JPH08310361A - Vehicle turning control device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a turning control device for a vehicle, an overshoot of a brake pressure supplied to a wheel brake is prevented, and the turning behavior of the vehicle is reliably and promptly stabilized. [Configuration] A required control amount for controlling a yaw moment of the vehicle is set according to a driving state of the vehicle and / or a behavior of the vehicle, and a braking force difference is generated between two or more predetermined wheels based on the required control amount. The control means for controlling the yaw motion of the vehicle includes a restricting means (S645 to S649) for restricting the control of the yaw motion when the absolute value of the required control amount tends to decrease.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle turning control device, and more particularly to a device for controlling a yaw motion of a vehicle.

[0002]

2. Description of the Related Art In recent years, a yaw rate sensor has been put into practical use, which is attached to an object to detect the yawing (yaw motion) of the object and detect the degree of yawing, that is, the yaw rate. Then, this yaw rate sensor is mounted on a vehicle together with other sensors such as an acceleration sensor (lateral G sensor) that detects lateral acceleration and an acceleration sensor (front and rear G sensor) that detects longitudinal acceleration, and the detection signal According to Japanese Patent Laid-Open No. 3-112755, a turning behavior control device (a turning control device for a vehicle) that controls braking force and the like for each wheel to generate a desired rotational moment in the vehicle and thereby appropriately controls the vehicle attitude is disclosed in Japanese Patent Laid-Open No. 3-112755. It is disclosed in the gazette and the like.

[0003]

Generally, in order to generate braking force on the wheels for controlling the turning of the vehicle, the wheel brakes provided on the wheels are driven. This wheel brake is equipped with a wheel cylinder as its drive device.
Liquid pressure (brake pressure) of the liquid supplied from the master cylinder connected to the brake pedal or the hydraulic pressure generation unit
The wheel brake is driven by this, and an appropriate braking force corresponding to the brake pressure is generated on the wheel.

By the way, since the liquid supplied to the wheel cylinder has an inertial mass, it is difficult for the brake pressure to follow the control signal very accurately and accurately. Therefore, in a situation where the magnitude of the control signal changes frequently, the brake pressure cannot follow the control signal at the point of change of the control signal and overshoots, so-called hunting occurs, and good turning control is performed. May not be implemented.

The present invention has been made based on the above-mentioned circumstances, and an object thereof is to prevent overshoot of the brake pressure supplied to a wheel brake,
It is an object of the present invention to provide a vehicle turning control device capable of reliably and quickly stabilizing the turning behavior of a vehicle.

[0006]

In order to achieve the above-mentioned object, the invention of claim 1 sets a required control amount for controlling the yaw moment of a vehicle according to the driving state of the vehicle and / or the behavior of the vehicle. In a turning control device for a vehicle, which comprises a control means for controlling a yaw motion of the vehicle by generating a braking force difference between two or more predetermined wheels based on the required control amount, the absolute value of the required control amount is reduced. In the case of a tendency, a regulation means for regulating the control of the yaw motion is provided.

Further, in the invention of claim 2, the regulating means includes a determining means for determining that the decreasing tendency is present when the time differential value of the absolute value of the required control amount is not more than a predetermined value. And Further, in the invention of claim 3, when the absolute value of the required control amount tends to decrease,
A holding means for holding each braking force of the predetermined wheel is included.

Further, in the invention of claim 4, the control means includes a yaw rate detecting means for detecting a yaw rate of the vehicle, and a setting means for setting the required control amount based on an actual yaw rate detected by the yaw rate detecting means. It is characterized by including. Further, in the invention of claim 5, the control means includes target yaw rate setting means for setting a target yaw rate of the vehicle, and the setting means is a yaw rate deviation between the actual yaw rate and the target yaw rate or a time derivative of the yaw rate deviation. The required control amount is set based on a value.

Further, in the invention of claim 6, when the vehicle is being braked by turning, only the front outer wheel and the rear inner wheel are set as control target wheels in the turning direction, and one of the wheels is controlled based on the required control amount. The braking force of the other wheel is increased and the braking force of the other wheel is decreased.

[0010]

According to the vehicle turning control device of the first aspect, the required control amount for yaw moment control is set according to the driving state of the vehicle and / or the behavior of the vehicle, and the predetermined wheel is controlled according to this required control amount. The braking force between them is controlled, and the yaw motion of the vehicle is suitably controlled. At this time, when the required control amount changes and its absolute value tends to decrease, the control of the yaw motion is prohibited or limited by the restricting means. As a result, the supply of the brake pressure to the wheel brakes provided on the wheels is stopped, and the overshoot of the supplied brake pressure, which is caused by the difficulty in following the control signal, is preferably prevented, and a good vehicle turning is achieved. Control is implemented.

According to the vehicle turning control device of the second aspect, the time differential value of the absolute value of the required control amount is obtained, and when the time differential value becomes equal to or less than the predetermined value, the required control amount is It is determined that the decreasing tendency has occurred, and the determination of the switching of the decreasing tendency is always reliably performed. Further, according to the vehicle turning control device of the third aspect, the control of the yaw motion is prohibited or restricted in accordance with the required control amount, so that the brake pressure in the wheel brake provided on the wheel is appropriately held. As a result, the overshoot of the supply brake pressure is appropriately prevented, and good turning control of the vehicle is performed.

Further, according to the vehicle turning control device of the fourth aspect, the yaw rate detecting means detects the actual yaw rate, the required control amount is set based on the actual yaw rate, and more accurate turning control of the vehicle is performed. To be done. According to the vehicle turning control device of the fifth aspect, the yaw rate deviation between the target yaw rate and the actual yaw rate or the time derivative of the yaw rate deviation is obtained, and the required control is performed according to the yaw rate deviation or the time derivative of the yaw rate deviation. The amount is set more finely.

Further, according to the vehicle turning control device of the sixth aspect, at the time of turning braking of the vehicle, the braking force of one of the front outer wheel and the rear inner wheel is increased with respect to the turning direction. It is controlled so that the braking force of the other wheel is reduced, whereby an effective rotational moment, that is, a yaw motion is generated in the vehicle, and good turning control of the vehicle is performed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a vehicle braking system is schematically illustrated. This brake system is equipped with a tandem type master cylinder 1, and the master cylinder 1 is connected to a brake pedal 3 via a vacuum brake booster 2. The pair of pressure chambers of the master cylinder 1 are respectively connected to the reservoir 4, while the main brake pipe lines 5 and 6 extend from these pressure chambers.

The main brake pipe lines 5 and 6 extend in the hydraulic unit (HU) 7, and the main brake pipe lines 5 and 6 are branched into a pair of branch brake pipe lines, respectively. The branch brake pipelines 8 and 9 from the main brake pipeline 5 are connected to the wheel brakes (not shown) of the left front wheel FWL and the right rear wheel RWR, respectively, and the branch brake pipeline 10 from the main brake pipeline 6 is Reference numeral 11 is connected to the wheel brakes (not shown) of the right front wheel FWR and the left rear wheel RWL, respectively. Therefore, the wheel brakes of the respective wheels are connected to the tandem master cylinder 1 in a cross piping type.

An electromagnetic valve is inserted in each of the branch brake pipe lines 8, 9, 10, and 11, and each electromagnetic valve is composed of an inlet valve 12 and an outlet valve 13. A proportional valve (PV) is inserted between the rear wheel brake and the corresponding solenoid valve, that is, the inlet valve 12. On the side of the branch brake pipes 8 and 9, the outlet valve 13 of the pair of solenoid valves is connected to the reservoir 4 via the return route 14, and also on the side of the branch brake pipes 10 and 11,
An outlet valve 13 of the pair of solenoid valves is connected to the reservoir 4 via a return path 15. Therefore, the brake pressure of each wheel is controlled by supplying and discharging the pressure in the wheel brake by opening and closing the inlet valve and the outlet valve.

Discharge ports of pumps 16 and 17 are connected to the main brake lines 5 and 6 respectively along the way through check valves, and these pumps 16 and 17 are connected to a common motor 18. There is. On the other hand, the suction ports of the pumps 16 and 17 are connected to the return paths 14 and 15 via the check valves, respectively. Further, cut-off valves 19 and 20 composed of electromagnetic valves are inserted in the main brake pipe lines 5 and 6 at a portion upstream from a connection point with the pumps 16 and 17, and the cut-off valves 19 and 20 are also provided. Relief valves 21 are arranged so as to bypass 20. Here, the cutoff valves 19 and 20 form a cutoff valve unit (CVU) 22.

The inlet and outlet valves 12 and 13, the cutoff valves 19 and 20, and the motor 18 described above are electrically connected to an electronic control unit (ECU) 23. More specifically, the ECU 23 includes a microprocessor, a storage device such as a RAM and a ROM, and an input / output interface.
3, 19, 20 and the motor 18 are connected to the output interface.

On the other hand, a wheel speed sensor 24 provided for each wheel and a rotation speed sensor 25 for detecting the rotation speed of the motor 18 are electrically connected to the input interface of the ECU 23. In addition, in FIG. 1, for convenience of drawing,
The connection between the motor 18 and the ECU 23 and the connection between the rotation speed sensor 25 and the ECU 23 are omitted. Further, as shown in FIG. 2, the input interface of the ECU 23 includes a wheel speed sensor 24 and a rotation speed sensor 25.
Besides, the steering wheel angle sensor 26, the pedal stroke sensor 27, the longitudinal G sensor 28, the lateral G sensor 29, and the yaw rate sensor 30 are electrically connected.

The steering wheel angle sensor 26 detects the steering amount of the steering wheel of the vehicle, that is, the steering wheel angle, and the pedal stroke sensor 27 detects the depression amount of the brake pedal 3, that is, the pedal stroke. The longitudinal G and lateral G sensors 28 and 29 detect longitudinal acceleration and lateral acceleration acting in the longitudinal and lateral directions of the vehicle, respectively, and the yaw rate sensor 30 detects a yaw angular velocity around the center of gravity of the vehicle.

The ECU 23 follows the various vehicle motion control based on the sensor signals of the above-mentioned various sensors and follows the HU 7 and the CV.
Controls the operation of U22. The vehicle motion control is shown in FIG.
As shown in the block of the ECU 23, there are yaw moment control, traction control (TCL) control, anti-skid brake (ABS) control, front and rear wheel braking force distribution control, etc. when the vehicle is turning. .

Referring to FIG. 3, the functions related to the yaw moment control among the functions of the ECU 23 are shown in more detail, and FIG. 4 shows a main routine for executing the functions related to the yaw moment control. Has been done. The control cycle T of the main loop is set to 8 msec, for example. First, when the sensor signals from the various sensors described above are supplied to the ECU 23, the ECU 23 filters the sensor signals (block 32 in FIG. 3). A recursive first-order low-pass filter is used for the filtering process here. Unless otherwise specified, the recursive first-order low-pass filter is also used in the following filter processing.

The filtered sensor signals, namely the wheel speed Vw (i), the steering wheel angle θ, the pedal stroke St, the longitudinal acceleration Gx (longitudinal Gx), the lateral acceleration Gy (lateral Gy) and the yaw rate γ are shown in FIG. The information read in step S1 is calculated based on these sensor signals, and the information indicating the motion state of the vehicle and the information for determining the driving operation of the driver are calculated (step S2).

In step S1, the wheel speed Vw
(I) is for collectively indicating the wheel speed of each wheel, and i is an integer from 1 to 4 that identifies the wheel. For example, i = 1 is the left front wheel FWL, i = 2 is the right front wheel FWR, i = 3 is the left rear wheel RWL, and i = 4 is the right rear wheel RWR.
Represents It should be noted that i attached to the following reference numerals is also used in the same meaning.

As shown in FIG. 3, the execution of step S2 is represented by the arithmetic units 34 and 36, respectively.
At 4, the wheel speed Vw (i), longitudinal Gx, lateral Gy and yaw rate γ
Based on the above, the motion state of the vehicle is calculated, and the calculation unit 36 determines the operation status of the steering wheel and the brake pedal by the driver based on the steering wheel angle Th and the pedal stroke St.

