JPH10167098A - Vehicle steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle steering control device performing appropriate steering control matching the traveling conditions of a vehicle by changing steering control characteristics according to the traveling conditions, although devices of the prior art cannot perform appropriate control because a controlled variable becomes too great at the increased vehicle speed and too small at a sharp curve of a small radius. SOLUTION: This device has a vehicle traveling condition detecting means M3 for detecting the traveling conditions of a vehicle and a control characteristic changing means M4 for changing steering control characteristics according to the detected traveling conditions of the vehicle. Thus by detecting the traveling conditions of the vehicle and changing the steering control characteristics according to the traveling conditions, steering control can be performed at an appropriate controlled variable matching the traveling conditions.

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 for recognizing a traveling road from an image ahead of the vehicle and performing steering control so as not to deviate from the traveling road.

[0002]

2. Description of the Related Art Conventionally, for the purpose of driving a vehicle stably, a guideline such as a white line on a road is recognized to recognize a travel path of an own vehicle, and steering control is performed so as not to deviate from the travel path. 2. Description of the Related Art A steering control device for a vehicle has been proposed. For example, Japanese Patent Application Laid-Open No. 6-255514 discloses that a white line on a road is recognized, and based on the white line recognition information, the stable traveling potential energy is set low at the center of the traveling lane inside the white line, and the white line is displayed near the white line. The document describes that the rear wheel steering control is performed so that the vehicle is set to be higher as the vehicle approaches, and the vehicle is moved to a side where the safe traveling potential energy becomes lower as the stable traveling potential energy becomes higher.

[0003]

In the conventional device, the stable traveling potential energy is determined only by the distance from the white line of the road. Therefore, when the vehicle approaches the white line and the stable traveling potential energy becomes higher, the stable traveling potential energy becomes higher. The steering control of the rear wheels for moving the vehicle to the lower side, that is, the center side of the traveling lane is performed. However, this steering control does not consider any change in the vehicle speed or the radius of curvature of the road (curve R). Therefore, when the vehicle speed increases, the control amount is too large, and when the curve R is small, the control amount is small. There was a problem that proper control could not be performed.

[0004] The present invention has been made in view of the above points,
An object of the present invention is to provide a vehicle steering control device that performs appropriate steering control according to a traveling condition by changing a control characteristic of steering control according to a traveling condition of the vehicle.

[0005]

According to the present invention, as shown in FIG. 1, there is provided a guide line recognizing means M1 for recognizing a guide line on a traveling path of a vehicle, based on the recognition result of the guide line. In a vehicle steering control device that sets a target position on a traveling road with the steering control means M2 and performs steering control so as to travel at the target position, a vehicle running state detecting means M3 for detecting a running state of the vehicle; Control characteristic changing means M4 for changing the control characteristic of the steering control based on the traveling state of the vehicle.

As described above, by detecting the running condition of the vehicle and changing the control characteristics of the steering control according to the running condition, it is possible to perform the steering control with an appropriate control amount according to the running condition. According to a second aspect of the present invention, in the vehicle steering control device according to the first aspect, the traveling state of the vehicle is a vehicle speed, and the control characteristic changing means controls the control amount to decrease as the vehicle speed increases. Change the gain.

For this reason, it is possible to prevent the control amount from becoming excessive when the vehicle speed is high, and to perform appropriate steering control in all vehicle speed ranges. The invention described in claim 3 is the invention according to claim 1.
In the vehicle steering control device according to the second aspect, the traveling condition of the vehicle is a radius of curvature of a traveling path, and the control characteristic changing unit changes the control gain so that the control amount decreases as the radius of curvature increases.

[0008] For this reason, even in a sharp curve with a small radius of curvature of the traveling path, it is possible to prevent the control amount from becoming too small and to perform appropriate steering control at all the radii of curvature.

[0009]

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 includes 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.

An electronic control circuit (ECU) 30 includes a front wheel steering angle sensor 32, a rear wheel steering angle sensor 34, and a vehicle speed sensor 3.
5, and the guideline recognition device 36 are connected.
The front wheel steering angle sensor 32 detects the steering angles of the left and right front wheels FW1 and FW2. The rear wheel steering angle sensor 34 is provided for the left and right rear wheels RW.
1, the steering angle of RW2 is detected. Traveling condition detecting means M3
The vehicle speed sensor 35 detects the vehicle speed of the own vehicle.

