JP5050402B2 - Vehicle steering control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering control device capable of suppressing any abrupt fluctuation of a steering wheel associated with the remaining reaction force accumulated in a turning unit when completing the turning control. <P>SOLUTION: A regenerative control means 14 is provided, which performs the regenerative control for generating the regenerative current in a turning motor 7 when completing the turning control. The regenerative control means 14 continues the regenerative control before it is determined that the remaining reaction force accumulated in a steering wheel or a steering rack 13 is eliminated. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention belongs to a technical field of a vehicle steering control device that drives and controls the steered motor so as to be in a steered state of the steered unit according to an operation state of an operation unit.

  In a steering system equipped with a steering motor, for example, when the vehicle is stopped in a stationary state when entering a garage, the steering motor remains in a state where reaction force remains in the steering system due to tire deformation (shrinkage or torsion). Since the residual reaction force is released, the steered wheels suddenly fluctuate, and the vehicle may shake and give the driver discomfort.

Therefore, in the conventional vehicle steering control device, the steering control is performed by adding the twist to the target turning angle at the time of stationary, and then performing the turning control to return to the target turning angle. Sudden fluctuation of the steering wheel is suppressed (for example, refer to Patent Document 1).
JP 2004-42769 A

  However, in the above prior art, if the driver turns off the ignition switch and stops the system after adding the twist to the target turning angle and before returning to the target turning angle, the residual reaction force is reduced. There was a problem that the steered wheels fluctuated rapidly at the same time as the SBW system stopped. On the other hand, after the steering control is finished, when the sudden change of the steered wheels is suppressed by using physical means, the steered wheels are difficult to steer and may interfere with the work in the maintenance shop. .

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to provide a residual reaction accumulated in the steering section at the end of the steering control without interfering with the work in the maintenance shop. An object of the present invention is to provide a vehicle steering control device capable of suppressing a sudden fluctuation of a steered wheel due to a force.

In order to achieve the above object, the present invention provides:
An operation unit operated by the driver;
A steering unit that is mechanically separated from the operation unit and steers the steering wheel;
A steering reaction force motor for applying a steering reaction force to the operation unit;
Steering reaction force control means for driving and controlling the steering reaction force motor so as to apply a reaction force according to the steering state of the steering unit to the operation unit;
A steering motor for applying steering torque to the steering unit,
Steering control means for performing steering control for driving and controlling the steered motor so as to be in a steered state of the steered unit according to an operation state of the operation unit;
In a vehicle steering control device comprising:
Backup means for mechanically connecting the operation unit and the steering unit;
Relative rotation maintaining means for fastening the backup means at the end of the steering control and maintaining the relative positional relationship between the operation unit and the steering unit during the steering control;
Residual reaction force determination means for determining whether or not residual reaction force is accumulated in the steered wheel or the steered portion at the end of the steering control;
When it is determined that the residual reaction force is accumulated, and after the operation unit and the steered unit are mechanically connected by the backup unit , until the residual reaction force is eliminated, Regenerative control means for performing regenerative control for generating a regenerative current in the steering motor, and when it is determined that residual reaction force is not accumulated, regenerative control means that does not perform the regenerative control ;
It is provided with.

In the present invention, when it is determined that the residual reaction force is accumulated in the steered wheel or the steered portion at the end of the steering control , the residual reaction force accumulated in the steered portion. Until the problem is resolved, regenerative control for generating a regenerative current in the steered motor is performed. That is, an electric power regenerative brake is applied to the rotation of the steered motor that accompanies the steering of the steered wheels, and the residual reaction force is gently released to suppress sudden fluctuations of the steered wheels. This regeneration control is canceled simultaneously with the cancellation of the residual reaction force, and the steering wheel returns to a free state in which it can easily move left and right.
As a result, it is possible to suppress sudden fluctuations of the steered wheels due to the residual reaction force accumulated in the steered wheels or the steered portion at the end of the steering control without hindering the work in the maintenance factory. it can.

  Hereinafter, the best mode for carrying out the present invention will be described based on Examples 1 and 2.

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 of the first embodiment includes a steering handle (operation unit) 1, a torque sensor 2, a steering reaction force motor 3, a handle angle sensor 4, a backup clutch (backup means) 5, a backup cable 6, Steering motor 7, steering angle sensor 8, steering reaction force ECU (steering reaction force control means) 9, steering ECU (steering control means) 10, right front wheel 11a and left front wheel 11b (hereinafter referred to as steering) A wheel 11), a vehicle speed sensor 12, and a steering rack 13.

