U.S. patent application number 15/761714 was filed with the patent office on 2018-12-20 for sound effect generation device for vehicles.
This patent application is currently assigned to MAZDA MOTOR CORPORATION. The applicant listed for this patent is MAZDA MOTOR CORPORATION. Invention is credited to Tadayuki NIIBE, Naoki YAMADA.
Application Number | 20180366103 15/761714 |
Document ID | / |
Family ID | 59964325 |
Filed Date | 2018-12-20 |
United States Patent
Application |
20180366103 |
Kind Code |
A1 |
NIIBE; Tadayuki ; et
al. |
December 20, 2018 |
SOUND EFFECT GENERATION DEVICE FOR VEHICLES
Abstract
A vehicle sound effect generation apparatus includes a running
state detecting unit that detects a running state of a vehicle; a
lateral input amount setting unit that sets, based on the running
state detected by the running state detecting unit, a lateral input
amount in which a physical amount relating to at least one of a
movement of the vehicle in a width direction and a movement of the
vehicle in a turning direction is a parameter; an adjustment wave
sound selector that selects one or more half-order adjustment wave
sounds having a half-order frequency component, based on the
lateral input amount; and a sound effect generation unit that
synthesizes a fundamental wave sound having a fundamental frequency
component with the one or more half-order adjustment wave sounds
selected.
Inventors: |
NIIBE; Tadayuki;
(Yawatahama-shi, JP) ; YAMADA; Naoki;
(Hiroshima-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAZDA MOTOR CORPORATION |
Hiroshima |
|
JP |
|
|
Assignee: |
MAZDA MOTOR CORPORATION
Hiroshima
JP
|
Family ID: |
59964325 |
Appl. No.: |
15/761714 |
Filed: |
March 15, 2017 |
PCT Filed: |
March 15, 2017 |
PCT NO: |
PCT/JP2017/010341 |
371 Date: |
March 20, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G10K 2210/1282 20130101;
G10K 2210/121 20130101; B60R 11/0264 20130101; B60R 11/0258
20130101; G10K 15/04 20130101; B60R 11/02 20130101; H04R 3/00
20130101 |
International
Class: |
G10K 15/04 20060101
G10K015/04; B60R 11/02 20060101 B60R011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2016 |
JP |
2016-071382 |
Claims
1. A vehicle sound effect generation apparatus for generating a
sound effect of an engine based on a vibration sound database
including a fundamental wave sound having a fundamental frequency
component and a plurality of adjustment wave sounds having a
frequency component other than the fundamental frequency component,
the vehicle sound effect generation apparatus comprising: a running
state detecting unit that detects a running state of a vehicle; a
lateral input amount setting unit that sets, based on the running
state detected by the running state detecting unit, a lateral input
amount in which a physical amount relating to at least one of a
movement of the vehicle in a width direction and a movement of the
vehicle in a turning direction is a parameter; an adjustment wave
sound selector that selects one or more half-order adjustment wave
sounds having a half-order frequency component, based on the
lateral input amount; and a sound effect generation unit that
synthesizes the fundamental wave sound with the one or more
half-order adjustment wave sounds selected.
2. The vehicle sound effect generation apparatus according to claim
1, wherein the adjustment wave sound selector increases, as the
lateral input amount is larger, a gain or gains of the one or more
half-order adjustment wave sounds selected.
3. The vehicle sound effect generation apparatus according to claim
1, wherein the adjustment wave sound selector selects, from the
half-order adjustment wave sounds included in the vibration sound
database, at least a half-order adjustment wave sound having a
half-order frequency component closest to the fundamental frequency
component.
4. The vehicle sound effect generation apparatus according to claim
1, wherein the sound effect generation unit increases a sound
pressure level of the sound effect as the lateral input amount is
larger.
5. The vehicle sound effect generation apparatus according to claim
1, wherein the adjustment wave sound selector is configured to be
capable of selecting one or more integer-order adjustment wave
sounds having an integer-order frequency component, based on the
lateral input amount, and the sound effect generation unit is
configured to be capable of synthesizing the fundamental wave sound
with the one or more integer-order adjustment wave sounds, the
vehicle sound effect generation apparatus further comprising a mode
selector unit that can select a first mode for synthesizing the
fundamental wave sound with the one or more integer-order
adjustment wave sounds, and a second mode for synthesizing the
fundamental wave sound with the one or more half-order adjustment
wave sounds.
6. The vehicle sound effect generation apparatus according to claim
1, wherein the adjustment wave sound selector is configured to be
capable of selecting one or more integer-order adjustment wave
sounds having an integer-order frequency component, based on the
lateral input amount, the sound effect generation unit is
configured to be capable of synthesizing the fundamental wave sound
with the one or more integer-order adjustment wave sounds, and the
adjustment wave sound selector selects at least an integer-order
adjustment wave sound having an integer-order frequency component
close to the one or more half-order adjustment wave sound selected.
Description
TECHNICAL FIELD
[0001] The present invention relates to a vehicle sound effect
generation apparatus and particularly relates to a vehicle sound
effect generation apparatus that synthesizes a fundamental wave
sound with a half-order adjustment wave sound based on a lateral
input amount.
BACKGROUND ART
[0002] In recent years, in-vehicle silencing is being dramatically
promoted from viewpoints of both a car body structure and control.
This causes a situation such that an engine sound cannot
appropriately bring the realism of running.
[0003] Therefore, a sound effect (also referred to as an active
engine sound) generation apparatus is proposed. The sound effect
generation apparatus detects driver's driving amount and generates,
in a vehicle, a sound effect of an engine according to the driving
amount through an in-vehicle speaker.
[0004] A sound effect generation apparatus disclosed in Patent
Literature 1 includes fundamental frequency setting means for
setting a fundamental frequency related to the number of cylinders
and a rotation speed of an engine, harmonic determining means for
determining a plurality of harmonics of the fundamental frequency,
and gain determining means for determining a harmonic-enhanced gain
of the engine. The gain determining means includes a circuit that
determines an engine load. The engine load determination circuit
includes at least one of an accelerator pedal position
determination circuit, a mass airflow determination circuit, a
negative pressure determination circuit, and an engine torque
determination circuit. The engine load determination circuit
adjusts a harmonic enhancing level based on the harmonic-enhanced
gain.
[0005] This configuration causes vehicle occupants including a
driver to feel a startlingly realistic engine sound.
[0006] Further, a vehicle control device disclosed in Patent
Literature 2 includes operation amount detecting means for
detecting an operation amount of operation means to be operated
during acceleration, transient operation amount arithmetic means
for calculating a transient operation amount based on a stationary
state of the operation means, speed arithmetic means for
calculating an operating speed of the operation means, and target
arithmetic means for calculating at least one of a target
acceleration and a target sound pressure that increase by an
increase exceeding a differential threshold per time when a human
can perceive stimuli received. At least one of a torque generation
device and an in-vehicle acoustic device is controlled based on at
least one of the target acceleration and the target sound
pressure.
[0007] This configuration offers comfortable acceleration
performance and acceleration feeling to a driver.
[0008] Normally, a sound recognized by a person is an auditory
phenomenon caused by a fluctuation (a sound wave) of an air
pressure, and its property is roughly classified into three parts
including a volume, a tone, and a timbre.
[0009] Herein, the volume is related to a sound pressure level, the
tone is related to a frequency, and the timbre is related to a
sound quality.
[0010] When a fundamental wave sound having a fundamental frequency
component and an integer-order component wave sound having an
integer-order (secondary or more) frequency component with respect
to the fundamental wave sound are simultaneously generated, a
concord in which both the sounds are mixed together is formed
without a beat (interference) between the sounds because an
integer-order adjustment wave sound (a component wave sound) of the
integer-order frequency component is an overtone series of the
fundamental wave sound.
[0011] On the contrary, when the fundamental wave sound and a
component wave sound having a frequency component other than the
integer-order (secondary or more) frequency component with respect
to the fundamental wave sound are simultaneously generated, a
discord (an unclear sound) is generated by the interference between
the sounds because an adjustment wave sound to be synthesized with
the fundamental wave sound is not an overtone series of the
fundamental wave sound.
[0012] In the sound effect generation apparatus in Patent
Literature 1, realism of an engine sound during actual running of a
vehicle and characteristics of engine sounds that vary with vehicle
types are artificially reproduced by setting a gain for enhancement
per frequency component wave sound.
[0013] Further, in the vehicle control device in Patent Literature
2, a sound effect according to an increase in acceleration of a
vehicle is generated by setting a target sound pressure level of a
high-frequency component wave sound of an engine sound.
[0014] However, in the sound effect generation apparatuses in
Patent Literature 1 and 2, an attention is not paid to
characteristics of a sound effect to be generated in driver's
perception (sense), and thus relativity between a tone of a sound
effect and a driver's operational feeling is not taken into
consideration at all.
[0015] Further, in Patent Literature 1 and 2, since a
harmonic-enhanced gain and a target sound pressure level are
determined by using only an operation amount of an accelerator
pedal as a parameter, a driver cannot feel sufficient running
realism that accords with the running state of a vehicle.
Therefore, the driver might not sufficiently acquire running
information relating to a driver's sense of hearing as one piece of
information necessary for the driving operation on the vehicle.
[0016] That is, in an initial turn state, when the accelerator is
excessively pressed down, a ground-contact friction force of front
wheels cannot withstand a centrifugal force, and thus under
steering is likely to occur. Therefore, an accelerator is
necessarily released or a steering wheel (hereinafter, referred to
as a steering) is necessarily additionally steered, or both of the
operations are necessarily performed. However, since opening of the
accelerator is small, a harmonic-enhanced gain is barely
obtained.
