JP4129700B2 - Vehicle attitude control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb the integrated error of a side slip angle and to improve stability during attitude control by integrating side slip angles computed on the basis of detected vehicle speed, steering angle, yaw rate and lateral acceleration, and bringing an estimated side slip angle close to the target value to change correction speed according to a travel state. SOLUTION: An SCS ECU 10 inputs FR wheel speed v1, FL wheel speed v2, RR wheel speed v3, RL wheel speed v4, vehicle speed V, a steering angle θ, a yaw rate ψ and lateral acceleration Y and computes vertical load. The SCS ECU 10 computes an actual side slip angle generated to a vehicle by integrating the change speed of the actual side slip angle. The SCS ECU 10 computes the reference value and an estimated side slip angle actually used for SCS control. Cutoff frequency is corrected so as to converge the estimated side slip angle according to the reliability of the reference value, and an integrated error generated to the estimated side slip angle is reset. A side slip and a spin generated to the traveling vehicle can therefore be suppressed effectively.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle attitude control device, for example, a vehicle attitude control device for suppressing side slip and spin of a running vehicle during cornering, emergency obstacle avoidance, and sudden change in road surface conditions.
[0002]
[Prior art]
Conventionally, there has been a control device that detects vehicle state quantities such as the yaw rate and steering angle of a running vehicle, and suppresses vehicle side slip and spin during cornering, emergency obstacle avoidance, and sudden changes in road surface conditions. Many proposals have been made.
[0003]
In JP-A-2-151568 and JP-A-2-151571, corrections corresponding to the crosswind and the road surface inclination with respect to the estimated values of the output amounts of two vehicle motions (for example, the yaw angular acceleration and the lateral acceleration at the center of gravity) are disclosed. Has been proposed to eliminate the estimation error of the vehicle state quantity.
[0004]
Japanese Patent Laid-Open No. 6-115418 proposes a method for executing distribution control only when it is really necessary by changing the distribution control start condition in accordance with the vehicle speed and the steering angle. In Japanese Patent Laid-Open No. 6-321077, a driving margin is detected in accordance with a driver's brake operating force, an accelerator pedal depression amount, and the like, and distribution control start conditions are determined based on the detected margin. Some changes have been proposed.
[0005]
[Problems to be solved by the invention]
However, in the above prior art, the side slip angle calculated as the vehicle state quantity is an integrated value of the lateral speed calculated by the yaw rate, the vehicle speed, and the lateral acceleration, so that even a slight output error of each sensor can be integrated. The error increases cumulatively, and the side slip angle must be periodically reset during steady running to absorb the integration error.
[0006]
The present invention has been made in view of such a problem, and the object of the present invention is to absorb the integration error of the skid angle calculated as the vehicle state quantity and improve the stability during the attitude control. It is to provide a control device.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, a vehicle attitude control device according to the present invention has the following configuration. That is,
An apparatus for controlling the attitude of the vehicle so that the estimated side slip angle converges to the target side slip angle when the deviation between the target side slip angle calculated based on the vehicle state quantity and the estimated side slip angle exceeds a predetermined control start threshold. The vehicle speed detecting means for detecting the vehicle speed of the vehicle, the steering angle detecting means for detecting the steering angle of the vehicle, the yaw rate detecting means for detecting the yaw rate generated in the vehicle, and the lateral acceleration generated in the vehicle are detected. A lateral acceleration detecting means for calculating the estimated side slip angle by integrating the vehicle side slip speed calculated based on the vehicle speed, steering angle, yaw rate, and lateral acceleration detected by each means. Means, error correction means for correcting an error caused by integration of the estimated side slip angle by bringing the estimated side slip angle close to a target value, and the vehicle speed is large. And a threshold value correcting means for correcting such that the control start threshold value as had decreases, The target value is a reference value calculated based on a vehicle speed, a yaw rate, a lateral acceleration, a skid speed, a change rate of the yaw rate, The error correction means includes To approximate the estimated skid angle to the reference value. Above Reference value The correction speed to The reference value is changed based on the reliability that changes with the change in the cornering power of the front wheels or the cornering power of the rear wheels, and when the reliability of the reference value is low, the correction speed decreases so as to be slow. When the reference value is highly reliable, the correction speed is increased so that the correction speed increases. To do.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0009]
[Control block configuration of attitude control device]
First, the control block configuration of the vehicle attitude control device 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.
[0010]
As shown in FIG. 1, the attitude control device of the present embodiment suppresses the side slip and spin of a traveling vehicle when the traveling state of the vehicle is, for example, cornering, emergency obstacle avoidance, or a sudden change in road surface conditions. In order to achieve this, the braking force to the front and rear, left and right wheels is controlled. Each wheel is provided with an FR (right front wheel) brake 31 such as a hydraulic disc brake, an FL (left front wheel) brake 32, an RR (right rear wheel) brake 33, and an RL (left rear wheel) brake 34. These FR, FL, RR, and RL brakes 31 to 34 are connected to the hydraulic control unit 30, respectively. The hydraulic control unit 30 is connected to each wheel cylinder (not shown) of the FR, FL, RR, and RL brakes 31 to 34, and applies braking force to each wheel by introducing hydraulic pressure to the wheel cylinders of the brakes 31 to 34. To do. 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 pressure of the brake pedal 38. The primary hydraulic pressure is introduced into the pressurizing unit 36, pressurized to the secondary hydraulic pressure by the pressurizing unit 36, and introduced into the hydraulic pressure control unit 30. The hydraulic control unit 30 is electrically connected to the SCSECU 10, and controls the braking force applied to each wheel by distributing the hydraulic pressure to the FR, FL, RR, and RL brakes 31 to 34 in accordance with a braking control signal from the ECU 10. To do.
[0011]
An SCS (STABILITY CONTROLLED SYSTEM) / ECU (ELECTRONIC CONTROLLED UNIT) 10 controls the braking of the front and rear wheels and the left and right wheels as an attitude control device of the present embodiment, and also performs a well-known ABS (anti-lock brake system) control. An arithmetic processing unit that also controls TCS (traction control system) control. The SCS / 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, a steering angle sensor 16, a yaw rate sensor 17, a lateral acceleration sensor 18, A longitudinal acceleration sensor 19, a brake pedal pressure sensor 35, an EGI ECU 20, and a TCS off switch 40 are connected.
[0012]
The outline of ABS control and TCS control will be explained. ABS control is to automatically control the braking force to the wheel when a sudden braking operation is performed while the vehicle is running and the wheel is likely to lock against the road surface. TCS control is a system that stops the vehicle while suppressing the lock of the wheel, and controls the driving force or braking force to each wheel to suppress the phenomenon that the wheel slips on the road surface while the vehicle is running. It is a system to let you.
[0013]
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 left front wheel to the SCS • 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 vehicle travel speed detection signal V to the SCS / ECU 10. The steering angle sensor 16 outputs a steering rotation angle detection signal θH to the SCS • ECU 10. The yaw rate sensor 17 outputs a detection signal ψ of the yaw rate actually generated in the vehicle body to the 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 a detection signal Z of the longitudinal acceleration actually generated in the vehicle body to the SCS / ECU 10. The brake pedal pressure sensor 35 is provided in the pressurizing unit 36 and outputs a detection signal PB of the pedal pressure of the brake pedal 38 to the SCS / ECU 10. The TCS off switch 40 is a switch that forcibly stops the spin control (traction control) of the wheel, which will be described later, and outputs this switch operation signal S to the SCS / ECU 10. An EGI (ELECTRONIC GASOLINE INJECTION) ECU 20 is connected to an engine 21, an AT (AUTOMATIC TRANSMISSION) 22, and a throttle valve 23, and controls output control of the engine 21, transmission control of the AT 22, and opening / closing control of the throttle valve 23.
[0014]
The SCS / ECU 10 and the EGI / ECU 20 include a CPU, a ROM, and a RAM, and execute an attitude control program and an engine control program stored in advance based on the input detection signals.
