WO2019244522A1

WO2019244522A1 - Steering control device

Info

Publication number: WO2019244522A1
Application number: PCT/JP2019/019384
Authority: WO
Inventors: こずえ小林; 安井　博文; 吉修遠藤
Original assignee: 日野自動車株式会社
Priority date: 2018-06-18
Filing date: 2019-05-15
Publication date: 2019-12-26
Also published as: JP7023801B2; JP2019217853A

Abstract

This steering control device performs steering control for allowing a vehicle to travel along a target locus on the basis of detection results from a vehicle-mounted external sensor. This steering control device comprises: a lane width recognition unit that recognizes the lane width of the lane in which the vehicle is travelling; a distance recognition unit that recognizes the distance between a reference line extending along the lane and the vehicle; a variation index calculation unit that, based on the distance, calculates a variation index representing variations in the lateral position of the vehicle in the lane; a lane width threshold value calculation unit that calculates a lane width threshold value, which is a criterion for whether to allow or disallow execution of steering control, on the basis of the variation index and the vehicle width; and a steering control unit that executes steering control if the lane width is larger than the lane width threshold value.

Description

Steering control device

The present disclosure relates to a steering control device.

Conventionally, as a technology related to a steering control device, a technology of executing lane keeping assist control when a lane width exceeds a predetermined threshold is known (for example, Patent Document 1).

JP 2010-18207 A

In the steering control for traveling a vehicle along a target trajectory, when there are various factors that change the straightness of the vehicle, the vehicle travels (meanders) in a state where there is a certain amount of lateral position variation with respect to the target trajectory. . For example, in a vehicle such as a large commercial vehicle, the influence of the factors tends to appear, and the straightness of the vehicle tends to change. Therefore, it is desired to appropriately execute the steering control.

The present disclosure has an object to provide a steering control device capable of appropriately executing steering control for causing a vehicle to travel along a target locus according to a change in straightness of the vehicle.

A steering control device according to an embodiment of the present disclosure is a steering control device that performs steering control for causing a vehicle to travel along a target trajectory based on a detection result of a vehicle-mounted external sensor, and includes a lane width of a lane in which the vehicle travels. A lane width recognition unit for recognizing a vehicle, a distance recognition unit for recognizing a distance between a reference line along the lane and the vehicle, and a fluctuation index calculation unit for calculating a fluctuation index representing a lateral position fluctuation of the vehicle in the lane based on the distance. And, based on the variation index and the vehicle width of the vehicle, a lane width threshold calculation unit that calculates a lane width threshold that is a threshold of the lane width serving as a reference for permission / prohibition of the execution of the steering control, and the lane width is greater than the lane width threshold. And a steering control unit that executes the steering control when the steering angle is large.

では In the steering control device according to an embodiment of the present disclosure, the fluctuation index calculating unit calculates the fluctuation index representing the lateral position fluctuation of the vehicle in the lane. The lane width threshold calculation unit calculates a lane width threshold, which is a threshold of the lane width as a criterion for permitting or rejecting the execution of the steering control, based on the variation index and the vehicle width of the vehicle. As a result, the lane width threshold value can be calculated in consideration of the lateral position fluctuation generated according to the change in the straightness of the vehicle. Therefore, by using the appropriate lane width threshold value according to the change in the straightness, it is possible to appropriately execute the steering control for causing the vehicle to travel along the target trajectory according to the change in the straightness of the vehicle.

In the steering control device according to an embodiment of the present disclosure, the variation index calculating unit may calculate a standard deviation of the distance recognized by the distance recognizing unit at the latest predetermined traveling time or the latest predetermined traveling distance as the variation index. . In this case, it is possible to calculate the lane width threshold according to the straightness of the latest vehicle.

The steering control device according to an embodiment of the present disclosure further includes a weight distribution change recognition unit that recognizes a change in the weight distribution in the vehicle, and the fluctuation index calculation unit calculates an initial value of the fluctuation index based on the change in the weight distribution. May be. In this case, it is possible to calculate the lane width threshold according to the change in the straightness of the vehicle due to the change in the weight distribution. Therefore, for example, even when a vehicle whose weight distribution has changed while the vehicle is stopped travels, steering control can be performed using an appropriate lane width threshold value according to the change in weight distribution.

According to the present disclosure, it is possible to appropriately execute the steering control for causing the vehicle to travel along the target locus according to the straightness of the vehicle.

