JP3409389B2 - Road surface friction coefficient estimation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for estimating the state of frictional coupling between a wheel tire and a road surface of a vehicle.

[0002]

Friction coupling between the tires of the wheels of a vehicle and the road surface is important for the safety of the vehicle. That is, any dynamic process in a vehicle, such as operating the accelerator pedal to accelerate the vehicle or operating the brake pedal to decelerate the vehicle, is the transmission of a corresponding force between the tire and the road surface. Is necessary. In this case, the frictional coupling between the tire and the road surface depends on the slip ratio of the wheels, and when the slip ratio exceeds a predetermined range, the frictional coupling weakens and the vehicle travel becomes unstable.

Therefore, a control device or the like for preventing the slip ratio of the vehicle from exceeding a predetermined range when the vehicle is decelerated or accelerated is already known. In these devices, the wheel sensor detects the wheel speed of the wheel and the acceleration / deceleration of the wheel rotation.Then, along with other measured values, the wheel slip and the like are calculated in the electronic evaluation control device, and there is a risk that the wheel will exceed a predetermined range. If so, a control method has been devised in which the braking pressure is reduced by an appropriate drive device or the like, or the engine torque is reduced.

In the control method as described above, the operation is not performed only when there is an imminent danger of the driving wheel idling, or when there is an imminent danger of the braked wheel locking. Prior to starting the method, a method has been devised for providing a driver of a vehicle with information regarding a frictional state between a tire of a wheel and a road surface, that is, a road surface condition.

The prior art is disclosed in Japanese Patent Laid-Open No. 4-224.
In consideration of frictional coupling between a tire and a road surface, as described in Japanese Patent No. 447, there is known one that uses a known characteristic curve of wheel circumferential force K-wheel slip ratio S. In this method, the wheel speed of the driving wheel and the wheel speed of the non-driving wheel are detected by a digital wheel speed sensor or the like. Further, the wheel speed of the non-driving wheels is regarded as the vehicle body speed. The wheel slip rate S is detected using the wheel speed of the drive wheel and the vehicle body speed detected as described above. At the same time, the wheel circumferential force K is numerically calculated using the known engine characteristic data at that time, or the wheel circumferential force K is measured using a known strain gauge device. Using the wheel slip ratio S and the wheel rolling force K determined by these methods, for example, a characteristic curve of wheel rolling force K-wheel slip ratio S on a road surface having a high coefficient of friction, which is generally dry, in advance. The above value K / S is stored in the storage element of the microcomputer in the vehicle.

Based on the above, during acceleration / deceleration of the vehicle, the values of the wheel revolution force K and the wheel slip ratio S in the known relationship between the wheel revolution force K and the wheel slip ratio S characteristic curve are detected. The value of the wheel slip rate S is compared with the stored value of the wheel slip rate S when the wheel turning force K has the same magnitude. Here, if the value of the wheel slip rate S is significantly larger than the stored value of the wheel slip rate S, this situation means that the friction between the tires of the drive wheels and the road surface has deteriorated, for example: It means that the vehicle is traveling on a muddy or frozen road surface, not a dry road surface. When a value of K / S that is significantly different from the stored characteristic curve of wheel orbital force K-wheel slip rate S is detected, a vehicle occupant can be warned by means of electronic evaluation or a control circuit. .

[0007]

However, in the above-mentioned prior art, the method of measuring the wheel turning force K by using the known strain gauge device when the characteristic curve of the known wheel turning force K-wheel slip ratio S is used. Alternatively, a method of calculating the wheel circumferential force K using the engine characteristic data at the time of detecting the frictional condition between the road surface and the tire is adopted. While the vehicle body is vibrating due to road conditions or engine rotation etc. while the vehicle is running, the wheel circumference force K measured using a strain gauge.
Since the value of has a large error component, it can be said that it is not reliable even when the frictional condition between the road surface and the tire is detected and judged by using the wheel circumferential force K. Further, when the wheel circumferential force is calculated from the engine characteristic data, considering the characteristics of the engine of each vehicle, the estimation method becomes complicated and difficult, and it is extremely difficult to obtain reliable data.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a road surface friction coefficient estimating device capable of easily and highly accurately estimating the road surface friction coefficient μ.

