JPH10181553A - Attitude control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shift control in a direction of heightening safety by detecting operation frequency of attitude control of converging the estimate per specified period on the target value, and making the attitude control start threshold value smaller as the operation frequency is larger so as to reduce specified deviation. SOLUTION: Vehicle speed V, a steering angle θH and the friction coefficient of the road surface are inputted to an SCS ECU 10, and operation frequency of SCS is computed. The operation frequency is the operation frequency of SCS control per unit time or the ratio of operating time of SCS control to nonoperating time. The SCS ECU 10 multiplies the control start threshold value by a correction factor according to the computed operation frequency and correct so that the larger the operation frequency of SCS control is, the smaller the control start threshold value is. This can result in heightening safety of a poor driver depending on SCS control.

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, and more particularly to a vehicle attitude control device for suppressing skidding or spinning of a running vehicle at the time of cornering, emergency avoidance of obstacles, or sudden change in road surface conditions. The present invention relates to a vehicle attitude control device.

[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
No. 51571 includes two vehicle motion output quantities (for example,
Yaw angular acceleration and center-of-gravity point lateral acceleration),
A proposal has been made to correct the crosswind and the road surface inclination to eliminate the estimation error of the vehicle state quantity.

Japanese Patent Application Laid-Open No. HEI 6-115418 proposes a technique in which distribution control is executed only when it is really necessary by changing the start condition of distribution control according to the vehicle speed and the steering angle. Also, Japanese Unexamined Patent Publication No.
No. 77 proposes a method of detecting a margin during driving according to a driver's brake operating force and an accelerator pedal depression amount, and changing a start condition of distribution control based on the detected margin. Have been.

[0005]

However, when the driver becomes accustomed to driving relying on the attitude control, the driver's safety consciousness becomes sparse, and the driver tends to drive in a state close to the uncontrollable limit area. There is a problem.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a driver who has become less conscious of safety due to the fact that the driver has become dependent on attitude control, and is therefore not required to provide safety. It is an object of the present invention to provide a vehicle attitude control device capable of shifting control in a direction in which the vehicle height increases.

[0007]

SUMMARY OF THE INVENTION To solve the above problems,
In order to achieve the object, a vehicle attitude control device according to the present invention has the following configuration. That is, when the deviation between the target value and the estimated value related to the vehicle state quantity is equal to or greater than a predetermined deviation, the apparatus converges the estimated value to the target value and controls the attitude of the vehicle to the target value. An operation frequency of the attitude control that causes the estimated value to converge to the target value is detected, and as the operation frequency increases, the start threshold value of the attitude control is reduced, and the predetermined deviation is reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

[Control Block Configuration of Attitude Control Apparatus] First, a control block configuration of the attitude control apparatus for a vehicle according to the present embodiment will be described. 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.

As shown in FIG. 1, the attitude control apparatus according to the present embodiment can be used, for example, when the running state of the vehicle is cornering, when avoiding an emergency obstacle, or when the road surface condition is suddenly changed. In order to suppress the spin, the braking force to the front, rear, left and right wheels is controlled. Each wheel has
FR (right front wheel) brake such as hydraulic disc brake 3
1. FL (left front wheel) brake 32, RR (right rear wheel) brake 33, RL (left rear wheel) brake 34 are provided. These FR, FL, RR, RL brakes 31 to 34
Are connected to the hydraulic control unit 30, respectively. The hydraulic control unit 30 includes FR, FL, RR, and RL brakes 31.
To brake wheels 34 (not shown), and a braking force is applied to each wheel by introducing hydraulic pressure to the wheel cylinders of the brakes 31 to 34. The hydraulic control unit 30 includes a pressurizing unit 36 and a master cylinder 37.
It is connected to the. The master cylinder 37 generates a primary hydraulic pressure in accordance with the depression force of the brake pedal 38. This one
The next hydraulic pressure is introduced into the pressurizing unit 36, is pressurized to the secondary hydraulic pressure by the pressurizing unit 36, and is introduced into the hydraulic pressure control unit 30. The hydraulic control unit 30 includes the SCSECU 10
And controls the distribution of oil pressure to the FR, FL, RR, and RL brakes 31 to 34 in response to a braking control signal from the ECU 10 to control the braking force on 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 also controls the well-known ABS (anti-lock brake system) and TCS (traction control system). This is an arithmetic processing unit that also performs control. S
The CS / ECU 10 includes an FR wheel speed sensor 11, an FL wheel speed sensor 12, an RR wheel speed sensor 13, an RL wheel speed sensor 14, a vehicle speed sensor 15, and a steering steering angle sensor 1.
6, yaw rate sensor 17, lateral acceleration sensor 18,
Longitudinal acceleration sensor 19, brake pressure sensor 3
5, 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 applies a braking force to a wheel when a sudden braking operation is performed while the vehicle is running and the wheel is likely to lock on a road surface. This is a system that controls the wheels to stop while suppressing the lock of the wheels. The TCS control suppresses the phenomenon that the wheels slip on the road surface while the vehicle is running by controlling the driving force or the braking force to each wheel. This is a system that runs while traveling.

The FR wheel speed sensor 11 outputs a detection signal v1 of the wheel speed of the right front wheel 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 v4 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 traveling speed of the vehicle to the SCS / ECU 1
Output to 0. The steering 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 a lateral acceleration actually generated in the vehicle body to the SCS / ECU 10. The longitudinal acceleration sensor 19 outputs a detection signal Z of the longitudinal acceleration actually generated in the vehicle body to the SCS / ECU 10. 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 (E
The LECTRONIC GASOLINE INJECTION) ECU 20 is connected to the engine 21, an automatic transmission (AT) 22, and a throttle valve 23 and controls output of the engine 21, shift control of the AT 22, and 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 turning moment and a deceleration force are applied to the vehicle body by controlling the braking of each wheel, thereby suppressing the front and rear wheels from skidding. For example, when the rear wheel is likely to skid while the vehicle is turning (spin), a brake is mainly applied to the front outer wheel to apply an outward moment to suppress the entrainment behavior inside the turn. When the front wheels are likely to skid to the outside of the turn (drift out), an appropriate amount of brake is applied to each wheel to apply an inward moment, and the turning radius is reduced by suppressing the engine output and adding a deceleration force. Is suppressed.

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.
From the detection signals V, ψ, and Y, the actual sideslip angle (hereinafter referred to as actual sideslip angle) βact and the actual yaw rate (hereinafter referred to as actual yaw rate) ψact generated in the vehicle are calculated, and from the actual sideslip angle βact 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
A target side slip angle βTR and a target yaw rate ψTR are calculated as a target attitude of the vehicle from a detection signal of a steering angle sensor or the like, and an estimated side slip angle βcont and a target side slip angle βTR are calculated.
Attitude control is started when the difference between the actual yaw rate ヨ ー act and the target yaw rate 所 定 TR exceeds a predetermined threshold β0, ψ0,
The 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 is a flowchart illustrating an overall operation for executing the posture control according to the present embodiment.

