JP3087438B2 - Vehicle turning state estimation device and vehicle motion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating a turning state of a vehicle, and more particularly to a technique for making the estimation inexpensive.

[0002]

2. Description of the Related Art Hitherto, there has been a strong demand for accurately grasping the turning state of a vehicle, and the following devices have already been proposed to satisfy this demand. This is a vehicle motion state detection device described in Japanese Patent Application Laid-Open No. 61-244669, in which a lateral acceleration sensor is provided at each of a position of a vehicle deviating forward and a position deviating rearward from a center of gravity, It is to detect whether the vehicle is in a steady turning motion state based on the detection results of these two lateral acceleration sensors.

[0003]

However, when implementing this conventional apparatus, there is a problem that an increase in apparatus cost cannot be avoided because two lateral acceleration sensors are indispensable. In addition, there has been a demand for a technique for controlling the motion state of a vehicle, in which it is desired to always maintain good operability of the vehicle during turning of the vehicle.

It is an object of the present invention to provide a single lateral acceleration sensor capable of estimating whether or not a turning state of a vehicle is in an understeer state. . It is an object of the present invention to provide a lateral acceleration sensor capable of estimating whether or not a turning state of a vehicle is in an oversteer state . The invention of claim 3 and 4 has been made as object to provide a vehicle motion control apparatus capable of constantly maintaining good steering ease of vehicle during turning of the vehicle. A fifth aspect of the present invention has been made to provide an application of the fourth aspect of the present invention.

[0005]

The gist of the present invention is as follows. As shown in FIG. 1, (a) lateral acceleration at the center of gravity of a vehicle based on vehicle motion state quantities such as vehicle speed, steering angle, and yaw rate. Lateral acceleration estimating means 1 for estimating the lateral acceleration, (b) a lateral acceleration sensor 2 provided at a position deviated forward from the center of gravity of the vehicle to detect lateral acceleration, and (c) a lateral acceleration sensor 2 Actual lateral acceleration is estimated by lateral acceleration estimating means 1.
When the estimated lateral acceleration is smaller than
Turning state estimating means 3 for estimating the understeer state
And a vehicle turning state estimating device including the following.

The turning state estimating means 3 is, for example, in a form for estimating whether or not the vehicle is in an understeer state, in a form for estimating whether or not the vehicle is in an oversteer state, or in a state of steady turning motion. It can be in the form of estimating whether or not.

[0007] SUMMARY OF THE INVENTION claim 2, (a) based on the vehicle motion state quantity, and the lateral acceleration estimation means for estimating the lateral acceleration at the center of gravity point of the vehicle, (b), the vehicle, behind the center of gravity < a lateral acceleration sensor provided at a deviated position to detect lateral acceleration, and (c) an actual lateral acceleration detected by the lateral acceleration sensor
The degree is based on the estimated lateral acceleration estimated by the lateral acceleration estimation means .
The vehicle turns oversteer when
It is an object of the present invention to provide a vehicle turning state estimating device including turning state estimating means for estimating that there is a turning state.

Further, the gist of the invention of claim 3, or fell a vehicle motion control device for controlling a motion state of the vehicle, in (a) based on the motion state quantity of the vehicle, understeering condition that the vehicle is at its acceleration Determining means for determining whether or not the vehicle has fallen into an understeer state at the time of acceleration of the vehicle, and And control means for controlling the state.
The gist of the invention according to claim 4 is that the vehicle motion control device for controlling the motion state of the vehicle includes: (a) a first position separated from each other in the front-rear direction of the vehicle and a second position behind the first position. Acquiring means for acquiring the first lateral acceleration and the second lateral acceleration, respectively; (b) when the acquired first lateral acceleration is smaller than the acquired second lateral acceleration, Control means for controlling the exercise state so as to increase the turning ability. According to a fifth aspect of the present invention, in the vehicle motion control device according to the fourth aspect of the present invention, when the acquired first lateral acceleration is smaller than the acquired second lateral acceleration,
If it is determined that the vehicle has entered an understeer state during its acceleration, and if the vehicle has determined that it has entered an understeer state during its acceleration,
The motion state is controlled so that the turning performance of the vehicle is increased.

