JPH10301625A - Automatic steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately suppress and prevent the noise of horizontal displacement and to make the responsiveness and accuracy of control be compatible by changing the characteristics of a low-pass filter corresponding to traveling state information detected in a traveling state information detection means by a control means. SOLUTION: The detection signals of a magnetic sensor 1 are outputted to a horizontal displacement detector 2 and the horizontal displacement detector 2 detects the direction size of the horizontal displacement to a lane of a vehicle from the vertical and horizontal component ratio of a detected magnetic force vector. At the time of controlling a steering actuator whose target is the detected horizontal displacement of the vehicle by an automatic steering control unit 13 which is the control mans, the automatic steering control unit 13 changes the characteristics of the low-pass filter corresponding to the traveling state information detected in the traveling state information detection means such as a steering angle sensor 3, a car speed sensor 4 and a lane curvature detector 16, etc. Thus, the noise of the horizontal displacement is surely prevented and the responsiveness and accuracy of the control are made compatible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic steering apparatus for a vehicle that automatically steers the vehicle so that the vehicle travels along a lane.

[0002]

2. Description of the Related Art An example of such a conventional automatic steering device for a vehicle is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-81602.

An automatic steering apparatus for a vehicle described in this conventional example defines steering characteristics so that more artificial steering is performed when traveling along various conditions related to steering, particularly, a curve. It is. As a result, the occupant is given a more natural driving feeling and a more comfortable ride.

[0004]

By the way, the vehicle automatic steering apparatus described in the above-mentioned publication discloses road information, more specifically, the state of a lane, that is, whether it is a straight road or a curved road, It is assumed that information such as how much the curvature is obtained from image information of a camera or the like. On the other hand, a magnetic force source such as a magnet called a magnetic nail is buried along the lane,
This is detected by a magnetic sensor attached to the vehicle, and the lateral displacement of the vehicle (lateral position information with respect to the magnetic force source, that is, the own vehicle position information with respect to the lane) is detected. In some cases, the front wheel or the rear wheel is steered by an actuator so as to match the lateral displacement described below.
In principle, the magnetic source is buried in the center of the lane,
The relative positional relationship between the magnetic sensor and the vehicle does not change.

[0005] However, if such an automatic steering device is mounted on an actual vehicle to perform automatic steering, the accuracy of control may be reduced. And this is
It was also found that the detected lateral displacement noise was caused by changing according to the running state of the vehicle, and that such an automatic steering device was constructed by a discretized system.

The present invention has been developed in view of these problems. For example, the characteristics of the low-pass filter and the correction of the observer can be changed according to the running state of the vehicle, and the noise of the detected lateral displacement can be accurately detected. It is an object of the present invention to provide an automatic steering device capable of achieving both control responsiveness and accuracy by preventing the above-mentioned suppression.

[0007]

In order to achieve the above object, an automatic steering apparatus for a vehicle according to a first aspect of the present invention includes a magnetic sensor for detecting a magnetic force source embedded along a lane, Lateral displacement detecting means for detecting the lateral displacement of the vehicle from the detection signal of the magnetic sensor, a low-pass filter for removing noise of the lateral displacement detected by the lateral displacement detecting means, and a steering actuator for steering a front wheel or a rear wheel And steering angle detection means for detecting a steering angle of a front wheel or a rear wheel steered by the steering actuator; traveling state information detection means for detecting information relating to the traveling state of the vehicle; and the detected lateral displacement of the vehicle. Control means for controlling the steering actuator so as to achieve a target lateral displacement, wherein the control means responds to traveling state information detected by the traveling state information detecting means. It is characterized in that a filter characteristic changing means for changing the characteristics of the low-pass filter.

According to a second aspect of the present invention, there is provided an automatic steering apparatus for a vehicle according to the first aspect, further comprising a lane curvature detecting means for detecting a lane curvature as the traveling state information detecting means. The filter characteristic changing means,
The characteristic of the low-pass filter is enhanced as the curvature of the lane detected by the lane curvature detecting means increases.

According to a third aspect of the present invention, there is provided an automatic steering apparatus for a vehicle according to the first or second aspect, further comprising a vehicle speed detecting means for detecting a vehicle speed as the traveling state information detecting means. The filter characteristic changing means is characterized in that the characteristic of the low-pass filter is enhanced as the vehicle speed detected by the vehicle speed detecting means increases.

According to a fourth aspect of the present invention, in the vehicle automatic steering apparatus according to any one of the first to third aspects, the magnetic sensor serves as the traveling state information detecting means in a lateral direction of the vehicle. A sensor side slip speed detecting unit for detecting a forward sensor side slip speed, wherein the filter characteristic changing unit enhances the characteristics of the low-pass filter as the speed detected by the sensor side slip speed detecting unit increases. It is.

According to a fifth aspect of the present invention, in the automatic steering apparatus for a vehicle according to the second aspect, the low-pass filter is constituted by a first-order lag filter, and the filter characteristic change is performed. The means enhances the characteristics of the low-pass filter by increasing the time constant of the first-order lag filter.

According to a sixth aspect of the present invention, in the vehicle automatic steering apparatus according to the second aspect, the low-pass filter calculates a moving average of a lateral displacement sampled. The moving average calculating means is provided, and the filter characteristic changing means enhances the characteristics of the low-pass filter by increasing the number of lateral displacements sampled by the moving average calculating means.

According to another aspect of the present invention, there is provided an automatic steering apparatus for a vehicle, comprising: a magnetic sensor for detecting a magnetic force source embedded along a lane; and detecting a lateral displacement of the vehicle from a detection signal of the magnetic sensor. Lateral displacement detecting means, a steering actuator for steering a front wheel or a rear wheel, a steering angle detecting means for detecting a steering angle of a front wheel or a rear wheel steered by the steering actuator, and detecting information on a running state of the vehicle. Traveling state information detecting means, and estimating a state quantity of the vehicle including at least an estimated lateral displacement value of the vehicle from the traveling state information detected by the traveling state information detecting means; State amount estimating means capable of correcting a state amount estimated value of the vehicle in accordance with an error with respect to the lateral displacement of the vehicle, and the steering actuator so that the estimated lateral displacement value of the vehicle becomes a target lateral displacement. And control means for controlling over data,
The control means includes correction changing means for changing correction of the state quantity of the vehicle by the state quantity estimating means in accordance with the running state information detected by the running state information detecting means. is there.

The automatic steering apparatus for a vehicle according to claim 8 of the present invention, in the invention according to claim 7, further comprises a lane curvature detecting means for detecting a lane curvature as the traveling state information detecting means. The correction change unit weakens the correction of the estimated state value of the vehicle by the state amount estimation unit as the curvature of the lane detected by the lane curvature detection unit increases.

