JPH08175334A - Vehicular road surface condition detecting - Google Patents

Abstract

PURPOSE: To enable accurate detection of a road-surface μ and the amount of water on road surface by detecting road noise and a splash which are caused as a vehicle travels, and calculating the amount of steadily stable liquid on the basis of a differential value from a running noise reference value related to sound pressure. CONSTITUTION: A follow-up running control unit 30, to which signals output from wheel speed sensors 28FL to 28RR and a running noise sensor 39, etc., are input, subjects the detected running noise to frequency analysis to obtain a detected sound pressure value. The unit 30 also fetches from stored data and on the basis of vehicle and engine speeds a running sound pressure reference value for running on dry road surfaces and thereby calculates road noise. Then a difference in the integrated value of sound pressures in a low frequency band where this noise exists, and a difference in the integrated value of sound pressures in a high frequency band where a splash exists are subjected to conversion correction using respective correction factors one of which corresponds to the vehicle speed and the other to the amount of rainfall, so that a road-surface μ and the amount of water on the road surface are calculated respectively from the corrected differences in the integrated values of sound pressures in the low and high frequency bands.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive force distribution control device for a four-wheel drive vehicle capable of variably controlling the drive force distribution to the front and rear wheels, and to follow a vehicle in front while securing a predetermined inter-vehicle distance. The present invention relates to a vehicle road surface condition detection device which is effectively applied to an automatic travel control device or the like capable of traveling, and particularly to a vehicle road surface condition capable of providing useful information such as the amount of water on the road surface to such a control device. Suitable for detection equipment.

[0002]

2. Description of the Related Art As such a road surface condition detecting device for a vehicle, for example, the actual application of the Japanese Laid-Open Patent Application Sho 62-93 previously proposed by the present applicant.
No. 328 and the same as Japanese Utility Model Laid-Open No. 62-97836. These vehicle road surface condition detection device, for example, a running state sound detector called a splash sensor is attached to the wheel house panel at the rear of the front wheels, and as a result of the wheels splashing rainwater and the like from the road surface as the vehicle travels, The splash sensor detects a vibration (also referred to as a splash sound) generated when the splash of water or the like hits the wheel house panel. Then, when the sound pressure of the splash sound becomes larger than a preset predetermined value, the arithmetic processing unit including a microcomputer or the like determines that, for example, the amount of water on the road surface is large, and the traveling stability of the vehicle is stabilized. In order to improve the property, for example, a signal for switching from the two-wheel drive state to the four-wheel drive state is output to the drive force distribution control device as described above (in this source, the same microcomputer performs the drive force distribution calculation process). Is supposed to run). Also,
In the vehicle described in the above publication, the negative acceleration (also referred to as deceleration) that actually occurs in the vehicle is detected, and on the other hand, the splash sound has a linear relationship with the splash amount of rainwater splashing from the road surface. Assuming that there is, the integrated value of the splash amount is calculated by integrating the splash sound, and the deceleration that may occur in the vehicle is calculated from the integrated value of the splash amount. Compared with the actual deceleration, when the detected deceleration is greater than the calculated deceleration, the two-wheel drive state is set, and when the calculated deceleration is greater than the detected deceleration, A control mode for switching to the four-wheel drive state is also disclosed.

[0003]

However, in the vehicle road surface condition detecting apparatus as described above, the vibration of the wheel house panel is directly detected as a splash sound, and the sound pressure is simply compared with a predetermined value. However, the following problems are possible. That is, the splash amount related to the splash sound should increase as the traveling speed, that is, the vehicle speed increases, even if the amount of rainwater on the road surface is the same. If the liquid amount on the road surface is calculated based on the sound pressure of the vibration of the wheel house panel detected as, there is a possibility that the road surface situation may be erroneously recognized.

Further, it is considered that the vibration of the wheel house panel also includes a vibration component caused by a vehicle running device such as an engine or a drive system, and these are mainly engine speed and engine speed. If it depends on the engine rotation state such as, the liquid amount on the road surface was calculated based on the sound pressure of the vibration of the wheel house panel detected as the splash sound without considering the engine rotation state. Then, there is a possibility that the recognition or discrimination accuracy of the road surface condition may be deteriorated.

Further, it is considered that the vibration of the wheel house panel also includes a vibration component related to road noise and the like. Therefore, without considering the road noise, the vibration of the wheel house panel detected as the splash sound. If the liquid amount on the road surface is calculated based on the sound pressure of vibration, the accuracy of recognition or discrimination of the road surface situation may be reduced. As is known, this road noise also depends on the vehicle speed and the engine rotation state.

The present invention has been developed in view of these problems, and in the sound pressure of the vibration of the wheel house panel, the frequency band related to the splash sound and the frequency band related to the road noise are different. Focusing on that,
In addition, a vehicle road surface condition detection device that can reject the effects of vehicle speed and engine rotation condition and detect the amount of rainwater and other liquids on a steady and stable road surface such as asphalt road surface or concrete road surface with high accuracy. It is intended to be provided.

[0007]

In order to solve the above-mentioned problems, a vehicle road surface state detecting device according to claim 1 of the present invention is used for running a vehicle as shown in the basic configuration diagram of FIG. 1a. Of the running state sound detection means for detecting the running state sound detecting means for detecting the road noise and splash sound generated together, the running state detecting means for detecting the running state of the vehicle, and the running state sound detection value detected by the running state sound detecting means. Based on the difference value regarding the sound pressure between the running state sound detection value in a preset predetermined frequency range and the running state sound reference value corresponding to the running state detection value detected by the running state detection means, And a road surface liquid amount calculating means for calculating the amount of the liquid material on the stable road surface.

The vehicle road surface state detecting device according to claim 2 of the present invention, as shown in the basic configuration diagram of FIG. 1b, has a running condition sound including at least road noise and splash sound accompanying the running condition of the vehicle. A running state sound detecting means for detecting the running state sound, a running state detecting means for detecting a running state of the vehicle, and a running state sound detection value detected by the running state sound detecting means within a predetermined frequency range set in advance. On the basis of the difference value regarding the sound pressure between the traveling state sound detection value and the traveling state sound reference value corresponding to the traveling state detection value detected by the traveling state detection means, the friction coefficient state of the road surface which is constantly stable Road surface friction coefficient state calculating means for calculating

A vehicle road surface condition detecting device according to a third aspect of the present invention comprises the road surface liquid amount calculating means and the road surface friction coefficient state calculating means, as shown in the basic configuration diagram of FIG. 1c, The road surface liquid amount calculation means is such that the sound pressure of the running state sound detection value in a predetermined frequency range set in advance for calculating the amount of the liquid substance on the road surface in a predetermined running state,
When there is a relatively increasing tendency relative to the sound pressure of the running state sound detection value in a preset predetermined frequency range for calculating the friction coefficient state of the road surface, the liquid substance on the road surface Either one or both of the traveling state sound detection value in a predetermined frequency range set in advance for calculating the amount and the traveling state sound reference value according to the traveling state detection value detected by the traveling state detection means. The present invention is characterized by including a rainfall-sound pressure correction means for correcting the calculated value obtained from the sound pressure.

A vehicle road surface condition detecting device according to a fourth aspect of the present invention, as shown in the basic configuration diagram of FIG.
As the traveling state detecting means, at least a vehicle speed detecting means for detecting a vehicle speed is provided, and the road surface liquid amount calculating means or the road surface friction coefficient state calculating means is adapted to perform the traveling based on the vehicle speed detection value detected by the vehicle speed detecting means. A running state sound detection value within a preset predetermined frequency range among the running state sound detection values detected by the state sound detecting means, and a running state according to the running state detection value detected by the running state detecting means. The present invention is characterized in that a vehicle speed / sound pressure correction means for correcting the calculated value obtained from the sound pressure of either one or both of the sound reference values is provided.

The road surface condition detecting means for a vehicle according to claim 5 of the present invention, as shown in the basic configuration diagram of FIG.
The traveling state detection means includes at least a vehicle speed detection means for detecting a vehicle speed and an engine rotation state detection means for detecting an engine rotation state, and is used in the road surface liquid amount calculation means or the road surface friction coefficient state calculation means. The running state sound reference value according to the running state detection value is composed of running state sounds when running on a dry road surface with a preset road friction coefficient state at least at a predetermined vehicle speed and a predetermined engine rotation state. It is characterized by.

[0012]

With the above-described structure, in the vehicle road surface condition detecting device according to claim 1 of the present invention, the road surface liquid amount calculating means travels according to the traveling state detection value detected by the traveling state detecting means. A state sound reference value is set, and the running state sound reference value and the running state sound detection value including road noise and splash sound accompanying at least the running state of the vehicle detected by the running state sound detecting means are used to determine the road surface. The sound pressure of a preset predetermined frequency band in which the vibration component related to the splash sound dependent on the above liquid amount mainly exists is calculated, and the sound of the running state sound detection value and the running state sound reference value in this frequency band is calculated. Integrated value difference of pressure, maximum value difference, average value difference,
When the difference value such as the representative value difference is calculated, this sound pressure difference value has a unique correlation with the liquid amount on the road surface, and therefore the liquid amount on the road surface can be calculated from the sound pressure difference value.