[0009]

When the vehicle is in a steady turning motion state, that is, when the vehicle is not in the understeer state or the oversteer state, the actual lateral acceleration of the vehicle at a position in front of or behind the center of gravity is the center of gravity of the vehicle. However, when the vehicle enters the understeer state or the oversteer state, the actual lateral acceleration does not match the estimated acceleration. At this time, the type of the turning state of the vehicle and the magnitude of the actual lateral acceleration and the estimated acceleration are different. A certain relationship is established with the relationship.

[0010] Based on such a fact, in the vehicle turning state estimating apparatus according to the first and second aspects of the present invention,
Lateral acceleration estimating means estimates lateral acceleration at the center of gravity of the vehicle based on the vehicle motion state quantity, and lateral acceleration sensors detects lateral acceleration of the vehicle at a position deviated from the center of gravity of the vehicle in the longitudinal direction of the vehicle. The state estimating means estimates a turning state of the vehicle based on the estimated lateral acceleration estimated by the lateral acceleration estimating means and the actual lateral acceleration detected by the lateral acceleration sensor.

Specifically, in the vehicle turning state estimating apparatus according to the first aspect of the present invention, the lateral acceleration sensor 2
The actual lateral acceleration at a position deviating forward from the center of gravity is detected, and the turning state estimating means 3 estimates that the vehicle is in an understeer state when the actual lateral acceleration is smaller than the lateral acceleration estimated by the lateral acceleration estimating means 1. You.

Further, in the vehicle turning state estimating apparatus according to the second aspect of the present invention, the lateral acceleration sensor detects an actual lateral acceleration at a position deviating rearward from the center of gravity, and the turning state estimating means detects the actual lateral acceleration. Is smaller than the lateral acceleration estimated by the lateral acceleration estimating means, it is estimated that the vehicle is in the oversteer state.

The results of estimation by the vehicle turning state estimating apparatus according to the present invention can be used in various applications. For example, it can be used in a vehicle movement control apparatus that controls the state of movement of a vehicle based on the estimation results. Conceivable. Such a vehicle motion control device includes, for example, a rear wheel steering angle control device that appropriately controls a rear wheel steering angle of a vehicle in relation to a front wheel steering angle, a yaw rate, and the like, and a front / rear steering angle control device that controls an engine driving torque.
A drive torque distribution control device that controls the ratio of distribution to the rear wheels, a suspension control device that keeps the vehicle body horizontal regardless of the inclination of the road surface, acceleration / deceleration / turning of the vehicle, and steering of the vehicle by the driver The amount by which the steering torque applied to the wheel is assisted is determined by the vehicle speed,
There is a steering torque assist amount control device for appropriately controlling the relationship with the engine speed and the like. In the vehicle motion control device according to the third aspect of the present invention,
Based on the motion state amount of the vehicle, it is determined whether or not the vehicle has entered an understeer state during its acceleration, and if the control means determines that the vehicle has entered the understeer state during its acceleration, The motion state of the vehicle is controlled such that the turning performance of the vehicle is increased as compared with the case where it is not the case. In the vehicle motion control device according to the fourth aspect of the present invention, the first lateral acceleration and the first lateral acceleration of the first position separated from each other in the front-rear direction of the vehicle and the second position behind the first position are obtained by the acquisition unit. 2 is acquired by the control means, and the control means controls the vehicle so that the turning property of the vehicle is increased when the acquired first lateral acceleration is smaller than the acquired second lateral acceleration, as compared with the case where the acquired first lateral acceleration is not smaller than the acquired second lateral acceleration. Is controlled. In particular, in the vehicle motion control device according to the fifth aspect of the present invention, when the acquired first lateral acceleration is smaller than the acquired second lateral acceleration, the vehicle enters the understeer state when the vehicle accelerates. When it is determined that the vehicle has fallen, and when it is determined that the vehicle has entered the understeer state when the vehicle accelerates, the motion state of the vehicle is controlled so that the turning performance of the vehicle is increased as compared with the case where it is not.

[0014]

As is apparent from the above description, according to the first and second aspects of the present invention, only one lateral acceleration sensor is required to estimate the turning state of the vehicle. The effect that the cost of the state estimation device can be easily reduced can be obtained.

Specifically, according to the first aspect of the present invention, there is also obtained an effect that it is possible to estimate whether or not the vehicle is in the understeer state.

