JPH0616123A - Brake control device - Google Patents

Abstract

PURPOSE:To provide a brake control device by which precise control becomes possible according to a change in road surface conditions or vehicle body behav ior and so on. CONSTITUTION:A brake control device 30 finds a target slip rate according to estimate vehicle body speed, a bank angle and a road surface friction coefficent obtained by an estimate vehicle body speed operation circuit 36, a bank angle operation circuit 42 and a road surface friction coefficient operation circuit 54, and corrects the target slip rate by multiplying the target slip rate by a correction factor determined by a correction factor determining circuit 56 and a road surface condition judging circuit 62 according to road surface conditions or a change in vehicle body behavior, and maintains a smooth vehicle body travel condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for changing a target slip ratio so that an optimum braking force can be obtained during braking.

[0002]

2. Description of the Related Art For example, in automobiles and motorcycles,
A brake control device is known in which a slip ratio of a wheel with respect to a road surface is calculated from the speed of a running vehicle and the rotational speed of a wheel, and the vehicle is optimally braked based on the slip ratio.

The brake control device has a predetermined slip ratio (hereinafter referred to as a target slip ratio) that maximizes the braking force.
Up to increase the braking force by changing the brake fluid pressure according to the amount of depression of the brake pedal (hereinafter referred to as normal control), and when the target slip ratio is reached, limit the increase in brake fluid pressure. Then, control is performed to avoid an increase in the slip ratio (hereinafter referred to as limit control).

In this case, there is a correlation between the slip ratio of the wheel with respect to the road surface and the road surface friction coefficient, and a road surface having a high friction coefficient (hereinafter referred to as a high μ road) and a road surface having a low friction coefficient (hereinafter referred to as a road surface).
The slip ratio that can stably control the vehicle body is different from the low μ road).

Therefore, in the brake control device, in order to widen the range of normal control, the target slip ratio is set on the high μ road side, and when the limit control is entered, the road surface friction coefficient μ is calculated to obtain the target slip ratio. Switching rates. As described above, as a method for starting detection of the road surface friction coefficient μ after switching from the normal control to the limit control, Japanese Patent Laid-Open No.
2-194636.

[0006]

As described above, the brake control device starts detecting the road surface friction coefficient μ after the normal control is switched to the limit control. Therefore, the setting of the target slip ratio may be delayed after the control is switched.

On an actual road, the road surface friction coefficient μ may change with changes in road surface conditions. For example, the slip condition is different between a low μ road such as ice burn and a high μ road such as asphalt road. So, for example,
When the target slip ratio is changed for a road surface (so-called μ-jump road surface) where the road surface condition changes from a low μ road to a high μ road, and normal boosting is performed by conventional brake control, time delay, etc. As a result, the fluctuation range of the braking force becomes large, and there is a problem that the brake feeling such as vibration is deteriorated.

Further, when an automobile or a motorcycle runs, if the road surface is uneven, vibration of the vehicle body increases. Therefore, when the vehicle speed and the road surface friction coefficient are obtained from the output of the sensor or the like, a large amount of noise is included, and it may not be possible to obtain the target slip ratio with accuracy higher than a predetermined value.

Therefore, if the target slip ratio is set by further considering information other than the road surface friction coefficient such as the behavior of the vehicle body and the road surface condition, more precise brake control can be performed.
Therefore, there is a demand for the appearance of a device that sets the target slip ratio based on information such as the behavior of the vehicle body and the road surface condition.

The present invention has been made in order to meet this type of demand, and an object of the present invention is to provide a brake control device capable of precise control based on changes in road surface conditions, vehicle behavior, and the like. And

[0011]

In order to achieve the above object, the present invention provides a bank angle detecting means for detecting a vehicle body inclination angle from a running state of a vehicle, a steering angle detecting means for detecting a steering angle, Estimated vehicle speed calculating means for calculating an estimated vehicle speed based on the wheel speed, a slip ratio of the wheel obtained from the wheel speed and the estimated vehicle speed, and a road surface friction coefficient between the wheel and the road surface based on the vehicle acceleration / deceleration. Road surface friction coefficient calculation means, storage means for storing the relationship between the vehicle body inclination angle, the estimated vehicle body speed and the road surface friction coefficient with respect to a target slip ratio for obtaining an optimum braking force, the vehicle body inclination angle, the estimated vehicle body Target slip ratio setting means for setting the target slip ratio based on the above relationship from the speed and the road friction coefficient, and the target slip ratio when the rate of change of the road friction coefficient is within a predetermined range. Is not changed and is out of the predetermined range, the first correction coefficient setting means for setting the first correction coefficient for suppressing the target slip ratio, and the change rate of the steering angle with respect to the estimated vehicle body speed are equal to or less than a predetermined value. In this case, the target slip ratio is not changed, and when the target slip ratio is equal to or more than a predetermined value, the second correction coefficient setting means sets a second correction coefficient for suppressing the target slip ratio, and the first and second correction coefficients. A target slip ratio correction means for correcting the target slip ratio.

