JP2003276623A - Steering control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering control device for a vehicle capable of obtaining optimum steering characteristics in a high frequency steering area to drivers having different anticipation operation degrees. <P>SOLUTION: This steering control means for a vehicle is provided with a front-wheel steering means 4 capable of arbitrarily changing the transfer characteristic of a front-wheel steering angle over a steering angle, and a control means 14 outputting a control command for changing the transfer characteristic to the front-wheel steering means 4 based on prescribed input information. The control means 14 is provided with a proportional element changing by a first order lead element as the transfer characteristic of the front wheel steering angle to the steering angle detected by the steering angle detection means 2, and detects the anticipation operation degree Ky which indicates how much a driver is performing a steering operation in anticipation. The primary progress time constant Tf is changed according to the driver's anticipation operation degree Ky. When the anticipation operation degree Ky is small, the primary progress time constant Tf is set large, and when the anticipation operation degree Ky is large, the primary progress time constant Tf is set small. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a vehicle steering control device capable of arbitrarily changing a transmission characteristic of a front wheel steering angle with respect to a steering steering angle.

[0002]

2. Description of the Related Art Conventionally, as a vehicle steering control device for changing a steering characteristic according to a vehicle state, for example, Japanese Patent Application Laid-Open No. 9-83200 is available.
The one described in JP-A-58507 is known.

In this prior art publication, as shown in FIG.
The steering angle ratio changes with respect to the vehicle speed. The characteristic is that the steering angle ratio is high when the vehicle speed is low, and gradually decreases as the vehicle speed increases. This characteristic is that the steering angle ratio is such that the yaw rate is constant with respect to the vehicle speed in the high vehicle speed range T1, and the yaw rate is constant with respect to the vehicle speed in the low vehicle speed range T2 where the vehicle speed is lower than that. It has a lower steering angle ratio.

In the following description, instead of the steering angle ratio, the text uses the steering gear ratio (steering steering angle / front wheel steering angle), which is the reciprocal of the steering angle ratio. In other words, the characteristics of FIG.
The characteristic is that the steering gear ratio changes with respect to the vehicle speed, the steering gear ratio is low when the vehicle speed is low, and gradually increases as the vehicle speed increases.

[0005]

However, the above-mentioned prior art has the following problems because the steering gear ratio is changed only based on the vehicle speed.

(Problem 1) Steering frequency response of the vehicle (particularly, response delay) is the same as that of the conventional example, and operability and stability are achieved in an operating region of high frequency (for example, during sudden lane change or emergency avoidance operation). There is little effect of improving sex. In addition, the characteristics are the same for drivers having different operation styles (particularly, how much ahead is read and steering operation is performed predictively).

In a high frequency region, the vehicle has a phase delay, and even in this characteristic, it was necessary to predictively operate the steering wheel in order to travel along the intended line. For drivers who read ahead of a distant road and operate the steering predictively, it is possible to operate smoothly, but for drivers who operate by seeing near the road, for example, a vehicle is jerky due to a quick lane change. It may end up. Therefore, here, in order to improve the operability / stability of the latter even in a high steering frequency region and allow the vehicle to travel on the intended line, it is considered to reduce the phase delay of the vehicle or to advance the phase. Specifically, it is to add a first-order advance characteristic to the steering system. However, in the driver operation of predicting the steering operation by reading ahead of a distant road, when the phase is advanced, there is a risk that the vehicle will be cut too early until the vehicle becomes proficient.

As mentioned above, as an important factor in the difference in the operation pattern at the high steering frequency, how far ahead the driver is looking and how the vehicle behavior is predicted can be mentioned. In the following, the amount of this factor of the driver will be referred to as the predicted operation degree.

(Problem 2) The characteristics are the same for drivers having different driving abilities. Particularly, since it is considered that the most appropriate steering gear ratio is different in each traveling scene between a beginner who is not used to driving and an expert who has excellent driving ability, both of them cannot provide appropriate steering characteristics in the conventional example. The proper steering gear ratio for beginners to experts is
It is higher in the high vehicle speed range (that is, the vehicle speed is less responsive to the operation), and in the low vehicle speed range, it is the same as the skilled person in the vicinity of the steering neutral, but the lower characteristic is preferred in the large steering angle range. That is, in a high vehicle speed range, a minute and highly precise operation is required, and it takes some getting used to to learn it. In the low vehicle speed range, beginners are unfamiliar with large and fast operations, resulting in a time delay in operations.

The present invention has been made in view of the above problems, and provides a vehicle steering control device capable of obtaining optimum steering characteristics in a steering region of high frequency for drivers having different predicted operation degrees. The first purpose is to do so. A second object of the present invention is to provide a vehicle steering control device capable of obtaining optimum steering characteristics in a high vehicle speed range for drivers having different degrees of skill.