According to a ninth aspect of the present invention, an automatic steering apparatus for a vehicle according to the seventh or eighth aspect further comprises a vehicle speed detecting means for detecting a vehicle speed as the traveling state information detecting means. The correction changing unit weakens the correction of the estimated state value of the vehicle by the state amount estimating unit as the vehicle speed detected by the vehicle speed detecting unit increases.

According to a tenth aspect of the present invention, in the automatic steering apparatus for a vehicle according to the seventh aspect, the magnetic sensor as the traveling state information detecting means is provided in a lateral direction of the vehicle. A sensor side slip speed detecting unit that detects a forward sensor side slip speed, wherein the correction changing unit is configured to detect a vehicle state amount estimated value by the state amount estimating unit as the vehicle speed detected by the sensor side slip speed detecting unit increases. It is characterized in that the correction is weakened.

In the automatic steering apparatus for a vehicle according to claim 11 of the present invention, in the invention according to any one of claims 8 to 10, the state quantity estimating means comprises a Kalman filter, and In the Kalman filter, the correction of the state quantity of the vehicle is weakened by reducing a gain relating to an error between the estimated lateral displacement and the detected lateral displacement.

[0018]

Thus, according to the automatic steering apparatus for a vehicle according to the first aspect of the present invention, the magnetic force of the magnetic force source embedded along the lane is detected by the magnetic sensor, and the detection signal is obtained from the detection signal. Detecting the lateral displacement of the vehicle and controlling the steering actuator so that the detected lateral displacement matches the target lateral displacement to automatically steer the front wheel or the rear wheel, according to the traveling state information of the vehicle, Since the configuration of the low-pass filter for removing the noise of the detected lateral displacement is changed, as the vehicle, that is, the relative speed between the magnetic sensor and the magnetic force source increases, the characteristic of the low-pass filter, that is, the high-frequency removal characteristic, By increasing the strength, the accuracy of the control can be improved by removing the noise associated with the discretization, and when the relative speed between the vehicle, that is, the magnetic sensor and the magnetic force source is low, the low-power It is possible to a response delay of the filter reduced to improve the responsiveness of the control.

According to the automatic steering apparatus for a vehicle according to the second aspect of the present invention, the curvature of the lane in which the vehicle is traveling is detected, and the larger the curvature of the lane, the more the magnetic sensor and the magnetic force source become. Since the relative speed in the lateral direction, that is, the side slip speed, is large, the larger the curvature, the stronger the high-frequency removal characteristics of the low-pass filter, so that the noise accompanying the discretization is reliably removed, and the control accuracy is improved. ,
When the curvature of the lane is small, the response delay can be reduced to increase the control response.

According to the automatic steering apparatus for a vehicle according to the third aspect of the present invention, as the detected vehicle speed increases, the relative speed of the magnetic sensor and the magnetic force source in the front-rear direction increases. As the value increases, the high-frequency removal characteristics of the low-pass filter are strengthened to reliably remove the noise associated with the discretization and improve the accuracy of the control. When the vehicle speed is low, the response delay is reduced to enhance the control response. It is also possible.

Further, according to the automatic steering apparatus for a vehicle according to the fourth aspect of the present invention, the sensor side slip speed at which the magnetic sensor advances in the lateral direction of the vehicle, that is, the relative lateral displacement of the magnetic sensor and the magnetic force source. By detecting the skid speed, the higher the sensor skid speed, the stronger the high-frequency removal characteristics of the low-pass filter to reliably remove the noise associated with discretization and improve the control accuracy. It is also possible to increase the control response by reducing the response delay.

According to the automatic steering apparatus for a vehicle according to the present invention, the low-pass filter is constituted by a first-order lag filter, and the first-order lag filter is used in accordance with the information on the running state of the vehicle as described above. By enhancing the characteristics of the low-pass filter by increasing the time constant of the delay filter, the automatic steering apparatus according to any one of claims 1 to 4 can be implemented.

According to the automatic steering apparatus for a vehicle according to the sixth aspect of the present invention, the low-pass filter is constituted by a moving average calculating means for calculating a moving average of the sampled lateral displacement. 5. The automatic steering apparatus according to claim 1, wherein the characteristic of the low-pass filter is enhanced by increasing the number of lateral displacements sampled by the moving average calculating means in accordance with the information on the running state of the vehicle. Can be

According to the automatic steering apparatus for a vehicle according to the present invention, the magnetic force of a magnetic force source embedded along the lane is detected by the magnetic sensor, and the lateral displacement of the vehicle is detected from the detection signal. And at the same time estimating the state quantity of the vehicle including at least the estimated lateral displacement value of the vehicle from the detected traveling state information of the vehicle, according to the error between the estimated lateral displacement value and the detected lateral displacement. Correcting the state quantity of the vehicle to be estimated, upon controlling the steering actuator so that the lateral displacement estimated value matches the target lateral displacement and automatically steering the front wheel or the rear wheel, according to the traveling state information of the vehicle, Since the correction of the estimated vehicle state quantity is changed, the correction of the estimated vehicle state quantity is weakened as the relative speed between the vehicle, that is, the magnetic sensor and the magnetic force source increases. In addition to removing the influence of the noise accompanying the discretization of the lateral displacement on the correction of the estimated state value of the vehicle, the accuracy of control can be improved, and the relative speed between the vehicle, that is, the magnetic sensor and the magnetic force source is reduced. When the value is small, it is possible to increase the correction and enhance the response of the control.

According to the automatic steering apparatus for a vehicle according to claim 8 of the present invention, the curvature of the lane in which the vehicle is traveling is detected, and the larger the curvature of the lane, the more the magnetic sensor and the magnetic force source become. Since the relative speed in the lateral direction of the vehicle, that is, the side slip speed, is large, the greater the curvature, the weaker the correction of the estimated state of the vehicle, thereby ensuring the effect of noise accompanying the discretization of the detected lateral displacement. , Control accuracy can be improved, and when the curvature of the lane is small, the correction can be enhanced to increase the control responsiveness.

According to the automatic steering apparatus for a vehicle according to the ninth aspect of the present invention, as the detected vehicle speed increases, the relative speed of the magnetic sensor and the magnetic force source in the front-rear direction increases. As the vehicle speed becomes larger, the correction of the estimated state of the vehicle is weakened, thereby reliably suppressing the influence of noise accompanying the discretization of the detected lateral displacement and improving the control accuracy. Can be increased to increase control responsiveness.

