JPH04185562A - Braking force controller - Google Patents

Abstract

PURPOSE:To achieve more appropriate integration and control for the braking force control in such a control region that the control of vehicle behavior and the control in the degree of wheel slipping are achieved simultaneously, by preceding the braking force control through the control of slipping degree when both of the control methods are not considered to be achieved simultaneously. CONSTITUTION:While first braking force control is carried out by generating difference in right and left braking forces of wheels to be controlled by a braking force control means B according to the output of a turning condition detection means A, at the time of driving a vehicle, so as to obtain an aimed characteristic of vehicle behavior, second braking force control is also carried out for controlling the braking force so as to define the amount of slip of the wheel in a fixed region based on the output of a physical amount of slip calculation means C. In the region where the first and the second braking force controls are carried out simultaneously, normally, the smaller command value is selected of both of the braking force controls by a command value selection/changing means D, and when the command value to be selected is the one that reverses the right and left difference in the first braking force control, the command value of the second braking force control is preceded as a control command value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a braking force control device, and particularly to a braking force control device that controls vehicle behavior by generating a difference in braking force between left and right wheels of a vehicle, and The present invention relates to a braking force control device that can perform braking force control that controls the amount of braking force.

(Prior Art) As a device for controlling the braking force of a vehicle, the present applicant has already proposed a braking force control device that attempts to control vehicle behavior by making a difference between the braking forces of the left and right wheels of the vehicle ( (Patent Application No. 1-250645). A braking force control system that generates such a braking force difference is a control (so-called active brake) that actively utilizes the braking force difference (brake fluid pressure difference), for example, to improve the turning performance of the vehicle during turning braking.
is possible. In this example, hydraulic pressure control is performed using a yaw rate feedback method that controls the left and right brake fluid pressures differently to eliminate the deviation between the vehicle's actual yaw rate and the target yaw rate. It can contribute to sex.

(Problem to be Solved by the Invention) However, when controlling by creating a difference between the left and right brake fluid pressures for the purpose of controlling vehicle behavior,
In a vehicle equipped with an anti-skid system (ABS), in a region where braking force control for vehicle behavior control and braking force control by anti-skid slip amount control are executed at the same time, the two controls interfere with each other. ,for example,
If anti-skid control is activated during vehicle behavior control, the brake fluid pressure will be reduced independently for each channel.
Control interference may occur, such as the difference in brake fluid pressure between the left and right brakes being out of order, and the original performance may not be achieved.

An object of the present invention is to prevent interference between the above-mentioned controls and to maximize their performance in braking force control in a braking range where vehicle behavior control and wheel slip amount control are performed simultaneously. To provide a braking force control device which can perform appropriate integrated control by giving priority to braking force control by slip amount control when both of these controls cannot be expected to be compatible.

(Means for Solving the Problems) The braking force control device of the present invention, as conceptually shown in FIG. a turning state detection means for detecting a turning state of the wheel; a slip physical quantity calculation means for calculating a slip physical quantity used in the wheel slip amount control; a first braking force control that controls the braking force so that the vehicle behavior becomes a target characteristic; and a first braking force control that controls the braking force so that the wheel slip is within a predetermined range based on the output of the slip physical calculation means. When the control means has each of the functions of braking force control described in Section 2, and the conditions for the first and second braking force controls are satisfied, the command values for the braking force control in both of these controls are usually compared and are smaller. When the command value of the first braking force control command value is selected as the braking force control command value of the wheel to be controlled, and the command value so selected is a command value that reverses the left and right magnitudes of the first braking force control command value. , a braking force control means including a command value selection and changing means for changing the command value so that the second braking force control command value is prioritized as the braking force control command value.

(Function) The braking force control means generates a difference between the left and right braking forces of the wheels to be controlled in accordance with the output from the turning state detection means that detects the turning state, and adjusts the braking force so that the vehicle behavior becomes the target characteristic. A first braking force control is performed to control the braking force, and a second braking force control is performed to control the braking force so that the slip of the wheel is within a predetermined range based on the output from the slip physical quantity calculating means. When the first braking force control and the second braking force control are executed simultaneously, the command value selection and changing means normally selects the smaller command value of the braking force control in both controls, and the second braking force control is executed simultaneously. If the command value is a command value that reverses the left-right difference of the first braking force control, the command value is set so that the command value of the second braking force control is given priority as the braking force control command value. make changes.