  The SBW system according to the first embodiment has a configuration in which there is no mechanical connection between the steering handle 1 and the steering rack 13. However, a backup clutch 5 is provided as a mechanical backup mechanism, and the steering handle 1 and the steering rack 13 can be mechanically connected by fastening the backup clutch 5. That is, when any abnormality occurs in the SBW system, manual steering can be performed by connecting the backup clutch 5.

  The steering reaction force ECU 9 performs steering reaction force control for driving and controlling the steering reaction force motor 3 so that the steering wheel target angle based on each sensor signal is obtained. The steered ECU 10 performs steered control for driving and controlling the steered motor 7 so that the steered wheels 11 are steered according to the steered state of the steering handle 1. The steering reaction force control and the turning control constitute SBW control.

  The steered ECU 10 generates a regenerative current in the steered motor 7 until the residual reaction force accumulated in the steered portion such as the steered wheels 11 and the steering rack 13 is eliminated at the end of the SBW control. Implement control. At the same time, the steering ECU 10 engages the backup clutch 5 to mechanically connect the steering handle 1 and the steering rack 13 while the regenerative control is continued, and the steering handle 1 and the steered wheels 11 during SBW control. The relative rotation maintaining control is performed to maintain the relative positional relationship with.

[Circuit configuration of steering ECU]
FIG. 2 is a circuit configuration diagram of the steered ECU 10 according to the first embodiment, and the steered ECU 10 includes a CPU 21 and a motor drive circuit 22.
The CPU 21 performs various calculations, signal output, and the like necessary for SBW control and regenerative control (including relative rotation maintenance control) based on each sensor signal.

  The motor drive circuit 22 controls the steered motor 7 and the backup clutch 5 in response to a command signal from the CPU 21, and includes a power relay 23, a capacitor 24, a transistor 25, a diode 26, a current sensor. 27, a motor relay 28, and a backup clutch drive circuit 29.

  The power relay 23 and the motor relay 28 are driven by a regenerative current of the steered motor 7 such that an unnecessary current such as an overcurrent flows through the CPU 21 or obstructs manual steering when the SBW system ends or fails. The relays 23 and 28 are both turned off and opened at the time of failure or termination of the SBW system. Further, during regenerative control, these relays 23 and 28 are used as one of means for terminating the regenerative control.

The capacitor 24 is for flowing an alternating current to the steered motor 7 during the regeneration control by the regeneration control means 14 described later. In the SBW system, a relatively large capacity capacitor of aluminum electrolysis is used.
The transistor 25 is used as a switching element that drives the steered motor 7 during SBW control, and is turned off during regenerative control.

The diode 26 rectifies the regenerative current that flows during regenerative control.
The current sensor 27 is used to control the current or torque of the steered motor 7 during SBW control, and is used to measure the regenerative current value of the steered motor 7 during regenerative control. It can also be used when diagnosing a failure of the transistor 25 or the like.
The power supply relay 23, the capacitor 24, the transistor 25, the diode 26, the current sensor 27, and the motor relay 28 constitute the regeneration control means 14 of the first embodiment.

The backup clutch drive circuit 29 drives the backup clutch 5 to the engagement side or the release side according to a command signal from the CPU 21.
The circuit configuration of the steered ECU 10 is a drive circuit for a general three-phase synchronous motor used in a conventional SBW system, and there are no special parts for the regeneration control means 14.

[Regenerative control and relative rotation maintenance control processing]
FIG. 3 is a flowchart showing the flow of the regenerative control and the relative rotation maintenance control process executed by the steered ECU 10 of the first embodiment, and each step will be described below.

  In step S1, it is determined whether or not the ignition switch is OFF. If YES, the process proceeds to step S2, and if NO, the process proceeds to step S9.

  In step S2, based on the signal from the vehicle speed sensor 12, it is determined whether or not the vehicle speed is 0 km / h. If YES, the process proceeds to step S3. If NO, the process proceeds to step S9.

  In step S3, in order to maintain the relative rotation between the steering wheel 1 and the steering wheel 11, the backup clutch drive circuit 29 is driven to the clutch engagement side to engage the backup clutch 5, and the process proceeds to step S4 (maintain relative rotation). means).

  In step S4, the turning control (SBW control) for controlling the angle of the steered wheels 11 according to the steering of the steering handle 1 is stopped, the regeneration control by the regeneration control means 14 is made to function, and the process proceeds to step S5. Here, in order to make the regeneration control function, all the transistors 25 for driving the steered motor 7 performed in the steered control are turned off, and are provided on the three-phase line and the power line of the steered motor 7. The power supply relay 23 and the motor relay 28 are kept ON.