A guide line recognizing device 36 serving as a guide line recognizing means M1 and a driving situation 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 a roadside white line and a yellow no-passing line, the traveling lane is recognized based on these guidelines, and the vehicle offset E from the traveling road centerline 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.

As shown in FIG. 3, the electronic control unit 30 is constituted by a microcomputer and has a central processing unit (CP).
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, the rear wheel steering angle sensor 34, and the vehicle speed sensor 35. In addition, the communication circuit 60 has a detection amount θ, e, E output from the guideline recognition device 36.
(N) and R are supplied. A control program is stored in the ROM 52. The CPU 50 performs various operations to be described later based on the control program.
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 drive the rear wheels RW1, RW
Steering 2 is performed.

FIG. 5 shows a flowchart of a first embodiment of a steering control process executed by the CPU 30 as the steering control means M2. 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 vehicle offset amount E (n) output from the guideline recognition device 36, the curvature radius R (curve R) of the traveling road, and the vehicle speed V output from the vehicle speed sensor 35 are read. Next, in step S16, the control gain Kpv is calculated by referring to the map shown by the solid line in FIG.
To calculate the control gain Kdv. The control gain Kpv is a value that decreases as the vehicle speed V increases, and the control gain Kdv is a value that increases as the speed V increases.

Thereafter, the process proceeds to step S18, where a rear wheel steering control amount D (n) is calculated by the following equation. D (n) = Kpv × E (n) + Kdv × {E (n) −E (n−1)} (3) where E (n−1) is the previous vehicle offset amount.
That is, when the vehicle speed V is high, the vehicle offset amount E
Although the component (m) is reduced, the component corresponding to the change in the vehicle offset amount is increased, and the responsiveness of the control is increased.

Steps S16 and S18 correspond to the control characteristic changing means M4. In step S20, the rear wheel steering control amount D (n) calculated in step S18 is set to the actual rear wheel steering control amount D, and the process proceeds to step S22, where the drive circuit 40 is controlled based on the actual rear wheel steering control amount D. Drive. Thus, the electric motor 21 is driven to rotate, and the rear wheels RW1, RW2 are steered. Thereafter, the process ends.

As described above, by changing the control amount and its response in accordance with the vehicle speed, it is possible to perform the optimal steering control corresponding to the vehicle speed, and the vehicle stability is high and the drivability is improved. FIG. 7 shows a flowchart of a second 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 S32, it is determined whether or not the guideway recognition device 36 has recognized the traveling path. If the travel path can be recognized, the process proceeds to step S34; otherwise, the processing cycle ends.

In step S34, the vehicle offset amount E (n) output from the guideline recognition device 36, the curvature radius R (curve R) of the traveling road, and the vehicle speed V output from the vehicle speed sensor 35 are read. Next, in step S36, the control gain Kpr is calculated by referring to the map shown by the solid line in FIG. 8 with the curve R, and the control gain Kdr is calculated by referring to the map shown by the dashed line with the curve R. The control gains Kpr and Kdr are values that increase as the curve R becomes smaller and become steeper, and decrease as the curve R becomes larger.

Thereafter, the process proceeds to step S38, where a rear wheel steering control amount D (n) is calculated by the following equation. D (n) = Kpr × E (n) + Kdr × {E (n) −E (n−1)} (4) That is, when the curve R is large, the vehicle offset amount E is obtained.
The component (n) is reduced, the component corresponding to the change in the vehicle offset amount is reduced, and the responsiveness of the control is reduced.

The above steps S36 and S38 correspond to the control characteristic changing means M4. In step S40, the rear wheel steering control amount D (n) calculated in step S38 is set to the actual rear wheel steering control amount D, and the routine proceeds to step S42, where the drive circuit 40 is controlled based on the actual rear wheel steering control amount D. Drive. Thus, the electric motor 21 is driven to rotate, and the rear wheels RW1, RW2 are steered. Thereafter, the process ends.

As described above, by changing the control amount and its response in accordance with the curve R, it is possible to perform the optimum steering control corresponding to the curve R, and the vehicle stability is high and the drivability is improved. . FIG. 9 shows a third example of the steering control process performed by the CPU 30 as the steering control unit M2.
4 shows a flowchart of an embodiment. This process is repeated at predetermined time intervals. In the figure, in a step S52, it is determined whether or not the travel path is recognized by the guideline recognition device 36. If the travel path can be recognized, step S5
The process proceeds to step 4, and if not recognized, the processing cycle ends.