According to the automatic steering apparatus for a vehicle according to the tenth aspect of the present invention, the sensor side slip speed at which the magnetic sensor advances in the lateral direction of the vehicle, that is, the relative lateral displacement of the magnetic sensor and the magnetic force source. The sensor detects the skid speed, and as the skid speed increases, the correction of the estimated state of the vehicle is weakened, so that the influence of noise due to the discretization of the detected lateral displacement is reliably suppressed and the control accuracy is improved. When the sensor skid speed is low, it is possible to enhance the correction and enhance the control responsiveness.

According to the automatic steering apparatus for a vehicle according to the eleventh aspect of the present invention, the state quantity estimating means is constituted by a Kalman filter, and the Kalman filter is used in accordance with the information on the running state of the vehicle as described above. 11. The automatic steering apparatus according to claim 7, wherein the correction of the state quantity of the vehicle is weakened by reducing a gain relating to an error between the estimated lateral displacement and the detected lateral displacement. it can.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. Here, an automatic steering device that steers only the front wheels will be described.

FIG. 1 is a schematic diagram showing an automatic steering system according to a first embodiment of the present invention. Reference numeral 12 in the figure denotes front left and right wheels, and reference numeral 15 denotes rear right and left wheels. The front left and right wheels 12 are provided with a very common rack and pinion type steering mechanism. The steering mechanism includes a rack 11 connected to a steering shaft (tie rod) of front left and right wheels 12, a pinion 10 meshing with the rack 11, and a steering wheel 1
And a steering shaft 9 rotated by the steering torque given to the steering shaft 4.

The steering shaft 9 includes:
An automatic steering mechanism for automatically steering the front left and right wheels 12 is also added. The automatic steering mechanism includes a driven gear 8 coaxially mounted on the steering shaft 9, a drive gear 7 meshing with the driven gear 8, and a motor 5 for rotating the drive gear 7. Note that a clutch mechanism 6 is interposed between the motor 5 and the drive gear 7, and the clutch mechanism 6 is connected only during automatic steering control. Otherwise, the clutch mechanism 6 is separated and the torque of the motor 5 is increased. Is not input to the steering shaft 9. These mechanisms constitute a steering actuator, and the automatic steering mechanism including the motor 5 is controlled by a control signal from an automatic steering control unit 13 which is control means described later.

Further, the vehicle is provided with various sensors as running state information detecting means. Reference numeral 3 denotes a steering angle sensor (steering angle detection means) to the automatic steering control unit 13 indexes the actual front wheel steering angle [delta] _f of the front left and right wheels 12 from the rotation angle of the steering shaft 9.
Reference numeral 4 in the figure denotes a vehicle speed sensor, for example, which determines the moving speed (vehicle speed v) of the vehicle from the rotation speed of the output shaft of the transmission, and outputs it to the automatic steering control unit 13.
Reference numeral 16 in the figure denotes a lane curvature detecting device that detects the curvature of the lane. For example, the lane curvature information wirelessly transmitted from the side of the lane is obtained, and the lane curvature ρ is output to the automatic steering control unit 13. The lane curvature detecting device may be softwareized so as to be configured by arithmetic processing executed in the control unit 13, and its brief contents will be described later.

On the other hand, the magnetic force of a magnet (not shown) buried along the lane as a magnetic force source is detected by a magnetic sensor 1 attached to a lower front part of the vehicle. This magnetic sensor 1
Decomposes not only the magnitude of the magnetic force of the magnet but also its magnetic force vector into a vertical component corresponding to the vehicle vertical direction and a horizontal component corresponding to the vehicle width direction, and calculates the respective directions and magnitudes. Can be detected.

The detection signal of the magnetic sensor 1 is output to a lateral displacement detecting device 2 constituting a lateral displacement detecting means. The lateral displacement detecting device 2 calculates the direction and magnitude of the lateral displacement of the vehicle (strictly speaking, the magnetic sensor 1) with respect to the lane (strictly speaking, the magnet) based on the vertical and horizontal component ratio of the detected magnetic force vector based on the principle described later. Is detected (calculated). Since the lateral displacement detecting device 2 is constituted by a discrete digital system such as a microcomputer (not shown), the sampling of the lateral displacement as described above is performed only at a preset sampling timing. The lateral displacement y of the vehicle detected by the lateral displacement detecting device 2 is output to an automatic steering control unit 13 which constitutes a control means and performs automatic steering control.

The automatic steering control unit 13
Is composed of a discretized digital system such as a microcomputer (not shown). This digital system, like an existing microcomputer, has an input interface circuit for reading detection signals from the sensors, a storage device such as a ROM and a RAM for storing necessary programs and calculation results, and an actual storage device. An arithmetic processing device such as a microprocessor unit which performs arithmetic processing and has a certain buffer mechanism, an output interface circuit for outputting a control signal set by the arithmetic processing device to the motor 5 of the automatic steering mechanism, etc. It has.

Next, the arithmetic processing of the present embodiment executed in the control unit 13 will be described with reference to the flowchart of FIG. Although this flowchart does not particularly include a step for exchanging information, the information read by the arithmetic processing unit, the physical quantity, or the calculated operation result is updated and stored in the storage device at any time. Necessarily, programs, maps, tables, and the like are read from the storage device to the buffer of the arithmetic processing device at any time.

This arithmetic processing is executed as a timer interrupt processing at every preset sampling time ΔT of, for example, 10 msec. First, at step S1, the lateral displacement y from the lateral displacement detecting device 2 is read.

Next, the process proceeds to step S2, where the lane curvature ρ from the lane curvature detector 16 is read. Next, the process proceeds to step S3, where the vehicle speed v from the vehicle speed sensor 4 is read.

[0039] Next, the process proceeds to step S4, and calculates the sensor side-slip velocity v _s in accordance with one formula below. The following 1
The principle of calculating the formula will be described in detail later. v _s = L _s · ρ · v + v · b · ρ − (m · a · ρ · v ³ ) / ((a + b) · C _r ) (1) where L _{s is the} magnetic sensor and the center of gravity of the vehicle. A: the distance between the front wheel axle and the center of gravity of the vehicle in plan view b: the distance between the rear axle and the center of gravity of the vehicle in plan view m: vehicle mass _Cr : the cornering stiffness of the rear left and right two wheels.

Next, the process proceeds to step S5, where the time constant τ of the low-pass filter is set, for example, according to the control map of FIG. In this control map, the horizontal axis represents the vehicle speed v, further sensors side-slip velocity v _s as parameters, sets the time constant τ of the low-pass filter to the vertical axis. And the vehicle speed v
The larger and the time constant τ of the low-pass filter as the sensor side slip velocity v _s is large is set quadratically larger. It is also possible to use the lane curvature ρ in lieu of or in addition to the side-slip velocity v _s as described below.

