JP2014223861A - Vehicular steering control device and vehicular steering control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular steering control device and a vehicular steering control method capable of performing SBW control and control of drive support function even when a stored steering angle cannot be read out.SOLUTION: When voltage of a battery becomes less than a voltage threshold in the on-state of an ignition switch, a clutch in the open state is switched into the fastening state and, further, drive support function for a driver of a vehicle is controlled by using a steering angle estimated immediately before the clutch is switched into the fastening state. When the clutch in the fastening state is switched into the open state, the voltage less than the voltage threshold becomes the voltage threshold or more and, by using the steering angle estimated when it is determined that a running state of the vehicle is straight, control of drive support function and calculation of target steering angle are performed.

Description

  The present invention steers the steered wheel via an actuator such as a steered motor according to the steering operation of the steering wheel in a state where the torque transmission path between the steering wheel and the steered wheel is mechanically separated. The present invention relates to a vehicle steering control device and a vehicle steering control method.

  As a device for controlling a steered wheel of a vehicle, for example, as described in Patent Document 1, a steer-by-wire method (SBW method) in which a steering wheel (steering operator) and a steered wheel are mechanically separated from each other is used. There is a vehicle steering control device.

JP 2004-291877 A

In the SBW-type vehicle steering control device, when the ignition switch is switched to the off state when the ignition switch is switched to the off state and the power supply from the battery to the ECU (calculation unit) is cut off, such as during parking. The steered angle of the steered wheels estimated in step 1 is stored. In addition, the torque transmission path is mechanically connected. When the ignition switch in the off state is switched to the on state, for example, when the vehicle starts, the torque transmission path is mechanically separated, and the torque transmission path is mechanically separated based on the stored turning angle. Steering wheel turning control (SBW control) in the state is performed.
However, in the conventional SBW-type vehicle steering control device including Patent Document 1, when the power supply from the battery to the ECU is cut off in a state outside the control target, the stored turning angle can be read out. There may not be.

For this reason, when the supply of electric power to the ECU is interrupted in a state outside the control target, it is not possible to control the driving support function (ABS control or the like), which is control performed based on the stored turning angle. May occur.
The present invention has been made by paying attention to the above-described problems, and is capable of controlling a driving support function even when the stored turning angle cannot be read. An object is to provide a steering control device and a steering control method.

  In order to solve the above-described problems, the present invention switches the clutch from the disengaged state to the engaged state when the ignition switch is in the on state and the battery voltage is less than a preset voltage threshold. And a driving assistance function is controlled using the turning angle estimated just before the clutch of an open state switches to a fastening state. Further, when the clutch is switched from the engaged state to the released state, the driving support function is performed using the turning angle estimated when the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the vehicle traveling state is determined to be straight ahead. Control.

According to the present invention, when the clutch is switched from the engaged state to the released state, the voltage less than the voltage threshold is equal to or higher than the voltage threshold, and the turning angle estimated when the traveling state of the vehicle is determined to be straight traveling is used. It becomes possible to control the driving support function.
For this reason, even when the stored turning angle cannot be read out, driving assistance is performed using the turning angle estimated with high estimation accuracy from the time when the clutch is switched from the engaged state to the released state. The function can be controlled.

1 is a diagram illustrating a schematic configuration of a vehicle including a vehicle steering control device according to a first embodiment of the present invention. It is a block diagram which shows the structure of a comprehensive controller. It is a figure which shows a turning angle estimation map. It is a figure which shows a limit angle setting map. It is a figure which shows the table which a driving mode setting part uses for the setting of driving mode. It is a flowchart which shows the process which a comprehensive controller performs. It is a time chart which shows the process which a comprehensive controller performs. It is a time chart which shows operation | movement of the vehicle using the steering control apparatus for vehicles of 1st embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
Hereinafter, a first embodiment of the present invention (hereinafter referred to as the present embodiment) will be described with reference to the drawings.
(Constitution)
FIG. 1 is a diagram illustrating a schematic configuration of a vehicle including the vehicle steering control device of the present embodiment.
A vehicle equipped with the vehicle steering control device 1 of the present embodiment employs a system (SBW system) referred to as a steer-by-wire (SBW: Steer By Wire, which may be described as “SBW” in the following description). Vehicle.

  Here, in the SBW system, driving of an actuator (for example, a steered motor) is controlled in accordance with an operation of a steering wheel (steering wheel) that is steered by a driver of the vehicle, and the steered wheel is steered. Thus, the traveling direction of the vehicle is changed. For the drive control of the steering motor, the clutch that is interposed between the steering wheel and the steered wheel is switched to the open state, which is the normal state, and the torque transmission path between the steering wheel and the steered wheel is mechanically separated. Perform in the state. Further, the drive control of the steering motor is performed according to the calculated target turning angle by switching the clutch to the disengaged state, calculating the target turning angle according to the steering angle of the steering wheel.

  For example, when an abnormality occurs in a part of the SBW system such as disconnection, or when the voltage of the battery mounted on the vehicle is lowered and the control of the SBW system becomes impossible, the clutch in the opened state Is switched to the fastening state, and the torque transmission path is mechanically connected. Thus, the turning of the steered wheels is continued using the force applied by the driver to the steering wheel. In addition to this, EPS (Electric Power Steering) control for outputting assist torque from the steered motor is performed in accordance with the operation state (steering amount, steering torque, steering speed, etc.) of the steering wheel by the driver. Note that, for example, the configuration of the vehicle includes a control changeover switch arranged in the passenger compartment, and the driver switches the control from the SBW system to the EPS control arbitrarily by the driver by operating the control changeover switch. It is good also as a structure which can be performed to.

  As shown in FIG. 1, the vehicle steering control device 1 of the present embodiment includes a first steering motor 2, a second steering motor 4, a reaction force motor 6, a clutch 8, and a steering angle detection unit. 10, a vehicle speed detection unit 12, and a yaw rate detection unit 14. In addition, the vehicle steering control device 1 includes a first turning motor angle sensor 16, a second turning motor angle sensor 18, a first turning motor torque sensor 20, and a general controller 22.

The first steered motor 2 is an electric motor that is driven according to the steered motor drive current output by the general controller 22, and rotates according to the target steered angle described above to steer the steered wheels 24. A steering actuator is formed. Moreover, the 1st steering motor 2 outputs the 1st steering torque for turning the steered wheel 24 by driving according to a steering motor drive current. As the steering actuator, it is possible to use a power cylinder, a hydraulic circuit including a solenoid, or the like in addition to the electric motor.
The first turning motor 2 has a rotatable first turning motor output shaft 26.
A first turning output gear (not shown) formed using a pinion gear is provided on the tip side of the first turning motor output shaft 26.
The first turning output gear meshes with a rack gear (not shown) provided between both ends of the rack shaft 30 inserted through the steering rack 28.

Like the first steering motor 2, the second steering motor 4 is an electric motor that is driven according to the steering motor drive current output by the integrated controller 22, and rotates according to the target steering angle described above. A steering actuator that controls the steering wheel 24 is formed. Similarly to the first steering motor 2, the second steering motor 4 outputs a second steering torque for turning the steered wheels 24 by being driven according to the steering motor drive current.
The second turning motor 4 has a rotatable second turning motor output shaft 32.
A second turning output gear (not shown) that is formed by using a pinion gear and meshes with the rack gear is provided on the distal end side of the second turning motor output shaft 32.

The steering rack 28 is formed in a cylindrical shape and allows the rack shaft 30 to be inserted therethrough.
The rack shaft 30 rotates at least one of the first steered motor output shaft 26 and the second steered motor output shaft 32, that is, rotates at least one of the first steered output gear and the second steered output gear. The vehicle is displaced in the vehicle width direction according to
Further, both ends of the rack shaft 30 are connected to the steered wheels 24 via tie rods 34 and knuckle arms 36, respectively.

