Information presentation device

Abstract

[Problem] To provide an information presentation device with which the recognizability of information relating to a steering angle is improved even when a steering gear ratio is variable. [Solution] An information presentation device 200 provided to a vehicle having a steering device in which the steering gear ratio changes as the wheels are steered is configured to comprise a steering operation amount detection unit 112 that detects an amount of steering operation performed by a driver, a steering gear ratio detection unit 10 that detects a steering gear ratio, an excitation waveform generation unit 210 that generates an excitation waveform, an excitation unit 270 that excites at least one of air around an occupant and a component in contact with the occupant using the excitation waveform, and a gain adjustment unit 230 that increases an output gain of the excitation waveform in accordance with an increase in the absolute value of a differential value of the product of the steering operation amount and a reciprocal of the steering gear ratio.

Description

Information presentation device

[0001] The present invention relates to an information presentation device that presents information about the behavior of a vehicle to a vehicle occupant.

[0002] As a technology related to outputting audio to occupants of a vehicle such as an automobile according to the vehicle's state, for example, Patent Document 1 describes a driving assistance device that provides an easy-to-recognize steering angle and steering direction, in which the steering amount of a steering wheel is indicated by a sound that changes in conjunction with the steering amount. Specifically, it describes controlling the pitch of the sound so that it becomes higher as the steering amount increases, and indicating the steering amount of the steering wheel by changing the volume, pitch, tone, sound pressure, frequency, position of the sound image, etc. Patent Document 2 describes a vehicle music generation device that easily generates music that reflects the vehicle behavior and driver operation, and includes a storage unit that stores multiple sound source loop patterns each corresponding to information based on the vehicle driver's operation or vehicle behavior, and a control unit that selects a specific sound source loop pattern from the multiple sound source loop patterns according to the information and controls output or stop of the output.

[0003] JP 2007-62706 A JP 2016-66912 A

[0004] Vehicles with a variable steering gear ratio (the deceleration rate of the front wheel steering angle relative to the steering wheel angle) can adjust the gear ratio to suit the situation by adjusting it according to the steering angle range and vehicle speed. For example, a small, quick gear ratio can be used at low vehicle speeds to achieve maneuverability and a nimble feel. On the other hand, a large, slow gear ratio can be used at high vehicle speeds to achieve high stability and stable vehicle performance. However, on slippery roads with snow and ice, erratic behavior (such as skidding or spinning) is likely to occur at low speeds. In such cases, corrective steering, such as countersteering, is necessary to control the vehicle's behavior. In such cases, a vehicle with a quick gear ratio set at low vehicle speeds requires fine control of the steering wheel's operational resolution, which can make driving more difficult. While a slow gear ratio can be used to address this issue, the inherent benefits of a variable gear ratio are lost. While it is also possible to flexibly change the gear ratio based on vehicle behavior, this reduces the reproducibility of vehicle behavior depending on the steering angle, causing the driver to feel uneasy. In view of the above-mentioned problems, an object of the present invention is to provide an information display device that improves the recognizability of information related to steering angle even when the steering gear ratio is variable.

[0005] In order to solve the above-mentioned problems, an information presentation device according to one aspect of the present invention is an information presentation device provided in a vehicle having a steering device in which a steering gear ratio changes as the wheels are steered, the information presentation device comprising: a steering operation amount detection unit that detects a steering operation amount by a driver; a steering gear ratio detection unit that detects the steering gear ratio; an excitation waveform generation unit that generates an excitation waveform; a vibration unit that uses the excitation waveform to vibrate at least one of the air around the occupant and a part in contact with the occupant; and a gain adjustment unit that increases an output gain of the excitation waveform in accordance with an increase in the absolute value of a derivative of a value obtained by multiplying the steering operation amount by the reciprocal of the steering gear ratio. According to this, by generating a sound whose sound pressure increases in accordance with an increase in the absolute value of a derivative of a parameter correlated with the steering amount of the steering device (so-called steering speed), it is possible to predict the occurrence of a behavior of the vehicle by the sound at an early stage of steering before the lateral acceleration, yaw rate, roll angle, etc. actually occur in the vehicle. This improves occupants' predictability of vehicle behavior and prevents them from experiencing abruptness in vehicle behavior. Furthermore, by increasing the output gain of the excitation waveform in accordance with an increase in the absolute value of the differential value of the steering operation amount multiplied by the reciprocal of the steering gear ratio, occupants can properly grasp information about the actual steering amount (steering angle) of the steered wheels, even in vehicles with a variable steering gear ratio. Furthermore, by generating an excitation waveform in accordance with driving operations, the driver can recognize the operation amount with a finer resolution than the driver's inherent steering angle resolution, enabling more precise control. For example, controllability is improved even when the steering gear ratio is set to a quick setting, making driving easier.

