JPH09221054A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a capability of a device for driving a steering device for performing a follow-up traveling and a steering angle correction device for performing a correction in respect to a steering angle inputted by a driver by a method wherein these devices are monitored under their separated state. SOLUTION: An image picked up by a CCD camera 38 is at first sent to an image processing section 38a, and after processing, the image is sent to a traveling area acknowledging section 38b where a traveling can be performed so as to search an area where the traveling can be carried out. Then, a result of search is sent to a target passage setting section 38c, where a course to be tried to run is designed and then a result of processing is inputted to a CPU 40. In addition, a steering angle sensor 22 is an encoder, where a steering torque sensor 20 converts it into a digital amount, its output is inputted to the CPU 40. The CPU 40 drives a motor 24 in response to these inputted signals to generate a steering torque followed by the lane so as to guide a driver and at the same time a motor 30 is driven and an improper steering input angle of the driver is properly corrected to cause the vehicle to be run in a stable manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system.

[0002]

2. Description of the Related Art As a vehicle steering system, the present applicant has proposed, for example, in Japanese Patent Laid-Open No. 5-197423, a technique for causing a moving body such as a vehicle to follow a target route with a smooth locus.

[0003]

The technique previously proposed by the applicant was to automatically drive the vehicle by the output of the device. However, when a vehicle encounters while driving, it may change lanes (lane change), change lanes at interchanges, avoid obstacles falling on the road surface, work vehicles working on the shoulder or construction signs A high degree of intelligence is required to change the course in a lane, and it is impossible for the current technology to perform fully automatic driving.

In the above-mentioned case, it is more practical to construct the vehicle so that the driver can intervene according to the driver's intention even during the automatic driving, and it is suitable for the automatic driving because the road side infrastructure is advanced in the distant future. Until it becomes a problem, it is desired to realize a device in which a person continues to be the driver of driving, and yet the device side provides information suitable for driving to the driver in an easy-to-understand form.

From this point of view, the present applicant previously disclosed in Japanese Patent Application No. Hei 7-31070 a relationship between a lane (lane) and a vehicle using a visual means such as a camera while traveling on a road. It proposes a technology that detects the occurrence of the vehicle, outputs a command for traveling along the lane to the steering device of the vehicle, and causes the vehicle to continuously travel along the lane.

The present invention is an improvement of the previously proposed technique, and its purpose is to convert information necessary for a vehicle to travel along a lane into a form of a steering force and a steering angle. Therefore, it is an object of the present invention to provide a vehicle steering system equipped with a more excellent man-machine interface, which allows the driver to drive the vehicle by his / her own will while taking the information into consideration.

More specifically, a device for driving a steering device for lane (lane) tracking and a device for driving a steering angle correction device for correcting a steering angle input by a driver are separated from each other. It is an object of the present invention to provide a vehicle steering system capable of efficiently exhibiting the respective capabilities while being managed by.

[0008]

In order to achieve the above-mentioned object, a vehicle steering system according to the present invention comprises a first means for detecting the lane condition of a running front road, and a motion condition of the own vehicle. And a third means for calculating the steering amount necessary for maintaining the positional relationship of the host vehicle with respect to the front road lane from the outputs of the first and second means, and the steering of the vehicle. Steering means for operating wheels, and first steering means for generating steering torque in response to the output of the third means.
Drive means for driving the steering wheel to generate the steering amount regardless of the steering angle applied to the steering wheel, and means for defining the maximum value of the steering torque. Configured.

[0009]

The information necessary for the vehicle to travel along the lane is converted into the form of the steering force and the steering angle to be transmitted to the driver. For the device that drives the steering device and the device that drives the steering angle correction device that corrects the steering angle input by the driver, the maximum torque of the former is determined, and the steering torque of the latter is controlled below that. Therefore, it is possible to efficiently exert each ability when managing them separately, and it is possible to reduce the size and weight of the device, and the driver can voluntarily take these information into consideration and voluntarily The vehicle can be driven more optimally.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

A virtual line 10 in FIG. 1 is an outline of a vehicle equipped with the vehicle steering system according to the present application. This device includes a steering wheel 12, a steering device 14 for steering the steering wheel 12, a steering wheel 16 for operating the steering device 14, and a combination of the steering wheel and the steering device 14. Column 18
And

On the column 18, a steering torque sensor 20 for detecting a steering torque, an electric motor 24 for giving a rotation torque to the column 18 in response to a command from a CPU (control unit) described later, and rotation of the motor. A steering angle sensor 22 including an encoder that detects an angle is provided.

