JP2002347645A - Vehicle steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle steering device capable of automatically set the optimum steering angle ratio adjusted for a driver's intention even for the driver having any driving experience and any vehicle speed. SOLUTION: A control means 1 is provided with a steering angle map 6 memorizing a characteristic of a steering angle ratio, i.e., a transmission ratio from a steering angle θ to a steering angle of a front wheel against a vehicle speed; a steering angle expectation means 5 for expecting an ideal steering angle by the driver based on a front side road shape detected by a front side road shape detection means 2; and a steering angle ratio map correction means 4 for calculating an index value representing an excess and a lack of an actual steering angle based on a difference θe of the expected steering angle and the actual steering angle and correcting the steering angle ratio map 6 based on the index value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a vehicle which changes a ratio of a steering angle of a steered wheel (front wheel) to a steering angle of a steering wheel, that is, a steering angle ratio according to a running state of the vehicle.

[0002]

2. Description of the Related Art Conventionally, as a technique for achieving both low-speed steering operability and high-speed steering stability, steering with a variable steering angle ratio (front wheel steering angle / steering steering angle) according to vehicle speed is known. Devices are known.

For example, according to the technology described in Japanese Patent Application Laid-Open No. 9-58507, a mechanism is provided for changing the steering angle ratio by an electric command, and the steering angle ratio changes with respect to the vehicle speed. Has a characteristic that the steering angle ratio is large, and at high speed (T1), the steering angle ratio gradually decreases as the vehicle speed increases (FIG. 12). According to this technique, the steering angle amount can be reduced at a low vehicle speed with respect to a normal vehicle, so that the operability of the maneuvering operation can be improved and the steering stability at a high speed can be obtained.

[0004]

However, since it is considered that the steering angle ratio which is optimal for the driver varies from individual to individual, the steering angle ratio map in which the conventional steering angle ratio with respect to the vehicle speed is fixed is given by: There is a problem that many drivers feel a sense of discomfort in the steering angle ratio.

[0005] In particular, there is a problem with the steering angle ratio at a low and middle vehicle speed, which is greatly different from that of a normal vehicle. The factor of this individual difference is that the expected value of the driver's expectation of turning by this much is formed by his / her driving experience, and therefore differs from individual to individual. For example, if you steer with the intention of a normal vehicle at low vehicle speed,
It is possible that over-cutting may occur. In this case, the driver notices the difference in the middle of the curve, and performs the corrective steering. Therefore, there is a problem that the burden on the driver is increased.

In view of the above problems, it is an object of the present invention to automatically set an optimum steering angle ratio suitable for a driver's intention at any vehicle speed, even for a driver having any driving experience. It is an object of the present invention to provide a vehicular steering device that can be used.

[0007]

According to a first aspect of the present invention, a steering angle ratio characteristic, which is a transmission ratio from a steering angle to a front wheel steering angle, is determined according to a steering angle ratio map with respect to a vehicle speed. A vehicle steering device that can be arbitrarily set; a front road shape detecting unit that detects a front road shape during traveling; a steering angle prediction unit that predicts an ideal driver's steering angle based on the front road shape; A steering angle ratio map that calculates an index value indicating excess or deficiency of the actual steering angle based on a difference θe between the predicted steering angle and the actual steering angle, and corrects the steering angle ratio map based on the index value. And a correcting means.

According to a second aspect of the present invention, there is provided a vehicle steering system as set forth in the first aspect, wherein a steering angle ratio is set when an actual steering angle is too far from the predicted steering angle. Is small, and in the case of insufficient turning, it is necessary to make a correction so as to increase the steering angle ratio.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, in the vehicle steering system according to the first or second aspect, the index value is the θ in one curve.
The gist is that the difference is the difference between the maximum peak value and the minimum peak value of the differential value of e.

According to a fourth aspect of the present invention, there is provided a vehicle steering system as set forth in the first or second aspect, wherein the correction of the steering angle ratio map is performed by correcting a value of the steering angle ratio with respect to a running vehicle speed. In addition to rewriting by adding a correction amount to the vehicle speed, the gist is to correct the value of the steering angle ratio at a vehicle speed near the traveling vehicle speed by a value obtained by multiplying the correction amount by a weight.

According to a fifth aspect of the present invention, in the vehicle steering system according to the first or second aspect, the steering angle estimating means performs a proportional operation, a differential operation, and a time delay operation. The gist of the invention is to have the ideal steering control characteristic of the driver.