[0006] In the present invention, the excitation waveform may have a dominant frequency within a frequency range of 100 to 400 Hz. This allows the use of Pacinian corpuscles, which are in the audible range and highly sensitive to cutaneous sensation, and improves the occupant's perception of sound and cutaneous sensation. This allows for more reliable transmission of information to the occupant. More preferably, the dominant frequency is set within a frequency range of 150 to 300 Hz, thereby utilizing a region with higher receptor sensitivity and enhancing the above-mentioned effects.

[0007] In the present invention, the gain adjustment unit may be configured to set the output gain so that the sound pressure generated by the vibration of the vibration unit does not become dominant at the ear of at least one occupant relative to background noise while the vehicle is running. This prevents the sound generated by the vibration of the vibration unit from being drowned out by background noise of the vehicle, which may cause the occupant to feel uncomfortable, and allows information to be transmitted appropriately.

[0008] The present invention may further include an internal tire pressure detection unit that detects the tire pressure of the wheel, and the gain adjustment unit may be configured to increase the output gain in response to an increase in the tire pressure. The steering torque gradient of a vehicle changes depending on the level of tire pressure. Because the driver determines the amount of steering wheel operation based on the steering torque gradient in addition to the steering angle, changes in this torque gradient can make driving difficult. According to the present invention, by adjusting the output gain of the vibration waveform of the information presentation device based on the tire pressure monitoring results, it is possible to suppress changes in the torque gradient felt by the driver and ensure ease of driving.

[0009] The present invention may include a low visibility condition detection unit that detects a low visibility condition around the vehicle, and the gain adjustment unit may be configured to increase the output gain in response to the detection of the low visibility condition. When a person drives, vision is the primary source of information, and the person relies on vision. The person drives by supplementing vision with hearing and touch, recognizing, making decisions, and operating the vehicle repeatedly. According to the present invention, in consideration of the fact that the degree of reliance on the auxiliary senses of hearing and touch increases in conditions of poor visibility, the output gain of the vibration waveform of the information presentation device can be increased to increase the amount of information obtained from hearing and touch, thereby ensuring ease of driving.

[0010] As described above, according to the present invention, it is possible to provide an information display device that improves the recognizability of information relating to steering angle even when the steering gear ratio is variable.

[0011] 1 is a diagram schematically showing a system configuration of a vehicle having an embodiment of an information presentation device to which the present invention is applied; FIG. 2 is a diagram schematically showing a configuration of a steering device of a vehicle having an information presentation device of an embodiment; FIG. 3 is a diagram schematically showing an example of a correlation between vehicle speed and a steering gear ratio; FIG. 4 is a diagram schematically showing an example of a correlation between a steering angle and a steering gear ratio; FIG. 5 is a diagram schematically showing a system configuration of an information presentation device of an embodiment; FIG. 6 is a diagram schematically showing an example of an excitation waveform in an embodiment; FIG. 7 is a diagram schematically showing the timing of an electrical pulse emitted by a receptor when stimulated; FIG. 8 is a diagram showing the frequency sensitivity distribution of Pacinian corpuscles and Meissner corpuscles; FIG. 9 is a diagram schematically showing an example of gain adjustment in a first gain adjustment unit; FIG. 10 is a diagram schematically showing an example of an output history of a microphone; FIG. 11 is a diagram showing an example of a correlation between the sound pressure of background noise and the frequency; FIG. 12 is a diagram schematically showing an example of gain adjustment in a second gain adjustment unit; FIG. 13 is a diagram schematically showing an arrangement in a passenger compartment of a vehicle in which an information presentation device of an embodiment is provided.

[0012] An embodiment of an information presentation device to which the present invention is applied will be described below. The information presentation device of the embodiment is installed in a vehicle such as a four-wheeled passenger car. Fig. 1 is a diagram schematically showing the system configuration of a vehicle having the information presentation device of the embodiment.