Further, a worm type speed reducer 2 which constitutes an actuator 26 integrally with the electric motor 24.
7, a steering wheel correction device 32 of a worm type that intervenes between the steering wheel 16 and the column 18 and rotatably couples them, a second electric motor 30 that drives the correction device 32, and a correction device. A potentiometer-type correction angle sensor 28 for detecting an angle is provided. The details of the steering angle correction device 32 are described in the previously proposed application.

A vehicle speed sensor 34 for electrically detecting the traveling speed of the vehicle, a yaw rate sensor 36 for electrically detecting the rotational speed of the vehicle about a vertical axis, and a CCD camera 38 for picking up an image of the road condition ahead of the vehicle. And the CPU (control unit) 40 described above drives the two motors 24 and 30 based on the information from these sensors.

FIG. 2 shows the CPU (control unit) 4 described above.
It is a block diagram which shows the detail of the structure of 0.

As shown in the figure, the image picked up by the CCD camera 38 is first sent to the image processing section 38a, where it is subjected to processing such as feature point extraction and Hough conversion, and then sent to the travelable area recognition section 38b. The area where the vehicle can run is searched for, and the search result is then sent to the target route setting unit 38c to formulate the plan of the course that the vehicle is about to travel. These processing results are input to the CPU 40.

The steering angle sensor 22 is an encoder,
The output is input to the CPU 40. The output of the steering torque sensor 20 is converted into a digital value through the A / D converter 20a and then input to the CPU 40. The CPU 40 calculates the motor torque command value based on these input signals according to the algorithm shown in FIGS.
4 and the motor 30 are driven. As is well known, D / A converters 24a and 30a and motor amplifiers 24b and 30b for converting the weak signals into current values are inserted in the path for outputting to the motor.

A SAS (Steer Assist S) that can be manually switched to the driver's seat to activate this device.
(witch) switch 41 and a follow-up indicator light 42 for indicating to the driver that the device is activated (FIG. 1).
(Not shown). The CPU 40 has a storage device ROM for storing various gains necessary for calculation, and can read the information in the ROM as needed.

The steering apparatus having such a configuration drives the motor 24 according to an algorithm described later with reference to FIGS. 3 and 4, thereby generating steering torque that follows the lane, guiding the driver, and driving the motor 30. By doing so, the driver's inappropriate steering input angle is appropriately corrected, and the vehicle is promised to travel stably in the lane. In addition, the course in which the output of the motor 24 is guided according to the output of the steering torque sensor is changed by an algorithm described later, and an obstacle falling inside the lane or a pylon row provided for safely working on the shoulder of the road is used. Allows to avoid.

FIG. 3 and FIG. 4 are flow charts showing the operation of this steering device.
The problems of the present invention will be more specifically covered.

The present invention is a device for driving a steering device for lane following in a vehicle steering system having a man-machine interface, and a device for driving a steering angle correction device for correcting a steering angle input by a driver. It is an object of the present invention to provide a vehicle steering system in which the above and the above are managed separately and the respective capabilities are efficiently exerted. Therefore, a motor 24 that generates a steering torque for following the lane and , A motor 30 for correcting an error in the steering angle input by the driver and giving a correct steering angle to the steering device.
I was prepared to.

Then, the former motor is caused to exhibit a tracking function along the lane, and when the latter motor has a difference between the input angle of the driver and the steering angle output by the device, this difference is used as the steering force. Configure to convert and call attention. Also, the former motor is assigned the function of changing the course within the same lane according to the driver's intention. In this way, the role of each motor is optimized to maximize the structural characteristics, and the overall size and weight of the device are reduced.

At the same time, as a result of the above separation,
Make sure that the two motor outputs do not conflict as driving information. While driving, the steering system must withstand the road surface reaction force coming from the road surface and steer the steered wheels, but the former motor 24 is required to be provided with an output that overcomes the maximum value of the road surface reaction force. It If not you
There is a risk that you will not be able to bend the largest curve you may encounter.

It is assumed that the latter motor 30 gives an output generally smaller than the maximum value of the former motor output with respect to the output of the former motor thus determined. This is because if the motor output of the latter is larger than that of the former, it may deviate from the lane during the steering angle correction, and the purpose of the steering angle correction cannot be achieved. Therefore, it is necessary to properly set these outputs so that the lane following function is exerted and the driver is informed that the driver does not feel uncomfortable.

