Vehicle steering control device

Abstract

To provide a vehicle steering control device capable of adjusting the reaction given to steering wheel operation for a driver to travel a vehicle smoothly along a curve road.SOLUTION: A vehicle steering control device 10 sets a target of a change in a steering operation amount when making an own vehicle 100 travel along a curve road, sets a guide steering operation amount for guiding steering operation by a driver so that a change in the steering operation amount corresponding to a target is attained when the own vehicle travels along the curve road, and when an actual amount of steering operation is smaller than the guide steering operation amount, decreases a steering reaction. When detecting a curve road ahead of the own vehicle, the vehicle steering control device 10 decreases the steering reaction earlier by a prescribed time than the time that the driver starts a steering operation for making the own vehicle travel along the curve road.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a vehicle steering control device. [Background technology]

[0002] There is known a vehicle steering control device that applies a reaction force to the steering operation by a vehicle driver, and that adjusts the reaction force applied to the steering operation so that the amount of steering operation by the driver remains within an appropriate range when the driver is driving the vehicle along a curved road (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-209844 A Summary of the Invention

[0004] When a driver drives a vehicle along a curved road, the driver turns the steering wheel clockwise or counterclockwise. When the driver drives a vehicle along a sharply curved road, the driver needs to turn the steering wheel more quickly than when the driver drives a vehicle along a gently curved road. If the timing of changing the reaction force applied to the steering wheel operation is the same when the vehicle drives a sharply curved road and when the vehicle drives a gently curved road, the steering wheel operation is delayed when the vehicle drives a sharply curved road. As a result, the vehicle may not be able to drive smoothly along the curved road.

[0005] An object of the present invention is to provide a vehicle steering control device that can adjust the reaction force applied to the steering operation so that the driver can drive the vehicle smoothly along a curved road.

[0006] The vehicle steering control device according to the present invention includes a control device that controls a steering reaction force applied to a steering operation performed by a driver of the vehicle. The control device is configured to set a target for a change in the amount of the steering operation when the vehicle is caused to travel along a curved road, set a guide steering operation amount that guides the steering operation by the driver so that a change in the amount of the steering operation according to the target is achieved when the vehicle is traveling along the curved road, and reduce the steering reaction force when an actual amount of the steering operation is smaller than the guide steering operation amount.

[0007] Furthermore, in the vehicle steering control device of the present invention, when a curved road is detected ahead of the vehicle, the control device is configured to predict the time when the driver will start a steering operation to drive the vehicle along the curved road as a steering operation start time, and to reduce the steering reaction force at a point a predetermined time before the steering operation start time.

[0008] If the steering reaction force is reduced when the time arrives when the driver starts a steering operation to make the vehicle travel along a curved road (steering operation start time), the driver will be able to easily perform a steering operation to make the vehicle travel along the curved road, but the steering operation may be delayed, making it impossible to make the vehicle travel along the curved road in an optimal manner. According to the present invention, the steering reaction force is reduced at an earlier timing than the steering operation start time. Therefore, even when the curve of the curved road is large, the steering operation to make the vehicle travel along the curved road is performed without delay, and as a result, the vehicle can be traveled along the curved road in an optimal manner.

[0009] In addition, in the vehicle steering control device of the present invention, the control device is configured to set the specified time to a longer time when the curved road is sharp, compared to when the curved road is sharp.

[0010] When the curvature of a curved road is large, the driver needs to perform a larger steering operation to drive the vehicle along the curved road, so that the possibility of the driver's steering operation being delayed increases. According to the present invention, when the curvature of a curved road is large, the predetermined time for advancing the timing for starting to set the guide steering operation amount is set to a long time, so that the steering reaction force is reduced at an earlier timing than the time when the driver starts a steering operation to drive the vehicle along the curved road. Therefore, it is possible to suppress delays in the driver's steering operation.

[0011] In addition, in the vehicle steering control device of the present invention, the control device is configured to set the specified time to a longer time when the traveling speed of the vehicle is high, compared to when the traveling speed of the vehicle is low.

[0012] When the vehicle is traveling at a high speed, the driver needs to steer the vehicle faster in order to drive the vehicle along a curved road, so that the driver's steering operation is likely to be delayed. According to the present invention, when the vehicle is traveling at a high speed, the predetermined time for advancing the timing for starting to set the guide steering operation amount is set to a long time, so that the steering reaction force is reduced at an earlier timing than the time when the driver starts to steer the vehicle to drive the vehicle along the curved road. This makes it possible to suppress delays in the driver's steering operation.

[0013] In addition, in the vehicle steering control device according to the present invention, the control device is configured, for example, to limit the maximum value of the guide steering operation amount to a value that is a predetermined value smaller than the maximum value of the steering operation amount that changes at the target.

[0014] When the driver drives the vehicle along a curved road, the driver first increases the amount of steering operation and then decreases the amount of steering operation. At this time, when the amount of steering operation approaches the maximum value of the amount of steering operation (target steering operation amount) defined by the target of the change, the amount of steering operation may be increased beyond the maximum value. According to the present invention, the maximum value of the guide steering operation amount is limited to a value smaller than the maximum value of the target steering operation amount by a predetermined value. Therefore, when the amount of steering operation approaches the maximum value of the target steering operation amount, the steering reaction force is increased. Therefore, it is possible to prevent the steering operation by the driver from exceeding the maximum value of the target steering operation amount.

[0015] In addition, in the vehicle steering control device of the present invention, the control device is configured, for example, to set the specified value to a larger value when the vehicle's traveling speed is high compared to when the vehicle's traveling speed is low.

[0016] When the vehicle is traveling at a high speed, the driver tends to increase the speed of the steering operation in order to drive the vehicle along a curved road, and therefore the driver is unable to stop the steering operation at an appropriate steering amount, and the steering amount is likely to become too large. According to the present invention, when the vehicle is traveling at a high speed, the predetermined value for making the maximum value of the guide steering operation amount smaller than the maximum value of the target steering operation amount is set to a large value, so that when the steering operation amount approaches the maximum value of the target steering operation amount while the vehicle is traveling at a high speed, the degree to which the steering reaction force is increased is reduced. Therefore, the steering operation by the driver can be appropriately prevented from exceeding the maximum value of the target steering operation amount.

[0017] In addition, in the vehicle steering control device of the present invention, the control device is configured to set the specified value to a larger value when the curved road is sharp, compared to when the curved road is sharp.