[0012]

In the brake control apparatus according to the present invention, the estimated vehicle speed, the vehicle body speed, the vehicle body speed, the vehicle body inclination angle, and the road surface friction coefficient are related to the target slip ratio for obtaining the optimum braking force stored in the storage means. A target slip ratio that provides a precise braking force is set from the inclination angle and the road friction coefficient. Further, the first correction coefficient is obtained based on the change rate of the road surface friction coefficient, the second correction coefficient is obtained based on the change rate of the steering angle with respect to the estimated vehicle speed, and the target slip rate is calculated by the first and second correction coefficients. to correct. Therefore, the target slip ratio in consideration of the road surface condition or the vehicle behavior can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake control device according to the present invention will be described in detail below with reference to the accompanying drawings with reference to preferred embodiments.

In FIG. 2, reference numeral 10 indicates a motorcycle, and the motorcycle 10 includes a main body portion 12, a front wheel portion (driven wheel) 14, a rear wheel portion (driving wheel) 16, and a handle portion 1.
8 and. In the front wheel portion 14 and the rear wheel portion 16,
A driven wheel rotation speed detection sensor 20 and a drive wheel rotation speed detection sensor 22 each including a rotary encoder and the like are provided, and a vehicle body acceleration / deceleration detection sensor 24 is provided in the main body portion 12.
However, the steering angle detection sensor 26 is provided on the handle portion 18. The sensors 20, 22, 24 and 26 are connected to a control unit 28, which constitutes a brake control device 30 shown in FIG.

The control unit 28 is a driven wheel.
Rotational speed detection sensor 20 and drive wheel rotational speed detection sensor
From the output signal of the service 22, the vehicle of the front wheel portion 14 and the rear wheel portion 16
Wheel speed V_wf, V_wrA wheel speed calculation circuit 32 for calculating
From the output signal of the vehicle body acceleration / deceleration detection sensor 24 to the motorcycle
Acceleration / deceleration determination circuit 34 for determining the acceleration / deceleration state of the vehicle 10,
Wheel speed signal from the wheel speed calculation circuit 32, vehicle body acceleration / deceleration
Vehicle body acceleration / deceleration signal from the detection sensor 24 and acceleration / deceleration judgment
Estimated vehicle speed based on the acceleration / deceleration determination signal from the separate circuit 34
V_refAn estimated vehicle speed calculation circuit 36 for calculating
Wheel speed V_wf, V _wrAnd estimated vehicle speed V_refFrom slip rate
S_f, S_rSlip ratio calculating circuit 38 for obtaining
Lip rate S_f, S_rBraking was done based on
Brake signal λ_B1, Λ_B2To generate
The rake signal generating circuit 40 and the estimated vehicle speed V_refWhen
The wheel speed V_wf, V_wrAnd the brake signal λ_B1, Λ_B2
And the steering angle signal detected by the steering angle detection sensor 26.
Bank angle θ_BA bank angle calculation circuit 42 for determining
A look-up to be described later that is output to the bank angle calculation circuit 42.
Table (hereinafter referred to as LUT) 44, 46, 48
And the wheel speed V_wf, V_wrTo wheel acceleration / deceleration α_wf, Α
_wrWheel acceleration / deceleration calculation circuit 50 for determining
Speed α_wf, Α_wrAnd the slip ratio S_f, S_rOn the basis of
A gate signal generating circuit 52 for outputting a gate signal, and
Based on the gate signal, the vehicle body acceleration / deceleration Gx and the slip ratio S
_f, S_rCalculate road friction coefficient μ from road surface friction coefficient calculation
The circuit 54, the road surface friction coefficient μ and the bank angle θ_BBased on
And a correction coefficient determination circuit 56 for obtaining the correction coefficient ηj,
An LUT 58 connected to the correction coefficient determination circuit 56;
Road friction coefficient storage circuit 60, steering angle signal and estimated vehicle body
Speed V_refDetermine the road surface condition based on the
The road surface condition determination circuit 62 that outputs the estimated vehicle body speed V
_refAnd the bank angle θ_BAnd road surface friction coefficient μ and correction coefficient η
The target slip that obtains the optimum braking force from j and the correction coefficient η1.
The target slip ratio calculation circuit 64 for obtaining the slip ratio S1
The LUT 65 connected to the target slip ratio calculation circuit 64
And the target slip ratio S1 and the preset target slip
Suppression coefficient calculation for obtaining the suppression coefficient K from the ratio with the increase rate S0
And a circuit 66.

The brake control device 3 having the above structure
For 0, the suppression coefficient K is obtained as follows.

That is, K = Smax / S0 × ηj × η1, where Smax is the estimated vehicle speed V _ref and the bank angle θ _B.
And the target slip ratio calculated based on the road surface friction coefficient μ.

The braking coefficient K thus obtained is multiplied by the signal of the output device such as the valve signal to perform the actual brake control.

Here, first, the method for obtaining the estimated vehicle speed V _ref , the bank angle θ _B , and the road surface friction coefficient μ will be described, and then the method for obtaining the target slip ratio Smax, the correction coefficients ηj, and η1 will be sequentially described.