[0011]

In order to achieve the above-mentioned object, in the invention according to claim 1, a transfer characteristic changing means capable of arbitrarily changing a transfer characteristic of a front wheel steering angle with respect to a steering steering angle, and predetermined input information. Based on the above, in the vehicle steering control means including the transfer characteristic control means for outputting the control command for changing the transfer characteristic to the transfer characteristic varying means, how predictably the driver performs the steering operation. The predictive manipulating degree detecting means for detecting the predictive manipulating degree indicating, and the transfer characteristic control means includes a proportional element which changes as a transfer characteristic by a first order advancing element, and the time constant of the first order advancing element is used to predict the driver's predicting operation. Change depending on the degree,
When the predicted operation degree is small, the time constant of the primary advance element is increased, and when the predicted operation degree is large, the time constant of the primary advance element is decreased.

In order to achieve the second object, in the invention according to claim 6, the steering gear ratio, which is provided between the steering wheel and the front wheels, is a transmission ratio of the steering steering angle to the front wheel steering angle. For a vehicle provided with a steering gear ratio variable means that can be arbitrarily changed, and steering gear ratio control means that outputs a control command for changing the steering gear ratio to the steering gear ratio variable means based on predetermined input information. In the steering control device, a vehicle speed detecting means for detecting a vehicle speed and a driving skill determining means for judging the skill of the driver are provided, and the steering gear ratio control means has a skill level in a region where the vehicle speed is higher than a predetermined value. Is smaller, the control is performed such that the steering gear ratio at all steering angles is increased.

[0013]

In the invention according to claim 1, when the transfer characteristic control means changes the time constant of the primary advancement element according to the predicted operation degree of the driver during traveling, the predicted operation degree is small. Increases the time constant of the linear advance element,
When the predicted operation degree is large, control is performed to reduce the time constant of the first-order advance element.

That is, in a steering region with a high frequency (for example, during a sudden lane change or emergency avoidance operation), the driver who does not look ahead advances the phase of the vehicle to improve the responsiveness of the steering operation. Further, the driver who is pre-reading delays the advance of the phase of the vehicle to improve the stability of the steering operation.

Therefore, the optimum steering characteristics in the steering region where the frequency is high can be obtained for the drivers having different predicted degrees of operation.

According to the invention of claim 6, when traveling,
In the steering gear ratio control means, in a region where the vehicle speed is higher than a predetermined value, the smaller the skill level, the larger the steering gear ratio at all steering angles is controlled.

That is, in the high vehicle speed range, the steering gear ratio to be corrected is increased as a beginner is used, and the correction amount is decreased as an expert is used. That is, in a high vehicle speed range where a minute and highly precise operation is required, the lower the skill level, the smaller the turning angle of the front wheels with respect to the steering operation amount, and the stability of the steering operation is improved. Further, the higher the skill level, the larger the turning angle of the front wheels with respect to the steering operation amount, and the more responsive the steering operation is.

Therefore, for drivers of different skill levels,
Optimal steering characteristics can be obtained in the high vehicle speed range.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment for realizing a vehicle steering control device of the present invention will be described with reference to a first embodiment corresponding to the invention according to claims 1 to 4 and claims 6 to 6. The second embodiment corresponding to the invention according to No. 11 will be described.

(First Embodiment) First, the structure will be described. FIG. 1 is an overall system diagram showing a vehicle steering control device according to a first embodiment. In FIG. 1, 1 is a steering wheel, 2 is a steering angle detecting means, 3 is a first steering shaft, and 4 is a front wheel steering means. 5 is the second steering shaft, 6 is the steering gear mechanism, 7 and 8 are tie rods,
Knuckles 9 and 10, 11 right front wheel, 12 left front wheel, 1
3 is a vehicle speed detection means, and 14 is a control means.

When the steering wheel 1 is operated, its rotation is transmitted to the steering angle detecting means 2.

The steering angle detecting means 2 is a steering angle θ which is a rotation angle of the steering wheel 1 operated by a driver.
(= Steering steering angle) is detected and a steering angle signal is output to the control means 14.

The vehicle speed detecting means 13 detects the vehicle speed V and outputs a vehicle speed signal to the control means 14.

The control means 14 controls the steering angle θ and the vehicle speed V.
Is input, the target turning angle θ ′ is calculated by calculation processing using a predetermined control law, and a control command for obtaining the calculated target turning angle θ ′ is output to the front wheel turning means 4.

The front wheel steering means 4 is an actuator for converting the input control command into rotational movement. This rotational movement is transmitted to the second steering shaft 5 and is replaced by the stroke movement in the vehicle width direction in the steering gear mechanism 6. By this stroke motion, the left and right front wheels 1 are passed through the tie rods 7 and 8 and the knuckles 9 and 10.
1, 12 are steered.

