JP3703635B2 - Vehicle behavior control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle behavior control apparatus for suppressing abnormal vehicle behavior such as drift-out and spin of a vehicle during traveling, and more particularly to a behavior control apparatus for a front-wheel drive vehicle.
[0002]
[Prior art]
A conventional control device that detects the occurrence of an unstable state such as vehicle drift-out or spin and controls the behavior of the vehicle to suppress the drift-out or spin is calculated based on data obtained from various sensors. The behavior of the vehicle is controlled according to the deviation between the target yaw rate to be obtained and the yaw rate of the vehicle obtained from the yaw rate sensor. In Japanese Patent Laid-Open No. 4-143129, when a turning abnormality occurs in which the side slip becomes excessive during turning of the vehicle and the turning state does not correspond to the operation of the steering device, at least one braking force and at least one wheel A vehicle turning control device for controlling driving force is disclosed.
[0003]
[Problems to be solved by the invention]
In the conventional technology such as the vehicle turning control device disclosed in Japanese Patent Laid-Open No. 4-143129, the driving force is controlled regardless of the oversteer state and understeer state of the vehicle. Generally, it is known that if the speed of the vehicle is reduced by reducing the driving force of the vehicle, the vehicle goes to a stable state. However, in a front-wheel drive vehicle, the driving force is increased in an oversteer state. It is possible to avoid an oversteer condition. However, in the conventional technology, even in such a front-wheel drive vehicle, since the driving force is suppressed in the oversteer state, there is a possibility that not only the escape from the oversteer state by the operation of the driver is disturbed but also the oversteer state is promoted. there were.
[0004]
On the other hand, conventionally, driving force control by vehicle behavior control and driving force control by traction control system (hereinafter referred to as TCS control) have been carried out independently, but by vehicle behavior control and TCS control. It is conceivable that the driving force is controlled simultaneously. In such a case, there was a problem of how to perform driving force control.
[0005]
The present invention has been made to solve the above-described problems. In a front-wheel drive vehicle, when the vehicle is in an oversteer state, the amount of decrease in driving force is reduced to 0 or the vehicle is oversteered. When not in the state, the larger value of the driving force decrease calculated during the behavior control and the TCS control is used to avoid the oversteer state without disturbing the escape from the oversteer state by the driver's operation. Therefore, an object of the present invention is to obtain a vehicle behavior control device that can achieve both TCS control and TCS control.
[0006]
[Means for Solving the Problems]
The vehicle behavior control apparatus according to the present invention determines a vehicle state from a deviation between a target yaw rate calculated based on data obtained from various sensors and a vehicle yaw rate obtained from a yaw rate sensor, and performs the determination. In accordance with the behavior control device that performs the behavior control of the front-wheel drive vehicle by performing the predetermined braking force control and the driving force control in response,
A vehicle state calculation unit that calculates the deviation and compares the calculated deviation with each threshold value for determining the state of the vehicle to determine oversteer and understeer of the vehicle;
A driving force control unit that controls the driving force according to the determination by the vehicle state calculation unit ;
A spin detector that detects spin in the drive wheel and calculates the spin rate of the drive wheel;
With
The driving force control unit, when the vehicle by the vehicle state calculating section is determined to be in the oversteer state, the reduction amount of the driving force or 0 smaller than the previous control cycle, the vehicle state calculating The amount of decrease in driving force is calculated from the deviation calculated by the unit and the spin rate calculated by the spin detection unit, and when the vehicle state calculation unit determines that the vehicle is not in an oversteer state, the calculation is performed. The driving force is controlled using the larger value of the respective driving force reduction amounts .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail based on the embodiments shown in the drawings.
FIG. 1 is a schematic block diagram showing an example of a vehicle behavior control device according to an embodiment of the present invention, and shows a behavior control device in a front-wheel drive vehicle.
