Information transmission device

Abstract

[Problem] To provide an information transmission device that improves predictability of behavior caused by steering a vehicle regardless of the seating position in a vehicle interior. [Solution] An information transmission device 100 provided in a vehicle having a steering device 1 for steering wheels FW is configured to include: a parameter detection unit 71 that detects a parameter σ correlated to a steering amount of the steering device; an excitation unit 240 that excites the air around an occupant by using a predetermined excitation waveform according to a change in the parameter of the steering device; a rotation center calculation unit that calculates the position of the rotation center NSP of yaw behavior of the vehicle body; and gain adjustment units 200 and 210 that adjust the output gain of the excitation waveform according to the relative position between the rotation center and the seating position of the occupant.

Description

Technical Field

[0001] The present invention relates to an information transmission device that transmits information regarding the behavior of a vehicle to an occupant of the vehicle.

Background Art

[0002] As a technology related to presenting information regarding the turning behavior of a vehicle such as an automobile to an occupant by sound, for example, Patent Document 1 describes a vehicle acoustic control device including a plurality of speakers arranged so as to surround the occupant in a plan view, and a controller that controls the sound field in the vehicle interior by driving the plurality of speakers individually. The controller sets a reference yaw rate corresponding to the driving input when a driving input that changes the vehicle behavior is made, detects the actual yaw rate of the vehicle, and rotates the sound field in the vehicle interior in the direction in which the vehicle behavior actually changes according to the deviation of the actual yaw rate with respect to the reference yaw rate, and produces a change in the turning behavior corresponding to the driving input before the turning behavior actually changes. Patent Document 2 describes a vehicle effect sound generation device that enhances the sense of presence of the vehicle turning state by providing driving information to the driver through hearing. The gain of a plurality of integral order components of the engine speed is set based on the accelerator opening, and an effect sound is generated based on the set gain and a storage unit of the plurality of integral order components. Also, it is described that when the vehicle is in a turning driving state, the gain of the fourth order component among the plurality of integral order components is set larger than in the normal driving state. Patent Document 3 describes a vehicle seat device in which, when the vehicle turns, the turning direction is accurately transmitted to the seated person while maintaining the quietness of the vehicle interior. The vehicle seat device has a left speaker that outputs sound from the left side of the headrest and a right speaker that outputs sound from the right side of the headrest, and it is described that when turning to the left, sound is output from the left speaker, and when turning to the right, sound is output from the right speaker.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] International Publication No. WO2014 / 174839 [Patent Document 2] Japanese Patent Publication No. 2016-145884 [Patent Document 3] Japanese Patent Publication No. 2022-119227 [Overview of the project] [Problems that the invention aims to solve]

[0004] Because there is a time response delay between the start of steering and the actual occurrence of vehicle behavior, resulting in the generation of lateral acceleration, yaw rate, roll angle, etc., depending on the steering situation, occupants may perceive lateral acceleration, etc., as occurring abruptly, and may experience discomfort or anxiety due to their inability to properly maintain their physical balance. In response to this, possible countermeasures include reducing the yaw rate gain in relation to the vehicle's steering angle, or improving the occupant's ability to be held in place by features such as seats. However, reducing the yaw rate gain slows down the vehicle's responsiveness, compromising its performance and marketability. Furthermore, seat-based solutions are insufficient to adequately accommodate occupants of various body types.

[0005] In contrast, if information about the vehicle's behavior can be presented to the occupants through acoustic information, as in the conventional technology described above, it is possible to improve the occupants' ability to anticipate the behavior caused by the vehicle's steering and suppress feelings of abruptness. However, there are concerns that even if uniform information is transmitted acoustically to all occupants, the appropriate effect may not be achieved because the perception of transient jerk (acceleration of acceleration) that occurs during the initial stages of a vehicle's turn varies depending on the seating position inside the vehicle. In view of the above-mentioned problems, the object of the present invention is to provide an information transmission device that improves the predictability of behavior caused by steering a vehicle, regardless of the seating position inside the vehicle. [Means for solving the problem]

[0006] To solve the above-mentioned problems, an information transmission device according to one aspect of the present invention is an information transmission device provided in a vehicle having a steering device for steering wheels, and is characterized by comprising: a parameter detection unit for detecting parameters correlated with the steering amount of the steering device; an excitation unit for exciting the air around the occupant using a predetermined excitation waveform in accordance with the change in the parameters of the steering device; a rotation center calculation unit for calculating the position of the rotation center of the yaw behavior of the vehicle body; and a gain adjustment unit for adjusting the output gain of the excitation waveform according to the relative position between the rotation center and the seating position of the occupant. According to this, by generating sound in accordance with the amount of steering input to the steering system, it is possible to predict the behavior of the vehicle through sound in the initial stages of steering, prior to the actual occurrence of lateral acceleration, yaw rate, roll angle, etc. This improves the occupants' ability to anticipate vehicle behavior and prevents them from feeling that the vehicle's actions are sudden or unexpected. Furthermore, by adjusting the output gain of the excitation waveform according to the relative position between the rotation center of the yaw motion and the occupant's seating position, it becomes possible to transmit information that appropriately reflects the effects of lateral acceleration and jerk experienced by the occupant due to the vehicle's yaw motion. This suppresses the discrepancy between the information transmitted to the occupant by the excitation unit and the lateral acceleration and jerk actually experienced by the occupant, improving the predictability of behaviors caused by vehicle steering, regardless of the occupant's seating position in the cabin.

