JP5233624B2 - Vehicle steering control apparatus and method - Google Patents

Description

  The present invention relates to a vehicle steering control device having an automatic steering control function.

In the conventional vehicle steering control device, the steering angle is controlled according to the steering angle of the steered wheel during automatic steering control such as a lane keep that automatically controls the steered wheel steered angle regardless of the steering wheel operation. By setting the set steering angle, a discrepancy between the steering angle and the vehicle behavior is avoided, and a sense of discomfort given to the driver is suppressed (for example, see Patent Document 1).
JP 2006-264374 A

  However, in the above prior art, the steering wheel counteracts the road reaction force generated by the steering angle in order to maintain the steering angle set according to the steering angle of the steered wheel, and cancels this road reaction force. For example, when the driver performs steering such as minute correction steering during automatic steering control, a large force is required during automatic steering control, giving a sense of restraint to the steering wheel. was there.

  An object of the present invention is to provide a vehicle steering control device and method that can prevent a driver from giving a sense of restraint to a steering wheel during automatic steering control.

  In order to achieve the above-described object, in the present invention, the amount of change in the steering reaction force difference, which is the difference between the detected steering reaction force and the steering reaction force estimated from the curvature of the road on which the vehicle travels, is calculated. The steering reaction force correction value is calculated by integration, and a steering reaction force corresponding to the difference between the steering reaction force difference and the steering reaction force correction value is applied to the steering wheel.

  In the present invention, at the time of automatic steering control, the steering angle set according to the target turning angle at the time of automatic turning becomes the steering angle at which the steering reaction force becomes zero, and the steering wheel naturally returns to the steering angle. Since only a reaction force acts, it is possible to prevent the driver from giving a sense of restraint to the steering wheel.

  Hereinafter, the best mode for carrying out the present invention will be described based on examples.

First, the configuration will be described.
FIG. 1 is an overall configuration diagram of a steer-by-wire system to which the vehicle steering control device of the first embodiment is applied. The vehicle steering control device of the first embodiment includes a handle 1 and a front wheel (steering wheel) 2. , 2 is a so-called steer-by-wire (SBW) system in which the steering mechanism 3 that steers is mechanically separated.

  The column shaft 4 that supports the handle 1 includes a reaction force motor (reaction mechanism) 5 that applies a steering reaction force to the handle 1, and the rotation of the column shaft 4 as a steering angle that is a rotation angle from the straight traveling state of the handle 1. A steering angle sensor 6 for detecting the angle is provided. The steered mechanism 3 includes a steered motor 7 for applying a steered torque for steering the front wheels 2 and 2 (steered wheels) to the steered mechanism 3, and a rotational angle from the straight traveling state of the front wheels 2 and 2 A turning angle sensor 9 for detecting the rotation angle of the pinion shaft 8 is provided as a certain turning angle. The pinion shaft 8 is mechanically connected to the front wheels 2 and 2 via the rack 16, and the front wheels 2 and 2 are steered by the rack 16 moving in the axial direction as the pinion shaft 8 rotates. The Therefore, the turning angle can be detected by detecting the rotation angle of the pinion shaft 8.

  The reaction force motor 5 and the steering motor 7 are controlled by a steering controller (reaction force control means) 10. In addition to the steering angle from the steering angle sensor 6 and the turning angle from the turning angle sensor 9, the steering controller 10 includes a rack axial force sensor that detects a force input in the axial direction of the rack 16 from the front wheels 2 and 2. (Steering reaction force detection means) 11, steering reaction force from vehicle speed sensor 12, vehicle speed (vehicle speed), yaw rate from yaw rate sensor 13, captured image from camera (curvature detection means) 14, An automatic steering control selection signal from an automatic steering switch (hereinafter referred to as SW) 15 is input.

  The automatic steering switch 15 is a switch for selecting automatic steering control in the lane keeping control by an ON operation of the driver (driver), and the steering controller 10 is operated when an OFF signal is output from the automatic steering switch 15. Performs normal control. Here, the normal control refers to setting a target turning angle (first target turning angle) according to the steering angle of the steering wheel 1 and the vehicle speed, and turning so that the set first target turning angle can be obtained. While driving the motor 7 to steer the front wheels 2 and 2, the reaction force motor 5 is driven with a torque corresponding to the turning reaction force (road reaction force) detected by the rack axial force sensor 11, and the steering reaction force is reduced. This is a general SBW control that applies force to the handle 1.