Next, the operation will be described. [Steering Gear Ratio Control Processing] FIG. 2 is a flowchart showing a flow of processing executed by the control means 14, and each step will be described below.

In step S1, the initial fine steering time average value Dtsm, the initial fine steering time range Dtsd, and the sampling time Δ
t is initialized, and the fine steering flag sflag = 0,
Initialization processing is performed with the fine steering time t = 0. Here, when the fine steering flag sflag is 1, it indicates that the fine steering is being performed, and the fine steering time t is after the fine steering is started (the steering angle is equal to or more than the constant value θs1 which is the minute steering angle). It's time.

In step S2, the steering angle θ from the steering angle detecting means 2 and the vehicle speed V from the vehicle speed detecting means 13 are read. Subsequently, in step S3, the basic steering gear ratio G is obtained from the vehicle speed V and the characteristics shown in FIG.

In step S4, whether or not the fine steering is being performed is determined by the fine steering flag sflag, and the fine steering flag sflag is determined.
When = 1, the process proceeds to step S5, and the fine steering flag s
If flag = 0, the process proceeds to step S10.

In step S5, the fine steering time t is counted up.

In step S6, it is determined whether or not the fine steering time t is within a fixed time. If it is within the fixed time, the process proceeds to step S7, and if it is not within the fixed time, step S13.
Go to.

In step S7, it is judged whether or not the steering time θ is a constant value θs2 which is a minute steering angle, and the steering time θ =
If θs2, the process proceeds to step S8 and the steering time θ ≠ θ
If it is s2, the process proceeds to step S13.

In step S8, the fine steering time t is set to the initial fine steering time Dts.

In step S9, the fine steering flag sfla
g, reset the fine steering time t.

In step S10, it is determined whether or not the steering angle θ is θs1 in the direction of further turning, and if θ = θs1, the process proceeds to S11 to start fine steering. If θ ≠ θs1, the process proceeds to step S12. Then, the fine steering flag sflag and the fine steering time t are reset.

In step S13, the average value of the past initial fine steering time Dts is set as the initial fine steering time average value Dtsm.

In step S14, the initial fine steering time range Dtsd of the 90th percentile is subtracted from the past initial fine steering time Dts of the 10th percentile to calculate the initial fine steering time range Dtsd.

In step S15, the predicted operation degree Ky is calculated from the initial fine steering time average value Dtsm and the initial fine steering time range Dtsd.
Is calculated by the following equation: Ky = K × Dtsm / Dtsd (K is a proportional constant).

In step S16, the primary advance correction coefficient Kt is calculated based on the predicted operation degree Ky and the characteristic shown in FIG.

In step S17, the basic characteristic Tf 'of the primary advance time constant is obtained from the vehicle speed V and the characteristic shown in FIG.

In step S18, the primary advance correction coefficient K
The primary advance time constant Tf is obtained from t and the basic characteristic Tf 'of the primary advance time constant.

At step S19, the transmission characteristic (1) is calculated from the steering angle θ, the primary advance time constant Tf and the basic steering gear ratio G.
The target steered angle θ ′ is calculated by + Tf · S) / G.

In step S20, the front wheel steering means 4 is driven so that the front wheel steering angle becomes the target steering angle θ '.

In step S21, it is determined whether or not the ignition key is OFF. If the ignition key is ON, the process returns to step S2, the above control processing is repeated, and when the ignition key is OFF, the control processing ends. .

[Steering Gear Ratio Control Logic] Next, FIG. 3 shows the basic characteristic of the steering gear ratio corresponding to the reciprocal of the proportional gain when the target turning angle θ ′ is calculated. This basic gear ratio characteristic is changed by the vehicle speed V, as in the conventional example. Vehicle speed V
The steering gear ratio is fixed in the region where V is less than Vl and Vh is greater than Vh, and during that period, the steering gear ratio changes substantially in proportion to the vehicle speed V. The purpose of this characteristic is to achieve both good maneuverability at low vehicle speed and good operation stability at high vehicle speed.

Further, in the process of calculating the target turning angle θ'from the steering angle θ, in addition to multiplying the reciprocal 1 / G of the steering gear ratio, as shown in the block diagram of FIG. It has a first-order advance element (time constant Tf) for improving the property.
In the present embodiment, the first-order advance time constant Tf is changed according to the driver's predicted operation degree Ky for the reason described above. Further, the vehicle speed V is taken as a factor that changes the first-order advance time constant Tf in addition to the predicted operation degree Ky. This is because the range of the generally used front wheel steering angle varies depending on the vehicle speed V. That is, the front wheel steering angle range is wide at low vehicle speeds, while the front wheel steering angle range is narrow at high vehicle speeds.