Vehicle motion state: Reference wheel speed: First, reference wheel speed V is calculated from among wheel speeds Vw (i).
s is selected, but here, the reference wheel speed Vs is one of the wheels that are not easily affected by the slip of the wheels due to the drive control, specifically, among the non-driving wheels when the vehicle is not braking. It is set to the faster wheel speed Vw, and is set to the fastest wheel speed Vw in the wheel speed Vw (i) during braking. It should be noted that whether or not the vehicle is in non-braking state is determined by a brake flag Fb set by pedal operation of the brake pedal 3 described later.

Vehicle speed: Next, with respect to the reference wheel speed Vs,
When the vehicle is turning, the center-of-gravity speed at the center-of-gravity position of the vehicle is calculated in consideration of the speed difference between the inner and outer wheels and the speed ratio between the front and rear wheels, and the vehicle body speed is determined based on this center-of-gravity speed. To do. First, yaw rate γ, front tread Tf,
If the rear tread Tr is used, the inner and outer wheel speed differences ΔVif and ΔVir between the front wheels and the rear wheels are expressed by the following equations.

ΔVif = γ × Tf ΔVir = γ × Tr Therefore, the average inner / outer wheel speed difference ΔVia between the front wheels and the rear wheels is expressed by the following equation. ΔVia = γ × (Tf + Tr) / 2 Regarding the speed ratio between the front and rear wheels, if it is assumed that the turning center of the vehicle is on the extension line of the rear axle and the vehicle is turning right, Speed ratio Rvr between front and rear wheels,
Rvl is represented by the following equation.

Rvr = cos (δ) Rvl≉cos (δ) Therefore, the front-rear wheel speed ratio Rv can be expressed by cos (δ) regardless of right and left. In the above equation, δ represents the front wheel steering angle (steering wheel angle / steering gear ratio).

However, the above equation is valid only when the vehicle is at a low speed (more accurately, when the lateral Gy is small).
The correction of the center-of-gravity velocity based on the front-rear wheel speed ratio Rv is limited to low speed only as shown below. Vbm ≧ 30 km / h, Rv = 1 Vbm <30 km / h, Rv = cos (δ) Here, Vbm represents the vehicle speed calculated in the previous routine, and this vehicle speed Vb The calculation will be described later.

If the vehicle is a front-wheel drive vehicle (FF vehicle), the reference wheel speed Vs follows the wheel speed of the rear outer wheel of the vehicle during turning without braking.
By adding 1/2 of the average inner / outer wheel speed difference ΔVia to s and the speed difference between the speed at the rear axle and the speed at the center of gravity,
Center-of-gravity velocity is obtained. However, in order to avoid complication of the calculation formula, if the center-of-gravity velocity is an intermediate value between the speeds of the front and rear axles, the center-of-gravity velocity Vcgo before filtering should be calculated by the following formula. You can

Vcg0 = (Vs-ΔVia / 2) × (1+ (1
/ Rv)) / 2 On the other hand, during turning during braking, it can be considered that the reference wheel speed Vs follows the wheel speed of the front outer wheel of the vehicle. Wheel speed difference Δ
By correcting the speed difference between 1/2 of Via and the speed at the front axle and the speed at the center of gravity, the center-of-gravity speed Vcg0 before filtering can be obtained from the following equation.

Vcg0 = (Vs−ΔVia / 2) × (1 + Rv) / 2 After that, the center-of-gravity velocity Vcg0 is continuously processed twice by the filter process (fc = 6 Hz) to obtain the center-of-gravity velocity Vcg (= LPF (LPF (LPF ( Vc
g0)) is obtained. In calculating the center-of-gravity velocity Vcg, it is determined based on the above-mentioned brake flag Fb whether or not the vehicle is in the non-braking state.

Normally, the center-of-gravity velocity Vcg coincides with the vehicle body velocity Vb, so that the center-of-gravity velocity Vcg is set as the vehicle body velocity Vb.
That is, the vehicle body speed Vb is usually calculated by the following equation. Vb = Vcg However, in the situation where the selected wheel having the reference wheel speed Vs falls into the lock tendency and the ABS control is started also for the selected wheel, the reference wheel speed Vs follows the slip of the selected wheel. Will sink and the speed will drop significantly below the actual vehicle speed.

Therefore, in such a situation, the vehicle body speed Vs is based on the front-rear Gx and the center-of-gravity speed Vs under the following separation conditions.
It is estimated to separate from cg and decrease with the following slope. When the separation judgment value is Gxs, dVcg / d
The condition of t ≦ Gxs continues for 50 msec, or dVcg
When the condition of /dt≦-1.4 g is satisfied, the vehicle body speed Vs is estimated separately from the center of gravity speed Vcg.

Here, the separation judgment value Gxs is set by the following equation. Gxs =-(| Gx | +0.2) However, -1.4g≤Gxs≤ -0.
35g When the above-mentioned separation condition is satisfied, the vehicle body speed Vs is estimated based on the following equation. Vb = Vbm-ΔG Vbm represents the vehicle speed before the separation condition is satisfied, and ΔG represents the gradient set under the following conditions.

ΔG = (| Gx | +0.15) where -1.2 g
≤ΔG≤ -0.3g When the vehicle body speed Vb is estimated separately from the center-of-gravity velocity Vcg, the condition for returning to the center-of-gravity velocity Vcg, that is, the separation end condition is as follows. Vcg> Vbm Slip rate: Next, the above-mentioned average inner / outer wheel speed difference Via and the front / rear wheel speed ratio Rv are added to the calculated vehicle speed Vb, and the reference wheel position speed V at each wheel position is calculated based on the following equation.
Calculate r (i).

Vr (i) = Vb × 2 / (1 + Rv) + (or−) Via / 2 Here, regarding the positive / negative sign of the second term in the above formula, when the vehicle turns right, the outer front and rear wheels The reference wheel position speed corresponding to (1) is (+), and the reference wheel position speed corresponding to the front and rear wheels of the inside is (-). On the other hand, when the vehicle turns left, the positive and negative signs are opposite.

The slip ratio Sl (i) of each wheel is calculated by the following equation, and the calculated value is filtered (fc = 1).
0Hz). Sl0 (i) = (Vr (i) -Vw (i)) / Vr (i) Sl (i) = LPF (Sl0 (i)) Note that Sl0 (i) represents the slip ratio before filtering. .

Center-of-gravity slip angular velocity: The relationship between the center-of-gravity slip angular velocity dβ and the yaw rate γ is represented by the following equation, where ω is the angular velocity with respect to the turning center of the vehicle (revolution speed of the vehicle). γ = dβ (= βg) + ωβg; center-of-gravity slip angle Here, assuming that the center-of-gravity slip angle βg is small and the vehicle speed is V, the following formula is established.

Gy = V × ω Vb = V × cos (βg) = V If ω and V are eliminated from the above three equations, the center-of-gravity slip angular velocity dβ0 before filtering can be obtained from the following equation. dβ0 = γ-Gy / Vb Again, the center of gravity slip angular velocity dβ0 is filtered (f
c = 2 Hz), the center-of-gravity slip angular velocity dβ is obtained as shown in the following equation.

Dβ = LPF (dβ0) Regardless of the turning direction of the vehicle, the positive and negative of the center-of-gravity slip angular velocity dβ are positive on the understeer (US) side and negative on the oversteer (OS) side. , The calculated gravity center slip angular velocity dβ is multiplied by (−), and the positive / negative sign is inverted.

When the vehicle is running at a low speed, that is, Vb <10 km / h
When the condition of is satisfied, the calculation of the center-of-gravity slip angular velocity dβ is prohibited in order to prevent calculation overflow.
The center-of-gravity slip angular velocity dβ is set to zero. : Judgment of driving operation: Steering wheel angular velocity; Now, assume that the steering wheel angle θ changes as shown in FIG.

Here, the steering wheel angular velocity θa when the steering wheel angle θ changes can be obtained by dividing the change amount of the steering wheel angle θ by the time required for the change. For example, as shown in FIG.
Assuming that the steering wheel angle θ changes by Δθ (n + 4) at n + 4, the steering wheel angular velocity θa0 (n + 4) at time n + 4 is calculated by the following equation.

Θa0 (n + 4) = Δθ (n + 4) / (4 × T) T is the control cycle of the main routine as described above. On the other hand, when the steering wheel angle θ does not change, the steering wheel angular velocity θa is in the same direction as the steering wheel angle θ when the steering wheel angle θ was last changed, and the steering wheel angle θ has the minimum change amount Δθmi.
It is obtained by dividing the minimum change amount Δθmin by the time required for the change, assuming that the change amount is n. For example, time n + 2
The steering wheel angular velocity θa0 (n + 2) at is calculated by the following equation.

Θa0 (n + 2) = Δθmin / (2 × T) Again, the steering wheel angular velocity θa0 is filtered (fc = 2H
z), the steering wheel angular velocity θa is calculated from the following equation. θa = LPF (θa0) Steering wheel angular velocity effective value: Steering wheel angular velocity effective value θae is
It is obtained by filtering the absolute value of the steering wheel angular velocity θa as shown in the following equation.

Θae = LPF (| θa |) In the filtering process here, whether the value of fc (cutoff frequency) is on the increasing side or the decreasing side of the steering wheel angle θa, that is, the value of It depends on the positive / negative, for example, fc = 20Hz in the direction in which the steering wheel angle θa increases,
On the contrary, fc = 0.32 Hz is set in the direction in which the steering wheel angle θa decreases.

Brake pedal stroke speed:
For the pedal stroke speed Vst, the difference between the pedal strokes St is filtered (fc = 1H as shown in the following equation.
z) is obtained. Vst = LPF (St (n) -St (n-1)) where St (n-1) is the pedal stroke read in the previous routine, and St (n) is read in this routine. Brake pedal brake flag indicating pedal stroke: The above-mentioned brake flag Fb is set as follows based on the pedal stroke St or the pedal stroke speed Vst.

When the condition of St> Ste or Vst> 50 mm / s is satisfied, Fb = 1, and other than the above conditions, Fb = 0 where Ste is in the master cylinder 2 when the brake pedal 3 is depressed. It is the amount of depression that the pressure actually rises. The brake flag Fb is used when selecting the reference wheel speed Vs and calculating the center-of-gravity speed Vcg as described above.

Brake pedal additional depression flag: The additional depression flag Fpp is set as follows based on the pedal stroke speed Vst. In the case of Vst> 50 mm / s, Fpp = 1, in the case of Vst <20 mm / s, Fpp = 0. The routine for setting the above-described step-on additional flag Fpp is shown in FIG. In this setting routine, when the pedal stroke speed Vst is read (step S201), the step-on additional flag Fpp is set based on the determination results of steps S202 and S204 (steps S203 and S205).

Turning determination: When various kinds of information indicating the motion state of the vehicle and various kinds of information for judging the driving operation of the driver are obtained as described above, as shown in FIG. The turning determination is performed. In the case of FIG. 3, the determination of the turning direction is performed by the calculation unit 38, the details of which are shown in FIG. 7. The details of step S3 are shown in the determination routine of FIG.

Here, the turning direction of the vehicle and the counter steer are determined based on the steering wheel angle θ and the yaw rate γ. First, the turning angle flag Fds based on the steering wheel angle is determined from the map Mθ shown in the block in FIG. 7 based on the steering wheel angle θ. Specifically, the steering wheel angle θ is 10
When deg is exceeded in the positive direction, the turning direction flag Fds is set to 1, and in this case, the turning direction flag Fds indicates that the vehicle is turning right. On the other hand, the steering wheel angle θ
When -10 deg exceeds -10 deg in the negative direction, 0 is set in the turning direction flag Fds, and the turning direction flag Fds indicates that the vehicle is turning left.

The setting of the turning angle flag Fds based on the steering wheel angle here is shown in steps S301 to S304 in FIG. When the steering wheel angle θ is in the range of −10 deg ≦ θ ≦ 10 deg, the turning direction flag Fds is maintained at the value set in the previous routine. On the other hand, based on the yaw rate γ, the yaw rate based turning direction flag Fdy is determined from the map Mγ shown in the block in FIG. Specifically, when the yaw rate γ exceeds 2 deg / s in the positive direction,
The turning direction flag Fdy is set to 1, and in this case, the turning direction flag Fdy indicates that the vehicle is turning right. On the other hand, when the yaw rate γ exceeds -2 deg / s in the negative direction, the turning direction flag Fdy is set to 0, and the turning direction flag Fdy indicates that the vehicle is turning left.

