JP3246119B2 - Automatic steering device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic steering apparatus for a vehicle suitable for use in an automobile, and more particularly to an automatic steering apparatus for a vehicle capable of recognizing a reference line and a curvature of a road so as to enable smooth steering. About.

[0002]

2. Description of the Related Art In recent years, in a steering mechanism provided in an automobile, for example, various sensors are provided in a vehicle, control signals are set based on information from these sensors, and the steering mechanism is actively activated by a hydraulic pressure or an electric motor. Many automatic steering devices or vehicles with automatic steering have been proposed that perform steering automatically and automatically.

For example, Japanese Patent Application Laid-Open Nos. 3-137798 and 4-504 disclose such an automatic steering device. Many have been proposed.

[0004]

However, a skilled driver drives the vehicle without giving the occupant a sense of incompatibility while correctly grasping the driving state of the automobile and the surrounding traffic conditions and accurately controlling the steering mechanism. There is a problem that it is very difficult to realize such a natural running feeling.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an automatic steering apparatus for a vehicle which can achieve a more natural driving feeling by approaching artificial steering characteristics. And

[0006]

According to a first aspect of the present invention, there is provided an automatic steering apparatus for a vehicle, comprising: a steering actuator for steering a steered wheel of a vehicle; and an imaging unit for imaging a road ahead of the vehicle. Image information processing means for processing image information from the imaging means; and setting a target steering angle based on the processing information from the image information processing means, and driving the steering actuator so as to obtain the target steering angle. and a control means for controlling, said image information processing means, from the image information
Lateral deviation calculating means for calculating a lateral deviation of the vehicle with respect to a reference line of the road based on a first reference position close to the vehicle in the obtained road information ; and a road obtained from the image information.
A second reference in the information ahead of the first reference position in the vehicle;
A declination calculating means for calculating a declination of the vehicle with respect to a road direction ahead of the vehicle based on the position ;
The control means sets the target steering angle based on information from the lateral deviation calculating means and the argument calculating means such that the lateral deviation and the argument are both reduced. And

Further, vehicular automatic steering device of the present invention according to claim 2, in addition to the first aspect, wherein the control hand
Step calculates the curve radius of the road based on the declination
Curve radius calculating means for calculating the curve radius and the
It is characterized in that the target steering angle is set based on the lateral deviation .

Further, the automatic steering apparatus for a vehicle of the present invention according to claim 3, wherein, in addition to the above-mentioned arrangement of the claim 1, comprising a vehicle speed detecting means for detecting a vehicle speed of the vehicle, the polarized angle calculating means Is configured to receive the information from the vehicle speed detecting means and calculate the declination at a point separated from the vehicle by a distance corresponding to the vehicle speed.

According to a fourth aspect of the present invention, in the vehicle automatic steering system according to the second aspect of the present invention, in addition to the configuration of the second aspect, the declination calculating means includes the road surface information obtained from the image information. The declination is calculated from reference line position information at a first point that is a predetermined distance away from the vehicle and reference line position information at a second point that is further away from the vehicle than the first point. It is characterized by being set to.

According to a fifth aspect of the present invention, in the vehicle automatic steering system according to the fourth aspect, the first point is a part of the road surface information obtained from the image information. It is a point closest to the vehicle. According to a sixth aspect of the present invention, in addition to the configuration of the fifth aspect, the vehicle automatic steering device further includes a vehicle speed detecting means for detecting a vehicle speed of the vehicle, and the second point is provided by the second point. Based on information from the vehicle speed detecting means, it is a point separated from the vehicle by a distance corresponding to the vehicle speed.

According to a seventh aspect of the present invention, there is provided an automatic steering apparatus for a vehicle, comprising: a steering actuator for turning a steered wheel of a vehicle; an imaging unit for imaging a road ahead of the vehicle; and an image from the imaging unit. Image information processing means for processing information, vehicle speed detection means for detecting the vehicle speed of the vehicle, and a target steering angle set based on the processing information from the image information processing means, so that the target steering angle is obtained. Control means for controlling the driving of the steering actuator, wherein the image information processing means calculates a deflection angle β at a point separated from the vehicle by a predetermined distance K using road surface information obtained from the image information. An angle calculating means, the control means comprising a vehicle stability factor A and a wheel base W stored in advance.
B, the vehicle speed V obtained from the vehicle speed detection means, and the distance K
Δ = (1 + AV ² ) · (WB /
K). The target steering angle δ is set based on the relational expression of β.

According to an eighth aspect of the present invention, in addition to the configuration of the seventh aspect, the predetermined distance K is given as a function of the vehicle speed of the vehicle. And

[0013]

In the vehicle automatic steering system according to the first aspect of the present invention, when a road ahead of the vehicle is imaged by the imaging means, the image information is processed by the image information processing means. Then, the control means sets the target steering angle based on the image processing information, and the control means drives the steering actuator so that the target steering angle is obtained, and steers the steered wheels.

At this time, the control means reduces both the lateral deviation and the declination of the vehicle based on information from the lateral deviation calculating means and the declination calculating means provided in the image information processing means. The steering actuator is controlled. In the vehicle automatic steering device according to the present invention,
The curve radius is calculated from the above declination by the curve radius calculation means.
Calculated based on the curve radius and the lateral deviation.
The steering angle is set.

In the vehicle automatic steering apparatus according to the third aspect of the present invention, the vehicle speed information from the vehicle speed detecting means is input to the declination calculating means, and the deviation at a point separated from the vehicle by a distance corresponding to the vehicle speed is obtained. An angle is calculated. In the vehicle automatic steering apparatus according to the fourth aspect of the present invention, the declination calculating means includes, among the road surface information obtained from the image information, reference line position information at a first point separated from the vehicle by a predetermined distance;
The declination is calculated from the reference line position information at the second point further away from the vehicle than the first point.

Further, in the vehicle automatic steering apparatus according to the present invention, the point closest to the vehicle is the first point in the road surface information obtained from the image information. Claim 6
In the vehicle automatic steering system according to the present invention, when the vehicle speed of the vehicle is detected by the vehicle speed detecting means, a point separated from the vehicle by a distance corresponding to the vehicle speed is determined based on the vehicle speed information.
It becomes the point of.