This prevents interference and ensures the effects of both vehicle behavior control and slip amount control in the control execution ranges of both vehicle behavior control and slip amount control. When the command value is such that the left and right magnitudes of the two directions are reversed, it is possible to prioritize slip amount control over vehicle behavior control and shorten the control distance.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows the configuration of an embodiment of the braking force control device of the present invention.

The applicable vehicle is one that can independently control the left and right braking forces of the front and/or rear wheels, and in this example, it is assumed that the left and right braking forces (braking fluid pressure) can be controlled for both the front and rear wheels. . In the figure, IL and IR indicate left and right front wheels, and 2L and 2R indicate left and right rear wheels, respectively. Each wheel has brake discs 3L and 3, respectively.
R, 4L, 4R, and wheel cylinders 5L, SR, 6L, 6R that apply brake force (braking force) to each wheel by frictionally pinching the brake disc by supplying hydraulic pressure (hydraulic pressure), and these brake units. When each wheel cylinder is supplied with hydraulic pressure from a pressure servo unit (pressure control unit) 7, each wheel is braked individually.

The pressure servo unit 7 constitutes a braking force control device together with a controller, which will be described later, and adjusts the hydraulic pressure from the hydraulic pressure generating source 8 based on an input control signal, and controls the hydraulic pressure in the wheel cylinders 5L and 5R of each wheel.

Controls the brake fluid pressure (brake fluid pressure) supplied to 6L and 6R. The pressure servo unit 7 is configured to include actuators for each hydraulic pressure supply system (each channel) for the left and right front and rear wheels. As the actuator, one that is capable of controlling pressure reduction, pressure holding, and pressure increase is used, which is also used for anti-skid control (ABS control).

In the pressure servo unit 7, the actuators for controlling the hydraulic pressure of each supply system output input hydraulic pressure command signals, specifically, the front wheel hydraulic pressure command value P, (CHD), and the right hydraulic pressure command value P.
, (CMD), rear wheel left hydraulic pressure command value h (CHD), rear wheel right hydraulic pressure command value P, (C?'lD), which individually adjusts the braking hydraulic pressure P, -P4. shall be.

The above signals to the pressure servo unit 7 are supplied from a controller (control unit) 9, and this controller 9 includes a steering angle sensor 11 that detects the steering angle δ (steering wheel angle) of the steering wheel (steering wheel) 10. A signal from the pedal force sensor 13 that detects the depression force F of the brake pedal 12, a signal from the yaw rate sensor (yaw angular velocity sensor) 14 that detects the actual yaw rate (yaw angular velocity) φ acting on the vehicle, and a signal from each wheel. Wheel load of -81-2, 3. -4 wheel load sensor 15 that detects
．． 16, signals from a wheel speed sensor 19 that detects the wheel speed VWI+VWZ+V@3rVH4+ of each wheel, and the like are respectively input.

The signal from the steering angle sensor is itself used as a parameter representing the vehicle turning state, or as part of it. The signal from the pedal force sensor is used as information representing deceleration, and the signal from the yaw rate sensor is used as a control parameter in hydraulic pressure control using a yaw rate feedback (yaw rate F/B) method.

Further, the signal from the wheel load sensor is used as a control parameter when controlling the left and right braking forces to generate a target braking force difference while avoiding wheel locking during yaw rate feedback control.

Further, the signals from the wheel speed sensors can be used as information for estimating the vehicle speed when the vehicle speed is used as a control parameter, and are also used for anti-skid control performed by the controller 9.

In anti-skid control, when using the channel, four-sensor method as in this example, a wheel speed detection value, a vehicle body speed detection value, and a slip amount detection value are obtained for each wheel, and the detected wheel speed and detected vehicle body speed are calculated. The braking force is controlled accordingly to keep the slip amount of the relevant wheel below the set value.As a result, the left front wheel, right front wheel, left rear wheel, and right rear wheel are individually anti-skid controlled. Maximum braking efficiency per wheel is achieved to avoid wheel locking.

