WO2014097541A1 - Steering control device and steering control method - Google Patents

Abstract

The present invention improves operator feeling by adjusting timing when imparting assist torque to a steering mechanism according to the curvature of the road. In order to turn and drive along a vehicle route, assist torque (TA) in the turning direction is imparted according to the curvature (ρ) of the road at a forward position (X). When imparting the assist torque (TA) in the turning direction, the forward position (X) changes according to the orientation and size of the steering torque (Ts). For example, when transitioning from driving straight to driving along a curve, the forward position (X) changes to a position near the vehicle when the steering torque (Ts) is opposite the turning direction and the absolute value of the steering torque (Ts) reaches or exceeds a pre-set first threshold (Te1). In addition, when transitioning from driving straight to driving along a curve, the forward position (X) changes to a position far from the vehicle when the steering torque (Ts) is the same as the turning direction and the absolute value of the steering torque (Ts) reaches or exceeds a pre-set first threshold (Tt1).

Description

Steering control device and steering control method

The present invention relates to a steering control device and a steering control method.

Patent Document 1 describes that the control for preventing lane departure is stopped when the own vehicle greatly deviates from the traveling lane and the lateral deviation amount with respect to the traveling lane becomes larger than the threshold value. Is set according to the steering torque. For example, when the steering torque is large, it is considered that the operation is an intentional operation. Therefore, the control stop timing is advanced by setting the threshold value to a small value. On the other hand, when the steering torque is small, the operation is not necessarily an intentional operation, so the control stop timing is delayed by setting the threshold value to a large value.

JP 2011-168194 A

Although the above technique is intended to improve the control stop timing, it is also necessary to consider the timing when the control is executed. For example, in a configuration in which assist torque is applied to the steering mechanism according to the curvature of the curve when traveling on a curve, if the assist torque deviates from the timing of the driver's steering operation, the operation feeling is reduced.
The subject of this invention is adjusting the timing at the time of giving assist torque to a steering mechanism according to a road curvature, and improving an operation feeling.

The steering control device according to one aspect of the present invention detects the road curvature ahead of the own vehicle course, and turns in the turning direction in accordance with the road curvature at a predetermined forward position in order to turn along the own car course. Assist torque is applied to the steering mechanism. Further, when detecting the steering torque of the driver and controlling the assist torque in the turning direction, the front position is changed according to the direction and magnitude of the steering torque.

According to the present invention, when the assist torque in the turning direction is controlled, the front position is changed according to the direction and magnitude of the steering torque. Therefore, the timing when the assist torque is applied is adjusted, and the operation feeling is adjusted. Can be improved.

It is a schematic block diagram of the steering device by a steering by wire. 2 is a schematic configuration of the controller 20. It is a map used for calculation of the steering angle ratio R according to the vehicle speed V. It is a map used for calculation of the steering angle ratio R according to the steering angle θs. 3 is a block diagram showing an operation side motor control unit 22. FIG. It is a flowchart which shows a steering reaction force setting process. It is a flowchart which shows the assist torque setting process of 1st Embodiment. It is a graph which shows the relationship between steering angle (theta) s and steering torque Ts. It is a figure which shows the relationship between the steering angle (theta) s according to the vehicle speed V, and the steering torque Ts. It is a figure which shows the relationship between the steering angle (theta) s according to the road surface friction coefficient (micro | micron | mu) s, and the steering torque Ts. It is a time chart which shows assist torque TA and steering torque Ts when a driver feels too early. It is a time chart which shows assist torque TA and steering torque Ts when a driver feels too late. It is a flowchart which shows the assist torque setting process of 2nd Embodiment. It is a time chart which shows assist torque TA and steering torque Ts when a driver feels that it is too early in 2nd Embodiment. It is a flowchart which shows the assist torque setting process of 3rd Embodiment. It is a time chart which shows assist torque TA and steering torque Ts when a driver feels that it is too early in 3rd Embodiment. It is a time chart which shows the assist torque TA and steering torque Ts when a driver feels that it is too late in 3rd Embodiment. It is a flowchart which shows the assist torque setting process of 4th Embodiment. It is a time chart which shows assist torque TA and steering torque Ts when a driver feels too early in a 4th embodiment. It is a flowchart which shows the assist torque setting process of 5th Embodiment. It is a graph which shows the relationship between steering angle (theta) s and steering torque Ts in 5th Embodiment. It is a flowchart which shows the assist torque setting process of 6th Embodiment. It is a flowchart which shows the assist torque setting process of 7th Embodiment. It is a flowchart which shows the assist torque setting process of 8th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<< First Embodiment >>
"Constitution"
In the present embodiment, driving operation support is performed by guiding the steering operation of the driver. In particular, in a scene where a certain amount of operation amount and operation accuracy at a very low speed are required, appropriate steering is performed. It encourages operation.
FIG. 1 is a schematic configuration diagram of a steering device using steering-by-wire.
The steering wheel 1 is connected to a steering shaft 2, and steered wheels (steering wheels) 3L and 3R are connected to a pinion shaft 7 through a knuckle arm 4, a tie rod 5, and a rack and pinion 6 in this order. The steering shaft 2 and the pinion shaft 7 are connected via a clutch 10 so as to be able to be interrupted.
Therefore, in a state where the clutch 10 is connected (fastened), when the steering wheel 1 is rotated, the steering shaft 2, the clutch 10, and the pinion shaft 7 are rotated. The rotational movement of the pinion shaft 7 is a forward and backward movement of the tie rod 5 by the rack and pinion 6, and the steered wheels 3L and 3R are steered through the knuckle arm 4.

A steered side motor 9 is connected to the pinion shaft 7. When the steered side motor 9 is driven in a state where the clutch 10 is disconnected, the pinion shaft 7 rotates, so that the steered wheels 3L and 3R are rotated. Steered. Therefore, the steering angle θw of the steered wheels 3L and 3R is controlled by detecting the steering angle θs of the steering wheel 1 and drivingly controlling the steered side motor 9 according to the detected steering angle θs.
An operation side motor 8 is connected to the steering shaft 2. When the operation side motor 8 is driven in a state where the clutch 10 is disconnected, a reaction torque is applied to the steering shaft 2. Accordingly, the reaction force received from the road surface when the steered wheels 3L and 3R are steered is detected or estimated, and the operation side motor 8 is driven and controlled in accordance with the detected or estimated reaction force, so that the driver can perform the steering operation. In contrast, an operation reaction force is applied.

Normally, the steering side motor 9 is driven and controlled while the clutch 10 is disengaged, and the operation side motor 8 is driven and controlled to execute steer-by-wire to realize desired steering characteristics and turning behavior characteristics. In addition, a good operation feeling is realized. On the other hand, when an abnormality occurs in the system, the steer-by-wire is stopped and the clutch 10 is returned to the engaged state as fail-safe to ensure mechanical backup.
The steered side motor 9 and the operation side motor 8 are driven and controlled by a controller 20 constituted by, for example, a microcomputer. The controller 20 inputs various signals detected by the steering angle sensor 11, the turning angle sensor 12, the hub sensor 13, the vehicle speed sensor 14, the yaw rate sensor 15, the torque sensor 31, and the lateral acceleration sensor 32. Further, the controller 20 inputs various data from the front camera 33 and the navigation system 34.

The steering angle sensor 11 detects the steering angle θs of the steering shaft 2. The steering angle sensor 11 detects, for example, rotation of a magnet built in a detection gear that rotates in synchronization with the steering shaft 2 by two MR (ferro-Magneto Resistance) elements, and a magnetic field accompanying rotation of the steering shaft 2. The direction vector change is converted into an electric signal and input to the controller 20. The controller 20 determines the steering angle θs of the steering shaft 2 from the input electric signal. The steering angle sensor 11 detects right turn as a positive value and detects left turn as a negative value.

The turning angle sensor 12 detects the turning angle θw of the pinion shaft 7. The turning angle sensor 12 detects, for example, rotation of a magnet built in a detection gear that rotates in synchronization with the pinion shaft 7 with two MR (ferro-Magneto®Resistance) elements, and accompanies the rotation of the pinion shaft 7. The vector change in the magnetic field direction is converted into an electrical signal and input to the controller 20. The controller 20 determines the turning angle θw of the pinion shaft 7 from the input electrical signal. The turning angle sensor 12 detects a right turn as a positive value and a left turn as a negative value.

The hub sensor 13 detects the tire lateral force Fy. The hub sensor 13 is provided in each hub unit of the left and right wheels, and converts, for example, a change in displacement difference between the inner ring and the outer ring in a bearing in the hub unit into an electric signal using a hall element and a magnetized encoder. Input to the controller 20. The controller 20 determines the tire lateral force from the input electrical signal. The tire lateral force Fy is a total value of the tire lateral forces of the left and right wheels detected by the hub sensor 13.
The vehicle speed sensor 14 detects a vehicle body speed (hereinafter referred to as a vehicle speed) V. This vehicle speed sensor 14 is provided, for example, in a driven gear on the output side of the transmission, detects the magnetic lines of force of the sensor rotor by a detection circuit, converts the change in the magnetic field accompanying the rotation of the sensor rotor into a pulse signal, and inputs it to the controller 20. To do. The controller 20 determines the vehicle speed V from the input pulse signal.

The yaw rate sensor 15 detects the yaw rate γ of the vehicle body. The yaw rate sensor 15 is provided on a body on a spring, and vibrates a vibrator made of, for example, a crystal tuning fork with an alternating voltage, and converts the distortion amount of the vibrator caused by the Coriolis force at the time of angular velocity input into an electric signal. Input to the controller 20. The controller 20 determines the yaw rate γ of the vehicle from the input electric signal. The yaw rate sensor 15 detects right turn as a positive value and detects left turn as a negative value.
The torque sensor 31 detects the torque Ts input to the steering shaft 2. The torque sensor 31 detects the torsion angle of the torsion bar interposed between the input side and the output side of the steering shaft 2 with, for example, a Hall element, and generates magnetic flux as a relative angular displacement between the multipolar magnet and the yoke. The change in density is converted into an electrical signal and input to the controller 20. The torque sensor 31 detects the right steering of the driver as a positive value and detects the left steering as a negative value.

The lateral acceleration sensor 32 detects the lateral acceleration of the vehicle. The lateral acceleration sensor 9 detects, for example, the displacement of the movable electrode relative to the fixed electrode as a change in capacitance, and converts it into a voltage signal proportional to the lateral acceleration and inputs it to the controller 6. The controller 6 determines the lateral acceleration from the input voltage signal.
In addition, although the controller 20 inputs each detection signal directly from sensors, it is not limited to this. The controller 20 is connected to another control unit, and receives various data via an in-vehicle communication network (in-vehicle LAN) such as CSMA / CA multiplex communication (CAN: Controller Area Network) or Flex Ray. May be.
The front camera 33 images the front of the vehicle body. The front camera 33 is composed of, for example, a CCD wide-angle camera provided in the upper part of the front window in the vehicle interior, and inputs imaged image data in front of the vehicle body to the controller 20.

