JPH0986367A - Body speed estimating device of vehicle and free rotational speed estimating device of wheels - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate vehicle speed accurately even in a wheel braking condition, by operating the weight of the longitudinal speed based on the braking conditions of the wheels, as well as operating the longitudinal speed at a specific position of the vehicle as to each wheel, and operating the body speed based on the longitudinal speed and its weight. SOLUTION: While speed sensors 12f1 to 12rr to detect the wheel speeds Vwi (i=f1 to rr) of wheels corresponding to the left side and the right side front and rear wheels 10 (10f1, 10fr, 10r1, and 10rr) as the rotation speeds are provided, the wheel speed signals are input together with the steering angle, the longitudinal acceleration, the lateral acceleration, and the output signals of yaw rate sensors, to an estimating device 14. In the estimating device 14, the body speed and the free rotation speeds of the wheels are operated, and the brakings of the wheels 10 are controlled to stabilize the rotating behavior of the vehicle. The dynamic correcting coefficients of the tire radius of each wheel resulting from the load transfer are operated, and by taking the dynamic coefficients into consideration in the operation of the longitudinal speed of the vehicle, vehicle speed can be accurately estimated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating a vehicle body speed and a free wheel rotation speed of a vehicle such as an automobile.

[0002]

2. Description of the Related Art As described in, for example, Japanese Patent Publication No. 5-502836, the specification of a vehicle is made based on the detected wheel speed and yaw rate of a specific wheel within the linear range of the μ-S characteristic when the vehicle is being braked. A technique for obtaining the speed of the position of the vehicle and using this as the vehicle body speed has been conventionally known, and the free rotation speed of each wheel (the rotation speed in the unbraked state is calculated from the vehicle speed and yaw rate calculated in this way). ) Is also known in the art.

According to such a technique, the vehicle body speed and the free rotation speed of each wheel are more accurately compared with the case where the wheel speed of each wheel is detected and the vehicle body speed is simply calculated as an average value of those wheel speeds. Therefore, the control of the vehicle based on these speeds can be performed well.

[0004]

However, in the above technique, it is necessary to confirm whether or not a particular wheel is within the range of the straight line of the μ-S characteristic, and the wheel has the μ-S characteristic. If it is not within the range of the straight line, the braking pressure of the wheel must be reduced, which may hinder the desired braking force control.

The present invention has been made in view of the above-mentioned problems in the conventional device, and the main problem of the present invention is the speed which is the basis of the vehicle speed calculation according to the braking state of each wheel. By weighting or selecting the speed that is the basis of the vehicle speed calculation according to the acceleration state of the vehicle,
It is to estimate the vehicle body speed of the vehicle and the free rotation speed of the wheel with high accuracy regardless of whether or not the wheel is within the range of the straight line of the μ-S characteristic.

[0006]

According to the present invention, the main problems as described above include means for detecting the wheel speed Vwi of each wheel, means for detecting a parameter indicating a turning state of a vehicle, and the wheels. Front-rear speed calculating means for calculating the front-rear speed Vri at a specific position of the vehicle for each wheel based on the speed Vwi and the parameter; and means for calculating a weight Wi of the front-rear speed Vri based on the braking state of each wheel, Front-rear speed V
A vehicle body speed estimating device having a vehicle speed Vx calculation means based on ri and the weight Wi (claim 1), a means for detecting a wheel speed Vwi of each wheel, and a parameter representing a turning state of the vehicle. Means for detecting the vehicle speed, front-rear speed calculating means for calculating the front-rear speed Vri at a specific position of the vehicle for each wheel on the basis of the wheel speed Vwi and the parameters, means for detecting an acceleration state of the vehicle, and the acceleration state. A vehicle body speed estimation device for a vehicle (configuration of claim 2), or a vehicle body speed estimation device for a vehicle according to claim 1 or 2; , Selecting means for selecting one of the longitudinal speed Vri and the vehicle body speed Vx based on the braking state of each wheel, and the free rotation speed Vbi of each wheel based on the one value and the parameter. It is achieved by the free rotational speed estimation device of a wheel and means for calculation (the fifth aspect).

According to the first aspect of the invention, the front-rear velocity Vri at a specific position of the vehicle is calculated for each wheel based on the wheel speed Vwi of each wheel and the parameter representing the turning state of the vehicle.
Based on the braking state of each wheel, in other words, the weight Wi of the front-rear speed Vri is calculated according to the degree of reliability, which can be the basis of the vehicle body speed calculation, based on the braking state. Since Vx is calculated, the vehicle body speed of the vehicle can be accurately estimated even when the wheels are in the braking state.