The controller 9 includes a microcomputer that uses an input detection circuit, an arithmetic processing circuit, a memory circuit, an output circuit, etc., and controls vehicle behavior by creating a difference in braking force on the left and right sides of the vehicle depending on the turning state. When controlling the braking force so that the vehicle behavior when turning has the target characteristics, basically, based on predetermined input information, the arithmetic processing circuit calculates the target reduction according to the control program described later. The speed, target yaw rate, yaw rate difference value, etc. are calculated, and each calculated value is used to calculate the target wheel cylinder fluid pressure value (command value) as the braking force (brake force) control value for each wheel. A corresponding signal is output to the pressure servo unit 7. As a result, pressure servo unit 7
Then, the hydraulic pressure from the hydraulic pressure source 8 is adjusted so that the actual wheel cylinder hydraulic pressure for each wheel matches the target hydraulic pressure, and the hydraulic pressure is applied to each wheel cylinder 5L as the braking hydraulic pressure.

It is supplied to 5R, 6L, and 6R.

When the controller 9 performs slip amount control using skinned cycles, the controller 9 calculates the vehicle speed, wheel acceleration, slip amount, etc. in its calculation processing circuit, and based on this calculates the braking force control value for each wheel. Calculate the target wheel cylinder fluid pressure value (command value). Even when such control is performed independently, a signal corresponding to the target wheel cylinder fluid pressure value due to anti-skid control is output to the pressure servo unit 7 via the output circuit, as in the case where the vehicle behavior control described above is performed independently. The unit adjusts the hydraulic pressure from the hydraulic pressure generating source 8 and supplies it to each wheel cylinder so that the actual wheel cylinder hydraulic pressure for each wheel matches the target hydraulic pressure.

Furthermore, when a control condition is established in which both anti-skid controls are performed simultaneously, such as when anti-skid control is activated during the vehicle behavior control, the controller 9 is designed to exert its original performance as much as possible. It also performs integrated control aimed at

In other words, when vehicle behavior control causes a difference in the braking force control command values for the left and right wheels, the command value is compared with the anti-skid control command value, and the smaller of the two control command values is usually selected. If the selected command value is a command value that reverses the difference between the left and right command values for vehicle behavior control, the output of the command value for vehicle behavior control is prohibited, and the anti-skid control is It also executes processing to give priority to the command value. Therefore, the controller 9 also constitutes a means for setting the final braking force control command value P, (CMD) (j=1 to 4) in cases corresponding to both control execution regions.

FIG. 3 is a flowchart showing an example of a braking force control program including selection and switching processing of braking force control command values in the vehicle behavior control and anti-skid control execution regions described above, which is executed by the controller 9. This program is executed at regular intervals.

First, in step 101, based on the signals from each sensor, the steering angle δ, the brake pedal force Fp, the actual yaw rate ψ
, wheel speed V of each wheel. j (j・1~4), wheel load of each wheel -
Read each of J (j・1 to 4).

In the following step 102, the speed of the vehicle body is estimated, and the wheel acceleration vwJ (j·1 to 4) of each wheel is determined. In other words, the vehicle speed is calculated using Vwj, but for example, in the case of a PR vehicle, the wheel speed VW of the front two wheels, which are the non-driving wheels, is
Using I+Vw2, ν=<Vwl+V, ri/
2, find the V value, and use this as the vehicle speed value. Furthermore, the wheel acceleration vwJ is determined using the differential coefficient of vwj.

The vehicle speed value and wheel acceleration value calculated above are calculated by the following target yaw rate calculation processing (step 104) in vehicle behavior control using yaw rate feedback (yaw rate F/B) control, and anti-skid (ABS) control described below. The latter is also applied to the slip amount calculation process (step 107), etc., and the latter is also applied to the process of calculating the deviation of the wheel acceleration of each wheel from the target value in the anti-skid control (step 10B).
), etc.

Next, in step 103, the brake depression force F2 value is used to calculate the target deceleration Grsf according to the following equation.

G,, -t = K+ 'X Fp''
(1) In the above, 1 is a proportionality constant, and here, the target deceleration of the vehicle is treated as being proportional to the brake pedal force.

Next, for yaw rate feedback control during control,
Here, in step 104, a target yaw rate (target yaw angular velocity) ψ□ is calculated from the vehicle speed V value and steering angle δ. In this embodiment, the target yaw rate is calculated according to the following equation.