Further, in the automatic steering apparatus for a vehicle according to the present invention, when a road ahead of the vehicle is imaged by the image pickup means, the image information from the image pickup means is processed by the image information processing means. Then, the target steering angle is set by the control means based on the processing information of the image, and the steering actuator is driven so as to obtain the target steering angle. As a result, the steered wheels are steered.

Then, the declination calculation means calculates the declination β at a point separated from the vehicle by a predetermined distance K, and the control means stores the stability factor A and the wheel base WB of the vehicle stored in advance and the vehicle speed. From the vehicle speed V obtained from the detecting means, the distance K, and the declination β, the target steering angle δ is δ = (1 + AV ² ) · (WB / K) ·
It is set based on the relational expression of β.

In the automatic steering apparatus for a vehicle according to the present invention, the predetermined distance K is given as a function of the vehicle speed of the vehicle, and changes according to the vehicle speed.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an automatic steering system for a vehicle according to an embodiment of the present invention. FIG. FIG. 2 is a functional block diagram, FIG. 2 is a schematic configuration diagram showing a main part configuration, FIG. 3 is a schematic diagram showing a relationship between a radius of curvature and an argument, and is a schematic diagram viewed from above the vehicle, FIG. Is a graph showing the relationship between the declination of the vehicle and the curve radius of the road, FIG. 5 is a graph showing the relationship between the declination of the vehicle due to the driver steering and the steering angle, and FIG. Is a graph showing the relationship between the peak value of the lateral acceleration and the peak value of the lateral jerk (the amount of change in the lateral acceleration per unit time). FIG. 7 is a graph showing the relationship between the steering start distance and the steering speed in the automatic steering. FIG.
(A) to (f) are schematic diagrams for explaining the white line recognition method, FIG. 9 is a graph showing a relationship between the vehicle speed and the steering start distance, and FIG. 10 is a characteristic between the automatic steering and the driver steering. FIG. 11 is a graph showing the relationship between the vehicle speed and the steering start distance, and FIG. 11 is a schematic diagram for explaining the variation of the declination angle, and is a schematic diagram viewed from above the vehicle.
2 is a schematic diagram showing the deviation between the vehicle and the center of the road when the vehicle turns, and is a diagram viewed from above the vehicle. FIG. 13 illustrates the setting of the gain when the declination detection point corresponds to the vehicle speed. FIG. 14 is a schematic block diagram for explaining gain setting when the deflection angle detection point is fixed, and is a diagram corresponding to FIG. 13 and FIG.
18 are diagrams for explaining the effect, and FIG. 15 is a diagram showing an example of a curved road, and a graph showing the steering characteristics thereof. FIG. Graph (b) showing steering angle characteristics when traveling on a curved road
Is a graph showing the characteristics of the lateral acceleration of the vehicle when traveling on a curved road during automatic steering and during driver steering. FIG. 17 is a graph showing the relationship between the peak value of lateral acceleration and the peak value of lateral jerk during automatic steering and during driver steering. Graph showing the relationship, FIG.
(A) to (c) are diagrams for explaining an example of recognition of a road reference line, FIG. 19 is a schematic diagram showing an example of the overall configuration of the steering actuator, and FIG. 20 is a method for setting the forward gaze distance. FIG. 21 is a graph for explaining the graph corresponding to FIG. 10, and FIG. 21 is a diagram for explaining a method of setting the argument gain, and is a schematic diagram viewed from above the vehicle.

[0021] As shown in FIG.
Actuator 2A for turning the vehicle, and a camera 3 as an imaging unit for imaging the road condition ahead of the vehicle.
And an image information processing means 4 for processing image information from the camera 3 and a controller 5 as a control means for setting a control signal to the steering actuator 2A.

That is, the vehicle 1 is an auto-steering vehicle that automatically steers the steered wheels 2 based on an image captured by the camera 3. Based on the information, a target steering angle is set as a control amount for controlling the steered wheels 2, and the steering actuator 2A operates according to the set amount of the target steering angle.

Here, the configuration of the control function of the automatic steering device will be described. The driver performs the steering operation (changes the steering angle) mainly in a case where the traveling direction of the vehicle 1 is to be corrected when it does not match the direction of the road (traveling lane) on which the vehicle is traveling. In addition, in addition to this, when the vehicle 1 is going to run out of the traveling lane in the lateral direction (outside of the left and right), it may be possible to correct this. The traveling direction may not match the traveling lane direction, while it is considered that the vehicle is traveling on a curved road, but the traveling direction is shifted from the traveling lane direction because the vehicle itself moves in the yaw direction even when traveling on a straight traveling road. It may come off.

Therefore, in the present apparatus, steering is mainly performed so that the traveling direction of the vehicle 1 matches the direction of the traveling lane, and a steering element for correcting the lateral position of the vehicle 1 is added thereto. It has become. In the case of artificial steering (driver steering), the relative operation between the vehicle and the road is determined based on information visually obtained by the driver, and the steering operation is performed. In other words, the driver determines the relative relationship (deviation) between the traveling direction of the vehicle 1 and the traveling lane direction and the lateral displacement (lateral deviation) of the vehicle 1 based on the information obtained from the eyes. The steering operation is performed so as to correct.

When the information obtained by the driver is visually arranged,
It can be classified into three elements: the radius of the road curve, the vehicle speed, and the riding comfort (lateral acceleration, lateral jerk). Also,
In general, when the vehicle is traveling on a steady circle on a curved road, a portion close to the circle, a straight road, or the like (at the time of steady traveling), the driver tries to maintain a constant steering angle. The steering is performed so as to maintain the steering angle δ0 which is in accordance with the above. On the other hand, when trying to enter the curved road from the straight road (at the time of transient traveling), the steering angle δ is gradually increased to a steering angle δ0 corresponding to the curvature of the curved road from a little before the curved road. Go. In this case, the driver determines how far ahead of the point on the curved road the steering should be started (that is, how much the steering start distance D should be) and what percentage (the steering angle δ at the steering speed δV). the is gradually allowed) or increased, set in consideration of the time of vehicle speed and expected comfort (lateral acceleration of the depth at) and the like.