[0007] In the present invention, the gain adjustment unit can be configured to change the output gain in accordance with the change in the distance between the pivot center and the seating position. According to this, it is possible to reflect how the acceleration and jerk experienced by the occupant change in response to an increase in the distance from the pivot point to the seating position, and to transmit appropriate information to the occupant.

[0008] In the present invention, the gain adjustment unit can be configured to reduce the output gain in accordance with the increase in the angle difference between the slip angle of the vehicle body and the angle made by the straight line connecting the pivot center and the seating position with respect to the vehicle body centerline in a plan view. According to this method, the lateral component of the acceleration and jerk experienced by the occupants due to the yaw angular acceleration of the vehicle body can be appropriately estimated, and appropriate information can be conveyed to the occupants.

[0009] In the present invention, multiple seating positions are provided, and multiple excitation units are provided corresponding to the multiple seating positions. The amplitude of the excitation waveform output by the multiple excitation units can be configured to differ according to the relative position between the rotation center and the seating position. According to this, it is possible to transmit appropriate information to multiple occupants seated in different positions, according to their respective seating locations.

[0010] In the present invention, the excitation waveform can be configured to have a dominant frequency that falls within a frequency band of 100 to 400 Hz. This allows for the use of Pacinian corpuscles and other structures that are audible and highly sensitive to touch, resulting in improved acoustic sound perception and tactile perception by the crew. Therefore, information can be transmitted more reliably to the crew. Here, more preferably, by setting the dominant frequency in the frequency band of 150 to 300 Hz, a region with better receptor sensitivity can be used, thereby promoting the effects described above. In the present invention, the vehicle is equipped with an automatic driving control unit that instructs the steering device on the amount of steering, and the parameter that correlates with the amount of steering of the steering device is configured to be an instructed value by the automatic driving control unit. According to this, even when automatic driving control is being executed, causing a change in steering angle in the steering system without the occupant's steering input, when steering by automatic driving control begins, a sound is generated corresponding to the change in steering amount and the positional relationship between the rotation center and the seating position. This makes it possible to anticipate the occurrence of vehicle behavior accompanied by lateral acceleration, yaw rate, roll angle, etc., and prevents the occupant from feeling abrupt about the vehicle's behavior. [Effects of the Invention]

[0011] As described above, according to the present invention, it is possible to provide an information transmission device that improves the predictability of the behavior generated by steering of a vehicle regardless of the seating position in the vehicle interior.

Brief Description of Drawings

[0012] [Figure 1] It is a figure which shows typically the structure of the electric power steering apparatus of the vehicle which has 1st Embodiment of the information transmission apparatus to which this invention is applied. [Figure 2] It is a figure which shows typically the system configuration of the information transmission apparatus of 1st Embodiment. [Figure 3] It is a figure which shows typically an example of the vibration waveform in 1st Embodiment. [Figure 4] It is a figure which shows typically the timing of the electric pulse which a receptor emits when stimulated. [[ID=I18]] [Figure 5] It is a figure which shows the sensitivity distribution with respect to the frequency of a Pacinian corpuscle and a Meissner's corpuscle. [Figure 6] It is a figure which shows typically an example of the gain adjustment in the 1st gain adjustment part of 1st Embodiment. [Figure 7] [[ID=I26]]It is a figure which shows typically an example of the output history of the microphone in the 1st Embodiment. [Figure 8] It is a figure which shows an example of the correlation of the sound pressure of the ambient noise with the frequency in the 1st Embodiment. [Figure 9] It is a figure which shows typically an example of the gain adjustment in the 2nd gain adjustment part of 1st Embodiment. [Figure 10] It is a figure which shows an example of the lateral acceleration, lateral jerk of each row seat at the start of turning in the vehicle which has a 3 - row seat, and the yaw rate of the vehicle body. [Figure 11] It is a figure which shows the resultant force generated by the vehicle body slip angle. [Figure 12] It is a figure which shows an example of the seat arrangement in the vehicle interior of the vehicle in the first embodiment. [Figure 13] It is a figure which shows typically an example of the gain adjustment in the 3rd gain adjustment part of 1st Embodiment. [Figure 14]This diagram schematically shows an example of gain adjustment in the fourth gain adjustment section. [Figure 15] This diagram schematically shows an example of gain adjustment in the fifth gain adjustment section. [Figure 16] This diagram schematically illustrates an example of the cornering force characteristics of a tire in response to changes in load. [Figure 17] This diagram schematically illustrates an example of a tire's cornering power characteristics in response to changes in load. [Figure 18] This diagram schematically shows the configuration of an automated driving system for a vehicle equipped with the information transmission device of the second embodiment. [Modes for carrying out the invention]

[0013] <First Embodiment> The following describes a first embodiment of an information transmission device to which the present invention is applied. The information transmission device of the first embodiment is installed in a four-wheeled vehicle (for example, a passenger car or other automobile) that steers (turns) the two front wheels. The vehicle is equipped with an electric power steering system that provides steering assist force to the steering mechanism that steers the front wheels using an electric motor.

[0014] Figure 1 is a schematic diagram showing the configuration of the electric power steering system of a vehicle according to the first embodiment. The electric power steering system 1 is composed of a steering wheel 10, a steering shaft 20, an intermediate shaft 21, a pinion shaft 22, a rack shaft 30, a rack housing 40, a tie rod 50, a housing 60, a steering angle sensor 71, a torque sensor 72, an actuator unit 80, an electric power steering control unit (EPS control unit) 90, and the like.

[0015] The steering wheel 10 is, for example, an annular operating member that the driver rotates to input steering operations. The steering wheel 10 is positioned in the vehicle's interior, facing the driver's seat.