FIG. 1 is a schematic configuration diagram of a steering control device according to the embodiment. FIG. 2 is a schematic plan view for explaining an example of the steering control. FIG. 3 is a flowchart illustrating the steering control process. FIG. 4 is a flowchart illustrating an execution permission / prohibition determination process of the steering control. FIG. 5 is a flowchart illustrating a process of initializing a variation index.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a schematic configuration diagram of the steering control device according to the embodiment. FIG. 2 is a schematic plan view for explaining an example of the steering control. As shown in FIG. 1, a steering control device 10 according to the present embodiment is mounted on a large-sized vehicle M such as a truck, a tractor, or a bus, and is a device that automatically performs steering control of the vehicle M. The steering control device 10 may constitute a part of an automatic driving device that automatically performs driving including speed control, for example.

The steering control device 10 executes the steering control of the vehicle M so that the vehicle M automatically runs along the set target trajectory. The steering control refers to control for causing the vehicle M to travel along a target trajectory based on a detection result of an external sensor such as the vehicle-mounted camera 1 or the like. The target trajectory can be generated by the ECU 4 by an existing method based on, for example, the external environment detected by the camera 1 and the like and the map information in the map database. Note that the target trajectory here is not a trajectory from the current position of the vehicle M but a trajectory that the vehicle M should travel (ideal). Therefore, the current position of the vehicle M may be shifted from the target locus. The target trajectory may be, for example, a position represented by a coordinate system based on the vehicle M, or a position represented by latitude and longitude. Thus, the traveling of the vehicle M is controlled by the steering control device 10 so as to automatically travel along the target locus T (see FIG. 2). 2, the direction Fr indicates the front of the vehicle M, the direction Rr indicates the rear of the vehicle M, the direction R indicates the right side of the vehicle M, and the direction L indicates the left side of the vehicle M.

1, the steering control device 10 includes a camera (external sensor) 1, an input unit 2, a weight sensor 3, an ECU [Electronic Control Unit] 4, and a steering actuator 5. The ECU 4 is an electronic control unit having a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], a CAN [Controller Area Network] communication circuit, and the like. The ECU 4 loads programs stored in the ROM into the RAM and executes the programs loaded into the RAM with the CPU to realize various functions. The ECU 4 may include a plurality of electronic control units. The camera 1, the input unit 2, the weight sensor 3, and the steering actuator 5 are connected to the ECU 4 via a CAN communication circuit.

The camera 1 is an imaging device that captures an image of an external situation of the vehicle M. The camera 1 is provided, for example, behind the windshield of the vehicle M. The external situation includes a captured image obtained by capturing an area in front of and on the side of the vehicle M in the lane R in which the vehicle M travels. The captured images of the lane R include the captured images of the division lines (reference lines) W1 and W2 extending along the lane R. The division lines W1 and W2 are, for example, solid white or yellow lines that define the lane R. The division lines W1 and W2 are not limited to solid lines, and may be a broken line used as a lane center line, a wide broken line provided at a branch portion of a road, or the like. The division lines W1 and W2 may be in a form according to the regulations of each country or region. The camera 1 transmits information of the captured images of the front and side of the vehicle M to the ECU 4. The camera 1 may further image the rear of the vehicle M.

The input unit 2 receives an input operation by a driver of the vehicle M. The input unit 2 may be, for example, a physical switch or lever provided in a driver's seat, or a button on a touch panel display of a navigation system (not shown). The input operation here is an operation for adjusting a reference (a lane width threshold value described later) as to whether execution of the steering control is permitted or not (details will be described later). The input unit 2 transmits information on the received input operation to the ECU 4.

The weight sensor 3 is a detection device that detects the weight of the load on the vehicle M. The weight sensor 3 includes, for example, a plurality of sensors so as to detect the weight distribution of the load on the vehicle M. For example, when the vehicle M is a truck or a tractor, the weight sensor 3 is provided at a plurality of positions on a bed of the truck or a bed of a trailer towed by the trailer, and detects a weight distribution of the load placed on the bed. The weight distribution includes at least the right and left weight distributions of the vehicle M. The weight distribution may include the weight distribution on the front side and the rear side of the vehicle M.

The weight sensor 3 may indirectly detect the weight of the load of the vehicle M based on, for example, a load applied to the suspension of the vehicle M. The weight sensor 3 may detect the weight of the load using various other existing methods. The weight of the load may include the weight of the occupant of the vehicle M. The weight sensor 3 transmits information on the weight of the load detected by the vehicle M to the ECU 4.