FIG. 5 shows the primary time constant Tf for this vehicle speed V.
The basic characteristic Tf 'of is shown. The characteristic is that it decreases when the vehicle speed is Vl or higher. On the other hand, the range corrected by the predicted operation degree Ky is shown by the diagonal lines in FIG. The predicted operation degree Ky indicates that the larger the value, the larger the predicted amount for the driver's forward trajectory and vehicle behavior, that is, that the driver is driving ahead of the vehicle. A method of deriving the predictive operation degree Ky will be described later.

First, the primary advance correction coefficient Kt is calculated from the predicted operation degree Ky using the characteristics shown in FIG. In the region where the predicted operation degree Ky is small, the first-order advance correction coefficient Kt becomes maximum, and when the predicted operation degree Ky becomes large, the first-order advance correction coefficient Kt.
Decreases, and the first-order advance correction coefficient Kt becomes 0 at Kyh or higher. The primary advance time constant Tf is calculated by the following equation using the primary advance correction coefficient Kt. Tf = Tf '× Kt

Next, a method of calculating the predictive operation degree Ky will be described. Here, the degree to which the user is reading and operating is detected by the speed of the timing of the minute steering angle in the initial steering. This is because when the vehicle is steered while looking far ahead, the steering angle range is such that the vehicle hardly appears, but it is considered that a small amount of steering is being performed fairly early due to the visual attraction effect.

FIG. 7 shows a generation pattern of the steering angle θ with respect to time at the beginning of one corner. First, set the constant values θs1 and θs2, which are minute steering angles, and set the steering angle θ to θ
Times ts1 and ts2 at which s1 and θs2 are obtained are obtained. This ts1, t
The difference between s2, that is, the time required to operate the minute steering angle is defined as the initial minute steering time Dts.

It can be expected that the distribution of the initial fine steering time Dts during long-time traveling will be as shown in FIG. It is considered that the driver who has performed the expected operation firmly has a large value of the initial fine steering time Dts and has a small variation. Therefore, the area value of the initial fine steering time Dts within which the average value of the initial fine steering time Dts falls within a certain variation range Dtsm is Dtsd.
(From the 10th percentile to 9th in the flow chart of FIG.
Assuming that the value covers the 0th percentile), the predictive operation degree Ky is expressed as follows. In addition, K
Is a constant of proportionality. Prediction operation degree Ky = K × Dtsm / Dtsd

The flowchart shown in FIG. 2 is executed by the control means 14 with the control logic described above inserted.

Next, the effect will be described. (1) In calculating a target turning angle θ ′ input to the front wheel turning means 4 from the steering angle θ detected by the steering angle detecting means 2, a primary advance time constant of a transfer characteristic for improving the responsiveness of the vehicle. Since Tf is set to be large when the predicted operation degree Ky is small and is set small when the predicted operation degree Ky is large, it is optimal for a driver having a different predicted operation degree in a steering region where the frequency is high. Steering characteristics can be obtained.

(2) The primary advance time constant Tf is changed according to the vehicle speed V, and the primary advance time constant Tf is increased in the low vehicle speed range.
In the high vehicle speed range, the control for reducing the first-order advance time constant Tf is performed, so that the optimum steering characteristics corresponding to the vehicle speed can be obtained for the drivers having different predicted operation degrees.

(Second Embodiment) First, the structure will be described. FIG. 9 is an overall system diagram showing the vehicle steering control system of the second embodiment. In FIG. 9, 15 is a steering wheel, 16 is a first steering shaft, 17 is a second steering shaft, and 18 is a steering gear mechanism. 1
9, 20 are tie rods, 21, 22 are knuckles, 23 is a right front wheel, 24 is a left front wheel, 25 is a steering angle detecting means, 26
Is a traveling distance detecting means, 27 is a vehicle speed detecting means, 28 is a deceleration detecting means, 29 is a driving experience inputting means, 30 is a controlling means, and 31 is a steering gear ratio varying means.

By operating the steering wheel 15, the rotation thereof is transmitted to the first steering shaft 16 → the steering gear ratio varying means 31 → the second steering shaft 17. This rotational movement is replaced by stroke movement in the vehicle width direction in the steering gear mechanism 18, and the tie rods 19 and 20 and the knuckle 2 are moved.
The left and right front wheels 23, 24 are steered via 1, 22.

The steering angle detecting means 25 detects the steering angle θ which is the rotation angle of the steering wheel 15 operated by the driver and outputs a steering angle signal to the control means 30.

The traveling distance detecting means 26 detects the traveling distance L of the vehicle and outputs a traveling distance signal to the control means 30.

The vehicle speed detecting means 27 detects the vehicle speed V and outputs a vehicle speed signal to the control means 30.

