JP4862414B2 - Vehicle steering control device - Google Patents

Description

  The present invention belongs to a technical field of a steering control device for a vehicle by a steer-by-wire system including a backup clutch that mechanically connects and disconnects an operation unit operated by a driver and a steering unit that steers a steered wheel.

Conventionally, a so-called steer-by-wire (SBW) system in which a steering wheel and a steering mechanism for a front wheel are mechanically separated includes a backup clutch as backup means for mechanically connecting the steering wheel and the steering mechanism. When an abnormality occurs in a part of the SBW system, the backup clutch is quickly connected, SBW control is stopped, and the control is switched to assist control that reduces the driver's steering burden (see, for example, Patent Document 1). .
JP 2002-225733 A

  However, in the above prior art, when the backup clutch is erroneously engaged (not intentionally engaged), SBW control is continued on the steered side. In addition, when SBW control is performed such that the steering gear ratio of the command turning angle with respect to the steering angle is smaller than the steering gear ratio when mechanically coupled (when the vehicle speed is high, steering is started, etc.) ), The ratio of the steering angle to the actual turning angle (ratio determined by mechanical coupling) when erroneously fastening is determined by the ratio of the commanded turning angle to the steering angle in SBW control. Since the steered motor is driven so as to return to the steered angle, in the state where the backup clutch is erroneously engaged, a force that is increased from that angle and counters the switchback is applied. That is, it may be difficult to operate the handle from this position.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to determine the erroneous engagement of the backup clutch in a short time during the steer-by-wire control, thereby causing the erroneous engagement of the backup clutch. An object of the present invention is to provide a vehicle steering control device that can perform a smooth steering operation.

In order to achieve the above-described object, in the vehicle steering control device of the present invention,
An operation unit operated by the driver;
A steering part that is mechanically separated from the operation part and steers the steering wheel;
A steering reaction force actuator for applying a steering reaction force to the operation unit;
A steering actuator for applying a steering force to the steering unit;
A backup clutch that mechanically connects and disconnects the operation unit and the steering unit;
The operation unit and the steered unit are separated by releasing the backup clutch, and a control command for driving the steered actuator to output a steered angle according to an operation state of the operating unit is output, and the steered Steer-by-wire control means for outputting a control command for driving the steering reaction force actuator so as to apply a steering reaction force according to the steering state of the unit;
During steer-by-wire control, when the drive direction of the steered portion is opposite to the operation direction of the operation portion, clutch engagement determining means for determining that the backup clutch has been engaged,
It is provided with.

In the vehicle steering control device of the present invention, in the steer-by-wire control means, the operation unit and the steered unit are separated by releasing the backup clutch so that the steered angle according to the operation state of the operating unit is obtained. A control command for driving the steering actuator is output, and a control command for driving the steering reaction force actuator to output a steering reaction force according to the steering state of the steering unit is output. During this steer-by-wire control, in the clutch engagement determination means, when the drive direction of the steered portion is opposite to the operation direction of the operation portion, it is determined that the backup clutch has been engaged.
That is, during steer-by-wire control, the steering gear ratio of the command turning angle with respect to the steering angle may be made smaller than the steering gear ratio when mechanically coupled, such as when the vehicle speed is high or steering is started. When the backup clutch is in the released state, the change direction of the operation and the drive direction of the steering actuator are the same direction. That is, if the change direction of the operation and the driving direction of the steering actuator are opposite, an abnormality has occurred in the backup clutch related to both steering / steering. Therefore, if this relationship is utilized, the erroneous engagement determination of the backup clutch can be performed. In addition, since the change direction of the operation and the driving direction of the steering actuator are reversed, it is only necessary to understand each change direction, and it does not take a long time to detect the state of the backup clutch, etc. Can be judged.
As a result, during the steer-by-wire control, it is possible to perform a smooth steering operation even if the backup clutch is erroneously engaged by determining the erroneous engagement of the backup clutch in a short time.

  Hereinafter, the best mode for carrying out the vehicle steering control apparatus of the present invention will be described based on Examples 1 to 4 shown in the drawings.

First, the configuration will be described.
[overall structure]
FIG. 1 is a configuration diagram of a steer-by-wire (SBW) system to which the vehicle steering control device of the first embodiment is applied.
The SBW system according to the first embodiment includes a steering wheel (operation unit) 1, a steering reaction force motor 2 (steering reaction force actuator), a steering angle sensor 3, a backup clutch 4, a backup cable 5, and a steering motor 6 ( (Steering actuator), steering angle sensor 7, steering mechanism 8 (steering portion), right front wheel 9a (steering wheel), left front wheel 9b (steering wheel), and steering reaction force controller 10 (steer) A by-wire control means), a turning controller 11 (steer-by-wire control means), and a vehicle speed sensor 12.

The SBW system of the first embodiment is a hardware system, and the steering wheel 1 that is operated by the driver, the steering mechanism 8 that is mechanically separated from the steering wheel 1 and steers the left and right front wheels 9a and 9b, and the steering wheel 1 is steered. A steering reaction force motor 2 that applies reaction force, a steering motor 6 that applies steering force to the steering mechanism 8, and a backup clutch 4 that mechanically connects and disconnects the handle 1 and the steering mechanism 8. I have.
Then, the SBW system of the first embodiment is a software system, and the steering wheel 1 and the steering mechanism 8 are disconnected by releasing the backup clutch 4 so that the steering angle is adjusted according to the operation state of the steering wheel 1. A steering device controller 11 for outputting a control command for driving the motor 6 and a control command for driving the steering reaction force motor 2 so as to apply a steering reaction force according to the steering state of the steering mechanism 8 are output. And a steering reaction force device controller 10.

  In addition, when an abnormality is found in a part of the SBW system, the backup clutch 4 is quickly connected, and the steering wheel 1 and the steering mechanism 8 are mechanically connected via the backup cable 5 to stop the SBW control. To do. Among these system abnormalities, when at least one of the steering reaction force motor 2 and the steered motor 6 can be driven, the steering reaction force motor 2 is applied so that the assist force is added to the operation force of the driver from the SBW control. And the assist control for driving at least one of the steering motor 6 is changed.

[Configuration of SBW control system]
FIG. 2 is a block diagram illustrating a control system for SBW control according to the first embodiment.
The sensor lead to input information, a steering angle sensor 3 as a steering reaction motor angle detecting means provided on the motor shaft of the steering reaction motor 2, a vehicle speed sensor 1 2 as vehicle speed detecting means, said steering And a turning angle sensor 7 as a turning motor angle detection means provided on the motor shaft of the motor 6.

