JPH10264794A - Attitude control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently absorb the error of a side slip angle so as to improve stability of attitude control by bringing an estimated side slip angle close to the target value by a correcting means when the friction coefficient of the travel road surface is detected to be in a high state, the steering angle variation is small, and a vehicle is in a steady turning travel state. SOLUTION: An SCS ECU 10 obtains an actual side slip angle from detection signals of a vehicle speed sensor 15, a steering angle sensor 16, a yaw rate sensor 17 and a lateral acceleration sensor 18, computes an estimated side slip angle from the reference value, and corrects the estimated side slip angle when the friction coefficient μ of the road surface exceeds the threshold value, the steering angle variation based on the steering angle sensor 16 is small, and a vehicle is in a steady turning travel state. That is, the reliability of the reference value is judged to be high in this case, and after adding the specified value to cutoff frequency to make a correction, the error correction speed of the estimated side slip angle is made high. As a result, correction speed can be changed even during turning of the vehicle, so that stability at the time of SCS control is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle attitude control device for suppressing side slip and spin of a running vehicle, for example, at the time of cornering, emergency obstacle avoidance, or sudden change in road surface conditions.

[0002]

2. Description of the Related Art Conventionally, a vehicle state quantity such as a yaw rate and a steering angle of a running vehicle is detected, and the vehicle skids or spins when cornering, avoiding an emergency obstacle, or suddenly changing road conditions. Numerous control devices have been proposed for suppression.

[0003] JP-A-2-151568 and JP-A-2-1-1
In each of the publications of Japanese Patent No. 51571, the estimated values of the output amounts of the two vehicle motions (for example, the yaw angular acceleration and the center-of-gravity point lateral acceleration) are corrected corresponding to the crosswind and the road surface inclination to estimate the vehicle state quantity estimation error. The thing which eliminates is proposed.

Japanese Unexamined Patent Publication No. Hei 6-115418 proposes a technique in which the start condition of distribution control is changed according to the vehicle speed and the steering angle to execute distribution suppression only when it is really necessary. . Also, Japanese Unexamined Patent Publication No.
In Japanese Patent No. 1077, the margin during driving is detected in accordance with the brake operating force of the driver, the depression amount of the accelerator pedal, and the like.
A proposal has been made to change the start condition of distribution control based on the detected margin.

[0005]

In the prior art, the sideslip angle calculated as the vehicle state quantity is an integrated value of the lateral speed calculated from the yaw rate, the vehicle speed, and the lateral acceleration. Even for a slight output error or the like, the integral error increases cumulatively, and it is necessary to periodically reset the sideslip angle to absorb the integral error.

Accordingly, the applicant of the present application has proposed a vehicle speed, a yaw rate,
A reference side slip angle calculated based on the lateral acceleration, the side slip speed, and the rate of change of the yaw rate is set, and when the vehicle is in a straight running state or at a high vehicle speed where the steering angle is substantially “0”,
It has been proposed to correct the estimated side slip angle so as to approach the reference side slip angle, reset the side slip angle to the reference side slip angle, and absorb the integration error.

However, in such a case, the setting of the above-mentioned correction condition is insufficient. For example, in a situation in which the vehicle keeps turning, it is determined that the vehicle is in an unstable state, and the skid angle is reset forever. Some things were not done and there was room for improvement.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object the purpose of the above-described vehicle attitude control apparatus when the vehicle slips when integrating the side slip angle integration error calculated as the vehicle state quantity. An object of the present invention is to make it possible to efficiently absorb the error even in a state where the running state continues, thereby improving the stability during the posture control.

[0009]

In order to achieve the above object, according to the present invention, when a vehicle is traveling on a road surface having a high friction coefficient in a steady turning state, an estimated side slip angle is reset and an integral error is reset. Was absorbed.

That is, when the deviation between the target side slip angle calculated based on the vehicle state quantity and the estimated side slip angle is equal to or larger than a predetermined deviation, the estimated side slip angle is set to the target side slip angle. A vehicle attitude control device that controls the attitude of the vehicle so as to converge to a sideslip angle, a vehicle speed detection unit that detects a vehicle speed, a steering angle detection unit that detects a steering angle of the vehicle, and a yaw rate generated in the vehicle. A yaw rate detecting means for detecting, a lateral acceleration detecting means for detecting a lateral acceleration generated in the vehicle, and a vehicle speed calculated based on the vehicle speed, steering angle, yaw rate and lateral acceleration detected by each of the detecting means. An estimated sideslip angle calculating means for integrating the sideslip speed to calculate the estimated sideslip angle; a road surface friction coefficient detecting means for detecting a friction coefficient of a road surface on which the vehicle is traveling; When the friction coefficient of the traveling road surface is detected as being high by the surface friction coefficient detecting means, and the amount of change in the steering angle detected by the steering angle detecting means is small and the vehicle is in a steady turning traveling state, And correcting means for bringing the estimated sideslip angle calculated by the angle calculating means closer to the target value.

According to this configuration, when the traveling road surface of the vehicle is a so-called high μ road having a high coefficient of friction, and the amount of change in the steering angle is small and the vehicle is in a steady turning traveling state, the estimated side slip angle is reduced. Since the correction that approaches the target value is performed, the integration error of the estimated sideslip angle can be made extremely small compared to, for example, the case where the correction of the estimated sideslip angle is performed in a straight traveling state of the vehicle. Control can be efficiently prevented.

In the invention according to claim 2, the target value is a vehicle speed,
The reference value is calculated based on the change rate of the yaw rate, the lateral acceleration, the skid speed, and the yaw rate. The correction means has a high coefficient of friction of the road surface and a small change amount of the steering angle, so that the vehicle turns normally. When the vehicle is running, the correction speed is increased. As described above, when the traveling road surface is a high μ road, the steering angle change amount is small, and the vehicle is in a steady turning state, the correction speed of the estimated side slip angle to the reference place increases, so that the vehicle is in a turning state. However, the estimated side slip angle is corrected to the reference value according to its reliability, and the reliability of the estimated slip angle can be improved.

According to a third aspect of the present invention, there is provided a vehicle attitude control device comprising:
When the deviation between the target sideslip angle calculated based on the vehicle state quantity and the estimated sideslip angle is equal to or larger than a predetermined deviation, the vehicle attitude control device controls the attitude of the vehicle such that the estimated sideslip angle converges to the target sideslip angle. And includes the vehicle speed detecting means, the steering angle detecting means, the yaw rate detecting means, the lateral acceleration detecting means, and the estimated sideslip angle calculating means. further,
A differential value calculating means for calculating a slip angle differential value by differentiating the estimated side slip angle calculated by the estimated side slip angle calculating means twice, and a slip angle differential value calculated by the differential value calculating means being equal to or less than a set value. Correction means for bringing the estimated sideslip angle closer to the target value.

In the case of the present invention, the same operation and effect as the first aspect of the invention can be obtained. In particular, since the estimated slip angle is differentiated twice to calculate a slip angle differential value, and the estimated slip angle is corrected to a target value based on a comparison between the slip angle differential value and a set value. Compared with the present invention, there is an advantage that the steering angle and the road surface friction coefficient are not required, and the correction condition for bringing the estimated sideslip angle close to the target value can be easily set.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

(Control Block Configuration of Attitude Control Apparatus) FIG. 1 shows an overall configuration of a control block of an attitude control apparatus for a vehicle according to an embodiment of the present invention. When an obstacle is avoided or when the road surface condition changes suddenly, the braking force applied to the front, rear, left and right wheels (not shown) is controlled in order to suppress the skid and spin of the running vehicle. Each wheel has a brake (FR, right front wheel) 31, FL including a hydraulic disc brake and the like.
A (left front wheel) brake 32, an RR (right rear wheel) brake 33, and an RL (left rear wheel) brake 34 are provided. These brakes 31 to 34 are respectively connected to the hydraulic control unit 30. The hydraulic control unit 30 is connected to a wheel cylinder (not shown) of each of the brakes 31 to 34, and applies a braking force to each wheel by introducing hydraulic pressure to the wheel cylinder of each of the brakes 31 to 34. The hydraulic control unit 30 is connected to the pressurizing unit 36 and the master cylinder 37. The master cylinder 37 generates a primary hydraulic pressure in accordance with the depression force of the brake pedal 38. This primary oil pressure is introduced into the pressurizing unit 36, is pressurized to the secondary oil pressure by the pressurizing unit 36, and is introduced into the hydraulic control unit 30. Hydraulic control unit 30
Are electrically connected to the SCS / ECU 10, and each brake 31 is controlled in accordance with a braking control signal from the ECU 10.
To control the braking force applied to each wheel.

SCS (Stability Controlled System)
The ECU (Electronic Controlled Unit) 10 controls the braking of the front, rear, left and right wheels as the attitude control device of the present embodiment, and controls the well-known ABS (anti-lock brake system) and TCS (traction control system). This is an arithmetic processing unit that also controls.
The SCS / ECU 10 includes an FR wheel speed sensor 11, FL
Wheel speed sensor 12, RR wheel speed sensor 13, RL wheel speed sensor 14, vehicle speed sensor 15, steering angle sensor 16, yaw rate sensor 17, lateral acceleration sensor 1
8, the longitudinal acceleration sensor 19, the brake pedal pressure sensor 35, the EGIECU 20, and the TCS off switch 40 are connected.