  The first target turning angle is set from the relationship between the steering angle and the turning angle based on the steering gear ratio (ratio of the steering angle to the turning angle). The steering gear ratio is changed according to the vehicle speed. For example, the steering gear ratio is reduced (lower steering angle relative to the turning angle) to improve turning performance at low vehicle speeds, and the steering gear ratio is increased (ratio of steering angle to steering angle) at high vehicle speeds. To increase driving stability. Further, the steering reaction force is set to a characteristic such that the steering angle at the time of straight traveling where the steering reaction force according to the steering angle becomes the minimum is the reaction force minimum position, and becomes larger as the steering reaction force increases.

On the other hand, when the ON signal is output from the automatic steering switch 15, the steering controller 10 automatically steers the front wheels 2 and 2 without operating the steering wheel until a predetermined release condition is satisfied. Automatic steering control is executed. Here, the automatic steering control recognizes the lane mark in front of the host vehicle with the camera 14, and the target steering angle (second target steering) of the front wheels 2 and 2 is maintained so that the host vehicle keeps traveling in the lane. Lane keeping control that automatically steers the front wheels 2 and 2 by driving the steering motor 7 so that the turning angle of the front wheels 2 and 2 becomes the set target turning angle. This refers to control for automatically turning the front wheels 2 and 2 according to the situation.
In the following description, the target turning angle at the time of the normal control is described as a first target turning angle, the target turning angle at the time of the automatic turning control is described as a second target turning angle, Collectively, it is described as the target turning angle.

  In Embodiment 1, the second target turning angle of the automatic turning control is obtained by adding the target deviation angle to the first target turning angle set according to the steering angle and the vehicle speed. In other words, the target deviation angle is a difference between the second target turning angle of the automatic turning control and the first target turning angle determined by the steering angle and the vehicle speed.

In the lane keep control of the first embodiment, the target deviation angle is calculated based on the following formula, for example.
Target deviation angle = A × (lateral position with respect to lane) + B × (yaw angle with respect to lane) + C × (lane curvature)
Here, A, B, and C are gains, which are calculated from the gain maps shown in FIGS.
That is, in the lane keep, a gain is set for the lateral position with respect to the lane, the yaw angle with respect to the lane, and the curvature of the lane, and the degree of tracking with respect to the lane is adjusted. The lateral position with respect to the lane, the yaw angle with respect to the lane, and the curvature of the lane can be detected based on the image captured by the camera 14.

  Examples of conditions for canceling automatic steering control include driver steering intervention and brake operation. Here, the steering intervention means that the actual steering angle (actual steering angle) obtained from the steering angle sensor 6 such as lane change or obstacle avoidance operation is larger than the steering angle set according to the second target turning angle. It is assumed that the steering is not changed and the automatic steering control is not canceled when the steering is small enough to maintain the straight traveling or turning state of the vehicle such as correction steering (that is, the small steering at the time of holding). Further, the relationship between the second target turning angle and the “steering angle set according to the second target turning angle” is the same as the relationship between the turning angle determined by the steering gear ratio and the steering angle during normal control. It is. Therefore, the “steering angle set according to the second target turning angle” can be obtained by multiplying the second target turning angle by the steering gear ratio.

  FIG. 3 is a control block diagram of the steering controller 10 of the first embodiment. As shown in FIG. 3, the steering controller 10 includes a turning angle calculation unit 10a, an angle servo calculation unit 10b, and a steering reaction force calculation unit. 10c, an automatic turning calculation unit (steering reaction force estimation means) 10d, a target deviation angle correction unit 10e, and a turning reaction force correction unit 10f.

  The automatic turning calculation unit 10d has a second target turning angle in the automatic turning control and a first target turning angle according to the steering angle and the vehicle speed during the automatic turning control in which the automatic turning SW 15 is ON. The target deviation angle which is the deviation of is calculated. The calculated target deviation angle is output to the target deviation angle correction unit 10e. Note that the automatic turning calculation unit 10d does not output the target deviation angle (outputs 0) during the normal control in which the automatic turning SW 15 is OFF.