[0018] When the curvature of a curved road is large, the driver needs to perform a larger steering operation in order to drive the vehicle along the curved road, so that the amount of steering operation is likely to exceed the maximum value of the amount of steering operation (target steering operation amount) defined by the target of the change. According to the present invention, when the curvature of a curved road is large, the predetermined value for making the maximum value of the guide steering operation amount smaller than the maximum value of the target steering operation amount is set to a large value, so that when the curvature of a curved road is large and the amount of steering operation approaches the maximum value of the target steering operation amount, the degree to which the steering reaction force is increased increases. Therefore, it is possible to appropriately suppress the steering operation by the driver from exceeding the maximum value of the target steering operation amount.

[0019] In addition, the vehicle steering control device of the present invention is equipped with a control device that controls the steering reaction force applied to a steering operation performed by a driver of the vehicle, and the control device is configured to make the steering reaction force applied to the steering operation when the vehicle is traveling along a curved road smaller when the curve of the curved road is large compared to when the curve of the curved road is small.

[0020] When the curvature of a curved road is large, the driver needs to perform a large steering operation to make the vehicle run along the curved road in a favorable manner, compared to when the curvature of the curved road is small. Therefore, when the curvature of a curved road is large, the driver's steering operation to make the vehicle run along the curved road may be delayed, and in that case, the vehicle may not be able to run along the curved road in a favorable manner. According to the present invention, when the curvature of a curved road is large, the steering reaction force is made smaller than when the curvature of the curved road is small. Therefore, even when the curvature of a curved road is large, the driver can perform a steering operation to make the vehicle run along the curved road without delay.

[0021] In addition, in the vehicle steering control device of the present invention, the curvature of the curved road is, for example, the minimum curve radius of the curved road. In this case, the control device is configured to acquire the curve radius of the curved road at a point farther forward from the vehicle when the minimum curve radius of the curved road is small, compared to when the minimum curve radius of the curved road is large, and to make the steering reaction force smaller when the acquired curve radius is small, compared to when the acquired curve radius is large.

[0022] In the case where the steering reaction force is reduced based on the radius of the curve of the road at the current position of the vehicle, when the vehicle is traveling on a straight road before a curve, the radius of the curve is not detected, and the radius of the curve is detected from the time when the vehicle enters the curve. Therefore, when the vehicle is traveling on a straight road before a curve, the steering reaction force is not reduced, and the steering reaction force is reduced from the time when the vehicle enters the curve. In this case, the driver's steering operation to make the vehicle travel along the curve may be delayed, and the vehicle may not be able to travel suitably along the curve. In addition, when the curve is sharp, if the driver's steering operation to make the vehicle travel along the curve is delayed, the possibility of the vehicle not being able to travel suitably along the curve increases.

[0023] According to the present invention, the steering reaction force is reduced based on the radius of the curve of the curved road at a point ahead of the vehicle, so that the steering reaction force is reduced while the vehicle is traveling on a straight road just before the curve. Moreover, when the curved road is sharp (when the minimum radius of the curve is small), the radius of the curve of the curved road at a point farther ahead of the vehicle is acquired compared to when the curved road is small (when the minimum radius of the curve is large), and when the radius of the curve is small, the steering reaction force is reduced compared to when the radius of the curve is large. Therefore, even when the curved road is sharp, the steering operation for driving the vehicle along the curved road can be performed without delay, and as a result, the vehicle can be driven to drive suitably along the curved road.

[0024] The components of the present invention are not limited to the embodiments of the present invention described below with reference to the drawings. Other objects, other features and associated advantages of the present invention will be easily understood from the description of the embodiments of the present invention. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a diagram showing a vehicle steering control device according to an embodiment of the present invention and a vehicle (host vehicle) on which the vehicle steering control device is mounted. [Diagram 2] FIG. 2A is a diagram showing a scene in which the host vehicle enters a road with a gentle curve, and FIG. 2B is a diagram showing a scene in which the host vehicle enters a road with a sharp curve. [Diagram 3] FIG. 3 is a diagram showing the presence or absence of a degree of urgency determined according to the traveling speed of the host vehicle (host vehicle speed) and the curve radius. [Figure 4] FIG. 4(A) is a diagram showing the relationship between the guide steering angle and the actual steering angle when the vehicle is entering a gently curved road, and FIG. 4(B) is a diagram showing the relationship between the guide steering angle and the actual steering angle when the vehicle is entering a sharply curved road. [Diagram 5] FIG. 5 is a flowchart showing a routine executed by the vehicle steering control device according to the embodiment of the present invention. [Figure 6] Figure 6 (A) is a diagram showing the change in the guide steering angle and the change in the target steering angle that are set when the curve radius is large and the vehicle speed is low, and Figure 6 (B) is a diagram showing the change in the guide steering angle and the change in the target steering angle that are set when the curve radius is small and the vehicle speed is high. [Figure 7] FIG. 7 is a flowchart showing a routine executed by a vehicle steering control device according to a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, a vehicle steering control device according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, a vehicle steering control device 10 according to an embodiment of the present invention is mounted on a host vehicle 100. In the following description, the driver of the host vehicle 100 will be referred to as "driver DR".

[0027] <ecu> The vehicle steering control device 10 includes an ECU 90. ECU is an abbreviation for electronic control unit. The ECU 90 includes a microcomputer as a main part. The microcomputer includes a CPU, a ROM, a RAM, a non-volatile memory, and an interface. The CPU realizes various functions by executing instructions, programs, or routines stored in the ROM.

[0028] <Running gear> The host vehicle 100 is also equipped with a traveling device 20. The traveling device 20 includes a drive device 21, a braking device 22, and a steering device 23.

[0029] <Drive unit> The drive device 21 is a device that outputs a drive torque (drive force) applied to the host vehicle 100 to make the host vehicle 100 travel, and is, for example, an internal combustion engine, a motor, etc. The drive device 21 is electrically connected to the ECU 90. The ECU 90 can control the drive torque output from the drive device 21 by controlling the operation of the drive device 21.

[0030] <Brake device> The braking device 22 is a device that outputs a braking torque (braking force) applied to the host vehicle 100 in order to brake the host vehicle 100, and is, for example, a brake device. The braking device 22 is electrically connected to the ECU 90. The ECU 90 can control the braking torque output from the braking device 22 by controlling the operation of the braking device 22.

