JP2001048033A - Lane following device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize stable lane following control performance by correcting a lane following control characteristic so as to attain the same lane following control as that when a power steering device is normal, regardless of a change in assist force characteristic of a power steering device. SOLUTION: In a lane following control, a motor 7 removes an output limit at the time of assist fall and generates an output required as steering assist force. Assist force is gradually reduced within time when the motor 7 is not damaged and is finally made as manual steering. Even if assist fall is generated at the time of steering, a rapid change in steering force by high assist capability is suppressed by intermediately getting a mode into a maximum assist control mode and the motor 7 can be prevented from being damaged without imparting unnatural feeling to a driver by confirming a straight advancing traveling, getting the mode into an assist reduction control mode and releasing assist force on a lane following control system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for taking in lane information and applying a steering torque to a steering force transmission system so as to follow the vehicle in the forward lane, or a steering reaction torque. The present invention belongs to the technical field of a lane following device that is applied as a control device that supports driver steering so that the own vehicle follows the front lane by giving it to a force transmission system.

[0002]

2. Description of the Related Art Conventionally, as a lane following device which detects a lane condition ahead of a vehicle, calculates a target line of the vehicle from this information, and performs lane following control, for example, Japanese Unexamined Patent Publication No. 8-33
One described in Japanese Patent No. 7181 is known.

This publication describes a technique for detecting an obstacle or a preceding vehicle in a traveling lane and changing the lane so as to avoid the preceding vehicle (an obstacle) promptly.

[0004]

However, in the above-described conventional lane following device, the lane following constant lane following control characteristic is obtained irrespective of the characteristic change of the power steering device provided in the same steering force transmission system. Since the device performs tracking control, if the characteristics of the power steering device change, the lane tracking control characteristics will also change,
There was a problem that stable lane following control performance could not be obtained.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a lane following device that realizes stable lane following control performance irrespective of changes in the characteristics of the power steering device. It is in.

[0006]

According to the first aspect of the present invention, a steering actuator provided in a steering force transmission system for applying a steering torque or a steering reaction torque, and a lane information detecting means for detecting a lane condition of a road ahead. And a target line setting means in which a target line which is a traveling lane of a target vehicle is set, and a control command for causing the vehicle to follow the set target line during lane tracking control is output to the steering actuator. An assist force characteristic detecting means for detecting an assist force characteristic of a power steering device provided in a steering force transmission system, and an assist for determining the detected assist force characteristic in a lane following device provided with lane following control means. The power characteristic determining means and the lane following control characteristic are set to the normal value of the power steering device regardless of the change in the determined assist force characteristic. Characterized in that it and a lane following control characteristic correcting means for correcting to achieve the same lane keeping control and.

According to a second aspect of the present invention, in the lane following device according to the first aspect, when the lane following control unit detects that the power steering device has failed, the steering is performed instead of the power steering device. A steering assist control unit that applies a steering assist force using an actuator is provided.

According to a third aspect of the present invention, in the lane following device according to the second aspect, the steering assist control unit is configured to control the steering actuator during the lane following control when the power steering device is detected as having an assist failure. Assist control mode in which the maximum output command is issued with the output limit removed, the assist force decrease control mode in which the assist force is gradually reduced when straight running is detected during the maximum assist control mode, and the assist force decrease Thus, the control unit is in a manual steering mode in which manual steering is performed when the assist force becomes zero.

According to a fourth aspect of the present invention, in the lane following apparatus according to any one of the first to third aspects, the power steering apparatus is a hydraulic power steering apparatus that obtains an assist force by hydraulic pressure, and the lane following control means includes ,
When it is detected that the power steering device is not in the assist failure state, the oil for performing oil temperature compensation that maintains a constant power steering characteristic regardless of the oil temperature by adding the assist force of the steering actuator to the assist force of the power steering device. A temperature compensation control unit is provided.

According to a fifth aspect of the present invention, in the lane following device according to the fourth aspect, the oil temperature compensation control unit is configured to make a gain characteristic with respect to a steering frequency of the power steering device constant regardless of the level of the oil temperature. The control unit is characterized by a characteristic oil temperature compensation and a static characteristic oil temperature compensation that makes the assist force characteristic with respect to the steering angle of the power steering device constant regardless of the oil temperature.