[0016] The steering shaft 20 is a rotating shaft with one end attached to the steering wheel 10, and it transmits the rotational motion of the steering wheel 10 to a rack and pinion mechanism that converts it into translational motion in the vehicle width direction. An intermediate shaft 21 and a pinion shaft 22 are sequentially connected to the end of the steering shaft 20 opposite to the steering wheel 10.

[0017] Universal joints (Cardan joints) 23 and 24 are provided between the steering shaft 20 and the intermediate shaft 21, and between the intermediate shaft 21 and the pinion shaft 22, respectively, which are capable of transmitting rotation while the shafts are bent. A pinion gear is formed at the tip of the pinion shaft 22, which meshes with the rack gear 31 of the rack shaft 30 to drive the rack shaft 30.

[0018] The rack axis 30 is a columnar member positioned so that its longitudinal direction (axial direction) aligns with the vehicle width direction. The rack shaft 30 is supported so as to be able to translate relative to the vehicle body in the vehicle width direction. A rack gear 31 is formed on a portion of the rack shaft 30, which meshes with the pinion gear of the pinion shaft 22. The rack shaft 30 moves in a straight line along the vehicle width direction, driven by a pinion gear that drives the rack gear 31 in response to the rotation of the steering shaft 20. The rack gear 31 is positioned offset to either the left or right side (usually the driver's side) in the vehicle width direction. For example, if the vehicle is a so-called right-hand drive vehicle with the driver's seat on the right front, the rack gear 31 is positioned offset to the right of the center when in the neutral position.

[0019] The rack housing 40 is a substantially cylindrical member that houses and supports the rack shaft 30 so that it can be displaced relative to it along the vehicle width direction. Rack boots 41 are provided at both ends of the rack housing 40. The rack boot 41 is a component that allows relative displacement of the tie rod 50 with respect to the rack housing 40, while preventing foreign matter such as dust from entering the rack housing 40. The rack boot 41 is formed in a flexible, bellows-like shape using a resin-based material such as elastomer.

[0020] The tie rod 50 is an axial interlocking member that connects the end of the rack shaft 30 to the knuckle arm 61 of the housing 60, and rotates the housing 60 around the kingpin axis in conjunction with the translational movement of the rack shaft 30. The inner end of the tie rod 50 in the vehicle width direction is pivotably connected to the end of the rack shaft 30 via a ball joint 51. The outer end of the tie rod 50 in the vehicle width direction is connected to the knuckle arm 61 of the housing 60 via a ball joint 52.

[0021] The housing (knuckle) 60 is a component that houses the hub bearing, which supports the front wheel FW so that it can rotate around the axle. The housing 60 has a knuckle arm 61 that is formed to protrude forward or backward relative to the axle. The housing 60 is supported so as to be rotatable around a kingpin axis, which is a predetermined rotational axis. The kingpin axis is, for example, a virtual axis connecting the bearing center of the strut top mount and the center of the ball joint connecting the lower part of the housing 60 and the transverse link (lower arm) in the case of a vehicle's front suspension being a MacPherson strut type. The housing 60 is pushed and pulled in the vehicle width direction by the rack shaft 30 via the tie rod 50, causing it to rotate around the kingpin axis and steer the front wheels FW.

[0022] The steering angle sensor 71 is an angle encoder that detects the rotational angle position of the pinion shaft 22. The output of the steering angle sensor 71 is transmitted to the electric power steering control unit 90. The electric power steering control unit 90 can calculate the steering angle (toe change angle associated with steering) σ of the front wheel FW based on the output of the steering angle sensor 71.

[0023] The torque sensor 72 is a sensor that detects the torque acting on the pinion shaft 22 (mainly the steering force from the driver). The torque sensor 72 is located on the pinion shaft 22 in a portion closer to the intermediate shaft 21 than to the actuator unit 80. The output of the torque sensor 72 is transmitted to the electric power steering control unit 90.

[0024] The actuator unit 80 is a drive device that rotates the pinion shaft 22 to provide power assist during manual operation and steering during automated operation. The actuator unit 80 is composed of a motor 81, a gearbox 82, and the like. Motor 81 is an electric actuator that generates the driving force supplied to the steering shaft 20. The motor 81's rotational direction and output torque are controlled by the electric power steering control unit 90. The gearbox 82 is equipped with a reduction gear train that reduces (amplifies the torque of) the rotational output of the motor 81 and transmits it to the pinion shaft 22.

[0025] The electric power steering (EPS) control unit 90 is a control device (motor control unit) that provides current instruction values ​​to the motor 81 to control the direction of rotation and output torque. The electric power steering control unit 90 can be configured as a microcontroller having, for example, an information processing unit such as a CPU, a storage unit such as RAM or ROM, an input / output interface, and a bus connecting these. The electric power steering control unit 90 can acquire information such as the output of the steering angle sensor 71 and torque sensor 72, the vehicle's speed, and the operating status of other in-vehicle electronic equipment, either via an in-vehicle LAN such as a CAN communication system or directly.

[0026] When the vehicle is being driven manually, the electric power steering control unit 90 sets the current instruction value supplied to the motor 81 based on the torque input direction and the detected torque value of the torque sensor 72. The electric power steering control unit 90 includes a power supply that supplies power to the motor 81 via a signal line, with current and voltage values ​​corresponding to the current instruction value.