  In step S5, it is determined whether or not the regenerative current during regenerative control obtained from the signal of the current sensor 27 is a predetermined value Ia (≈0). If YES, the process proceeds to step S6, and if NO, this control process is terminated.

In step S6, it is determined whether or not the amount of change in the rotation angle of the turning motor 7 during regenerative control obtained from the signal of the turning angle sensor 8 is a predetermined amount ΔNa (≈0). If YES, the process proceeds to step S7, and if NO, this control process ends.
By step S5 and step S6, it is determined whether the residual reaction force accumulated in the steered portion has been eliminated.
Instead of step S5 and step S6, set the time for eliminating the residual reaction force accumulated in the steered part in advance, and remain if the elapsed time after turning the steering control exceeds the set time It may be determined that the reaction force has been eliminated.

  In step S7, the regeneration control by the regeneration control means 14 is canceled, and the process proceeds to step S8. Here, the regenerative control is canceled by turning off the power supply relay 23 and the motor relay 28.

  In step S8, the power supply of the ECU 21 is turned off, and this control process ends.

  In step S9, it is determined whether regenerative control is being performed. If YES, the process proceeds to step S10. If NO, the process proceeds to step S15.

  In step S10, SBW diagnosis for diagnosing whether or not the SBW system is operating normally is performed, and the process proceeds to step S11 (system diagnosis means). This diagnosis restarts the diagnosis again when a function unnecessary for regenerative control and relative rotation maintenance control, for example, the diagnosis of the torque sensor 2 or the like, is completed when the SBW system end condition is satisfied, and is about several tens of ms. Can be done in a very short time.

  In step S11, it is determined whether or not the SBW diagnosis result (normal / abnormal) is confirmed. If YES, the process proceeds to step S12. If NO, the present control process is terminated.

  In step S12, the regenerative control is canceled to place the SBW system in a fail safe state, and the process proceeds to step S13.

  In step S13, it is determined whether or not the SBW system is normal. If YES, the process proceeds to step S14. If NO, the present control is terminated.

  In step S14, the relative rotation maintenance control is canceled by releasing the backup clutch 5, and the process proceeds to step S15.

  In step S15, SBW control is started and this control is ended.

Next, the operation will be described.
[Sudden change of steering wheel due to residual reaction force]
Conventionally, in a steer-by-wire (SBW) system that employs angular position control to control the steered wheels, if the system termination conditions (eg, ignition switch OFF and vehicle speed zero) are met, the ECU power supply and motor Drive power is stopped.

  Therefore, when the system ends with the steering wheel being twisted due to a stationary or the like, the current flowing in the angular position control to maintain the position stops flowing at the same time as the motor drive power is stopped, and the road surface The steering wheel may suddenly fluctuate due to the release of the residual reaction force accumulated by the twisting of the steering wheel. In particular, when the fluctuating power is large, the vehicle body shakes, giving the driver discomfort.

  Further, in the SBW system having the mechanical backup means (backup clutch) as shown in FIG. 4, the backup means is fastened in consideration of safety immediately after the power supply is stopped at the end of the system. Therefore, as shown in FIG. 5, when the motor current is stopped due to the end of the SBW system (time point t0), not only the steered wheel suddenly fluctuates but also the steering wheel suddenly fluctuates.

  Such a sudden fluctuation of the vehicle body and a sudden fluctuation of the steering wheel due to a sudden fluctuation of the steering wheel when the system is OFF are uncomfortable for the driver and are not preferable in terms of products. Therefore, in the rudder angle control device described in Japanese Patent Application Laid-Open No. 2004-42769, an object is to prevent the steered wheels from being steered by a residual reaction force when switching from the stationary state to the EPS (electric power steering) control. At the time of stationary, control is performed by adding the target turning angle to the twisted amount, and then returning to the true target turning angle.

  However, in this conventional technology, after adding the twist to the target turning angle and before returning to the target turning angle, the system is stopped by turning off the ignition switch of the driver, the residual reaction force is not eliminated, and the SBW There was a problem that the steering wheel fluctuated suddenly at the same time as the system stopped. On the other hand, after the steering control is finished, when the sudden change of the steered wheels is suppressed by using physical means, the steered wheels are difficult to steer and may interfere with the work in the maintenance shop. .