[0009]
In FIG. 1, a vehicle behavior control device 1 includes a wheel speed sensor 2 that detects a wheel speed of each wheel, a steering angle sensor 3 that detects a steering angle of a steering, and a yaw rate sensor 4 that detects a yaw rate generated in the vehicle. Further, there are provided various sensors such as a throttle sensor 5 for detecting the throttle opening degree and a lateral acceleration sensor 6 for detecting the lateral acceleration of the vehicle.
[0010]
In addition, the vehicle behavior control device 1 calculates various data for determining the state of the vehicle from the input signals from the respective sensors and performs control to eliminate the oversteer state from the calculated data. A vehicle state calculation unit 7 that performs execution determination of understeer control, which is control performed to eliminate a certain oversteer control and understeer state, and the state of the drive wheel from the wheel speed of each wheel obtained from the wheel speed sensor 2, specifically Specifically, a drive wheel spin detection unit 8 that detects the spin state of the drive wheel is provided.
[0011]
Furthermore, the vehicle behavior control device 1 includes a braking force calculation unit 9 that calculates a control amount of the braking force for each wheel from various data and various determinations from the vehicle state calculation unit 7 and the drive wheel spin detection unit 8, and a vehicle A driving force calculation unit 10 that calculates a control amount of the driving force from each data and various determinations from the state calculation unit 7 and the driving wheel spin detection unit 8, and a control amount of the braking force calculated by the braking force calculation unit 9 A brake actuator 11 that performs wheel brake control and a throttle actuator 12 that controls the throttle from the control amount of the driving force calculated by the driving force calculation unit 10 are provided.
[0012]
The wheel speed sensor 2, the steering angle sensor 3, the yaw rate sensor 4, the throttle sensor 5, and the lateral acceleration sensor 6 are each connected to a vehicle state calculation unit 7, and the wheel speed sensor 2 is further connected to a driving wheel spin detection unit 8. ing. The vehicle state calculation unit 7 and the driving wheel spin detection unit 8 are connected to a braking force calculation unit 9 and a driving force calculation unit 10, respectively. The braking force calculation unit 9 is connected to the brake actuator 11, and the driving force calculation unit 10 is connected to the throttle actuator 12. It is connected to the.
[0013]
In such a configuration, the vehicle state calculation unit 7 calculates the vehicle body speed V from the wheel speed of each wheel obtained from the input signal from the wheel speed sensor 2, and the steering rudder from the input signal from the steering angle sensor 3. The angle δ, the actual yaw rate ωr that is the actual yaw rate of the vehicle from the input signal from the yaw rate sensor 4, the throttle opening from the input signal from the throttle sensor 5, and the lateral acceleration from the input signal from the lateral acceleration sensor 6. Get Gy respectively. The vehicle state calculation unit 7 calculates various data for determining the state of the vehicle from the values obtained from the input signals from these sensors, and controls the behavior of the vehicle from the calculated data. Whether to perform oversteer control and understeer control is determined.
[0014]
Further, the drive wheel spin detection unit 8 calculates the slip rate Sf of the front wheel, which is the drive wheel, from the wheel speed of each wheel obtained from the input signal from the wheel speed sensor 2, and controls the calculated spin rate Sf. It outputs to the power calculation part 9 and the driving force calculation part 10, respectively.
[0015]
Here, an execution determination method for vehicle behavior control including oversteer control and understeer control by the vehicle state calculation unit 7 will be described.
The vehicle state calculation unit 7 calculates the first target yaw rate ω1 from the following equation (1) using the vehicle body speed V and the steering angle δ among the values obtained from the sensors.
ω1 = V × δ / {(1-k × V ² ) × L} (1)
In the above equation (1), k is a stability factor, a constant determined from a field turning on a high μ (friction coefficient) road, and L is a constant indicating the wheel base.
[0016]
Next, the vehicle state calculation unit 7 calculates the second target yaw rate ω2 from the following equation (2) using the vehicle body speed V and the lateral acceleration Gy among the values obtained from the sensors.
