JPH0624304A - Brake force control device - Google Patents

Abstract

PURPOSE:To combine right/left distribution and front/back distribution by yaw rate F/B brake force control to be used effectively at a good efficiency, achiev ing the optimum control allocation in accordance with a vehicle condition such as a lateral G at the time of control. CONSTITUTION:In a control device, both control of right/left distribution, and front/back distribution are performed by a yaw rate F/B (S110-130). Where a lateral G (Yg) is a parameter, a control allocation ratio between right/left distribution control and front/back distribution control is set in accordance with the detected lateral G, and allocation ratio characteristics can be set in such a way that the right/left distribution control is the main one in a range of a small lateral G, and that control allocation for the front/back distribution is increased as the lateral G becomes larger. In a range of a low lateral G, control allocation of the right/left distribution having effects in the range (that of the front/back distribution, having smaller effects, is decreased) to utilize control effect of both controls effectively, and the control allocation for the front/back distribution having a larger effect is increased in a high lateral G range such as in high-speed cornering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking force control device, and more particularly to a control device which realizes an effective combination of left and right distribution of braking force and front and rear distribution.

[0002]

2. Description of the Related Art As a vehicle braking force control device, there is a braking force (braking force) left / right distribution control device (active brake) by yaw rate feedback (F / B) (Japanese Patent Laid-Open No. 3-112756). Also, for example, a braking force front / rear distribution control by mechanical (mechanical) or electric control, which makes it possible to control the front / rear braking force distribution by changing the wheel load, is known as a split point change control or the like (Japanese Patent Laid-open No. Sho 60) -248466 publication).

[0003]

In the yaw rate F / B type left / right distribution control of the braking force control, the yaw rate is fed back and the left and right braking forces are differentiated according to the yaw rate deviation, whereby the vehicle behavior can be controlled. However, since the yaw moment can also be controlled in the front-rear distribution control, a combination of these as the braking force control system, and a combination of both by the yaw rate F / B system can be considered. However, efficient control cannot be expected if it is a simple combination.

As will be referred to later in FIG. 6, this is the yaw rate depending on the lateral distribution (a) and the longitudinal distribution (b) of the braking force considered in the area division of the vehicle lateral acceleration and longitudinal acceleration. The control effect is shown (the broken line in the figure represents the characteristic in the middle part of the yaw rate control effect characteristic surface of (b) including the solid line in the case of front and rear distribution). The region has a certain effect, and the front-rear distribution has a large effect in the region where the lateral acceleration and the front-rear acceleration are large, and the characteristics of the effect of the respective distribution control are different. Therefore, even if the left and right distribution and the front and rear distribution are simply combined to control the braking force, the magnitude of the obtained effect may change depending on the vehicle state during braking such as lateral acceleration. Without this, efficient and effective braking force control (vehicle behavior control) cannot be expected. In particular,
When both controls are to be realized by F / B control by feeding back yaw rate capable of compensating for disturbance inputs and the like, not only the waste of energy is consumed but also the system design is not appropriate. The combination may cause a decrease in controllability. In this respect as well, it is important to efficiently and optimally combine the two, but conventionally, control from such a viewpoint has not been found.

According to the present invention, from the standpoint of how to optimally combine the left and right distribution control and the front and rear distribution control of the braking force control, the respective controls are selectively used in the effective areas of both controls, and the overall control is efficient and appropriate. It is intended to provide a braking force control device capable of controlling the braking force.