[0011]

According to the first aspect of the present invention, at the time of lane following control, the lane information detecting means detects the lane state of the road ahead, and the target line setting means determines the traveling lane of the target vehicle. The target line is set,
In the lane following control means, a command for matching the own vehicle traveling line detected with the set target line, that is, a control command for causing the own vehicle to follow the target line is transmitted to the steering force transmission system by steering torque or steering reaction force. It is output to a steering actuator that applies torque.

Then, the assist force characteristic detecting means detects the assist force characteristic of the power steering device provided in the steering force transmission system, and the assist force characteristic determining means determines the detected assist force characteristic. The lane-following control characteristic correcting means corrects the lane-following control characteristic so as to achieve the same lane-following control as when the power steering device is normal, irrespective of a change in the determined assist force characteristic.

Therefore, for example, when the characteristic of the power steering device is changed to a characteristic in which the assist force is lower than normal, the lane following control is performed while supplementing the reduced assist force by the steering actuator. As a result, stable lane following control performance can be realized irrespective of changes in the characteristics of the power steering device.

According to the second aspect of the present invention, when it is detected that the power steering device has failed, the steering assist control section of the lane following control means uses a steering actuator instead of the power steering device. Power is applied.

Therefore, in the conventional system, if the power steering device loses the assist during the turning due to the manual steering, the steering assist force is lost, so that a sharp change in the steering force occurs, giving a sense of incongruity to the driver. . On the other hand, in the event of assist failure, the steering assist control unit uses a steering actuator to apply steering assist force instead of the power steering device, thereby preventing a sudden change in steering force at the time of assist failure. can do.

According to the third aspect of the invention, when it is detected that the power steering device is in the assist failure state and the steering assist control section starts the control, first, the output to the steering actuator during the lane following control is limited. It is set to the maximum assist control mode that issues the maximum output command by removing
When straight running is detected during the maximum assist control mode, the assist force decrease control mode is performed in which the assist force is gradually reduced, and the manual steering is performed when the assist force becomes zero due to the decrease in the assist force. Manual steering mode is set.

That is, in the lane following control, the steering actuator normally limits the output such as the current so as to generate only the output corresponding to the steering force by the driver.
When the assist fails, the output restriction is removed, and the necessary output is generated as the steering assist force. However, if the maximum output is continued, the steering actuator may be damaged in a certain period of time due to the insufficient capacity of the steering actuator. Therefore, the assist force is gradually reduced within a time period that does not lead to damage, and finally, the manual steering is performed. The gradual reduction of the assist force is performed when the vehicle goes straight without requiring the steering assist force.

As a result, even if an assist failure occurs at the time of steering, by immediately entering the maximum assist control mode, a rapid change in the steering force is suppressed by the high assist ability, and the assist force reduction control is performed by confirming straight running. By entering the mode and releasing the assisting force on the lane following control system side, it is possible to prevent the steering actuator from being damaged without giving the driver an uncomfortable feeling of assisting force release.

According to the fourth aspect of the present invention, when it is detected that the hydraulic power steering apparatus is not in the assist failure state, the oil temperature compensation control section of the lane following control means applies the steering force to the steering force by the power steering apparatus. , An oil temperature compensation that maintains a constant power steering characteristic regardless of the level of the oil temperature is performed.

Therefore, in the case of a hydraulic power steering device, a sufficient assist force may not be generated at the time of low oil temperature due to the effect of oil viscosity. On the other hand, when it is detected that the hydraulic power steering device is not in the assist failure state, the oil temperature compensation that maintains a constant power steering characteristic regardless of the level of the oil temperature is performed in the oil temperature compensation control unit. Power steering characteristics in which the oil temperature is stable from low to high can be realized.

According to a fifth aspect of the present invention, in the oil temperature compensation control section, dynamic characteristic oil temperature compensation for making the gain characteristic with respect to the steering frequency of the power steering device constant regardless of the level of the oil temperature, and steering of the power steering device. Static characteristic oil temperature compensation is performed so that the assist force characteristic with respect to the angle is constant regardless of the oil temperature.