That is, when the steering elements determined by the driver during the steering operation are classified, they are divided into a steering angle δ ₀ , a steering start distance (steering start timing) D, and a steering speed δ _V. In this device, automatic steering is performed by a method similar to the driver steering. Therefore,
In this device, the image processing means 4 corresponding to the driver's visual system and the respective amounts required for steering, that is, the steering angle δ ₀ , the steering start distance D,
It's and a controller 5 for setting the steering speed [delta] _V.

Here, the image information processing means 4 corresponding to the visual system of the driver will be described first. As shown in FIG. 1, the image information processing means 4 includes an image converting means 4C, a lateral deviation calculating means 7, an argument calculating means 6, and a curvature state estimating means 9. Then, when the state of the road is imaged by the camera 3, the original image 4A from the camera 3 is obtained.
Is taken in, and this original image 4A is
By C, the planar view image 4B as if viewed from above
Has been converted to.

In the declination calculating means 6, a point separated from the vehicle 1 by a predetermined distance based on the plane view image 4B (ie,
The declination at a point at a predetermined height in the planar view image 4B) is calculated. The declination is, as shown in FIG. 1, an angle formed between a tangent to the curved road center line and the vehicle center line. The declination β is calculated as follows. That is, as shown in FIG. 1, reference line position information at a first point (first detection point, shown as perigee in the figure) separated from the vehicle by a predetermined distance, and a point further from vehicle 1 than this perigee A second point separated by a fixed amount (second detection point,
The declination β is calculated from the reference line position information at the apogee in the figure). In this example, the first detection point is a detection point of the lateral deviation, that is, the camera 3
Is the point closest to the vehicle in the image information by

The deflection angle β is calculated as an angle between a straight line connecting the first detection point and the second detection point and the center line of the vehicle 1. The declination calculated in this way is the declination of the intermediate point (the mark x in the figure) between the first detection point and the second detection point, and is at least the declination of a point at least a certain distance ahead of the vehicle 1. . Further, the curvature state estimating means 9 estimates the curve radius R based on the argument β calculated by the argument calculating means 6. That is, the declination β of the road taken by the camera 3 is fed forward to the curvature state estimating means 9 as a value for reflecting the curve radius R.

A method of estimating the curve radius R will be described. As shown in FIG. 3, when the declination β is calculated a predetermined distance K ahead of the vehicle 1, the curve radius is calculated when the declination β is relatively small. R, the predetermined distance K, and the argument β can be geometrically approximated by the relational expression of R · β = K (1). That is, assuming that the distance K is constant to the detection point of the declination β, the curve radius R
And the argument β are in inverse proportion. This is proved by the experimental results as shown in FIG. Therefore, the curve radius R is estimated from this equation (1). The lateral deviation calculating means 7 will be described later.

Next, the controller 5 will be described.
The controller 5 includes a steering angle setting unit 5A, a steering start distance setting unit 5B, a steering speed setting unit 5C, and an adder 5D for finally setting a steering angle. In the steering angle setting section 5A, the steering angle δ ₀ is set as follows. Since the driver determines the steering angle at the time of steady turning of the curve according to the radius of curvature R of the curve, the present device also
Similarly to the driver steering, when the curve radius R is estimated, the steering angle δ ₀ is set based on the curve radius R.

That is, the steering angle setting section 5A receives the curve radius R estimated by the above-mentioned curvature state estimating means 9 and the vehicle speed V obtained from the vehicle speed detecting means 16, and inputs these values R, V. The steering angle δ0 is kinematically determined according to the following equation (2) based on the stability factor A of the vehicle 1 and the wheelbase WB input in advance. δ0 = (1 + AV2) · (W B / R) ····· (2) Substituting the polarization angle beta at which the aforementioned equation (1), δ0 = (1 + AV2) · (WB / K) · β · ... (3) According to this equation (3), it is possible to directly obtain δ0 from the declination β and the vehicle speed V without using the curve radius R. Therefore, in actual control, δ0 is obtained using equation (3).
Find 0. The graph shown in FIG. 5 is experimental data showing the relationship between the declination β and the driver's steering angle. From this graph, as shown in equation (3), the declination β and the driver's steering angle , Are approximately proportional.

When the steering angle δ ₀ is set so as to feed forward the curve radius R or the declination β in front of the vehicle 1, the steering angle setting unit 5 A issues
The steering angle δ ₀ (the steering angle command value s ₀ ) is input to the steering actuator (steering actuator) 2A of the vehicle 1. The steering angle command value s ₀ allows the vehicle 1 to travel while being adjusted in a direction along the direction of the traveling lane.

When the vehicle 1 is traveling with a certain inclination (angle β2) with respect to the center line of the road when viewed from above, as shown in FIG. , The angle β2 due to the inclination of the vehicle 1 is also included. Therefore, the declination gain K
1 is the gain K ₁₁ set by the declination β 1 and the angle β 2
Than it is set from the gain K ₁₂ Metropolitan set by.

Originally, the gains K ₁₁ and K ₁₂ should be determined independently of each other.
By setting the gain K1 as K ₁₁ + K ₁₂ , steering control for matching the current direction of the vehicle 1 to the direction of the road and steering control for matching the vehicle 1 to a direction corresponding to the curvature R of the curve ahead are performed. Can be realized simultaneously. The lateral deviation calculating means 7 determines how much the vehicle 1 is laterally displaced from the road center 8 by the amount of deviation (lateral deviation).
Is calculated, and the value of the lateral deviation is calculated based on the converted planar image 4B.
In addition, since the lateral deviation is desired to be an amount corresponding to the lateral deviation of the current position of the vehicle 1, the point closest to the vehicle in the planar view image 4B (that is, the lowest point in the effective portion in the planar view image 4B). (Point).

In this example, it is assumed that the white line 12 at the left end of the road, which corresponds to the road-side portion of the left-hand traffic, is a reference line, and a position at a certain distance from the reference line to the right (= a distance approximately half the lane width) is the road center. It has become. Then, the distance from the center of the road to the left and right centers of the vehicle 1 is calculated as a lateral deviation. Note that, here, the left and right centers of the camera 3 are installed so as to coincide with the left and right centers of the own vehicle 1, and this lateral deviation corresponds to the distance between the left and right center line 3A on the planar view image 4B and the road center line. .