[Steering wheel fluctuation suppression effect]
On the other hand, in the first embodiment, when the SBW system end condition (for example, the ignition switch is OFF and the vehicle speed is zero) is satisfied and the SBW control is ended, the turning motor 7 so that the regenerative current flows through the turning motor 7. Regenerative control means 14 for controlling the driving of the steering wheel 11 is provided to suppress sudden fluctuations of the steering wheel 11.

FIG. 6 is a time chart showing the steered wheel fluctuation suppressing effect of the first embodiment when the engine is stopped after being stationary.
At time t1, since the ignition switch is turned off after the vehicle stops, the process proceeds from step S1 to step S2 to step S3 in the flowchart of FIG. 3, and the backup clutch 5 is switched from disengagement to engagement.

  Subsequently, at time t2, the process proceeds to step S4 to switch from SBW control to regenerative control until the regenerative current value is equal to or smaller than the predetermined value Ia and the rotation angle change amount of the steered motor 7 is equal to or smaller than the predetermined amount ΔNa. In the meantime, the flow of step S1, step S2, step S3, step S4, step S5 or step S1, step S2, step S3, step S4, step S5, and step S6 is repeated.

  At this time, the steering motor 7 is about to be rotated by the residual reaction force. However, in the first embodiment, a regeneration current flows through the steering motor 7 by the regeneration control means 14 (FIG. 7), and the braking force generated thereby is changed. Abrupt fluctuation of the steered wheel 11 generated in the rudder motor 7 can be suppressed. At this time, since the braking force is a braking force generated by regenerative power generation, the battery of the vehicle is not used unnecessarily in order to suppress sudden fluctuations in the steered wheels 11, and power consumption can be suppressed.

  In the first embodiment, the regeneration control unit 14 includes the diode 26 generally provided in the transistor 25 of the motor drive bridge circuit (H bridge, three-phase bridge) of the SBW system, the power source and ground of the motor drive circuit. This is realized by the configuration with the capacitor 24 mounted for the purpose of flowing an alternating current between them. For this reason, it can implement | achieve easily, without causing the cost increase by an additional component.

[Regeneration control release action when residual reaction force is eliminated]
In the time chart of FIG. 6, at time point t3, the regenerative current value (motor current) of the steered motor 7 is equal to or less than the predetermined value Ia and the amount of change in rotational angular velocity is equal to or less than the predetermined amount ΔNa, so step S1 → step S2 → step The process proceeds from S3 → step S4 → step S5 → step S6 → step S7. In step S7, the power supply relay 23 and the motor relay 28 are turned off, and the regenerative control is released.

  In the SBW system, when the system is stopped, it is desirable that the steered wheels are free to move left and right in consideration of, for example, work in a maintenance shop, and the braking force by the regeneration control means 14 has a residual reaction force. It is desirable to make it function only during Therefore, it is necessary to detect whether or not the residual reaction force has been released. In Example 1, since the regenerative current flows while the residual reaction force is applied to the steering motor 7, it can be determined whether or not the residual reaction force has been released depending on whether or not this regenerative current is flowing. You can know when the regeneration control is released. Furthermore, the current sensor 27 for detecting the current is provided in the motor drive circuit of a normal SBW system, and a special sensor for detecting the residual reaction force is not necessary.

  Further, when the steered wheel 11 fluctuates due to the residual reaction force, the steered motor 7 rotates, so whether or not the residual reaction force from the rotation angle change amount of the steered motor 7 is released as with the regenerative current. Therefore, it is possible to detect the appropriate regenerative control release timing.

[Relative rotation maintaining action]
In the first embodiment, when the system termination condition is satisfied and the regeneration control is functioned, the relationship between the turning angle of the steered wheels 11 and the relative rotation of the steering handle 1 is maintained. That is, in step S3, the relative rotation maintaining control for engaging the backup clutch 5 is performed.

  The regenerative control is intended to suppress sudden fluctuation of the steered wheel 11 by gently releasing the residual reaction force. Therefore, when there is a residual reaction force in the steered portion, the steered wheel 11 has a residual reaction force. Fluctuates depending on In that case, when the relationship between the turning angle of the steered wheels 11 and the relative rotation of the steering wheel 1 deviates from the state immediately before the control stop (during SBW control), the steering gear ratio stored during the control changes. End up. Therefore, the next time the SBW system is started, processing such as neutral deviation correction is forced. Therefore, in the first embodiment, by maintaining the relative rotation when the regenerative control is functioning, the steered angle of the steered wheel 11 and the steering handle 1 are accompanied by a sudden change of the steered wheel 11 due to the residual reaction force. The relative rotation relationship between the neutral shift and the neutral shift can be suppressed.