Further, according to the second aspect of the invention, the longitudinal velocity Vri of a specific position of the vehicle for each wheel is calculated based on the wheel speed Vwi of each wheel and the parameter indicating the turning state of the vehicle, and the acceleration state of the vehicle is calculated. Based on this, any one of the front-rear speed Vri is selected as the vehicle body speed Vx. In other words, the front-rear speed V calculated for the wheel in which the acceleration slip does not occur.
Since ri is the vehicle speed, the vehicle speed of the vehicle can be accurately estimated even when the vehicle is in an accelerating state.

According to the configuration of claim 5, claim 1 or 2
The vehicle body speed estimation device calculates the front-rear velocity Vri of a specific position of the vehicle for each wheel and the vehicle body velocity V
x is obtained, and the longitudinal speed Vri is calculated based on the braking state of each wheel.
And one of the vehicle body speeds Vx, in other words, one of the most reliable vehicle body speeds is selected, and the free rotation speed Vbi of each wheel is calculated based on the selected value and the parameter representing the turning state of the vehicle. Therefore, the free rotation speed of each wheel is accurately calculated regardless of the braking state of the vehicle.

Further, according to the present invention, in order to effectively achieve the above-mentioned main problem, in the structure of the above-mentioned claim 2, the selecting means selects one of the longitudinal speed Vri when the vehicle is in an accelerating state. The smallest value is selected, and the largest value of the longitudinal velocity Vri is selected when the vehicle is not in an accelerating state (configuration of claim 3).

According to this structure, the smallest value of the longitudinal speed Vri is selected when the vehicle is in an accelerating state,
When the vehicle is not in an accelerating state, the largest value of the front-rear speed Vri is selected. Therefore, when the vehicle accelerates, the front-rear speed of the wheel with zero acceleration slip or the smallest slip is the vehicle speed Vx, and when the vehicle is not accelerating, the vehicle decelerates No slip
Alternatively, the smallest longitudinal speed is set as the vehicle body speed.

Further, according to the present invention, in order to effectively achieve the above-mentioned main problems, in the structure of claim 1 or 2, there is provided means for detecting a change in the dynamic load radius of each wheel. The longitudinal speed calculating means calculates the longitudinal speed Vri based on the wheel speed Vwi, the parameter, and the change in the dynamic load radius.
Is configured to be calculated (Claim 4).

According to this structure, the change in the dynamic load radius of each wheel is detected, and the longitudinal velocity Vri is calculated based on the change in the wheel speed Vwi, the parameter indicating the turning state of the vehicle, and the change in the dynamic load radius. The front-rear velocity Vri can be obtained without being affected by the change in the dynamic load radius of the wheel due to the load movement caused by the turning or acceleration / deceleration of the vehicle.

Further, according to the present invention, in order to effectively achieve the above-mentioned main problem, in the structure according to any one of the above-mentioned fifth aspect, the selecting means is arranged so that when all the wheels are not in a braking state. When the vehicle speed Vx is selected and any one of the wheels is in the braking state, the wheel speed Vwi of the wheel that is not in the braking state is selected.
It is configured to select the front-rear velocity Vri calculated on the basis of the above-mentioned (Claim 6).

According to this structure, the free rotation speed V of each wheel is
bi is the vehicle speed V when all the wheels are not in the braking state.
It is calculated based on the front-rear speed Vri calculated based on the wheel speed Vwi of the wheel that is not in a braking state when any of the wheels is in a braking state, so that it is calculated regardless of the braking state of the vehicle. The free rotation speed of the wheel is determined very accurately.

[0016]

Generally, in controlling a vehicle, the speed at the center of gravity of the vehicle is important as the speed of the vehicle, and the speed at other positions of the vehicle is the speed at the center of gravity of the vehicle. Can be obtained relatively easily. Therefore, in the above-mentioned structure of claim 1 or 2, the longitudinal speed Vri
Is configured to be calculated as the longitudinal velocity of the center of gravity of the vehicle.

When the radius of each wheel in the stationary state is significantly different from the standard state due to the difference in tire air pressure or the static support load of each wheel, etc., the vehicle speed and the free rotation of each wheel are different. The speed cannot be calculated accurately. Therefore, in the above-mentioned structure of claim 4, there is provided a means for obtaining a static correction coefficient for the radius of each wheel in a stationary state of the vehicle,
The longitudinal speed calculation means is configured to calculate the longitudinal speed Vri based on the wheel speed Vwi, the parameter, the change in the dynamic load radius, and the static correction coefficient.