An outline of the ABS control and the TCS control will be described. The ABS control automatically controls the braking force on the wheels when a sudden braking operation is performed while the vehicle is running and the wheels are likely to lock on the road surface. This is a system that controls and stops the wheel while suppressing the lock. On the other hand, the TCS control is a system in which a vehicle travels while suppressing a phenomenon in which wheels slip on a road surface while the vehicle is traveling by controlling a driving force or a braking force applied to each wheel.

The FR wheel speed sensor 11 outputs a detection signal vl of the right front wheel speed to the SCS / ECU 10. The FL wheel speed sensor 12 outputs a detection signal v2 of the wheel speed of the front left wheel to the SC.
Output to S · ECU 10. The RR wheel speed sensor 13 outputs a detection signal v3 of the wheel speed of the right rear wheel to the SCS / ECU 10. The RL wheel speed sensor 14 outputs a detection signal x4 of the wheel speed of the left rear wheel to the SCS / ECU 10. The vehicle speed sensor 15 outputs a detection signal V of the running state of the vehicle to the SCS / ECU 1
Output to 0. The steering angle sensor 16 outputs a steering rotation angle detection signal θH to the SCS / ECU 10. Yaw rate sensor 17 outputs detection signal ψ of the yaw rate actually generated in the vehicle body to SCS / ECU 10. The lateral acceleration sensor 18 outputs a detection signal Y of the lateral acceleration actually generated in the vehicle body to the SCS / ECU 10. The longitudinal acceleration sensor 19 outputs to the SCS / ECU 10 a detection signal Z of the longitudinal acceleration actually generated in the vehicle body. The brake depression force sensor 35 includes a pressure unit 36
And a detection signal PB of the depression force of the brake pedal 38
Is output to the SCS / ECU 10. The TCS off switch 40 is a switch for forcibly stopping wheel spin control (traction control), which will be described later, and outputs this switch operation signal S to the SCS-ECU 10. EGI
(Electronic Gasoline Injection)
Engine 21, AT (Automatic Transmission) 22,
It is connected to the slot valve 23 and controls the output control of the engine 21, the shift control of the AT 22, and the opening / closing control of the throttle valve 23.

SCS ECU 10 and EGI ECU 2
Reference numeral 0 includes a CPU, a ROM, and a RAM, and executes a posture control program and an engine control program stored in advance based on the input detection signals.

(Schematic Description of Posture Control) In the posture control of the present embodiment, a braking moment is applied to each wheel to apply a turning moment and a deceleration force to the vehicle body, thereby suppressing the front and rear wheels from skidding. For example, when the vehicle is in a spin state in which the rear wheels are likely to skid while turning, the brake is mainly applied to the front outer wheels and an outward moment is applied to suppress the entrainment behavior into the inside of the turns. Also, in the drift-out state where the front wheels are likely to skid and skid to the outside of the turn, an appropriate amount of brake is applied to each wheel to apply an inward moment, while suppressing the engine output and adding a deceleration force to reduce the turning radius. Suppress increase.

Although the details of the attitude control will be described later, the SCS / ECU 10 generally includes the vehicle speed sensor 15, the yaw rate sensor 17, and the lateral acceleration sensor 18 described above.
The actual side slip angle βact (hereinafter, referred to as an actual side slip angle) and the actual yaw rate ψact (hereinafter, referred to as an actual yaw rate) generated in the vehicle are calculated from the detected signals V, ψ, and Y of the vehicle. The reference value βref referred to in the calculation of the estimated sideslip angle βcont actually used for the SCS control is calculated. Also, the SCS / ECU 10
Calculates a target side slip angle βTR and a target yaw rate ψTR as a target attitude of the vehicle from a detection signal of a steering angle sensor or the like, and calculates a difference between the estimated side slip angle βcont and the target side slip angle βTR or an actual yaw rate ψact and a target yaw rate. The attitude control is started when the difference from ψTR exceeds predetermined threshold values β0 and ψ0, respectively, and control is performed so that the estimated actual sideslip angle βcont or the actual yaw rate ψact converges to the target sideslip angle βTR or the target yaw rate ψTR.

(Detailed Description of Attitude Control) Next, the attitude control (hereinafter referred to as SCS control) of the present embodiment will be described in detail. FIG. 2 shows the overall operation for executing the posture control. First, when the ignition switch is turned on by the driver and the engine is started, step S2 is executed.
Initialize CS · ECU10 and EGI · ECU20,
Clears the sensor detection signal, calculated value, etc. stored in the previous processing. In step S4, the SCS / ECU 10 detects the detection signal v1 of the FR wheel speed sensor 11, the detection signal v2 of the FL wheel speed sensor 12, the detection signal v3 of the RR wheel speed sensor 13, the detection signal v4 of the RL wheel speed sensor 14, The detection signal V of the vehicle speed sensor 15, the detection signal θH of the steering angle sensor 16, the detection signal の of the yaw rate sensor 17, the detection signal Y of the lateral acceleration sensor 18, the detection signal Z of the longitudinal acceleration sensor 19, the brake pedal pressure sensor 35 detection signal PB, switch operation signal S of the TCS off switch 40
Enter In step S6, the SCS / ECU 10
The vehicle state quantity is calculated based on each of the detection signals described above. In step S7, a wheel speed correction process is executed based on the vehicle state quantity. In step S8, the SCS-ECU 10 calculates an SCS control target value and a control output value necessary for the SCS control from the vehicle state quantity calculated in step S6. Similarly, in step S10, an ABS control target value, a control output value, and the like required for the ABS control are calculated.
It calculates a TCS control target value, a control output value, and the like necessary for CS control.

In step S14, steps S6 to S12
A control output arbitration process of each calculated control output value is executed. In this control output arbitration process, the SCS control output value, A
Compare the BS control output value and the TCS control output value respectively,
The control is shifted to the control corresponding to the largest value. Further, as will be described later, the arbitration process between the SCS control output value and the ABS control output value is executed according to the magnitude of the driver's brake pedal pressure PB. That is, in step S14, ABS
If the control output value is the largest value, ABS control is executed based on the ABS control output value (step S16), and S
If the CS control output value is the largest value, SCS control is executed based on the SCS control output value (step S1).
8) If the TCS control output value is the largest value, TC
The TCS control is executed based on the S control output value (Step S20). Then, in step S22, SCS / EC
U10 makes a fail-safe determination as to whether the hydraulic control unit 30 or the like is operating normally, and if it is determined that there is an abnormality, stops the control corresponding to the abnormality and returns to step S2. Then, the above processing is repeatedly executed.

(Explanation of SCS calculation processing) Next, the details of the SCS calculation processing shown in step S8 of FIG. 2 will be described. Note that the ABS control calculation processing and the TCS control calculation processing in steps S10 and S12 are well known, and thus description thereof will be omitted.

FIG. 3 shows a flow for executing the SCS operation processing of FIG. 2. When the processing is started, step S is executed.
At 20, the SCS / ECU 10 determines the FR wheel speed v1, the FL wheel speed v2, the RR wheel speed v3, the RL wheel speed v4, the vehicle speed V, the steering angle θ, the actual yaw rate ψact, and the actual lateral acceleration Yact.
Enter In step S32, the SCS-ECU 10 calculates the vertical load generated on the vehicle. This vertical load is estimated and calculated from the vehicle speed V and the lateral acceleration Y by a well-known mathematical method. In step S33, the SCS-ECU 10 calculates the actual sideslip angle βact actually generated in the vehicle. The actual side slip angle βact is calculated by integrating the change speed Δβact, and the change speed Δβact is calculated by the following equation (1).
Is calculated by

Δβact = ψact + Yact / V (1)

Next, in step S34, SCS / EC
U10 is an estimated side slip angle β actually used for SCS control.
The reference value βref referred to in the operation of cont is calculated. The reference value βref is determined by vehicle specifications, vehicle state quantities (vehicle speed V, yaw rate ψact, actual lateral acceleration Yact, change speed Δβact of actual sideslip angle βact, change amount (differential value) Δ ヨ ー act of yaw rate ψact), and braking. The two-degree-of-freedom model is used for calculation based on the estimated value D1 of the generated yaw moment and the estimated value D2 of the amount of decrease in the lateral force caused by the brake. In short, the reference value βref is used to calculate a side slip angle estimated based on the detected vehicle state amount and the brake operation force. Then, step S3
In step 5, the SCS-ECU 10 calculates an estimated sideslip angle βcont actually used for SCS control. The estimated sideslip angle βcont is calculated by solving a differential equation derived from the following equations (2) and (3). That is,

Δβcont = Δβact + e + Cf · (βref−βcont) (2) Δe = Cf · (Δβref−Δβact−e) (3) where e: offset correction value of yaw rate sensor and lateral acceleration sensor Cf: cut Off frequency

As will be described later in detail, the cutoff frequency Cf is generated at the estimated sideslip angle βcont by correcting the estimated sideslip βcont so as to converge to the reference value βref in accordance with the reliability of the reference value βref. This is a factor for changing the correction speed when resetting the integration error, and is corrected so as to decrease as the reliability of the reference value βref decreases. Also, the reliability of the reference value βref is lowered because the cornering power Cpf of the front wheel or the cornering power Cpr of the rear wheel is low.
When a change has occurred.