More specifically, the lane is normally held to withstand road surface resistance, and when moving from the current lane to another lane, the induced torque that tends to stay inside the lane and the steering angle correction portion When the centering torque that is generated and tries to stay at the center of the correction range is coupled, the torque fluctuation at the coupling point between the two is set so that a natural feeling can be obtained.

As a means for solving the above proposition, it is simply 2
Adjusting and setting one output is not always the optimum one, so it is necessary to create an adjusting mechanism more actively according to the situation. Specifically, when lane guidance is the main mode, the torque required for lane guidance is set to be large so that it can follow the lane of a fairly sharp curve well, and this is detected when a lane change is required. And gradually reduce the torque required for lane guidance,
By smoothly connecting with the centering torque exerted by the steering angle correction device 32, a more natural driving feeling can be obtained.

In the following description based on the above assumption, when the SAS switch 41 is pressed, the program is started in STEP-51, and the flow advances to STEP-52 to read various sensor information.
Go to STEP-53.

The processing from STEP-53 to STEP-63 is based on the control algorithm disclosed in Japanese Patent Application Laid-Open No. 5-197423 and Japanese Patent Application No. 7-31070 previously proposed by the present applicant. . A brief description will be given below.

First, in STEP-53, the inclination angle Θ W of the vehicle (referred to as the vehicle W) on the coordinates is calculated, and the flow advances to STEP-54 to calculate the current position of the vehicle W. This is xy of vehicle W
This is performed by obtaining the XY coordinate component (XW, YW) of the origin o of the relative coordinates.

Then, in STEP-55, the target point P is set. This expresses the target route M as a sequence of points in xy relative coordinates, and the distance xp (= VT), which is the current vehicle speed V of the vehicle W moved in the x-axis direction by a predetermined preview time T, is defined as an x-coordinate component. Yes, it is set as a point on the target route M.

Next, in STEP-56, it is judged whether or not the lane (lane) has been changed. If the result is affirmative, STEP-6
Go to 9 to end the program. To determine whether or not the lane has been changed, for example, how much the vehicle is currently biased from the center of the lane is detected and the deviation ΔL is calculated, and the deviation ΔL is less than 0.75L with respect to the lane width L. When it gets bigger, it is considered that the lane has changed substantially.

When it is determined in STEP-56 that the lane has not been changed, the process proceeds to STEP-57, and the course change amount ΔX is calculated. Here, ΔX is obtained by multiplying the detected steering torque τs by a proportional constant K1, but it does not make sense to change the target course to be greater than or equal to the width L of the lane. If it is less than 60% in the lane. Considering the width of the car, this is a sufficiently practical course change.) 3 when exceeded
Limit to 0%.

Next, in STEP-58, the current position XW is corrected. That is, the above-mentioned course change amount Δ from the detected value XW
X is subtracted to cause the CPU 40 to intentionally misrecognize that the current vehicle position is laterally (vehicle width) shifted by -ΔX. As a result, it is considered that the target point is laterally deviated by ΔX in the process described below, and the necessary steering angle is calculated based on this, resulting in the target course being Δ
It can be moved laterally by X.

Next, in STEP-59, the target yaw rate γ
Calculate m.

First, the target point yaw rate γ P,
That is, the yaw rate of the vehicle W for causing the vehicle W to reach the target point P from the current position (origin o) is obtained by an appropriate formula. Subsequently, the angle deviation ΔθP between the vehicle W and the target route M at the target point P is obtained, and the correction amount ΔγP of the yaw rate that eliminates the angle deviation ΔθP is obtained.
This is performed by correcting the target yaw rate γP by subtracting the product obtained by multiplying ΔγP obtained from P by the correction coefficient Km.

The correction coefficient Km is the curvature ρ and the road width D of the travelable route A (same as the travelable region described above) in STEP-60, which is performed in parallel with the processing of STEP-53 and below in the illustrated flow chart. Obtained, STEP-61 curvature ρ, road width D, vehicle speed V
From fuzzy reasoning.

