JP2001018774A - Vehicle behavior control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the quality of control by always varying according to a lateral slip angle and a lateral slip angular velocity a threshold value at which the start of control is determined, and optimizing the threshold value so that the lateral slip angle does not exceed a maximum allowable value. SOLUTION: In this vehicle behavior control device having a control means (c) adapted to effect vehicle behavior control by which a yaw moment generating mechanism (a) is actuated when an input from a vehicle behavior detecting means (b) meets a condition for starting the control, the control means (c) meets β0-β-(I0.Δβ2/2Y0)<0; YM=-Y0 and β0+β-(I0.Δβ2/2Y0)<0 when Δβ>0; and YM=Y0 when Δβ<0 wherein βis lateral slip angle, β0 is the maximum allowable value of the lateral slip angle β, I0 is the yaw inertial moment of the vehicle, YM is the yaw moment generated by the yaw moment generating mechanism, and Y0 is the absolute value of the yaw moment YM.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an automobile,
For example, changing the distribution of the driving force between the left and right driving wheels, or generating a braking force on a predetermined wheel out of the four wheels, or steering the rear wheel, generates a yaw moment in the vehicle, and the vehicle behaves. The present invention relates to a control technique of a vehicle behavior control device that controls a vehicle.

[0002]

2. Description of the Related Art Conventionally, when behavior of a vehicle becomes unstable such as in an over-steer state, a vehicle behavior control for generating a yaw moment in a direction to stabilize the vehicle and executing control for stabilizing the vehicle behavior. As an apparatus, a technique described in, for example, Japanese Patent Application Laid-Open No. 8-295216 is known.

In this prior art, a spin area is set based on the coordinates of a skid angle and a skid angular velocity, and it is determined whether or not a spin value is in a spin area. Control to generate a yaw moment in a direction to suppress spin.

[0004]

However, in the above-described vehicle behavior control device, the boundary line (threshold) for determining the spin region in the coordinates of the sideslip angle and the sideslip angular velocity has no physical meaning. Since the linear characteristics are set, it is inappropriate to determine whether or not control is necessary. That is, if the sideslip angle in the vicinity of the sideslip angular velocity of 0 is optimally set, the spin region becomes unduly wide in a region where the sideslip angular velocity is high. In other words, if you try to set the boundaries so that the vehicle never spins,
It is necessary to set the boundary line optimally in the low range of the sideslip angular velocity. In this case, the margin on the non-spin side is wide and the setting of the boundary line is low overall (the non-spin side Therefore, the frequency of executing unnecessary control becomes high in the middle and high speed sideslip angular velocities. Therefore, in this region, the driver may feel uncomfortable. Conversely, if the boundary line is optimally set in the medium / high speed range of the side slip angular velocity, the boundary line may enter the spin region in the low range of the side slip angular velocity, and spin may occur.

The present invention has been made in view of the above-mentioned problems, and the threshold value for judging the start of control is constantly varied by the sideslip angle and the sideslip angular velocity so that the sideslip angle does not exceed the maximum allowable value. The purpose of this is to improve the control quality by optimizing the threshold value.

[0006]

In order to achieve the above-mentioned object,
As shown in the claim correspondence diagram of FIG. 1, the present invention detects a yaw moment generating mechanism a that generates a yaw moment in a vehicle by a mechanism that applies a braking / driving force difference between left and right wheels or a rear wheel steering mechanism, and detects a vehicle behavior. Vehicle behavior detecting means b
And when the input from the vehicle behavior detecting means b becomes a predetermined control start condition, the yaw moment generating mechanism a
And a control unit c configured to execute vehicle behavior control for stabilizing the behavior of the vehicle by operating the vehicle behavior control device.
When the maximum allowable value of the side slip angle β is β0, the yaw moment of inertia of the vehicle is I0, the yaw moment generated by the yaw moment generating mechanism is YM, and the absolute value of the yaw moment YM is Y0, β0−β− (I0 · Δβ ² / 2Y0) <0
, And the and, when △ beta ≧ 0, and YM = -Y0, also, β0 + β- (I0 · △ β 2 / 2Y0) < 0, and △ beta <When 0, YM = Y0 It is characterized by the following. In the present invention, the threshold value as the control start condition is set based on the physically significant allowable value using the sideslip angle and its differential value. It can be performed accurately without any shortage.