[0031] <Steering system> The steering device 23 is a device for steering the host vehicle 100, and in this example, includes a power steering device 231 and a reaction force actuator 232. The power steering device 231 is a device for outputting a steering torque (steering force) for steering the host vehicle 100. The reaction force actuator 232 is a device for applying a reaction force (steering reaction force) to the steering operation when a force for rotating the steering wheel 35 is applied to the steering wheel 35. The power steering device 231 and the reaction force actuator 232 are electrically connected to the ECU 90. The ECU 90 can control the steering torque output from the power steering device 231 by controlling the operation of the power steering device 231, and can control the steering reaction force by controlling the operation of the reaction force actuator 232.

[0032] <Sensors, etc.> Furthermore, the host vehicle 100 is equipped with an accelerator pedal 31, an accelerator pedal operation amount sensor 32, a brake pedal 33, a brake pedal operation amount sensor 34, a steering wheel 35, a steering shaft 36, a steering angle sensor 37, a steering torque sensor 38, a vehicle speed detection device 51, a surrounding information detection device 60, and a road information detection device 70.

[0033] <Accelerator pedal operation amount sensor> The accelerator pedal operation amount sensor 32 is a sensor that detects the operation amount of the accelerator pedal 31, and is electrically connected to the ECU 90. The accelerator pedal operation amount sensor 32 transmits information about the detected operation amount of the accelerator pedal 31 to the ECU 90. The ECU 90 acquires the operation amount of the accelerator pedal 31 as an accelerator pedal operation amount AP based on that information. The ECU 90 acquires a required driving torque (required driving force) based on the accelerator pedal operation amount AP and the host vehicle speed V (the traveling speed of the host vehicle 100), and controls the operation of the drive device 21 so that the required driving torque is output from the drive device 21.

[0034] <Brake pedal operation amount sensor> The brake pedal operation amount sensor 34 is a sensor that detects the amount of operation of the brake pedal 33, and is electrically connected to the ECU 90. The brake pedal operation amount sensor 34 transmits information about the detected amount of operation of the brake pedal 33 to the ECU 90. The ECU 90 obtains the amount of operation of the brake pedal 33 as a brake pedal operation amount BP based on that information. The ECU 90 obtains a required braking torque (required braking force) based on the brake pedal operation amount BP, and controls the operation of the braking device 22 so that the required braking is output from the braking device 22.

[0035] <Steering angle sensor> The steering angle sensor 37 is a sensor that detects the rotation angle of the steering shaft 36 with respect to the neutral position, and is electrically connected to the ECU 90. The steering angle sensor 37 transmits information on the detected rotation angle of the steering shaft 36 to the ECU 90. The ECU 90 obtains the rotation angle of the steering shaft 36 as the steering angle θ based on the information.

[0036] <Steering torque sensor> The steering torque sensor 38 is a sensor that detects the torque input by the driver DR to the steering shaft 36 via the steering wheel 35, and is electrically connected to the ECU 90. The steering torque sensor 38 transmits information on the detected torque to the ECU 90. The ECU 90 acquires the torque (driver input torque) input by the driver DR to the steering shaft 36 via the steering wheel 35 based on that information. The ECU 90 acquires a required steering torque based on the steering angle θ, the driver input torque, and the host vehicle speed V (the traveling speed of the host vehicle 100), and controls the operation of the steering device 23 so that the required steering torque is output from the steering device 23.

[0037] <Vehicle speed detection device> The vehicle speed detection device 51 is a device that detects the vehicle speed (host vehicle speed V) of the host vehicle 100, and is, for example, a wheel speed sensor. The vehicle speed detection device 51 is electrically connected to the ECU 90. The vehicle speed detection device 51 transmits information on the detected vehicle speed of the host vehicle 100 to the ECU 90. The ECU 90 acquires the host vehicle speed V based on the information.

[0038] <Peripheral information detection device> The surrounding information detection device 60 is a device that detects information about the surroundings of the vehicle 100, and in this example, includes a radio wave sensor 61 and an image sensor 62. The radio wave sensor 61 is, for example, a radar sensor (such as a millimeter wave radar). The image sensor 62 is, for example, a camera. The surrounding information detection device 60 may also include a sonic sensor such as an ultrasonic sensor (clearance sonar) or an optical sensor such as a laser radar (LiDAR).

[0039] <Radio wave sensor> The radio wave sensor 61 is electrically connected to the ECU 90. The radio wave sensor 61 transmits radio waves and receives radio waves (reflected waves) reflected by an object. The radio wave sensor 61 transmits information (detection results) related to the transmitted radio waves and received radio waves (reflected waves) to the ECU 90. In other words, the radio wave sensor 61 detects objects present in the vicinity of the vehicle 100 and transmits information (detection results) related to the detected objects to the ECU 90. The ECU 90 can obtain information (periphery detection information IS) related to objects present in the vicinity of the vehicle 100 based on the information (radio wave information). In this example, the objects are vehicles, motorcycles, bicycles, people, etc.

[0040] <Image sensor> The image sensor 62 is also electrically connected to the ECU 90. The image sensor 62 captures an image of the surroundings of the vehicle 100 and transmits information related to the captured image to the ECU 90. The ECU 90 can obtain information (surroundings detection information IS) related to the surroundings of the vehicle 100 based on the information (camera image information IC).

[0041] <Road information detection device> The road information detection device 70 includes a GPS device 71 and a map information database 72.

[0042] <GPS device> The GPS device 71 is a device that receives a so-called GPS signal and is electrically connected to the ECU 90. The ECU 90 acquires a GPS signal via the GPS device 71. The ECU 90 can acquire the current position P100 of the host vehicle 100 based on the acquired GPS signal.

[0043] <Map information database> The map information database 72 is a database that stores map information including "information regarding the regulated speed" and "information regarding the type of road", etc., and is electrically connected to the ECU 90. The ECU 90 can acquire information (road information IR) regarding the road on which the host vehicle 100 is currently traveling from the current position P100 of the host vehicle 100.

[0044] <Outline of the operation of the vehicle steering control device> Next, the outline of the operation of the vehicle steering control device 10 will be described.

[0045] When the driver DR drives the host vehicle 100 along a curved road, the driver DR rotates the steering wheel 35 clockwise or counterclockwise. At this time, when the driver DR drives the host vehicle 100 along a sharp curved road, compared with when driving the host vehicle 100 along a gentle curved road, it is necessary to rotate the steering wheel 35 quickly. Here, if the reaction force (steering reaction force) applied from the reaction force actuator 232 to the steering wheel 35 is constant when driving the host vehicle 100 along a sharp curved road and when driving the host vehicle 100 along a gentle curved road, the steering operation may be delayed when driving the host vehicle 100 along a sharp curved road, and it may not be possible to realize smooth driving of the host vehicle 100 along the curved road.