Further, in the road surface condition detecting device for a vehicle according to claim 2 of the present invention, the road surface friction coefficient state calculating means determines the traveling state sound according to the traveling state detection value detected by the traveling state detecting means. A reference value is set, and the running state sound reference value and the running state sound detection value including road noise and splash sound accompanying at least the running state of the vehicle detected by the running state sound detecting means are used to determine the road surface The sound pressure of a preset predetermined frequency band in which the vibration component mainly related to the road noise depending on the friction coefficient state mainly exists is calculated, and the sound pressure between the running state sound detection value and the running state sound reference value in this frequency band is calculated. When the difference values such as the integrated value difference, the maximum value difference, the average value difference, and the representative value difference are calculated, this sound pressure difference value has a unique correlation with the friction coefficient state of the road surface. It can be calculated the coefficient of friction conditions.

Further, the running state sound reference value corresponding to the running state detection value is set to a preset road surface friction coefficient as described in, for example, a vehicle road surface state detecting device according to a fifth aspect of the present invention. If the dry road surface in the state is composed of at least a running state sound when running at a predetermined vehicle speed and a predetermined engine rotation state, a sound pressure difference between the running state sound detection value and the running state sound reference value in the predetermined frequency band. Since the engine rotation state dependency and the vehicle speed dependency of the value can be eliminated or almost eliminated, the calculation accuracy of the friction coefficient state of the road surface is improved.

According to a third aspect of the present invention, there is provided the road surface fluid amount calculating means, which has both the road surface liquid amount calculating means and the road surface friction coefficient state calculating means. The rainfall-sound pressure correction means is operated in a predetermined traveling state such as the predetermined vehicle speed or the predetermined engine rotation state,
The sound pressure integral value of the traveling state sound detection value related to the splash sound becomes larger than the sound pressure integral value of the traveling state sound detection value due to road noise, and the amount of the liquid substance on the road surface is calculated. When it is determined that the sound pressure of the running state sound detection value for doing is relatively increasing as compared to the sound pressure of the running state sound detection value for calculating the friction coefficient state of the road surface, In order to correct the sound pressure of either one or both of the running state sound reference values or the calculated value of the difference value between the both, this correction is performed so that the amount of rainfall and the liquid matter on the road surface are corrected. According to the uniqueness with the increase amount of the running state sound detection value for calculating the amount, if the increase amount of the running state sound detection value due to the rainfall amount is removed, the road surface liquid amount calculating means calculates It is possible to further improve the calculation accuracy of the liquid amount on the road surface.

Further, in the vehicle road surface condition detecting device according to a fourth aspect of the present invention, the vehicle speed / sound pressure correcting means provided in the road surface liquid amount calculating means or the road surface friction coefficient state calculating means is preset. The vehicle speed with respect to the calculated value of the sound pressure of one or both of the traveling state sound detection value in the predetermined frequency range and the traveling state sound reference value according to the traveling state detection value, or the difference between the two. In order to make a correction based on the vehicle speed detection value detected by the detection means, this correction is performed according to the uniqueness between the vehicle speed and the increase / decrease amount of the running state sound detection value in each frequency range. If the increase / decrease amount of the detected value is removed, the calculation accuracy of the liquid amount on the road surface calculated by the road surface liquid amount calculation means and the calculation coefficient of the friction coefficient state of the road surface calculated by the road surface friction coefficient state calculation means is further improved. Can be improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle road surface condition detecting device of the present invention will be described in detail below with reference to the drawings. 2 to 8 show a first embodiment in which the vehicle road surface condition detecting device of the present invention is applied to an automatic traveling control device capable of following a preceding vehicle, and basically, it corresponds to an increase in vehicle speed. Control is performed to follow the preceding vehicle so as to maintain the increased target vehicle distance.

The vehicle applied to this embodiment is based on a rear-wheel-drive front-mounted engine, a so-called FR vehicle. In the figure, 10FL and 10FR indicate front left wheels which are non-driving wheels, and front right wheels, 10RL and 10RR indicate rear left wheels and rear right wheels which are driving wheels. The basic structure thereof will be briefly described. The engine 20 is vertically installed in front of the vehicle, that is, the output shaft is arranged so as to match or substantially match the front-rear direction of the vehicle. The transmission 14 is arranged in series with the engine 20 via a torque converter (not shown). The rotational driving force of the engine 20 appropriately decelerated by the automatically selected gear ratio of the automatic transmission 14 is the propeller shaft 22 arranged in the vehicle front-rear direction or substantially the front-rear direction, and the rear wheel differential device. 24, the rear left and right wheels 10RL and 10RR, which are transmitted to the rear left and right drive shafts 12 via so-called rear differentials and are connected to these drive shafts 12, are rotationally driven.

On the other hand, a steering device (not shown) is connected to each of the front left and right wheels 10FL and 10FR. If necessary, the steering device includes an automatic steering control device for the preceding vehicle following control. You may install in parallel. In the engine 20,
An engine rotation control device for controlling the output by controlling the rotation speed or rotation speed of the engine 20 is provided. This engine rotation control device
By controlling the opening of the throttle valve separately from the pedal input, it is possible to cause the engine 20 to exert a driving force required for a desired vehicle speed, acceleration and the like. Specifically, in response to an acceleration command from the engine rotation control unit 21, the step motor 45 is electrically rotationally controlled, and the throttle valve 44 provided in the intake pipe line 36.
The throttle opening of is increased or decreased. A throttle sensor 42 is provided in the throttle valve 44 in the figure, and this throttle sensor 42 detects the throttle opening TH of the throttle valve 44. Also, the input shaft of the coupling such as the torque converter,
That is, the rotation speed of the output shaft of the engine 20 is detected by the engine rotation speed sensor 38 as the engine rotation speed N _{E including} a pulse signal corresponding to the engine rotation speed. Further, in the present embodiment, the accelerator opening S _ACC output from the accelerator sensor 47 provided on the accelerator pedal 46 is 0/8 to a digital value of 0/8 when digitally converted by an A / D converter 83B described later. 8/8 a sign, a fully closed throttle opening amount S _ACC of the digital value 0/8 represents the fully opened accelerator opening S _ACC of the digital value 8/8.

On the other hand, the front and rear left and right wheels 10FL to 10R
The wheel cylinders 52FL are provided as Rs as braking devices.
.About.52RR and rotors 53FL to 53RR are provided. Among these, the braking force of the rear left and right wheels 10RL, 10RR by the braking device for the rear left and right wheels is a braking force control for controlling the fluid pressure (braking pressure) of the working fluid to the rear left and right wheel cylinders 52RL, 52RR. Controlled by the device. This braking force control device is provided with a pressure increasing function and a pressure reducing function, and controls the working fluid pressure by these functions so as to control the friction between the wheel cylinders 52RL, 52RR and the rotors 53RL, 53RR. Power can be controlled. Specifically, in response to a deceleration command from the braking force control unit 18, the solenoids 71 of the solenoid valves 70L and 70R in the control module 49 are each.
Also, the motor 74 of the pump 75 is electrically controlled so that the brake fluid pressure of the wheel cylinders 52RL, 52RR of the rear left and right wheels 10RL, 10RR, which are the drive wheels, is controlled by the fluid pressure of the master cylinder 51 corresponding to the pedaling force of the brake pedal 50. Pressure P
_The pressure is controlled separately from _M. In addition, the hydraulic control valves 54, 54 in the figure are the rear left and right wheel cylinders 52RL, 52.
This is for effectively increasing or decreasing the brake fluid pressure of the RR. A pressure switch 77 in the figure is for detecting the accumulated pressure of the accumulator 73.
By the way, in this embodiment, the braking force of the rear left and right wheels, which are the driving wheels, is controlled to increase according to the deceleration command due to the distance relationship with the preceding vehicle, but the preceding vehicle follow-up device only needs to output the deceleration command. Therefore, the braking force of the non-driving wheels can be controlled to increase.

Further, wheel speed sensors 28FL to 28RR are provided on the wheels 10FL to 10RR, and the wheel speed sensors 28FL to 28RR are connected to the wheels 10FL to 28RR.
Pulse signal corresponding to the rotation speed of the FL~10RR is, the wheel speed detected value (hereinafter, simply referred to as wheel speed) Vw _i (i
= FL to RR) but is output to the follow-up running control unit 30 to be described later as the engine control unit 21 and by the mutual communication function with the braking force control unit 18, the wheel speed Vw _i Each of these controls It is also transmitted to the units 21 and 18. Therefore, the engine rotation control unit 2
1, the rear left and right wheels 10RL and 10RR, which are driving wheels, and the front left and right wheels 10, which are driven wheels, are subjected to arithmetic processing (not shown).
FL, to compare the wheel speed Vw _i with 10FR, the left and right wheels 10RL after a the drive wheels, when the slip amount of 10RR becomes too large, control to reduce the output of the engine 20 by the traction control function as described above Can be executed. Further, in the brake force control unit 18 compares the left and right wheels 10RL after a drive wheel by a not shown processing, 10RR and driven wheels in a left and right front wheels 10FL, the wheel speed Vw _i and 10FR,
When the slip amounts of the rear left and right wheels 10RL and 10RR, which are the drive wheels, become excessive, control for increasing the working fluid pressure to the rear left and right wheel cylinders 52RL and 52RR by the traction control function as described above is executed. Or the rear left and right wheel cylinders 5 by the anti-skid control function as described above.
Control for reducing the working fluid pressure to 2RL and 52RR can be executed.