The controller for executing the arithmetic processing includes a steering reaction force controller 10 having a backup clutch engagement determination means, a motor control command value calculation means, a motor drive means, a command turning angle calculation means, and a road surface μ estimation means, and a backup clutch engagement. And a turning controller 11 having a determination means, a motor control command value calculation means, a motor drive means, and a road surface μ estimation means. Note that the steering reaction force controller 10 and the turning controller 11 are connected by a bidirectional communication line.
In the steering controller 11, for example, as shown in the turning angle control block diagram of FIG. 3, the desired turning characteristic is given to the command turning angle θta calculated by the command turning angle calculation means. A robust model matching method consisting of a model matching compensator for matching and a robust compensator for estimating and canceling control impediment factors including modeling errors as disturbances is adopted, and the actual turning angle θt is calculated. The steered motor 6 is driven to obtain.
The backup clutch engagement determination means determines whether or not the backup clutch 4 is engaged during SBW control according to the flowchart shown in FIG.

  As the control actuator, a steering reaction force motor 2 as a steering reaction force actuator that receives a control command from the steering reaction force controller 10, a steering motor 6 as a steering actuator that receives a control command from the steering controller 11, It has.

[Clutch engagement determination process]
FIG. 4 is a flowchart showing the flow of the backup clutch engagement determination process executed by the steering reaction force controller 10 and the turning controller 11 of the first embodiment, and each step will be described below (clutch engagement determination means).

  In step S101, the vehicle speed V from the vehicle speed sensor 12, the actual steering angle θs from the steering angle sensor 3, the actual turning angle θt from the turning angle sensor 7, and the turning current It ( Either command / actual current may be used, but the command current is preferable because the command current changes first), and the process proceeds to step S102.

  In step S102, following the input information reading in step S101, in order to confirm the current command status to the backup clutch 4, the command to the backup clutch 4 is an engagement release command (the steering wheel 1 and the steering mechanism 8 are not connected). In the case of YES, the process proceeds to step S103, and in the case of NO, the process proceeds to step S104.

In step S103, following the determination that the command to the backup clutch 4 in step S102 is the engagement release command, the operation change direction is calculated from the actual steering angle θs read in step S101, and the process proceeds to step S105. .
Here, in the operation change direction calculation process, for example, the value of the actual steering angle θs (n−1) acquired last time is subtracted from the value of the actual steering angle θs (n) acquired this time, and the operation is calculated according to the sign of the value. The change direction is calculated.

In step S104, following the determination that the command to the backup clutch 4 in step S102 is an engagement command, the count value of the erroneous engagement determination number Ne is cleared, and the process returns to step S101.
That is, since it is determined that a command is issued so that the steering wheel 1 and the steering mechanism 8 are connected, the backup clutch 4 is intentionally engaged. Therefore, since there is no possibility that the backup clutch 4 is erroneously engaged, the count value of the erroneous engagement determination number Ne is cleared.

In step S105, following the operation change direction calculation process in step S103, the drive change direction of the turning motor 6 is calculated from the turning current It read in step S101, and the process proceeds to step S106.
Here, in the drive change direction calculation processing of the steering motor 6, the value of the steering current It (n-1) acquired last time is subtracted from the value of the steering current It (n) acquired this time, and the sign of the value is calculated. To calculate the driving change direction.

  In step S106, following the drive change direction calculation process of the steered motor 6 in step S105, it is determined whether or not the operation change direction and the drive change direction of the steered motor 6 are opposite. The process proceeds to step S107, and if NO, the process proceeds to step S108.

  In step S107, following the determination that the operation change direction in step S106 and the drive change direction of the steered motor 6 are opposite, the erroneous engagement determination number Ne is counted up, and the process proceeds to step S109.

  In step S108, following the determination that the operation change direction and the drive change direction of the steered motor 6 are the same in step S106, the erroneous engagement determination number Ne is counted down, and the process returns to step S101.

  In step S109, following the count-up of the erroneous engagement determination number Ne in step S107, the counted erroneous engagement determination number Ne is a predetermined value Nej (for example, 10 times so that the determination can be performed quickly while preventing erroneous determination). It is determined whether or not it is greater than or equal to.) If YES, the process proceeds to step S110. If NO, the process returns to step S101.

  In step S110, following the determination that the counted erroneous engagement determination number Ne in step S109 is greater than or equal to the predetermined value Nej, it is determined that the backup clutch 4 is erroneously engaged, and the count value of the erroneous engagement determination number Ne. Is cleared and the process proceeds to step S111.

In step S111, following the erroneous engagement determination of the backup clutch 4 in step S110, an engagement command (= connection command) is issued to the backup clutch 4, the contradiction between the command turning angle and the actual turning angle is eliminated, and the process ends. Transition.
Here, after issuing the engagement command to the backup clutch 4, the SBW control for driving one of the steering reaction force actuator 3 and the steering actuator 5 may be switched to the assist control, and a warning lamp (not shown) may be switched. It may be lit to warn the driver of switching to assist control.

Next, the operation will be described.
[Background technology]

In the conventional SBW system, when an abnormality occurs in a part of the system, the backup clutch is quickly connected, the steering wheel and the steering mechanism are mechanically connected, and the SBW control is stopped.
However, if an abnormality is recognized in a part of the SBW system and the backup clutch is not engaged, if the backup clutch is erroneously engaged (not intentionally engaged), SBW control will continue on the steered side. .
In addition, when SBW control is performed such that the steering gear ratio of the command turning angle with respect to the steering angle is smaller than the steering gear ratio when mechanically coupled (when the vehicle speed is high, steering is started, etc.) ), The ratio of the steering angle to the actual turning angle (ratio determined by mechanical coupling) when erroneously fastening is determined by the ratio of the commanded turning angle to the steering angle in SBW control. The steered motor is driven to return to the steered angle.
For this reason, in a state where the backup clutch is erroneously engaged, torque is generated so that the angle is increased from the angle or switched back to the angle. That is, it becomes difficult to operate the handle from this position.
In this state, the steered side tries to maintain the position, so that a driving force is generated, and the driving force is opposite to the steering direction. Therefore, the steering force for the driver to steer from this state increases as the amount of increase or return from the angle increases, and increases as the time increases.

[Backup clutch erroneous engagement determination action]
On the other hand, in the vehicle steering control device of the first embodiment, SBW control is performed such that the steering gear ratio of the command turning angle with respect to the steering angle is smaller than the steering gear ratio when mechanically coupled. In this case, attention is paid to the fact that the operation direction and the driving direction of the steering are reversed when the clutch is erroneously engaged, so that the erroneous engagement of the backup clutch 4 can be determined in a short time during the SBW control. .