[0006]

According to the present invention, the following braking force control device is provided. That is, in a vehicle in which the braking force of each wheel can be controlled as in claim 1, a traveling state detecting means for detecting a traveling state of the vehicle including a steering state of a steering wheel, and a yaw rate generated in the vehicle are detected. A yaw rate detecting means, a target yaw rate setting means for setting a target yaw rate based on the output of the running state detecting means, a deviation calculating means for calculating a deviation between the target yaw rate and the generated yaw rate, and a lateral acceleration generated in the vehicle and / or Lateral acceleration for detecting longitudinal acceleration and /
Alternatively, the longitudinal acceleration detecting means, the control sharing rate setting means for setting the control sharing rate of both the lateral distribution and the longitudinal distribution of the braking force according to the output of the lateral acceleration and / or the longitudinal acceleration detecting means, and the wheel braking force. Target left / right distribution calculating means and target front / rear distribution calculation for calculating the left / right distribution of the target in the left / right distribution control and the front / rear distribution of the target in the front / rear distribution control based on the yaw rate deviation and the control share ratio. And a wheel braking force control means for controlling the braking force of the wheels to be controlled in the corresponding control so that the target left / right distribution and the target front / rear distribution thus calculated can be obtained. 1). Further, according to a second aspect of the present invention, the braking force control device according to the first aspect is configured to increase the control share of the front-rear distribution control as the lateral acceleration increases.

[0007]

In the braking force control device according to the first aspect of the present invention, the yaw rate deviation is calculated by the system of the running state detecting means, the target yaw rate setting means, and the yaw rate detecting means, and this is the wheel braking force for which the left / right distribution control and the front / rear distribution control are possible. Although it is applied to the control means, the control sharing rate setting means sets the control sharing rate of both the lateral distribution and the longitudinal distribution of the braking force applied by the control sharing rate setting means in accordance with the output of the lateral acceleration and / or the longitudinal acceleration detecting means. The power control means calculates the right / left distribution of the target in the left / right distribution control and the front / rear distribution of the target in the front / rear distribution control based on the yaw rate deviation and the control share ratio thus set, and obtains the target left / right distribution and the target front / rear distribution. As described above, the braking force of the control target wheel in the corresponding distribution control is controlled. Therefore, in both cases, the braking force control is executed by the left / right distribution control and the front / rear distribution control by feeding back the yaw rate, and the control share of the left / right distribution control and the front / rear distribution control is the lateral acceleration generated by the vehicle during the control. And / or modified accordingly to the longitudinal acceleration, both controls allow it to operate in a more effective area and the efficiency of each control to be effective in each effective area of the distribution control. If possible to use properly. According to the second aspect of the present invention, when the lateral acceleration is large, the control share ratio of the front-rear distribution control having a large control effect is increased. Therefore, it is more effective in a region where the lateral acceleration is large such as cornering at a high vehicle speed.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows the configuration of an embodiment of the braking force control device of the present invention. The vehicle to be applied can independently control the braking force of each wheel, and in this embodiment, the left and right braking forces (braking hydraulic pressure) of both the front and rear wheels can be controlled. 1 in the figure
L and 1R indicate left and right front wheels, and 2L and 2R indicate left and right rear wheels, respectively. Each wheel has a brake disc 3L, 3R, 4 respectively.
L, 4R, and wheel cylinders 5L, 5R, 6L, 6R for frictionally sandwiching the brake disc by supplying hydraulic pressure (hydraulic pressure) to give a braking force (braking force) to each wheel,
When hydraulic pressure is supplied from the pressure servo unit (pressure control unit) 7 to each wheel cylinder of these brake units, each wheel is individually braked.

The pressure servo unit 7 constitutes a braking force control device together with a controller, which will be described later, including this. The pressure servo unit 7 adjusts the hydraulic pressure from the hydraulic pressure generation source 8 by an input control signal, and the wheel cylinders 5L, 5R of each wheel. , 6L, 6R to control the brake fluid pressure (brake fluid pressure). The pressure servo unit 7 is configured to include an actuator for each hydraulic pressure supply system (each channel) on the front and rear wheels. As the actuator, for example, an actuator that can be used for anti-skid control (ABS control) and can control pressure reduction, pressure holding, and pressure increase can be used. In the pressure servo unit 7, the input hydraulic pressure command signal, specifically the front wheel left hydraulic pressure command value P _1A (S), the same right hydraulic pressure command value P _2A (S), is provided with actuators for controlling the hydraulic pressure of each supply system. The braking hydraulic pressures P ₁ to P ₄ are individually adjusted according to the signals of the rear wheel left hydraulic pressure command value P _3A (S) and the right hydraulic pressure command value P _4A (S).

