JPH0986378A - Turning behavior control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the behavior of a vehicle in a turning condition by carrying out the left and the right wheel driving force control and the left and the right wheel braking force control of a vehicle efficiently. SOLUTION: A left and right wheel driving force regulating mechanism to give the difference between the left wheel and the right wheel driving forces, and a braking force regulating mechanism to give the braking force differences between the wheels, of a vehicle are provided, the difference between an object yaw rate calculated depending on the car speed and the steering amount, and the actual yaw rate, is calculated as a yaw rate deflection by a yaw rate deflection calculating means, and the left and right wheel driving force regulating mechanism, and the braking force regulating mechanism are controlled integrally depending on the yaw rate deflection, in a control means. That is, by controlling the left and right wheel driving force regulating mechanism, and the braking force regulating mechanism integrally depending on the common control rule subject to the yaw rate deflection, the vehicle behavior in the turning condition is stabilized, as well as the control efficiency is increased.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to improvement of turning performance,
The present invention relates to a vehicle turning behavior control device capable of stabilizing vehicle behavior in a turning limit region.

[0002]

2. Related Background Art As a technique for controlling the behavior of a vehicle while turning to stabilize it, for example, Japanese Patent Laid-Open No. 4-1855
As disclosed in Japanese Patent Laid-Open No. 62-62, a braking force control that makes a difference in braking force between wheels according to a turning state of a vehicle, and JP-A-5-13
As disclosed in Japanese Patent No. 1855, there is left / right wheel driving force control that makes a difference in driving force between the left and right wheels according to the behavior of the vehicle.

The above braking force control has high responsiveness, and a large yaw moment can be obtained without a large additional object. Further, by applying a braking force to the turning outer wheel having a large ground load, spin avoidance control is performed. Has a great effect, and since the deceleration is automatically obtained by the control, there is an excellent effect such that safety can be improved when entering a corner at an overspeed. On the other hand, in the left and right wheel drive force control, deceleration hardly occurs during the control, so that a feeling of discomfort in vehicle steering is small, control is possible even during normal traveling, and drive according to the left and right wheel ground load during turning. Since the force can be distributed, the driving efficiency can be improved, and further, the understeer near the turning limit can be suppressed to improve the turning limit.

[0004]

On the other hand, in braking force control, on the other hand, deceleration occurs during the control, which causes a large discomfort, and it is not possible to distribute the driving force according to the left and right wheel ground loads during turning. However, there are drawbacks such as a large loss in terms of driving efficiency, and further suppression of understeer near the turning limit, but a large loss. Also, in the left and right wheel drive force control, the size of the mechanism is greatly limited in terms of weight and dimensions, so it is difficult to generate a large yaw moment, and in general, a wet multi-plate clutch is used. Since the control of the driving force distribution to the left and right wheels is inferior, the response is inferior.Furthermore, because the yaw moment magnitude and response are limited as described above, there are problems such as not being able to exert a sufficient effect during spin avoidance control. is there.

The present invention has been made in view of the above circumstances, and an object thereof is to ensure maneuverability without discomfort, improve turning performance, and vehicle behavior in a turning limit region where the yaw rate deviation is large. It is an object of the present invention to provide a vehicle turning behavior control device capable of stabilizing the vehicle and improving safety.

[0006]

In order to achieve the above object, a vehicle turning behavior control device according to the present invention includes a left and right wheel driving force adjusting mechanism for making a difference between left and right wheel driving forces of a vehicle, and each of the vehicles. A braking force adjusting mechanism for applying a braking force difference between the wheels is provided, and a target yaw rate is set based on the vehicle speed of the vehicle detected by the vehicle speed detecting means and the steering amount of the vehicle detected by the steering amount detecting means. The difference between the target yaw rate and the yaw rate of the vehicle detected by the yaw rate detecting means is calculated by the yaw rate deviation calculating means as a yaw rate deviation, and the control means calculates the left and right wheel drive force adjusting mechanism based on the yaw rate deviation. And the braking force adjusting mechanism is controlled in an integrated manner.