In step S36, the SCS-ECU 10 calculates a wheel slip ratio and a wheel slip angle of each wheel. The wheel slip ratio and the wheel slip angle are estimated and calculated from the wheel speeds v1 to v4 of each wheel, the vehicle speed V, the estimated side slip angle βcont, and the front wheel steering angle θH by a well-known mathematical method. In step S38, the SCS-ECU 10 calculates a load factor for each wheel. The wheel load factor is calculated in step S36.
Is calculated from the wheel slip rate and the wheel slip angle calculated in step S32 and the vertical load calculated in step S32 by a known mathematical method. In step S40, SCS · E
The CU 10 calculates a friction coefficient μ of the road surface during traveling. The coefficient of friction μ of the road surface is calculated by comparing the actual lateral acceleration Yact with the step S38.
Is calculated by a well-known mathematical method from the wheel load factors calculated in the above. Next, in step S42, SCS / EC
U10 calculates a target yaw rate ΔTR and a target sideslip angle βTR, which are target values, in order to converge the actual yaw rate Δact and the estimated sideslip angle βcont. Target yaw rate ψTR is vehicle speed
V, the friction coefficient μ of the road surface calculated in step S40, and the front wheel steering angle θH are estimated and calculated by a known mathematical method. The target sideslip angle βTR is calculated by solving the differential equation of Expression (6) derived from Expressions (4) and (5) below. That is,

Βx = 1 / (1 + A · V ² ) · {1− (M · Lf · V ² ) / (2L·Lr · Cpr)} · Lr · θH / L (4) A = M · (Cpr) · Lr-Cpf · Lf) / 2L 2 · Cpr · Cpf ... (5) ΔβTR = C · (βx -βTR) ... (6) where, V: vehicle speed .theta.H: front-wheel steering angle M: vehicle weight I: moment of inertia L: Wheel base Lf: Distance from front wheel to vehicle center of gravity Lr: Distance from rear wheel to vehicle center of gravity Cpf: Cornering power of front wheel Cpr: Cornering power of rear wheel C: Value corresponding to phase delay

Next, in step S44 shown in FIG.
The CS / ECU 10 determines whether or not the absolute value of the value obtained by subtracting the estimated sideslip angle βcont from the target sideslip angle βTR is equal to or greater than the SCS control start threshold value β0 (| βTR−βcont | ≧ β0).
? ). If the absolute value of the value obtained by subtracting the estimated sideslip angle βcont from the target sideslip angle βTR in step S44 is equal to or greater than the SCS control start threshold value β0, step S4
Proceeding to 6, set the SCS control target value to the target side slip angle βTR. On the other hand, when it is determined in step S44 that the absolute value of the value obtained by subtracting the estimated sideslip angle βcont from the target sideslip angle βTR does not exceed the SCS control start threshold value β0, the process proceeds to step S52, and the SCS-ECU 10 proceeds to step S52. It is determined whether or not the absolute value of the value obtained by subtracting the actual yaw rate ψact from the yaw rate ψTR is equal to or greater than the SCS control start threshold value ψ0 (| ψTR−ψact | ≧ ψ0?). If it is determined in step S52 that the absolute value of the value obtained by subtracting the actual yaw rate ψact from the target yaw rate ψTR is equal to or greater than the SCS control start threshold value ψ0, the process proceeds to step S54 to set the SCS control target value to the target yaw rate ψTR. . On the other hand, step S
If it is determined in step 52 that the absolute value of the value obtained by subtracting the actual yaw rate ψact from the target yaw rate ψTR does not exceed the SCS control start threshold value ψ0, the process returns to step S30 to repeatedly execute the above-described processing.

Next, in step S50, SCS / EC
U10 is the SCS control amount β actually used for SCS control.
Operate amt. In step S56, the SCS
The ECU 10 calculates an SCS control amount ψamt actually used for SCS control.

(Arbitration process between SCS control and ABS control)
Next, SCS control and arbitration processing of SCS control and ABS control will be described with reference to FIGS. Figure 5
FIG. 7 shows a flowchart for executing the arbitration process between the SCS control and the ABS control. The arbitration process described below gives priority to the ABS control if the SCS control start condition is satisfied and the ABS control is being performed. Alternatively, the SCS control output value is corrected based on the ABS control output value. When both the SCS control start condition and the ABS control start condition are satisfied, one of the controls is executed according to the magnitude of the driver's brake pedal pressure PB.

More specifically, as shown in FIG. 5, in step S58, the SCS / ECU 10
It is determined whether a failure has occurred in the hydraulic control unit 30 or the like used for the S control. If YES is determined in step S58, the process proceeds to step S74 to stop the SCS control, returns to step S2 shown in FIG. 2, and repeats the above-described processing. On the other hand, if it is determined in step S58 that no failure has occurred, the process proceeds to step S60. In this step S60, the SCS
The ECU 10 determines whether the SCS control flag F1 is set to "1". This SCS control flag F1 is
When "1" is set, it indicates that SCS control is being executed. If it is determined in step S60 that the SCS control flag F1 is set to "1", that is, if YES, the process proceeds to step S76 to determine whether the ABS control flag F2 is set to "1". This AB
If the S control flag F2 is set to "1", ABS
Indicates that control is being executed. On the other hand, if the SCS control flag F1 is not set to "1" in step S60, NO
Is determined, the process proceeds to step S62 to determine whether the ABS control is being executed. If YES in step S62 during execution of ABS control, the process proceeds to step S80 described later, while step S62 indicates that ABS control is not being executed.
In the case of O, the process proceeds to step S64. Step S64
Then, the SCS / ECU 10 determines whether or not the TCS control is being executed. If it is determined in step S64 that the TCS control is being performed (YES), the process proceeds to step S78, and the TCS control is performed.
After the braking control in the control is stopped (that is, only the torque down control by the engine can be executed), the process proceeds to step S66. On the other hand, if NO in step S64 where TCS control is not being executed, the process proceeds to step S66.

In step S66, the SCS-ECU 10
Calculates a wheel to be subjected to SCS control, calculates a target slip ratio to be allocated to the selected wheel, and calculates an SCS control amount βamt or ψamt according to the target slip ratio. Thereafter, in step S68, an engine control amount according to the required torque reduction amount is calculated. Then, SCS control is executed in step S70, and SCS is executed in step S72.
After setting the CS control flag F1 to "1", the process returns to the above-described step S2, and the above-described processing is repeatedly executed.

If it is determined in step S76 that the ABS control flag F2 has been set to "1", that is, if YES, the flow advances to step S80 shown in FIG. In step S80,
The SCS-ECU 10 converts the ABS control amount into the SCS control amount βam
Correct based on t or ψamt. Then, step S
At 82, the SCS-ECU 10 determines whether the ABS control has been completed. If NO in step S82, the SCS control flag F1 is set to "1" in step S84, and step S86.
Sets the ABS control flag F2 to "1" and returns to step S30. On the other hand, in step S82, A
If it is determined that the BS control has ended, the SCS control flag F1 is reset to "0" in step S88, the ABS control flag F2 is reset to "0" in step S90, and the process returns to step S30. I do.

Further, if it is determined in step S76 that the ABS control flag F2 is not set to "1", that is, if the determination is NO, the process proceeds to step S92 shown in FIG. Step S92
Then, the SCS / ECU 10 determines whether or not the brake equal pressure PB is equal to or more than a predetermined threshold value P0 (PB ≧ P0?). If it is determined in step S92 that the brake equal pressure PB is equal to or greater than the predetermined threshold value P0, the process proceeds to step S94 to stop the SCS control, and switches to the ABS control in step S96. Then, in step S98, the ABS control flag is set.
F2 is set to "1", and the process returns to step S30. On the other hand, if it is determined in step S92 that the brake equal pressure PB does not exceed the predetermined threshold value P0, the process proceeds to step S100. In step S100, the SCS
The ECU 10 determines whether the SCS control has been completed.
If the determination in step S100 is NO that the SCS control has not ended, the process returns to step S68, and the subsequent processing is executed. On the other hand, if it is determined in step S100 that the SCS control has been completed (YES), the SCS control flag F1 is reset to "0" in step S102, and the ABS control flag is reset in step S104.
F2 is reset to "0", and the process returns to step S30.

(Explanation of Wheel Speed Correction Processing) Next, details of the wheel speed correction processing shown in step S7 of FIG. 2 will be described. FIG. 8 shows a processing operation for executing the wheel speed correction processing of FIG. 2, and FIG. 9 shows a wheel speed correction procedure.

For example, the diameter of an auxiliary wheel (hereinafter referred to as a tempered wheel) used for puncturing is about 5 to 15% smaller than that of a normal wheel, and the wheel speed is higher than that of other normal tires. The wheel speed correction process is executed to remove the adverse effects due to such variations in the diameter of the tempered wheels and the normal wheels. The disadvantages are as follows. That is,

In the ABS control, when the wheel speed of only one wheel is high, the reference vehicle speed increases, and it is erroneously determined that the normal wheels other than the tempered wheels have a tendency to lock.

In the TCS control, if a tempered wheel is mounted on a drive wheel, it is erroneously determined that the normal wheel, which is the other drive wheel, is spinning.

The normal wheel has an error of 5% at the maximum in its diameter.
Affects S control.