[0017] For this reason, since running information (a sound effect)
which is acoustically perceived by a driver is insufficient, there
is concern about a delay of start timing of a driver's
response.
[0018] In an intermediate turn state, theoretically, since the
opening of the accelerator is maintained small, namely, a so-called
partial state is brought about, the harmonic-enhanced gain is
barely obtained.
[0019] For this reason, although a great cornering force exists,
the running information acoustically perceived by a driver is
insufficient, and thus the driver might have a feeling of
strangeness.
[0020] Further, in a latter turn state, when the steering is
operated back and simultaneously the accelerator is pressed down, a
harmonic-enhanced gain is barely obtained in a region where the
opening of the accelerator is still insufficient although a
cornering force gradually reduces.
[0021] For this reason, the driver cannot sensationally expect the
feeling of an increase in a vehicle speed when the accelerator is
pressed down at an exit of the corner.
CITATION LIST
Patent Literature
Patent Literature 1: Japanese Translation of PCT Publication No.
2014-507679
Patent Literature 2: Unexamined Japanese Patent Publication No.
2008-025492
SUMMARY OF INVENTION
[0022] An object of the present invention is to provide a vehicle
sound effect generation apparatus that is capable of acoustically
exhibiting a turning behavior of a vehicle using a half-order
adjustment wave sound including a half-order frequency of a
fundamental wave sound of an engine.
[0023] The present invention for achieving the above object
provides a vehicle sound effect generation apparatus for generating
a sound effect of an engine based on a vibration sound database
including a fundamental wave sound having a fundamental frequency
component and a plurality of adjustment wave sounds having a
frequency component other than the fundamental frequency component,
the vehicle sound effect generation apparatus including: a running
state detecting unit that detects a running state of a vehicle; a
lateral input amount setting unit that sets, based on the running
state detected by the running state detecting unit, a lateral input
amount in which a physical amount relating to at least one of a
movement of the vehicle in a width direction and a movement of the
vehicle in a turning direction is a parameter; an adjustment wave
sound selector that selects one or more half-order adjustment wave
sounds having a half-order frequency component, based on the
lateral input amount; and a sound effect generation unit that
synthesizes the fundamental wave sound with the one or more
half-order adjustment wave sounds selected.
[0024] According to the vehicle sound effect generation apparatus
of the present invention, a feeling of a turning operation can be
heightened for a vehicle occupant by acoustically exhibiting a
turning behavior of the vehicle using a dynamic rumble sound of the
engine.
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 is a schematic configuration diagram of a vehicle
equipped with a vehicle sound effect generation apparatus according
to a first embodiment.
[0026] FIG. 2 is a block diagram of the vehicle sound effect
generation apparatus.
[0027] FIG. 3 is a vibration sound map.
[0028] FIG. 4A to FIG. 4C illustrate gain maps of adjustment wave
sounds set in accordance with a lateral acceleration: FIG. 4A is a
standard gain map; FIG. 4B is a decrease gain map; and FIG. 4C is
an increase gain map.
[0029] FIG. 5 is a flowchart of a sound effect generating
process.
[0030] FIG. 6 is a flowchart of a lateral input amount setting
process.
[0031] FIG. 7 is a flowchart of a map selecting process.
[0032] FIG. 8 is a flowchart of a risk degree determining
process.
[0033] FIG. 9 is a flowchart of a discord generating process.
[0034] FIG. 10 is a flowchart of a harmonic sound generating
process.
[0035] FIG. 11 is a flowchart of a rumble sound generating
process.
[0036] FIG. 12 is a flowchart of a weight setting process.
DESCRIPTION OF EMBODIMENTS
[0037] Embodiments of the present invention will be described in
detail below with reference to the drawings.
[0038] The following description illustrates that the present
invention is applied to a vehicle V, and does not limit the present
invention, its application, or its usefulness.
First Embodiment
[0039] A first embodiment of the present invention will be
described below with reference to FIGS. 1 to 12.
[0040] A sound effect generation apparatus 1 selectively generates
sound effects (a harmonic sound, a rumble sound, and a discord) of
an engine in accordance with a running state of the vehicle V, and
differently uses tones of the sound effects of the engine in
accordance with the running state. As a result, the sound effect
generation apparatus 1 provides current and future running
information to a driver (a vehicle occupant) through an acoustic
sense. In such a manner, an acoustic presentation effect during
driving is heightened.
[0041] A sound effect presentation function provided by the sound
effect generation apparatus 1 includes a realism enhancing
function, a reminder function, and an operation uncomfortable
feeling alleviating function.
[0042] Herein, the harmonic sound is a sound effect obtained by
synthesizing a fundamental wave sound having a fundamental
frequency component with an integer-order adjustment wave sound
having an integer-order frequency component of the fundamental wave
sound. The rumble sound is a sound effect obtained by synthesizing
a fundamental wave sound having a fundamental frequency component
with a half-order adjustment wave sound having a half-order
frequency component of the fundamental wave sound. The discord is a
sound effect obtained by synthesizing a fundamental wave sound
having a fundamental frequency component with a discordant
adjustment wave sound having a discordant frequency component other
than the integer-order frequency component and the half-order
frequency component of the fundamental wave sound. Further, in the
following description, a primary frequency component is the
fundamental frequency component, and a primary component wave sound
having the primary frequency component is the fundamental wave
sound.
[0043] As illustrated in FIGS. 1 and 2, the sound effect generation
apparatus 1 includes an electric control unit (ECU) 2, a pair of
right and left speakers 3 and 4 used as a part of an audio system,
an accelerator sensor 5, a yaw rate sensor 6, a steering angle
sensor 7, a lateral acceleration sensor (hereinafter, referred to
as a lateral G sensor) 8, a wheel speed sensor 9, a gradient sensor
10, a weight sensor 11, a navigation device 12, a turn control
device (hereinafter, referred to as a DSC device) 13, a drive
assist device 14, a mode selector switch 15 (mode selector unit),
and the like.
[0044] The pair of speakers 3 and 4 is connected so as to be
capable of receiving an electric signal from the ECU 2. The
respective sensors 5 to 11 and the mode selector switch 15 are
connected so as to be capable of transmitting an electric signal to
the ECU 2. The respective devices 12 to 14 are connected so as to
be capable of transmitting and receiving an electric signal to and
from the ECU 2. At least one of the respective sensors 5 to 11 and
the respective devices 12 to 14 corresponds to a running state
detecting unit that directly or indirectly detects a running state
of the vehicle V including running environment information of the
vehicle V.
[0045] The pair of speakers 3 and 4 and the respective sensors 5 to
11 will be first described.
[0046] The pair of speakers 3 and 4 is disposed on lower end
portions of a pair of right and left front pillars, respectively,
in accordance with a left front position and a right front position
of a driver sat on a front seat.
[0047] The speakers 3 and 4 are configured to be capable of
independently changing respective frequency gains and sound
pressure levels of sounds (sound effects) generated by an operation
signal input from the ECU 2.
[0048] For this reason, when a sound pressure level of a sound
effect generated from the speaker 3 is set to be higher than a
sound pressure level of a sound effect generated from the speaker
4, a driver's visual line is guided toward the speaker 3.
Therefore, the driver can be caused to recognize a left front
visual field including a left door mirror.
[0049] Further, when a sound pressure level of a sound effect
generated from the speaker 4 is set to be higher than a sound
pressure level of a sound effect generated from the speaker 3, a
driver's visual line is guided toward the speaker 4. Therefore, the
driver can be caused to recognize a right front visual field
including a right door mirror.
[0050] The accelerator sensor 5 detects a pressing-down amount of
an accelerator pedal (not illustrated) and outputs a detection
signal. The yaw rate sensor 6 outputs a signal according to a yaw
rate y of the vehicle V.
[0051] The steering angle sensor 7 outputs a signal relating to a
steering angle .theta. of a steering wheel operated by a driver.
The lateral G sensor 8 outputs a signal relating to a current
lateral acceleration A which acts on the vehicle V. The wheel speed
sensor 9 outputs a signal according to a rotation speed of wheels
(not illustrated) for detection of a vehicle speed v. The gradient
sensor 10 outputs a signal according to an inclination angle of a
driving lane (road surface) on which the vehicle V currently runs
or stops. The weight sensor 11 outputs a signal relating to a
weight of a load in a trunk of the vehicle V.
[0052] The respective devices 12 to 14 will be described below.
[0053] As illustrated in FIGS. 1 and 2, the navigation device 12 is
disposed on an upper center of an instrument panel, and includes a
position detector for the vehicle V, a map data input unit, a sound
output speaker, a monitor, and the like (they are not illustrated).
The navigation device 12 is electrically connected with a global
positioning system (GPS) receiver (not illustrated) for detecting a
current running position of the vehicle V.
[0054] The GPS receiver receives signals from a plurality of GPS
satellites to detect a current position of the vehicle V.
[0055] Further, the navigation device 12 includes a map database in
which road map data is stored, traffic rules database in which
traffic rules data is stored, and the like (these databases are not
illustrated).
[0056] As a result, the navigation device 12 gives a driver a route
to driver's destination using the current position data of the
vehicle V through the GPS receiver, the road map data in the map
database, and the traffic rules data in the traffic rules database.
The navigation device 12 outputs the current position data of the
vehicle V, the road map data, and the traffic rules data to the ECU
2.