In this embodiment, the wheel velocities V _wf and V _wr of the driven wheels and the drive wheels are obtained, and the estimated vehicle body velocity V _ref is obtained from the wheel velocities V _wf and V _wr . Here, first, the estimated vehicle speed V is _calculated from the wheel speed V _{wf of} the driven wheels (front wheel portion 14).
A method for obtaining _ref will be described with reference to the flowchart of FIG. 3 and FIGS. 4 and 5, and a similar drive wheel (rear wheel portion 1
A description of how to obtain the estimated vehicle body speed V _ref on the 6) side is omitted. The estimated vehicle body speed calculation circuit 36 calculates the estimated vehicle body speed V _{ref (n)} as follows at every predetermined calculation cycle t. Here, (n) indicates a value in the n-th calculation.

First, while the motorcycle 10 is running,
The driven wheel rotation speed detection sensor 20 is configured to drive the driven wheel (front wheel portion 1
The rotation of 4) is detected as a pulse signal and output to the wheel speed calculation circuit 32. The wheel speed calculation circuit 32 obtains the wheel speed V _{wf (n)} based on the pulse signal and outputs it to the estimated vehicle body speed calculation circuit 36 (step S1).

On the other hand, the vehicle body acceleration / deceleration detection sensor 24 provided in the main body 12 detects the vehicle body acceleration / deceleration Gx and outputs it to the acceleration / deceleration determination circuit 34 and the estimated vehicle body speed calculation circuit 36 (step S2).

Therefore, the acceleration / deceleration determination circuit 34 determines that the vehicle body acceleration / deceleration Gx is a predetermined value β (β> 0) or more (| Gx |>
It is determined whether or not β) (step S3). When the vehicle body acceleration / deceleration Gx is less than or equal to a predetermined value β (| Gx | <β), there is no acceleration / deceleration, or vice versa (| Gx |>
In β), it is determined that acceleration / deceleration is in progress.

When it is determined that there is no acceleration / deceleration, as shown in FIG. 4, the difference between the wheel speed V _{wf (n )} and the actual vehicle body speed V _i is usually small, and the vehicle body acceleration / deceleration is also small. This is because it is considered that the vehicle body acceleration / deceleration Gx obtained from the detection sensor 24 contains noise due to vibration of the motorcycle 10 or the like. Therefore, when an acceleration / deceleration determination signal indicating no acceleration / deceleration is supplied from the acceleration / deceleration determination circuit 34, the estimated vehicle body speed calculation circuit 36 calculates the estimated vehicle body speed V _{ref (n} by a preset acceleration / deceleration as described below. ₎ .

That is, when it is determined in step S3 that there is no acceleration / deceleration, the wheel speed V _{wf (n)} input this time is the estimated vehicle body speed V _{ref (n-1)} calculated in the previous calculation. It is determined whether or not it is larger than (step S4). If it is determined that the wheel speed V _{wf (n)} is greater than the estimated vehicle body speed V _{ref (n-1)} , the estimated vehicle body speed V _{ref (n)} is obtained as follows (step S5 _). ).

V _{ref (n)} = V _{ref (n-1)} + G ₁ × t Here, G ₁ (> 0) is a preset acceleration, and t is a calculation cycle.

Further, when the wheel speed V _{wf (n)} is determined to be smaller than the estimated vehicle speed V _{ref (n-1)} in step S4, furthermore, the estimated vehicle speed V _{ref (n-1 )} Is the wheel speed V
It is determined whether or not it is larger than _{wf (n )} (step S
6). If the estimated vehicle body speed _{Vref (n-1)} is larger than the wheel speed _{Vwf (n)} , the estimated vehicle body speed _{Vref (n)} is obtained as follows (step S7).

V _{ref (n)} = V _{ref (n-1)} -G ₂ × t where G ₂ (> 0) is a preset deceleration and t is a calculation cycle.

In step S6, the estimated vehicle speed V
_{When ref (n-1)} is not larger than the wheel speed V _{wf (n)} , that is, when both are determined to be equal, the estimated vehicle body speed V _{ref (n)} is obtained as follows (step S8).

V _{ref (n)} = V _{ref (n-1) As} described in steps S4 to S8, the wheel speed V _{wf (n)} is compared with the estimated vehicle speed V _{ref (n-1)} , based on the results, by calculating the estimated vehicle speed V _{ref (n),} as shown in FIGS. 4 and 5, the estimated vehicle speed V _{ref (n)} is calculated with high accuracy.

On the other hand, in the motorcycle 10, for example, slippage occurs between the wheels and the road surface during deceleration, so that the difference between the wheel speed V _wf and the actual vehicle body speed V _i becomes large as shown in FIG. . Therefore, the estimated vehicle speed V is _calculated based on the wheel speed V _{wf (n)} as shown in steps S4 to S8.
_{When ref (n)} is calculated, a highly accurate estimated vehicle body speed V _ref close to the actual vehicle body speed V _i cannot be obtained.

Therefore, when the acceleration / deceleration determination circuit 34 determines that the vehicle body acceleration / deceleration Gx is equal to or greater than the predetermined value β, it is determined that the vehicle body is being accelerated / decelerated, and the estimated vehicle body speed V _{ref ( The} method of obtaining _n) is switched (step S9).