As shown in FIG. 9, when the processing is started,
In step S110, the SCS / ECU 10 determines the FR wheel speed.
v1, FL wheel speed v2, RR wheel speed v3, and RL wheel speed v4 are input. In step S112, the SCS-ECU 10 determines whether or not the vehicle is traveling normally. During this steady running,
This indicates a state other than extreme acceleration / deceleration or cornering running where the reliability of the wheel speed is reduced. If it is determined in step S112 that the vehicle is not traveling normally, the process returns to step S110. Step S112
If it is determined that the vehicle is traveling in a steady state, the process proceeds to step S114, where the SCS-ECU 10 determines whether the FR wheel speed v1
It is determined whether any one of the FL wheel speed v2, the RR wheel speed v3, and the RL wheel speed v4 is equal to or higher than a predetermined threshold value va. If it is determined in step S114 that one of the wheels is equal to or greater than the predetermined threshold value va, the process proceeds to step S116. If it is determined that none of the wheels exceeds the predetermined threshold value, the process proceeds to step S122. Execute wheel speed correction for normal wheels.

In step S116, the SCS ECU 1
A value of 0 determines whether or not only one of the wheels has exceeded a predetermined threshold for a predetermined time. In this step S116, 1
If it is determined that the state where only the wheels are equal to or more than the predetermined threshold has continued for a predetermined time, the process proceeds to step S118, but the state where only one wheel is equal to or more than the predetermined threshold has not continued for the predetermined time If NO is determined, step S11 is performed.
Proceeding to 2, the wheel speed correction for the normal wheels is executed. In step S118, the SCS-ECU 10 determines that one wheel is a tempered wheel because only one wheel is equal to or greater than the predetermined threshold for a predetermined time. Then, in step S120, the SCS-ECU 10 executes a wheel speed correction for the tempered wheel.

The wheel speed correction for the normal wheel or the tempered wheel is executed by the following procedures shown in FIG. That is, the RR wheel speed is corrected based on the FR wheel speed,
Next, the FL wheel speed is corrected based on the FR wheel speed,
Finally, the RL wheel speed is corrected based on the FL wheel speed. However, when the FR wheel is a tempered wheel, the reference wheel is set to a subcutaneous wheel.

(Correction speed change processing (1))
A description will be given of a process of changing the correction speed for correcting the error accumulated by integrating the estimated sideslip angle βcont by bringing the estimated sideslip angle βcont closer to the reference value βref in the S control. FIG. 10 is a flowchart for executing a process of changing the correction speed for correcting the integration error of the estimated sideslip angle βcont, and FIG.
Shows maps for changing the correction speed for correcting the integration error of the estimated sideslip angle βcont.

Since the estimated sideslip angle βcont calculated by the above equations (2) and (3) includes the integrated value of the actual sideslip angle change amount Δβact, the estimated sideslip angle βcont is calculated by a slight output error of each sensor. Integration errors are accumulated. Estimated sideslip angle β
Since cont is a value actually used in the SCS control, if an error occurs in the estimated side slip angle βcont, the actual control may be adversely affected.

Therefore, in this embodiment, the estimated sideslip angle β
The difference between the error generated in cont and the reference value βref (βref −
βcont) and using the reference value βref as a reference value to bring the estimated sideslip angle βcont closer to the reference value βref, an error (βref−βco) generated in the estimated sideslip angle βcont
nt) is reset (βref ← βcont).

Here, the cutoff frequency Cf is a factor for determining the reset speed at which the estimated side slip angle βcont approaches the reference value βref. That is, when increasing the reset speed, the cutoff frequency Cf is set to a large value,
Conversely, when the reset speed is reduced, the cutoff frequency Cf may be set to a small value.

Referring to equations (2) and (3), the reference value β
difference between ref and estimated sideslip angle βcont (βref-βcont)
Changes according to the cutoff frequency Cf. And
If the difference is a large value, the estimated side slip angle βcont converges faster to the reference value βref, so that the error correction speed increases. Conversely, when the difference is a small value, the estimated side slip angle βcont is converged slowly by the reference value βref, so that the error correction speed becomes slow. in this way,
The cut-off frequency Cf is a factor for changing the error correction speed, and is a coefficient that is corrected to be smaller as the reliability of the reference value βref is lower. The reliability of the reference value βref becomes low when the cornering power Cpf of the front wheel or the cornering power Cpr of the rear wheel changes.

The reference value βref is based on vehicle specifications, vehicle state quantities (vehicle speed V, yaw rate ψact, actual lateral acceleration Yact, Δ
βact, the rate of change of the yaw rate ψact Δψact), etc. Accordingly, by determining whether or not the reference value βref is reliable, the estimated side slip angle βco
The reliability of nt can be determined.

Therefore, in the present embodiment, the error of the estimated sideslip angle βcont is determined based on the reliability of the reference value βref by the reference value βcon.
By changing the correction speed to be reset to ref, the more reliable value of the reference value βref and the estimated sideslip angle βcont is used as the value actually used for control,
For example, even when the vehicle is turning, the error accumulated in the estimated sideslip angle βcont can be absorbed while the more reliable value of the reference value βref and the estimated sideslip angle βcont is actually used for control. I have to. When the vehicle is traveling straight, the reference value βref is “0”, so that the estimated sideslip angle βcont is reset to “0” and the error is absorbed.

The cornering power Cpf of the front wheels or the cornering power Cpr of the rear wheels at which the reliability of the reference value βref changes changes according to the friction coefficient μ of the road surface and the steering angle. )
The reliability of the reference value βref is determined depending on whether the vehicle is in a steady turning state due to a high friction coefficient of road surface and a high μ road and a small change in the steering angle, and cutoff frequency Cf is determined. The correction speed of the error is changed by performing the correction as described above.

Then, the reliability of the reference value βref is determined according to the presence or absence of the steady turning state on the high μ road, and the reference value βref
Is low, the cutoff frequency Cf is reduced and the reference value βref is slowly corrected so that the estimated sideslip angle βcont is actually used for control.
When the reliability of the reference value βref is high in a steady turning running state of the road, the cutoff frequency Cf is increased and the estimated side slip angle βcont is corrected more quickly so that the reference value βref is actually used for control. I have.

Next, specific processing will be described. After step S42 in FIG. 3, as shown in FIG.
30, the SCS-ECU 10 determines that the road surface friction coefficient μ
Is less than or equal to a predetermined threshold value μ1 (μ ≧
μ1? ). When it is determined that the friction coefficient μ is equal to or smaller than the predetermined threshold value μ1 in step S130, the process proceeds to step S1.
At 32, the SCS-ECU 10 determines that the reliability of the reference value βref is low, and at step S134, the cutoff frequency C
A predetermined value k (k> 0) is subtracted from f (Cf → Cf−k), and the correction speed of the error of the estimated side slip angle βcont is estimated based on the cutoff frequency Cf corrected in step S136. Correct the sideslip angle βcont. On the other hand, if it is determined in step S130 that the friction coefficient μ has exceeded the predetermined threshold value μ1, that is, NO, in step S138, the steering angle θH
Is θH ≠ 0 and the steering angular velocity θH ′ is substantially “0”, that is, it is determined whether or not the vehicle is in a steady turning traveling state. If it is determined in step S138 that .theta.H = 0 or .theta.H 'is not substantially "0" and NO, the above-described step S1
Go to 32. In step S138, θHθ0 and θ
If it is determined that H ′ is substantially “0”, that is, YES, the SCS-ECU 10 determines in step S140 that the reliability of the reference value βref is high, and adds a predetermined value k from the cutoff frequency Cf in step S142 (Cf (→ Cf + k) After the correction, the speed of correcting the error of the estimated sideslip angle βcont is increased based on the cutoff frequency Cf corrected in step S136 to correct the estimated sideslip angle βcont. Thereafter, the process proceeds to step S44 in FIG.

As described above, the reliability of the reference value βref is determined according to the steady turning state of the vehicle when the road surface friction coefficient μ is high, and the error correction speed of the estimated side slip angle βcont is determined by the reference value. The higher the reliability of βref is, the higher the correction is, and the lower the reliability of the reference value βref, the lower the correction. The correction speed is determined by the cutoff frequency Cf based on the map shown in FIG. . In other words, when the reliability of the reference value βref at which the integration error occurs in the estimated side slip angle βcont is low, the correction speed at which the cutoff frequency Cf is reduced and the integration error is reset to the reference value βref is made slow, Conversely, if the reference value βref is so reliable that the integration error is small and does not affect the SCS control, the cutoff frequency Cf is increased to make the correction speed for resetting to the reference value βref faster, so that the high μ road The reliability of the reference value βref is determined in accordance with the degree of steady turning at the vehicle, and if the reliability of the reference value βref is low, the cutoff frequency Cf is decreased and the reference value βref is slowly corrected to the reference value βref to estimate the slip. The angle βcont is actually used for the control, and conversely, if the reference value βref is highly reliable, the cutoff frequency Cf is increased and the estimated side slip angle βref is corrected more quickly to obtain the reference value βref. Is actually used for control, so that there is no need to reset the sideslip periodically during steady running and absorb the integration error as in the past, and the correction speed can be changed even during vehicle turning, The stability at the time of SCS control can be improved.

(Correction Speed Changing Process (2)) Next, another embodiment of the correction speed changing process will be described. FIG. 12 is a flowchart for executing a process of changing the correction speed for correcting the integration error of the estimated sideslip angle βcont, and FIG.
Shows maps for changing the correction speed for correcting the integration error of the estimated sideslip angle βcont.