Next, the process proceeds to step S6, where the first-order lag transfer function G represented by the following equation (10) is added to the read lateral displacement using the time constant τ set in step S5.
by performing low-pass filtering process consisting of _(s), the high-frequency component, i.e. the lateral displacement which the noise components have been removed (hereinafter, simply referred to as noise removal lateral displacement) calculating the y _L.

G _(s) = 1 / (τS + 1) (10) Next, the process proceeds to step S7, where the noise removal lateral displacement y is calculated.
_{Using L} , vehicle speed v, and lane curvature ρ, the target front wheel steering angle δ _fd is calculated and set according to the following equations (2) to (4). The calculation principle of each calculation formula will be described later in detail. Further, the proportional gain K _p in Equation 4, the derivative gain K _d, respectively is the integral gain K _i, both a function of the vehicle speed v and the lane curvature [rho, the vehicle speed v
Increases, and as the lane curvature ρ increases,
The calculated corrected front wheel steering angle Δδ _fd is set to be small. In addition, _δf0 calculated by Equation 3 is defined as a steady front wheel steering angle that is constantly set according to the curvature of the lane.

Δ _fd = δ _f0 + Δδ _fd (2) δ _f0 = (a + b) · ρ + (m · ρ · v ² · (b · C _r −a · C _f )) / ((a + b)・ C _f・ C _r ) (3) Δδ _fd = (K _p + K _d・ S + K _i / S) ・ (y _L −y _d ) (4) where C _f : front left and right two wheels Cornering stiffness S: Laplace operator.

Further, _let y _d be the target lateral displacement. Next, the process proceeds to step S8, where the set target front wheel steering angle δ _{fd is set.}
And creating a control signal for feedback control to match the actual front wheel steering angle [delta] _f and outputs return to the main program to.

Next, the calculation principle of the above equation (1) will be described. The equations of motion when the rear wheels are not steered as in the present embodiment, that is, when the rear wheel steering angle is always zero, are expressed by the following equations 5 and 6 using a two-wheel model.

M · v · (ψ ′ + β ′) = C _f · (δ _f − (a · ψ ′ + v · β) / v) + C _r · (− (v · β−b · ψ ′) / v ) (5) I · ψ ″ = a · _Cf · (δ _f − (a · ψ ′ + v · β) / v) −b · _Cr · (− (v · β−b · ψ) ') / V) (6) where ψ': yaw rate β ': sideslip angular velocity at the center of gravity of the vehicle β: sideslip angle at the center of gravity of the vehicle I: moment of inertia of the vehicle ψ'': yaw angular acceleration.

The yaw rate ψ ′ in the steady state of the turning motion is expressed by the following equation from the lane curvature ρ and the vehicle speed v. ψ ′ = ρ · v (7) In the steady state of the turning motion, both the sideslip angular velocity β ′ and the yaw angular acceleration ψ ″ at the center of gravity of the vehicle are zero.

The β '= ψ''= 0 ......... (8) In addition, side-slip velocity v _s of the magnetic sensor position are those given by the following formula (9) by using the yaw rate [psi' and slip angle beta.

V _s = L _s · ψ ′ + v · β (9) The above equation (1) is obtained by solving equations (5) to (9). Next, as for the calculation principles of Equations 3 and 4, when the rear wheels are not steered as in the present embodiment, that is, when the rear wheel steering angle is always zero, the steady equations in Equations 5 to 8 are used. The normal front wheel steering angle δ _f is defined as the steady front wheel steering angle δ _f0 , and this steady front wheel steering angle δ
Solving for _f0 gives the above three equations. Further, regarding the corrected front wheel steering angle Δδ _fd , assuming that the corrected front wheel steering angle δ _f0 is a correction amount by feedback control of the noise elimination lateral displacement y _L when the steady front wheel steering angle δ _f0 is given, the so-called PID control described in the fixed control theory is changed to 4 An expression is given. Note that the proportional gain K _p ,
Derivative gain K _d, because it is sufficiently well known for a reconciliation technique integral gain K _i, a description thereof will be omitted.

Next, the operation of the present embodiment will be described. Here, when a magnet is used as a magnetic force source, the principle of detecting the lateral displacement of the vehicle with respect to the lane based on the magnetic force from the magnet will be briefly described. When the line of magnetic force from the magnet is generated as shown in FIG. 8, the level (height) of the magnetic sensor is constant, so if the ratio of the vertical and horizontal components of the detected magnetic force vector is known, the magnetic sensor, that is, the vehicle, You can see how far the magnets, or lanes, are displaced laterally. In other words, if the magnetic sensor is directly above the magnet, the ratio of the vertical and horizontal components of the detected magnetic force vector becomes 1: 0, and the more it is shifted in the horizontal direction, the more the horizontal component of the detected magnetic force vector is shifted. Becomes large, and the vertical component becomes small. Further, it can be determined from the direction in which the lateral component of the magnetic force vector is generated, which of the magnetic sensor, that is, the vehicle, is deviated from the magnet, that is, the lane.

Next, the timing for detecting the lateral displacement of the vehicle with respect to the lane using this principle will be briefly described. Now, assuming that the magnetic sensor attached to the vehicle is not displaced in the lateral direction with respect to the magnet as described with reference to FIG.
As shown in FIG. 9A, assuming that the distance between the magnetic sensor and the magnet is D, the relationship between the distance D and the magnetic force appears as shown in FIG. 9B. That is, when the magnetic sensor is closest to the magnet, the detected magnetic force also becomes maximum. Therefore, when the detected magnetic force becomes the maximum, it becomes possible to accurately detect the lateral displacement of the vehicle from the vertical and horizontal component ratio of the magnetic force vector.

Therefore, in the case where the steering actuator is controlled using the detected lateral displacement so as to coincide with the target lateral displacement as described above, in the present embodiment, a low-pass filter is applied to the detected lateral displacement. To remove noise.

Next, the noise component of the lateral displacement y detected as described above will be described. In a method of detecting the magnetic force of a magnetic force source such as a magnet buried along the lane with a magnetic sensor to detect the lateral displacement of the vehicle with respect to the lane,
There are many noises (including error components) in the lateral displacement detected by the actual vehicle. This has been considered to be because, for example, as shown in FIG. 10, a magnetic force source such as a magnet is not accurately embedded in the center of the lane corresponding to the center of two white lines indicating the width of the lane. That is, if a magnetic force source such as a magnet, which should be originally located at the center of the lane, is buried with a lateral shift, the detected lateral displacement is, as shown in FIG. Even if you move along the center,
It is erroneously recognized as if it is shifted in the horizontal direction.