[0013] As shown in Fig. 1, a vehicle 1 includes a steering control unit 10, a tire pressure monitoring device 20, an environment recognition unit 30, an information presentation device 200, etc. The steering control unit 10 comprehensively controls a steering device 100, which is a steer-by-wire steering system. The configuration of the steering device 100 will be described in detail later.

[0014] The tire pressure monitoring device 20 is a device (internal pressure detection unit) that monitors the internal pressure (air pressure) of the tires of the vehicle 1. The tire pressure monitoring device 20 includes, for example, a communication device that receives information wirelessly transmitted from an internal pressure sensor provided on a tire valve cap or the like.

[0015] The environment recognition unit 30 is a device that recognizes the environment around the vehicle using various sensors. The environment recognition unit 30 is connected to, for example, a stereo camera device 31, an illuminance sensor 32, a rainfall sensor 33, and the like. The stereo camera device 31 is an imaging device having a pair of stereo cameras installed facing the front of the vehicle. The illuminance sensor 32 is a sensor that detects the illuminance around the vehicle. The rainfall sensor 33 is a sensor that detects rainfall conditions based on, for example, vibrations of the front windshield. The environment recognition unit 30 is capable of recognizing a state in which visibility around the vehicle is reduced based on the output of each sensor. The environment recognition unit 30 functions as a low visibility condition detection unit that detects low visibility conditions around the vehicle in cooperation with each sensor.

[0016] The information presentation device 200 is a device that presents information to the occupant by sound based on the behavior of the steering device 100. The configuration of the information presentation device 200 will be described in detail later.

[0017] The vehicle has a steering device 100, which will be described below, for steering the front right wheel FWR and front left wheel FWL, which are steered wheels. Fig. 2 is a diagram schematically showing the configuration of the steering device of a vehicle having an information presentation device according to an embodiment. As shown in Fig. 2, the steering device 100 is an electric steer-by-wire type that includes a steering wheel 110, a reaction force generator 120, a rack shaft 130, a rack housing 140, a tie rod 150, a housing 160, an actuator unit 170, etc.

[0018] The steering wheel 110 is an annular operating member (steering input unit) that is rotated by the driver to input steering operations. The steering wheel 110 is disposed opposite the driver's seat in the vehicle cabin. The steering wheel 110 is provided with a steering shaft 111, a steering wheel angle sensor 112, and a torque sensor 113.

[0019] The steering shaft 111 is a rotating shaft with one end attached to the steering wheel 110. The steering wheel angle sensor 112 is provided in the middle of the steering shaft 111 and is a steering operation amount detection unit that detects the rotation angle position of the steering shaft 111 (the amount of operation by the driver). The torque sensor 113 is provided in the middle of the steering shaft 111 in an area closer to the reaction force generating device 120 than the steering wheel angle sensor 112 and detects the torque applied to the steering shaft 111 (the operating force or holding force of the steering wheel 110 by the driver). The outputs of the steering wheel angle sensor 112 and the torque sensor 113 are transmitted to the steering control unit 10. The steering control unit 10 controls the output of the motor 171 of the actuator unit 170 in accordance with the outputs of the steering wheel angle sensor 112 and the torque sensor 113.

[0020] The reaction force generating device 120 has an actuator that applies torque to the steering shaft 111 to generate a pseudo steering reaction force in response to a command from the steering control unit 10. The output shaft of the reaction force generating device 120 is connected to the end of the steering shaft 111 on the opposite side to the steering wheel 110 side.

[0021] The rack shaft 130 is a columnar member arranged with its longitudinal direction (axial direction) aligned with the vehicle width direction. The rack shaft 130 is supported on the vehicle body so as to be able to translate in the vehicle width direction. A rack gear 131 that meshes with a pinion gear of a pinion shaft 173 is formed on a part of the rack shaft 130. In response to rotation of the steering shaft 120, the rack gear 131 is driven by the pinion gear, causing the rack shaft 130 to translate (move straight) along the vehicle width direction.

[0022] The rack housing 140 is a substantially cylindrical member that houses and supports the rack shaft 130 so that it can be relatively displaced in the vehicle width direction. The rack housing 140 constitutes a steering gearbox in cooperation with the rack shaft 130, the pinion shaft 173, etc. Rack boots 141 are provided on both ends of the rack housing 140. The rack boots 141 are members that prevent foreign matter such as dust from entering the rack housing 140 while allowing relative displacement of the tie rod 150 with respect to the rack housing 140. The rack boots 141 are formed in a flexible bellows-like shape from a resin-based material such as elastomer.