V _{ref (n)} = V _{ref (n-1)} + ∫Gxdt where t is the calculation cycle.

Therefore, the estimated vehicle body speed V _{ref (n)} can be obtained with high accuracy by using the value of the vehicle body acceleration / deceleration Gx only when the acceleration / deceleration is determined.

Estimated vehicle speed V thus obtained
_{ref (n)} , the wheel speed V _{wf (n) of} the front wheel portion 14 and the rear wheel portion 16,
V _{wr (n)} is output to the slip ratio calculation circuit 38, and the front wheel portion 14 and the rear wheel portion are based on the estimated vehicle body speed V _{ref (n)} and the wheel speeds V _{wf (n)} and V _{wr (n).} The brake signal generating circuit 4 calculates the slip ratios S _{f (n)} and S _{r (n)} of each of the sixteen.
Output to 0. In the brake signal generation circuit 40, when the slip ratios S _{f (n)} and S _{r (n)} are 3% or more, it is determined that the brake is operating, and each brake signal λ
_{B1 (n)} and λ _{B2 (n)} are set to "1" and output to the bank angle calculation circuit 42.

The bank angle calculation circuit 42 calculates the bank angle θ _B as follows. A method of calculating the bank angle will be described with reference to the flowchart of FIG.

First, the estimated vehicle obtained as described above
Body speed V_{ref (n)}, Wheel speed V_{wf (n)}, V_{wr (n)}, Brae
Signal λ_{B1 (n)}, Λ_{B2 (n)}And the steering angle detection sensor 26
Detected rudder angle θ_{h (n)}Is read (step S21).
Then, the brake signal λ _{B1 (n)}, Λ_{B2 (n)}OR of
Is 1 or not, that is, the brake is operating
It is determined whether or not (step S22). Brake in operation
If so, the estimated vehicle speed V_{ref (n)}Is 60 km /
It is determined whether or not h or less (step S23). Guess
Constant vehicle speed V_{ref (n)}Is less than 60 km / h, the estimation
Vehicle speed V_{ref ( n)}And rudder angle θ_{h (n)}To LUT4 shown in FIG.
Bank angle θ by 4_{B (n)}Is calculated (see FIG. 8 (I)).
As shown in FIG. 7, the LUT 44 contains experimental data.
Each steering angle θ set based on_hIn case of
Estimated vehicle speed V_refAnd bank angle θ _BThe relationship with
Based on this, the bank angle θ_{B (n)}(Fig. 7
(See arrow) (step S24).

In step S23, the estimated vehicle speed V
_{When ref (n)} is larger than 60 km / h, the bank angle θ _{B (n)} is retained as the previous bank angle θ _{B (n-1)} (FIG. 8 ₎ .
(See (II)) (step S25). This is because when the brake is operating and the estimated vehicle body speed V _{ref ( n)} is larger than 60 km / h, the value of the wheel speed difference ΔV _W described later is small because the brake is operating, and the bank angle θ _{B ( This is because n)} cannot be obtained accurately.

If it is determined in step S22 that the brake is not operating (λ _{B1 (n)} + λ _{B2 (n)} = 0), the estimated vehicle body speed V _{ref (n)} is further larger than 60 km / h. It is determined whether or not (step S26). If the estimated vehicle body speed V _{ref (n)} is greater than 60 km / h, then it is determined whether the estimated vehicle body speed V _{ref (n)} is 70 km / h or less (step S27). Estimated vehicle speed V
_{ref (n)} is 70km / h or less, that is, 60km / h <
When V _{ref (n)} ≦ 70 km / h, it is determined whether the steering angle θ _{h ( n)} is 2 ° or less (step S28).
If it is determined in step S28 that the steering angle θ _{h (n)} is 2 ° or less, or in step S26, the estimated vehicle speed V
_{When ref (n)} is determined to be 60 km / h or less, it is determined that the bank angle θ _{B ( n)} and the steering angle θ _{h (n)} have a correlation, and the wheel speed V _{wf (n )} And the steering angle θ _{h (n),} L shown in FIG.
The bank angle θ _{B (n)} is calculated by the UT 46 (Fig. 8 (IV) (I
II)). The LUT 46 stores the relationship between the wheel speed V _{wf (n)} and the bank angle θ _B for each steering angle θ _h set based on the experimental data.
Based on this, the bank angle θ _{B (n)} is obtained (see the arrow in FIG. 9) (step S29).