The navigation system 17 recognizes the current position of the host vehicle and road information at the current position. This navigation system 17 has a GPS receiver, and recognizes the position (latitude, longitude, altitude) of the host vehicle and the traveling direction based on the time difference between radio waves arriving from four or more GPS satellites. Then, the road information including the road type, road alignment, lane width, vehicle traffic direction, etc. stored in the DVD-ROM drive or hard disk drive is referred to, and the road information at the current position of the host vehicle is recognized. input. In addition, as a safe driving support system (DSSS: Driving Safety Support Systems), two-way wireless communication (DSRC: Dedicated Short Range Communication) may be used to receive various data from the infrastructure.

FIG. 2 is a schematic configuration of the controller 20.
As shown in FIG. 2, the controller 20 includes a steered side motor control unit 21 that drives and controls the steered side motor 9, and an operation side motor control unit 22 that drives and controls the operation side motor 8.
The steered side motor control unit 21 controls the steered angle θw by driving the steered side motor 9 after determining the steered angle ratio R (= θs / θw) of the steered angle θw with respect to the steered angle θs. To do.
The steering angle ratio R is determined, for example, in the following manner.
For example, the steering angle ratio R is calculated according to the vehicle speed V with reference to the map of FIG.
FIG. 3 is a map used to calculate the steering angle ratio R according to the vehicle speed V.
According to this map, the steering angle ratio R decreases as the vehicle speed V decreases. Therefore, at the time of stationary driving or low speed traveling, a large turning angle θw can be obtained with a small steering angle θs, so that the operation burden on the driver is reduced. On the other hand, during high speed traveling, the change in the steering angle θw with respect to the change in the steering angle θs is suppressed, so that sensitive vehicle behavior is suppressed and traveling stability is ensured.

Further, the steering angle ratio R may be calculated according to the steering angle θs with reference to the map of FIG.
FIG. 4 is a map used for calculating the steering angle ratio R according to the steering angle θs.
According to this map, the steering angle ratio R increases as the steering angle θs decreases. Therefore, as the steering angle θs is further increased, a larger turning angle θw is obtained, so that the operation burden on the driver is reduced. On the other hand, in a scene such as when traveling substantially straight, the change in the turning angle θw with respect to the change in the steering angle θs is suppressed, so that a sensitive vehicle is suppressed and traveling stability is ensured.
The steering angle ratio R may be determined according to both the vehicle speed V and the steering angle θs. That is, the steering angle ratio Rv corresponding to the vehicle speed V and the steering angle ratio Rs corresponding to the steering angle θs are individually calculated, and an average of these is calculated or added after weighting each. Thus, the final steering angle ratio R may be determined.
As described above, after determining the steering angle ratio R, the target turning angle θw ^* is calculated according to the steering angle θs and the steering angle ratio R, and the turning angle θw is included in the target turning angle θw ^*. For example, the driving of the steered side motor 9 is controlled using a robust model matching method or the like.

FIG. 5 is a block diagram showing the operation side motor control unit 22.
The operation side motor control unit 22 includes a steering reaction force setting unit 23, an assist torque setting unit 24, an addition unit 25, and a drive control unit 26.
The steering reaction force setting unit 23 sets a steering reaction force TR for the driver's steering operation. Further, the assist torque setting unit 24 sets an assist torque TA for turning along the own vehicle path. The adding unit 25 adds the steering reaction force TR and the assist torque TA to set the final drive torque TD. Further, the drive control unit 26 drives and controls the operation side motor 8 according to the drive torque TD.

Next, a steering reaction force setting process executed by the steering reaction force setting unit 23 will be described.
FIG. 6 is a flowchart showing the steering reaction force setting process.
First, in step S101, the steering speed dθs is calculated by differentiating the steering angle θs with respect to time.
In the subsequent step S102, as shown in (1) below, the angular term torque TRa is calculated by multiplying the steering angle θs by the gain Ka.
TRa = Ka × θs (1)
In the subsequent step S103, the speed term torque TRs is calculated by multiplying the steering speed dθs by the gain Ks as shown in the following equation (2).
TRs = Ks × dθs (2)
In the subsequent step S104, the steering reaction force Tr is calculated by adding the angular torque TRa and the speed term torque TRs as shown in the following equation (3).
TR = TRa + TRs (3)

In the following step S105, the road surface friction coefficient μ is calculated based on the vehicle speed V, the yaw rate γ, and the lateral acceleration Yg, for example. Further, the road surface friction coefficient μ may be estimated according to the relationship between the braking / driving force of each wheel and the slip ratio, and if the road surface friction coefficient μ is available from the infrastructure, it may be used.
In subsequent step S106, an upper limit value TL of the steering reaction force is calculated based on the vehicle speed V, the steering angle θs, and the road surface friction coefficient μ.
In the subsequent step S107, the smaller one of the steering reaction force TR and the upper limit value TL is calculated as the final steering reaction force TR, and then the process returns to a predetermined main program.
The above is the steering reaction force setting process.

Next, an assist torque setting process executed by the assist torque setting unit 24 will be described.
FIG. 7 is a flowchart showing the assist torque setting process of the first embodiment.
First, in step S111, first threshold values Te1 and Tt1 for the steering torque Ts when the assist torque TA is controlled are set. The first threshold Te1 is a threshold for determining that the assist torque TA is too early, and is set to about ± 1 Nm, for example. The first threshold value Tt1 is a threshold value for determining that the assist torque TA is too slow, and is set to about ± 1 Nm, for example. These first threshold values Te1 and Tt1 may not be the same value.

Here, the relationship between the assist torque TA and the steering torque Ts regarding the setting of the first thresholds Te1 and Tt1 will be described.
FIG. 8 is a graph showing the relationship between the steering angle θs and the steering torque Ts.
The relationship between the steering angle θs and the steering torque Ts is expressed by coordinates with the steering angle θs as the horizontal axis and the steering torque Ts as the vertical axis, with the right turn being a positive value and the left turn being a negative value.
First, the characteristic line Ln shows the relationship between the steering angle θs and the steering torque Ts when a steering operation is performed with a conventional steering mechanism that does not apply the assist torque TA. According to the characteristic line Ln, when the steering torque Ts is increased in the positive direction from 0, the steering angle θs is increased in the positive direction from 0 (initial steering angle), and when the steering torque Ts is decreased in the negative direction, the steering angle is increased. θs decreases from 0 in the negative direction. When the absolute value of the steering angle θs is increased, a relatively large steering torque Ts is required at the initial stage of the steering operation.

Next, the relationship between the steering angle θs and the steering torque Ts when the assist torque TA is applied is indicated by a characteristic line La. Here, a scene that runs along a curve in the right direction will be described as an example. First, a steering angle θs for traveling along a curve is set as a required steering angle, a steering torque Ts for obtaining the required steering angle is set as a required torque, and this required torque is set as an assist torque TA. With this assist torque TA, the required steering angle is achieved even when the steering torque Ts of the driver is zero.
A relationship between the steering angle θs and the steering torque Ts in a state where the assist torque TA is applied is indicated by a characteristic line La. This characteristic line La is obtained by translating the characteristic line Ln in the positive direction along the horizontal axis by the required steering angle. According to this characteristic line La, when the steering torque Ts is increased from 0 to the positive direction, the steering angle θs is increased from the required steering angle to the positive direction, and when the steering torque Ts is decreased from 0 to the negative direction, the steering angle is increased. θs decreases in the negative direction from the required steering angle.

Next, when shifting from straight traveling to curve traveling, an assist torque TA corresponding to a predetermined road curvature ρ is applied to the steering torque Ts when the steering angle θs increases from 0 to the required steering angle. Pay attention to. Here, it is assumed that the driver is holding the steering wheel 1.
First, the characteristic line Ls shows the relationship between the steering angle θs and the steering torque Ts when the control of the assist torque TA in the positive direction and the steering operation of the driver are performed substantially simultaneously (synchronously). In this characteristic line Ls, the driver performs the steering operation himself in hope of increasing the steering angle θs in the positive direction. However, since the assist torque TA is controlled almost simultaneously with the steering angle Ts, the steering torque Ts becomes substantially 0, and the steering is performed as it is. The angle θs increases in the positive direction and the required steering angle is achieved. Thus, when the assist torque TA in the turning direction is controlled substantially simultaneously with the driver's steering operation, the steering torque Ts becomes substantially zero.

On the other hand, the relationship between the steering angle θs and the steering torque Ts when the driver feels too early for the control of the assist torque TA in the positive direction is indicated by a characteristic line Le. In this characteristic line Le, when the assist torque TA in the positive direction starts to be applied, the driver does not yet want to increase the steering angle θs in the positive direction, so the steering is held against the assist torque TA in the positive direction. Therefore, the direction of the steering torque Ts is generated in the negative direction. However, when the vehicle further moves forward, the driver wants to increase the steering angle θs in the positive direction, so this time, the steering torque Ts in the negative direction is relaxed and the assist torque TA is followed (or left). Accordingly, the steering torque Ts in the negative direction increases in the positive direction along the characteristic line La and eventually becomes 0, and at this time, the necessary steering angle is achieved.
Thus, when the driver feels that the assist torque TA is controlled too early in the turning direction, the direction of the steering torque Ts is opposite to the turning direction. Therefore, in this embodiment, when the direction of the steering torque Ts is opposite to the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold value Te1, the driver is quicker than the control of the assist torque TA. Judge that you feel too much.

Conversely, the relationship between the steering angle θs and the steering torque Ts when the driver feels that the driver is too slow with respect to the control of the assist torque TA in the forward direction is indicated by a characteristic line Lt. In this characteristic line Lt, since the driver desires to increase the steering angle θs in the positive direction before the assist torque TA, the driver himself increases the steering torque Ts in the positive direction. At this time, the steering torque Ts increases in the positive direction along the characteristic line Ln. However, when the vehicle further moves forward, the positive assist torque TA starts to be applied, so that the positive steering torque Ts is relaxed and the assist torque TA is followed (or left). In addition, when the steering torque Ts is increased in the positive direction and the assist torque TA in the positive direction is further applied, the steering angle θs tends to overshoot beyond the necessary steering angle. Accordingly, since the correction steering is performed to return the steering angle θs by the excessive amount, the forward steering torque Ts decreases along the characteristic line La and eventually becomes 0, and the necessary steering angle is achieved at this time. .