  That is, at the time of SBW control, the steering wheel 6 is disconnected from the steering mechanism 8 by releasing the backup clutch 4, and the steering controller 11 drives the steering motor 6 so that the steering angle corresponds to the operation state of the steering wheel 1. And a control command for driving the steering reaction force motor 2 to output a steering reaction force according to the steering state of the steering mechanism 8 is output in the steering reaction force controller 10.

When the backup clutch 4 is erroneously engaged during SBW control in which the steering gear ratio Gr, which is the ratio of the command turning angle θta to the steering angle θs, is smaller than the steering gear ratio Gr when mechanically coupled. In the flowchart of FIG. 4, the process proceeds from step S101 → step S102 → step S103 → step S105 → step S106 → step S107 → step S109. That is, in step S106, it is determined that the operation change direction and the drive change direction of the steered motor 6 are opposite. In the next step S107, the erroneous engagement determination number Ne is counted up, and in the next step S109, the count is counted. If the number of erroneous fastening determinations Ne that has been increased is less than a predetermined value Nej (for example, about 10 times), the process returns to step S101.
If it is determined that the operation change direction and the drive change direction of the steered motor 6 are instantaneously the same direction, the process proceeds from step S106 to step S108, and the erroneous engagement determination number Ne is counted down. The determination that the change direction and the drive change direction of the steered motor 6 are opposite is continued, and there is a condition that the counted erroneous engagement determination number Ne in step S109 is equal to or greater than a predetermined value Nej (for example, about 10 times). If established, the process proceeds to step S110, where it is determined that the backup clutch 4 is erroneously engaged, the count value of the erroneous engagement determination number Ne is cleared, and in the next step S111, an engagement command is issued to the backup clutch 4.

Here, the reason why the erroneous engagement determination of the backup clutch 4 can be made by the determination logic used in the flowchart shown in FIG. 4 that the operation change direction and the drive change direction of the steered motor 6 are opposite to each other. This will be described below.
When the steering gear ratio (= θta / θs) of the command turning angle θta with respect to the steering angle θs is smaller than the steering gear ratio at the time of mechanical connection, each steering angle when further tightened due to erroneous engagement in FIG. The relationship between the steering current and the steering current is shown in FIG.
5 and 6, it can be said that if the backup clutch 4 is erroneously engaged, the change direction of the operation and the change direction of the steering current are reversed.

In other words, during SBW control, when the vehicle speed is high or when steering is started, the steering gear ratio of the command turning angle relative to the steering angle may be made smaller than the steering gear ratio when mechanically coupled. When the clutch 4 is in the released state, the change direction of the operation and the drive direction of the steered motor 6 are the same direction. In other words, the fact that the change direction of the operation and the drive direction of the steered motor 6 are opposite means that an abnormality has occurred in the backup clutch 4 related to both steering / steering. Therefore, if this relationship is utilized, the erroneous engagement determination of the backup clutch 4 can be performed.
In addition, since the change direction of the operation and the driving direction of the steering motor 6 are reversed, it is only necessary to understand each change direction, and it does not take a long time to detect the state of the backup clutch 4 and the like. The fastening can be determined.

In addition, when there is a deviation between the command turning angle and the actual turning angle at the time of erroneous engagement, FIG. 7 shows the relationship between each steering angle and the steering current when erroneously engaged and maintained, and FIG. When there is no deviation between the command turning angle and the actual turning angle, the relationship between each turning angle and the turning current when the steering is held in error is shown.
In FIG. 7, the steering current is integrated and is increased so as to eliminate the deviation between the command turning angle and the actual turning angle (when there is an integral element in the turning control), but the command turning angle and the actual turning angle are increased. The relationship of the turning angle is a relationship that maintains a constant value after steering. Further, in FIG. 8, since the steering is maintained in a state where there is no deviation between the command turning angle and the actual turning angle, the turning current hardly increases or decreases, and the relationship between the command turning angle and the actual turning angle is After the steering, the relationship is maintained at a constant value.
Therefore, after the erroneous engagement of the backup clutch 4 occurs, the operation change direction does not occur in the state where the steering is maintained, so that the erroneous engagement determination of the backup clutch 4 is not performed. It will not interfere with the steering.

Next, the effect will be described.
In the vehicle steering control device according to the first embodiment, the following effects can be obtained.

  (1) The steering wheel 1 operated by the driver and the steering wheel 1 are mechanically separated from each other, the steering mechanism 8 for turning the left and right front wheels 9a and 9b, and the steering reaction force for applying a steering reaction force to the steering wheel 1 A motor 2, a steering motor 6 that imparts a steering force to the steering mechanism 8, a backup clutch 4 that mechanically connects and disconnects the handle 1 and the steering mechanism 8, and the handle 1 by releasing the backup clutch 4. The steering mechanism 8 is disconnected, and a control command for driving the steering motor 6 to output a steering angle corresponding to the operation state of the steering wheel 1 is output, and steering according to the steering state of the steering mechanism 8 is output. A steering reaction force controller 10 and a steering controller 11 that output a control command for driving the steering reaction force motor 2 to apply a reaction force, and the steering wheel during steer-by-wire control. Since the steering mechanism 8 includes a clutch engagement determination unit (FIG. 4) that determines that the backup clutch 4 is in an engaged state when the driving direction of the steering mechanism 8 is opposite to the operation direction of 1. By determining the erroneous engagement of the backup clutch in a short time during the control, a smooth steering operation can be performed even if the erroneous engagement of the backup clutch 4 occurs.

  (2) During the steer-by-wire control in which the clutch engagement determination means (FIG. 4) outputs an engagement release command to the backup clutch 4 (step S102), the steering mechanism 8 with respect to the operation direction of the handle 1 When the driving direction is determined to be the reverse direction, the erroneous engagement determination number Ne is counted up (step S107), and when it is determined that the driving direction of the steering mechanism 8 is not the reverse direction with respect to the operation direction of the handle 1. The erroneous engagement determination number Ne is counted down (step S108), and when the erroneous engagement determination number Ne when counted up becomes equal to or greater than a predetermined value Nej (step S109), it is determined that the backup clutch 4 has been engaged. Therefore, erroneous engagement determination can be performed at an early timing from occurrence while preventing erroneous determination of engagement of the backup clutch 4.