  The backup clutch 5 used for maintaining the relative rotation is a mechanism necessary for enabling manual steering when the SBW system fails, and the steering wheel 11 and the steering handle 1 are relatively moved during regenerative control. It is a means that functions in addition to maintaining rotation. The backup clutch 5 is usually configured to perform mechanical engagement and disengagement by electromagnetic force. From the fail-safe design concept, the backup clutch 5 only needs to be de-energized and processed. Is simple (see FIG. 2).

  Further, since the backup clutch 5 has a fastening force capable of maintaining the relative rotation between the steering wheel 1 and the steered wheels 11 with respect to the input torque at the time of manual steering, the regenerative control is functioning. The relative rotation between the steering wheel 1 and the steering wheel 11 can be reliably maintained even when the steering wheel 11 is displaced.

[SBW control return action according to system diagnosis]
FIG. 8 is a time chart showing the SBW control return operation of the first embodiment when the ignition switch is turned on immediately after the ignition switch is turned off after stationary.
At time points t4 and t5, processing similar to that at time points t1 and t2 in FIG.

  At time t6, since the ignition switch is turned on during the regeneration control, the process proceeds from step S1 to step S9 to step S10 in the flowchart of FIG. 3, and in step S10, it is diagnosed whether the SBW system is operating normally. Until the SBW diagnosis is started and the SBW diagnosis result is confirmed, the flow from step S1, step S9, step S10, and step S11 is repeated.

  In the first embodiment, when the engine (vehicle drive source) is started during the regenerative control (ignition switch ON), the regenerative control is continued until the normal / abnormal diagnosis of the SBW system is completed. That is, the process proceeds from step S1 to step S9 to step S11, and only when the SBW diagnosis result is confirmed in step S11, the process proceeds to step S12 and the regenerative control is released.

  The ignition switch ON indicates that the driver wants to resume driving. Therefore, the SBW control is started. In the first embodiment, since the SBW control is temporarily stopped and switched to the regenerative control and the relative rotation maintenance control, the part used only for the SBW control (for example, the steering torque of the driver is changed). Diagnosis of the torque sensor to be detected) may be stopped.

  In this case, it is necessary to perform an initial diagnosis as to whether it is safe to start SBW control in response to a request for starting SBW control. Since the SBW control is not executed during the initial diagnosis, there is no command value for the steering motor angle and no current command value. Therefore, if the regenerative control is stopped during the initial diagnosis, a sudden change in the steered motor 7 due to the residual reaction force occurs.

  Therefore, in Example 1, the regeneration control is continued during the initial diagnosis. Thereby, the sudden fluctuation of the steered wheel 11 due to the residual reaction force during the initial diagnosis can be suppressed. Then, if normal according to the diagnosis result, the regeneration control is canceled and the SBW control may be started. In that case, even if the residual reaction force remains, the SBW control can suppress the angle fluctuation of the steered wheel 11, and even if it is not normal, for example, in the SBW system having the backup clutch 5, the regenerative control is continued, By releasing the regeneration control after the residual reaction force is released, it is possible to shift to manual steering.

  It should be noted that the time required for the initial diagnosis is at most several 10 to 100 ms, which is sufficiently shorter than the time until the engine is started, for example. Therefore, by continuing the regenerative control during that time, there is no safety problem even if the timing for shifting to manual steering is delayed in the SBW system having the backup clutch 5.

At time t7, since it is determined that the SBW system is normal, the process proceeds from step S11 to step S12 to step S13 to step S14 to step S15. After releasing the backup clutch 5 and releasing the relative rotation maintenance control, the SBW control is performed. Switch. When it is determined that the SBW system is normal, the SBW control is started, and the angular position control of the steered wheel 11 by the SBW control is performed even when the residual reaction force remains. Sudden fluctuation of the steering wheel 11 due to force can be suppressed.
Since the battery is charged if the engine is started, there is no particular problem even if power is consumed by controlling the angle of the steered wheel 11 by SBW control.

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 handle 1 operated by the driver, the steering rack 13 that steers the steered wheels 11, the steering motor 7 that applies a steering torque to the steering rack 13, and the operation state of the steering handle 1 In a vehicle steering control device, including a steered ECU 10 that performs steered control (SBW control) for driving and controlling a steered motor 7 so that a steered state of a corresponding steering rack 13 is obtained. At the end, regenerative control means 14 for performing regenerative control for generating a regenerative current in the steering motor 7 is provided, and the regenerative control means 14 regenerates until the residual reaction force accumulated in the steered portion is eliminated. Continue control. Accordingly, it is possible to suppress sudden fluctuations in the steered wheels due to the residual reaction force accumulated in the steered portion at the end of the steered control without hindering work or the like in the maintenance factory.