Therefore, the gain characteristic is stable from low to high oil temperature by dynamic characteristic oil temperature compensation, that is, the response to the steering speed becomes constant regardless of the oil temperature, and the oil temperature is reduced from low to high by static characteristic oil temperature compensation. Until then, the assist force characteristic with respect to the steering angle becomes constant irrespective of the oil temperature, and a stable power steering characteristic including a transient response can be realized.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) Embodiment 1 is a lane following apparatus according to the first to sixth aspects of the present invention.

First, the configuration will be described.

FIG. 1 is an overall system diagram showing an automobile steering system to which the lane following device of the first embodiment is applied. In FIG. 1, reference numeral 1 denotes a steering wheel, and 2 denotes a steering shaft (corresponding to a steering force transmission system). ), 3 is a universal joint,
4 is a rack and pinion type steering gear box, 5 is a side rod, 6 is a worm wheel gear, 7
Denotes a motor (corresponding to a steering actuator), 8 denotes a worm gear, 9 denotes an electromagnetic clutch, 10 denotes a steering angle sensor, 11 denotes a CCD camera (corresponds to lane information detecting means), and 12 denotes a lane tracking controller (corresponds to lane tracking control means). , 13 an automatic steering switch, 14 a steering torque sensor, 15 a power steering controller, 16 a vehicle speed sensor, 1
7 is an engine rotation sensor, 18 is a hydraulic pressure sensor (corresponding to assist force characteristic detecting means), 19 is a power steering solenoid,
Reference numeral 20 denotes an oil temperature sensor.

The steering shaft 2 includes an upper shaft 2a which rotates integrally with the steering wheel 1.
And a lower shaft 2b connected to the upper shaft 2a by a universal joint 3. The steering wheel 1 is attached to an upper end of the upper shaft 2a.
A pinion provided at the lower end of the lower shaft 2b is screwed into a side rod 5 extending in the left-right direction of the vehicle in the rack and pinion type steering gear box 4.

A worm wheel gear 6 is provided below the upper shaft 2a, and a worm gear 8 screwed to the worm wheel gear 6 is provided on a motor shaft of a motor 7, and a motor steering torque is applied to the upper shaft 2a by driving the motor. . The motor 7 has a built-in electromagnetic clutch 9.

The steering angle sensor 10 is provided above the upper shaft 2a.
Is detected and the signal is sent to the lane following controller 12. The actual steering angle calculation unit of the lane following controller 12 calculates the actual steering angle θd using the rotation angle θ and the steering gear ratio.

The CCD camera 11 captures an image of the road ahead in the direction of travel, and converts the image signal into a lane following controller 1.
Send to 2. Then, the image processing unit of the lane following controller 12 performs image processing on the forward video based on the signal from the CCD camera 11, and extracts and identifies the boundary of the forward lane such as a white line or a center line.

When the automatic steering mode is selected, the lane following controller 12 calculates a target steering torque Tr necessary for causing the vehicle to follow the target line based on the traveling state information of the own vehicle and the set target line information. Then, lane following control for outputting a control command (motor current) to the motor 7 to obtain the target steering torque Tr is performed. In addition,
The steering state by the control is fed back based on the detected actual steering angle θd. In addition, a response control and an oil temperature compensation control in response to a characteristic change or a failure of the power steering device are also performed.

The automatic steering switch 13 is provided at a position where a driver in the passenger compartment can operate the automatic steering switch 13, and enters an automatic steering mode when the switch is turned on.

The steering torque sensor 14 is provided above the upper shaft 2a adjacent to the steering angle sensor 10, detects a twist angle φ corresponding to a driver input torque from the steering wheel 1, and outputs the signal. This is sent to the lane following controller 12. Then, the actual steering torque calculation unit of the lane following controller 12 calculates the actual steering torque Td using the twist angle φ.

The power steering controller 15
Outputs, to the power steering solenoid 19, a control command for obtaining a vehicle speed-sensitive assist force characteristic that increases the assist force as the vehicle speed decreases, based on the input information from the vehicle speed sensor 16 and the engine rotation sensor 17. The power steering controller 15 sends an assist force characteristic signal to the lane following controller 12 based on the control command.

The vehicle speed sensor 16 detects the vehicle speed and sends it to the power steering controller 15.

The engine rotation sensor 17 detects the number of engine revolutions,
Send to

The oil pressure sensor 18 detects a power steering oil pressure as an assist force and sends it to the lane following controller 12.