Thus, when the driver feels that the control of the assist torque TA in the turning direction is too slow, the direction of the steering torque Ts is the same as the turning direction. Therefore, in the present embodiment, when the direction of the steering torque Ts is the same as the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold value Tt1, the driver is delayed with respect to the control of the assist torque TA. Judge that you feel too much.
The above is the relationship between the assist torque TA and the steering torque Ts regarding the setting of the first thresholds Te1 and Tt1.
In subsequent step S112, the vehicle speed V is read.
In the subsequent step S113, the threshold values Te1 and Tt1 are adjusted according to the vehicle speed V.
Here, the absolute values of the thresholds Te1 and Tt1 are adjusted to a larger value as the vehicle speed V is higher, and the absolute values of the thresholds Te1 and Tt1 are adjusted to a smaller value as the vehicle speed V is lower. This is because in order to obtain the same steering angle θs while traveling, a larger steering torque Ts is required as the vehicle speed V is higher.

FIG. 9 is a diagram showing the relationship between the steering angle θs and the steering torque Ts according to the vehicle speed V.
For example, when the steering angle θs is about 3 deg, the steering torque Ts is about 1.0 Nm when the vehicle speed V is about 100 km / h, but the steering torque Ts is about 1.3 Nm when the vehicle speed V is about 120 km / h. Thus, when the vehicle speed V is about 60 km / h, the steering torque Ts is about 0.7 Nm. Therefore, the absolute values of the threshold values Te1 and Tt1 are adjusted to larger values as the vehicle speed V is higher, and the absolute values of the threshold values Te1 and Tt1 are adjusted to smaller values as the vehicle speed V is lower.

In the subsequent step S114, the road surface friction coefficient μ is acquired.
For example, the road surface friction coefficient μ is calculated based on the vehicle speed V, the yaw rate γ, and the lateral acceleration Yg. Further, the road surface friction coefficient μ may be estimated according to the relationship between the braking / driving force of each wheel and the slip ratio, and if the road surface friction coefficient μ is available from the infrastructure, it may be used.
In subsequent step S115, the threshold values Te1 and Tt1 are adjusted according to the road surface friction coefficient μ.
Here, the absolute values of the threshold values Te1 and Tt1 are adjusted to smaller values as the road surface friction coefficient μ is lower, and the absolute values of the threshold values Te1 and Tt1 are adjusted to larger values as the road surface friction coefficient μ is higher. This is because, in order to obtain the same steering angle θs, a smaller steering torque Ts is required as the road surface friction coefficient μ is lower.

FIG. 10 is a diagram showing the relationship between the steering angle θs and the steering torque Ts according to the road surface friction coefficient μ.
For example, when the steering angle θs is set to about 3 degrees, the steering torque Ts is about 1.0 Nm on a normal road surface with a high road surface friction coefficient μ such as a dry road, for example, a rainy road, a snowy road, a frozen road, etc. When the road surface is a slippery road surface having a low friction coefficient μ, the steering torque Ts is about 0.7 Nm. Therefore, the absolute values of the threshold values Te1 and Tt1 are adjusted to smaller values as the road surface friction coefficient μ is lower, and the absolute values of the threshold values Te1 and Tt1 are adjusted to larger values as the road surface friction coefficient μ is higher.
In subsequent step S116, the road curvature ρ at the forward position X is detected. Here, the forward position X is a distance from the host vehicle.
Here, it is calculated from image data picked up by the front camera 33, or acquired based on the current position of the host vehicle recognized by the navigation system 17 and road information at the current position.

In the subsequent step S117, the assist torque TA is set according to the road curvature ρ at the forward position X.
Here, the required steering angle corresponding to the road curvature ρ of the forward position X is calculated, for example, the required torque required to achieve the required steering angle is calculated according to the above-described characteristic line Ln, and this required torque amount is calculated. Set as assist torque TA.
In the subsequent step S118, the assist torque TA is output to the adding unit 25. As a result, the drive control unit 26 drives and controls the operation side motor 8 according to the final drive torque TD obtained by adding the steering reaction force TR and the assist torque TA.
In the subsequent step S119, the steering torque Ts is read.
In the subsequent step S120, the signs of the steering torque Ts and the road curvature ρ are determined, and it is determined whether or not the direction of the steering torque Ts and the direction of the road curvature ρ are opposite. Here, when the steering torque Ts and the road curvature ρ are in the opposite directions, it is determined that the application of the assist torque TA is earlier than the driver's steering operation, and the process proceeds to step S121. On the other hand, when the steering torque Ts and the road curvature ρ are in the same direction, it is determined that the application of the assist torque TA is later than the steering operation by the driver, and the process proceeds to step S123.

In step S121, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold Te1. Here, when the determination result is “| Ts | ≧ | Te1 |”, it is determined that the driver feels too early with respect to the timing of applying the assist torque TA, and the process proceeds to step S122. On the other hand, when the determination result is “| Ts | <| Te1 |”, it is determined that the driver does not feel that it is too early with respect to the timing of applying the assist torque TA, and the predetermined main program is directly executed. Return.
In step S122, in order to delay the timing for applying the assist torque TA, the front position X at which the road curvature ρ is read is corrected to the front. That is, as shown below, a position (X−ΔX) that is closer to the front by a predetermined distance ΔX from the front position X is corrected to a new front position X and then returned to a predetermined main program. In the subsequent calculation, the corrected road curvature ρ at the forward position X is read. In order to avoid a sudden change in the forward position X, the forward position X is changed by a predetermined allowable amount per unit time.
X ← X-ΔX

In step S123, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold value Tt1 described above. Here, when the determination result is “| Ts | ≧ | Tt1 |”, it is determined that the driver feels too late with respect to the timing of applying the assist torque TA, and the process proceeds to step S124. On the other hand, when the determination result is “| Ts | <| Tt1 |”, it is determined that the driver does not feel that it is too late with respect to the timing of applying the assist torque TA, and the predetermined main program is directly executed. Return.
In step S124, the forward position X at which the road curvature ρ is read is corrected far away in order to advance the timing for applying the assist torque TA. That is, a position (X + ΔX) that is far away from the front position X by a predetermined distance ΔX is corrected to a new front position X and then returned to a predetermined main program. In the subsequent calculation, the corrected road curvature ρ at the forward position X is read. In order to avoid a sudden change in the forward position X, the forward position X is changed by a predetermined allowable amount per unit time.
X ← X + ΔX
The above is the assist torque setting process.

<Action>
Next, the operation of the first embodiment will be described.
The present embodiment assumes a scene where the vehicle travels from straight traveling to curve traveling.
First, a road curvature ρ at a predetermined forward position X is read (step S116), and an assist torque TA corresponding to the road curvature ρ is set (step S117). Since the assist torque TA corresponds to the necessary torque for obtaining the necessary steering angle according to the road curvature ρ, by outputting the assist torque TA (step S118), the driver's steering torque Ts is made substantially zero. Can also achieve the required steering angle. That is, it is possible to reduce the operation burden since the vehicle can turn along the own vehicle path while only putting a hand on the steering wheel 1.

However, when the assist torque TA is applied according to the road curvature ρ, the driver feels uncomfortable if the timing of applying the assist torque TA deviates from the driver's feeling. Therefore, in this embodiment, the timing for applying the assist torque TA according to the road curvature ρ is optimized. That is, the timing of the assist torque TA is adjusted when the driver feels too early or too late with respect to the timing of applying the assist torque TA.

First, a case where the driver feels that it is too early for the application of the assist torque TA will be described.
FIG. 11 is a time chart showing the assist torque TA and the steering torque Ts when the driver feels too early.
First, when the assist torque TA in the positive direction starts to be applied, the driver does not yet want to increase the steering angle θs in the positive direction, so that the steering torque Ts is maintained in order to keep the steering against the positive assist torque TA. The direction of is generated in the negative direction. That is, the direction of the steering torque Ts is opposite to the turning direction (the determination in step S120 is “Yes”). When the steering torque Ts in the negative direction is equal to or smaller than the first threshold Te1, that is, when the absolute value of the steering torque Ts is equal to or larger than the absolute value of the first threshold Te1 (determination in step S121 is “Yes”). It is determined that the driver feels that the assist torque TA is applied too early.

In this case, in order to delay the timing for applying the assist torque TA, the forward position X for reading the road curvature ρ is corrected to a position (X−ΔX) closer to the front by ΔX (step S122). In the calculation, the road curvature ρ at the forward position X after correction is read. As a result, the assist torque TA decreases, and the steering torque Ts against the assist torque TA also decreases. When the corrected forward position X and the forward position of the driver's gaze substantially coincide, that is, when the timing of the assist torque TA substantially coincides with the driver's feeling, the steering torque Ts becomes substantially zero. Thereafter, even if the assist torque TA increases or decreases according to the road curvature ρ, the steering torque Ts remains substantially zero as long as the timing substantially matches the driver's feeling.

In this way, when the driver feels that the assist torque TA is too early, the timing when the assist torque TA is applied by correcting the forward position X for reading the road curvature ρ to the front. Can be delayed and optimized. As a result, the assist torque TA is applied almost simultaneously with the driver's steering operation, so that the vehicle can turn along the vehicle's own course while the hand is touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.
Even if the forward position X is brought closer to the front by ΔX, when the absolute value of the steering torque Ts is still equal to or larger than the absolute value of the first threshold Te1, the front position X is further brought closer to the front by ΔX. That is, every time the absolute value of the steering torque Ts becomes equal to or greater than the absolute value of the first threshold value Te1, it is corrected forward by ΔX. Therefore, since the adjustment of the front position X is continuously performed until the absolute value of the steering torque Ts becomes less than the absolute value of the first threshold Te1, the timing when the assist torque TA is applied can be optimized. .

Next, a case where the driver feels that the assist torque TA is too late will be described.
FIG. 12 is a time chart showing the assist torque TA and the steering torque Ts when the driver feels too late.
Here, the driver himself increases the steering torque Ts in the positive direction before the assist torque TA. That is, the direction of the steering torque Ts is the same as the turning direction (determination in step S120 is “No”). Then, when the steering torque Ts in the positive direction becomes equal to or greater than the first threshold value Tt1 (determination in step S123 is “Yes”), it is determined that the driver feels too late with respect to the application of the assist torque TA. .

In this case, in order to advance the timing of applying the assist torque TA, the front position X where the road curvature ρ is read is corrected to a position (X + ΔX) far away by ΔX (step S124). The road curvature ρ at the forward position X after correction is read. As a result, the assist torque TA starts to be applied and increases, so that the driver follows (trusts) the assist torque TA and the steering torque Ts decreases. When the corrected forward position X substantially coincides with the forward position of the driver's gaze, that is, when the assist torque TA timing substantially coincides with the driver's feeling, the steering torque Ts becomes substantially zero. Thereafter, even if the assist torque TA increases or decreases according to the road curvature ρ, the steering torque Ts remains substantially zero as long as the timing substantially matches the driver's feeling.