[0023] The tie rod 150 is a shaft-shaped interlocking member that connects the end of the rack shaft 130 and a knuckle arm 161 of the housing 160 and rotates the housing 160 about the kingpin axis in conjunction with the translational movement of the rack shaft 130. The inner end of the tie rod 150 in the vehicle width direction is swingably connected to the end of the rack shaft 130 via a ball joint 151. The outer end of the tie rod 150 in the vehicle width direction is connected to the knuckle arm 161 of the housing 160 via a ball joint 152. A turnbuckle mechanism (not shown) for toe-in adjustment is provided at the connection between the tie rod 150 and the ball joint 152.

[0024] The housing (knuckle) 160 is a member that houses hub bearings that support hubs to which the right front wheel FWR and the left front wheel FWL are attached so that they can rotate about the axle. The housing 160 has a knuckle arm 161 that protrudes forward from the axle. The housing 160 is supported so that it can rotate about a kingpin axis, which is a predetermined rotation center axis. The housing 160 is pushed and pulled in the vehicle width direction by the rack shaft 130 via the tie rod 150, so that it rotates about the kingpin axis and steers the right front wheel FWR and the left front wheel FWL.

[0025] The actuator unit 170 is a drive device that rotates and drives the pinion shaft 173 to generate rack thrust and perform steering operation. The actuator unit 170 is configured to include a motor 171, a gearbox 172, a pinion shaft 173, etc. The motor 171 is an electric actuator that generates driving force to be applied to the pinion shaft 173. The rotation direction and output torque of the motor 171 are controlled by the steering control unit 10. The output shaft angular position (rotation angle) of the motor 171 is configured to be fed back to the steering control unit 10. The gearbox 172 is equipped with a reduction gear train that reduces the rotation output of the motor 171 (torque amplification) and transmits it to the pinion shaft 173. The pinion shaft 173 is a rotating shaft that is rotated and driven by the motor 171 via the gearbox 172. A pinion gear that meshes with the rack gear 131 of the rack shaft 130 to drive the rack shaft 130 is formed at the tip of the pinion shaft 173.

[0026] The steering device 100 is a steer-by-wire type with a variable steering gear ratio. The steering control unit 10 has a function of changing the steering gear ratio by changing the correlation between the rotation angle (steering wheel angle) of the steering wheel 110 detected by the steering wheel angle sensor 112 and the actual steering angle of the front wheels. The steering gear ratio is the ratio of the change in steering wheel angle to the change in actual steering angle, and the smaller the value, the quicker the steering, and the larger the change in actual steering angle when the steering wheel angle is the same.

[0027] Fig. 3 is a diagram showing an example of the correlation between vehicle speed and steering gear ratio. In Fig. 3, the horizontal axis represents vehicle speed, and the vertical axis represents steering gear ratio. As shown in Fig. 3, the steering gear ratio is set small in the low speed range, providing quick characteristics. On the other hand, the steering gear ratio is set to increase as the vehicle speed increases, providing a slow setting to ensure vehicle stability.

[0028] Fig. 4 is a diagram showing an example of the correlation between the steering angle and the steering gear ratio. In Fig. 4, the horizontal axis represents the steering angle (steering wheel angle), and the vertical axis represents the steering gear ratio. As shown in Fig. 4, the steering gear ratio is set to be large in a range where the steering wheel angle is small, and set to be small in a range where the steering wheel angle is large. The steering control unit 10 is provided with a map created based on the trends shown in Figs. 3 and 4, and successively changes the steering gear ratio of the steering device 100 in accordance with the running state of the vehicle.

[0029] 5 is a diagram illustrating a system configuration of an information presentation device according to an embodiment. The information presentation device 200 vibrates the air around the ears of occupants using a speaker 270 disposed in the vehicle cabin, thereby notifying the occupants of an impending vehicle behavior by means of an acoustic signal. The information presentation device 200 includes a waveform generation unit 210, a differential calculation unit 220, a first gain adjustment unit 230, a microphone 240, a sensing value calculation unit 250, a second gain adjustment unit 260, the speaker 270, and the like.