That is, the yaw rate is fed back based on a common control law for the left and right wheel drive force adjusting mechanism and the braking force adjusting mechanism, and these are integratedly controlled, thereby causing control interference between the both adjusting mechanisms. It is a matter of dividing roles and letting each of them exert their advantages. According to a second aspect of the present invention, when the yaw rate deviation does not exceed a predetermined threshold value in the control means, the left and right wheel drive force control by the left and right wheel drive force adjustment mechanism and the braking force control by the braking force adjustment mechanism are performed. Not to
The feature is that a dead zone region is provided. In other words, by having the above-mentioned dead zone in the control means,
It is characterized in that the control efficiency is improved by eliminating the needless control when there is almost no yaw rate deviation.

Further, in the invention according to claim 3, when the yaw rate deviation is greater than or equal to the first threshold value and less than the second threshold value, the control means only controls the left and right wheel driving force by the left and right wheel driving force adjusting mechanism. It is characterized by performing. That is, in the region where the yaw rate deviation is small, only the left and right wheel driving force control is performed, and the braking force control is not performed, so that the turning performance is improved without a loss in driving efficiency.

According to the invention described in claim 4, when the yaw rate deviation is equal to or more than the first and second threshold values, the control means controls the left and right wheel driving force by the left and right wheel driving force adjusting mechanism and the braking force adjusting mechanism. The feature is that power control is performed simultaneously. In other words, in a region where the yaw rate deviation is large, the left and right wheel driving force control and the braking force control are performed simultaneously to improve the vehicle behavior controllability at the turning limit, and to improve safety in combination with the deceleration effect. I am trying.

According to a fifth aspect of the present invention, particularly, as the control means in the fourth aspect of the invention, the left and right wheel drive by the left and right wheel drive force adjusting mechanism as the yaw rate deviation increases beyond the second threshold value. It is characterized by reducing the contribution rate of force control. In other words, the yaw rate deviation becomes large, and the effect of the braking force control becomes prominent exclusively as the turning limit is approached. Therefore, the overall control efficiency is improved by gradually suppressing the left and right wheel driving force control. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a vehicle turning behavior control device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram of a vehicle in which the embodiment apparatus is incorporated, in which 1 is a vehicle body and 2 (2FL, 2F).
R, 2RL, 2RR) represent front, rear, left and right wheels. Reference numerals 3 (3FL, 3FR, 3RL, 3RR) denote brake mechanisms provided on the respective wheels 2, and the respective brake mechanisms 3 are individually operated and controlled under the brake pressure control mechanism 4 so that each of them is controlled. Braking is applied to the wheels 2. The brake pressure control mechanism 4 applies a braking force (braking force) corresponding to the pedaling force of the brake pedal 5 to each brake mechanism 3, and based on an instruction from the brake pressure drive circuit 6, each brake mechanism 3 will be described later. It plays a role in making a difference in the braking force applied to the vehicle.

On the other hand, in this example, the driving force is transmitted to the rear wheels 2RL and 2RR via the driving force transmission mechanism 7. The driving force transmission mechanism 7 is a so-called left / right wheel driving force moving differential that allows a differential between the left wheel 2RL and the right wheel 2RR and distributes the driving force transmitted to them at a required ratio. It is a thing. Such a driving force transmission mechanism (left and right wheel driving force moving differential) is disclosed in, for example, Japanese Patent Laid-Open No.
As described in detail in Japanese Unexamined Patent Publication No. 131855, a transmission mechanism and a multi-disc clutch mechanism are provided between the input shaft and the left and right wheels 2RL and 2RR, respectively. Then, the driving force transmission mechanism 7
The distribution of the driving force to the left and right wheels 2RL and 2RR in
It is controlled by the driving force movement drive circuit 8 under the control described later.

The CPU (Central Processing Unit) 9 is detected by the vehicle speed (wheel speed) detected by the vehicle speed detecting means, the vehicle steering amount (steering wheel angle) detected by the steering amount detecting means, and the yaw rate detecting means. Based on the information on the yaw rate that has occurred in the vehicle, the brake pressure drive circuit 6 and the drive force movement drive circuit 8 function as control means as described later.