As shown in FIG. 2, first, when the ignition switch is turned on by the driver and the engine is started, in step S2, the SCS-ECU 10, EGI-E
The CU 20 is initialized, and clears the sensor detection signal, the calculated value, and the like stored in the previous processing. In step S4, the SCS / ECU 10 detects the detection signal v1 of the above-described FR wheel speed sensor 11, the detection signal v2 of the FL wheel speed sensor 12, and RR.
Detection signal v3 of wheel speed sensor 13, 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 ψ of the yaw rate sensor 17, and the detection signal of the lateral acceleration sensor 18.
Y, detection signal Z of longitudinal acceleration sensor 19, detection signal PB of brake pedal pressure sensor 35, TCS off switch 40
The switch operation signal S is input. In step S6, S
The CS / ECU 10 calculates a vehicle state quantity 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
The ECU 10 calculates an SCS control target value and a control output value required for 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, and in step S12, a TCS control target value, a control output value, and the like required for the TCS control are calculated.

In step S14, a control output arbitration process of each control output value calculated in steps S8 to S12 is executed. In this control output arbitration process, the SCS control output value, the ABS control output value, and the TCS control output value are compared, and the control is shifted to the control corresponding to the largest value. Also,
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 pressing force PB. That is, when the ABS control output value is the largest value in step S14, 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
TCS control is executed based on the S control output value (step S20). Thereafter, in step S22, SCS · E
The CU 10 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. 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 is omitted. FIG. 3 is a flowchart for executing the SCS operation processing of FIG.

As shown in FIG. 3, when the process is started,
In step S30, the SCS / ECU 10 determines the FR wheel speed v
1, FL wheel speed v2, RR wheel speed v3, RL wheel speed v4, vehicle speed
V, steering angle θ, actual yaw rate ψact, and actual lateral acceleration Yact are input. In step S32, SCS · E
The CU 10 calculates a vertical load generated in 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, SCS / EC
U10 calculates the actual sideslip angle βact actually generated in the vehicle. The actual sideslip angle βact is calculated by integrating the rate of change Δβact of the actual sideslip angle βact. Also, Δβa
ct is calculated by the following equation 1. Δβact = −ψact + Yact / V (1) Next, in step S34, the SCS · ECU 10
The reference value βref referred to in the calculation of the estimated sideslip angle βcont actually used for the S control is calculated. The reference value βref is based on the vehicle specifications and the vehicle state quantity (vehicle speed V, yaw rate ψact, actual lateral acceleration Yact, change speed Δβact of actual side slip angle βact, change amount (differential value) Δψ of yaw rate ψact.
act), estimated yaw moment D caused by braking
1.Estimated value D of the amount of lateral force reduction caused by braking
2 and is calculated using a two-degree-of-freedom model. In short, the reference value βref calculates the sideslip angle estimated based on the detected vehicle state quantity and the brake operation force. Then, in step S35, SCS / EC
U10 is an estimated side slip angle β actually used for SCS control.
Operate cont. The estimated sideslip angle βcont is calculated by solving a differential equation derived from the following Expressions 2 and 3. That is, Δβcont = Δβact + e + Cf · (βref−βcont) (2) Δe = Cf · (Δβref−Δβact-e) (3) where e: offset correction value of the yaw rate sensor and the lateral acceleration sensor Cf: cutoff frequency Further, as will be described later in detail, the cutoff frequency Cf corrects the estimated sideslip angle 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 generated at t, and is corrected so as to be smaller as the reliability of the reference value βref is lower. Also, the reference value βre
The low reliability of f is due to the cornering power Cp of the front wheels
f or when the cornering power Cpr of the rear wheel changes.

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 that are target values to converge the actual yaw rate Δact and the estimated sideslip angle βcont. Target yaw rate ψTR is vehicle speed
V, the road surface friction coefficient μ calculated in step S40 and the front wheel steering angle θH are estimated and calculated by a well-known mathematical method. Further, 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 θH: front wheel steering angle M: body mass 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 lag Represents a multiplier. For example, "L @
"2" means the square of L, and the same applies to the following description.

Next, in step S44 shown in FIG.
The CS / ECU 10 calculates the absolute value of the value obtained by subtracting the estimated sideslip angle βcont from the target sideslip angle βTR as the SCS control start threshold β
It is determined whether it is 0 or more (| βTR−βcont | ≧ β0?).
In step S44, the estimated sideslip angle β is calculated from the target sideslip angle βTR.
If the absolute value of the value obtained by subtracting cont is equal to or greater than the SCS control start threshold value β0 (Yes in step S44), step S46 is performed.
To set the SCS control target value to the target side slip angle βTR. On the other hand, if the absolute value of the value obtained by subtracting the estimated sideslip angle βcont from the target sideslip angle βTR in step S44 does not exceed the SCS control start threshold β0 (No in step S44), the process proceeds to step S52, and the SCS / ECU 10 sets the target yaw rate. It is determined whether or not the absolute value of the value obtained by subtracting the actual yaw rate ψact from ψTR is equal to or greater than the SCS control start threshold ψ0 (| ψ
TR−ψact | ≧ ψ0? ). If 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 in step S52 (Yes in step S52), the process proceeds to step S54 to set the SCS control target value to the target yaw rate ψTR. On the other hand, step S52
If 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 (No in step S52), the process returns to step S30 to repeatedly execute the above processing.

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

[Arbitration process between SCS control and ABS control] Next, the SCS control and the arbitration process between the SCS control and the ABS control will be described with reference to FIGS. 5 to 7
5 is a flowchart for executing arbitration processing between SCS control and ABS control.

In the arbitration process described below, even if the SCS control start condition is satisfied, if the ABS control is being performed, the ABS control is prioritized, or 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.

Specific processing will be described.

As shown in FIG. 5, in step S58,
The SCS / ECU 10 determines whether a failure has occurred in the hydraulic control unit 30 or the like used for SCS control. If a failure has occurred in step S58 (yes in step S58)
s), the process proceeds to step S74, the SCS control is stopped, and the process returns to step S2 shown in FIG. 2 to repeatedly execute the above processing. On the other hand, if no failure has occurred in step S58 (No in step S58), the process proceeds to step S60. In step S60, the SCS / ECU 10 determines whether the SCS control flag F1 is set to "1". When the SCS control flag F1 is set to "1", it indicates that the SCS control is being executed. Step S60
If the SCS control flag F1 is set to "1" in step S60 (Yes in step S60), the process proceeds to step S76 to determine whether the ABS control flag F2 is set to "1". When the ABS control flag F2 is set to "1", it indicates that the ABS control is being executed. On the other hand, if the SCS control flag F1 is not set to "1" in step S60 (No in step S60), step S6
Proceeding to 2, it is determined whether the ABS control is being executed. If the ABS control is being executed in step S62 (Yes in step S62), the process proceeds to step S80 described later. On the other hand, when the ABS control is not being executed in step S62 (step S62).
(No at 62), the process proceeds to step S64. Step S64
Then, the SCS / ECU 10 determines whether or not the TCS control is being executed. If the TCS control is being executed in step S64 (Yes in step S64), the process proceeds to step S78 and T
The braking control in the CS control is stopped (that is, only the torque down control by the engine can be executed), and the process proceeds to step S66. On the other hand, if the TCS control is not being executed in step S64 (No in step S62), step S6
Proceed to 6.