According to a sixth aspect of the present invention, in order to solve the above problem, in the vehicle steering system according to the first or second aspect, the front road shape detecting means is a camera for photographing a road image ahead of the vehicle. The steering angle prediction means calculates the center between white lines, that is, the center of the traveling lane, from the road image captured by the camera, and calculates the center of the traveling lane a predetermined distance ahead from the lateral distance difference between the traveling lane center position and the position when traveling straight. The gist is to predict an ideal driver steering angle.

According to a seventh aspect of the present invention, there is provided a vehicle steering system according to the first or second aspect, wherein the front road shape detecting means is a navigation device.

[0014]

According to the first aspect of the invention, the characteristics of the steering angle ratio, which is the transmission ratio from the steering angle to the front wheel steering angle, can be arbitrarily set according to the steering angle ratio map with respect to the vehicle speed. In the device, a front road shape detecting means for detecting a front road shape during traveling, a steering angle prediction means for predicting a steering angle by an ideal driver based on the front road shape, and a predicted steering angle and an actual steering angle. Difference θ from steering angle
e) calculating an index value indicating an excess or deficiency of the actual steering angle based on the calculated steering angle, and correcting the steering angle ratio map based on the index value. It is now possible to correct the steering angle ratio map based on whether the steering angle of the driver with respect to the steering angle is excessive or insufficient, and it is possible to automatically set the optimum steering angle ratio that suits the driver's intention at any vehicle speed. effective.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, when the actual steering angle is too far from the predicted steering angle, the steering angle ratio is reduced, In the case of insufficient turning, the steering angle ratio was corrected so as to increase, so that the driver's steering angle was excessively turned,
There is an effect that the steering angle ratio can be corrected so as to cancel the insufficient turning.

According to the third aspect of the present invention, in addition to the effect of the first or second aspect, the index value is a maximum peak value and a minimum peak value of the differential value of θe in one curve. Since the difference from the peak value is determined, there is an effect that an index value indicating an excess or deficiency of the actual steering angle can be calculated by a relatively easy calculation.

According to the fourth aspect of the invention, in addition to the effect of the first or second aspect, the correction of the steering angle ratio map is performed by correcting the steering angle ratio with respect to the vehicle speed during traveling. Is added and rewritten, and the value of the steering angle ratio at a vehicle speed near the traveling vehicle speed is also corrected by a value obtained by multiplying the correction amount by weight, so that the steering angle ratio with respect to the vehicle speed is corrected to be smooth. Thus, there is an effect that even when the vehicle speed changes, a change in the steering angle ratio does not cause discomfort.

According to the fifth aspect of the present invention, in addition to the effects of the first or second aspect, the steering angle predicting means performs the proportional operation, the differential operation, and the time delay operation by the ideal operation. The present invention has an effect that the predicted steering angle based on the ideal driver steering control characteristic can be accurately calculated with a relatively simple control model.

According to a sixth aspect of the present invention, in addition to the effect of the first or second aspect, the front road shape detecting means is a camera for photographing a road image ahead of the vehicle. The steering angle prediction means calculates the center between white lines, that is, the center of the traveling lane, from the road image captured by the camera, and calculates the ideal distance from the lateral distance difference between the center position of the traveling lane ahead of a predetermined distance and the position when the vehicle is straight ahead. Since the steering angle of the driver is predicted, there is an effect that the ideal steering angle of the driver can be reliably predicted.

According to the seventh aspect of the present invention, in addition to the effects of the first or second aspect of the present invention, since the front road shape detecting means is a navigation device, its popularity has increased in recent years. In a vehicle equipped with a navigation device, the shape of the front road can be easily obtained without using a new front road shape detecting means and without performing complicated image processing, and can be used for prediction of a steering angle. This has the effect.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a system configuration diagram showing a configuration of an embodiment of a vehicle steering system according to the present invention, and includes a main part of a vehicle to which the present invention is applied.

In FIG. 1, a steering wheel 10 steered by a driver is provided in front of a driver's seat 19. A steering shaft 13 is fixed to the steering wheel 10, and the steering shaft 13 is rotatably attached to the vehicle body. A steering angle detecting means 11 is provided at an end of the steering shaft 13 on the steering wheel 10 side. Further, the steering shaft 13 is provided with a steering force adjusting means 12 for applying a variable resistance force to the turning power of the steering shaft in accordance with an instruction from the control means 1 substantially below the center. At the lower end of the steering shaft 13,
A steering angle ratio varying means 14 is provided, and a steering gear box 16 is provided below the steering angle ratio varying means 14 via a joint 15. From the steering gear box 16, tie rods 17 extend in the left and right directions, respectively.
A front wheel 19, which is a steering wheel, is connected to the front wheel 8 via the steering wheel 8. The direction of the front wheel 19 can be changed by operating the steering wheel 10.