[0057] The navigation device 12 corresponds to a turn information
acquisition unit that acquires curvature information including an
existence position and a turning radius of a curve on a driving
lane in a traveling frontal direction of the vehicle V from the map
database.
[0058] The DSC device 13 receives input signals from the respective
sensors to perform DSC control to improve running stability of the
vehicle V during turn.
[0059] Specifically, when determining, based on detection signals
from the yaw rate sensor 6, the lateral G sensor 8, and the wheel
speed sensor 9, that a turning attitude of the vehicle V is lost by
a predetermined amount or more, the DSC device 13 controls braking
forces of the respective wheels through an operation of a
pressurizing unit (not illustrated) for a brake fluid pressure, and
causes a yaw moment to act on a vehicle body so as to turn the
turning attitude of the vehicle V in a target direction.
[0060] Further, the DSC device 13 receives the input signals from
the respective sensors, and performs antilock brake system (ABS)
control to prevent wheel locks of the respective wheels.
[0061] Specifically, the DSC device 13 calculates slip ratios of
the respective wheels based on a detection signal from the wheel
speed sensor 9, and when detecting a wheel whose calculated slip
ratio exceeds a predetermined threshold, controls the pressurizing
unit to reduce the braking force acting on the wheel detected. In
such a manner, the wheel lock is prevented.
[0062] The DSC device 13 calculates, based on a detection signal
from the lateral G sensor 8 and a detection signal from the wheel
speed sensor 9, a road surface friction coefficient .mu.
(hereinafter, simply the friction coefficient .mu.) as well as the
slip ratios of the wheels, and outputs the calculated friction
coefficient .mu. to the ECU 2.
[0063] The drive assist device 14 has an inter-vehicle distance
notifying function of notifying an inter-vehicle distance in front
of and behind the vehicle V, a feeling improving function of
improving driver's feeling, and the like.
[0064] The inter-vehicle distance notifying function is a function
of avoiding collision by sounding an alarm via the speakers 3 and 4
or lighting a warning lamp (not illustrated) so as to cause a
driver to recognize a risk of collision when another vehicle (a
leading vehicle or a following vehicle) or an obstacle is present
in a region which is separated from the vehicle V by a
predetermined distance in front of and behind the vehicle V during
running, and by guiding the driver to perform an avoiding
operation.
[0065] The feeling improving function is a function of estimating a
feeling relating to driver's emotions during running, based on
driver's facial expression and action, and guiding a driver's
feeling to an improved zone (from an uncomfortable or inactive
state to a comfortable or active state) through lighting and
music.
[0066] As illustrated in FIG. 1, the drive assist device 14
includes charge coupled device (CCD) cameras 16 to 18 that can
capture a still image or a moving image.
[0067] The front camera 16 is attached to a position near a
rear-view mirror (not illustrated) on a front-end lower surface of
a roof panel, and is configured to be capable of imaging a white
line position of a driving lane in a traveling frontal direction, a
leading vehicle, approach and parting positions of a curve in the
traveling frontal direction, and the like, via a front windshield
glass.
[0068] The rear camera 17 is attached to a rear-end lower surface
of the roof panel, and is configured to be capable of imaging a
following vehicle and the like via a rear windshield glass. The
cameras 16 and 17 are a stereo type camera in which a lens
mechanism and a shutter mechanism are shared by the two cameras,
and are configured to be capable of individually detecting a
distance between the vehicle V and an object to be imaged and a
direction from the vehicle V to the object to be imaged.
[0069] The indoor camera 18 is attached, for example, to above the
instrument panel to image an upper body of the driver including a
driver's face. The captured image of the upper body of the driver
is used for: specifying a facial expression by cutting out the
facial image from the captured image; specifying a dimension of
pupils and an eye direction by enlarging and detecting irises of
eyes; and specifying an attitude based on a barycentric position of
the image and a shape of the upper body, for example. A driver's
emotion is estimated by using a biaxial plane formed by a
transverse axis expressing comfort and discomfort and a vertical
axis expressing activeness and inactiveness (for example, a
Russell's circumplex model of emotions) and a feature amount of a
driver's facial expression imaged by the indoor camera 18.
[0070] Further, the indoor camera 18 can capture an indoor image
including a vehicle occupant (passenger) other than the driver at a
wide angle, and detects the number of vehicle occupants in the
vehicle V through this captured image.
[0071] The mode selector switch 15 includes a momentary selector
switch with which activation (starting of an operation) of the
sound effect generation apparatus 1 and a type (a mode) of a sound
effect can be selected.
[0072] The mode selector switch 15 is configured to be capable of
selecting a first mode for generating an engine sound effect mainly
including a harmonic sound through a predetermined ON operation, or
a second mode for generating an engine sound effect mainly
including a rumble sound through a predetermined ON operation.
[0073] All frequencies of component sounds match with each other
and a beat (interference) does not occur between a fundamental wave
sound and an integer-order adjustment wave sound having an
integer-order frequency component. For this reason, a harmonic
sound, which is obtained by synthesizing the fundamental wave sound
with one or more integer-order adjustment wave sounds,
reverberates, and a concord that makes a driver comfortable is
generated.
[0074] Interference partially occurs between a fundamental wave
sound and a half-order adjustment wave sound, in which an
even-number-order overtone includes a half-order frequency
component which is an overtone series of the fundamental wave
sound. However, since a driver (a vehicle occupant) feels such
interference only slightly, a rumble sound, which is obtained by
synthesizing the fundamental wave sound with one or more half-order
adjustment wave sounds, is rather dynamic. Thus, a quasi-concord
that causes the vehicle occupants such as the driver to recognize
feeling of power is generated.
[0075] Further, when any one of the first and second modes is
selected in an ON state of the mode selector switch 15, a third
mode for generating an engine sound effect mainly including a
discord is executed under a condition that a risk degree B
determined by a risk degree determining unit 25, described later,
is a determination threshold r1 or more for determining the risk
degree.
[0076] The sound effect to be generated in the third mode is
obtained by synthesizing a fundamental wave sound having a
fundamental frequency component with one or more discordant
adjustment wave sounds having a discordant frequency component
other than an integer-order frequency component and a half-order
frequency component of the fundamental wave sound. For this reason,
a beat occurs between component sounds. Thus, this sound effect is
a discord that gives the driver an uncomfortable impression
accompanied by nervousness and a sense of caution.
[0077] The ECU 2 will be described below.
[0078] The ECU 2 is configured to synthesize a fundamental wave
sound with the selected one or more adjustment wave sounds to
artificially generate an engine sound effect so as to improve a
driver's operational feeling.
[0079] The ECU 2 includes a central processing unit (CPU), a
read-only memory (ROM), a random-access memory (RAM), an amplifier,
an in-side interface, and an out-side interface.
[0080] The ROM stores various programs and data for generating
respective engine sound effects, and the RAM is provided with a
processing area to be used when the CPU executes a series of
process.
[0081] The in-side interface is electrically connected to the
respective sensors 5 to 11, the respective devices 12 to 14, and
the mode selector switch 15. The out-side interface is electrically
connected to the pair of speakers 3 and 4 and the respective
devices 12 to 14 via the amplifier.
[0082] The ECU 2 stores, for example, a vibration sound map M1 (a
vibration sound database) in which a plurality of sound sources is
stored, the sound sources being preset so as to be fitted to
generated sounds from a four-cylinder gasoline engine mounted to
the vehicle V.
[0083] As illustrated in FIG. 3, the vibration sound map M1 stores,
per rotation speed of an engine, sound sources at each unit
frequency (for example, 0.01-order frequency) from a primary
component wave sound (a fundamental wave sound) to 10-order
component wave sound, the primary component wave sound having a
fundamental frequency component, the 10-order component wave sound
having a frequency component which is ten times as large as the
fundamental frequency component.
[0084] For this reason, the vibration sound map M1 includes, per
rotation speed of an engine, a fundamental wave sound, an
integer-order component wave sound (an integer-order adjustment
wave sound) having a frequency component which is an integral
multiple of a fundamental frequency component, a half-order
component wave sound (a half-order adjustment wave sound) in which
an even-number-order overtone is an overtone series of the
fundamental wave sound, and a discordant component wave sound (a
discordant adjustment wave sound) in which an overtone relationship
does not hold with respect to the fundamental wave sound.
[0085] As illustrated in FIG. 2, the ECU 2 includes a lateral input
amount setting unit 21, an adjustment wave sound selector 22, a
behavior delay predicting unit 23, an inhibition condition
determining unit 24, a risk degree determining unit 25, a lateral G
calculating unit 26 (a lateral acceleration calculating unit), a
sound effect generation unit 27, and a visual guidance direction
setting unit 28.
[0086] The lateral input amount setting unit 21 is configured to be
capable of setting a lateral input amount P in which a physical
amount relating to at least one of a movement of the vehicle V in a
width direction and a movement of the vehicle V in the turning
direction is a parameter, based on a running state of the vehicle V
detected by a running state detecting unit (at least one of the
respective sensors 5 to 11 and the respective devices 12 to
14).
[0087] When a detection value of a yaw rate is set to y and a
detection value of the lateral acceleration is set to A, in a case
where the vehicle speed v of the vehicle V is a determination
threshold t2 or more, the lateral input amount P is calculated in
accordance with a following equation (1).
P=y/A (1)
[0088] As a result, the lateral input amount P in which a sideslip
tendency and a slip tendency of the vehicle V are reflected is
obtained.
[0089] When the vehicle speed v of the vehicle V is less than the
determination threshold t2, the lateral input amount setting unit
21 sets the lateral input amount P to the lateral acceleration A.