The power steering solenoid 19 is operated by a control command from the power steering controller 15 during steering.

The oil temperature sensor 20 detects the power steering oil temperature and sends it to the lane following controller 12.

Next, the operation will be described.

[Lane Tracking Control Process] FIG. 2 shows an automatic steering switch 13 in the lane tracking control section of the lane tracking controller 12.
Each step will be described below with reference to a flowchart showing the flow of the lane following control process started by the ON operation of.

In step 30, the own vehicle traveling state information from the image processing section for processing the video signal from the CCD camera 11 for photographing the road ahead in the traveling direction, the power steering pressure information from the hydraulic pressure sensor 18, the power steering The vehicle speed and engine rotation information from the controller 15 is read, and the routine proceeds to step 31.

In step 31, the same calculation as that of the power steering controller 15 is performed based on the vehicle speed and the engine rotation information from the power steering controller 15 to calculate the estimated assist force. On the other hand, the hydraulic pressure sensor 18
The actual assist force is calculated based on the power steering pressure information from. Then, a characteristic deviation which is a difference between the estimated assist force and the actual assist force is calculated, and the process proceeds to step 32.

In step 32, the characteristic deviation is calculated as the absolute value A
(Error range during normal operation)
If NO, go to step 34, if NO, go to step 3
Proceed to 3.

In step 33, it is determined whether or not the characteristic deviation is equal to or larger than the deviation threshold value E.
Go to step 5, if YES, go to step 36. In addition,
Steps 32 and 33 correspond to assist force characteristic determination means.

In step 34, the lane following control gain G is set to Ga based on the determination in step 32 that the assist force characteristic is within the normal error range, and the routine proceeds to step 37.

In step 35, the lane following control gain G
Is set to Gb, and the routine proceeds to step 37.

In step 36, the lane following control gain G
Is set to Gc, and the routine proceeds to step 37. Note that Ga <
Gb <Gc, and steps 34, 35, 3
Reference numeral 6 corresponds to a lane following control characteristic correcting means.

In step 37, for example, the center position of the left and right lanes is calculated as the target line Yopt (corresponding to the target line setting means d), and the target steering torque Tr required for the own vehicle to follow this target line Yopt is calculated. The calculation is performed, and the process proceeds to step 38.

At step 38, steps 34, 35,
36, a lane following control gain G determined by any one of
A motor current I ｛= G · f (Tr)｝, which is a control command, is output to the motor 7 based on the target steering torque Tr calculated in step 37.

[Lane Following Control Action for Power Steering Characteristic Change] In the lane following control, if the assist force characteristic of the hydraulic power steering device is normal, the flow chart of FIG.
→ The flow proceeds from step 34 → step 37 → step 38, the lane following control gain G is set to Ga (reference gain), and the motor current I that gives the target steering torque Tr to the steering force transmission system is output to the motor 7. Is done.

If the assisting force characteristic of the hydraulic power steering apparatus is such that an assisting force slightly smaller than the normal assisting force is generated, the flow chart of FIG. 32 → Step 33 → Step 35 → Step 3
The flow proceeds from 7 to step 38, the lane following control gain G is set to Gb (> Ga), and the motor current I that gives the target steering torque Tr to the steering force transmission system is output to the motor 7. Further, if the assist force characteristic of the hydraulic power steering device is such that an assist force that is considerably smaller than a normal assist force is generated, FIG.
In the flowchart of FIG.
1 → Step 32 → Step 33 → Step 36 → Step 37 → Step 38, the lane following control gain G is set to Gc (> Gb), and the motor current for giving the target steering torque Tr to the steering force transmission system. I is output to the motor 7.

As described above, when the assist force characteristic of the hydraulic power steering apparatus is detected and the change level of the assist force characteristic is determined, the lane following control gain G is set according to the determined assist force characteristic. Regardless of the determined change in the assist force characteristic, the lane following control characteristic is corrected so as to achieve the same lane following control as when the hydraulic power steering device is operating normally.

Therefore, for example, when the characteristic of the hydraulic power steering device is changed to a characteristic in which the assist force is lower than that in a normal state, the reduced assist force is replaced by the motor 7.
Thus, stable lane following control performance can be realized irrespective of the characteristic change of the hydraulic power steering device, such that the lane following control is performed while replenishing.