Further, the automatic turning calculation unit 10d calculates an estimated turning reaction force with reference to the following formula. The calculated estimated turning reaction force is output to the turning reaction force correction unit 10e.
Fr ^ = 1/2 × M × V ² / r
here,
Fr ^: Estimated steering reaction force
M: Vehicle weight
V: Vehicle speed
1 / r: Lane curvature (r is the radius of the lane determined from the image captured by the camera 14)
1/2 means the steering reaction force of the front wheels.

The target deviation angle correction unit 10e outputs a target turning angle addition amount corresponding to the target deviation angle input from the automatic turning calculation unit 10d. The output target turning angle addition amount is added to the target turning angle output from the turning angle calculation unit 10a. As shown in FIG. 4, the target turning angle addition amount is a value proportional to the absolute value of the target deviation angle when the absolute value of the target deviation angle is not more than a predetermined value | α | When the absolute value of the target deviation angle exceeds a predetermined value | α |, a constant value is set. Further, when the target deviation angle is 0, that is, during the normal control in which the automatic turning SW 15 is OFF, 0 is output. Here, the predetermined value α is a target deviation angle (for example, a turning angle) that does not give a driver a sense of incongruity even when the front wheels 2 and 2 are steered without rotating the steering wheel 1. About 0.3 °).
In the first embodiment, steering and turning in the right direction as viewed from the driver are positive (+), and steering and turning in the left direction are negative (-).

The turning angle calculation unit 10a sets the target yaw rate of the vehicle according to the steering angle and the vehicle speed, and calculates the first target turning angle of the front wheels 2 and 2 for obtaining the set target yaw rate.
The angle servo calculation unit 10b calculates a second target turning angle obtained by adding the target turning angle addition amount output from the target deviation angle correction unit 10e to the first target turning angle calculated by the turning angle calculation unit 10a. The steering command electric current which makes this 2nd target turning angle and an actual turning angle (actual turning angle) correspond is calculated, and the turning motor 7 is servo-controlled. As described above, the target turning angle addition amount output from the target deviation angle correction unit 10e is 0 during normal control in which the automatic turning SW 15 is OFF. Therefore, during normal control, the first target turning angle and the second target turning angle obtained by adding the target turning angle addition amount to the first target turning angle coincide with each other.

  The turning reaction force correction unit 10f includes an actual turning reaction force (actual turning reaction force) detected by the rack axial force sensor 11, an estimated turning reaction force calculated by the automatic turning calculation unit 10d, The signal of the automatic steering switch 15 is input, and the steering reaction force difference corrected so as to cancel only the steady component of the steering reaction force difference that is the difference between the actual steering reaction force and the estimated steering reaction force is steered. It outputs to the reaction force calculating part 10c.

FIG. 5 is a block diagram of the turning reaction force correction unit 10f of the first embodiment. The turning reaction force correction unit 10f includes a differencer 16a, a differencer 16b, a multiplier 16c, an integrator 16d, A differentiator 16e.
The differentiator 16a outputs a difference in turning reaction force, which is a difference between the actual turning reaction force and the estimated turning reaction force, to the differentiator 16b and the differencer 16e.
The difference unit 16b outputs the difference between the turning reaction force difference, which is the output of the difference unit 16a, and the turning reaction force correction value, which is the output of the integrator 16d, to the multiplier 16c.

The multiplier 16c outputs, to the integrator 16d, a value obtained by multiplying the difference between the turning reaction force difference and the turning reaction force correction value, which is the output of the difference unit 16b, by the integral gain K. Here, the integral gain K is
K = K1 x K2 x K3 x K4 x K5 (0 to 1)
However, K1, K2, K3, K4, and K5 are gains.