[0027] Figure 2 is a schematic diagram showing the system configuration of the information transmission device according to the first embodiment. The information transmission device 100 uses a speaker 240 located inside the vehicle to vibrate the air around the occupants' ears, thereby notifying the occupants of any signs of impending vehicle behavior through an audible signal. The information transmission device 100 includes a waveform generation unit 110, a differential calculation unit 120, a first gain adjustment unit 130, a microphone 140, a sensing value calculation unit 150, a second gain adjustment unit 160, a neutral steer point calculation unit 170, a yaw rate sensor 180, a vehicle speed sensor 190, a third gain adjustment unit 200, a fourth gain adjustment unit 210, a fifth gain adjustment unit 220, a load sensor 230, a speaker 240, and the like.

[0028] The waveform generation unit 110 generates an excitation waveform, which is the waveform of the acoustic signal generated by the speaker 240. Figure 3 is a schematic diagram showing an example of the excitation waveform in the first embodiment. In Figure 3, the horizontal axis represents time, and the vertical axis represents voltage (amplitude). For example, as shown in Figure 3(a), the excitation waveform can be a sine wave. Furthermore, as shown in Figure 3(b), for example, the excitation waveform can be a waveform obtained by superimposing (combining) multiple sine waves with different wavelengths. Furthermore, the excitation waveform is not limited to these and can be changed as appropriate. For example, various waveforms such as square waves, triangular waves, and waveforms that mimic the sound of a vehicle running can be used as excitation waveforms, either individually or in combination with other waveforms.

[0029] In the first embodiment, the frequency of the excitation waveform can be set to have a dominant frequency in the range of, for example, 100 to 400 Hz, more preferably 150 to 300 Hz. The reason is explained below. When the air surrounding the crew is vibrated, sensory receptors that detect the vibrations include Merkel cells, Meissner corpuscles, and Pacinian corpuscles. Figure 4 schematically shows the timing of electrical pulses emitted by receptors in response to stimulation. In Figure 4, the horizontal axis represents time, and the vertical axis, from top to bottom, represents pressure and the electrical pulse generation state of Merkel cells, Meissner corpuscles, and Pacinian corpuscles.

[0030] Merkel cells respond relatively slowly and correspond to the DC component. Meissner bodies correspond to situations where a rate of change (velocity) of contact pressure is occurring. Pacinian corpuscles respond to moments of transient change and are considered to be the most sensitive of these receptors. Pacinian corpuscles are considered to have the best sensitivity as receptors that allow crew members to perceive minute vibrations as a combination of auditory and tactile information.

[0031] Figure 5 shows the sensitivity distribution of Pacinian and Meissner corpuscles with respect to frequency. In Figure 5, the horizontal axis represents frequency, and the vertical axis represents amplitude above the threshold; a smaller value indicates better sensitivity. As shown in Figure 5, Pacinian corpuscles exhibit good sensitivity in the region of approximately 100 to 400 Hz, and even better sensitivity in the region of 150 to 300 Hz. This range generally falls within the 20Hz to 20kHz range, which is considered the range of human hearing. The dominant frequency of the excitation waveform can be set to 250 Hz, for example.

[0032] The differential calculation unit 120 obtains information regarding the steering angle σ of the front wheel FW detected by the steering angle sensor 71 from the electric power steering control unit 90, and calculates the differential value Δσ by taking the time derivative. The differential calculation unit 120 sequentially transmits the calculated differential value Δσ to the first gain adjustment unit 130.

[0033] The first gain adjustment unit 130 performs the first gain adjustment described below on the fundamental wave of the excitation waveform generated by the waveform generation unit 110. The first gain adjustment involves changing the gain G1, which is the output gain multiplied by the voltage of the excitation waveform, according to the derivative (rate of change per unit time) of the steering angle σ (a parameter correlated with the amount of steering) of the steering device.

[0034] Figure 6 is a schematic diagram showing an example of gain adjustment in the first gain adjustment section. In Figure 6, the horizontal axis represents the absolute value of the derivative Δσ of the steering angle σ of the wheel FW, and the vertical axis represents the gain G1 multiplied by the voltage of the excitation waveform. The gain G1 can be configured to increase in accordance with the increase in the absolute value of the derivative Δσ. Furthermore, the rate of increase of the gain G1 in the first gain adjustment unit 130 with respect to the increase in the absolute value of the differential value Δσ can be configured to be maximum in the region where the absolute value of the differential value Δσ is small, and to decrease as the absolute value of the differential value Δσ increases.

[0035] The gain G1 in the first gain adjustment unit 130 can be calculated, for example, from the absolute value of the derivative Δσ of the rudder angle σ using a logarithmic function. The gain G1 can be expressed, for example, by the following equation 1. Gain G1 = log(absolute value of the derivative of the rudder angle Δσ × coefficient k) (Equation 1) The coefficient k can be a value set during the vehicle development stage, for example, in accordance with the vehicle's characteristics (e.g., yaw gain with respect to steering angle σ, center of gravity position, etc.).

[0036] Microphone 140 is a sound collection device installed inside the vehicle cabin to collect ambient noise inside the vehicle cabin. The microphone 140 is preferably positioned close to the occupant's ear, and can be configured, for example, to be installed on the headrest of the seat. The output of the microphone 140 is transmitted to the sensing value calculation unit 150.

[0037] The sensing value calculation unit 150 extracts components in a predetermined frequency band from the ambient noise of the vehicle acquired by the microphone 140, and transmits the sound pressure of the extracted components as a sensing value to the second gain adjustment unit 160. Figure 7 is a schematic diagram illustrating an example of a microphone output history. In Figure 7, the horizontal axis represents time, and the vertical axis represents the sound pressure of the ambient noise acquired by microphone 140.