  (2) Since the regenerative control means 14 determines that the residual reaction force has been eliminated when the regenerative current becomes equal to or less than the predetermined value Ia, the regenerative control means 14 can determine the appropriate regenerative control release time and does not require additional components. The presence or absence of residual reaction force can be determined using a current sensor used in normal steering control.

  (3) Since the regenerative control means 14 determines that the residual reaction force has been eliminated when the rotation angle change amount of the steered motor 7 is equal to or less than the predetermined amount ΔNa, it can determine the appropriate regenerative control release timing. Without the addition of parts, it is possible to determine the presence or absence of residual reaction force using a current sensor used in normal steering control.

  (4) The steering handle 1 and the steering rack 13 are mechanically separated, a steering reaction force motor 3 for applying a steering reaction force to the steering handle 1, and the steering handle 1 according to the steering state of the steering rack 13. Steering reaction force ECU 9 that drives and controls the steering reaction force motor 3 to apply reaction force, and relative rotation maintenance control that maintains the relative positional relationship between the steering wheel 1 and the steering rack 13 during regenerative control and steering control. And a relative rotation maintaining means (step S3). Thereby, in the SBW system in which the steering handle 1 and the steering rack 13 are mechanically separated, it is possible to suppress the occurrence of neutral shift due to the fluctuation of the steered wheels 11.

  (5) The backup clutch 5 that mechanically connects the steering handle 1 and the steering rack 13 is provided, and the relative rotation maintaining means (step S3) fastens the backup clutch 5. As a result, relative rotation maintaining means that suppresses the occurrence of neutral shift without increasing the cost by using the backup clutch 5 mounted on the vehicle in order to realize manual steering during fail-safe in a general SBW system. Can be configured.

  (6) When the ignition switch is turned on during the regenerative control, the regenerative control means 14 cancels the regenerative control, and the turning ECU 10 starts the turning control after the regenerative control is released. Thereby, residual reaction force can be suppressed by steering control, suppressing the control delay of the steering wheel 11 at the time of vehicle start.

  (7) System diagnosis means (step S10) for diagnosing the state of the steered control system is provided, and the steered ECU 10 and the steering reaction force ECU 9 perform relative rotation control after diagnosing that the steer-by-wire system state is normal. When the means (step S14) is released, SBW control is started. Thereby, it is possible to safely shift from the regenerative control to the SBW control.

  The second embodiment is an example of an SBW system that does not have backup means for mechanically connecting the steering handle 1 and the steering rack 13.

[overall structure]
FIG. 9 is a configuration diagram of the SBW system to which the vehicle steering control device of the second embodiment is applied. As for the overall configuration, the backup clutch 5 and the backup cable 6 are omitted from the configuration of the first embodiment shown in FIG. Since it is a structure, description is abbreviate | omitted.

[Control structure of relative rotation maintaining means]
FIG. 10 is a control block diagram illustrating the relative rotation maintaining unit of the second embodiment. The relative rotation maintaining unit is set as software executed by the steering reaction force ECU 9 and includes a target angle calculation processing unit 41 and a comparator 42. And a PI (integral proportional) controller 43 and a steering reaction force motor drive circuit 44.

The target angle calculation processing unit 41 inputs the steered angle of the steered wheels 11 from the steered angle sensor 8 and the current steering gear ratio, and maintains the relative relationship between the steering handle 1 and the steered wheels 11. Output the steering handle target angle.
The comparator 42 inputs the steering handle target angle and the steering handle angle from the handle angle sensor 4 and outputs a difference.

A PI (proportional integration) controller 43 inputs a difference between the steering handle target angle and the steering handle angle, and outputs a current command value of the steering reaction force motor 3 based on the PI control.
The steering reaction force motor drive circuit 44 inputs a current command value and outputs a control current supplied to the steering reaction force motor 3.

[Regenerative control and relative rotation maintenance control processing]
FIG. 11 is a flowchart showing the flow of regenerative control and relative rotation maintenance control processing executed by the relative rotation maintenance means of the steered ECU 10 and the steering reaction force ECU 9 of the second embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the process same as Example 1 shown in the figure, and description is abbreviate | omitted.