[0009]

In order to solve the above problems, a road surface friction coefficient estimating apparatus according to the present invention comprises means for obtaining the wheel speed of each wheel of a vehicle, means for obtaining the vehicle body speed of the vehicle, and Based on the wheel speed and the vehicle body speed, a calculating means for periodically calculating a wheel slip value for each wheel, a means for obtaining the vehicle body acceleration of the vehicle, a value related to the slip value of each wheel and the vehicle. from the relationship between the value associated with vehicle acceleration, and a road surface friction coefficient estimating means for estimating a coefficient of friction between the road surface and the wheels of the vehicle, the
As a value related to the slip value of each wheel, for each cycle
, The sum of the slip values of each wheel over multiple cycles
Slip product calculated by the first integrating means for integrating
It is characterized by using an arithmetic value. Also, in claim 2.
As described above, the road surface friction coefficient estimating means
If the value related to the value exceeds a predetermined value, the friction coefficient
To adopt a device characterized by estimating
You may. Also, as described in claim 3, the road surface
The friction coefficient estimating means has a value related to the vehicle body acceleration.
Estimate and calculate the road friction coefficient when it exceeds a certain level
You may make it employ | adopt the apparatus characterized by the above.

[0010]

[0011]

[Action] Here, road surface friction coefficient, which indicates the magnitude of the frictional coupling between the road surface and the tire, the greater the road surface friction coefficient vehicles may generate a large acceleration or deceleration. As is known, the road surface friction coefficient has a characteristic that it increases as the slip ratio increases up to a wheel slip ratio of about 20%. Therefore, even if the same vehicle body acceleration occurs, it can be said that the larger the slip value of the wheel at that time, the smaller the coefficient of friction with the road surface. For this reason, the vehicle body acceleration of the vehicle is detected, and the slip ratio of the wheels that is generated to generate the vehicle body acceleration is obtained, so that the friction coefficient between the road surface and the wheels can be estimated from the relationship between the two. it can.

However, estimating the friction coefficient of the road surface only from the relationship between the vehicle body acceleration detected at a certain timing and the wheel slip ratio at that time is easily affected by an error factor such as noise, and the estimation accuracy decreases. Cause. This
Because of this, the sum of slip values accumulated over multiple cycles
Estimate road friction coefficient based on
When the value related to the value or the vehicle body acceleration exceeds a predetermined value
Estimation of the road surface friction coefficient improves the estimation accuracy.
It

[0013]

The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a block diagram showing the configuration of the present invention. As shown in FIG. 1, wheel speed sensors 2a to 2d are provided corresponding to the wheels 1a to 1d of the vehicle. Further, a central processing unit 3 (hereinafter referred to as ECU) is installed in the vehicle,
The signal from each wheel speed sensor 2a-2d is taken in and each wheel speed is calculated. The ECU 3 further takes in a detection signal detected by the acceleration sensor 4 and integrates the value of the vehicle body acceleration of the vehicle over a plurality of cycles. Further, the ground speed sensor 5 detects a signal corresponding to the relative speed between the vehicle body and the road surface and outputs it to the ECU 3. The ECU 3 calculates each wheel slip ratio or each wheel slip amount based on the detection signal from each sensor, obtains the sum of all the wheel slip values of all the wheels, and integrates the value of this sum over a plurality of cycles.
Furthermore, for the vehicle body acceleration, the integrated value obtained by integrating over a plurality of cycles is calculated, and the coefficient of friction between the road surface of the vehicle and the wheels is calculated by using the relationship with the integrated value of the sum of all wheel slip values. Estimate the coefficient of friction, medium coefficient of friction, or low coefficient of friction. The road surface condition can be determined based on the estimated friction coefficient, and the display unit 6 allows the driver or the like to recognize the current road surface condition to call attention or be applied to control of ABS and TRC.