[0038] The sensing value calculation unit 150 performs a fast Fourier transform (FFT) on the acoustic signal of the background noise acquired by the microphone 140 to convert it into the frequency domain, and then performs a bandpass filter to extract components in a predetermined frequency band. The frequency band to be extracted is set to include the dominant frequency of the excitation waveform output by the waveform generation unit 110. The sensing value calculation unit 150 uses the average sound pressure of the extracted frequency band as the sensing value used for the second gain adjustment.

[0039] Figure 8 shows an example of the correlation between the sound pressure of background noise and its frequency. In Figure 8, the horizontal axis represents frequency, and the vertical axis represents sound pressure. The bandpass filter can be configured to extract a frequency band near the dominant frequency (for example, 250 Hz) of the excitation waveform in the waveform generation unit 110. The sound pressure in the extracted frequency band (for example, the average value of the frequency band) is provided to the second gain adjustment unit 160 as a sensing value.

[0040] The second gain adjustment unit 160 performs a second gain adjustment on the excitation waveform after the first gain adjustment, as described below. The second gain adjustment adjusts the output amplitude of the excitation waveform in response to changes in ambient noise during vehicle operation (drivetrain noise, aerodynamic noise, road noise, etc.). This is achieved by changing the gain of the excitation waveform according to the sensed value of the in-cabin noise. The second gain adjustment unit 160 performs a second gain adjustment based on the output of the sensing value calculation unit 150.

[0041] The second gain adjustment unit 160 sets the gain G2 based on the sensing value output by the sensing value calculation unit 150. Figure 9 is a schematic diagram showing an example of gain adjustment in the second gain adjustment section. In Figure 9, the horizontal axis represents the sensed value, and the vertical axis represents the gain G2 multiplied by the voltage of the excitation waveform. The gain G2 can be configured to increase in accordance with the increase in the sensing value.

[0042] The gain G2 is set so that the sound pressure of the sound produced by the excitation amplitude output from speaker 240 does not outweigh the sound pressure of the ambient noise near the occupant's ears. Preferably, the gain G2 should be set so that the sound produced by the excitation amplitude blends into the ambient noise of the vehicle, resulting in a sound pressure level that can be unconsciously heard by the occupants. Furthermore, when no steering angle σ is generated in the steering system, the sound pressure of the sound produced by the excitation amplitude output from speaker 240 is kept in a standby state that is sufficiently lower than the sound pressure of the vehicle's ambient noise.

[0043] The output value (voltage) A of the excitation waveform after the first and second gain adjustments described above can be expressed as shown in Equation 2. Output value A = Waveform generation unit output value × Gain G1 × Gain G2 = Waveform generation unit output value × log(absolute value of rudder angle derivative Δσ × coefficient k) × Gain G2 (Equation 2)

[0044] A portion of the output of the second gain adjustment unit 160 is transmitted directly to the speaker 240 as a fundamental term. The remaining portion of the output of the second gain adjustment unit 160 is transmitted to the speaker 240 after undergoing further gain adjustment as a correction term, as described below. Here, the correction term reflects the effects of lateral acceleration and jerk acting on the occupants due to the vehicle's yaw angular velocity and yaw angular acceleration.

[0045] Figure 10 shows an example of the lateral acceleration and lateral jerk of each row of seats, as well as the yaw rate of the vehicle body, at the start of a turn in a vehicle with three rows of seats. From top to bottom, the vertical axis represents lateral acceleration, lateral jerk (acceleration of lateral acceleration), and yaw rate, while the horizontal axis represents time. In a vehicle with three rows of seats arranged sequentially from the front, it can be seen that even within the same vehicle, the timing of sensing lateral acceleration and lateral jerk, as well as the magnitude of lateral acceleration and lateral jerk, differ between the rear row seats and the front row seats. This phenomenon is thought to be caused by the difference in relative position between the neutral steering point, which is the center of rotation for the vehicle's yaw motion, and each seating position. Therefore, in this embodiment, the position of the vehicle's neutral steering point NSP is calculated, and the output gain of the excitation waveform is corrected as follows according to the relative position between the neutral steering point NSP and each seating position.

[0046] The neutral steering point calculation unit 170 calculates the position of the neutral steering point NSP from information on the steering angle σ transmitted from the electric power steering control unit 90, the yaw rate sensor 180, the output of the vehicle speed sensor 190, and the like. The yaw rate sensor 180 is a sensor that detects the yaw rate γ, which is the rotational speed of the vehicle in the yaw direction. The vehicle speed sensor 190 is, for example, installed in the hub portion that supports the wheel, and is a sensor that outputs a vehicle speed signal corresponding to the rotational speed of the wheel. Vehicle speed V can be calculated from the vehicle speed signal.

[0047] Figure 11 shows the resultant force generated by the vehicle body slip angle. As shown in Figure 11, when a slip angle β occurs in the vehicle body, the front wheels FW and rear wheels RW generate lateral forces (cornering forces) corresponding to the slip angle β and stiffness (cornering power) Kf and Kr, respectively. The neutral steering point (NSP) is the point where the yaw moment of the vehicle, generated by the cornering forces of the front wheels (FW) and rear wheels (RW), balances out.

[0048] l: wheelbase l f : Distance from the vehicle's center of gravity to the front axle l r : Distance from the center of gravity of the vehicle to the rear axle l N Distance from the vehicle's center of gravity to the neutral steering point. β: Vehicle slip angle K f Front wheel stiffness (cornering power Cp) K r : Rear wheel stiffness (cornering power Cp) If defined as such, then equation 3 holds true.

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[0049] From Equation 3, we obtain the following Equation 4.