  The steered wheels 24 are front wheels (left and right front wheels) of the vehicle, and the rack shaft 30 is displaced in the vehicle width direction according to the rotation of at least one of the first steered motor output shaft 26 and the second steered motor output shaft 32. Then, the steering is performed through the tie rod 34 and the knuckle arm 36. Thereby, the advancing direction of a vehicle is changed. In the present embodiment, a case where the steered wheels 24 are formed of left and right front wheels will be described. Accordingly, in FIG. 1, the steered wheel 24 formed with the left front wheel is denoted as steered wheel 24FL, and the steered wheel 24 formed with the right front wheel is denoted as steered wheel 24FR.

The reaction force motor 6 is an electric motor that is driven in accordance with a reaction force motor drive current output from the general controller 22, and forms a reaction force actuator that can output a steering reaction force to the steering wheel 38. The steering reaction force is output by rotating the steering shaft 40 that rotates together with the steering wheel 38. Here, the steering reaction force output from the reaction force motor 6 to the steering wheel 38 is calculated according to the tire axial force acting on the steered wheels 24 and the steering state of the steering wheel 38. This calculation is performed in a state where the clutch 8 is switched to the released state and the torque transmission path between the steering wheel 38 and the steered wheel 24 is mechanically separated. Thereby, an appropriate steering reaction force is transmitted to the driver who steers the steering wheel 38. That is, the steering reaction force output from the reaction force motor 6 to the steering wheel 38 is a reaction force acting in a direction opposite to the operation direction in which the driver steers the steering wheel 38. As the reaction force actuator, in addition to the electric motor, a power cylinder, a hydraulic circuit including a solenoid, or the like can be used.
The clutch 8 is interposed between the steering wheel 38 and the steered wheel 24 operated by the driver, and is switched to an open state or an engaged state according to a clutch command current output from the general controller 22. Note that the clutch 8 is in an open state in a normal state.

  Here, when the clutch 8 is switched to the released state, the one end side of the steering shaft 40 and the one end side of the pinion shaft 42 are separated. As a result, the torque transmission path between the steering wheel 38 and the steered wheel 24 is mechanically separated so that the steering operation of the steering wheel 38 is not transmitted to the steered wheel 24. The steering shaft 40 has one end connected to a steering clutch plate (not shown) inside the clutch 8 and the other end connected to the steering wheel 38 and rotates together with the steering wheel 38. The pinion shaft 42 has one end connected to a steered side clutch plate (not shown) inside the clutch 8 and a gear (not shown) provided on the other end is meshed with the rack gear.

On the other hand, when the clutch 8 is switched to the engaged state, one end side of the steering shaft 40 and one end side of the pinion shaft 42 are connected. As a result, the torque transmission path between the steering wheel 38 and the steered wheel 24 is mechanically connected, so that the steering operation of the steering wheel 38 is transmitted to the steered wheel 24.
The steering angle detector 10 is formed by using, for example, a rotary encoder, and is provided in a steering column (not shown) that rotatably supports the steering wheel 38.
Further, the steering angle detection unit 10 detects a current steering angle that is a current rotation angle (steering operation amount) of the steering wheel 38. Then, the steering angle detection unit 10 outputs an information signal including the detected current steering angle of the steering wheel 38 to the general controller 22.

Here, a vehicle in recent years is often provided with a sensor that can detect the steering angle of the steering wheel 38 as a standard. Therefore, in the present embodiment, a case will be described in which a sensor that can detect the steering angle of the steering wheel 38, which is an existing sensor in the vehicle, is used as the steering angle detection unit 10.
The vehicle speed detection unit 12 is, for example, a known vehicle speed sensor, detects the vehicle speed of the vehicle, and outputs an information signal including the detected vehicle speed to the general controller 22.
The yaw rate detector 14 detects the yaw rate of the vehicle, and outputs an information signal including the detected yaw rate to the general controller 22.

The first turning motor angle sensor 16 is formed using, for example, a resolver and provided in the first turning motor 2.
The first turning motor angle sensor 16 detects the rotation angle (steering angle) of the first turning motor 2. Then, the first turning motor angle sensor 16 outputs an information signal including the detected turning angle (may be described as “first turning motor rotation angle” in the following description) to the general controller 22. To do.
The first turning motor torque sensor 20 is formed using, for example, a sensor having a torsion bar, and is provided in the first turning motor 2.
The first steered motor torque sensor 20 detects first steered motor torque that is torque generated by the first steered motor 2 during driving. Then, the first turning motor torque sensor 20 outputs an information signal including the detected first turning motor torque to the general controller 22.

In the present embodiment, the first turning motor torque detected by the first turning motor torque sensor 20 is converted into steering torque that is torque applied by the driver to the steering wheel 38. And the case where the information signal containing this converted steering torque is output to the comprehensive controller 22 will be described.
The second steered motor angle sensor 18 is formed by using, for example, a resolver and provided in the second steered motor 4, similarly to the first steered motor angle sensor 16.
The second turning motor angle sensor 18 detects the rotation angle (steering angle) of the second turning motor 4. Then, the second turning motor angle sensor 18 outputs an information signal including the detected turning angle (may be described as “second turning motor rotation angle” in the following description) to the general controller 22. To do.

The integrated controller 22 inputs and outputs information signals via the first turning motor 2, the second turning motor 4, the reaction force motor 6, the clutch 8, and a communication line 44 such as CAN (Controller Area Network) or FlexRay. I do.
The general controller 22 also includes a steering angle detection unit 10, a vehicle speed detection unit 12, a yaw rate detection unit 14, a first steering motor angle sensor 16, a second steering motor angle sensor 18, The information signal output from the turning motor torque sensor 20 is received.
Further, the general controller 22 acquires the state (voltage, battery capacity, etc.) of the battery 46.

A detailed configuration of the general controller 22 and a specific process performed by the general controller 22 will be described later.
(Detailed configuration of the general controller 22)
Next, a detailed configuration of the integrated controller 22 will be described with reference to FIG. 1 and FIGS. 2 to 5.
FIG. 2 is a block diagram showing the configuration of the integrated controller 22.
As shown in FIG. 2, the general controller 22 includes a turning angle storage unit 48, a first turning motor control unit 50, a second turning motor control unit 52, a reaction force motor control unit 54, A steering angle estimation map storage unit 56 is provided. In addition to this, the integrated controller 22 includes a turning angle estimation unit 58, a travel mode setting unit 60, a clutch state switching unit 62, and a driving support function control unit 64.
The steered angle storage unit 48 includes the first steered motor 2 and the second steered motor in a state where both the steered angle of the steering wheel 38 and the actual steered angle of the steered wheel 24 are adjusted to the neutral position: 0 [°]. The rotation angle of 4 is stored.

  Here, the process which memorize | stores the rotation angle of the 1st steering motor 2 and the 2nd steering motor 4 is performed in the adjustment process etc. which are performed at the time of manufacture of a vehicle, or before shipment of a vehicle, for example. The rotation angles of the first steering motor 2 and the second steering motor 4 in a state where both the steering angle of the steering wheel 38 and the actual steering angle of the steered wheels 24 are adjusted to the neutral position are the first to the steering angle. It is a deviation of one turning motor rotation angle and the first turning motor rotation angle. Further, the deviation of the first turning motor rotation angle and the first turning motor rotation angle with respect to the steering angle is represented by a deviation angle [deg], for example.

  In the present embodiment, as an example, the rotation angle of the first turning motor 2 in a state where both the steering angle of the steering wheel 38 and the actual turning angle of the steered wheels 24 are adjusted to the neutral position is set to the first turning angle with respect to the steering angle. The case where the deviation of the rudder motor rotation angle is set to 0 [°] will be described. Similarly, when the steering angle of the steering wheel 38 and the actual turning angle of the steered wheels 24 are both adjusted to the neutral position, the rotational angle of the second steered motor 4 is set to the second steered motor rotational angle relative to the steered angle. A case where the deviation is 0 [°] will be described.

The steered angle storage unit 48 stores the steered steering angle, the first steered motor rotation angle, and the second steered motor according to the steered angle of the steered wheels 24 estimated by the steered angle estimating unit 58. Processing to correct (overwrite) the relationship with the rotation angle is performed. For example, when the turning angle of the steered wheels 24 estimated by the turning angle estimation unit 58 is 10 [°] in the clockwise direction (the direction in which the vehicle turns to the right), the steering motor with respect to the steering angle is processed. This is a process of correcting (overwriting) the rotation angle deviation counterclockwise to 10 [°].
The first turning motor control unit 50 calculates a first turning motor driving current for driving the first turning motor 2, and uses the calculated first turning motor driving current as the first turning motor 2. Output to.

