JP2000219146A - Vehicle travel control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve riding comfort of a vehicle by effectively restraining rolling of a vehicle body without applying uncomfortable feeling to an occupant of the vehicle. SOLUTION: In this control device, the estimated roll angle ϕe of a vehicle body is calculated (S20), the detected roll angle ϕ of the vehicle body is calculated (S30), the judgment whether excessive large rolling is generated or not on the vehicle body is performed (S40), the roll angle Δϕ of the vehicle body generated caused by disturbance is calculated (S60) when excessive large rolling is not generated on the vehicle body, a roll index value RVd of the vehicle body generated caused by disturbance is calculated (S70), the correction steering angle θfa of front wheels and correction steering angle θra of rear wheels are calculated (S80) on the basis of the roll index value RVd of the vehicle body, and a correction steering device 24 and an actuator device 26 are controlled on the basis of the correction steering angles θfa and θra. Therefore, the left and right front wheels are corrected and steered in the rolling direction of the vehicle body, and the right and left rear wheels are corrected and steered (S110) in the opposite direction to the front wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control device for a vehicle, and more particularly, to a travel control device capable of effectively suppressing a roll of a vehicle body.

[0002]

2. Description of the Related Art As one of traveling control devices for vehicles such as automobiles, a roll prediction sensor for predicting the roll of a vehicle body and detecting the roll of the vehicle body are disclosed in, for example, JP-A-63-116918. It has means for calculating the vehicle condition based on the signal from the roll detection sensor and displaying the vehicle condition as a result of the calculation, and means for decelerating the vehicle before the vehicle condition reaches the roll limit. A traveling control device configured to perform the operation is conventionally known.

According to such a travel control device, for example, when the vehicle makes a sharp turn at a relatively high vehicle speed, an excessively high centrifugal force acts on the vehicle, so that the roll of the vehicle body becomes excessive. In such a situation, the vehicle is decelerated before reaching the roll limit, thereby reducing the centrifugal force acting on the vehicle. Can be reliably prevented from becoming excessive.

[0004]

However, in the conventional traveling control device described in the above-mentioned publication, when the roll of the vehicle body increases, the vehicle speed is suddenly reduced by suddenly decelerating the vehicle. Although the occurrence of an excessive roll can be prevented, there is a problem that the occupant of the vehicle, particularly the driver, feels strange.

In the above-mentioned conventional traveling control device, when the roll of the vehicle body is caused by disturbance such as unevenness on the traveling road surface, the traveling of the vehicle body is generally slight because the degree of the roll of the vehicle body is slight. Since the control device does not operate, and even if the vehicle is decelerated by activating the cruise control device, the roll of the vehicle body cannot be prevented, the roll of the vehicle body in such a situation is effectively suppressed to prevent the vehicle from rolling. There is a problem that ride comfort cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in a conventional travel control device configured to automatically decelerate the vehicle when the roll of the vehicle body becomes excessive. The main problem is that when a roll of the car body occurs, the centrifugal force acts on the car body in the roll restraining direction without decelerating the car, so that the car body roll can be effectively applied without giving the occupants of the car a sense of discomfort. And to improve the riding comfort of the vehicle.

[0007]

According to the present invention, the above-mentioned main object is achieved by the construction according to claim 1, that is, means for obtaining a roll index value indicating the degree of roll of the vehicle body, And a corrective steering means for performing a corrective steering in a direction in which the centrifugal force in the roll reduction direction is applied to the vehicle body.

According to the first aspect of the present invention, the steering is corrected in the direction in which the centrifugal force in the roll reduction direction is applied to the vehicle body in accordance with the roll index value indicating the degree of roll of the vehicle body. Is reduced by the centrifugal force in the roll reduction direction due to the correction steering, whereby the roll of the vehicle body is reliably reduced and suppressed without decelerating the vehicle.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned structure, the correction steering means may be arranged so that when the roll index value is equal to or more than a reference value. It is configured to perform the correction steering (the configuration of claim 2).

According to the second aspect of the present invention, the correction steering is performed when the roll index value is equal to or larger than the reference value. Therefore, unnecessary correction steering is reliably prevented and reduced. Rolls of the vehicle body that need to be suppressed are reliably reduced and suppressed.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned structure of the first or second aspect, the roll index value determines the degree of roll of the vehicle body caused by disturbance. (The configuration of claim 3).

