the phase of the head movement detected in step S11. That is, the air vibration generated by the headphones corresponding to the vibration generating device 10 is set to a phase that is the opposite to the phase estimated from the head movement of the occupant caused by the vibration of the vehicle body 1. In this specification, "opposite" does not necessarily have to be the opposite in a mathematically strict sense, but is sufficient if it is within the range of tolerance.

[0048] In steps S12 and S13, the sound pressure and phase are set, and in step S14, air vibrations are output from headphones corresponding to the vibration generating device 10, which will be described later. This produces the following effect: Air vibrations generated around the head due to the movement of the occupant's head, shown by the dashed line in Figure 5, are canceled out by the air vibrations output from the headphones, shown by the solid line in Figure 5. As a result, the vibrations perceived by the occupant due to the vibration of the vehicle body 1 can be reduced. Note that steps S12 and S13 do not necessarily have to be performed in this order; they may be performed in reverse order or in parallel. The process then proceeds to step S14.

[0049] In step S14, the drive control unit 25 controls the drive of the headphones corresponding to the vibration generating device 10 so as to generate air vibrations based on the sound pressure set in step S12 and the phase set in step S13.

[0050] Specifically, the drive control unit 25 generates a control signal to output air vibrations having the sound pressure set in step S12 and the phase set in step S13 from headphones corresponding to the vibration generating device 10. The drive control unit 25 then transmits the generated control signal to the headphones via wired or wireless communication. As a result, air vibrations having the sound pressure set in step S12 and the phase set in step S13 are output from the headphones. The process is then completed.

[0051] (1-3. Effects) As described above, the control device 20 according to the first embodiment detects the direction, amplitude, and phase of the head movement of the occupant of the vehicle 1, which corresponds to the moving object, from headphones corresponding to the vibration generating device 10. The control device 20 then sets the sound pressure of the air vibration generated by the headphones corresponding to the vibration generating device 10 based on the detected direction and amplitude of the movement. The control device 20 also sets the phase of the air vibration generated by the headphones corresponding to the vibration generating device 10 based on the detected phase. The control device 20 then controls the drive of the headphones corresponding to the vibration generating device 10 so as to generate air vibration based on the set sound pressure and phase.

[0052] With this configuration, vibrations perceived by the occupants due to vibrations of the vehicle 1, which is the moving body, can be reduced. Specifically, the vibration of the vehicle 1 causes the head to shake, generating relative air vibrations with respect to the air around the head. However, these air vibrations are canceled out by air vibrations from the headphones, thus reducing the vibrations perceived by the occupants. As a result, the ride comfort of the vehicle 1 is improved.

[0053] <2. Second Embodiment> Referring to Figure 6, the vibration reduction device 200 according to the second embodiment will be described. The differences from the vibration reduction device 100 according to the first embodiment will be mainly described below. For other aspects, the description in the first embodiment will be used. Therefore, modifications in the first embodiment are also applicable to the second embodiment.

[0054] (2-1. Vehicles) A vibration sensor 30 is provided at a predetermined second position on the vehicle 1, which corresponds to the moving body. The vibration sensor 30 is an acceleration sensor or angular velocity sensor capable of detecting floor vibrations or seat vibrations of the vehicle 1, which corresponds to the moving body. For example, the vibration sensor 30 may be a suspension stroke sensor or vertical G sensor provided on the suspension of the vehicle 1, or a seat pressure sensor provided at the seating position of the occupant of the vehicle 1.

[0055] However, in the second embodiment, the vibration sensor 30 is not limited to an acceleration sensor or angular velocity sensor capable of detecting floor vibrations or seat vibrations of the vehicle 1, which corresponds to a moving object. The vibration sensor 30 may be the acceleration sensor, or in place of or in addition to the acceleration sensor, a vibration sensor provided by headphones similar to those in the first embodiment.

[0056] (2-2. Vibration Reduction Devices) The vibration reduction device 200 is a device that reduces vibrations perceived by the occupants of a vehicle 1, which is a moving object. The vibration reduction device 200 comprises a vibration generating device 40 and a control device 20.