[0007] According to a second aspect of the present invention, the control
The means c is defined as β0-β- (I0 △ Δβ² / 2Y0) <0
And △ β ≧ 0, or β ≧ β0, and
Δβ <0 and β0 + β− (I0 △ Δβ²/ 2Y0)
> 0, YM = −Y0, and β0 + β− (I
0 · △ β²/ 2Y0) <0 and △ β <0
Time or β <-β0 and △ β> 0 and β
0-β- (I0 ・ △ β ²/ 2Y0)> 0, YM
= Y0. Therefore,
According to the second aspect of the present invention, the road surface friction coefficient is changed.
Accordingly, even if the sign of the sideslip angular velocity changes
Thus, accurate control can be executed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is an overall view of the vehicle behavior control device according to the embodiment. As shown in FIG.
, A sensor group 100 and a controller 18.

The differential device 1 includes a left and right driving force distribution device corresponding to a yaw moment generating mechanism. The configuration of the differential device 1 will be described with reference to the schematic configuration diagram of FIG. The basic configuration of the differential 1 shown in FIG. 1 is the same as that of the conventional differential, and the rotational force of the propulsion shaft 2 is transmitted to the differential case 5 by the small reduction gear 3 and the large reduction gear 4.
, And the rotational force of the differential case 5 is equally distributed to the left and right wheel shafts 9 and 10 by the differential small gear 6 and the differential large gears 7 and 8. The rotation of the differential small gear 6 causes the left and right wheel shafts 9 and 10 to rotate.
Is absorbed. In the drawing, reference numeral 11 denotes a differential housing as a main body of the differential device 1, 12 denotes a left wheel, and 13 denotes a right wheel.

The left and right driving force distribution device according to the present embodiment includes a hydraulic piston motor 20 capable of applying a relative rotational force between the left wheel shaft 9 and the differential case 5, and a hydraulic piston motor 20 by rotating the differential case 5. And a hydraulic piston pump 30 for generating pressure. Note that, for example, an axial piston motor is used as the hydraulic piston motor 20, and a radial piston pump is used as the hydraulic piston pump 30.

The hydraulic oil discharged from the hydraulic piston pump 30 through the line L13 is adjusted by the pressure adjusting valve 16 and then led out to the switching valve 17. The pressure adjusting valve 16 is configured to adjust the hydraulic pressure according to a control signal from the controller 18 and discharge the relief hydraulic oil to the reservoir 15.

The switching valve 17 is a four-port, three-position switching valve that is switched and controlled by the controller 18, and is capable of obtaining first, second, and third position switching states according to the switching position. The first switching state is a state where the input ports P1 and P2 communicate with each other and the output ports P3 and P4 communicate with each other as shown in FIG. 3, and the second switching state is a state where the input port P1 and the output port P3 communicate with each other. And the input port P2 communicates with the output port P4. The third switching state is a state in which the input port P1 communicates with the output port P4 and the input port P2 communicates with the output port P3. It is.

The hydraulic piston pump 20 is connected to a line L1.
When the hydraulic pressure is supplied from 1, the left wheel axle 9 is rotated in the speed increasing direction with respect to the differential case 5, while when the hydraulic pressure is supplied from the line L <b> 12, the left wheel axle 9 is rotated with respect to the differential case 5. To rotate in the deceleration direction. Since the details are not the subject of the present application, they are omitted in the present specification, but refer to, for example, JP-A-10-329572.

Therefore, when the switching valve 17 is in the first switching state as shown in FIG.
Is permitted and the switching valve 17 is in the second switching state, the hydraulic oil from the hydraulic piston pump 30 is introduced into the pipeline L11 of the hydraulic piston motor 20 and the left wheel with respect to the differential case 5 The shaft 9 is accelerated while the right wheel shaft 10 is decelerated, and the switching valve 17
, The hydraulic oil from the hydraulic piston pump 30 is introduced into the pipeline L12 of the hydraulic piston motor 20, and the left wheel shaft 9 is decelerated with respect to the differential case 5 while the right wheel shaft 10 Is increased. The speed increase amount and the deceleration amount at this time are determined based on the adjustment pressure of the pressure adjustment valve 16.