The deceleration detecting means 28 detects the deceleration Vd of the vehicle when the brake is operated and outputs a deceleration signal to the control means 30.

In the driving experience input means 29, the driver inputs the driving experience years Y and outputs the driving experience years signal to the control means 3.
Output to 0.

The control means 30 inputs the steering angle θ, the traveling distance L, the vehicle speed V, the deceleration Vd, and the years Y of driving experience, and the steering gear ratio is calculated by a calculation process using a predetermined control law. The control command for obtaining G (steering steering angle / front wheel steering angle) and obtaining the obtained steering gear ratio G is the steering gear ratio varying means 3
It is output to 1.

The steering gear ratio varying means 31 is interposed between the first steering shaft 16 which rotates together with the steering wheel 15 and the second steering shaft 17 which serves as an input rotation for obtaining the front wheel steering angle, and the steering wheel 15 is provided. Is an actuator that changes the steering gear ratio G by changing the speed of rotation of the vehicle and transmitting it to the second steering shaft 17.

Next, the operation will be described. [Steering Gear Ratio Control Processing] FIG. 10 is a flowchart showing the flow of processing executed by the control means 30, and each step will be described below.

At step S31, the skill level J1 to be described later is set.
To J4, a brake operation flag bflag indicating that deceleration (during brake operation), a brake operation number i, and a steering operation flag s indicating that steering operation is in progress
Initialize the flag.

In step S32, the steering angle detecting means 2
The steering angle θ from 5 and the vehicle speed V from the vehicle speed detecting means 27
Then, the deceleration Vd from the deceleration detecting means 28 is read.

In step S33, the driving experience input means 2
The number Y of years of driving experience from 9 and the traveling distance L from the traveling distance detecting means 26 are read.

In step S34, whether or not the brake is being operated is determined by the brake operation flag bflag. If the brake operation flag bflag = 1, the process proceeds to step S35, and if bflag = 0, the process proceeds to step S40.

In step S35, it is determined whether or not the deceleration Vd is a certain value or more. If the deceleration Vd is a certain value, the process proceeds to step S36. If it is not the certain value, a step S4 is performed.
Go to 1.

In step S41, the skill level J1 is calculated from the variance of P1 to Pi and the characteristics shown in FIG.

In step S42, the brake operation flag bflag and the brake operation number i are reset.

In step S36, it is determined whether or not the differential value of the deceleration Vd is 0. If the differential value of the deceleration Vd is 0, the process proceeds to S37, and if it is not 0, the process proceeds to step S39 to perform the brake operation. And

In step S37, the number of brake operations i
To count up.

In step S38, the deceleration Vd is set to the deceleration peak value Pi.

In step S43, it is determined whether the steering operation is being performed by the steering operation flag sflag, and sflag is set.
If = 1, the process proceeds to step S44, and sflag =
If it is 0, the process proceeds to step S51.

In step S44, it is determined whether or not the steering angle θ is a certain value or more. If the steering angle θ is a certain value or more, the process proceeds to step S45, and if it is less than the certain value, step S45.
Go to 52 to reset sflag.

In step S45, it is judged whether or not the twice-differentiated value of the steering angle θ is 0, that is, the steering angular velocity θd is a peak value. If the twice-differentiated value of the steering angle θ is 0, the process proceeds to S46. If it is not 0, the process proceeds to step S53 and the steering operation is being performed.

In step S46, the steering angle θa = θ at the point a where the steering angular velocity is maximum is set.

In step S47, the differential value of the steering angle θa is θad, the steering angle at θa / 2 is θb, and the differential value of θb is θbd.

In step S48, the ratio Kad of the steering angular velocity, which is the degree of increase, is calculated from the differential value θad of the steering angle θa and the differential value θbd of the steering angle θb by the following equation: Kad = θad /
Calculated from θbd.

In step S49, the steering angular velocity ratio K
The skill level J2 is calculated from ab and the characteristics shown in FIG.

In step S50, the steering operation flag s
Reset the flag.

In step S54, the skill level J3 is calculated from the years Y of driving experience and the characteristics shown in FIG.

In step S55, the skill level J4 is calculated from the traveling distance L in a certain period and the characteristics shown in FIG.

In step S56, the average value of the skill levels J1 to J4 is calculated to obtain the skill level J.

In step S57, the basic steering gear ratio G0 'is calculated from the vehicle speed V and the characteristic shown in FIG.

In step S58, the steering gear ratio correction coefficient Kjv is calculated from the vehicle speed V and the characteristic shown in FIG.

In step S59, the skill level coefficient Kj is calculated from the skill level J and the characteristics shown in FIG.

In step S60, the basic steering gear ratio G
The steering gear ratio G0 is calculated from 0 ', the steering gear ratio correction coefficient Kjv, and the skill level coefficient Kj by the following equation, G0 = G0' + Kjv + Kj.