The steering actuator 5 is an actuator that changes the steering angle of the vehicle M based on a control signal from the ECU 4. The steering actuator 5 may be configured by, for example, an assist motor of an electric power steering system.

Next, the functional configuration of the ECU 4 will be described. The ECU 4 includes a lane width recognition unit 11, a weight distribution change recognition unit 12, a distance recognition unit 13, a variation index calculation unit 14, a lane width threshold calculation unit 15, a control permission determination unit 16, a steering amount calculation unit 17, and a steering control unit. 18 is provided.

The lane width recognition unit 11 recognizes the lane width L of the lane R on which the vehicle M travels based on the image captured by the camera 1. The lane width recognition unit 11 recognizes the distance between the lane markings W1 and W2 in the captured image as the lane width L by, for example, an existing method.

The weight distribution change recognition unit 12 recognizes a change in the weight distribution based on the weight detected by the weight sensor 3. The weight distribution change recognizing unit 12 may calculate the right and left weights of the vehicle M based on, for example, the weight of the load on the right side of the vehicle M (right weight) and the weight of the load on the left side of the vehicle M (left weight). Recognize changes in distribution. The weight distribution change recognition unit 12 recognizes the absolute value of the weight difference between the right weight and the left weight as the magnitude of the change in the weight distribution. Note that the weight distribution change recognition unit 12 may recognize a change in the weight distribution before and after the vehicle M, or may recognize a change in the weight distribution before and after the vehicle M in a combined manner.

The distance recognition unit 13 recognizes the distance d between the lane line W1 of the lane R in which the vehicle M runs and the vehicle M based on the image captured by the camera 1. The distance recognizing unit 13 uses, for example, an existing method, an inner edge of the lane marking W1 (the center side of the lane R), a predetermined position of the vehicle M (eg, an end of the vehicle body closer to the lane marking W1), Is recognized. The predetermined position of the vehicle M may be another position such as the mounting position of the camera 1.

The fluctuation index calculating unit 14 calculates a fluctuation index based on the distance d recognized by the distance recognizing unit 13. The variation index is an index indicating the amount of variation (lateral position variation) of the position of the vehicle M in the lane R in the lane width direction. The lateral position fluctuation means the magnitude of meandering of the vehicle M in the lane R. The magnitude of the meandering here can be regarded as a change in the lateral position of the vehicle M with respect to the lane marking W1. As the change index, for example, the standard deviation σ of the distance d recognized by the distance recognition unit 13 can be used.

As an example, the variation index calculating unit 14 calculates, as a variation index, the standard deviation σ of the distance d recognized by the distance recognizing unit 13 at the latest predetermined travel time or the latest predetermined travel distance. The latest predetermined travel time is any travel time in the range of 10 seconds to 40 seconds, and may be, for example, 20 seconds or 30 seconds. The latest predetermined traveling distance is an arbitrary traveling distance within a range of 1 km to 5 km, and may be, for example, 2 km. The travel time and travel distance may be, for example, the time and distance during which the vehicle M continuously travels at a predetermined speed (for example, 10 km / h) or more.

The fluctuation index calculation unit 14 calculates the initial value of the fluctuation index based on the change in the weight distribution, and initializes the fluctuation index. For example, when the vehicle M is a truck or a tractor, when the vehicle M is a truck or a tractor, the weight difference between the right side weight and the left side weight is smaller than a predetermined threshold value by loading or unloading the load on the bed of the vehicle M. In the case of a large change, the change index is initialized. For example, when the vehicle M is a bus, the variation index calculation unit 14 initializes the variation index when the weight difference between the right weight and the left weight changes more than a predetermined threshold due to getting on and off the occupant of the vehicle M. As the initial value of the variation index, for example, a value (for example, 3.5 m) corresponding to a preset general lane width can be used.

The lane width threshold calculator 15 calculates the lane width threshold Lth based on the standard deviation σ, the vehicle width wm of the vehicle M, and the input operation received by the input unit 2. The lane width threshold value Lth is a threshold value of the lane width L which is a criterion of whether or not to execute the steering control. As an example, the lane width threshold calculator 15 calculates the lane width threshold Lth by summing a value obtained by multiplying the standard deviation σ by a predetermined coefficient, the vehicle width wm of the vehicle M, and the allowance α. As the predetermined coefficient of the standard deviation σ, for example, a real number of 2 or more (for example, 2 or 3) can be used. The allowance α is an adjustment term for adjusting the lane width threshold Lth by the driver's intention.