However, the detected noise component of the lateral displacement y also includes the following noise components. That is, the automatic steering apparatus for a vehicle as described above generally includes a digital system that is discretized because it requires advanced arithmetic processing. Therefore, for example, as described above, there is a possibility that the sampling timing when the magnetic force of the magnet is detected by the magnetic sensor differs from the timing when the magnetic sensor actually comes closest to the magnet. This possibility increases as the relative speed between the magnet and the magnetic sensor, that is, the vehicle, increases.

If this is reproduced in an actual vehicle, for example, as the vehicle speed v increases or the lane curvature ρ increases, the noise component of the detected lateral displacement increases, and as a result, the accuracy of the automatic steering control decreases. I do. Among these, the increase in the lane curvature ρ means that the angle between the moving direction of the vehicle that is to move along the lane center line and the direction in which the vehicle is actually facing, that is, the yaw angle, as shown in FIG. Is large, which means that the skid speed of the magnetic sensor is large at the same time. During a steady turning motion, the two can be evaluated as equivalent to each other. However, the difference between the magnetic force sampling timing and the closest approach timing of the magnetic sensor described above is due to the magnet and the magnetic sensor,
In other words, when it is considered that the noise component is caused by the relative speed with respect to the vehicle, it is appropriate to consider that the noise component of the detected lateral displacement increases as the sideslip speed of the magnetic sensor increases.

On the other hand, a low-pass filter for removing a noise component, that is, a high-frequency component from the lateral displacement detected in this way generally has a first-order lag transfer function.
It is expressed by an equation. The time constant τ of the denominator is called a time constant. As the time constant τ is increased, the time required for the actual value to follow the target value becomes longer, so that the followability of the high-frequency component is reduced. It is well known from classical control theory that the removal of high frequency components increases. This is generally referred to as enhancing the characteristics of the low-pass filter. Therefore, in this embodiment, as the vehicle speed v is increased, or the sensor side slip velocity v _S is greater, the time constant τ is set quadratically increases, thereby, the magnet and the magnetic sensor as described above, that is the vehicle The noise of the detected lateral displacement, which increases as the relative speed with respect to the control signal increases, is effectively removed, and the accuracy of the automatic steering control is improved. Moreover, relatively, as the vehicle speed v decreases, or the sensor side slip velocity v as _S becomes small, the time constant τ is the noise eliminating effect of the detected lateral displacement to be set small drops, thus magnet and magnetic Since the noise component of the detected lateral displacement is small when the relative speed with the sensor, that is, the vehicle, is small, the noise removing effect does not need to be so large. Rather, by setting the time constant τ to a small value, control responsiveness is improved. As described above, in the automatic steering device according to the present embodiment, the information on the traveling state such as the vehicle speed and the sensor side skid speed is obtained, and the noise removal characteristic of the low-pass filter is made variable in accordance with the traveling state information. Accuracy and responsiveness can be compatible.

As described above, this embodiment is an embodiment of an automatic steering apparatus for a vehicle according to claim 1 or 2 or 3 or 4 or 5 of the present invention. Step S1 of the arithmetic processing constitutes the lateral displacement detecting means of the present invention, and similarly, the lane curvature detecting device 16 and FIG.
2 constitutes a lane curvature detecting means and a traveling state information detecting means, and the vehicle speed sensor 4 and step S3 of the computing processing of FIG. 2 constitute a vehicle speed detecting means and a traveling state information detecting means. Step S4 of the arithmetic processing constitutes the sensor side slip speed detecting means and the traveling state information detecting means, the entire arithmetic processing of FIG. 2 and the automatic steering control unit 13 constitute the control means, and step S5 of the arithmetic processing of FIG. A characteristic changing means is constituted.

In the first embodiment, the lane curvature ρ
And the vehicle speed v to calculate the sensor side-slip velocity v _s from has been decided to set the constant τ when the first-order lag filter from both the sensor side-slip velocity v _s and the vehicle speed v, for example the sensor side slip velocity v as described above _The lane curvature ρ may be used instead of or in addition to _S , in which case the lane curvature ρ
, The time constant τ may be set larger to enhance the characteristics of the low-pass filter. Further, the low-pass filter described above may be configured by a unit that calculates a moving average of the sampled lateral displacement. In the low-pass filter including the moving average means, the greater the number of sampling lateral displacements used for the moving average, the lower the followability to the target value. Therefore, the low-pass filter according to the traveling state information as in the first embodiment. In order to enhance the characteristics of the low-pass filter, the number of sampling lateral displacements may be increased.

Next, an automatic steering system according to a second embodiment of the present invention will be described. First, since the outline of the automatic steering device provided in the vehicle is the same as that shown in FIG. 1 of the first embodiment, the description of the detailed configuration will be omitted.

The fundamental difference of the present embodiment from the first embodiment is that a Kalman filter as a state estimator is constructed in a digital system such as a microcomputer in the automatic steering control unit 13. Here, the Kalman filter will be described. Kalman filter is based on the assumption that state quantities based on modern control theory are estimated in accordance with a preset model and feedback control is performed for each of them.
As a result, when various feedbacks are eliminated and feedback control of a single state quantity is facilitated and accurate, a model is provided according to an output error between an output estimated state quantity and a detected state quantity. That is, the estimated state quantity can be corrected. Specifically, the configuration shown in FIG. 5A is obtained.

Here, the model in the Kalman filter of the present embodiment is a two-wheel model of a vehicle, and this is expressed by the following equation 12 using a state space expression. However, in the two-wheel model shown in Formula 12, the rear wheels can be steered, and the yaw moment can be controlled by the traction of the rear wheels. Therefore, as in the present embodiment, the steering of the vehicle can be performed only by steering the front wheels. In the case of controlling lateral displacement, the rear wheel steering angle δ
_It is sufficient that both _r and the yaw moment _Tr are set to zero.

[0062] Where a ₁₁ = − (C _r + C _f ) / (m · v) (12-1) a ₁₂ = (− 1+ (C _r · b−C _f · a)) / (m · v ²⁾ _{) ......... (12-2) a 21 =} (C r · b-C f · a) / I ......... (12-3) a 22 = - (C r · b 2 + C f · a 2) / (I · v)… (12-4) b ₁₁ = C _f / (m · v)… (12-5) b ₁₂ = C _r / (m · v) …… (12-6) ) b ₂₁ = C _f · a / I (12-7) b ₂₂ = −C _r · b / I (12-8) b ₂₃ = 1 / I (12-9) It is. In the present embodiment, r is the yaw rate, Δ レ イ
Is used as the yaw angle with respect to the lane, and the other symbols are the same as in the first embodiment.