[0046] Therefore, the vehicle steering control device 10 adjusts the steering reaction force according to the curvature of the curved road along which the driver DR is trying to drive the vehicle 100, thereby enabling the driver DR to drive the vehicle 100 smoothly along the curved road.

[0047] More specifically, while the host vehicle 100 is traveling, the vehicle steering control device 10 determines whether or not the host vehicle 100 is predicted to enter a curved road based on the camera image information IC and / or road information IR.

[0048] When the vehicle steering control device 10 determines that the host vehicle 100 is predicted to enter a curved road, the vehicle steering control device 10 acquires or estimates the minimum curve radius (curve radius R) of the curved road based on the road information IR and / or the camera image information IC. In this example, when acquiring the curve radius R based on the road information IR, the vehicle steering control device 10 compares the current position P100 of the host vehicle 100 identified from the GPS signal with the map information stored in the map information database 72, identifies the road on which the host vehicle 100 is traveling at that time, and acquires the curve radius R by reading out the curve radius R associated with the road and stored from the map information database 72. When acquiring the curve radius R based on the camera image information IC, the vehicle steering control device 10 estimates the curve radius R from the image information of the host vehicle traveling road RD ahead of the host vehicle 100 obtained based on the camera image information IC.

[0049] When the vehicle steering control device 10 acquires the curve radius R, it acquires as the gaze point curvature ρ the curvature of the host vehicle road RD at a point ahead of the host vehicle 100 where it is estimated that the driver DR will be gazing at the curved road ahead with the curve radius R. At this time, when the acquired curve radius R is small as described above, the vehicle steering control device 10 acquires as the gaze point curvature ρ the curvature of the host vehicle road RD at a point farther ahead of the host vehicle 100 than when the curve radius R is large.

[0050] For example, as shown in (A) of Fig. 2, when the curve radius R is large (i.e., when the curve road where the host vehicle 100 is predicted to enter is a gently curved road), the vehicle steering control device 10 acquires the curvature of the host vehicle road RD a first distance D1 ahead of the host vehicle 100 as the gaze point curvature ρ. On the other hand, as shown in (B) of Fig. 2, when the curve radius R is small (i.e., when the curve road where the host vehicle 100 is predicted to enter is a sharply curved road), the vehicle steering control device 10 acquires the curvature of the host vehicle road RD a second distance D2 ahead of the host vehicle 100, which is longer than the first distance D1, as the gaze point curvature ρ. In this way, when the acquired curve radius R is small, the vehicle steering control device 10 acquires the curvature of the host vehicle road RD at a point farther ahead of the host vehicle 100 as the gaze point curvature ρ, compared to when the acquired curve radius R is large.

[0051] When the vehicle steering control device 10 acquires the gaze point curvature ρ, it controls the operation of the reaction force actuator 232 so that the larger the acquired gaze point curvature ρ, the smaller the steering reaction force applied to the steering wheel operation.

[0052] More specifically, the vehicle steering control device 10 obtains, by calculation, a target value of the steering reaction force (target steering reaction force Ftgt) to be applied to the steering operation by the reaction force actuator 232, as described below, and controls the operation of the reaction force actuator 232 so that the target steering reaction force Ftgt is applied to the steering operation.

[0053] First, when the vehicle steering control device 10 acquires the curve radius R, it judges whether or not there is a degree of tension based on the curve radius R and the vehicle speed V at that time. The degree of tension in this example represents a point (forward gaze point) ahead of the vehicle 100 that the driver DR is estimated to be gazing at when the driver DR makes the vehicle 100 enter the curved road, and when the degree of tension is judged to be high (i.e., when it is judged that there is a degree of tension), the degree of tension indicates that the forward gaze point is a point relatively far ahead of the vehicle 100, and when it is judged to be low (i.e., when it is judged that there is no tension), the degree of tension indicates that the forward gaze point is a point relatively close ahead of the vehicle 100.

[0054] As shown in Fig. 3, when the vehicle speed V is in a range lower than a predetermined vehicle speed Vth, if the curve radius R is greater than a predetermined value (first radius Rth1), the vehicle steering control device 10 determines that there is tension, but if the curve radius R is equal to or smaller than the first radius Rth1, the vehicle steering control device 10 determines that there is tension, but if the curve radius R is equal to or smaller than the first radius Rth2, the vehicle steering control device 10 determines that there is tension, but if the curve radius R is equal to or smaller than the second radius Rth2, the vehicle steering control device 10 determines that there is tension, but if the curve radius R is equal to or smaller than the second radius Rth2, the vehicle steering control device 10 determines that there is tension, but if the curve radius R is equal to or smaller than the second radius Rth2, the vehicle steering control device 10 determines that there is tension,

[0055] In the example described here, the vehicle steering control device 10 determines whether or not there is a sense of urgency based on both the vehicle speed V and the curve radius R, but may be configured to determine whether or not there is a sense of urgency based only on the curve radius R.

[0056] When the vehicle steering control device 10 judges whether or not there is a degree of tension, it estimates how far ahead the driver DR is gazing at a point on the road RD ahead of the vehicle, depending on whether or not there is a degree of tension. That is, the vehicle steering control device 10 acquires the distance (forward gaze distance D) from the vehicle 100 to a point (forward gaze point) where the driver DR is estimated to be gazing, by calculation according to the following formula 1.

[0057] D = V × T … (1)

[0058] In the above formula 1, "V" is the vehicle speed V, and "T" is the forward gaze time.

[0059] When the vehicle steering control device 10 determines that there is no tension, it sets a predetermined time (first time T1) as the forward gaze time T, and when it determines that there is tension, it sets a predetermined time (second time T2) longer than the first time T1 as the forward gaze time T. Therefore, the forward gaze distance D acquired when it is determined that there is tension is longer than the forward gaze distance D acquired when it is determined that there is no tension.

[0060] When the vehicle steering control device 10 acquires the forward gaze distance D, it acquires the curvature (gaze point curvature ρ) of the road RD on which the vehicle is traveling, which is the forward gaze distance D ahead of the vehicle 100, using the camera image information IC and / or road information IR. At this time, as described above, the forward gaze distance D when there is tension is longer than the forward gaze distance D when there is no tension, so the gaze point curvature ρ acquired when there is tension tends to be larger than the gaze point curvature ρ acquired when there is no tension.

[0061] When the vehicle steering control device 10 acquires the gaze point curvature ρ, it acquires a guide steering angle θg by calculation according to the calculation formula shown in the following formula 2.

