JP3255052B2 - Vehicle steering control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering control device, and more particularly to a vehicle steering control device that recognizes a traveling road from an image ahead of the vehicle and performs steering control so as not to deviate from the traveling road.

[0002]

2. Description of the Related Art Conventionally, a vehicle position with respect to a traveling road to be traveled has been detected from an image of a road ahead of the vehicle. For example, Japanese Patent Application Laid-Open No. 7-105498 discloses a method in which a white line or the like is detected from an image of a road ahead of a vehicle to detect a side edge of a traveling road of the own vehicle, and a traveling route of the own vehicle is determined based on a vehicle speed and a steering angle. It is described that an estimated angle and a distance to an intersection between the estimated traveling path and a side edge of the traveling path are obtained, and a corrective steering is performed to predict a deviation from the traveling path and prevent the deviation. .

[0003]

In the conventional apparatus, an intervention start point is provided in the left and right direction at a predetermined distance (front gazing distance) from the vehicle, and when the intervention start point is on the side edge of the road, the steering control is started. are doing. However, when the traveling path is sharply curved, the side edge of the traveling path cannot be detected just ahead of the gazing point distance.
There is a problem that the relationship between the estimated traveling path and the side edge of the traveling path becomes unclear, the steering control amount cannot be obtained, and the steering control becomes impossible.

[0004] The present invention has been made in view of the above points,
An object of the present invention is to provide a steering control device for a vehicle that can perform steering control in the same manner as a straight road even when the running road is curved, by varying the distance of the point of gazing ahead in accordance with the radius of curvature of the running road.

[0005]

According to the first aspect of the present invention, as shown in FIG. 1, a guide line recognizing means M1 for recognizing a guide line on a traveling path of a vehicle is provided. Based on the recognition result, a target position is set on a traveling road ahead of the vehicle by a gazing point distance ahead of the vehicle, and a steering control device of the vehicle that performs steering control so as to travel at the target position has a curvature of a traveling road where the vehicle is traveling. The curvature detecting means M3 for detecting the radius , the smaller the detected radius of curvature is, the smaller the front fixation point distance is.
And a forward fixation point distance varying means M4 which varies as described above.

As described above, the smaller the radius of curvature of the traveling road, the smaller the radius of curvature.
It is necessary to change the above
Because, can be set so that the target position is not out of the running path, this
This makes it possible to obtain the steering control amount and perform steering control, and also to prevent a sudden change in the steering control amount by gradually reducing the forward fixation distance when proceeding from a straight road to a curve,
Drivability is improved.

[0007]

FIG. 2 is a block diagram showing an embodiment of the apparatus according to the present invention. In FIG. 1, a front wheel steering mechanism 10 has a steering handle 11, and the steering handle 11 is a steering shaft 12.
Is connected to a pinion gear in the steering gear box 13. This pinion gear is rack bar 1
4, and converts the rotational motion of the steering handle 11 into a reciprocating motion of the rack bar 14 for transmission. Left and right front wheels F are connected to both ends of the rack bar 14 via left and right tie rods 15a and 15b and left and right knuckle arms 16a and 16b.
W1 and FW2 are steerably connected.

The rear wheel steering mechanism 20 has an electric motor 21 such as a brushless motor as an actuator for steering the rear wheels. The rotating shaft of the electric motor 21 is connected to a relay rod 23 supported in a steering gear box 22 via a speed reduction mechanism so as to be displaceable in the axial direction, and the relay rod 23 rotates in accordance with the rotation of the motor 21. Displace in the direction. The reverse efficiency of the speed reduction mechanism is set small, so that the electric motor 21 is not driven to rotate by an external input from the relay rod 23 side. At both ends of the relay rod 23, tie rods 24a,
The left and right rear wheels RW1 and RW2 are connected via the knuckle arms 25a and 25b.
1, RW2 is steered according to the axial displacement of the relay rod 23.

A front wheel steering angle sensor 32, a rear wheel steering angle sensor 34, and a guideline recognition device 36 are connected to an electronic control circuit (ECU) 30. Front wheel steering angle sensor 3
2 detects the steering angles of the left and right front wheels FW1 and FW2. The rear wheel steering angle sensor 34 detects the steering angles of the left and right rear wheels RW1, RW2.

A guide line recognizing device 36 serving as a guide line recognizing means M1 and a curvature detecting means M3 is supplied from a camera 38 with a road image obtained by imaging a road ahead in the traveling direction of the vehicle. Recognizing guidelines such as white lines and yellow no-pass lines,
The travel lane is recognized based on these guidelines, and the vehicle offset amount E from the travel road center line indicated by a broken line in FIG.
(N) and distance L ₁ from guideline I indicated by double line
And the radius of curvature R of the curve of the traveling path is detected. Here, θ is the inclination angle of the vehicle with respect to the traveling path obtained from the image, 1 is the distance of the front fixation point (constant value), e is the current lateral shift amount, and E (n) = e + L ₁ (1) L ₁ ≒ 1 × θ (2) The above-described tilt angle θ, current lateral displacement amount e, vehicle offset amount E (n), and radius of curvature R are supplied to the ECU 30.

The electronic control unit 30 comprises a microcomputer as shown in FIG.
U) 50, a read only memory (ROM) 52, a random access memory (RAM) 54, an input port circuit 56, an output port circuit 58, and a communication circuit 60, which are a bidirectional common bus. They are connected to each other by 62.

The input port circuit 56 is supplied with detection signals output from the front wheel steering angle sensor 32 and the rear wheel steering angle sensor 34, respectively. Further, the detection amounts θ, e, E (n), and R output from the guideline recognition device 36 are supplied to the communication circuit 60. A control program is stored in the ROM 52. The CPU 50 performs various operations to be described later based on the control program, and at that time, the RAM 54 is used as a work area. A control signal generated by the CPU 50 executing the control program is supplied from the output port circuit 58 to the drive circuit 40. The drive circuit 40 drives the electric motor 21 to steer the rear wheels RW1, RW2.