The lane width threshold calculator 15 calculates the margin α in accordance with the input operation received by the input unit 2. The lane width threshold calculator 15 may calculate the margin α stepwise according to, for example, the on / off operation of the input unit 2 or the number of operations, or may set the margin α in accordance with a set value directly input to the input unit 2. The margin α may be calculated.

The control permission determination unit 16 determines whether or not to permit the execution of the steering control based on the lane width L and the lane width threshold Lth. Specifically, the control permission determination unit 16 determines that the execution of the steering control is permitted when the lane width L is larger than the lane width threshold Lth. When the lane width L is equal to or smaller than the lane width threshold Lth, the control permission determination unit 16 determines that the execution of the steering control is not permitted.

The steering amount calculation unit 17 calculates the steering amount of the vehicle M based on the target trajectory T and the current position (vehicle position) of the vehicle M. The steering amount here is a steering amount of the vehicle M for causing the vehicle M to travel along the target locus T. The vehicle position can be recognized by the ECU 4 using various existing methods. The vehicle position may be, for example, a position represented by a coordinate system based on the vehicle M, or a position represented by latitude and longitude.

The steering control unit 18 performs the steering control based on the determination result of the control permission determination unit 16 and the steering amount calculated by the steering amount calculation unit 17. When the steering amount calculating unit 17 determines that the execution of the steering control is permitted, the steering control unit 18 sets the steering angle of the steered wheels of the vehicle M to the steering amount calculated by the steering amount calculating unit 17. And outputs a control signal to the steering actuator 5. As a result, the traveling locus of the vehicle M approaches the target locus T.

[Process by ECU]
Next, an example of a process performed by the ECU 4 will be described with reference to FIGS. FIG. 3 is a flowchart illustrating the steering control process. FIG. 4 is a flowchart illustrating an execution permission / prohibition determination process of the steering control. The steering control device 10 executes a steering control process shown in FIG.

ＥＣＵAs shown in FIG. 3, the ECU 4 generates a target trajectory in S11. The ECU 4 recognizes the vehicle position in S12. In S13, the steering amount is calculated by the steering amount calculation unit 17 in S13. The steering amount calculator 17 calculates the steering amount of the vehicle M based on the target trajectory T and the vehicle position.

(4) In S14, the ECU 4 determines whether or not to permit execution of the steering control. The ECU 4 performs an execution permission / prohibition determination process of the steering control of FIG. 4 as specifically described later.

If the execution of the steering control is permitted in S15, the ECU 4 executes the steering control by the steering control unit 18 in S16. When the steering amount calculation unit 17 determines that the execution of the steering control is permitted (S15: YES), the steering control unit 18 calculates the steering angle of the steered wheels of the vehicle M by the steering amount calculated by the steering amount calculation unit 17. A control signal is output to the steering actuator 5 so as to obtain the amount.

On the other hand, if the execution of the steering control is not permitted in S15, the ECU 4 ends the processing in FIG. The steering control unit 18 does not execute the steering control when the steering amount calculation unit 17 determines that the execution of the steering control is not permitted (S15: NO).

Next, a description will be given of a process of determining whether to permit execution of steering control. As shown in FIG. 4, in S21, the lane width recognition unit 11 recognizes the lane width L in S21. The lane width recognition unit 11 recognizes the lane width L of the lane R on which the vehicle M travels based on the image captured by the camera 1.

In step S22, the ECU 4 uses the distance recognition unit 13 to recognize the distance d between the lane marking W1 and the vehicle M. The distance recognition unit 13 recognizes a distance d between the lane line W1 of the lane R in which the vehicle M travels and the vehicle M based on the captured image captured by the camera 1.

(4) In S23, the ECU 4 causes the fluctuation index calculation unit 14 to calculate a fluctuation index. The variation index calculating unit 14 calculates, as a variation index, a standard deviation σ of the distance d recognized by the distance recognizing unit 13 in the latest predetermined travel time or the latest predetermined travel distance.

The ECU 4 calculates the lane width threshold Lth by the lane width threshold calculator 15 in S24. The lane width threshold calculator 15 calculates the lane width threshold Lth by summing a value obtained by multiplying the standard deviation σ by a predetermined coefficient, the vehicle width wm of the vehicle M, and the allowance α.