(3) The clutch engagement determination means (FIG. 4) outputs an engagement command to the backup clutch 4 when it is determined that the backup clutch 4 is engaged during the steer-by-wire control (step S111). After the erroneous engagement determination of the backup clutch 4, the steering lock state can be prevented by shifting the control from the steer-by-wire control to the assist control or the like.
Incidentally, according to the invention of the first embodiment, it is possible to steer with only a small change in operating force of about 10 N by quickly detecting erroneous fastening and shifting the control to assist control or the like.

The second embodiment is an example in which the possibility of erroneous engagement of the backup clutch is determined based on the driving force value of the steering actuator, and the steering gear ratio is set smaller than the steering gear ratio at the time of mechanical coupling.
Since the system configuration is the same as that of the first embodiment shown in FIGS. 1 to 3, illustration and description thereof are omitted.

[Steering gear ratio change processing]
FIG. 9 is a flowchart showing the flow of the steering gear ratio changing process executed by the steering reaction force controller 10 and the steering controller 11 of the second embodiment. Each step will be described below (steering gear ratio changing means).

  In step S201, the vehicle speed V from the vehicle speed sensor 12, the actual steering angle θs from the steering angle sensor 3, the actual turning angle θt from the turning angle sensor 7, and the turning current It ( Either the command / actual current may be used, but the command current is preferable because the command current changes first), and the process proceeds to step S202.

  In step S202, following the input information reading in step S201, the driving force Ft of the steering motor 6 is calculated from the steering current It read in step S201 and the known mechanical constant of the steering motor 6. The process proceeds to step S203.

In step S203, following the driving force Ft calculation process in step S202, it is determined whether or not the driving force Ft of the steered motor 6 is equal to or greater than a predetermined value Ftj. If YES, the process proceeds to step S204. If NO, The process proceeds to step S205.
Here, the predetermined value Ftj of the driving force Ft of the steering motor 6 is set to a value larger than the driving force required for normal steering.

  In step S204, following the determination that the driving force Ft of the steered motor 6 in step S203 is equal to or greater than the predetermined value Ftj, the driving force determination number Nf is counted up, and the process proceeds to step S206.

  In step S205, following the determination that the driving force Ft of the steered motor 6 is less than the predetermined value Ftj in step S203, the driving force determination number Nf is counted down, and the process returns to step S201.

  In step S206, following the count-up of the driving force determination number Nf in step S204, the counted driving force determination number Nf is set to a predetermined value Nfj (for example, five times so that the determination can be performed quickly while preventing erroneous determination). It is determined whether or not it is greater than or equal to. If YES, the process proceeds to step S207, and if NO, the process returns to step S201.

  In step S207, following the determination that the counted driving force determination number Nf in step S206 is equal to or greater than the predetermined value Nfj, it is determined that there is a possibility that the backup clutch 4 is erroneously engaged, and the steering angle θs is determined. When the steering gear ratio Gr, which is the ratio of the commanded turning angle θta, is set to 1 based on the vehicle speed V, the actual steering angle θs, and the actual turning angle θt read in step S201, and 1 The value is determined to be smaller than 1, and the process proceeds to step S208. By performing such processing, the erroneous fastening determination logic described in FIG. 4 is validated.

  In step S208, following the process of making the steering gear ratio Gr smaller than 1 in step S207, the erroneous engagement determination process for the backup clutch 4 described in FIG. 4 is executed, and the process proceeds to step S209.

  In step S209, following the erroneous engagement determination process of the backup clutch 4 in step S208, it is determined whether or not it is determined that there is an erroneous engagement. If YES, the process proceeds to step S210, and if NO, the process returns to step S201.

  In step S210, following the determination of erroneous engagement in step S209, as a process for accurately performing the subsequent determination, the count value of the driving force determination number Nf is cleared, and the process proceeds to the end.

Next, the operation will be described.
[Steering gear ratio changing action]
When SBW control is being performed and the driving force Ft of the steering motor 6 is larger than the driving force required for normal steering, in the flowchart of FIG. 9, step S201 → step S202 → step S203 → step S204 → step Proceed to S206. That is, in step S203, it is determined that the driving force Ft of the steered motor 6 is equal to or greater than the predetermined value Ftj. In the next step S204, the driving force determination number Nf is counted up, but in the next step S206, the counting is performed. When the increased driving force determination number Nf is less than a predetermined value Nfj (for example, about 5 times), the process returns to step S201.
If it is determined that the driving force Ft is momentarily less than the predetermined value Ftj, the process proceeds from step S203 to step S205, and the driving force determination number Nf is counted down, but the driving force Ft is greater than or equal to the predetermined value Ftj. If it is determined that there is a condition, and the condition that the counted driving force determination number Nf in step S206 is equal to or greater than a predetermined value Nfj (for example, about 5 times), the process proceeds to step S207, and command steering for the steering angle θs The steering gear ratio Gr, which is the ratio of the angle θta, is determined to be smaller than 1.
Then, after setting the steering gear ratio Gr to a value smaller than 1, an erroneous engagement determination process for the backup clutch 4 is executed according to the flowchart shown in FIG.

  Here, it is determined that the possibility of erroneous engagement of the backup clutch 4 is large based on the determination logic used in the flowchart shown in FIG. 9 that the driving force Ft of the steered motor 6 is equal to or greater than the predetermined value Ftj. The reason why this is possible will be described below.

The steering load of the steered wheels when the SBW system is normal corresponds to the resisting force for steering that the left and right front wheels 9a and 9b, which are steered wheels, receive from the road surface, and the driving force that can counter this road surface resisting force If applied to the turning actuator, the turning operation of the left and right front wheels 9a, 9b is secured.
However, the steering load of the steered wheels when the backup clutch 4 is erroneously engaged is the road surface resistance that the left and right front wheels 9a, 9b, which are steered wheels, receive from the road surface, and from the handle 1 side via the backup clutch 4. This is equivalent to the sum of the steering resistance force (steering force by the driver or the steering reaction force by the motor) and the driving force that can counter the sum of this road resistance force and the steering resistance force. Therefore, the driving force becomes larger than the driving force necessary for turning at normal time. This point is also clear from the fact that the turning current shows an increase characteristic when the steering is erroneously held and held as shown in FIG.
Therefore, there is a high possibility that the backup clutch 4 is erroneously engaged due to the determination logic that the driving force Ft of the steering motor 6 is equal to or greater than a predetermined value Ftj (a value larger than the driving force required for normal steering). Can be determined.