In the above equation (12), in the steady running state, all of the left side, ie, the side slip angular velocity β ′ at the center of gravity of the vehicle, the yaw angular acceleration r ′, the yaw rate Δψ ′, and the lateral displacement velocity y ′ are all zero. Therefore, the following equation (14) is obtained by adding a suffix “0” to each physical quantity or state quantity at this time. Note that each state quantity in such a steady running state is defined as a state quantity around the equilibrium point.

[0064] Then, similarly to the first embodiment, the actually required steering angle and yaw moment are further corrected by a correction error generated due to a model error or the like when a steady steering angle or yaw moment around the equilibrium point is given. Is given as a feedback value, and the following equations 15-1 to 3-5 are given. Further, the same can be said for other state quantities. Equations (4) to (4) hold.

Δ_f= Δ_f0+ Δδ_f ……… (15-1) δ_r= Δ_r0+ Δδ_r ............ (15-2) T_r= T_r0+ ΔT_r ……… (15-3) β = β₀+ Δβ ……… (16-1) r = r₀+ Δr... (16-2) Δψ = Δψ₀+ Δ^Twoψ ……… (16-3) y = y₀+ Δy (16-4) Next, since there is no correction in the lane curvature ρ, Δρ is
Qualitatively zero (ie, ρ₀= Ρ)
Is solved to obtain the following equation (17). That is, here
Vector x of the obtained state quantity (corrected sideslip angle Δβ, correction
Yaw rate Δr, corrected yaw angle Δ^Twoψ, corrected lateral displacement Δy)
Is accurate, the correction from this vector
Power wheel steering angle, that is, the corrected front wheel steering angle Δδ_fdAnd the wheel after correction
Steering angle Δδ _rdAnd corrected yaw moment ΔT_rdEtc. can be calculated
Become. As described above, the rear wheel steering angle and yaw moment
In the case of this embodiment in which is not corrected,
Wheel steering angle δ_r0And steady yaw moment T_r0Or correction Δδ
_rdAnd corrected yaw moment ΔT_rdEtc. are all set to “0”
It just needs to be done.

[0066] This 17 equation is abbreviated according to the configuration diagram of the Kalman filter shown in FIG.

Dx / dt = Ax + Bu (11) That is, each vector, x, A,
B and u are summarized as follows.

[0068] Here, once away from the description of the configuration of the Kalman filter, the lane following, that is, the corrected front wheel steering angle Δδ for realizing the corrected lateral displacement Δy = 0 from the vector x of the state quantity.
_fd , the corrected rear wheel steering angle Δδ _rd and the corrected yaw moment ΔT _rd
In order to set, consider optimization control using an optimal regulator. Here, the constraint condition is the above equation 11, and the evaluation function J is given by the following equation 18.

J = ∫ (x ^T Qx + u ^T Ru) dt (18) where x ^T is the transposed vector of vector x, and u ^T is the transposed vector of vector u. Q is a symmetric non-negative definite matrix, and R is a symmetric positive definite matrix, which is generally called a weight. Since the corrected lateral displacement Δy in the vector x is the fourth row, to reduce the corrected lateral displacement Δy, it is sufficient to increase the 4-row, 4-column element of the symmetric non-negative definite matrix Q. However, it goes without saying that it is necessary to consider a trade-off in that the noise is more easily picked up by increasing the gain.

The feedback rule obtained as a conclusion is:
According to the block diagram shown in FIG. 5B, the following equation (19) is used, and when each element is listed, equation (20) is obtained. Note that K _R
Is a constant matrix.

U = −K _R · x (19) In order to set Δy = Δy _d (target lateral displacement), Becomes

That is, in this embodiment, the estimated corrected side slip angle Δβ, the corrected yaw rate Δr, and the corrected yaw angle Δ
² [psi, with respect to the correction transverse displacement [Delta] y, correction front wheel steering angle .DELTA..delta _fd will be given briefly below 21 expression.

Δδ _fd = k ₁₁ · Δβ + k ₁₂ · Δr + k ₁₃ · Δ ² ψ + k ₁₄ · (Δy−Δy _d ) (21) The corrected side slip angle Δβ excluding the corrected lateral displacement Δy in the state estimator described above. , corrected yaw rate [delta] r, when the corrected yaw angle delta ² [psi can not be detected, if constituting a state estimator using reverse the correction lateral displacement Δy and the correction front wheel steering angle .DELTA..delta _f, to estimate the amount their state Can be.

On the other hand, returning again to the description of the Kalman filter, the estimated lateral displacement y ＾ (＾ indicates an estimated value) estimated as described above is obtained by adding the corrected front wheel steering angle Δδ _fd to the aforementioned model. Substitution (In view of the straight running state, it seems that the target front wheel steering angle δ _fd should be substituted. However, the model before that, that is, the model around the equilibrium point corresponding to the steady turning state until then, will be described later. Is substantially substituted into the corrected front wheel steering angle Δ.
δ becomes _fd) to result tried, since an estimated value of the vehicle is achieved, which is referred to as estimated lateral displacement y _e. However,
There is always an error between the aforementioned model and the actual vehicle. Therefore, as shown in FIG. 5A, a deviation (hereinafter simply referred to as an output error) ε between the estimated lateral displacement y _e and the actual lateral displacement y detected as in the first embodiment is obtained, and the output is calculated. over the output error feedback gain vector K _e to the error epsilon, it corrects the model in the state estimator. Here, in order to facilitate understanding, the notation of correcting the model is used. However, since there is no problem in directly correcting each state quantity, it is assumed that the state quantity is corrected in a broad sense. Handle.

Although the magnitude of the output error feedback gain vector K _e cannot be simply compared due to the characteristics of the vector, it is clear from the above description that if the gain characteristic is large, the correction of the state quantity can be performed quickly. It can be seen that the responsiveness of control can be improved, but on the other hand, it is easily affected by noise components. Conversely, the smaller the gain characteristics of the output error feedback gain vector K _e is the correction effect of the state quantity decreases, it can be seen accuracy of control to prevent suppress the influence of noise components can be improved.

Next, the arithmetic processing of the present embodiment executed in the control unit 13 will be described with reference to the flowchart of FIG. In this flowchart, although there is no particular step for transmitting and receiving information, the transmission and reception of information is executed at any time as in the first embodiment.

This arithmetic processing is executed as a timer interrupt processing at every preset sampling time ΔT of, for example, 10 msec. First, the lateral displacement y from the lateral displacement detecting device 2 is read in step S11.

Next, the flow shifts to step S12, where the lane curvature ρ from the lane curvature detector 16 is read. Next, the process proceeds to step S13, and the vehicle speed v from the vehicle speed sensor 4 is obtained.
Read.