As described above, when the driver feels that the assist torque TA is too late, the timing when the assist torque TA is applied by correcting the forward position X for reading the road curvature ρ in the distance. Can be optimized early. As a result, the assist torque TA is applied almost simultaneously with the driver's steering operation, so that the vehicle can turn along the vehicle's own course while the hand is touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.
Even if the front position X is moved away by ΔX, when the absolute value of the steering torque Ts is still equal to or larger than the absolute value of the first threshold value Tt1, the front position X is further moved away by ΔX. That is, every time the absolute value of the steering torque Ts becomes equal to or larger than the absolute value of the first threshold value Tt1, the distance is corrected by ΔX in the distance. Therefore, since the adjustment of the front position X is continuously performed until the absolute value of the steering torque Ts becomes less than the absolute value of the first threshold value Tt1, the timing when the assist torque TA is applied can be optimized. .

《Application example》
In the present embodiment, the configuration applied to steering-by-wire has been described. However, the present invention is not limited to this, and may be applied to any other configuration as long as the assist torque TA can be applied to the steering mechanism. For example, the present embodiment may be applied to an electric power steering device. Further, even when the steering-by-wire configuration is used, the present invention can be applied even when electric power steering control is executed by at least one of the operation side motor 8 or the steered side motor 9 when the clutch 10 is connected in a fail-safe manner. .
In the present embodiment, the configuration in which the steering reaction force TR and the assist torque TA are added to set the final drive torque TD has been described, but the present invention is not limited to this. For example, the driver may select one of the steering reaction force TR set by the steering reaction force setting unit 23 and the assist torque TA set by the assist torque setting unit 24 by a switch operation. According to this, the driver can arbitrarily select whether to execute normal steering-by-wire control or to perform assist control that applies assist torque TA along the curve.

In the present embodiment, the front position X is changed according to the direction and magnitude of the steering torque Ts, but is not limited to this. That is, according to the direction and magnitude of the steering torque Ts, either the road curvature ρ or the assist torque TA may be directly changed so as to be the same as when the front position X is changed. According to this, the same effect as the case where the front position X is changed according to the direction and magnitude of the steering torque Ts can be obtained.
As described above, the processing in step S116 corresponds to the “curvature detection unit”, step S119 corresponds to the “torque detection unit”, and the processing in steps S117, S118, and S120 to S124 corresponds to the “assist control unit”. Further, the process of step S112 corresponds to the “vehicle speed detection unit”, and the process of step S114 corresponds to the “friction coefficient acquisition unit”.

"effect"
Next, the effect of the main part in 1st Embodiment is described.
(1) In the steering control device of the present embodiment, in order to detect the road curvature ρ in front of the own vehicle path and turn along the own vehicle path, in accordance with the road curvature ρ of the predetermined forward position X, An assist torque TA in the turning direction is applied to the steering mechanism. When the assist torque TA in the turning direction is applied to the steering mechanism, the front position X is changed according to the direction and magnitude of the steering torque Ts.
As described above, when the assist torque TA in the turning direction is applied to the steering mechanism, the front position X from which the road curvature ρ is read is changed according to the direction and magnitude of the steering torque Ts, so the assist torque TA is applied. Timing can be optimized and operational feeling can be improved.

(2) In the steering control device of the present embodiment, when shifting from straight traveling to curve traveling, the steering torque Ts is opposite to the turning direction, and the absolute value of the steering torque Ts is greater than or equal to a predetermined first threshold value Te1. When this happens, the front position X is changed to a position close to the host vehicle.
Thus, when the steering torque Ts is opposite to the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold value Te1, the driver feels that the driver is too early with respect to the timing for applying the assist torque TA. Can be judged. Therefore, by changing the front position X to a position close to the host vehicle and delaying the timing for applying the assist torque TA, the timing for applying the assist torque TA can be optimized and the operation feeling can be improved. .

(3) In the steering control device of the present embodiment, when shifting from straight traveling to curve traveling, the steering torque Ts is the same as the turning direction, and the absolute value of the steering torque Ts is greater than or equal to a predetermined first threshold value Tt1. When this happens, the front position X is changed to a position far from the host vehicle.
Thus, when the steering torque Ts is the same as the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold value Tt1, the driver feels that the driver is too late with respect to the timing for applying the assist torque TA. Can be judged. Therefore, by changing the front position X to a position far from the host vehicle and accelerating the timing for applying the assist torque TA, the timing for applying the assist torque TA can be optimized and the operation feeling can be improved. .

(4) In the steering control device of the present embodiment, the front position X is changed by a predetermined allowable amount per unit time.
Thus, when changing the front position X, a sudden change of the front position X can be suppressed by changing the unit time value by a predetermined allowable amount. Therefore, since the sudden change in the assist torque TA can be suppressed, the driver does not feel uncomfortable.
(5) In the steering control device of the present embodiment, the front position X is changed by a predetermined distance ΔX.
As described above, when the front position X is changed, the front position X is changed by the predetermined distance ΔX, so that the front position X can be prevented from being changed unnecessarily. That is, when the timing for applying the assist torque TA is delayed, the excessive response of the front position X being too close to the front or the front position X being too far away when the timing for applying the assist torque TA is advanced is suppressed. it can.

(6) In the steering control device of the present embodiment, the first threshold values Te1 and Tt1 are set to larger values as the vehicle speed V is higher.
As described above, the first threshold values Te1 and Tt1 that are optimal for the traveling scene can be set by setting the first threshold values Te1 and Tt1 to larger values as the vehicle speed V increases.
(7) In the steering control device of the present embodiment, the first threshold values Te1 and Tt1 are set to smaller values as the road surface friction coefficient μ is lower.
Thus, the first threshold values Te1 and Tt1 that are optimal for the traveling scene can be set by setting the first threshold values Te1 and Tt1 to smaller values as the road surface friction coefficient μ is lower.

(8) In the steering control device of the present embodiment, in order to detect the road curvature ρ in front of the own vehicle course and turn along the own vehicle course, in accordance with the road curvature ρ at the predetermined forward position X, An assist torque TA in the turning direction is applied to the steering mechanism. When the assist torque TA in the turning direction is applied to the steering mechanism, the road curvature ρ and the assist torque TA are set to be equal to the case where the front position X is changed according to the direction and magnitude of the steering torque Ts. Change one.
As described above, when the assist torque TA in the turning direction is applied to the steering mechanism, one of the road curvature ρ and the assist torque TA is changed according to the direction and magnitude of the steering torque Ts, so that the assist torque TA is applied. Timing can be optimized and operational feeling can be improved.

(9) In the steering control method of the present embodiment, in order to detect the road curvature ρ in front of the own vehicle path and turn along the own vehicle path, according to the road curvature ρ at the predetermined forward position X, An assist torque TA in the turning direction is applied to the steering mechanism. When the assist torque TA in the turning direction is applied to the steering mechanism, the front position X is changed according to the direction and magnitude of the steering torque Ts.
As described above, when the assist torque TA in the turning direction is applied to the steering mechanism, the front position X from which the road curvature ρ is read is changed according to the direction and magnitude of the steering torque Ts, so the assist torque TA is applied. Timing can be optimized and operational feeling can be improved.

<< Second Embodiment >>
"Constitution"
In this embodiment, when shifting from straight traveling to curve traveling, when the steering torque Ts is opposite to the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold Te1, the assist torque at that time After maintaining TA for a predetermined time Δt, the forward position X is changed to a position close to the host vehicle.
The apparatus configuration is the same as that of the first embodiment described above.
Next, the assist torque setting process will be described.
FIG. 13 is a flowchart illustrating assist torque setting processing according to the second embodiment.
Here, the process in step S122 in the first embodiment described above is changed to a process in new step S201, and the processes in other steps S111 to S121, S123, and S124 are the same as those in the first embodiment described above. Since it is the same, detailed description is omitted about a common part.

In step S201, the assist torque TA at that time is maintained for a predetermined time Δt. Thereafter, in order to delay the timing of applying the assist torque TA, the front position X at which the road curvature ρ is read is corrected to the front. That is, as shown below, a position (X−ΔX) that is closer to the front by a predetermined distance ΔX from the front position X is corrected to a new front position X and then returned to a predetermined main program. In the subsequent calculation, the corrected road curvature ρ at the forward position X is read. In order to avoid a sudden change in the forward position X, the forward position X is changed by a predetermined allowable amount per unit time.
X ← X-ΔX
The above is the assist torque setting process of the second embodiment.

<Action>
Next, the operation of the second embodiment will be described.
FIG. 14 is a time chart showing the assist torque TA and the steering torque Ts when the driver feels too early in the second embodiment.
First, when the assist torque TA in the positive direction starts to be applied, the driver does not yet want to increase the steering angle θs in the positive direction, so that the steering torque Ts is maintained in order to keep the steering against the positive assist torque TA. The direction of is generated in the negative direction. That is, the direction of the steering torque Ts is opposite to the turning direction (the determination in step S120 is “Yes”). When the steering torque Ts in the negative direction is equal to or smaller than the first threshold Te1, that is, when the absolute value of the steering torque Ts is equal to or larger than the absolute value of the first threshold Te1 (determination in step S121 is “Yes”). It is determined that the driver feels that the assist torque TA is applied too early.

In this case, the assist torque TA at that time is first maintained for Δt. Thereafter, in order to delay the timing of applying the assist torque TA, the forward position X at which the road curvature ρ is read is corrected to a position closer to the front by ΔX (X−ΔX) (step S201). The road curvature ρ at the forward position X after correction is read. As a result, at least the increase in the assist torque TA is suppressed, so that the increase in the steering torque Ts against the increase can also be suppressed. Moreover, since the assist torque TA is fixed, the increase / decrease in the assist torque TA before and after Δt is suppressed, and the influence on the operation feeling is reduced. Then, after Δt has elapsed, the assist torque TA decreases, so the steering torque Ts against it also decreases. When the corrected forward position X substantially coincides with the forward position of the driver's gaze, that is, when the assist torque TA timing substantially coincides with the driver's feeling, the steering torque Ts becomes substantially zero. Thereafter, even if the assist torque TA increases or decreases according to the road curvature ρ, the steering torque Ts remains substantially zero as long as the timing substantially matches the driver's feeling.