[Assist Force Control Process] FIG. 3 is a flowchart showing a flow of assist force control process started by the driver's steering in the steering assist control unit and the oil temperature compensation control unit of the lane following controller 12. Will be described.

In step 40, the power steering pressure information from the hydraulic pressure sensor 18, the steering angle information from the steering angle sensor 10, and the power steering oil temperature information from the oil temperature sensor 20 are read.

In step 41, it is determined whether or not there is no power steering pressure and the assist failure has occurred even though the power steering pressure must be generated in the hydraulic power steering apparatus during steering. If YES, the process proceeds to step 42,
If NO, the process proceeds to step 46.

In step 42, the restriction on the output to the motor 7 is released, and the routine proceeds to step 43.

In step 43, it is determined from the steering angle information or the CCD camera information whether or not the vehicle is traveling straight. If NO, the process proceeds to step 44, and if YES, the process proceeds to step 45.

At step 44, a control command for obtaining the maximum assist force from the maximum motor current is output to the motor 7.

In step 45, if it is determined in step 43 that the vehicle is traveling straight, a control command is output to the motor 7 to gradually reduce the motor current from the maximum motor current to zero.

In step 46, if it is determined in step 41 that there is no assist failure, dynamic characteristic oil temperature compensation is performed so that the gain characteristic with respect to the steering frequency of the hydraulic power steering apparatus is constant regardless of the oil temperature. Then, the process proceeds to step 47.

In step 47, static characteristic oil temperature compensation is performed to make the assist force characteristic with respect to the steering angle of the hydraulic power steering apparatus constant regardless of the oil temperature.

At step 48, an assist control command corresponding to the steering angle and the steering speed (the time derivative of the read steering angle) is output to the motor 7.

[Steering Assist Control Action at the Time of Failure] When it is detected that the hydraulic power steering apparatus is at the failure of the assist, step 4 in the flowchart of FIG.
The flow proceeds from 0 → step 41 → step 42 → step 43 → step 44, and a steering assist force is applied using the motor 7 as a steering actuator instead of the hydraulic power steering device.

Therefore, in the conventional system, when the hydraulic power steering device fails in assist during turning due to manual steering, the steering assist force is lost, so that a sudden change in the steering force occurs, giving the driver an uncomfortable feeling. become. On the other hand, at the time of assist failure, the control for applying the steering assist force using the motor 7 as the steering actuator instead of the hydraulic power steering device is performed, so that a sudden change in the steering force at the time of the assist failure can be prevented. Can be prevented.

Referring to the specific steering assist control by the lane following control system instead of the hydraulic power steering system, as shown in FIG. 4, when the control is started due to the assist failure, the lane following control is first performed. The maximum assist control mode in which the output limitation to the motor 7 at the time is removed and the maximum output command is issued. When straight running is detected during the maximum assist control mode, the assist force decrease control mode is performed in which the assist force is gradually reduced. Further, the manual steering is started when the assist force becomes zero due to the decrease in the assist force. Manual steering mode.

That is, in the lane following control, the motor 7
Usually, the output of the motor current is limited so that only the output of the steering force by the driver is generated, but when the assist fails, the output is removed and the necessary output is generated as the steering assist force. However, if the maximum output is continued, the motor 7 may be damaged in a certain period of time due to the insufficient performance of the motor 7. Therefore, the assist force is gradually reduced within a time period that does not lead to damage, and finally, the manual steering is performed. The gradual reduction of the assist force is performed when the vehicle goes straight without requiring the steering assist force.

Thus, even if an assist failure occurs at the time of steering, immediately entering the maximum assist control mode suppresses a sudden change in the steering force due to the high assist ability, and confirms straight running to confirm the assist force reduction control. By entering the mode and canceling the assist force on the lane following control system side, it is possible to prevent the motor 7 from being damaged without giving the driver an uncomfortable feeling of canceling the assist force.

[Operation of Oil Temperature Compensation Control at No Failure] When it is detected that the hydraulic power steering apparatus is not in the assist failure state, step 40 in the flowchart of FIG.
→ Step 41 → Step 46 → Step 47 → Step 48. The assist force by the motor 7 is added to the assist force by the hydraulic power steering device, so that a constant power steering characteristic is maintained regardless of the oil temperature. Keep oil temperature compensation is performed.