Next, the vehicle behavior control by the controller 18 will be described. FIG. 4 is a flowchart showing the start determination and the control amount determination in the vehicle behavior control. First, in step 101, a side slip angle β is obtained based on an input from the sensor group 100. This side slip angle β can be obtained from the ratio (Vx / Vy) between the longitudinal speed Vx and the side slip speed Vy of the vehicle as in the prior art, and can be calculated from the yaw rate △ ψ, the lateral acceleration △△ Y, and the vehicle speed V of the vehicle. The rear wheel cornering power estimated value PC is calculated by the following equation (1), and the rear wheel cornering power estimated value PC is calculated.
It is also possible to estimate the side slip angle β by the following equation (2) using the yaw rate signal △ ψ and the yaw rate signal △ ψ. PC = (V / h) (ma △△ Y-I △ ψs) s / [△ ψ (bs + V)-△△ Y) + f (△△ Y) (1) β = -Kbr [(Tb S + 1) / (Tr · s + 1)] △ ψ (2) where s is the Laplace operator, m is the vehicle mass, and a is the longitudinal direction from the center of gravity of the vehicle to the front wheel axle. Distance, b is the longitudinal distance from the center of gravity of the vehicle to the rear wheel axle, h is the wheel base, I is the moment of inertia of the vehicle,
In the equation (1), the first term on the right side is the cornering power of the rear wheel analytically obtained from the two-wheel model of the vehicle,
F (△△ Y) in the second term on the right side of the equation is a correction term based on the lateral acceleration. Kbr = (1− (ma / (hbPC)) V
² ) (b / V), Tb = IV / (hbPC-maV)
² ), Tr = [ma / hPC)] V.

In step 102, β0-β- (I0 ·
It is determined whether or not Δβ ² / 2Y0) <0 and Δβ ≧ 0, and in the case of YES, the routine proceeds to step 103, where the yaw moment YM generated by the differential 1 is −Y.
Set to 0.

On the other hand, if NO is determined in step 102, the process proceeds to step 104, where β0 + β− (I0 · ０
β ² / 2Y0) <0 and △ β <0 is determined, and in the case of YES, the routine proceeds to step 105,
It is assumed that the momentum generated by the differential device 1 is YM = Y0. If the determination in steps 102 and 104 is NO, the flow ends once without performing the processing. In steps 102 and 104,
β0 is an allowable value of the sideslip angle and is a value determined based on the vehicle performance. I0 is the yaw moment of inertia of the vehicle. Y0 is a yaw moment generated by the differential device 1. In this case, since the control is for emergency avoidance, the absolute value of the generated yaw moment is fixed, and the left and right directions of the generated yaw moment are made different. I have to. In addition, steps 102 and 10
FIG. 5 shows the control determination threshold value according to the example No. 4. As shown in this figure, in the present embodiment, when the sideslip angle β increases, the control starts even at a small slip speed 大 き く β, and when the sideslip angle β decreases, the control starts at a high slip speed △ β. The threshold value is not a linear characteristic as in the prior art, but a curve based on a performance target value β0 based on vehicle specifications.

In the present embodiment described above, when the sideslip angle β becomes abnormally large, or when the sideslip angle is likely to become abnormally large, that is, when the control condition of step 102 or 104 in FIG. ,
As an emergency avoidance operation, the differential device 1 generates a yaw moment in one of the left and right directions by a preset control amount Y0 (absolute value), and the vehicle changes from the abnormal state to the over-oversteer state. Can be prevented. At this time, in the present embodiment, since the threshold value for determining whether to execute this control is determined based on the performance target value β0, the control becomes excessive or the control is delayed. Therefore, it is possible to control the vehicle so that the side slip angle β does not exceed an allowable value.

Furthermore, in the first embodiment, when the side slip angle β is estimated using the estimated cornering power value PC of the rear wheels and the yaw rate signal △ ψ, it is necessary to store past time-series data for a certain period of time. Therefore, it is possible to accurately estimate the side slip angle β even for a sudden road surface change, prevent the performance of the system from deteriorating, and reduce the load on the memory to make the device inexpensive. .