When the vehicle speed v is low like a time of turning right or
left at an intersection, since sideslip or slip of the vehicle V
hardly occurs, the lateral acceleration A in which an actual
turning state of the vehicle V is reflected most clearly is used as
the lateral input amount P.
[0090] At least a vehicle state in a lateral direction may be
reflected in the lateral input amount P. Like the lateral input
amount P at the low-vehicle speed, any one detection value of the
steering angle .theta. of the steering wheel, the yaw rate y, and
the lateral acceleration A may be used as the lateral input amount
P regardless of the vehicle speed v. Further, a parameter in which
two or more detection values are combined can be adopted as the
lateral input amount P regardless of the vehicle speed v.
[0091] The adjustment wave sound selector 22 will be described
below.
[0092] The adjustment wave sound selector 22 is configured to be
capable of selecting, from the plurality of component wave sounds
stored in the vibration sound map M1, one or more adjustment wave
sounds to be synthesized with a fundamental wave sound N0.
[0093] The adjustment wave sound selector 22 selects first to third
adjustment wave sounds N1 to N3, and determines, using the gain
maps M2 to M4 selected based on a running state, first to third
gains g1 to g3 (0<g1<g2<g3) for correcting the first to
third adjustment wave sounds N1 to N3, respectively.
[0094] The gain maps M2 to M4 will be described.
[0095] As illustrated in FIG. 4A to FIG. 4C, the ECU 2 stores a
standard gain map M2, a decrease gain map M3, an increase gain map
M4 in advance.
[0096] Gains .alpha.2 to .alpha.4, .beta.2 to .beta.4, and .gamma.2
to .gamma.4 of the first to third adjustment wave sounds N1 to N3
as one of output properties of a sound effect are set symmetrically
so as to be defined to zero when the lateral acceleration A is zero
and so as to be increased like a linear function as an absolute
value of the lateral acceleration A increases.
[0097] The gains .alpha.2 to .alpha.4, .beta.2 to .beta.4, and
.gamma.2 to .gamma.4 increase at an increase rate which is larger
than an increase rate before a certain mid-stage point and are
converged to a constant value at an upper limit value.
[0098] In the gain maps M2 to M4, the gain values are defined such
that a following formula (2) holds.
.gamma.2<.beta.2<.alpha.2
.gamma.3<.beta.3<.alpha.3
.gamma.4<.beta.4<.alpha.4 (2)
[0099] Further, in the gain maps M2 to M4, the gain values are
defined respectively such that a following formula (3) holds.
.alpha.3<.alpha.2<.alpha.4
.beta.3<.beta.2<.beta.4
.gamma.3<.gamma.2<.gamma.4 (3)
[0100] The adjustment wave sound selector 22 selects the gain maps
M2 to M4 using, as determination conditions, a predicted result of
the behavior delay predicting unit 23 and a determined result of
the inhibition condition determining unit 24.
[0101] The behavior delay predicting unit 23 is configured to
predict that a behavior delay of the vehicle V occurs when a total
weight of the vehicle V to be specified by the number of vehicle
occupants and a weight of a cargo (hereinafter, simply a vehicle
weight) is a determination threshold t3 or more.
[0102] When the behavior delay predicting unit 23 predicts
occurrence of the behavior delay of the vehicle V in such a manner,
the adjustment wave sound selector 22 selects the increase gain map
M4 having high responsivity.
[0103] That is, when the vehicle weight is the determination
threshold t3 or more, the behavior of the vehicle V is likely to be
delayed with respect to a steering angle operation (an operation
amount) performed by the driver. For this reason, the adjustment
wave sound selector 22 selects the increase gain map M4 having high
responsivity such that a sound effect is corrected to be increased
prior to a current behavior of the vehicle V. As a result, the
behavior delay of the vehicle V is corrected acoustically so that a
driver's feeling of strangeness in the operation can be
eliminated.
[0104] The inhibition condition determining unit 24 is configured
to determine that the vehicle V is in a condition that association
between a driver's operation amount and the behavior of the vehicle
V is inhibited, in other words, operability of the vehicle V is
deteriorated (hereinafter, in the inhibition condition), when the
friction coefficient .mu. is a determination threshold t4 or less
or when an ascending gradient is a determination threshold t5 or
more.
[0105] When the inhibition condition determining unit 24 determines
the inhibition condition such that the operability of the vehicle V
is deteriorated, the adjustment wave sound selector 22 selects the
decrease gain map M3 having low responsivity.
[0106] That is, when the friction coefficient .mu. input from the
DSC device 13 is the determination threshold t4 or less or when an
ascending gradient input from the gradient sensor 10 is the
determination threshold t5 or more, an actual behavior of the
vehicle V can hardly follow a steering angle operation performed by
the driver. For this reason, the adjustment wave sound selector 22
selects the decrease gain map M3 having low responsivity such that
the sound effect is corrected to be decreased. As a result,
degradation of the following performance of the vehicle V is
corrected acoustically so that a driver's feeling of strangeness in
the operation can be eliminated.
[0107] On the other hand, when a behavior delay of the vehicle V
and the degradation of the following performance are unlikely to
occur, the standard gain map M2 having standard responsivity is
selected.
[0108] Further, description returns to the adjustment wave sound
selector 22.
[0109] When the first mode is selected, the adjustment wave sound
selector 22 is configured to select, based on the lateral input
amount P, the first to third adjustment wave sounds N1 to N3 having
an integer-order frequency component.
[0110] Specifically, when the lateral input amount P is a
determination threshold p2 or less (0<p1<p2), a secondary
component wave sound which is an integer-order frequency component
closest to a fundamental frequency component is allocated to the
first adjustment wave sound N1. When the lateral input amount P is
larger than the determination threshold p2 and is a determination
threshold p3 or less (p2<p3), a tertiary component wave sound
which is an integer-order frequency component next closest after
the secondary component wave sound is allocated to the second
adjustment wave sound N2 as well as the already selected first
adjustment wave sound N1. When the lateral input amount P is larger
than the determination threshold p3, a quaternary component wave
sound which is an integer-order frequency component next closest
after the tertiary component wave sound is allocated to the third
adjustment wave sound N3 as well as the already selected first and
second adjustment wave sounds N1 and N2.
[0111] The reason for such an operation is that a consonance level
of an adjustment wave sound having an integer-order frequency
component can be made to be higher as the integer-order frequency
component is closer to the fundamental frequency component.
[0112] The adjustment wave sound selector 22 extracts, based on the
lateral input amount P, the gain g1 (.alpha.2 to .alpha.4) for
correcting the first adjustment wave sound N1, the gain g2 (.beta.2
to .beta.4) for correcting the second adjustment wave sound N2, and
the gain g3 (.gamma.2 to .gamma.4) for correcting the third
adjustment wave sound N3 from any one of the selected gain maps M2
to M4. As described above, when the first mode is selected, as the
lateral input amount P is larger, the adjustment wave sound
selector 22 increases the number of the first to third adjustment
wave sounds N1 to N3 and increases the first to third gains g1 to
g3 of the selected first to third adjustment wave sounds N1 to
N3.
[0113] The adjustment wave sound selector 22 is configured to
select, based on the lateral input amount P, the first to third
adjustment wave sounds N1 to N3 having a half-order frequency
component when the second mode is selected.
[0114] Specifically, when the lateral input amount P is the
determination threshold p2 or less, a 1.5-order component wave
sound which is a half-order frequency component closest to a
fundamental frequency component is allocated to the first
adjustment wave sound N1. When the lateral input amount P is larger
than the determination threshold p2 and is the determination
threshold p3 or less, a 2.5-order component wave sound which is a
half-order frequency component next closest after the 1.5-order
component wave sound is allocated to the second adjustment wave
sound N2 as well as the already selected first adjustment wave
sound N1. When the lateral input amount P is larger than the
determination threshold p3, a 3.5-order component wave sound which
is a half-order frequency component next closest after the
2.5-order component wave sound is allocated to the third adjustment
wave sound N3 as well as the already selected first and second
adjustment wave sounds N1 and N2.
[0115] The reason for such an operation is that a consonance level
(a quasi-concordant level) of an adjustment wave sound having a
half-order frequency component can be made to be higher as the
half-order frequency component is closer to the fundamental
frequency component.
[0116] Similarly to the first mode, the adjustment wave sound
selector 22 extracts, based on the lateral input amount P, the gain
g1 for correcting the first adjustment wave sound N1, the gain g2
for correcting the second adjustment wave sound N2, and the gain g3
for correcting the third adjustment wave sound N3 from any one of
the selected gain maps M2 to M4. As described above, when the
second mode is selected, as the lateral input amount P is larger,
the adjustment wave sound selector 22 increases the number of the
first to third adjustment wave sounds N1 to N3 and increases the
first to third gains g1 to g3 of the selected first to third
adjustment wave sounds N1 to N3.
[0117] The adjustment wave sound selector 22 is configured to
select, based on the risk degree B, the first to third adjustment
wave sounds N1 to N3 having a discordant frequency component when
the third mode is selected in accordance with the determination in
the risk degree determining unit 25.
[0118] The risk degree determining unit 25 determines the risk
degree B of the vehicle V based on a current running state.
[0119] The risk degree determining unit 25 calculates determination
amounts a to c based on a steering angle speed .DELTA..theta. in a
driver's steering operation, the lateral input amount P, and an
inter-vehicle distance L between the vehicle V and a leading
vehicle or a following vehicle closest to the vehicle V, and
calculates the risk degree B based on the calculated determination
amounts a to c.