Further, according to the second aspect of the present invention, it is possible to estimate whether or not the vehicle is in an oversteer state. According to claims 3 to 5 ,
Even if the vehicle is accelerated during the turning of the vehicle, the vehicle is prevented from exhibiting a strong understeer tendency, and as a result, the effect that the operability of the vehicle is always maintained satisfactorily is obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below in detail with reference to the drawings.

First, a description will be given of a rear wheel steering angle control apparatus according to an embodiment common to the first , third, and fifth aspects of the present invention. This rear-wheel steering angle control device, the four-wheel motor vehicle front wheel drive (FF) type, and controls the steering angle [delta] _R of the left and right rear wheels it steering angle proportional and yaw rate feedback type. This rear wheel steering angle control device includes a rear wheel steering angle control computer 10 as shown in FIG. The rear wheel steering angle control computer 10 includes, at its input part, a front wheel steering angle sensor 14 for detecting the steering angles δ _F of the left and right front wheels of the vehicle, a yaw rate sensor 16 for detecting the yaw rate γ of the vehicle body, and a running speed of the vehicle body. a vehicle speed sensor 18 for detecting a vehicle speed V is connected to a lateral acceleration sensor 20 to be described later, whereas, at the output, is connected to the wheel steering angle actuator 24 after changing the rear wheel steering angle [delta] _R.

As shown in FIG. 3, the lateral acceleration sensor 20
Provided at the front end of the vehicle and the actual lateral acceleration G _F there
Is to be detected. That is, the lateral acceleration sensor 20 is an aspect of the "lateral acceleration sensor 2" of the first aspect of the invention, and the front end of the vehicle is an aspect of the "position deviated forward from the center of gravity".

The rear wheel steering angle control computer 10 determines its R
In the OM, a program represented by a flowchart in FIG. 4 is stored in advance, and the CPU of the OM executes the program to perform rear wheel steering angle control.

In the program shown in FIG. 1, first, in step S101 (hereinafter, simply referred to as S101; the same applies to other steps), a scheduled initial setting is performed.
The front wheel steering angle δ _F , the yaw rate γ, and the vehicle speed V are detected by 6, 18, and subsequently, in S103, it is estimated whether or not the vehicle is currently in an understeer state.

FIG. 5 is a flowchart showing details of this step. That is, the horizontal to first, in S1, based on said detected front wheel steering angle [delta] _F and vehicle speed V, the estimated that the vehicle is generated in its center of gravity when it is assumed to be in steady circular turning state Acceleration (hereinafter referred to as estimated lateral acceleration)
G ^* is determined. In the steady turning motion state, the front wheel steering angle δ
A certain relationship is established between _F , the vehicle speed V, and the estimated lateral acceleration G ^* as shown in the graph of FIG. Rear wheel steering angle control computer 10 is provided that relationship is also stored in advance in the ROM, in the present step, according to the relation, estimated lateral acceleration G corresponding to the front wheel steering angle [delta] _F and the vehicle speed V
^* Is determined. The estimated lateral acceleration G ^* can be calculated, for example, as a product of the vehicle speed V and the yaw rate γ.

[0023] Subsequently, in S2 of FIG. 5, the actual lateral acceleration G _F by the lateral acceleration sensor 20 is detected, subsequently, S
In 3, the absolute value of the estimated lateral acceleration G of the actual lateral acceleration G _F
^* If the absolute value positive threshold A ₀ or less a constant value than whether, i.e., the estimated lateral acceleration G ^* value threshold A minus the absolute value from the absolute value the actual lateral acceleration G _F It is determined whether it is ₀ or more. Assuming that this time is the case, the determination is YES, and in S4, it is estimated that the vehicle is in the understeer state. On the other hand, if not, the determination is NO, and in S5, the vehicle is in the understeer state. It is estimated that there is no. This completes one execution of this routine.

For example, as shown in the graph of FIG.
If the vehicle is in the steady turning motion state, estimated lateral acceleration G ^* and the actual lateral acceleration G _F match, as long the vehicle was the accelerated from this state, at the beginning, the estimated lateral acceleration G ^* and the actual lateral acceleration and G _F increases almost proportionally while being kept equal to each other. However, a front-wheel drive vehicle generally has an understeer tendency when the drive torque of the left and right front wheels that are the drive wheels increases. Therefore, when pivoted while being allowed to accelerate, estimated lateral acceleration G ^* is still to continue to rise substantially proportionally, the front portion of the vehicle will flow out to the outside of the turn, the actual lateral acceleration G _F is the estimated lateral acceleration G ^* (ie, lateral acceleration at the center of gravity of the vehicle)
Can not follow and follow. Based on these facts, in this embodiment, when the actual lateral acceleration G _F becomes smaller threshold A ₀ or more than the estimated lateral acceleration G ^*,
It is assumed that the vehicle has entered an understeer state.