[0057] (2-3. Vibration Generating Equipment) The vibration generating device 40 is installed at a predetermined first position on the vehicle 1, which corresponds to the moving body. The vibration generating device 40 may be an actuator capable of vibrating a part of the vehicle 1, which corresponds to the moving body. The actuator may be a vibration actuator capable of vibrating the roof trim, rear gate, onboard subwoofer, cargo area floor, or seats, or it may be a brake-related actuator such as a brake booster or ABS (Antilock Braking System).

[0058] (2-4. Control device) The control device 20 is installed in the vehicle 1 and can communicate with the vibration sensor 30 and the actuator corresponding to the vibration generating device 40 via wired or wireless communication. The vehicle control unit 7 may also perform the functions of the control device 20.

[0059] (2-4-1. Example of Control Device Configuration) The acquisition unit 22 of the control device 20 acquires the sensor signal from the vibration sensor 30, which is installed at a predetermined second position on the vehicle 1, which corresponds to the moving object.

[0060] The detection unit 23 of the control device 20 detects the direction, amplitude, and phase of the occupant's head movement based on the sensor signals acquired by the acquisition unit 22. Further details will be described later.

[0061] The setting unit 24 sets the sound pressure of the air vibration generated by the actuator corresponding to the vibration generating device 40 based on the direction and amplitude of the head sway detected by the detection unit 23. The setting unit 24 also sets the phase of the air vibration generated by the actuator corresponding to the vibration generating device 10 based on the phase of the head sway detected by the detection unit 23. Further details will be described later.

[0062] The drive control unit 25 controls the drive of the actuator corresponding to the vibration generating device 40 so as to generate air vibrations based on the sound pressure and phase set by the setting unit 24.

[0063] (2-4-2. Examples of Control Device Operation) Referring to Figure 7, an example of the operation of the control device 20 according to this embodiment will be explained with reference to a flowchart.

[0064] This operational example describes the case where an occupant is seated in a vehicle 1, which corresponds to a moving object. Furthermore, this operational example describes the case where a seat pressure sensor located at the occupant's seat is used as the vibration sensor 30. Additionally, this operational example describes the case where an actuator capable of vibrating the roof trim of the vehicle 1, which corresponds to a moving object, is used as the vibration generating device 40. However, this disclosure is not limited to these examples; for instance, the vibration sensor 30 may be replaced by a vibration sensor provided in headphones, similar to the first embodiment, either additionally or alternatively.

[0065] In step S20, the acquisition unit 22 acquires the sensor signal from the vibration sensor 30 located at a predetermined second position on the vehicle 1. If a vibration sensor provided by headphones is additionally or alternatively applied as the vibration sensor 30, the sensor signal from that vibration sensor is acquired additionally or alternatively. The process then proceeds to step S21.

[0066] In step S21, the detection unit 23 detects the direction, amplitude, and phase of the occupant's head movement based on the sensor signal from the vibration sensor 30 acquired in step S20. The amplitude may be the amplitude of acceleration or the amplitude of displacement.

[0067] In other words, a table T2 is created in advance, which associates the direction, amplitude, and phase of various vibrations caused by the body vibration of vehicle 1 with the direction, amplitude, and phase of the occupant's head movement, and is stored in the storage unit 26 of the control device 20. The detection unit 23 detects the direction, amplitude, and phase of head movement by referring to the table T2 stored in the storage unit 26 and selecting the direction, amplitude, and phase of head movement that corresponds to the direction, amplitude, and phase of vibration indicated by the sensor signal acquired in step S20.

[0068] However, instead of table T2, training data in which the relationship between vibrations observed by the vibration sensor 30 and head sway has been pre-learned by a DNN or the like may be used. Alternatively, a transfer function showing the relationship between vibrations observed by the vibration sensor 30 and head sway may be used. This transfer function can be appropriately calculated using a known or arbitrary vibrator. The process then proceeds to step S22.