The vehicle-to-vehicle distance is detected and a current vehicle-to-vehicle distance detection value (hereinafter also simply referred to as the current vehicle-to-vehicle distance) L consisting of a voltage signal proportional to the magnitude of the vehicle-to-vehicle distance is detected. , Follow-up traveling control unit 3 described later
An inter-vehicle distance sensor 40 that outputs toward 0 is provided. The inter-vehicle distance sensor 40 is composed of, for example, an ultrasonic range finder or the like, and outputs a signal having an analog voltage value corresponding to the current inter-vehicle distance to the follow-up traveling control unit 30 in this embodiment.

On the rear rear surface side of the wheel housing panel of the front right wheel 10FR of the vehicle, at least the road noise generated in the front right wheel 10FR and the front right wheel 10FR are generated.
The vibration of the wheel housing panel is detected by the splash sound of the water FR lifts up, and a running sound detection value (hereinafter, referred to as a running sound detection value composed of a voltage signal proportional to the magnitude of the vibration is detected.
A traveling sound sensor 39 that outputs S _P toward the following traveling control unit 30 described later.
Is provided. The running sound sensor 39 is composed of, for example, a vibration sensor using a piezoelectric element or the like, and in the present embodiment, a signal having an analog voltage value corresponding to the magnitude of vibration of the wheel housing panel is sent to the following running control unit. Output to 30.

Further, in the vehicle interior of the vehicle, a preceding vehicle following traveling select switch 26 is provided, for example, near the instrument panel. This select switch 2
From 6 onward, the follow-up running selection signal S consisting of a digital signal of logical value "1" in ON state and logical value "0" in OFF state
_F is output to the following traveling control unit 30 described later.

The following traveling control unit 30
As shown in FIG. 3, each wheel speed sensor 28FL ...
Wheel speed Vw _{FL to} Vw composed of pulse signals from 28RR
Frequency-voltage converter 81F for converting _RR into analog voltage
L to 81RR, A / D converters 82FL to 82RR for converting the wheel speeds Vw _{FL to} Vw _RR converted by these converters 81FL to 81RR into digital values, and an inter-vehicle distance L detected by the inter-vehicle distance sensor 40. And an A / D converter 83D that converts the digital value into a digital value and an A / D converter that converts the accelerator opening S _ACC detected by the accelerator sensor 47 into a digital value.
/ D converter 83B and the engine speed sensor 38
Engine speed N _E consisting of the pulse signal detected at
Frequency-voltage converter 85 for converting the voltage into an analog voltage,
An A / D converter 83C for converting the engine speed N _E converted by the converter 85 into a digital value, and an A / D conversion for converting the traveling sound S _P detected by the traveling sound sensor 39 into a digital value. 83E and each A / D converter 82F
L～82RR, and a microcomputer 84 for the follow-up run selection signal S _F of the converted output signal and the previous run vehicle following cruise selection switch 26 of 83B~83E is input, the digital value outputted from the microcomputer 84 The vehicle-to-vehicle distance deviation ΔL of the engine rotation control unit 21 connected by a digital communication network.
In addition, according to a command value input to the braking force control unit 18, processed by a microcomputer in an engine rotation control unit 21 (not shown), and output from a microcomputer, a drive signal output from a drive circuit (not shown) is used. The stepping motor 45 is drive-controlled, and the braking force is generated by a drive signal output from a drive circuit (not shown) in accordance with a command value output from the microcomputer which is arithmetically processed by the microcomputer in the braking force control unit 18 (not shown). The drive of the motor 74 and the solenoid valves 70L and 70R in the control module 49 is controlled.

Here, the follow-up traveling control unit 3
The microcomputer 84 in 0 has at least the input input.
Interface circuit 84a, output interface circuit 84
b, an arithmetic processing device 84c and a storage device 84d,
The arithmetic processing unit 84c includes the wheel speed sensors 28FL.
Wheel speed detection value Vw from ~ 28RR_FL~ Vw_RRUsing
Vehicle speed V including pseudo vehicle speed_CIs calculated, and
Follow-up traveling selection signal S from the rect switch 26_FIs logical
The value from the accelerator sensor 47 is ON when the value is "1".
Xcel opening S_ACCIs a fully closed state with digital value 0/8
The vehicle speed V_CAnd the engine speed sensor
Engine rotation speed N detected by service 38 _ERun according to
Traveling sound pressure reference value N₀Select and set the
Running sound S detected by the sound sensor 39_PFast Fourier transform
Frequency analysis by replacement etc. to obtain the traveling sound pressure detection value N
Therefore, the traveling sound pressure detection value N and the traveling sound pressure reference value N₀When
Of low frequency band and high frequency band that do not overlap each other
Integral value difference ΔN_R, ΔN_WCalculate the low frequency
Band running sound pressure integral value difference ΔN_RTo the friction coefficient of the road surface
In addition to calculating several states (hereinafter simply referred to as road surface μ)
High frequency band running sound pressure integrated value difference ΔN_WOn the road surface
Calculate the amount of water (hereinafter, simply referred to as road surface water amount) R
Using these road surface μ and road surface water amount R,
Correct the quasi value A and target inter-vehicle distance L^*Calculate this goal
Inter-vehicle distance L^*And the current distance detected by the inter-vehicle distance sensor 40.
Calculate the inter-vehicle distance deviation ΔL with the in-vehicle distance L and
The engine speed control unit
Appears on the knit 21 and braking force control unit 18.
Force

The storage device 84d is an arithmetic processing device 84.
A processing program and a control map necessary for the arithmetic processing of c are stored in advance, the processing results of the arithmetic processing device are sequentially stored, and the traveling sound pressure reference value N ₀ used in the arithmetic processing 84c is set to each vehicle speed V. _{C and} engine speed N _E
It is stored in advance for each. Next, the calculation of the road surface μ and the amount of water on the road surface of the forward running vehicle following automatic running control executed by the microcomputer 84 of the following running control unit 30 will be described.

For example, a special peripheral such as a microphone
Vibration consisting of the piezoelectric element or the like not subjected to wavenumber bandpass processing
The dynamic sensor is capable of detecting vibrations in a relatively wide frequency band.
I will pick it up. That is, the front right wheel 10F
Running mounted on the rear rear side of the wheel house panel of R
Running sound S of all frequency bands detected by the sound sensor 39 _P
Is lifted as the front right wheel 10FR rotates.
Water generated by collision with the wheel house panel
In addition to vibration components related to the plush sound, road noise
Vibration components related to
Dynamic components are also mixed.

Therefore, when frequency analysis is performed on the traveling sound S _P by Fourier transform or the like, here, as shown in FIG. 4, with a boundary of about 100 Hz as a boundary, a vibration related to road noise is generated in a lower frequency band. There are ingredients,
Since there is a vibration component related to the splash sound in a frequency band higher than this, it is possible to individually extract the vibration component related to the road noise and the vibration component related to the splash sound from the traveling sound pressure N of each frequency band. However, the vibration component caused by the rotation state of the engine exists in a wide frequency band from the first order to the higher order according to the rotation state, and is added in each frequency band of the traveling sound pressure N. Strictly speaking, it must be removed,
Further, since both the splash sound and the road noise depend on the vehicle speed, the road surface μ and the road surface water amount R may be erroneously detected unless these are taken into consideration.

Therefore, a predetermined vehicle speed and a predetermined engine speed are set.
In the rolling state, for example, the road surface μ is a preset value μ₀of
When traveling on a completely dry road surface, the traveling sound pressure at that time is the traveling sound pressure
Reference value N₀As the difference with the traveling sound pressure detection value N on the road surface
In considering about the
Low frequency where vibration components related to vibration are mainly present
The band is 0 to 100 Hz and is related to the splash sound.
The high frequency band where the vibration component that mainly exists is 1
Run at 0 to 200Hz for more accuracy
Sound pressure reference value N₀And the traveling sound pressure detection value N in each frequency band
Integral value difference ΔN_R, ΔN_WWhen you calculate
Low frequency band running sound pressure integral value difference ΔN _RAnd the running
Sound pressure reference value N₀Constant value for setting μ₀To
Between the positive value Δμ, a simple increase as shown in FIG.
A correlation consisting of an upwardly convex characteristic curve was found. Therefore,
The road surface μ is the constant value road surface μ₀And the correction value Δμ
Can be calculated from In addition, the high frequency band running
Line sound pressure integrated value difference ΔN_WBetween the road surface water quantity R and
It consists of a simple increasing downward convex curve as shown in b.
Correlation was found. That is, various vehicle speeds and engine rotations
Running sound pressure reference value N according to the state₀Have in advance
Corresponding to the current vehicle speed and engine speed
Running sound pressure reference value N₀Is selected, and this running sound pressure reference value N₀
And the actual traveling sound pressure detection value N in each frequency band
Minute value difference ΔN_R, ΔN_WCalculate and run each frequency band
Sound pressure integral value difference ΔN_R, ΔN_WFrom the road surface according to the above correlation
By calculating μ and road surface water amount R, the engine rotation
Not only can the vibration component caused by the
To some extent the vehicle speed dependence of noise and splash noise is eliminated
can do. Here, each frequency band product obtained
Minute value difference ΔN_R, ΔN_WTo obtain road surface μ and road surface water amount R
In order to do this, we decided to use the map shown in FIG.
However, you may follow the arithmetic expression which made this correlation into a mathematical expression.