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[0050] γ = yaw rate A = Stability Factor σ = Actual rudder angle (steering amount) V=vehicle speed m = vehicle mass Therefore, equations 5 through 7 below hold true.

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[0051] Figure 12 shows an example of the seat arrangement inside the vehicle's interior in the first embodiment. The vehicle has, for example, a first-row seat S1, a second-row seat S2, and a third-row seat S3 arranged in the front-to-rear direction, and each row of seats is provided with multiple (e.g., pairs) of seating positions arranged in the width direction of the vehicle. In the example shown in Figure 12, the vehicle's center of gravity CG is located, for example, near the area between the left and right seating positions of the first-row seats S1 (between the driver's seat and the passenger seat). The neutral steering point (NSP) is located behind the center of gravity (CG) and ahead of the axle position of the rear wheels (RW). The longitudinal position of the neutral steering point (NSP) changes, for example, with vehicle speed, and also changes from a transient state (at the start of a turn) to a steady state even at the same vehicle speed.

[0052]

number

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[0053] Furthermore, if the angle θ from the neutral steering point NSP to the seat (occupant) (see Figure 12) is φ, then the following equation 9 holds true.

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[0054] The third gain adjustment unit 200, the fourth gain adjustment unit 210, and the fifth gain adjustment unit 220 sequentially adjust the output gain with respect to the correction term of the excitation waveform output from the second gain adjustment unit 160. The third gain adjustment unit 200 adjusts the output gain (third gain adjustment) according to the distance between the neutral steering point NSP calculated by the neutral steering point calculation unit 170 and the occupant's seating position (especially the position of the head (ears)).

[0055] Figure 13 is a schematic diagram showing an example of gain adjustment in the third gain adjustment section. In Figure 13, the horizontal axis represents the distance between the neutral steering point (NSP) and the occupant's seating position, and the vertical axis represents the gain G3 multiplied by the voltage of the excitation waveform (correction term). The absolute value of the gain G3 increases with increasing absolute value of distance. Furthermore, if the distance is negative (i.e., the occupant is seated further back than the neutral steering point NSP), the gain G3 will be negative. In this case, the acceleration and jerk experienced by the occupants due to the vehicle's yaw motion counteract the acceleration and jerk experienced by the centripetal acceleration during the vehicle's turn. In other words, the acceleration and jerk felt by the occupants are reduced. When the distance between the neutral steering point (NSP) and the occupant's seating position is zero (their positions coincide), the gain G3 becomes zero, and the correction term disappears.

[0056] The fourth gain adjustment unit 210 adjusts the output gain (fourth gain adjustment) according to the angle difference φ (see Figure 12) between the vehicle body slip angle β and the angle θ made by the straight line connecting the neutral steering point NSP and the occupant's seating position with respect to the vehicle body centerline. In Figure 12, occupant P is shown seated, for example, on the left side (passenger seat) of the first-row seat S1. This diagram schematically shows an example of gain adjustment in the fourth gain adjustment section. Figure 14 is a schematic diagram showing an example of gain adjustment in the fourth gain adjustment section. In Figure 14, the horizontal axis represents the angle difference φ, and the vertical axis represents the gain G4 multiplied by the voltage of the excitation waveform (correction term). The gain G4 is maximum when the angle difference φ = 0, and from there it decreases as the absolute value of the angle difference φ increases. When the angle difference φ reaches ±90°, the gain G4 becomes zero.

[0057] The fifth gain adjustment unit 220 adjusts the output gain (fifth gain adjustment) according to the vehicle speed. The fifth gain adjustment unit 220 adjusts the output gain based on the outputs of the vehicle speed sensor 190 and the load sensor 230. The load sensor 230 includes, for example, a stroke sensor that detects the stroke of a suspension device (typically a rear suspension). Based on the output of the load sensor 230, the fifth gain adjustment unit 220 can determine the load condition of the vehicle, such as the number of occupants or the amount of cargo loaded.

[0058] Figure 15 is a schematic diagram showing an example of gain adjustment in the fifth gain adjustment section. In Figure 15, the horizontal axis represents vehicle speed, and the vertical axis represents the gain G5 multiplied by the voltage of the excitation waveform (correction term). The gain G5 is set to decrease as the vehicle speed increases. Furthermore, the gain G5 is provided with multiple maps (diagrams) depending on the vehicle's load condition.

[0059] Figure 16 schematically shows an example of the cornering force characteristics of a tire in response to a change in load. In Figure 16, the horizontal axis represents the tire slip angle, and the vertical axis represents the cornering force CF. Figure 17 schematically shows an example of the cornering power characteristics of a tire in response to changes in load. In Figure 17, the horizontal axis represents the tire slip angle, and the vertical axis represents the cornering power CP. As shown in Figures 16 and 17, the characteristics of the tires differ depending on the load, so the gain G5 map (diagram) shown in Figure 15 is switched appropriately according to the vehicle's load condition detected by the load sensor 230.

[0060] Speaker 240 is a vibration exciter that is placed inside the vehicle and uses the output value A of the excitation waveform after the first to fifth gain adjustments described above to excite the air around the occupants inside the vehicle and generate sound. The speaker 240 may be configured to be shared with, for example, a speaker used for audio playback in a car audio system. Alternatively, a speaker 240 dedicated to the information transmission device 100 may be provided.