The estimated vehicle speed V _{ref (n)} is 70 km / h or more, or the estimated vehicle speed V _{ref (n)} is 60 km / h.
When the steering angle θ _{h (n)} is more than 70 km / h and the steering angle θ _{h (n)} is larger than 2 ° (steps S27 and S28), there is a correlation between the bank angle θ _{B (n)} and the steering angle θ _{h (n).} When it is determined that there is no such difference, the wheel speed difference ΔV _{w (n)} between the wheel speeds V _{wf (n)} and V _{wr (n)} of the front wheel portion 14 and the rear wheel portion 16 is obtained (step S30). continue,
The bank angle θ _{B ( n)} is obtained from the wheel speed V _{wf (n) of the} front wheel portion 14 and the wheel speed difference ΔV _{w (n)} by the LUT 48 shown in FIG. 10 (see FIGS. 8 (VI) and (V)). The wheel speed difference Δ set on the basis of experimental data is set in the LUT 48.
Wheel speed V _{wf (n)} and bank angle θ _B when V _{w (n)}
And the bank angle θ is stored based on this relationship.
_{B (n)} is calculated (see arrow in FIG. 10) (step S31).
This is because the wheel radii of the front and rear wheels are different and the wheel speed difference Δ
Together produce V _w, since a change in actual wheel the wheel speed difference [Delta] V _w rotation radius is changed in the bank angle theta _B, bank angle theta _B is obtained accurately.

In this way, after obtaining the bank angle θ _{B (n)} in steps S24, S25, S29, and S31, the calculation of the bank angle θ _{B (n)} is repeated (step S32).

In this embodiment, the wheel accelerations / decelerations α _wf and α _wr and the slip ratios S _f and S _r of the driven wheel and the driving wheel are calculated,
The road surface friction coefficients μ _f and μ _r are obtained. Here, first, the road surface friction coefficient μ on the driven wheel (front wheel portion 14) side
How to obtain _f will be described with reference to FIG.

A signal relating to the wheel speed V _wf of the front wheel portion 14 obtained by the wheel speed calculation circuit 32 is output to the wheel acceleration / deceleration calculation circuit 50. Wheel acceleration / deceleration calculation circuit 50
_Calculates the wheel acceleration / deceleration α _wf based on the wheel speed V _wf .

The slip calculated by the slip ratio calculation circuit 38
Up rate S_fIs the wheel acceleration / deceleration α _wfWith the gate
It is output to the signal generation circuit 52. Gate signal generation circuit 5
2, in S, as shown in FIG._fIf> 0, then
Slip that goes high when slipping
Confirmation signal and α_wf≤-α_s(Α_sIs a positive predetermined value)
In other words, that is, the wheel acceleration / deceleration α_wfIs less than the specified value
Generates a high speed wheel deceleration confirmation signal and
Road friction coefficient calculation circuit 5 using the logical product of the numbers as a gate signal
Output to 4. Note that this gate signal is generated
The brake control signal limits the brake oil pressure.
It is suggested that there is a possibility that it will come to you.

The road surface friction coefficient calculation circuit 54 detects the rising edge of the gate signal and starts calculation. The slip ratio S _r of the rear wheel portion 16 and the vehicle body acceleration / deceleration Gx obtained in the same manner as the front wheel portion 14 are output to the road surface friction coefficient calculation circuit 54.

In the road surface friction coefficient calculation circuit 54, the rear wheel 1
Based on the slip ratio S _{r of} 6 and the vehicle body acceleration / deceleration Gx, the road surface friction coefficient μ _f on the front wheel portion 14 side is obtained by the following equation.

Μ _f = (A−B × Kx) × Gx Here, A and B are constants, and Kx is a coefficient set in advance corresponding to the slip ratio S _r .

That is, from the vehicle body acceleration / deceleration Gx to the front wheel portion 1
When determining the road surface friction coefficient μ _f on the 4 side, by subtracting the B × Kx relating to the road surface friction coefficient μ _r on the rear wheel portion 16 side as a correction term, the road surface friction coefficient μ _f only on the front wheel portion 14 can be accurately calculated. Can be detected.

Similar to the case of the front wheel section 14, a gate signal is issued only when the wheel acceleration / deceleration α _wr and the slip rate S _r satisfy predetermined conditions, and the slip rate S _f of the front wheel section 14 and the vehicle body acceleration / deceleration Gx are generated. Based on, the road surface friction coefficient μ _r on the rear wheel portion 16 side can be obtained.

Estimated vehicle body speed V thus obtained
_{The ref (n)} , the bank angle θ _{B (n)} and the road surface friction coefficient μ _(n) are output to the target slip ratio calculation circuit 64. In the target slip ratio calculation circuit 64, the target slip ratio Sma is calculated as follows.
Seeking x.

First, as shown in FIGS. 12 to 14, a relational diagram between the estimated vehicle speed V _ref and the optimum slip ratio SA at which the optimum braking force obtained experimentally is obtained, the road surface friction coefficient μ and the optimum slip. The relationship diagram with the ratio SB and the relationship diagram with the bank angle θ _B and the optimum slip ratio SC are converted into the following expressions.

The optimum slip ratio SA with respect to the estimated vehicle body speed V _ref is approximated as follows.

SA = d−e × V _ref where SA is the slip ratio at which the optimum braking force is obtained,
d and e are constants.

Optimal slip ratio S for road surface friction coefficient μ
B is approximated as follows.

SB = f / μ + g where SB is the slip ratio at which the optimum braking force is obtained,
f and g are constants.

Optimal slip ratio SC for bank angle θ _B
Is approximated as follows.

SC = h−i × θ _B where SC is the slip ratio at which the optimum braking force is obtained,
h and i are constants.