[0015]
[Outline explanation of attitude control]
In the posture control of the present embodiment, braking control is performed on each wheel to apply a turning moment and a deceleration force to the vehicle body to suppress a side slip of the front wheel or the rear wheel. 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 inward turning behavior. Also, when the front wheels are likely to skid to the sides of the turn (drift out), an appropriate amount of brake is applied to each wheel to apply an inward moment, while reducing the engine output and applying a deceleration force, turning radius Suppresses the increase of
[0016]
Although details of the attitude control will be described later, generally speaking, the SCS / ECU 10 detects that the vehicle speed sensor 15, the yaw rate sensor 17, and the lateral acceleration sensor 18 have detected the actual signals generated in the vehicle from the detection signals V, ψ, and Y. The side slip angle (hereinafter referred to as the actual side slip angle) βact and the actual yaw rate (hereinafter referred to as the actual yaw rate) ψact are calculated, and also referred to in the calculation of the estimated side slip angle βcont actually used for SCS control from the actual side slip angle βact. The reference value βref is calculated. Further, the SCS • ECU 10 calculates a target side slip angle βTR and a target yaw rate ψTR as a vehicle target posture from a detection signal from 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. Attitude control is started when the difference between ψact and target yaw rate ψTR exceeds predetermined threshold values β0 and ψ0, and control is performed so that the estimated actual skid angle βcont or actual yaw rate ψact converges to the target skid angle βTR or target yaw rate ψTR.
[0017]
[Detailed explanation of attitude control]
Next, attitude control (hereinafter referred to as SCS control) of this embodiment will be described in detail. FIG. 2 is a flowchart showing an overall operation for executing the posture control of the present embodiment.
[0018]
As shown in FIG. 2, first, when the ignition switch is turned on by the driver and the engine is started, the SCS • ECU 10 and the EGI • ECU 20 are initially set in step S2, and the sensor detection stored in the previous processing is performed. Clear the signal and operation value. 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, and the vehicle speed. Detection signal V of sensor 15, detection signal θH of steering angle sensor 16, detection signal ψ of yaw rate sensor 17, detection signal Y of lateral acceleration sensor 18, detection signal Z of longitudinal acceleration sensor 19, brake pedal pressure sensor 35 Detection signal PB and switch operation signal S of the TCS off switch 40 are input. In step S6, the SCS / ECU 10 calculates a vehicle state quantity based on the above detection signals. 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, control output value, etc. necessary for ABS control are calculated, and in step S12, a TCS control target value, control output value, etc. required for TCS control are calculated.
[0019]
In step S14, control output arbitration processing 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 respectively compared, and control is shifted to the control corresponding to the largest value. 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 force pressure PB. That is, if the ABS control output value is the largest value in step S14, the ABS control is executed based on the ABS control output value (step S16), and if the SCS control output value is the largest value, the SCS control output value. The SCS control is executed based on (step S18), and when the TCS control output value is the largest value, the TCS control is executed based on the TCS control output value (step S20). Thereafter, in step S22, the SCS / ECU 10 determines whether the hydraulic control unit 30 or the like is operating normally. If it is determined that there is an abnormality, the control corresponding to the abnormal part is stopped. Then, the process returns to step S2 to repeatedly execute the above-described processing.
[0020]
[Description of SCS processing]
Next, the details of the SCS calculation process shown in step S8 of FIG. 2 will be described. Since the ABS control calculation process and the TCS control calculation process in steps S10 and S12 are well known, the description thereof will be omitted. FIG. 3 is a flowchart for executing the SCS calculation process of FIG.
[0021]
As shown in FIG. 3, when the process is started, in step S30, the SCS • ECU 10 causes the FR wheel speed v1, FL wheel speed v2, RR wheel speed v3, RL wheel speed v4, vehicle speed V, steering angle θ, actual Enter the yaw rate ψact and the actual lateral acceleration Yact. In step S32, the SCS • ECU 10 calculates the 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, the SCS • ECU 10 calculates an actual side slip angle βact actually generated in the vehicle. The actual side slip angle βact is calculated by integrating the change rate Δβact of the actual side slip angle βact. Δβact is calculated by the following equation 1.
Δβact = −ψact + Yact / V (1)
Next, in step S34, the SCS • ECU 10 calculates a reference value βref that is referred to in the calculation of the estimated skid angle βcont that is actually used for SCS control. This reference value βref depends on the vehicle specifications, vehicle state quantity (vehicle speed V, yaw rate ψact, actual lateral acceleration Yact, actual skid angle βact change rate Δβact, yaw rate ψact change amount (differential value) Δψact), and brake. 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, the two-degree-of-freedom model is used for calculation. In short, the reference value βref calculates the side slip angle estimated based on the detected vehicle state quantity and the brake operation force. Thereafter, in step S35, the SCS • ECU 10 calculates an estimated side slip angle βcont actually used for the SCS control. The estimated side slip 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)
E: Offset correction value of yaw rate sensor and lateral acceleration sensor
Cf: Cut-off frequency
Further, as will be described in detail later, the cutoff frequency Cf is corrected so that the estimated side slip angle βcont converges to the reference value βref according to the reliability of the reference value βref, and an integration error generated in the estimated side slip angle βcont. Is a coefficient that is corrected so as to become smaller as the reliability of the reference value βref is lower. Further, the reliability of the reference value βref is lowered when a change occurs in the cornering power Cpf of the front wheels or the cornering power Cpr of the rear wheels.
[0022]
In step S36, the SCS • ECU 10 calculates the wheel slip ratio and wheel slip angle of each wheel. The wheel slip ratio and the wheel slip angle are estimated and calculated by a well-known mathematical method from the wheel speeds v1 to v4, the vehicle speed V, the estimated side slip angle βcont, and the front wheel steering angle θH of each wheel. In step S38, the SCS • ECU 10 calculates the load factor on each wheel. The wheel load factor is estimated and calculated by a well-known mathematical method from the wheel slip rate and wheel slip angle calculated in step S36 and the vertical load calculated in step S32. In step S40, the SCS • ECU 10 calculates the friction coefficient μ of the road surface during traveling. The friction coefficient μ of the road surface is estimated and calculated by a well-known mathematical method from the actual lateral acceleration Yact and the wheel load factor calculated in step S38. Next, in step S42, the SCS • ECU 10 calculates a target yaw rate ψTR and a target skid angle βTR, which are target values, in order to converge the actual yaw rate ψact and the estimated skid angle βcont. The target yaw rate ψTR is estimated and calculated by a well-known mathematical method from the vehicle speed V, the road surface friction coefficient μ calculated in step S40, and the front wheel steering angle θH. Further, the target side slip angle βTR is calculated by solving a 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)
V: Vehicle speed
θH: Front wheel steering angle
M: Body mass
I: Moment of inertia
L: foil base
Lf: Distance from the front wheel to the center of gravity of the vehicle
Lr: Distance from the rear wheel to the center of gravity of the vehicle
Cpf: Front wheel cornering power
Cpr: Rear wheel cornering power
C: Value corresponding to phase delay
In the above formula, “↑” represents a multiplier. For example, “L ↑ 2” means the square of L, and the same applies to the following description.
[0023]
Next, in step S44 shown in FIG. 4, the SCS / ECU 10 determines whether or not the absolute value of the value obtained by subtracting the estimated skid angle βcont from the target skid 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 skid angle βcont from the target skid angle βTR in step S44 is equal to or greater than the SCS control start threshold value β0 (Yes in step S44), the process proceeds to step S46 and the SCS control target value is set to the target skid angle βTR. Set. On the other hand, if the absolute value of the value obtained by subtracting the estimated side slip angle βcont from the target side slip angle βTR in step S44 does not exceed the SCS control start threshold value β0 (No in step S44), the process proceeds to step S52, and the SCS / ECU 10 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 (| ψTR−ψact | ≧ ψ0?). If the absolute value of the value obtained by subtracting the actual yaw rate ψact from the target yaw rate ψTR in step S52 is equal to or greater than the SCS control start threshold value ψ0 (Yes in step S52), the process proceeds to step S54, and the SCS control target value is set to the target yaw rate ψTR. On the other hand, when the absolute value of the value obtained by subtracting the actual yaw rate ψact from the target yaw rate ψTR in step S52 does not exceed the SCS control start threshold value ψ0 (No in step S52), the process returns to step S30 and the above-described processing is repeatedly executed.
[0024]
Next, in step S50, the SCS • ECU 10 calculates the SCS control amount βamt actually used for the SCS control. In step S56, the SCS • ECU 10 calculates the SCS control amount ψamt actually used for the SCS control.
[0025]
[Arbitration between SCS control and ABS control]
Next, arbitration processing between SCS control and SCS control and ABS control will be described with reference to FIGS. 5 to 7 are flowcharts for executing arbitration processing between the SCS control and the ABS control.
[0026]
In the arbitration process described below, even if the SCS control start condition is satisfied, if the ABS control is in progress, the ABS control is prioritized or the SCS control output value is corrected based on the ABS control output value. Further, when both the SCS control start condition and the ABS control start condition are satisfied, either control is executed according to the magnitude of the driver's brake pedal pressure PB.