The setting of the yaw rate-based turning direction flag Fdy here is shown in steps S305 to S308 in FIG. 8, and the yaw rate γ is -2 deg / s≤θ≤2 deg / s.
It goes without saying that the turning direction flag Fdy is maintained at the value set in the previous routine when the value is within the range. When the turning direction flags Fds and Fdy are set as described above, one of them is set to the switch S in FIG.
The turning flag Fd is selected by Wf. The switch SWf is switched by a switching signal output from the determination unit 40 in FIG.

That is, when the condition that the ABS control is operating on at least one front wheel and the brake flag Fb is set to 1 is satisfied, the determination unit 40 causes the switch SW to switch.
A switching signal for switching f to the upper side is output as indicated by a dashed arrow in FIG. 7, and in this case, the turning flag Fd is the turning direction flag Fds based on the steering wheel angle as shown in the following equation.
Is selected.

Fd = Fds However, when the above condition is not satisfied, the switch SWf is switched as shown by the solid arrow, and in this case, the turning flag Fd is set to the yaw rate base as shown in the following equation. The turning direction flag Fdy is selected. Fd = Fdy The turning flag Fd here is set in step S309 to FIG.
This is shown in S311.

Further, after the turning flag Fd is set, in step S312 in FIG. 8, it is judged whether or not the values of the turning direction flag Fds and the turning direction flag Fdy match, and the result of the judgment here. Is true (Yes), that is, when the yawing direction of the vehicle body does not match the operating direction of the steering wheel, the canter steer flag Fcs is set to 1 (step S314).

On the other hand, if the determination result in any of steps S312 and S313 is false (No), the counter steer flag Fcs is set to 0 (step S315). : Calculation of target yaw rate: Next, in the routine of FIG. 4, steps S3 to S
4, the target yaw rate of the vehicle is calculated by the calculation unit 39 in FIG. 3, the details of which are shown in the block diagram of FIG.

First, the vehicle speed Vb and the front wheel steering angle δ are supplied to the calculating unit 42, where after the steady gain is obtained, the steady gain is subjected to a two-step filtering process as shown by blocks 44 and 46. Thus, the target yaw rate γt is calculated. Here, the front wheel steering angle δ is expressed by the following equation, where the steering gear ratio is ρ as described above.

Δ = θ / ρ The steady-state gain indicates the steady-state value of the yaw rate response to the steering of the vehicle, which can be derived from the linear two-wheel model of the vehicle, and the first-stage filtering process is for noise removal. A low-pass filter (LPF1) is used, and a low-pass filter (LPF2) for first-order lag response is used for the second stage filter processing.

Therefore, the target yaw rate γt is calculated from the following equation. γt = LPF2 (LPF1 (Vb / (1 + A × Vb ² ) × (δ /
L))) In the above equation, A is the stability factor and L is the wheel base. Calculating the required yaw moment; When the target yaw rate γt is calculated in the previous step S4, the required yaw moment is calculated in step S5 in the routine of FIG. 3 and in the routine of FIG. The details of step S5 and step S5 are shown in the block diagram of FIG. 10 and the flowchart of FIG. 11, respectively.

First, as shown in FIG. 10, the subtractor 48 calculates the yaw rate deviation Δγ between the target yaw rate γt and the detected yaw rate γ. This is shown in steps S501 and S502 in FIG. Here, in step S502, the positive / negative of the yaw rate deviation Δγ is unified as positive on the understeer (US) side and negative on the oversteer (OS) side. Therefore, the yaw rate deviation Δγ is left when the vehicle turns left.
Reverses the sign of. The turning direction of the vehicle can be determined based on the value of the turning flag Fd described above.

Further, in step S502, the maximum yaw rate deviation Δγmax is calculated as shown in the following expression by filtering the absolute value of the calculated yaw rate deviation Δγ. Δγmax = LPF (| Δγ |) In the filtering process here, the value of fc differs depending on whether the yaw rate deviation Δγ is increasing or decreasing. For example, fc = 10Hz on the increasing side and its decreasing On the side, fc = 0.08Hz is set.

When the yaw moment control ends (when the yaw moment control start / end flag Fym, which will be described later, becomes 0).
In this case, the maximum yaw rate deviation Δγmax is set to the absolute value of the yaw rate deviation Δγ as shown in the following equation. Δγmax = | Δγ | Next, the yaw rate deviation Δγ is calculated by the differentiating section 50 of FIG. 10 as shown in the following equation, and after its differential value, that is, the difference is calculated, it is filtered (fc = 5 Hz) and the yaw rate deviation is differentiated. The value Δγs is obtained.

Δγs = LPF (Δγ−Δγm) In the above equation, Δγm is the yaw rate deviation calculated in the previous routine. Also here, for the same reason as in the case of the yaw rate deviation Δγ, the positive / negative of the yaw rate deviation differential value Δγs is inverted when the vehicle turns left. The step of calculating the yaw rate deviation differential value Δγs described above is shown in step S503 of FIG.

Thereafter, as shown in FIG. 10, the yaw rate deviation differential value Δγs is multiplied by the feedback gain, that is, the proportional gain Kp in the multiplication section 52, and the yaw rate deviation Δγ is multiplied by the multiplication section 54. Are multiplied by the integral gain Ki, and these multiplication values are added by the adder 56.
Will be added at. Furthermore, the required yaw moment γd is obtained by multiplying the added value output from the adder 56 by the correction value Cpi in the multiplier 58.

Here, the correction value Cpi takes different values depending on whether the vehicle is braking or not, and is set as follows, for example. When braking (Fb = 1), Cpi = 1.0 When not braking (Fb = 0), Cpi = 1.5 The above-described calculation of the required yaw moment γd is performed in steps S504 and S505 in the routine of FIG. It

Step S504 is a step of calculating the above-mentioned proportional and integral gains Kp and Ki, and the calculation procedure of the proportional gain Kp is shown in the block diagram of FIG. The proportional gain Kp is a reference value Kpu (for example, 4 kgm / s / (deg / s ² )) which is different between the time of turning in the US and the time of turning in the OS,
Kpo (for example, 5 kgm / s / (deg / s ² )), and use of these reference values Kpu and Kpo is selected by the switch SWp.

The switch SWp is switched by the judgment signal from the judgment unit 60, and this judgment unit 60 makes the judgment signal for changing the switch SWp to the reference value Kpu side when the above-mentioned yaw rate deviation differential value Δγs becomes 0 or more. Output. The reference value output from the switch SWp has a multiplication unit 6
The correction coefficients Kp1, Kp2, and Kp3 are sequentially multiplied at 2, 64, and 66, whereby the proportional gain Kp is calculated.

Therefore, the proportional gain Kp is calculated by the following equation. US: Kp = Kpu × Kp1 × Kp2 × Kp3 OS: Kp = Kpo × Kp1 × Kp2 × Kp3 When the yaw moment control for the vehicle body is activated before the vehicle reaches the limit travel area, the driver is informed. The correction coefficient Kp1 is used to correct the proportional gain Kp so that the proportional gain Kp works effectively only when the yaw rate deviation Δγ or the lateral Gy of the vehicle body becomes large.

The correction coefficient Kp2 is used to correct the proportional gain Kp for the following reason. That is, when the yaw rate γ is simply made to follow the target yaw rate γt, when the road surface is a low μ road, the lateral force of the vehicle body reaches its limit value as shown in FIG. As a result of the increase of the slip angle β, the vehicle body may spin, and the correction coefficient Kp2 is set to prevent this. In other words, when the correction coefficient Kp2 is set appropriately,
As shown in FIG. 3 (b), the center of gravity slip angle β of the vehicle body is kept small, which is considered to prevent the vehicle body from spinning. Note that FIG. 13C shows the case of the high μ road.

On the other hand, the correction coefficient Kp3 is used to correct the proportional gain Kp for the following reasons. That is,
When the vehicle is running on a rough road and a vibration component is added to the output of the yaw rate sensor 30, the influence of the vibration component is greatly shown in the yaw rate deviation differential value Δγs, which causes malfunction of control and deterioration of controllability. . Therefore, the correction coefficient Kp3 reduces the proportional gain Kp to prevent the above-mentioned problems.

Next, referring to FIG. 14, there is shown a block diagram of a procedure for calculating the integral gain Ki described above.
Here, as in the case of the proportional gain Kp, the reference integral gain Ki0 (for example, 10 kgm / s / (deg / s)) is used, and this reference integral gain Ki0 is sequentially corrected by the multiplying units 74 and 76 in the correction coefficients Ki1 and The integral gain Ki is calculated by multiplying Ki2. Therefore, the integral gain Ki is calculated from the following equation.

Ki = Ki0 × Ki1 × Ki2 The correction coefficient Ki1 is used to reduce the integral gain Ki for the following reasons. That is, when the steering angle of the front wheels is increased, the error of the target yaw rate γt may further increase the error of the yaw rate deviation Δγ, which may cause a malfunction of the control. Decrease Ki.

On the other hand, the correction coefficient Ki2 is the integral gain Ki for the same reason as the correction coefficient Kp2 of the proportional gain Kp described above.
Is used to reduce In addition, these K
Details of p1, Kp2, Kp3 and Ki1, Ki2 are omitted here. : Yaw Moment Control: When the required yaw moment γd is calculated as described above, the yaw moment control of the calculation unit 78 is executed in the next step S6 in the main routine of FIG. The details of are shown in FIG.

First, in the yaw moment control of FIG. 15, the control start / end determination section 80 determines the control start / end flag Fymc based on the required yaw moment γd. Specifically, the control start / end flag Fymc is as shown in FIG.
Is determined by the judgment circuit of. This determination circuit is an OR circuit 8
1, and an ON / OFF signal corresponding to the required yaw moment γd is input to the two input terminals of the OR circuit 81.

Specifically, an ON signal is input to one input terminal of the OR circuit 81 when the required moment γd is smaller than a threshold value γos (eg, -100 kgm / s) on the OS side, and the other input terminal. When the required moment γd is larger than the threshold value γus on the US side (for example, 200 kgm / s), an ON signal is input to the. Therefore, when the required yaw moment γd exceeds one of the threshold values, an ON signal is output from the output terminal of the OR circuit 81, and this ON signal is input to the set terminal S of the flip-flop 82. As a result, the control start / end flag Fymc is output from the output terminal Q of the flip-flop 82, and in this case, Fymc = 1 indicating the start of control.
Is output.

Here, the absolute value of the threshold γos on the OS side (100 k
gm / s) is smaller than the absolute value (200 kgm / s) of the threshold value γus on the US side, so that the control start / end flag F is set on the OS side.
The output timing of ymc = 1, that is, the yaw moment control start timing is earlier than that on the US side. On the other hand, the reset terminal R of the flip-flop 82
Is supplied with a reset signal for determining the reset timing of the control start / end flag Fymc, that is, the output timing of Fymc = 0 from the flip-flop 82.

The circuit for generating the reset signal includes a switch 83 as shown in FIG. 16, and the switch 83 has two input terminals. Switch 8
The first end determination time tst1 (for example, 152 msec) is supplied to one of the input terminals of No. 3 and the second end is supplied to the other of the input terminals.
The end determination time tst2 (for example, 504 msec) is supplied.

The switch 83 is adapted to be switched in response to a switching signal from the judging section 84. Here, when the behavior of the vehicle body is stable, the judging section 84 satisfies the following conditions. If so, a first switching signal for outputting the first end determination time tst1 as the end determination time tst is output from the output terminal of the switch 83. If even one of the above conditions is not satisfied, the switch 83 A second switching signal for outputting the second end determination time tst2 as the end determination time tst is output from the output terminal.

Conditions: Target yaw rate γt <10 deg / s, yaw rate γ <10 deg / s, and steering wheel angular velocity effective value θa
e <200 deg / s Next, the output of the end determination time tst is supplied to the determination unit 85, which holds or does not control the brake pressure control signal (control mode M (i) described later (In the holding or non-control mode) continues for the end determination time tst or longer, the end instruction flag Fst
(i) = 1 is output, and if the condition is not satisfied, the end instruction flag Fst (i) = 0 is output. The i of the end instruction flag Fst represents the corresponding wheel. The brake pressure control signal will be described later.