The steering angle detecting means 11 detects the steering angle of the steering wheel 10 operated by the driver (hereinafter referred to as steering angle θ), and inputs the steering angle θ to the control means 1. Further, a front road shape detecting means 2 for detecting a front road shape during traveling and a vehicle speed detecting means 3 such as a speedometer for detecting a running speed of the vehicle are provided, and output the front road shape and the vehicle speed to the control means 1 respectively. are doing.

The control means 1 includes a steering angle ratio map 6 storing the characteristics of the steering angle ratio, which is a transmission ratio from the steering angle θ to the front wheel steering angle, with respect to the vehicle speed. Steering angle predicting means 5 for predicting an ideal driver's steering angle based on the shape of the road ahead, and indicating the excess or deficiency of the actual steering angle based on the difference θe between the predicted steering angle and the actual steering angle. A steering angle ratio map correcting means 4 for calculating an index value and correcting the steering angle ratio map 6 based on the index value is provided (claim 1).

The control means 1 can calculate the position of the center of the road a certain distance ahead by processing the image taken by the road shape detecting means 2 ahead. The front road shape detecting means 2 is, for example, a CCD camera mounted in a vehicle compartment facing forward.

The characteristics of the steering angle ratio stored in the steering angle ratio map 6 change according to the vehicle speed V.
(V) is expressed as a function of the vehicle speed V.

As shown in FIG. 2, the basic characteristic of the steering angle ratio is a characteristic that is constant at a high value below a constant vehicle speed VL and gradually decreases according to the vehicle speed at a vehicle speed higher than VL. The control means 1 has a steering angle ratio map 6 in which the value of the steering angle ratio G (Vn) for each vehicle speed range Vn is stored in advance, and searches the steering angle ratio map 6 from the vehicle speed detected by the vehicle speed detection means 3. Thus, the steering angle ratio of the steering angle ratio varying means 14 is controlled.

In this embodiment, a map 6 of the steering angle ratio G (Vn) with respect to each vehicle speed range Vn is obtained based on the signal of the road shape detecting means 2 so that the steering angle ratio is optimal for the driver.
Is rewritten momentarily based on the driver model described below.

First, processing of an image captured by the front road shape detecting means (CCD camera) 2 will be described with reference to FIG. FIG. 3 shows an image of image data obtained by binarizing the image captured by the road shape detecting means 2 in black and white. However, in order to make the drawing easier to see, black and white are inverted and displayed in FIG.

By binarizing the captured image in black and white, the outline of the white line is raised, and the position of the center of the left and right white line of the automatic driving lane ahead of a certain distance is obtained (FIG. 3).
The position of the large white circle inside). Let e be the distance of that position from the image center in the horizontal direction. This value indicates a deviation from the course at a fixed forward fixation point distance. The control means 1 obtains a steering angle (hereinafter referred to as a predicted steering angle θref) on the basis of the value e based on the assumption that ideal steering is performed by the following driver model (claim 6).

Predicted steering angle θ for deviation e from the course
ref is obtained by equation (1). Here, h (t) is the time t
Is the transfer function of the driver model at.

[0032]

Θref = h (t) · e / G (Vn) (1) Here, assuming that the Laplace transform of h (t) is H (s), H (s) is represented by the following equation (2) ).

[0033]

H (s) = h1 (1 + T1S) e- ^T2S (2) where h1 is a proportional coefficient of the driver model, T1 is a differential coefficient, and T2 is a time delay coefficient. That is, the driver model is proportional to the deviation e from the course,
This is based on the assumption that an operation with a primary advance and a time delay is performed (claim 5).

FIG. 4 shows the relationship between the ideal steering angle θref of the driver and the actual driver's steering pattern according to the shape of the road ahead as obtained above. When the steering angle ratio is correct for the driver, the driver's steering angle θ matches θref.However, when the steering angle ratio is too high, the operation becomes too sharp at the beginning of steering, and to correct it, as shown in the figure Perform a switchback operation during a corner.