ω2 = Gy / V ……………………………………… (2)
[0017]
Further, the vehicle state calculation unit 7 selects a value having a smaller absolute value from the first target yaw rate ω1 and the second target yaw rate ω2 and sets it as the target yaw rate ωt.
[0018]
Next, the vehicle state calculation unit 7 calculates a yaw rate deviation Δω that is a deviation between the target yaw rate ωt thus obtained and the actual yaw rate ωr obtained from the yaw rate sensor 4. The yaw rate deviation Δω is calculated from the following equation (3).
Δω = ωr−ωt …………………………………… (3)
[0019]
For example, if the polarity of the yaw rate sensor 4 is positive when it is counterclockwise and negative when it is clockwise, the vehicle state calculation unit 7 indicates that the calculated yaw rate deviation Δω is positive when the vehicle is making a left turn. When an oversteer threshold value Thos that is a value is exceeded, an oversteer control start determination is performed, and when the calculated yaw rate deviation Δω is less than a negative understeer threshold value Thus, an understeer control start determination is performed. When the vehicle is making a right turn, the vehicle state calculation unit 7 performs oversteer control start determination if the calculated yaw rate deviation Δω is less than the negative oversteer threshold value Thos, and calculates the calculated yaw rate. When the deviation Δω exceeds a positive understeer threshold value Thus, an understeer control start determination is performed.
[0020]
Next, a method of calculating the front wheel spin rate Sf by the drive wheel spin detection unit 8 will be described.
The drive wheel spin detection unit 8 calculates the spin rate SfR of the left front wheel from the following formula (4) from the wheel speed of each wheel obtained from the input signal from the wheel speed sensor 2, and the spin rate SfR of the right front wheel is 5) Each is calculated from the equation.
SfL = (VfL−VrL) / VrL ……………………… (4)
SfR = (VfR-VrR) / VrR (5)
In the above equation (4), VfL indicates the wheel speed of the left front wheel, and VrL indicates the wheel speed of the left rear wheel. In the above equation (5), VfR represents the wheel speed of the right front wheel, and VrR represents the wheel speed of the right rear wheel.
[0021]
Further, the drive wheel spin detection unit 8 calculates the average value of the calculated spin rate SfL of the left front wheel and the spin rate SfR of the right front wheel from the following equation (6), and sets it as the spin rate Sf of the front wheel.
Sf = (SfL + SfR) / 2 ………………………… (6)
The smaller one of the left front wheel spin rate SfL and the right front wheel spin rate SfR calculated by the above equations (4) and (5) may be used as the front wheel spin rate Sf.
[0022]
The braking force calculation unit 9 calculates the control amount of the braking force of each wheel from each data calculated by the vehicle state calculation unit 7 and the drive wheel spin detection unit 8 and each control execution determination, and controls the brake actuator 11. Do.
The driving force calculation unit 10 controls the throttle actuator 12 by calculating a control amount of the driving force from each data calculated by the vehicle state calculation unit 7 and the driving wheel spin detection unit 8 and the above control execution determination.
[0023]
In this way, the braking force calculation unit 9 and the driving force calculation unit 10 cause the brake actuator 11 and the throttle actuator 12 to perform predetermined oversteer control when the vehicle state calculation unit 7 determines oversteer control start, When the vehicle state calculation unit 7 performs the understeer control start determination, predetermined understeer control is performed. In the present embodiment, the value that is positive or negative depending on the turning direction of the vehicle will be described as an example in which the counterclockwise direction is positive and the clockwise direction is negative.
[0024]
As oversteer control, the braking force calculation unit 9 calculates a braking force braking amount to be applied to the outer front wheels in order to eliminate the oversteer state. The braking force control amount is calculated such that the larger the yaw rate deviation Δω is, that is, the larger the degree of oversteer is, and the smaller the yaw rate deviation Δω is, that is, the smaller the degree of oversteer is. At the same time, the driving force calculation unit 10 calculates the driving force control amount by a predetermined method so as to decrease the driving force.