The cornering power Cpf of the front wheel or the cornering power Cpr of the rear wheel is calculated by calculating the estimated side slip angle βcont by 2
In this correction speed change processing (2), the reliability of the reference value βref is determined according to the slip angle differential value β ″ cont, and the cutoff frequency is changed. To correct the error correction speed.

Next, specific processing will be described (FIG. 1
The same processes as those of 0 will be described with the same numbers. After step S42 in FIG. 3, as shown in FIG. 13, the process proceeds to step S145, in which the SCS-ECU 10 differentiates the estimated side slip angle βcont twice to obtain a slip angle differential value β ″ co.
It is determined whether or not nt is greater than a set threshold value β1 (β ″ cont> β1?) When it is determined in step S145 that the slip angle differential value β ″ cont is larger than the set threshold value β1, YES In step S132, the SCS-ECU 10
Determines that the reliability of the reference value βref is low, and determines in step S
At step 134, a predetermined value k is subtracted from the cutoff frequency Cf (C
f → Cf−k), and the estimated side slip angle βcont is corrected by slowing the correction speed of the error of the estimated side slip angle βcont based on the cutoff frequency Cf corrected in step S136. On the other hand, if it is determined in step S145 that the slip angle differential value β ″ cont is NO equal to or smaller than the set threshold value β1, the SCS / ECU 10 determines in step S140 that the reliability of the reference value βref is high, and cuts in step S142. After a predetermined value k is added (Cf → Cf + k) from the off frequency Cf and corrected, the correction speed of the error of the estimated sideslip angle βcont is increased based on the cutoff frequency Cf corrected in step S136 to increase the estimated sideslip angle βcont. Then, the process proceeds to step S44 in FIG.

As described above, the reliability of the reference value βref is determined in accordance with the slip angle differential value β ″ cont obtained by differentiating the estimated sideslip angle βcont twice, and the error correction speed of the estimated sideslip angle βcont is determined by the reference speed. The higher the reliability of the value βref is, the higher the correction is, and the lower the reliability of the reference value βref is, the lower the correction is. The correction speed is determined by the cutoff frequency Cf based on the map shown in FIG. So
When the reliability of the reference value βref is low, the cutoff frequency Cf is reduced and the reference value βref is slowly corrected so that the estimated sideslip angle βcont is actually used for control,
Conversely, when the reliability of the reference value βref is high, the cutoff frequency Cf is increased and the estimated side slip angle βref is corrected more quickly so that the reference value βref is actually used for control. As a result, there is no need to reset the sideslip periodically during steady driving to absorb the integration error,
Since the correction speed can be changed even while the vehicle is turning, the stability during SCS control can be improved. In particular, in the change processing (2), the reliability of the reference value βref is determined based on the slip angle differential value β ″ cont obtained by differentiating the estimated side slip angle βcont twice, so that the change processing (1) is different from the change processing (1). It is unnecessary to use the steering angle θH and the road friction coefficient μ, and the estimated side slip angle βco
There is an advantage that conditions for correcting nt can be easily set.

(Explanation of Road Surface Tilt Angle Calculation Method) Next, a road surface tilt angle calculation method will be described in detail. FIG.
Shows a flow for executing a road surface inclination angle calculation process. In the road surface inclination angle calculation method according to the present embodiment, the road surface inclination angle is calculated not only from the yaw rate but also from the wheel speed difference between the inner and outer wheels. That is, the inclination angle θ of the road surface is calculated using the following equation (7) or (8).

(Vi ² −vo ² ) / 2 · L−Yact = g · sin θ (7) where vi: wheel speed of the inner wheel vo: wheel speed of the outer wheel L: wheel interval between the inner wheel and the outer wheel Yact: actual lateral Direction acceleration g: gravitational acceleration V · ψact−Yact = g · sinθ (8) where V: vehicle speed ψact: actual yaw rate Yact: actual lateral acceleration g: gravitational acceleration

Here, Y1cal = (vi ² −vo ² ) / 2 · L (9) Y2cal = V · ψact (10) In the equation (7), the right and left wheel speeds vi and vo and the inner and outer wheels are obtained. First estimated sideslip angle Y calculated from wheel spacing L of
The road surface inclination angle θ is calculated based on the deviation between 1 cal (see equation (9)) and the actual lateral acceleration Yact. In equation (8), the second estimated lateral acceleration calculated from the vehicle speed V and the actual yaw rate ψact The road surface inclination angle θ is calculated based on the deviation between Y2cal (see equation (10)) and the actual lateral acceleration Yact.

Since the detected wheel speed is not always accurate, especially before the wheel speed correction process and in at least one state of running on a rough road, accelerating, decelerating, or making a sharp turn as a vehicle running state, the following equation is used. 8), or repeatedly calculates the second estimated lateral acceleration Y2cal, and calculates the road surface inclination angle based on the average value, the maximum value, and the value weighted by a predetermined ratio. Calculate.

In addition, the calculation of the road surface inclination angle θ needs to be corrected by bringing the road surface inclination angle θ closer to “0” at a predetermined timing so that the detection error of each sensor is not affected. The timing at which the road surface inclination angle θ approaches “0” may be constantly executed slowly, may be executed slowly in accordance with the error occurrence speed of the lateral acceleration sensor, or may be executed while the vehicle is traveling straight. May be. When the control is executed during straight running of the vehicle, the yaw rate ψ is “0”, the lateral acceleration is “0”, and the steering angle θH is set.
Is “0”, and the road surface inclination angle θ is determined to be “0” under the condition that the inner and outer wheel speed difference is “0”.

In order to determine only the presence or absence of the road surface inclination angle, the first estimated yaw rate ψ1 cal calculated from the vehicle speed V and the steering angle θH does not match the actual yaw rate 、 act, and the vehicle speed V and the steering angle θH Is calculated from the second estimated lateral acceleration Y2cal is the actual lateral acceleration Y
and the first estimated yaw rate Y1cal calculated from the inner and outer wheel speed difference always matches the actual yaw rate Yact, and the second estimated lateral acceleration ψ2cal calculated from the inner and outer wheel speed difference is calculated in the actual lateral direction. The presence or absence of the road surface inclination angle θ can be estimated using the acceleration ψact and the disagreement property.

Next, specific processing will be described. In step S50 or step S56 of FIG. 4, the SCS control amount βamt
Alternatively, after calculating ψamt, as shown in FIG. 14, the process proceeds to step S160, in which the SCS-ECU 10 determines whether the steering angle θH is equal to or larger than a predetermined threshold value θ1 (θH ≧ θ1?). It is determined whether the vehicle is turning sharply. If it is determined in step S160 that the steering angle θH does not exceed the predetermined threshold value θ1, the process proceeds to step S162, while the process proceeds to step S162.
If it is determined that the steering angle θH is equal to or greater than the predetermined threshold value θ1 at 60, the process proceeds to step S172, and the second estimated sideslip calculated from the above equation (8), that is, from the vehicle speed V and the actual yaw rate ψact. The road surface inclination angle θ is calculated based on the deviation between the angle Y2cal and the actual lateral acceleration Yact.

In step S162, the SCS ECU 1
A value of 0 determines whether the vehicle is traveling on a rough road. If the determination in step S162 is NO that the vehicle is not traveling on a rough road, the process proceeds to step S164. If the determination is YES that the vehicle is traveling on a rough road, the process proceeds to step S172 to calculate from the above equation (8), that is, from the vehicle speed V and the actual yaw rate ψact. The road surface inclination angle θ is calculated based on the deviation between the second estimated side slip angle Y2cal and the actual lateral acceleration Yact.

In step S164, the SCS ECU 1
In the case of 0, it is determined whether or not the vehicle is rapidly decelerating by determining whether or not the brake equal pressure PB is equal to or more than a predetermined threshold value P1 (PB≥P1?). If it is determined in step S164 that the brake equal pressure PB is not equal to or larger than the predetermined value P1, the process proceeds to step S165, where the brake equal pressure PB is determined.
Is greater than or equal to the predetermined threshold value P1, the process proceeds to step S172, where the second value calculated from the equation (8), that is, from the vehicle speed V and the actual yaw rate ψact, is used.
The road surface inclination angle θ is calculated based on the deviation between the estimated lateral acceleration Y2cal and the actual lateral acceleration Yact.

In step S165, the SCS ECU 1
0 is determined by determining whether the vehicle acceleration ΔV (differential value of the vehicle speed V) is equal to or greater than a predetermined threshold value V2 (ΔV ≧ V2?)
It is determined whether the vehicle is rapidly accelerating. Step S16
If it is determined in step S5 that the vehicle acceleration .DELTA.V (differential value of the vehicle speed V) is not equal to or greater than the predetermined threshold value V2, step S1 is reached.
Proceeding to 66, if it is determined that the vehicle acceleration .DELTA.V (differential value of the vehicle speed V) is equal to or greater than the predetermined threshold value V2, the process proceeds to step S172, in which the vehicle speed V and the actual yaw rate .SIGMA.act Is calculated on the basis of the deviation between the second estimated lateral acceleration Y2cal and the actual lateral acceleration Yact.