Further, in a vehicle equipped with a braking force control device for controlling the turning behavior of the vehicle and the acceleration / deceleration slip of the wheels, the braking force control device controls the braking force of each wheel as necessary. Therefore, in the above-described structure of claim 1, 5 or 6, the braking state of the wheel is configured to be determined based on the information from the braking force control device.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing a first embodiment of an estimation device according to the present invention applied to a vehicle equipped with a behavior control device for controlling the braking force of each wheel to stabilize the turning behavior of the vehicle. It is (A) and a block diagram (B).

In FIG. 1A, the wheel speed Vwi (i = fr, fl, rr, rl) of the wheels corresponding to the right front wheel 10fr, the left front wheel 10fl, the right rear wheel 10rr, and the left rear wheel 10rl, respectively. Wheel speed sensors 12fr, 12fl, 12r
r and 12rl are provided, and a signal indicating the wheel speed Vwi is input to the estimation device 14. Further, the estimation device 14 has a signal indicating the steering angle θ from the steering angle sensor 16, a signal indicating the longitudinal acceleration Gx of the vehicle body from the longitudinal acceleration sensor 18 provided substantially at the center of gravity of the vehicle, and a lateral acceleration sensor 20 indicating the lateral direction of the vehicle body. A signal indicating the acceleration Gy and a signal indicating the yaw rate γ of the vehicle are input from the yaw rate sensor 22. The longitudinal acceleration sensor 18 detects the longitudinal acceleration with the forward direction of the vehicle as positive, and the lateral acceleration sensor 20 etc. detects the lateral acceleration with the left turning direction of the vehicle as positive.

Although not shown in detail in FIG. 1, the estimation device 14 includes a central processing unit (CPU), a read only memory (ROM), and a random access memory (RA).
M) and an input / output port device, which have a general configuration in which these are connected to each other by a bidirectional common bus, and an estimation routine described later based on the parameters detected by the various sensors described above. The vehicle body speed Vb of the vehicle and the free rotation speed Vri of the wheels are calculated by performing various calculations in accordance with the above, and the vehicle body speed Vb and the vehicle body speed Vb are sent to the behavior control device 24 for controlling the braking force of each wheel to stabilize the turning behavior of the vehicle. A signal indicating the free rotation speed Vri is output.

The behavior control device 24 estimates the turning behavior of the vehicle based on the vehicle speed Vb and the free rotation speed Vri when the vehicle speed Vb is equal to or higher than a reference value Vc such as 15 km / h, and the turning behavior is a spin state. When the vehicle is on, braking force is applied to the turning outer wheels to give an anti-spin moment to the vehicle to stabilize the behavior of the vehicle, and when the turning behavior is drifting out, braking force is applied to the left and right rear wheels to decelerate the vehicle. In addition, the lateral force of the rear wheels is reduced and a turning assist moment is applied to the vehicle to stabilize the behavior of the vehicle.

Next, the outline of the routine for estimating and calculating the vehicle body speed and the free wheel rotation speed in the first embodiment will be described with reference to the flow charts shown in FIGS. The estimation calculation according to the flowcharts shown in FIGS. 2 and 3 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, at step 10, a signal indicating the wheel speed Vwi detected by the wheel speed sensors 12fl to 12rr is read, and at step 20, with T as the tread, the yaw rate is calculated according to the following equation 1. A speed difference Vyr between the speed at the wheel position and the speed at the center of gravity of the vehicle is calculated.

[Formula 1] Vyr = γ * (T / 2) * 3.6 * π / 180

In step 30, the steering angle δ of the front wheels is calculated according to the following equation 2 using Nsg as the steering gear ratio.

[Equation 2] δ = θ / Nsg

In step 40, W is the weight of the vehicle, H is the height of the center of gravity of the vehicle, and L is the wheel base, and the load movement amount ΔWgx of each wheel due to the longitudinal acceleration Gx is calculated according to the following equation (3).

[Formula 3] ΔWgx = Gx * W * H / L / 2

In step 50, the load movement amounts ΔWgyf and ΔWgyr of the front and rear wheels due to the lateral acceleration Gy are calculated according to the following equation 4 by using Gpf and Gpr as roll rigidity distributions on the front wheel side and the rear wheel side, respectively.

## EQU4 ## ΔWgyf = (Gy * W * H / T) * Gpf ΔWgyr = (Gy * W * H / T) * Gpr

In step 60, K is the tire stiffness and Rt is the tire radius, and the dynamic correction coefficient Kdi of the tire radius of each wheel due to load movement is calculated according to the following equation (5).