  Here, the first turning motor drive current controls the first turning torque described above to calculate a target turning angle corresponding to the operation of the steering wheel 38, and according to the calculated target turning angle. This is a current for driving and controlling the first turning motor 2. In addition, the first turning motor drive current includes the command value of the current actually energized to the first turning motor 2 and the rotation angle of the first turning motor 2 stored in the turning angle storage unit 48. Is used to correct and calculate the steering motor current command.

  Further, the first steered motor control unit 50 estimates the temperature of the first steered motor 2 based on the command value of the current that is actually energized to the first steered motor 2. Further, an information signal including the estimated temperature of the first steering motor 2 is output to the travel mode setting unit 60. This is to estimate overheating of the first steered motor 2 due to resistance heat generation due to current application. The command value of the current that is actually energized to the first turning motor 2 is, for example, a substrate temperature sensor (not shown) built into the first turning motor 2, and this built-in substrate temperature sensor is used. To measure.

The second steered motor control unit 52 computes a second steered motor drive current for driving the second steered motor 4, and uses the computed second steered motor drive current as the second steered motor 4. Output to.
Here, the second turning motor drive current controls the second turning torque described above to calculate a target turning angle according to the operation of the steering wheel 38, and according to the calculated target turning angle. This is a current for driving and controlling the second steered motor 4. Further, the second turning motor drive current includes the command value of the current actually energized to the second turning motor 4 and the rotation angle of the second turning motor 4 stored in the turning angle storage unit 48. Is used to correct and calculate the steering motor current command.

The second steered motor control unit 52 is similar to the first steered motor control unit 50 based on the command value of the current that is actually energized to the second steered motor 4. Estimate the temperature. Further, an information signal including the estimated temperature of the second turning motor 4 is output to the travel mode setting unit 60.
The reaction force motor control unit 54 calculates a reaction force motor drive current for driving the reaction force motor 6, and outputs the calculated reaction force motor drive current to the reaction force motor 6. Here, the calculation of the reaction force motor drive current is performed based on the value of the current that is actually energized to the reaction force motor 6.

Similarly to the first turning motor control unit 50, the reaction force motor control unit 54 estimates the temperature of the reaction force motor 6 based on the value of the current that is actually energized to the reaction force motor 6. Further, an information signal including the estimated temperature of the reaction force motor 6 is output to the travel mode setting unit 60.
The turning angle estimation map storage unit 56 stores a map for estimating the turning angle of the steered wheels 24 based on the amount of operation of the steering wheel 38 by the driver and the speed (vehicle speed) of the vehicle. .

Here, the maps stored in the turning angle estimation map storage unit 56 are the turning angle estimation map shown in FIG. 3 and the limit angle setting map shown in FIG. 4. FIG. 3 is a diagram showing a steered angle estimation map, and FIG. 4 is a diagram showing a limit angle setting map.
As shown in FIG. 3, the turning angle estimation map is a map in which the horizontal axis indicates the steering angle and the vertical axis indicates the turning angle. The turning angle estimation map stores the degree of change in the turning angle according to the change in the steering angle in accordance with the preset vehicle speed, as indicated by a straight line rising to the right in the figure.

Here, the degree of change indicated by a straight line that rises to the right in the turning angle estimation map is such that when the vehicle speed is 0 [km / h], the amount of change in the turning angle with respect to the change in the steering angle is maximum. The change degree indicating a straight line right up in the steering angle estimation map, as the vehicle speed is changed to V ₃ from 0 [km / h], the amount of change in the steering angle with respect to a change in the steering angle is reduced . Incidentally, the magnitude relationship of _{V 3} from vehicle speeds _{V 1} to shown in the steering angle estimation map is a _"V 1 _<V 2 _{<V 3".} In other words, the degree of change indicated by a straight line rising to the right in the turning angle estimation map decreases as the vehicle speed increases.

  As shown in FIG. 4, the limit angle setting map is a map showing the turning angle on the horizontal axis. In the limit angle setting map, the end contact angle (for example, 500 [deg]), which is the turning limit angle from the neutral position of the turning wheel 24, is shown on the vertical axis. Therefore, as shown in the drawing, when the turning angle increases and reaches the end contact angle, the turning angle of the steered wheels 24 reaches a limit angle that is an upper limit value.

Here, the end contact angle is a limit turning angle at which the steered wheels 24 can be steered, and is set in advance, for example, at the time of vehicle design, manufacture, and factory shipment. That is, in a state where the turning angle of the steered wheels 24 has reached the end contact angle, even if the steering wheel 38 is steered, the steered angle of the steered wheels 24 does not change (increase).
The turning angle estimation unit 58 receives input of information signals output from the steering angle detection unit 10, the vehicle speed detection unit 12, the first turning motor angle sensor 16, and the second turning motor angle sensor 18. Further, the turning angle estimation unit 58 detects the voltage of the battery 46. In addition, the turning angle estimation map and the limit angle setting map stored in the turning angle estimation map storage unit 56 are referred to.

Then, when the voltage of the battery 46 becomes less than a preset voltage threshold value or more than the voltage threshold value, the current steering angle detected by the steering angle detection unit 10 and the vehicle speed detected by the vehicle speed detection unit 12 are displayed in the turning angle estimation map. input. Thereby, the turning angle of the steered wheels 24 according to the current steering angle and the vehicle speed is estimated. At this time, when the estimated turning angle exceeds the limit angle shown in the limit angle setting map, the turning angle estimated according to the current steering angle and the vehicle speed is corrected to the limit angle.
Here, the voltage threshold is a voltage at which the reading state of the rotation angles of the first turning motor 2 and the second turning motor 4 stored in the turning angle storage unit 48 becomes abnormal. That is, the voltage threshold is a voltage at which SBW control and control of a driving support function described later cannot be performed.

That is, when the voltage of the battery 46 is less than the voltage threshold value to the voltage threshold value or more, the turning angle estimation unit 58 is based on the current steering angle detected by the steering angle detection unit 10 and the vehicle speed detected by the vehicle speed detection unit 12. The turning angle of the steered wheels 24 is estimated.
For example, the travel mode setting unit 60 may include a result of processing performed by the first turning motor control unit 50, the second turning motor control unit 52, and the reaction force motor control unit 54, the first turning motor 2, and the second turning motor control unit 54. Based on the state of the rudder motor 4 and the reaction force motor 6, the vehicle travel mode is set. In addition to this, the travel mode setting unit 60 is configured to drive the vehicle according to the read state of the rotation angles of the first turning motor 2 and the second turning motor 4 stored in the turning angle storage unit 48, for example. Set the mode.

  Specifically, as shown in FIG. 5, the diagnosis results of the first turning motor control unit 50, the second turning motor control unit 52, and the reaction force motor control unit 54, and the reading state of the rotation angle are all normal. If it is (indicated by “◯” in the figure), the traveling mode is set to normal SBW control. The normal SBW control is SBW control using the first steered motor 2, the second steered motor 4 and the reaction force motor 6 (shown as "2M-SBW" in the figure). FIG. 5 is a diagram illustrating a table used by the travel mode setting unit 60 for setting the travel mode.

  Further, as shown in FIG. 5, the rotation angle reading state is abnormal (indicated by “x” in the drawing), that is, the rotation angle stored in the turning angle storage unit 48 cannot be read. Then, the traveling mode is set to Tmp-EPS control. The Tmp-EPS control is an EPS control using the first steered motor 2, the second steered motor 4 and the reaction force motor 6 (shown as “Tmp-EPS (2M-EPS)” in the drawing). Yes, it is an EPS control that is temporarily performed.