FIG. 5 shows a flowchart of one embodiment of the steering control process as the steering control means M2 executed by the CPU 30. This process is repeated at predetermined time intervals. In the figure, in a step S12, it is determined whether or not the guideway recognizing device 36 can recognize the traveling path. If the travel path can be recognized, the process proceeds to step S14; otherwise, the processing cycle ends.

In step S14, the inclination angle θ, the current lateral shift amount e, the vehicle offset amount E (n), and the curvature radius R output from the guide line recognition device 36 are read. Then calculates the forward observation point distance l ₁ with reference to the map shown in FIG. 6 at step S16 as forward observation point distance varying means M4 with a radius of curvature R of the above. In the map of FIG.
Is larger, that is, as the traveling path is closer to a straight line, the front fixation point distance l ₁ is increased (however, the front fixation point distance l ₁
Does not exceed the fixed value l), and the smaller the radius of curvature R, that is, the steeper the curve of the traveling road, the smaller the distance 1 of the forward fixation point.

Next, at step S18, the vehicle offset E '(n) is calculated by the following equation. E ′ (n) = e + L ′ ₁ (3) L ′ ₁ ≒ l ₁ × θ (4) In the guideline recognition device 36, the vehicle offset amount E ( n) is calculated and output. Since the forward fixation point distance 1 in the equation (2) is a constant value,
In this step, the vehicle offset E ′ (n) is calculated using the forward fixation point distance l ₁ corresponding to the curvature radius R of the curve.

Next, in step S20, a rear wheel steering control amount D (n) is calculated by the following equation. D (n) = D (n−1) + K1 × {E ′ (n) −E ′ (n−1)} (1) where D (n−1) is the previous rear wheel steering control amount , E '(n
-1) is the previous vehicle offset amount, and K1 is the rear wheel control gain (constant value).

In step S22, the rear wheel steering control amount D (n) calculated in step S18 is replaced with the actual rear wheel steering control amount D
Then, the process proceeds to step S24 to drive the drive circuit 40 based on the actual rear wheel steering control amount D. As a result, the electric motor 21 is driven to rotate and the rear wheels RW1, RW2
Steering is performed. Thereafter, the process ends.

As described above, the smaller the radius of curvature R of the traveling path, the smaller the distance L _{1 in the} point of gaze at the front.
In the sharply curved traveling path 70 as shown in the figure, the forward fixation distance l ₁ of the vehicle 72 becomes smaller than the fixed value l, and the vehicle offset amount E ′ (n) does not go outside the traveling path.
, Whereby the rear wheel steering control amount D
The steering control can be performed by calculating (n).

Also, as shown in FIG.
Gaze forward in the vehicle 72 when changes from a straight line to a curve
Point distance l₁Indicates that the radius of curvature R of the traveling path 74 gradually decreases with time.
Because the distance becomes smaller,₁Over time
Become smaller. That is, l₁(T ₀)> L₁(T_n) And
You. As a result, the vehicle offset amount E '(n) becomes a curve.
Vehicle offset with almost no effect
Abrupt change in E '(n) can be prevented, and abrupt change in steering control amount can be prevented.
Therefore, running of the vehicle 72 does not become unstable.
And the tribability is improved.

In the above-described embodiment, the radius of curvature R of the traveling road is detected by the guideline recognition device 36. Alternatively, the radius of curvature R may be obtained from the front wheel steering angle or the yaw rate. The radius of curvature may be obtained from the information. Also, instead of steering control of the rear wheels, it may be one that controls the front wheels or the front wheels and the rear wheels,
It is not limited to the above embodiment.

[0021]

As described above, the first aspect of the present invention provides
The smaller the radius of curvature of the traveling path, the smaller
The target position is outside the travel path
Can be set so that the steering control amount is determined.
Steering control, and from a straight road
When proceeding to a curve, gradually reduce the
Prevents sudden changes in rudder control and improves drivability
You.

[0022]

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of the device of the present invention.

FIG. 3 is a block diagram of an ECU.

FIG. 4 is a diagram for explaining a vehicle offset amount.

FIG. 5 is a flowchart of a steering control process.

FIG. 6 is a diagram showing a map.

FIG. 7 is a diagram for explaining the present invention.

[Explanation of symbols]

 Reference Signs List 10 front wheel steering mechanism 11 steering handle 12 steering shaft 13, 22 steering gear box 14 rack bar 15a, 15b, 24a, 24b tie rod 16a, 16b, 25a, 25b knuckle arm 20 rear wheel steering mechanism 21 electric motor 23 relay rod 30 ECU 32 Front wheel steering angle sensor 33 Rear wheel steering angle sensor 36 Guideline recognition device 38 Camera 40 Drive circuit M1 Guideline recognition means M2 Steering control means M3 Curvature detection means M4 Forward fixation distance variable means

Continuation of the front page (56) References JP-A-6-300580 (JP, A) JP-A-7-105498 (JP, A) JP-A-7-81603 (JP, A) JP-A-6-289139 (JP) , A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B62D 6/00

Claims (1)

(57) [Claims] 1. A guide line recognizing means for recognizing a guide line on a traveling path of a vehicle, wherein a target position is set on a traveling path ahead of the vehicle by a distance of a gazing point ahead based on a recognition result of the guide line. in the steering control apparatus for a vehicle which performs steering control so as to travel, and curvature detection means for detecting the radius of curvature of the traveling path of the traveling of the vehicle, as detected by said radius of curvature is smaller above the forward fixed point distance
And a front-point-of-regard distance varying unit that varies so as to reduce the separation .