In step S54, the vehicle offset amount E (n) output from the guideline recognition device 36, the radius of curvature R (curve R) of the traveling road, and the vehicle speed V output from the vehicle speed sensor 35 are read. Next, in step S56, the control gains Kpv and Kpr are calculated by referring to the maps indicated by the solid lines in FIGS. 6 and 8 using the vehicle speed V and the curve R, respectively, and the maps indicated by the broken lines are referred to by the speed V and the curve R. Thus, the control gains Kdv and Kdr are calculated.

Thereafter, the process proceeds to step S58, where a rear wheel steering control amount D (n) is calculated by the following equation. D (n) = Kp × E (n) + Kd × {E (n) −E (n−1)} (5) where Kp = (Kpv + Kpr) / 2 and Kd = (Kdv
+ Kdr) / 2.

The above steps S56 and S58 correspond to the control characteristic changing means M4. In step S60, the rear wheel steering control amount D (n) calculated in step S58 is set to the actual rear wheel steering control amount D, and the process proceeds to step S62 to drive the drive circuit 40 based on the actual rear wheel steering control amount D. Drive. Thus, the electric motor 21 is driven to rotate, and the rear wheels RW1, RW2 are steered. Thereafter, the process ends.

As described above, by changing the control amount and its response in accordance with the vehicle speed and the curve R, it is possible to perform the optimum steering control corresponding to the vehicle speed and the curve R, and the vehicle stability is high and the driver is improved. The ability is improved. In the above embodiment, the guideline recognition device 36 detects the radius of curvature R of the traveling road. Alternatively, the radius of curvature R may be obtained from the front wheel steering angle and the yaw rate. You may get the radius. Further, instead of steering control of the rear wheel, steering control of the front wheel or the front wheel and the rear wheel may be performed, and the present invention is not limited to the above embodiment.

[0028]

As described above, the first aspect of the present invention provides
As shown in FIG. 1, the vehicle has a guideline recognizing means for recognizing a guideline on a traveling road of a vehicle, sets a target position on the traveling road based on the recognition result of the guideline, and performs steering control so as to travel at the target position. The vehicle steering control device includes a vehicle running condition detecting unit that detects a running condition of the vehicle, and a control characteristic changing unit that changes a control characteristic of the steering control based on the detected running condition of the vehicle.

As described above, by detecting the running condition of the vehicle and changing the control characteristics of the steering control according to the running condition, it becomes possible to perform the steering control with an appropriate control amount according to the running condition. According to a second aspect of the present invention, in the vehicle steering control device according to the first aspect, the traveling condition of the vehicle is a vehicle speed, and the control characteristic changing unit decreases the control amount as the vehicle speed increases. Change the control gain as follows.

Therefore, it is possible to prevent the control amount from becoming excessive when the vehicle speed is high, and to perform appropriate steering control in all vehicle speed ranges. The invention described in claim 3 is:
3. The vehicle steering control device according to claim 1, wherein the traveling condition of the vehicle is a radius of curvature of a traveling path, and the control characteristic changing unit changes the control gain so that the control amount decreases as the radius of curvature increases. .

Therefore, even in a sharp curve with a small radius of curvature of the traveling road, it is possible to prevent the control amount from becoming too small and to perform appropriate steering control at all the radii of curvature.

[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 flowchart of a steering control process.

FIG. 8 is a diagram showing a map.

FIG. 9 is a flowchart of a steering control process.

[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 34 Rear wheel steering angle sensor 35 Vehicle speed sensor 36 Guideline recognition device 38 Camera 40 Drive circuit M1 Guideline recognition means M2 Steering control means M3 Running state detection means M4 Control characteristic changing means

Claims (3)

[Claims] 1. A vehicle having a guideline recognizing means for recognizing a guideline on a traveling path of a vehicle, setting a target position on the traveling path based on the recognition result of the guideline, and performing a steering control to travel the target position. The steering control device according to claim 1, further comprising: a vehicle traveling condition detecting unit that detects a traveling condition of the vehicle; and a control characteristic changing unit that changes a control characteristic of the steering control based on the detected traveling condition of the vehicle. Vehicle steering control device. 2. The vehicle steering control device according to claim 1, wherein the traveling condition of the vehicle is a vehicle speed of the vehicle, and the control characteristic changing unit changes a control gain so that the control amount decreases as the vehicle speed increases. A steering control device for a vehicle, comprising: 3. The steering control device for a vehicle according to claim 1, wherein the traveling condition of the vehicle is a radius of curvature of a traveling path, and the control characteristic changing unit decreases the control amount as the radius of curvature increases. A vehicle steering control device for changing a control gain.