That is, the CPU 9 functionally calculates the target yaw rate during turning based on the vehicle speed and the steering wheel angle as shown in FIG.
a, a yaw rate deviation calculating means 9b for calculating a difference between the target yaw rate and a yaw rate (actual yaw rate) actually occurring in the vehicle body 1 as a yaw rate deviation Δφ, and the wheels 2RL, 2RR according to the yaw rate deviation Δφ.
Difference in driving force distribution (moving torque ΔT)
And a braking force calculation means 9d for obtaining a braking force applied to each of the brake mechanisms 3 in accordance with the yaw rate deviation Δφ. In particular, when the yaw rate deviation Δψ exceeds the preset first threshold value Tha, the moving torque calculating means 9c obtains the moving torque ΔT according to the yaw rate deviation Δψ, and the braking force calculating means 9d. Is
The second threshold Thb for which the yaw rate deviation Δφ is set in advance.
When (> Tha) is exceeded, the braking force information BL, BR corresponding to the yaw rate deviation Δφ is obtained.

Specifically, the CPU 9 advances the processing procedure according to the procedure shown in FIG. 3 to obtain the moving torque ΔT and the braking force information BL and BR corresponding to the yaw rate deviation Δψ, respectively.
Output this. Explaining this processing procedure,
The CPU 9 inputs the steering wheel angle θ, the vehicle speed V, and the actual yaw rate ψ every predetermined period (step S1), and calculates the target yaw rate ψ * according to these input information (step S).
2). This target yaw rate ψ * is given, for example, when the front wheel steering angle δf is given as [steering wheel angle / steering gear ratio], the rear wheel steering angle δr, the wheel base length is L, and the stability factor is A. Calculated as * = V (δf−δr) / L (1 + AV ² ).

When the target yaw rate ψ * is calculated, the yaw rate deviation Δψ is calculated as Δψ = ψ * −ψ (step S3), and the magnitude thereof is determined (steps S4 and S5). This determination is based on whether or not the yaw rate deviation Δψ is larger than the first threshold Tha, and
If it is larger than the threshold Tha of the above, it is performed by determining whether it is smaller than the second threshold Thb. Then, according to the magnitude of the yaw rate deviation Δφ, it is divided into three cases of | Δφ | <Tha Tha ≤ | Δφ | <Thb Thb ≤ | Δφ |.

By this determination processing, the yaw rate deviation Δψ
If the above condition is determined as being less than the first threshold Tha, the yaw rate deviation Δψ is substantially small enough to be neglected. In order not to operate the control unnecessarily, the moving torque ΔT is set to [0], and the braking force information BL and BR for the left and right wheels are set to [0] (step S6).

On the other hand, when the yaw rate deviation Δψ has a certain magnitude and it is determined that the above conditions are satisfied, the yaw rate deviation Δψ is small, so that only the left and right wheel drive force control should be activated. , The moving torque ΔT corresponding to the yaw rate deviation Δψ at that time is calculated, and the braking force information BL and BR for the left and right wheels are set as [0] (step S7).

If it is determined that the yaw rate deviation Δψ is large and the above condition is satisfied, the movement torque ΔT corresponding to the yaw rate deviation Δψ at that time is set so that the braking force control is operated together with the left and right wheel drive force control. Calculate,
At the same time, braking force information BL, BR for the left and right wheels is calculated according to the yaw rate deviation Δφ (step S8). Thus, the moving torque ΔT calculated according to the magnitude of the yaw rate deviation Δψ and the braking force information B for the left and right wheels
By outputting L and BR, the driving force movement drive circuit 8 and the brake pressure drive circuit 6 respectively operate (step S9).

That is, the drive force movement drive circuit 8 controls the operation of the drive force transmission mechanism 7 according to the information of the movement torque ΔT obtained by the CPU 9 as described above, and the left wheel 2RL and the right wheel 2RR are respectively controlled. The given driving force is moved by ΔT between the wheels 2RL and 2RR. This wheel 2RL, 2
A yaw moment is applied to the vehicle body 1 by moving the torque ΔT between RRs, that is, by distributing the driving force between the left and right wheels.

By the way, as shown in FIG. 4A, when the driving force is moved by ΔT between the rear wheels 2RL and 2RR, a yaw moment as indicated by an arrow is given to the vehicle body 1. Such a yaw moment is similarly generated when the driving force is moved on the front wheel side, and is similarly generated when the driving force is moved on each of the front and rear wheels. Therefore, the control target of the moving torque is not limited to the rear wheel side. Furthermore, since the amount of movement of the drive torque is determined according to the yaw rate deviation Δφ, it can be applied as a constant control law regardless of the acceleration / deceleration situation.