As described above, in the second embodiment, when the driving force Ft of the steering motor 6 is equal to or greater than the predetermined value Ftj, the backup clutch 4 may be erroneously engaged. By setting the steering gear ratio Gr, which is the ratio of the angle θta, to a value smaller than 1, the erroneous engagement determination logic shown in FIG. 4 can be validated, and an erroneous engagement determination with higher accuracy becomes possible.
Further, it is possible to prevent the steering wheel 1 from being removed when the steering gear ratio Gr, which is the ratio of the command turning angle θta to the steering angle θs, is set to a value larger than 1, that is, when the quick control is continued. .
Further, by setting the steering gear ratio Gr, which is the ratio of the command turning angle θta to the steering angle θs, to a value smaller than 1, the amount of displacement of the command turning angle θta can be reduced. The force can be suppressed (the load can be reduced), and an increase in steering force when erroneously engaged can be suppressed.

Next, the effect will be described.
In the vehicle steering control apparatus according to the second embodiment, in addition to the effects (1) to (3) of the first embodiment, the following effects can be obtained.

  (4) During the steer-by-wire control, when there is a possibility that the backup clutch 4 is erroneously engaged, a steering gear ratio Gr, which is a ratio of the steering amount of the steering mechanism 8 to the operation amount of the handle 1, Steering gear ratio changing means (FIG. 9) for setting smaller than the steering gear ratio Gr when the steering wheel 1 and the steering mechanism 8 are mechanically connected is provided, and the clutch engagement determining means (FIG. 4) When the steering gear ratio Gr is changed by the steering gear ratio changing means, in order to determine whether or not the backup clutch 4 is in the engaged state, by enabling the erroneous engagement determination logic, a more accurate backup clutch 4 erroneous fastening determination can be performed. In addition, it is possible to prevent the handle 1 from being removed when the quick control is continued. Furthermore, the driving force of the steering motor 6 can be kept small.

  (5) The steering gear ratio changing means (FIG. 9) turns the steering mechanism 8 with respect to the operation amount of the handle 1 when the driving force Ft of the steering motor 6 is equal to or greater than a predetermined value Ftj (step S203). In order to set the steering gear ratio Gr, which is a ratio of the amount, smaller than the steering gear ratio Gr when the steering wheel 1 and the steering mechanism 8 are mechanically connected (step S207), the state of the backup clutch 4 is detected, etc. In order to determine that there is a possibility that the backup clutch 4 is erroneously engaged in a short time with good response by the driving force Ft of the steered motor 6 without taking a long time to enable the erroneous engagement determination logic. The gear ratio can be changed.

The third embodiment is an example in which the possibility of erroneous engagement of the backup clutch is determined based on the deviation of the actual turning angle with respect to the estimated turning angle, and the steering gear ratio is set smaller than the steering gear ratio at the time of mechanical coupling.
Since the system configuration is the same as that of the first embodiment shown in FIGS. 1 to 3, illustration and description thereof are omitted.

[Steering gear ratio change processing]
FIG. 10 is a flowchart showing the flow of the steering gear ratio changing process executed by the steering reaction force controller 10 and the steering controller 11 of the third embodiment. Each step will be described below (steering gear ratio changing means). Steps S301 and S307 to S310 are steps corresponding to steps S201 and S207 to S210 of the flowchart shown in FIG.

  In step S302, following the input information reading in step S301, the turning of the actual turning angle θt with respect to the estimated turning angle θt ^ estimated from the command turning angle θta corresponding to the actual steering angle θ read in step S301. The angular deviation Δθt is calculated, and the process proceeds to step S303.

In step S303, following the turning angle deviation Δθt calculation processing in step S302, it is determined whether the turning angle deviation Δθt is equal to or greater than a predetermined value Δθtj. If YES, the process proceeds to step S304. If NO, step S304 is performed. The process proceeds to S305.
Here, the predetermined value Δθtj of the turning angle deviation Δθt is set to a value larger than a value assumed to be a normal motor control response of the turning motor 6.

  In step S304, following the determination that the turning angle deviation Δθt is greater than or equal to the predetermined value Δθtj in step S303, the deviation determination number Na is counted up, and the process proceeds to step S306.

  In step S305, following the determination that the turning angle deviation Δθt is less than the predetermined value Δθtj in step S303, the deviation determination number Na is counted down, and the process returns to step S301.

  In step S306, following the count-up of the deviation determination number Na in step S304, the counted deviation determination number Na is a predetermined value Naj (for example, about five times so that the determination can be made quickly while preventing erroneous determination). If it is YES, the process proceeds to step S307, and if it is NO, the process returns to step S301.

Next, the operation will be described.
[Steering gear ratio changing action]
During the SBW control, the turning angle deviation Δθt of the actual turning angle θt with respect to the estimated turning angle θt ^ estimated from the command turning angle θta corresponding to the actual steering angle θ When the motor control responsiveness is larger than the assumed value, the process proceeds from step S301 to step S302 to step S303 to step S304 to step S306 in the flowchart of FIG. That is, in step S303, it is determined that the turning angle deviation Δθt is greater than or equal to the predetermined value Δθtj, and in the next step S304, the deviation determination number Na is counted up, but in the next step S306, the counted deviation is increased. When the determination number Na is less than a predetermined value Naj (for example, about 5 times), the process returns to step S301.
When it is determined that the turning angle deviation Δθt is instantaneously less than the predetermined value Δθtj, the process proceeds from step S303 to step S305, and the deviation determination number Na is counted down, but the turning angle deviation Δθt is a predetermined value. If the determination that Δθtj or more is continued and the condition that the counted deviation determination number Na is greater than or equal to a predetermined value Naj (for example, about 5 times) is established in step S306, the process proceeds to step S307, and a command for the steering angle θs is issued. The steering gear ratio Gr, which is the ratio of the turning angle θta, is determined to be smaller than 1.
Then, after setting the steering gear ratio Gr to a value smaller than 1, an erroneous engagement determination process for the backup clutch 4 is executed according to the flowchart shown in FIG.

  Here, it is possible to determine that the possibility of erroneous engagement of the backup clutch 4 is large by the determination logic used in the flowchart shown in FIG. 10 that the turning angle deviation Δθt is equal to or larger than the predetermined value Δθtj. The reason will be described below.