In step S66, the SCS-ECU 10
Calculates the SCS control target wheel, calculates the target slip ratio to be allocated to the selected wheel, and calculates the SCS control amount βamt or Δamt 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 SC control is performed in step S72.
After setting the S control flag F1 to "1", the process returns to step S2 to repeatedly execute the above processing.

In step S76, the ABS control flag F2 is set to "
1 "(Ye in step S76)
s), and proceed to step S80 shown in FIG. Step S8
At 0, the SCS-ECU 10 corrects the ABS control amount based on the SCS control amount βamt or ψamt. Thereafter, in step S82, the SCS-ECU 10 determines whether the ABS control has been completed. If the ABS control is not completed in step S82 (No in step S82), the SCS control flag F1 is set to "1" in step S84, and the ABS control flag F2 is set to "1" in step S86. It returns to step S30. On the other hand, if the ABS control is completed in step S82 (Yes in step S82), the SCS control flag is set in step S88.
F1 is reset to "0" and AB is set in step S90.
The S control flag F2 is reset to "0" and the above-described step S
It returns to 30.

Further, at step S76, an ABS control flag is set.
If F2 is not set to "1" (No in step S76), the process proceeds to step S92 shown in FIG. Step S
At 92, the SCS-ECU 10 determines whether or not the brake pedal pressure PB is equal to or greater than a predetermined threshold value P0 (PB ≧ P0?). If the brake depression force PB is equal to or more than the predetermined threshold value P0 in step S92 (Yes in step S92), the process proceeds to step S94, where the SCS control is stopped, and the process is switched to ABS control in step S96. Then, in a step S98, the ABS control flag F2 is set to "1", and the process returns to the step S30. On the other hand, in step S92, the brake pedal pressure PB
Does not exceed the predetermined threshold value P0 (N in step S92).
o), and proceed to step S100. In step S100, the SCS-ECU 10 determines whether the SCS control has been completed. If the SCS control has not been completed in step S100 (No in step S100), the process returns to step S68 to execute the subsequent processing. on the other hand,
If the SCS control is completed in step S100 (Yes in step S100), the SCS control flag F1 is reset to "0" in step S102, and the step S1 is performed.
In step 04, the ABS control flag 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 is a flowchart for executing the wheel speed correction processing of FIG. FIG. 9 is a schematic diagram showing the procedure for correcting the wheel speed.

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 the drive wheel, it is erroneously determined that the normal wheel, which is the other drive wheel, is spinning.

The normal wheel has a maximum error of 5% in its diameter, and the variation of the wheel speed based on this error is SCS.
Affect control.

As shown in FIG. 9, when the process 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 or deceleration or corner traveling where the reliability of the wheel speed is reduced. Step S11
2 when the vehicle is not traveling normally (N in step S112)
o), and return to step S110. If the vehicle is traveling normally in step S112 (step S112
Yes), the process proceeds to step S114 and the SCS-ECU
10 is FR wheel speed v1, FL wheel speed v2, RR wheel speed v3, R
It is determined whether any one of the L wheel speeds v4 is equal to or greater than a predetermined threshold value va. When one of the wheels is equal to or larger than the predetermined threshold value va in step S114 (Yes in step S114), the process proceeds to step S116. On the other hand, if none of them exceeds the predetermined threshold in step S114 (N in step S114
o), the process proceeds to step S122 to execute the wheel speed correction for the normal wheel.

In step S116, the SCS ECU 1
A value of 0 determines whether or not a state in which only one wheel is equal to or greater than a predetermined threshold has continued for a predetermined time. If it is determined in step S116 that only one wheel is equal to or greater than the predetermined threshold for a predetermined time (Yes in step S116), the process proceeds to step S118. On the other hand, when the state in which only one wheel is equal to or more than the predetermined threshold has not continued for the predetermined time in step S116 (step S116).
At 116, the flow proceeds to step S122 to execute the wheel speed correction for the normal wheel. In step S118, the SCS-ECU 10 determines that one of the wheels is a tempered wheel because only one of the wheels has a predetermined threshold or more for a predetermined time. Then, in step S120, the SCS
The 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,
The FL wheel speed is corrected based on the FR wheel speed, and 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 another 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. FIG. 11 is a diagram showing a map 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 integral value of the actual side slip angle change amount Δβact, the integration error in the estimated sideslip angle βcont is caused by a slight output error of each sensor or the like. Cumulative. Estimated sideslip angle βcont
Is a value actually used in the SCS control, and if an error occurs in the estimated side slip angle βcont, there is a possibility that the actual control will be adversely affected.

Therefore, in this embodiment, the estimated sideslip angle β
The difference between the error amount generated in cont and the reference value βref (βref−β
cont), the error (βref−βcont) generated in the estimated sideslip angle βcont by approaching the estimated sideslip angle βcont to the reference value βref using the reference value βref as a reference value.
Is reset (βref ← βcont).

Here, the cutoff frequency Cf is a factor for determining a reset speed for bringing the estimated side slip angle βcont closer to the reference value βref. That is, to increase the reset speed, the cutoff frequency Cf is set to a large value. Conversely, to decrease the reset speed, the cutoff frequency Cf is increased.
It is sufficient to set f to a small value.

Referring to Equations 2 and 3, the difference (βref−βcont) between the reference value βref and the estimated sideslip angle βcont changes according to the cutoff frequency Cf. If the difference is a large value, the estimated sideslip angle βcont is equal to the reference value βre.
Since the convergence is made faster by f, the error correction speed becomes faster. Conversely, when the difference is a small value, the estimated side slip angle βcont is slowly converged by the reference value βref, so that the error correction speed becomes slow. As described above, the cutoff frequency Cf is a change factor of 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 a change occurs in the cornering power Cpf of the front wheels or the cornering power Cpr of the rear wheels.