Therefore, in the case of a hydraulic power steering apparatus, a sufficient assist force may not be generated at a low oil temperature due to the effect of the viscosity of the oil. On the other hand, if the hydraulic power steering system detects that there is no assist failure, oil temperature compensation is performed to maintain a constant power steering characteristic regardless of the oil temperature. Stable power steering characteristics can be realized.

The specific oil temperature compensation control by the lane following control system will be described. As shown in FIG. 5, the dynamic characteristic oil temperature compensation uses a gain characteristic with respect to a steering frequency f of a hydraulic power steering apparatus as shown in FIG. The compensation is kept constant regardless of The static characteristic oil temperature compensation is shown in FIG.
As shown in (1), compensation for making the assist force characteristic with respect to the steering angle of the hydraulic power steering device constant regardless of the level of the oil temperature is performed.

Accordingly, the gain characteristic in which the oil temperature is stable from a low temperature to a high temperature by dynamic characteristic oil temperature compensation, that is, the response to the steering speed becomes constant regardless of the oil temperature, and the oil temperature becomes low to high temperature by the static characteristic oil temperature compensation. Until then, the assist force characteristic with respect to the steering angle becomes constant irrespective of the oil temperature, and a stable power steering characteristic including a transient response can be realized.

Next, the effects will be described.

(1) When the assist force characteristic of the hydraulic power steering apparatus is detected and the change level of the assist force characteristic is determined, the lane following control gain G is set according to the determined assist force characteristic, and is determined. Irrespective of the change in the assist force characteristic, the lane following control characteristic is corrected so as to achieve the same lane following control as when the hydraulic power steering device is normal. Thus, stable lane following control performance can be realized.

(2) If it is detected that the assist of the hydraulic power steering device has failed, the motor 7 serving as a steering actuator is used instead of the hydraulic power steering device.
Since the steering assist force is applied by using the above, it is possible to prevent a sudden change in the steering force when the assist fails.

(3) The steering assist control by the lane following control system in place of the hydraulic power steering device is as follows.
When the control is started due to the assist failure, the maximum assist control mode in which the output limit to the motor 7 during the lane following control is removed and the maximum output command is issued is set. If the assist force is reduced, the assist force decrease control mode is set to gradually reduce the assist force, and the manual steering mode is set to the manual steering when the assist force becomes zero due to the decrease in the assist force. As a result, a sudden change in the steering force can be suppressed, and the assist force released after confirming the straight running can be prevented from damaging the motor 7 without giving the driver an uncomfortable feeling of the assist force release.

(4) When it is detected that the hydraulic power steering device is not in the assist failure state, the assist force of the motor 7 is added to the assist force of the hydraulic power steering device, and a constant power is maintained regardless of the oil temperature. Since oil temperature compensation for maintaining the power steering characteristics is performed, stable power steering characteristics can be realized from a low oil temperature to a high oil temperature.

(5) The oil temperature compensation control by the lane-following control system is based on the steering frequency f of the hydraulic power steering device.
The dynamic characteristic oil temperature compensation that keeps the gain characteristic of the hydraulic power steering device constant regardless of the oil temperature, and the static characteristic oil temperature compensation that makes the assist force characteristic for the steering angle of the hydraulic power steering device constant regardless of the oil temperature. As a result, the response to the steering speed becomes constant irrespective of the oil temperature, and the assist force to the steering angle becomes constant irrespective of the oil temperature, so that stable power steering characteristics including transient response can be realized.

(Other Embodiments) In the first embodiment, an example in which the present invention is applied to a control device that applies a steering torque when following a lane is described. However, the first embodiment is applied to a control device that applies a steering reaction torque when following a lane. May be. In this case, control is performed such that the greater the degree of driver intervention, the smaller the steering reaction torque.

In the first embodiment, an example in which the control gain is changed stepwise based on the assist force characteristic determination has been described.
For example, an example in which the control gain is changed steplessly according to the characteristic deviation may be used.