On the other hand, if the steering angle ratio is too low, the steering is insufficiently turned in the early stage of the steering. Assuming that the difference between the predicted steering angle θref and the driver's steering angle θ is the steering angle error θe (= θref−θ), θe in the case of over-cutting or under-cutting has a pattern as shown in FIG. When the turning is insufficient, θe gradually increases, and the error suddenly decreases due to the correction steering that increases the turning.
In the case of excessive turning, θe gradually increases to one side, and an error decreases in the corrected steering to be recovered. Overcut,
The feature of the driver's steering in the case of insufficient turning is that correction steering is suddenly performed in the latter half. (If the driver simply cuts off the optimal line without being aware of excessive cutting and insufficient cutting, the error gradually decreases in the latter half. Operation can be expected).

That is, it is considered that the gradient (differential value) of θe in the correction steering in the latter half is appropriate as an index value (parameter) for judging the amount of overcut or undercut. Assuming that the differential value of θe is a steering angular velocity error △ θe, 。θe has a pattern shown in FIG. If the maximum value (positive peak value) of Δθe is P1, and the minimum value is P2 (minus peak value), the absolute value of P2 becomes extremely larger than the absolute value of P1 as a feature of the turning-up operation. , P1 and P2 (hereinafter Pe ′ (= P1 + P
2)) is a large negative value. In the case of excessive cutting, the pattern shown in FIG. Since the absolute value of P1 becomes extremely large with respect to the absolute value of P2 as a feature of the switchback operation, the value Pe ′ obtained by adding P1 and P2 is a large plus value.

In this embodiment, the amount of undercut or overcut is determined based on the value of Pe 'which is the difference between the maximum value P1 and the minimum value P2 in one curve of the differential value of θe. The steering angle ratio is corrected so as to reduce the steering angle ratio when the steering wheel is excessively turned, and to increase the steering angle ratio when the steering wheel is insufficiently turned (claim 3).

Here, Pe 'is a value at one corner, but in order to further improve the accuracy of discrimination, the average of Pe' values at the current to a plurality of previous (N) corners is defined as Pe. The steering angle ratio correction amount (hereinafter referred to as ΔG; steering angle ratio G (Vn) at vehicle speed Vn = original G (Vn) + ΔG) is calculated according to the value.

FIG. 7 shows the relationship between Pe and ΔG. When Pe is large (that is, excessive turning), the steering angle ratio is reduced by setting △ G to minus. When Pe is large on the minus side (that is, insufficient turning), the steering angle ratio is increased with △ G as a plus value. By performing this correction, it is possible to improve over-turning or under-turning due to excessive or insufficient steering angle ratio.

When the steering angle ratio is corrected by the above-described logic, the range of the steering angle ratio to be corrected here is within the range indicated by the hatched portion in FIG. It has an upper limit (Gmax (Vn)) and a lower limit (Gmin (Vn)) that differ depending on the vehicle speed (Vn).
Further, the correction of the steering angle ratio is to rewrite the steering angle ratio G (Vn) at the vehicle speed (Vn) in the steering angle ratio map, but if only G (Vn) is changed, the peripheral vehicle speed is changed. Map (G (Vn-2), G (Vn-1), G (Vn
+1), G (Vn + 2)).
Therefore, as shown in FIG. 9, when the correction is performed by rewriting the contents of the steering angle ratio map, the correction amount is ΔG at the vehicle speed Vn, but the values in the front and rear vehicle speed regions are also coefficients (the K1 and K2 next to each other) Next, K2, for example, K1 = 0.5, K2 = 0.2) is applied and correction is performed (claim 4).

The processing contents of the control means having the above-described logic will be described in detail with reference to the flowcharts of FIGS. First, the outline of the processing contents will be described. First, the work memory and the flag are initialized. This flag is a flag indicating whether or not the vehicle is traveling on a curve.
In the case of 1, it is a curve. Next, the current steering angle ratio G (Vn)
Drives the variable steering angle ratio means. Next, the lateral displacement amount e is calculated from the image of the CCD camera, and if the lateral displacement amount e is equal to or more than a predetermined value, it is considered that the vehicle is traveling on a curve, and the maximum peak value P1 and the minimum peak value P2 of the steering angular velocity error are calculated. Next, Pe ′ = P1 + P2 is calculated, the steering angle ratio correction value ΔG is determined with the average value of Pe ′ for a plurality of curves as Pe, and the steering angle ratio map is rewritten.

In the detailed flowchart of FIG. 10, first, in step S10, the steering angle ratio G to the vehicle speed is set.
(), The work area used for the maximum value Gmax () and the minimum value Gmin () is initialized, and in step S12, the work flag is initialized. This flag is a flag indicating whether or not the vehicle is traveling on a curve.
Is a curve, and 0 indicates that the vehicle is traveling on a straight road or a substantially straight road. Then, step S1
In step S4, the current vehicle speed Vn is read, and in step S16, the value G (Vn) of the steering angle ratio map is read from the vehicle speed Vn. Then, in step S18, the steering angle ratio varying means is driven so that the steering angle ratio becomes G (Vn).