In step S61, the steering angle dependence correction coefficient Kθv is calculated from the vehicle speed V and the characteristic shown in FIG.

In step S62, the steering angle dependence gradient Kθ is calculated from the steering angle dependence correction coefficient Kθv and the skill level coefficient Kj by the following equation, Kθ = Kθv × Kj.

In step S63, the final steering gear ratio G is calculated from the steering gear ratio G0, the steering angle dependence gradient Kθ, and the characteristics shown in FIG.

In step S64, the steering gear ratio varying means 31 is driven so that the steering gear ratio becomes G.

In step S65, it is determined whether or not the ignition key is OFF. If the ignition key is ON, the process returns to step S32 and the above process is repeated.
Further, when the ignition key is turned off, the control process is ended.

[Steering Gear Ratio Control Logic] Next, the basic characteristics of the steering gear ratio are shown by the basic steering gear ratio G0 'in FIG. This basic gear ratio characteristic is changed by the vehicle speed V, as in the conventional example. In the region where the vehicle speed V is Vl or lower and Vh or higher, the steering gear ratio is fixed, and during that period, the steering gear ratio changes substantially in proportion to the vehicle speed V. The purpose of this characteristic is to achieve both good maneuverability at low vehicle speed and good operation stability at high vehicle speed.

In this embodiment, the skill level J of the driver is determined, and the skill level J is used to change the characteristics of the steering gear ratio G0 with respect to the vehicle speed V and the characteristics of the front wheel steering angle with respect to the steering angle θ. The characteristic of the steering gear ratio G0 with respect to the vehicle speed V is
When the skill J is high, the characteristic is the basic steering gear ratio G0 'in FIG. When the skill level J is low, as shown in FIG. 17, the characteristic is such that it becomes gradually higher than G0 'at a vehicle speed Vc or higher. A method of calculating the steering gear ratio G0 with respect to the vehicle speed V will be described below.

The steering gear ratio G0 is calculated by the following formula. G0 = G0 '+ Kjv + Kj where Kjv is a steering gear ratio correction coefficient determined by the vehicle speed V, and Kj is a skill level coefficient determined by the skill level J.

FIG. 13 shows the relationship between the vehicle speed V and the steering gear ratio correction coefficient Kjv. This is fixed at 0 up to a predetermined vehicle speed Vc and fixed at 1 above the vehicle speed Vh. This indicates the amount by which the skill level J is corrected by the vehicle speed V, the correction by the skill level J is not performed until the vehicle speed Vc, the vehicle speed Vc is gradually increased to the vehicle speed Vh, and the correction amount is performed at the vehicle speed Vh or higher. It will be the maximum.

FIG. 14 shows the relationship between the skill level J and the skill level coefficient Kj.
Shown in. The skill level coefficient Kj is the maximum when the skill level J is a constant value Jl, and it decreases temporarily from Jl to Jh.
The skill factor Kj is 0 when h or more. This is the skill level J
Is small, that is, in the case of a beginner, the steering gear ratio G0 to be corrected is increased, the correction amount is decreased as the skill level J increases, and the correction is not performed for the driver with the skill level Jh or higher. means.

Here, a method of calculating the skill level J will be described. In this embodiment, the skill levels J1 to J4 are determined by four methods.
Is calculated, and the average value is taken as J.

First, the first J1 is calculated from the fluctuation degree of the brake operation. It is considered that the degree of fluctuation in braking operation is a good indicator of the driver's driving skill. is there. The fluctuation degree of the brake operation is obtained from the variance of the peak value Pi at the vehicle deceleration Vd.

FIG. 18 shows the relationship between deceleration Vd and time. The peak value (P1 to P5) of the deceleration Vd appears each time the pedal is stepped up and the pedal is stepped back. If the amount is large, the variance of this value becomes large. FIG. 11 shows the relationship between the variance of the peak values Pi and the skill level J1. That is, when the variance is large, the driver's skill level J1 is considered to be low.

The second skill level J2 is calculated from the smoothness of the steering angle θ. FIG. 19 shows an example of the steering angle θ and the steering angular velocity θd with respect to the time during the steering operation. It is considered that if the operator is not familiar with the driving operation, the predictive steering cannot be performed and the additional operation is performed in the initial operation. Therefore, the point at which the steering angular velocity θd becomes maximum (θad in the figure) is a, and the steering angle (θb) that is half the steering angle θa at that point a is set.
= Θa / 2) is b and the steering angular velocity at point b is θbd, the degree of additional turning is θad / θbd
(= Kab). The larger the amount Kab, the larger the additional turning during steering. Kab and skill level J2 have the relationship shown in FIG. The larger the Kab, the lower the skill level J2.

