JP3163990B2 - 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 for recognizing a white line on a road and preventing a vehicle from deviating from a travel lane.

[0002]

2. Description of the Related Art Conventionally, for the purpose of driving a vehicle more safely, a vehicle which recognizes a white lane of a road or the like and recognizes a traveling lane of a vehicle and performs steering control so as not to deviate from the traveling lane. Has been proposed.

For example, Japanese Patent Application Laid-Open No. Hei 4-300781 discloses a method in which an image in front of a road is captured, a white line is detected, a target route to be traveled is recognized based on the white line, and a deviation amount of a vehicle position from the target route is determined. It is disclosed that the steering control is performed based on the steering state calculated and detected and the deviation amount.

[0004]

A guideline such as a white line provided on a road may be provided in parallel depending on the laying condition. For example, a solid line and a dashed line are provided adjacent to and parallel to one another on an overtaking prohibited road. Also, there are places where guidelines are provided in parallel even when roads merge or branch.

As described above, when the guidelines are parallel, a plurality of guidelines are detected in the road image, so that it is difficult to stably recognize the target route. Has become unstable and drivability has been degraded.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and reduces and corrects the rear wheel steering control amount when the amount of change in lane width of a traveling road exceeds a predetermined reference value. It is an object of the present invention to provide a vehicle steering control device that stabilizes the vehicle and improves drivability.

[0007]

According to the present invention, as shown in FIG. 1A, there is provided a guideline recognizing means M1 for recognizing a guideline on a traveling path of a vehicle. Control amount calculating means M2 based on
In the vehicle steering control device that calculates the rear wheel steering control amount and controls the rear wheel steering so that the vehicle travels on the target route, the lane of the traveling road based on the recognition result of the guideline is set. A lane width change detecting means M3 for detecting a change state of the width and a correcting means M4 for reducing and correcting the steering control amount of the rear wheel when the amount of change of the lane width exceeds a predetermined reference value.

For this reason, when the amount of change in the lane width exceeds the reference value and the amount of steering control of the rear wheels greatly changes, the above-described amount of steering control is corrected to decrease, and the steering of the rear wheels is stabilized, and drivability is improved. . The invention described in claim 2 is the one shown in FIG.
As shown in (B), in the vehicle steering control device according to claim 1, when the lane width change state detected by the lane width change detection means M3 is periodic and continues for a predetermined time, the decrease correction by the correction means. Has a correction stopping means M5 for stopping the operation.

For this reason, when the lane width changes at a predetermined cycle on a road that protrudes from one side and does not pass, if the target route is set from the minimum value, the maximum value, or the average value of the lane width, it is not necessary to perform the decrease correction. Driving on the target route is enabled by stable rear wheel steering, and drivability is improved.

[0010]

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 A is a steering wheel 1
The steering wheel 11 is connected to a pinion gear 13 via a steering shaft 12. The pinion gear 13 meshes with a rack bar 14 to control the steering wheel 1.
1 is converted into a reciprocating motion of the rack bar 14 and transmitted. Left and right tie rods 15a, 15b and left and right knuckle arms 16a,
Left and right front wheels FW1 and FW2 are steerably connected via 16b.

Further, the rack bar 14 is driven by the left and right front wheels FW1, FW in accordance with the axial displacement caused by the rotation of the steering handle 11.
Steer 2 A control valve 17 composed of a four-way valve is mounted in the middle of the steering shaft 12. Control valve 17
Supplies hydraulic oil from a hydraulic pump 21 driven by an engine 18 to one oil chamber of a power cylinder 22 in accordance with a steering torque acting on a steering shaft 12.
It functions to discharge the hydraulic oil in the other oil chamber of the power cylinder 22 to the reservoir 23. Power cylinder 22
Assists the steering of the left and right front wheels FW1 and FW2 by driving the rack bar 14 in the axial direction according to the intake and discharge of the hydraulic oil.

The steering torque varying device 25 as the steering torque changing means M6 is a shock absorber (steering damper) for attenuating an impact transmitted directly from the road surface and a vibration of the steering system, and varies an orifice diameter of the shock absorber. Thus, the steering torque is varied by varying the damping coefficient.