Further, the brake pressure drive circuit 6 controls the brake pressure control mechanism 4 in accordance with the braking force information BL, BR obtained by the CPU 9 as described above, and each of the brake mechanisms 3 is controlled.
The braking force is individually applied to the vehicle body 1 to give a yaw moment to the vehicle body 1. For example, when the braking force BR is applied only to the right front wheel 2FR as shown in FIG. 4B according to the braking force information BL and BR for the left and right wheels, a yaw moment as indicated by an arrow is applied to the vehicle body 1. . Incidentally, when the braking force is applied to each of the front, rear, left and right wheels 2 according to the pedaling force of the brake pedal 5, as shown in FIG. 4 (c), the braking force BR is further added to the braking force by the foot brake.
Therefore, the yaw moment as indicated by the arrow is similarly given. Such a yaw moment occurs not only in the braking force control on the front wheels side, but also in the braking force control on the rear wheels side, and by extension, on the braking force control for all the front and rear wheels. The rules are applicable. Further, it can be applied as a constant control law regardless of the acceleration / deceleration situation.

Thus, as described above, the yaw rate deviation Δ
The control system of the embodiment apparatus that integrally performs the driving force movement control and the braking force control according to ψ is conceptually expressed as shown in FIG. That is, an area in which the yaw rate deviation Δφ is less than the first threshold value Tha is set as a dead zone for control, and the driving force movement control and the braking force control are not performed in this dead zone area. Further, a region where the yaw rate deviation Δψ exceeds the first threshold Tha is defined as a control region for performing the driving force movement control, and a region where the yaw rate deviation Δψ exceeds the second threshold Thb is controlled in addition to the driving force movement control. It is defined as a control range for power control. Then, the yaw rate is given to the vehicle body 1 by performing control according to each of the above control areas according to the yaw rate deviation Δφ.

Specifically, in FIG. 5, when the braking force addition control is performed on the left and right wheels on the front wheel side and the left and right wheels driving force is moved on the rear wheel side, the movement of the driving force and the addition of the braking force are performed. As the concept is schematically shown, the yaw rate deviation Δψ is [A, B, C,
D], the driving force is moved and the braking force is added as shown in the figure. Then, depending on whether the vehicle is turning to the left or to the right, and depending on whether the yaw rate deviation Δψ at that time is positive or negative, an oversteer (OS) or an understeer (US) yaw moment is applied to the vehicle body 1. Will be given.

Thus, according to the above-described control, when the yaw rate deviation Δφ is close to [0], which is less than the first threshold value Tha, this is regarded as a normal traveling state, and the driving force movement control and control are performed. Power control is not performed, so there is no control burden. In other words, it is possible to improve the control efficiency by eliminating the needless control when there is almost no yaw rate deviation.

Further, the yaw rate deviation Δψ is the first threshold Th.
In a small area that exceeds a, only the driving force movement control for the left and right wheels is performed, so smooth and decelerating travel can be realized. Moreover, since the driving force can be distributed according to the left and right wheel ground loads during turning, the driving efficiency can be increased and the turning performance can be effectively improved. Further yaw rate deviation Δ
In a large region where ψ exceeds the second threshold Thb, for example, in a region close to the turning limit in the case of emergency avoidance, in addition to the driving force movement control between the left and right wheels described above, additional control of the braking force to each wheel 3 is performed. Therefore, a large yaw moment can be applied to the vehicle body 1 simply and efficiently, and the vehicle behavior can be effectively stabilized. Moreover, the braking force applied to each wheel 3 can also provide a deceleration effect, which greatly contributes to the improvement of safety when the vehicle enters a corner at an excessive speed, for example.

Moreover, as described above, the yaw rate given to the vehicle body 1 is controlled according to a common control rule that the deviation from the target yaw rate is reduced by feeding back the yaw rate, but the yaw rate deviation Δψ is controlled to the magnitude. Since the control mode is changed accordingly, the driving force movement control for the left and right wheels and the braking force control for each wheel can be effectively divided and the advantages thereof can be mutually derived. Further, since no control interference is caused between the two control systems, it is possible to achieve the effect of enabling efficient vehicle turning control by making the most of the advantages of the driving force movement control and the braking force control.