The reference value βref is based on vehicle specifications and vehicle state quantities (vehicle speed V, yaw rate ψact, actual lateral acceleration Yact, Δβ
act, the side slip angle calculated from the yaw rate ψact change rate Δψact) and the like. Therefore, the reliability of the estimated side slip angle βcont can be determined by determining whether or not the reference value βref is reliable. Therefore, in the present embodiment, by changing the correction speed at which the error of the estimated sideslip angle βcont is reset to the reference value βref based on the reliability of the reference value βref, the reliability of the reference value βref and the estimated sideslip angle βcont is changed. The higher value is used as the value actually used for the control. For example, even when the vehicle is turning, the reference value β
The error accumulated in the estimated side slip angle βcont can be absorbed while the more reliable value of ref and the estimated side slip angle βcont is actually used for control. When the vehicle is traveling straight, the reference value βref is zero, so that the estimated side slip angle βcont is reset to zero and the error is absorbed.

Since 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 of the road surface, in this correction speed changing process (1), the road surface friction is changed. The reliability of the reference value βref is determined according to the coefficient μ, and the cutoff frequency Cf is corrected as described above to change the error correction speed.

Then, the reliability of the reference value βref is determined in accordance with the coefficient of friction μ of the road surface. If the reliability of the reference value βref is low, the cutoff frequency Cf is reduced to reduce the reference value βref.
To make the estimated side slip angle βcont actually used for control. 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. Thus, the reference value βref is actually used for control.

Next, specific processing will be described.

After step S42 in FIG. 3, the process proceeds to step S130 as shown in FIG.
0 determines whether or not the friction coefficient μ is equal to or smaller than a predetermined threshold value μ1 (μ ≦ μ1?). When the friction coefficient μ is equal to or smaller than the predetermined threshold value μ1 in step S130 (Yes in step S130)
s), the SCS-ECU 10 determines in step S132 that the reliability of the reference value βref is low, and subtracts a predetermined value k (k> 0) from the cutoff frequency Cf (Cf → Cf−k) in step S134. , The estimated side slip angle βcont based on the cutoff frequency Cf corrected in step S136.
Is corrected, the estimated side slip angle βcont is corrected. If the friction coefficient μ does not exceed the predetermined threshold value μ1 in step S130 (No in step S130),
In step S138, the SCS / ECU 10 sets the reference value βref
Is determined to be highly reliable, a predetermined value k is added (Cf → Cf + k) from the cutoff frequency Cf in step S140, and the estimated side slip angle βcont is corrected based on the corrected cutoff frequency Cf in step S136. Is increased to correct the estimated sideslip angle βcont. Then, FIG.
Go to step S44.

As described above, the reliability of the reference value βref is determined in accordance with the friction coefficient μ of the road surface, and the correction speed of the error of the estimated side slip angle βcont increases as the reliability of the reference value βref increases. The correction speed is corrected in such a manner that the lower the reliability of the reference value βref is, the lower the correction speed is. The correction speed is determined by the cutoff frequency Cf based on the map shown in FIG. That is, 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, a reference value βref that has a small integration error and does not affect SCS control
If the reliability of the reference value βref is high, the cutoff frequency Cf is increased to increase the correction speed for resetting the reference value βref to the reference value βref. If the value βref is unreliable,
The cutoff frequency Cf is reduced and slowly corrected to the reference value βref so that the estimated side slip angle βcont is actually used for control. Conversely, if the reliability of the reference value βref is high, the cutoff frequency Cf The reference value βref is actually used for control by correcting the estimated side slip angle βref more quickly, so that the side slip angle is periodically reset during steady driving to absorb the integration error as in the past. Since the correction speed can be changed even during turning of the vehicle, the stability during 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. FIG. 13 is a diagram showing a map for changing the correction speed for correcting the integration error of the estimated sideslip angle βcont.

Since the cornering power Cpf of the front wheels or the cornering power Cpr of the rear wheels changes depending on whether the road surface is a rough road, in the correction speed changing process (2), whether the road surface is a rough road is determined. Then, the reliability of the reference value βref is determined and the cutoff frequency is corrected to change the error correction speed.

Next, specific processing will be described. FIG.
The same processes as those of 0 are given the same numbers.

After step S42 in FIG. 3, the process proceeds to step S145 as shown in FIG.
0 determines whether or not the road surface is rough. Step S1
If the road surface is a bad road at 45 (Ye at step S145)
s), the SCS-ECU 10 determines in step S132 that the reliability of the reference value βref is low, and subtracts a predetermined value k from the cutoff frequency Cf in step S134 (Cf → Cf−).
k) Correction is performed, 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. Also,
If the road surface is not a rough road in step S145 (step S145)
145, No), and SCS · ECU1 in step S138.
0 determines that the reliability of the reference value βref is high, adds a predetermined value k to the cutoff frequency Cf (Cf → Cf + k) in step S140, and estimates based on the corrected cutoff frequency Cf in step S136. Side slip angle βcont
Is increased to correct the estimated side slip angle βcont. Thereafter, the process proceeds to step S44 in FIG.

As described above, the reliability of the reference value βref is determined depending on whether the road surface is rough or not, and the correction speed of the error of the estimated side slip angle βcont increases as the reliability of the reference value βref increases. And the correction is performed in such a way that the lower the reliability of the reference value βref is, the lower the correction speed is. The correction speed is determined by the cutoff frequency Cf based on the map shown in FIG. Is low, the cutoff frequency Cf is reduced and the reference value βref is slowly corrected so that the estimated side slip angle βcont is actually used for control. Conversely, when the reliability of the reference value βref is high, Is to increase the cut-off frequency Cf to increase the estimated sideslip angle βr
By making the reference value βref actually used for control by correcting it faster by ef, there is no need to periodically reset the sideslip angle to absorb the integration error during steady-state driving as in the past, and the vehicle turns. Since the correction speed can be changed even during the operation, the stability during the SCS control can be improved.

[Correction Speed Changing Process (3)] Next, another embodiment of the correction speed changing process will be described. FIG. 14 is a flowchart for executing a process of changing the correction speed for correcting the integration error of the estimated sideslip angle βcont. FIG. 15 is a diagram showing a map for changing the correction speed for correcting the integration error of the estimated sideslip angle βcont.

Since the cornering power Cpf of the front wheels or the cornering power Cpr of the rear wheels changes depending on whether or not the vehicle is traveling straight, in the correction speed changing process (3), the vehicle is traveling straight. The reliability of the reference value βref is determined according to whether or not there is, and the correction speed of the error is changed by correcting the cutoff frequency.

Next, specific processing will be described. FIG.
The same processes as those of 0 are given the same numbers.