[0025]
Further, as the understeer control, the braking force calculation unit 9 calculates a braking force braking amount to be applied to the inner rear wheel in order to cancel the understeer state. The braking force control amount is calculated such that the larger the yaw rate deviation Δω is, that is, the larger the degree of understeer is, and the smaller the yaw rate deviation Δω is, that is, the smaller the degree of understeer is. At the same time, the driving force calculation unit 10 calculates the driving force control amount by a predetermined method so as to decrease the driving force.
[0026]
Here, a method of calculating the amount of decrease in driving force by the driving force calculator 10 will be described.
In accordance with the yaw rate deviation Δω calculated from the equation (3) by the vehicle state calculation unit 7, the driving force calculation unit 10 specifically reduces the driving force as the yaw rate deviation Δω increases (7 ) To calculate the first driving force decrease amount ΔEa.
ΔEa = K1 × Δω + K2 × Δω '(7)
In the above equation (7), K1 and K2 are constants of K1, K2> 0, and Δω ′ is a derivative of the yaw rate deviation Δω.
[0027]
In addition, the driving force calculation unit 10 has a large front wheel spin rate Sf according to the spin rate Sf of the front wheel, which is the drive wheel, calculated by the drive wheel spin detection unit 8 from the above equation (6). The second driving force decrease amount ΔEt is calculated from the following equation (8) so as to decrease the driving force as much as possible.
ΔEt = K3 x Sf + K4 x Sf '(8)
In the above equation (8), K3 and K4 are constants of K3, K4> 0, and Sf ′ is a derivative of the spin rate Sf of the front wheel.
[0028]
Further, when the determination from the vehicle state calculation unit 7 is not an oversteer state, the driving force calculation unit 10 calculates the first driving force decrease amount ΔEa calculated by the equation (7) and the second driving force decrease calculated by the equation (8). Of the amount ΔEt, the larger value is selected as the driving force decrease amount ΔE. Further, when the determination from the vehicle state calculation unit 7 is an oversteer state, the driving force calculation unit 10 is, for example, the following (9) so as to be smaller than the driving force decrease amount ΔE _n−1 calculated in the previous control cycle. The driving force decrease amount ΔE _n of the current control cycle is calculated from the equation.
[0029]
ΔE _n = m × ΔE _n-1 (9)
In the above equation (9), _n in ΔE _n−1 and ΔE _n indicates the number of control cycles, and is a natural number where n> 0. Further, m is a real number for making the driving force decrease smaller than the previous control cycle, and 0 ≦ m <1. In particular, when m = 0, the driving force decrease amount in the current control cycle is set to 0 and the driving force control is prohibited.
[0030]
Next, FIG. 2 is a flowchart showing an example of the operation of the vehicle behavior control device 1 shown in FIG. 1, and FIG. 3 is a flowchart showing an example of a routine for calculating the driving force decrease amount ΔE. The operation of the vehicle behavior control device 1 will be described in a little more detail with reference to FIGS.
[0031]
In FIG. 2, in step S <b> 1, the vehicle state calculation unit 7 calculates the vehicle body speed V from the wheel speed of each wheel obtained from the input signal from the wheel speed sensor 2 and steers from the input signal from the steering angle sensor 3. The steering angle δ, the actual yaw rate ωr from the input signal from the yaw rate sensor 4, the throttle opening from the input signal from the throttle sensor 5, and the lateral acceleration Gy from the input signal from the lateral acceleration sensor 6 are obtained. Further, the drive wheel spin detection unit 8 calculates the spin rate Sf of the front wheel that is the drive wheel from the wheel speed of each wheel obtained from the input signal from the wheel speed sensor 2.