FIG. 2 is a graph of a characteristic curve showing the relationship between the road surface friction coefficient μ and the wheel slip ratio S. Road friction coefficient μ
The boundary between the vertical axes indicating the values is the relationship between the road surface friction coefficient μ and the wheel slip ratio S when the wheel is driving, and the left side is the road surface friction coefficient when the wheel is braking. The relationship between μ and the wheel slip ratio S is shown. In this graph, the road surface friction coefficient μ corresponds to the driving force or braking force between the tire and the road surface of the vehicle. Therefore,
The road surface friction coefficient μ can be regarded as the vehicle body acceleration generated by the driving force and the braking force.

As described above, in the known road surface friction coefficient μ-wheel slip ratio S characteristic curve, the road surface friction coefficient μ can be replaced with the vehicle body acceleration, and the characteristic curve of vehicle body acceleration-wheel slip S can be considered. This makes it possible to determine the coefficient of friction μ between the tire of the vehicle and the road surface even when the vehicle is normally traveling. This is because, in general, driving in an urban area or driving on a highway can be considered to be repeated gradual acceleration / deceleration driving. That is, not to mention traveling-stopping at a signal waiting time, even when traveling at a substantially constant speed,
A slight acceleration / deceleration is performed depending on the vehicle interval, climbing / descending of the road surface, etc., and it is extremely rare for the vehicle to travel with zero speed change.
Therefore, by capturing the minute acceleration / deceleration, the vehicle body acceleration can be calculated, and the road surface friction coefficient μ can be estimated.

When the vehicle is traveling at a constant speed, the wheel speed and the vehicle body speed are the same, but when a driving torque is applied to the wheel, the wheel speed is lower than the vehicle body speed, and the wheel speed decreases between the wheel and the road surface. Slip phenomenon occurs. When the wheel slip rate is close to 20% in this slip phenomenon. As shown in FIG. 2, the maximum friction coefficients μph and μpl between the tire of the wheel and the road surface are obtained. Here, regarding the stability of motion in the behavior during driving of the wheel, the left side region of the maximum friction coefficients μph and μpl in the graph, that is, when the wheel slip rate is 0 to when the wheel slip rate is about 10% to 20% The area up to the peak of the friction coefficient μ is called the stable area of the wheel during driving. Also, the maximum friction coefficient μph,
The value of μpl differs depending on the road surface condition, etc., but by making the graph in this stable region an approximately straight line, the slope can be taken into consideration, and from that slope, the maximum friction coefficient μph, μpl It is possible to discriminate a curve that passes through, that is, it is possible to estimate whether the current road surface condition is a high μ road surface or a low μ road surface.

FIG. 3 shows a first embodiment for determining whether the road surface friction coefficient μ between the tire on which the vehicle is running and the road surface is low μ, medium μ, or high μ according to the configuration shown in FIG. It is a flowchart showing. The operation will be described below according to the flow shown in FIG. When the ignition switch IG of the vehicle is turned on and the vehicle starts traveling, the process starts from step 100. In step 101, a count process of incrementing the counter value n by a predetermined value is performed. Step 102
Then, the wheel speed sensors 2a to 2d are used to calculate the wheel speeds Vfr, Vfl, Vrr, and Vrl of all the tires. In step 103, the ground speed sensor 5 is used to calculate the vehicle speed Vb. In step 104, the wheel speeds and vehicle body speeds detected in steps 102 and 103 are used, and the wheel slip rates Sfr, Sfl, Srr,
Calculate Srl. For example, the wheel slip ratio Sfr of the right front wheel
Is

[0018]

## EQU1 ## Calculated by Sfr = (Vb-Vfr) / Vb. Wheel slip rate Sf of other wheels
l, Srr, and Srl are calculated in the same manner. Step 10
5, the vehicle body acceleration Ab is calculated by differentiating the vehicle body speed Vb approximately with time t.

[0019]

## EQU2 ## Calculation is performed by Ab = {Vb (n) -Vb (n-1)} / t. In step 106, the sum St of the slip ratios Sfr, Sfl, Srr, and Srl of each wheel is obtained. In step 107 and step 108, the sum St of the wheel slip ratios and the vehicle body acceleration Ab are calculated by the equations 3 and 4.
Total by.