In step S166, the SCS ECU 1
0 determines whether or not the wheel speed correction processing has been completed.
The wheel speed correction process has not been completed in step S166.
If it is determined to be O, the process proceeds to step S168, and the wheel speed correction process has been completed in step S166 YES
If it is determined that the vehicle speed V and the actual lateral acceleration Yact are calculated from the vehicle speed V and the actual yaw rate ψact, the process proceeds to step S172. Calculate the angle θ.

In step S168, the SCS ECU 1
0 determines whether or not a tempered wheel is mounted in the wheel speed correction processing. If it is determined in step S168 that the temper wheel is not mounted (NO), the process proceeds to step S17.
0, and if YES is determined that the tempered wheels are mounted, the flow proceeds to step S172, and the second is calculated from the above equation (8), that is, from the vehicle speed V and the actual yaw rate ψact.
The road surface inclination angle θ is calculated based on the deviation between the estimated lateral acceleration Y2cal and the actual lateral acceleration Yact.

In step S170, the road surface is determined based on the deviation between the first estimated lateral acceleration Y1cal and the actual lateral acceleration Yact calculated from the left and right wheel speeds vi and vo and the wheel interval L between the inner and outer wheels by the above equation (7). The inclination angle θ is calculated.

As described above, the calculation of the road surface inclination angle can be performed not only from the yaw rate but also from the wheel speed difference between the inner and outer wheels, and the lateral acceleration calculated from the yaw rate when the road surface inclination angle is calculated. And the lateral acceleration calculated from the difference between the inner and outer wheel speeds in accordance with the running state quantity of the vehicle (steering steering angle θH, whether or not running on a rough road, brake equal pressure PB, vehicle speed V, etc.) to achieve more reliability. Since a value with high performance can be selected, it is possible to reduce an error in the skid angle and prevent erroneous control even in a situation where the yaw rate is detected in spite of the steering angle being substantially zero, such as when traveling on an inclined road surface.

(Explanation of SCS control according to road surface inclination angle)
Next, SCS control according to the road surface inclination angle calculated by the above-described road surface inclination angle calculation method will be described in detail.
Normally, when the vehicle is always traveling on an inclined road surface, an error occurs in the detection value from the yaw rate sensor or the lateral acceleration sensor, and the estimated side slip angle βcont is calculated by integrating the detected values. Errors accumulate in the integrated value. Therefore, the estimated side slip angle βco is calculated from the target side slip angle βTR.
The absolute value of the value obtained by subtracting nt is the SCS control start threshold β0
, And there is a risk that SCS control may be erroneously intervened.

Therefore, in the SCS control of this embodiment, the first estimated lateral acceleration Y1cal and the actual lateral acceleration Yac calculated from the left and right wheel speeds vi and vo and the wheel interval L between the inner and outer wheels.
The road surface inclination angle θv calculated based on the deviation of t, or the θＶ calculated based on the deviation between the second estimated lateral acceleration Y2cal calculated from the vehicle speed V and the actual yaw rate ψact and the actual lateral acceleration Yact is predetermined. If the threshold value is θB or more,
The SCS control intervention threshold value β shown in step S44 of FIG.
0 or the SCS control intervention threshold value ψ0 shown in step S52 of FIG. 4 is increased to suppress the intervention of the SCS control,
Alternatively, the control based on the estimated sideslip angle cont and the actual yaw rate ψact is stopped, and the control is switched to the control based on the SCS control amount Yamt calculated from the actual lateral acceleration Yact.

Next, specific processing will be described. (Control intervention suppression processing based on SCS control start threshold value) First, the SCS control intervention threshold value β0 shown in step S44 in FIG. 4 or the SC shown in step S52 in FIG.
A method for suppressing the intervention of the SCS control by increasing the S control intervention threshold value ψ0 will be described. FIG. 15 shows a flow for executing the control intervention suppression process based on the SCS control start threshold value. As shown in FIG. 15, after calculating the road surface inclination angle θv from the left and right wheel speeds vi and vo in step S170 of FIG. 14, or calculating the road surface inclination angle θψ from the actual yaw rate {act in step S172,
In step S174, the SCS-ECU 10 inputs the road surface inclination angle θv or θψ. After that, step S176
Then, the SCS-ECU 10 determines whether or not the road surface inclination angle θv or θψ is equal to or larger than a predetermined threshold value θB. In step S176, the road surface inclination angle θv or θψ is equal to the predetermined threshold value θ.
If NO is determined to be not greater than B, the process proceeds to step S44 in FIG. 4. If it is determined in step S176 that the road surface inclination angle θv or θψ is equal to or greater than the predetermined threshold θB, the process proceeds to step S178. In step S178, the SCS / ECU 10 sets the SCS control start threshold value β0
Alternatively, a predetermined value 1 (1> 0) is added to ψ0 (β0 → β0 + 1)
Or ψ0 → ψ0 + 1) to increase the SCS control start threshold, and then proceed to step S44 in FIG.

As described above, if the road surface inclination angle θv or θψ is equal to or larger than the predetermined threshold value θB, the predetermined value 1 is added to the SCS control start threshold value β0 or ψ0 (β0 → β0 + 1).
Or, ψ0 → ψ0 + 1) to increase the SCS control start threshold value and suppress the SCS control intervention, thereby preventing the erroneous intervention of the posture control even while traveling on an inclined road surface.

(Control Intervention Suppression Processing by Switching SCS Control) Next, the estimated side slip angle cont and the actual yaw rate ψact
A method of stopping the control based on the actual lateral acceleration Yact and switching to the control based on the SCS control amount Yamt calculated from the actual lateral acceleration Yact will be described. FIG. 16 shows a flow for executing the SCS control switching process. The same processes as those in FIG. 15 are given the same numbers.

As shown in FIG. 16, step S in FIG.
After calculating the road surface inclination angle θv from the left and right wheel speeds vi and vo in 170, or calculating the road surface inclination angle θψ from the actual yaw rate {act in step S172, in step S174, the SCS / ECU 10 inputs the road surface inclination angle θv or θψ. I do. Then, in step S176, S
The CS / ECU 10 determines whether the road surface inclination angle θv or θψ is equal to or larger than a predetermined threshold value θB. Step S17
If it is determined in step 6 that the road surface inclination angle θv or θ 以上 is not equal to or greater than the predetermined threshold value θB, the process proceeds to step S44 in FIG. 4, and it is determined that the road surface inclination angle θv or θψ is equal to or greater than the predetermined threshold value θB. If so, the process proceeds to step S180. In step S180, the SCS / ECU 10
The SCS control amount Yamt actually used for the CS control is calculated, the control based on the estimated side slip angle cont and the actual yaw rate ψact is stopped, and the control is switched to the control based on the SCS control amount Yamt calculated from the actual lateral acceleration Yact. Then, the process proceeds to step S44 in FIG.

As described above, if the road surface inclination angle θv or θψ is equal to or larger than the predetermined threshold value θB, the estimated side slip angle cont
By halting the control based on the actual yaw rate ψact and switching to the control based on the control amount Yamt calculated from the actual lateral acceleration Yact, erroneous intervention of the attitude control can be prevented even when the vehicle is traveling on an inclined road surface. .

(Explanation of Calculation Method of SCS Control Amount Based on Actual Lateral Acceleration) Next, in the SCS control in step S180 in FIG.
The process of calculating the S control amount Yamt will be described. FIG.
7 shows a flow for executing the calculation processing of the SCS control amount based on the actual lateral acceleration.

The control based on the actual lateral acceleration Yact described below is executed only when the actual lateral acceleration Yact detected by the lateral acceleration sensor is equal to or less than the target lateral acceleration YTR.

To explain the specific processing, as shown in FIG. 17, in step S182, the SCS-ECU 10
Calculates the maximum lateral acceleration Ymax allowed by the road surface friction coefficient μ, the actual lateral acceleration Yact, and the road surface friction coefficient μ. Then, in step S184, the SCS ECU
Numeral 10 calculates a target lateral acceleration YTR which becomes a target value in order to converge the actual lateral acceleration Yact. Step S18
In step 6, it is determined whether or not the target lateral acceleration YTR is equal to or greater than a predetermined threshold Y1 (Yact≤Y1?). If it is determined in step S186 that the target lateral acceleration YTR is not equal to or larger than the predetermined threshold Y1, the process proceeds to step S188. If it is determined that the target lateral acceleration YTR is equal to or larger than the predetermined threshold Y1, the process proceeds to step S188. Proceeding to S190, the target lateral acceleration YTR is set to the predetermined threshold value Y1, and then the process proceeds to step S188.

In step S188, the SCS ECU 1
A value of 0 determines whether the actual lateral acceleration Yact is greater than or equal to the target lateral acceleration YTR (Yact≤YTR?). In step S188, the actual lateral acceleration Yact is equal to the target lateral acceleration Yact.
If it is determined that NO is not more than TR, step S in FIG.
Returning to step 30, the subsequent processing is repeatedly executed.
On the other hand, if it is determined in step S188 that the actual lateral acceleration Yact is equal to or greater than the target lateral acceleration YTR, the process proceeds to step S192 to calculate the SCS control amount Yamt based on the target lateral acceleration YTR. The process proceeds to step S58 of No. 5, and the subsequent processing is repeatedly executed.

The SCS control method according to the road surface inclination angle θ described with reference to FIGS. 14 to 17 can also be applied to the pressing force due to the crosswind while the vehicle is running. In this case, the road surface inclination angle θ
Instead, the pressing force due to the cross wind is calculated, and if the pressing force is equal to or more than the predetermined threshold, the intervention of the SCS control may be suppressed.