Here, φref in equation (2) is obtained in relation to the target turning radius Rr0 given an arbitrary steering angle and vehicle speed, and Rraf is obtained according to the following equation (3).

First = Ax(1+KtxV”)/δ
-(3) Here, A is a constant determined by the wheel base and steering gear ratio of the vehicle, and K is a constant representing the steering characteristics of the vehicle.

In general, the steering characteristic that is considered to be good for driving is called the so-called weak understeer characteristic, and this is based on (3)
2 in the formula, K2〉0 and z O1, that is, the steering angle δ
This can be expressed as a steering characteristic in which the turning radius does not increase much even if the vehicle speed V is increased while V remains fixed. Therefore, in order to obtain this preferable steering characteristic, any δ
,■ is given, and this Rref
With the relationship (φr*f = v/R,,t), ψr, f
+fi will be found.

Next, in step 105, a yaw rate difference value Δφ, which is the difference between the target yaw rate ψrmf obtained in step 104 and the actual yaw rate ψ (detected actual yaw rate), is calculated according to the following equation.

Δφ=φrat−ψ (4) As described above, target deceleration Grit and target yaw rate←. 7. Once the yaw rate difference value Δφ has been calculated, in step 106, the target wheel cylinder pressure p, (s) (j=i
~4) is calculated.

The relationship between the actual wheel cylinder hydraulic pressure Pj (j=1 to 4) and the braking force F, (j=1 to 4) can be expressed by the following equation (5) assuming that the wheel slip is sufficiently small.

2xa, xμp, ×rpJ F, = PJX□ ... (5) rma However, in the above, aj etc. (j=1 to 4) represent the following.

aJ: Wheel cylinder area μp, : Friction coefficient between pad and disc rotor rl)j
Distance rJ from the center of the nib floater to the band: tire rotation radius Therefore, the following equation (6) holds true between the target deceleration Grtaf and the target wheel cylinder pressure Pja (s).

However, W, aj (j = 1 to 4) represent the following.

-Two-vehicle type quantity αi; (2Xα1×μpJXrl)J/rj) For simplicity, the target wheel cylinder hydraulic pressures of the front and rear wheels on the same left and right sides are equal (i.e., PIA (S) = P: 1A (S)
, PzA(S) = PaA(S) ) and also α.

= α2 α, (f: front), α3 = α4 = αzu (r
: rear), the above equation (6) can be expressed as the following equation (7).

Gr*f = X (α, +α−)
(S) + hA (S) ) ... (7) Here, the actual yaw rate φ of the vehicle and the target yaw rate 9' rsf are determined such that the yaw rate difference value Δψ obtained by the above equation (4) is zero, that is, the actual yaw rate φ of the vehicle and the target yaw rate 9' rsf The target wheel cylinder fluid pressure difference (braking force difference between the left and right wheels) in order to generate yawing torque in the vehicle by the left and right braking fluid pressure difference that eliminates the deviation from the If you set it as 3,
It is given by the following equation (8).

PIa(S) Pza(S) = 3・Aφ
...(8) And from the above (7), (8) 2, P
+ a (S) ~ P4^ (S) is ... (9-1) P2A (S) = (GrarX - α, ÷ αr) - K
3XΔψ)...(9-2) PaA(S)=PIA(S)
...(9-3) PJA(S) = PEA(S)
...(9-4) is obtained.

The PJA(S) value obtained from equations (9-1) to (9-4) in step 106 above is the hydraulic pressure command value determined by vehicle behavior control (here, yaw rate feedback control) as mentioned earlier. So here, (9-1)
Focusing on equation (9-2), when this control is executed independently, the left and right wheels of the front wheels are shifted using the -Gr*rXW/(α, ÷αr) value as the reference hydraulic pressure value. (Fig. 5 (a) to (C), and t0 in Fig. 6)
- t8) and for the left and right rear wheels (9-3).

As shown in formula (9-4) (similar to the above).

Next, in this embodiment, in steps 107 to 110 following step 106, the target wheel cylinder hydraulic pressure value 7 m (S) (j -Perform the calculation processes 1 to 4).

First, in step 107, the slip amount S of each wheel is determined.

For (j, 1 to 4), the vehicle speed v value and vehicle speed V. , is calculated using the following equation.