In FIG. 5, the EPS control using at least the first steering motor 2 without using all the motors among the first steering motor 2, the second steering motor 4, and the reaction force motor 6, Shown as “1M-EPS”. Moreover, in FIG. 5, SBW control using the 2nd steering motor 4 and the reaction force motor 6 is shown as 1M-SBW. In FIG. 5, the traveling mode in which the steered wheels 24 are steered by the steering operation of the steering wheel 38 by the driver with the clutch 8 engaged without using all the motors is indicated as “MS”. .
The clutch state switching unit 62 switches the state of the clutch 8 based on the state of the ignition switch of the vehicle, the travel mode set by the travel mode setting unit 60, and the voltage of the battery 46.

Specifically, when the ignition switch is in the on state, a clutch current command for switching the clutch 8 to the released state is output to the clutch 8. Further, when the traveling mode setting unit 60 sets the traveling mode to “2M-SBW” or “1M-SBW”, a clutch current command for switching the clutch 8 to the released state is output to the clutch 8. The determination that the ignition switch is on is not limited to when the engine is operating. In this case, when it is detected that the ignition switch has been operated by the driver or the like, it may be determined that the ignition switch is on even if the engine is stopped. The same applies to the following description. Further, even when the engine is stopped, the ignition switch of the vehicle is in the on state, for example, when the operation position of the ignition switch is ACC (accessory position).
Further, when the ignition switch is in the ON state, if the voltage of the battery 46 becomes less than the voltage threshold value, a clutch current command for switching the clutch 8 in the released state to the engaged state is output to the clutch 8.

When the voltage that is less than the voltage threshold becomes equal to or greater than the voltage threshold, a clutch current command for switching the engaged clutch 8 to the released state is output to the clutch 8 in accordance with the running state of the vehicle. In addition, the process which switches the clutch 8 of a fastening state to an open state according to the driving | running | working state of a vehicle in the state in which the voltage which became less than a voltage threshold became more than a voltage threshold value is mentioned later.
On the other hand, when the ignition switch is in the OFF state, a clutch current command for switching the clutch 8 to the engaged state is output to the clutch 8. Further, when the traveling mode setting unit 60 sets the traveling mode to any one of “Tmp-EPS (2M-EPS)”, “1M-EPS”, and “MS”, the clutch 8 is switched to the disengaged state. A clutch current command is output to the clutch 8.

The driving support function control unit 64 performs processing for controlling the steering state, braking force, driving force, and the like of the vehicle in order to perform driving support functions such as ABS control, VDC control, and in-lane travel maintenance support control. Here, the ABS (Antilock Break System) control is control for preventing the wheels from being locked, and the VDC (Vehicle Dynamics Control) control is control for suppressing the side slip of the vehicle. The in-lane travel maintenance support control is control that suppresses a vehicle traveling in the lane from deviating outside the lane.
The driving support function control unit 64 uses the turning angle estimated by the turning angle estimation unit 58 in order to perform the various driving support functions described above.

  Further, when the driving support function control unit 64 receives an input of the turning angle correction flag from the traveling mode setting unit 60, the driving support function control unit 64 uses the turning angle estimated by the turning angle estimation unit 58 as a temporary turning angle. Carry out driving support functions. This is because, for example, in the VDC control or the like, compared with the case where the turning angle estimated by the turning angle estimation unit 58 is used as a normal turning angle, the importance of the turning angle is set to other parameters (vehicle speed). Etc.) is a process of lowering the importance.

Further, the turning angle correction flag presumes a new turning angle when the turning angle estimated at the time when the ignition switch was previously turned off cannot be stored in the turning angle storage unit 48. It is a flag indicating the state. The case where the previously estimated turning angle cannot be stored in the turning angle storage unit 48 is a case where power supply from the battery 46 to the general controller 22 (ECU) is interrupted in a state outside the control target. is there.
Here, the case where the power supply from the battery 46 to the general controller 22 is interrupted in a state outside the control target is, for example, an instantaneous voltage drop (instantaneous low) of the battery or disconnection of the cable from the battery terminal. Etc. In this state, if the supply of power to the general controller 22 is interrupted in a state outside the control target, there may be a problem that the SBW control cannot be performed.

(Specific processing performed by the general controller 22)
Next, specific processing performed by the integrated controller 22 will be described with reference to FIGS. 1 to 5 and FIGS. 6 and 7.
FIG. 6 is a flowchart showing processing performed by the integrated controller 22.
As shown in FIG. 6, the process performed by the integrated controller 22 is started when the ignition switch in the off state is switched to the on state or when the voltage of the battery 46 becomes equal to or higher than the voltage threshold after being lower than the voltage threshold (START). To do.

When the process performed by the integrated controller 22 is started, first, in step S100, a process of reading the rotation angle stored in the turning angle storage unit 48 ("stored turning angle reading" shown in the drawing) is performed. In step S100, when the rotation angle stored in the turning angle storage unit 48 is read, the process performed by the integrated controller 22 proceeds to step S102.
In step S102, a process of determining whether or not the process performed in step S100, that is, the process of reading the rotation angle stored in the turning angle storage unit 48 has been normally performed ("Read OK?"")I do.
If it is determined in step S102 that the process of reading the rotation angle stored in the steered angle storage unit 48 has been performed normally ("Yes" shown in the figure), the process performed by the integrated controller 22 is performed in step S104. Migrate to

On the other hand, if it is determined in step S102 that the process of reading the rotation angle stored in the turning angle storage unit 48 has not been performed normally ("No" shown in the figure), the process performed by the integrated controller 22 is as follows. The process proceeds to step S106.
In step S104, the turning angle estimation unit 58 performs processing for estimating the turning angle of the steered wheels 24 ("steering angle estimation" shown in the figure). If the process which estimates the turning angle of the steered wheel 24 is performed in step S104, the process which the comprehensive controller 22 will transfer to step S108.

In step S106, as in step S104, the turning angle estimation unit 58 performs processing for estimating the turning angle of the steered wheels 24 ("steering angle estimation" shown in the figure). If the process which estimates the turning angle of the steered wheel 24 is performed in step S106, the process which the comprehensive controller 22 performs will transfer to step S114.
In step S108, the process performed in step S104, that is, the process for determining whether or not the steered angle estimating unit 58 has performed the process of estimating the steered angle of the steered wheels 24 (" Rudder angle estimation OK? ”).
If it is determined in step S108 that the process of estimating the turning angle has been performed normally ("Yes" shown in the figure), the process performed by the integrated controller 22 proceeds to step S110.

  On the other hand, if it is determined in step S108 that the process of estimating the turning angle is not performed normally ("No" shown in the figure), the process performed by the integrated controller 22 proceeds to step S112. Here, the case where the process of estimating the turning angle is not normally performed includes, for example, the steering angle detection unit 10, the vehicle speed detection unit 12, the first turning motor angle sensor 16, and the second turning motor angle sensor. This is a case where any one of 18 is out of order. Further, the case where the process of estimating the turning angle is not normally performed is, for example, any of the first turning motor control unit 50, the second turning motor control unit 52, and the reaction force motor control unit 54. It may include a case in which there is a failure (calculation failure).

In step S110, the travel mode setting unit 60 performs processing for setting the travel mode of the vehicle to “2M-SBW” or “1M-SBW” (“shift to SBW control” shown in the figure). In step S110, when the travel mode of the vehicle is set to “2M-SBW” or “1M-SBW”, the process performed by the integrated controller 22 ends (END).
In step S112, the travel mode setting unit 60 performs a process of setting the travel mode of the vehicle to “1M-EPS” (“shift to 1M-EPS control” shown in the figure). In step S112, when the vehicle travel mode is set to “1M-EPS”, the processing performed by the integrated controller 22 ends (END).

In step S114, the process performed in step S106, that is, the process for determining whether or not the steered angle estimating unit 58 has performed the process of estimating the steered angle of the steered wheels 24 normally (the “turning” shown in the figure). Rudder angle estimation OK? ”).
If it is determined in step S114 that the process of estimating the turning angle has been performed normally ("Yes" shown in the figure), the process performed by the integrated controller 22 proceeds to step S116.