The ECU 4 uses the control permission determination unit 16 to determine whether the lane width L is larger than the lane width threshold Lth in S25. When the control permission determining unit 16 determines that the lane width L is larger than the lane width threshold Lth (S25: YES), the ECU 4 permits the control permission determining unit 16 to execute the steering control in S26. On the other hand, when the control permission determining unit 16 determines that the lane width L is smaller than the lane width threshold Lth (S25: NO), the ECU 4 disables the execution of the steering control by the control permission determining unit 16 in S27. I do. After that, the ECU 4 proceeds to the process of S15 in FIG.

Next, the process of initializing the fluctuation index will be described. FIG. 5 is a flowchart illustrating a process of initializing a variation index. The steering control device 10 executes the initialization process of the variation index shown in FIG. 5, for example, when the vehicle M is stopped or when the control system of the vehicle M is started (for example, when the engine is started).

ＥＣＵAs shown in FIG. 5, in S31, the ECU 4 uses the weight distribution change recognition unit 12 to recognize a change in the weight distribution. The weight distribution change recognition unit 12 recognizes the absolute value of the weight difference between the right weight and the left weight as the magnitude of the change in the weight distribution.

In step S32, the ECU 4 determines whether or not the magnitude of the change in the weight distribution is greater than a threshold value by the variation index calculator 14. When it is determined that the magnitude of the change in the weight distribution is greater than the threshold (S32: YES), the ECU 4 initializes the variation index by the variation index calculation unit 14 in S33. The variation index calculation unit 14 sets the variation index to, for example, 3.5 m. On the other hand, when it is determined that the magnitude of the change in the weight distribution is equal to or smaller than the threshold value (S32: NO), the ECU 4 does not initialize the variation index and ends the processing in FIG.

[Action and effect]
As described above, in the steering control device 10, the variation index calculation unit 14 calculates the standard deviation σ as a variation index representing the lateral position variation of the vehicle M in the lane R. The lane width threshold value calculation unit 15 calculates a lane width threshold value Lth, which is a threshold value of the lane width L as a criterion for permitting or rejecting the execution of the steering control, based on the standard deviation σ, the vehicle width wm of the vehicle M, and the allowance α. Is done. Thus, it is possible to calculate the lane width threshold Lth in consideration of the lateral position variation generated according to the change in the straightness of the vehicle M (change in the meandering degree of the vehicle M). Therefore, by using the appropriate lane width threshold Lth according to the change in the straightness, it is possible to appropriately execute the steering control for causing the vehicle M to travel along the target trajectory T according to the change in the straightness of the vehicle M. It becomes possible.

In the steering control device 10, the variation index calculating unit 14 calculates the standard deviation σ of the distance recognized by the distance recognizing unit 13 at the latest predetermined traveling time or the latest predetermined traveling distance as a variation index. As a result, the lane width threshold Lth according to the straightness of the latest vehicle M can be calculated.

The steering control device 10 includes a weight distribution change recognition unit 12 that recognizes a change in the weight distribution in the vehicle M. The variation index calculator 14 calculates an initial value of the standard deviation σ based on the change in the weight distribution. Thereby, the lane width threshold Lth according to the change in the straightness of the vehicle M due to the change in the weight distribution can be calculated. Thus, for example, even when the vehicle M whose weight distribution has changed while the vehicle is stopped travels, the steering control can be executed using the appropriate lane width threshold Lth according to the change in the weight distribution.

[Modification]
The embodiments according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments.

For example, in the above-described embodiment, the camera 1 is provided as the external sensor. However, for example, a laser radar may be provided in addition to or instead of the camera 1. In this case, the lane width L and the lane markings W1, W2 can be recognized by various existing methods based on the position information of the plurality of measurement points detected by the laser radar.

In the above embodiment, the distance recognized by the distance recognition unit 13 is the distance d between the lane marking W1 and the vehicle M, but may be the distance between the lane marking W2 and the vehicle M, or both distances. It may be. Further, for example, when one of the lane markings W1 and W2 is a wide dashed line provided at a branch portion of the road, the distance recognition unit 13 recognizes the distance using the other of the lane markings W1 and W2. Is also good.

In the above embodiment, the lane markings W1 and W2 are illustrated as the reference lines along the lane R, but the present invention is not limited to this. For example, the virtual line may be a center line of the lane R (a virtual line extending at an intermediate position between the lane markings W1 and W2) or a virtual line extending on a side surface of a structure (guard rail, curbstone, etc.) on the side of the lane R. There may be.