The end instruction flag Fst (i) is set in the AND circuit 86.
Of the AND circuit 86, and the output terminal of the AND circuit 86 is connected to one input terminal of the OR circuit 87, while the vehicle speed Vb is 10 km / h at the other input terminal.
The ON signal is input at a later time. The output terminal of the OR circuit 87 is connected to the reset terminal R of the flip-flop 82 described above.

The AND circuit 86 outputs the end instruction flag Fst.
When the values of (i) are all 1, the ON signal is sent to the OR circuit 87.
The OR circuit 87 supplies the ON signal to the reset terminal R of the flip-flop 82 when the ON signal is supplied to any of its input sides. In other words, the vehicle speed Vb is 10k
When it becomes slower than m / h or when the above-mentioned conditions regarding the control signal of the brake pressure are satisfied in all of the wheels,
The reset signal is supplied to the flip-flop 82.

When the flip-flop 82 receives the reset signal, the flip-flop 82 outputs a control start end flag Fymc = 0 indicating the end of control. As shown in FIG. 15, the output of the control start / end determination unit 80, that is, the control start / end flag Fymc is supplied to the brake pressure control mode determination unit 88. In this determination unit 88, the control start / end flag Fymc is output. When the value is 1, the brake pressure control mode of each wheel is determined based on the required yaw moment γd and the turning flag Fd described above.

First, based on the required moment γd from the map shown in FIG. 17, the control execution flags Fcus and Fcos for brake pressure control at US time and OS time are set as follows based on the magnitude relationship with these threshold values. Is set. US time: γd> γdus1 (= 100kgm / s), Fcus = 1 γd <γdus0 (= 80kgm / s), Fcus = 0 OS time: γd <γdos1 (= -80kgm / s), Fcos = 1 γd> γdos0 (= -60 kgm / s), Fcos = 0 Next, control execution flags Fcus, Fcos and turning flag Fd
The control mode M (i) of the brake pressure control for each wheel is selected based on the combination of FIG.
Is shown in.

In the control mode selection routine of FIG. 18, first, it is judged if the value of the turning flag Fd is 1 (step S601). If the judgment result here is true,
That is, when the vehicle is turning right, the control execution flag F
It is determined whether or not the value of cus is 1 (step S60).
2). The situation where the determination result here is true means that the US tendency of the vehicle at the time of turning is strong, the required moment γd is a large value exceeding the threshold γdus1, and the vehicle requests the turning moment. ing. In this case, the control mode M (1) of the left front wheel FWL is set to the pressure reducing mode, while the control mode M (4) of the right rear wheel RWR is set to the pressure increasing mode, and the right front wheel FWR and the left wheel The control modes M (2) and M (3) of the rear wheel RWL are set to the non-control mode (step S603).

If the determination result of step S602 is false,
It is determined whether or not the value of the control execution flag Fcos is 1 (step S604). The situation in which the determination result here is true means that the OS tendency of the vehicle at the time of turning is strong, the required moment γd is a small value less than the threshold γdos1, and the vehicle requests the restoration moment. ing. In this case, the control mode M (1) of the left front wheel FWL is set to the pressure increasing mode, while the control mode M (4) of the right rear wheel RWR is set to the pressure reducing mode, and the right front wheel F
The control modes M (2) and M (3) of WR and the left rear wheel RWL are set to the non-control mode (step S605).

The situation in which the determination results of steps S602 and S604 are both false is that neither the US tendency nor the OS tendency of the vehicle body is strong at the time of turning, so in this case, the left front wheel FWL and the right rear wheel RWR are The control modes M (1) and M (4) are both set to the holding mode, and the control modes M (2) and M (3) of the right front wheel FWR and the left rear wheel RWL are set to the non-control mode ( Step S606).

On the other hand, if the determination result of step S601 is false and the vehicle is turning left, it is determined whether the value of the control execution flag Fcus is 1 (step S6).
07). In the situation where the determination result here is true, it means that the vehicle requests the turning moment as in the case of the right turn described above. In this case, contrary to the case of the right turn, , The control mode M (2) of the right front wheel FWR is set to the pressure reducing mode, while the control mode M (3) of the left rear wheel RWL is set to the pressure increasing mode, and the left front wheel FWL and the right rear wheel R
The WR control modes M (1) and M (4) are set to the non-control mode (step S608).

If the determination result of step S607 is false,
It is determined whether or not the value of the control execution flag Fcos is 1 (step S609). If the determination result here is true, the vehicle is requesting a restoring moment, so the right front wheel FWR
The control mode M (2) of the left rear wheel RWL is set to the pressure increasing mode, while the control mode M (3) of the left rear wheel RWL is set to the pressure reducing mode, and the control mode of the left front wheel FWL and the right rear wheel RWR is set. M (1) and M (4) are set to the non-control mode (step S610).

When the determination results of steps S607 and S609 are both false, as in the case of the right turn described above, the control modes M (2) and M (3) for the right front wheel FWRL and the left rear wheel RWL are set.
Are both set to the holding mode, and the control modes M (1) and M (4) of the left front wheel FWL and the right rear wheel RWR are set to the non-control mode (step S611). The selection of the control mode M (i) described above is summarized in Table 1 below.

[0092]

[Table 1]

When the control mode M (i) for each wheel is selected as described above, the next valve control signal calculator 89 calculates each wheel based on the control mode M (i) and the required yaw moment γd. The control signals for the solenoid valves, i.e. the inlet and outlet valves 12, 13 for controlling the brake pressure of the wheel brakes of the above are calculated. Specifically, first, the hydraulic pressure in the wheel cylinder to obtain the required yaw moment,
That is, the pressure increasing / decreasing rate (gradient of pressure increasing / decreasing) with respect to the brake pressure is calculated. Then, in accordance with the calculated pressure increasing / decreasing rate, the actual brake pressure is increased by a constant amount of pressure increasing / decreasing Δ.
In order to change with P, the drive pulse of the inlet or outlet valves 12 and 13 for realizing the pressure increase / decrease amount ΔP, that is, the pulse period Tpls and the pulse width Wpls (i) of the valve control signal are calculated. The pressure increase / decrease amount ΔP is set to, for example, ± 5 kg / cm ² , but the pressure increase / decrease amount ΔP is set to ± 10 kg / cm ² only for the first time in order to ensure responsiveness. In this regard, referring to FIG. 19, it is shown that the brake pressure in the wheel cylinder is increased / decreased for each increase / decrease amount ΔP.

The inlet and outlet valves 12 and 13 are driven by receiving a valve control signal, that is, a pressure increasing pulse signal or a pressure reducing pulse signal, based on the holding mode. Is instructed every control cycle T (8 msec) of the main routine, so that the drive mode Mpls is set so that the actual driving is performed every pulse cycle Tpls.
Set (i).

The above-mentioned pulse period Tpls, pulse width Wpls (i) and drive mode Mpls (i) will be described in detail below. First, when the brake pressure in the wheel brakes of the front wheels changes by ΔPwc, the change amount ΔMz of the yaw moment of the vehicle body can be expressed by the following formula, ignoring the lateral force of the vehicle body.

ΔMz = ΔPwc × BF × TF / 2 where BF is the front brake coefficient (kg / cm ² → kg),
TF indicates the front tread. Therefore, the rate of pressure increase / decrease Rpwc (kg / cm ² / s) of the brake pressure when the required yaw moment γd is given can be expressed by the following equation.

Rpwc = 2 × γd / BF / TF On the other hand, when the pressure increase / decrease amount ΔP (5 kg / cm ² or 10 kg / cm ² ) once is fixed, the relationship between the pressure increase / decrease rate Rpwc and the pulse period Tpls. The following equation is derived from | Rpwc | = ΔP / (Tpls × T (= 8 msec)) From the above two equations, the pulse period Tpls is represented by the following equation.

Tpls = ΔP × BF × TF / (2 × T × | γd |) where 2 ≦ Tpls ≦ 12 The pulse cycle of the front and rear wheels is the pulse cycle Tpls of the front and rear wheels. . Next, pulse width Wpls
Regarding (i), it has been set in advance by an experiment, and in this experiment, the master cylinder pressure and the wheel brake pressure (brake pressure) are used as reference pressures, and in this state, the valve is driven and then the wheel brake pressure is increased or decreased. Amount ΔP
The time when a change of (5 kg / cm ² or 10 kg / cm ² ) appears is measured, and the pulse width Wpls (i) is set based on this time. Since the discharge pressure from the pump 16 or 17 described above is used for increasing the wheel brake pressure, the pulse width Wpls (i) is set in consideration of the response delay of the pump 16 or 17. Is desirable.

The drive mode Mpls (i) described above is based on the control mode M (i) and the pulse period Tpls described above, as shown in FIG.
It is set according to the setting routine shown in. In this setting routine, first, the control mode M (i) is determined (step S612). If the control mode M (i) is not controlled, the pressure increase cycle counter CNTi (i) and the pressure decrease cycle counter are determined. Both CNTd (i) are set to 0, and the non-control mode is set to the drive mode Mpls (i) (step S613).

When the control mode M (i) is the holding mode, the holding mode is set in the driving mode Mpls (i) (step S614). When the control mode M (i) is the pressure increasing mode, only the pressure increasing period counter CNTi (i) operates (step S615), and the pressure increasing period counter CNTi.
It is determined whether or not the value of (i) has reached the pulse period Tpls (step S616). Since the determination result is false at this time, it is next determined whether or not the value of the pressure increase cycle counter CNTi (i) is 0 (step S617), and the determination result here is true. Therefore, the pressure increasing mode is set to the drive mode Mpls (i) (step S618).

When the subsequent routine is repeatedly executed, the determination result of step S617 is maintained as false.
The holding mode is set to the drive mode Mpls (i) (step S619). However, with the passage of time, the determination result of step S616 becomes true, and the pressure increase cycle counter CN
When the value of Ti (i) is reset to 0 (step S62)
0) In this case, the determination result of step S617 becomes true, and the pressure increasing mode is set to the drive mode Mpls (i) (step S618). Therefore, when the control mode M (i) is the pressure increasing mode, the drive mode Mpls (i) is set to the pressure increasing mode every pulse period Tpls.

On the other hand, when the control mode M (i) is the pressure reducing mode, the steps S621 to S629 in FIG. 20 are executed in the same manner as in the pressure increasing mode, so that the drive mode Mpls. (i) is set to the pressure reduction mode for each pulse period Tpls. When the drive mode Mpls (i) and the pulse width Wpls (i) have been calculated as described above, the next pressure increase / decrease prohibition correction unit 90 (see FIG. 15) indicates that the driver is performing countersteer or excessive slip. Further, the pulse width Wpls (i) is corrected so as to prohibit the increase or decrease of the brake pressure in consideration of the control overshoot, and the details thereof are shown in the block diagram of FIG.

The pulse width Wpls (i) supplied to the pressure increase / decrease prohibition correction unit 90 is output as the pulse width Wpls1 (i) by passing through the three switches 91, 92, 93. Is the setting unit 94, 95, 96
The output is Wpls1 according to the value of the flag set in
(i) = Wpls (i) or Wpls1 (i) = 0 can be switched. In the pressure increase / decrease prohibition correction unit 90, the supplied drive mode Mpls (i) is output as it is.

First, the setting unit 94 sets the pressure increase prohibition flag Fk1 (i) during counter steering. In particular,
The setting unit 94 includes an AND circuit 97, and the AND circuit 97
The output of the circuit 97 is supplied to the switch 91,
An ON signal is supplied to each of the inputs when the corresponding condition is satisfied. Here, the input condition of each ON signal includes the case where the own wheel is the rear wheel, the case where the counter steer flag Fcs is 1, and the case where the control mode M (i) is the pressure increasing mode. There is.

Therefore, when all of the inputs of the AND circuit 97 are ON signals, the pressure increase prohibition flag Fk1 (i) = 1.
Is output. In other cases, the pressure increase prohibition flag Fk1 (i) is output.
= 0 will be output. When the switch 91 receives the pressure increase prohibition flag Fk1 (i) = 1, it is switched from the state shown in the figure, and thereby the pulse width Wpls1 (i) is set to zero. In this case, the pulse width Wpls (i) may be decreased instead of 0.