(SCS Control Intervention Permission Processing Based on Running State) Next, SCS control intervention permission processing based on the running state of the vehicle will be described. FIG. 18 shows a flow for executing the SCS control intervention permission process based on the running state of the vehicle, and FIG. 19 shows a map for changing the SCS control intervention permission area.

As described above, if the SCS control intervention is suppressed just because the vehicle is running while receiving an inclined road surface or a crosswind, when the vehicle actually skids,
CS control is not executed.

To eliminate such adverse effects, the vehicle speed V,
Steering angle θH, changing speed of steering angle θH ΔθH, changing speed of actual side slip angle βact Δβact, changing speed of actual yaw rate ψact Δψact, friction coefficient of road surface μ
For example, an SCS control intervention permission area is provided to allow the SCS control intervention in a situation where the vehicle is likely to skid.

The specific processing will be described. As shown in FIG. 18, in step S200, the SCS / ECU 10 inputs the vehicle speed V, the steering angle θH, the actual yaw rate ψact, and the actual lateral acceleration Yact. Then, step S2
In 02, it is determined whether or not the current traveling state of the vehicle is within the SCS control intervention inhibition area A determined by the steering angle θH, the vehicle speed V, and the road surface friction coefficient μ shown in FIG. In step S202, the current running state of the vehicle is set to SC.
If it is determined to be YES in the S control intervention inhibition area A, the process proceeds to step S204. If it is determined that the current vehicle running state is not in the SCS control intervention inhibition area A, the process proceeds to step S212 to proceed to S212. Allow control intervention.

In step S204, the SCS ECU 1
0 determines whether or not the change speed ΔθH of the steering angle θH (the differential value of the steering angle θH) is equal to or greater than a predetermined threshold value α1 (ΔθH ≧ α1?). Step S20
If it is determined in step S4 that the change speed .DELTA..theta.H of the steering angle .theta.
Proceeding to 206, the change speed ΔθH of the steering angle θH
Is greater than or equal to the predetermined threshold value α1, the process proceeds to step S212, and SCS control intervention is permitted.

In step S206, the SCS ECU 1
0 determines whether or not the change speed Δβact of the actual sideslip angle βact (the differential value of the actual sideslip angle βact) is equal to or greater than a predetermined threshold value α2 (Δβact ≧ α2?). In step S206, the speed of change Δβact of the actual sideslip angle βact is
If it is determined that the answer is no more than 2 (step S208)
When it is determined that the change speed .DELTA..beta.act of the actual side slip angle .beta.act is equal to or larger than the predetermined threshold value .alpha.2, the process proceeds to step S212 to permit the intervention of the SCS control.

In step S208, the SCS ECU 1
0 determines whether or not the change speed Δ 変 化 act of the actual yaw rate ψact (the differential value of the actual yaw rate ψact) is equal to or greater than a predetermined threshold α3 (Δψact ≧ α3?). Step S20
If it is determined in step S8 that the change speed Δ 実 act of the actual yaw rate ψact is not equal to or larger than the predetermined threshold value α3, NO
Proceed to 10 to prohibit SCS control intervention, and
If it is determined that the rate of change Δψact of act is equal to or greater than the predetermined threshold value α3, the process proceeds to step S212 and proceeds to step S212.
Allow CS control intervention.

As described above, the SCS is calculated based on the vehicle speed V, the steering angle θH, the changing speed ΔθH of the steering angle θH, the changing speed Δβact of the actual sideslip angle βact, the changing speed Δψact of the actual yaw rate ψact, the friction coefficient μ of the road surface, and the like. By providing the control intervention permission area, it is possible to reliably execute the SCS control intervention in a situation where the vehicle is likely to skid, and it is highly possible that the SCS is running while receiving an inclined road surface or a crosswind. In the control prohibition area A, erroneous intervention can be prevented by suppressing SCS control intervention.

(Description of SCS Control Method Based on SCS Control Operation Frequency) Next, a description will be given of a process of changing the SCS control start threshold based on the SCS control operation frequency. FIG. 20 shows the SCS based on the operation frequency of the SCS control.
A flow for executing a process of changing the control start threshold value, and FIGS. 21 to 24 show maps for changing the SCS control start threshold value, respectively.

In the above-described SCS control, it is possible to effectively suppress a skid or a spin that occurs in a running vehicle at the time of cornering, emergency avoidance of an obstacle, sudden change of road surface condition, or the like.

However, when the driver becomes accustomed to the operation relying on the above-mentioned SCS control, the driver's safety consciousness becomes sparse, and the driver tends to operate in a state close to the limit area where the SCS control is impossible. May come out.

Therefore, in the process of changing the SCS control start threshold value based on the SCS control operation frequency described below,
The frequency of SCS control operation per unit time is detected,
When the operation frequency of the S control is large, the SCS control start threshold value is corrected so as to decrease, so that it is easy to intervene in the SCS control. That is, for a driver who frequently operates the SCS control, the SCS control is not executed immediately before the vehicle reaches the limit, but the SCS control is intervened sufficiently before the vehicle reaches the limit. As a result, the safety of an insecure driver who relied on the SCS control is improved, and in particular, the torque down control of the engine in the SCS control is used as a warning for a driver who performs a dangerous operation in which the SCS control frequently operates. It will work.

The specific processing will be described. As shown in FIG. 20, in step S220, the SCS / ECU 10 inputs the vehicle speed V, the steering angle θH, and the road surface friction coefficient μ. In step S222, the SCS / ECU 10
The operation frequency of CS control is calculated. The operation frequency is the number of times the SCS control is operated per unit time or the ratio of the operation time of the SCS control to the non-operation time. Step S224
Then, the SCS-ECU 10 corrects the SCS control start threshold values β0, ψ0 according to the operation frequency calculated in step S222 (β0 → β0 · x0, ψ0 → ψ0 · x0). That is, based on the map shown in FIG. 21, the SCS control start threshold value β0, ψ0 is multiplied by the correction coefficient x0, and as the SCS control operation frequency increases, the SCS control start threshold value β0, ψ0
Correct so that 0 becomes smaller.

In step S226, the SCS ECU 1
0 means that the SCS control start threshold value β0, ψ0 corrected in step S224 is further corrected according to the vehicle speed V (β0
→ β0 x0 x1, ψ0 → x0 x1). That is, based on the map shown in FIG. 22, the SCS control start threshold values β0, ψ0 corrected in step S224 are added to the correction coefficient x1.
And the SCS control start threshold values β0, ψ0 are further reduced as the vehicle speed V increases.

At step S228, the SCS ECU 1
A value of 0 further corrects the SCS control start threshold values β0 and ψ0 corrected in step S226 in accordance with the steering angle θH (β0 → β0x0x1x2, ψ0 → ψ0x0
x1 x2). That is, based on the map shown in FIG.
The SCS control start threshold value β0, ψ0 corrected in step S226 is multiplied by a correction coefficient x2, and the steering angle θ
Further correction is made so that the larger the H is, the smaller the SCS control start threshold values β0 and ψ0 are.

At step S230, the SCS ECU 1
A value of 0 further corrects the SCS control start threshold values β0 and ψ0 corrected in step S228 according to the friction coefficient μ of the road surface (β0 → β0x0x1x2x3, ψ0 → ψ0x0
x1, x2, x3). That is, based on the map shown in FIG. 24, the SCS control start threshold value β0, ψ0 corrected in step S228 is multiplied by the correction coefficient x3, and as the road surface friction coefficient μ decreases, the SCS control start threshold value β0, Make further corrections to reduce 0.

Next, in step S232, SCS · E
CU10 changes the target sideslip angle βTR or ΔTR and changes the SCS
It is determined whether or not the control start threshold value β0, ψ0 or more has been reached (see steps S44 and S52 in FIG. 4). YES in step S232 when target side slip angle βTR or ΔTR has changed
If it is determined that the target side slip angle βTR or ΔTR has not changed in step S232, the process proceeds to step S236.

In step S234, the SCS ECU 10
Sets d1 as the correction coefficient x4, while step S236
Then, the SCS-ECU 10 sets d2 as the correction coefficient x4. However, d1> d2.

In step S238, step S230
The SCS control start threshold values β0 and ψ0 corrected by the above are multiplied by a predetermined coefficient x4, and when the target sideslip angle βTR or ψTR changes, the SCS control start threshold value becomes larger than when the actual sideslip angle βact or ψact changes. Correct so as to suppress the decrease of β0 and ψ0.

In the above embodiment, the SCS control start threshold value β0 is set according to the operation frequency of the SCS control and the vehicle state quantity.
, Ψ0, but the SCS control end threshold may be corrected based on these values to make it difficult to end the SCS control.

As described above, when the operation frequency of the SCS control is high or when the SCS control start threshold value β0, ψ0 is corrected in a direction in which the SCS control is started easily according to the vehicle state quantity, the disadvantage of relying on the SCS control is obtained. In addition to increasing the safety for an inexperienced driver, the torque down control of the engine in the SCS control in particular acts as a warning for a driver who performs dangerous driving in which the SCS control frequently operates. .

(Description of TCS Control Method During SCS Control) Next, TCS control during SCS control will be described. FIG. 25 shows a flow for executing TCS control during SCS control.