[0027]
A specific process will be described.
[0028]
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 there is a failure in step S58 (Yes in step S58), the process proceeds to step S74, the SCS control is stopped, the process returns to step S2 shown in FIG. 2, and the above-described processing is repeatedly executed. On the other hand, if there is no failure in step S58 (No in step S58), the process proceeds to step S60. In step S60, the SCS • ECU 10 determines whether or not the SCS control flag F1 is set to “1”. The SCS control flag F1 indicates that SCS control is being executed when "1" is set. When 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 or not the ABS control flag F2 is set to “1”. The ABS control flag F2 indicates that ABS control is being executed when “1” is set. On the other hand, if the SCS control flag F1 is not set to “1” in step S60 (No in step S60), the process proceeds to step S62 to determine whether or not ABS control is being executed. When 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, if the ABS control is not being executed in step S62 (No in step S62), the process proceeds to step S64. In step S64, the SCS / ECU 10 determines whether TCS control is being executed. When the TCS control is being executed in step S64 (Yes in step S64), the process proceeds to step S78, the braking control in the TCS 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), the process proceeds to step S66.
[0029]
In step S66, the SCS / ECU 10 selects and calculates a wheel to be subjected to SCS control, calculates a target slip ratio to be distributed to the selected wheel, and calculates an SCS control amount βamt or ψamt corresponding to the target slip ratio. . Thereafter, in step S68, an engine control amount corresponding to a necessary torque reduction amount is calculated. Then, the SCS control is executed in step S70, and the SCS control flag F1 is set to "1" in step S72. Then, the process returns to the above step S2 and the above processing is repeatedly executed.
[0030]
If the ABS control flag F2 is set to “1” in step S76 (Yes in step S76), the process proceeds to step S80 shown in FIG. In step S80, 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 or not the ABS control has ended. In step S82, the ABS control has not ended (No in step S82). In step S84, the SCS control flag F1 is set to "1", and in step S86, the ABS control flag F2 is set to "1". The process 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 F1 is reset to "0" in step S88, and the ABS control flag F2 is reset to "0" in step S90. The process returns to step S30 described above.
[0031]
Furthermore, when the ABS control flag F2 is not set to “1” in step S76 (No in step S76), the process proceeds to step S92 shown in FIG. In step S92, 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 pedal pressure PB is greater than or equal to the predetermined threshold value P0 in step S92 (Yes in step S92), the process proceeds to step S94, the SCS control is stopped, and the control is switched to ABS control in step S96. In step S98, the ABS control flag F2 is set to "1", and the process returns to step S30. On the other hand, if the brake pedal pressure PB does not exceed the predetermined threshold value P0 in step S92 (No in step S92), the process proceeds to step S100. In step S100, the SCS / ECU 10 determines whether or not the SCS control is finished. In step S100, the SCS control is not finished (No in step S100), and the above-described step S6. 6 Return to, and 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 ABS control flag F2 is reset to “0” in step S104. The process returns to step S30 described above.
[0032]
[Description of wheel speed correction processing]
Next, the details of the wheel speed correction process shown in step S7 of FIG. 2 will be described. FIG. 8 is a flowchart for executing the wheel speed correction process of FIG. FIG. 9 is a schematic diagram showing a wheel speed correction procedure.
[0033]
For example, auxiliary wheels used for puncture (hereinafter referred to as tempered wheels) are about 5 to 15% smaller in diameter than normal wheels, and have higher wheel speeds than other normal tires. The wheel speed correction process is executed in order to remove the adverse effects caused by such variations in the diameters of the tempered wheel and the normal wheel. The adverse effects are as shown below. That is,
(1) In ABS control, if the wheel speed is high for only one wheel, the reference vehicle speed is raised and it is erroneously determined that normal wheels other than the tempered wheels tend to lock.
[0034]
{Circle around (2)} In TCS control, if a temper wheel is attached to a drive wheel, it is erroneously determined that the normal wheel that is the other drive wheel is spinning.
[0035]
(3) Normal wheels have a maximum error of 5% in diameter, and variations in wheel speed based on this error affect SCS control.
[0036]
Figure 8 When the process is started, the SCS • ECU 10 inputs the FR wheel speed v1, the FL wheel speed v2, the RR wheel speed v3, and the RL wheel speed v4 in step S110. In step S112, the SCS • ECU 10 determines whether or not the vehicle is in steady running. This steady running means a state that is not during extreme acceleration / deceleration or corner running where the reliability of the wheel speed is reduced. If the vehicle is not in steady running in step S112 (No in step S112), the process returns to step S110. Further, when the vehicle is in steady driving in step S112 (Yes in step S112), the process proceeds to step S114, and the SCS • ECU 10 is any one of FR wheel speed v1, FL wheel speed v2, RR wheel speed v3, and RL wheel speed v4. It is determined whether the wheel is equal to or greater than a predetermined threshold value va. If any one wheel is greater than or equal to the predetermined threshold va in step S114 (Yes in step S114), the process proceeds to step S116. On the other hand, if none of the predetermined threshold values is exceeded in step S114 (No in step S114), the process proceeds to step S122 to execute wheel speed correction for the normal wheels.
[0037]
In step S116, the SCS • ECU 10 determines whether or not a state where only one wheel is equal to or greater than the 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 value for a predetermined time (Yes in step S116), the process proceeds to step S118. On the other hand, if the state where only one wheel is equal to or greater than the predetermined threshold value does not continue for a predetermined time in step S116 (No in step S116), the process proceeds to step S122, and the wheel speed correction for the normal wheel is executed. In step S118, the SCS • ECU 10 determines that only one wheel is a tempered wheel because a state in which only one wheel is equal to or greater than the predetermined threshold has continued for a predetermined time. In step S120, the SCS • ECU 10 executes wheel speed correction for the temper wheel.
[0038]
The wheel speed correction for the normal wheel or the temper wheel is executed according to procedures (1) to (3) shown in FIG. That is,
(1) Correct RR wheel speed based on FR wheel speed, then (2) Correct FL wheel speed based on FR wheel speed, and finally (3) RL wheel speed based on FL wheel speed. to correct. However, when the FR wheel is a tempered wheel, the reference wheel is set to another wheel.
[0039]
[Correction speed change process (1)]
Next, a correction speed changing process for correcting an error accumulated by integration of the estimated side slip angle βcont by bringing the estimated side slip angle βcont close to the reference value βref in the SCS control will be described. FIG. 10 is a flowchart for executing a correction speed changing process for correcting the integral error of the estimated skid angle βcont. FIG. 11 is a diagram showing a map for changing the correction speed for correcting the integral error of the estimated side slip angle βcont.
[0040]
Since the estimated side slip angle βcont calculated by the above formulas 2 and 3 includes the integral value of the actual side slip angle change amount Δβact, an integration error is accumulated in the estimated side slip angle βcont due to a slight output error or the like of each sensor. . Since the estimated side slip angle βcont 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.
[0041]
Therefore, in the present embodiment, the amount of error occurring in the estimated skid angle βcont is determined from the difference (βref−βcont) from the reference value βref, and the estimated skid angle βcont is brought close to the reference value βref using the reference value βref as a reference value. As a result, the error (βref−βcont) occurring in the estimated side slip angle βcont is reset (βref ← βcont).
[0042]
Here, the cut-off frequency Cf is a factor that determines a reset speed at which the estimated skid angle βcont approaches the reference value βref. That is, when the reset speed is increased, the cut-off frequency Cf is set to a large value, and when the reset speed is decreased, the cut-off frequency Cf is set to a small value.
[0043]
Referring to Equations 2 and 3, the difference between the reference value βref and the estimated skid angle βcont (βref−βcont) changes according to the cutoff frequency Cf. When the difference is a large value, the estimated side slip angle βcont is converged faster by the reference value βref, so that the error correction speed is increased. On the other hand, 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. Thus, the cutoff frequency Cf is a factor for changing the error correction speed, and is a coefficient that is corrected so as to decrease as the reliability of the reference value βref decreases. Further, the reliability of the reference value βref is lowered when a change occurs in the cornering power Cpf of the front wheels or the cornering power Cpr of the rear wheels.
[0044]
The reference value βref is a skid angle calculated from vehicle specifications, vehicle state quantities (vehicle speed V, yaw rate ψact, actual lateral acceleration Yact, Δβact, change rate Δψact of yaw rate ψact), and the like. Therefore, the reliability of the estimated skid angle βcont can be determined by determining whether or not the reference value βref is reliable.