FIG. 22 shows a routine for setting the pressure increase prohibition flag Fk1 (i). In this routine, the pressure increase prohibition flag Fk1 (i) is set only when all the determination results of steps S627 to S631 are true. ) Is set to 1. In step S630, i represents the numerical value for distinguishing the wheels as described above, and when i is 3 or 4, the wheel is a rear wheel.

In the setting section 95, the pressure increase prohibition flag Fk2 (i) at the time of excessive slip is set. Here again, the setting unit 95
Includes an AND circuit 98, the output of the AND circuit 98 is supplied to the switch 92, and an ON signal is supplied to each input of the switch 92 when a corresponding condition is satisfied. . The input condition of the ON signal here is that the slip ratio Sl (i) is the allowable slip ratio Slmax.
It is larger than (i) and the control mode M (i) is the pressure increasing mode.

The AND circuit 98 outputs the pressure increase prohibition flag Fk2 (i) = 1 when all of its inputs are ON signals, and outputs the pressure increase prohibition flag Fk2 (i) = 0 otherwise. Will be output. The switch 92 has a pressure increase prohibition flag F.
When k2 (i) = 1 is received, the state shown in the figure is switched, and in this case as well, the pulse width Wpls1 (i) is set to zero. In this case, the pulse width Wpls (i) may be decreased instead of 0.

Referring to FIG. 23, the pressure increase prohibition flag Fk2
Detailed routine showing the setting procedure of (i) is shown,
In this setting routine, first, it is determined whether or not the value of the control start / end flag Fymc is 1, that is, whether or not the yaw moment control is being performed (step S634),
If the determination result here is true, it is determined whether or not the ABS control is operating for the wheel (pressure-increasing wheel) whose control mode M (i) is in the pressure-increasing mode (step S63).
Five). A flag Fabs (i), which will be described later, is used for the determination here, and therefore the flag Fabs (i) is set in the setting unit 95 of FIG.
Is also supplied.

If the determination result in step S635 is true, the determination slip ratio of the pressure-increasing wheel at the time when the ABS control is started is held as Slst (i) (step S636), and then the next Step S638 is executed. On the other hand, if the determination result of step S635 is false, step S638 is executed without executing step S636. The ABS control will be described later.

On the other hand, if the determination result of step S634 is false, that is, if the yaw moment control is not being performed, the determination slip ratio Slst is reset to 0 (step S637), and then step S638 is executed. . Step S
At 638, it is judged if the judgment slip ratio Slst (i) is 0, and if the judgment result here is false, that is, if the ABS control is not operating for the pressure-increasing wheels, The allowable slip rate Slmax (i) is calculated (step S63).
9). Specifically, the allowable slip ratio Slmax (i) is calculated as shown in FIG.
The yaw moment γd is read from the map as shown in FIG. Here, the allowable slip ratio Slmax (i)
As is clear from FIG. 24, the required yaw moment γd
Has the characteristic of increasing at a predetermined rate as
The maximum value is set to 20%.

In the next step S641, the slip ratio Sl
It is determined whether or not (i) is larger than the allowable slip ratio Slmax (i). If the determination result here is true, the pressure increase prohibition flag Fk2 (i) is set to 1 (step S642), and If the determination result is false, 0 is set to the pressure increase prohibition flag Fk2 (i) (step S643). On the other hand, if the determination result of step S638 is true, that is, if the ABS control is operating for the pressure-increasing wheels, the allowable slip ratio S
The map used to read lmax (i) is modified (step S640). Specifically, in step S640, the map shown in FIG. 24 is replaced with the map shown in FIG.
In this case, as is apparent from FIG. 25, the maximum value of the permissible slip rate Slmax (i) is the determined slip rate Slst (i).
(Or 95% of Slst (i)), and the increasing gradient is also changed according to the determination slip rate Slst (i).

Therefore, when the ABS control is operating for the pressure-increasing wheel, the allowable slip ratio Slmax (i)
Is set to the determination slip ratio Slst (i), the determination result in step S641 becomes true, and the pressure increase prohibition flag Fk2 (i) is maintained at 1. Setting unit 9
6 (see FIG. 21), when the condition that the absolute value of the required yaw moment γd tends to decrease by a predetermined value or more is satisfied, a prevention flag Fk3 = that prevents control overshoot.
1 is output to the switch 93, and when the condition is not satisfied, the prevention flag Fk3 = 0 is output to the switch 93.
Also here, when the prevention flag Fk3 = 1 is supplied to the switch 93, the switch 93 is switched and the pulse width Wpl
Set 0 to s1 (i).

Referring to FIG. 26, there is shown a detailed routine showing the procedure for setting the prevention flag Fk3. In this setting routine, first, the required yaw moment γd is read (step S644), and the required yaw moment is then read. A value Dγd obtained by differentiating the absolute value of γd is calculated (step S645). Further, the differential value Dγd is filtered (fc = 2 Hz) (step S646).

The processing in steps S645 and S646 can be expressed by the following equation. Dγd = LPF (| γd | − | γdm |) γdm: Previous value Next, the differential value Dγd is the overshoot determination value Dγov
(For example, -125 kgm / s ² ), that is, the negative change gradient of the absolute value of the required yaw moment γd is the judgment value D.
It is determined whether or not it is larger than γov (step S64
7) If the determination result here is true, the prevention flag Fk3
Is set to 1 (step S648), and conversely, if the determination result is false, 0 is set to the prevention flag Fk3 (step S649).

As a result, the differential value Dγd is smaller than the overshoot determination value Dγov (for example, -125 kgm / s2),
That is, the absolute value of the required yaw moment γd is the judgment value Dγov
Pulse width Wpls1
(i) is set to 0, and at this time, the brake pressure in the wheel cylinder is kept constant without increasing or decreasing. Therefore, the excessive increase or decrease of the brake pressure is suppressed, and even if the required yaw moment γd is further reduced, no extra braking force is generated, and the overshoot of the yaw moment control is favorably prevented. .

The graph of FIG. 27 shows the change over time of the required yaw moment γd and the brake pressure during pressure increase. As indicated by the solid line in the figure, when the yaw moment control is started, the brake pressure increases as the required yaw moment γd increases, and the required yaw moment γd turns to decrease accordingly. At this time, the overshoot is prevented when the differential value Dγd of the required yaw moment γd reaches the determination value Dγov, and the brake pressure is kept constant. This constant brake pressure is maintained until the required yaw moment γd increases again.

The prevention of this overshoot is repeatedly performed as long as the differential value Dγd of the required yaw moment γd becomes smaller than the judgment value Dγov, whereby the required yaw moment γd is well damped in a short time. Then
Suitable yaw moment control will be realized. For reference, in the figure, the dashed line also shows the required yaw moment γd when the overshoot prevention is not implemented and the change over time in the brake pressure during pressure increase. If this is not done, the brake pressure will not follow the required yaw moment γd with good response and will overshoot and hunting will occur. Therefore, in this case, the required yaw moment γd continues to vibrate, and good yaw moment control cannot be realized.

Referring again to FIG. 15, the block diagram of the yaw moment control includes the preload control determination unit 100. In this determination unit 100, prior to the start of the yaw moment control, the pumps 16, 17 and the inlets are controlled. The preload flags Fpre1 and Fpre2 for controlling the operation of the outlet valves 12 and 13 and the cutoff valves 19 and 20 are set.
Specifically, when the absolute value of the required yaw moment becomes larger than a predetermined value or the maximum yaw rate deviation Δγmax becomes larger than a predetermined value and the yaw moment control is started, the preload flag Fpre1 = 1 or Fpr
When e2 = 1 is set for a fixed duration (for example, 96 msec), and the yaw moment control is started during the duration, the preload flag Fpre1 or Fpre2 is reset to 0 at the start time. The preload flag Fpre1 = 1 is set when the vehicle turns right, while the preload flag Fpre2 is set when the vehicle turns left. Further, FIG. 15 includes a control signal compulsory changing unit 111, and the details of the compulsory changing unit 111 are shown in FIG. Forced change section 1
In 11, the pulse width Wpls (i) and the drive mode Mpls (i) can be forcibly changed according to various situations, and the pulse width Wpls (i) and the drive mode Mpls (i) can be forcibly changed.
After passing 11, pulse width Wy (i) and drive mode My
It is output as (i).

As is apparent from FIG. 28, the drive mode Mpl
s (i) passes through the switches 112 to 117 to drive mode My.
(i), the switches 112 to 117 are supplied with a flag and are switched according to the value of the flag.
That is, the switch 112 is the non-control diagonal hold determination unit 1
It is switched by a flag Fhld (i) output from 18, and the determination unit 118 determines that the vehicle is not being braked (Fb =
0) and the pumps 16 and 17 are operating (when the motor drive flag Fmtr = 1 described later), the flag Fhld (i) corresponding to the wheel in the non-control mode is set to 1. Therefore, in this case, the switch 112 outputs the drive mode Mpls1 (i) in which the wheels in the non-control mode in the drive mode Mpls (i) are forcibly switched to the holding mode, while the flag Fhld (i) is output. = 0, drive mode Mpls (i)
Is output as is. In the drive mode Wpls1 (i), the uncontrolled wheel is forcibly switched to the holding mode, so that the discharge pressure from the pumps 16 and 17 is not supplied to the wheel brake of that wheel. .

The switch 113 has a termination control determination section 119.
It is switched by an end flag Ffin (i) output from the determination unit 119, and in the determination unit 119, a predetermined period (for example, 40 msec) is maintained for a fixed period (for example, 340 msec) after the end of yaw moment control (Fymc = 0). Therefore, the end flag Ffin (i) is set to 1 for a predetermined time (for example, 16 msec). The end flag Ffin (i) is also used for opening / closing control of the cutoff valves 19 and 20 as described later.

When the end flag Ffin (i) = 1 is supplied,
The switch 113 is a drive mode Mpls2 that switches the wheels that were the control target to the holding mode during the drive mode Mpls (i).
(i) is output. On the other hand, when the flag Ffin = 0, the drive mode Mpls (i) is output as it is. Thus, after the end of the yaw moment control, when the drive mode of the wheel that was the control target is periodically switched to the holding mode, the brake pressure of the control target wheel does not change suddenly,
The behavior of the vehicle can be stabilized.

The switch 114 is switched by the preload flags Fpre1 and Fpre2 output from the preload control determination unit 100, and these preload flags Fpre1 = 1 or Fpr.
When e2 = 1 is received, the switch 114 switches the drive mode Mpl.
During s (i), the drive mode Mpls3 (i) in which the wheel to be controlled is forcibly switched to the holding mode is output, and Fpre1 = Fpre
When 2 = 0, the drive mode Mpls (i) is output as it is. Here, in the above description regarding FIG. 15, the control mode M (i) and the drive mode Mpls (i) are received in response to the output of the control start / end flag Fymc = 1 from the control start / end determination unit 80.
However, the control mode M (i) and the drive mode Mpls (i) are set regardless of the control start / end flag Fymc. Therefore, even if the drive mode Mpls (i) is set to the drive mode Mpls3 (i) and the above-mentioned preload control is started, the brake pressure of the wheel to be controlled is adversely affected before the yaw moment control is started. There is no such thing.

The switch 115 is used for the pedal release determining section 12
It is switched by the release flag Frp output from 0,
The determination unit 120 sets the release flag Frp to 1 for a predetermined time (for example, 64 msec) when the brake pedal 3 is released during the yaw moment control during braking. Release flag Frp
= 1 is received, the switch 115 drives the drive mode Mpls.
In (i), the drive mode Mpls4 (i) for forcibly reducing the brake pressure of the wheel in the pressure reduction mode is output, and the release flag Frp is output.
When = 0, the drive mode Mpls (i) is output as it is.