However, focusing on the integrated value of the traveling sound pressure N in all frequency bands, for example, as shown in FIG. 6b, the vehicle is traveling at a relatively medium speed, and the vehicle is traveling at a lower speed than this. In a relatively low speed running state where the vehicle is running at a relatively low speed, the proportion of the sound pressure in the relatively low frequency band due to the engine rotation state is higher than the proportion of the sound pressure in the high frequency band. In a relatively high-speed running state where the vehicle is running at a high speed, the proportion of high frequency band sound pressure, which is also caused by the engine rotation state, is higher than the proportion of low frequency band sound pressure. Of course, the traveling sound pressure reference value N
_{Although 0 is} also affected by this, the traveling sound pressure detection value N and the traveling sound pressure reference value N _{0 in} the low frequency band for calculating or detecting the road surface μ from the vibration component related to the road noise.
The difference ΔN _{R in} the integrated value of is compared to the difference ΔN _W in the high frequency band running sound pressure for calculating or detecting the road surface water amount R from the vibration component related to the splash sound, in the low speed running state. It appears large and small in a high-speed running state, and the running sound pressure integrated value difference ΔN _W in the high frequency band based on the integrated value difference ΔN _R between the running sound pressure detection value N in the low frequency band and the running sound pressure reference value N ₀ is ， It will show the opposite tendency.

In contrast to the vehicle speed dependence of the traveling sound pressure integral value differences ΔN _R , ΔN _W in each frequency band, in the present embodiment, the respective frequency traveling sound pressure integral value differences Δ as shown in FIG.
When the correlation between N _R , ΔN _W and the road surface μ correction value Δμ or the road surface water amount R is set to be slightly closer to the high speed running state and the vehicle speed V _C is smaller than a certain predetermined vehicle speed threshold V _C0 , the road surface μ and the road surface μ It was decided not to calculate or detect the water amount R. This is because, for example, the vehicle speed threshold value V _C0 is 10 km / h or 15 km / h.
In low-speed running conditions such as this, the running stability of the vehicle will not be significantly impaired even if rainwater, etc. is present on a constantly stable road surface such as an asphalt road surface or a concrete road surface with a certain amount of water. When V _C decelerates and shifts to this low-speed running state, it is assumed that the road surface μ and the road surface water amount R that have been calculated or detected until then do not change significantly, and the target inter-vehicle distance L ^* to be described later is set. If it is set, no significant performance degradation will occur in the forward running vehicle following automatic running control.

Then, in the forward traveling vehicle following automatic traveling control of the present embodiment, the target inter-vehicle distance L ^* is set as follows. First, on a stable dry road surface, it is known about an ideal that the inter-vehicle distance is set so as to be proportional to the square value of the vehicle speed. Therefore, for example, as shown in FIG. 7, a downward convex characteristic that simply increases with the vehicle speed V _C. The reference value A of the target inter-vehicle distance is calculated and set according to the correlation represented by the curve. This target inter-vehicle distance reference value A is an ideal inter-vehicle distance when traveling on a completely dry road surface having a constant value road surface μ ₀ equivalent to the setting of the traveling sound pressure reference value N _O. It is set in consideration of various vehicle characteristics including the control response of automatic vehicle following control. When the vehicle speed V _C is “0”,
That is, the intercept of the characteristic curve of the target inter-vehicle distance reference value A is set so that the vehicle can be stopped or started with an ideal inter-vehicle distance even when the vehicle is stopped.

By correcting the target inter-vehicle distance reference value A according to the road surface μ and the road surface water amount R,
Calculate and set an appropriate target inter-vehicle distance L ^* for traveling on the current road surface. First, regarding the road surface μ, it is ideal that the inter-vehicle distance becomes longer as the road surface μ is lower in view of traveling stability during braking / driving. Therefore, the target inter-vehicle distance reference value A is set to the constant value road surface μ of the road surface μ. _By dividing by the ratio to _{0, the} appropriate target inter-vehicle distance L ^* on the road surface μ can be corrected. On the other hand, the road surface water amount R should be set in a direction in which the target inter-vehicle distance is lengthened as the road surface water amount increases in order to avoid, for example, a hydroplaning phenomenon. However, as the amount of water on the road surface increases, for example, when the lower part of the tire is submerged in water, the running resistance increases, and as a result of increasing the target inter-vehicle distance as described above, the engine output decreases. When the vehicle is controlled in the direction, it is considered that the vehicle may not be able to maintain the vehicle speed against the running resistance, and a significant feeling of deceleration may occur together with the running resistance. Therefore, in the present embodiment, the correction of the target inter-vehicle distance reference value A for the road surface water amount R is performed in consideration of these, at least an optimum correction coefficient is obtained according to the arithmetic expression f (R) for the road surface water amount R, and the correction coefficient is calculated as described above. By multiplying the target inter-vehicle distance reference value A, an appropriate target inter-vehicle distance L ^* at the road surface water amount is calculated.

Next, the road surface μ, road surface water amount R,
The calculation processing executed by the microcomputer 84 of the following traveling control unit 30 in order to calculate the target inter-vehicle distance L ^{* and the} inter-vehicle distance deviation ΔL will be described with reference to the flowchart of FIG. The definition of each frequency band in the figure is as described above. Further, although no step is specifically provided for transmitting / receiving the stored data or the calculated data, the data such as the road surface μ and the road surface water amount R calculated by this arithmetic processing is updated in the storage device 84c at any time, and the data of the arithmetic processing is It is assumed that the latest data is transmitted to the buffer or the like of the arithmetic processing unit 84c when the execution is started. Therefore, when the data such as the road surface μ and the road surface water amount R is not newly calculated, the arithmetic processing may be executed using the latest updated storage data of the road surface μ and the road surface water amount R. Further, it is assumed that the calculated data and the stored data are cleared to a constant value road surface μ ₀ and the road surface water amount R to “0” when the key switch is turned off or turned on again.

This arithmetic processing is performed, for example, in the arithmetic processing unit 84c of the microcomputer 84 by 5
It is executed by a timer interrupt process at every predetermined time ΔT of about msec. First, in step S1, the follow-up travel selection signal S _F from the follow-up travel select switch 26 is read. Next, the process proceeds to step S2, and the following traveling selection signal S _F
Is in the ON state of "1", and if the following traveling selection signal _SF is in the ON state of "1", the process proceeds to step S3, and if not, the process returns to the main program. To do.

In step S3, the accelerator
Accelerator opening S detected by service 47 _ACCRead in. next
The process proceeds to step S4, and the accelerator opening S_ACCDe
Determine whether the digital value is 0/8 fully closed,
The accelerator opening S_ACCIs a digital value and is 0/8 fully closed
If it is in a state, the process proceeds to step S5, and if not,
If so, return to the main program.

[0038] At the step S5, each wheel speed Vw _i detected by the wheel speed sensors 28FL~28RR (i
= FL to RR). At the next step S6, the calculated set vehicle speed V _C using the respective wheel speed Vw _i. Note that the wheel speed Vw is when calculating the vehicle speed V _C from _i, for example, before a driven wheel left and right wheel speeds Vw _FL, V
Toka using the average value of w _FR, the smallest select low wheel speed Vw _iL during acceleration, Toka selects the largest select high wheel speed Vw _iH on the vehicle speed V _C during deceleration, further these elected wheel speed Vw _i The existing vehicle speed calculating means, such as adding the integrated value of the acceleration with an appropriate offset amount added thereto, can be applied.

Next, in step S7, the vehicle speed V
_C it is determined whether the the predetermined vehicle speed threshold V _C0 above, when the vehicle speed V _C is the vehicle speed threshold V _C0 or proceeds to step S8, otherwise the step S9
Move to In step S8, the engine rotation speed N _E detected by the engine rotation speed sensor 38 is read, and then the process proceeds to step S10.

In step S10, the vehicle speed V_COver
And engine speed N_EVehicle speed and engine rotation equivalent to
Traveling sound pressure reference value N at speed₀The storage device 84
Various running sound pressure reference value data banks stored in d
After selecting from, the process proceeds to step S11. In addition, before
Based on the storage capacity of the storage device 84d and the like, the traveling sound pressure reference value N ₀
The number of data is limited, and as a result, the same vehicle speed and
Running sound pressure reference value N according to engine speed₀Can be elected
If it does not exist, for example, the running sound that most closely resembles it
Pressure reference value N₀Or choose two
Running sound pressure reference value N₀To the appropriate running sound pressure level.
Quasi value N₀It is also possible to calculate

In step S11, the traveling sound S _P detected by the traveling sound sensor 39 is read, and then the process proceeds to step S12. In the step S12, the traveling sound S _P is cut out in time by, for example, Fourier transform or the like, frequency-analyzed, the traveling sound pressure detection value N is calculated, and then the process proceeds to step S13.

In step S13, the traveling sound pressure detection is performed.
Output value N and traveling sound pressure reference value N₀Using the low frequency
Band running sound pressure integral value difference ΔN_RAnd high frequency band running sound pressure
Integration value difference ΔN_WAfter calculating and setting, go to step S14
Transition. In step S14, the low frequency band
Running sound pressure integrated value difference ΔN_RThe correction value Δμ corresponding to
5a is calculated and set from the correlation shown in FIG.
μ ₀To calculate the road surface μ, and then step S15
Move to.

In step S15, the road surface water amount R corresponding to the high frequency band traveling sound pressure integral value difference ΔN _W is calculated from the correlation shown in FIG.
Move to In step S9, the target inter-vehicle distance reference value A corresponding to the vehicle speed V _C is calculated and set from the correlation shown in FIG.

Next, in step S16, the target inter-vehicle distance L ^* is calculated and set with respect to the target inter-vehicle distance reference value A using the road surface μ and the road surface water amount R. Next, in step S17, the current inter-vehicle distance L detected by the inter-vehicle distance sensor 40 is read.