In the above embodiment, the variation index calculation unit 14 uses the distance d recognized by the distance recognition unit 13 in the latest predetermined travel time or the latest predetermined travel distance in order to calculate the standard deviation σ. Not limited. For example, the distance d recognized by the distance recognition unit 13 in the past may be used.

In the above embodiment, the variation index calculation unit 14 calculates the standard deviation σ of the distance d as the variation index, but is not limited to this. For example, the variation index calculating unit 14 calculates a maximum value, an average value, a median value, a mode value, and the like of the distance d recognized by the distance recognizing unit 13 in the latest predetermined travel time or the latest predetermined travel distance as a variation index. May be.

In the above embodiment, the variation index calculation unit 14 initializes the variation index based on the change in the weight distribution, but does not necessarily need to be based on the change in the weight distribution. For example, when the vehicle M has been stopped for a certain period of time, or when the control system of the vehicle M has been started (for example, when the engine is started), the fluctuation index calculation unit 14 does not depend on the change in the weight distribution. May be initialized.

では In the above embodiment, the margin α is variable as an adjustment term for adjustment by the driver's intention, but may be a fixed value. The margin α may be zero.

In the above-described embodiment, the control permission determination unit 16 determines whether or not to execute the steering control according to whether or not the lane width L is larger than the lane width threshold Lth. In the determination, a certain hysteresis may be set. For example, after the lane width L becomes larger than the lane width threshold Lth, the control permission determination unit 16 determines whether the steering control is to be performed when a predetermined delay time has elapsed since the lane width L became equal to or less than the lane width threshold Lth. It may be determined that execution is not permitted. In this case, the lane width threshold calculator 15 may set a predetermined delay time based on the variation index. For example, when the variation index is large (when the meandering of the vehicle M is large), the lane width threshold value calculation unit 15 may set the predetermined delay time to be shorter than when the variation index is small. Good.

In the above embodiment, the vehicle M is exemplified by a large vehicle such as a truck, a tractor, or a bus, but the vehicle M is not limited to these. The vehicle M may be a medium-sized car, a small car, and a mini car. In short, the vehicle M whose straightness changes due to various factors can be a target. Various factors that change the straightness include, for example, the characteristics of the tires of the vehicle M (such as the structure of ribs, studless and mixed tires, or the amount of air), and the aging of the underbody (for example, rubber bushes). , And the road surface condition of the lane R (such as the presence or absence of a rut or unevenness). Note that the variation index calculation unit 14 may initialize the variation index using a change in the various factors described above as a trigger.

DESCRIPTION OF SYMBOLS 1 ... Camera (external sensor), 2 ... Input part, 3 ... Weight sensor, 4 ... ECU, 5 ... Steering actuator, 10 ... Steering control device, 11 ... Lane width recognition part, 12 ... Weight distribution change recognition part, 13 ... Distance recognition unit, 14: variation index calculation unit, 15: lane width threshold calculation unit, 16: control permission determination unit, 17: steering amount calculation unit, 18: steering control unit, d: distance, L: lane width, Lth ... Lane width threshold, M: vehicle, R: lane, T: target locus, W1, W2: lane marking (reference line), wm: vehicle width, α: margin, σ: standard deviation.

Claims

A steering control device that performs steering control to cause the vehicle to travel along a target trajectory based on a detection result of an on-board external sensor,
A lane width recognition unit that recognizes a lane width of a lane in which the vehicle travels,
A distance recognition unit that recognizes a distance between the reference line and the vehicle along the lane,
A variation index calculating unit configured to calculate a variation index representing a lateral position variation of the vehicle in the lane based on the distance;
A lane width threshold calculation unit that calculates a lane width threshold that is a threshold of the lane width that is a reference for permission / prohibition of the execution of the steering control, based on the variation index and the vehicle width of the vehicle;
A steering control unit configured to execute the steering control when the lane width is larger than the lane width threshold.
2. The steering control device according to claim 1, wherein the variation index calculation unit calculates, as the variation index, a standard deviation of the distance recognized by the distance recognition unit during a latest predetermined travel time or a latest predetermined travel distance. 3.
The vehicle further includes a weight distribution change recognition unit that recognizes a change in weight distribution in the vehicle,
The steering control device according to claim 1, wherein the variation index calculation unit calculates an initial value of the variation index based on a change in the weight distribution.