The release flag Frp is also supplied to the switch 121. When Frp = 1, the switch 121 forcibly changes the value of the pulse width Wpls (i) to the control cycle T (= 8 msec). (i) is output, and when Frp = 0, the pulse width Wpls (i) is output as it is as the pulse width Wy (i). The switch 116 is switched by the additional pedal flag Fpp output from the pedal additional pedal determination unit 122,
The step-up flag Fpp is set as described above according to the routine of FIG. When Fpp = 1 is received, the switch 116 forces the drive mode M to switch all the wheels to the non-control mode instead of the drive mode Mpls (i).
If pls5 (i) is output and Fpp = 0, drive mode Mpls
Output (i) as it is. When the drive mode is set to Mpls5 (i), the brake pedal operation by the driver can be reflected in the brake pressure of each wheel.

The switch 117 is switched by the reverse flag Frev output from the reverse determination unit 123, and the determination unit 123 sets the reverse flag Frev to 1 when the reverse gear is selected in the transmission of the vehicle, In other cases, the backward movement flag Frev is set to 0. Flag Fr
Upon receiving ev = 1, the switch 117 switches the drive mode M
Instead of pls (i), the drive mode My (i) for forcibly switching all the wheels to the non-control mode is output, and when Frev = 0, the drive mode Mpls (i) is set to the drive mode My (i). Output as.

As shown in FIG. 15, the output from the control signal compulsory changing unit 111, that is, the drive mode My (i) and the flag from the preload control determining unit 100 are the drive determining unit 1
24, and details of the drive determination unit 124 are shown in FIGS. 29 to 32. First, in the determination circuit 125 shown in FIG. 29, a flag requesting driving of the cutoff valves 19 and 20 and the motor 18 is set for each wheel cylinder of each wheel.

The determination circuit 125 includes two AND circuits 12
6, 127, one of the AND circuits 126 has its input at the brake flag Fb = 1 and the drive mode My (i).
Is in the pressure increasing mode, the pressure increasing mode i is output to the OR circuit 128. When the input of the other AND circuit 127 is the brake flag Fb = 0 and the drive mode My (i) is in the non-control mode, i which is not in the non-control mode is set to O.
Output to the R circuit 128. That is, the drive mode side input of the AND circuit 127 is supplied via the NOT circuit 129.

The OR circuit 128 is composed of AND circuits 126, 1
When the output from 27 is received, the value of the request flag Fmon (i) corresponding to the received i among the request flags Fmon (i) requesting the driving of the motor 18 is set to 1 and output. Also,
The output of the OR circuit 128 is also supplied to the set terminal of the flip-flop 130, and the reset terminal receives a reset signal for each i when the drive mode My (i) is uncontrolled. ing.

When the request flag Fmon (i) = 1 is supplied to the set terminal of the flip-flop 130, the flip-flop 130 requests the request flag Fcov (i) for driving the cutoff valves 19 and 20. Flag Fmon (i) =
The value of the request flag Fcov (i) corresponding to i of 1 is continuously output as 1 and when the reset signal is received, the values of all the request flags Fcov (i) are reset to 0.

Next, the judgment circuit 131 of FIG. 30 is provided with an OR circuit 132, and this OR circuit 132 is a request flag Fcov (1) related to the cutoff valve 19 on the left front wheel FWL and right rear wheel RWR which is the input thereof. ), Fcov (4), the end flags Ffin (1), Ffin (4), and the preload flag Fpre1 are set to 1, the value of the cut drive flag Fvd1 for driving the cutoff valve 19 is set to Output as 1.

Cut drive flag F from the OR circuit 132
vd1 is further output via the switches 133 and 134,
Here, the switch 133 is switched by the step-up flag Fpp, and the switch 134 is switched by the reverse flag Frev. That is, even if the output of the OR circuit 132 is Fvd1 = 1, the cut drive flag Fvd1 is reset to 0 (non-control mode) when one of the step-up flag Fpp and the backward movement flag Frev is set to 1. .

The determination circuit 135 of FIG. 31 has the same configuration and function as the determination circuit 131 of FIG. 30, but the OR circuit 136 has the cut-off valve 20 on the right front wheel FWR and left rear wheel FWL side. Request flags for Fcov (2), Fco
v (3), end flag Ffin (2), Ffin (3), preload flag Fpre2
In this case, the OR circuit 136 outputs the cut drive flag Fvd2 for driving the cutoff valve 20 via the switches 137 and 138, unlike the determination circuit 131 in that the input is input.

The determination circuit of FIG. 32, that is, the OR circuit 139.
When the value of the request flag Fmon (i) for each wheel requesting the drive of the motor 18 or the value of the preload flag Fpre1 or Fpre2 indicating that the preload control is in operation is 1, , And sets the value of the motor drive flag Fmtr to 1 and outputs. : ABS coordinate control: In the yaw moment control described above, the drive mode My
When (i), the pulse width Wy (i), the cut drive flags Fvd1 and Fvd2, and the motor drive flag Fmtr are set, cooperative control with the ABS control is performed (the determination unit 78a in FIG. 3 and the steps in FIG. 4). (See S7).

If the ABS control is activated, the ABS
Since the yaw moment control is executed in coordination with the control,
In the BS coordinated control, the drive mode Mabs (i) and the pulse width Wabs (i) of each wheel in consideration of the ABS control are set. Here, detailed description on the setting of the drive mode Mabs (i) and the pulse width Wabs (i) is omitted, but the drive mode Mabs (i) and the pulse width Wabs (i) are also increased / decreased as described above. It should be noted that the functions of the pressure inhibition correction unit 90 (see FIG. 21) and the control signal forced change unit 111 (see FIG. 28) are reflected.

However, to explain one function of the ABS coordinated control, when the vehicle is in a situation requiring a turning or a restoring moment at the time of turning during the ABS control, the AB
In S coordinated control, drive mode Mabs (i) and pulse width Wabs
(i) is set as follows. That is, the ABS of FIG.
As shown in the cooperation routine, in step S701, it is determined whether the ABS control is operating. It should be noted that the determination here is made based on whether or not the flag Fabs (i) indicating each wheel during the operation of the ABS control is 1.
The flag Fabs (i) is set in an ABS control routine (not shown) based on the changing tendency of the slip ratio of the wheel as is known.

If the determination result of step S701 is true,
It is determined whether or not the control execution flag Fcus or Fcos is 1 (step S702), and if the determination result here is true, that is, the vehicle requests the turning or restoring moment when turning. In such a situation, in the next step S703, the drive mode Mabs (i) and the pulse width Wabs (i)
Is set as follows.

When the yaw moment control is executed for the diagonal wheels: 1) In order to further obtain the turning moment, the front wheel FW, which is the inner side in the turning direction, is set to the pressure reduction mode, and its pulse width is set to the outer side. It is set to be the same as the pulse width of the front wheels FW. 2) In order to further obtain the restoring moment, the rear wheel RW, which is the outer side in the turning direction, is set to the decompression mode, and its pulse width is set to be the same as the pulse width of the inner rear wheel.

The yaw moment control can be executed not only on the diagonal wheels but also between the front and rear wheels. That is, when the yaw moment control is executed based on the braking force difference between the left and right wheels, the braking force of the outer wheels is set to the pressure increasing mode and the braking force of the inner wheels is set to the depressurizing mode to generate a restoring moment in the vehicle. On the other hand, if the braking force of the outer wheels is set to the pressure reducing mode and the braking force of the inner wheels is set to the pressure increasing mode, a turning moment can be generated in the vehicle.

Therefore, when the yaw moment control is executed between the left and right rear wheels, in order to further obtain the turning moment, the outer front wheel is set to the decompression mode and its pulse width is set to that of the outer rear wheel. Set the same as the pulse width. On the other hand, when yaw moment control is executed between the left and right front wheels, in order to further obtain the restoring moment, the inner rear wheel is set to the decompression mode, and its pulse width is set to the pulse width of the inner front wheel. Set the same as.

On the other hand, if the determination result in any of steps S701 and S702 is false, this routine is terminated without executing step S703. : Control signal selection: Coordination routine with ABS control, that is, when step S7 is exited in FIG. 4, the control signal selection routine is executed in the next step S8, and the selection circuit 140 for executing this routine is shown in FIG. It is shown. It should be noted that in FIG. 34, a block 141 for executing the routine of FIG.
142 is also shown.

The selection circuit 140 includes four switches 143 ...
The switch 143 has a block 1
The drive mode Mabs (i) after passing 41 and the drive mode My (i) set by the yaw moment control described above are input, and the switch 144 passes through the block 142. The subsequent pulse width Wabs (i) and the pulse width Wy (i) set by the yaw moment control are input.

The cut drive flags Fvd1 and Fvd2 set by the yaw moment control and 0 for resetting these flags are input to the switch 145. The motor drive flag Fmtr set by the yaw moment control is set in the switch 146 by the OR circuit 14.
7, the motor drive flag Fmabs during ABS control is also input, and the motor drive flag Fmabs is also supplied to the other input terminal of the OR circuit 147. The motor drive flag F
mabs is a flag set by the ABS control itself, and is set to Fmabs = 1 when the ABS control is started.

The switches 143 to 146 described above are switched in response to the result of the flag output from the determination section 148. That is, the determination unit 148 includes an OR circuit 149. The input of the OR circuit 149 is when the three or more wheels are in the ABS control or the drive mode My (i) in the yaw moment control is not the pressure reduction mode. AND the flag Fmy (i) = 1 corresponding to the wheel in the decompression mode
Output to the circuit 150. When three or more wheels are under ABS control, the flag Fabs3 = 1 is supplied to the switches 145 and 146.

Further, the drive mode Mabs (i) = 1 is input to the AND circuit 150 when the drive mode Mabs (i) in the ABS cooperative control is not the non-control mode, and AND
From the circuit 150, its input flags Fmy (i) and Mabs
In (i), the flag Fm # a (i) having the same i number is set to 1 and output to the switches 143 and 144, respectively.

If three or more wheels of the vehicle are under ABS control,
Since the flag Fabs3 = 1 is supplied from the determination unit 148 to the switches 145 and 146, respectively, the switch 14
5 is the cut drive flags Fvd1 and Fvd2, that is, Fv1 = F
v2 = 1 is output, and the switch 146 sets the motor drive flag F.
Output mabs as Fm. On the other hand, the switch 14
When the flag Fabs3 = 0 is supplied to 5 and 146, the switch 145 outputs the cut drive flags Fvd1 and Fvd2 as Fv1 and Fv2, respectively, and the switch 146 outputs the motor drive flag Fmtr as Fm. Here, the motor drive flag Fmabs is set to the switch 146 via the OR circuit 147.
Therefore, regardless of the switching of the switch 146, the motor drive flag Fm = 1 is output from the switch 146 when either of the motor drive flags Fmabs and Fmtr is set to 1. Become.

On the other hand, when the input condition of the AND circuit 150 is satisfied, the AND circuit 150 causes the switch 143,
The flag Fm # a (i) = 1 is supplied to 144, and in this case, the switch 143 changes the drive mode Mabs (i) to the drive mode MM.
(i), and the switch 144 outputs the pulse width Wabs (i).
Is output as the pulse width WW (i). On the other hand, when the flag Fm # a (i) = 0 is supplied to the switches 134 and 144, the switch 143 outputs the drive mode My (i) as the drive mode MM (i), and the switch 144. The pulse width Wy (i) is output as the pulse width WW (i).

Drive signal initialization: When the drive mode MM (i) and the pulse width WW (i) are output from the control signal selection circuit 140, these are shown in FIG. 3 as the drive signal initialization unit 151 and FIG. Then, in step S9, the actual drive mode Mexe (i) and the actual pulse width Wexe (i) are set, and initial values are given to the actual drive mode Mexe (i) and the actual pulse width Wexe (i).

Step S9 is shown in detail in FIG. 35. Here, first, after the interrupt prohibiting process is executed (step S901), the drive mode MM (i) is determined (step S902). If the determination result of step S902 is the non-control mode, the pressure increasing mode is set to the actual drive mode Mexe (i), and the control cycle T (= 8 msec) of the main routine is set to the actual pulse width Wexe (i). Is set (step S90
3) Then, after the interrupt permission process is executed (step S904), the routine here ends.

If the result of the determination in step S902 is the pressure increasing mode, it is determined whether or not the actual drive mode Mexe (i) is the pressure increasing mode (step S905). However, since the actual drive mode Mexe (i) has not yet been set at this point, the result is false, and in this case, the actual drive mode Mexe (i) is changed to the drive mode MM (i), that is, the pressure increase. After the mode is set and the actual pulse width Wexe (i) is set to the pulse width WW (i) (step S906), this routine ends after step S904.