The present invention is not limited to the above embodiment. For example, in a situation where the yaw rate deviation Δψ is large and the braking force control is performed accordingly, the effect of applying the yaw moment by the braking force control is greater, so
As shown in FIG. 6, the contribution rate of the driving force movement control may be gradually reduced to reduce the control load. By doing so, for example, when the braking force by the foot brake is applied to enter the operating range of the ABS (anti-skid braking system), the driving force movement control and the A
It is possible to prevent the possibility that the BS control resonates unintentionally. In addition, various modifications can be made without departing from the scope of the invention.

[0029]

As described above, according to the present invention, the driving force movement control between the left and right wheels and the braking force addition control for each wheel are integrally controlled according to a common control rule based on the yaw rate deviation. Therefore, the driving force movement control and the braking force addition control can be effectively divided into roles, and the behavior of the vehicle at the time of turning can be effectively controlled. Moreover, when the yaw rate deviation is small, the turning performance is improved by control that does not cause discomfort, and when the yaw rate deviation is large, a large yaw moment is generated to stabilize the vehicle behavior and, in combination with the deceleration effect, the safety is improved. A great effect such as improving the property can be obtained.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a vehicle incorporating a turning behavior control device according to an embodiment of the present invention.

FIG. 2 is a functional configuration diagram schematically showing the role of a CPU in the apparatus of the embodiment.

FIG. 3 is a diagram showing a flow of processing procedures in the apparatus of the embodiment.

FIG. 4 is a diagram schematically showing the concept of a yaw moment generated by the movement of the torque by the driving force movement control and the addition of the braking force by the braking force control.

FIG. 5 is a diagram conceptually showing an integrated control system of driving force movement control and braking force control according to the present invention.

FIG. 6 is a diagram showing a modified example of an integrated control system for driving force movement control and braking force control.

[Explanation of symbols]

 1 Vehicle body 2 (2FL, 2FR, 2RL, 2RR) Wheels 3 (3FL, 3FR, 3RL, 3RR) Brake mechanism 4 Brake pressure control mechanism 5 Brake pedal 6 Brake pressure drive circuit 7 Driving force transmission mechanism (left and right wheel driving force movement) 8) Driving force movement drive circuit 9 CPU 9a Target yaw rate calculation means 9b Yaw rate deviation calculation means 9c Moving torque calculation means 9d Braking force calculation means

Claims (5)

[Claims] 1. A left / right wheel driving force adjusting mechanism for making a difference between left and right wheel driving forces of a vehicle, a braking force adjusting mechanism for making a braking force difference between respective wheels of the vehicle, and a vehicle speed detection for detecting a vehicle speed of the vehicle. Means, a steering amount detecting means for detecting a steering amount of the vehicle, a yaw rate detecting means for detecting a yaw rate generated in the vehicle, a target yaw rate based on the steering amount and a vehicle speed, and the target yaw rate and the yaw rate. A yaw rate deviation calculating means for obtaining a difference from the yaw rate detected by the detecting means as a yaw rate deviation, and a control means for integrally controlling the left and right wheel drive force adjusting mechanism and the braking force adjusting mechanism based on the calculated yaw rate deviation. A turning behavior control device for a vehicle, comprising: 2. The dead zone region in which the control means does not perform left / right wheel drive force control by the left / right wheel drive force adjustment mechanism and braking force control by the braking force adjustment mechanism until the yaw rate deviation exceeds a predetermined threshold value. The turning behavior control device for a vehicle according to claim 1, wherein: 3. The yaw rate deviation is first
2. The turning behavior control device for a vehicle according to claim 1, wherein only the left and right wheel drive force control by the left and right wheel drive force adjustment mechanism is performed when the threshold value is equal to or more than the threshold value and is less than the second threshold value. 4. The yaw rate deviation is the first
And when the second threshold value is exceeded, the left and right wheel drive force control by the left and right wheel drive force adjustment mechanism and the braking force control by the braking force adjustment mechanism are simultaneously performed.
Alternatively, the vehicle turning behavior control device according to claim 3. 5. The yaw rate deviation is second
5. The turning behavior control device for a vehicle according to claim 4, wherein the contribution ratio of the left and right wheel driving force control by the left and right wheel driving force adjusting mechanism is reduced as the value exceeds the threshold value.