According to the third aspect of the present invention, since the roll index value indicates the degree of the roll of the vehicle body caused by the disturbance, the roll of the vehicle body caused by the disturbance such as unevenness on the traveling road surface is reliably reduced and suppressed. Is done.

[0013]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the correction steering means is configured to correct the front wheels in the same direction as the roll direction of the vehicle body. (Preferred embodiment 1).

According to another preferred aspect of the present invention, in the configuration of the first aspect, the correction steering means is configured to correct and steer the rear wheel in a direction opposite to the roll direction of the vehicle body. (Preferred embodiment 2).

According to another preferred embodiment of the present invention, in the configuration of the first aspect, the correction steering means corrects the front wheels in the same direction as the roll direction of the vehicle body and corrects the rear wheels by the vehicle body. (Preferred mode 3).

According to another preferred aspect of the present invention, in the configuration according to the second aspect, the roll index value is an index value for determining an excessive roll of the vehicle body, and the correction steering means includes a roll index value. When the value is equal to or larger than the reference value, the correction steering is performed at the correction steering angle corresponding to the actual roll angle of the vehicle body and the rate of change thereof (preferred mode 4).

According to another preferred aspect of the present invention, in the configuration of the third aspect, the means for obtaining the roll index value excludes the influence of disturbance due to the means for obtaining the actual roll angle of the vehicle body. It is configured to include means for estimating the roll angle of the vehicle body and means for calculating a roll index value based on a deviation between the actual roll angle and the estimated roll angle and a rate of change of the deviation (preferred mode 5).

According to another preferred embodiment of the present invention, in the configuration of the above-described preferred embodiment 5, the roll index value is a difference between an actual roll angle and an estimated roll angle and a rate of change of the difference. It is configured to be a linear sum (preferred embodiment 6).

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 6, when the roll index value is equal to or larger than the reference value, the correction steering means adjusts the corrected steering angle according to the roll index value. To perform the correction steering (preferred mode 7).

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the accompanying drawings, in which several preferred embodiments are shown.

FIG. 1 is a schematic configuration diagram showing a first preferred embodiment of a vehicle traveling control device according to the present invention applied to a vehicle provided with a four-wheel steering device.

In FIG. 1, 10FL and 10FR denote left and right front wheels of the vehicle 12, respectively, and 10RL and 10RR denote left and right rear wheels which are driving wheels of the vehicle, respectively. The left and right front wheels 10FL and 10FR, which are both driven wheels and steering wheels, are tie rods 18L and 1FR by a rack-and-pinion type electric power steering device 16 driven in response to the driver turning the steering wheel 14.
Steered via 8R.

In the illustrated embodiment, a correction steering device 24 is interposed between the upper shaft 20 and the lower shaft 22 that connect the steering wheel 14 and the gear box of the power steering device 16. ,
The correction steering device 24 includes, for example, a motor and a gear mechanism,
Correction steering is performed by rotating the lower shaft 22 relatively to the upper shaft 20.

The left and right rear wheels 10RL and 10RR are steered by an actuator device 26 via tie rods 28L and 28R. The correction steering device 24 and the actuator device 26 are controlled by the electric control device 30 so as to suppress the roll of the vehicle body due to disturbance, as described in detail later. The actuator device 26 is controlled by the electric control device 30 in response to the turning of the steering wheel 14 in the four-wheel steering mode.

As shown in the figure, a signal indicating the steering angle θ detected by the steering angle sensor 32 provided on the upper shaft 20 and a signal indicating the yaw rate γ of the vehicle detected by the yaw rate sensor 34 are provided to the electric control device 30. A signal indicating the vehicle speed V detected by the vehicle speed sensor 36, and the roll rate φ of the vehicle body detected by the roll rate sensor 38.
A signal indicating r and a signal indicating the lateral acceleration Gy of the vehicle detected by the lateral acceleration sensor 40 are input.

The steering angle sensor 32 and the like detect the steering angle θ and the like with the value in the case of the vehicle turning left as positive. Although not shown in detail in FIG. 1, the electric control device 30 includes, for example, a CPU, a ROM, a RAM, and an input / output port device.
These may include a microcomputer having a general configuration and a drive circuit connected to each other by a bidirectional common bus.