In the first embodiment, an example of application to a hydraulic power steering device has been described. However, the present invention can be applied to an electric power steering device using a motor. In this case, a fail-safe operation signal of the electric power steering is transmitted. The monitoring may be performed, and the correction control of the lane following control characteristic or the assist control in the lane following control system may be performed.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing a vehicle steering system to which a lane following device according to a first embodiment is applied.

FIG. 2 is a flowchart illustrating a flow of a lane following control process started by an ON operation of an automatic steering switch in a lane following controller of the lane following controller according to the first embodiment.

FIG. 3 is a flowchart showing a flow of an assist force control process started by steering by a driver in a steering assist control unit and an oil temperature compensation control unit of the lane following controller according to the first embodiment.

FIG. 4 is a time chart when assist control is performed by the lane-following control device according to the first embodiment when an assist failure occurs.

FIG. 5 is a gain characteristic diagram illustrating dynamic characteristic oil temperature compensation in the lane following control device according to the first embodiment when a non-assist failure occurs.

FIG. 6 is an assist force characteristic diagram for explaining static characteristic oil temperature compensation in the lane following control device of the first embodiment when a non-assist failure occurs.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 steering wheel 2 steering shaft 3 universal joint 4 rack and pinion type steering gear box 5 side rod 6 worm wheel gear 7 motor 8 worm gear 9 electromagnetic clutch 10 steering angle sensor 11 CCD camera 12 lane following controller 13 automatic steering switch 14 steering torque sensor 15 Power steering controller 16 Vehicle speed sensor 17 Engine rotation sensor 18 Oil pressure sensor 19 Power steering solenoid 20 Oil temperature sensor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D032 CC02 CC08 CC20 CC21 CC34 CC46 DA03 DA09 DA15 DA16 DA23 DA49 DA52 DA53 DA76 DA77 DA84 DA88 DA91 DC03 DC33 DC34 DC38 DD02 DD06 DD17 DE02 EA01 EB04 EB11 EB12 EC01 EC23 EC27 GG01 5H180 A01 CC04 CC24 LL01 LL02 LL09

Claims (5)

[Claims] 1. A steering actuator provided in a steering force transmission system for applying a steering torque or a steering reaction torque, a lane information detecting means for detecting a lane state of a road ahead, and a target which is a traveling lane of a target vehicle. A lane tracking device comprising: a target line setting device on which a line is set; and a lane tracking control device for outputting a control command for causing the vehicle to follow the set target line to the steering actuator during lane tracking control. An assist force characteristic detecting means for detecting an assist force characteristic of the power steering device provided in the steering force transmission system; an assist force characteristic determining means for determining the detected assist force characteristic; and the determined assist force characteristic. Irrespective of the change of the vehicle, the lane following control characteristics are set to achieve the same lane following control as when the power steering device is normal. Lane keeping apparatus characterized by comprising: a lane following control characteristic correcting means for correcting. 2. The lane following device according to claim 1, wherein when the lane following control unit detects that the power steering device has failed, the steering assist is performed by using a steering actuator instead of the power steering device. A lane following device provided with a steering assist control unit for applying force. 3. The lane following device according to claim 2, wherein the steering assist control unit removes an output restriction to a steering actuator during the lane following control when it is detected that the power steering device has failed. The maximum assist control mode that outputs the maximum output command at the same time, the assist force decrease control mode that gradually reduces the assist force when straight running is detected during the maximum assist control mode, and the assist force A lane following device which is a control unit in a manual steering mode in which manual steering is performed at a point in time. 4. The lane following device according to claim 1, wherein the power steering device is a hydraulic power steering device that obtains an assist force by hydraulic pressure, and the lane following control means includes a power steering device. If it is detected that there is no failure, an oil temperature compensation control unit that performs oil temperature compensation that maintains constant power steering characteristics regardless of the oil temperature by adding the assist force of the steering actuator to the assist force of the power steering device A lane following device provided. 5. The lane following device according to claim 4, wherein the oil temperature compensation control unit is configured to perform dynamic characteristic oil temperature compensation for making a gain characteristic with respect to a steering frequency of a power steering device constant regardless of the level of the oil temperature. A lane following device comprising a control unit for compensating static force oil temperature to make the assist force characteristic with respect to the steering angle of the power steering device constant regardless of the oil temperature.