The above signals to the pressure servo unit 7 are
From the controller (control unit) 9
The controller 9 supplies the steering wheel
The steering angle δ (steering wheel angle) of the steering wheel (steering wheel) 10
Signal from steering angle sensor 11, stepping force of brake pedal 12
 F_PFrom the pedal force sensor 13 that detects
Yaw rate detection means for detecting the actual yaw rate (d / dt) φ
Signal from the yaw rate sensor 14 as
Wheel speed (rotation speed) V_w1, V_w2, V_w3, V_w4Detect
The signals from the wheel speed sensors 15, 16, 17, 18 that act on the vehicle
Lateral acceleration Y _gAs a lateral acceleration detection means for detecting
Input signals from the lateral acceleration (lateral G) sensor 19 respectively.
It The signal from the steering angle sensor itself is the vehicle running condition.
Used as a parameter or as part of
Be done. Also, the signal from the yaw rate sensor is
Control by hydraulic pressure difference control by feedback (F / B) method
It is used as a parameter. Furthermore, from the wheel speed sensor
The signal of when the vehicle speed is used as a control parameter
It can be used as information for vehicle speed estimation.
In addition, anti-skid control is performed by the controller 9.
Wheel speed V_wj(J = 1 to 4) is its derivative
(D / dt) V_wjFor anti-skid control in search of
Can be It should be noted that in the present embodiment, detection of the running state of the vehicle
Is based on steering angle and vehicle speed, and
The state detecting means includes the steering angle sensor 11 and the controller 9.
A part (vehicle speed estimation calculation processing part described later) corresponds to this.

The controller 9 corresponding to the wheel braking force control means includes a microcomputer and the like, and when the vehicle behavior is controlled by the yawing moment during braking, the yaw rate F is set so that the vehicle behavior becomes the target characteristic. When the braking force is controlled by the / B method, basically, a target yaw rate, a yaw rate difference value, etc. are calculated in the arithmetic processing circuit according to a control program described later, and each calculated value is used for each wheel. A target wheel cylinder hydraulic pressure value (command value) as a braking force (braking force) control value is calculated, and a signal corresponding thereto is output to the pressure servo unit 7. As a result, the pressure servo unit 7 is used to adjust the hydraulic pressure from the hydraulic pressure generation source 8 so that the actual wheel cylinder hydraulic pressure for each wheel matches the above-mentioned target hydraulic pressure. 5L,
Supply to 5R, 5L, 6R. In this example,
The target yaw rate setting means and the deviation calculating means for calculating the deviation of the yaw rate each correspond to a part of the controller 9.

In this case, the controller 9 further controls the yawing moment by controlling the yaw rate F / B by a combination of the front-rear distribution and the left-right distribution of the braking force.
The braking force control may be performed, and the distribution control may be performed in combination with an appropriate share ratio according to the state of the vehicle. In the present embodiment, the control distribution ratio between the left-right distribution control and the distribution control is changed according to the lateral acceleration so that both controls are operated in a more efficient area. For this reason,
In order to properly use each control, the arithmetic processing circuit of the controller 9 also calculates the control share ratio, and when calculating the target wheel cylinder hydraulic pressure value, the left and right distribution control values of the braking force according to the control share ratio ( A target left / right differential pressure) and a front / rear distribution control value (target front / back differential pressure) are calculated, and a target value of the wheel cylinder hydraulic pressure is set. Therefore, in the present embodiment, a part of the controller 9 also corresponds to each of the control share ratio setting means for setting such a control share ratio, and the target left / right distribution calculating means and the target front / rear distribution calculating means. Controller 9
In this case, the storage circuit stores the characteristic data having the lateral acceleration for the above-mentioned control sharing as a parameter.