If the determination result of step S902 is maintained in the pressure increase mode even when the next routine is executed, in this case, the determination result of step S905 becomes true and the pulse width WW (i) is It is determined whether or not the actual pulse width Wexe (i) is smaller than that (step S907). Here, the pulse width WW (i) is newly set for each control cycle T, as is clear from the fact that the main routine is executed for each control cycle T, but the actual pulse width Wexe (i) will be described later. When the inlet or outlet valve is actually driven, the amount decreases with the driving. Therefore, according to the determination result in step S907, the newly set pulse width WW (i) is the remaining actual pulse width at this moment. If it is longer than Wexe (i), a new pulse width WW (i) is set to the actual pulse width Wexe (i) (step S908). However, when the determination result of step S907 is false, the remaining actual pulse width Wexe (i) is maintained without resetting the new pulse WW (i) to the actual pulse width Wexe (i). .

On the other hand, if the result of the determination in step S902 is the pressure reducing mode, steps S909 to S912 are executed, and in the same manner as in the pressure increasing mode, the actual drive mode Mexe (i) and The actual pulse width Wexe (i) is set. Further, when the determination result of step S902 is the pressure reduction mode, the holding mode is set to the actual drive mode Mexe (i) (step S913).

Drive signal output: When the actual drive mode Mexe (i) and the actual pulse width W (i) are set as described above, these are changed from the drive signal initial setting unit 151 to the valve drive unit 152 in FIG. Is output to step S10 in the main routine of FIG. In step S10, in addition to the actual drive mode Mexe (i) and the actual pulse width Wexe (i), based on the cut drive flags Fv1, Fv2 and the motor drive flag Fm set by the control signal selection routine, the cutoff valve Drive signals for driving 19, 20 and the motor 18 are also output.

Here, the cut drive flag Fv1 is Fv1 = 1.
In the case of, a drive signal for closing the cutoff valve 19 is output, and when the cut drive flag Fv2 is Fv2 = 1, a drive signal for closing the cutoff valve 20 is output. On the other hand, when the cut drive flags Fv1 and Fv2 are reset to 0, the cutoff valves 19 and 20 are cut off.
Is kept open. On the other hand, the motor drive flag Fm
When Fm = 1, a drive signal for driving the motor 18 is output, and when Fm = 0, the motor 18 is not driven.

Driving the inlet and outlet valves: When the actual drive mode Mexe (i) and the actual pulse width Wexe (i) are supplied to the valve drive unit 152, the valve drive unit 152 drives as shown in FIG. The inlet and outlet valves 12, 13 are driven according to a routine. Here, the drive routine of FIG. 36 is executed independently of the main routine of FIG. 4, and its execution cycle is 1 msec.

In the drive routine, first, the actual drive mode Mexe (i) is discriminated (step S1001). If the actual drive mode Mexe (i) is the pressure increasing mode in this discrimination, It is determined whether or not the actual pulse width Wexe (i) is larger than 0 (step S1002). If the determination result here is true, the inlet and outlet valves corresponding to the wheel + 1
For 2 and 13, the inlet valve is opened while the outlet valve 13 is closed and the actual pulse width Wexe (i)
Is reduced by its execution cycle (step S1003). Therefore, when step S1003 is performed, the motor 18 is already driven and the corresponding cutoff valve 19
Alternatively, if 20 is closed, the wheel brake corresponding to the wheel will be boosted.

When the actual driving mode Mexe (i) is maintained in the pressure increasing mode, the driving routine is repeatedly executed, and when the determination result of step S1002 becomes false,
At this point, the corresponding inlet and outlet valve 1 for that wheel
For 2 and 13, both the inlet and outlet valves are closed, and the actual drive mode Mexe (i) is set to the hold mode (step S1004).

If it is determined in step S1001 that the actual drive mode Mexe (i) is the pressure reducing mode, it is again determined whether the actual pulse width Wexe (i) is greater than zero. (Step S1005). If the determination result here is true, the inlet and outlet valves 12, 13 corresponding to the wheels are
Regarding, regarding the inlet valve, the outlet valve 13 is opened while the outlet valve 13 is opened, and the actual pulse width Wexe (i) is decreased by its execution period (step S1006). Therefore, by executing step S1006, the wheel brakes corresponding to the wheels are depressurized.

Also in this case, when the drive routine is repeatedly executed in the state where the actual drive mode Mexe (i) is maintained in the pressure reduction mode, and the determination result of step S1005 becomes false, at this point, Regarding the inlet and outlet valves 12 and 13 corresponding to the wheel, both the inlet and outlet valves are closed, and the actual drive mode Mexe (i) is set to the holding mode (step S1007).

If it is determined in step S1001 that the actual drive mode Mexe (i) is the holding mode, both the inlet and outlet valves 12 and 13 corresponding to that wheel are closed (step S1008). . Referring to FIG. 37, a time chart shows the relationship among the drive mode MM (i), the pulse width WW (i), the actual drive mode Mexe (i), and the actual pulse width Wexe (i) described above.

Action of Yaw Moment Control: Diagonal Wheel Control: It is assumed that the vehicle is currently running and the main routine of FIG. 4 is repeatedly executed. In this state, in step S3 of the main routine, that is, in the turning determination routine of FIG. 8, if the turning flag Fd indicating turning of the vehicle from the steering wheel angle θ and the yaw rate γ is set to Fd = 1, in this case, The vehicle is making a right turn.

During right turn: After this, the required yaw moment γd is obtained through steps S4 and S5 of the main routine, and when the yaw moment control in step S6 is executed, the control is started in this yaw moment control. The control mode selection routine is executed on condition that the end flag Fymc (see the determination circuit in FIG. 16) is Fymc = 1, and the control mode M (i) for each wheel is set according to the selection routine in FIG. It

Since it is assumed here that the vehicle is turning to the right, step S601 in the selection routine of FIG.
The determination result of is true, and steps after step S602 are performed. Right turn of US tendency: In this case, if the determination result of step S602 is true, that is, the control execution flag Fcus is Fcus = 1 and the vehicle has a strong US tendency, the left front wheel (outer front wheel) ) The control mode M (1) of the FWL is set to the pressure reducing mode, the control mode M (4) of the right rear wheel (inner rear wheel) RWR is set to the pressure increasing mode, and the control of the other two wheels is performed. The modes M (2) and M (3) are set to the non-control mode (see Table 1 and step S603).

Thereafter, the drive mode Mpls (i) is set as described above based on the control mode M (i) of each wheel and the required yaw moment γd (see the setting routine of FIG. 20), and each wheel is also set. Each pulse width Wpls (i) is set. Then, these drive modes Mpls (i) and pulse width W
pls (i) becomes the drive mode My (i) and the pulse width Wy (i) through the pressure increase prohibition correction unit 90 and the control signal forced change unit 111 in FIG.

On the other hand, in the drive determination section 124 of FIG. 15, that is, the determination circuits of FIGS. 29 to 32, in the determination circuit 125 of FIG. 29, the brake flag Fb is Fb = 1 (during braking) and the drive mode My (i ) Is in the pressure increasing mode, a request flag Fmon (i) for each wheel requesting the drive of the motor 18 via the AND circuit 126 and the OR circuit 128, and a cutoff valve 19, via the flip-flop 130. Request flag Fcov for each wheel that requires 20 drives
(i) is set to 1, respectively.

Specifically, as described above, in the situation where the brake pedal 3 is stepped on during a right turn having a strong US tendency, the output of the determination circuit 125 is Fmon (4) = Fcov.
(4) = 1, and the decision circuit 131 (O
The cut drive flag Fvd1 from the R circuit 132) is Fvd1 = 1.
32 is output as the judgment circuit of FIG.
The motor drive flag Fmtr is output from the circuit 139 as Fmtr = 1. Here, the request flag Fcov (2) = Fcov
Since (3) = 0, Fvd2 = 0 for the cut drive flag Fvd2 output from the determination circuit 135 (OR circuit 136) in FIG.

Therefore, at the time of braking, only one cut drive flag, in this case, Fvd1 becomes 1. Thereafter, the cut drive flag Fvd1 = 1 and the motor drive flag Fmtr = 1 are set in the control signal selection unit 140 (FIG. 34) of FIG.
Then, through the switches 145, 146), Fv1 = 1, Fv2 =
0, Fm = 1, and these flags are supplied as drive signals to the cutoff valves 19 and 20 and the motor 18. That is, in this case, the front left wheel FWL and the rear right wheel R
Cut-off valve 1 paired with WR wheel brake
Only 9 is closed, the cut-off valve 20 paired with the wheel brakes of the right front wheel FWR and the left rear wheel RWL remains open, and the motor 18 is driven. By driving the motor 18, the pressure liquid is discharged from the pumps 16 and 17.

On the other hand, in the non-braking mode in which the brake pedal 3 is not depressed, the control mode M (1) for the left front wheel FWL and the control mode M (4) for the right rear wheel RWR are not in the non-control mode. Therefore, the AND circuit 12 of the determination circuit 125
7 and the OR circuit 128, the request flag Fmon (1) = F
mon (4) = 1 is output, and Fcov (1) = Fcov (4) = 1 is output from the flip-flop 130. Therefore, also in this case, the motor drive flag Fmt
When r = 1 and the motor 18, that is, the pumps 16 and 17 are driven, and only the cut drive flag Fvd1 is set to 1, as a result, only the cutoff valve 19 is closed.

However, in the case of non-braking, when the drive mode Mpls (i) described above is processed by the control signal compulsory changing unit 111 (FIG. 15), the non-control diagonal hold determining unit is operated. Flag F, which is the output of 118 (FIG. 28)
It should be noted that since hld is set to 1, switch 112 is toggled, forcing drive mode Mpls (i) in the uncontrolled mode to hold mode.

Further, in the case of non-braking (Fb = 0), regarding the calculation of the required yaw moment γd (see FIG. 10), the correction value Cpi is set to 1.5 which is larger than 1.0 in the case of braking. Therefore, the required yaw moment γd is raised. This padding is the drive mode Mpl
Since the pulse period Tpls for executing s (i), that is, My (i) is shortened, if the drive mode My (i) is the pressure increasing mode or the pressure decreasing mode, the increase / decrease is strongly executed. It should be noted that

After that, the drive mode My (i) and the pulse width W
As described above, y (i) is set as the drive mode MM (i) and the pulse width WW (i) via the control signal selection unit 140, and based on these, the actual drive mode Mexe (i) and the actual pulse width Wexe are set. As a result of setting (i), the corresponding inlet and outlet valves 12 and 13 are driven according to the actual drive mode Mexe (i) and the actual pulse width Wexe (i) (see the drive routine in FIG. 36).

Specifically, when the vehicle is turning to the right with a strong US tendency and is braking, the wheel drive for the left front wheel FWL is a decompression mode because its actual drive mode Mexc (1) is a pressure reduction mode. As a result of closing the inlet valve 12 corresponding to and closing the outlet valve 13 (step S1006 in FIG. 36), the brake pressure of the left front wheel FWL is reduced. On the other hand, in this case, since the actual drive mode Mexe (4) is the pressure increasing mode for the wheel brake of the right rear wheel RWR, the inlet valve 12 corresponding to the wheel brake is opened and the outlet valve 13 is closed. (Step S1003 in FIG. 36). Here, at this point, the cutoff valve 19 is closed as described above,
Since the pumps 16 and 17 are driven by the motor 18, the pressure in the branch brake pipe line 8 (see FIG. 1) leading to the wheel brake of the right rear wheel RWR is independent of the master cylinder pressure. Has already been launched,
As a result, the wheel brake of the right rear wheel RWR receives the supply of the pressure fluid from the branch brake line 8 through the inlet valve 12, and as a result, the brake pressure of the right rear wheel RWR is increased.

Referring to the braking force / cornering force characteristics with respect to the slip ratio shown in FIG. 38, the wheel brake pressure, that is, the braking force Fx, is in the slip ratio range when the vehicle is in a normal running state. It can be seen that the slip ratio decreases as the braking force Fy increases, whereas the slip ratio increases as the braking force Fy increases. On the other hand, decreasing the slip ratio increases the cornering force, while increasing the slip ratio increases the cornering force. It can be seen that the force is reduced.