[0120] When the steering angle speed .DELTA..theta. is a
determination threshold t6 or more, the steering angle speed
determination amount a is calculated in accordance with a following
formula (4). When the steering angle speed .DELTA..theta. has the
other values, the amount a is zero. Symbols k1 to k3 (0<k1, k2,
k3) represent correction coefficients.
a=k1.times..DELTA..theta. (4)
[0121] When the lateral input amount P is a determination threshold
t7 or less, the lateral input amount determination amount b is
calculated in accordance with a following formula (5). When the
lateral input amount P has the other values, the amount b is
zero.
b=k2.times.P (5)
[0122] When the inter-vehicle distance L is a determination
threshold t8 or less, the inter-vehicle distance determination
amount c is calculated in accordance with a following formula (6).
When the inter-vehicle distance L has the other values, the amount
c is zero.
c=k3.times.L (6)
[0123] The risk degree B is calculated in accordance with a
following formula (7).
B=a+b+c (7)
[0124] As a result, when each of the determination amounts is
averagely high and also when a specific determination amount is
high, the risk degree B is determined accurately.
[0125] When the risk degree B determined by the risk degree
determining unit 25 is the determination threshold r1 or more
(0<r1) in a state that either of the first and second modes is
selected, the adjustment wave sound selector 22 determines that the
third mode is selected and selects the first to third adjustment
wave sounds N1 to N3 based on the risk degree B.
[0126] Specifically, when the risk degree B is a determination
threshold r2 or less (r1<r2), a 9.75-order component sound wave
is allocated to the first adjustment wave sound N1, the 9.75-order
component sound wave being a discordant frequency component which
is farthest from the fundamental frequency component and is in a
middle section between an integer-order frequency component (a
ten-order frequency component) and a half-order frequency component
(a 9.5-order frequency component). When the risk degree B is larger
than the determination threshold r2 and is a determination
threshold r3 or less (r2<r3), a 9.25-order component sound wave
is allocated to the second adjustment wave sound N2 as well as the
already selected first adjustment wave sound N1, the 9.25-order
component sound wave being a discordant frequency component which
is next farthest from the fundamental frequency component after the
9.75-order component sound wave and is in a middle section between
an integer-order frequency component (a 9-order frequency
component) and the half-order frequency component (the 9.5-order
frequency component). When the risk degree B is larger than the
determination threshold r3, a 8.75-order component wave sound is
allocated to the third adjustment wave sound N3 as well as the
already selected first and second adjustment wave sounds N1 and N2,
the 8.75-order component wave sound being a discordant frequency
component which is next farthest from fundamental frequency after
the 9.25-order component sound wave and is in a middle section
between the integer-order frequency component (the 9-order
frequency component) and a half-order frequency component (a
8.5-order frequency component).
[0127] The reason for such an operation is that interference
increases and a discordant level can be made to be higher in the
adjustment wave sound having the discordant frequency component as
the discordant frequency component is farther from the fundamental
frequency component and is farther from the integer-order frequency
component and the half-order frequency component.
[0128] Similarly to the first and second modes, the adjustment wave
sound selector 22 extracts, based on the lateral input amount P,
the gain g1 for correcting the first adjustment wave sound N1, the
gain g2 for correcting the second adjustment wave sound N2, and the
gain g3 for correcting the third adjustment wave sound N3 from any
one of the selected gain maps M2 to M4, and corrects the first to
third adjustment wave sounds N1 to N3.
[0129] As described above, when the third mode is selected, as the
risk degree B is larger, the adjustment wave sound selector 22
increases the number of the first to third adjustment wave sounds
N1 to N3 to be selected and increases the first to third gains g1
to g3 of the selected first to third adjustment wave sounds N1 to
N3.
[0130] When a prediction lateral acceleration A1 calculated by the
lateral G calculating unit 26 is a determination threshold t1 or
more, the adjustment wave sound selector 22 selects the first to
third adjustment wave sounds N1 to N3, and determines, using the
gain maps M2 to M4 selected based on the running state, the first
to third gains g1 to g3 for respectively correcting the first to
third adjustment wave sounds N1 to N3.
[0131] The lateral G calculating unit 26 is configured to
determine, based on map information including a turning radius
input from the map database of the navigation device 12, whether a
curve is present in the traveling frontal direction of the vehicle
V, and to calculate, when the curve is present, the prediction
lateral acceleration A1, which acts on the vehicle V going around
the curve.
[0132] The prediction lateral acceleration A1 is calculated under a
condition that a curve is present at a distance which has been
preset so as to be separated from a current running position of the
vehicle V or in an area where the vehicle V has been predicted to
arrive within a preset time.
[0133] A turning angle .theta.t of the wheels can be calculated in
accordance with a following formula (8) when a prediction steering
angle of the vehicle V according to the turning radius of the curve
is represented by .theta.p and a gear ratio of the vehicle V is
represented by gr.
.theta.t=.theta.p/gr (8)
[0134] Further, a front wheel position rotating radius R of the
vehicle V can be calculated in accordance with a following formula
(9) when a wheel base of the vehicle V is represented by W.
R=W/sin.theta.t (9)
[0135] When a vehicle speed is represented by v, the prediction
lateral acceleration A1 can be expressed by a following formula
(10). For this reason, the prediction lateral acceleration A1,
which acts on the vehicle V in going around the curve where the
vehicle V runs in the near future, can be obtained by assigning the
front wheel position rotating radius R calculated in accordance
with the formula (9) to the formula (10).
A1=v.sup.2/R (10)
[0136] The sound effect generation unit 27 will be described
below.
[0137] The sound effect generation unit 27 is configured to
correct, as expressed in a following formula (11), the first to
third adjustment wave sounds N1 to N3 using the first to third
gains g1 to g3 extracted for each mode, and synthesize the
fundamental wave sound N0 with the first to third adjustment wave
sounds N1 to N3 corrected after selection to generate a sound
effect S.
N1.rarw.g1.times.N1
N2.rarw.g2.times.N2
N3.rarw.g3.times.N3 (11)
[0138] Further, the sound effect generation unit 27 increases a
sound pressure level of the sound effect S as the lateral input
amount P is larger, the risk degree B is larger, and the prediction
lateral acceleration A1 is larger.
[0139] As a result, the driver is caused to acoustically recognize
levels of the lateral input amount P, the risk degree B, and the
prediction lateral acceleration A1 which affect running of the
vehicle V.
[0140] The sound effect generation unit 27 is configured to be
capable of setting the sound pressure level correction coefficients
G.sub.L and G.sub.R of the pair of speakers 3 and 4 and changing
the sound pressure levels of the sound effects independently.
[0141] The sound effect generation unit 27 increases a sound
pressure level of the speaker 3 (4) on a side of the visual
guidance direction, the sound pressure level being set by the
visual guidance direction setting unit 28, and decreases a sound
pressure level of the other speaker 4 (3) with respect to a visual
guidance direction .theta.d.
[0142] When the visual line of the driver is guided, a strength
ratio between the sound pressure level correction coefficients
G.sub.L and G.sub.R is changed by setting the sound pressure level
correction coefficients G.sub.L and G.sub.R for correction
coefficients k4 and k5, respectively, and a localized horizontal
direction of a sound image with respect to a frontal direction of
the driver is changed.
[0143] The correction coefficients k4 and k5 are obtained as
interpolation coefficients to be set based on the visual guidance
direction .theta.d.
[0144] The visual guidance direction setting unit 28 is configured
to determine presence or absence of a visual guidance request based
on various information from the navigation device 12 and the drive
assist device 14, and be capable of setting, when the visual
guidance request is present, the visual guidance direction .theta.d
at which the driver shoots a look in a frontal direction of the
driver.
[0145] A subject at which the driver has to look is a subject that
possibly affects running of the vehicle V from a viewpoint of
safety and operability when the driver does not recognize the
subject. The visual guidance direction .theta.d is defined as a
direction where the driver can recognize a subject at which the
driver has to look with the driver as a reference.
[0146] Specifically, in a situation that a following vehicle
overtakes the vehicle V (or a vehicle that is running on a right
lane is approaching rapidly), the following vehicle passes by on a
right side of the vehicle V. For this reason, when the vehicle V
makes a lane change to the right lane, the vehicles might get
contact with each other. Therefore, when the drive assist device 14
detects rapid approach of a following vehicle (a vehicle that is
running on a right lane), the visual guidance direction setting
unit 28 determines presence of the visual guidance request to guide
the driver's visual line to a right door mirror. For this reason,
the visual guidance direction .theta.d associated with a right
forward direction is set, and sound images from the speakers 3 and
4 are localized in the visual guidance direction .theta.d.
[0147] Further, in a situation that the driver is following a
curve, when a driver's visual line is not fixed to a parting
position (or a clipping point) of the curve, the driver might lose
control of the vehicle. Therefore, when the drive assist device 14
(the navigation device 12) detects a curve parting position during
running, the visual guidance direction setting unit 28 determines
presence of the visual guidance request, and sets the visual
guidance direction .theta.d associated with a curve parting
position to localize sound images from the speakers 3 and 4 in the
visual guidance direction .theta.d.
[0148] In a situation that the driver is tired during running on a
freeway, the driver might lose control of the vehicle. Therefore,
when the drive assist device 14 detects a driver's fatigue (for
example, uncomfortable and inactive) state, the visual guidance
direction setting unit 28 determines presence of the visual
guidance request, and sets the visual guidance direction .theta.d
associated with a rest area (or an overhead sign) based on the map
information in the navigation device 12 to localize the sound
images from the speakers 3 and 4 in the visual guidance direction
.theta.d.