[0061] As shown in Figure 12, if each of the first to third row seats has left and right seating positions, the speaker 240 can be configured to have at least six speakers corresponding to each seating position. Each speaker 240 can be a directional speaker directed towards the head (ear area) of an occupant seated in each seating position. The speaker 240 can be configured to be installed, for example, inside interior components of the vehicle interior such as the instrument panel, door trim, and pillar trim, or on the headrest or backrest of a seat positioned directly in front of the occupant. Here, of the gain adjustments described above, the third and fourth gain adjustments are performed independently for each speaker 240, according to the seating position of the occupant that each speaker 240 directs towards. In other words, the amplitude of the excitation waveform in each speaker 240 will differ depending on the seating position of the corresponding occupant.

[0062] According to the first embodiment described above, the following effects can be obtained. (1) By generating sound in which the sound pressure increases in accordance with the increase in the absolute value of the derivative of the steering angle σ of the steering device (so-called steering speed), the occupant P can be made to anticipate the behavior that will occur in the initial stages of steering, prior to the actual occurrence of lateral acceleration, yaw rate, roll angle, etc. in the vehicle, through sound. This improves the occupant P's ability to anticipate the vehicle's behavior and prevents the occupant P from feeling that the vehicle's behavior is sudden. Furthermore, by adjusting the output gain of the excitation waveform according to the relative position between the neutral steering point NSP, which is the rotation center of the yaw motion, and the seating position of the occupant P, it becomes possible to transmit information that appropriately reflects the lateral acceleration and jerk effects experienced by the occupant P due to the vehicle's yaw motion. This suppresses the discrepancy between the acoustic information transmitted to the occupant P by the speaker 240 and the lateral acceleration actually experienced by the occupant, thereby improving the predictability of behaviors caused by vehicle steering, regardless of the seating position in the cabin. In particular, for seats in the second row and beyond, where there is less visual information and the vehicle's behavior is more likely to feel abrupt compared to the first-row seats (S1), it is possible to improve the predictability of vehicle behavior, reduce the feeling of abruptness, and prevent motion sickness. (2) The third gain adjustment unit 200 changes the output gain in accordance with the change in distance between the neutral steering point NSP and the seating position, thereby reflecting the change in acceleration and jerk experienced by the occupant P in accordance with the increase in distance from the neutral steering point NSP to the seating position, and enabling appropriate information to be transmitted to the occupant P. (3) The fourth gain adjustment unit 210 reduces the output gain in accordance with the increase in the angular difference φ between the vehicle body's slip angle β and the angle θ made between the straight line connecting the neutral steering point NSP and the seating position with respect to the vehicle body's centerline in a plan view. This allows for the appropriate estimation of the lateral components of the acceleration and jerk experienced by the occupant P due to the change in the vehicle body's yaw angular acceleration, and enables the transmission of appropriate information to the occupant P. (4) Multiple seating positions are provided, and multiple speakers 240 are provided corresponding to the multiple seating positions. By making the amplitude of the excitation waveform output by the multiple speakers 240 different according to the relative position between the neutral steering point NSP and the seating position, appropriate information can be transmitted to multiple occupants P seated in each of the multiple seating positions according to their seating position. (5) The excitation waveform has a dominant frequency within the 100 to 400 Hz frequency band, making it possible to use Pacinian corpuscles or similar objects that are audible and highly sensitive to tactile sensation, resulting in improved acoustic sound perception and tactile perception by the crew member P. Therefore, information can be reliably transmitted by the crew member P.

[0063] <Second Embodiment> Next, a second embodiment of an information transmission device to which the present invention is applied will be described. In the second embodiment, the vehicle is equipped with an autonomous driving function that performs steering, acceleration, deceleration, and other operations independently, without relying on the driver's operation.

[0064] Figure 18 is a schematic diagram showing the configuration of an automated driving system in a vehicle equipped with the information transmission device of the second embodiment. In addition to the electric power steering control unit 90 described above, the autonomous driving system 300 also includes an autonomous driving control unit 310, an engine control unit 320, a transmission control unit 330, a brake control unit 340, and the like. Each of these units comprises a microcontroller having an information processing unit such as a CPU, a storage unit such as RAM or ROM, an input / output interface, and a bus to connect them. Furthermore, each unit can communicate with one another, either via an in-vehicle LAN such as a CAN communication system, or directly.

[0065] The automated driving control unit 310 recognizes the environment around its vehicle using various sensors such as a stereo camera, millimeter-wave radar, and laser scanner, as well as high-precision 3D maps. The automated driving control unit 310 generates an automated driving scenario that includes information about the vehicle's driving line, speed, etc., based on the recognized environment. The autonomous driving control unit 310 issues instructions to the electric power steering control unit 90, engine control unit 320, transmission control unit 330, and brake control unit 340 based on the autonomous driving scenario, thereby controlling the steering and acceleration / deceleration of the vehicle.

[0066] Instead of receiving steering input from the driver as in the first embodiment, the electric power steering control unit 90 controls the actuator unit 80 in accordance with the requested steering angle instructed by the automatic driving control unit 310 to steer the front wheels FW.

[0067] The engine control unit 320 comprehensively controls the engine and its auxiliary equipment, which are the power source for the vehicle's propulsion. The engine control unit 320 controls the engine output so that the torque actually generated by the engine matches the requested torque instructed by the automatic driving control unit 310.

[0068] The transmission control unit 330 comprehensively controls the transmission and its auxiliary components that change the speed (deceleration or acceleration) of the engine's output shaft rotation. The transmission control unit 330 performs actions such as switching between driving range and non-driving range, switching between forward and reverse, and shifting gears (changing the gear ratio) when moving forward, in response to instructions from the automatic driving control unit 310.