The electric control device 30 calculates the estimated roll angle φe of the vehicle body based on the lateral acceleration Gy of the vehicle and calculates the estimated roll angle φe of the vehicle body based on the roll rate φr of the vehicle body in accordance with the flowcharts shown in FIGS. The roll angle Δφ of the vehicle body caused by disturbance is calculated as a deviation between the estimated roll angle φe and the detected roll angle φ, and the linear roll of the roll angle Δφ and its differential value is calculated by the disturbance. And the corrected steering angles θfa and θra of the front and rear wheels are calculated based on the roll index value RVd, and based on these, the corrected steering device 24 and the actuator device 26 are calculated.
, Thereby assisting the steering in the direction in which the centrifugal force in the roll reduction direction is applied to the vehicle body, thereby suppressing the roll of the vehicle body due to disturbance.

The electric control device 30 calculates a roll index value RVr and the like for determining an excessive roll of the vehicle body based on the steering angle θ and the lateral acceleration Gy of the vehicle according to a routine shown in FIG. Then, it is determined whether an excessive roll of the vehicle body is generated based on the roll index value RVr or the like. When an excessive roll of the vehicle body is generated, a linear relationship between the roll angle φ of the vehicle body and its differential value φd is determined. The correction steering device 24 and the actuator device 26 are controlled in accordance with the sum, whereby the excessive steering of the vehicle body is suppressed by reducing the centrifugal force acting on the vehicle body by performing auxiliary steering in the direction of reducing the steering angle.

Next, the traveling control of the vehicle in the first embodiment will be described with reference to the flowcharts shown in FIGS. The control according to the general flowcharts shown in FIGS. 2 and 3 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, in step 10, a signal indicating the steering angle θ detected by the steering angle sensor 32 is read, and in step 20, the second-order differential value of the estimated roll angle φe of the vehicle body is set to φetd. By solving the following differential equation (1) with the difference between the roll inertia moment of the vehicle as Ix, the roll rigidity of the vehicle as Kr, and the distance between the roll axis of the vehicle and the center of gravity of the vehicle as L, Is calculated. Ixφetd = −Krφe + LGy (1)

In step 30, the detected roll angle φ of the vehicle body is calculated by solving the following differential equation (2) as a difference by setting the differential value of the roll angle as φd and T as an attenuation time constant. φd = −φ / T + φr (2)

In step 40, it is determined according to the excessive roll determination routine shown in FIG. 3 whether or not the roll of the vehicle body is excessive. If an affirmative determination is made, the process proceeds to step 90, and a negative determination is made. Is performed, the routine proceeds to step 60.

In step 60, the roll angle Δφ of the vehicle body caused by the disturbance is calculated according to the following equation (3).
In step 70, the differential value Δφd of the roll angle Δφ of the vehicle body caused by the disturbance is calculated, and the roll index value RVd of the vehicle body caused by the disturbance is calculated according to the following equation (4), using K1 as a positive constant coefficient. Is calculated. Δφ = φ−φe (3) RVd = Δφ + K1Δφ (4)

In step 80, based on the roll index value RVd of the vehicle body, the corrected steering angle θfa of the front wheels and the corrected steering angle θra of the rear wheels are obtained from a map corresponding to the graph shown in FIG.
Is calculated.

In step 90, a linear sum φt of the roll angle of the vehicle body and its differential value is calculated according to the following equation (5) using K2 as a positive constant coefficient. In step 100, the linear sum φt is calculated. The corrected steering angle θfa of the front wheels and the corrected steering angle θra of the rear wheels are calculated based on the map corresponding to the graph shown in FIG. φt = φ + K2φd (5)

In step 110, the corrective steering device 24 and the actuator device 26 are controlled based on the corrective steering angle θfa of the front wheel and the corrective steering angle θra of the rear wheel calculated in step 80 or 100. The front wheels 10FL and 10FR and the left and right rear wheels 10RL and 10RR are corrected and steered at the corrected steering angles θfa and θra, respectively.

In step 41 of the excessive roll determination routine shown in FIG. 3, Kh is used as a stability factor, Rg is used as a steering gear ratio, and H is used as a wheel base, and the steering angle θ is calculated according to the following equation (6). The lateral acceleration Gys of the vehicle is calculated based on the following equation. Gys = V ² θ / [(1 + KhV ² ) RgH] (6)

In step 42, Rrf is the previous value of the estimated roll rate Rr, ωo is the natural frequency of the vehicle body,
An estimated roll rate Rr is calculated according to the following equation (7), where φo is a steady roll angle per unit of gravitational acceleration, ξ is a roll damping coefficient, and ΔT is a cycle time of the flowchart shown in FIG. Rr = Rrf + ｛(ωo ² (Gyφo-R) −2ωoξRrf｝ ΔT (7)