[0032]
Next, in step S2, the vehicle state calculation unit 7 calculates a target yaw rate ωt from the first target yaw rate ω1 calculated from the equation (1) and the second target yaw rate ω2 calculated from the equation (2). In step S3, the vehicle state calculation unit 7 calculates the yaw rate deviation Δω from the actual yaw rate ωr obtained in step S1 and the target yaw rate ωt calculated in step S2. Thereafter, in step S4, the vehicle state calculation unit 7 calculates and sets the oversteer threshold value Thos and the understeer threshold value Thus.
[0033]
In step S5, the vehicle state calculation unit 7 compares the yaw rate deviation Δω calculated in step S3 with the oversteer threshold value Thos set in step S4, and determines whether or not to start oversteer control. For example, assuming that the polarity of the yaw rate sensor 4 is positive when it is counterclockwise and negative when it is clockwise, the oversteer threshold value Thos is a positive value when turning counterclockwise, and the yaw rate deviation Δω is the oversteer threshold value. Check if Thos is exceeded. When the vehicle state calculation unit 7 determines that the yaw rate deviation Δω exceeds the oversteer threshold value Thos and starts oversteer control (YES), the process proceeds to step S6.
[0034]
In step S6, based on the oversteer control start determination of the vehicle state calculation unit 7, the braking force calculation unit 9 calculates the braking amount of the outer front wheel braking force, and the driving force calculation unit 10 calculates the control amount of the driving force. Next, in step S7, the braking force calculation unit 9 causes the brake actuator 11 to execute the braking force control of the calculated braking amount, and the driving force calculation unit 10 executes the driving control of the calculated drive amount to the throttle actuator. This flow is terminated.
[0035]
In step S5, for example, when the yaw rate deviation Δω is equal to or less than the oversteer threshold value Thos and the start of oversteer control is not determined (NO), the process proceeds to step S8. In step S8, the vehicle state calculation unit 7 compares the yaw rate deviation Δω calculated in step S3 with the understeer threshold value Thus set in step S4, and determines whether to start understeer control. For example, assuming that the polarity of the yaw rate sensor 4 is positive when it is counterclockwise and negative when it is clockwise, the understeer threshold value Thus is a negative value when turning counterclockwise, and the yaw rate deviation Δω is the understeer threshold value. It is checked whether or not it is less than Thos. If the yaw rate deviation Δω is less than the understeer threshold value Thus and it is determined to start understeer control (YES), the process proceeds to step S9.
[0036]
After the understeer control start determination of the vehicle state calculation unit 7 in step S9, the braking force calculation unit 9 calculates the braking amount of the inner rear wheel braking force, and the driving force calculation unit 10 calculates the control amount of the driving force. Then, the process of step S7 is performed, and the process returns to step S1. In step S8, for example, when the yaw rate deviation Δω is equal to or greater than the understeer threshold value Thus and the start of understeer control is not determined (NO), the process returns to step S1.
[0037]
Next, a method of calculating the driving force decrease amount ΔE performed by the driving force calculator 10 will be described with reference to FIG. In FIG. 3, unless otherwise specified, all processes performed in each flow are performed by the driving force calculation unit 10.
In FIG. 3, the first driving force decrease amount ΔEa is calculated from the yaw rate deviation Δω calculated by the vehicle state calculation unit 7 in step S11 using the equation (7). In step S12, the driving wheel spin detection unit 8 is calculated. The second driving force decrease amount ΔEt is calculated from the front wheel spin rate Sf calculated in step (5) using equation (8).
[0038]
Next, in step S13, it is checked whether or not the vehicle is in an oversteer state from the determination by the vehicle state calculation unit 7. If the vehicle is in an oversteer state (YES), in step S14, the above equation (9) is used. The driving force decrease amount ΔE _n of the current control cycle is calculated, and this flow ends.