On the other hand, if it is determined in step S114 that the process of estimating the turning angle is not performed normally ("No" shown in the figure), the process performed by the integrated controller 22 proceeds to step S112. Here, the case where the process of estimating the turning angle is not normally performed is the same as the process performed in step S108 described above.
In step S116, the travel mode setting unit 60 performs processing for setting the travel mode of the vehicle to “Tmp-EPS” (“transition to Tmp-EPS control” shown in the figure). In addition, in step S116, a process of transmitting a turning angle correction flag to the driving support function control unit 64 ("transmission angle correction flag transmission" shown in the figure) is performed. In step S116, when the vehicle travel mode is set to “Tmp-EPS” and the turning angle correcting flag is transmitted to the driving support function control unit 64, the processing performed by the integrated controller 22 proceeds to step S118.

In step S118, it is determined whether or not the following three conditions C1 to C3 are all satisfied, thereby determining whether or not the vehicle is traveling straight (“straight line determination condition satisfied?” Shown in the figure). )I do.
C1. The vehicle speed detected by the vehicle speed detection unit 12 is equal to or greater than a preset vehicle speed threshold. In the present embodiment, as an example, a case where the vehicle speed threshold is set to 40 [km / h] will be described.
C2. The absolute value of the vehicle yaw rate detected by the yaw rate detection unit 14 is equal to or less than a preset yaw rate threshold. In the present embodiment, as an example, a case where the yaw rate threshold is set to 0.2 [deg / s] will be described.
C3. The absolute value of the steering angular velocity based on the amount of change per unit time of the current steering angle detected by the steering angle detector 10 is equal to or less than a preset straight steering determination steering angular velocity threshold. In the present embodiment, as an example, a case where the straight traveling determination steering angular velocity threshold is set to 20 [deg / s] will be described.

In addition, said conditions C1-C3 are preset and memorize | stored in the comprehensive controller 22, for example.
In step S118, when it is determined that all the above three conditions C1 to C3 are satisfied and it is determined that the vehicle is traveling straight ("Yes" shown in the drawing), the process performed by the integrated controller 22 is as follows. The process proceeds to S120.
On the other hand, if it is determined in step S118 that at least one of the three conditions C1 to C3 described above is not established and it is determined that the vehicle is not traveling straight ("No" shown in the figure), the general controller 22 The process to be performed repeats the process of step S118.

  In step S120, a process ("timer count UP" shown in the figure) for measuring the time during which the state where it is determined that the vehicle is traveling straight is continued. If the process which measures the time which the state determined that the vehicle is moving straight in step S120 is continued, the process which the comprehensive controller 22 will transfer to step S122.

In step S122, a process of determining whether or not the time when the measurement is started in the process of step S120 and the state in which it is determined that the vehicle is traveling straight is continued is equal to or greater than a preset straight traveling determination time threshold ( “UP ≧ 1000 ms?” Shown in the figure. In the present embodiment, as an example, a case where the straight traveling determination time threshold is set to 1000 [ms] will be described.
In step S122, when it is determined that the time during which the state where the vehicle is determined to be traveling straight is longer than or equal to the straight traveling determination time threshold ("Yes" shown in the drawing), the processing performed by the integrated controller 22 is as follows. The process proceeds to step S124.

On the other hand, if it is determined in step S122 that the time during which the state in which it is determined that the vehicle is traveling straight continues is less than the straight traveling determination time threshold ("No" shown in the figure), the process performed by the integrated controller 22 Proceeds to step S118.
In step S124, the steered angle estimating unit 58 performs a process of estimating the steered angle of the steered wheels 24.

Here, in step S124, unlike the above-described steps S104 and S106, the steered wheels 24 are in a state where the vehicle is traveling straight, that is, in a state where the steering angle and the turning angle are in the neutral position or in the vicinity of the neutral position. The process which estimates the steering angle of will be performed.
Therefore, in step S124, the steering angle in a state where both the steering angle of the steering wheel 38 and the actual turning angle of the steered wheels 24 are adjusted to the neutral position: 0 [°], that is, a process for estimating a correct turning angle ( "Estimate correct steering angle") shown in the figure. If the process which estimates the turning angle of the steered wheel 24 is performed in step S124, the process which the comprehensive controller 22 will transfer to step S126.

  Here, the “correct steering angle” refers to, for example, the steering angle estimated in the subsequent processing when the steering angle at the time when it is determined in step S118 that the vehicle is traveling straight is estimated to be 3 [°]. This is an angle obtained by subtracting 3 [°] from the rudder angle. This is because the steering angle of the steering wheel 38 and the actual turning angle of the steered wheel 24 are both in the neutral position: 0 [°] when the vehicle is traveling straight. In addition, the angle displaced from 0 [°] while the vehicle is traveling straight is generated by, for example, an error in calculation processing, the engagement of the clutch 8, and the twist of the shaft constituting the torque transmission path. The reason is that the angle deviation is.

  In step S126, it is determined whether or not the vehicle is stopped in a state where the steering wheel 38 is not steered by determining whether or not the following three conditions C4 to C6 are all satisfied (FIG. "Non-steering stop condition established?") In the following description, a state where the steering wheel 38 is not steered may be referred to as a “non-steering state”.

C4. The vehicle speed detected by the vehicle speed detection unit 12 is 0 [km / h].
C5. The absolute value of the steering angular velocity based on the amount of change per unit time of the current steering angle detected by the steering angle detection unit 10 is equal to or less than a preset steering angular velocity threshold for non-steer determination. In this embodiment, as an example, a case where the steering angular velocity threshold for non-steer determination is set to 10 [deg / s] will be described.
C6. The absolute value of the first steered motor torque detected by the first steered motor torque sensor 20 is not more than a preset non-steering determination torque threshold. In the present embodiment, as an example, a case where the non-steering determination torque threshold is set to 1 [Nm] will be described.

Note that the above conditions C4 to C6 are set in advance and stored in the general controller 22, for example. Further, the state in which the above conditions C5 and C6 are satisfied corresponds to a preset non-steering state.
When it is determined in step S126 that the vehicle is stopped in the non-steering state (“Yes” shown in the drawing), the process performed by the integrated controller 22 proceeds to step S128. This is a case where it is determined that all the above three conditions C4 to C6 are satisfied.

On the other hand, if it is determined in step S126 that at least one of the non-steering condition and the vehicle stopping condition is not satisfied ("No" shown in the drawing), the process performed by the integrated controller 22 is as follows. The process of step S126 is repeated. This is a case where it is determined that at least one of the above three conditions C4 to C6 is not satisfied.
In step S128, a process ("timer count UP" shown in the drawing) for measuring the time during which the state in which it is determined that the vehicle is stopped in the non-steering state is continued is performed. If the process which measures the time which the state determined that the vehicle has stopped in the non-steering state in step S128 is performed, the process which the comprehensive controller 22 will transfer to step S130.

In step S130, whether or not the time during which measurement is started in the process of step S128 and the state in which the vehicle is stopped in the non-steering state continues is equal to or greater than a preset non-steering stop determination time threshold value. Is performed (“UP ≧ 1000 ms?” Shown in the figure). In the present embodiment, as an example, a case where the non-steer stop determination time threshold is set to 1000 [ms] will be described.
In step S130, when it is determined that the time during which the state in which the vehicle is stopped in the non-steering state is continued is equal to or greater than the non-steering stop determination time threshold ("Yes" shown in the figure), the overall controller The process performed by 22 proceeds to step S132.

On the other hand, when it is determined in step S130 that the time during which it is determined that the vehicle is stopped in the non-steering state is less than the non-steering stop determination time threshold ("No" shown in the drawing), The process performed by the integrated controller 22 proceeds to step S126.
In step S132, using the correct turning angle estimated in step S124, the relationship between the steering angle stored in the turning angle storage unit 48, the first turning motor rotation angle, and the first turning motor rotation angle is determined. Perform correction (overwriting). Thereby, in step S132, the steering motor rotation angle with respect to the steering angle stored in the steering angle storage unit 48 is updated using the correct steering angle estimated in step S124 ("correct" shown in the figure). Update to steered angle ").