Next, the flow shifts to step S14, where the first
Calculating the sensor side-slip velocity v _s in accordance with the expression 1 described in the embodiment. At the next step S15, the output error feedback gain vector K _e of the Kalman filter described above, set according to the control map of FIG. 7, for example. In this control map, the horizontal axis represents the vehicle speed v, further sensors side-slip velocity v _s as a parameter for setting an output error feedback gain vector K _e on the vertical axis. Since the output error feedback gain vector _Ke is a vector as its name implies, the control map of FIG. 7 shows only the state of change of each element. When the overall appearance and gain characteristics, and, as the vehicle speed v is larger, also the larger the sensor side-slip velocity v _s, the gain characteristics of the output error feedback gain vector K _e is set quadratically smaller. It is also possible to use the lane curvature ρ in lieu of or in addition to the side-slip velocity v _s as described below.

Next, the processing shifts to step S16, where
From the vehicle speed v and the lane curvature ρ, a steady front wheel steering angle δ _f0 and a steady lateral displacement y corresponding at least around the equilibrium point are calculated according to the following equations.
Calculate ₀ .

Next, the processing shifts to step S17, where
According to the equation, the actual front wheel steering angle [delta] _f, and calculates a front wheel steering angle deviation .DELTA..delta _f from the steady front wheel steering angle [delta] _f0. Δδ _f = δ _f −δ _f0 (22) Next, the processing shifts to step S18, where
A lateral displacement deviation Δy is calculated from the detected actual lateral displacement y and steady lateral displacement y ₀ . Note that when the front-wheel automatic steering based on state estimation has already been started, the calculated steady-state lateral displacement y ₀ is substantially zero, and the detected lateral displacement y is a feedback amount for correcting the model error described above. Therefore, the detected lateral displacement y may be directly set to the lateral displacement deviation Δy.

Δy = y−y ₀ (23) Next, the flow shifts to step S 19, where each state quantity is estimated by the Kalman filter composed of the above formula (17).
The state estimation vector x is calculated.

Next, the flow shifts to step S20, where the aforementioned 19
From Equations (21) and (21), the corrected front wheel steering angle Δδ _fdIs calculated. next
Proceeding to step S21, according to the following equation (24),
The calculated corrected front wheel steering angle Δδ_fd, Steady front wheel steering angle δ_f0Or
Target front wheel steering angle δ_fdIs calculated.

[0084] _{δ fd = δ f0 + Δδ fd} ......... (24) then the process proceeds to step S22, the control signal of the feedback control for matching the actual front wheel steering angle [delta] _f on the set target front wheel steering angle [delta] _fd Create, output, and return to the main program.

Next, the operation of the present embodiment will be described. First, since the detected noise component of the lateral displacement y is the same as that described in the first embodiment, the description is omitted here.

On the other hand, when the state quantity in the Kalman filter as described above is corrected using the lateral displacement y having a large amount of noise components, the corrected state quantity itself has a large amount of error (noise). As a result, the accuracy of the control deteriorates. In this case, it is sufficient weaker correction state quantity by reducing the gain characteristics of the output error feedback gain vector K _e mentioned above. However, just because the gain characteristic of an output error feedback gain vector K _e than was the inadvertently selected small initially, when less noise error lateral displacement y is detectable, the responsiveness of the control is degraded.

[0087] Therefore, in this embodiment, the vehicle speed v increases, or the sensor side slip velocity v _S is greater, sets the gain characteristics of the output error feedback gain vector K _e quadratically smaller, thereby, the aforementioned As described above, the effect of the noise component of the detected lateral displacement, which increases as the relative speed between the magnet and the magnetic sensor, that is, the vehicle, increases, to effectively correct the estimated state variables, is effectively eliminated. Improve accuracy. Moreover, relatively, as the vehicle speed v decreases, or the sensor as the side slip velocity v _S is small, the gain characteristics of the output error feedback gain vector K _e is the effect of suppressing the influence of the detected lateral displacement of the noise to be set large However, when the relative speed between the magnet and the magnetic sensor, that is, the vehicle is small, the influence of the noise of the detected lateral displacement is small, and the effect of suppressing the noise influence may not be so large. Rather, the output error feedback gain vector K
_By setting the gain characteristic of _e large, control responsiveness is improved. As described above, in the automatic steering apparatus according to the present embodiment, information on a traveling state such as a vehicle speed and a sensor skid speed is obtained, and the state quantity correction characteristic of a state estimator such as a Kalman filter is made variable according to the traveling state information. In addition, the accuracy and responsiveness of the automatic steering control can be compatible.

As described above, this embodiment is an embodiment of an automatic steering apparatus for a vehicle according to claim 7 or 8 or 9 or 10 or 11 of the present invention. Step S11 of the arithmetic processing constitutes the lateral displacement detecting means of the present invention, and similarly, the lane curvature detecting device 16 and step S12 of the arithmetic processing of FIG. 6 constitute the lane curvature detecting means and the traveling state information detecting means, similarly. The vehicle speed sensor 4 and step S13 of the calculation processing of FIG. 6 constitute a vehicle speed detection means and a traveling state information detection means, and step S14 of the calculation processing of FIG. 6 constitutes a sensor skid speed detection means and a traveling state information detection means, Step S19 of the arithmetic processing of FIG. 6 constitutes the state quantity estimating means, the entire arithmetic processing of FIG. 6 and the automatic steering control unit 13 constitute the control means, and the processing of FIG. -Up S15 constitute a correction changing means.

In the second embodiment, the lane curvature ρ
And the vehicle speed v to calculate the sensor side-slip velocity v _s from the gain characteristics of the output error feedback gain vector K _e of the Kalman filter from both the sensor side-slip velocity v _s and the vehicle speed v, i.e. sets the state quantity correction characteristic of the state estimator However, as described above, for example, the sensor side slip speed v
_A lane curvature ρ may be used instead of or in addition to _{S. In} this case, the output error feedback gain vector K of the Kalman filter increases as the lane curvature ρ increases.
The correction of the state quantity of the state estimator may be weakened by setting the gain characteristic of _e to be small.

Further, in the first and second embodiments, only the case where the lane curvature ρ is read as information from the outside is described in detail. However, the lane curvature ρ is determined by the lateral displacement, yaw rate, yaw Since it is well known that it is represented by equations of motion such as an angle and a vehicle speed, it is also possible to estimate using these.

In the first and second embodiments, the lane following, that is, the detected lateral displacement is made to coincide with the target lateral displacement only by steering the front wheels. Or in addition to this, the rear wheels may be steered, or if the lateral displacement is controlled while focusing on the yawing motion, the traction of each of the front and rear wheels, that is, the driving force, may be controlled in addition to them. The steering characteristics may be controlled.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an automatic steering device for a vehicle according to the present invention, in which FIG. 1A is a side view and FIG. 1B is a plan view.