After step S42 in FIG. 3, the process proceeds to step S150 as shown in FIG.
0 determines whether the steering angle θH is “0” (θH = 0?) To determine whether the vehicle is traveling straight. In step S150, the steering angle θH is “0”.
If not (No in step S150), 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
The predetermined value k is subtracted from f (Cf → 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. . If the steering angle θH is “0” in step S150 (step S15
0, Yes), and SCS · ECU 10 in step S138.
Determines that the reliability of the reference value βref is high, and determines in step S
At 140, a predetermined value k is added from the cutoff frequency Cf (Cf
→ Cf + k), and the estimated side slip angle βcont is corrected by increasing the correction speed of the error of the estimated side slip angle βcont based on the cutoff frequency Cf corrected in step S136. Thereafter, the process proceeds to step S44 in FIG.

As described above, the reliability of the reference value βref is determined depending on whether or not the vehicle is traveling straight, and the correction speed of the error of the estimated sideslip angle βcont is determined by the reliability of the reference value βref. The higher the value, the higher the correction, the lower the reliability of the reference value βref. The lower the reliability, the lower the correction. The correction is performed by the cutoff frequency Cf based on the map shown in FIG. If the reliability 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, and conversely, the reliability of the reference value βref is high. In this case, the cut-off 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. To reset the integration error Is eliminated, and the correction speed can be changed even during turning of the vehicle, so that the stability during SCS control can be improved.

[Correction Speed Changing Process (4)] Next, another embodiment of the correction speed changing process will be described. FIG. 16 is a flowchart for executing a process of changing the correction speed for correcting the integration error of the estimated sideslip angle βcont. FIG. 17 is a diagram showing a map for changing the correction speed for correcting the integration error of the estimated sideslip angle βcont.

Since the cornering power Cpf of the front wheels or the cornering power Cpr of the rear wheels changes according to the vehicle speed, in the correction speed changing process (4), the reliability of the reference value βref is determined in accordance with the vehicle speed and cut. The error correction speed is changed by correcting the off-frequency.

Next, specific processing will be described. FIG.
The same processes as those of 0 are given the same numbers.

After step S42 in FIG. 3, the process proceeds to step S155 as shown in FIG.
0 determines whether the vehicle speed V is equal to or higher than a predetermined threshold V1 (V
≧ V1? ). If the vehicle speed V is not equal to or greater than the predetermined threshold value V1 in step S155 (No in step S155), 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
The predetermined value k is subtracted from f (Cf → 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. . If the vehicle speed V is equal to or higher than the predetermined threshold value V1 in step S155 (step S150)
In step S138, the SCS-ECU 10 determines that the reliability of the reference value βref is high, and proceeds to step S1.
At step 40, a predetermined value k is added from the cutoff frequency Cf (Cf →
Cf + k), and corrects the estimated sideslip angle βcont by increasing the correction speed of the error of the estimated sideslip angle βcont based on the cutoff frequency Cf corrected in step S136.
Thereafter, the process proceeds to step S44 in FIG.

As described above, according to the vehicle speed V, the reference value βref
And the correction speed of the error of the estimated side slip angle βcont is corrected in a direction that increases as the reliability of the reference value βref increases, and corrected in a direction that decreases as the reliability of the reference value βref decreases. Since the correction speed is determined by the cutoff frequency Cf based on the map shown in FIG. 17, when the reliability of the reference value βref is low, the cutoff frequency Cf is reduced to slowly correct the reference value βref. Then, the estimated side slip angle βcont is actually used for control, and conversely, if 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 to obtain the reference value. By making βref actually used for control, there is no need to periodically reset the sideslip angle during steady driving to absorb integration errors as in the past, and the correction speed can be changed even during vehicle turning So S Stability can be improved at S control.

In order to more accurately determine the reliability of the reference value βref, the correction speed change processing (1) to (4) is performed.
May be appropriately combined and executed as a series of processes.

[Explanation of road surface inclination angle calculation method] Next, a road surface inclination angle calculation method will be described in detail. FIG.
8 is a flowchart for executing a road surface inclination angle calculation process.

In the method for calculating the road surface inclination angle according to the present embodiment,
The calculation of the road surface inclination angle is performed 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 Expression 7 or 8. (Vi ↑ 2-vi ↑ 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 · sin θ (8) where V: vehicle speed ψact: actual yaw rate Yact: actual lateral acceleration g: gravitational acceleration Here, Y1cal = (vi ↑ 2−vi ↑ 2) ) / 2 · L (9) Y2cal = V · ψact (10) In Expression 7, the first estimated lateral acceleration Y1c calculated from the left and right wheel speeds vi and vo and the wheel interval L between the inner and outer wheels.
al (see equation 9) and the actual lateral acceleration Yact, the road inclination angle θ is calculated. In equation 8, the second estimated lateral acceleration Y2ca calculated from the vehicle speed V and the actual yaw rate ψact is calculated.
The road surface inclination angle θ is calculated based on the deviation between l (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 or in at least one state of running on a rough road, accelerating, decelerating, or making a sharp turn as a vehicle running state, the equation 8 is used. Or the second estimated lateral acceleration Y2cal is repeatedly calculated, and the road surface inclination angle is calculated based on the average value, the maximum value, and the value weighted by a predetermined ratio. . In addition, the calculation of the road surface inclination angle θ needs to be corrected by bringing the road surface inclination angle θ close to “0” at a predetermined timing so that the detection error of each sensor is not affected. Set the road inclination angle θ to "0"
May be always 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. In addition, when the process is executed while the vehicle is traveling straight, the yaw rate ψ is set to “0”, the lateral acceleration is set to “0”, the steering angle θH is set to “0”, and the difference between the inner and outer wheel speeds is set to “0”. It is determined that the inclination angle θ is “0”. Further, 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 ψact, and is calculated from the vehicle speed V and the steering angle θH. The second estimated lateral acceleration Y2cal is always equal to the actual lateral acceleration Yact, and the first estimated yaw rate Y1cal calculated from the inner and outer wheel speed difference is always equal to the actual yaw rate Yact, and is calculated from the inner and outer wheel speed difference. The calculated second estimated lateral acceleration ψ2cal is the actual lateral acceleration ψac
The presence or absence of the road surface inclination angle θ can be estimated using the property that does not coincide with t.

Next, specific processing will be described.

Step S50 or S56 in FIG.
After calculating the SCS control amount βamt or ψamt, the process proceeds to step S160 as shown in FIG.
U10 determines whether the vehicle is turning sharply by determining whether the steering angle θH is equal to or greater than a predetermined threshold value θ1 (θH ≧ θ1?). If the steering angle θH does not exceed the predetermined threshold value θ1 in step S160 (No in step S160), the process proceeds to step S162, and if the steering angle θH is equal to or larger than the predetermined threshold value θ1 in step S160 (Yes in step S160). ), The process proceeds to step S172, and the second estimated lateral acceleration Y2ca calculated from the above equation 8, that is, from the vehicle speed V and the actual yaw rate ψact.
l and the actual lateral acceleration Yact
Is calculated.