[0020]

[Equation 3]       ΣSt = {St (n) + St (n + 1) + ... + St (n + k)}

[0021]

ΣAb = {Ab (n) + Ab (n + 1) + ... + Ab (n + k)} Here, in the numerical values calculated by using Expressions 3 and 4, the influence of noise components is minimized. In addition, the sum St of the wheel slip ratios and the vehicle body acceleration Ab are accumulated for a predetermined time period of k times. In step 109, when the vehicle is traveling without much acceleration / deceleration and changes in the vehicle body acceleration Ab and the wheel slip sum St are not detected so much, it is determined whether or not a predetermined time has elapsed. The data is kn
When it is determined that a predetermined time has elapsed, the process proceeds to step 112, at which time the vehicle acceleration ΣAb integrated for a predetermined time and the sum Σ of wheel slips integrated for a predetermined time.
If the slope in the graph showing the relationship with St is M,

[0022]

## EQU5 ## The slope M can be detected from M = ΣAb / ΣSt. Here, the sum ΣSt of wheel slips integrated for a predetermined time and the vehicle body acceleration ΣAb integrated for a predetermined time
By using, the reliability of the determination of the road surface condition is improved. Next, the routine proceeds to step 113, where the value kμ1 stored in advance is compared with the value of M based on the road surface friction coefficient value when the vehicle travels on a road surface having an apparently high road surface friction coefficient, and the value of M is compared. Is larger than the value of kμ1,
It is estimated that the current friction coefficient between the tire and the road surface is high, and in step 115 a high μ flag indicating that the road surface condition is good is set. If it is determined in step 113 that the value of M is smaller than the value of kμ1, the process proceeds to step 114, and the road surface friction coefficient value when traveling on a road surface having a clearly low road surface friction coefficient is used as a reference in advance. The stored value kμ2 is compared with the value of the sum ΣSt of the vehicle body acceleration ΣAb / wheel slip ratio based on the value integrated for each predetermined time, and if the value of M is larger than the value of kμ2,
It is estimated that the current friction coefficient between the tire and the road surface is relatively high, and in step 116, the medium μ flag indicating that the road surface condition is relatively good is set. Further, when the value of M is smaller than the value of kμ2 in step 114, it is determined that the current friction coefficient between the tire and the road surface is low, and in step 117, low μ indicating that the road surface condition is bad.
Set the flag. Then, at step 118, the counter value n, the sum ΣSt of the integrated wheel slip rates, and
Clear the integrated vehicle acceleration ΣAb, and proceed to step 10
Start from 0 as well. If it is determined in step 109 that the predetermined time has not yet elapsed, step 1
Go to 10. In step 110, when the vehicle is mainly traveling on a low friction coefficient road surface, it is determined whether the sum ΣSt of wheel slips is equal to or more than a predetermined value ks before the predetermined time determined in step 109 elapses, and ΣSt is ks. If it is determined that the above is the case, the process proceeds to step 112. Thereafter, steps 113 to 118 proceed in the same manner as described above. Further, when the sum ΣSt of wheel slips integrated within the predetermined time in step 110 does not exceed the predetermined value ks and the process proceeds to step 111, the integrated value ΣAb of the vehicle body acceleration is mainly during acceleration and deceleration. It is determined whether or not a predetermined value KG is exceeded, and if it is determined that ΣAb has exceeded KG, the process proceeds to step 112. If the sum of the vehicle body acceleration ΣAb integrated in step 111 does not exceed the predetermined value KG, the process proceeds to step 118 and proceeds as described above.

FIG. 4 is a flow chart showing the second embodiment of the present invention. In the second embodiment, an FF vehicle is assumed, and the vehicle speed is calculated from the wheel speed using only the wheel speed sensor without using the ground sensor. The operation will be described below according to the flow shown in FIG. When the ignition switch IG of the vehicle is turned on and the vehicle starts traveling, the routine starts from step 200. In step 201, a count and processing for incrementing the counter value n by a predetermined value are performed. In step 202, the wheel speeds of all tires Vfr ′, Vfl ′, Vrr ′,
Calculate Vrl '. In step 203, the average wheel speed of the non-driving wheels that is less influenced by the braking force and the driving force in the wheel speed detected in step 202 is set as the vehicle body speed Vb '. In step 204, the average wheel speed of the driving wheels that directly receives the braking force and the driving force, and in step 203
The wheel slip amount is calculated by the following equation using the vehicle body speed Vb ′ calculated in step 1.