FIG. 3 shows an example of a control program executed by the controller 9 for vehicle behavior control based on a braking hydraulic pressure difference, which includes a control of changing the distribution ratio of the braking force to the left and right according to the lateral acceleration and the distribution of longitudinal distribution. This processing is executed by a regular interrupt at regular time intervals by an operating system (not shown). In the figure, first in step S110,
Based on the outputs of the steering angle sensor, the pedal force sensor, the wheel speed sensor, the yaw rate sensor, and the lateral acceleration sensor, the steering angle δ, the wheel speeds V _w1 to V _{w4 of} the wheels 1L, 1R, 2L, 2R, the brake pedal force F _P , Yaw rate (d / dt) φ and lateral acceleration Y _g are read respectively. In the following step S111, the wheel speed V
The speed of the vehicle body is estimated based on _wj (j = 1 to 4). In this embodiment, the wheel speeds (wheel rotation speeds) of the two non-driving wheels are used. For example, in the case of an FR vehicle, the wheel speeds _Vw1 and _{Vw of} the two front wheels are used.
_{From w2} , V = (V _w1 + V _w2 ) / 2 From vehicle speed (vehicle speed)
Is calculated and used as a vehicle speed value V.

In the next step S112, the brake pedal force F
_The brake pressure reference value P ₀ is calculated from P. In this embodiment, the reference value P ₀ is calculated by P ₀ = k · F _P. here,
k is a proportional constant determined by vehicle specifications. Further, the reference value P ₀ is not simply proportional to the brake pedal force F _P , but F
_It may be a function of the _P value. That is, it may be obtained as P ₀ = f (F _P ). In this embodiment, the brake is a complete brake-by-wire, but of course, in consideration of fail-safe and the like, the brake pedal 3 and the brake caliper are directly connected to each other at the time of a failure so as to have a hard structure. May be.

Next, for the purpose of controlling the yaw rate feedback braking force during braking, here, in step S113, the target yaw rate (d / dt) φ is calculated from the vehicle speed V and the steering angle δ.
_{Compute ref} . In this embodiment, the target yaw rate is calculated according to the following equation.

## EQU1 ## (d / dt) φ _ref = δ × V (1 + KV ² )-(1) where A is a constant determined by the vehicle wheel base and steering gear ratio, and K is the steering of the vehicle. It is a constant that represents the characteristic. In the next step S114, the yaw rate difference value Δ (d / dt) φ which is the difference between the target yaw rate (d / dt) φ _ref obtained in step S113 and the actual yaw rate (d / dt) φ (actual yaw rate). Is

[Equation 2] Δ (d / dt) φ = (d / dt) φ _ref − (d / dt) φ --- (2)

Next, in step S115, the lateral acceleration
According to Y _g , the control share rate α of both the left and right distribution control and the front and rear distribution control of the braking force is set. here,
In this example, the value α is set within the range of 0 ≦ α ≦ 1, and as shown in Expression 3 (target left / right differential pressure calculation expression in step S116) and the like, in this program example, Specifically, it functions as a distribution ratio to the left / right distribution control (thus, in this case, the distribution ratio to the other front / rear distribution control is 1-α), and in this embodiment, control of both controls is performed. In order to effectively utilize the effect, for example, the control share rate α value is set to have a characteristic as shown in FIG.

In the figure, which shows an example of the change characteristics of the control share rate α with the lateral acceleration Y _g , the control share rate is the lateral acceleration.
In the region where Y _g is small, left and right distribution control is the main (so that the ratio of front and rear distribution control is small) so that α takes a large value and front and rear distribution control is performed as lateral acceleration Y _g increases. It is set to have a characteristic as shown in the figure according to the lateral acceleration Y _g so that α takes a small value so that it is centered (so that the distribution to the left and right distribution control side is reduced). .

Next, in step S116, the target differential pressures generated on the left and right wheels are calculated. In this embodiment, step S
From the yaw rate difference value Δ (d / dt) φ obtained in step 114 and the share rate α value obtained by searching according to the lateral acceleration Y _g at that time point based on the above characteristics, the wheel cylinders on the left and right of the wheel to be controlled are obtained. The target right-and-left differential pressure ΔP _RL to be generated is calculated according to the following equation.