Hereinafter, a method for setting each gain will be described.
As shown in FIG. 6, the gain K1 is ₀ when the curvature of the lane is equal to or less than the predetermined straight line determination threshold 1 / r ₀ and until the curvature exceeds the straight line determination threshold 1 / r ₀ and reaches a predetermined value. The larger the curvature is, the larger the value is. When the curvature exceeds the predetermined value 1 / r ₁ , the constant is the maximum. Here, the straight line determination threshold 1 / r ₀ is a curvature value with which it can be determined that the vehicle is traveling on a straight road.

As shown in FIG. 7, the gain K2 is a constant maximum value when the absolute value of the difference between the actual turning reaction force and the estimated turning reaction force (steering reaction force difference) is equal to or less than a predetermined value ΔF ₀ . When the absolute value of the difference between the actual turning reaction force and the estimated turning reaction force exceeds a predetermined value ΔF ₀ , the absolute value is made smaller as the absolute value is larger.

  As shown in FIG. 8, the gain K3 is a constant maximum value when the differential value of the estimated turning reaction force is equal to or less than the predetermined value Fr0 ^ ', and the differential value of the estimated steering reaction force is the predetermined value Fr0 ^'. When exceeding, the smaller the value, the smaller the value.

  As shown in FIG. 9, the gain K4 is set to a constant maximum value when the actual steering reaction force differential value is less than or equal to the predetermined value Fr0 ′, and the actual steering reaction force differential value exceeds the predetermined value Fr0 ′. In some cases, the larger the differential value, the smaller the value.

Here, instead of the differential value of the actual turning reaction force, the differential value of the yaw rate detected by the yaw rate sensor 13 may be used. Further, a lateral acceleration sensor that detects a lateral acceleration acting on the vehicle may be provided, and a differential value of the lateral acceleration detected by the lateral acceleration sensor may be used. That is, the parameter for setting the gain K5 only needs to indicate a change in turning behavior.
The gain K5 is set to 0 when the automatic steering control signal input from the automatic steering switch 15 is OFF, and is set to 1 when the signal is ON.

The integrator 16d outputs the turning reaction force correction value obtained by integrating the output of the multiplier 16c to the difference unit 16b and the difference unit 16e.
The differentiator 16e outputs the difference between the turning reaction force difference and the turning reaction force correction value, that is, the corrected turning reaction force difference to the steering reaction force calculation unit 10c.

  As can be seen from the foregoing, during the normal control in which the automatic turning SW 15 outputs an OFF signal, the turning reaction force correction value is 0 because the gain K5 = 0 to the integral gain K = 0. Therefore, during normal control, the steering reaction force correction unit 10f outputs the steering reaction force difference as it is to the steering reaction force calculation unit 10c without correcting the steering reaction force difference that is the difference between the actual steering reaction force and the estimated steering reaction force. To do.

  On the other hand, during automatic turning control in which the automatic turning SW 15 outputs an ON signal, K5 = 1, so the integral gain K is set according to the gains K1, K2, K3, and K4, and the turning reaction force difference Is corrected so as to approach 0, and the corrected steering reaction force difference is output to the steering reaction force calculation unit 10c.

  Further, the turning reaction force correction unit 10f gradually sets the turning reaction force correction value to 0 when the automatic turning control is switched from ON to OFF (when the automatic turning control is shifted to the normal control). This can be realized, for example, by providing a block that gradually reduces the turning reaction force correction value output from the integrator 16c as shown in FIG. 10 inside the integrator 16c. Thereby, when canceling the automatic turning control, the turning reaction force correction value can be gradually reduced to 0 in a time a that does not give the driver a sense of incongruity.

  The steering reaction force calculation unit 10c receives the steering angle input from the steering angle sensor 6, the corrected steering reaction force difference input from the steering reaction force correction unit 10f, and the vehicle speed sensor 12 during normal control. The target steering reaction force is calculated according to the vehicle speed, and the reaction force motor 5 is driven by calculating the steering reaction force command current of the reaction force motor 5 from which the target steering reaction force is obtained. The target steering reaction force is set to a larger value as the steering angle is larger, the difference in turning reaction force is larger, or the vehicle speed is higher.