Next, in STEP-62, the target yaw rate γ
The rudder angle that produces m is calculated as the target rudder angle δm using an appropriate formula, and the process proceeds to STEP-63 to calculate the target value θD of the displacement angle of the motor 24 so that the target rudder angle δm is obtained. Next, in STEP-64, the current motor angle θt and target angle θ
The amount obtained by multiplying the difference from d by a predetermined gain K2 is determined as the torque command value T24. Here, the motor torque command value T24
The maximum output (maximum torque) value of is To, and if the calculated value is less than or equal to To, the calculated value is output as it is. However, if the calculated value exceeds To, the calculated result is ignored and To is set as the motor torque command value. Output as.

Next, a motor torque command value T30 output to the motor 30 of the steering angle correction device is calculated.

That is, in STEP-65, an amount obtained by multiplying the detected steering force τs by the proportional constant K3 is calculated as the target angle αad of the motor 30. If the calculated value of αad is within 15 °, adopt the calculated value as it is, and if the calculated value exceeds 15 °, αad
Fix ad at 15 °.

Since the output of the motor 30 is boosted by the worm gear as described with reference to FIG.
Even if the torque to be fixed at 15 ° is small, the steering wheel 16 can be used due to the irreversible power transmission characteristics of the worm gear.
The angle is fixed at 15 ° even if the steering force applied to the motor exceeds the output of this motor.

Next, in STEP-66, the target angle αad
Then, a motor torque command value T30 for performing follow-up control so that the actual angle αt becomes equal to is obtained as a known feedback control operation amount. Next, in STEP-67, the determined command value is output to each of the amplifiers 24b and 30b.

Here, the maximum value To of the output of the motor 24 will be explained. When the vehicle steers along a curve while traveling, the reaction force (the road surface reaction) that tends to return the wheels to the straight traveling position by the alignment of the front wheels. Force) occurs. To steer against this reaction force, it is necessary to operate the steering device with more torque.

Since the road reaction force normally increases in proportion to the steering angle (steering angle) of the steering wheel, a steering angle at which a curve with a large radius R, which is expected on a curved road, can be bent is assumed. The maximum torque To is set to a value equal to or larger than the road surface reaction force. For example, T
o = 50 Kg m. To = 50 kg m is a value that can reliably follow the vehicle running even on the above curve.

The relationship between the steering torques of the motor 30 and the motor 24 at this time will be described with reference to FIG.

Here, the case where the correction of the steering angle is limited to ± 15 ° will be described. When the steering angle is within ± 15 °, the steering angle shown in FIG. 5 is obtained by the virtual spring force generated by the steering angle correction device 32. A proportional steering reaction force can be obtained. This is to control the drive angle of the motor according to the applied torque, but from the driver's point of view, when torque is applied, it is as if the steering wheel was twisted with respect to the column with that torque. This is because it acts as a spring.
The details are described in the application previously proposed by the present applicant.

When the steering angle reaches ± 15 °, the correction angle is limited to 15 ° in STEP-65, and if the driver tries to steer the steering angle beyond that, the steering wheel 16 is turned against the electric motor 24. It will rotate. However, at that time, since the electric motor 24 deviates from the target angle, the maximum torque To opposes the steering force applied by the driver. The driver outputs the output torque To x (
If a steering force larger than the gear ratio Kw) of the actuator 26 is exerted, the steering device 14 can be manually rotated to the driver's intention and moved to the adjacent lane.

However, when the driver's steering force is less than To * Kw, the vehicle travels on the target course (corrected target course displaced up to 30%), but the lane is not changed. In order to obtain such behavior, the steering force τ15 caused by the output torque of the electric motor 30 generated at the correction angle of ± 15 ° is to be calculated as To × Kw caused by the maximum torque of the electric motor 24. The requirement is that they are greater or at least the same.

If this is not the case, the lane change will occur with a torque lower than τ15, and the angle range for steering angle correction will be narrowed. Here, the steering torque τ15 caused by the maximum output of the motor 30 is described by the amount obtained by multiplying the output torque of the motor 30 by the gear ratio ratio kw of the actuator (steering angle correction device) 32.

Since the normal steering torque is much lower than this, when the steering torque resulting from the maximum torque of the motor 24 is as high as 50 Kg m, the steering force τ15 resulting from the maximum output of the motor 30 is increased. The setting as shown in FIG. 5 will make the driver feel more natural.

Returning to the explanation of FIG. 3 and FIG. 4 again, the program proceeds to STEP-68, and it is judged whether or not the operation is completed, specifically, whether or not the SAS switch is turned off.
Return to 2 and repeat the same process. If the SAS switch is judged to be off, proceed to STEP-69 and end the program.