## EQU3 ## ΔP _RL = H × Δ (d / dt) φ × α --- (3) where H is a constant (F / B gain in yaw rate control) determined by vehicle specifications. In the case of the above three equations, a so-called proportional control method is used as a feedback control method for the yaw rate difference value Δ (d / dt) φ, but the feedback control method is not limited to this, and either a differential operation or an integral operation is performed. A control method in which one or both are added may be used. With this configuration, when the left / right distribution control is mainly performed, the actual yaw rate response and stability of the vehicle with respect to the target yaw rate can be further improved.

Further, in step S117, step S
Similar to 116, the target front-to-back differential pressure ΔP _FR is calculated here. In the front-rear distribution control, the absolute value of the yaw moment and the directionality in the stable direction or the unstable direction can be controlled, so the yaw rate difference value Δ (d / dt) φ is not used as it is, The value Δ (d / dt) φ _FR obtained by
That is,

[Equation 4] Δ (d / dt) φ _FR = | (d / dt) φ _ref − (d / dt) φ | --- (4) is used to determine the control amount, and its direction is, for example, the generated yaw rate. And the yaw rate deviation are multiplied to determine the sign. That is,

(5) k_FR= {(D / dt) φ × ((d / dt) φ_ref− (D / dt) φ)} / {| (d / dt) φ | × | (d / dt) φ_ref− (D / dt) φ |} --- (5) Coefficient for code determination k_FRTo determine. Therefore,
Physically, ΔP_FRValue calculation is the Δ (d / dt) φ_FRValue and above
Α value and k _FRWith values and

[Equation 6] ΔP _FR = G × Δ (d / dt) φ _FR × (1−α) × k _FR --- (6) Here, G is a constant (F / B gain in yaw rate control) determined by vehicle specifications.

The control direction may be determined by the direction of change of the sideslip angle of the vehicle, the sign of a value obtained by multiplying the target yaw rate by the yaw rate deviation, or the like. In addition,
Regarding the front-rear distribution control of the braking force, when the processing in step S117 of this program example is performed, a method of applying a front-rear differential pressure ΔP _FR to change the front-rear distribution is used. Wheel brake hydraulic split
By changing the points, the front-rear distribution may be changed according to the share rate α. For example, if the target split point P _s is

[ _Equation 7] P _s = P _s0 −k ₁ × (d / dt) φ _FR × (1-α) × k _FR --- (7) (where P _s0 is the reference split point and k ₁ is a constant )
It may be determined according to.

However, in this program example, if the target left-right differential pressure ΔP _RL and the target front-rear differential pressure ΔP _FR are calculated as described above, then in step S118, the target wheel cylinder hydraulic pressure P _{j of} each wheel is calculated. Calculate (S). In the present embodiment, the wheel cylinder hydraulic pressure target value P _j (S) is the above ΔP.
_{The RL} value, the ΔP _FR value, and the calculated reference pressure P ₀ value in step S112 are calculated according to the following equation.

[Equation 8] P ₁ (S) = P ₀ + (1/2) ・ ΔP _FR − (1/2) ・ ΔP _RL --- (8)

[Equation 9] P ₂ (S) = P ₀ + (1/2) ・ ΔP _FR + (1/2) ・ ΔP _RL --- (9)

[Equation 10] P ₃ (S) = P ₀ − (1/2) ・ ΔP _FR --- (10)

[Equation 11] P ₄ (S) = P ₀ − (1/2) ・ ΔP _FR --- (11)