[0069] In step S22, the setting unit 24 sets the sound pressure of the air vibration generated by the actuator corresponding to the vibration generating device 40, based on the direction and amplitude of the head sway detected in step S21.

[0070] Specifically, the setting unit 24 estimates the sound pressure generated by the compression and expansion of air in the occupant's ear canal from the direction and amplitude of the head movement detected in step S21. The setting unit 24 then sets the estimated sound pressure as the sound pressure of the air vibration generated by the actuator corresponding to the vibration generating device 40. The details are the same as in the first embodiment. The process then proceeds to step S23.

[0071] In step S23, the setting unit 24 sets the phase of the air vibration generated by the actuator corresponding to the vibration generating device 10 based on the phase of the head sway detected in step S21.

[0072] Specifically, the setting unit 24 sets the phase of the air vibration generated by the actuator corresponding to the vibration generating device 40 to be the opposite phase to the phase of the head movement detected in step S21. However, there is a distance from the position of the roof trim where the actuator corresponding to the vibration generating device 40 is installed to the position of the occupant's head (ears). Therefore, the phase of the air vibration is set to take into account the phase difference corresponding to this distance. For example, when the air vibration generated by the actuator corresponding to the vibration generating device 40 reaches the occupant's ears, the setting unit 24 adjusts the timing of outputting the air vibration using this distance so that the air vibration generated around the head due to the vibration of the vehicle 1 is canceled out. The position of the occupant's ears can be determined by image processing of images captured by the onboard camera installed in the vehicle 1.

[0073] Here, in step S22 or S23, the setting unit 24 may set the sound pressure and phase of the air vibration based on the information of the orientation of the occupant's face and the direction, amplitude, and phase of the head movement. This makes it possible to more accurately calculate the phase difference corresponding to the distance from the position of the roof trim equipped with the actuator corresponding to the vibration generating device 40 to the position of the occupant's head. The orientation of the occupant's face can be appropriately obtained by image processing of the image captured by the onboard camera installed in the vehicle 1. Steps S22 and S23 do not necessarily have to be performed in this order; they may be performed in reverse order or in parallel. After that, the process proceeds to step S24.

[0074] In step S24, the drive control unit 25 controls the drive of the actuator corresponding to the vibration generating device 40 so as to generate air vibrations based on the sound pressure set in step S22 and the phase set in step S23.

[0075] Specifically, the drive control unit 25 generates a control signal for outputting air vibrations having the sound pressure set in step S22 and the phase set in step S23 from an actuator corresponding to the vibration generating device 40. The drive control unit 25 then transmits the generated control signal to the actuator via wired or wireless communication. As a result, the actuator outputs air vibrations having the sound pressure set in step S22 and the phase set in step S23. With this, the process is completed.

[0076] (2-5. Effects) As described above, the control device 20 according to the second embodiment detects the direction, amplitude, and phase of the head sway of the occupant of the vehicle 1, which corresponds to the moving body, based on the sensor signal of the vibration sensor 30 at a predetermined second position on the vehicle 1, which corresponds to the moving body. The control device 20 then sets the sound pressure of the air vibration generated by the actuator corresponding to the vibration generating device 40, which is installed at a predetermined first position on the vehicle 1, which corresponds to the moving body, based on the detected direction and amplitude of the sway. The control device 20 also sets the phase of the air vibration generated by the actuator corresponding to the vibration generating device 40, which is installed at a predetermined first position on the vehicle 1, which corresponds to the moving body, based on the detected phase. The control device 20 then controls the drive of the actuator corresponding to the vibration generating device 40, which is installed at a predetermined first position on the vehicle 1, which corresponds to the moving body, so as to generate air vibration based on the set sound pressure and phase.

[0077] With this configuration, vibrations perceived by the occupants due to vibrations of the vehicle 1, which is the moving body, can be reduced. Specifically, the vibration of the vehicle 1 causes the head to shake, generating relative air vibrations with respect to the air around the head. However, these air vibrations are canceled out by air vibrations from the actuator, thus reducing their perception by the occupants. As a result, the ride comfort of the vehicle 1 is improved.