In step S162, the SCS ECU 1
A value of 0 determines whether the vehicle is traveling on a rough road. If the vehicle is not traveling on a rough road in step S162 (step S16
2 is No), the process proceeds to step S164, and the process proceeds to step S16.
2 and the vehicle is traveling on a rough road (Ye in step S162).
s), the process proceeds to step S172, and the road surface inclination angle θ is calculated by the above equation 8, that is, 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. .

In step S164, the SCS ECU 1
A value of 0 determines whether or not the vehicle is rapidly decelerating by determining whether or not the brake pedal pressure PB is equal to or greater than a predetermined threshold value P1 (PB ≧ P1?). If the brake depression force PB is not equal to or greater than the predetermined threshold value P1 in step S164 (N in step S164)
o) If the brake pedal pressure PB is equal to or more than the predetermined threshold value P1 in step S164 (Yes in step S164), the flow advances 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 lateral acceleration Y2cal and the actual lateral acceleration Yact.

In step S165, the SCS ECU 1
0 indicates that the vehicle acceleration ΔV (the differential value of the vehicle speed V) is equal to the predetermined threshold V2
It is determined whether or not the vehicle is rapidly accelerating by determining whether or not the above is the case (ΔV ≧ V2?). If the vehicle acceleration ΔV (the differential value of the vehicle speed V) is not equal to or greater than the predetermined threshold value V2 in step S165 (No in step S165), step S1 is performed.
Proceeding to step 66, if the vehicle acceleration ΔV (differential value of the vehicle speed V) is equal to or greater than the predetermined threshold value V2 in step S165 (Yes in step S165), the process proceeds to step S172 and the above equation (8), that is, the vehicle speed V and the actual yaw rate ψact Estimated lateral acceleration Y2cal and actual lateral acceleration Y calculated from
The road surface inclination angle θ is calculated based on the deviation of act.

At step S166, the SCS ECU 1
0 determines whether or not the wheel speed correction processing has been completed.
If the wheel speed correction process has not been completed in step S166 (No in step S166), the process proceeds to step S168, and if the wheel speed correction process has been completed in step S166 (Yes in step S166), the process proceeds to step S166.
Proceeding to 172, the second estimated lateral acceleration Y2cal calculated from the above equation 8, that is, from the vehicle speed V and the actual yaw rate ψact
Road surface inclination angle θ based on the deviation of the actual lateral acceleration Yact
Is calculated.

In step S168, the SCS ECU 1
0 determines whether or not a tempered wheel is mounted in the wheel speed correction processing. If the tempered wheel is not mounted in step S168 (No in step S168), the process proceeds to step S170. If the tempered wheel is mounted in step S168 (Yes in step S168), the process proceeds to step S172 to execute the above equation. 8, the road surface inclination angle θ is 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.

In step S170, the following equation 7 is used.
First estimated lateral acceleration Y1cal and actual lateral acceleration Y calculated from left and right wheel speeds vi and vo and wheel interval L between inner and outer wheels.
The road surface inclination angle θ is calculated based on the deviation of act.

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 and the traveling state quantity of the vehicle (steering steering angle θH, whether or not traveling on a rough road, brake pedal pressure PB, vehicle speed V
) Can be selected according to the value of the vehicle, so that even when the yaw rate is detected even when the steering angle is almost zero, such as when the vehicle is running on a sloped road, the error of the sideslip angle can be reduced. Erroneous control can be prevented.

[Description 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 values from the yaw rate sensor and the lateral acceleration sensor.
Is calculated by integrating the detected values, and errors are accumulated in the integrated value. For this reason, the absolute value of the value obtained by subtracting the estimated sideslip angle βcont from the target sideslip angle βTR tends to exceed the SCS control start threshold value β0, and there is a possibility that the SCS control may be erroneously intervened.

Thus, 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 θψ 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 a predetermined threshold value. If θB or more, the SCS control intervention threshold β0 shown in step S44 of FIG. 4 or the SCS control intervention threshold ψ0 shown in step S52 of FIG. 4 is increased to suppress the intervention of the SCS control, or the estimated side slip angle cont and The control based on 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 Process Based on SCS Control Start Threshold> First, the SCS shown in step S44 in FIG.
A method for suppressing the intervention of the SCS control by increasing the control intervention threshold β0 or the SCS control intervention threshold ψ0 shown in step S52 of FIG. 4 will be described. FIG. 19 is a flowchart for executing the control intervention suppression process based on the SCS control start threshold value.

As shown in FIG. 19, 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, the SCS / ECU 10 inputs the road surface inclination angle θv or θ 角 in step S174. I do. Then, in step S176, S
The CS / ECU 10 determines whether the road surface inclination angle θv or θ 又 は is equal to or larger than a predetermined threshold value θB. If the road surface inclination angle θv or θψ is not equal to or larger than the predetermined threshold value θB in step S176 (No in step S1176), step S44 in FIG.
If the road surface inclination angle θv or θψ is equal to or larger than the predetermined threshold θB in step S176 (Y in step S176).
es), and proceed to step S178. In step S178, the SCS-ECU 10 adds a predetermined value l (l> 0) to the SCS control start threshold value β0 or ψ0 (β0 → β0 + 1 or ψ0).
→ ψ0 + 1) to increase the SCS control start threshold, and
Go to step S44.

As described above, if the road surface inclination angle θv or θψ is equal to or larger than the predetermined threshold θB, the SCS control start threshold β0
Or, add a predetermined value l to ψ0 (β0 → β0 + 1 or ψ0 → ψ0
+1) to increase the SCS control start threshold value and suppress the SCS control intervention, thereby preventing 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 sideslip angle cont and the actual yaw rate ψac
A method of stopping the control based on t and switching to the control based on the SCS control amount Yamt calculated from the actual lateral acceleration Yact will be described. FIG. 20 is a flowchart for executing the SCS control switching process. FIG.
The same processes as those in No. 9 are given the same numbers.

As shown in FIG. 20, 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, the SCS / ECU 10 inputs the road surface inclination angle θv or θ 角 in step S174. I do. Then, in step S176, S
The CS / ECU 10 determines whether the road surface inclination angle θv or θ 又 は is equal to or larger than a predetermined threshold value θB. If the road surface inclination angle θv or θψ is not equal to or larger than the predetermined threshold value θB in Step S176 (No in Step S176), the process proceeds to Step S44 in FIG. 4, and if the road surface inclination angle θv or θψ is equal to or larger than the predetermined threshold value θB in Step S176. (Ye in step S176
s), and proceed to step S180. In step S180, the SCS-ECU 10 calculates the SCS control amount Yamt actually used for the SCS control, stops the control based on the estimated sideslip angle cont and the actual yaw rate ψact, and executes the control calculated from the actual lateral acceleration Yact. The control is switched to the control based on the amount Yamt, and 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 control based on the estimated side slip angle cont and the actual yaw rate ψact is stopped, and the control calculated from the actual lateral acceleration Yact is performed. By switching to the control based on the amount Yamt, erroneous intervention of the posture control can be prevented even while traveling on an inclined road surface.