Therefore, as shown in FIG. 39, when the braking force Fx of the left front wheel FWL is decreased from the white arrow to the black arrow, the cornering force Fy increases from the white arrow to the black arrow. On the other hand, when the braking force Fx of the right rear wheel RWR is increased from the white arrow to the black arrow, the cornering force Fy decreases from the white arrow to the black arrow. As a result, the braking force Fx of the front left wheel FWL is reduced and the cornering force Fy is reduced.
On the other hand, since the braking force Fx of the right rear wheel RWR increases and the cornering force Fy decreases, a turning moment M (+) is generated in the turning direction of the vehicle.

Note that, in FIG. 39, hatching arrows indicate changes in braking force Fx and cornering force Fy ± ΔFx, ± Δ.
It shows Fy. Here, in the left front wheel FWL and the right rear wheel RWR, which are diagonal wheels of the vehicle, the inlet and outlet valves 12 and 13 of those wheels are the actual drive mode Mexe (i) and the actual drive mode set based on the required yaw moment γd. Since the vehicle is opened / closed in accordance with the pulse cycle Wexe (i), the turning moment M (+) can be appropriately added to the vehicle, whereby the US tendency of the vehicle can be eliminated and its drift-out can be prevented.

Here, the required yaw moment γd is calculated in consideration of the motion state and the driving operation state of the vehicle as described above (see steps S504 and S505 in the calculation routine of FIG. 11). If the braking force of the diagonal wheels is increased or decreased based on the yaw moment γd, fine yaw moment control according to the turning state of the vehicle becomes possible.

Further, in this yaw moment control, the overshoot of the brake pressure that increases the braking force Fx is suitably prevented in accordance with the decreasing tendency of the required yaw moment γd, so that the vehicle can be satisfactorily controlled to turn. become.
That is, when the brake pressure supplied to the wheel brakes of the diagonal wheels is increased or decreased based on the required yaw moment γd, hunting due to overshoot of the brake pressure is suitably prevented, which results in unstable turning of the vehicle. The behavior recovers more quickly and smoothly, enabling extremely stable turning of the vehicle.

OS-oriented right turn: In the control mode selection routine of FIG. 18, the determination result of step S602 is false and the determination result of step S604 is true, that is, Fcos = 1, and the OS tendency of the vehicle is strong. If so, left front wheel F
This is different from the US tendency only in that the control mode M (1) of WL is set to the pressure increasing mode and the control mode M (4) of the right rear wheel RWR is set to the pressure reducing mode (Table 1 And step S605).

Here, when the vehicle is being braked, FIG.
As shown in Fig. 5, the braking force Fx of the left front wheel FWL increases while the cornering force Fy decreases, while the braking force Fx of the right rear wheel RWR decreases while the cornering force Fy increases. Therefore, in this case, the restoring moment M (-) is applied to the vehicle.
Occurs. This restoring moment M (-) cancels the OS tendency of the vehicle, whereby the spin of the vehicle due to the tuck-in can be surely avoided.

Left turn: When the yaw moment control in the left turn is executed with the above-described turn flag Fd and the control start / end flag Fymc set to Fd = 0 and Fymc = 1, the right turn described above is performed again. Similarly to the case, when the vehicle tends to have a strong US tendency, a turning moment M (+) is generated. On the other hand, when the OS tendency is strong, a right front wheel is generated to generate a restoring moment M (-). The brake pressures of the FWR and the left rear wheel RWL are controlled, and as a result, the same effect as in the case of a right turn can be obtained (see Table 1 and steps S607 to S611 in FIG. 18, and the drive routine in FIG. 36).

In the above embodiment, when performing the yaw moment control, the required yaw moment γd is calculated based on the information from the yaw rate sensor 30, and the yaw rate feedback control is performed by using the yaw rate feedback control.
It is also possible to perform open control according to y, the vehicle speed V and the steering angle δ.

[0182]

As described above, according to the vehicle turning control device of the first aspect, the required control amount for controlling the yaw moment of the vehicle is set according to the driving state of the vehicle and / or the behavior of the vehicle. In a vehicle turning control device including a control means for controlling a yaw motion of a vehicle by generating a braking force difference between two or more predetermined wheels based on the required control amount, when the absolute value of the required control amount tends to decrease. Since the control means for restricting the control of the yaw motion is provided, it is possible to appropriately stop the supply of the brake pressure to the wheel brakes provided on the wheels according to the required control amount, and it is difficult to follow the control signal. It is possible to suitably prevent the overshoot of the supply brake pressure that occurs due to the yaw motion control, that is, to perform the turning control of the vehicle.

Further, according to the vehicle turning control device of the second aspect, the regulation means includes the determination means for determining that the time differential value of the absolute value of the required control amount is less than or equal to the predetermined value. Therefore, it is possible to always reliably and satisfactorily determine the decreasing tendency of the absolute value of the required control amount, and to perform the turning control of the vehicle in a good condition. Further, according to the vehicle turning control device of the third aspect, the regulating means includes the retaining means for retaining each braking force of the predetermined wheel when the absolute value of the required control amount tends to decrease. Is preferably prevented, and good yaw motion control, that is, turning control of the vehicle can be performed.

According to the vehicle turning control device of the fourth aspect, the control means sets the required control amount based on the yaw rate detecting means for detecting the yaw rate of the vehicle and the actual yaw rate detected by the yaw rate detecting means. Since the yawing motion, that is, the yaw motion of the vehicle can be directly detected, the turning control of the vehicle can be performed more accurately.

According to another aspect of the vehicle turning control device of the present invention, the control means includes target yaw rate setting means for setting the target yaw rate of the vehicle, and the setting means determines the yaw rate deviation between the actual yaw rate and the target yaw rate. Since the required control amount is set based on the time differential value of the yaw rate deviation, the precision of the required control amount can be increased, and a better and more accurate vehicle turning control can be implemented.

Further, according to the vehicle turning control device of the sixth aspect, the control means sets only the front outer wheel and the rear inner wheel as control target wheels in the turning direction during turning braking of the vehicle, based on the required control amount. , Because the braking force of one wheel is increased and the braking force of the other wheel is decreased,
The yaw motion control during turning and braking can be extremely effectively performed, and more suitable turning control of the vehicle can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a brake system that executes yaw moment control.

FIG. 2 is a diagram showing a connection relationship between various sensors and an HU (hydro unit) with respect to an ECU (electronic control unit) in the brake system of FIG.

FIG. 3 is a functional block diagram schematically illustrating a function of an ECU.

FIG. 4 is a flowchart showing a main routine executed by the ECU.

FIG. 5 is a steering wheel angle θ when the steering wheel is operated.
It is a graph showing the change over time.

FIG. 6 is a flowchart showing a brake pedal further depression flag setting routine which is a part of step S2 of FIG. 4;

7 is a block diagram showing details of a turning determination unit in FIG.

FIG. 8 is a flowchart showing details of a turning determination routine executed by a turning determination unit in FIG.

9 is a block diagram showing details of a target yaw rate calculation unit in FIG.

10 is a block diagram showing details of a required yaw moment calculation unit in FIG.

FIG. 11 is a flowchart showing a required yaw moment calculation routine.

FIG. 12 is a block diagram for obtaining a proportional gain Kp by calculating a required yaw moment.

FIG. 13 is a diagram for explaining the turning behavior of the vehicle body with respect to the center-of-gravity slip angle β when the vehicle turns.

FIG. 14 is a block diagram for obtaining the integral gain Ki in the calculation of the required yaw moment.

15 is a block diagram showing details of a yaw moment control unit in FIG.

16 is a block diagram showing details of a control start / end determination unit in FIG.

FIG. 17 is a graph showing setting criteria of control execution flags Fcus and Fcos with respect to the magnitude of the required yaw moment.

FIG. 18 is a flowchart showing a control mode selection routine.

19 is a control mode M (i), a drive mode Mpls (i), and a pulse width Wpls (i) set in the selection routine of FIG.
It is a time chart showing the relationship with.

FIG. 20 is a flowchart showing a setting routine of a drive mode Mpls (i).

FIG. 21 is a block diagram showing details of the pressure increase / decrease prohibition correction unit in FIG. 15.

FIG. 22 is a pressure increase prohibition flag F regarding the pressure increase / decrease prohibition correction unit.
7 is a flowchart showing a setting routine for k1 (i).

FIG. 23 is a pressure increase prohibition flag F regarding the pressure increase / decrease prohibition correction unit.
6 is a flowchart showing a setting routine for k2 (i).

FIG. 24: Required yaw moment γd and allowable slip ratio Sl
It is a graph showing the relationship with max.

FIG. 25 is a graph showing the relationship between the required yaw moment γd and the allowable slip ratio Slmax after the ABS control is activated.

FIG. 26 is a flowchart showing a routine for setting a prevention flag Fk3.

FIG. 27 is a graph showing changes over time in the required yaw moment γd and the brake pressure when increasing the pressure.

28 is a block diagram showing details of a control signal forcible change unit in FIG.

FIG. 29 is a block diagram showing a part of the drive determination unit in FIG. 15.

FIG. 30 is a block diagram showing a part of the drive determination unit in FIG. 15.

FIG. 31 is a block diagram showing a part of a drive determination unit in FIG. 15.

FIG. 32 is a block diagram showing a part of the drive determination unit in FIG. 15.

FIG. 33 is a flowchart showing an ABS cooperation routine.

FIG. 34 is a block diagram showing details of a control signal selection unit in FIG. 3.

FIG. 35 is a flowchart showing a drive signal initial setting routine.

FIG. 36 is a flowchart showing a drive routine.

FIG. 37 is a time chart showing the relationship between drive mode MM (i), pulse width WW (i), actual drive mode Mexe (i), and actual pulse width Wexe (i).

FIG. 38 is a graph showing braking force / cornering force characteristics with respect to slip ratio.

FIG. 39 is a diagram for explaining the execution result of yaw moment control during right turn US during braking.

FIG. 40 is a diagram for explaining the execution result of yaw moment control during a right turn OS during braking.

[Explanation of symbols]

 2 Tandem master cylinder 3 Brake pedal 12 Inlet valve 13 Outlet valve 16,17 Pump 18 Motor 19,20 Cut-off valve 22 HU (Hydro unit) 23 ECU (Electronic control unit) 24 Wheel speed sensor 26 Handle angle sensor 27 Pedal stroke sensor 28 front and rear G sensor 29 lateral G sensor 30 yaw rate sensor

Claims (6)

[Claims] 1. A required control amount for controlling a yaw moment of a vehicle is set according to a driving state of the vehicle and / or a behavior of the vehicle, and a braking force difference is generated between two or more predetermined wheels based on the required control amount. In a turning control device for a vehicle, which is provided with a control means for controlling the yaw movement of the vehicle, when the absolute value of the required control amount tends to decrease, a regulation means for regulating the control of the yaw movement is provided. A turning control device for a vehicle. 2. The regulating means includes a determining means for determining that the decreasing tendency is present when the time differential value of the absolute value of the required control amount is not more than a predetermined value. Vehicle turning control device. 3. The control means includes a holding means for holding each braking force of the predetermined wheel when the absolute value of the required control amount tends to decrease. Vehicle turning control device. 4. The yaw rate detecting means for detecting a yaw rate of the vehicle, and the setting means for setting the required control amount based on the actual yaw rate detected by the yaw rate detecting means. The turning control device for a vehicle according to any one of claims 1 to 3. 5. The control means comprises target yaw rate setting means for setting a target yaw rate of the vehicle, wherein the setting means is based on a yaw rate deviation between the actual yaw rate and the target yaw rate or a time derivative value of the yaw rate deviation,
5. The request control amount is set, and the request control amount is set.
The vehicle turning control device described. 6. The control means, during turning braking of the vehicle, sets only the front outer wheel and the rear inner wheel as control target wheels in the turning direction, and increases the braking force of one wheel based on the required control amount. The turning control device for a vehicle according to any one of claims 1 to 5, wherein the braking force of the other wheel is reduced.