As described above, when the driver feels that the assist torque TA is too early, the assist torque TA at that time is first maintained for a certain time Δt, and then the forward position X from which the road curvature ρ is read is set in front. By making corrections to the above, it is possible to optimize by delaying the timing when applying the assist torque TA while suppressing the variation of the assist torque TA. As a result, the assist torque TA is applied almost simultaneously with the driver's steering operation, so that the vehicle can turn along the vehicle's own course while the hand is touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.

Even if the forward position X is brought closer to the front by ΔX, when the absolute value of the steering torque Ts is still equal to or larger than the absolute value of the first threshold Te1, the front position X is further brought closer to the front by ΔX. That is, every time the absolute value of the steering torque Ts becomes equal to or greater than the absolute value of the first threshold value Te1, it is corrected forward by ΔX. Therefore, since the adjustment of the front position X is continuously performed until the absolute value of the steering torque Ts becomes less than the absolute value of the first threshold Te1, the timing when the assist torque TA is applied can be optimized. .
Other parts common to the first embodiment described above are assumed to have the same operational effects and will not be described in detail.
As described above, the processes in steps S117, S118, S120, S121, S201, S123, and S124 correspond to the “assist control unit”.

"effect"
Next, the effect of the main part in 2nd Embodiment is described.
(1) In the steering control device of the present embodiment, when the forward position X is changed to a position close to the host vehicle, the assist torque TA at the time when the absolute value of the steering torque Ts becomes equal to or greater than the first threshold Te1 is determined in advance. After maintaining the time Δt, the front position X is changed to a position close to the host vehicle.
In this way, the assist torque TA at the time when the absolute value of the steering torque Ts becomes equal to or greater than the first threshold Te1 is maintained for a predetermined time Δt, and then the front position X is corrected forward, thereby assist torque. While suppressing increase / decrease of TA, the timing which gives it can be delayed and optimized, and operation feeling can be improved.

<< Third Embodiment >>
"Constitution"
In the present embodiment, when shifting from straight traveling to curve traveling, the absolute value of the steering torque Ts is smaller than the absolute values of the second thresholds Te2 and Tt2, which are predetermined in a range smaller than the absolute values of the first thresholds Te1 and Tt1. At this point, the forward position X is fixed.
The apparatus configuration is the same as that of the first embodiment described above.
Next, the assist torque setting process will be described.
FIG. 15 is a flowchart illustrating assist torque setting processing according to the third embodiment.
Here, the processing in steps S121 to S124 in the first embodiment described above is changed to the processing in new steps S301 to S312. The processing in other steps S111 to S120 is the same as that in the first embodiment described above. Since it is the same, detailed description is omitted about a common part.

In step S301, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold Te1. Here, when the determination result is “| Ts | ≧ | Te1 |”, it is determined that the driver feels too early with respect to the timing of applying the assist torque TA, and the process proceeds to step S302. On the other hand, when the determination result is “| Ts | <| Te1 |”, it is simply determined that the driver does not feel that it is too early with respect to the timing of applying the assist torque TA, and the process proceeds to step S304. To do.
In step S302, in order to delay the timing at which the assist torque TA is applied, the forward position X at which the road curvature ρ is read is corrected so as to be gradually closer to the front. Here, in order to avoid a sudden change in the forward position X, the amount is changed by a predetermined allowable amount per unit time, and after returning to the predetermined main program, a new forward position X is set.

In the subsequent step S303, the correction flag is set to fr = 1, and then the process returns to a predetermined main program. The correction flag fc is a flag indicating whether or not the correction is performed on the front position X. When the correction flag fc is reset to fc = 0, it indicates that the correction is not performed on the front position X. When fc = 1 is set, this indicates that correction has been performed for the forward position X. Note that fc = 0 is reset in the initial state.
In step S304, it is determined whether or not the correction flag fc is set to 1. When the determination result is “fc = 0”, it is determined that the correction for the forward position X has not been performed, and therefore the driver does not feel that the assist torque TA is too early, and the predetermined main Return to the program. On the other hand, when the determination result is “fc = 1”, it means that the correction for the forward position X has already been performed, and the driver felt that the driver torque was too early for the assist torque TA until the last time. The process proceeds to S305.

In step S305, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to a predetermined second threshold Te2 within a range smaller than the absolute value of the first threshold Te1. The second threshold value Te2 is a value that does not cause hunting even when the adjustment of the assist torque TA is stopped at that value, and is, for example, about ± 0.6 Nm. Here, when the determination result is “| Ts | ≧ | Te2 |”, it is determined that there is a possibility that the driver still feels too early with respect to the timing of applying the assist torque TA. The process proceeds to step S302. On the other hand, when the determination result is “| Ts | <| Te2 |”, it is determined that the driver no longer feels too early with respect to the timing of applying the assist torque TA, and the process proceeds to step S306.
In step S306, the correction flag is reset to fr = 0, and then the process returns to the predetermined main program.

In step S307, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold value Tt1. Here, when the determination result is “| Ts | ≧ | Tt1 |”, it is determined that the driver feels too late with respect to the timing of applying the assist torque TA, and the process proceeds to step S308. On the other hand, when the determination result is “| Ts | <| Tt1 |”, it is simply determined that the driver does not feel that it is too late with respect to the timing of applying the assist torque TA, and the process proceeds to step S310. To do.
In step S308, in order to delay the timing at which the assist torque TA is applied, the forward position X at which the road curvature ρ is read is increased and corrected so as to gradually move away. Here, in order to avoid a sudden change in the forward position X, the amount is changed by a predetermined allowable amount per unit time, and after returning to the predetermined main program, a new forward position X is set.

In the subsequent step S309, the correction flag is set to fr = 1, and then the process returns to a predetermined main program. The correction flag fc is a flag indicating whether or not the correction is performed on the front position X. When the correction flag fc is reset to fc = 0, it indicates that the correction is not performed on the front position X. When fc = 1 is set, this indicates that correction has been performed for the forward position X. Note that fc = 0 is reset in the initial state.
In step S310, it is determined whether or not the correction flag fc is set to 1. When the determination result is “fc = 0”, it is determined that the correction for the forward position X has not been performed, and therefore the driver does not feel that the assist torque TA is too late, and the predetermined main Return to the program. On the other hand, when the determination result is “fc = 1”, it means that the correction for the forward position X has already been performed, and the driver felt that the driver torque was too late for the assist torque TA until the last time. The process proceeds to S311.

In step S311, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to a predetermined second threshold value Tt2 within a range smaller than the absolute value of the first threshold value Tt1. The second threshold value Tt2 is a value that does not cause hunting even if adjustment of the assist torque TA is stopped at that value, and is, for example, about ± 0.6 Nm. Here, when the determination result is “| Ts | ≧ | Tt2 |”, it is determined that the driver may still feel that it is still too late with respect to the timing of applying the assist torque TA. The process proceeds to step S308. On the other hand, when the determination result is “| Ts | <| Tt2 |”, it is determined that the driver no longer feels too late with respect to the timing of applying the assist torque TA, and the process proceeds to step S312.
In step S312, the correction flag is reset to fr = 0, and then the process returns to a predetermined main program.
The above is the assist torque setting process of the third embodiment.

<Action>
Next, the operation of the third embodiment will be described.
First, a case where the driver feels that it is too early for the application of the assist torque TA will be described.
FIG. 16 is a time chart showing the assist torque TA and the steering torque Ts when the driver feels too early in the third embodiment.
First, when the assist torque TA in the positive direction starts to be applied, the driver does not yet want to increase the steering angle θs in the positive direction, so that the steering torque Ts is maintained in order to keep the steering against the positive assist torque TA. The direction of is generated in the negative direction. That is, the direction of the steering torque Ts is opposite to the turning direction (the determination in step S120 is “Yes”). When the steering torque Ts in the negative direction is equal to or smaller than the first threshold Te1, that is, when the absolute value of the steering torque Ts is equal to or larger than the absolute value of the first threshold Te1 (determination in Step S301 is “Yes”). It is determined that the driver feels that the assist torque TA is applied too early.

In this case, in order to delay the timing of applying the assist torque TA, the forward position X for reading the road curvature ρ is corrected to decrease so as to gradually approach the front (step S302). As a result, the assist torque TA decreases, and the steering torque Ts against the assist torque TA also decreases. At this time, if the absolute value of the steering torque Ts is merely less than the first threshold Te1 and the correction for reducing the forward position X is stopped, hunting may occur. Therefore, in the present embodiment, the reduction correction of the forward position X is executed until the absolute value of the steering torque Ts becomes less than the second threshold value Te2. Then, the steering torque Ts becomes substantially zero when the forward position X after the decrease correction substantially coincides with the forward position at which the driver gazes, that is, when the timing of the assist torque TA and the driver's feeling substantially coincide. Thereafter, even if the assist torque TA increases or decreases according to the road curvature ρ, the steering torque Ts remains substantially zero as long as the timing substantially matches the driver's feeling.

In this way, when the driver feels that the assist torque TA is too early, the timing when the assist torque TA is applied by correcting the forward position X for reading the road curvature ρ to the front. Can be delayed and optimized. As a result, the assist torque TA is applied almost simultaneously with the driver's steering operation, so that the vehicle can turn along the vehicle's own course while the hand is touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.
Further, the front position X is gradually corrected toward the front until the absolute value of the steering torque Ts becomes less than the absolute value of the second threshold value Te2. Thereby, the timing at the time of providing the assist torque TA can be optimized while suppressing hunting.

Next, a case where the driver feels that the assist torque TA is too late will be described.
FIG. 17 is a time chart showing the assist torque TA and the steering torque Ts when the driver feels too late in the third embodiment.
Here, the driver himself increases the steering torque Ts in the positive direction before the assist torque TA. That is, the direction of the steering torque Ts is the same as the turning direction (determination in step S120 is “No”). Then, when the steering torque Ts in the positive direction becomes equal to or greater than the first threshold value Tt1 (the determination in step S307 is “Yes”), it is determined that the driver feels too late with respect to the application of the assist torque TA. .

In this case, in order to advance the timing of applying the assist torque TA, the forward position X at which the road curvature ρ is read is increased and corrected so as to gradually move away (step S308). As a result, the assist torque TA starts to be applied and increases, so that the driver follows (trusts) the assist torque TA and the steering torque Ts decreases. At this time, if the absolute value of the steering torque Ts is merely less than the first threshold value Tt1 and the increase correction of the front position X is stopped, hunting may occur. Therefore, in this embodiment, the increase correction of the forward position X is executed until the absolute value of the steering torque Ts becomes less than the second threshold value Tt2. When the corrected forward position X substantially coincides with the forward position of the driver's gaze, that is, when the assist torque TA timing substantially coincides with the driver's feeling, the steering torque Ts becomes substantially zero. Thereafter, even if the assist torque TA increases or decreases according to the road curvature ρ, the steering torque Ts remains substantially zero as long as the timing substantially matches the driver's feeling.