Therefore, in the present embodiment, the reliability of the reference value βref and the estimated skid angle βcont is improved by changing the correction speed for resetting the error of the estimated skid angle βcont to the reference value βref based on the reliability of the reference value βref. The higher value is actually used for control. For example, even when the vehicle is turning, the more reliable value of the reference value βref and the estimated skid angle βcont is actually controlled. The error accumulated in the estimated side slip angle βcont can be absorbed. When the vehicle is traveling straight ahead, the reference value βref is zero, so the estimated side slip angle βcont is reset to zero and the error is absorbed.
[0045]
The front wheel cornering power Cpf or the rear wheel cornering power Cpr, which changes the reliability of the reference value βref, changes according to the friction coefficient of the road surface. Therefore, in this correction speed changing process (1), the road surface friction coefficient μ Accordingly, the reliability of the reference value βref is determined, and the error correction speed is changed by correcting the cutoff frequency Cf as described above.
[0046]
Then, the reliability of the reference value βref is determined according to the friction coefficient μ of the road surface. If the reliability of the reference value βref is low, the cut-off frequency Cf is decreased and the correction is made slowly to the reference value βref. If the skid angle βcont is actually used for control, and the reliability of the reference value βref is high, the cutoff frequency Cf is increased. Reference value The reference value βref is actually used for control by correcting faster by βref.
[0047]
Next, specific processing will be described.
[0048]
After step S42 in FIG. 3, as shown in FIG. 10, the process proceeds to step S130, where the SCS • ECU 10 determines whether the friction coefficient μ is equal to or less than a predetermined threshold value μ1 (μ ≦ μ1?). When the friction coefficient μ is equal to or smaller than the predetermined threshold μ1 in step S130 (Yes in step S130), the SCS • ECU 10 determines in step S132 that the reliability of the reference value βref is low, and in step S134, the predetermined value is determined from the cutoff frequency Cf. The value k (k> 0) is subtracted (Cf → Cf−k) to correct the estimated side slip angle βcont by reducing the error correction speed of the estimated side slip angle βcont based on the cut-off frequency Cf corrected in step S136. Correct. If the friction coefficient μ does not exceed the predetermined threshold μ1 in step S130 (No in step S130), the SCS • ECU 10 determines that the reliability of the reference value βref is high in step S138, and the cutoff frequency Cf is determined in step S140. Then, a predetermined value k is added (Cf → Cf + k) to correct, 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 cut-off frequency Cf corrected in step S136. Then, it progresses to step S44 of FIG.
[0049]
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 is corrected so as to increase as the reliability of the reference value βref increases. The reference value βref is corrected so as to decrease as the reliability is low, and 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 that causes an integration error in the estimated side-slip angle βcont is low, the correction speed for reducing the cut-off frequency Cf and resetting the integration error to the reference value βref is slow, On the other hand, when the reliability of the reference value βref is so high that the integration error is small and does not affect the SCS control, the correction speed for increasing the cutoff frequency Cf and resetting to the reference value βref is increased. The reliability of the reference value βref is determined according to the friction coefficient μ, and when the reliability of the reference value βref is low, the estimated side slip angle βcont is set by reducing the cut-off frequency Cf and slowly correcting the reference value βref. If the reference value βref is highly reliable, the cutoff frequency Cf is increased. Reference value By correcting faster by βref so that the reference value βref is actually used for control, there is no need to periodically reset the skid angle during steady running to absorb integration error, and turn the vehicle Since the correction speed can be changed, the stability during SCS control can be improved.
[0050]
[Correction speed change process (2)]
Next, another embodiment of the correction speed changing process will be described. FIG. 12 is a flowchart for executing a correction speed changing process for correcting the integral error of the estimated side slip angle βcont. FIG. 13 is a diagram showing a map for changing the correction speed for correcting the integral error of the estimated side slip angle βcont.
[0051]
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 bad road or not, in this correction speed changing process (2), the reference value depends on whether the road surface is a bad road or not. The error correction speed is changed by judging the reliability of βref and correcting the cutoff frequency.
[0052]
Next, specific processing will be described. Note that the same numbers are assigned to processes similar to those in FIG.
[0053]
After step S42 in FIG. 3, FIG. 2 In step S145, the SCS • ECU 10 determines whether or not the road surface is a bad road. If the road surface is a bad road in step S145 (Yes in step S145), the SCS • ECU 10 determines that the reliability of the reference value βref is low in step S132, and subtracts the predetermined value k from the cutoff frequency Cf in step S134. (Cf → Cf−k) is corrected, and the estimated side slip angle βcont is corrected by slowing down the error correction speed of the estimated side slip angle βcont based on the cutoff frequency Cf corrected in step S136. If the road surface is not a rough road in step S145 (No in step S145), the SCS • ECU 10 determines in step S138 that the reliability of the reference value βref is high, and in step S140, the predetermined value k is determined from the cutoff frequency Cf. The addition (Cf → Cf + k) is corrected, and the estimated side slip angle βcont is corrected by increasing the error correction speed of the estimated side slip angle βcont based on the cut-off frequency Cf corrected in step S136. Then, it progresses to step S44 of FIG.
[0054]
As described above, the reliability of the reference value βref is determined depending on whether or not the road surface is a bad road, and the error correction speed of the estimated side slip angle βcont increases in a direction that increases as the reliability of the reference value βref increases. When the reliability of the reference value βref is low, the correction is made in such a direction that it decreases as the reliability of the reference value βref decreases, and the correction speed is determined by the cutoff frequency Cf based on the map shown in FIG. In this case, the cut-off frequency Cf is decreased and slowly corrected to the reference value βref so that the estimated side slip angle βcont is actually used for control. On the contrary, when the reliability of the reference value βref is high, Increase off frequency Cf Reference value By making the reference value βref actually used for control by correcting faster by βref, it is not necessary to reset the side slip angle periodically during steady running to absorb the integration error as in the past, and the vehicle turns Since the correction speed can be changed, the stability during SCS control can be improved.
[0055]
[Correction speed change process (3)]
Next, another embodiment of the correction speed changing process will be described. FIG. 14 is a flowchart for executing a correction speed changing process for correcting the integral error of the estimated skid angle βcont. FIG. 15 is a diagram showing a map for changing the correction speed for correcting the integral error of the estimated side slip angle βcont.
[0056]
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 ahead, in this correction speed changing process (3), it is determined whether or not the vehicle is traveling straight ahead. Accordingly, the reliability of the reference value βref is determined, and the correction speed of the error is changed by correcting the cutoff frequency.
[0057]
Next, specific processing will be described. Note that the same numbers are assigned to processes similar to those in FIG.
[0058]
After step S42 in FIG. 3, as shown in FIG. 14, the process proceeds to step S150, and the SCS • ECU 10 determines whether the steering angle θH is “0” (θH = 0?). It is determined whether or not the vehicle is traveling straight ahead. When the steering angle θH is not “0” in step S150 (No in step S150), the SCS • ECU 10 determines in step S132 that the reliability of the reference value βref is low, and in step S134, a predetermined value is obtained from the cutoff frequency Cf. k is subtracted (Cf → Cf−k) and the estimated side slip angle βcont is corrected by slowing down the correction speed of the error of the estimated side slip angle βcont based on the cut-off frequency Cf corrected in step S136. If the steering angle θH is “0” in step S150 (Yes in step S150), the SCS • ECU 10 determines that the reliability of the reference value βref is high in step S138, and the cutoff frequency Cf is determined in step S140. Then, a predetermined value k is added (Cf → Cf + k) to correct, 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 cut-off frequency Cf corrected in step S136. Then, it progresses to step S44 of FIG.
[0059]
As described above, the reliability of the reference value βref is determined depending on whether or not the vehicle is traveling straight, and the error correction speed of the estimated side slip angle βcont increases as the reliability of the reference value βref increases. The reference value βref is corrected so as to decrease as the reliability of the reference value βref is low. The correction is performed by the cutoff frequency Cf based on the map shown in FIG. If it is low, the cut-off frequency Cf is decreased and slowly corrected to the reference value βref so that the estimated side slip angle βcont is actually used for control. On the contrary, when the reliability of the reference value βref is high Increase the cutoff frequency Cf Reference value By making the reference value βref actually used for control by correcting faster by βref, it is not necessary to reset the side slip angle periodically during steady running to absorb the integration error as in the past, and the vehicle turns Since the correction speed can be changed, the stability during SCS control can be improved.