  In step S21, the control of the steering reaction force motor 3 is changed from the normal steering reaction force control to the angular position of the steering handle 1 corresponding to the angular position of the steered wheel 11 as the relative rotation maintenance control, and the process proceeds to step S4. (Relative rotation maintaining means). Here, as shown in FIG. 10, the steering angle of the steered wheels 11 and the steering handle target angle of the steering handle 1 are obtained by dividing the steered angle of the steered wheels 11 by the steering gear ratio. Is calculated. Then, a current command value of the steering reaction force motor 3 corresponding to the difference between the current steering wheel angle and the steering wheel target angle is calculated, and a current is supplied to the steering reaction force motor 3 by the steering reaction force motor drive circuit. This current flows in a direction in which the difference between the current steering wheel angle and the steering steering wheel target angle is small.

  In step S22, the terminal of the steering reaction force motor 3 is short-circuited, and the steering handle 1 is fixed using a mechanical rotation restraining mechanism (not shown), so that the steering handle 1 and the steering wheel 11 while the SBW system is stopped are stopped. Shifts in the relationship of the rotation angle with the shift to step S9.

Next, the operation will be described.
In Example 2, as shown in the time chart of FIG. 12, when the system termination condition is satisfied and the SBW control is terminated, the steering motor 7 is driven and controlled so that the regenerative current flows through the steering motor 7. Similar to the first embodiment, the steered wheel 11 can be gently released by the electric power regenerative braking of the steered motor 7 to suppress sudden fluctuation of the steered wheel 11.

  Also, in the second embodiment, when the ignition switch is turned on during the regeneration control, the regeneration control is continued until the SBW system is diagnosed as normal, and after the regeneration control is released, the SBW control is started. Similar to Example 1, the residual reaction force can be suppressed by the turning control while suppressing the control delay of the steered wheels 11 when the vehicle starts (FIG. 13).

[Relative rotation maintaining action]
In the second embodiment, the relative rotation maintaining unit controls the steering reaction force motor 3 so that the steering wheel 1 has a steering wheel angle corresponding to the steering angle of the steering wheel 11.

  In the SBW, during normal traveling, the angular position of the steered wheels 11 is controlled so that the steered wheel 11 has a steered angle corresponding to the handle angle of the steering handle 1. Thereby, the relative rotation of the steering wheel 1 and the steering wheel 11 is maintained. In addition, the steering reaction force is controlled so that a steering reaction force equivalent to that of a normal vehicle that is mechanically connected is generated, and the steering angle of the steering handle 1 corresponds to the turning angle of the steered wheels 11. The handle angle of the steering handle 1 is not controlled.

  Therefore, when the steering angle control on the steered wheel 11 side is stopped and the regenerative control is made to function, the normal reaction force control maintains the relationship between the steered angle of the steered wheel 11 and the relative rotation of the steering handle 1. Can not do it. Therefore, in the second embodiment, the steering reaction force motor 3 is controlled so as to have a steering wheel 1 angle corresponding to the steering angle of the steering wheel 11, whereby the steering angle of the steering wheel 11 and the steering wheel 1 are controlled. The relative rotation relationship with the handle angle can be maintained.

Thereby, even if it is a case where the steering wheel 11 fluctuates during regenerative control, generation | occurrence | production of a neutral shift can be suppressed.
In the second embodiment, the steering reaction force motor 3 adjusts the steering wheel 1 to the steered wheel 11 side, so that the steered wheel 11 is controlled against the road surface reaction force. The relative rotation can be maintained with a small amount of electric power.

Next, the effect will be described.
In the vehicle steering control apparatus according to the second embodiment, the following effects can be obtained in addition to the effects (1) to (4), (6), and (7) of the first embodiment.

  (8) The relative rotation maintaining means (step S21) controls the steering reaction force motor 3 so that the steering angle of the steering wheel 1 becomes the steering angle corresponding to the steering angle of the steered wheels 11, and therefore has no backup means. In the system, the occurrence of neutral shift can be suppressed.

(Other examples)
The best mode for carrying out the present invention has been described based on the first and second embodiments. However, the specific configuration of the present invention is not limited to the first and second embodiments. Design changes and the like within a range not departing from the gist are included in the present invention.

For example, in the first and second embodiments, the steer-by-wire system in which the operation unit and the steering unit are mechanically separated has been described. However, the vehicle may include a steering motor that applies a steering torque to the steering unit. The present invention can be applied.
In addition, the motor, ECU, etc. may have a redundant configuration of two or more.