S7=V-'Jwj'', Qω Furthermore, in step 108, the difference Δ, (j=1 to 4) in the wheel acceleration of each wheel is calculated according to the following equation.

ΔV, = V, , -, j-00 Here, the above V rat is the target wheel acceleration, and may be a preset constant value (for example, -1, 3G), or the aforementioned target reduction. It may also be a function of speed Gr*f.

In the next step 109, the amount of pressure reduction ΔPJ (j-1 to 4) of the wheel cylinder fluid pressure of each wheel is determined from the difference Δ■ between the slip amount SJ and the wheel acceleration calculated as described above.
is calculated and determined according to the following formula.

AP, , X4XS, +, XΔ, ...α
Here, K4+Ks is a constant representing the weight for the slip amount Sj+the wheel acceleration difference ΔV, respectively.

After executing steps 107 to 109, the target wheel cylinder hydraulic pressure p5m(S) for each wheel in the case of anti-skid control is calculated in step 110.

This is done as follows.

That is, considering the target wheel cylinder hydraulic pressure for each wheel when the above-mentioned yaw rate feedback control is not performed,
From equations (9-1) to (9-4) above, the target wheel cylinder hydraulic pressure Pjll(S) is: P+g(S) □ XGr-rXW/(α,
10α, )−ΔP, −(13−1)P! I(S)
□ XGrmtx-ba cr t+ cx r)-Δ
p, ・(13-2)P, m(S) -XGr*rX
W/(αy+αr)−Δp, −(13-3)P4.
(S) = XGr*rXW α, +α, )−AP
, −(13-4).

In this way, the pjg(s) value is determined by the above calculation, but these are hydraulic pressure command values determined by anti-skid control, and when anti-skid control is executed independently, the wheel cylinder hydraulic pressure of each wheel is controlled depending on the target value.

After step 110, in the following step 111 of this program example, a check is made as to whether or not the timing is such that both braking force control by vehicle behavior control and braking force control by anti-skid control are performed simultaneously. If Yes, the process proceeds to step 113 and subsequent steps described below, but if No, the hydraulic pressure command value pJ(
CMD) Set (j・1 to 4) to the corresponding control target value. For example, if yaw rate feedback control is used alone, the calculated target wheel cylinder hydraulic pressure value pja (s) in (9-1) to (9-4) above is changed to the final command value Pj (C
HD), execute steps 115 to 117 to be described later, and end this program.

The braking force control between times t0 and t0 in FIG. 6 shows, for example, the wheel cylinder hydraulic pressures of the left and right front wheels in such a case, and only yaw rate feedback control is executed during this period.

Also, in the case of anti-skid control alone, P
j (CHD) value setting processing is performed.

On the other hand, when proceeding from step 111 to step 113 and subsequent steps, for example, when the anti-skid control is activated during yaw rate feedback control, such as after time t2 in FIG. 6 (time t, ~ts ), in steps 113 and subsequent steps, the effect of both side opening is usually achieved by selecting the smaller of the vehicle behavior control and anti-skid control command values for each wheel, that is, the target wheel cylinder hydraulic pressure value mentioned above. If each command value secured and selected is a command value that reverses the difference between left and right command values for vehicle behavior control, processing for giving priority to anti-skid control over vehicle behavior control. Execute.

First, in step 113, the target wheel cylinder hydraulic pressure P ja of each wheel is determined by yaw rate feedback control.
(S) value and the target wheel cylinder hydraulic pressure Pjm(S) for each wheel by anti-skid control, the smaller value is output as the target wheel cylinder hydraulic pressure value, that is, the hydraulic pressure command value P, (CHD). select.

Normally, the smaller of the target wheel cylinder hydraulic pressure PjA(S) by yaw rate feedback control and the target wheel cylinder hydraulic pressure PjmC5) by antiskid control is selected, thereby ensuring the control effects of both.

An example of this is shown in FIGS. 5(a) and 5(b).

Figures 5 (a), (b), and (C) are examples of target wheel cylinder hydraulic pressure selection for the left and right front wheels, including the case where priority is given to anti-skid control, which will be described later. Xc is the differential pressure between the left and right sides when using yaw rate feedback control, arrows Y and ~Yc are the differential pressures ultimately generated between the left and right sides according to the final selected command value, and the shaded area is the anti-skid area. Indicates that it is due to control.