[0060]
[Correction speed change process (4)]
Next, another embodiment of the correction speed changing process will be described. FIG. 16 is a flowchart for executing a correction speed changing process for correcting the integral error of the estimated skid angle βcont. FIG. 17 is a diagram showing a map for changing the correction speed for correcting the integral error of the estimated side slip angle βcont.
[0061]
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 according to the vehicle speed, and the cutoff frequency is determined. The correction speed of error is changed by correcting.
[0062]
Next, specific processing will be described. Note that the same numbers are assigned to processes similar to those in FIG.
[0063]
After step S42 in FIG. 3, as shown in FIG. 16, the process proceeds to step S155, where the SCS • ECU 10 determines whether the vehicle speed V is equal to or higher than a predetermined threshold value V1 (V ≧ V1?). If the vehicle speed V is not equal to or higher than the predetermined threshold value V1 in step S155 (No in step S155), the SCS • ECU 10 determines in step S132 that the reliability of the reference value βref is low, and in step S134, the predetermined value k is determined from the cutoff frequency Cf. Is subtracted (Cf → Cf−k), and the estimated side slip angle βcont is corrected by slowing down the correction speed of the error of the estimated side slip angle βcont based on the cut-off frequency Cf corrected in step S136. If the vehicle speed V is greater than or equal to the predetermined threshold value V1 in step S155 (Yes in step S150), the SCS • ECU 10 determines in step S138 that the reliability of the reference value βref is high, and the cut-off frequency Cf is determined in step S140. The predetermined value k is added (Cf → Cf + k) to correct, and the estimated side slip angle βcont is corrected by increasing the error correction speed of the estimated side slip angle βcont based on the cutoff frequency Cf corrected in step S136. Then, it progresses to step S44 of FIG.
[0064]
As described above, the reliability of the reference value βref is determined according to the vehicle speed V, and the correction speed of the error of the estimated skid angle βcont is corrected so as to increase as the reliability of the reference value βref increases. The correction is performed in such a direction that it decreases as the reliability of βref is lower, and the correction speed is determined by the cutoff frequency Cf based on the map shown in FIG. 17, so that the cutoff is performed when the reliability of the reference value βref is low. The estimated side slip angle βcont is actually used for control by decreasing the frequency Cf and slowly correcting it to the reference value βref. On the contrary, when the reliability of the reference value βref is high, the cutoff frequency Cf is increased. do it Reference value By making the reference value βref actually used for control by correcting faster by βref, it is not necessary to reset the side slip angle periodically during steady running to absorb the integration error as in the past, and the vehicle turns Since the correction speed can be changed, the stability during SCS control can be improved.
[0065]
In order to more accurately determine the reliability of the reference value βref, the correction speed changing processes (1) to (4) may be appropriately combined and executed as a series of processes.
[0066]
[Explanation of road slope calculation method]
Next, a road surface inclination angle calculation method will be described in detail. FIG. 18 is a flowchart for executing a road surface inclination angle calculation process.
[0067]
In the road surface inclination angle calculation method of this 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 road surface inclination angle θ is calculated using the following Expression 7 or Expression 8.
(Vi ↑ 2-vi ↑ 2) / 2 · L-Yact = g · sin θ (7)
Where vi: wheel speed of the inner ring
vo: Wheel speed of the outer ring
L: Wheel spacing between inner ring and outer ring
Yact: Actual lateral acceleration
g: Gravity acceleration
V · ψact−Yact = g · sinθ (8)
V: Vehicle speed
ψact: Actual yaw rate
Yact: Actual lateral acceleration
g: Gravity acceleration
here,
Y1cal = (vi ↑ 2-vi ↑ 2) / 2 · L (9)
Y2cal = V · ψact (10)
Then, in Expression 7, the road surface inclination angle is based on the deviation between the first estimated lateral acceleration Y1cal (see Expression 9) 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. θ is calculated, and in Equation 8, the road surface inclination angle θ is calculated based on the deviation between the second estimated lateral acceleration Y2cal (see Equation 10) calculated from the vehicle speed V and the actual yaw rate ψact and the actual lateral acceleration Yact. .
[0068]
The detected wheel speed is not always accurate, particularly in at least one of the states before the wheel speed correction process and during the rough road driving, acceleration, deceleration, and sudden turning as the vehicle driving state. The road surface inclination angle θ is calculated, or the second estimated lateral acceleration Y2cal is calculated repeatedly, and the road surface inclination angle is calculated based on the average value, the maximum value, and the value weighted at a predetermined ratio.
In addition, it is necessary to correct the calculation of the road surface inclination angle θ 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. The timing at which the road surface inclination angle θ approaches “0” may be executed slowly at any time, may be executed slowly according to the error generation speed of the lateral acceleration sensor, or executed while the vehicle is traveling straight ahead. May be. In addition, when it is executed while the vehicle is traveling straight, the road surface is subject to the conditions that the yaw rate ψ is “0”, the lateral acceleration is “0”, the steering angle θH is “0”, and the inner / outer wheel speed difference is “0”. The inclination angle θ is determined to be “0”.
In order to determine only the presence or absence of the road surface inclination angle, the first estimated yaw rate ψ1cal calculated from the vehicle speed V and the steering rudder angle θH does not match the actual yaw rate ψact, and is calculated from the vehicle speed V and the steering rudder angle θH. The second estimated lateral acceleration Y2cal always matches the actual lateral acceleration Yact, and the first estimated yaw rate Y1cal calculated from the inner and outer wheel speed difference always matches the actual yaw rate Yact and calculated from the inner and outer wheel speed difference. The presence / absence of the inclination angle θ of the road surface can be estimated using the property that the second estimated lateral acceleration ψ2cal thus made does not match the actual lateral acceleration ψact.
[0069]
Next, specific processing will be described.
[0070]
After calculating the SCS control amount βamt or ψamt in step S50 or step S56 in FIG. 4, the process proceeds to step S160 as shown in FIG. 18, and the SCS • ECU 10 determines whether the steering angle θH is equal to or greater than a predetermined threshold value θ1. Is determined (θH ≧ θ1?) To determine whether the vehicle is turning sharply. If the steering angle θH does not exceed the predetermined threshold θ1 in step S160 (No in step S160), the process proceeds to step S162. If the steering angle θH is equal to or larger than the predetermined threshold θ1 in step S160 (Yes in step S160). In step S172, the road surface inclination angle θ is calculated according to the above formula 8, that is, based on the deviation between the second estimated lateral acceleration Y2cal and the actual lateral acceleration Yact calculated from the vehicle speed V and the actual yaw rate ψact.
[0071]
In step S162, the SCS • ECU 10 determines whether or not the vehicle is traveling on a rough road. If the vehicle is not traveling on a rough road in step S162 (No in step S162), the process proceeds to step S164. If the vehicle is traveling on a rough road in step S162 (Yes in step S162), the process proceeds to step S172 and the above equation 8 is satisfied. That is, 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 calculated from the vehicle speed V and the actual yaw rate ψact.
[0072]
In step S164, the SCS • ECU 10 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 pedal pressure PB is not equal to or greater than the predetermined threshold P1 in step S164 (No in step S164), the process proceeds to step S165, and if the brake pedal pressure PB is equal to or greater than the predetermined threshold P1 in step S164 (Yes in step S164). Proceeding to step S172, the road surface inclination angle θ is calculated according to the above equation 8, that is, based on the deviation between the second estimated lateral acceleration Y2cal and the actual lateral acceleration Yact calculated from the vehicle speed V and the actual yaw rate ψact.
[0073]
In step S165, the SCS • ECU 10 determines whether or not the vehicle is rapidly accelerating by determining whether or not the vehicle acceleration ΔV (the differential value of the vehicle speed V) is equal to or greater than a predetermined threshold value V2 (ΔV ≧ V2?). If the vehicle acceleration ΔV (the differential value of the vehicle speed V) is not greater than or equal to the predetermined threshold value V2 in step S165 (No in step S165), the process proceeds to step S166, and the vehicle acceleration ΔV (the differential value of the vehicle speed V) is determined in step S165. If this is the case (Yes in step S165), the process proceeds to step S172 and 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 according to the above equation 8. Thus, the road surface inclination angle θ is calculated.
[0074]
In step S166, the SCS / ECU 10 determines whether or not the wheel speed correction process has been completed. If the wheel speed correction process is not completed in step S166 (No in step S166), the process proceeds to step S168. If the wheel speed correction process is completed in step S166 (Yes in step S166), the process proceeds to step S172. Then, 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 calculated from the vehicle speed V and the actual yaw rate ψact.