In the steering control when the SBW system is normal, when the command turning angle θta is calculated according to the actual steering angle θ, a drive command for obtaining the command turning angle θta is output to the steering motor 6 and the steering is performed. The left and right front wheels 9a, 9b, which are wheels, are steered by a motor driving force, and an actual steered angle θt is generated. At this time, the relationship between the command turning angle θta and the actual turning angle θt has a small turning angle deviation corresponding to a response delay assumed from the motor control response of the turning motor 6.
However, in the steering control when the backup clutch 4 is erroneously engaged, when the command turning angle θta is calculated according to the actual steering angle θ, a drive command for obtaining the command turning angle θta is issued to the steering motor. The left and right front wheels 9a and 9b , which are steered wheels, are combined with the force of the motor driving force output to 6 and the force in the steered direction input from the handle 1 side via the backup clutch 4. The actual steering angle θt is generated. Therefore, when the backup clutch 4 is erroneously engaged, the relationship between the command turning angle θta and the actual turning angle θt is assumed to be a follow-up relationship due to the motor control response delay, and is assumed from the motor control responsiveness of the turning motor 6. The steering angle deviation is larger than the response delay. As shown in FIG. 5 and FIG. 6, the difference between the actual turning angle and the command turning angle at the time of incorrect fastening and further turning up or turning back is gradually increased as time passes. It is also clear from the fact that it shows the expanding characteristics.
Therefore, the determination logic that the turning angle deviation Δθt is equal to or greater than the predetermined value Δθtj (a value larger than the value assumed for the motor control response of the turning motor 6) is likely to cause erroneous engagement of the backup clutch 4. It can be determined.

As described above, in the third embodiment, when the turning angle deviation Δθt is equal to or larger than the predetermined value Δθtj, the backup clutch 4 may be erroneously engaged. Therefore, the command turning angle θta relative to the steering angle θs By setting the steering gear ratio Gr, which is the ratio, to a value smaller than 1, the erroneous engagement determination logic shown in FIG. 4 can be validated, and an erroneous engagement determination with higher accuracy becomes possible.
Further, it is possible to prevent the steering wheel 1 from being removed when the steering gear ratio Gr, which is the ratio of the command turning angle θta to the steering angle θs, is set to a value larger than 1, that is, when the quick control is continued. .
Further, by setting the steering gear ratio Gr, which is the ratio of the command turning angle θta to the steering angle θs, to a value smaller than 1, the amount of displacement of the command turning angle θta can be reduced. Force can be reduced (load can be reduced).

Next, the effect will be described.
In the vehicle steering control device of the third embodiment, in addition to the effects (1), (2), (3) of the first embodiment and (4) of the second embodiment, the following effects can be obtained.

  (6) The steering gear ratio changing means (FIG. 10) has a predetermined deviation Δθt of the actual turning angle θt with respect to the estimated turning angle θt ^ estimated from the command turning angle θta corresponding to the operation amount of the handle 1. When the angle Δθtj or more (step S303), the steering gear ratio Gr, which is the ratio of the steering amount of the steering mechanism 8 to the operation amount of the steering wheel 1, is mechanically connected to the steering mechanism 8. Therefore, the backup clutch 4 is erroneously engaged in a short time with good response by the turning angle deviation Δθt without taking a long time to detect the state of the backup clutch 4 and the like (step S307). The gear ratio can be changed to determine that there is a possibility that the erroneous engagement determination logic is valid.

In Example 4, in the erroneous engagement determination process of Examples 1 to 3, a threshold value is provided for the current value on the steering side, and the backup clutch 4 is erroneously engaged when the current value exceeds the threshold value. This is an example of determination.
Since the system configuration is the same as that of the first embodiment shown in FIGS. 1 to 3, illustration and description thereof are omitted.

[Clutch engagement determination process]
FIG. 11 is a flowchart showing the flow of the backup clutch engagement determination process executed by the steering reaction force controller 10 and the turning controller 11 of the fourth embodiment, and each step will be described below (clutch engagement determination means). Steps S401 to S406 correspond to the steps S101 to S106 in the flowchart of FIG.

  In step S407, following the determination that the operation change direction in step S406 and the drive change direction of the steering motor 6 are opposite, the vehicle speed V from the vehicle speed sensor 12 and the actual steering angle θs from the steering angle sensor 3 are determined. The actual turning angle θt from the turning angle sensor 7, the ratio Gr of the command turning angle to the steering angle from the steering reaction force controller 10, the turning current It from the turning controller 11, and the road surface μ estimation. The road surface μ value μe from the means is read, and the process proceeds to step S408.

In step S408, following the input information reading in step S407, a steered current threshold Ith is calculated from each read information, and the process proceeds to step S409.
That is, in a situation where the current required for turning is considered to be small, the determination time can be shortened by setting the turning current threshold value Ith small. The steering current threshold Ith is set from an assumed current value by calculating a self-aligning torque based on a vehicle model such as a vehicle speed and an actual steering angle based on a vehicle model. In this case, it may be set in advance simply by a combination of the vehicle speed and the actual turning angle.
For example, there is a method of determining the steering current threshold value Ith in the following situation.
(a) As shown in FIG. 12, as the steering gear ratio Gr, which is the ratio of the commanded turning angle θta to the steering angle θs, is larger (however, a value smaller than the steering gear ratio in which the operation unit and the turning unit are directly connected) Set the steering current threshold Ith to a small value.
(b) As shown in FIG. 13, the steering angular velocity θsp (= dθs / dt) is calculated from the actual steering angle θs, and the steered current threshold Ith is set to a smaller value as the steering angular velocity θsp is lower.
(c) As shown in FIG. 14, the steered current threshold Ith is set to a smaller value as the road surface friction coefficient μe is lower.
In other words, the force that causes the vehicle to move is generated from the frictional force between the tire and the road surface, so if the road surface μ changes, the lateral force also changes and the self-aligning torque also changes, so the same steering speed is cut at the same vehicle speed. The current required for this also changes.
Further, at the time of turning back the steering wheel, a deviation is generated in the direction of increase on the steered side, so that the current is increased because of driving in the direction of increase in turn. On the other hand, when the steering wheel is increased, a deviation occurs in the return direction on the steered side, so that the current is reduced because the steering is driven in the return direction. Therefore, the turning current threshold value Ith is set to be smaller when the steering wheel is turned more than when the steering wheel is turned back.

  In step S409, following the calculation process of the steering current threshold Ith in step S408, it is determined whether the steering current It is equal to or greater than the steering current threshold Ith. If YES, step S410 is determined. If NO, the process moves to step S411.

  In step S410, following the determination that the turning current It in step S409 is greater than or equal to the turning current threshold Ith, the current determination number Ni is counted up, and the process proceeds to step S412.

  In step S411, following the determination that the turning current It in step S409 is less than the turning current threshold Ith, the current determination number Ni is counted down, and the process returns to step S401.