[Description 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.
1 is a flowchart for executing a calculation process 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.

The specific processing will be described.

As shown in FIG. 21, 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, step S18
In step 4, the SCS-ECU 10 calculates a target lateral acceleration YTR as a target value to converge the actual lateral acceleration Yact. In step S186, the target lateral acceleration YTR
Is greater than or equal to a predetermined threshold Y1 (Yact ≦ Y
1? ). If the target lateral acceleration YTR is not equal to or larger than the predetermined threshold Y1 in step S186 (N in step S186)
o) In step S188, if the target lateral acceleration YTR is equal to or more than the predetermined threshold Y1 in step S186 (Yes in step S186), the flow advances to step S190, and the target lateral acceleration YTR is set to the predetermined threshold Y1. Proceed to step S188.

In step S188, the SCS-ECU 1
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 YT.
If it is not more than R (No in step S188), the process returns to step S30 in FIG. 3 to repeatedly execute the subsequent processing. On the other hand, in step S188, the actual lateral acceleration Y
If act is equal to or greater than the target lateral acceleration YTR (Yes in step S188), the process proceeds to step S192 to calculate the SCS control amount Yamt based on the target lateral acceleration YTR, and then proceeds to step S58 in FIG. Is repeatedly executed.

The SCS control method according to the road surface inclination angle θ described with reference to FIGS. 18 to 21 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. 22 is a flowchart for executing the SCS control intervention permission process based on the running state of the vehicle. FIG. 23 is a diagram showing 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, S
CS control is not executed.

To eliminate such adverse effects, the vehicle speed V,
The SCS control intervention permission area is provided by the steering angle θH, the change speed ΔθH of the steering angle θH, the change speed Δβact of the actual skid angle βact, the change speed Δψact of the actual yaw rate ψact, the friction coefficient μ of the road surface, etc. In situations where skidding is likely to occur, SCS control intervention is allowed.

The specific processing will be described.

As shown in FIG. 22, in step S200, the SCS / ECU 10 determines the vehicle speed V and the steering angle θ.
H, actual yaw rate ψact, and actual lateral acceleration Yact are input. Thereafter, in step S202, 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. When the current running state of the vehicle is within the SCS control intervention prohibition region A in step S202 (Yes in step S202), step S204.
And the current traveling state of the vehicle is changed to S in step S202.
If not in the CS control intervention inhibition area A (step S20)
(No in 2), the process proceeds to step S212, and SCS control intervention is permitted.

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?). If the change speed ΔθH of the steering angle θH is not equal to or greater than the predetermined threshold α1 in step S204 (No in step S204), step S206.
And if the change speed ΔθH of the steering angle θH is equal to or larger than the predetermined threshold α1 in step S204 (step S204).
(Yes in 204), the process proceeds to step S212, and SCS control intervention is permitted.

In step S206, the SCS ECU 1
0 is the change speed Δβact of the actual sideslip angle βact (actual sideslip angle βact
It is determined whether the differential value of act is equal to or greater than a predetermined threshold value α2 (Δβact ≧ α2?). If the change speed Δβact of the actual sideslip angle βact is not equal to or larger than the predetermined threshold α2 in step S206 (No in step S206), the process proceeds to step S208, and the change speed Δ of the actual sideslip angle βact in step S206.
When βact is equal to or more than the predetermined threshold α2 (step S206)
(Yes), the process proceeds to step S212, and SCS control intervention is permitted.

In step S208, the SCS / ECU 1
0 determines whether or not the rate of change Δψact 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?). If the change speed Δψact of the actual yaw rate ψact is not equal to or more than the predetermined threshold α3 in step S208 (No in step S208), step S210
If the change speed Δ act of the actual yaw rate ψact is equal to or more than the predetermined threshold α3 in step S208 (Yes in step S208), the process proceeds to step S208.
Proceeding to 212, SCS control intervention is permitted.

As described above, the vehicle speed V, the steering angle θH, the change speed ΔθH of the steering angle θH, the change speed Δβact of the actual sideslip angle βact, the change speed Δψact of the actual yaw rate ψact, the friction coefficient μ of the road surface, etc. 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 control prohibition area A, S
CS control intervention can be suppressed to prevent erroneous intervention.

[Description of SCS Control Method Based on SCS Control Operation Frequency] Next, a process of changing the SCS control start threshold based on the SCS control operation frequency will be described.
FIG. 24 is a flowchart for executing a process of changing the SCS control start threshold based on the operation frequency of the SCS control. FIG. 25 to FIG. 28 are diagrams showing maps for changing the SCS control start threshold.

In the above-described SCS control, it is possible to effectively suppress skidding and spin occurring in a running vehicle at the time of cornering, emergency avoidance of an obstacle, sudden change in road surface conditions, and the like.

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

Therefore, in the process of changing the SCS control start threshold based on the operation frequency of the SCS control described below, the operation frequency of the SCS control per unit time is detected, and when the operation frequency of the SCS control is high, the SCS control is performed. Correcting the start threshold value in the direction of decreasing the threshold value facilitates intervention in the SCS control. That is, for a driver who frequently operates the SCS control, the SC is controlled immediately before the vehicle reaches the limit.
By intervening in the SCS control well before the vehicle reaches the limit, rather than executing the S control, the safety for an inexperienced driver who relied on the SCS control is increased, and the engine torque particularly in the SCS control is increased. The down control will act as a warning for drivers who drive dangerously, such as when the SCS control operates frequently.

The specific processing will be described.

As shown in FIG. 24, in step S220, the SCS-ECU 10 determines the vehicle speed V and the steering angle θ.
H, Enter the friction coefficient μ of the road surface. In step S222, the SCS-ECU 10 calculates the operation frequency of the SCS control. 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. In step S224, the SCS-ECU 10
Is SC according to the operation frequency calculated in step S222.
Correct the S control start threshold β0, ψ0 (β0 → β0x0, ψ
0 → ψ0x0). That is, based on the map shown in FIG.
The SCS control start threshold β0, ψ0 is multiplied by a correction coefficient x0, and S
The SCS control start threshold β increases as the CS control operation frequency increases.
Correct so that 0 and ψ0 become smaller.

In step S226, the SCS ECU 1
0 further corrects the SCS control start threshold value β0, ψ0 corrected in step S224 according to the vehicle speed V (β0 → β0 · x0
・ X1, ψ0 → ψ0ψx0 ・ x1). That is, based on the map shown in FIG. 26, the SCS control start threshold value β0, ψ0 corrected in step S224 is multiplied by the correction coefficient x1, and the larger the vehicle speed V, the smaller the SCS control start threshold value β0, ψ0. to correct.