## EQU00005 ## Kdfr = 1 + {-. DELTA.Wgx + .DELTA.Wgyf} * 9.8
/ K / Rt Kdfl = 1 + {-ΔWgx-ΔWgyf} * 9.8 / K / R
t Kdrr = 1 + {ΔWgx + ΔWgyf} * 9.8 / K / Rt Kdrl = 1 + {ΔWgx−ΔWgyf} * 9.8 / K / Rt

In step 70, the longitudinal velocity V of the vehicle body at the center of gravity of the vehicle for each wheel is calculated according to the following equation 6.
ri is calculated.

## EQU6 ## Vrfr = Kdfr * Vwfr * cos δ−Vyr Vrfl = Kdfl * Vwfl * cos δ + Vyr Vrrr = Kdrr * Vwrr−Vyr Vrrl = Kdrl * Vwrl + Vyr

In step 80, it is determined whether or not the longitudinal acceleration Gx of the vehicle is positive, that is, whether or not the vehicle is in an accelerating state, and if a positive determination is made, step 90 is entered. In this case, the minimum value of the longitudinal velocity Vri of the vehicle body is selected as the longitudinal velocity Vws, and when a negative determination is made, the maximum value of the longitudinal velocity Vri of the vehicle body is selected as the longitudinal velocity Vws in step 100.

In step 110, Vxf is the vehicle body speed obtained in step 110 one cycle before, and α1 and α2 are positive constants.
The vehicle speed Vx is calculated in accordance with the above. In the following expression 7, MED means selecting an intermediate value of the three numerical values in parentheses.

## EQU00007 ## Vx = MED [Vms, Vxf + .alpha.1, Vxf-.alpha.2]

In step 120, it is judged whether or not the vehicle speed Vx is less than the reference value Vc for behavior control. If a negative judgment is made, the routine proceeds to step 140, and if a positive judgment is made. In step 130, the vehicle body speed Vx is selected as the reference speed Vwsb for calculating the free rotation speed Vbi of each wheel.

In step 140, the behavior controller 2
In step 150, it is determined whether only the outer wheel on the turning side is being braked in order to reduce spin. When a positive determination is made, the vehicle body speed Vri of the front wheel on the turning inner wheel side is selected as the reference speed Vwsb in step 150. If a negative determination is made, the process proceeds to step 160. In step 160, the behavior control device 24 determines whether or not only the rear wheels are being braked in order to reduce drift-out. When a negative determination is made, the routine proceeds to step 130, where an affirmative determination is made. In step 170, the larger one of the vehicle speeds Vfr and Vrfl of the front wheels is selected as the reference speed Vwsb.

In step 180, step 13
Reference speed Vws selected at 0, 150 or 170
Free rotation speed Vbi of each wheel according to the following equation 8 based on b
Is calculated. In the following expression 8, MAX means selecting the larger value of the two values in the parentheses.

## EQU8 ## Vbfr = MAX [(Vwsb + Vyr) * cosδ *
Kdfr, 0] Vbfl = MAX [(Vwsb-Vyr) * cosδ * Kdfl,
0] Vbrr = MAX [(Vwsb + Vyr) * Kdrr, 0] Vbrl = MAX [(Vwsb-Vyr) * Kdrl, 0]

In step 190, the signals indicating the vehicle body speed Vx and the free wheel rotation speed Vbi calculated in steps 110 and 180 are the behavior control device 2.
4 is output.

Thus, in the first embodiment, the speed difference Vyr between the speed at the wheel position and the speed at the center of gravity of the vehicle due to the yaw rate is calculated in step 20, and in step 30. The steering angle δ of the front wheels is calculated,
In step 40, the load movement amount ΔWgx of each wheel due to the longitudinal acceleration Gx is calculated, and in step 50, the load movement amount ΔWgyf and Δ of the front and rear wheels due to the lateral acceleration Gy.
Wgyr is calculated, the dynamic correction coefficient Kdi of the tire radius of each wheel due to load movement is calculated in step 60, and in step 70, the wheel speed Vwi of each wheel and the turning state of the vehicle are set as parameters. Based on this, the longitudinal velocity Vri of the vehicle body at the center of gravity of the vehicle for each wheel is calculated.

Then, in step 80, it is judged whether or not the vehicle is in the accelerating state, and when the vehicle is in the accelerating state, in steps 90 and 110, the calculation is made for the wheel with 0 or the smallest acceleration slip. The vehicle body speed VX is obtained based on the longitudinal velocity of the vehicle body, and when the vehicle is not in the accelerating state, the vehicle body velocity VX is obtained based on the longitudinal velocity of the vehicle body calculated in steps 100 and 110 for the wheel having the zero deceleration slip or the smallest wheel. To be

Therefore, according to the first embodiment, when the vehicle is in an accelerating state, the longitudinal speed Vri calculated for the wheel that has not undergone the acceleration slip or the wheel with the smallest acceleration slip is used as the vehicle body speed. The vehicle body speed of the vehicle can be accurately estimated even when the vehicle is in an accelerating state.