(Embodiment 2) In Embodiment 2, steps 102 and 10 of the embodiment shown in FIG.
The judgment of No. 4 is partially different. That is, FIG.
As shown in the flowchart of FIG.
β0-β- (I0 · △ β 2 / 2Y0) < 0, and, △ beta ≧ 0, or, beta ≧ [beta] 0 and,, △ beta <0 and,, β0 + β- (I0 · △ β 2 / 2Y0)> 0 is determined, and in the case of YES, the routine proceeds to step 103, where Y
M = −Y0, and in step 204, β0 + β−
(I0 · △ β ² / 2Y0) <0, and Δβ <
0 or β <−β0 and Δβ> 0 and β0−
It is determined whether or not β− (I0 △ Δβ ² / 2Y0)> 0, and in the case of YES, the routine proceeds to step 105, where YM = Y
The process of setting to 0 is executed.

That is, in the second embodiment, the threshold values are as shown in FIG. In the second embodiment, even if the sign of the side slip angle β changes due to a disturbance or a change in the road surface μ (a so-called μ jump), the control is continued without suspending the control, and the vehicle is over-oversteered. (Particularly, in a control region near the maximum value of the sideslip angle β).

Although the embodiment has been described with reference to the drawings, the present invention is not limited to the configuration of the above embodiment. For example, in the embodiment, a device that changes the left and right driving force distribution is used as the yaw moment generating mechanism. However, a device that generates a braking force on any of the four wheels or a device that steers the rear wheels is used. In short, any device that can control the yaw moment of the vehicle may be used.

[0023]

As described above, according to the present invention, the threshold value as the control start condition is set based on the physically meaningful allowable value using the sideslip angle and its differential value. Thus, the effect that the control start determination can be accurately performed without excessive control or insufficient control can be obtained. According to the second aspect of the present invention, even when the sign of the side slip angular velocity changes in accordance with the change in the road surface friction coefficient, it is possible to execute appropriate control in response to the change, and furthermore. Control accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle behavior control device of the present invention.

FIG. 2 is a configuration explanatory view showing a vehicle behavior control device according to an embodiment.

FIG. 3 is a sectional view showing a main part of the embodiment.

FIG. 4 is a flowchart illustrating a control flow according to the first embodiment.

FIG. 5 is a control range characteristic diagram of the first embodiment.

FIG. 6 is a flowchart illustrating a control flow according to the second embodiment.

FIG. 7 is a control range characteristic diagram according to the second embodiment.

[Explanation of symbols]

 a yaw moment generating mechanism b vehicle behavior detecting means c 1 differential gear 2 propulsion shaft 3 reduction small gear 4 reduction large gear 5 differential case 6 differential small gear 7,8 differential large gear 9,10 wheel shaft 11 differential housing 12 Left wheel 13 Right wheel 16 Pressure adjusting valve 17 Switching valve 18 Controller 20 Hydraulic piston motor 30 Hydraulic piston pump 100 Sensor group

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D034 CA02 CA10 CC01 CD20 CE08 CE12 CE13 CE15 3D045 BB40 FF42 GG00 GG25 3D046 BB21 GG07 HH21 HH25 JJ01 LL23

Claims (2)

[Claims] 1. A yaw moment generating mechanism for generating a yaw moment in a vehicle by a mechanism for providing a braking / driving force difference between left and right wheels or a rear wheel steering mechanism, vehicle behavior detecting means for detecting vehicle behavior, and vehicle behavior detection Control means configured to execute the vehicle behavior control for stabilizing the behavior of the vehicle by activating the yaw moment generating mechanism when an input from the means becomes a predetermined control start condition. In the above, the control means may set the side slip angle to β, the maximum allowable value of the side slip angle β to β0, the yaw moment of inertia of the vehicle to I0, the yaw moment generated by the yaw moment generating mechanism to YM, and the absolute value of the yaw moment YM to Y0. And β0-β-
(I0 △ Δβ ² / 2Y0) <0, and Δβ ≧
0, YM = −Y0, and β0 + β− (I
0 · △ β ² / 2Y0) <0, and when Δβ <0, the vehicle behavior control device is configured to satisfy YM = Y0. 2. The control means according to claim 1, wherein β0-β- (I0０β
² / 2Y0) <0 and Δβ ≧ 0, or β ≧ β0, Δβ <0, and β0 + β− (I
0 · △ β ² / 2Y0)> 0, YM = −Y0, β0 + β− (I0 △ Δβ ² / 2Y0) <0, and Δβ <0, or , Β <-β0 and △ β> 0, and β0-β- (I0０Δβ ² / 2Y
2. The vehicle behavior control device according to claim 1, wherein YM = Y0 when 0)> 0.