Next, in step S18, the inter-vehicle distance deviation ΔL is calculated by subtracting the current inter-vehicle distance L from the target inter-vehicle distance L ^* . Next, in step S19,
It is determined whether or not the absolute value | ΔL | of the inter-vehicle distance deviation is equal to or greater than a preset dead zone threshold L ₀ , and when the absolute value | ΔL | of the inter-vehicle distance deviation is equal to or greater than the dead zone threshold L _0. Moves to step S20, otherwise returns to the main program.

In step S20, the inter-vehicle distance deviation is
The difference ΔL is calculated as the engine rotation control unit 21.
And output to the braking force control unit 18
To return to the main program. According to this arithmetic processing
For example, the follow-up traveling select switch 26 is OFF.
When the following drive select switch 26 is ON
Therefore, the follow-up traveling selection signal S _FIs a logical value "1"
Also, by pressing the accelerator pedal 46, the accelerator opening
S_ACCWhen is a digital value that is 1/8 or more,
Is the target inter-vehicle distance L^*Or the inter-vehicle distance deviation ΔL is calculated or
Engine rotation control unit 21 and braking force
Since it is not output to the control unit 18,
The preceding vehicle following automatic traveling control is not executed.

On the other hand, the key switch of the vehicle is turned on again, the follow-up travel select switch 26 is in the ON state, the follow-up travel selection signal S _F has the logical value "1", and the accelerator pedal 46 is not depressed. , Even when the accelerator opening S _ACC is in a fully closed state with a digital value of 0/8, the vehicle speed V
_As long as _C does not exceed the vehicle speed threshold V _C0 , the above step S
In step S9, the target inter-vehicle distance reference value A corresponding to the current vehicle speed V _C is calculated and set. At this time, by turning the key switch on again, the road surface μ of the storage device 84c
Since the stored data of the road surface water amount R and the road surface water amount R has been cleared, the target inter-vehicle distance reference value A is set as it is to the target inter-vehicle distance L ^* without correction according to the road surface μ and the road surface water amount R. The target inter-vehicle distance L ^* and the current inter-vehicle distance L
When the absolute value | ΔL | of the vehicle-to-vehicle distance deviation between and is greater than or equal to the dead zone threshold L ₀ , the vehicle-to-vehicle distance deviation ΔL is output to the engine rotation control unit 21 and the braking force control unit 18.

Then, in the engine rotation control unit 21, if the inter-vehicle distance deviation ΔL is a positive value, the throttle opening is set so that the throttle valve 44 is opened greatly according to the magnitude of the inter-vehicle distance deviation ΔL. If the deviation ΔL is a negative value, the throttle opening is set so that the throttle valve 44 is largely closed according to its value, and the rotation angle (the number of steps) of the step motor 45 that achieves these throttle openings is set. The corresponding drive signal is output. On the other hand, the braking force control unit 18
Then, when the inter-vehicle distance deviation ΔL is a negative value, the braking force control module 49 is set so that the working fluid pressure to the wheel cylinders 52RL and 52RR increases according to the negative value.

From this state, when the vehicle speed V _C is further increased to the vehicle speed threshold V _C0 or more, the running sound pressure reference value N ₀ corresponding to the current vehicle speed V _C and the current engine speed N _E is selected, and The frequency band running sound pressure integrated value differences ΔN _R and ΔN _W are calculated, and the road surface μ and the road surface water amount R are calculated according to these values. Then, the target inter-vehicle distance reference value A calculated and set according to the current vehicle speed V _C is corrected according to the road surface μ and the road surface water amount R to set the target inter-vehicle distance L ^*. When the absolute value | ΔL | of the vehicle-to-vehicle distance deviation between L ^* and the current vehicle-to-vehicle distance L is greater than or equal to the dead zone threshold L ₀ , this vehicle-to-vehicle distance deviation ΔL is determined by the engine rotation control unit 21 and the braking force control unit 18.
Is output to.

In the engine rotation control unit 21 and the braking force control unit 18, the braking / driving force control according to the inter-vehicle distance deviation ΔL is performed in the same or almost the same manner as described above to achieve the target inter-vehicle distance L ^*. However, the braking / driving force control is performed for each wheel 10 especially when the road surface μ is low or the road surface water amount R is large.
If a slip occurs on FL-10RR,
The braking / driving force control amount is adjusted and controlled by the pressure increasing function and the like of each control unit 21, 18.

At this time, in the automatic traveling control for following the preceding vehicle
Indicates that the correction was made according to the road surface μ and the road surface water amount R.
Becomes, vehicle speed V_CIs already equivalent to the medium / high speed running state
Therefore, the road surface μ
The target inter-vehicle distance L in anticipation of a decrease and an increase in the road surface water amount R
^*Can be set. From this state, the vehicle speed V
_CIs the vehicle speed threshold V_C0If less than V _CBut
Vehicle speed threshold V_C0If the road surface μ and the road surface water amount R
The target is updated because it is updated and stored in the storage device 84c.
This road surface μ and road surface water amount R are compared with the inter-vehicle distance reference value A.
The target inter-vehicle distance L is corrected according to^*Is set and
The inter-vehicle distance deviation ΔL is the engine speed control unit.
To the control unit 21 and the braking force control unit 18.
The same as or almost the same as the above.
Braking / driving force control is performed according to ΔL, and the target inter-vehicle distance is
L^*Is achieved.

As described above, the present embodiment is an implementation of the vehicle road surface condition detecting device according to claims 1 and 2 and 5 of the present invention, and the wheel speed sensors 28FL to 28R shown in FIG.
R and step S5 and step S6 of the calculation process of FIG.
Corresponds to vehicle speed detecting means in the vehicle road surface condition detecting device of the present invention, and similarly, hereinafter, the engine speed sensor 38 of FIG. 2 and step S8 of the arithmetic processing of FIG. 8 correspond to engine speed detecting means. Running state detection means is configured to include the vehicle speed detection means and the engine rotation state detection means,
The running sound sensor 39 of FIG. 2 and step S11 of the calculation process of FIG. 8 correspond to the running state sound detecting means, and steps S10, S12, and S1 of the calculation process of FIG.
3, step S14 corresponds to the road surface friction coefficient state calculating means, and step S10 and step S1 of the arithmetic processing of FIG.
2, step S13 and step S15 correspond to the road surface liquid amount calculation means.

Next, FIGS. 9 to 11 show a second embodiment of the vehicle road surface condition detecting device of the present invention. In the second embodiment, only the arithmetic processing executed by the microcomputer in the follow-up traveling control unit 30 is different from that of the first embodiment. Therefore, the other components are given the same reference numerals as those in the first embodiment. Detailed description thereof will be omitted. In the microcomputer 84 in the follow-up traveling control unit 30, the arithmetic processing unit 84c has the wheel speed detection values Vw _FL to VV from the wheel speed sensors 28FL to 28RR.
The vehicle speed V _{C including the} pseudo vehicle speed is calculated by using w _RR, and the follow-up travel selection signal S _F from the follow-up travel select switch 26 is in the ON state of the logical value “1” and the accelerator opening degree from the accelerator sensor 47 is set. When S _ACC is in a fully closed state with a digital value of 0/8, the vehicle speed V _C and the engine speed N _E detected by the engine speed sensor 38 are detected.
Elected sets the driving sound pressure reference value N ₀ corresponding to preparative, its running sound pressure detection value N the running noise S _P detected by the running sound sensor 39 contrary to frequency analysis by fast Fourier transform or the like And the running sound pressure integrated value differences ΔN _R and ΔN _W between the running sound pressure detection value N and the running sound pressure reference value N ₀ in the low frequency band and the high frequency band that do not overlap with each other are calculated. The correction coefficients C _NRV and C _NWV of the traveling sound pressure _integrated value differences of the respective frequency bands corresponding to the vehicle speed V _C are calculated and set, and the traveling sound pressure _integrated value difference ΔN _{W of the} high frequency band and the traveling sound pressure _integration of the low frequency band are integrated. The correction coefficient C _NWC of the running sound pressure _integral value difference in the high frequency band is calculated and set from the deviation ε from the value difference ΔN _R, and the low frequency band corrected using these correction coefficients C _NRV , C _NWV and C _NWC. From the running sound pressure integrated value difference ΔN _R , the friction coefficient state (below Below, simply referred to as road surface μ) is calculated, and the amount of water on the road surface (hereinafter simply referred to as road surface water amount) R is calculated from the high frequency band traveling sound pressure integrated value difference ΔN _W , and these road surface μ and using road water R, calculates the target inter-vehicle distance L ^* to correct the target inter-vehicle distance reference value a, the inter-vehicle distance between the target inter-vehicle distance L ^* and the inter-vehicle distance current inter-vehicle distance L detected by the sensor 40 The deviation .DELTA.L is calculated and is output as a digital value to the engine rotation control unit 21 and the braking force control unit 18 as it is.

Next, the calculation of the road surface μ and the amount of water on the road surface of the forward running vehicle following automatic running control executed by the microcomputer 84 of the following running control unit 30 will be described. For example, from the traveling sound S _P of the traveling sound sensor 39 composed of a piezoelectric element such as a microphone, the vehicle speed V
Running sound pressure in each frequency band in which fluctuations due to _C and the engine rotation state N _E are almost removed, specifically, a low frequency band in which vibration components related to road noise are mainly present and a high frequency band in which vibration components related to splash noise are mainly present. Since the basic principle of calculating or detecting the road surface μ and the road surface water amount R based on the integrated value differences ΔN _R , ΔN _W is similar to or substantially the same as that of the first embodiment, detailed description thereof will be omitted. .