As described above, when the driver feels that the assist torque TA is too late, the timing when the assist torque TA is applied by correcting the forward position X for reading the road curvature ρ in the distance. Can be optimized early. As a result, the assist torque TA is applied almost simultaneously with the driver's steering operation, so that the vehicle can turn along the vehicle's own course while the hand is touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.
Further, the forward position X is gradually corrected toward the front until the absolute value of the steering torque Ts becomes less than the absolute value of the second threshold value Tt2. Thereby, the timing at the time of providing the assist torque TA can be optimized while suppressing hunting.
Other parts common to the first embodiment described above are assumed to have the same operational effects and will not be described in detail.
As described above, the processes in steps S117, S118, S120, and S301 to S312 correspond to the “assist control unit”.

"effect"
Next, the effect of the main part in 3rd Embodiment is described.
(1) In the steering control device of the present embodiment, when the absolute value of the steering torque Ts becomes less than the predetermined second threshold values Te2 and Tt2 in a range smaller than the first threshold values Te1 and Tt1, the forward position X Is fixed.
Thus, the assist torque TA is reduced while suppressing the hunting by gradually correcting the front position X until the absolute value of the steering torque Ts becomes less than the absolute values of the second threshold values Te2 and Tt2. The timing at the time of grant can be optimized.

<< 4th Embodiment >>
"Constitution"
In this embodiment, when shifting from straight traveling to curve traveling, when the steering torque Ts is opposite to the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold Te1, the absolute value of the steering torque Ts. The assist torque TA when the absolute value of the steering torque Ts becomes equal to or greater than the absolute value of the first threshold value Te1 is maintained until the absolute value of the steering torque Ts becomes equal to or greater than the absolute value of the first threshold value Te1 in a range smaller than the first threshold value Te1. To do.
The apparatus configuration is the same as that of the first embodiment described above.
Next, the assist torque setting process will be described.
FIG. 18 is a flowchart illustrating assist torque setting processing according to the fourth embodiment.
Here, the process in step S302 in the third embodiment described above is changed to a process in new step S401, and the processes in other steps S111 to S120, S301, and S303 to S312 are described in the third embodiment described above. Since the configuration is the same as that of the embodiment, detailed description of common portions is omitted.
In step S401, thereafter, the assist torque TA at the time when the absolute value of the steering torque Ts becomes equal to or greater than the first threshold Te1 is maintained.
The above is the assist torque setting process of the fourth embodiment.

<Action>
Next, the operation of the fourth embodiment will be described.
FIG. 19 is a time chart showing the assist torque TA and the steering torque Ts when the driver feels too early in the fourth embodiment.
First, when the assist torque TA in the positive direction starts to be applied, the driver does not yet want to increase the steering angle θs in the positive direction, so that the steering torque Ts is maintained in order to keep the steering against the positive assist torque TA. The direction of is generated in the negative direction. That is, the direction of the steering torque Ts is opposite to the turning direction (the determination in step S120 is “Yes”). When the steering torque Ts in the negative direction is equal to or smaller than the first threshold Te1, that is, when the absolute value of the steering torque Ts is equal to or larger than the absolute value of the first threshold Te1 (determination in Step S301 is “Yes”). It is determined that the driver feels that the assist torque TA is applied too early.

In this case, the assist torque TA at that time is maintained. As a result, at least the increase in the assist torque TA is suppressed, so that the increase in the steering torque Ts can be suppressed. Moreover, since the assist torque TA is fixed, the increase / decrease in the assist torque TA before and after Δt is suppressed, and the influence on the operation feeling is reduced. The assist torque TA is maintained until the absolute value of the steering torque Ts becomes less than the second threshold value Te2.
When the vehicle moves forward and reaches a point that matches the currently maintained assist torque TA, the timing of the assist torque TA substantially matches the driver's feeling, and the steering torque Ts is substantially zero. It becomes. Thereafter, the forward position X at the time when the absolute value of the steering torque Ts becomes less than the second threshold Te2 is used. Even if the assist torque TA increases or decreases, the steering torque Ts is maintained in a substantially zero state as long as the timing substantially matches the driver's feeling.

As described above, when the driver feels that the assist torque TA is too early, by maintaining the assist torque TA at that time, the assist torque TA is applied while suppressing the variation of the assist torque TA. Can be optimized by delaying the timing. As a result, the assist torque TA is applied almost simultaneously with the driver's steering operation, so that the vehicle can turn along the vehicle's own course while the hand is touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.
Further, the front position X is gradually corrected toward the front until the absolute value of the steering torque Ts becomes less than the absolute value of the second threshold value Te2. Thereby, the timing at the time of providing the assist torque TA can be optimized while suppressing hunting.
Other parts common to the above-described third embodiment are assumed to have the same operational effects and will not be described in detail.
As described above, the processes in steps S117, S118, S120, S301, S401, and S303 to S312 correspond to the “assist control unit”.

"effect"
Next, the effect of the principal part in 4th Embodiment is described.
(1) In the steering control device of the present embodiment, when the forward position X is changed to a position close to the host vehicle, the assist torque TA at the time when the absolute value of the steering torque Ts becomes equal to or greater than the first threshold Te1 is maintained.
In this way, by maintaining the assist torque TA at the time when the absolute value of the steering torque Ts becomes equal to or greater than the first threshold Te1, the timing of applying the torque is optimized while suppressing increase / decrease in the assist torque TA. , The operational feeling can be improved.

<< 5th Embodiment >>
"Constitution"
The present embodiment shows a case where the vehicle travels from curve traveling to straight traveling.
The apparatus configuration is the same as that of the first embodiment described above.
Next, the assist torque setting process will be described.
FIG. 20 is a flowchart illustrating assist torque setting processing according to the fifth embodiment.
Here, the processing in steps S120 to S124 in the first embodiment described above is changed to new processing in steps S501 to S505, and the processing in other steps S111 to S119 is the same as that in the first embodiment described above. Since it is the same, detailed description is omitted about a common part.
In step S501, the signs of the steering torque Ts and the road curvature ρ are determined, and it is determined whether the direction of the steering torque Ts and the direction of the road curvature ρ are the same direction. Here, when the steering torque Ts and the road curvature ρ are in the same direction, it is determined that the application of the assist torque TA is earlier than the driver's steering operation, and the process proceeds to step S502. On the other hand, when the steering torque Ts and the road curvature ρ are in the opposite directions, it is determined that the application of the assist torque TA is later than the steering operation by the driver, and the process proceeds to step S504.

In step S502, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold Te1. Here, when the determination result is “| Ts | ≧ | Te1 |”, it is determined that the driver feels too early with respect to the timing of applying the assist torque TA, and the process proceeds to step S503. On the other hand, when the determination result is “| Ts | <| Te1 |”, it is determined that the driver does not feel that it is too early with respect to the timing of applying the assist torque TA, and the predetermined main program is directly executed. Return.
In step S503, in order to delay the timing for applying the assist torque TA, the front position X at which the road curvature ρ is read is corrected to the front. That is, as shown below, a position (X−ΔX) that is closer to the front by a predetermined distance ΔX from the front position X is corrected to a new front position X and then returned to a predetermined main program. In the subsequent calculation, the corrected road curvature ρ at the forward position X is read. In order to avoid a sudden change in the forward position X, the forward position X is changed by a predetermined allowable amount per unit time.
X ← X-ΔX

In step S504, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold value Tt1 described above. Here, when the determination result is “| Ts | ≧ | Tt1 |”, it is determined that the driver feels too late with respect to the timing of applying the assist torque TA, and the process proceeds to step S505. On the other hand, when the determination result is “| Ts | <| Tt1 |”, it is determined that the driver does not feel that it is too late with respect to the timing of applying the assist torque TA, and the predetermined main program is directly executed. Return.
In step S505, the forward position X at which the road curvature ρ is read is corrected far away in order to advance the timing for applying the assist torque TA. That is, a position (X + ΔX) that is far away from the front position X by a predetermined distance ΔX is corrected to a new front position X and then returned to a predetermined main program. In the subsequent calculation, the corrected road curvature ρ at the forward position X is read. In order to avoid a sudden change in the forward position X, the forward position X is changed by a predetermined allowable amount per unit time.
X ← X + ΔX
The above is the assist torque setting process of the fifth embodiment.

<Action>
Next, the operation of the fifth embodiment will be described.
The present embodiment assumes a scene in which the vehicle returns from curve traveling to straight traveling.
Here, the relationship between the assist torque TA and the steering torque Ts regarding the setting of the first thresholds Te1 and Tt1 will be described.
FIG. 21 is a graph showing the relationship between the steering angle θs and the steering torque Ts in the fifth embodiment.
The relationship between the steering angle θs and the steering torque Ts is expressed by coordinates with the steering angle θs as the horizontal axis and the steering torque Ts as the vertical axis, with the right turn being a positive value and the left turn being a negative value.
Here, the state in which the steering wheel 1 is turned off is the initial steering angle, and the steering angle θs = 0 is the required steering angle.
First, the characteristic line Ls shows the relationship between the steering angle θs and the steering torque Ts when the positive assist torque TA is applied and the driver's steering operation is performed substantially simultaneously. In this characteristic line Ls, the driver performs the steering operation by himself in hopes of decreasing the steering angle θs, but the assist torque TA is released almost simultaneously with it, so the steering torque Ts becomes substantially 0 and the steering angle θs decreases as it is. The required steering angle is achieved. Thus, when the decrease in the assist torque TA is made substantially simultaneously with the driver's steering operation, the steering torque Ts becomes substantially zero.

On the other hand, the relationship between the steering angle θs and the steering torque Ts when the driver feels too early with respect to the decrease in the assist torque TA is indicated by a characteristic line Le. In this characteristic line Le, when the assist torque TA in the positive direction starts to decrease, the driver does not yet want to decrease the steering angle θs. Therefore, the steering torque is maintained to resist the decrease in the assist torque TA. The direction of Ts occurs in the positive direction. However, when the vehicle further moves forward, the driver wants to decrease the steering angle θs, so this time, the steering torque Ts is relaxed and the assist torque TA is decreased (subjected). Accordingly, the steering torque Ts in the positive direction decreases along the characteristic line Ln and eventually becomes 0, and at this time, the necessary steering angle is achieved.
As described above, when the driver feels that the assist torque TA decreases too quickly, the direction of the steering torque Ts is the same as the turning direction. Therefore, in the present embodiment, when the direction of the steering torque Ts is the same as the turning direction (the determination in step S501 is “Yes”), and the absolute value of the steering torque Ts is greater than or equal to the first threshold Te1 (in step S502) If the determination is “Yes”), it is determined that the driver feels that the assist torque TA is decreased too early.