According to the first embodiment, step 4
In 0 to 60, the dynamic correction coefficient Kdi of the tire radius of each wheel due to load movement is calculated, and in the calculation of the vehicle body longitudinal velocity Vri in step 70, the dynamic correction coefficient Kdi is considered. Therefore, as compared with the case where the change in tire radius of each wheel due to load movement is not taken into consideration, the front-rear velocity Vri of the vehicle body at the center of gravity of the vehicle is accurately calculated, and thereby the vehicle body speed Vx is accurately estimated. You can

According to the first embodiment, step 1
At 20, 140 and 160, it is determined whether or not the behavior of the vehicle is controlled. Based on the determination result, the vehicle speed Vri or the vehicle speed VX that does not affect the braking force control by the behavior control is applied to each wheel. Since the free rotation speed Vbi is calculated, the free rotation speed of each wheel can be accurately estimated even when the braking force of the wheel is controlled by the behavior control device.

FIG. 4 shows the present invention applied to a vehicle equipped with a behavior control device for controlling the braking force of each wheel to stabilize the turning behavior of the vehicle and an ABS device for controlling the braking force of each wheel so as not to lock. FIG. 2 is a schematic configuration diagram (A) and a block diagram (B) showing a second embodiment of the estimation device according to the present invention.

The estimation device 14 of this embodiment performs various calculations according to an estimation routine to be described later based on the parameters detected by various sensors as in the estimation device of the first embodiment. The ABS device 26 not only calculates the speed Vb and the free rotation speed Vri of the wheels and outputs a signal indicating the vehicle body speed Vb and the free rotation speed Vri to the behavior control device 24, but also controls so as not to lock the braking force of each wheel. Also, the vehicle body speed Vb and the free rotation speed V
It is designed to output a signal indicating ri.

Next, the outline of the routine for estimating and calculating the vehicle body speed and the free wheel rotation speed in the second embodiment will be described with reference to the flow chart shown in FIG. The estimation calculation according to the flow chart shown in FIG. 5 is also started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, at step 210, a signal indicating the wheel speed Vwi detected by the wheel speed sensors 12fl to 12rr is read, and at step 220, the steering angle δ of the front wheels is calculated according to the above equation 2. With A as the Ackermann ratio, T as the tread, and H as the height of the center of gravity of the vehicle, the steering angles δl and δr of the left front wheel and the right front wheel are calculated according to the following equation 9.

## EQU9 ## δl = [1 + A {1+ (T * δ) / (2 * H)}] * δ δr = [1-A {1- (T * δ) / (2 * H)}] * δ

In step 230, the load movement amount ΔWgx of each wheel due to the longitudinal acceleration Gx is calculated according to the above equation 3, and in step 240, the load movement amount of the front wheel and the rear wheel due to the lateral acceleration Gy according to the above equation 4. ΔWgyf and ΔWgyr are calculated, and in step 250, the dynamic correction coefficient Kdi of the tire radius of each wheel due to the load movement is calculated according to the equation (5).

In step 260, the lateral acceleration Gy and the vehicle body speed Vx calculated in step 280 described later.
And the deviation of the yaw rate γ from the product Vx * γ Gy -Vx * γ
Is the deviation of the lateral acceleration, that is, the lateral slip acceleration of the vehicle Vyd
Is calculated, and the lateral slip velocity Vy of the vehicle body is calculated by integrating the deviation Vyd of the lateral acceleration, and the ratio Vy / Vx of the lateral slip velocity Vy of the vehicle body to the vehicle body speed Vx is calculated.
The slip angle β of the vehicle body at the center of gravity of the vehicle is calculated as

In step 270, the vehicle body speed Vri at the center of gravity of the vehicle for each wheel is calculated in accordance with the following equation 10 using Lf as the distance between the center of gravity and the axle of the front wheel. In Expression 10, Ksi is a static correction coefficient of the tire radius of each wheel calculated by the routine shown in FIG. 6 described later.