When the lateral deviation of the vehicle 1 is calculated by the lateral deviation calculating means 7, a deviation × gain K0 is set as a control command value for bringing the lateral deviation closer to 0 according to the lateral deviation.
, A steering angle δ ₁ is set, and the steering actuator 2A is controlled according to the command value s ₁ of the steering angle δ ₁ . Then, by the steering control through the command value s _1, lateral deviation of the vehicle 1 is reduced, which is a traveling position of the vehicle 1 so as to fix the center of the traffic lane of the road. The method for recognizing the white line 12 will be described later in detail.

The aforementioned steering angle command value s ₀ is a signal that is set using the declination β of the curve ahead of the vehicle 1, whereby the vehicle 1 travels while predictively controlling the curve ahead. You can do it. Thus the steering angle [delta] ₀ is set by the feed-forward, to complement this, since the feedback of the lateral deviation of the above, the command value s ₀ of the feedforward steering actuator 2A
And the feedback command value s ₁ are input. Here, the steering angle δ is mainly determined by the deflection angle gain K1.
₀ is set and the lateral deviation gain K0 is set small.
The influence on the vehicle 1 by the control based on the lateral deviation gain K0 when a disturbance is input can be minimized.

By the way, in the steering start distance setting section 5B,
The steering start timing (steering start distance D) is set in consideration of the vehicle speed and the riding comfort. In general, at the time of steering, lateral acceleration is applied to the vehicle 1, the driver, and the like, and it is considered that the lateral acceleration has a great influence on the riding comfort. On the other hand, as shown in FIG. 5, the relationship between the lateral acceleration of various curves and the lateral jerk (the amount of change in the lateral acceleration per unit time) in driver steering is represented by a curve radius R, a vehicle speed V,
Regardless of the driving sensation, the ratio of lateral acceleration to lateral jerk is a substantially constant value.

This means that if the vehicle 1 operates the steering wheel with a constant lateral jerk when entering a curve, the steering time ΔT required to reach a constant lateral acceleration is constant. Further, the steering start distance D is represented by the following equation (4) as a product of the steering time ΔT and the vehicle speed V. Where ΔT
Is constant, the steering start distance D is proportional to the vehicle speed V, and the steering start distance setting unit 5B determines the steering start distance D from the vehicle speed V. D = ΔT · V (4) The steering start distance D and the vehicle speed V actually performed by the driver
9A is as shown in FIG. 9A, and it is verified that the steering start distance D is set in proportion to the vehicle speed V.
Note that the steering start distance D is a distance from the host vehicle 1 to the curve entrance as shown in FIG. 9B.

The steering time ΔT is given by ΔT = δ ₀ / δ _V = V ² / (R · J) = constant (5) where J is the lateral jerk. Assuming that ΔT is constant from equation (5), the vehicle speed V becomes
It can be seen that the lateral jerk J should be set according to the curve radius R so that the value of the lateral jerk J does not exceed a certain upper limit in consideration of the riding comfort.

As described above, by setting the timing (steering start distance D) at which the steering is started in accordance with the vehicle speed V, the user can ride in a transition region between a straight road and a curved road, a region where the curvature of the road changes, and the like. It achieves comfortable and smooth running. Next, the steering speed setting unit 5C will be described. In the steering speed setting unit 5C, the steering speed δ _V is set based on the steering start distance D set by the steering start distance setting unit 5B. .

[0043] That is, as shown in the graph of FIG. 7, the relation between the steering start distance D in the automatic steering and the steering velocity [delta] _V, the steering start distance D is set, originally, the steering speed [delta]
_V is determined dependently. Then, the steering speed δ _V set by the steering speed setting section 5C is taken into the declination calculating means 6.

Here, a method of recognizing the white line 12 on the road as a reference line, which is a reference for calculating the declination β and the lateral deviation, will be described. Here, the recognition of the white line 12 as the roadside line at the left end of the traveling lane will be described. First, FIG.
As shown in (a), the camera 3 provided in the vehicle 1 uses a camera 3 in an area in front of the vehicle (for example, 5 m to 20 m) on flat ground.
m), the image in the vertical direction on the screen is partially omitted from the image information. Then, a plurality of horizontal lines 11 are set at equal intervals on this screen. The reference numeral 12 indicates the black and white image information indicating the white line of the road, and is updated every minute control cycle. As shown in FIG. In, a required range (here, left and right 50 pixels [dot]) of the white line position on the previous screen is set as a white line search area (processing target area) 10. Also,
For the first screen, the white line position on the straight road is used as the previous screen data.

Then, as shown in FIG. 8C, the brightness of each horizontal line is differentiated in the horizontal direction from the left. Reference numeral 14 in the figure is a guardrail. By the way, a normal road surface has low luminance and a small change in luminance. On the contrary,
Since the brightness of the white line 12 is much higher than that of the normal road surface, when the brightness of the road is differentiated in this way, the luminance change is positive at the boundary point from the normal road surface to the white line 12, and the white line 12 changes to the normal road surface. Differential data is obtained such that the luminance change becomes negative at the boundary point of. FIG. 8D shows an example of such differential data.

Then, with respect to the data of each horizontal line 11, the peaks of the differential values appear in the order of plus and minus from the left, and the interval between the peaks is the white line 12
As a white line candidate, a combination that fits within a reasonable degree (interval between a positive peak and a negative peak is, for example, within 30 dots) is extracted as shown in FIG.
As shown in (e), the midpoint is stored as a white line candidate point 15.

Then, among these white line candidate points 15,
Only the point closest to the screen center is left as the final candidate point.
This means that, for example, when the vehicle 1 is traveling on the left side, the search area 1
The right side of 0 is a road surface with little change in normal luminance, and the white line candidate point 15 closest to this normal road surface can be determined as the white line 12. Therefore, further to the left of the white line 12,
Objects that cause noise (for example, guardrails 14)
, The white line 12 can be reliably recognized from the image information captured by the camera 3.

Finally, as shown in FIG. 8 (f), the continuity of the white line candidate points 15 in each horizontal line data in the vertical direction is sequentially verified from the bottom of the screen. First, the inclination between the upper and lower ends of the white line 12 on the previous screen is calculated in advance.
Then, assuming that the lowest point 15A is the white line 12, it is verified whether or not the candidate point 15B on the upper horizontal line 11 is within the range of ± 50 dots of the inclination of the previous white line 12.