In this case, in order to delay the timing of decreasing the assist torque TA, the front position X for reading the road curvature ρ is corrected to a position (X−ΔX) that is closer to the front by ΔX (step S503), In the calculation, the road curvature ρ at the forward position X after correction is read. Thereby, since the reduction | decrease of assist torque TA is suppressed, the steering torque Ts resisting it also reduces. When the corrected forward position X substantially coincides with the forward position of the driver's gazing, that is, when the decrease timing of the assist torque TA substantially coincides with the driver's feeling, the steering torque Ts becomes substantially zero. Thereafter, even if the assist torque TA increases or decreases according to the road curvature ρ, the steering torque Ts remains substantially zero as long as the timing substantially matches the driver's feeling.

As described above, when the driver feels that the assist torque TA is decreased too early, when the assist torque TA is decreased by correcting the front position X at which the road curvature ρ is read to the front, the driver torque TA is decreased. Can be optimized by delaying the timing. As a result, the assist torque TA is decreased substantially simultaneously with the driver's steering operation, so that the vehicle can turn along the own vehicle path with the hand just touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.
Even if the forward position X is brought closer to the front by ΔX, when the absolute value of the steering torque Ts is still equal to or larger than the absolute value of the first threshold Te1, the front position X is further brought closer to the front by ΔX. That is, every time the absolute value of the steering torque Ts becomes equal to or greater than the absolute value of the first threshold value Te1, it is corrected forward by ΔX. Therefore, since the adjustment of the front position X is continuously performed until the absolute value of the steering torque Ts becomes less than the absolute value of the first threshold Te1, it is possible to optimize the decrease timing of the assist torque TA.

Next, the relationship between the steering angle θs and the steering torque Ts when the driver feels that the assist torque TA is too slow is indicated by a characteristic line Lt. In this characteristic line Lt, the driver desires to decrease the steering angle θs prior to the assist torque TA, so the driver himself decreases the steering torque Ts in the negative direction. At this time, the steering torque Ts decreases in the negative direction along the characteristic line La. However, as the vehicle further moves forward, the assist torque TA starts to decrease, so this time, the steering torque Ts in the negative direction is relaxed and the decrease in the assist torque TA is followed (or left). Thus, the steering torque Ts in the negative direction eventually becomes 0 so as to increase, and at this time, the necessary steering angle is achieved.
Thus, when the driver feels that the decrease in the assist torque TA is too slow, the direction of the steering torque Ts is opposite to the turning direction. Therefore, in the present embodiment, when the direction of the steering torque Ts is opposite to the turning direction (the determination in step S501 is “No”) and the absolute value of the steering torque Ts is equal to or greater than the first threshold value Tt1 (in step S504). If the determination is “Yes”), it is determined that the driver feels that the assist torque TA is decreased too late.

In this case, in order to speed up the timing of decreasing the assist torque TA, the forward position X at which the road curvature ρ is read is corrected to a position (X + ΔX) farther away by ΔX (step S505). The road curvature ρ at the forward position X after correction is read. As a result, the assist torque TA starts to decrease, so that the driver follows (trusts) the decrease in the assist torque TA, and the steering torque Ts decreases. When the corrected forward position X substantially coincides with the forward position of the driver's gazing, that is, when the decrease timing of the assist torque TA substantially coincides with the driver's feeling, the steering torque Ts becomes substantially zero. Thereafter, even if the assist torque TA increases or decreases according to the road curvature ρ, the steering torque Ts remains substantially zero as long as the timing substantially matches the driver's feeling.

As described above, when the driver feels that the assist torque TA is decreased too slowly, the forward position X for reading the road curvature ρ is corrected to a far distance so that the decrease timing of the assist torque TA is adjusted. It can be optimized early. As a result, the assist torque TA is decreased substantially simultaneously with the driver's steering operation, so that the vehicle can turn along the own vehicle path with the hand just touching the steering wheel 1. Therefore, the operation burden can be reduced and the operation feeling can be improved.

Even if the front position X is moved away by ΔX, when the absolute value of the steering torque Ts is still equal to or larger than the absolute value of the first threshold value Tt1, the front position X is further moved away by ΔX. That is, every time the absolute value of the steering torque Ts becomes equal to or larger than the absolute value of the first threshold value Tt1, the distance is corrected by ΔX in the distance. Therefore, since the adjustment of the front position X is continuously performed until the absolute value of the steering torque Ts becomes less than the absolute value of the first threshold value Tt1, the timing when the assist torque TA is applied can be optimized. .
Other parts common to the first embodiment described above are assumed to have the same operational effects and will not be described in detail.
The processes in steps S117, S118, and S501 to S505 correspond to the “assist control unit”.

"effect"
Next, the effect of the principal part in 5th Embodiment is described.
(1) In the steering control device of the present embodiment, when the vehicle travels from the curve traveling to the straight traveling, the steering torque Ts is the same as the turning direction, and the absolute value of the steering torque Ts is equal to or greater than a predetermined first threshold Te1. When this happens, the front position X is changed to a position close to the host vehicle.
Thus, when the steering torque Ts is the same as the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold value Te1, the driver feels that the driver torque is too early with respect to the decrease timing of the assist torque TA. Can be judged. Therefore, by changing the forward position X to a position close to the host vehicle and delaying the timing for decreasing the assist torque TA, the timing for decreasing the assist torque TA can be optimized and the operation feeling can be improved.

(2) In the steering control device of the present embodiment, when the vehicle travels from the curve traveling to the straight traveling, the steering torque Ts is opposite to the turning direction, and the absolute value of the steering torque Ts is equal to or greater than a predetermined first threshold value Tt1. When this happens, the front position X is changed to a position far from the host vehicle.
As described above, when the steering torque Ts is opposite to the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold value Tt1, the driver feels that the driver is too late with respect to the timing of decreasing the assist torque TA. Can be judged. Therefore, by changing the front position X to a position far from the host vehicle and accelerating the timing at which the assist torque TA is decreased, the timing at which the assist torque TA is decreased can be optimized and the operation feeling can be improved.

<< 6th Embodiment >>
"Constitution"
In the present embodiment, when the vehicle travels from the curve travel to the straight travel, when the steering torque Ts is the same as the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold Te1, the assist torque at that time After maintaining TA for a predetermined time Δt, the forward position X is changed to a position close to the host vehicle.
The apparatus configuration is the same as that of the first embodiment described above.
Next, the assist torque setting process will be described.
FIG. 22 is a flowchart illustrating assist torque setting processing according to the sixth embodiment.
Here, the process in step S503 in the fifth embodiment described above is changed to a process in new step S601. The processes in other steps S111 to S119, S501, S502, S504, and S505 are described above. Since it is the same as that of 5 embodiment, detailed description is abbreviate | omitted about a common part.

In step S601, the assist torque TA at that time is maintained for a predetermined time Δt. Thereafter, in order to delay the timing of decreasing the assist torque TA, the front position X at which the road curvature ρ is read is corrected to the front. That is, as shown below, a position (X−ΔX) that is closer to the front by a predetermined distance ΔX from the front position X is corrected to a new front position X and then returned to a predetermined main program. In the subsequent calculation, the corrected road curvature ρ at the forward position X is read. In order to avoid a sudden change in the forward position X, the forward position X is changed by a predetermined allowable amount per unit time.
X ← X-ΔX
The above is the assist torque setting process of the sixth embodiment.

In the sixth embodiment, as in the second embodiment described above, the assist torque TA at the time when the absolute value of the steering torque Ts becomes equal to or greater than the first threshold Te1 is maintained for a predetermined time Δt, and then the front position X By correcting the shift toward the front, it is possible to optimize by delaying the timing to decrease the assist torque TA while suppressing increase / decrease in the assist torque TA, thereby improving the operational feeling.
Other parts common to the fifth embodiment described above are assumed to have the same operational effects, and detailed description thereof is omitted.

<< 7th Embodiment >>
"Constitution"
In the present embodiment, when the vehicle travels from the curve travel to the straight travel, the absolute value of the steering torque Ts is less than the absolute values of the second thresholds Te2 and Tt2, which are set in advance in a range smaller than the absolute values of the first thresholds Te1 and Tt1 At this point, the forward position X is fixed.
The apparatus configuration is the same as that of the first embodiment described above.
Next, the assist torque setting process will be described.
FIG. 23 is a flowchart illustrating assist torque setting processing according to the seventh embodiment.
Here, the processes in steps S502 to S505 in the fifth embodiment described above are changed to the processes in new steps S701 to S712, and the processes in other steps S111 to S119 and S501 are described in the fifth embodiment described above. Since the configuration is the same as that of the embodiment, detailed description of common portions is omitted.

In step S701, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold Te1. Here, when the determination result is “| Ts | ≧ | Te1 |”, it is determined that the driver feels too early with respect to the timing of decreasing the assist torque TA, and the process proceeds to step S702. On the other hand, when the determination result is “| Ts | <| Te1 |”, it is simply determined that the driver does not feel that it is too early with respect to the timing to decrease the assist torque TA, and the process proceeds to step S704. To do.
In step S702, in order to delay the timing at which the assist torque TA is decreased, the forward position X at which the road curvature ρ is read is corrected so as to be gradually closer to the front. Here, in order to avoid a sudden change in the forward position X, the amount is changed by a predetermined allowable amount per unit time, and after returning to the predetermined main program, a new forward position X is set.

In the subsequent step S703, the correction flag is set to fr = 1, and then the process returns to a predetermined main program. The correction flag fc is a flag indicating whether or not the correction is performed on the front position X. When the correction flag fc is reset to fc = 0, it indicates that the correction is not performed on the front position X. When fc = 1 is set, this indicates that correction has been performed for the forward position X. Note that fc = 0 is reset in the initial state.
In step S704, it is determined whether or not the correction flag fc is set to 1. When the determination result is “fc = 0”, it is determined that the correction for the forward position X has not been performed, and therefore the driver does not feel that the assist torque TA is too early, and the predetermined main Return to the program. On the other hand, when the determination result is “fc = 1”, it means that the correction for the forward position X has already been performed, and the driver felt that the driver torque was too early for the assist torque TA until the last time. The process proceeds to S705.