[0024]

## EQU00006 ## .DELTA.Vb '= Vb'-(Vfr + Vfl) / 2 In step 205, the vehicle speed Vb 'is approximately differentiated with respect to time t to calculate the vehicle acceleration Ab' by the following equation.

[0025]

Ab ′ = {Vb ′ (n) −Vb ′ (n−1)} / t In step 206 and step 207, the sum ΔVb ′ of the wheel slip amounts and the vehicle body acceleration Ab ′ are integrated for a predetermined time. , ΣΔVb ′ and ΣA calculated by Equations 8 and 9
At the value of b ′, the influence of noise components is suppressed as much as possible.

[0026]

ΣΔVb ′ (n) = ΣΔVb ′ (n−1) + |
ΔVb '(n) |

[0027]

ΣAb ′ (n) = ΣAb ′ (n−1) + | A
b ′ (n) | In step 208, when the vehicle is running without acceleration / deceleration, it is determined whether a predetermined time has elapsed and the data has been accumulated kn times. When it is determined that the predetermined time has elapsed, the routine proceeds to step 211, and the magnitude of the value of the vehicle body speed Vb ′ in the current vehicle traveling state is determined. When the vehicle body speed Vb 'is higher than the predetermined vehicle body speed KVb', the routine proceeds to step 213. In step 213, the sum ΣΔVb ′ of the vehicle body acceleration ΣAb ′ integrated for a predetermined time and the wheel slip amount integrated for a predetermined time when the vehicle is traveling at high speed.
The MAP representing the relationship is set in advance. Figure 4
-As shown in FIGS. 4A and 4B, in the MAP, a road surface having a high friction coefficient, that is, an area showing that the road surface condition is good, and a road surface having a relatively high friction coefficient, that is, an obstacle to traveling stability It is divided into a region showing that there is no road surface condition and a region showing a low friction coefficient, that is, a region showing that the road surface condition is bad. In step 214, the vehicle body acceleration ΣA on such a MAP.
The flag is set by judging which of the above-mentioned regions the relationship between b ′ and the sum ΣΔVb ′ of the wheel slip amounts is applied. The detected value when the wheel slip amount ΔVb ′ is calculated while the vehicle is traveling at high speed is the wheel slip amount ΔVb ′ during low speed traveling.
It is likely that the value will be larger than the detected value of. Therefore,
MAP for high-speed running Figure 4-A shows the sum of wheel slippage ΣΔV
The area of determination of the road surface condition and the change of b'are gentle with respect to the change of b '. After the flag is set in step 214, the counter value n, the sum ΣΔVb ′ of the integrated wheel slip amounts and the vehicle body acceleration ΣAb are cleared in step 215, and the process returns to step 200.
If the vehicle body speed Vb 'is smaller than the predetermined vehicle body speed KVb' in step 211, step 21
Go to 2. In step 212, MAP FIG. 4-B when the vehicle is traveling at a low speed is preset. There is a high possibility that the detected value when the sum ΣΔVb ′ of wheel slips is calculated during low-speed running of the vehicle will be smaller than the detected value of the wheel slip ΔVb ′ during high-speed running. Therefore,
MAP for low speed running Fig. 4-B shows the sum of the wheel slippage ΔVb '
The area of determination of the road surface condition and the change of are slower with respect to the change of. Next, in step 214, the flag is set similarly. If it is determined in step 208 that the predetermined time has not yet passed,
Go to step 209. In step 209, when the vehicle is mainly traveling on a low friction coefficient road surface, the sum Σ of wheel slip amounts before the predetermined time determined in step 208 elapses.
When ΔVb ′ is not less than the predetermined value KV, the process proceeds to step 211. Thereafter, steps 211 to 215 proceed in the same manner as described above. Further, when the sum ΣΔVb ′ of the wheel slip amounts integrated in step 209 does not exceed the predetermined value KV, the process proceeds to step 210. In step 210, the integrated vehicle body acceleration ΣA is mainly used during acceleration and deceleration of the vehicle.
If the value of b ′ exceeds the predetermined value KG, step 211
, And so on. If the integrated value of the vehicle body acceleration ΣAb ′ does not exceed the predetermined value KG, the process returns to step 200 and starts.