[Equation 10] Vrfr = {Ksfr * Kdfr * Vwfr + (T /
2) * γ * cos δr −Lf * γ * sin δr} / cos (β
−δr) Vrfl = {Ksfl * Kdfl * Vwfl + (T / 2) * γ *
cos δl −Lf * γ * sin δl} / cos (β−δl) Vrrr = {Ksrr * Kdrr * Vwrr + (T / 2) * γ}
/ Cos β Vrrl = {Ksrl * Kdrl * Vwrl + (T / 2) * γ}
/ Cos β

In step 280, the vehicle body speed Vx is calculated according to the following equation 11 based on the weight Wi of each wheel and the vehicle body speed Vri of each wheel calculated by the routine shown in FIG.

[Equation 11] Vx = (Wfr * Vrfr + Wfl * Vrfl + Wrr
* Vrrr + Wrl * Vrrl) / (Wfr + Wfl + Wrr + Wr
l)

In step 290, the free rotation speed Vbi of each wheel is calculated according to the following equation 12 based on the vehicle speed Vx.

## EQU12 ## Vbfr = Vx * cos (β-δr)-(T /
2) * γ * cos δr + Lf * γ * sin δr Vbfl = Vx * cos (β-δl) + (T / 2) * γ * co
s δl-Lf * γ * sin δr Vbrr = Vx * cos β- (T / 2) * γ Vbrl = Vx * cos β + (T / 2) * γ

In step 300, the signals indicating the vehicle body speed Vx and the free rotation speed Vbi of each wheel calculated in steps 280 and 290 are the behavior control device 2.
4 and the ABS device 26.

Next, the routine for calculating the weight Wi of each wheel and the static correction coefficient Ksi of the tire radius of each wheel will be described with reference to the flow chart shown in FIG. The routine shown in FIG. 6 is also repeatedly executed at predetermined time intervals, and steps 410 to 450 are executed for each wheel in a time series order, for example, the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel.

First, at step 410, it is determined whether or not the wheel is under the behavior control by the behavior control device 24, that is, whether or not the braking force control for the behavior control is being executed. When a negative determination is made, the routine proceeds to step 430, and when a positive determination is made, the weight Wi is set to Rvsc in step 420.

In step 430, the wheel is AB
Whether or not the S control is being performed, that is, whether or not the braking force control by the ABS device 26 is being performed,
When a positive determination is made, the weight Wi is set to Rabs in step 440, and when a negative determination is made, the weight Wi is set to Rnor in step 450. Rvsc, Rabs, and Rnor are constants that satisfy the following Expression 13.

[Equation 13] Rnor> Rabs> Rvsc = 0

In step 460, the weight Wi of each wheel is calculated according to the following equation 14 using Rf and Rr as coefficients (positive constants) for the front wheel and the rear wheel, respectively.
The coefficients Rf and Rr are Rf when the vehicle is a rear-wheel drive vehicle.
> Rr, and in the case of a front-wheel drive vehicle, Rf <Rr.

[Equation 14] Wfr = Wfr * Rf Wfl = Wfl * Rf Wrr = Wrr * Rr Wrl = Wrl * Rr

In step 470, the static correction coefficient Ksi of the tire radius of each wheel is calculated according to the following equation 15. In addition, R is a filter coefficient, and Ts is a sampling time, and Tr is Ts / Tr, where Tr is a positive constant of about several seconds. Vbi is the free rotation speed of each wheel calculated in step 290, and the static correction coefficient Ksi is set to 1 when this routine is first executed.

[Expression 15] Ksi = (1-R) * Ksi + R * Vbi / Vwi

Thus, in the second embodiment, the steering angles δr and δl of the front wheels are calculated in step 220, and the load movement amount ΔWgx of each wheel due to the longitudinal acceleration Gx is calculated in step 230. In step 240, the load movement amount ΔWgy of the front and rear wheels due to the lateral acceleration Gy
f and ΔWgyr are calculated, and in step 250, the dynamic correction coefficient Kdi of the tire radius of each wheel caused by the load movement is calculated.
Is calculated, and the slip angle β of the vehicle body is calculated in step 260, and in step 270, the vehicle body at the center of gravity of the vehicle for each wheel is calculated based on the wheel speed Vwi of each wheel and the parameter indicating the turning state of the vehicle. The front-rear velocity Vri of V is calculated.

Then, in steps 410 to 460, the weight Wi is calculated according to the braking state of the wheels, and step 2
At 80, the vehicle body speed VX is calculated based on the vehicle body longitudinal speed Vri and the weight Wi, and the free rotation speed Vbi of each wheel is calculated based on the vehicle body speed VX.

Therefore, according to the second embodiment, the weight Wi is calculated as the degree based on the reliable braking state which can be the basis of the vehicle speed calculation, and the vehicle speed Vx is calculated as the weighted average of the longitudinal speed Vri based on the weight Wi. Is calculated,
Even when the wheel is in the state where the braking force is controlled by the behavior control device, the vehicle body speed of the vehicle and the free rotation speed of each wheel can be accurately estimated.