Next, in step S20, an image of the road ahead is captured by the CCD camera. Step S22
Then, as shown in FIG. 3, a horizontal distance (lateral displacement amount) e from the center of the image to the center of both white lines indicating the left and right boundaries of the own vehicle traveling lane is calculated from this image. Then, in a step S24, it is determined whether or not the distance e is equal to or more than a predetermined value.

If the distance e is equal to or greater than the predetermined value, it is considered that the vehicle is traveling on a curve, and the flag is set to 1 in step S26. Next, at step S28, the steering angle θ is read by the steering angle detecting means.

Next, in step S30, the ideal driver model is obtained from the steering angle ratio G (Vn) and the distance e at the current speed and the ideal driver model shown in the above equations (1) and (2). Predicted steering angle θ
Calculate ref. Then, in step S32, a steering angular velocity error △ θe, which is a difference between the time differential values of the steering angle θ and the predicted steering angle θref, is obtained. Next, step S34
Then, after this △ θe enters the curve, ie, flag
Is determined to be the maximum value after the value has changed to 1.

If △ θe is the maximum value in the judgment of step S34, the flow branches to step S36 to store △ θe in P1, and if it is not the maximum value in the judgment of step S34, P1 is not updated.

Next, in step S38, this △
It is determined whether or not θe is the minimum value after the flag changes to 1. If it is determined in step S38 that Ｓθe is the minimum value, the flow branches to step S40 to store △ θe in P2. If △ θe is not the minimum value in step S38, P2 is not updated.

Next, at step S42, the key OF
It is determined whether or not the key is F. If the key is OFF, the process ends. If the key is not OFF, the process returns to step S14 to continue the process.

If the determination in step S24 is No, that is, the distance e
Is smaller than the predetermined value, the process moves to step S44 in FIG. 11, and it is determined whether or not flag of the previous sample is 1. If the previous sample is flag = 1, in order to perform the process of ending the curve running in step S46,
g is reset, and the routine goes to step S50. If the previous sample is not flag = 1, in step S48 flag
Assuming that g = 0, the flow branches to step S42 in FIG.

In step S50, the difference (peak-to-pae) between the maximum peak and the minimum peak of the steering angular velocity error is determined.
k value) is calculated by Pe ′ = P1 + P2. Next, at step S52, N Pe's up to the present time are set.
Is calculated. Next, in step S54, a steering angle ratio correction value △ G is obtained using a table or a calculation formula of Pe and the steering angle ratio correction value △ G as shown in FIG.

Next, in step S56, a value G (Vn) + ΔG obtained by adding the correction value ΔG to the value of the steering angle ratio G (Vn) of the current vehicle speed Vn in the steering angle ratio map is calculated. The steering angle ratio map is rewritten with the steering angle ratio of. Next, in order to limit the corrected steering angle ratio G (Vn) with the maximum value Gmax (Vn) and the minimum value Gmin (Vn), first in step S58, is G (Vn) exceeding the maximum value Gmax (Vn)? Determine whether or not. G (Vn) is the maximum value Gma
If it exceeds x (Vn), G (V
n) is rewritten with the maximum value Gmax (Vn), and step S
Move to 66.

In step S58, G (Vn) is the maximum value Gma
If it does not exceed x (Vn), G is determined in step S62.
It is determined whether (Vn) is smaller than the minimum value Gmin (Vn). G (Vn) is the minimum value G in the determination of step S62.
If smaller than min (Vn), G (V
n) is rewritten with the minimum value Gmin (Vn), and step S
Move to 66. In step S66, the steering angle ratio G (Vn−V) at the vehicle speed around the vehicle speed Vn to be corrected.
2), G (Vn-1), G (Vn + 1), G (Vn +
2) Also, as shown in FIG. 9, rewriting is performed in consideration of the weighting factors K2, K1, K1, and K2, respectively. Next, the state of the key switch is determined in step S42, and if the key switch is not OFF, the process proceeds to step S14 to continue the processing.

As described above, according to the present invention, the steering angle ratio is small when the actual steering angle is too large with respect to the steering angle predicted from the ideal steering characteristics of the driver. Since the angle ratio is corrected so as to be large, the steering angle ratio can be corrected so as to cancel the driver's excessive steering angle and insufficient steering angle, and the steering angle ratio suitable for the driver's steering characteristics and steering image Automatically adjusted.