If the candidate point 15B falls within this range, it is regarded as a white line. If not, the candidate point 15B is rejected, and the coordinates obtained by interpolation from the above-mentioned inclination are regarded as the white line position. Then, this verification is performed for each horizontal line in the same manner, whereby a continuous white line 12 can be recognized. Such white line recognition work is continuously performed at a required cycle, and the recognition of the white line 12 is updated each time.

When the white line 12 is detected, the lateral deviation and the deflection angle β are calculated in the vehicle 1. Among these, the lateral deviation is determined from the effective road surface information obtained from the image information. This is calculated using the reference line position information of the point closest to the vehicle 1, whereby a value close to the lateral deviation at the current position of the vehicle 1 is calculated, and the control accuracy is improved. . Note that the point closest to the vehicle 1 is the first detection point used when calculating the above-mentioned argument β.

By the way, the higher the vehicle speed, the more it becomes necessary to grasp the road condition farther from the vehicle than the road condition immediately before the vehicle. That is, the line a in FIG. 10 indicates the driving characteristics of the driver. As shown in this graph, the higher the normal vehicle speed, the longer the gaze distance in front.
Therefore, in the present apparatus, based on such steering characteristics of the driver, of the two detection points for calculating the argument β, the second detection point is dynamically changed as shown by the line c in FIG. ing. As a result, the forward gaze distance, that is, the distance K from the vehicle 1 to the intermediate point between the first detection point and the second detection point becomes like the line b, and can be closer to the line a indicating the driving characteristics of driver steering. It is. Incidentally, as shown in FIG. 20 (a), the look-ahead distance, the second detection point is dynamically changes the first detection point remains fixed (see line c ₁₎ (line d
₁ ), the vehicle speed may be made to correspond to the vehicle speed. As shown in FIG. 20B, both the first and second detection points are changed according to the vehicle speed (see lines c ₂ and d ₂₎ . ) The forward fixation distance may be determined.

Thus, when the vehicle speed is high, the deflection angle β is calculated sufficiently before the curve, and when the vehicle speed is sufficiently low, the deflection angle β is calculated at a position relatively close to the entrance to the curve. That is, as shown in FIG.
For fixed both detection point, since the steering angle command value s _0, regardless of the vehicle speed is set, the steering becomes constant regardless of the vehicle speed, it is caused discomfort to the steering.

On the other hand, as shown in FIG. 13, the value of the calculated declination β is changed by changing the gaze distance in front corresponding to the vehicle speed, and the declination gain K
By also making 1 variable, steering according to the vehicle speed can be realized. In addition, by moving the detection point for calculating the declination β back and forth according to the vehicle speed in this manner, FIG.
As shown in FIG. 1, it is conceivable that the value of the argument β calculated fluctuates even though the curves are the same.

Therefore, it is necessary to absorb such a variation of the argument β. As shown in the above equation (3), the steering angle δ ₀ is determined by the coefficient (1 + AV ² ) · WB / K
And the factor of 1 / K in this coefficient component works to offset the variation of the argument β, and the steering angle δ
₀ is set appropriately. Incidentally, the lateral deviation gain K0 is merely a correction amount,
As shown in FIG. 12, when the vehicle 1 is traveling in a curve, a certain amount of lateral deviation is output due to the influence of the curvature of the curve even when the vehicle 1 is traveling in the center of the road. Can be considered. In such a case, the deviation gain K0 is set to be larger than necessary due to the output lateral deviation.

[0055] Therefore, for example, (3) may be smaller setting the declination gain K1 from the steering angle [delta] ₀ which is calculated by subtracting a predetermined value in expression. This predetermined value is a correction gain obtained empirically or calculated by calculation. As described above, by setting the deflection angle gain K1 to a value smaller by the amount of the correction gain, the deviation gain K0 set larger can be complemented, and the steering actuator 2A can be operated accurately.

As the steering actuator 2A, for example, the following hydraulic power steering mechanism 104 is used.
It is possible to use one. As shown in FIG. 19, a power steering mechanism 104 is provided in the steering force transmission system 103 of the vehicle 1, and when a steering force is input to the steering wheel 20, the steering force is changed according to the steering state of the vehicle. It is designed to be assisted.

The power steering mechanism 104 is configured as a hydraulic power steering mechanism that assists a steering force with a hydraulic pressure. By supplying hydraulic oil of a predetermined hydraulic pressure to the hydraulic cylinder 104A, the steering force of the driver is reduced. It can be reduced. For this reason, this vehicle is provided with an oil pump 110 driven by, for example, an electric motor 122 or the like. The oil pump 110 draws hydraulic oil from the oil tank 111.

The hydraulic oil discharged from the oil pump 110 is branched by a flow dividing valve 112 in two directions. One of the oil passages is, for example, EP
It is connected to a known power steering valve such as an S valve 115, and the hydraulic state of the hydraulic cylinder 104 </ b> A is adjusted through the EPS valve 115.

Further, as shown in FIG. 19, the hydraulic system is provided with an automatic steering control valve 107 as an automatic steering means. Oil passages are connected. The automatic steering control valve 107 is a valve for controlling a steering amount at the time of automatic steering.
By operating the hydraulic cylinder 1 during automatic steering.
04A can be supplied with hydraulic oil of a predetermined oil pressure.

The vehicle is provided with a mode switching valve device 106 for switching between a state in which the power steering mechanism 104 is operated and an automatic steering state. The mode switching valve device 106 and the automatic steering control valve 107 are provided. The steering actuator 2A is composed of the hydraulic cylinder 104A and the hydraulic cylinder 104A. This mode switching valve 1
Reference numeral 06 switches between performing steering by the power steering mechanism 104 and performing automatic steering. The switching between the automatic steering control valve 107 and the hydraulic cylinder 104A and between the EPS valve 115 and the hydraulic cylinder 104A are performed. It is interposed between.

The mode switching valve 106 is normally in a mode in which it is steered by the power steering mechanism 104, and the hydraulic oil supplied to the EPS valve 115 passes through the mode switching valve 106 and the hydraulic cylinder 104A
And assists the steering force.
Further, between the oil pump 110 and the flow dividing valve 112,
A relief valve 113 is provided. The relief valve 113 is opened when hydraulic oil higher than a predetermined oil pressure is supplied to the automatic steering control valve 107 or the EPS valve 115, and returns the hydraulic oil to the oil tank 111.