Therefore, in this embodiment, the turning state can be estimated by providing only one lateral acceleration sensor 20, that is, whether or not the vehicle is in the understeer state can be estimated. The effect that the cost increase for can be suppressed small.

[0026] When the above manner once the turning state estimation is completed, then, in S104 of FIG. 4, the control coefficient K _F for the target value determining the rear wheel steering angle [delta] _R, is K _B are determined, in S105, the target value of the rear wheel steering angle [delta] _R is determined.

The rear wheel steering angle control computer 10 determines a target value of the rear wheel steering angle [delta] _R using the _{δ R = K F δ F +} K B γ becomes equation. Here, “K _F ” is a control coefficient that changes according to the vehicle speed V as shown in the graph of FIG.
" _B " is a control coefficient that changes according to the vehicle speed V as shown in the graph of FIG. These control coefficients K _F , K
_{For B} , a value for the normal state used when the vehicle is in the normal state and a value for the understeer state used when the vehicle is in the understeer state are prepared in advance. Control coefficient K _F, none of the K _B, for (control coefficient K _F so it is smaller than for the normal state for understeer state, the absolute value of it becomes larger, the control coefficient K _B, it This is set in advance so that the absolute value becomes smaller, so that when the vehicle is in the understeer state, the turning performance of the vehicle is improved as compared with the normal state, and the understeer tendency is reduced. Incidentally, in advance the relationship between the control coefficients K _F, turning the K _B and the vehicle speed V (or the vehicle is in understeer state or in a normal state) R
It is stored in the OM.

The control coefficients K _F, K _B from a normal state for understeer state, or from a understeer state is abruptly changed for the normal state, the rear wheel steering angle when the difference therebetween is larger [delta] _R Suddenly changes, the driver may feel uncomfortable. Therefore, the rear wheel steering angle control computer 10, from the normal state to the understeer state, or immediately from the understeer state just because it is determined to have shifted to the normal state, the control coefficient K _F, without changing the K _B, Figure 9
As one example of control shown in, if the transition from the normal state to the understeer state, the control coefficient K _F, gradually increase K _B, then transition to a predetermined time T _RT is passed from the understeer state to the normal state , The control coefficient K _F ,
Gradually reducing K _B.

In S104 of FIG. 4, the control coefficients K _F and K _B are determined as described above.
In their control coefficient K _F, and K _B, the vehicle speed V, the target value of the rear wheel steering angle [delta] _R by substituting the yaw rate γ in the equation is determined. Subsequently, in S106, the rear wheel steering angle actuator 24 is controlled so that the target value is realized. Then, the process returns to S102.

[0030] Thus, in this embodiment, for example, when the vehicle falls into understeer state to moderately strong acceleration is performed during turning of the vehicle, in that the control characteristic of the rear wheel steering angle [delta] _R is reduced understeer tendency Since the vehicle is changed, the vehicle is prevented from exhibiting a strong understeer tendency, and an effect is obtained that the operability of the vehicle is always maintained satisfactorily.

As is apparent from the above description, in this embodiment, the rear wheel steering angle control computer 10 of FIG.
Of the rear wheel steering angle control computer 10 constitutes one aspect of the "lateral acceleration estimation means 1" in the invention of claim 1 in cooperation with the front wheel steering angle sensor 14 and the vehicle speed sensor 18. The part that executes S2 to S5 in the figure constitutes one mode of the "turning state estimation means 3".

Next, a description will be given of a rear wheel steering angle control apparatus which is an embodiment common to the second aspect of the present invention. This embodiment has many parts common to the previous embodiment, and therefore only different parts will be described in detail.

This embodiment is different from the previous embodiment and is provided in a rear-wheel drive type four-wheel vehicle. In the present embodiment, the lateral acceleration sensor 20 is replaced by a
As shown in FIG. ₁ , a lateral acceleration sensor 50 for detecting the lateral acceleration GR at the rear end of the vehicle is provided. That is, the lateral acceleration sensor 50 is one embodiment of a "lateral acceleration sensor" in the invention of claim 2, the rear end of the vehicle is the aspect of "position deviated rearward from the center of gravity."