[0149] A procedure of a sound effect generating process will be
described below with reference to flowcharts of FIGS. 5 to 12. In
FIGS. 5 to 12, Si (i=1, 2 . . . ) represents a step of each
process.
[0150] As illustrated in the flowchart of FIG. 5, in the sound
effect generating process, first, in S1 various information such as
detection values of the respective sensors and determination
thresholds is read, and the first to third adjustment wave sounds
N1 to N3, the gains g1 to g3, a sound pressure level correction
coefficient F, the sound pressure level correction coefficients
G.sub.L and G.sub.R, and the determination amounts a to c which are
set in the previous routine are initialized, and the process goes
to S2.
[0151] In S2, a determination is made whether the mode selector
switch 15 has performed an ON operation.
[0152] As a result of the determination in S2, when the mode
selector switch 15 has performed the ON operation, the process goes
to S3 and a lateral input amount setting process is executed. As
the result of the determination in S2, when the mode selector
switch 15 has not performed the ON operation, the sound effect
generating process is not executed, and the process returns.
[0153] After a map selecting process (S4) is executed, the process
goes to S5 and a risk degree determining process is executed.
[0154] In S6, a determination is made whether the risk degree B is
the determination threshold r1 or more.
[0155] As a result of the determination in S6, when the risk degree
B is the determination threshold r1 or more, the third mode is
executed more preferentially than the first and second modes. The
process then goes to S7 and a discord generating process is
executed.
[0156] The process goes to S8 and a weight setting process is
executed.
[0157] The process then goes to S9. A signal of the left sound
effect S.sub.L is set by multiplying the sound effect S and the
sound pressure level correction coefficient G.sub.L, and a signal
of the right sound effect S.sub.R is set by multiplying the sound
effect S and the sound pressure level correction coefficient
G.sub.R.
[0158] The process then goes to S10. The control signals of the
sound effect S.sub.L and S.sub.R are output to the speakers 3 and
4, respectively, and after the sound effects S.sub.L and S.sub.R
are generated from the speakers 3 and 4, respectively, the process
returns.
[0159] As the result of the determination in S6, when the risk
degree B is less than the determination threshold r1, the process
goes to S11, and a determination is made whether a curve is present
in the traveling frontal direction of the vehicle V.
[0160] As a result of the determination in S11, when a curve is
present in the traveling frontal direction of the vehicle V, the
process goes to S12, and the prediction lateral acceleration A1 is
calculated by using formulas (8) to (10).
[0161] In S13, a determination is made whether the prediction
lateral acceleration A1 is the determination threshold t1 or
more.
[0162] As a result of the determination in S13, when the prediction
lateral acceleration A1 is the determination threshold t1 or more,
a careful driving operation is necessary for running on a curve
where the vehicle V enters in the near future, and an alert has to
be raised such that driver's attention is turned to the driving
operation. For this reason, the process goes to S14, and a
multiplied value of the prediction lateral acceleration A1 by
correction coefficient f1 is set as the sound pressure level
correction coefficient F.
[0163] In S15, a determination is made whether the first mode has
been selected by an operation of the mode selector switch 15.
[0164] As a result of the determination in S15, when the first mode
has been selected, the process goes to S16. After the harmonic
sound generating process is executed, the process goes to S8.
[0165] As the result of the determination in S15, when the first
mode has not been selected, the second mode is selected. For this
reason, the process goes to S17, and after the rumble sound
generating process is executed, the process goes to S8.
[0166] As the result of the determination in S13, when the
prediction lateral acceleration A1 is less than the determination
threshold t1, the prediction lateral acceleration A1 to be
generated in the future is small, and the need to raise an alert
for the driver is low. For this reason, the process goes to S18,
and a determination is made whether the current lateral input
amount P is a determination threshold p1 or more.
[0167] As a result of the determination in S18, when the lateral
input amount P is the determination threshold p1 or more, the
lateral input amount P that affects a behavior of the vehicle V is
generated. Therefore, process goes to S15.
[0168] As the result of the determination in S18, when the lateral
input amount P is less than the determination threshold p1, the
lateral input amount P that affects a behavior of the vehicle V is
not generated. Therefore, process returns.
[0169] A procedure of the lateral input amount setting process will
be described below.
[0170] As illustrated in the flowchart of FIG. 6, in the lateral
input amount setting process, first, a determination is made in S21
whether the vehicle speed v is the determination threshold t2 or
more.
[0171] As a result of the determination in S21, when the vehicle
speed v is the determination threshold t2 or more, the process goes
to S22, and a value obtained by dividing the yaw rate y by the
lateral acceleration A is set as the lateral input amount P. The
process then ends.
[0172] As the result of the determination in S21, when the vehicle
speed v is less than the determination threshold t2, the process
goes to S23, and the lateral acceleration A is set as the lateral
input amount P. The process then ends.
[0173] A procedure of the map selecting process will be described
below.
[0174] As illustrated in the flowchart of FIG. 7, in the map
selecting process, first, a determination is made in S31 whether a
vehicle weight specified based on the number of vehicle occupants
and a weight of a cargo is the determination threshold t3 or
more.
[0175] As a result of the determination in S31, when the vehicle
weight is the determination threshold t3 or more, the behavior of
the vehicle V might be delayed with respect to the steering angle
operation performed by the driver. For this reason, the process
goes to S32, the increase gain map M4 is selected, and then the
process ends.
[0176] As the result of the determination in S31, when the vehicle
weight is less than the determination threshold t3, the process
goes to S33, and a determination is made whether the friction
coefficient .mu. is the determination threshold t4 or less, or the
ascending gradient is the determination threshold t5 or more.
[0177] As a result of the determination in S33, when the friction
coefficient .mu. is the determination threshold t4 or less, or the
ascending gradient is the determination threshold t5 or more, an
actual behavior of the vehicle V might hardly follow a steering
angle operation performed by the driver. For this reason, the
process goes to S34, the decrease gain map M3 is selected, and then
the process ends.
[0178] As the result of the determination in S33, when the friction
coefficient .mu. exceeds the determination threshold t4 and the
ascending gradient is less than the determination threshold t5, an
actual behavior of the vehicle V follows a steering angle operation
performed by the driver. Therefore, the process goes to S35, the
standard gain map M2 is selected, and then the process ends.
[0179] A procedure of the risk degree determining process will be
described below.
[0180] As illustrated in the flowchart of FIG. 8, in the risk
degree determining process, first, a determination is made in S41
whether the steering angle speed .DELTA..theta. is the
determination threshold t6 or more.
[0181] As a result of the determination in S41, when the steering
angle speed .DELTA..theta. is the determination threshold t6 or
more, the process goes to S42. Thereafter, a multiplied value of
the steering angle speed .DELTA..theta. by the correction
coefficient k1 is set as the steering angle speed determination
amount a.
[0182] In S43, a determination is made whether the lateral input
amount P is the determination threshold t7 or less.
[0183] As a result of the determination in S43, when the lateral
input amount P is the determination threshold t7 or less, the
process goes to S44 and a multiplied value of the lateral input
amount P by the correction coefficient k2 is set as the lateral
input amount determination amount b.
[0184] In S45, a determination is made whether the inter-vehicle
distance L with respect to a leading vehicle or a following vehicle
is the determination threshold t8 or less.
[0185] As a result of the determination in S45, when the
inter-vehicle distance L is the determination threshold t8 or less,
the process goes to S46, and a multiplied value of the
inter-vehicle distance L by the correction coefficient k3 is set as
the inter-vehicle distance determination amount c.
[0186] In S47, a value obtained by adding the determination amounts
a, b, and c is set as the risk degree B, and then the process
ends.
[0187] As the result of the determination in S45, when the
inter-vehicle distance L exceeds the determination threshold t8,
the process goes to S48, and the inter-vehicle distance
determination amount c is set to zero. The process then goes to
S47.
[0188] As the result of the determination in S43, when the lateral
input amount P exceeds the determination threshold t7, the process
goes to S49, and the lateral input amount determination amount b is
set to zero. The process then goes to S45.
[0189] As the result of the determination in S41, when the steering
angle speed .DELTA..theta. is less than the determination threshold
t6, the process goes to S50, and the steering angle speed
determination amount a is set to zero. The process then goes to
S43.
[0190] A procedure of the discord generating process will be
described below.
[0191] As illustrated in a flowchart of FIG. 9, in the discord
generating process, first, a determination is made in S51 whether
the risk degree B is the determination threshold r2 or less.
[0192] As a result of the determination in S51, when the risk
degree B is the determination threshold r2 or less, the risk degree
B is at an intermediate level, and thus the process goes to
S52.
[0193] In S52, the 9.75-order component sound wave which is the
discordant frequency component is set to the first adjustment wave
sound N1, and the process goes to S53 without setting the second
and third adjustment wave sounds N2 and N3 (in this case, N2 and N3
are zero, the same below).
[0194] In S53, the gain g1 (g2, g3) of the adjustment wave sound N1
(N2, N3) set in the previous step is set based on the gain map
selected in the map selecting process.
[0195] The process then goes to S54, and a multiplied value of the
risk degree B by a correction coefficient f2 is set as the sound
pressure level correction coefficient F.
[0196] In S55, a multiplied value, which is obtained by multiplying
an added value of the first adjustment wave sound N1 corrected by
the gain g1, the second adjustment wave sound N2 corrected by the
gain g2, and the third adjustment wave sound N3 corrected by the
gain g3, by the sound pressure level correction coefficient F, is
set to the sound effect S. The process then ends.