[0062] θg=n×K×(1+A×V 2 ) × L × ρ … (2)

[0063] In the above equation 2, "n" is the gear ratio of the steering box, "K" is a coefficient (suitable value) determined by experiments, etc. so that the guide steering angle θg obtained by the above equation 1 can be obtained as a value that enables the vehicle 100 to travel smoothly along a curved road, "A" is the so-called stability factor, "V" is the vehicle speed, and "L" is the wheelbase of the vehicle 100.

[0064] When the vehicle steering control device 10 acquires the guide steering angle θg, it acquires the difference between the guide steering angle θg and the actual steering angle θ at that time (steering angle difference Δθ) by calculation according to the calculation formula shown in the following formula 3.

[0065] Δθ=θg-θ …(3)

[0066] When the vehicle steering control device 10 acquires the steering angle difference Δθ, the larger the steering angle difference Δθ, the smaller the target steering reaction force Ftgt is set to a value, and the operation of the reaction force actuator 232 is controlled so that the target steering reaction force Ftgt is applied to the steering operation. The vehicle steering control device 10 may be configured to store a map of the target steering reaction force Ftgt using the steering angle difference Δθ as an argument, and set the target steering reaction force Ftgt by applying the steering angle difference Δθ to the map, instead of setting the target steering reaction force Ftgt by calculation according to an arithmetic expression. In this case, the larger the steering angle difference Δθ, the smaller the target steering reaction force Ftgt set by the map becomes.

[0067] <Effects> According to the vehicle steering control device 10, when it is predicted that the host vehicle 100 will enter a gently curved road, the acquired guide steering angle θg changes as shown in Fig. 4(A). In Fig. 4(A), the line Lg shows the change in the guide steering angle θg, and the line La shows the change in the actual steering angle θ, where the guide steering angle θg starts to increase from zero at time t40, and the actual steering angle θ starts to increase from zero at time t41.

[0068] On the other hand, when it is predicted that the vehicle 100 will enter a sharp curved road, the acquired guide steering angle θg changes as shown in Fig. 4B. In Fig. 4B, line Lg shows the change in guide steering angle θg, and line La shows the change in actual steering angle θ, where the guide steering angle θg starts to increase from zero at time t40, and the actual steering angle θ starts to increase from zero at time t41.

[0069] As can be seen by comparing the transition of the guide steering angle θg shown in FIG. 4(A) with the transition of the guide steering angle θg shown in FIG. 4(B), when the curved road that the host vehicle 100 is predicted to enter is a sharp curved road, the guide steering angle θg is increased at an earlier timing than when the curved road is a gentle curved road. Therefore, when the curved road that the host vehicle 100 is predicted to enter is a sharp curved road, the steering reaction force F is reduced at an earlier timing than when the curved road is a gentle curved road. Therefore, when the host vehicle 100 approaches a sharp curved road and the driver DR starts to turn the steering wheel 35, the steering reaction force F is reduced, so that the driver DR can quickly turn the steering wheel 35, and as a result, the host vehicle 100 can run smoothly along the curved road even if the curved road is a sharp curved road. Therefore, the vehicle steering control device 10 can adjust the steering reaction force so that the driver DR can run the host vehicle 100 smoothly along the curved road.

[0070] In addition, when the curved road that the vehicle 100 is predicted to enter is a sharp curved road, the guide steering angle θg increases or decreases prior to the change in the actual steering angle θ while the vehicle 100 is traveling on the curved road. Therefore, even if the curved road is a sharp curved road, the vehicle 100 can be smoothly traveled along the curved road.

[0071] When the curved road into which the vehicle 100 is predicted to enter is a gentle curved road, the guide steering angle θg increases or decreases in a manner similar to the change in the actual steering angle θ while the vehicle 100 is traveling on the curved road. Therefore, the steering reaction force is adjusted in a manner similar to the actual steering wheel rotation operation by the driver DR.

[0072] <Specific operation of the vehicle steering control device> Next, a specific operation of the vehicle steering control device 10 will be described. The CPU of the ECU 90 of the vehicle steering control device 10 executes the routine shown in Fig. 5 at a predetermined calculation cycle. Therefore, at a predetermined timing, the CPU starts the process from step 500 in Fig. 5, advances the process to step 505, and determines whether or not there is a degree of tension.

[0073] If the CPU judges "Yes" in step 505, the process proceeds to step 510 and sets the forward gaze time T to the second time T2. Next, the CPU proceeds to step 515 and acquires the forward gaze distance D by calculation according to the calculation formula shown in the above formula 1 using the forward gaze time T set in step 510. Next, the CPU proceeds to step 520 and acquires the gaze point curvature ρ as described above using the forward gaze distance D acquired in step 515. Next, the CPU proceeds to step 525 and acquires the guide steering angle θg by calculation according to the calculation formula shown in the above formula 2 using the gaze point curvature ρ acquired in step 520. Next, the CPU proceeds to step 550 and acquires the steering angle difference Δθ by calculation according to the calculation formula shown in the above formula 3 using the guide steering angle θg acquired in step 525. Next, the CPU advances the process to step 555, and acquires the target steering reaction force Ftgt as described above using the steering angle difference Δθ acquired in step 550. Next, the CPU advances the process to step 560, and controls the operation of the reaction force actuator 232 so as to achieve the target steering reaction force Ftgt acquired in step 555. Thereafter, the CPU advances the process to step 595, and temporarily ends this routine.

[0074] On the other hand, if the CPU judges "No" in step 505, the process proceeds to step 530, where the forward gaze time T is set to the first time T1. Next, the CPU proceeds to step 535, where the CPU acquires the forward gaze distance D by calculation according to the calculation formula shown in the above formula 1 using the forward gaze time T set in step 530. Next, the CPU proceeds to step 540, where the CPU acquires the gaze point curvature ρ as described above using the forward gaze distance D acquired in step 535. Next, the CPU proceeds to step 545, where the CPU acquires the guide steering angle θg by calculation according to the calculation formula shown in the above formula 2 using the gaze point curvature ρ acquired in step 540. Next, the CPU proceeds to step 550, where the CPU acquires the steering angle difference Δθ by calculation according to the calculation formula shown in the above formula 3 using the guide steering angle θg acquired in step 545. Next, the CPU advances the process to step 555, and acquires the target steering reaction force Ftgt as described above using the steering angle difference Δθ acquired in step 550. Next, the CPU advances the process to step 560, and controls the operation of the reaction force actuator 232 so as to achieve the target steering reaction force Ftgt acquired in step 555. Thereafter, the CPU advances the process to step 595, and temporarily ends this routine.