  In step S412, following the count-up of the current determination number Ni in step S410, the counted current determination number Ni is set to a predetermined value Nij (for example, about five times so that the determination can be made quickly while preventing erroneous determination). If it is YES, the process proceeds to step S413, and if NO, the process returns to step S401.

  In step S413, following the determination that the counted current determination number Ni in step S412 is equal to or greater than the predetermined value Nij, it is determined that the backup clutch 4 is erroneously engaged, and the count value of the current determination number Ni is cleared. Then, the process proceeds to step S414.

In step S414, following the erroneous engagement determination of the backup clutch 4 in step S413, an engagement command (= connection command) is issued to the backup clutch 4, the contradiction between the command turning angle and the actual turning angle is eliminated, and the process ends. Transition.
Here, after issuing the engagement command to the backup clutch 4, the SBW control for driving one of the steering reaction force actuator 3 and the steering actuator 5 may be switched to the assist control, and a warning lamp (not shown) may be switched. It may be lit to warn the driver of switching to assist control.

Next, the operation will be described.
[Backup clutch erroneous engagement determination action]
In the vehicle steering control device of the fourth embodiment, during SBW control in which the steering gear ratio Gr, which is the ratio of the command turning angle θta to the steering angle θs, is smaller than the steering gear ratio Gr when mechanically coupled, or When the backup clutch 4 is erroneously engaged while the SBW control is set to be small, in the flowchart of FIG. 11, step S401 → step S402 → step S403 → step S405 → step S406 → step S407 → step S408 → step S409 → The process proceeds from step S410 to step S412. That is, in step S406, it is determined that the operation change direction and the drive change direction of the turning motor 6 are opposite. In step S409, it is determined that the turning current It is equal to or greater than the turning current threshold Ith. In step S410, the current determination number Ni is counted up. In step S412, the counted current determination number Ni is less than a predetermined value Nij (for example, about five times), and the process returns to step S401.
When it is determined that the turning current It is momentarily less than the turning current threshold Ith, the process proceeds from step S409 to step S411, and the current determination number Ni is counted down, but the turning current It is When it is determined that the turning current threshold value is greater than or equal to the steering current threshold value Ith, and the condition that the counted current determination number Ni is greater than or equal to a predetermined value Nij (for example, about 5 times) in step S412, the process proceeds to step S413. Then, it is determined that the backup clutch 4 is erroneously engaged, the count value of the current determination number Ni is cleared, and an engagement command is issued to the backup clutch 4 in the next step S414.

As described above, in the fourth embodiment, when the operation change direction and the drive change direction of the steered motor 6 are opposite, the judgment logic that the steered current It is equal to or greater than the steered current threshold Ith is used for backup. An erroneous engagement determination of the clutch 4 is made.
That is, since the driving direction opposite to the operation direction is determined by the current flowing to the steered side, the erroneous engagement determination of the backup clutch 4 can be performed at an earlier timing by using the steered current It. .
In addition, since the steering current It is a current value used in the normal SBW control, it is not necessary to use another sensor when determining erroneous engagement of the backup clutch 4.

Next, the effect will be described.
In the vehicle steering control device of the fourth embodiment, the effects listed below are obtained in addition to the effects of the first to third embodiments.

  (7) The steered actuator is a steered motor 6, and the clutch engagement determining means (FIG. 11) has the drive direction of the steering mechanism 8 reversed with respect to the operation direction of the handle 1 during steer-by-wire control. When the direction becomes the direction (step S406) and the motor current value It to the steered motor 6 is equal to or greater than the steered current threshold Ith (step S409), the backup clutch 4 is engaged. Therefore, it is not necessary to use another sensor when determining the erroneous engagement of the backup clutch 4, and the erroneous engagement determination of the backup clutch 4 can be performed at an early timing from the occurrence of the erroneous engagement.

  (8) The clutch engagement determination means (FIG. 11) determines that the steering current threshold increases as the steering gear ratio Gr, which is the ratio of the command turning angle θta of the steering mechanism 8 to the steering angle θs of the handle 1, increases. Since the value Ith is set to a small value (step S408), it is possible to make a quick erroneous engagement determination with respect to a difference in current fluctuation due to a difference in steering gear ratio.

  (9) The clutch engagement determination means (FIG. 11) sets the steering current threshold Ith to a smaller value as the steering angular velocity θsp of the steering wheel 1 is lower (step S408), and therefore the steering angular velocity θsp is different. It is possible to make a quick erroneous fastening determination with respect to a difference in current fluctuation caused by the above.

  (10) The clutch engagement determination means (FIG. 11) sets the steering current threshold Ith to a smaller value as the road surface friction coefficient μe is lower (step S408), and therefore, the road surface friction coefficient μe is different. A quick erroneous fastening determination can be made for the difference in current fluctuation.

  As mentioned above, although the vehicle steering control apparatus of the present invention has been described based on the first to fourth embodiments, the specific configuration is not limited to these embodiments, and each claim of the claims Design changes and additions are permitted without departing from the spirit of the invention according to the paragraph.

  For example, in Examples 2 and 3, when the driving force is greater than or equal to a predetermined value, or when the turning angle deviation is greater than or equal to a predetermined value, it is determined that there is a possibility of erroneous engagement of the backup clutch, and the steering gear ratio is set to 1. In the example shown below, the steering gear ratio may be set to 1 or less to make an erroneous engagement determination, for example, when the vehicle is traveling straight ahead with little influence on the vehicle behavior even if the steering gear ratio is 1 or less. good.

  In the first to fourth embodiments, an example of application to a steer-by-wire system including a backup clutch and a backup cable as a backup mechanism has been shown. However, for example, the present invention can also be applied to an SBW system having only a backup clutch. In short, the operation part and the turning part are separated by releasing the backup clutch, and a control command for driving the turning actuator to output a turning angle corresponding to the operation state of the operating part is output, and the turning of the turning part is performed. Any vehicle steering control device that executes steer-by-wire control that outputs a control command for driving a steering reaction force actuator so as to apply a steering reaction force according to a state can be applied.