[0075]
In step S168, the SCS • ECU 10 determines whether or not a tempered wheel is mounted in the wheel speed correction process. If the temper wheel is not attached in step S168 (No in step S168), the process proceeds to step S170. If the temper wheel is attached in step S168 (Yes in step S168), the process proceeds to step S172 and the above formula is obtained. 8, that is, 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 calculated from the vehicle speed V and the actual yaw rate ψact.
[0076]
In step S170, the road surface inclination angle θ is calculated 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 in accordance with Equation 7 above. Is done.
[0077]
As described above, the calculation of the road surface inclination angle does not depend only on the yaw rate, but can also be calculated from the wheel speed difference between the inner and outer wheels, and the lateral acceleration and inner and outer wheels calculated from the yaw rate when calculating the road surface inclination angle. A more reliable value by switching the lateral acceleration calculated from the speed difference according to the running state amount of the vehicle (steering steering angle θH, whether the vehicle is traveling on a rough road, brake pedal pressure PB, vehicle speed V, etc.) Therefore, even when the yaw rate is detected even when the steering angle is substantially 0, such as when the vehicle is traveling on an inclined road surface, the error of the skid angle can be reduced to prevent erroneous control.
[0078]
[Description of SCS control according to road surface inclination angle]
Next, the SCS control corresponding to the road surface inclination angle calculated by the above-described road surface inclination angle calculation method will be described in detail.
[0079]
Normally, when the vehicle is always traveling on an inclined road surface, an error occurs in the detected value from the yaw rate sensor or the lateral acceleration sensor. Therefore, the estimated skid angle βcont is calculated by integrating these detected values. Errors are accumulated in the integrated value. For this reason, the absolute value of the value obtained by subtracting the estimated side slip angle βcont from the target side slip angle βTR easily exceeds the SCS control start threshold value β0, and there is a possibility that the SCS control intervention may be erroneously performed.
[0080]
Therefore, in the SCS control of the present embodiment, the road surface inclination calculated 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. Step S44 of FIG. 4 when the angle θv or θψ calculated based on the deviation between the second estimated lateral acceleration Y2cal and the actual lateral acceleration Yact calculated from the vehicle speed V and the actual yaw rate ψact is equal to or greater than the predetermined threshold θB. SCS control intervention threshold β0 shown in FIG. 4 or SCS control intervention threshold ψ0 shown in step S52 of FIG. 4 is increased to suppress SCS control intervention, or control based on the estimated skid angle cont and actual yaw rate ψact is stopped, The control is switched to the control based on the SCS control amount Yamt calculated from the actual lateral acceleration Yact.
[0081]
Next, specific processing will be described.
[0082]
<Control intervention suppression processing by SCS control start threshold>
First, a method for suppressing the intervention of the SCS control by increasing the SCS control intervention threshold value β0 shown in step S44 of FIG. 4 or the SCS control intervention threshold value φ0 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.
[0083]
As shown in FIG. 19, after calculating the road surface inclination angle θv from the left and right wheel speeds vi and vo in step S170 of FIG. 18 or calculating the road surface inclination angle θψ from the actual yaw rate ψact in step S172, in step S174, the SCS is calculated. The ECU 10 inputs a road surface inclination angle θv or θψ. Thereafter, in step S176, the SCS • ECU 10 determines whether or not the road surface inclination angle θv or θψ is equal to or greater than a predetermined threshold value θB. If the road surface inclination angle θv or θψ is not greater than or equal to the predetermined threshold value θB in step S176 (step S176) S1 If the road surface inclination angle θv or θψ is equal to or greater than the predetermined threshold value θB in step S176 (Yes in step S176), the process proceeds to step S178. In step S178, the SCS / ECU 10 increases the SCS control start threshold by adding a predetermined value l (l> 0) to the SCS control start threshold β0 or ψ0 (β0 → β0 + 1 or ψ0 → ψ0 + l), and step S44 in FIG. Proceed to
[0084]
As described above, if the road surface inclination angle θv or θψ is equal to or larger than the predetermined threshold θB, the predetermined value l is added to the SCS control start threshold β0 or ψ0 (β0 → β0 + l or ψ0 → ψ0 + l) to set the SCS control start threshold. By increasing the size and suppressing the SCS control intervention, it is possible to prevent erroneous intervention in posture control even when the vehicle is traveling on an inclined road surface.
[0085]
<Control intervention suppression process by switching SCS control>
Next, a method for stopping the control based on the estimated side slip angle cont and the actual yaw rate ψact 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. In addition, the same number is given about the process similar to FIG.
[0086]
As shown in FIG. 20, after calculating the road surface inclination angle θv from the left and right wheel speeds vi and vo in step S170 of FIG. 18 or calculating the road surface inclination angle θψ from the actual yaw rate ψact in step S172, in step S174, the SCS is calculated. The ECU 10 inputs a road surface inclination angle θv or θψ. Thereafter, in step S176, the SCS • ECU 10 determines whether or not the road surface inclination angle θv or θψ is equal to or greater than a predetermined threshold value θB. If the road surface inclination angle θv or θψ is not greater than or equal to the predetermined threshold value θB in step S176 (No in step S176), the process proceeds to step S44 of FIG. 4, and if the road surface inclination angle θv or θψ is greater than or equal to the predetermined threshold value θB in step S176. (Yes in step S176), the process proceeds 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 side slip angle cont and the actual yaw rate ψact, and performs the control calculated from the actual lateral acceleration Yact. Switching to the control based on the amount Yamt proceeds to step S44 in FIG.
[0087]
As described above, if the road surface inclination angle θv or θψ is equal to or larger than the predetermined threshold θB, the control based on the estimated side slip angle cont and the actual yaw rate ψact is stopped, and the control amount Yamt calculated from the actual lateral acceleration Yact is obtained. By switching to the control based on this, it is possible to prevent erroneous intervention in posture control even when traveling on an inclined road surface.
[0088]
[Description of Calculation Method of SCS Control Amount Based on Actual Lateral Acceleration]
Next, processing for calculating the SCS control amount Yamt from the lateral acceleration Yact in the SCS control in step S180 of FIG. 20 will be described. FIG. 21 is a flowchart for executing the calculation process of the SCS control amount based on the actual lateral acceleration.
[0089]
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.
[0090]
A specific process will be described.
[0091]
As shown in FIG. 21, in step S182, the SCS • ECU 10 calculates the maximum lateral acceleration Ymax allowed by the road friction coefficient μ, the actual lateral acceleration Yact, and the road friction coefficient μ. Thereafter, in step S184, the SCS • ECU 10 calculates a target lateral acceleration YTR that is a target value so as to converge the actual lateral acceleration Yact. In step S186, it is determined whether or not the target lateral acceleration YTR is equal to or greater than a predetermined threshold Y1 (Yact ≦ Y1?). If the target lateral acceleration YTR is not greater than or equal to the predetermined threshold Y1 in step S186 (No in step S186), the process proceeds to step S188, and if the target lateral acceleration YTR is greater than or equal to the predetermined threshold Y1 in step S186 (Yes in step S186). Proceeding to step S190, the target lateral acceleration YTR is set to a predetermined threshold Y1, and then proceeding to step S188.
[0092]
In step S188, the SCS • ECU 10 determines whether or not the actual lateral acceleration Yact is equal to or greater than the target lateral acceleration YTR (Yact ≦ YTR?). If the actual lateral acceleration Yact is not greater than or equal to the target lateral acceleration YTR in step S188 (No in step S188), the process returns to step S30 in FIG. 3 to repeat the subsequent processing. On the other hand, if the actual lateral acceleration Yact is greater than or equal to the target lateral acceleration YTR in step S188 (Yes in step S188), the process proceeds to step S192, and the SCS control amount Yamt is calculated based on the target lateral acceleration YTR. The process proceeds to step S58 of step 5 and the subsequent processing is repeatedly executed.
[0093]
Note that the SCS control method according to the road surface inclination angle θ described in FIGS. 18 to 21 can also be applied to a pressing force caused by a cross wind while the vehicle is traveling. In this case, instead of the road surface inclination angle θ, the pressing force by the cross wind may be calculated, and when the pressing force is equal to or greater than a predetermined threshold, the intervention of the SCS control may be suppressed.