In the vehicle speed dependence of the difference value of the traveling sound pressure in each frequency band as described above, the difference ΔN _{R in the} low frequency band traveling sound pressure value uniquely decreases as the vehicle speed V _C increases. And high frequency band running sound pressure integral value difference ΔN
_W increases uniquely as the vehicle speed V _C increases, and the mode of increase / decrease is the same when the vertical axis of the correlation characteristic of FIG. 9A is replaced by the low frequency band traveling sound pressure integral value difference ΔN _R. A curve formed by an inverse ratio of the characteristic curve of FIG. 9B, and a curve formed by an inverse ratio of the characteristic curve of FIG. 9B when the vertical axis of the correlation characteristic of FIG. 9B is replaced with the high frequency band traveling sound pressure integrated value difference ΔN _W. Appears in.
Therefore, in this embodiment, the vehicle speed V shown by the curve in FIG.
_A correction conversion is performed to remove the vehicle speed dependency by multiplying the vehicle speed correction coefficient C _NRV of the low frequency band running sound pressure _integral value difference depending on C by the simply calculated low frequency band running sound pressure _integral value difference ΔN _R. Low frequency band running sound pressure integrated value difference ΔN _R
On the other hand, the vehicle speed correction coefficient C of the high frequency band traveling sound pressure integrated value difference depending on the vehicle speed V _C shown by the curve in FIG.
_{By multiplying NWV} by the simply calculated high frequency band running sound pressure _integrated value difference ΔN _W , the similarly converted high frequency band running sound pressure integrated value difference ΔN _W is obtained. That is, by matching the vehicle speed V _C to obtain the road surface μ and the road surface water R in correlation characteristic of FIG. 5, the correction coefficient C _NRV of FIG. 9, and a vehicle speed V _C that is corrected converted by C _NWV, each It is possible to almost completely eliminate the vehicle speed dependence of the frequency band traveling sound pressure integrated values ΔN _R , ΔN _W , and improve the calculation accuracy of each road surface μ and road surface water amount R.

Further, it has been found that, when it rains, the vibration component accompanying the rain sound mainly affects the traveling sound pressure in the high frequency band where the vibration component related to the splash sound exists. That is, the integrated value of the running sound pressure in the high frequency band when the amount of rainfall is small as shown by the alternate long and short dash line in FIG. 10 is integrated with the integrated value of the running sound pressure in the high frequency band when the amount of rainfall is large as shown by the solid line in FIG. The value increases, and as a result, the high frequency band traveling sound pressure integrated value difference ΔN _W increases as the rainfall increases. On the other hand, the low frequency band traveling sound pressure integral value difference ΔN _R in which a vibration component mainly related to road noise is present is constant or almost constant regardless of the rainfall amount. Deviation ε (= ΔN _W −Δ of running sound pressure integrated value difference ΔN _R , ΔN _W in high and low frequency bands
When a correlation with N _R ) was obtained, a unique correlation as shown in FIG. 11 was found between them. That is, as described above, the road surface μ is constant and the vehicle speed V _C and the engine speed N are constant.
Under the condition of _E , in contrast to the low frequency band traveling sound pressure integral value difference ΔN _R which appears constant or almost constant, only the high frequency band traveling sound pressure integral value difference ΔN _W increases with the increase in rainfall. Become. Therefore, the high-frequency band running sound pressure integrated value difference ΔN
_In order to remove the influence of rainfall from _W and make the correlation characteristic of FIG. 5 constant, when the deviation ε of the high and low frequency band traveling sound pressure integral value difference is “0” as shown in FIG. The correction coefficient C _NWC, which is “1” and increases with the deviation ε of the difference between the high and low frequency band traveling sound pressure integrated values, that is, uniquely decreases with an increase in rainfall. By multiplying the integrated value difference ΔN _W , the amount of rainfall is “0”
Since it is possible to obtain the high-frequency band traveling sound pressure integral value difference ΔN _W that has been corrected and converted to the state at the time, the calculation accuracy of the road surface water amount R can be improved.

The road surface μ calculated or detected in this way
Further, the principle of setting the target inter-vehicle distance L ^{* in} the forward vehicle following automatic traveling control of the present embodiment using the road surface water amount R is the same as or substantially the same as the principle of setting the target inter-vehicle distance L ^* of the first embodiment. The detailed description is omitted because it is similar. Then, in order to calculate the road surface μ, the road surface water amount R, the target vehicle-to-vehicle distance L ^{* and the} vehicle-to-vehicle distance deviation ΔL, the arithmetic processing executed by the microcomputer 84 of the follow-up traveling control unit 30 is performed according to the flowchart of FIG. explain. The definition of each frequency band in the figure is as described above. In addition, although there are no particular steps to exchange stored data or calculated data,
The data such as the road surface μ and the road surface water amount R calculated by this arithmetic processing are updated in the storage device 84c at any time, and the latest data are transmitted to the buffer or the like of the arithmetic processing device 84c when the execution of the arithmetic processing is started. I shall. Further, it is assumed that the calculated data and the stored data are cleared to a constant value road surface μ ₀ and the road surface water amount R to “0” when the key switch is turned off or turned on again.

This arithmetic processing is performed, for example, in the arithmetic processing unit 84c of the microcomputer 84 by, for example, 5
It is executed by the timer interrupt processing at every predetermined time ΔT of about msec., but the respective arithmetic processings from step S21 to step S26 shown in the figure are performed from step S1 to step S6 of the arithmetic processing of FIG. 8 of the first embodiment. Since it is similar to the above, detailed description thereof will be omitted.

Next, in step S27, the engine speed N _E detected by the engine speed sensor 38 is read. Next, in step S28, the traveling sound pressure reference value N ₀ at the vehicle speed and the engine rotation speed equivalent to the vehicle speed V _C and the engine rotation speed N _E is set to the various traveling sounds stored in the storage device 84d. Selected from the pressure reference data bank. Note that, as in the first embodiment, it is possible to calculate an appropriate traveling sound pressure reference value N ₀ by appropriately supplementing.

Next, the process proceeds to step S29, and the traveling is performed.
Running sound S detected by the sound sensor 39 _PRead in. Next
Go to step S30 and use, for example, Fourier transform.
The running sound S_PFrequency analysis
Then, the traveling sound pressure detection value N is calculated. Then step S
31, the running sound pressure detection value N and the running sound pressure base are transferred.
Quasi value N ₀To run in the low frequency band as described above.
Sound pressure integral value difference ΔN_RAnd high frequency band running sound pressure integrated value difference
ΔN_WIs calculated and set.

Next, in step S32, the vehicle speed V _C is used to calculate and set the vehicle speed correction coefficient C _NRV of the low frequency band traveling sound pressure _integral value difference by the map search of FIG. 9a or the like. Note that the vehicle speed correction coefficient C _NRV of the difference in the _integrated value of the low-frequency band traveling sound pressure may be calculated from an arithmetic expression. Next, the process proceeds to step S33, and the vehicle speed V _C
Using, the vehicle speed correction coefficient C _NWV of the high frequency band traveling sound pressure _integral value difference is calculated and set by the map search of FIG. 9B or the like. The vehicle speed correction coefficient C _NWV of the difference in the _integrated sound pressure values in the high frequency band may be calculated from an arithmetic expression.

Next, in step S34, the difference in high-frequency band traveling sound pressure integral value difference ΔN _R is subtracted from the high-frequency band traveling sound pressure integral value difference ΔN _W to obtain a deviation of the high-low frequency band traveling sound pressure integral value difference. Calculate ε. Next, in step S35, the rainfall correction coefficient C _NWC of the high frequency band traveling sound pressure integral value difference is obtained by the map search of FIG. 12 using the deviation ε of the high and low frequency band traveling sound pressure integral value difference. Calculate and set. The rainfall correction coefficient C _NWC of the difference in the integrated high-frequency sound pressure may be calculated from an arithmetic expression.

Next, in step S36, the vehicle speed correction coefficient C _{NRV for} the low-frequency band traveling sound pressure _integral value difference, the vehicle speed correction coefficient C _{NWV for} the high-frequency band traveling sound pressure _integral value difference, and the high frequency band. Using the rainfall correction coefficient C _NWC of the difference in running sound pressure value, the difference ΔN _R in low frequency band running sound pressure converted by the following equation 1 is converted into the high frequency running sound by high frequency band running by the following equation 2. Integrated pressure difference Δ
Calculate N _W respectively.

ΔN _R = C _NRV · ΔN _R (1) ΔN _W = C _NWV · C _NWC · ΔN _W (2) Next, the process proceeds to step S37 and the low frequency band traveling sound pressure is set. The correction value Δμ corresponding to the integrated value difference ΔN _R is calculated as shown in FIG.
It is calculated and set from the correlation shown in a.
_The road surface μ is calculated by adding to ₀ .

Next, in step S38, the road surface water amount R corresponding to the high frequency band traveling sound pressure integral value difference ΔN _W is set.
Is calculated and set from the correlation shown in FIG. Next, in step S39, the target inter-vehicle distance reference value A corresponding to the vehicle speed V _C is calculated and set from the correlation shown in FIG.
Next, in step S40, the target inter-vehicle distance L ^* is calculated and set with respect to the target inter-vehicle distance reference value A using the road surface μ and the road surface water amount R.