[0069] The brake control unit 340 controls the braking force of the hydraulic service brakes provided on each wheel of the vehicle. The brake control unit 340 adjusts the brake fluid pressure supplied to the wheel cylinders of each wheel in accordance with the required braking force instructed by the automatic driving control unit 310, thereby generating the necessary braking force.

[0070] In the second embodiment, even during autonomous driving when the driver does not perform steering operations, the requested steering angle instruction value transmitted from the autonomous driving control unit 310 to the electric power steering control unit 90 is used as the input to the information transmission device 100 (a parameter correlated with the steering angle of the steering device), and the first gain adjustment is performed based on its derivative value. According to the second embodiment described above, even in a vehicle performing autonomous driving, when steering is initiated by autonomous driving control, the absolute value of the derivative of the steering angle and the sound corresponding to the positional relationship between the neutral steering point (NSP) and the seating position are generated. This makes it possible to predict the occurrence of vehicle behavior accompanied by lateral acceleration, yaw rate, roll angle, etc., and prevents the occupant from feeling that the vehicle's behavior is sudden.

[0071] (modified version) The present invention is not limited to the embodiments described above, and various modifications and changes are possible, all of which fall within the technical scope of the present invention. (1) The configuration of the information transmission device and the vehicle is not limited to the embodiments described above and can be modified as appropriate. For example, the number and arrangement of seating positions in the vehicle interior, and the corresponding speaker placement, can be appropriately modified from the configuration of the embodiment. Furthermore, the hardware configuration of the information transmission device and the specific method for adjusting the gain (amplitude change) of the excitation waveform are not limited to the configuration of each embodiment and can be modified as appropriate. (2) In each embodiment, for example, the steering angle (actual steering angle detected by the steering angle sensor, or the requested steering angle in the automatic driving control) is used as a parameter that correlates with the steering amount of the steering device, but this parameter is not limited to this and can be changed as appropriate. For example, the system can be configured to include at least one of the following: steering torque (input torque) input from the driver, the amount of operation of an actuator that steers the wheels (for example, the amount of rotation of a motor), and an output instruction value to the actuator. (3) The present invention is not limited to vehicles in which an operating member such as a steering wheel and a steering mechanism such as a steering gearbox are mechanically connected, as in each embodiment, but can also be applied to vehicles having a steer-by-wire type steering system in which the steering wheel and the steering mechanism are not mechanically connected. In this case, parameters that correlate with the amount of steering of the steering system can be used, such as the actual steering angle of the front wheels or the state of the steering mechanism (for example, the rotational angle position of the pinion gear or the amount of movement of the rack axis). (4) In each embodiment, the ambient noise level of the vehicle is acquired by a microphone as an example, but the ambient noise level may be acquired by other methods. For example, the ambient noise level may be estimated based on the acceleration of the unsprung portion of the vehicle which correlates with input from the road surface, or the output value of the torque sensor of the steering system (torsion bar torque). [Explanation of symbols]

[0072] 1. Electric power steering system W wheels 10 Steering Wheel 20 Steering Shaft 21 Intermediate shaft 22 Pinion shaft 23, 24 Universal joint 30 Rack shaft 31 Rack gear 40 Rack housing 41 Rack boot 50 Tie rod 51, 52 Ball joint 60 Housing 71 Steering angle sensor 72 Torque sensor 80 Actuator unit 81 Motor 82 Gearbox 90 Electric Power Steering Control Unit 100 Information transmission device 110 Waveform generation unit 120 Differential calculation unit 130 First gain adjustment unit 140 Microphone 150 Sensing Value Calculation Unit 160 Second Gain Adjustment Section 170 Neutral Stair Point Calculation Unit 180 Yaw rate sensor 190 Vehicle speed sensor 200 Third gain adjustment section 210 Fourth gain adjustment section 220 Fifth gain adjustment unit 230 Load sensor 240 speakers 300 Autonomous driving system 310 Autonomous driving control unit 320 Engine control unit 330 Transmission control unit 340 Brake control unit

Claims

1. An information transmission device installed in a vehicle having a steering system for steering the wheels, A parameter detection unit that detects parameters correlated with the steering amount of the steering device, A vibration unit that vibrates the air around the occupant using a predetermined vibration waveform in response to changes in the parameters of the steering device, A rotation center calculation unit that calculates the position of the rotation center of the vehicle's yaw motion, A gain adjustment unit adjusts the output gain of the excitation waveform according to the relative position between the pivot center and the seated position of the occupant. An information transmission device characterized by being equipped with the following features.

2. The gain adjustment unit changes the output gain in accordance with the change in the distance between the pivot center and the seating position. The information transmission device according to claim 1, characterized by the following:

3. The gain adjustment unit reduces the output gain in accordance with the increase in the angular difference between the vehicle body's slip angle and the angle formed by the straight line connecting the pivot center and the seating position with respect to the vehicle body's centerline in a plan view. An information transmission device according to claim 1 or claim 2, characterized by the above.

4. Multiple seating positions are provided. The vibration excitation section is provided in multiple locations corresponding to the multiple seating positions. The amplitude of the excitation waveform output by the multiple excitation units is made different according to the relative position between the rotation center and the seating position. An information transmission device according to claim 1 or claim 2, characterized by the above.

5. The excitation waveform has a dominant frequency that falls within the frequency band of 100 to 400 Hz. An information transmission device according to claim 1 or claim 2, characterized by the above.

6. The vehicle is equipped with an automatic driving control unit that instructs the steering device on the amount of steering, The parameter that correlates with the steering amount of the steering device is the value instructed by the automatic driving control unit. An information transmission device according to claim 1 or claim 2, characterized by the above.

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