Thus, in step S118, the control is
For power control, target wheel cylinder hydraulic pressure P for each wheel_j
For (S), the left-right distribution and the front-rear distribution are combined,
One, each control amount ΔP on each side_RL, ΔP_FRIs the above formula 3, 6
Lateral acceleration Y at that time according to the formula _gControl share α according to
As a result, the distribution ratio according to the lateral acceleration
The target value of the wheel cylinder hydraulic pressure of the corresponding wheel is set by
Will be decided. Note that here, for simplicity,
It was decided to generate a left-right difference only on the wheel side (see
In the case of, the hydraulic pressure command value is
As shown in Section 3, one of the left and right pressure reductions, the other
It means that a braking force difference is generated by increasing the pressure)
Alone, or both front and rear wheels will produce a left-right difference
However, including that case, right and left allocation system
The control may be performed by one-side pressure reduction control. Also before
The post-allocation is also shown in the second term on each right-hand side of equations 8-11.
So basically, boosting pressure either before or after
(P₀Pressure increase), the other pressure decrease (P₀Decompression)
It means to generate more differential pressure across the front and back, but this also
With only pressure increase / decrease for front wheels only or rear wheels only
It may be in the form of generation.

After the target wheel cylinder hydraulic pressure P _j (S) value is obtained in step S118, the next step S119,
In S120, a case where the value P _j (S) becomes a negative value may occur, and in that case, the target wheel cylinder hydraulic pressure P _j (S) is set to a value of 0 to prevent the value from becoming a negative value. Execute the process. Then, as described above, after the target wheel cylinder hydraulic pressure of each wheel is determined, in step S130, the wheel cylinder hydraulic pressure (brake hydraulic pressure) of each wheel is actually set as the target hydraulic pressure each time this step is executed. The brake fluid pressure control is performed so that the program ends. The processing content consists of individually determining a control signal (P _jA (S)) corresponding to the target wheel cylinder hydraulic pressure P _j (S) and _outputting the control signal to the pressure servo unit 7. Supply of each wheel cylinder fluid pressure P ₁ ~
The actual wheel cylinder hydraulic pressure P _j (hydraulic pressure) is adjusted so as to control P ₄ to the target hydraulic pressure P _j (S), and is applied to the wheel cylinders 5L, 6L, 6R for each wheel.

By executing the control as described above, in this embodiment, the control can be efficiently performed by properly using the lateral acceleration Y _g . 3 types, 6 types, 8 to 11 shown above
As can be seen from the equation and the characteristics of FIG. 4, the region in which the lateral acceleration Y _g is small when the α value is large according to the control share ratio α (therefore, when the (1-α) value is small, When the yaw rate F / B control contribution by ΔP _FR is small, the left and right braking force distribution is the main (when α = 1, only the left and right distribution control), and when the lateral acceleration Y _g is large (that is, the α value is The smaller the (1-α) value is closer to the value 1, the smaller the contribution due to the left-right differential pressure ΔP _RL becomes, and the control is increased in the front-rear distribution control (finally, that is, when α = 0). Front and rear distribution control only).

Therefore, in the low lateral G region, the yaw rate F /
By the B type left / right distribution control, a difference in braking force is generated between the left and right wheels according to the deviation between the yaw rate and the target yaw rate, and the vehicle behavior can be controlled directly by the yawing moment by the difference. Distribution of
Similarly, the yaw rate can be controlled by the yaw rate F / B method, and the yawing moment can be indirectly controlled by using the change in the tire cornering force due to the increase / decrease in the front / rear braking force. Lateral acceleration Y that produces a control share α for distribution control and front-rear distribution control on the vehicle
It can be changed appropriately according to _g , and both controls can be operated in a more effective area in accordance with the vehicle condition.