The rear wheel steering mechanism B has a relay rod 31 that is displaced in the axial direction and steers the left and right rear wheels RW1 and RW2 similarly to the rack bar 14. The left and right tie rods 32a, 32b and the left and right knuckle arms 33a, 33 are provided at both ends of the relay rod 31, as in the case of the front wheel steering mechanism A.
The left and right rear wheels RW1 and RW2 are steerably connected via b.

The relay rod 31 is axially displaceably supported by a housing 34 supported by the vehicle body. A power cylinder 35 is formed in the housing 34.
The power cylinder 35 drives the relay rod 31 in the axial direction in accordance with the suction and discharge of hydraulic oil.
The left and right oil chambers 35b,
35c. These left and right oil chambers 35b, 3
5c has springs 36a and 36b incorporated therein so as to penetrate the relay rod 31 in a preloaded state, and the springs 36a and 36b urge the relay rod 31 to a neutral position by their elastic force. are doing.

In the housing 34, a spool valve 37 constituting a hydraulic copying mechanism together with the power cylinder 35 is incorporated. The spool valve 37 includes a valve sleeve 37a accommodated in the housing 34 in a liquid-tight and slidable manner in the axial direction, and a valve sleeve 37b fixed to the housing 34. In accordance with the displacement, hydraulic oil from a hydraulic pump 38 driven by the engine 18 is supplied to the left oil chamber 35b of the power cylinder 35, and hydraulic oil in the right oil chamber 35c of the power cylinder 35 is supplied to the reservoir 23.
Discharge to When the valve sleeve 37a is displaced rightward, the spool valve 37 supplies the hydraulic oil from the hydraulic pump 38 to the right oil chamber 35c of the power cylinder 35, and supplies the hydraulic oil in the left oil chamber 35b of the power cylinder 35. Discharge to reservoir 23.

[0016] the right end portion of the valve sleeve 37a has a through hole 37a ₁ is provided, the lever 41 is in the through-holes 37a ₁ are through. The intermediate portion of the lever 41 is provided nodose ridges 41a of the spherical, lever 41 is tilted and slidably engaged with the inner peripheral surface of the through hole 37a ₁ at the outer peripheral surface of the nodular elevations 41a ing. Further, the lower end portion of the lever 41 is slidably fitted in the annular groove 35a ₁ provided on the outer periphery of the piston 35a to be rotatable and vertically, the lever 4
The upper end of 1 is rotatably connected to a pin 42.

Both ends of the pin 42 enter the support holes 34a and 34b provided in the housing 34 so as to be able to advance and retreat and not to rotate. In addition, rack teeth 42
a is formed, and the stepping motor 43 is provided on the rack teeth 42a.
The worm 44 fixed to the rotation shaft of the gear is engaged. In this case, when the step motor 43 rotates clockwise or counterclockwise, the pin 42 is displaced rightward or leftward.

The electronic control circuit (ECU) 50 is connected with a steering torque sensor 51, a rear wheel steering angle sensor 54, a turn signal switch 60, and a guide line recognition means 62. A steering torque sensor 51 as a steering torque detecting means M3 detects a torque applied to the steering shaft 12 and supplies a signal representing the steering torque MT to the ECU 50. The rear wheel steering angle sensor 54 measures the rotation angle of the step motor 43 and supplies a signal representing the rear wheel steering angle θr to the ECU 50. The turn signal switch 60 is turned on when the turn signal is operated, and supplies an on / off signal to the ECU 50. The road surface μ sensor 61 as a road surface condition detecting means detects a road surface μ (friction coefficient) from, for example, the amount of torsion of the axle and the wheel speed to obtain E.
Supply to CU50. It should be noted that there is another type in which the road surface μ is estimated using an ultrasonic sensor.