If the process which updates the steering motor rotation angle with respect to the steering angle memorize | stored in the steering angle memory | storage part 48 in step S132 is performed, the process which the comprehensive controller 22 will transfer to step S134.
In step S134, as in step S110, the travel mode setting unit 60 sets the vehicle travel mode to "2M-SBW" or "1M-SBW"("shift to SBW control" shown in the figure). Do.

In addition, in step S134, a process of transmitting an information signal including the estimated correct turning angle to the driving support function control unit 64 ("transmit turning angle information" shown in the figure) is performed. Accordingly, transmission of the turning angle correction flag to the driving support function control unit 64 is stopped.
Here, in the present embodiment, in step S134, after setting the vehicle travel mode to “2M-SBW” or “1M-SBW”, when the clutch 8 is switched to the released state, the estimated correct turning angle is estimated. Is transmitted to the driving support function control unit 64. That is, in the present embodiment, as shown in FIG. 7, when the vehicle travel mode is switched from “Tmp-EPS” to “2M-SBW” or “1M-SBW”, the turning angle estimation unit 58 The information on the turning angle estimated by is switched from the temporary turning angle to the correct turning angle. FIG. 7 is a time chart showing processing performed between step S126 and step S134 among the processing performed by the integrated controller 22.

Therefore, when the process performed by the integrated controller 22 proceeds to step S134, SBW control can be performed based on the correct turning angle estimated in step S124.
In step S134, when the vehicle traveling mode is set to “2M-SBW” or “1M-SBW” and the correct turning angle is transmitted to the driving support function control unit 64, the processing performed by the integrated controller 22 Ends (END).

(Operation)
Next, an example of an operation performed using the vehicle steering control device 1 of the present embodiment will be described with reference to FIGS. 1 to 7 and FIG. FIG. 8 is a time chart showing the operation of the vehicle using the vehicle steering control device 1 of the present embodiment.
The time chart shown in FIG. 8 shows a state in which the ignition switch is on, such as when the vehicle is traveling, the torque transmission path is mechanically separated, and the vehicle traveling mode is set to “2M-SBW” ( The process starts from “SBW control in progress” shown in the figure. In the state in which the vehicle travel mode is set to “2M-SBW” or “1M-SBW”, for example, control for reducing the degree of change in the turning angle with respect to the steering angle during high-speed travel compared to during low-speed travel ( (Variable gear control), etc., to control the turning angle according to the vehicle speed. Further, the control of the turning angle according to the vehicle speed is performed by the relationship between the steering angle stored in the turning angle storage unit 48 and the turning motor rotation angle, the current steering angle detected by the steering angle detection unit 10, and the vehicle speed detection. The vehicle speed detected by the unit 12 is used.

Then, for example, after the vehicle is parked, from the time t1 when the driver switches the ignition switch to the off state ("IGN OFF" in the figure), the processing at the end of the SBW control ("end time" shown in the figure) Process ”).
Here, the process at the end of the SBW control includes a process of switching the clutch 8 from the disengaged state to the engaged state (“clutch engagement” shown in the figure) and a process of estimating the steered angle of the steered wheels 24 at the time point t1 ( It is “steering angle estimation”) shown in the figure. The process at the end of the SBW control is a process of writing and storing the steered angle of the steered wheels 24 at the estimated time t1 in the steered angle storage unit 48 ("steering angle writing" shown in the figure). In the drawing, the time point when the process at the end of the SBW control is ended is indicated as a time point t2.

After the time point t2, for example, when the driver switches the ignition switch to an on state ("IGN ON" shown in the figure), such as when the vehicle starts, the process at the time of starting the SBW control (in the figure) "Processing at startup").
Here, the process at the time of starting the SBW control is a process of switching the clutch 8 from the engaged state to the released state (“clutch release” shown in the drawing). In addition to this, the process at the time of starting the SBW control is a process of reading the turning angle of the steered wheels 24 written and stored in the turning angle storage unit 48 in the process at the end of the SBW control ("steering shown in the figure" Corner reading ").

Then, from the time t4 when the process at the time of starting the SBW control is completed, the vehicle travel mode is set to “2M-SBW” and the SBW control is started (“SBW control in progress” shown in the figure).
Here, in a state where the vehicle travel mode is set to “2M-SBW”, it is determined whether or not to activate the SBW control when the voltage of the battery 46 becomes equal to or higher than the voltage threshold after being lower than the voltage threshold. Processing (“SBW control activation determination” shown in the figure) is performed. In the figure, the time point when the voltage of the battery 46 becomes less than the voltage threshold ("voltage drop" shown in the figure) is indicated as time point t5. Further, in the figure, a process of determining whether or not to activate the SBW control at the time when the voltage of the battery 46 that has become less than the voltage threshold becomes equal to or higher than the voltage threshold ("voltage restoration" shown in the figure) The starting time is indicated as time t6.

In the process of determining whether or not to activate the SBW control, it is determined whether or not the process of step S102 described above, that is, the process of reading the rotation angle stored in the turning angle storage unit 48 has been performed normally. Perform the process.
Here, in the following description, a case where it is determined that the process of reading the rotation angle stored in the turning angle storage unit 48 has not been performed normally will be described. That is, in the following description, a case where the process proceeds from step S102 to step S106 described above will be described.

After determining that the process of reading the rotation angle stored in the steered angle storage unit 48 has not been performed normally, the process of step S114 described above, that is, the steered angle estimating unit 58 performs the turning of the steered wheels 24. Processing for determining whether or not the processing for estimating the steering angle has been performed normally is performed.
Here, the following description will be given of a case where the turning angle estimation unit 58 determines that the process of estimating the turning angle of the steered wheels 24 has been performed normally. That is, in the following description, a case where the process proceeds from step S114 to step S116 described above will be described.

From the time t7 when the process of reading the rotation angle stored in the steered angle storage unit 48 is not normally performed and the process of estimating the steered angle of the steered wheels 24 is normally performed by the steered angle estimating unit 58, The vehicle travel mode is set to “Tmp-EPS”. Thereby, Tmp-EPS control is started from time t7 ("Tmp-EPS control in progress" shown in the figure).
When the time during which the Tmp-EPS control is started and the state in which it is determined that the vehicle is traveling straight is longer than or equal to the straight traveling determination time threshold, a correct turning angle is estimated (see steps S118 to S124). If the time during which the vehicle is stopped in the non-steering state is longer than the non-steering stop determination time threshold, the estimated correct turning angle is stored in the turning angle storage unit 48. The turning motor rotation angle with respect to the steering angle is updated (see steps S126 to S132).

  When the steered motor rotation angle with respect to the steering angle stored in the steered angle storage unit 48 is updated using the estimated correct steered angle, the traveling mode of the vehicle is set to “2M-SBW” at this time t8. To do. Then, the process of switching the clutch 8 from the engaged state to the released state is performed, and the steering motor rotation angle with respect to the steering angle stored in the steering angle storage unit 48 is updated using the estimated correct steering angle. , SBW control is started ("SBW control in progress" shown in the figure). Specifically, the steering with respect to the steering angle stored in the turning angle storage unit 48 updated by using the correct turning angle by the first turning motor control unit 50 and the second turning motor control unit 52. The target turning angle described above is calculated using the motor rotation angle.

That is, when the clutch 8 is switched to the disengaged state, the first turning motor control unit 50 and the second turning motor control unit 52 estimate that the turning angle estimation unit 58 estimates that the traveling state of the vehicle is straight. The target turning angle is calculated using the turning angle.
Furthermore, at time t8, an information signal including the estimated correct turning angle is transmitted to the driving support function control unit 64 (see step S134).
That is, when the driving support function control unit 64 switches the clutch 8 from the released state to the engaged state, the driving angle estimation unit 58 uses the turning angle estimated immediately before the opened clutch 8 switches to the engaged state, Control driving support functions. Further, when the clutch 8 is switched from the engaged state to the released state, the turning angle estimated by the turning angle estimation unit 58 when the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the vehicle traveling state is determined to be straight traveling. Is used to control the driving support function.