Figures (a) and 2) are normal selection cases; in the case of Figure (a), the left wheel side is set to the target wheel cylinder hydraulic pressure value Pill (S) in yaw rate feedback control.
) Since the target wheel cylinder hydraulic pressure value P+m (S) due to anti-skid control is smaller than the command ([P+ (CMD), the above P1
The ml(S) value is selected, and similarly for the right wheel side, a small value hm(S) 4! is the command value P, (CH
D) will be selected. As a result, the final generated differential pressure is generated between the left and right sides in an amount and direction as shown by the arrow Ya, and it is possible to prevent interference in both control execution areas and to maximize the original performance of each control.

In addition, in the case of the same figure (b), the selection is made according to the above, and the Pus (S) value is set for the left wheel side, and the Pza (S) value is set for the right wheel side.
As a result of selecting small values, anti-skid control is also possible, and the final generated differential pressure is the same as the differential pressure (arrow xb) due to yaw rate feedback control, as shown by arrow yb. Since it is generated with directionality, it is also possible to generate a differential pressure between the left and right wheels to exert the effect of controlling vehicle behavior. In the example of FIG. 6, such a normal selection pattern corresponds to the braking force control between times t and t4, and normally both control effects are secured in this way.

Therefore, if each command value force selected in step 113 is a command value that reverses the difference between the left and right command values of yaw rate feedback control, anti-skid control is given priority over yaw rate feedback control. Therefore, in step 114, command value switching control is executed.

FIG. 4 shows an example of a subroutine for the selection switching control, and here the case is shown in which the left and right front wheels are targeted. In step 201, first, target left and right wheel cylinder hydraulic pressure values Pea (S) and P are determined by yaw rate feedback control.
za (S), and if the answer is Yes, it is determined in the next step 202 whether the target wheel cylinder hydraulic pressure value P+i (S) by anti-skid control is greater than or equal to the above P□(S) value. , if the answer is Yes, this program is terminated. In this case, the PJ (CHD) value selected in step 113 of FIG. 3 is used as the final braking force control command value, and the normal selection pattern described above is maintained.

On the other hand, if the answer to step 202 in FIG. (s) (however, j.1.2) and terminates this program (in other words, the application of the target value of yaw rate feedback control is prohibited).

Furthermore, if the answer to step 201 is No, it is determined in step 204 whether the ha (S) value is greater than or equal to the Pus (S) value, and if the answer is Yes, the program is terminated. On the other hand, if the answer is NO, the process of switching the command value to that based on anti-skid control is executed in the same manner at step 205, and the program ends.

The reason why the command value for anti-skid control is preferentially applied under certain conditions as described above is from the following viewpoint. In other words, in order to prevent interference in both control execution areas, the smaller of the target wheel cylinder hydraulic pressure values for yaw rate feedback control and anti-skid control is normally used as the command value. However, if control is performed in the opposite direction to the control aimed at by yaw rate feedback control, the vehicle behavior control by yaw rate feedback control will not be effective, so the smaller value is usually used as the command value depending on the selection pattern. There is no point in selecting it, and therefore, under such conditions, it may be possible to shorten the indicated braking distance by applying anti-skid control itself.

Therefore, it was decided to give priority to anti-skid control.

More specifically, PIA (
S) value, PzA(S) value, Ppm (S) value and Ptm
(S) In the case of the value relationship, if the command value is determined according to the normal selection pattern, the differential pressure will be reversed with respect to the arrow xc, as shown by the arrow Z.
Unlike the cases shown in FIGS. 2A and 2B, yaw rate feedback control has no effect. Therefore,
In such a case, select the smaller value and use it as the command value (Option B), and in the case of Figure 5 (C), anti-skid control is applied to the right wheel as well. Priority is given to anti-skid control by selecting the target wheel cylinder hydraulic pressure value hl (s) according to the following. The period from time t4 to time t5 shown in FIG. 6 is an example of such a case, where priority is given to anti-skid control. In other words, even though yaw rate feedback control is used to generate a pressure difference between the left and right wheels to control vehicle behavior, the command value that is ultimately selected is a command value that will generate a pressure difference that is opposite to the pressure difference. In that case, the yaw rate feedback control will have no effect, so in that case, anti-skid control alone is used in order to generate as much braking force as possible.