[0197] As the result of the determination in S51, when the risk
degree B exceeds the determination threshold r2, the process goes
to S56, and a determination is made whether the risk degree B is
the determination threshold r3 or less.
[0198] As a result of the determination in S56, when the risk
degree B is the determination threshold r3 or less, the risk degree
B is large. Therefore, the process goes to S57.
[0199] In S57, the 9.75-order component sound wave is set to the
first adjustment wave sound N1, and the 9.25-order component sound
wave which is discordant frequency component is set to the second
adjustment wave sound N2. The process goes to S53 without setting
the third adjustment wave sound N3.
[0200] As the result of the determination in S56, when the risk
degree B exceeds the determination threshold r3, the risk degree B
is extremely large, and thus the process goes to S58.
[0201] In S58, the 9.75-order component sound wave is set to the
first adjustment wave sound N1, the 9.25-order component sound wave
is set to the second adjustment wave sound N2, and the 8.75-order
component wave sound which is the discordant frequency component is
set to the third adjustment wave sound N3. Thereafter, the process
goes to S53.
[0202] A procedure of the harmonic sound generating process will be
described below.
[0203] As illustrated in the flowchart of FIG. 10, in the harmonic
sound generating process, first, a determination is made in S61
whether the lateral input amount P is the determination threshold
p2 or less.
[0204] As a result of the determination in S61, when the lateral
input amount P is the determination threshold p2 or less, the
lateral input amount P is at an intermediate level, and thus the
process goes to S62.
[0205] In S62, the secondary component wave sound which is the
integer-order frequency component is set to the first adjustment
wave sound N1, and the process goes to S63 without setting the
second and third adjustment wave sounds N2 and N3.
[0206] In S63, the gain g1 (g2, g3) of the adjustment wave sound N1
(N2, N3) set in the previous step is set based on the gain map
selected in the map selecting process.
[0207] The process then goes to S64, and a determination is made
whether the sound pressure level correction coefficient F has
already been set.
[0208] As a result of the determination in S64, when the sound
pressure level correction coefficient F has already been set, the
process goes to S65.
[0209] In S65, a multiplied value, which is obtained by multiplying
an added value of the first adjustment wave sound N1 corrected by
the gain g1, the second adjustment wave sound N2 corrected by the
gain g2, and the third adjustment wave sound N3 corrected by the
gain g3, by the sound pressure level correction coefficient F, is
set to the sound effect S. The process then ends.
[0210] As the result of the determination in S64, when the sound
pressure level correction coefficient F has not yet been set, the
process goes to S66.
[0211] In S66, a multiplied value of the lateral input amount P by
a correction coefficient f3 is set as the sound pressure level
correction coefficient F, and then the process goes to S65.
[0212] As the result of the determination in S61, when the lateral
input amount P exceeds the determination threshold p2, the process
goes to S67. A determination is made whether the lateral input
amount P is the determination threshold p3 or less.
[0213] As a result of the determination in S67, when the lateral
input amount P is the determination threshold p3 or less, the
lateral input amount P is large, and thus the process goes to
S68.
[0214] In S68, the secondary component wave sound is set to the
first adjustment wave sound N1, and the tertiary component wave
sound which is the integer-order frequency component is set to the
second adjustment wave sound N2. The process goes to S63 without
setting the third adjustment wave sound N3.
[0215] As the result of the determination in S67, when the lateral
input amount P exceeds the determination threshold p3, the lateral
input amount P is extremely large, and thus the process goes to
S69.
[0216] In S69, the secondary component wave sound is set to the
first adjustment wave sound N1, the tertiary component wave sound
is set to the second adjustment wave sound N2, and the quaternary
component wave sound N which is the integer-order frequency
component is set to the third adjustment wave sound N3. The process
then goes to S63.
[0217] A procedure of the rumble sound generating process will be
described below.
[0218] As illustrated in the flowchart of FIG. 11, in the rumble
sound generating process, first, a determination is made in S71
whether the lateral input amount P is the determination threshold
p2 or less.
[0219] As a result of the determination in S71, when the lateral
input amount P is the determination threshold p2 or less, the
lateral input amount P is at an intermediate level, and thus the
process goes to S72.
[0220] In S72, the 1.5-order component wave sound which is the
half-order frequency component is set to the first adjustment wave
sound N1, and the process goes to S73 without setting the second
and third adjustment wave sounds N2 and N3.
[0221] In S73, the gain g1 (g2, g3) of the adjustment wave sound N1
(N2, N3) set in the previous step is set based on the gain map
selected in the map selecting process.
[0222] The process then goes to S74, and a determination is made
whether the sound pressure level correction coefficient F has
already been set.
[0223] As a result of the determination in S74, when the sound
pressure level correction coefficient F has already been set, the
process goes to S75.
[0224] In S75, a multiplied value, which is obtained by multiplying
an added value of the first adjustment wave sound N1 corrected by
the gain g1, the second adjustment wave sound N2 corrected by the
gain g2, and the third adjustment wave sound N3 corrected by the
gain g3, by the sound pressure level correction coefficient F, is
set to the sound effect S. The process then ends.
[0225] As the result of the determination in S74, when the sound
pressure level correction coefficient F has not yet been set, the
process goes to S76.
[0226] In S76, a multiplied value of the lateral input amount P by
a correction coefficient f4 is set as the sound pressure level
correction coefficient F, and then the process goes to S65.
[0227] As the result of the determination in S71, when the lateral
input amount P exceeds the determination threshold p2, the process
goes to S77 and a determination is made whether the lateral input
amount P is the determination threshold p3 or less.
[0228] As a result of the determination in S77, when the lateral
input amount P is the determination threshold p3 or less, the
lateral input amount P is large, and thus the process goes to
S78.
[0229] In S78, the 1.5-order component wave sound is set to the
first adjustment wave sound N1, the 2.5-order component wave sound
which is the half-order frequency component is set to the second
adjustment wave sound N2. The process then goes to S73 without
setting the third adjustment wave sound N3.
[0230] As the result of the determination in S77, when the lateral
input amount P exceeds the determination threshold p3, the lateral
input amount P is extremely large, and thus the process goes to
S79.
[0231] In S79, the 1.5-order component wave sound is set to the
first adjustment wave sound N1, the 2.5-order component wave sound
is set to the second adjustment wave sound N2, and the 3.5-order
component wave sound which is the half-order frequency component is
set to the third adjustment wave sound N3. The process then goes to
S73.
[0232] A procedure of the weight setting process will be described
below.
[0233] As illustrated in the flowchart of FIG. 12, in the weight
setting process, first, the visual guidance direction setting unit
28 determines in S81 whether the visual guidance request is
present.
[0234] As a result of the determination in S81, when the visual
guidance request is present, the sound pressure levels of the right
and left speakers 3 and 4 are necessarily differentiated.
Therefore, the process goes to S82 and the visual guidance
direction .theta.d is set.
[0235] The process then goes to S83, and the sound pressure level
correction coefficients G.sub.L and G.sub.R are set to the
correction coefficients k4 and k5, respectively, based on the
visual guidance direction .theta.d. Thereafter, the process
ends.
[0236] As the result of the determination in S81, when the visual
guidance request is not present, the sound pressure levels of the
right and left speakers 3 and 4 are not necessarily differentiated.
Therefore, the sound pressure level correction coefficients G.sub.L
and G.sub.R are set to 1, and the process ends.
[0237] A function and an effect of the vehicle sound effect
generation apparatus 1 will be described below.
[0238] The sound effect generation apparatus 1 includes the lateral
input amount setting unit 21 that sets, based on the running state
detected by the sensors 6 and 8, the lateral input amount P in
which a physical amount relating to at least one of a movement of
the vehicle V in the width direction and a movement of the vehicle
V in the turning direction is a parameter. For this reason, the
lateral input amount P in which an actual turning behavior of the
vehicle V is reflected can be set regardless of an operating amount
of the vehicle V by the driver.
[0239] Further, the sound effect generation apparatus 1 includes
the adjustment wave sound selector 22 that can select, based on the
lateral input amount P, the first to third adjustment wave sounds
N1 to N3 having a half-order frequency component. For this reason,
it is possible to select the first to third adjustment wave sounds
N1 to N3 (half-order adjustment wave sounds) that can generate
rumble sounds for causing the driver to recognize dynamism as a
quasi-concord. Further, the sound effect generation apparatus 1
includes the sound effect generation unit 27 that synthesizes the
fundamental wave sound N0 with the selected first to third
adjustment wave sounds N1 to N3. For this reason, the rumble sound
adaptable to an actual turning behavior of the vehicle V is
generated so that driver's operational feeling can be
heightened.
[0240] The adjustment wave sound selector 22 increases the gains g1
to g3 of the selected half-order adjustment wave sounds N1 to N3 as
the lateral input amount P is larger. For this reason, feeling of
power to be recognized by the driver can be enhanced.
[0241] The adjustment wave sound selector 22 selects, from the
half-order component wave sounds included in the vibration sound
map M1, at least a half-order adjustment wave sound N1 having a
half-order frequency component closest to the fundamental frequency
component. For this reason, interference with the fundamental wave
sound N0 can be suppressed, and a rumble sound which is both
comfortable and powerful can be generated.
[0242] The sound effect generation unit 27 increases the sound
pressure level of the sound effect S as the lateral input amount P
is larger. Therefore, feeling of power to be recognized by the
driver can be further enhanced according to the turning behavior of
the vehicle V.