As a result of the above-described configuration in this embodiment, the device that follows the lane and the device that corrects the steering angle are separated in terms of both hardware (structure) and software (control algorithm), and Since the device 26 on the lane follower side is assigned the role of changing the target course in the lane according to the applied steering torque, and the virtual spring action according to the applied steering torque is assigned to the device 32 on the steering angle correction side. The roles of the respective devices are clarified, it becomes easier to prevent mutual interference, and the steering torque can be set more appropriately.

Further, the output produced by the steering angle correction side 32 is set to be smaller than the output of the device 26 on the lane following side to prevent mutual interference, and the magnitude of the motor output on the lane following side is set. It is possible to more easily set the size that can oppose the road surface reaction force.

Next, a second embodiment of the present invention will be described.

In the first embodiment, as shown in FIG.
The output of the motor 24 must be set to a large value, and the driver will encounter a large torque fluctuation at the connection point with the steering angle correction motor output. When such a large steering torque is encountered, it is difficult for the driver to change lanes because the driver will practically give up further steering.

The second embodiment is intended to eliminate this drawback. The structure of the device according to the second embodiment is the same as that of the first embodiment shown in FIGS. 1 and 2.

FIGS. 6 and 7 are flow charts showing the operation of the apparatus according to the second embodiment.

In the figure, steps up to STEP-163 are substantially the same as steps up to STEP-63 of the first embodiment. In the following description, focusing on the difference, in the second embodiment, the maximum value To of the output of the motor 24 in STEP-164 is To.
Is configured to be changed by the applied steering torque τs.

That is, as shown in FIG. 8, when the detected steering torque approaches τ15, the motor 2 which has been high until then is detected.
The maximum torque value To of 4 gradually decreases, and the steering force becomes τ15.
It is configured so that when it reaches, it becomes exactly τs.

Therefore, in STEP-164, the detected steering torque τ
When s is 0, To is directly applied to To, but
When τs increases to 15 ° / K3, To is just τ
We prepared a formula that is equal to 15, and decided to use the amount calculated according to this formula as the torque command value instead of To.

Note that, after STEP-165, the first embodiment
It is practically the same as that after STEP-64.

In addition to the effects described in the first embodiment, the second embodiment is configured so that the torque for following the lane decreases as the steering force increases. As shown in FIG. 8, smooth steering can be performed at the junction of the outputs of the two motors, and it is possible to avoid encountering a sudden increase in torque as shown in FIG.

Decreasing the lane following torque according to the steering force is consistent with the lane following function. This is because the steering torque is being applied and increasing because the driver wants a lane change, and at that time, it is more realistic to reduce the lane following function.

In the above, the technique disclosed here is only an example, and various modifications can be made when actually designing a product.

The motor 24 is not limited to being provided on the column, and the motor may be arranged concentrically with the steering device, for example, on a rack.

Various steering torque sensors have been proposed so far, and a combination of a torsion bar and a potentiometer, a combination of electric resistance change by a strain gauge, or a combination of a torsion bar and a hall element is known. As such, it should not be limited to that disclosed.

The change of the target course is not limited to the method illustrated here, and the same effect can be obtained by shifting the target point P to the left or right according to the steering force τs.

As the steering angle correction device, as proposed by the present applicant in the above-mentioned application, a sector gear system in which the worm gear is not circular but in the shape of a partial circle is also effective. In addition to determining the range of ± 15 ° by the algorithm as in the above-described embodiment, a method of providing a mechanical stopper is also disclosed in the above application. It will be apparent to those skilled in the art that these techniques can be applied to the present invention.

The method for realizing the characteristics shown in FIG. 8 is not limited to the disclosed embodiment, and the maximum output value of the motor 24 is reduced in accordance with the increase in the output of the correction angle sensor 28, for example. It is also easy to do.

In the present invention, as described above, the first means (CCD camera 38) for detecting the lane condition of the traveling forward road and the second means (3) for detecting the motion condition of the own vehicle.
8a, 38b, 38c) and a third means (CPU) for calculating the steering amount δm required to maintain the positional relationship of the own vehicle with respect to the road lane ahead from the outputs of the first and second means.
40, STEP-62, etc.), steering means for operating the steered wheels of the vehicle (steering device 14), and a first means for generating steering torque T24 in the steering means according to the output of the third means. Of the steering amount .delta.t regardless of the steering angle .theta.t applied to the driving means (electric motor 24) and the steering wheel 16.
It is constituted by a second drive means (electric motor 30) for driving the steering wheel to generate m and a means (STEP-64) for defining the maximum value To of the steering torque.