Further, in the present embodiment, a program corresponding to FIG. 4 is stored, but the execution contents of S103 and S104 in FIG. 4 are changed.

That is, with respect to S103, the routine of FIG. 5 is changed to a routine represented by a flowchart of FIG. 11 for estimating whether or not the vehicle has entered an oversteer state. This embodiment is provided in a rear-wheel drive vehicle. Unlike the front-wheel drive vehicle in the previous embodiment, this rear-wheel drive vehicle has a strong tendency to show oversteer during vehicle acceleration. Unlike the example, the vehicle is changed to one that estimates whether or not the vehicle is in an oversteer state.

In the routine shown in FIG.
1, the estimated lateral acceleration G is calculated in the same manner as in S101.
^* Is determined, subsequently, in S202, the actual lateral acceleration G _R is detected by the lateral acceleration sensor 50. afterwards,
In step S203, as in step S103, whether the absolute value of the actual lateral acceleration G _F is smaller than the absolute value of the estimated lateral acceleration G ^* by a threshold value A ₀ that is a positive constant value, ie, whether the estimated lateral acceleration G F ^* the absolute value minus the absolute value actual lateral acceleration G _F whether the threshold value a ₀ or not is determined. If so, the determination is YES, and the vehicle is presumed to be in an oversteer state in S204, whereas if not, the determination is NO and the vehicle is in an oversteer state in S205. It is estimated that there is no. This completes one execution of this routine.

Therefore, in this embodiment, the turning state can be estimated by providing only one lateral acceleration sensor 50, that is, whether or not the vehicle is in an oversteer state can be estimated. The effect that the cost increase for can be suppressed small.

On the other hand, the execution contents of S104 in FIG. 4 are changed as follows, and accordingly, the contents of FIG.
And the control coefficients K _F ,
Characteristics of K _B is also modified as follows.

[0039] That is, the control coefficient K _F, respectively K _B, FIG. 12 according to the vehicle speed V (a), is a control factor that varies as represented by the graph (b), the their control coefficient K _F, each for K _B, the vehicle is the value for the normal state to be used when in a normal state, and the value for the oversteer state for use when in the oversteer state are prepared in advance. Control coefficient K _F, none of the K _B, for (control coefficient K _F so it is greater than for the normal state for oversteer, the absolute value of it becomes small, the control coefficient K _B, it This is set in advance so that the absolute value becomes larger, so that the vehicle is more stable when in the oversteer state than in the normal state and the oversteer tendency is reduced.

Accordingly, S104 in FIG. 4 has been changed as follows. That is, the control coefficient K _F, the K _B, respectively, the vehicle is based on the whether that information and the vehicle speed V is in the oversteer state, and is changed to the rear wheel steering angle [delta] _R is determined not to sudden change It is.

[0041] Thus, in this embodiment, for example, when the vehicle falls into oversteer state to moderately strong acceleration is performed during turning of the vehicle, in that the control characteristic of the rear wheel steering angle [delta] _R is reduced to oversteer Since the vehicle is changed, the vehicle is prevented from exhibiting a strong oversteer tendency, and an effect is obtained that the operability of the vehicle is always maintained satisfactorily.

As is apparent from the above description, in this embodiment, the rear wheel steering angle control computer 10 of FIG.
The part that executes S201 of step 1 forms one aspect of the "lateral acceleration estimating means " in the invention of claim 2 in cooperation with the front wheel steering angle sensor 14 and the vehicle speed sensor 18, and the rear wheel steering angle control computer 10 The part that executes S202 to S205 in the figure constitutes one mode of “turning state estimating means ” .

Although the two embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be implemented in other embodiments.

For example, in each of the above embodiments, the turning state of the understeer state and the oversteer state are estimated. However, for example, other kinds of turning state, that is, the drift-out state and the spinning state, The present invention can also be implemented as estimating a turning state of the type called a state.

Further, both the embodiment has been an example of applying the present invention to wheel steering angle control system for controlling a rear wheel steering angle [delta] _R based on the estimation result of the turning state, Other vehicle motion control devices, i.e., for example,
The present invention can also be applied to a vehicle motion control device such as a drive torque distribution control device, a suspension control device, and a steering torque assist amount control device.