Next, in step S41, the current inter-vehicle distance L detected by the inter-vehicle distance sensor 40 is read.
Next, in step S42, the target inter-vehicle distance L ^{* is set.}
Then, the current inter-vehicle distance L is subtracted from the current inter-vehicle distance L to calculate the inter-vehicle distance deviation ΔL. Next, in step S43, the absolute value | ΔL | of the inter-vehicle distance deviation is set to the preset dead zone threshold L.
Determines whether a ₀ or more, the absolute value of the inter-vehicle distance deviation | [Delta] L | is the case where the dead zone threshold L ₀ or shifts to step S44, otherwise returns to the main program.

In step S44, the inter-vehicle distance deviation is
The difference ΔL is calculated as the engine rotation control unit 21.
And output to the braking force control unit 18
To return to the main program. According to this arithmetic processing
For example, the follow-up traveling select switch 26 is OFF.
When the following drive select switch 26 is ON
Therefore, the follow-up traveling selection signal S _FIs a logical value "1"
Also, by pressing the accelerator pedal 46, the accelerator is opened.
Degree S_ACCIs a digital value that is 1/8 or more
Is the target distance L ^*Or the inter-vehicle distance deviation ΔL is calculated or
Is the engine rotation control unit 21 and braking
Isn't it output to the force control unit 18?
Therefore, the preceding vehicle following automatic traveling control is not executed.

On the other hand, there is a certain road surface μ and there is no rainfall, but the road surface
When there is water such as rainwater on the top, key of the stopped vehicle
Turn the switch back on, and the follow-up run select switch 26
In the ON state, the follow running selection signal S_FIs a logical value
It is "1" and there is no depression of the accelerator pedal 46.
, Accelerator opening S_ACCIs a digital value and is 0/8 fully closed
The vehicle is in the state
Now when you are about to start right, the vehicle speed V
_C"0" and engine speed N_EIs almost idle
Running sound pressure reference value N₀Is elected. Also,
Running sound S_PThe level of itself is basically the engine
Is it only due to the vibration component caused by the rotating state?
, The vibration component due to the engine rotation state was removed
Difference in traveling sound pressure integrated value for each frequency band ΔN_R, ΔN_WIs in principle
Becomes "0" or almost "0". In addition, each frequency band
Vehicle speed correction coefficient C for the difference in running sound pressure integrated value_NRV, C_NWVBut the vehicle speed
V_CCalculated and set in the state of "0", but high and low frequency band
Because the deviation ε of the running sound pressure integrated value difference is “0”,
Rainfall correction coefficient C of traveling sound pressure integrated value over several bands_NWCIs "1"
Become. However, as described above, the running sound of each frequency band
Pressure integrated value difference ΔN_R, ΔN_WIs “0” or almost “0”
Therefore, the running sound pressure integrated value difference ΔN in each frequency band_R, ΔN_W
Is actually "0" or almost "0" without conversion correction.
Therefore, the road surface μ is₀And calculation set
The road surface water amount R is calculated and set to "0" or almost "0".
It On the other hand, the constant value road surface μ₀Dry road surface immediately
Target vehicle distance when the road surface water amount R is "0" or almost "0"
The reference value A is calculated and set, and the key switch is turned on again.
Storage of the road surface μ and the road surface water amount R of the storage device 84c by N
Data has been cleared, depending on the road surface μ and road surface water amount R
The target inter-vehicle distance reference value A remains as it is without correction.
Target distance L^*Will be set to this goal
Inter-vehicle distance L ^*Between the current vehicle distance L and the current vehicle distance L
The value | ΔL | is the dead zone threshold L₀If it is more than this,
Inter-vehicle distance deviation ΔL is the engine rotation control unit
21 and output to the braking force control unit 18
Is done.

In the engine speed control unit 21, the inter-vehicle distance deviation ΔL should be a positive value. Therefore, the throttle opening is set so that the throttle valve 44 is opened widely according to its magnitude. A drive signal corresponding to the rotation angle (the number of steps) of the step motor 45 that achieves the throttle opening is output. On the other hand, in the braking force control unit 18, since the inter-vehicle distance deviation ΔL should be a positive value, the wheel cylinder 5
The positions of the solenoid valves 70L and 70R of the braking force control module 49, specifically, the brake pedal 45 is not depressed and the motor 74 is operated so that the working fluid pressure to the 2RL and 52RR becomes atmospheric pressure or almost atmospheric pressure. Unless this is done, the working fluid pressure is at or near atmospheric pressure, so the master cylinder pressure PM is directly transmitted to the rear left and right wheel cylinders 52RL and 52RR at the (A) position. 70L, 70R
Drive signal to achieve the position of each solenoid valve 70L, 7
Output to the 0R solenoid 71.

From this state, the engine speed N_EIncrease
The vehicle starts to accelerate with the speed and the vehicle speed V_CIs accelerated
And the current vehicle speed V_CAnd current engine speed N_EAccording to
Running sound pressure reference value N₀Is selected and the running sound for each frequency band
Pressure integrated value difference ΔN_R, ΔN_WIs calculated and the vehicle speed V_CTo
Low frequency band running sound pressure integral value difference ΔN_RThe above figure
Low frequency band running sound pressure product at vehicle speed satisfying the correlation of 5a
Vehicle speed correction coefficient C for conversion correction_NRVIs calculated
Is set and the vehicle speed V_CSound pressure in high frequency band in Japan
Integration value difference ΔN_WAt a vehicle speed that satisfies the correlation shown in FIG. 5b.
For converting to the high frequency band running sound pressure integral value difference for correction
Vehicle speed correction coefficient C_NWVIs calculated and set. On the other hand, at this time
Deviation ε of the calculated difference in the running sound pressure integrated value in the high and low frequency bands
Is “0” or almost “0” because there is no rainfall.
Therefore, the rainfall correction coefficient C of the traveling sound pressure integrated value in the high frequency band_NWC
Becomes "1". And at least each of the frequency bands
Vehicle speed correction coefficient C for the difference in running sound pressure integration value_NRV, C_NWVUsing
Then, the vehicle speed V_CTo a vehicle speed that satisfies the correlation shown in Fig. 5 above.
Replaced and corrected frequency band running sound pressure integrated value difference ΔN_R, ΔN
_WIs calculated and set, the road surface μ and the road surface water amount R are
Accurately or almost accurately by removing the vehicle speed dependence
Be done. And the current vehicle speed V_CEyes calculated and set according to
Depending on the road surface μ and road surface water amount R,
The target inter-vehicle distance L is corrected by the same correction.^*Is set, this
Target inter-vehicle distance L^*Of the vehicle-to-vehicle distance deviation between
The absolute value | ΔL | is the dead zone threshold L₀If this is the case,
This inter-vehicle distance deviation ΔL is the engine rotation control unit.
Towards the hood 21 and the braking force control unit 18
Is output.

In the engine rotation control unit 21 and the braking force control unit 18, the braking / driving force control according to the inter-vehicle distance deviation ΔL is performed in the same or almost the same manner as described above to achieve the target inter-vehicle distance L ^*. However, the braking / driving force control is performed for each wheel 10 especially when the road surface μ is low or the road surface water amount R is large.
If a slip occurs on FL-10RR,
The braking / driving force control amount is adjusted and controlled by the pressure increasing function and the like of each control unit 21, 18.

At this time, the target inter-vehicle distance achieved by the preceding vehicle following automatic traveling control is corrected in accordance with the road surface μ and the road surface water amount R, and the vehicle speed V _C is already equivalent to the medium / high speed traveling state. Therefore, in such a medium / high speed traveling state, the target inter-vehicle distance L ^* can be set in consideration of a reduction in traveling stability caused by a decrease in the road surface μ and an increase in the road surface water amount R. it can. Note that the calculation of the road surface μ and the road surface water amount R, or the follow-up control to the target inter-vehicle distance L ^* corrected based on these, is similarly continued even if the vehicle speed changes thereafter.

When there is rainfall in such a state, the deviation ε of the integrated sound pressure value difference between the high and low frequency bands increases as the amount of rainfall increases. Therefore, the deviation of the integrated sound pressure value difference between the high and low frequency bands. The rainfall correction coefficient C _{NWC of the} high-frequency band traveling sound pressure integral value difference, which becomes smaller as ε increases, is calculated and set. At this time, since the calculated high frequency band traveling sound pressure integral value difference ΔN _W should be large as the amount of rainfall increases, the rainfall correction coefficient C _NWC of the high frequency band traveling sound pressure integral value difference is also used. Therefore, the corrected high frequency band traveling sound pressure integrated value difference ΔN _W becomes a value that satisfies the correlation of FIG. 5b without rainfall, so that the road surface μ and the road surface water amount R are dependent on the vehicle speed and the rainfall amount, respectively. It is calculated accurately or almost accurately by removing the dependency. Then, the target inter-vehicle distance reference value A calculated and set according to the current vehicle speed V _C is corrected according to the road surface μ and the road surface water amount R to set the target inter-vehicle distance L ^* , and the inter-vehicle distance deviation is further set. ΔL is the engine rotation control unit 21 and the braking force control unit 1
It is output toward 8.