The steering mechanism includes a controller 5.
The open / close state of the relief valve 113 is controlled by a control command value set by the controller 5, and the automatic steering control valve 107 and the mode switching valve 106 are also controlled by the controller 5. It has become. Thus, at the time of automatic steering, the mode switching valve 106 is switched to the automatic steering mode based on the control command value of the controller 5, and the automatic steering control valve 10 is controlled based on this control command value.
7 is controlled, and required hydraulic oil is supplied to the hydraulic cylinder 104A. The hydraulic pressure of the hydraulic oil causes the vehicle 1
Is steered.

The rack 102 is provided with a rack position detection sensor 120 for detecting the position of the rack 102, and detection information from the rack position detection sensor 120 is fed back to the controller 5. . During automatic steering, the steering wheel (hereinafter, referred to as a steering wheel) is controlled by supplying hydraulic oil to the hydraulic cylinder 104A. However, when the steering wheel 20 is steered with an input larger than the operating hydraulic pressure, the operation is started. Steering wheels can be steered by overcoming hydraulic pressure.

The above-described configuration is merely an example of the steering force transmission system 103, and is not limited to such a configuration. For example, as a hydraulic oil supply source of hydraulic oil,
Not limited to the electric motor 122, a motor using the driving force of the engine may be used. Since the vehicle automatic steering device as one embodiment of the present invention is configured as described above,
The setting of the steering angle δ ₀ , the steering start distance D, and the steering speed δ _v is periodically performed by a signal flow as indicated by an arrow in FIG.
Based on this, the steering actuator 2A is periodically controlled to steer the vehicle 1.

That is, the declination calculation means 6 calculates the declination β of the vehicle 1 based on the image taken by the camera 3, and the lateral deviation calculation means 7 calculates the lateral deviation of the vehicle 1. . Then, according to this declination β, s ₀ is set as a control command value for approaching the declination β to 0, and according to the lateral deviation, s ₁ is set as a control command value for approaching the lateral deviation to 0. Is set.

When the vehicle travels on a straight running road or a steady circular curved road (during a steady running), the lateral deviation and the declination approach zero based on the command values s ₀ and s ₁ set by the controller 5. By controlling the steering actuator 2A as described above, the vehicle 1 can accurately travel on the traveling lane of the road. In particular, since the steering angle δ ₀ is set by feeding forward the curve radius R and the declination β in front of the vehicle 1, there is no small change in set values such as feedback control. The vehicle can travel while performing predictive control.

Thus, natural steering control can be performed, and the vehicle 1 travels while being adjusted in a direction along the direction of the traveling lane. By the way, the steering angle is set by the deflection angle gain K1 and the lateral deviation gain K0 which complements the steering angle gain. Here, the lateral deflection gain K0 is relatively small, and the steering angle δ is mainly determined by the deflection angle gain K1.
_{Since 0} is set, the influence of the lateral deviation gain K0 on the vehicle 1 when disturbance is input can be minimized.

Further, in the present apparatus, based on the steering characteristics of the driver, the forward fixation distance K for calculating the declination β is changed according to the vehicle speed, and the declination β is calculated according to the vehicle speed. Steering according to the vehicle speed can be realized, and the driving characteristics of the driver can be approximated. Further, the steering start distance setting unit 5B sets a timing (steering start distance D) at which the steering is started according to the vehicle speed V, while taking into consideration that the lateral jerk J does not exceed a predetermined value.
This is because, by actually detecting the curve at the front position corresponding to the vehicle speed V and starting the steering together with the detection of the curve, the control based on the steering start distance D is performed simultaneously with the setting of the steering start distance D. .

The steering speed δ _V at this time is determined in accordance with the steering start distance D. However, the steering speed δ _V is actually set within the steering angle δ ₀ set by reflecting the steering start distance D. used for control in the form of velocity [delta] _V is included. As a result, even when the steering angle is increased at the time of entering a curve, FIG.
As shown in FIG. 7, the peak of the lateral acceleration is suppressed so as to correspond to the lateral jerk, and a relatively slow running feeling can be realized with almost the same feeling as driver steering. As described above, it is possible to realize a comfortable and smooth traveling in a transition area between a straight road and a curved road, an area where the curvature of the road changes, and the like.

When the vehicle travels on a curved road as shown in FIG. 15 by the automatic steering as described above, the steering characteristics as shown in FIG. 16 can be obtained. Here, FIG.
A line a shown in (a) is a steering angle characteristic of the automatic steering when the forward gaze distance D is fixed, a line b is a steering angle characteristic of the automatic steering when the forward gaze distance D is changed according to the vehicle speed, Line c
Is a steering characteristic by driver steering. FIG.
A, B, and C in (a) and (b) correspond to A, B, and C in FIG.

As shown in FIG. 16 (a), by changing the front gaze distance D according to the vehicle speed, the steering angle characteristic (line b) of the automatic steering becomes substantially the same as the driver steering (line c). Steering characteristics can be made more natural than when the front gaze distance D is fixed (line a). Also, as shown in FIG. 16B, the lateral acceleration (lateral G) generated by the steering can have substantially the same characteristics as the driver steering, and a natural steering feeling can be obtained without giving the occupant a feeling of strangeness. Can be.

The road white line 12 is estimated on the basis of the amount of change in luminance on the road, and the image information from the camera 3 that is close to the center of the screen is estimated as the road white line 12. As shown in FIG. 18A, when the previous image information is processed and the road white line 12 is recognized, disturbance (noise) such as a manhole is input at the next cycle as shown in FIG. 18B. Also, the road white line 12 can be correctly recognized.

That is, by continuously performing such white line recognition work at a required cycle and updating the recognition of the white line 12 each time, a disturbance such as a manhole on the road as shown in FIG. Noise), the road white line 1
2 can be prevented from being erroneously recognized. Further, when the white line 12 is detected in this manner, the lateral deviation and the deflection angle β are calculated in the vehicle 1, and the lateral deviation is a position of the point closest to the vehicle 1 among the road surface information obtained from the image information. Since the calculation is performed using the reference line position information, a value close to the lateral deviation at the current position of the vehicle 1 is calculated, and the control accuracy is improved.