Referring to FIG. 6, focusing on the lateral acceleration during braking, the yaw rate control effect (a) by the lateral distribution of the braking force can exhibit a substantially constant effect regardless of the magnitude of the lateral acceleration. (Conversely, it can be said that even if the lateral acceleration becomes large, it is almost the same as when the lateral acceleration is small, but the effect does not become extremely large.) There is a significant difference depending on the size of the vehicle.If the lateral acceleration is small, the effect is small.However, if the lateral acceleration is large, a very large control effect tends to appear.For example, turning the corner at a high vehicle speed. The effect is significant when braking when there is such (b). Therefore, by controlling so as to change the control sharing ratio α according to the magnitude of the lateral acceleration Y _g as in the present embodiment, the left-right distribution control shows that the lateral acceleration Y _{g in} the area where the lateral acceleration Y _g is small exhibits a higher effect. So that it can be used mainly by those who want to exert its effect sufficiently,
On the other hand, the front-rear distribution that has the yaw rate control effect on the side of large lateral acceleration Y _g , such as cornering at high vehicle speeds as described above, raises its share α in that area and makes full use of that effect. , And can be effectively used, and such a change in control sharing enables effective use of both controls in combination.

Further, from the standpoint of how it is optimal to divide the front-rear distribution and the left-right difference, the present control, which can be optimized as described above, is effective for both of these controls. As a result of being able to properly use each control in a wide range, the efficiency is high in terms of control energy (control efficiency), and even in the case of yaw rate F / B control, the control effect such as deterioration of the convergence of the yaw rate is exerted. It is also possible to improve the effectiveness of the braking force control while avoiding deterioration.

When yaw rate control is performed by combining the front-rear distribution and the left-right distribution of the braking force, it is not decided how much the two controls should control the deviation of the yaw rate, and both controls should be performed according to the deviation. Is Yaw rate F / B
Even if control is performed, it is not efficient considering the control energy. That is, although the effect of front-rear distribution control in a region where the lateral acceleration is small is small, the control is performed to drive the actuator and the effectiveness is low and the control energy is inefficient. Also, when both controls operate for the same yaw rate deviation, the feedback gain becomes too large considering the yaw rate deviation as a whole, and the yaw rate overshoots or the yaw rate convergence is deteriorated. The control may diverge.
Furthermore, in contrast to the above, if the sharing ratios of both controls are determined, but if the sharing ratios are fixed, for example, if the two controls share half of the yaw rate deviation, the control effect As a result of not considering the change due to the magnitude of the lateral acceleration of, for example, when the lateral acceleration is small, the effect of the front-rear distribution is small.
The feedback gain is the same as when the deviation is small, and the control effect may deteriorate.

According to this embodiment, both controls can be combined and both can be performed by the yaw rate F / B control without causing such a decrease in controllability, and the proper control is used according to the lateral acceleration. It is also efficient.

In the above embodiment, the sharing rate of both controls is set by the lateral acceleration Y _g detected by the lateral acceleration sensor.
It is not limited to this. For example, control share α
The longitudinal acceleration can be targeted as a parameter for setting, and the longitudinal acceleration _Xg is also detected, for example, as shown in FIG.
The share rate α may be set from the longitudinal and lateral accelerations according to the characteristics as described above.

The characteristic of FIG. 3 is represented by a three-dimensional graph of an α-value curved surface, and the surface is lower toward the front side of the figure. Specifically, the longitudinal acceleration is the same for the same Y _g value.
X _g is large enough (brake enough large becomes X _g occurs is stepped), in the figure representatively alpha (small), (medium),
As noted as (Large), the value α is set to take a small value (therefore, the (1-α) value takes a large value) (where X _g = constant state). The tendency of the characteristics when viewed is the same as the tendency of FIG. 4 even with this α curved surface characteristic). Therefore, when applying the characteristics of FIG.
The larger the Y _{g is and the} larger the longitudinal acceleration X _g is, the smaller the α value is and the lower the ratio of the left / right distribution control is. On the other hand, the larger the value (1-α) is, the more the weight is shifted to the front / rear distribution control. Therefore, it is possible to effectively use the longitudinal distribution (see Fig. 6), which has a great effect in a large region of X _g and Y _g , and the lateral acceleration X _g as well as the longitudinal acceleration X _g . If it is added as a parameter, it can be implemented in such a mode. In this case as well, the control efficiency is high, and the yaw rate F / B control force control can be appropriately performed from the viewpoint of control energy. In the case of performing in the above mode, a map search with parameters Y _g and X _g is performed, or, for example, α searched in the basic α-Y _g table is used.
The value may be multiplied by a correction coefficient according to the longitudinal acceleration X _g .