[0075] The specific operation of the vehicle steering control device 10 has been described above.

[0076] <Modification> Alternatively, the vehicle steering control device 10 may be configured to enable the driver DR to drive the vehicle 100 smoothly along a curved road by adjusting the steering reaction force according to the curvature of the curved road along which the driver DR is to drive the vehicle 100, as follows.

[0077] That is, the vehicle steering control device 10 relating to a modified embodiment of the present invention may be configured, when it is predicted that the host vehicle 100 will enter a curved road, to set a target for changing the steering angle so that the host vehicle 100 can travel smoothly along the curved road as a steering angle change target, to set a guide steering angle θg that guides the steering operation by the driver DR so that a change in the steering angle θ in accordance with the steering angle change target is achieved when the host vehicle 100 travels along the curved road, and to reduce the steering reaction force when the actual steering angle θ is smaller than the guide steering angle θg, and to increase the steering reaction force when the actual steering angle θ is larger than the guide steering angle θg.

[0078] Particularly in this example, the steering angle θ according to the steering angle change target (target steering angle θtgt) is expressed by the following formula 4. In the following formula 4, "t" is the time (steering wheel operation start time) when the driver DR starts to turn the steering wheel 35 from the neutral position in order to drive the host vehicle 100 along a curved road. Therefore, in the following formula 4, "f(t)" is a function with the steering wheel operation start time t as a variable.

[0079] θtgt=f(t) …(4)

[0080] In this example, the guide steering angle θg is obtained (set) from the following formula 5. In the following formula 5, "t" is the steering wheel operation start time, "τ" is a time (look-ahead time) for advancing the time to start setting the guide steering angle θg, and "a" is a gain.

[0081] θg=a×f(t-τ) …(5)

[0082] In this example, the look-ahead time τ is set based on the curve radius R and the vehicle speed V, and is obtained from the following formula 6 in particular. In the following formula 6, "R" is the curve radius, "V" is the vehicle speed, and "H(R, V)" is a function with the curve radius R and the vehicle speed V as variables.

[0083] τ = H(R,V) …(6)

[0084] According to the above formula 6, when the curve radius R is small, a longer look-ahead time τ is acquired compared to when the curve radius R is large, and in particular, the smaller the curve radius R, the longer the look-ahead time τ is acquired. Also, according to the above formula 6, when the curve radius R is greater than zero, a look-ahead time τ longer than zero is acquired. Also, according to the above formula 6, when the host vehicle speed V is high, a longer look-ahead time τ is acquired compared to when the host vehicle speed V is low, and in particular, the higher the host vehicle speed V, the longer the look-ahead time τ is acquired.

[0085] In this example, the gain a is set based on the curve radius R and the vehicle speed V, and is obtained from the following formula 7 in particular. In the following formula 7, "R" is the curve radius, "V" is the vehicle speed, and "G(R, V)" is a function with the curve radius R and the vehicle speed V as variables.

[0086] a = G(R,V) …(7)

[0087] According to the above formula 7, when the curve radius R is small, a smaller value of gain a is acquired compared to when the curve radius R is large, and in particular, the smaller the curve radius R, the smaller the value of gain a is acquired. Also, according to the above formula 7, when the host vehicle speed V is high, a smaller gain a is acquired compared to when the host vehicle speed V is low, and in particular, the higher the host vehicle speed V, the smaller the gain a is acquired. Also, the gain a acquired from the above formula 7 is a value greater than zero and less than or equal to "1". Also, according to the above formula 7, when the curve radius R is greater than zero, at least a gain a smaller than "1" is acquired.

[0088] In addition, a linear expression, a quadratic expression, or a sigmoid function can be used as the function H(R,V) or the function G(R,V). Alternatively, the function H(R,V) or the function G(R,V) may be stored in the form of a map (or a look-up table), and the look-ahead time τ and the gain a may be obtained by applying the curve radius R and the vehicle speed V to the map. Alternatively, as described above, the presence or absence of a degree of tension may be determined based on the vehicle speed V and the curve radius R, and if there is no degree of tension, a relatively short time may be set as the look-ahead time τ, and if there is a degree of tension, a longer time may be set as the look-ahead time τ.

[0089] The target steering angle θtgt obtained from the above equation 4 begins to become larger than zero at time t61 (time t when the steering operation begins), as shown by line La in Figure 6, and then gradually increases over time, reaching its maximum value, and then gradually decreases, until it becomes zero at time t63 when the vehicle 100 has finished traveling the curved road.

[0090] On the other hand, the guide steering angle θg obtained from the above equation 5, as shown by line Lg in Figure 6, begins to become greater than zero at time t60, which is earlier than time t61 (time t when the steering operation begins), and then gradually increases over time, reaching its maximum value θmax, and then gradually decreases, becoming zero at time t62, which is earlier than time t63 when the vehicle 100 has finished traveling the curved road.

[0091] In this way, in this example, when a curved road is detected and the curve radius R of the curved road is acquired, a look-ahead time τ longer than zero is set, so that setting of the guide steering angle θg is started at time t60, which is earlier than the steering wheel operation start time t (time t61). In other words, the guide steering angle θg becomes larger than zero from time t60, which is earlier than the steering wheel operation start time t (time t61).

[0092] In addition, in this example, when a curved road is detected and the curve radius R of the curved road is obtained, a gain a smaller than "1" is set, so that the maximum value θmax of the guide steering angle θg becomes smaller than the maximum value of the target steering angle θtgt.

[0093] Furthermore, the look-ahead time τ is set to a longer time when the curve radius R is small than when the curve radius R is large, so that the time t60 at which setting of the guide steering angle θg begins is earlier than the steering operation start time t (time t61) when the curve radius R is small than when the curve radius R is large.

[0094] In addition, the look-ahead time τ is set to a longer time when the vehicle speed V is high than when the vehicle speed V is low, so that the time t60 at which setting of the guide steering angle θg begins is earlier than the steering operation start time t (time t61) when the vehicle speed V is high than when the vehicle speed V is low.

[0095] Furthermore, since the gain a is set to a smaller value when the curve radius R is small compared to when the curve radius R is large, the maximum value θmax of the guide steering angle θg is set to a smaller value when the curve radius R is small compared to when the curve radius R is large.

[0096] In addition, since the gain a is set to a smaller value when the vehicle speed V is high than when the vehicle speed V is low, the maximum value θmax of the guide steering angle θg is set to a smaller value when the vehicle speed V is high than when the vehicle speed V is low.