A guide line recognizing means 62 serving as a running path recognizing means M1 is supplied from a camera 64 with a road image obtained by photographing a road ahead in the traveling direction of the vehicle. The road image is processed and a white line or yellow at the center or road side of the road is processed. , The travel lane is recognized based on the guideline, and the vehicle offset amount E (n) from the travel lane center line indicated by the one-dot chain line in FIG. 4 is detected. Here, θ is the inclination angle obtained from the image, l is the forward fixation point distance (constant value), e is the current lateral shift amount, and is expressed as E (n) = e + e ′ e ′ ≒ l × θ. This vehicle offset amount E (n) is determined by the ECU
50.

As shown in FIG. 3, the electronic control unit 50 is constituted by a microcomputer and has a central processing unit (CP).
U) 70, a read only memory (ROM) 72, a random access memory (RAM) 74, an input port circuit 76, an output port circuit 78, and a communication circuit 80. They are connected to each other by 82.

The input port circuit 76 is supplied with detection signals output from the steering torque sensor 51, the rear wheel steering angle sensor 54, and the turn signal switch 60. Further, the communication circuit 80 is supplied with the vehicle offset amount E (n) output from the guide line recognition means 62.

The ROM 72 stores a control program. The CPU 70 performs various operations described below based on the control program, and the RAM 74 is used as a work area at that time. FIG. 5 shows a flowchart of one embodiment of the steering control process executed by the ECU 50 of the device of the present invention.
This process is repeatedly executed at predetermined time intervals. In the figure, in step S12, it is determined whether or not the travel lane has been recognized by the guideline recognition means 62. If the travel lane can be recognized, the process proceeds to step S14, and if not, the processing cycle ends.

In step S14, the steering torque sensor 51
Is read, and the vehicle offset amount E output by the guideline recognition means 62 is read.
(N) and the lane width l (n) are read. Next, step S
In step 16, 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 last rear wheel steering control. Quantity, E (n-
1) is the previous vehicle offset amount, and K1 is the rear wheel control gain (constant value). Next, in step S18, the lane width change amount L (n) and the change speed ΔL (n) are calculated by the following equations.

L (n) = | l (n) −l (n−1) | (2) ΔL (n) = | L (n) −L (n−1) | (3) ) Where l (n-1) is the previous lane width and L (n-1) is the previous
This is the change amount of the lane width calculated each time. After this, step S
20 and the lane width variation L (n) is equal to the reference value L. ₀Than
Whether the speed is large or the lane width change speed ΔL (n) is a reference value
ΔL₁It is determined whether or not the value is larger. Here, L (n)> L
₀Or ΔL (n)> ΔL₁If it is one of
Proceeding to step S22, L (n) ≦ L₀And ΔL (n) ≦
ΔL₁In the case of, the process proceeds to step S24.

In step S22, the lane width variation L
(N) is greater than the reference value or the lane width change rate Δ
Since L (n) is larger than the reference value, the vehicle is traveling on a junction or merging point of the road or a part where the guidelines are parallel, and it is highly possible that the target route is not stable. , The actual rear wheel steering control amount D (m) is multiplied by the correction control gain Ka (0 <Ka <1) to correct the actual rear wheel steering control amount D.

D = D (n) × Ka (4) In step S 24, the lane width change amount L (n) is smaller than the reference value, and the lane width change speed ΔL (n) is smaller than the reference value. Since the target route is stable, there is no need to correct the rear wheel steering control amount D (n), and this is set as it is as the actual rear wheel steering control amount D.

After executing the above-described step S22 or S24, the process proceeds to step S26, in which the drive circuit 56 is driven based on the actual rear wheel steering control amount D, whereby the step motor 43 is rotationally driven to steer the rear wheels. Is performed, and then the processing cycle ends.

Here, as shown in FIG. 6, when the left side of the vehicle 70 has one guide line and the right side has two guide lines, and the one-sided protruding road continues beyond the one side, the guide line recognizing means 62 sends the ECU 50 to the ECU 50. 7 fluctuates between values a and b in periods T ₁ and T ₃ in which there are two guidelines, a solid line and a broken line on the right side, as shown in FIG. At this time, the lane width change amount | a
If −b | exceeds the reference value L ₀ , it is determined that the road is one side protruding and no overtaking is prohibited, and the rear wheel steering control amount D (n) is multiplied by the correction control gain Ka shown in FIG.
Reduction correction of the actual rear wheel steering control amount D is performed. Constant gain in the period T ₂ in the lane width value a is 1.