In step 43, the estimated roll angle R is calculated according to the following equation (8), using Rf as the previous value of the estimated roll angle R. R = Rf + RrΔT (8)

In step 44, the roll index value RVr is calculated based on the lateral acceleration Gy of the vehicle in accordance with the following equation (9), using Gylim as the allowable limit value of the lateral acceleration and Rrlim as the allowable limit value of the roll angular velocity. . Note that the allowable limit value Gy
lim and Rrlim may be positive constants, but may be variably set based on, for example, the vehicle speed V or the like. RVr = Gy / Gylim + Rr / Rrlim (9)

In step 45, the absolute value of the lateral acceleration Gys of the vehicle body based on the steering angle is set to a reference value Gyso (positive constant).
Is determined, and if a negative determination is made, it is determined in step 46 whether the absolute value of the lateral acceleration Gy of the vehicle body exceeds a reference value Gyo (a positive constant). Step 4 is performed when a negative determination is made
At 7, it is determined whether or not the absolute value of the product of the yaw rate γ and the vehicle speed V exceeds a reference value Gvo (positive constant). If a negative determination is made, the process proceeds to step 48;
When an affirmative determination is made in any of steps 45 to 47, the process proceeds to step 50.

In step 48, the roll index value RV
It is determined whether or not the absolute value of r exceeds a reference value RVro (positive constant). If a negative determination is made, in step 49, .DELTA.CP is set to a relatively small positive constant to count the value of the counter. When Cp is decremented by ΔCp and an affirmative determination is made, in step 50, the count value Cp is set to an initial value Cpo (a positive constant) of the control.

In step 51, it is determined whether or not the count value Cp exceeds a reference value Cpe (a positive constant smaller than Cpo). If a negative determination is made, the process proceeds to step 60, and an affirmation is made. When the determination is made, the routine proceeds to 90.

Thus, according to the illustrated embodiment, the estimated roll angle φe of the vehicle body is calculated in step 20, the detected roll angle φ of the vehicle body is calculated in step 30,
At step 40, it is determined whether or not an excessive roll has occurred on the vehicle body. When an excessive roll has not occurred on the vehicle body, at step 60, the roll angle Δφ of the vehicle body caused by disturbance is calculated. Then, in step 70, the roll index value RVd of the vehicle body caused by the disturbance is calculated,
In step 80, the corrected steering angle θfa of the front wheels and the corrected steering angle θra of the rear wheels are calculated based on the roll index value RVd of the vehicle body. In step 110, the corrected steering angles θfa and θra are calculated.
Correction steering device 24 and actuator device 2 based on ra
6, the left and right front wheels 10FL and 10FR are corrected and steered in the roll direction of the vehicle body, and the left and right rear wheels 10RL and 10RR are corrected and steered in the opposite phase to the front wheels.

Therefore, as shown in FIG. 6, for example, when the left front wheel 10FL rides over the projection 44 of the road surface 42 and the left front wheel 10FL receives the pushing force Fr from the projection 44, the vehicle body 46 moves in the traveling direction. On the other hand, when the wheel is rolled rightward, the wheel is corrected and steered in the right turning direction as indicated by the arrow 48, so that a centrifugal force Fc of a magnitude corresponding to the roll index value RVd is applied to the center of gravity 50 of the vehicle body 46. On the other hand, since it acts in the roll reduction direction, that is, the direction in which the pushing-up force Fr is canceled, the roll of the vehicle body can be effectively reduced, thereby improving the riding comfort of the vehicle.

When the roll of the vehicle body is excessive, an affirmative determination is made in step 40, and in step 90, a linear sum φt of the roll angle φ of the vehicle body and its differential value φd
The corrected steering angle θfa of the front wheels and the corrected steering angle θra of the rear wheels are calculated based on the linear sum φt in step 100, and the corrected steering angles θfa and θra in step 110.
Correction steering device 24 and actuator device 2 based on ra
6, the left and right front wheels 10FL and 10FR are corrected and steered in the roll direction of the vehicle body, and the left and right rear wheels 10RL and 10RR are corrected and steered in the opposite phase to the front wheels.

Therefore, when an excessive roll is generated on the vehicle body due to a strong centrifugal force acting on the vehicle body, for example, when a sharp turn is performed at a high vehicle speed,
Since the centrifugal force acting on the vehicle body is reduced by an amount corresponding to the linear sum φt, the roll of the vehicle body can be reliably reduced.