This improves steering stability during braking (active braking)
It is also possible to prevent braking force from being lost in the anti-skid control area near wheel lock.

In step 113 of FIG. 3, the process for switching the command value selection as described above is executed, and step 115.
If the result is found in step 116, processing is executed to set the p(C'MD) value to 0. That is, it may happen that the set final command value P, (CMD) becomes a negative value, but in that case, the Pj (CMD) value, that is, the target wheel cylinder hydraulic pressure, can be set to O, and the following In step 117, brake fluid pressure control processing is executed, and the program ends.

The content of this process is to individually determine control signals corresponding to the hydraulic pressure command values P and (CMD) for each wheel, and to control the pressure servo unit 7.
By supplying these signals to the pressure servo unit 7, the actual wheel cylinder hydraulic pressure Pj (hydraulic) is adjusted according to the above P, (CHD), and the wheel cylinders 5L, 5R, It will be given to 6L and 6R.

By controlling as described above, even if anti-skid control is activated during yaw rate feedback control, interference between the controls is prevented, and when yaw rate feedback control is ineffective, anti-skid control is given priority. This allows appropriate integrated control to be performed.

In the above embodiment, yaw rate feedback is used to control vehicle behavior by generating a braking force difference, and in this case, a so-called proportional control method is used as a feedback control method for the yaw rate difference value Δψ. The present invention is not limited to this, and a control method may include either or both of differential operation and integral operation. When doing so, it is possible to improve the actual yaw rate response and stability of the vehicle relative to the target yaw rate.

It can also be implemented with a control comb that does not use yaw rate feedback.

Furthermore, in this embodiment, as the anti-skid control method, the feedback control method of S, (・Δ■J) and ΔvJ is used as described above, but S, only or Δ! , or may be a control method that also includes integral operation.

(Effects of the Invention) According to the braking force control device of the present invention, when the braking force control of vehicle behavior control and slip amount control conflict, the smaller command value of vehicle behavior control and slip amount control is usually selected. It is possible to ensure the effects of both controls, and when the selected command value is a command value that reverses the left and right magnitudes of vehicle behavior control, priority can be given to slip amount control. Even if slip amount control is activated during behavior control, it is possible to prevent control interference and perform appropriate braking force control.In addition, under the above conditions, slip amount control has priority because it increases braking force. As a result, the braking distance can be shortened.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the braking force control device of the present invention, Fig. 2 is a system diagram showing an embodiment of the braking force control device of the present invention, and Fig. 3 is a flowchart showing an example of a control program of the controller on the same side. , FIG. 4 is a program flowchart showing an example of a subroutine for command value selection switching control of the control program, and FIG. 5 is a diagram showing an example of target wheel cylinder hydraulic pressure selection to provide an explanation of control contents in the control program. FIG. 6 is a diagram similarly showing an example of time series data of braking force control. IL, 01... Left and right front wheels 2L, 2R... Left and right rear wheels 3L, 3R, 4L, 4R... Brake disc 5
L, SR, 6L, 6R...Wheel cylinder 7.
... Pressure servo unit 8 ... Hydraulic pressure generation source 9 ... Controller 10 ... Steering wheel 11 ... Steering angle sensor 12 ... Brake pedal 13 ... Pedal force sensor 14 ... Yaw rate sensor 15 ~ 18...Wheel speed sensor

Claims (1)

[Claims] 1. A vehicle capable of independently controlling left and right braking forces of the front wheels and/or rear wheels, comprising: a turning state detection means for detecting the turning state of the vehicle; and a slip physical quantity used in wheel slip amount control. A first means for controlling the braking force so that the vehicle behavior becomes a target characteristic by creating a difference between the left and right braking forces of the wheels to be controlled according to the output from the slip physical quantity calculating means and the turning state detecting means. A control means having the functions of braking force control and a second braking force control for controlling the braking force so that the wheel slip is within a predetermined range based on the output of the slip physical calculation means, When the conditions for braking force control are satisfied, normally the command values for braking force control in both controls are compared and the smaller command value is selected as the braking force control command value for the wheel to be controlled. When the command value is a command value that reverses the left and right magnitude of the command value for the first braking force control, the command value for the second braking force control is given priority as the braking force control command value. A braking force control device comprising a braking force control means including a command value selection and changing means for changing the command value.