[0097] From the above, when the curve radius R is large and the vehicle speed V is low, the guide steering angle θg changes over time as shown by line Lg in Figure 6(A), and when the curve radius R is small and the vehicle speed V is high, the guide steering angle θg changes over time as shown by line Lg in Figure 6(B).

[0098] Then, when the vehicle steering control device 10 sets the guide steering angle θg, if the actual steering angle θ is smaller than the guide steering angle θg, the greater the difference (steering angle difference Δθ) between the actual steering angle θ and the guide steering angle θg, the smaller the steering reaction force is made to be than the reference steering reaction force.

[0099] On the other hand, when the actual steering angle θ becomes larger than the guide steering angle θg, the vehicle steering control device 10 makes the steering reaction force larger than the reference steering reaction force as the difference between the actual steering angle θ and the guide steering angle θg (steering angle difference Δθ) becomes larger.

[0100] The above is an outline of the operation of the vehicle steering control device 10 according to the modified embodiment of the present invention.

[0101] If the steering reaction force is reduced when the time arrives for the driver DR to start steering the vehicle 100 to travel along the curved road (steering start time), it will be easier for the driver DR to perform steering operations to travel the vehicle 100 along the curved road, but the steering operation may be delayed, and the vehicle 100 may not be able to travel smoothly along the curved road.

[0102] According to the vehicle steering control device 10 of this embodiment, setting of the guide steering angle θg (guide steering operation amount) is started earlier than the steering wheel operation start time (steering operation start time), and as a result, the steering reaction force is reduced earlier. Therefore, even when the curve radius R is small (when the curve road is curved greatly), the steering wheel operation (steering operation) for running the host vehicle 100 along the curve road is performed without delay, and as a result, the host vehicle 100 can be suitably run along the curve road.

[0103] Furthermore, when the curve radius R is small, the driver DR needs to make a larger steering effort to drive the vehicle 100 along the curve, which increases the possibility that the driver DR will make a delayed steering effort.

[0104] According to the vehicle steering control device 10 of this embodiment, when the curve radius R is small, the look-ahead time τ (predetermined time) for accelerating the timing of starting to set the guide steering angle θg is set to a long time, so that the setting of the guide steering angle θg is started at an earlier timing than the time when the driver DR starts the steering operation to make the vehicle 100 run along the curved road, and as a result, the steering reaction force is reduced at an earlier timing. Therefore, it is possible to suppress delay in the steering operation by the driver DR. Therefore, while the vehicle 100 is running on the curved road, the actual steering angle θ changes in a state that coincides (or approximately coincides) with the target steering angle θtgt, so that the vehicle 100 can be run suitably along the curved road.

[0105] Furthermore, when the vehicle speed V (the traveling speed of the vehicle 100) is high, the driver DR needs to operate the steering wheel faster in order to drive the vehicle 100 along a curved road, so there is a high possibility that the driver DR will operate the steering wheel late.

[0106] According to the vehicle steering control device 10 of this example, when the vehicle speed V is high, the look-ahead time τ for accelerating the timing of starting to set the guide steering angle θg is set to a long time, so that the setting of the guide steering angle θg is started at an earlier timing than the time when the driver DR starts the steering operation to make the vehicle 100 run along the curved road, and as a result, the steering reaction force is reduced at an earlier timing. Therefore, it is possible to suppress delay in the steering operation by the driver DR. Therefore, while the vehicle 100 is running on the curved road, the actual steering angle θ changes in a state that coincides (or approximately coincides) with the target steering angle θtgt, so that the vehicle 100 can be run suitably along the curved road.

[0107] In addition, when the driver DR drives the vehicle 100 along a curved road, the driver DR increases the steering angle θ (amount of steering operation) and then decreases the steering angle θ. At this time, when the steering angle θ approaches the maximum value of the target steering angle θtgt (target steering operation amount) defined by the steering angle change target, the steering angle θ may be increased beyond the maximum value.

[0108] According to the vehicle steering control device 10 of this embodiment, the maximum value θmax of the guide steering angle θg is limited to a value smaller than the maximum value of the target steering angle θtgt by a predetermined value. Therefore, when the steering angle θ approaches the maximum value of the target steering angle θtgt, the steering reaction force is increased. Therefore, it is possible to suppress the steering operation by the driver DR from exceeding the maximum value of the target steering angle θtgt. Therefore, while the vehicle 100 is traveling on a curved road, the actual steering angle θ changes in a state that coincides (or approximately coincides) with the target steering angle θtgt, so that the vehicle 100 can be suitably traveled along the curved road.

[0109] Furthermore, when the vehicle speed V is high, the driver DR tends to increase the steering speed in order to drive the vehicle 100 along a curved road, and therefore the driver DR is unable to stop the steering at an appropriate steering angle, which can easily result in the steering angle becoming too large.

[0110] According to the vehicle steering control device 10 of this example, when the vehicle speed V is high, the predetermined value for making the maximum value θmax of the guide steering angle θg smaller than the maximum value of the target steering angle θtgt is set to a large value, so that when the steering angle θ exceeds the guide steering angle θg and approaches the maximum value of the target steering angle θtgt while the vehicle speed V is high, the degree to which the steering reaction force increases increases. Therefore, it is possible to appropriately suppress the steering angle θ from exceeding the maximum value of the target steering angle θtgt. Therefore, while the vehicle 100 is traveling on a curved road, the actual steering angle θ changes in a state that coincides (or approximately coincides) with the target steering angle θtgt, so that the vehicle 100 can be suitably traveled along the curved road.

[0111] In the above example, when the vehicle 100 travels on a curved road with the same curve radius R, the gain a is set to a smaller value when the vehicle speed V is high compared to when the vehicle speed V is low in order to prevent the actual steering angle from greatly exceeding the target steering angle θtgt. As a result, the maximum value of the guide steering angle θg is reduced, and a larger steering reaction force F is applied to the steering operation. However, even when the vehicle 100 travels on a curved road with the same curve radius R, when the vehicle speed V is high, in order to properly drive the vehicle 100 along the curved road, it is necessary to perform a larger steering operation compared to when the vehicle speed V is low, so that the actual steering angle θ becomes a larger value. In this case, if a larger steering reaction force F is applied to the steering operation, it becomes difficult for the driver DR to perform the steering operation.