FIG. 2 is a flowchart illustrating a calculation process of the first embodiment of the automatic steering device for a vehicle according to the present invention.

FIG. 3 is a time constant setting map of a low-pass filter used in the calculation processing of FIG. 2;

FIG. 4 is an explanatory diagram of a skid speed of a magnetic sensor.

FIG. 5A is a block diagram illustrating an example of a Kalman filter, and FIG. 5B is a block diagram illustrating an example of an arithmetic device that outputs a control amount from an estimated state amount.

FIG. 6 is a flowchart illustrating a calculation process of a second embodiment of the automatic steering device for a vehicle according to the present invention.

7 is an output error feedback gain vector setting map of a Kalman filter used in the calculation processing of FIG. 2;

FIG. 8 is an explanatory diagram of a magnetic force vector from a magnet embedded in a lane.

FIG. 9 is an explanatory diagram for detecting a magnetic force of a magnet with a magnetic sensor attached to a vehicle.

FIG. 10 is an explanatory diagram of a magnet embedded in a lane.

FIG. 11 is an explanatory diagram of a vehicle lateral displacement obtained according to a detected magnetic force.

[Explanation of symbols]

 1 is a magnetic sensor 2 is a lateral displacement detecting device (lateral displacement detecting means) 3 is a steering angle sensor (steering angle detecting means) 4 is a vehicle speed sensor (vehicle speed detecting means) 5 is a motor 6 is a clutch mechanism 7 is a drive gear 8 is a driven gear 9 is a steering shaft 10 is a pinion 11 is a rack 12 is front left and right wheels 13 is an automatic steering control unit (control means) 14 is a steering wheel 15 is rear right and left wheels 16 is a lane curvature detector (lane curvature detector)

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B62D 113: 00

Claims (11)

[Claims] 1. A magnetic sensor for detecting a magnetic force source buried along a lane, a lateral displacement detecting means for detecting a lateral displacement of a vehicle from a detection signal of the magnetic sensor, and a lateral displacement detecting means for detecting the lateral displacement of the vehicle. A low-pass filter for removing lateral displacement noise, a steering actuator for steering a front wheel or a rear wheel, steering angle detection means for detecting a steering angle of a front wheel or a rear wheel steered by the steering actuator, and travel of the vehicle. Driving state information detecting means for detecting information on a state; and control means for controlling the steering actuator so that the detected lateral displacement of the vehicle becomes a target lateral displacement. The vehicle of claim 1, further comprising: a filter characteristic changing unit configured to change a characteristic of the low-pass filter according to the traveling state information detected by the state information detecting unit. Dynamic steering device. 2. The vehicle according to claim 1, further comprising: a lane curvature detecting unit configured to detect a curvature of a lane as the traveling state information detecting unit. 2. The automatic steering apparatus for a vehicle according to claim 1, wherein a characteristic of the filter is enhanced. 3. A vehicle speed detecting means for detecting a vehicle speed as the traveling state information detecting means, wherein the filter characteristic changing means strengthens the characteristics of the low-pass filter as the vehicle speed detected by the vehicle speed detecting means increases. The automatic steering device for a vehicle according to claim 1 or 2, wherein: 4. The apparatus according to claim 1, further comprising a sensor side slip speed detecting unit for detecting a sensor side slip speed in which the magnetic sensor advances in a lateral direction of the vehicle, wherein the filter characteristic changing unit detects the sensor side slip speed by the sensor side slip speed detecting unit. 4. The automatic steering apparatus for a vehicle according to claim 1, wherein the characteristic of the low-pass filter is strengthened as the speed of the low-pass filter increases. 5. 5. The low-pass filter is constituted by a first-order lag filter, and the filter characteristic changing means increases the time constant of the first-order lag filter to enhance the characteristics of the low-pass filter. 5. The automatic steering device for a vehicle according to any one of 4. 6. The low-pass filter includes moving average calculating means for calculating a moving average of the sampled lateral displacement, and the filter characteristic changing means increases the number of lateral displacements sampled by the moving average calculating means. The automatic steering apparatus for a vehicle according to any one of claims 2 to 4, wherein the characteristics of the low-pass filter are strengthened by doing so. 7. A magnetic sensor for detecting a magnetic force source embedded along a lane, lateral displacement detecting means for detecting a lateral displacement of a vehicle from a detection signal of the magnetic sensor, and a steering actuator for steering a front wheel or a rear wheel. Steering angle detecting means for detecting a steering angle of a front wheel or a rear wheel steered by the steering actuator; running state information detecting means for detecting information on a running state of the vehicle; and detecting by the running state information detecting means. A vehicle state quantity including at least a vehicle lateral displacement estimated value from the traveling state information, and a vehicle state quantity estimation based on an error between the vehicle lateral displacement estimated value and the detected vehicle lateral displacement. State quantity estimating means capable of correcting the value, and control means for controlling the steering actuator so that the estimated lateral displacement of the vehicle becomes a target lateral displacement,
The control unit includes a correction change unit that changes correction of a state amount of the vehicle by the state amount estimation unit according to the traveling state information detected by the traveling state information detection unit. Automatic steering device. 8. The vehicle according to claim 1, further comprising: a lane curvature detecting unit configured to detect a curvature of a lane as the traveling state information detecting unit. 8. The automatic steering apparatus for a vehicle according to claim 7, wherein the correction of the estimated state value of the vehicle by the estimation unit is weakened. 9. A vehicle speed detecting means for detecting a vehicle speed as the traveling state information detecting means, wherein the correction changing means detects a vehicle speed by the state quantity estimating means as the vehicle speed detected by the vehicle speed detecting means increases. 9. The automatic steering apparatus for a vehicle according to claim 7, wherein the correction of the estimated state value is weakened. 10. The apparatus according to claim 1, further comprising a sensor side slip speed detecting means for detecting a sensor side slip speed in which the magnetic sensor travels in a lateral direction of the vehicle, wherein the magnetic sensor detects the sensor side slip speed. 10. The automatic steering apparatus for a vehicle according to claim 7, wherein the correction of the estimated state value of the vehicle by the state amount estimating means is reduced as the vehicle speed increases. 11. The Kalman filter as the state quantity estimating means, and the correction amount changing means reduces a gain related to an error between the estimated lateral displacement and the detected lateral displacement in the Kalman filter. 11. The automatic steering apparatus for a vehicle according to claim 8, wherein the correction of the state quantity of the vehicle is weakened.