In step S705, it is determined whether or not the absolute value of the steering torque Ts is equal to or greater than a predetermined second threshold Te2 within a range smaller than the absolute value of the first threshold Te1. The second threshold value Te2 is a value that does not cause hunting even when the adjustment of the assist torque TA is stopped at that value, and is, for example, about ± 0.6 Nm. Here, when the determination result is “| Ts | ≧ | Te2 |”, it is determined that there is a possibility that the driver still feels too early with respect to the timing at which the assist torque TA is decreased. The process proceeds to step S702. On the other hand, when the determination result is “| Ts | <| Te2 |”, it is determined that the driver no longer feels too early with respect to the timing for decreasing the assist torque TA, and the process proceeds to step S706.

In step S706, the correction flag is reset to fr = 0, and then the process returns to a predetermined main program.
In step S707, it is determined whether or not the absolute value of the steering torque Ts is greater than or equal to the absolute value of the first threshold value Tt1. Here, when the determination result is “| Ts | ≧ | Tt1 |”, it is determined that the driver feels too late with respect to the timing of decreasing the assist torque TA, and the process proceeds to step S708. On the other hand, when the determination result is “| Ts | <| Tt1 |”, it is simply determined that the driver does not feel that it is too late with respect to the timing at which the assist torque TA is decreased, and the process proceeds to step S710. To do.

In step S708, in order to delay the timing at which the assist torque TA is decreased, the forward position X at which the road curvature ρ is read is corrected to increase gradually so that it is farther away. Here, in order to avoid a sudden change in the forward position X, the amount is changed by a predetermined allowable amount per unit time, and after returning to the predetermined main program, a new forward position X is set.
In the subsequent step S709, the correction flag is set to fr = 1, and then the process returns to the predetermined main program. The correction flag fc is a flag indicating whether or not the correction is performed on the front position X. When the correction flag fc is reset to fc = 0, it indicates that the correction is not performed on the front position X. When fc = 1 is set, this indicates that correction has been performed for the forward position X. Note that fc = 0 is reset in the initial state.

In step S710, it is determined whether the correction flag fc is set to 1. When the determination result is “fc = 0”, it is determined that the correction for the forward position X has not been performed, and therefore the driver does not feel that the assist torque TA is too late, and the predetermined main Return to the program. On the other hand, when the determination result is “fc = 1”, it means that the correction for the forward position X has already been performed, and the driver felt that the driver torque was too late for the assist torque TA until the last time. The process proceeds to S711.

In step S711, it is determined whether or not the absolute value of the steering torque Ts is equal to or greater than a second threshold value Tt2 that is predetermined within a range smaller than the absolute value of the first threshold value Tt1. The second threshold value Tt2 is a value that does not cause hunting even if adjustment of the assist torque TA is stopped at that value, and is, for example, about ± 0.6 Nm. Here, when the determination result is “| Ts | ≧ | Tt2 |”, it is determined that there is a possibility that the driver still feels too late with respect to the timing at which the assist torque TA is decreased. The process proceeds to step S708. On the other hand, when the determination result is “| Ts | <| Tt2 |”, it is determined that the driver no longer feels too late with respect to the timing of decreasing the assist torque TA, and the process proceeds to step S712.

In step S712, the correction flag is reset to fr = 0, and then the process returns to the predetermined main program.
The above is the assist torque setting process of the seventh embodiment.
In the seventh embodiment, as in the third embodiment described above, the forward position X is gradually corrected toward the front until the absolute value of the steering torque Ts becomes less than the absolute values of the second threshold values Te2 and Tt2. Thus, it is possible to optimize the timing for reducing the assist torque TA while suppressing hunting.
Other parts common to the fifth embodiment described above are assumed to have the same operational effects, and detailed description thereof is omitted.

<< Eighth Embodiment >>
"Constitution"
In this embodiment, when the vehicle travels from the curve travel to the straight travel, when the steering torque Ts is the same as the turning direction and the absolute value of the steering torque Ts is equal to or greater than the first threshold Te1, the absolute value of the steering torque Ts. The assist torque TA when the absolute value of the steering torque Ts becomes equal to or greater than the absolute value of the first threshold value Te1 is maintained until the absolute value of the steering torque Ts becomes equal to or greater than the absolute value of the first threshold value Te1 in a range smaller than the first threshold value Te1. To do.
The apparatus configuration is the same as that of the first embodiment described above.

Next, the assist torque setting process will be described.
FIG. 24 is a flowchart illustrating assist torque setting processing according to the eighth embodiment.
Here, the process of step S702 in the seventh embodiment described above is changed to a new process of step S801, and the processes of other steps S111 to S119, S501, S701, and S703 to S712 are described above. Since it is the same as that of 7 embodiment, detailed description is abbreviate | omitted about a common part.
In step S801, thereafter, the assist torque TA at the time when the absolute value of the steering torque Ts becomes equal to or greater than the first threshold Te1 is maintained.
The above is the assist torque setting process of the eighth embodiment.

In the eighth embodiment, similarly to the fourth embodiment described above, by maintaining the assist torque TA at the time when the absolute value of the steering torque Ts is equal to or greater than the first threshold Te1, the increase or decrease in the assist torque TA is suppressed. However, it is possible to improve the operation feeling by optimizing by delaying the timing to reduce it.
Other parts common to the above-described seventh embodiment can obtain the same operation effects, and detailed description thereof will be omitted.
The entire contents of the Japanese patent application P2012-276887 (filed on Dec. 19, 2012) to which the present application claims priority are incorporated herein by reference.
Although the present invention has been described with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of the embodiments based on the above disclosure will be apparent to those skilled in the art.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3L, 3R Steering wheel 4 Knuckle arm 5 Tie rod 6 Rack and pinion 7 Pinion shaft 8 Operation side motor 9 Steering side motor 10 Clutch 11 Steering angle sensor 12 Steering angle sensor 13 Hub sensor 14 Vehicle speed sensor 15 Yaw rate Sensor 20 Controller 21 Steering side motor control unit 22 Operation side motor control unit 23 Steering reaction force setting unit 24 Assist torque setting unit 25 Switching unit 26 Drive control unit 31 Torque sensor 32 Lateral acceleration sensor 33 Front camera 34 Navigation system 35 Radar device

Claims (15)

1. A curvature detection unit for detecting a road curvature ahead of the own vehicle path;
   An assist control unit that applies an assist torque in a turning direction to the steering mechanism according to a road curvature at a predetermined forward position among road curvatures detected by the curvature detection unit in order to make a turn along the own vehicle path. When,
   A torque detector for detecting the steering torque of the driver,
   The assist control unit
   A steering control device, wherein when controlling assist torque in a turning direction, the front position is changed according to the direction and magnitude of steering torque detected by the torque detector.
2. The assist control unit
   When shifting from straight traveling to curve traveling, when the direction of the steering torque detected by the torque detector is opposite to the turning direction and the absolute value of the steering torque is equal to or greater than a predetermined first threshold, The steering control device according to claim 1, wherein the front position is changed to a position close to the host vehicle.
3. The assist control unit
   When shifting from straight traveling to curve traveling, when the direction of the steering torque detected by the torque detection unit is the same as the turning direction and the absolute value of the steering torque is equal to or greater than a predetermined first threshold, The steering control device according to claim 1 or 2, wherein the front position is changed to a position far from the host vehicle.
4. The assist control unit
   When transitioning from curve traveling to straight traveling, when the direction of the steering torque detected by the torque detection unit is the same as the turning direction and the absolute value of the steering torque is equal to or greater than a predetermined first threshold, The steering control device according to any one of claims 1 to 3, wherein the front position is changed to a position close to the host vehicle.
5. The assist control unit
   When transitioning from curve traveling to straight traveling, when the direction of the steering torque detected by the torque detector is opposite to the turning direction and the absolute value of the steering torque is equal to or greater than a predetermined first threshold, The steering control device according to any one of claims 1 to 4, wherein the front position is changed to a position far from the host vehicle.
6. The assist control unit
   The steering control device according to any one of claims 1 to 5, wherein the front position is changed by a predetermined allowable amount per unit time.
7. The assist control unit
   The steering control device according to claim 6, wherein the front position is changed by a predetermined distance.
8. The assist control unit
   When the front position is changed to a position close to the host vehicle, the assist torque at the time when the absolute value of the steering torque detected by the torque detection unit becomes equal to or greater than the first threshold is maintained for a predetermined time. The steering control device according to any one of claims 2 to 7, wherein the forward position is changed to a position close to the host vehicle.
9. The assist control unit
   The front position is fixed when the absolute value of the steering torque detected by the torque detector becomes less than a predetermined second threshold within a range smaller than the first threshold. The steering control device according to any one of claims 6 to 8.
10. The assist control unit
    When shifting from straight traveling to curve traveling, when the direction of the steering torque detected by the torque detector is opposite to the turning direction and the absolute value of the steering torque is equal to or greater than a predetermined first threshold, Maintaining the assist torque when the absolute value of the steering torque is equal to or greater than the first threshold until the steering torque is less than a predetermined second threshold within a range smaller than the first threshold. The steering control device according to claim 1, wherein
11. The assist control unit
    When transitioning from curve traveling to straight traveling, when the direction of the steering torque detected by the torque detection unit is the same as the turning direction and the absolute value of the steering torque is equal to or greater than a predetermined first threshold, Maintaining the assist torque when the absolute value of the steering torque becomes equal to or greater than the first threshold until the steering torque is less than a predetermined second threshold within a range smaller than the first threshold. The steering control device according to claim 1 or 2, characterized in that
12. It has a vehicle speed detector that detects the vehicle speed,
    The assist control unit
    The steering control device according to any one of claims 1 to 11, wherein the first threshold value is set to a larger value as the vehicle speed detected by the vehicle speed detection unit is higher.
13. A friction coefficient acquisition unit for acquiring a road surface friction coefficient is provided,
    The assist control unit
    The steering control device according to any one of claims 1 to 12, wherein the first threshold value is set to a smaller value as the road surface friction coefficient acquired by the friction coefficient acquisition unit is lower.
14. A curvature detection unit for detecting a road curvature ahead of the own vehicle path;
    An assist control unit that applies an assist torque in a turning direction to the steering mechanism according to a road curvature at a predetermined forward position among road curvatures detected by the curvature detection unit in order to make a turn along the own vehicle path. When,
    A torque detector for detecting the steering torque of the driver,
    The assist control unit
    When controlling the assist torque in the turning direction, the road curvature and the assist torque are set to be the same as when the front position is changed according to the direction and magnitude of the steering torque detected by the torque detector. A steering control device characterized by changing one side.
15. Detects the road curvature ahead of the vehicle
    In order to make a turn along the own vehicle path, an assist torque in the turning direction is applied to the steering mechanism in accordance with a road curvature at a predetermined forward position.
    Detects the steering torque of the driver,
    A steering control method, wherein when the assist torque in the turning direction is controlled, the front position is changed according to the direction and magnitude of the steering torque.

Images