The above-described second embodiment is a flow assuming a FF vehicle, but when applying to a 4WD vehicle,
When considering the vehicle speed VB 'in step 203',
The average of all four wheels receiving the driving force is calculated by the equation 10.

[0029]

VB ′ = (Vfr ′ + Vfl ′ + Vrr ′ +
Vrl ′) / 4 Further, when considering the wheel slip amount ΔVB in step 204 ′, a calculation number 10 is obtained by subtracting the average wheel speed of the rear wheels from the average wheel speed of the front wheels, which is greatly influenced by the vehicle body weight.

[0030]

ΔVB ′ = (Vfr ′ + Vfl ′) / 2−
(Vrr '+ Vrl') / 2 The present invention is not limited to the above embodiment, but can be variously modified as follows. For example, in the first embodiment, a ground speed sensor is used when detecting the vehicle speed Vb,
The vehicle body acceleration Ab is calculated by differentiating this with respect to time. However, in the first embodiment and the second embodiment, the known G sensor is used to detect the vehicle body acceleration and the vehicle body speed. Good. Further, although the FF vehicle is assumed in the second embodiment, when the sum of the wheel slip amounts is integrated in step 206 and ΣΔVb ′ is considered by the formula 8, the FF vehicle also has a rear wheel to which no driving force is applied. Approximately is regarded as the vehicle body speed, so that there is a possibility that the vehicle body speed of the vehicle may have a minute difference between the vehicle acceleration and the vehicle deceleration, that is, the driving time and the braking time. This is because the driving force is not applied to the rear wheels at the time of driving, but the braking force is applied to the rear wheels at the time of braking, so that it may be detected lower than the true vehicle speed. In this case, the vehicle speed V
The reliability of the wheel slip amount ΔVb ′ calculated using b ′ may also decrease. Therefore, in equation 8, | Vb '
The coefficient Q may be multiplied by (n) | to set Q = 1 during vehicle acceleration and Q ≧ 1 during vehicle deceleration.

[0031]

As described above, according to the present invention,
The road friction coefficient can be easily calculated from the relationship between wheel speed and vehicle speed.
Can be estimated. By estimating the road surface friction coefficient using the relationship in the integrated value obtained by integrating the vehicle body acceleration and the wheel slip value over a plurality of cycles, the influence of error factors such as noise can be reduced, and
And it can estimate the road surface friction coefficient and high precision
You can also

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a block configuration of the present invention.

FIG. 2 is a graph showing a road surface friction coefficient μ-wheel slip S characteristic curve.

FIG. 3 is a flowchart showing a first embodiment of the present invention.

FIG. 4 is a flowchart showing a second embodiment of the present invention.

[Explanation of symbols]

1 wheel 2 Wheel speed detection means 3 Accumulation means for detecting and integrating wheel slip ratio and wheel slip amount 4 Vehicle body acceleration detection means 5 Vehicle speed detection means

Continuation of front page (56) References JP-A-4-5156 (JP, A) JP-A-1-223064 (JP, A) JP-A-63-141866 (JP, A) JP-A-6-3257 (JP , A) JP-A-3-178853 (JP, A) JP-A-1-114523 (JP, A) JP-A-2-306864 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) (Name) B60T 8/58

Claims (13)