When the road is branched on the left side of the vehicle 70 as shown in FIG. 8 and the guide line is divided into two, the lane width 1 supplied from the guide line recognizing means 62 to the ECU 50 is as shown in FIG. As shown in (2), the value f varies between values a and b as the vehicle advances from the branch point, and the value b gradually increases. At this time, the amount of change | ab− of the lane width is equal to the reference value L _0.
Correction control gain Ka shown in FIG. 9 (B) is multiplied by the rear wheel steering control amount D (n) in a period T _10, T ₁₁ beyond the,
Reduction correction of the actual rear wheel steering control amount D is performed. The amount of change in lane width | a-b | gain in a period of less than the reference value L ₀ is a 1.

[0031] Thus, when the lane width l is varied, whether the amount of change exceeds the reference value L _0, or when the change rate is large change that exceeds the reference value L ₁ is, for example, the lane width l The target route at the center position changes to the left and right and is not stable, and the rear wheel steering is also unstable, but in this embodiment, the rear wheel steering control amount is reduced and corrected in such a driving state. Rear wheel steering is stable and drivability is improved.

FIG. 10 shows a flowchart of another embodiment of the steering control process executed by the ECU 50 of the device of the present invention.
This process is repeatedly executed at predetermined time intervals. In the figure, in a step S32, it is determined whether or not the travel lane can be recognized by the guideline recognition means 62. If the traveling lane can be recognized, the process proceeds to step S34, and if not, the processing cycle ends.

In step S34, the steering torque sensor 51
Is read, and the vehicle offset amount E output by the guideline recognition means 62 is read.
(N) and the lane width l (n) are read. Next, step S
At 36, the rear wheel steering control amount D (n) is calculated by the above equation (1).

D (n) = D (n−1) + K1 × {E (n) −E (n−1)} (1) Next, in step S38, the amount of change in lane width L (n) And the change rate ΔL (n) are calculated by the equations (2) and (3). L (n) = | l (n) −l (n−1) | (2) ΔL (n) = | L (n) −L (n−1) | (3) In step S40, it is determined whether the lane width l (n) changes over time. Here, as shown in FIG. 11, the lane width l (n) repeats each of the values la and lb at a cycle S ₀ , and the repetition duration is a predetermined time t _S (for example, t _S).
Is several seconds) or more. If the above-described periodic fluctuation of the lane width continues for t _S or more, it is regarded as a road that protrudes beyond one side as shown in FIG. 6, and in such a case, the fluctuation of the lane width l (n) is small and the normal lane width is small. Since there is no problem even if rear wheel steering is performed, the process proceeds to step S42, and the rear wheel steering control amount D (n) is set as it is to the actual rear wheel steering control amount D. Steps S40 and S42 above
Corresponds to the correction stopping means M4.

On the other hand, if the lane width l (n) does not change periodically as shown in FIG. 11, the process proceeds to step S44. At step S44, the large whether from the change amount L (n) is the reference value L ₀ of the lane width, or a change in lane width rate ΔL
(N) is to determine whether large or not than the reference value [Delta] L _1. Here, if either L (n)> L ₀ or ΔL (n)> ΔL ₁ proceeds to step S46, L (n) ≦ L 0
And proceeds to step S48 when the ΔL (n) ≦ ΔL _1.

In step S44, the lane width variation L
(N) is greater than the reference value or the lane width change rate Δ
Since L (n) is larger than the reference value, the vehicle is traveling on a diverging portion or a merging portion of the road, or a portion where the guidelines are parallel, and it is highly possible that the target route is not stable. ), The actual rear wheel steering control amount D is reduced by multiplying the rear wheel steering control amount D (m) by the correction control gain Ka (0 <Ka <1).

D = D (n) × Ka (4) In step S48, the lane width change amount L (n) is smaller than the reference value, and the lane width change speed ΔL (n) is smaller than the reference value. Since the target route is stable, there is no need to correct the rear wheel steering control amount D (n), and this is set as it is as the actual rear wheel steering control amount D.