[0074]

As described above in detail, according to the automatic steering apparatus for a vehicle according to the first aspect of the present invention, the steering actuator for turning the steered wheels of the vehicle and the imaging for imaging the road ahead of the vehicle. Means, image information processing means for processing image information from the image pickup means, and a target steering angle set based on the processing information from the image information processing means, and the steering actuator so as to obtain the target steering angle. and a control means for controlling the drive, the image processing means, whether the image information
A lateral deviation calculating means for calculating a lateral deviation of the vehicle with respect to a reference line of the road based on a first reference position close to the vehicle among the road information obtained, and a road obtained from the image information.
A second unit in the road information ahead of the first reference position in the vehicle.
A declination calculating means for calculating a declination of the vehicle with respect to a road direction ahead of the vehicle based on the quasi-position , and the control means transmits information from the lateral deviation calculating means and the declination calculating means to based, as lateral deviation and polarization angle decreases both, the configuration of setting the target steering angle in accordance with any road state, to realize the automatic steering of the natural feeling be able to. Also the vehicle
Has the effect of improving the response to lateral deviation
You.

Further, according to the vehicle automatic steering system of the present invention, the control means is configured to perform the control based on the declination.
Radius calculating means for calculating the radius of the curve of the above road
Including the above based on the curve radius and the lateral deviation
By setting the target steering angle , more natural flow is achieved.
Automatic steering of the wheeling can be realized .

According to a third aspect of the present invention, there is provided an automatic steering apparatus for a vehicle, comprising: a vehicle speed detecting means for detecting a vehicle speed of the vehicle; and the declination calculating means transmitting information from the vehicle speed detecting means. Receiving the vehicle and setting the declination at a point separated by a distance corresponding to the vehicle speed from the vehicle, so that the steering start timing at the time of entering a curve is made substantially the same as the artificial steering. Can be. As a result, it is also possible to realize automatic steering traveling with a natural steering feeling.

The running locus of the vehicle is also close to the running locus due to artificial steering, and automatic steering running with a natural steering feeling can be realized. Further, according to the automatic steering apparatus for a vehicle according to the present invention, the declination calculating means determines a reference value at a first point at a predetermined distance from the vehicle among road surface information obtained from the image information. With the configuration in which the declination is set to be calculated from the line position information and the reference line position information at a second point further away from the vehicle than the first point, the declination is set to the first angle. The angle between the line connecting the point and the second point and the center line of the vehicle is calculated, and this declination can be reliably detected.

According to the fifth aspect of the present invention, the first point is the point closest to the vehicle in the road surface information obtained from the image information. As a result, the detection accuracy of the lateral deviation and the declination of the vehicle is improved, and accurate steering control can be performed. According to the automatic steering device for a vehicle according to the present invention, the second point is provided based on information from the vehicle speed detecting means, based on information from the vehicle speed detecting means. With such a configuration that the vehicle is located at a distance from the vehicle by a distance corresponding to the vehicle speed, the declination is calculated at a point corresponding to the vehicle speed.

Further, according to the vehicle automatic steering apparatus of the present invention, a steering actuator for turning a steered wheel of the vehicle, an imaging means for imaging a road ahead of the vehicle,
Image information processing means for processing image information from the imaging means; vehicle speed detection means for detecting the vehicle speed of the vehicle; and a target steering angle set based on the processing information from the image information processing means. Control means for controlling the driving of the steering actuator so as to obtain an angle, wherein the image information processing means uses the road surface information obtained from the image information to adjust the bias at a point separated by a predetermined distance K from the vehicle. An angle calculating means for calculating the angle β, the control means controlling the stability factor A and the wheel base WB of the vehicle stored in advance, the vehicle speed V obtained from the vehicle speed detecting means, the distance K, From the argument β, δ = (1 + AV ² ) · (W
By setting the target steering angle δ based on the relational expression of B / K) · β, the steering gain, which is a control signal to the steering actuator, can be variably set. Automatic steering with a natural feeling can be realized according to the curvature state of the road up to the road.

Further, according to the automatic steering apparatus for a vehicle according to the present invention, the predetermined distance K is given as a function of the vehicle speed of the vehicle. The steering feel can be approximated.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a functional configuration of an automatic steering apparatus for a vehicle as one embodiment of the present invention so as to correspond to each function at the time of a steering operation by a driver.

FIG. 2 is a schematic configuration diagram showing a main configuration of an automatic steering device for a vehicle as one embodiment of the present invention.

FIG. 3 is a diagram schematically illustrating a relationship between a radius of curvature and a declination in the automatic steering device for a vehicle as one embodiment of the present invention, and is a schematic diagram viewed from above the vehicle.

FIG. 4 is a graph showing a relationship between a vehicle deflection angle and a road curve radius in a vehicle automatic steering system as one embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a vehicle deflection angle and a steering angle due to driver steering in the vehicle automatic steering device as one embodiment of the present invention.

FIG. 6 shows a relationship between a peak value of a lateral acceleration and a peak value of a lateral jerk (a change amount of a lateral acceleration per unit time) during traveling on a curve by driver steering in an automatic steering device for a vehicle as one embodiment of the present invention. It is a graph which shows a relationship.

FIG. 7 is a graph showing a relationship between a steering start distance and a steering speed in the automatic steering device for a vehicle as one embodiment of the present invention.

FIG. 8 is a schematic diagram for explaining a white line recognition method in the automatic steering device for a vehicle as one embodiment of the present invention.

FIG. 9 is a graph showing a relationship between a vehicle speed and a steering start distance in the automatic steering device for a vehicle as one embodiment of the present invention.

FIG. 10 is a graph showing a front gaze distance characteristic of automatic steering in a vehicle automatic steering apparatus as one embodiment of the present invention, as compared with driver steering.

FIG. 11 is a schematic diagram for explaining a variation of an argument in the automatic steering device for a vehicle as one embodiment of the present invention, and is a schematic diagram viewed from above the vehicle.

FIG. 12 is a schematic diagram showing a deviation between the center of the vehicle and the center of the road when the vehicle turns in the automatic steering device for a vehicle as one embodiment of the present invention, as viewed from above the vehicle.

