JP3493921B2 - Vehicle steering control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a vehicle steering control device, and more particularly to a vehicle steering control system 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. The present invention relates to a vehicle steering control device. 2. Description of the Related Art Conventionally, for the purpose of driving a vehicle safely, a guideline such as a white line on a road is recognized to recognize a travel path of a vehicle, and steering is performed so as not to deviate from the travel path. 2. Description of the Related Art A steering control device for a vehicle that performs control has been proposed. For example, Japanese Unexamined Patent Publication No. 5-294250 discloses that when a driver operates a turn signal, the presence or absence of a rear vehicle on the moving side due to an operation deviating from a traveling path on which the vehicle travels is detected. Alerts you when there is a vehicle behind you,
It also describes that steering control is performed so that the vehicle travels while maintaining the traveling path on which the vehicle is traveling when there is no direction instruction operation by the driver. [0004] When the course is corrected by steering control of the front wheels, when a large course deviation occurs due to cross wind or the like, the control amount per unit time of the steering control of the front wheels also becomes large, and the steering wheel is controlled. The reaction force is also greater. For this reason, it gives the driver a sense of incongruity, and unintentionally generates a steering force in the opposite direction or a corrected steering force in response to the reaction force,
In some cases, automatic steering for course correction and driver's steering operation interfere with each other. [0005] Further, when the course is corrected by the steering control of the rear wheel, if the steering of the rear wheel is controlled by the course deviation such as the crosswind, the interference with the driver's steering does not occur in the initial stage of the steering control. However, if the driver steers the front wheels during steering control for course correction and the course of the vehicle is parallel to the guideline in the state where the front wheels are steered, the steering amount of the rear wheels is reduced. It remains with the amount of front wheel steering.
That is, if the vehicle goes straight in parallel with the guideline with the front wheels turned left, the rear wheels are also turned left, and the vehicle body leans to the right (crab running). When the steering wheel is returned to the neutral position in this state, the vehicle turns right.
Also, in this state, if it becomes necessary to correct the course of turning the rear wheel to the left, the steering control amount of the rear wheel will be further increased, exceeding the rear wheel steering range, and the steering control amount will be limited. There is a problem that the course correction becomes insufficient. [0006] The present invention has been made in view of the above points,
A vehicle capable of performing steering control without giving the driver an uncomfortable feeling and without interfering with the driver's steering operation by additionally performing the steering control of the rear wheel so that the steering control amount of the front wheel does not exceed a predetermined value. It is an object of the present invention to provide a steering control device. [0007] According to an aspect of the invention according to claim 1, as shown in Figure 1, has a recognized guidelines recognizing means M1 guidelines traveling path of the vehicle, the recognition of the Guidelines A steering control device for a vehicle that performs steering control to move the vehicle to a target position on a traveling road based on the result; When the steering control amount of the front wheel exceeds a predetermined value, a second calculating means M3 for calculating again the steering control amount of the front wheel and the steering control amount of the rear wheel so as not to exceed the predetermined value; and control means M4 for performing steering of the front wheels or the front and rear wheels based on the steering control amount obtained by the second computing means, [0008] [0009] rear wheel when the vehicle is skewed when steering the helmsman stage as well as Having return means M5 for returning the steering control amount of people wheel respectively in the direction of the steering angle of the rear wheels is zero. For this reason, even when the driver operates the steering wheel during steering control of the rear wheels and the steering direction of the front wheels and the rear wheels becomes the same direction and the vehicle leans, the steering angle of the rear wheels is returned to zero. Therefore, the vehicle can go straight after getting out of the skew. FIG. 2 is a block diagram showing an embodiment of the apparatus according to the present invention. In the figure, the front wheel steering mechanism is a steering wheel 11.
The steering wheel 11 is connected to a pinion gear in a steering gear box 13 via a steering shaft 12. This pinion gear meshes with the rack bar 14 to rotate the steering handle 11 in rotation.
This is converted into a reciprocating motion and transmitted. Left and right front wheels are steerably connected to both ends of the rack bar 14 via left and right tie rods and left and right knuckle arms. Also,
An electric motor 15 is provided as an actuator for steering control of the front wheels. The rotation shaft of the electric motor 15 is connected to a pinion gear in the steering gear box 16, and the pinion gear meshes with the rack bar 14. The rear wheel steering mechanism 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. Right and left rear wheels are connected to both ends of the relay rod 23 via tie rods and knuckle arms, and the left and right rear wheels are steered according to the axial displacement of the relay rod 23. An electronic control circuit (ECU) 30 includes a steering angle sensor 32, a steering torque sensor 33, a vehicle speed sensor 34, a guideline recognition device 36, and electric motors 15, 2.