FIG. 7 is a flowchart showing a traveling control routine in a second embodiment of the traveling control device for a vehicle according to the present invention applied to a vehicle provided with a four-wheel steering device. In FIG. 7, the same steps as those shown in FIG. 2 are assigned the same step numbers as those given in FIG. In this embodiment, strokes Sl and Sr of the left and right front wheels are detected by stroke sensors instead of the roll rate sensor 38 in the first embodiment, though not shown in the drawing.

In this embodiment, in step 35 executed after step 30, the roll angle φi of the vehicle body caused by disturbance is calculated in accordance with the following equation (10) using Tr as the tread of the vehicle. . φi = (Sl−Sr) / Tr−φe (10)

If a negative determination is made in step 40, the differential value φid of the roll angle φi of the vehicle body caused by the disturbance is calculated in step 75, and K3 is defined as a positive constant coefficient as follows: The roll index value RVi of the vehicle body caused by the disturbance is calculated according to equation (11). RVi = φi + K3φid (11)

Further, in step 85 executed after step 75, the correction steering angle θfa for the front wheels and the correction for the rear wheels based on the map corresponding to the graph shown in FIG. The steering angle θra is calculated.

Thus, according to the illustrated second embodiment,
In step 30, the detected roll angle φ of the vehicle body is calculated, and in step 35, the roll angle φi of the vehicle body caused by disturbance is calculated. In step 40, it is determined whether an excessive roll has occurred on the vehicle body. When no excessive roll has occurred on the vehicle body, a roll index value RVi of the vehicle body caused by disturbance is calculated in step 75, and in step 85, the front wheel is calculated based on the roll index value RVi of the vehicle body. Corrected steering angle θfa and rear wheel corrected steering angle θra
Is calculated, and in step 110, the correction steering device 24 and the actuator device 26 are controlled based on the correction steering angles θfa and θra, whereby the left and right front wheels 10FL and 10FL are controlled.
The FR is steered in the roll direction of the vehicle, and the left and right rear wheels 10RL
And 10RR are corrected and steered in the opposite phase to the front wheels.

Therefore, as in the case of the first embodiment, the roll of the vehicle body caused by the unevenness of the traveling road surface is effectively reduced,
This makes it possible to improve the riding comfort of the vehicle and to suppress an excessive roll of the vehicle body when, for example, the vehicle turns sharply at a high vehicle speed.

In particular, according to this embodiment, the roll angle φi of the vehicle body caused by the disturbance is calculated according to the above equation (10). Therefore, when the disturbance is a crosswind and the roll of the body is generated by the crosswind, Also, it is possible to effectively reduce the roll of the vehicle body and improve the riding comfort and the steering stability of the vehicle.

In the first embodiment, the roll index value RVd of the vehicle body caused by the disturbance is calculated as a linear sum of the roll angle Δφ of the vehicle body caused by the disturbance and its differential value Δφd. In the second embodiment described above,
Since the roll index value RVi of the vehicle body caused by the disturbance is calculated as a linear sum of the roll angle φi of the vehicle body caused by the disturbance and its differential value φid, the roll index value RVi is compared with a case where the differential value is not considered. The roll of the vehicle body caused by disturbance can be effectively reduced.

Similarly, in each of the first and second embodiments, the corrected steering angles θfa and θra are calculated based on the linear sum of the roll angle φ of the vehicle body and its differential value φd. Therefore, it is possible to effectively reduce the roll of the vehicle body caused by a sharp turn as compared with a case where the differential value is not considered.

Further, in any of the first and second embodiments, the correction steering is performed only when the magnitude of the roll index value RVd or the like of the vehicle body caused by the disturbance is equal to or larger than the corresponding reference value. As a result, unnecessary correction steering can be reliably prevented from being performed, and thereby unnecessary correction steering may hinder the stability of the vehicle or the occupant of the vehicle may feel uncomfortable. Can be reliably prevented.

In the above, the present invention has been described in detail with respect to a specific embodiment. However, the present invention is not limited to the above embodiment, and various other embodiments are included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the first embodiment described above,
The estimated roll angle φe of the vehicle body is calculated according to the above equation (1), the detected roll angle φ of the vehicle body is calculated according to the above equation (2), and the roll index value RVd of the vehicle body due to disturbance is calculated according to the above equation (3). In the above-described second embodiment, the roll angle φi of the vehicle body caused by the disturbance is calculated according to the above equation (10), and the roll angle φi caused by the disturbance is calculated according to the above equation (11). The roll index value RVi of the vehicle body is calculated, but the roll index value of the vehicle body may be calculated in any manner as long as it is a value indicating the degree of roll of the vehicle body.