Other than these, the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a diagram conceptually showing a configuration of the present invention.

FIG. 2 is a system diagram showing a rear wheel steering angle control device which is an embodiment common to the first , third to fifth aspects of the present invention.

FIG. 3 is a plan view for explaining a position where the lateral acceleration sensor in FIG. 2 is mounted on a vehicle.

FIG. 4 is a flowchart showing a program used by a rear wheel steering angle control computer in FIG. 2;

FIG. 5 is a flowchart showing details of S103 in FIG. 4;

FIG. 6 shows a vehicle speed V used by the rear wheel steering angle control computer.
And is a graph illustrating the relationship between the front wheel steering angle [delta] _F and the estimated lateral acceleration G ^*.

FIG. 7 is a graph showing an example of a relationship between an estimated lateral acceleration G ^* and an actual lateral acceleration G in a vehicle turning state.

FIG. 8 shows a vehicle speed V used by the rear wheel steering angle control computer.
Each control coefficient K _F, and is a graph for explaining a relationship between a turning state and the K _B.

FIG. 9 is a graph showing an example of control by the rear wheel steering angle control device.

FIG. 10 is a plan view for explaining a position at which a lateral acceleration sensor is mounted on a vehicle in a rear wheel steering angle control device which is an embodiment common to the invention of claim 2 ;

FIG. 11 is a flowchart showing a turning state estimation routine used by a rear wheel steering angle control computer in the rear wheel steering angle control device.

12 is a graph for explaining a relationship between vehicle speed V and the control coefficient which the rear wheel steering angle control computer uses K _F, and K _B and the turning state.

[Explanation of symbols]

 Reference Signs List 10 rear wheel steering angle control computer 14 front wheel steering angle sensor 16 yaw rate sensor 18 vehicle speed sensor 20,50 lateral acceleration sensor 24 rear wheel steering angle actuator

Claims (5)

(57) [Claims] 1. A lateral acceleration estimating means for estimating a lateral acceleration at a center of gravity of a vehicle based on a vehicle motion state quantity, and detecting a lateral acceleration provided at a position of the vehicle deviated forward from the center of gravity. The lateral acceleration sensor and the actual lateral acceleration detected by the lateral acceleration sensor are
Less than the estimated lateral acceleration estimated by the lateral acceleration estimating means
The vehicle turns to an understeer state.
Vehicle turning state estimating apparatus which comprises a turning state estimation means for estimating that there. 2. A lateral acceleration estimating means for estimating a lateral acceleration at a center of gravity of a vehicle based on a vehicle motion state quantity, and detecting a lateral acceleration provided at a position deviated rearward from the center of gravity of the vehicle. The lateral acceleration sensor and the actual lateral acceleration detected by the lateral acceleration sensor are
Less than the estimated lateral acceleration estimated by the lateral acceleration estimating means
The turning state of the vehicle is over-steering
A turning state estimating means for estimating that there is a vehicle turning state estimating device. 3. A vehicle motion control device for controlling a motion state of a vehicle, comprising: a determination unit configured to determine, based on a motion state amount of the vehicle, whether or not the vehicle has entered an understeer state at the time of acceleration thereof; Control means for controlling the motion state so that the turning property of the vehicle is increased, in a case where the determination means determines that the vehicle has fallen into the understeer state at the time of acceleration thereof, as compared with the case where it is not the case. Vehicle motion control device. 4. A vehicle motion control apparatus for controlling a motion state of the vehicle, a first position spaced from one another in the longitudinal direction of the vehicle, the first
For a second position behind the position first lateral acceleration and the second
Acquisition means for acquiring the lateral acceleration, respectively; and the exercise state is such that when the acquired first lateral acceleration is smaller than the acquired second lateral acceleration, the turning property of the vehicle is increased as compared with otherwise. Control means for controlling the vehicle movement. Wherein said control means, first lateral acceleration obtained is, if less than the second lateral acceleration obtained, determines that the vehicle has fallen into an understeering state when it accelerates,
5. The vehicle motion control device according to claim 4 , wherein, when it is determined that the vehicle has entered an understeer state at the time of acceleration thereof, the motion state is controlled so that the turning performance of the vehicle is increased as compared with the case where it is not.