The third skill level J3 is calculated from the years Y of driving experience according to the relationship shown in FIG. The driving experience years Y shall be declared by the driver through the driving experience input means 29.

The fourth skill level J4 is judged from the traveling distance L in a certain period. This relationship is shown in FIG. The smaller the travel distance L, the lower the skill level J4.

From the above J1 to J4, the driver's skill level J
Is calculated by the following formula: J = (J1 + J2 + J3 + J4) / 4.

Up to now, the steering gear ratio G with respect to the vehicle speed V
Although the correction of 0 has been described, a method of changing the characteristic (steering angle dependency) of the front wheel steering angle with respect to the steering angle θ will be described next.

First, this correction is performed only in the region where the vehicle speed V is low. FIG. 15 shows the relationship of the steering angle dependence correction coefficient Kθv, which is a coefficient indicating the degree of correction with respect to the vehicle speed V. It is the maximum in the low vehicle speed range up to the vehicle speed Vl, decreases temporarily from the vehicle speed Vl to the vehicle speed Vc, and becomes 0 at the vehicle speed Vc or higher.

FIG. 16 shows the relationship between the steering angle θ and the steering gear ratio G. When the steering angle θ is equal to or less than the constant value θl, the steering gear ratio G is G0 obtained by the above-described method, and the steering angle θ is equal to or greater than the constant value θl. Is a characteristic that decreases temporarily. here,
This gradient Kθ is changed according to the skill level J described above. The relational expression is the following expression. Kθ = Kθv ×
J Due to this relationship, for a driver whose vehicle speed V is low and skill J is low, the front wheel steering angle with respect to the steering angle θ has a quadratic curve characteristic.

The flow chart shown in FIG. 10 is executed by the control means 30 with the control logic described above inserted.

Next, the effect will be described. (1) In a region where the vehicle speed V is higher than a predetermined value, that is, in a high vehicle speed region, the smaller the skill level J, the larger the steering gear ratio G at all steering angles θ is controlled. On the other hand, optimum steering characteristics in the high vehicle speed range can be obtained.

(2) In the region where the vehicle speed V is lower than the predetermined value, that is, in the low vehicle speed region, the smaller the skill level J is, the larger the negative change gradient of the steering gear ratio G with respect to the steering angle θ is controlled. Optimal steering characteristics in the low vehicle speed range can be obtained for drivers of different skill levels.

(Other Embodiments) The vehicle steering control device of the present invention has been described above based on the first embodiment and the second embodiment, but the specific configuration is limited to these embodiments. It is not intended that modifications and additions of the design are allowed without departing from the gist of the invention according to each claim of the claims.

For example, in the first embodiment, the predictive operation degree Ky
Although the example in which is obtained from the change pattern of the steering angle θ in the initial stage of steering is shown, the predicted operation degree Ky can be obtained by directly detecting how far the driver is looking. Figure 2
2 shows the configuration. This embodiment corresponds to the invention according to claim 5.

That is, the line-of-sight direction detecting means 32 for detecting the line-of-sight direction of the driver is provided.
Then, the front lower angle θe in the figure is obtained. The value of θe becomes smaller as the distance is seen, and becomes larger as the distance is seen. FIG. 23 shows the relationship between θe and the predicted operation degree Ky.
The larger θe is, the smaller Ky is. The predicted operation degree Ky can be obtained from this characteristic.

[Brief description of drawings]

FIG. 1 is an overall system diagram showing a vehicle steering control system of a first embodiment.

FIG. 2 is a flowchart of control means.

FIG. 3 is a diagram showing a relationship between a vehicle speed V and a steering gear ratio G.

FIG. 4 is a diagram showing a transfer characteristic of a control means.

FIG. 5 is a diagram showing a relationship between a vehicle speed V and a primary advance time constant Tf.

FIG. 6 is a diagram showing a relationship between a predicted operation degree Ky and a first-order advance correction coefficient Kt.

FIG. 7 is a diagram showing a change pattern of a steering angle θ during steering.

FIG. 8 is a diagram showing a distribution of initial fine steering time Dts.

FIG. 9 is an overall system diagram showing a vehicle steering control device of a second embodiment.

FIG. 10 is a flowchart of control means.

FIG. 11 is a diagram showing the relationship between the variance of Pi and the skill level J1.

FIG. 12 is a diagram showing a relationship between years of driving experience Y and skill level J3.

FIG. 13 is a diagram showing a relationship between a vehicle speed V and a steering gear ratio correction coefficient Kjv.

FIG. 14 is a diagram showing a relationship between a skill level J and a skill level coefficient Kj.

FIG. 15 is a diagram showing a relationship between a vehicle speed V and a steering angle dependency correction coefficient Kθv.