1, a display unit 40 and an alarm unit 41 are connected. The steering angle sensor 32 detects the steering angles of the left and right front wheels. The steering torque sensor 33 detects the steering torque of the steering wheel 11. The vehicle speed sensor 34 detects the speed of the vehicle. A guide line recognizing device 36 as a guide line recognizing means M1 is supplied from a camera 38 with a road image obtained by photographing a road ahead in the traveling direction of the vehicle. The road image is processed and white lines or yellow lines at the center or road side of the road are processed. Recognizing the guideline such as the no-passing line, the traveling lane is recognized based on the guideline, and the vehicle offset E (n) from the center line of the traveling road indicated by a broken line in FIG. detecting the inclination angle theta _S respectively for the distance L ₁ and the travel path of the vehicle obtained from the image. Where 1
Is the forward fixation point distance (constant value), e is the current lateral shift amount, and is expressed as E (n) = e + L ₁ L ₁ ≒ 1 × θ. The vehicle offset E (n), the tilt angle theta _S is 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. They are connected to each other by 62. The input port circuit 56 includes the steering angle sensor 3
2. Detection signals output from the steering torque sensor 33 and the vehicle speed sensor 34 are supplied. The communication circuit 60 also has a vehicle offset amount E output from the guideline recognition device 36.
(N) and the inclination angle θ _S are supplied. The ROM 52 stores a control program. 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 circuits 42 and 43. Drive circuits 42, 4
Each of the three drives the electric motors 15 and 21 to perform steering control of the front wheels and the rear wheels, respectively. In addition, the CPU 50 displays the state of the steering control on the display unit 40, and issues an alarm from the alarm unit 41 when the vehicle is likely to deviate from the traveling path regardless of the steering control. FIG. 5 shows a flowchart of one embodiment of the steering control process executed by the CPU 30. This process is repeated at predetermined time intervals. In the figure, to read the vehicle offset E (n) and the inclination angle theta _S supplied from the step S10 Guideline recognition device 36, the E (n),
vehicle from theta _S whether trying to deviate from the travel path currently traveling, to determine whether that is in need of steering control. Here, if the deviation of the traveling road is not predicted, step S10 is repeated, and if the deviation of the traveling road is predicted, the process proceeds to step S12. Step S1 as the first calculating means M2
In step 2, a required correction steering control amount by steering only the front wheels is calculated. Here, a course correction time T0 and an allowable correction steering angular velocity H0 are provided as constraints on the calculation of the steering control amount. Normally, the course correction time T0 is a look-ahead time (2 to 3 seconds) relating to driving that the driver has. This is 2-3
About 50 to 70% of the prediction before 2 seconds is considered appropriate. The permissible corrected steering angular velocity H0 is an angular velocity on the periphery of the steering wheel at which the response of the steering wheel by the front wheel steering control given to the driver is felt as uncomfortable. Is considered appropriate. The steering control of the front wheels is performed so that the steering control amount has a sine wave shape under these two constraints. In step S12, as shown in FIG. 6A, the current vehicle offset amount E ( n), the inclination angle θ _S, and the course correction time, as shown in FIG.
(B) A sine wave shaped steering control amount Mf (Mf
Is a function of time. Next, in step S14, it is determined whether or not the maximum value Mfmax of the steering control amount Mf as shown in FIG. 6A exceeds the limit value A0. The limit value A0 is the maximum steering angle when the maximum steering angular velocity is the allowable corrected steering angular velocity H0. Here, if Mfmax ≦ A0, step S12
Since the steering control amount Mf of the front wheel calculated in the above is within the range of the permissible corrected steering angular velocity H0, the process proceeds to step S16, and the steering control of only the front wheel is performed based on the steering control amount Mf. This steering control is repeated until the end is confirmed in step S18, and the processing cycle ends when the end is confirmed. On the other hand, when Mfmax> A0, as shown in FIG. 7, the front wheel steering control amount M calculated in step S12 is calculated.
Since f (solid line VIa) exceeds the permissible corrected steering angular velocity H0 and the response of the steering wheel gives the driver an uncomfortable feeling, the process proceeds to step S20 as the second calculating means M3, and the front wheel such that the maximum value becomes the limit value A0. A steering control amount Mfa (solid line VIb in FIG. 7) and a rear wheel steering control amount Mr (solid line VIc in FIG. 7) are calculated. This calculation calculates the distance from each of the front and rear wheels to the center of gravity,
This is performed based on vehicle specifications such as a stability factor. Here, the front wheel steering control amount Mfa and the rear wheel steering control amount M
The simultaneous control with r corresponds to the control of the steering control amount Mf of only the front wheels. Next, the routine proceeds to step S22, where the steering control amount Mfa
, And the steering control of the rear wheels based on the steering control amount Mr is simultaneously performed. In step S24, it is determined whether or not the above-described steering control has been completed. If not, in step S26, it is determined whether or not the driver has performed steering, that is, whether or not the steering wheel operation has been performed. If the steering has been performed, it is determined in step S28 whether or not the course angle θg is zero. Here, the course angle θg is an angle between the traveling direction of the center of gravity of the vehicle and the guide line, and the vehicle offset amount E
It is obtained by analyzing (n) and the inclination angle θ _S temporally. If .theta.g = 0, the flow advances to step S30 to determine skew. If there is no steering by the driver, or if θg ≠ 0, there is no possibility of skewing, so step S2
Proceed to 2. In step S30, it is determined whether or not the rear wheel / steering angle is zero. Although the rear wheel steering angle uses the steering control amount of the rear wheel as it is, a rear wheel steering angle sensor may be separately provided. Here, if the rear wheel steering angle is not 0, the course angle θg is 0 and the vehicle is traveling obliquely, so the process proceeds to step S32. Since the front wheel and the rear wheel are steered in the same direction in the skew, the rear wheel steering control amount Mr is returned to the direction in which the rear wheel steering angle becomes zero at the angular velocity Hr in step S32. At the same time, the front wheel steering control amount Mfa is changed to the angular speed Hf and the front wheel steering angle becomes zero.