[0078] While preferred embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the present disclosure is not limited to such examples. It is clear to any person with ordinary skill in the art to which the present disclosure belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also be understood to fall within the technical scope of the present disclosure. For example, the functions, etc., included in each component or step, etc., can be rearranged in a logically consistent manner, and multiple components or steps, etc., can be combined into one or divided.

[0079] As one variation, in step S12 or S13 or step S22 or S23, the setting unit 24 may additionally perform the following processing. That is, the setting unit 24 may set the frequency of further air vibrations to be output superimposed on the air vibrations output from headphones corresponding to vibration generating device 10 or actuators corresponding to vibration generating device 40. In this case, the setting unit 24 may set a frequency in the inaudible range that is lower than the audible range, for example, a frequency within the range of 5 Hz to 20 Hz. As a result, for example, high-frequency noise from motors or inverters in electric vehicles, etc., shown by thin solid lines in Figure 8, is masked by further air vibrations shown by bold solid lines or dashed lines in Figure 8. In Figure 8, bold solid lines show air vibrations from actuators, and bold dashed lines show air vibrations from headphones. The sound pressure and phase of the further air vibrations are not particularly limited as long as they do not cause discomfort to the occupants, and can be set as appropriate.

[0080] Furthermore, the setting unit 24 may perform the masking described above if the acceleration of vehicle 1 exceeds a threshold. In this case, the acceleration of vehicle 1 may be calculated based on the sensor signal of an acceleration sensor (not shown) provided in vehicle 1 and used to detect the acceleration of vehicle 1. Alternatively, the acceleration of vehicle 1 may be estimated based on the DC component of the vibration sensor S provided in the headphones.

[0081] Furthermore, the technology disclosed herein can also be realized as a vehicle 1 equipped with the vibration reduction devices 100, 200 described in the above-described embodiments, a vibration reduction method using the vibration reduction devices 100, 200, a computer program that causes a computer to function as the control device 20 described in the above-described embodiments, and a non-temporary tangible recording medium on which the computer program is recorded. [Explanation of symbols]

[0082] 1: Vehicle, 100, 200: Vibration reduction device, 10: Vibration generating device, 20: Control device, 21: Processing unit, 22: Acquisition unit, 23: Detection unit, 24: Setting unit, 25: Drive control unit, 26: Memory unit, 30: Vibration sensor

Claims

1. A vibration reduction device that reduces vibrations perceived by the occupants of a moving vehicle, Vibration generating equipment, The system includes a control device for controlling the drive of the vibration generating device, The control device is The direction, amplitude, and phase of the head movement of the occupant are detected. Based on the direction and amplitude of the vibration, the sound pressure of the air vibration generated by the vibration generating device is set. Based on the aforementioned phase, the phase of the air vibration is set, The drive of the vibration generating device is controlled to generate the air vibration based on the set sound pressure and phase. Vibration reduction device.

2. The vibration generating device is a pair of headphones that are worn on the head and generate the air vibrations inside the ear canal of the occupant. The headphones are equipped with a vibration sensor, The control device is Based on the sensor signal of the vibration sensor, the direction, amplitude, and phase of the head's movement are detected. The vibration reduction device according to claim 1.

3. The vibration generating device is installed at a predetermined first position on the moving body. The moving body further comprises a vibration sensor provided at a predetermined second position, The control device is Based on the sensor signal of the vibration sensor, the direction, amplitude, and phase of the head's movement are detected. The vibration reduction device according to claim 1.

4. The control device is The information on the orientation of the crew member's face is obtained, Based on the information regarding the orientation of the face, and the direction, amplitude, and phase of the head movement, the sound pressure and phase of the air vibration are set. The vibration reduction device according to claim 3.

5. The vibration generating device is an actuator that vibrates a part of the moving body. The vibration reduction device according to claim 3.

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