FIG. 13 is a schematic block diagram for explaining setting of a gain when the declination detection point is set to correspond to the vehicle speed in the automatic steering device for a vehicle as one embodiment of the present invention.

FIG. 14 is a schematic block diagram for explaining setting of a gain when the declination detection point is fixed in the vehicle automatic steering apparatus as one embodiment of the present invention, and is a diagram corresponding to FIG. 13; It is.

FIG. 15 is a diagram for describing an effect of the vehicle automatic steering system as one embodiment of the present invention, and is a diagram illustrating an example of a curved road.

16A and 16B are diagrams illustrating an effect of the vehicle automatic steering apparatus as one embodiment of the present invention, wherein FIG. 16A is a diagram illustrating a steering angle characteristic during a curved road running during automatic steering and driver steering. (B) is a graph showing the characteristics of the lateral acceleration of the vehicle when traveling on a curved road during automatic steering and during driver steering.

FIG. 17 is a diagram for explaining an effect of the vehicle automatic steering device as one embodiment of the present invention, and illustrates a lateral acceleration peak value and a lateral jerk peak value during automatic steering and driver steering. 5 is a graph showing the relationship of FIG.

FIG. 18 is a diagram for explaining an example of recognition of a reference line on a road in the automatic steering device for a vehicle as one embodiment of the present invention, wherein FIG. 18A is taken in for recognition of the reference line; FIG. 3B is a diagram illustrating image information, FIG. 3B is a diagram illustrating an example of a case where a reference line is correctly recognized based on FIG.
FIG. 9 is a diagram illustrating an example of a case where a reference line has not been correctly recognized based on.

FIG. 19 is a schematic diagram showing an example of the overall configuration of a steering actuator in an automatic steering device for a vehicle as one embodiment of the present invention.

FIG. 20 is a graph for explaining another example of setting the front gaze distance in the vehicle automatic steering system as one embodiment of the present invention, and is a graph corresponding to FIG. 10;

FIG. 21 is a diagram for describing setting of a deflection angle gain in the automatic steering device for a vehicle as one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle 2 Steering wheel 2A Steering actuator 3 Camera as imaging means 3A Vehicle center 4 Image information processing means 4A Original image 4B Planar view image 4C Image conversion means 5 Controller as control means 5A Steering angle setting part 5B Steering start distance setting part Reference Signs List 5C Steering speed setting unit 5D Adder 6 Deflection calculating means 7 Lateral deviation calculating means 8 Road center 9 Curvature state estimating means 10 White line search area 11 Horizontal line 12 White line as road reference line 14 Guard rail 15, 15A to 15D White line candidate point 16 Vehicle speed detecting means 20 Steering wheel 103 Steering force transmission system 104 Power steering mechanism 104A Hydraulic cylinder 106 Mode switching valve device 107 Automatic steering control valve 110 Oil pump 111 Oil tank 112 Divide valve 113 Relief valve 115 EPS Lube 122 electric motor 120 position detecting sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B62D 117: 00 B62D 117: 00 137: 00 137: 00 (72) Inventor Toshiya Maho 5-33-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Kiichi Yamada 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (56) References JP 4-273301 (JP, A) JP Hei 3-113513 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62D 6/00 G05D 1/02

Claims (8)

(57) [Claims] 1. A steering actuator for steering a steered wheel of a vehicle, an imaging unit for imaging a road ahead of the vehicle, an image information processing unit for processing image information from the imaging unit, and the image information processing unit based on the processing information from the set target steering angle and a control means for controlling driving of the steering actuator so this target steering angle is obtained, a road to which the image information processing unit is obtained from the image information Information close to the above vehicle
Lateral deviation calculating means for calculating a lateral deviation of the vehicle with respect to a reference line of the road based on the first reference position; and the first reference position of road information obtained from the image information.
A deflection angle calculating means for calculating a deflection angle of the vehicle with respect to a road direction ahead of the vehicle based on a second reference position in front of the vehicle relative to the vehicle position; An automatic steering apparatus for a vehicle, wherein the target steering angle is set such that both the lateral deviation and the argument are reduced based on information from the argument calculating means. 2. The method according to claim 1, wherein the control means calculates a curve radius of the road based on the declination.
Including the curve radius and the lateral deviation
The vehicle automatic steering apparatus according to claim 1, wherein the target steering angle is set based on the following . 3. A vehicle speed detecting means for detecting a vehicle speed of the vehicle, wherein the declination calculating means receives information from the vehicle speed detecting means, and at a point separated from the vehicle by a distance corresponding to the vehicle speed. characterized in that it is configured to calculate the polarization angle, automatic steering apparatus for a vehicle according to claim 1. 4. The method according to claim 1, wherein the declination calculating means includes a first road surface information separated from the vehicle by a predetermined distance among road surface information obtained from the image information.
Is set so as to calculate the declination from reference line position information at a point and a reference line position information at a second point further away from the vehicle than the first point. to, automatic steering apparatus for a vehicle according to claim 1. 5. The vehicle automatic steering system according to claim 4, wherein the first point is a point closest to the vehicle in road surface information obtained from the image information. 6. A vehicle speed detecting means for detecting a vehicle speed of the vehicle, wherein the second point is a point separated from the vehicle by a distance corresponding to the vehicle speed based on information from the vehicle speed detecting means. 6. The automatic steering device for a vehicle according to claim 5, wherein: 7. A steering actuator for turning a steered wheel of a vehicle, an imaging unit for imaging a road ahead of the vehicle, an image information processing unit for processing image information from the imaging unit, and a vehicle speed of the vehicle. Vehicle speed detecting means for detecting, and control means for setting a target steering angle based on processing information from the image information processing means, and controlling driving of the steering actuator so as to obtain the target steering angle. The image information processing means includes a declination calculation means for calculating a declination β at a point separated by a predetermined distance K from the vehicle using road surface information obtained from the image information, and the control means is stored in advance. From the stability factor A and the wheelbase WB of the vehicle, the vehicle speed V obtained from the vehicle speed detecting means, the distance K, and the declination β, δ =
An automatic steering apparatus for a vehicle, wherein a target steering angle δ is set based on a relational expression of (1 + AV ² ) · (WB / K) · β. 8. An automatic steering apparatus for a vehicle according to claim 7, wherein said predetermined distance K is given as a function of a vehicle speed of said vehicle.