(57) [Claims] 1. A means for obtaining a wheel speed of each wheel of a vehicle, a means for obtaining a vehicle body speed of the vehicle, and a wheel slip value for each wheel periodically based on the wheel speed and the vehicle body speed. From the relationship between the calculation means for calculating, the means for obtaining the vehicle body acceleration of the vehicle, and the value related to the slip value of each wheel and the value related to the vehicle body acceleration of the vehicle, between the traveling road surface of the vehicle and the wheels. and a road surface friction coefficient estimating means for estimating a coefficient of friction, as the value associated with the slip value of each wheel, you each period
And the sum of the slip values of each wheel over multiple cycles.
Slip calculated by the first integrating means for integrating
A road friction coefficient estimating device characterized by using an integrated value . 2. A means for obtaining a wheel speed of each wheel of a vehicle.
And a means for obtaining the vehicle body speed of the vehicle, and the wheels are periodically cycled based on the wheel speed and the vehicle body speed.
Calculating means for calculating the slip value of each wheel , means for obtaining the vehicle body acceleration of the vehicle, a value related to the slip value of each wheel, and the vehicle body of the vehicle
From the relationship with the value related to acceleration,
And a friction coefficient estimating means for estimating the friction coefficient with the wheel.
The road surface friction coefficient estimating means relates to the slip value.
When the value exceeds a predetermined value, the friction coefficient is estimated and calculated.
An apparatus for estimating a friction coefficient of a road surface, characterized by: 3. A means for obtaining a wheel speed of each wheel of a vehicle.
And a means for obtaining the vehicle body speed of the vehicle, and the wheels are periodically cycled based on the wheel speed and the vehicle body speed.
Calculating means for calculating the slip value of each wheel , means for obtaining the vehicle body acceleration of the vehicle, a value related to the slip value of each wheel, and the vehicle body of the vehicle
From the relationship between the value associated with the acceleration, the road surface and the car of the vehicle
And a friction coefficient estimating means for estimating the friction coefficient with the wheel.
The road surface friction coefficient estimating means relates to the vehicle body acceleration.
The road surface friction coefficient when the value exceeds a predetermined value
An apparatus for estimating a friction coefficient of a road surface, which is characterized by calculating. 4. As the value related to the slip value of each wheel, the slip integrated value calculated by the first integrating means for integrating the total sum of the slip values of each wheel for each cycle is used. Claims characterized in that
The friction coefficient estimating device for a road surface according to claim 2 or claim 3 . 5. The acceleration integrated value calculated by the second integrating means for integrating the vehicle body acceleration over the same cycle as the cycle integrated by the first integrating means is used as the value related to the vehicle body acceleration. A contract characterized by
The road surface friction coefficient estimating device according to claim 1 or claim 4 . Wherein said road surface friction coefficient estimation means according to claim 1 or請 value associated with the slip value and estimates calculating the friction coefficient if it becomes more than a predetermined
The road surface friction coefficient estimating device according to any one of claims 3 to 5 . Wherein said road friction coefficient estimating means also claim 1 values related to the vehicle body acceleration and wherein said estimating calculating a road surface friction coefficient if it becomes more than a predetermined
Is a road surface friction coefficient estimating device according to any one of claims 2 and 4 to 6 . 8. The road surface friction coefficient estimating means estimates and calculates the friction coefficient based on a relationship between a value related to the slip value and a value related to a vehicle body acceleration at every predetermined time (Kn). Claims 1 to 7
The friction coefficient estimating device for a road surface according to any one of 1. 9. The road surface friction coefficient estimating means either reaches the predetermined time, a value related to the slip value becomes a predetermined value or more, or a value related to the vehicle body acceleration becomes a predetermined value or more. or when satisfied, 6 to claim 2 or claim 3 or claim, characterized in that it is determined that the timing for calculating the road surface friction coefficient
The road surface friction coefficient estimating device according to claim 8 . Wherein said vehicle speed, according to any one of claims 1 to 9, characterized in that the approximation calculation at an average wheel speed of the output value of the wheel speed sensor provided in the non-driven wheel road surface Friction coefficient estimation device. Wherein said slip value, the friction coefficient estimating apparatus of the road surface according to any of claims 1 to 10, characterized in that the approximation calculation at a wheel speed difference between the drive wheel and non-driven wheel. 12. The vehicle speed, the friction coefficient estimating apparatus of the road surface according to any of claims 1 to 10, characterized in that the approximation calculation by the average value of the wheel speeds of the four wheels. 13. calculation of the vehicle speed, the time of vehicle acceleration, the friction coefficient estimating device of the road surface according to any of claims 1 to 12, characterized in that switching the calculation method by the deceleration.