In both the first and second embodiments described above, it is determined in step 40 whether an excessive roll of the vehicle body has occurred. When it occurs, the excessive roll of the vehicle body is suppressed by performing the correction steering in steps 90 to 110, but step 40 and steps 90 to 110 may be omitted. If it is determined in step 40 that an excessive roll of the vehicle body is occurring, corrective steering is performed in step 110, and braking force is preferably applied to the turning outer wheel, particularly the turning outer front wheel. As a result, the vehicle is given a yaw moment in the direction of reducing the deceleration and the degree of turning, whereby the corrected steering angle is reduced and the occupant feels during the deceleration. Sum feeling may be reduced.

In each of the above embodiments, the vehicle is provided with a four-wheel steering device, and the corrective steering is performed for both the front wheels and the rear wheels. However, the corrective steering is performed for the front wheels or the rear wheels. May be modified so as to be performed only for one of them.

Further, in each of the above embodiments, the front wheel steering device is a rack-and-pinion type electric power steering device 16 and the correction steering device 24.
Is a lower shaft 22 relative to the upper shaft 20
The steering is performed by rotating the steering wheel. However, the front wheel steering device and the correction steering device may have any structure known in the art.

[0063]

As is apparent from the above description, according to the construction of the first aspect, the steering is corrected in a direction in which the centrifugal force in the roll reduction direction is applied to the vehicle body in accordance with the roll index value indicating the degree of roll of the vehicle body. Therefore, the force acting on the vehicle body and causing the roll is reduced by the centrifugal force in the roll reduction direction by the correction steering, and therefore, the roll of the vehicle body can be surely reduced and suppressed without decelerating the vehicle. Ride comfort and steering stability of the vehicle can be improved.

According to the second aspect of the present invention, the correction steering is performed when the roll index value is equal to or larger than the reference value.
Unnecessarily performing the corrective steering can be reliably prevented, and the rolls of the vehicle body, which need to be reduced and suppressed, can be reliably reduced and suppressed.

According to the third aspect of the present invention, the roll index value indicates the degree of the roll of the vehicle body caused by the disturbance, so that the roll of the vehicle body caused by the disturbance such as unevenness on the traveling road surface can be reliably reduced. Therefore, the ride comfort of the vehicle can be reliably improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first preferred embodiment of a vehicle traveling control device according to the present invention applied to a vehicle provided with a four-wheel steering device.

FIG. 2 is a flowchart illustrating a traveling control routine according to the first embodiment.

FIG. 3 is a flowchart showing an excessive roll determination routine in step 40 shown in FIG. 2;

FIG. 4 is a graph showing a relationship between a roll index value RVd of a vehicle body, a corrected steering angle θfa of a front wheel, and a corrected steering angle θra of a rear wheel.

FIG. 5 is a graph showing a relationship between a linear sum φt, a corrected steering angle θfa of a front wheel, and a corrected steering angle θra of a rear wheel.

FIG. 6 is a front view of the vehicle showing the operation of the first embodiment when the left front wheel gets over a projection on the road surface.

FIG. 7 is a flowchart illustrating a travel control routine in a second embodiment of the vehicle travel control device according to the present invention applied to a vehicle including a four-wheel steering device.

FIG. 8 is a graph showing the relationship between the roll index value RVi of the vehicle body, the corrected steering angle θfa of the front wheels, and the corrected steering angle θra of the rear wheels.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 16 ... Electric power steering device 24 ... Correction steering device 26 ... Actuator device 30 ... Electric control device 32 ... Steering angle sensor 34 ... Yaw rate sensor 36 ... Vehicle speed sensor 38 ... Roll rate sensor 40 ... Lateral acceleration sensor

Claims (3)

[Claims] 1. A vehicle comprising: means for obtaining a roll index value indicating a degree of roll of a vehicle body; and correction steering means for performing correction steering in a direction of applying a centrifugal force in a roll reduction direction to the vehicle body in accordance with the roll index value. Characteristic vehicle travel control device. 2. The vehicle travel control device according to claim 1, wherein said correction steering means performs correction steering when said roll index value is equal to or greater than a reference value. 3. The vehicle travel control device according to claim 1, wherein the roll index value indicates a degree of roll of the vehicle body caused by a disturbance.