Therefore, from the estimated vehicle speed V _{ref (n)} , the road surface friction coefficient μ _(n) , and the bank angle θ _{B (n)} calculated based on the slip ratios SA, SB, and SC at which the optimum braking force can be obtained. Although the target slip ratio Smax can be directly calculated, the following work is performed here to reduce the parameter to two.

In order to convert the road surface friction coefficient μ and the bank angle θ _B into one parameter, the optimum slip ratio SD obtained by the road surface friction coefficient μ and the bank angle θ _B was approximated as follows.

SD = j × θ _B / μ + k where SD is the slip ratio at which the optimum braking force is obtained,
j and k are constants.

The target slip ratio Smax _(n) is calculated from the experimentally obtained function f (SA, SD) (see FIG. 15) stored in the LUT 65 from the optimum slip ratios SA and SD thus obtained. Ask.

For example, the calculated estimated vehicle speed V _{ref (n)}
From the road surface friction coefficient μ _(n) and the bank angle θ _{B (n), the} optimum slip ratio SA _(n) is calculated from the optimum slip ratio SD _{(n).
When (n)} is calculated, the target slip ratio Smax _(n) is obtained as shown in FIG.

The target slip ratio Smax _(n) thus obtained is multiplied by the correction coefficients ηj and η1 so that the vehicle body behavior does not suddenly change according to the road surface condition.

First, a method of obtaining the correction coefficient ηj will be described.

First, how to obtain the correction coefficient ηj for the target slip ratio Smax on the driven wheel (front wheel portion 14) side will be described with reference to FIG. The correction coefficient ηj of the driven wheel (front wheel portion 14) and the driving wheel (rear wheel portion 16) can be independently obtained. Brake control device 30
Is a correction coefficient η for each predetermined calculation cycle t as follows.
Find j (n). Here, (n) indicates a value in the n-th calculation.

The road surface friction coefficient μ _(n) is supplied from the road surface friction coefficient calculation circuit 54 to the correction coefficient determination circuit 56 and the road surface friction coefficient storage circuit 60, respectively. Also, the bank angle θ
_{B (n)} is the correction coefficient determination circuit 5 from the bank angle calculation circuit 42.
6 is supplied.

The correction coefficient determination circuit 56 reads out the road surface friction coefficient μ _(n-1) obtained by the previous calculation from the road surface friction coefficient storage circuit 60, and changes the road surface friction coefficient μ, that is, μ _{(n )} / Μ _(n-1) is calculated. Subsequently, based on the LUT 58 (see FIG. 16), the bank angle θ _{B (n)} is distinguished by being equal to or larger than the predetermined value θ ₀ , and μ _(n) /
from the value of μ _(n-1) value and μ _(n-1), obtains a correction factor ηj _(n).

Next, how to obtain the correction coefficient η1 will be described. In this case, the road surface condition is determined (correction coefficient η1 is output) based on the estimated vehicle speed V _{ref (n)} and the steering angle θ _{h (n)} detected by the steering angle detection sensor 26. The determination of the road surface condition will be described with reference to the flowchart of FIG. 17 and FIG.

First, the estimated vehicle body speed V _{ref (n)} calculated as described above and the steering angle θ _{h (n)} detected by the steering angle detection sensor 26 are output to the road surface condition determination circuit 62 (step S41). Then, the estimated vehicle speed _{Vref (n)} is Va
It is determined whether or not the following (step S42). When the estimated vehicle speed V _{ref (n)} is Va or less, it is further determined whether or not the differential value of the steering angle θ _{h (n)} is a predetermined value c or more (see the straight line portion in FIG. 18) ( Step S43). In step S42, when the estimated vehicle speed V _{ref (n)} is larger than Va, the differential value of the steering angle θ _{h (n)} is C × (D−E × V _{ref (n).} ) / V _{ref (n)} or more is determined (see the curved line portion in FIG. 18) (step S
44). Here, C, D, and E are constants. In step S43 and step S44, when the differential value of the steering angle θ _{h (n)} is greater than or equal to the predetermined value c, or C × (D−E × V
If it is greater than or _{equal to ref (n)} ) / _{Vref (n) (} see the shaded area in FIG. 18), it is determined whether or not this continues m times consecutively (step S45). When it continues for m times or more, it is determined that the handle portion 18 is displaced due to the unevenness of the road surface rather than the influence of the steering wheel operation, and the road surface condition determination signal (correction coefficient η1) is output as the target slip ratio calculation circuit. 64
(Step S46). After it is determined in step S46 that the road surface condition is bad (correction coefficient η1 = β is output, where 0 <β <1), or in step S43,
After the conditions are not satisfied in steps S44 and S45, it is determined that the road surface condition is not bad (correction coefficient η1 = 1 is output), and then the road surface condition determination is repeated again (step S47).

The correction coefficient ηj thus obtained
_(n) and η1 _(n) are output to the target slip ratio calculation circuit 64. In the target slip ratio calculation circuit 64, the correction coefficient η
The target slip ratio Smax _(n) is corrected by j _(n) and η1 _(n) as follows.

S1 _(n) = Smax _(n) × η1 _(n) × ηj _(n) where S1 _(n) is the corrected target slip ratio.