[0030] The waveform generating unit 210 generates an excitation waveform, which is the waveform of the acoustic signal generated by the speaker 270. FIG. 6 is a diagram schematically illustrating an example of an excitation waveform in an embodiment. In FIG. 6, the horizontal axis represents time, and the vertical axis represents voltage (amplitude). For example, as shown in FIG. 6( a), the excitation waveform can be a sine wave. Furthermore, as shown in FIG. 6( b), the excitation waveform can be a waveform in which multiple sine waves with different wavelengths are superimposed (combined). Furthermore, the excitation waveform is not limited to these and can be changed as appropriate. For example, various waveforms such as a square wave, a triangular wave, and a waveform simulating the sound of a vehicle running can be used alone or combined with other waveforms as the excitation waveform.

[0031] In an embodiment, the frequency of the vibration 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 for this is explained below. When the air around the occupant is vibrated, sensory receptors that detect vibrations include Merkel cells, Meissner's corpuscles, and Pacinian corpuscles. Figure 7 is a diagram schematically showing the timing of electrical pulses emitted by receptors when stimulated. In Figure 7, the horizontal axis represents time, and the vertical axis represents, from top to bottom, pressure and the electrical pulse generation state of Merkel cells, Meissner's corpuscles, and Pacinian corpuscles.

[0032] Merkel cells have a relatively slow response and correspond to direct current components. Meissner's corpuscles respond when there is a rate of change (speed) of contact pressure. Pacinian corpuscles respond to moments of transient change and are said to be the most sensitive of these receptors. Pacinian corpuscles are thought to have the best sensitivity as receptors that allow passengers to perceive minute vibrations as combined auditory and tactile information.

[0033] Figure 8 shows the frequency sensitivity distribution of Pacinian corpuscles and Meissner corpuscles. In Figure 8, the horizontal axis represents frequency and the vertical axis represents amplitude above threshold, with smaller values ​​indicating better sensitivity. As shown in Figure 8, Pacinian corpuscles exhibit good sensitivity in the range of approximately 100 to 400 Hz, and even better sensitivity in the range of 150 to 300 Hz. This range is included in the range of 20 Hz to 20 kHz, which is generally considered to be the human audible range. The dominant frequency of the excitation waveform can be set to 250 Hz, for example.

[0034] The differential calculation unit 220 receives from the steering control unit 10 the rotation angle (steering wheel angle) θ of the steering wheel 110 detected by the steering wheel angle sensor 112. Ｈ and the current steering gear ratio R ＳＴＧ The differential calculation unit 220 first obtains information about the steering wheel angle θ Ｈ Steering gear ratio R ＳＴＧ (steering wheel angle θ Ｈ steering gear ratio R ＳＴＧ The steering control unit 10 functions as a steering gear ratio detector of the present invention. Ｈ / Steering gear ratio R ＳＴＧ = front wheel actual steering angle θ The differential calculation unit 220 calculates a differential value Δθ by time-differentiating the front wheel actual steering angle θ The differential calculation unit 220 sequentially transmits the calculated differential value Δθ to the first gain adjustment unit 230.

[0035] The first gain adjustment unit 230 performs the first gain adjustment, which will be described below, on the fundamental wave of the excitation waveform generated by the waveform generation unit 210. The first gain adjustment changes the gain G1, which is the output gain by which the voltage of the excitation waveform is multiplied, in accordance with the differential value (rate of change per time) of the actual steering angle θ of the front wheels in the steering device 100 (a parameter correlated with the steering amount).

[0036] 9 is a diagram schematically illustrating an example of gain adjustment in the first gain adjustment unit. In FIG. 9, the horizontal axis represents the absolute value of the derivative value Δθ of the steering angle θ of the wheel FW, and the vertical axis represents the gain G1 by which the voltage of the excitation waveform is multiplied. The gain G1 can be configured to increase as the absolute value of the derivative value Δθ increases. Furthermore, the rate of increase of the gain G1 relative to the increase in the absolute value of the derivative value Δθ in the first gain adjustment unit 230 can be configured to be maximum in a region where the absolute value of the derivative value Δθ is small, and to decrease as the absolute value of the derivative value Δθ increases.

[0037] The gain G1 in the first gain adjustment unit 230 can be calculated, for example, from the absolute value of the differential value Δθ of the steering angle θ using a logarithmic function. The gain G1 is expressed, for example, by the following equation 1. Gain G1=log(absolute value of steering angle differential value Δθ×coefficient k) (Equation 1) The coefficient k can be a value set, for example, during the development stage of the vehicle, in accordance with the characteristics of the vehicle (for example, yaw gain with respect to the steering angle θ, center of gravity position, etc.).