Further, the second drive means (electric motor 3
0) is operated, the output T24 of the first drive means is changed so that the motion state of the own vehicle can be changed according to the operation amount T30.

Further, the second drive means (electric motor 3
0) is operated, the second drive means is driven so as to bias the steering wheel to the reference position of the second drive means in accordance with the operation amount T30 (STEP-66).
Configured as

Furthermore, a measuring means (steering torque sensor 20) capable of measuring the steering torque τs applied to the steering wheel is provided, and the steering torque is within a predetermined range (±
15 °), a displacement (αad = K3 · τs) proportional to the steering torque τs, and a substantially constant displacement (αad = ± 15) when the steering torque exceeds the predetermined range.
Is provided to the second driving means.

Further, the second drive means (electric motor 3
0) driving displacement θt is measured and an urging force T30 corresponding to the driving displacement is applied to the steering wheel, so that the driving displacement measuring means (correction angle sensor 28) can be driven by the second driving means. ) Is provided.

Further, the second drive means (electric motor 3
An angle defining means (STEP-65) for defining the driving range of 0) within a specified angle (± 15 degrees) is provided.

Further, the first drive means (electric motor 3
The maximum value To of the driving force (0) is set to be equal to or more than the road surface resistance value that the vehicle receives during traveling.

Further, the first means (CCD 38) for detecting the lane condition of the road in front of which the vehicle is running, the second means (38a, 38b, 38c) for detecting the motion condition of the own vehicle, and the first, The third means (CPU, STEP-62, etc.) for calculating the steering amount δm required to maintain the positional relationship of the own vehicle with respect to the road lane ahead from the output of the second means, and the steering wheel of the vehicle are operated. Steering means (steering device 14), and the third
The first drive means (electric motor 24) for generating steering torque T24 in the steering means in accordance with the output of the steering means and the steering amount δm regardless of the steering angle θt applied to the steering wheel 16. And a second drive means (electric motor 30) for driving the steering wheel for this purpose.
The driving force T30 of 0) is set to be equal to or less than the driving force T24 of the first driving means (electric motor 24).

Further, when the steering force τs is small, the lane following function is strengthened, and when the steering force is large, the lane following function is lowered (FIG. 5, To × Kw).

Further, the second drive means (electric motor 3
0) is actuated, the maximum value To of the driving force T24 of the first driving means (electric motor 24) is changed according to the actuation amount T30 (STEP-164).

Further, the second drive means (electric motor 3
0) is driven and the specified value of the drive range (± 15 °)
When approaching the first drive means (electric motor 24)
The maximum value To of the driving force T24 is reduced (STEP-164).

Further, the second drive means (electric motor 3
0) is driven and the specified value of the drive range (± 15 °)
When approaching the first drive means (electric motor 24)
The maximum value To of the driving force T24 is reduced to substantially the same level as the driving force T30 of the second driving means (electric motor 30) (STEP-164).

Further, when the detected torque τs of the steering force detecting means (steering torque sensor 20) increases and approaches the specified value, the driving force of the first driving means (electric motor 24) is increased according to the approaching amount. Change the maximum value To of T24 (STEP
-164)

Further, in the above-mentioned embodiment, the CCD camera is used for obtaining the front lane information, but the present invention is not limited to this, and other methods can be applied. For example, in recent years, an attempt has been made to embed a magnetic mark on the road side and use the magnetism to drive in a lane. However, if this method and more precise navigation information are put to practical use, a CCD camera will be used. This information can be used instead of information.

[0083]

As described above, the information necessary for the vehicle to travel along the lane is converted into the form of the steering force and the steering angle and transmitted to the driver. The maximum torque of the former is determined for the device that drives the steering device and the device that drives the steering angle correction device that corrects the steering angle input by the driver, and the steering torque of the latter is controlled below that. As a result, it is possible to efficiently exert each capacity when managing them separately, and it is possible to reduce the size and weight of the device as well, and the driver can keep his or her own information while taking this information into consideration. The driver can drive the vehicle more optimally.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an entire vehicle steering system according to the present invention.

2 is a block diagram showing details of a configuration of a control unit (CPU) in the apparatus of FIG.