By thus correcting the target slip ratio Smax _(n) according to the road surface condition, the following effects can be obtained. That is, when the target slip ratio Smax _(n) is calculated based on the estimated vehicle speed V _{ref (n)} , the road surface friction coefficient μ _(n) , and the bank angle θ _{B (n)} , the road surface friction coefficient μ
If only _(n) changes, the following calculation is performed using the road surface friction coefficient μ _(n) .

Smax _(n) = f (μ _(n) ) × Smax _(n-1) where f (μ) is a function that changes as shown by the chain double-dashed line in FIG. 19, Smax _(n-1) Is the target slip ratio calculated by the ₍ n-1) th calculation, and Smax _(n) is the target slip ratio calculated by the nth calculation.

Therefore, as shown in FIG. 19, the function f (μ) representing the relationship of the slip ratios that can obtain the maximum braking force in the case of the road surface condition of the road surface friction coefficient μ _(n) is calculated as the target slip ratio. By multiplying Smax _(n-1) , the target slip ratio S that gives the maximum braking force according to the road surface condition
You can set max _(n) .

Subsequently, this target slip ratio Smax _(n)
Is multiplied by the correction coefficients η j _(n) and η1 _(n) .

S1 _(n) = ηj _(n) × η1 _(n) × Smax _{(n) In} this case, for example, when the vehicle body travels from a low μ road to a high μ road, a μ jump road surface is formed at a turning point, Although the braking force may significantly increase as shown by the broken line arrow A in FIG. 19, the target slip ratio is lowered as shown by the solid line arrow B in FIG. 19 by multiplying by the correction coefficient η j _(n) . It is possible to prevent the braking force from changing significantly. Therefore, by obtaining the target slip ratio S1 _(n) corrected in this way, it becomes possible to maintain smooth running of the vehicle body regardless of changes in the road surface condition.

Similarly, it is possible to maintain smooth running of the vehicle body by determining the unevenness of the road surface based on the change rate of the steering angle θ _h and multiplying the correction coefficient η1 by the target slip rate Smax. Become.

The corrected target slip ratio S1 _(n) thus obtained is output to the suppression coefficient calculation circuit 66. In the suppression coefficient calculation circuit 66, a suppression coefficient (S which is a ratio to a preset target slip ratio S0 is set.
1 / S0) is calculated. By the suppression coefficient K thus obtained, it is possible to suitably suppress the rate of pressure increase / decrease.

In the brake control device 30 in this embodiment,
Is the estimated vehicle speed V_ref, Road friction coefficient μ, and van
Angle θ_BThe target slip that gives the optimum braking force based on
Since the up ratio Smax is calculated,
Good brake control is performed. Also, based on the road condition
Then, the correction coefficients η1 and ηj are calculated based on
By multiplying ηj by the target slip ratio Smax,
The target slip ratio Smax is corrected. Therefore, the break
Even if the road surface condition changes during braking, the braking force changes significantly.
The vehicle body can run smoothly without doing. Furthermore, the road surface
When calculating the friction coefficient μ, the gate signal generating circuit 52
The road friction coefficient μ during normal braking control._f,
μ_rIs calculated, and the road surface friction is
Friction coefficient μ _f, Μ_rThe optimum target slip ratio Sma
x can be set and precise brake control is possible.
Become.

The rate of change of the road surface friction coefficient μ _(n) / μ
If the table set in the LUT 58 according to _(n-1) is further subdivided, more precise control becomes possible.

Further, when adding this function to the existing vehicle body control system that does not incorporate the vehicle body behavior,
The target slip ratio can be corrected only by multiplying the target slip ratio obtained as the calculation result by the suppression coefficient K.

[0082]

According to the brake control device of the present invention, the following effects can be obtained.

That is, the estimated vehicle speed with respect to the target slip ratio that can obtain the optimum braking force stored in the storage means,
Based on the relationship between the vehicle body inclination angle and the road surface friction coefficient, a target slip ratio that gives an optimum braking force is set from the estimated vehicle body speed, the vehicle body inclination angle, and the road surface friction coefficient. Therefore,
Optimal brake control is performed based on vehicle body behavior other than the road friction coefficient. Further, the first correction coefficient is obtained based on the change rate of the road friction coefficient, the second correction coefficient is obtained based on the change rate of the steering angle with respect to the estimated vehicle speed, and the first and second correction coefficients are set as the target slip rate. By riding, the target slip ratio is corrected due to changes in road surface conditions or vehicle behavior. Therefore, even if the road surface suddenly changes, a smooth running state is maintained. Further, since the calculation instruction means calculates the road surface friction coefficient, the road surface friction coefficient is obtained before the brake control device enters the limit control. Based on this, the road surface friction coefficient is calculated from the beginning when switching to the limit control. Brake control is performed based on.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a brake control device according to the present invention.

FIG. 2 is an explanatory diagram of a motorcycle equipped with a brake control device according to the present invention.

FIG. 3 is a flowchart showing a method for calculating an estimated vehicle body speed in the brake control device according to the present invention.