[0038] Furthermore, the coefficient k is corrected in accordance with the outputs of the tire pressure monitoring device 20 and the environment recognition unit 30. In accordance with an increase in tire pressure detected by the tire pressure monitoring device 20, the coefficient k is increased.

[0039] Furthermore, when the environment recognition unit 30 recognizes that the visibility around the vehicle has deteriorated, the coefficient k is corrected to be increased. For example, when the stereo camera device 31 recognizes a poor visibility state such as fog or backlight, when the illuminance sensor 32 recognizes a predetermined dark environment such as nighttime or inside a tunnel, or when the rainfall sensor 33 detects rain, it is determined that the visibility around the vehicle has deteriorated, and the coefficient k is corrected to be increased.

[0040] The microphone 240 is a sound collecting device provided in the vehicle cabin to collect background noise within the vehicle cabin. The microphone 240 is preferably disposed in a position close to the ears of the occupants, and may be provided, for example, in the headrest of the seat. The output of the microphone 240 is transmitted to the sensing value calculation unit 250.

[0041] The sensing value calculation unit 250 extracts components in a predetermined frequency band from the background noise of the vehicle acquired by the microphone 240, and transmits the sound pressure of the extracted components as a sensing value to the second gain adjustment unit 260. Fig. 10 is a diagram schematically showing an example of the microphone output history. In Fig. 10, the horizontal axis represents time, and the vertical axis represents the sound pressure of the background noise acquired by the microphone 240.

[0042] The sensing value calculation unit 250 performs fast Fourier transform (FFT) processing on the acoustic signal of the background noise acquired by the microphone 240 to convert it into the frequency domain, and further performs band-pass filtering to extract components of a predetermined frequency band. The frequency band to be extracted is set so as to include the dominant frequency of the excitation waveform output by the waveform generation unit 210. The sensing value calculation unit 250 sets the average sound pressure of the extracted frequency band as a sensing value to be used for the second gain adjustment.

[0043] Fig. 11 is a diagram showing an example of the correlation between the sound pressure of background noise and frequency. In Fig. 11, the horizontal axis represents frequency and the vertical axis represents sound pressure. The band-pass filter can be configured to extract a frequency band near the dominant frequency (e.g., 250 Hz) of the excitation waveform in the waveform generating unit 210. The sound pressure in the extracted frequency band (e.g., the average value of the frequency band) is provided to the second gain adjusting unit 260 as a sensing value.

[0044] The second gain adjustment unit 260 further performs a second gain adjustment, which will be described below, on the excitation waveform after the first gain adjustment. The second gain adjustment changes the gain of the excitation waveform according to the sensed value of the cabin noise in order to adjust the output amplitude of the excitation waveform according to changes in background noise (drivetrain noise, aerodynamic noise, road noise, etc.) while the vehicle is running. The second gain adjustment unit 260 performs the second gain adjustment based on the output of the sensing value calculation unit 250.

[0045] The second gain adjustment unit 260 sets the gain G2 based on the sensing value output by the sensing value calculation unit 250. FIG. 12 is a diagram schematically illustrating an example of gain adjustment in the second gain adjustment unit. In FIG. 12, the horizontal axis represents the sensing 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 as the sensing value increases. The gain G2 is set so that the sound pressure of the sound generated by the excitation amplitude output from the speaker 270 does not dominate over the sound pressure of background noise near the ears of the occupants. Preferably, the gain G2 is set so that the sound generated by the excitation amplitude blends in with the background noise of the vehicle and reaches a sound pressure level that the occupants can unconsciously hear.

[0046] The output value (voltage) A of the vibration waveform after the first gain adjustment and the second gain adjustment described above is expressed as in Equation 2. Output value A = Waveform generator output value × Gain G1 × Gain G2 = Waveform generator output value × log (absolute value of steering angle differential value Δθ × coefficient k) × Gain G2 (Equation 2)

[0047] The speaker 270 is a vibration device disposed in the vehicle cabin that uses the output value A to vibrate the air around the occupants in the vehicle cabin and generate sound. The placement of the speaker 270 will be described in detail later. The speaker 270 may be configured to be shared with a speaker used for audio playback of an in-vehicle audio device, for example. Alternatively, a dedicated speaker 270 may be provided for the information presentation device 200.