[0112] Therefore, when the vehicle speed V is high, the vehicle steering control device 10 sets the gain a to a small value so as to prevent the actual steering angle from significantly exceeding the target steering angle θtgt compared to when the vehicle speed V is low, but the value by which the gain a is reduced may be configured to be limited to a value that prevents the driver DR from having difficulty in operating the steering wheel.

[0113] Furthermore, when the curve radius R is small, the driver DR needs to make a larger steering effort to drive the vehicle 100 along the curve, so there is a high possibility that the steering angle θ will exceed the maximum value of the target steering angle θtgt defined by the steering angle change target.

[0114] According to the vehicle steering control device 10 of this embodiment, when the curve radius R is small, the predetermined value for making the maximum value θmax of the guide steering angle θg smaller than the maximum value of the target steering angle θtgt is set to a large value, so that when the curve radius R is small and the steering angle θ approaches the maximum value of the target steering angle θtgt, the degree to which the steering reaction force is reduced is reduced. That is, the steering reaction force becomes large. Therefore, it is possible to appropriately suppress the steering angle θ from exceeding the maximum value of the target steering angle θtgt. Therefore, while the vehicle 100 is traveling on a curved road, the actual steering angle θ changes in a state that coincides (or approximately coincides) with the target steering angle θtgt, so that the vehicle 100 can be suitably traveled along the curved road.

[0115] <Specific Operation of Vehicle Steering Control Device According to Modification> Next, a specific operation of the vehicle steering control device 10 according to the modified embodiment of the present invention will be described. The CPU of the ECU 90 of the vehicle steering control device 10 executes the routine shown in Fig. 7 at a predetermined calculation cycle. Therefore, at a predetermined timing, the CPU starts the process from step 700 in Fig. 7, advances the process to step 705, and determines whether or not the curved road entry condition is satisfied.

[0116] The curved road entry condition is a condition that a curved road that the vehicle 100 is predicted to enter within a predetermined time is detected. Therefore, the curved road entry condition is satisfied when such a curved road is detected, and is not satisfied when the vehicle 100 has finished traveling the curved road. Therefore, the curved road entry condition is satisfied while the vehicle 100 is traveling the curved road after such a curved road is detected, and is not satisfied at other times. The vehicle steering control device 10 may be configured to determine whether the curved road entry condition is satisfied based on the position of the vehicle 100 identified from the GPS signal and the map information in the map information database 72.

[0117] If the CPU determines "Yes" in step 705, the process proceeds to step 710, where it acquires the curve radius R and the vehicle speed V. Next, the CPU proceeds to step 715, where it applies the curve radius R and the vehicle speed V acquired in step 710 to the above formulas 6 and 7, respectively, to acquire the look-ahead time τ and the gain a. Next, the CPU proceeds to step 720, where it applies the look-ahead time τ and the gain a acquired in step 715 to the above formula 5, to acquire the guide steering angle θg.

[0118] Next, the CPU advances the process to step 725 and acquires the difference (steering angle difference Δθ) between the guide steering angle θg acquired in step 720 and the actual steering angle θ. Next, the CPU advances the process to step 730 and acquires the target steering reaction force Ftgt based on the steering angle difference Δθ acquired in step 725. Next, the CPU advances the process to step 735 and controls the operation of the reaction force actuator 232 so that a steering reaction force equivalent to the target steering reaction force Ftgt acquired in step 730 is applied to the steering wheel 35. Next, the CPU advances the process to step 795 and temporarily ends this routine.

[0119] On the other hand, if the CPU determines "No" in step 705, it proceeds directly to step 795 and ends this routine for the time being.

[0120] The above is a specific operation of the vehicle steering control device 10 according to the modified embodiment of the present invention.

[0121] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0122] 10...vehicle steering control device, 23...steering device, 35...handle, 37...steering angle sensor, 38...steering torque sensor, 60...surrounding information detection device, 62...image sensor, 70...road information detection device, 71...GPS device, 72...map information database, 90...ECU, 232...reaction actuator< / ecu>

Claims

1. A control device is provided for controlling a steering reaction force applied to a steering operation performed by a driver of the vehicle, The control device is configured to set a target for a change in the amount of the steering operation when the vehicle is caused to travel along a curved road, set a guide steering operation amount that guides the steering operation by the driver so that a change in the amount of the steering operation according to the target is achieved when the vehicle is traveling along the curved road, and reduce the steering reaction force when an actual amount of the steering operation is smaller than the guide steering operation amount. In a vehicle steering control device, The control device includes: When a curved road is detected ahead of the vehicle, a time when the driver starts a steering operation for driving the vehicle along the curved road is predicted as a steering operation start time; The steering reaction force is reduced at a time point a predetermined time before the steering operation start time. It is configured as follows: Vehicle steering control device.

2. 2. The vehicle steering control device according to claim 1, The control device is configured to set the predetermined time to a longer time when the degree of curvature of the curved road is large compared to when the degree of curvature of the curved road is small. Vehicle steering control device.

3. 3. The vehicle steering control device according to claim 1, The control device is configured to set the predetermined time to a longer time when the traveling speed of the host vehicle is high, compared to when the traveling speed of the host vehicle is low. Vehicle steering control device.

4. The vehicle steering control device according to any one of claims 1 to 3, The control device is configured to limit a maximum value of the guide steering operation amount to a value smaller by a predetermined value than a maximum value of the amount of the steering operation that changes at the target. Vehicle steering control device.

5. 5. The vehicle steering control device according to claim 4, The control device is configured to set the predetermined value to a larger value when the traveling speed of the host vehicle is high, compared to when the traveling speed of the host vehicle is low. Vehicle steering control device.

6. 6. The vehicle steering control device according to claim 4 or 5, The control device is configured to set the predetermined value to a larger value when the degree of curvature of the curved road is large compared to when the degree of curvature of the curved road is small. Vehicle steering control device.

7. A vehicle steering control device including a control device that controls a steering reaction force applied to a steering operation performed by a driver of a vehicle, The control device is configured to make the steering reaction force applied to the steering operation when the vehicle is traveling along a curved road smaller when the curve of the curved road is large than when the curve of the curved road is small. Vehicle steering control device.

8. 8. The vehicle steering control device according to claim 7, The curvature of the curved road is the minimum curve radius of the curved road, The control device includes: When the minimum curve radius of the curved road is small, a curve radius of the curved road at a point farther forward from the vehicle is acquired compared to when the minimum curve radius of the curved road is large; When the acquired curve radius is small, the steering reaction force is made smaller than when the acquired curve radius is large. It is configured as follows: Vehicle steering control device.

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