Further, according to the second embodiment, in addition to the dynamic correction coefficient Kdi of the tire radius of each wheel due to the load movement, the static correction coefficient Ksi of the tire radius of each wheel is calculated in step 470. Since both the dynamic correction coefficient Kdi and the static correction coefficient Ksi are taken into consideration in the calculation of the vehicle body front-rear speed Vri in step 270, each wheel is affected by a change in tire air pressure or the like. Even when the tire radius is different from the standard state, the longitudinal velocity Vri of the vehicle body at the center of gravity of the vehicle is calculated more accurately than in the case of the first embodiment, and thereby the vehicle body speed Vx is accurately estimated. be able to.

Further, according to the second embodiment, the Ackermann ratio A is taken into consideration when calculating the steering angle of the front wheels, and the steering angles of the left and right front wheels are accurately calculated. Compared with the case, the longitudinal velocity Vri of the vehicle body at the center of gravity of the vehicle can be accurately calculated, and the vehicle body velocity Vx can be accurately estimated.

The above-described first embodiment is an embodiment applied to a vehicle in which only the behavior control device is installed, but is applied to a vehicle in which an ABS control device or a TRC device is installed in addition to the behavior control device. If so, step 16
If a negative determination is made at 0, it is determined whether ABS control or TRC control is in progress, and the ABS control
When it is determined that the control is being performed, the maximum of Vri of the wheels that are not under ABS control is selected as Vwsb, and when it is determined that the TRC control is being performed, T
The minimum value of Vri of wheels that are not RC controlled is Vws
If b is selected and neither ABS control nor TRC control is executed, the process may proceed to step 130.

In the second embodiment described above, the free rotation speed Vbi of each wheel is calculated in step 290 based on the vehicle body speed Vx calculated in step 280. However, even in this embodiment, the free rotation speed of each wheel is determined by the step 12 in the first embodiment.
It may be calculated according to the same routine as 0 to 180.

Although the present invention has been described above in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are also possible within the scope of the present invention. It will be apparent to those skilled in the art that

[0065]

As is apparent from the above description, according to the configuration of claim 1 of the present invention, the specific position of the vehicle for each wheel is determined based on the wheel speed Vwi of each wheel and the parameter indicating the turning state of the vehicle. The front-rear speed Vri of the vehicle is calculated, and the front-rear speed Vri is calculated according to the braking state of each wheel, in other words, the degree of reliability based on the braking state, which is the basis of the vehicle body speed calculation.
Since the weight Wi of ri is calculated and the vehicle body speed Vx is calculated based on the longitudinal speed Vri and the weight Wi, the vehicle body speed of the vehicle can be accurately estimated even when the wheels are in a braking state.

Further, according to the second aspect of the invention, the longitudinal velocity Vri of each wheel at a specific position of the vehicle is calculated based on the wheel speed Vwi of each wheel and the parameter indicating the turning state of the vehicle, and the vehicle acceleration state is calculated. Based on this, any one of the front-rear speed Vri is selected as the vehicle body speed Vx. In other words, the front-rear speed V calculated for the wheel in which the acceleration slip does not occur.
Since ri is the vehicle body speed, the vehicle body speed of the vehicle can be accurately estimated even when the vehicle is in an accelerating state.

According to the third aspect of the invention, the smallest value of the longitudinal velocity Vri is selected when the vehicle is in the accelerating state, and the longitudinal velocity Vri is selected when the vehicle is not in the accelerating state.
Since the largest value is selected, the vehicle body speed Vx is the front-rear speed of the wheel having the smallest acceleration slip or the smallest acceleration slip when the vehicle is accelerating, and the vehicle body speed Vx is the vehicle speed when the vehicle has no acceleration. Since the speed is used, the vehicle speed of the vehicle can be estimated very accurately even when the vehicle is in an accelerating state.

According to the fourth aspect of the invention, the change in the dynamic load radius of each wheel is detected, and the longitudinal speed Vri is calculated on the basis of the wheel speed Vwi, the parameter indicating the turning state of the vehicle, and the change in the dynamic load radius. Therefore, even when the vehicle turns or accelerates or decelerates, the front-rear speed Vri can be obtained without being affected by the change in the dynamic load radius of the wheels due to the load movement caused by these.