[0094]
[SCS control intervention permission processing according to the running state]
Next, the SCS control intervention permission process according to the running state of the vehicle will be described. FIG. 22 is a flowchart for executing the SCS control intervention permission process according to the running state of the vehicle. FIG. 23 is a diagram showing a map for changing the SCS control intervention permission area.
[0095]
As described above, if the SCS control intervention is suppressed just because the vehicle is traveling while receiving an inclined road surface or a crosswind, the SCS control is not executed when a side slip actually occurs in the vehicle.
[0096]
In order to eliminate such adverse effects, the SCS is determined by the vehicle speed V, the steering angle θH, the change rate ΔθH of the steering angle θH, the change rate Δβact of the actual skid angle βact, the change rate Δψact of the actual yaw rate ψact, the friction coefficient μ of the road surface, etc. A control intervention permission area is provided so that SCS control intervention is permitted in a situation where a side slip is likely to occur in the vehicle.
[0097]
A specific process will be described.
[0098]
As shown in FIG. 22, 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. Thereafter, in step S202, it is determined whether or not the current running state of the vehicle is within the SCS control intervention prohibition area A determined by the steering angle θH, the vehicle speed V, and the road friction coefficient μ shown in FIG. If the current driving state of the vehicle is in the SCS control intervention prohibition area A in step S202 (Yes in step S202), the process proceeds to step S204, and the current driving state of the vehicle is in the SCS control intervention prohibition area A in step S202. If not (No in step S202), the process proceeds to step S212 to permit SCS control intervention.
[0099]
In step S204, the SCS • ECU 10 determines whether or not the change speed ΔθH of the steering angle θH (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), the process proceeds to step S206, and if the change speed ΔθH of the steering angle θH is equal to or greater than the predetermined threshold α1 in step S204 ( In step S204, Yes), the process proceeds to step S212, and SCS control intervention is permitted.
[0100]
In step S206, the SCS • ECU 10 determines whether or not the change rate Δβact (the differential value of the actual skid angle βact) of the actual skid angle βact is equal to or greater than a predetermined threshold value α2 (Δβact ≧ α2?). If the change rate Δβact of the actual skid angle βact is not greater than or equal to the predetermined threshold α2 in step S206 (No in step S206), the process proceeds to step S208, and if the change rate Δβact of the actual skid angle βact is greater than or equal to the predetermined threshold α2 in step S206 ( In step S206, Yes), the process proceeds to step S212 to permit SCS control intervention.
[0101]
In step S208, the SCS • ECU 10 determines whether or not the change rate Δψact of the actual yaw rate ψact (differential value of the actual yaw rate ψact) is equal to or greater than a predetermined threshold value α3 (Δψact ≧ α3?). If the change rate Δψact of the actual yaw rate ψact is not greater than or equal to the predetermined threshold α3 in step S208 (No in step S208), the process proceeds to step S210 and SCS control intervention is prohibited, and the change rate Δψact of the actual yaw rate ψact is greater than or equal to the predetermined threshold α3 in step S208. (Yes in step S208), the process proceeds to step S212, and SCS control intervention is permitted.
[0102]
As described above, SCS control intervention permission is permitted by vehicle speed V, steering rudder angle θH, steering rudder angle θH change rate ΔθH, actual side slip angle βact change rate Δβact, actual yaw rate ψact change rate Δψact, road surface friction coefficient μ, etc. By providing an area, SCS control intervention can be executed reliably in a situation where a skid is likely to occur in the vehicle, and an SCS control prohibition area that is highly likely to be running while receiving an inclined road surface or a crosswind. In A, SCS control intervention can be suppressed to prevent erroneous intervention.
[0103]
[Description of SCS Control Method Based on Operation Frequency of SCS Control]
Next, a process for changing the SCS control start threshold based on the operation frequency of the SCS control will be described. FIG. 24 is a flowchart for executing processing for changing the SCS control start threshold based on the operation frequency of SCS control. 25 to 28 are diagrams illustrating maps for changing the SCS control start threshold value.
[0104]
In the SCS control described above, it is possible to effectively suppress a skid and spin generated in a traveling vehicle during cornering, emergency obstacle avoidance, and sudden changes in road surface conditions.
[0105]
However, if the driver gets used to driving that relies on the SCS control described above, the driver's safety consciousness becomes weak, and he tends to drive in a state close to the limit area where SCS control is impossible, which may cause a safety problem. There is sex.
[0106]
Therefore, in the SCS control start threshold value changing process based on the SCS control operation frequency described below, the SCS control operation frequency per unit time is detected. If the SCS control operation frequency is high, the SCS control start threshold value is set. By making the correction in the decreasing direction, it is easy to intervene in the SCS control. That is, for the driver who operates the SCS control frequently, the SCS control is not executed immediately before the vehicle reaches the limit as in the original case, but is intervened in the SCS control sufficiently before the vehicle reaches the limit. As a result, the safety for the poor driver who relies on the SCS control is improved, and the torque reduction control of the engine in the SCS control is a commandment for the driver who performs dangerous driving such that the SCS control is frequently operated. It will work.
[0107]
A specific process will be described.
[0108]
As shown in FIG. 24, in step S220, the SCS • ECU 10 inputs the vehicle speed V, the steering angle θH, and the road friction coefficient μ. In step S222, the SCS / ECU 10 calculates the operation frequency of the SCS control. This operating frequency is the number of SCS control operations per unit time or the ratio between the SCS control operation time and the non-operation time. In step S224, the SCS / ECU 10 corrects the SCS control start threshold values β0 and ψ0 according to the operating frequency calculated in step S222 (β0 → β0 · x0, ψ0 → ψ0 · x0). That is, based on the map shown in FIG. 25, the SCS control start threshold values β0 and ψ0 are multiplied by the correction coefficient x0, and the SCS control start threshold values β0 and ψ0 are corrected so as to decrease as the SCS control operation frequency increases.
[0109]
In step S226, the SCS • ECU 10 further corrects the SCS control start threshold values β0 and ψ0 corrected in step S224 according to the vehicle speed V (β0 → β0 · x0 · x1, ψ0 → ψ0 · x0 · x1). That is, based on the map shown in FIG. 26, the SCS control start threshold values β0 and ψ0 corrected in step S224 are multiplied by the correction coefficient x1, and the SCS control start threshold values β0 and ψ0 are further reduced as the vehicle speed V increases. to correct.
[0110]
In step S228, the SCS • ECU 10 further corrects the SCS control start threshold values β0 and ψ0 corrected in step S226 according to the steering angle θH (β0 → β0 · x0 · x1 · x2, ψ0 → ψ0 · x0 · x1). X2). That is, based on the map shown in FIG. 27, the SCS control start threshold values β0 and ψ0 corrected in step S226 are multiplied by the correction coefficient x2, and the SCS control start threshold values β0 and ψ0 become smaller as the steering angle θH increases. Further corrections are made.
[0111]
In step S230, the SCS • ECU 10 further corrects the SCS control start threshold values β0 and ψ0 corrected in step S228 in accordance with the friction coefficient μ of the road surface (β0 → β0 · x0 · x1 · x2 · x3, ψ0 → ψ0 · x0 ・ x1 ・ x2 ・ x3). That is, based on the map shown in FIG. 28, the SCS control start threshold values β0 and ψ0 corrected in step S228 are multiplied by the correction coefficient x3, and the smaller the road friction coefficient μ, the smaller the SCS control start threshold values β0 and ψ0. Further correction is made as follows.
[0112]
Next, in step S232, the SCS • ECU 10 determines whether or not the target skid angle βTR or ψTR has changed to become the SCS control start threshold value β0, ψ0 or more (see steps S44 and S52 in FIG. 4). If the target skid angle βTR or ψTR has changed in step S232 (Yes in step S232), the process proceeds to step S234, and if the target skid angle βTR or ψTR has not changed in step S232 (No in step S232), step S236. Proceed to
[0113]
In step S234, the SCS • ECU 10 sets d1 as the correction coefficient x4, while in step S236, the SCS • ECU 10 sets d2 as the correction coefficient x4. However, d1> d2.
[0114]
In step S238, the SCS control start threshold values β0 and ψ0 corrected in step S230 are multiplied by a predetermined coefficient x4. When the target side slip angle βTR or ψTR changes, the SCS control is performed more than when the actual side slip angle βact or ψact changes. Correction is performed so as to suppress the decrease amount of the start threshold values β0 and ψ0.
[0115]
In the above embodiment, the SCS control start threshold values β0 and ψ0 are corrected according to the operation frequency of the SCS control and the vehicle state quantity. However, the SCS control end threshold value is corrected based on these values, and the SCS control is ended. It may be difficult.