FIG. 4 is a diagram showing a calculation result of an estimated vehicle body speed in the brake control device according to the present invention.

FIG. 5 is a diagram showing a method of calculating an estimated vehicle body speed in the brake control device according to the present invention.

FIG. 6 is a flowchart showing a bank angle calculation method in the brake control device according to the present invention.

FIG. 7 is a diagram showing a relationship between an estimated vehicle speed and a bank angle when the steering angle is set in the brake control device according to the present invention.

FIG. 8 is a table showing a bank angle calculation method in the brake control device according to the present invention.

FIG. 9 is a diagram showing the relationship between the wheel speed of the driven wheels and the bank angle in the case of a certain steering angle in the brake control device according to the present invention.

FIG. 10 is a relationship diagram between the wheel speed of the driven wheel and the bank angle in the case where there is a certain wheel speed difference between the driven wheel and the drive wheel in the brake control device according to the present invention.

FIG. 11 is a diagram showing a method of generating a gate signal in the brake control device according to the present invention.

FIG. 12 is a reference diagram showing the relationship between the estimated vehicle body speed and the optimum slip ratio in the brake control device according to the present invention.

FIG. 13 is a reference diagram showing a relationship between a road surface friction coefficient and an optimum slip ratio in the brake control device according to the present invention.

FIG. 14 is a reference diagram showing the relationship between the bank angle and the optimum slip ratio in the brake control device according to the present invention.

FIG. 15 is a diagram showing how to obtain a target slip ratio in the brake control device according to the present invention.

FIG. 16 is an explanatory diagram of a table used to determine a correction coefficient in the brake control device according to the present invention.

FIG. 17 is a flowchart showing a road surface condition determination method in the brake control device according to the present invention.

FIG. 18 is an explanatory diagram showing a road surface condition determination standard in the brake control device according to the present invention.

FIG. 19 is a diagram showing a correction state of the target slip ratio in the brake control device according to the present invention.

[Explanation of symbols]

 10 ... Motorcycle 14 ... Front wheel part 16 ... Rear wheel part 20 ... Driven wheel rotation speed detection sensor 22 ... Drive wheel rotation speed detection sensor 24 ... Vehicle body acceleration / deceleration detection sensor 26 ... Steering angle detection sensor 30 ... Brake control device 32 ... Wheels Speed calculation circuit 36 ... Estimated vehicle speed calculation circuit 38 ... Slip ratio calculation circuit 40 ... Brake signal generation circuit 42 ... Bank angle calculation circuit 44, 46, 48, 58, 65 ... Look-up table 52 ... Gate signal generation circuit 54 ... Road surface Friction coefficient calculation circuit 56 ... Correction coefficient determination circuit 62 ... Road surface condition determination circuit 64 ... Target slip ratio calculation circuit 66 ... Suppression coefficient calculation circuit

Claims (2)

[Claims] 1. A bank angle detecting means for detecting a vehicle body inclination angle from a running state of a vehicle, a steering angle detecting means for detecting a steering angle, and an estimated vehicle body speed calculating means for calculating an estimated vehicle body speed based on a wheel speed. A road surface friction coefficient calculating means for calculating a road surface friction coefficient between the wheel and the road surface based on a vehicle slip rate obtained from the wheel speed and the estimated vehicle body speed and a vehicle body acceleration / deceleration, and a target for obtaining an optimum braking force. Storage means for storing the relationship between the vehicle body inclination angle, the estimated vehicle body speed, and the road surface friction coefficient with respect to the slip rate, and a target for setting a target slip rate based on the relationship from the vehicle body inclination angle, the estimated vehicle body speed, and the road surface friction coefficient When the rate of change of the road surface friction coefficient is within a predetermined range, the target slip rate is not changed, and when the rate of change of the road surface friction coefficient is outside the predetermined range, the target slip rate is not changed. A first correction coefficient setting means for setting a first correction coefficient to be suppressed, and a target slip ratio which is not changed when the rate of change of the steering angle with respect to the estimated vehicle speed is not more than a predetermined value Includes a second correction coefficient setting unit that sets a second correction coefficient that suppresses the target slip ratio, and a target slip ratio correction unit that corrects the target slip ratio by the first and second correction coefficients. A brake control device characterized by the above. 2. The brake control device according to claim 1, wherein the road surface friction coefficient calculation means obtains a slip ratio of the wheel from a wheel speed of one of the vehicles having front wheels and rear wheels and an estimated vehicle body speed. Slip ratio calculating means, second slip ratio calculating means for obtaining the slip ratio of the wheel from the other wheel speed and estimated vehicle speed, vehicle body acceleration / deceleration detecting means for detecting vehicle body acceleration / deceleration, and rotation of the one wheel Wheel acceleration / deceleration calculating means for obtaining the rotation acceleration / deceleration of the wheel from the speed, a slip ratio of the one wheel, and a calculation for outputting a calculation instruction signal when the one wheel acceleration / deceleration satisfies predetermined conditions. And a road surface friction coefficient for the one wheel, based on the slip ratio of the other wheel and the vehicle body acceleration / deceleration, based on the calculation instruction signal. Brake control apparatus according to claim Rukoto.