[0048] 13 is a diagram illustrating the layout of a vehicle interior in which the information presentation device according to the embodiment is installed. Inside the vehicle interior 300, a driver's seat 310, a passenger seat 320, a rear seat 330, an instrument panel 340, and the like are provided.

[0049] The driver's seat 310 and the passenger seat 320 are front seats located at the front of the vehicle cabin. The driver's seat 310 and the passenger seat 320 are arranged side by side in the vehicle width direction. In the example shown in Fig. 13, the vehicle is, as an example, a so-called right-hand drive vehicle, and the driver's seat 310 is located on the right side and the passenger seat 320 is located on the left side with respect to the center of the vehicle body. The driver's seat 310 and the passenger seat 320 each have a cushion portion on which the occupant's buttocks and thighs are placed, a seatback portion located behind the occupant's back, and a headrest portion located behind the occupant's head.

[0050] The rear seat 330 is a bench-like seat located behind the driver's seat 310 and the passenger seat 320. The rear seat 330 can accommodate, for example, two passengers sitting side by side. The rear seat 330 has a cushion portion on which the passenger's buttocks and thighs are placed, a seatback portion located behind the passenger's back, and a headrest portion located behind the passenger's head. The right seating portion of the rear seat 330 is located behind the driver's seat 310, and the left seating portion is located behind the passenger seat 320.

[0051] The instrument panel 340 is provided near the front end of the vehicle interior 300 and houses, for example, an instrument panel, a ventilation / air-conditioning / heating system, an infotainment system, etc. The instrument panel 340 is disposed to face the occupants seated in the driver's seat 310 and the passenger seat 320.

[0052] 13, for example, four speakers 270 are provided spaced apart from each other at the front, rear, left and right sides of the vehicle interior 300. In the following description, the reference numerals of the speakers 270 will be given with subscripts corresponding to their positions.

[0053] The right front speaker 270FR is disposed near the right end of the instrument panel 340. The speaker 270FR is a directional speaker that is directed toward the head (ear) of an occupant seated in the driver's seat 310. The left front speaker 270FL is disposed near the left end of the instrument panel 340. The speaker 270FL is a directional speaker that is directed toward the head (ear) of an occupant seated in the passenger seat 320.

[0054] The right rear speaker 270RR is disposed in the headrest of the driver's seat 310. The speaker 270RR is a directional speaker that is directed toward the head (ear) of an occupant seated on the right side of the rear seat 330. The left rear speaker 270RL is disposed in the headrest of the passenger seat 320. The speaker 270RL is a directional speaker that is directed toward the head (ear) of an occupant seated on the left side of the rear seat 330.

[0055] In this embodiment, with the above configuration, when the driver performs a steering operation and a change in the steering angle θ of the wheels W occurs, a sound having an amplitude corresponding to the differential value Δθ of the steering angle θ is emitted to the occupants from the speaker 270. This sound is masked by the sound of the vehicle traveling (background noise), and therefore is difficult for the occupants to consciously recognize as sound, but it allows the occupants to unconsciously predict the occurrence of vehicle behavior accompanied by the generation of lateral acceleration or yaw rate.