3 is a first half flow chart showing the first half of the flow chart showing the operation of the apparatus of FIG. 1. FIG.

4 is a second half flow chart showing a second half of the flow chart showing the operation of the apparatus of FIG.

FIG. 5 is a graph showing steering torque characteristics of a motor for explaining the operations of FIGS. 3 and 4;

FIG. 6 is a first half flow chart showing a first half of the flow chart showing the operation of the apparatus according to the second embodiment.

FIG. 7 is a second half flow chart showing a second half of the flow chart showing the operation of the apparatus according to the second embodiment.

FIG. 8 is a graph diagram showing steering torque characteristics of the motor in the second embodiment similar to FIG.

[Explanation of symbols]

 10 Vehicle 14 Steering Device 16 Steering Wheel 18 Column 20 Steering Torque Sensor 22 Steering Angle Sensor 24, 30 Electric Motor 26 Actuator 28 Correction Angle Sensor 32 Steering Angle Correction Device 34 Vehicle Speed Sensor 38 CCD Camera 40 CPU (Control Unit) 41 SAS Switch

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B62D 119: 00 137: 00

Claims (13)

[Claims] 1. A first means for detecting a lane condition of a running front road, a second means for detecting a motion condition of the own vehicle, and a front road lane based on outputs of the first and second means. Third means for calculating a steering amount required to maintain the positional relationship of the host vehicle with respect to the vehicle, steering means for activating steering wheels of the vehicle, and the steering means according to the output of the third means. A first drive means for generating a steering torque, a second drive means for driving the steering wheel to generate the steering amount regardless of a steering angle applied to the steering wheel, and a maximum value of the steering torque. A vehicle steering system comprising: 2. When the second drive means operates, the output of the first drive means is changed so that the motion state of the own vehicle can be changed according to the operation amount. The vehicle steering system according to claim 1, wherein the steering system is a vehicle. 3. When the second drive means is operated, the steering wheel is moved to the second wheel according to an operation amount of the second drive means.
2. The second driving means is configured to be driven so as to urge the driving means to the reference position.
Item 3. A vehicle steering system according to item 2 or item 3. 4. A measuring means capable of measuring a steering torque applied to the steering wheel, wherein when the steering torque is within a predetermined range, a displacement proportional to the steering torque, or the steering torque is within the predetermined range. The vehicle steering system according to claim 3, wherein the second drive means is provided with a substantially constant displacement when the range is exceeded. 5. The driving displacement of the second driving means is measured so that the second driving means can be driven so that an urging force corresponding to the driving displacement is applied to the steering wheel. The vehicle steering system according to claim 3, further comprising measuring means. 6. The angle defining means for defining the driving range of the second driving means within a specified angle, as set forth in claim 1, 4, or 5. Vehicle steering system. 7. The vehicle steering system according to claim 1, wherein the maximum value of the driving force of the first drive means is set to be equal to or more than a road surface resistance value received while the vehicle is traveling. 8. A first means for detecting a lane condition of a running front road, a second means for detecting a motion condition of the own vehicle, and a front road lane based on outputs of the first and second means. Third means for calculating a steering amount required to maintain the positional relationship of the host vehicle with respect to the vehicle, steering means for activating steering wheels of the vehicle, and the steering means according to the output of the third means. First drive means for generating a steering torque, and second drive means for driving the steering wheel to generate the steering amount regardless of the steering angle applied to the steering wheel. The driving force of the driving means is set to be less than or equal to the driving force of the first driving means. 9. The structure according to claim 4, wherein the lane follow-up function is strengthened when the steering force is small, and the lane follow-up function is reduced when the steering force is large. The vehicle steering system according to any one of 1. 10. When the second drive means is operated, the maximum value of the drive force of the first drive means is changed according to the operation amount of the second drive means. Item 8. The vehicle steering system according to item 1 or item 8. 11. The maximum driving force of the first driving means is reduced when the second driving means is driven to approach a specified value of the driving range. The vehicle steering system according to claim 10. 12. The maximum value of the driving force of the first driving means is substantially equal to the driving force of the second driving means when the second driving means is driven to approach a specified value of the driving range. 2. The level is reduced to the same level.
The vehicle steering system according to item 0 or 11. 13. When the detected torque of the steering force detecting means increases and approaches a specified value, the maximum value of the driving force of the first drive means is changed according to the approaching amount. The vehicle steering system according to claim 9.