[0116]
As described above, when the operation frequency of the SCS control is large, or by correcting the SCS control start thresholds β0 and ψ0 in the direction in which the SCS control is easily started according to other vehicle state quantities, In addition to enhancing safety, engine torque-down control, particularly in SCS control, acts as a commandment for a driver who performs dangerous driving where SCS control frequently operates.
[0117]
[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.
[0118]
In the SCS control described above, the brake control for the wheels of the TCS control is stopped during the SCS control, and only the torque down control by the engine can be executed.
[0119]
However, even if the engine output is increased by the driver's accelerator operation even during TCS control, the wheel speed difference between the braking wheel subject to SCS control and the other driving wheels becomes larger than the target value, and the vehicle Behavioral changes may not be controlled as intended.
[0120]
Therefore, in the SCS control described below, the torque down control by the TCS control is supplementarily applied to the SCS control with the wheel braking by facilitating the engine torque down control by the TCS control during the SCS control. Thus, the load on the braking device can be reduced, and the change in the vehicle speed can be controlled as intended by suppressing the change in the wheel speed generated by the driver's accelerator operation.
[0121]
A specific process will be described.
[0122]
FIG. 9 In step S250, the SCS • ECU 10 determines whether or not the SCS control is being performed. If the 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 and normal control of the TCS, that is, braking to the wheels. Control and engine torque down control are executed.
[0123]
In step S252, the SCS • ECU 10 reduces the start threshold value of TCS control (however, only engine torque down control) by 20% so that TCS control is easily started. In step S254, the SCS / ECU 10 changes the average wheel speed, which serves as a reference for TCS control, to the maximum wheel speed (select High) to make it seem that slip wheels are likely to occur, and TCS control is started. Make it easier.
[0124]
In step S256, the SCS • ECU 10 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 turned off.
[0125]
In step S258, the SCS • ECU 10 reduces the target value used for the TCS control by 10% to make it easier to start the TCS control.
[0126]
In step S260, the SCS • ECU 10 limits the upper limit of the engine output value to the output value at the start of the SCS control.
[0127]
As described above, during the SCS control, the torque reduction control of the engine by the TCS control is easily performed, so that the torque reduction control by the TCS control is additionally applied to the SCS control accompanied by wheel braking. The load can be reduced, and the change in vehicle behavior can be controlled as intended by suppressing the change in wheel speed caused by the driver's accelerator operation.
[0128]
<Description of other engine control methods during SCS control>
Next, another engine control method during SCS control will be described.
[0129]
In the SCS control described above, a change in the wheel speed is suppressed by facilitating 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. During the SCS control, the opening of the throttle valve 23 is kept constant, and the engine output is controlled to be substantially constant, so that the wheel speed change caused by the driver's accelerator operation can be suppressed.
[0130]
Note that the present invention can be applied to a modified or changed embodiment without departing from the spirit of the present invention.
[0131]
As described above, according to the present invention, The reliability of the estimated skid angle can be determined by determining whether the reliability of the reference value is high, and the reference value can be determined by changing the correction speed to bring the estimated skid angle error closer to the reference value based on the reliability of the reference value. The more reliable value of the estimated side slip angle is the value that is actually used for control.For example, even if the vehicle is turning, the more reliable value of the reference value and the estimated side slip angle is The value is actually used for control and can absorb the error accumulated in the estimated skid angle .
[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 showing an overall operation for executing posture control of the present embodiment.
FIG. 3 is a flowchart for executing the SCS calculation process of FIG. 2;
FIG. 4 is a flowchart for executing the SCS calculation process 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 the 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 correction speed changing process (1) of an error of an estimated side slip angle.
FIG. 11 is a diagram showing a map for changing a correction speed of an estimated side slip angle error;
FIG. 12 is a flowchart for executing a correction speed changing process (2) for an estimated side slip angle error;
FIG. 13 is a diagram showing a map for changing a correction speed of an estimated side slip angle error.
FIG. 14 is a flowchart for executing a process (3) for changing a correction speed of an error of an estimated side slip angle.
FIG. 15 is a diagram showing a map for changing a correction speed of an estimated side slip angle error;
FIG. 16 is a flowchart for executing a process (4) of changing a correction speed of an error of an estimated side slip angle.
FIG. 17 is a diagram showing a map for changing the correction speed of the estimated side slip angle error.
FIG. 18 is a flowchart for executing road surface inclination angle calculation processing;
FIG. 19 is a flowchart for executing control intervention suppression processing 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 an SCS control amount calculation process based on actual lateral acceleration.
FIG. 22 is a flowchart for executing SCS control intervention permission processing according to the running state of the 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 the SCS control start threshold value.
FIG. 26 is a diagram showing a map for changing the SCS control start threshold value.
FIG. 27 is a diagram showing a map for changing the SCS control start threshold.
FIG. 28 is a diagram showing a map for changing the SCS control start threshold value.
FIG. 29 is a flowchart for executing TCS control during SCS control.
[Explanation of symbols]
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 pedal pressure sensor
36 ... Pressure unit
37 ... Master cylinder
38 ... Brake pedal
40 ... TCS off switch

Claims (5)

An apparatus for controlling the attitude of the vehicle so that the estimated side slip angle converges to the target side slip angle when the deviation between the target side slip angle calculated based on the vehicle state quantity and the estimated side slip angle exceeds a predetermined control start threshold. There,
Vehicle speed detecting means for detecting the vehicle speed of the vehicle;
Rudder angle detection means for detecting the steering angle of the vehicle;
Yaw rate detection means for detecting the yaw rate generated in the vehicle;
Lateral acceleration detection means for detecting lateral acceleration generated in the vehicle;
Estimated side slip angle calculating means for calculating the estimated side slip angle by integrating the vehicle side slip speed calculated based on the vehicle speed, steering rudder angle, yaw rate, and lateral acceleration detected by each means;
Error correcting means for correcting an error caused by integration of the estimated side slip angle by bringing the estimated side slip angle close to a target value;
Threshold correction means for correcting so that the control start threshold decreases as the vehicle speed increases,
The target value is a reference value calculated based on a vehicle speed, a yaw rate, a lateral acceleration, a skid speed, and a change rate of the yaw rate, and the error correction unit is configured to make the estimated skid angle close to the reference value. the correction speed to the reference value, the reference value, and changes based on the reliability that varies with changes in the cornering power of the front wheel cornering power or the rear wheels, if the reliability of the reference value is low the An attitude control apparatus for a vehicle, characterized in that the correction speed is changed so as to decrease slowly, and when the reliability of the reference value is high, the correction speed is changed so as to increase so as to increase . Cornering power of the cornering power or the rear wheel of the front wheel is changed by the friction coefficient of the road surface, the reliability of the reference value is determined based on the friction coefficient of the road surface, when the friction coefficient of the road surface is low the reference It is determined that the reliability of the value is low, and the correction speed is changed in a decreasing direction. When the friction coefficient of the road surface is high, it is determined that the reliability of the reference value is high and the correction speed increases. attitude control device for a vehicle according to claim 1, wherein the be subject to change direction. The cornering power of the front wheels or the cornering power of the rear wheels varies depending on whether or not the road surface during vehicle travel is a bad road, and the reliability of the reference value is determined based on whether or not the road surface is a bad road. When the vehicle is traveling on a rough road , the reliability of the reference value is determined to be low, and the correction speed is changed in a decreasing direction. When the vehicle is not traveling on a rough road, the reliability of the reference value is determined to be high. It has been, attitude control device for a vehicle according to claim 1, wherein the be subject to change a direction in which the correction speed is increased. The cornering power of the front wheels or the cornering power of the rear wheels varies depending on whether or not the vehicle is traveling straight ahead, and the reliability of the reference value is based on whether or not the vehicle is traveling straight ahead. If the vehicle is not traveling straight ahead, it is determined that the reliability of the reference value is low, the correction speed is changed in a decreasing direction, and if the vehicle is traveling straight ahead, the reliability of the reference value is determined. The vehicle attitude control device according to claim 1 , wherein the vehicle attitude control device is determined to have high performance and is changed in a direction in which the correction speed increases. The front wheel cornering power or the rear wheel cornering power varies depending on the vehicle speed, and the reliability of the reference value is determined based on the vehicle speed. When the vehicle speed is low, the reliability of the reference value is low. When the vehicle speed is high, the reference value is determined to be highly reliable, and the correction speed is changed to increase. The vehicle attitude control device according to claim 1 .

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