According to the fifth aspect of the present invention, the vehicle body speed estimating apparatus according to the first or second aspect calculates the longitudinal velocity Vri of a specific position of the vehicle for each wheel and obtains the vehicle body velocity Vx. Based on the braking state of each wheel, one of the longitudinal speed Vri and the vehicle body speed Vx, in other words, one of the most reliable vehicle body speeds is selected, and based on that value and the parameter indicating the turning state of the vehicle. Since the free rotation speed Vbi of each wheel is calculated, the free rotation speed of each wheel can be calculated accurately regardless of the braking state of the vehicle.

Further, according to the structure of claim 6, the free rotation speed Vbi of each wheel is calculated based on the vehicle body speed Vx when all the wheels are not in the braking state, and when any of the wheels is in the braking state. Wheel speed Vwi for wheels not in braking
Since it is calculated based on the front-rear speed Vri calculated on the basis of the above, the free rotation speed of each wheel can be obtained very accurately regardless of the braking state of the vehicle.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an estimation device according to the present invention applied to a vehicle equipped with a behavior control device for controlling a braking force of each wheel and stabilizing a turning behavior of the vehicle (A). ) And a block diagram (B).

FIG. 2 is a flowchart showing a first half of an estimation calculation routine of a vehicle body speed and a free wheel rotation speed in the first embodiment.

FIG. 3 is a flowchart showing a latter half of a routine for estimating and calculating a vehicle body speed and a free wheel rotation speed in the first embodiment.

FIG. 4 is an estimation according to the present invention applied to a vehicle equipped with a behavior control device that controls the braking force of each wheel to stabilize the turning behavior of the vehicle and an ABS device that controls so that the braking force of each wheel is not locked. It is the schematic block diagram (A) and block diagram (B) which show 2nd embodiment of an apparatus.

FIG. 5 is a flowchart showing a routine for estimating and calculating a vehicle body speed and a free wheel rotation speed in the second embodiment.

FIG. 6 is a flow chart showing a calculation routine of a dynamic correction coefficient Kdi and a static correction coefficient Ksi of a tire radius of each wheel in the second embodiment.

[Explanation of symbols]

 12fr, 12fl, 12rr, 12rl ... Wheel speed sensor 14 ... Estimating device 16 ... Steering angle sensor 18 ... Longitudinal acceleration sensor 20 ... Lateral acceleration sensor 22 ... Yaw rate sensor 24 ... Behavior control device 26 ... ABS device

Claims (6)

[Claims] 1. A means for detecting a wheel speed Vwi of each wheel, a means for detecting a parameter representing a turning state of the vehicle, a front-rear speed of a specific position of the vehicle for each wheel based on the wheel speed Vwi and the parameter. Front-rear speed calculation means for calculating Vri, and the front-rear speed Vri based on the braking state of each wheel.
Vehicle speed estimating device for a vehicle having means for calculating the weight Wi of the vehicle and means for calculating the vehicle speed Vx based on the longitudinal speed Vri and the weight Wi. 2. A means for detecting a wheel speed Vwi of each wheel, a means for detecting a parameter representing a turning state of the vehicle, and a front and rear speed of a specific position of the vehicle for each wheel based on the wheel speed Vwi and the parameter. Vehicle body speed of a vehicle having front-rear speed calculation means for calculating Vri, means for detecting an acceleration state of the vehicle, and selection means for selecting one of the front-rear speed Vri as the body speed Vx based on the acceleration state. Estimator. 3. The vehicle body speed estimating apparatus according to claim 2, wherein the selecting means selects the smallest value among the longitudinal speed Vri when the vehicle is in an accelerating state, and when the vehicle is not in an accelerating state. A vehicle body speed estimating device for a vehicle, wherein a largest value among the longitudinal speed Vri is selected. 4. A vehicle body speed estimating apparatus for a vehicle according to claim 1 or 2, further comprising means for detecting a change in dynamic load radius of each wheel, wherein the longitudinal speed calculating means includes the wheel speed Vwi and the parameter. And a vehicle body speed estimation device for a vehicle, wherein the longitudinal speed Vri is calculated based on a change in the dynamic load radius. 5. A vehicle body speed estimating device for a vehicle according to claim 1 or 2, and a selecting means for selecting one of the longitudinal speed Vri and the vehicle speed Vx based on a braking state of each wheel. A free wheel rotation speed estimating device for a wheel having one value and means for calculating a free wheel speed Vbi of each wheel based on the parameter. 6. The wheel free rotation speed estimating device according to claim 5, wherein the selecting means selects the vehicle body speed Vx when all the wheels are not in a braking state, and one of the wheels is in a braking state. A free wheel rotation speed estimating device for a wheel, characterized in that the front-rear speed Vri calculated based on the wheel speed Vwi of a wheel which is not in a braking state is sometimes selected.