[0243] The adjustment wave sound selector 22 is configured to be
capable of selecting the first to third adjustment wave sounds N1
to N3 having an integer-order frequency component, based on the
lateral input amount P. The sound effect generation unit 27 is
configured to be capable of synthesizing the fundamental wave sound
N0 with the selected first to third adjustment wave sounds N1 to N3
(the integer-order adjustment wave sounds). Further, the sound
effect generation apparatus 1 includes the mode selector switch 15
that can select the first mode and the second mode, the first mode
being for selecting integer-order adjustment wave sounds as the
first to third adjustment wave sounds N1 to N3 and synthesizing the
integer-order adjustment wave sounds with the fundamental wave
sound N0, the second mode being for selecting half-order adjustment
wave sounds as the first to third adjustment wave sounds N1 to N3
and synthesizing the half-order adjustment wave sounds with the
fundamental wave sound N0.
[0244] With this configuration, various acoustic presentation can
be provided by a harmonic sound and a rumble sound that do not make
the driver uncomfortable.
[0245] A modified example in which the embodiment is partially
changed will be described below.
[0246] [1] In the above embodiment, the number of adjustment wave
sounds to be synthesized with a fundamental wave sound can be set
to at most 3 based on a running state, but the number of the
adjustment wave sounds may be set to 2 or 4 or more according to a
specification, a running environment, and a state of the vehicle V.
When the number of adjustment wave sounds is set to 4 or more, the
number of gains defined in the gain maps M2 to M4 is preferably set
according to the number of set adjustment wave sounds.
[0247] [2] In the above embodiment, an adjustment wave sound to be
synthesized with a fundamental wave sound is limited to a
half-order adjustment wave sound, but the adjustment wave sound may
be selected to include an integer-order adjustment wave sound
having an integer-order frequency component close to one or more
half-order adjustment wave sounds selected.
[0248] Specifically, when a 2.5-order component wave sound is
synthesized with a fundamental wave sound (a primary component wave
sound), a secondary component wave sound or a tertiary component
wave sound closest to the 2.5-order component wave sound is
additionally synthesized so that a rumble sound that provides
enhanced comfortableness can be generated.
[0249] [3] In the above embodiment, the sound effect generation
unit changes the sound pressure levels of the pair of right and
left speakers so that the localized direction of a sound image is
changed. However, the localized direction of a sound image may be
changed by setting a delay time of a sound effect to reach the
driver while the sound pressure levels of the pair of speakers are
maintained without changing the sound pressure levels of the pair
of speakers.
[0250] Specifically, an output from the speaker on a side opposite
to the visual guidance direction is delayed from an output from the
visual guidance direction-side speaker, so that the localized
direction of a sound image can be moved toward the visual guidance
direction.
[0251] Further, in order to heighten recognition by the driver, the
localized direction of a sound image may be shifted linearly from
the frontal direction of the driver through the visual guidance
direction, and this shifting operation may be repeated.
[0252] Further, speakers may be movable. In addition to the pair of
speakers, a speaker may be additionally disposed above the pair of
speakers so that the visual guidance direction can be set
three-dimensionally.
[0253] [4] The above embodiment has described an example of the
drive assist device having the inter-vehicle distance notifying
function and the feeling improving function. However, the drive
assist device can detect at least an outside-vehicle situation and
an in-vehicle situation, and thus may have an obstacle detecting
function or a white line (of a driving lane) detecting
function.
[0254] Further, detecting means may be means other than a CCD, and
thus may be, for example, a millimeter-wave radar.
[0255] [5] The above embodiment has described an example of the
sound effect generation apparatus that generates a sound effect of
an engine based on a lateral input amount that affects a movement
of the vehicle in the width direction. However, the sound effect
generation apparatus may generate a sound effect of an engine based
on at least the lateral input amount. Therefore, a sound effect
generation apparatus that generates a sound effect of an engine
based on an accelerator opening degree may be used in
combination.
[0256] Further, cooperative control is enabled by the sound effect
generation apparatus that generates a sound effect of an engine
based on an accelerator opening degree.
[0257] [6] The above embodiment has described an example where the
sound pressure level of the rumble sound is increased in accordance
with an increase in the lateral input amount, but a harmonic sound
may be used in combination.
[0258] In this case, when the sound pressure level of the rumble
sound is increased, accordingly a sound pressure level of the
harmonic sound is decreased.
[0259] [7] The above embodiment has described an example where the
vibration sound map is used. However, a vibration sound map may be
prepared for each engine specification such as displacement or the
number of cylinders so that a vibration sound map according to an
engine specification can be selected when a mounted engine is
replaced.
[0260] The above embodiment has described an example using the
vibration sound map of the four-cylinder gasoline engine actually
mounted to a vehicle. However, a sound effect may be generated by
using a vibration sound map of any internal combustion (for
example, a four-cylinder gasoline engine) for a hybrid vehicle or
an electric vehicle.
[0261] [8] Embodiments obtained by applying various modifications
of which a person skilled in the art thinks to the embodiments may
be included within a range of the present invention as long as they
do not deviate from the subject matter of the present
invention.
SUMMARY OF THE EMBODIMENT
[0262] The above embodiment will be summarized as follows.
[0263] The above embodiment relates to a vehicle sound effect
generation apparatus for generating a sound effect of an engine
based on a vibration sound database including a fundamental wave
sound having a fundamental frequency component and a plurality of
adjustment wave sounds having a frequency component other than the
fundamental frequency component. The vehicle sound effect
generation apparatus includes a running state detecting unit that
detects a running state of a vehicle, a lateral input amount
setting unit that sets, based on the running state detected by the
running state detecting unit, a lateral input amount in which a
physical amount relating to at least one of a movement of the
vehicle in a width direction and a movement of the vehicle in a
turning direction is a parameter, an adjustment wave sound selector
that selects one or more half-order adjustment wave sounds having a
half-order frequency component, based on the lateral input amount,
and a sound effect generation unit that synthesizes the fundamental
wave sound with the one or more half-order adjustment wave sounds
selected.
[0264] The vehicle sound effect generation apparatus includes the
lateral input amount setting unit that sets, based on the running
state detected by the running state detecting unit, the lateral
input amount in which a physical amount relating to at least one of
the movement of the vehicle in the width direction and the movement
of the vehicle in the turning direction is a parameter. For this
reason, a lateral input amount in which an actual turning behavior
of the vehicle is reflected can be set regardless of an operation
amount of the vehicle operated by a vehicle occupant.
[0265] Further, the vehicle sound effect generation apparatus
includes the adjustment wave sound selector that selects the one or
more half-order adjustment wave sounds having a half-order
frequency component, based on the lateral input amount. For this
reason, it is possible to select a half-order adjustment wave
sound, which enables generation of a rumble sound for causing a
vehicle occupant to recognize dynamics. Further, the vehicle sound
effect generation apparatus includes the sound effect generation
unit that synthesizes the fundamental wave sound with the one or
more half-order adjustment wave sounds selected. For this reason, a
rumble sound adaptable to an actual turning behavior of the vehicle
is generated so that operational feeling of the vehicle occupant
can be heightened.
[0266] Herein, as to the half-order adjustment wave sound having
the half-order frequency component, an even-number-order overtone
is an overtone series of the fundamental wave sound, interference
partially occurs with respect to the fundamental wave sound.
However, a vehicle occupant feels such interference only slightly.
Therefore, the rumble sound obtained by synthesizing the
fundamental wave sound with the half-order adjustment wave sound
can be treated as a quasi-concord that might cause a vehicle
occupant to sensationally recognize dynamics while the vehicle is
being driven.
[0267] Preferably, the adjustment wave sound selector increases, as
the lateral input amount is larger, a gain or gains of the one or
more half-order adjustment wave sounds selected.
[0268] This configuration can enhance feeling of power to be
recognized by a vehicle occupant.
[0269] Preferably, the adjustment wave sound selector selects, from
the half-order adjustment wave sounds included in the vibration
sound database, at least a half-order adjustment wave sound having
a half-order frequency component closest to the fundamental
frequency component.
[0270] This configuration can suppress interference with the
fundamental wave sound and can generate a rumble sound which is
both comfortable and powerful.
[0271] Preferably, the sound effect generation unit increases a
sound pressure level of the sound effect as the lateral input
amount is larger.
[0272] This configuration can further enhance feeling of power to
be recognized by a vehicle occupant according to a turning behavior
of the vehicle.
[0273] Preferably, the adjustment wave sound selector is configured
to be capable of selecting one or more integer-order adjustment
wave sounds having an integer-order frequency component, based on
the lateral input amount, and the sound effect generation unit is
configured to be capable of synthesizing the fundamental wave sound
with the one or more integer-order adjustment wave sounds. The
vehicle sound effect generation apparatus further includes a mode
selector unit that can select a first mode for synthesizing the
fundamental wave sound with the one or more integer-order
adjustment wave sounds, and a second mode for synthesizing the
fundamental wave sound with the one or more half-order adjustment
wave sounds.
[0274] With this configuration, various acoustic presentation can
be provided by a harmonic sound and a rumble sound that do not make
a vehicle occupant uncomfortable.
[0275] In another preferable mode, the adjustment wave sound
selector is configured to be capable of selecting one or more
integer-order adjustment wave sounds having an integer-order
frequency component, based on the lateral input amount, the sound
effect generation unit is configured to be capable of synthesizing
the fundamental wave sound with the one or more integer-order
adjustment wave sounds, and the adjustment wave sound selector
selects at least an integer-order adjustment wave sound having an
integer-order frequency component being close to the one or more
half-order adjustment wave sounds selected.
[0276] This configuration can generate a rumble sound that provides
enhanced comfortableness.
* * * * *