FIG. 16 is a diagram showing a relationship between a steering angle θ and a steering gear ratio G.

FIG. 17 is a diagram showing a relationship between a vehicle speed V and a steering gear ratio G0.

FIG. 18 is a diagram showing a pattern of deceleration Vd.

FIG. 19 is a diagram showing a pattern of a steering angle θ and a steering angular velocity θd.

FIG. 20 is a view showing a relationship between a steering angular velocity ratio Kab and a skill level J2.

FIG. 21 is a diagram showing a relationship between a traveling distance L and a skill level J4.

FIG. 22 is an explanatory diagram showing a configuration of another embodiment.

FIG. 23 is a diagram showing a relationship between a front lower angle θe and a predicted operation degree Ky in another embodiment.

FIG. 24 is a steering angle ratio characteristic diagram corresponding to a conventional vehicle speed.

[Explanation of symbols]

1 steering wheel 2 Steering angle detection means 3 First steering shaft 4 Front wheel steering means 5 Second steering shaft 6 Steering gear mechanism 7,8 Tie rod 9,10 knuckles 11 right front wheel 12 left front wheel 13 Vehicle speed detection means 14 Control means

Claims (11)

[Claims] 1. A transfer characteristic changing means capable of arbitrarily changing a transfer characteristic of a front wheel rudder angle with respect to a steering rudder angle, and a control command for changing the transfer characteristic to the transfer characteristic changing means based on predetermined input information. A vehicle steering control means including: a transfer characteristic control means for detecting a predicted operation degree indicating a driver's predictive steering operation. The control means includes a proportional element that changes as a transfer characteristic by a primary advance element, changes the time constant of the primary advance element by the predicted operation degree of the driver, and when the predicted operation degree is small, sets the time constant of the primary advance element. A steering control device for a vehicle, wherein the steering control device for a vehicle is characterized in that when the predicted operation degree is large, the time constant of the primary advance element is decreased. 2. The vehicle steering control device according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed, wherein the transfer characteristic control means changes the time constant of the primary advance element according to the vehicle speed. Steering control device for a vehicle. 3. The vehicle steering control device according to claim 1, wherein the predicted manipulating degree detection means calculates the predicted manipulating degree from the speed of the steering start timing in the steering operation, and the timing is A vehicle steering control device characterized in that the predicted operation degree is increased as the speed is increased. 4. The vehicle steering control device according to claim 3, wherein the predictive manipulating degree detecting means sets a time period from a predetermined angle in a small steering range at which steering operation is started to a time when another predetermined steering angle is reached. A steering control device for a vehicle, which calculates a predicted operation degree from an average and a variation. 5. The vehicle steering control device according to claim 1, further comprising a line-of-sight direction detection unit that detects a line-of-sight direction of the driver, wherein the predictive operation degree detection unit detects the line-of-sight of the driver. A vehicle steering control device, characterized in that a predicted degree of operation is calculated according to how far the vehicle is looking forward. 6. A steering gear ratio varying means, which is provided between the steering wheel and the front wheels and which can arbitrarily change a steering gear ratio, which is a transmission ratio of the steering steering angle to the front wheel steering angle, and based on predetermined input information. A steering gear ratio control means for outputting a control command for changing the steering gear ratio to the steering gear ratio varying means, a vehicle speed detecting means for detecting a vehicle speed, and a driver's skill The steering gear ratio control means performs control to increase the steering gear ratio at all steering angles as the skill level decreases in a region where the vehicle speed is higher than a predetermined value. A steering control device for a vehicle, comprising: 7. The vehicle steering control device according to claim 6, wherein the steering gear ratio control means has a negative change in the steering gear ratio with respect to the steering angle as the skill level decreases in a region where the vehicle speed is lower than a predetermined value. A vehicle steering control device characterized by performing control for increasing a gradient. 8. The vehicle steering control device according to claim 6 or 7, further comprising deceleration detecting means for detecting deceleration, wherein the driving skill determining means reduces the driver's skill during deceleration. A steering control device for a vehicle, which is calculated from the fluctuation of the deceleration of the vehicle. 9. The vehicle steering control device according to claim 6, wherein the driving skill level determination unit calculates the driver's skill level from the amount of additional steering angle during steering operation. A steering control device for a vehicle, comprising: 10. The vehicle steering control device according to claim 6, further comprising mileage detection means for detecting a mileage, wherein the driving skill level determination means determines a driver's skill level for a certain period of time. A steering control device for a vehicle, which is calculated from the traveling distance in the vehicle. 11. The vehicle steering control device according to claim 6, further comprising a driving experience input means for inputting a driving experience of a driver, wherein the driving skill determination means is a driver's skill level. A steering control device for a vehicle, wherein: is calculated from the number of years of driving experience input by the driver.