In this embodiment, the lateral displacement e of the road ahead at a certain distance is obtained from the image of the CCD camera, which is a CCD camera. However, in a vehicle equipped with a navigation device, a simpler method is as follows. The lateral displacement amount e of the road ahead at a certain distance can also be obtained from the shape of the road ahead and the direction of the vehicle recognized by the navigation device. In this case, the shape of the front road can be easily obtained and used for predicting the steering angle without newly providing a front road shape detecting means and without performing complicated image processing.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram illustrating a configuration of an embodiment of a vehicle steering system according to the present invention.

FIG. 2 is a graph showing a relationship between a vehicle speed V and a steering angle ratio G (V).

FIG. 3 is a diagram showing an example of an image of a CCD camera.

FIG. 4 is a diagram showing patterns of a predicted steering angle θref and an actual steering angle θ.

FIG. 5 is a diagram showing a time change pattern of a steering angle error θe.

6A is a diagram showing a pattern of a steering angular velocity error △ θe when the steering is insufficiently cut, and FIG. 6B is a diagram showing a steering angular velocity error when the steering is excessively cut.
It is a figure showing the pattern of (theta) e.

FIG. 7 is a graph showing a relationship between Pe and a steering angle ratio correction amount ΔG.

FIG. 8 is a graph showing a relationship between a vehicle speed and an upper limit value and a lower limit value of a steering angle ratio.

FIG. 9 is a graph showing the details of steering angle ratio correction near the vehicle speed Vn.

FIG. 10 is a flowchart illustrating processing performed by a control device.

FIG. 11 is a flowchart illustrating processing performed by a control device.

FIG. 12 is a graph showing an example of a steering angle ratio control characteristic of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control means 2 forward road shape prediction means 3 vehicle speed detection means 4 steering angle ratio map correction means 5 steering angle prediction means 6 steering angle ratio map 10 steering wheel 11 steering angle detection means 12 steering force adjustment means 13 steering shaft 14 steering angle ratio Variable means 15 Joint 16 Steering gear box 17 Tie rod 18 Knuckle arm 19 Front wheel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01C 21/00 G01C 21/00 A // B62D 101: 00 B62D 101: 00 113: 00 113: 00 137: 00 137: 00 F term (reference) 2F029 AA02 AB13 3D032 CC08 DA03 DA23 DA84 DA87 DC01 DC03 DC08 EC31 EC35

Claims (7)

[Claims] 1. A vehicle steering system in which a characteristic of a steering angle ratio, which is a transmission ratio from a steering steering angle to a front wheel steering angle, can be arbitrarily set according to a steering angle ratio map with respect to a vehicle speed. Forward road shape detecting means for detecting, steering angle predicting means for predicting an ideal driver's steering angle based on the forward road shape, and an actual steering angle based on a difference θe between the predicted steering angle and the actual steering angle. A steering angle ratio correction means for calculating an index value indicating excess or deficiency of the steering angle and correcting the steering angle ratio map based on the index value. 2. The method according to claim 1, wherein the steering angle ratio is corrected to be small when the actual steering angle is excessively steered with respect to the predicted steering angle, and to be increased when the actual steering angle is insufficiently steered. The vehicle steering system according to claim 1, wherein: 3. The vehicle steering system according to claim 1, wherein the index value is a difference between a maximum peak value and a minimum peak value of the derivative of θe in one curve. apparatus. The correction of the steering angle ratio map is performed by adding a correction amount to the value of the steering angle ratio with respect to the vehicle speed during traveling and rewriting the weight, and the value of the steering angle ratio at a vehicle speed near the traveling vehicle speed is also weighted by the correction amount. The vehicle steering apparatus according to claim 1 or 2, wherein the correction is performed by a value multiplied by: 5. The vehicle according to claim 1, wherein the steering angle predicting means has a proportional operation, a differential operation, and a time delay operation as the ideal steering control characteristics of the driver. Steering device. 6. The front road shape detecting means is a camera for photographing a road image ahead of the vehicle, and the steering angle predicting means calculates a center between white lines, that is, a running lane center from the road image photographed by the camera. 3. The vehicle according to claim 1, wherein an ideal steering angle of the driver is predicted from a lateral distance difference between a center position of the traveling lane ahead of a predetermined distance and a position when the vehicle is straight ahead. Steering gear. 7. The vehicle steering system according to claim 1, wherein the front road shape detection means is a navigation device.