As described above, the present embodiment is an implementation of all the vehicle road surface condition detecting devices of claims 1 to 5 of the present invention, and the wheel speed sensors 28FL to 28R shown in FIG.
R and step S25 and step S26 of the calculation process of FIG. 13 correspond to the vehicle speed detecting means in the vehicle road surface state detecting device of the present invention, and hereinafter, similarly, the engine rotation speed sensor 38 of FIG. 2 and the calculation process of FIG. Step S2
7 corresponds to the engine rotation state detection means, and the traveling state detection means is configured to include the vehicle speed detection means and the engine rotation state detection means. The traveling sound sensor 39 of FIG. 2 and step S29 of the arithmetic processing of FIG. Corresponds to the running state sound detection means,
Steps S32 and S33 of the arithmetic processing of FIG.
Step S36 corresponds to the vehicle speed-sound pressure correction means, and FIG.
Of step S34 to step S36 of the calculation process of
It corresponds to the sound pressure correction means, and corresponds to step S of the arithmetic processing of FIG.
28, step S30, step S31, step S3
Reference numeral 7 corresponds to a road surface friction coefficient state calculating means, which is step S28, step S30, step S3 of the calculation process of FIG.
1, step S38 corresponds to the road surface liquid amount calculation means.

Although the vehicle speed is calculated from the wheel speed and detected in the above embodiment, the detection of the vehicle speed is not limited to this, and the vehicle speed of the transmission is the same as the vehicle speed displayed on the instrument panel. The output shaft rotation speed may be converted and detected. Further, in the above embodiment, the case where the microcomputer is applied as the controller 30 has been described, but the present invention is not limited to this, and it is also possible to combine electronic circuits such as a function generator and an arithmetic circuit.

In the above embodiment, a map in which each correlation is simplified is used in order to facilitate understanding, and various numerical values can be set or calculated by searching this map even in actual arithmetic processing. However, as a matter of course, these correlations may be mathematically expressed and calculated from the arithmetic expression of each variable. In addition to the above-mentioned functions, the engine rotation control unit has a function of adjusting and controlling the idle valve opening, a function of controlling the air-fuel ratio, a function of adjusting and controlling the ignition timing by the spark plug, or a supercharger. The mounted vehicle may be provided with a function of controlling the supercharging pressure.

Further, in the above-mentioned embodiment, the case where the preceding vehicle following automatic traveling control is executed only when the select switch is selected and the accelerator pedal is not depressed is explained, but for the same reason as described above. You may add to the condition that the brake pedal is not depressed. Further, in the above-mentioned embodiment, the case where the forward traveling vehicle following automatic traveling control device is applied to the rear wheel drive vehicle has been described, but the present invention can also be applied to the front wheel drive vehicle and the four wheel drive vehicle.

Further, in the above-mentioned embodiment, only the case where the vehicle road surface condition detecting device of the present invention is applied to the forward traveling vehicle following automatic traveling control device has been described in detail, but the driving force to each wheel can be variably controlled. The present invention is applicable to all types of devices such as a four-wheel drive vehicle driving force distribution control device that is considered to be preferable to change the control amount according to the road surface μ and the amount of liquid on the road surface. .

[0079]

As described above, according to the vehicle road surface condition detecting apparatus of the present invention, at least the vibration component caused by the engine rotation state is removed and the dependence on the vehicle speed is almost removed, and the road surface μ and the road surface are removed. The liquid amount can be calculated or detected almost accurately. Further, by removing the vehicle speed dependency from the sound pressure of the running state sound in each frequency range, the road surface μ and the road surface liquid amount can be further accurately calculated or detected. Further, by removing the influence of rainfall from the sound pressure of the running state sound in the frequency range for calculating or detecting the road surface liquid amount, the road surface liquid amount can be calculated or detected more accurately.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an outline of the present invention.

FIG. 2 is a schematic configuration diagram of a vehicle in which the vehicle road surface state detection device of the present invention is applied to a forward traveling vehicle following automatic traveling control device.

FIG. 3 is a block diagram showing an example of a following traveling control unit shown in FIG.

FIG. 4 is a sound pressure frequency characteristic diagram of a running state sound used in the vehicle road surface state detection device of the present invention.

FIG. 5A is an explanatory diagram showing a correlation between a sound pressure integrated value of a running condition sound and a road surface friction coefficient condition used in the vehicle road surface condition detecting device of the present invention, and FIG. FIG. 6 is an explanatory diagram showing a correlation between a sound pressure integrated value of a traveling state sound and a road surface fluid amount used in the vehicle road surface state detection device of FIG.

FIG. 6 is an explanatory diagram showing the vehicle speed dependence of the sound pressure of the running state sound in each frequency range.

7 is an explanatory diagram showing a vehicle speed characteristic of a target inter-vehicle distance reference value used in the automatic travel control system of FIG.

8 is a flowchart showing a first embodiment of a calculation process of a road surface friction coefficient state and a road surface liquid amount calculation and a target inter-vehicle distance calculation using them which are executed by the following travel control unit of FIG.

FIG. 9 is an explanatory diagram showing a correction coefficient characteristic for correcting the vehicle speed dependence of the sound pressure of the running state sound in each frequency range used in the vehicle road surface state detection device of the present invention.

FIG. 10 is an explanatory diagram showing the rainfall amount dependency of the sound pressure of the traveling state sound in each frequency range used in the vehicle road surface condition detection device of the present invention.

FIG. 11 is an explanatory diagram showing the correlation between the sound pressure difference value of the running state sound and the rainfall amount in each frequency range used in the vehicle road surface condition detection device of the present invention.

FIG. 12 is an explanatory diagram showing a correction coefficient characteristic for correcting the rainfall amount dependency of the sound pressure of the running state sound in each frequency range used in the vehicle road surface state detection device of the present invention.

13 is a flowchart showing a second embodiment of the calculation processing of the road surface friction coefficient state and the road surface liquid amount calculation and the target inter-vehicle distance calculation using them which are executed by the following travel control unit of FIG.

[Explanation of symbols]

 10FL and 10FR are front wheels (non-driving wheels) 10RL and 10RR are rear wheels (driving wheels) 14 is an automatic transmission 18 is a braking force control unit 20 is an engine 21 is an engine rotation control unit 26 is a follow-up drive select switch 28FL to 28RR are Wheel speed sensor 30 is a follow-up running control unit 38 is an engine speed sensor 39 is a running sound sensor 40 is a vehicle distance sensor 42 is a throttle sensor 44 is a throttle valve 45 is a step motor 46 is an accelerator pedal 47 is an accelerator sensor 49 is a braking force control. Module 50 is a brake pedal 51 is a brake master cylinder 52FL to 52RR is a wheel cylinder 54L and 54R are hydraulic control valves 70L and 70R are solenoid valves 84 is a microcomputer

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G01N 29/00

Claims (5)

[Claims] 1. A running state sound detecting means for detecting road noise and splash sound generated as the vehicle runs, a running state detecting means for detecting a running state of the vehicle, and the running state sound detecting means. Sound pressure of a running state sound detection value in a preset predetermined frequency range among the running state sound detection values and a running state sound reference value corresponding to the running state detection value detected by the running state detection means. A road surface condition detecting device for a vehicle, comprising: a road surface liquid amount calculating means for calculating an amount of a liquid substance on a road surface which is constantly stable on the basis of a difference value regarding 2. A running state sound detecting means for detecting a running state sound including at least road noise and splash sound accompanying the running state of the vehicle, a running state detecting means for detecting a running state of the vehicle, and the running state sound detection. Of the detection values of the traveling state sound detected by the means, the detected value of the traveling state sound in a preset predetermined frequency range, and the reference value of the traveling state sound corresponding to the detected value of the traveling state detected by the traveling state detecting means. And a road surface friction coefficient state calculation means for calculating a steady and stable friction coefficient state of the road surface based on a difference value relating to sound pressure between the vehicle road surface state detection device and the vehicle road surface state detection device. 3. The road surface liquid amount calculating means and the road surface friction coefficient state calculating means, wherein the road surface liquid amount calculating means sets in advance for calculating the amount of the liquid substance on the road surface in a predetermined traveling state. The sound pressure of the running state sound detection value in the predetermined frequency range is compared with the sound pressure of the running state sound detection value in the preset predetermined frequency range for calculating the friction coefficient state of the road surface. When there is a relatively increasing tendency, the running state sound detection value within a preset predetermined frequency range for calculating the amount of liquid matter on the road surface, and the running state detected by the running state detecting means. 3. Rainfall-sound pressure correction means for correcting a calculated value obtained from the sound pressure of one or both of the running state sound reference values according to the detected value. The road surface condition detection device for a vehicle described. 4. A vehicle speed detection means for detecting at least a vehicle speed is provided as the traveling state detection means, and the road surface liquid amount calculation means or the road surface friction coefficient state calculation means uses the vehicle speed detection value detected by the vehicle speed detection means. On the basis of the traveling state sound detection value detected by the traveling state sound detecting means, the traveling state sound detection value within a preset predetermined frequency range, and the traveling state detection value detected by the traveling state detection means. 4. A vehicle speed-sound pressure correcting means for correcting a calculated value obtained from the sound pressure of one or both of the running state sound reference values according to the above. The road surface condition detection device for a vehicle according to item 1. 5. The running state detecting means includes at least a vehicle speed detecting means for detecting a vehicle speed and an engine rotating state detecting means for detecting a rotating state of the engine, and the road surface liquid amount calculating means or the road surface friction coefficient state calculating means. The running state sound reference value according to the running state detection value used in the means is a running state sound when running on a dry road surface having a preset road surface friction coefficient state at least at a predetermined vehicle speed and a predetermined engine rotation state. The road surface condition detecting device for a vehicle according to any one of claims 1 to 4, wherein