Return to the direction Each of the angular velocities Hr and Hf is set to １ ／ of the allowable corrected steering angular velocity H0. This step S3
After the execution of step 2, the process proceeds to step S30. Step S
If the steering angle of the rear wheel is 0 at 30, the processing cycle ends because the vehicle is traveling straight. The above steps S16, S
20 corresponds to the control means M4, and step S32 corresponds to the return means M5. Here, when the steering control is started with the front wheel steering control amount Mfa as shown by the solid line VIIb in FIG. 8 and the rear wheel steering control amount Mr as shown by the solid line VIIc, the operation is started at time t ₁ . It is assumed that the driver performs the steering operation, and thereby the vehicle 70 skews as shown in FIG. 8B in the period T1. Also in this case, in the period T2, the rear wheel steering control amount and the front wheel steering control amount are returned so that the rear wheel steering angle becomes 0, and the vehicle stops straight and travels straight. Incidentally, the rear wheel steering angle at the time t ₂ is 0, and sometimes became a track angle θg is 0 in a state where the vehicle 70 is not ride on the target line as shown in FIG. 8 (B). However, the skewing is a result of the driver consciously operating the steering wheel, so that there is no problem if the steering control is terminated and the driver operates the steering wheel. As described above, since the steering control amount of the front wheels does not exceed the predetermined value, and thereby the driver does not feel uncomfortable, the driver generates the holding force or the correction steering force in the reverse direction. Therefore, interference between the steering control and the driver's steering operation can be prevented. As described above, the first aspect of the present invention provides
The vehicle steering control device includes a guideline recognizing means for recognizing the guideline on the traveling path of the vehicle, and performs a steering control to move the vehicle to a target position on the traveling path based on the recognition result of the guideline. A first calculating means for calculating a front wheel steering control amount based on the result; and when the front wheel steering control amount exceeds a predetermined value, the front wheel steering control amount and the rear wheel steering are controlled so as not to exceed the predetermined value. A second calculating means for calculating the control amount again, a control means for steering the front wheel or the front and rear wheels based on the steering control amount obtained by the first or second calculating means, [0029] with a return means for returning in the direction in which the steering angle of the rear wheel steering control amount of the rear wheels and front wheels, respectively when the vehicle upon steering of the steering hand stage skewed becomes 0. Therefore, the steering angle of the rear wheels is returned to 0 even when the driver operates the steering wheel during the steering control of the rear wheels and the steering directions of the front wheels and the rear wheels become the same direction and the vehicle leans. Therefore, the vehicle can go straight after getting out of the skew.

[Brief description of the drawings] FIG. 1 is a diagram illustrating the principle 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 for explaining steering control according to the present invention. FIG. 7 is a diagram for explaining steering control according to the present invention. FIG. 8 is a diagram for explaining steering control according to the present invention. [Explanation of symbols] 10 Front wheel steering mechanism 11 Steering wheel 12 Steering axis 13,16,22 Steering gear box 14 rack bar 15,21 Electric motor 20 Rear wheel steering mechanism 23 relay rod 30 ECU 32 Steering angle sensor 33 Steering torque sensor 34 Vehicle speed sensor 36 Guideline Recognition Device 38 Camera 40 Display 41 Alarm section 42, 43 drive circuit M1 guideline recognition means M2 First calculation means M3 Second calculation means M4 control means M5 return means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 6/00-6/06 B62D 7/00-7/20 G08G 1/16

Claims (1)

(57) [Claims 1] A guide line recognizing means for recognizing a guide line on a traveling path of a vehicle, and based on the recognition result of the guide line, steering to move the vehicle to a target position on the traveling path. A first calculating means for calculating a front wheel steering control amount based on the recognition result of the guideline, wherein the first wheel steering control amount exceeds a predetermined value. A second calculating means for recalculating the front wheel steering control amount and the rear wheel steering control amount so as not to exceed, and a front wheel or a front wheel based on the steering control amount obtained by the first or second calculating means. And control means for steering the rear wheels, and a rear wheel and a front wheel when the vehicle leans while steering the steering means.
Each steering control amount is returned to the direction where the steering angle of the rear wheel becomes zero.
A steering control device for a vehicle, comprising : a return unit for causing the vehicle to return .