[0039]
In step S13, if the vehicle is not in an oversteer state (NO), it is checked in step S15 whether the first driving force decrease amount ΔEa is larger than the second driving force decrease amount ΔEt. If ΔEa> ΔEt ( YES), in step S16, the first driving force decrease amount ΔEa is set to the driving force decrease amount ΔE _n of the current control cycle, and this flow is ended. Further, in step S15, if the ΔEa ≦ ΔEt (NO), at step S17, and the second driving force reduction amount .DELTA.ET the driving force reduction amount Delta] E _n of the current control cycle, the flow ends.
[0040]
As described above, the vehicle behavior control apparatus according to the present embodiment reduces the driving force reduction amount when the front-wheel drive vehicle is in the oversteer state, and calculates the yaw rate deviation Δω when the vehicle is not in the oversteer state. Of the second driving force reduction amount ΔEt calculated from the driving force reduction amount ΔEa and the spin rate Sf of the front wheel as the driving wheel, the larger value is selected as the driving force reduction amount ΔE. Therefore, the oversteer state can be avoided without disturbing the escape from the oversteer state by the driver's operation.
[0041]
【The invention's effect】
As is apparent from the above description, according to the vehicle behavior control apparatus of the present invention, when the front-wheel drive vehicle is in the oversteer state, the driving force reduction amount is made smaller than that in the previous control cycle or set to zero. I tried to do it. Therefore, the oversteer state can be avoided without disturbing the escape from the oversteer state by the operation of the driver, and unnecessary driving force control can be prevented.
[0042]
If it is determined that the vehicle is not in an oversteer state, the driving force is controlled using the larger value of the driving force decrease amount calculated from the yaw rate deviation and the driving force decrease amount calculated from the spin rate. did. From this, when the vehicle is neither oversteered nor understeered, it is possible to control the driving force using the driving force decrease amount calculated from the spin rate so that the wheel spin is not excessively increased. . When the vehicle is in an understeer state, excessive spin on the front wheels of the front-wheel drive vehicle tends to fall into an understeer state, and the driving force is controlled using a driving force decrease amount calculated from a yaw rate deviation that suppresses excessive wheel spin, The understeer state can be alleviated at an early stage, and appropriate driving force control can be performed even in an understeer state in which no wheel spin occurs.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing an example of a vehicle behavior control apparatus according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing an operation example of the vehicle behavior control apparatus in FIG. 1;
FIG. 3 is a flowchart showing a routine for calculating a driving force decrease amount ΔE.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vehicle behavior control apparatus 2 Wheel speed sensor 3 Steering angle sensor 4 Yaw rate sensor 5 Throttle sensor 6 Lateral acceleration sensor 7 Vehicle state calculation part 8 Drive wheel spin detection part 9 Braking force calculation part 10 Driving force calculation part 11 Brake actuator 12 Throttle Actuator

Claims (1)

The vehicle state is determined from the deviation between the target yaw rate calculated based on data obtained from various sensors and the vehicle yaw rate obtained from the yaw rate sensor, and predetermined braking force control and driving force control are performed according to the determination. In a behavior control device that controls the behavior of a front-wheel drive vehicle by performing
A vehicle state calculation unit that calculates the deviation and compares the calculated deviation with each threshold value for determining the state of the vehicle to determine oversteer and understeer of the vehicle;
A driving force control unit that controls the driving force in accordance with the determination by the vehicle state calculation unit;
A spin detection unit that detects spin in the drive wheel and calculates a spin rate of the drive wheel;
With
When the vehicle state calculation unit determines that the vehicle is in an oversteer state, the driving force control unit reduces the driving force decrease amount to 0 or less than the previous control cycle, and calculates the vehicle state calculation. The amount of decrease in driving force is calculated from the deviation calculated by the unit and the spin rate calculated by the spin detection unit, and when the vehicle state calculation unit determines that the vehicle is not in an oversteer state, the calculation is performed. A vehicle behavior control device characterized in that a driving force is controlled using a larger value of each driving force decrease amount .

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