As described above, in the vehicle steering control device 1 of the present embodiment, the driving support function control unit outputs the information signal including the correct turning angle at the time t8 when the clutch 8 is switched from the engaged state to the released state and the SBW control is started. 64. That is, at the time t8, the turning angle included in the information signal transmitted to the driving support function control unit 64 is switched from the temporary turning angle to the correct turning angle (see FIG. 7).
For this reason, the control of the driving support function using the correct turning angle from the time point t8 when the SBW control is started, in the state where the driving support function such as the VDC control described above is controlled using the temporary turning angle. It is possible to shift to a state in which

Therefore, even when the turning angle stored in the turning angle storage unit 48 cannot be read, the turning estimated with high estimation accuracy from the time when the clutch 8 in the engaged state is switched to the released state. SBW control and driving support function control can be performed using the corners.
Note that, among the above-described integrated controller 22, the first turning motor control unit 50 and the second turning motor control unit 52 correspond to a target turning angle calculation unit.

In addition, among the above-described integrated controller 22 and the processes performed by the integrated controller 22, specifically, the processes performed by the integrated controller 22, the processes from step S118 to step S122 correspond to the straight traveling determination unit.
In addition, among the above-described integrated controller 22 and the processes performed by the integrated controller 22, specifically, the processes performed by the integrated controller 22, the processes from step S126 to step S130 correspond to the non-steer stop state determination unit.
The first turning motor torque sensor 20 described above corresponds to a steering torque detector.

  As described above, in the vehicle steering control method implemented by the operation of the vehicle steering control device 1 of the present embodiment, when the ignition switch is on and the voltage of the battery 46 becomes less than the voltage threshold, the clutch 8 Is switched from the open state to the fastened state. In addition, the driving support function is controlled using the turning angle estimated immediately before the clutch 8 in the released state is switched to the engaged state. On the other hand, when the clutch 8 is switched from the engaged state to the released state, the driving support function is performed using the steering angle estimated when the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the vehicle traveling state is determined to be straight. To control.

(Effects of the first embodiment)
In the present embodiment, the following effects can be obtained.
(1) When the driving support function control unit 64 switches the clutch 8 from the released state to the engaged state, the turning angle estimated by the turning angle estimating unit 58 immediately before the released clutch 8 is switched to the engaged state is used. Control driving support functions. In addition to this, when the clutch 8 is switched from the engaged state to the released state, the voltage less than the voltage threshold becomes equal to or higher than the voltage threshold, and the turning angle estimation unit 58 estimates when the vehicle traveling state is determined to be straight. The driving support function is controlled using the steering angle.

For this reason, when the clutch 8 is switched from the engaged state to the released state, the driving assistance is performed using the steering angle estimated when the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the vehicle traveling state is determined to be straight. The function can be controlled.
As a result, even when the stored turning angle stored in the turning angle storage unit 48 cannot be read, the estimation accuracy is high since the clutch 8 is switched from the engaged state to the released state. It is possible to control the driving support function using the steering angle estimated in (1).

(2) For the clutch 8 in the engaged state, it is determined that the voltage less than the voltage threshold is equal to or greater than the voltage threshold, the vehicle traveling state is straight, and further, the non-steering state and the vehicle are stopped are determined. If established, switch to the open state. Further, the first turning motor control unit 50 and the second turning motor control unit 52 determine that when the clutch 8 in the engaged state is switched to the released state, the voltage becomes equal to or higher than the voltage threshold value, and the traveling state of the vehicle is straight ahead. After that, the target turning angle is calculated using the turning angle estimated by the turning angle estimation unit 58.

For this reason, when the clutch 8 in the engaged state is switched to the released state, it is possible to perform SBW control using the steered angle estimated after determining that the traveling state of the vehicle is straight.
As a result, even when the stored turning angle stored in the turning angle storage unit 48 cannot be read, the estimation accuracy is high since the clutch 8 in the engaged state is switched to the released state. SBW control can be performed using the steered angle estimated in step (1).

(3) When the vehicle speed is equal to or greater than the vehicle speed threshold, the absolute value of the vehicle yaw rate is equal to or less than the yaw rate threshold, and the absolute value of the steering angular velocity is equal to or less than the steering angular velocity threshold for straight travel determination, Judge that there is.
Therefore, it is possible to determine the timing for estimating the correct turning angle used for controlling the SBW control and the driving support function in accordance with the speed and yaw rate of the vehicle and the steering state of the steering wheel 38. .
As a result, the SBW control and the driving support function are performed using the turning angle estimated at a timing according to the speed and yaw rate of the vehicle and the steering state of the steering wheel 38 and estimated with a high estimation accuracy. Can be controlled.

(4) The state where the vehicle speed is equal to or greater than the vehicle speed threshold, the absolute value of the vehicle yaw rate is equal to or less than the yaw rate threshold, and the absolute value of the steering angular velocity is equal to or less than the steering angular velocity threshold for straight travel determination continues until the straight travel determination time threshold. Then, it is determined that the traveling state of the vehicle is straight.
For this reason, it is possible to estimate a correct turning angle used for controlling the SBW control and the driving support function when the state in which the traveling state of the vehicle is determined to be straight continues stably.

  As a result, the SBW control is performed using the turning angle estimated in a state in which the state in which the traveling state of the vehicle is determined to be straight is stably continued and the estimation angle is estimated with high estimation accuracy. And driving support functions can be controlled. As a result, SBW control and control of the driving support function can be performed with higher accuracy than when the steered angle estimated at the time when the traveling state of the vehicle is determined to be straight traveling is used.

(5) If the vehicle speed is 0 [km / h], it is determined that the vehicle is in a non-steering state, the absolute value of the steering angular velocity is equal to or less than the steering angular velocity threshold for non-steering determination, and the absolute value of the steering torque Is less than or equal to the non-steering determination torque threshold, it is determined that the vehicle is stopped.
For this reason, the clutch 8 in the engaged state is switched to the released state, and the determination of switching the vehicle travel mode from “Tmp-EPS” to “2M-SBW” is made according to the speed of the vehicle and the steering state of the steering wheel 38. Can be performed.
As a result, the clutch 8 in the engaged state can be switched to the released state at a timing according to the speed of the vehicle and the steering state of the steering wheel 38, and the clutch 8 in the engaged state is in the released state when the vehicle is running and steering operation is performed. It becomes possible to prevent switching to.

(6) A state in which the vehicle speed is 0 [km / h], the absolute value of the steering angular velocity is equal to or less than the steering angular velocity threshold for non-steering determination, and the absolute value of the steering torque is equal to or less than the non-steering determination torque threshold. If the vehicle continues to the non-steer stop determination time threshold, it is determined that the vehicle is stopped in the non-steer state.
For this reason, it is possible to perform a process of switching the clutch 8 in the engaged state to the disengaged state when the state in which it is determined that the vehicle is stopped in the non-steering state continues stably.
As a result, the clutch 8 in the engaged state can be switched to the released state in a state where the state in which it is determined that the vehicle is stopped in the non-steering state continues stably. As a result, the clutch 8 in the engaged state is disengaged when the vehicle travels and when the steering operation is performed, compared to the case where the clutch 8 in the engaged state is switched to the disengaged state when it is determined that the vehicle is stopped in the non-steered state. It is possible to prevent switching with high accuracy.

(7) In the vehicle steering control method of the present embodiment, when the ignition switch is in the on state and the voltage of the battery 46 becomes less than the voltage threshold, the clutch 8 is switched from the released state to the engaged state. In addition, the driving support function is controlled using the turning angle estimated immediately before the clutch 8 in the released state is switched to the engaged state. On the other hand, when the clutch 8 is switched from the engaged state to the released state, the driving support function is performed using the steering angle estimated when the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the vehicle traveling state is determined to be straight. To control.

For this reason, when the clutch 8 is switched from the engaged state to the released state, the driving assistance is performed using the steering angle estimated when the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the vehicle traveling state is determined to be straight. The function can be controlled.
As a result, even when the stored turning angle stored in the turning angle storage unit 48 cannot be read, the estimation accuracy is high since the clutch 8 is switched from the engaged state to the released state. It is possible to control the driving support function using the steering angle estimated in (1).