The above step S42 or S46 or S4
8, the process proceeds to step S50, in which the drive circuit 56 is driven based on the actual rear wheel steering control amount D, whereby the step motor 43 is driven to rotate and the rear wheels are steered. To end.

As described above, even if the lane width periodically fluctuates at a predetermined cycle like a one-sided overtaking prohibited road, in the calculation in step S36, the rear wheel steering control amount D ( Since n) is calculated, even if this control amount D (n) is set as the actual rear wheel steering control amount D, stable steering control can be performed without any problem in control. Of course, when the lane width 1 fluctuates periodically as the pre-processing of step S42, D (n) calculation similar to step S36 may be performed using the maximum value or the minimum value.

[0040]

According to the first aspect of the present invention, there is provided a guideline recognizing means for recognizing a guideline on a traveling route of a vehicle, a target route is set based on the recognition result of the guideline, and the vehicle travels on the target route. In a vehicle steering control device that calculates the rear wheel steering control amount and controls the rear wheel steering, a lane width change detection unit that detects a lane width change state of the traveling road based on the recognition result of the guideline, ,
A correction means is provided for reducing the rear wheel steering control amount when the amount of change in the lane width exceeds a predetermined reference value.

For this reason, when the amount of change in the lane width exceeds the reference value and the amount of steering control of the rear wheels greatly changes, the above-described amount of steering control is corrected to decrease, and the steering of the rear wheels is stabilized, and drivability is improved. . According to a second aspect of the present invention, in the vehicle steering control device according to the first aspect, when the lane width change state detected by the lane width change detection unit is periodic and continues for a predetermined time, the correction unit Correction stop means for stopping the reduction correction by the correction.

For this reason, when the lane width is changed at a predetermined cycle on a road that protrudes from one side and is not allowed to pass, setting the target route from the minimum value, the maximum value, or the average value of the lane width eliminates the necessity of the decrease correction. Driving on the target route is enabled by stable rear wheel steering, and drivability is improved.

[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 for explaining the present invention.

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

FIG. 8 is a diagram for explaining the present invention.

FIG. 9 is a diagram for explaining the present invention.

FIG. 10 is a flowchart of a steering control process.

FIG. 11 is a diagram for explaining the present invention.

[Explanation of symbols]

 Reference Signs List 11 steering handle 21 hydraulic pump 22 power cylinder 23 reservoir 31 relay rod 32a, 32b left and right tie rod 35 power cylinder 37 spool valve 38 hydraulic pump 41 lever 50 ECU 51 steering torque sensor 54 rear wheel steering angle sensor 56, 57 drive circuit 60 turn signal switch 70 vehicle M1 travel path recognition means M2 control amount calculation means M3 lane width change detection means M4 correction means M5 correction stop means

Continuation of the front page (72) Inventor Yoshiaki Suzuki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-7-104850 (JP, A) JP-A-6-300581 (JP, A) JP-A-5-294250 (JP, A) JP-A-3-74274 (JP, A) JP-A-7-129897 (JP, A) JP-A-7-81604 (JP, A) JP-A-6 -300580 (JP, A) JP-A-5-185947 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62D 6/00 G08G 1/16 B62D 7/14

Claims (2)

(57) [Claims] 1. A guide line recognizing means for recognizing a guide line on a traveling route of a vehicle, a target route is set based on a recognition result of the guide line, and a steering control amount of a rear wheel is set so as to travel on the target route. A vehicle steering control device that calculates and controls rear wheel steering; a lane width change detecting unit that detects a lane width change state of a traveling road based on a recognition result of the guideline; A steering control device for a vehicle, comprising a correction means for reducing and correcting the steering control amount of the rear wheel when the reference value exceeds the reference value. 2. The vehicle steering control device according to claim 1, wherein when the lane width change state detected by the lane width change detection unit is periodic and continues for a predetermined time, the decrease correction by the correction unit is stopped. Steering control means for a vehicle, comprising a correction stopping means.