[0056] According to the embodiment described above, the following effects can be obtained. (1) By generating a sound whose sound pressure increases in response to an increase in the absolute value of the differential value (so-called steering speed) of a parameter correlated with the steering amount of the steering device 100, the sound can allow the occupant to predict the occurrence of a behavior in the vehicle 1 before the actual occurrence of lateral acceleration, yaw rate, roll angle, or the like in the early stages of steering. This improves the occupant's predictability of the vehicle behavior, preventing the occupant from feeling abrupt about the behavior of the vehicle 1. Furthermore, by increasing the output gain of the excitation waveform in response to an increase in the absolute value of the differential value of the steering operation amount multiplied by the reciprocal of the steering gear ratio, the occupant can appropriately grasp information about the actual steering angles of the right front wheel FWR and the left front wheel FWL, even in a vehicle 1 with a variable steering gear ratio. Furthermore, by generating an excitation waveform in response to a driving operation, the driver can recognize the operation amount in a finer range than the driver's inherent steering angle resolution, enabling more precise control. For example, even when the steering gear ratio is set to a quick setting, controllability is improved, making driving easier. (2) The excitation waveform has a dominant frequency in the 100 to 400 Hz frequency band, enabling the use of Pacinian corpuscles, which are highly sensitive to audible sounds and cutaneous sensations, improving occupant perception of acoustic sounds and cutaneous sensation. This allows for more reliable information transmission to occupants. (3) By setting the output gain so that the sound pressure generated by the vibration of the vibration unit does not dominate the background noise of the vehicle 1 at the ear of at least one occupant, the sound generated by the vibration of the vibration unit is prevented from being drowned out by the background noise of the vehicle 1, which would cause the occupant to feel uncomfortable, and information can be transmitted appropriately. (4) By adjusting the output gain of the excitation waveform of the information display device based on the tire pressure monitoring results, the change in the torque gradient felt by the driver can be suppressed, ensuring ease of driving. (5) Considering that drivers rely more heavily on auxiliary hearing and tactile senses in poor visibility conditions, increasing the output gain of the excitation waveform of the information display device increases the amount of information obtained through hearing and tactile senses, ensuring ease of driving.

[0057] (Modifications) The present invention is not limited to the above-described embodiments, and various modifications and variations are possible, and these are also within the technical scope of the present invention. (1) The specific configurations of the information presentation device and the vehicle are not limited to those of the above-described embodiments, and can be modified as appropriate. (2) In the embodiments, the excitation waveform is presented to the occupant as acoustic information via a speaker. However, instead of or in addition to this, a configuration may be adopted in which a member that the occupant comes into contact with is vibrated to present information to the occupant as tactile vibration. (3) In the embodiments, the steering device is a steer-by-wire type as an example, but the present invention can also be applied to steering devices with variable steering gear ratios other than steer-by-wire types.

[0058] REFERENCE SIGNS LIST 1 vehicle 10 steering control unit 20 tire pressure monitoring device 30 environment recognition unit 31 stereo camera device 32 illuminance sensor 33 rainfall sensor FWR right front wheel FWL left front wheel 100 steering device 110 steering wheel 111 steering shaft 112 steering wheel angle sensor 113 torque sensor 120 reaction force generator 130 rack shaft 131 rack gear 140 rack housing 141 rack boot 150 tie rod 151 ball joint 152 ball joint 160 housing 161 knuckle arm 170 actuator unit 171 motor 172 gearbox 173 pinion shaft 200 information presentation device 210 waveform generation unit 220 differential calculation unit 230 first gain adjustment unit 240 microphone 250 Sensing value calculation unit 260 Second gain adjustment unit 270 Speaker 300 Vehicle interior 310 Driver's seat 320 Passenger seat 330 Rear seat 340 Instrument panel

Claims

1. An information presentation device provided in a vehicle having a steering device that steers wheels and changes the steering gear ratio, a steering operation amount detection unit that detects the steering operation amount by the driver, a steering gear ratio detection unit that detects the steering gear ratio, a parameter calculation unit that calculates a parameter correlated with the steering operation amount and the steering gear ratio, a vibration waveform generation unit that generates a vibration waveform, a vibration unit that vibrates at least one of the air around the occupant and the components in contact with the occupant using the vibration waveform, and a gain adjustment unit that increases the output gain of the vibration waveform in accordance with an increase in the absolute value of the derivative value of the parameter characterized by comprising an information presentation device.

2. The parameter is a value obtained by multiplying the steering operation amount by the reciprocal of the steering gear ratio The information presentation device according to claim 1, characterized in that.

3. The vibration waveform has a dominant frequency included in a frequency band of 100 to 400 Hz The information presentation device according to claim 1 or claim 2, characterized in that.

4. The gain adjustment unit sets the output gain so that the sound pressure generated by the vibration of the vibration unit does not dominate the ambient noise during running of the vehicle at the ears of at least one occupant The information presentation device according to claim 1 or claim 2, characterized in that.

5. comprising an internal pressure detection unit that detects the tire internal pressure of the wheel, The gain adjustment unit increases the output gain in accordance with an increase in the tire internal pressure The information presentation device according to claim 1 or claim 2, characterized in that.

6. It is provided with a low visibility state detection unit that detects a low visibility state around the own vehicle, The gain adjustment unit increases the output gain in response to the detection of the low visibility state The information presentation device according to claim 1 or claim 2, characterized by the above.