In the above-mentioned SCS control, during SCS control, T
The brake control for the wheels under the CS control is stopped, and only the torque down control by the engine can be executed.

However, if the engine output is increased by the driver's accelerator operation even during the TCS control, the difference between the wheel speeds of the brake wheels to be subjected to the SCS control and the other drive wheels becomes larger than the target value. In some cases, changes in vehicle behavior cannot be controlled as intended.

Thus, in the SCS control described below,
By facilitating the execution of the torque down control of the engine by the TCS control during the SCS control, the load on the braking device can be reduced by making the torque down control by the TCS control act on the SCS control involving the wheel braking in an auxiliary manner. In addition, a change in vehicle behavior can be controlled as intended by suppressing a change in wheel speed caused by a driver's accelerator operation.

The specific processing will be described. As shown in FIG. 24, in step S250, the SCS / ECU 10
It is determined whether CS control is being performed. Step S250
If the determination is YES during the control, the process proceeds to step S252, and if the determination is NO during the SCS control, the process proceeds to step S262.
To perform the normal control of the TCS, that is, the braking control for the wheels and the torque down control of the engine.

At step S252, the SCS ECU 1
A value of 0 lowers the start threshold value of the TCS control (however, only the torque down control of the engine) by 20%, so that the TCS control is easily started. In step S254, the SCS / ECU
Numeral 10 changes the average value of the wheel speeds, which is the reference of the TCS control, to the maximum value of the wheel speeds (select High), and makes it easier to start the TCS control in a situation where apparently slip wheels are likely to occur.

At step S256, the SCS ECU 1
0 forcibly turns on the TCS off switch 40 shown in FIG. 1 so that the TCS control can be started even when the TCS off switch 40 is off.

In step S258, the SCS / ECU 1
0 means that the target value used for TCS control is reduced by 10% and T
CS control is easily started.

In step S260, the SCS ECU 1
0 restricts the upper limit of the output value of the engine to the output value at the start of the SCS control.

As described above, during SCS control, TC
By facilitating the execution of the torque down control of the engine by the S control, the torque down control by the TCS control is additionally applied to the SCS control involving the wheel braking, so that the load on the braking device can be reduced. By suppressing the wheel speed change generated by the accelerator operation, the change in the behavior of the vehicle can be controlled as intended.

(Description of Another Engine Control Method During SCS Control) Next, another engine control method during SCS control will be described. In the above SCS control, S
Although the change in the wheel speed was suppressed by making it easier to perform the torque reduction control of the engine by the TCS control during the CS control, as another method, the opening and closing of the throttle valve 23 shown in FIG. 1 was controlled, and the throttle valve was controlled during the SCS control. By controlling the opening of 23 to be constant and the engine output to be substantially constant, it is also possible to suppress a change in wheel speed caused by the accelerator operation by the driver.

The present invention can be applied to a modified or changed embodiment without departing from the spirit of the invention.

[0121]

As described above, according to the first aspect of the present invention, when the vehicle is traveling on a road surface having a high friction coefficient in a steady turning state, the estimated value is calculated for use in actual attitude control. By resetting the sideslip angle to the target value, the integrated error of the estimated sideslip angle can be absorbed even while the vehicle is turning, efficiently preventing erroneous control due to the integrated error, Stability can be improved.

According to the second aspect of the present invention, the estimated sideslip angle is corrected to a reference value calculated based on the vehicle speed, the yaw rate, the lateral acceleration, the sideslip speed, and the rate of change of the yaw rate. Even when the vehicle is in a steady turning running condition with a high μ road and a small steering angle change amount, the estimated side slip angle can be used as a reference value even when the vehicle is turning. , The reliability of the estimated slip angle can be improved.

According to the third aspect of the present invention, the slip angle differential value is calculated by time-differentiating the estimated slip angle twice, and when the slip angle differential value is small, the estimated slip angle approaches the target value. Accordingly, the same function and effect as those of the first aspect of the invention can be obtained, and a steering condition and a road surface friction coefficient are not required, and a correction condition for bringing the estimated sideslip angle close to the target value can be easily set.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a control block of a vehicle attitude control device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an overall operation for executing the posture control according to the embodiment.

FIG. 3 is a flowchart for executing the SCS calculation processing of FIG. 2;

FIG. 4 is a flowchart for executing the SCS calculation processing of FIG. 2;

FIG. 5 is a flowchart for executing arbitration processing between SCS control and ABS control.

FIG. 6 is a flowchart for executing arbitration processing between SCS control and ABS control.

FIG. 7 is a flowchart for executing arbitration processing between SCS control and ABS control.

FIG. 8 is a flowchart for executing a wheel speed correction process of FIG. 2;

FIG. 9 is a schematic diagram showing a wheel speed correction procedure.

FIG. 10 is a flowchart for executing a process (1) for changing the correction speed of the error of the estimated sideslip angle.

FIG. 11 is a diagram showing a map for changing a correction speed of an error of an estimated sideslip angle in a change process (1).

FIG. 12 is a flowchart for executing a process (2) for changing the correction speed of the error of the estimated sideslip angle.

FIG. 13 is a diagram showing a map for changing a correction speed of an error of an estimated sideslip angle in a changing process (2).

FIG. 14 is a flowchart for executing a road inclination angle calculation process;

FIG. 15 is a flowchart for executing control intervention suppression processing based on an SCS control start threshold value.

FIG. 16 is a flowchart for executing SCS control switching processing.

FIG. 17 is a flowchart for executing a calculation process of an SCS control amount based on an actual lateral acceleration.

FIG. 18 is a flowchart for executing SCS control intervention permission processing based on the running state of the vehicle.

FIG. 19 is a diagram showing a map for changing an SCS control intervention permission area.

FIG. 20 is a flowchart for executing a process of changing the SCS control start threshold based on the operation frequency of the SCS control.

FIG. 21 is a diagram showing a map for changing an SCS control start threshold value.

FIG. 22 is a diagram showing a map for changing an SCS control start threshold value.

FIG. 23 is a diagram showing a map for changing an SCS control start threshold value.

FIG. 24 is a diagram showing a map for changing an SCS control start threshold value.

FIG. 25 is a flowchart for executing TCS control during SCS control.

[Explanation of symbols]

 Reference Signs List 10 SCS / ECU 11 FR wheel speed sensor 12 FL wheel speed sensor 13 RR wheel speed sensor 14 RL wheel speed sensor 15 Vehicle speed sensor 16 Steering angle sensor 17 Yaw rate sensor 18 Lateral acceleration sensor 19 Forward / backward acceleration sensor 20 EGI / ECU 21 Engine 22 Automatic transmission 23 Throttle valve 30 Hydraulic control unit 31 FR brake 32 FL brake 33 RR brake 34 RL brake 35 Brake pedal pressure sensor 36 Pressurizing unit 37 Master cylinder 38 Brake pedal 40 TCS off switch

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsuya Tachihata 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (3)

[Claims] When the deviation between a target sideslip angle calculated based on a vehicle state quantity and an estimated sideslip angle is equal to or larger than a predetermined deviation, the attitude of the vehicle is controlled such that the estimated sideslip angle converges to the target sideslip angle. A vehicle attitude control device, comprising: vehicle speed detection means for detecting a vehicle speed; steering angle detection means for detecting a steering angle of the vehicle; yaw rate detection means for detecting a yaw rate generated in the vehicle; A lateral acceleration detecting means for detecting the directional acceleration; and a vehicle slip, steering angle, yaw rate, and a vehicle skid speed calculated based on the lateral acceleration detected by the detecting means are integrated to calculate the estimated skid angle. Estimated side slip angle computing means, road surface friction coefficient detecting means for detecting a friction coefficient of a vehicle traveling road surface, and friction of a traveling road surface by the road surface friction coefficient detecting means The estimated side slip angle calculated by the estimated side slip angle calculating means when the vehicle is in a steady turning traveling state with the change in the steering angle detected by the steering angle detecting means being small and the steering angle being detected by the steering angle detecting means being small. And a correction means for bringing the value closer to a target value. 2. The vehicle attitude control device according to claim 1, wherein the target value is a reference value calculated based on a vehicle speed, a yaw rate, a lateral acceleration, a side slip speed, and a change rate of the yaw rate. An attitude control device for a vehicle, wherein the correction speed is increased when the vehicle is in a steady turning traveling state with a high coefficient of friction on a road surface and a small amount of change in a steering angle. 3. When the deviation between the target sideslip angle calculated based on the vehicle state quantity and the estimated sideslip angle is equal to or larger than a predetermined deviation, the attitude of the vehicle is controlled so that the estimated sideslip angle converges on the target sideslip angle. A vehicle attitude control device, comprising: vehicle speed detection means for detecting a vehicle speed; steering angle detection means for detecting a steering angle of the vehicle; yaw rate detection means for detecting a yaw rate generated in the vehicle; A lateral acceleration detecting means for detecting the directional acceleration; and a vehicle slip, steering angle, yaw rate, and a vehicle skid speed calculated based on the lateral acceleration detected by the detecting means are integrated to calculate the estimated skid angle. Estimated side slip angle calculating means, and differential value calculating means for calculating a slip angle differential value by differentiating the estimated sideslip angle calculated by the estimated side slip angle calculating means twice. And a correcting means for bringing the estimated side slip angle closer to a target value when the slip angle differential value calculated by the differential value calculating means is equal to or less than a set value.