1 is a configuration diagram of a steer-by-wire system to which a vehicle steering control device of Embodiment 1 is applied. 1 is a circuit configuration diagram of a steered ECU 10 according to a first embodiment. FIG. 3 is a flowchart illustrating a flow of regenerative control and relative rotation maintenance control processing executed by the steered ECU 10 according to the first embodiment. It is a block diagram of the steer-by-wire system provided with the conventional backup means. It is a time chart which shows the sudden fluctuation | variation of the steering wheel accompanying a residual reaction force. It is a time chart which shows the steering wheel fluctuation | variation suppression effect | action of Example 1 at the time of stopping an engine after stationary. It is a figure which shows the flow of the regeneration electric current in the regeneration control means 14 of Example 1. FIG. It is a time chart which shows the SBW control return effect | action of Example 1 at the time of restarting an engine immediately after stopping an engine after stationary. It is a block diagram of the SBW system to which the steering control apparatus for vehicles of Example 2 is applied. It is a control block diagram which shows the relative rotation maintenance means of Example 2. 6 is a flowchart showing a flow of regenerative control and relative rotation maintenance control processing executed by the relative rotation maintenance means of the steering ECU 10 and the steering reaction force ECU 9 of the second embodiment. It is a time chart which shows the steered wheel fluctuation | variation suppression effect | action of Example 2 at the time of stopping an engine after stationary. It is a time chart which shows the SBW control return effect | action of Example 2 at the time of restarting an engine immediately after stopping an engine after stationary.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Torque sensor 3 Steering reaction force motor 4 Steering angle sensor 5 Backup clutch 6 Backup cable 7 Steering motor 8 Steering angle sensor 9 Steering reaction force ECU
10 Steering ECU
11 Steering wheel 12 Vehicle speed sensor 13 Steering rack 14 Regeneration control means 21 CPU
22 motor drive circuit 23 power relay 24 capacitor 25 transistor 26 diode 27 current sensor 28 motor relay 29 backup clutch drive circuit 41 target angle calculation processing unit 42 comparator 43 PI controller 44 steering reaction force motor drive circuit

Claims (6)

An operation unit operated by the driver;
A steering unit that is mechanically separated from the operation unit and steers the steering wheel;
A steering reaction force motor for applying a steering reaction force to the operation unit;
Steering reaction force control means for driving and controlling the steering reaction force motor so as to apply a reaction force according to the steering state of the steering unit to the operation unit;
A steering motor for applying steering torque to the steering unit,
Steering control means for performing steering control for driving and controlling the steered motor so as to be in a steered state of the steered unit according to an operation state of the operation unit;
In a vehicle steering control device comprising:
Backup means for mechanically connecting the operation unit and the steering unit;
Relative rotation maintaining means for fastening the backup means at the end of the steering control and maintaining the relative positional relationship between the operation unit and the steering unit during the steering control;
Residual reaction force determination means for determining whether or not residual reaction force is accumulated in the steered wheel or the steered portion at the end of the steering control;
When it is determined that the residual reaction force is accumulated, and after the operation unit and the steered unit are mechanically connected by the backup unit , until the residual reaction force is eliminated, Regenerative control means for performing regenerative control for generating a regenerative current in the steering motor, and when it is determined that residual reaction force is not accumulated, regenerative control means that does not perform the regenerative control ;
The vehicle steering control apparatus characterized by comprising a. The vehicle steering control device according to claim 1,
The regenerative control means determines that the residual reaction force has been eliminated when the regenerative current becomes a predetermined value or less. The vehicle steering control device according to claim 1 or 2,
The regenerative control means determines that the residual reaction force has been eliminated when the turning angle change amount of the steered wheels is equal to or less than a predetermined amount. The vehicle steering control device according to any one of claims 1 to 3,
The vehicle steering control device, wherein the relative rotation maintaining means controls the steering reaction force motor so as to be in a position of the operation unit according to a position of the steering unit. The vehicle steering control device according to any one of claims 1 to 4 ,
The regeneration control means cancels the regeneration control when a drive source of a vehicle is started during the regeneration control,
The vehicle steering control device, wherein the steering control means starts the steering control after releasing the regeneration control. The vehicle steering control device according to any one of claims 1 to 5 ,
System diagnosis means for diagnosing the state of the steering control system is provided,
The steering control means and the steering reaction force control means start control when the relative rotation maintaining means is released after it is diagnosed that the state of the steering control system is normal. Vehicle steering control device.

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