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 according to the steering angle θH (β0 → β0x0x1x2, ψ0 → ψ0x0x1x2). That is, based on the map shown in FIG.
SCS control start threshold value β0 corrected by
And the SCS control start threshold values β0 and ψ0 are further reduced as the steering angle θH increases.

At step S230, the SCS ECU 1
0 further corrects the SCS control start threshold value β0, ψ0 corrected in step S228 according to the road surface friction coefficient μ (β
0 → β0 ・ x0 ・ x1 ・ x2 ・ x3 、 ψ0 → ψ0 ・ x0 ・ x1 ・ x2 ・ x
3). That is, based on the map shown in FIG. 28, the SCS control start threshold value β0, ψ0 corrected in step S228 is multiplied by the correction coefficient x3.
Further correction is performed so that the control start threshold values β0 and ψ0 become smaller.

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). Step S2
If the target sideslip angle βTR or ΔTR has changed at 32 (Yes at step S232), the process proceeds to step S234. If the target sideslip angle βTR or ΔTR has not changed at step S232 (No at step S232), the process proceeds to step S236. move on.

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
SCS control start threshold value β0 corrected by
Is multiplied by SCS when the target sideslip angle βTR or ψTR changes, compared to when the actual sideslip angle βact or ψact changes.
The control start threshold value β0, is corrected so as to suppress the decrease amount of ψ0.

In the above embodiment, the SCS control start thresholds β0, ψ0 are set according to the operation frequency of the SCS control and the vehicle state quantity.
However, 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, 00 is corrected in a direction in which the SCS control is easy to start according to the vehicle state quantity, it is difficult to rely on the SCS control. In addition to increasing the safety for the driver, the engine torque-down control, particularly in the SCS control, acts as a warning for a driver who performs dangerous driving such that the SCS control frequently operates.

[Description of TCS Control Method During SCS Control] Next, TCS control during SCS control will be described. FIG. 29 is a flowchart for executing TCS control during SCS control.

In the above-described 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.

Therefore, in the SCS control described below,
By making it easier for the torque down control of the engine by the TCS control to be executed 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. 28, in step S250, SCS / ECU 10 determines whether or not SCS control is being performed. If SCS control is being performed in step S250 (Yes in step S250), the process proceeds to step S252.
If the SCS control is not being performed in step S250 (No in step S250), the process proceeds to step S262 to execute the normal control of the TCS, that is, the braking control for the wheels and the torque reduction control of the engine.

In 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% to make it easier to start the TCS control. In step S254, the SCS / ECU 1
A value of 0 changes the average value of the wheel speed, which is the reference of the TCS control, to the maximum value of the wheel speed (Select High), and makes it easier to start the TCS control in a situation where an apparently slipping wheel is likely to occur.

In 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 reduction control of the engine by the S control, the torque reduction 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-described SCS control, the change in the wheel speed is suppressed by making it easier to execute the torque reduction control of the engine by the TCS control during the SCS control.
As another method, the throttle valve 23 shown in FIG. 1 is controlled to open and close, and during SCS control, the opening of the throttle valve 23 is controlled to be constant so that the engine output becomes substantially constant. The generated wheel speed change can be suppressed.

The present invention can be applied to a modification or change of the above embodiment without departing from the gist of the invention.

[0131]

As described above, according to the present invention, the operation frequency of the posture control per predetermined period is detected, and the higher the operation frequency, the smaller the start threshold value of the posture control and the smaller the predetermined deviation. As a result, the safety for a poor driver who relies on the attitude control is enhanced, and the driver who performs a dangerous driving in which the attitude control is frequently activated is warned.

[0132]

[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 present 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 a correction speed of an error of an estimated side slip angle.

FIG. 11 is a diagram showing a map for changing a correction speed of an error of an estimated side slip angle.

FIG. 12 is a flowchart for executing processing (2) for changing a correction speed of an error of an estimated side slip angle.

FIG. 13 is a diagram showing a map for changing a correction speed of an error of an estimated side slip angle.

FIG. 14 is a flowchart for executing a process (3) for changing the correction speed of the error of the estimated side slip angle.

FIG. 15 is a diagram showing a map for changing a correction speed of an error of the estimated sideslip angle.

FIG. 16 is a flowchart for executing a process (4) for changing the correction speed of the error of the estimated sideslip angle.

FIG. 17 is a diagram showing a map for changing a correction speed of an error of an estimated side slip angle.

FIG. 18 is a flowchart for executing a road surface inclination angle calculation process.

FIG. 19 is a flowchart for executing a control intervention suppression process based on an SCS control start threshold.

FIG. 20 is a flowchart for executing SCS control switching processing.

FIG. 21 is a flowchart for executing a calculation process of an SCS control amount based on an actual lateral acceleration.

FIG. 22 is a flowchart for executing an SCS control intervention permission process based on a running state of a vehicle.

FIG. 23 is a diagram showing a map for changing an SCS control intervention permission area.

FIG. 24 is a flowchart for executing a process of changing the SCS control start threshold based on the operation frequency of the SCS control.

FIG. 25 is a diagram showing a map for changing an SCS control start threshold value.

FIG. 26 is a diagram showing a map for changing an SCS control start threshold.

FIG. 27 is a diagram showing a map for changing an SCS control start threshold.

FIG. 28 is a diagram showing a map for changing an SCS control start threshold.

FIG. 29 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 ... longitudinal 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 depression force sensor 36 ... Pressing 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 (7)

[Claims] An apparatus for controlling the attitude of a vehicle to a target value by converging the estimated value to a target value when a deviation between a target value and an estimated value of the vehicle state quantity is equal to or greater than a predetermined deviation, comprising: Detecting the operation frequency of the attitude control that converges the estimated value per the target value to a target value, reducing the start threshold value of the attitude control as the operation frequency increases, and reducing the predetermined deviation. Attitude control device. 2. The attitude control device for a vehicle according to claim 1, wherein when the attitude control intervenes with the change in the target value, the start threshold value is made smaller than when the attitude control intervenes with the change in the estimated value. . 3. The vehicle attitude control device according to claim 1, wherein the lower the coefficient of friction of the road surface, the more the amount of decrease in the start threshold value is suppressed. 4. The attitude control device for a vehicle according to claim 1, wherein the start threshold value is reduced as the vehicle speed increases. 5. The vehicle attitude control device according to claim 1, wherein the start threshold value is reduced as the steering angle increases. 6. The vehicle attitude control device according to claim 1, wherein the attitude control end threshold value is increased as the detection operation frequency increases. 7. The method according to claim 1, further comprising: detecting an operation ratio of the attitude control for causing the estimated value to converge to a target value; and decreasing the predetermined threshold by decreasing the attitude control start threshold as the operation ratio increases. The vehicle attitude control device according to claim 1.