(Modification)
(1) In the present embodiment, when the clutch 8 in the engaged state is determined that the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the traveling state of the vehicle is straight, the non-steering state and the vehicle are stopped. If the determination is established, the state is switched to the open state, but the present invention is not limited to this. That is, the clutch 8 in the engaged state may be switched to the released state when at least one of the determination that the clutch 8 is in a non-steering state and the determination that the vehicle is stopped is established.

(2) In the present embodiment, it is determined whether or not the vehicle is traveling straight in the state where the vehicle travel mode is set to “Tmp-EPS”, and whether or not the vehicle is stopped in a non-steered state. However, the present invention is not limited to this. That is, with the vehicle travel mode set to “1M-EPS” or “MS”, it is determined whether the vehicle is traveling straight and whether the vehicle is stopped in a non-steered state. A determination may be made. Similarly, SBW control and driving assistance using the steering angle estimated after determining that the vehicle traveling state is straight traveling with the vehicle traveling mode set to “1M-EPS” or “MS”. Function control may be performed.

(3) In the present embodiment, the configuration of the vehicle is configured to include two steering actuators (the first steering motor 2 and the second steering motor 4), but the configuration of the vehicle is limited to this. It is not a thing. That is, the configuration of the vehicle may be a configuration including only one steering actuator.

(4) In the present embodiment, the steered angle of the steered wheels 24 is estimated using the steered angle estimation map showing the relationship between the steering angle of the steering wheel 38, the steered angle of the steered wheels 24, and the vehicle speed. However, the present invention is not limited to this. That is, for example, the turning angle of the steered wheel 24 may be estimated using a mathematical formula that indicates the relationship between the steering angle of the steering wheel 38, the steered angle of the steered wheel 24, and the vehicle speed.

DESCRIPTION OF SYMBOLS 1 Vehicle steering control apparatus 2 1st steering motor 4 2nd steering motor 6 reaction force motor 8 clutch 10 steering angle detection part 12 vehicle speed detection part 14 yaw rate detection part 16 1st steering motor angle sensor 18 2nd steering Motor angle sensor 20 First steered motor torque sensor 22 General controller 24 Steered wheels (24FL, 24FR)
26 First steering motor output shaft 28 Steering rack 30 Rack shaft 32 Second steering motor output shaft 34 Tie rod 36 Knuckle arm 38 Steering wheel 40 Steering shaft 42 Pinion shaft 44 Communication line 46 Battery 48 Steering angle storage section 50 First Steering motor control unit 52 Second steering motor control unit 54 Reaction force motor control unit 56 Steering angle estimation map storage unit 58 Steering angle estimation unit 60 Travel mode setting unit 62 Clutch state switching unit 64 Driving support function control unit

Claims (7)

A clutch that switches between an open state that mechanically separates a torque transmission path between a steering wheel and a steered wheel and a fastening state that mechanically connects the torque transmission path; A steering control device for a vehicle that controls the turning of the steered wheels according to the steering angle of the vehicle,
A clutch state switching unit for switching the state of the clutch;
A steered angle estimating unit that estimates a steered angle of the steered wheels based on the steered angle and the speed of the vehicle;
A straight traveling determination unit that determines whether or not the traveling state of the vehicle is traveling straight;
A driving support function control unit that controls a driving support function for the driver of the vehicle using the turning angle estimated by the turning angle estimation unit;
The driving support function control unit is configured such that the ignition switch of the vehicle is on and the voltage of a battery mounted on the vehicle is less than a preset voltage threshold, and the clutch state switching unit moves the clutch from the opened state to the When switching to the engaged state, the driving support function is controlled using the turning angle estimated by the turning angle estimating unit immediately before the released clutch is switched to the engaged state, and the clutch state switching unit Is switched from the engaged state to the opened state, the steering angle estimating unit when the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the straight traveling determination unit determines that the traveling state of the vehicle is straight traveling A vehicle steering control device that controls the driving support function using a turning angle estimated by the vehicle. A non-steering stop state determination unit that determines whether the state of the steering wheel is a preset non-steering state and whether the vehicle is stopped;
A target turning angle for calculating a target turning angle according to a steering operation of the steering wheel by the driver using the steering angle of the steering wheel and the turning angle estimated by the turning angle estimation unit. A calculation unit,
The clutch state switching unit determines that the voltage less than the voltage threshold is equal to or higher than the voltage threshold, the straight traveling determination unit determines that the traveling state of the vehicle is straight traveling, and the non-steer stop state determination unit When at least one of the determination of the non-steering state and the determination that the vehicle is stopped is established, the clutch is switched from the engaged state to the released state,
When the clutch in the engaged state is switched to the disengaged state, the target turning angle calculation unit has a voltage less than the voltage threshold equal to or higher than the voltage threshold, and the straight traveling determination unit determines that the vehicle is traveling straight. The vehicle steering control apparatus according to claim 1, wherein the target turning angle is calculated using the turning angle estimated by the turning angle estimation unit after the determination. A vehicle speed detector for detecting the speed of the vehicle;
A yaw rate detector for detecting the yaw rate of the vehicle;
A steering angle detector for detecting a steering angle of the steering wheel,
The straight traveling determination unit is configured such that the speed detected by the vehicle speed detection unit is equal to or greater than a preset vehicle speed threshold, the absolute value of the yaw rate detected by the yaw rate detection unit is equal to or less than a preset yaw rate threshold, and the steering angle detection The vehicle traveling state is determined to be straight traveling if the absolute value of the steering angular velocity based on the steering angle detected by the unit is equal to or less than a preset straight traveling determination steering angular velocity threshold value. Item 3. The vehicle steering control device according to Item 2.   The straight traveling determination unit is configured such that the speed detected by the vehicle speed detection unit is equal to or higher than the vehicle speed threshold, the absolute value of the yaw rate detected by the yaw rate detection unit is equal to or lower than the yaw rate threshold, and the absolute value of the steering angular velocity is 4. The vehicle steering control according to claim 3, wherein when the state that is equal to or less than the straight-ahead determination steering angular velocity threshold continues to a preset straight-ahead determination time threshold, the vehicle traveling state is determined to be straight ahead. apparatus. A vehicle speed detector for detecting the speed of the vehicle;
A steering angle detector for detecting a steering angle of the steering wheel;
A steering torque detector for detecting a steering torque applied to the steering wheel by the driver,
The non-steer stop state determination unit determines that the state of the steering wheel is the non-steer state when the speed detected by the vehicle speed detection unit is 0 [km / h], and the steering angle detection unit The absolute value of the steering angular velocity based on the detected steering angle is equal to or less than a preset non-steering determination steering angular velocity threshold, and the absolute value of the steering torque detected by the steering torque detection unit is set in advance. 3. The vehicle steering control device according to claim 2, wherein the vehicle steering control device determines that the vehicle is stopped when the following is true.   The non-steer stop state determination unit is configured such that the absolute value of the steering angular velocity is equal to or less than the steering angular velocity threshold for non-steer determination, and the absolute value of the steering torque detected by the steering torque detection unit is the non-steer determination torque threshold. 6. The vehicle steering control device according to claim 5, wherein the vehicle is determined to be stopped when the following state continues until a preset non-steer stop determination time threshold value. When the clutch is switched between an open state in which the torque transmission path between the steering wheel and the steered wheel is mechanically separated and an engagement state in which the torque transmission path is mechanically coupled, the steering wheel is steered. A vehicle steering control method for steering-controlling the steered wheel according to a corner,
When the ignition switch of the vehicle is on and the voltage of the battery mounted on the vehicle falls below a preset voltage threshold value, the clutch is switched from the opened state to the engaged state, and the opened clutch is engaged. The driving support function for the driver of the vehicle is controlled using the turning angle of the steered wheels estimated based on the steering angle and the speed of the vehicle immediately before switching to a state, and the clutch is moved from the engaged state to the clutch. When switching to the open state, the steering angle estimated based on the steering angle and the speed of the vehicle when it is determined that the voltage less than the voltage threshold is equal to or higher than the voltage threshold and the traveling state of the vehicle is straight ahead. A vehicle steering control method using the driving support function.

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