1 is a configuration diagram of a steer-by-wire (SBW) system to which a vehicle steering control device according to a first embodiment is applied. FIG. 3 is a block diagram illustrating a control system for SBW control according to the first embodiment. It is a control block diagram at the time of employ | adopting a robust model matching method as steering control among the steer-by-wire controls of Example 1. FIG. It is a flowchart which shows the flow of the backup clutch fastening determination process performed with the steering reaction force controller and steering controller of Example 1. FIG. It is a characteristic view which shows the relationship between each steering angle and steering current when the backup clutch is erroneously engaged and further increased. It is a characteristic view which shows the relationship between each steering angle and steering current when a backup clutch is erroneously engaged and switched back. It is a characteristic view which shows the relationship between each steering angle and steering current at the time of incorrect fastening when it has deviation when there exists a deviation in a command turning angle and an actual turning angle. It is a characteristic view which shows the relationship between each steering angle and steering current at the time of incorrect fastening and maintaining when there is no deviation between the command turning angle and the actual turning angle. It is a flowchart which shows the flow of the steering gear ratio change process performed with the steering reaction force controller and steering controller of Example 2. FIG. It is a flowchart which shows the flow of the steering gear ratio change process performed with the steering reaction force controller and steering controller of Example 2. FIG. It is a flowchart which shows the flow of the backup clutch fastening determination process performed with the steering reaction force controller and steering controller of Example 4. It is a figure which shows the relationship of the steering current threshold value of ratio of the command turning angle with respect to a steering angle. It is a figure which shows the relationship between a steering angular velocity and a steering current threshold value. It is a figure which shows the relationship between road surface (micro | micron | mu) and steering current threshold value.

Explanation of symbols

1 Handle (operating part)
2 Steering reaction force motor (steering reaction force actuator)
3 Steering angle sensor 4 Backup clutch 5 Backup cable 6 Steering motor (steering actuator)
7 Steering angle sensor 8 Steering mechanism (steering part)
9a Front right wheel (steering wheel)
9b Left front wheel (steering wheel)
10 Steering reaction force controller (steer-by-wire control means)
11 Steering controller (steer-by-wire control means)
12 Vehicle speed sensor

Claims (11)

An operation unit operated by the driver;
A steering part that is mechanically separated from the operation part and steers the steering wheel;
A steering reaction force actuator for applying a steering reaction force to the operation unit;
A steering actuator for applying a steering force to the steering unit;
A backup clutch that mechanically connects and disconnects the operation unit and the steering unit;
The operation unit and the steered unit are separated by releasing the backup clutch, and a control command for driving the steered actuator to output a steered angle according to an operation state of the operating unit is output, and the steered Steer-by-wire control means for outputting a control command for driving the steering reaction force actuator so as to apply a steering reaction force according to the steering state of the unit;
During steer-by-wire control, when the drive direction of the steered portion is opposite to the operation direction of the operation portion, clutch engagement determining means for determining that the backup clutch has been engaged,
A vehicle steering control device comprising: The vehicle steering control device according to claim 1,
In the steer-by-wire control that outputs an engagement release command to the backup clutch, the clutch engagement determination means erroneously determines that the drive direction of the steered portion is opposite to the operation direction of the operation portion. Counts up the number of times of fastening, and counts down the number of times of wrong fastening when it is determined that the driving direction of the steered portion is not opposite to the direction of operation of the operating portion, and determines wrong fastening when counted up. When the number of times becomes equal to or greater than a predetermined value, it is determined that the backup clutch has been engaged. In the vehicle steering control device according to claim 1 or 2,
The vehicle steering control device, wherein the clutch engagement determination means outputs an engagement command to the backup clutch when it is determined that the backup clutch is engaged during the steer-by-wire control. The vehicle steering control device according to any one of claims 1 to 3,
During steer-by-wire control, when there is a possibility that the backup clutch is erroneously engaged, a steering gear ratio, which is a ratio of the turning amount of the turning unit to the operation amount of the operation unit, is set to the operation unit and the operation unit. A steering gear ratio changing means for setting the steering gear ratio to be smaller than the steering gear ratio when mechanically connected to the steered portion;
The vehicle steering control device, wherein the clutch engagement determining means determines whether or not the backup clutch is in an engaged state when the steering gear ratio is changed by the steering gear ratio changing means. In the vehicle steering control device according to claim 4,
When the driving force value of the steering actuator is greater than or equal to a predetermined value, the steering gear ratio changing unit is configured to set a steering gear ratio, which is a ratio of a steering amount of the steering unit to an operation amount of the operating unit, as the operation unit. The steering control device for a vehicle is set to be smaller than a steering gear ratio when the steering unit and the steering unit are mechanically connected. In the vehicle steering control device according to claim 4 or 5,
When the deviation of the actual turning angle with respect to the estimated turning angle estimated from the command turning angle corresponding to the operation amount of the operation unit is equal to or greater than a predetermined angle, the steering gear ratio changing unit Steering for a vehicle, wherein a steering gear ratio, which is a ratio of a steering amount of the steering section, is set smaller than a steering gear ratio when the operation section and the steering section are mechanically connected. Control device. The vehicle steering control device according to any one of claims 1 to 6,
The steering actuator is a steering motor,
The clutch engagement determination unit is configured so that, during steer-by-wire control, the driving direction of the steered portion is opposite to the operation direction of the operating portion, and the motor current value to the steered motor is changed. A steering control device for a vehicle, wherein when the steering current threshold value is equal to or greater than a steering current threshold value, it is determined that the backup clutch has been engaged. In the vehicle steering control device according to claim 7,
The clutch engagement determination means sets the steering current threshold value to a smaller value as the steering gear ratio, which is the ratio of the steering amount of the steering unit to the operation amount of the operation unit, is larger. A vehicle steering control device. In the vehicle steering control device according to claim 7 or 8,
The vehicle steering control device, wherein the clutch engagement determination unit sets the steering current threshold value to a smaller value as the operation speed of the operation unit is lower. The vehicle steering control device according to any one of claims 7 to 9,
The vehicle steering control device, wherein the clutch engagement determination means sets the steering current threshold value to a smaller value as the road surface friction coefficient is lower. An operation unit operated by the driver;
A steering part that is mechanically separated from the operation part and steers the steering wheel;
A steering reaction force actuator for applying a steering reaction force to the operation unit;
A steering actuator for applying a steering force to the steering unit;
A backup clutch that mechanically connects and disconnects the operation unit and the steering unit,
The operation unit and the steered unit are separated by releasing the backup clutch, and a control command for driving the steered actuator to output a steered angle according to an operation state of the operating unit is output, and the steered In a vehicle steering control device that executes steer-by-wire control that outputs a control command to drive the steering reaction force actuator so as to apply a steering reaction force according to a steering state of the unit,
During the steer-by-wire control, when the drive direction of the steered portion is opposite to the operation direction of the operation portion, it is determined that the backup clutch has been engaged. apparatus.

Images