Further, according to the set share ratio, for example, when controlling the left-right distribution as the center, the left-right differential pressure (left-right hydraulic pressure difference) ΔP _RL becomes a certain set value (upper limit value). In this case, the method may be such that the front-rear distribution control is performed regardless of only the control share rate α. That is, when the reference value P ₀ is so small that the target left-right differential pressure necessary for the one-side pressure reduction cannot be sufficiently generated, although it is a region that is executed only by the left-right distribution or a region that mainly performs it (( When the brakes are not pressed too much), the left / right distribution control is the limit and no further effect can be obtained, so even in such cases, the braking force distribution is uniformly distributed with the setting control share ratio α. If maintained, there will be a limit to the improvement of the control effect. In such a case, the left / right distribution control at that time may be assisted by the front / rear distribution which is the other combination control regardless of the set share ratio. The above points can also be applied when using lateral acceleration and / or longitudinal acceleration as parameters.

Further, when the above equations 3 and 6 are applied, the feedback gains H and G of both controls are constants. However, considering that the effect changes depending on the region, H and G
G may also be a function of lateral acceleration, for example. Further, for example, the lateral acceleration may be applied to the search parameter by using an estimated value from other information.

[0034]

According to the present invention, the right / left distribution control and the front / rear distribution control are applied to the vehicle behavior control in an appropriate combination, and the control is changed according to the lateral acceleration and / or the longitudinal acceleration generated in the vehicle at the time of control. Both controls can be operated in a more effective region with a sharing ratio, and high control efficiency and controllability can be ensured, and control of vehicle behavior by yaw rate feedback braking force control can be improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a braking force control device of the present invention.

FIG. 2 is a system diagram showing an embodiment of the present invention.

FIG. 3 is a flowchart showing an example of a control program of a controller in the same example.

FIG. 4 is a diagram showing an example of characteristics of lateral acceleration-control share ratio applicable to the program.

FIG. 5 is a diagram showing an example of a control share ratio characteristic when including longitudinal acceleration.

FIG. 6 is a diagram illustrating the principle of the present distribution control, and is a diagram for explaining the yaw rate control effect.

[Explanation of symbols]

 1L, 1R Left and right front wheels 2L, 2R Left and right rear wheels 3L, 3R, 4L, 4R Brake discs 5L, 5R, 6L, 6R Wheel cylinder 7 Pressure servo unit 8 Hydraulic pressure source 9 Controller 10 Steering wheel 11 Steering angle sensor 12 Brake pedal 13 Tread force sensor 14 Yaw rate sensor 15 to 18 Wheel speed sensor 19 Lateral acceleration sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Maruko 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (2)

[Claims] 1. In a vehicle capable of controlling the braking force of each wheel, a running state detecting means for detecting a running state of the vehicle including a steering state of a steering wheel, and a yaw rate detecting means for detecting a yaw rate occurring in the vehicle. A target yaw rate setting means for setting a target yaw rate based on the output of the running state detection means, a deviation calculation means for calculating a deviation between the target yaw rate and the generated yaw rate, and a lateral acceleration and / or a longitudinal acceleration generated in the vehicle are detected. Lateral acceleration and / or longitudinal acceleration detecting means, and control sharing rate setting means for setting control sharing rates for both lateral distribution and longitudinal distribution of braking force according to the output of the lateral acceleration and / or longitudinal acceleration detecting means. As a means for controlling the wheel braking force, the eyes in the left / right distribution control are based on the yaw rate deviation and the control share ratio. The target left / right distribution calculation means and the target front / rear distribution calculation means for calculating the left / right distribution and the target front / rear distribution in the front / rear distribution control are included. And a wheel braking force control means for controlling the braking force of the controlled wheel. 2. The braking force control device according to claim 1, wherein a control share ratio of front-rear distribution control is increased with an increase in lateral acceleration.