  The steering reaction force calculator 10c turns the steering when the absolute value of the target deviation angle input from the automatic steering calculator 10d exceeds a predetermined value | α | A reaction force motor that calculates the target steering reaction force according to the corrected steering reaction force difference input from the reaction force correction unit 10f and the vehicle speed input from the vehicle speed sensor 12, and obtains this target steering reaction force. 5 is operated to drive the reaction force motor 5. The target steering reaction force is set to a larger value as the steering reaction force difference is larger or the vehicle speed is higher.

  On the other hand, the steering reaction force calculation unit 10c performs the target operation when the absolute value of the target deviation angle input from the automatic steering calculation unit 10d is equal to or less than a predetermined value | α | The steering reaction force is set to zero.

  Here, the estimated turning reaction force calculated from the curvature of the lane is approximately the turning reaction force received when the lane is traveling at the target turning angle of the automatic turning control when the estimation error is 0. Match. The reason is that the target turning angle at the time of automatic turning control is set according to the curvature of the lane ahead of the host vehicle, similarly to the estimated turning reaction force.

  Therefore, the application of the steering reaction force according to the difference in the steering reaction force is performed by setting the steering angle of the steering wheel 1 so that the steering angle of the front wheels 2 and 2 is steered to the future second target turning angle. This is equivalent to guiding to a steering angle set according to the turning angle (a steering angle determined by multiplying the second target turning angle by the steering gear ratio). Here, the future second target turning angle is a target turning angle that is calculated in the next or subsequent calculation cycle.

Next, the operation will be described.
In general, when automatic steering control such as lane keeping control is performed in a so-called SBW system in which the steering wheel and the steering mechanism for steering the front wheels are mechanically separated, the target deviation angle is set to the front wheels 2 and 2. The method of reflecting the turning angle of
1. Apply the steering reaction force command current according to the target deviation angle to the reaction force motor, rotate the handle and change the steering angle by the angle corresponding to the target deviation angle, to the target turning angle of the steering motor. How to reflect the target deviation angle
2. It is possible to add the target deviation angle directly to the target turning angle of the steering motor without rotating the steering wheel.

  Here, when a steering reaction force command current corresponding to the target deviation angle is given to the reaction motor, the steering wheel is automatically rotated so that the target deviation angle is reflected in the target turning angle and the front wheels are steered. The steering reaction force from the road surface is not transmitted by the given steering reaction force command current, which gives the driver a feeling of strangeness.

  On the other hand, when the target deviation angle of automatic steering control is added directly to the target steering angle, only the front wheels are automatically steered, so the steering wheel does not rotate and the driver recognizes the turning of the vehicle from the vehicle behavior alone. There must be. When a large vehicle behavior change occurs in this state, the steering angle and the vehicle behavior deviate, which gives the driver a sense of discomfort.

  In contrast, in the first embodiment, during the automatic turning control, when the absolute value of the target deviation angle does not give the driver a sense of incongruity | α | or less, the steering wheel 1 is not rotated and the target deviation angle is adjusted. When only the front wheels 2 and 2 are steered and the absolute value of the target deviation angle exceeds | α |, the steering wheel 1 is rotated to the steering angle set according to the target steered angle.

  That is, when a change in vehicle behavior occurs without rotating the steering wheel 1, the deviation of the steering angle with respect to the actual turning angle of the front wheels 2 and 2 is suppressed to a range that does not give the driver a sense of incongruity. It is possible to prevent a sense of incongruity caused by the mismatch.

  Further, in the first embodiment, during the automatic steering control, only the steering reaction force obtained by removing the steady component from the steering reaction force difference that is the difference between the actual steering reaction force and the estimated steering reaction force is applied to the handle 1. . And as mentioned above, since the estimated turning reaction force is calculated based on the curvature of the lane calculated from the lane mark ahead of the host vehicle recognized by the camera 14, when the estimation error is assumed to be 0, This substantially coincides with the turning reaction force when the lane is traveling at the target turning angle.

  That is, by generating a steering reaction force that eliminates the deviation between the actual steering reaction force and the estimated steering reaction force, the steering angle of the steering wheel 1 is changed to the steering angle set according to the next target steering angle. Can be guided. Thereby, the followability of the vehicle when the target turning angle increases as in the early stage of turning can be improved, and the traceability of the vehicle with respect to the target track of automatic turning control is improved.

  Further, in the turning reaction force correcting unit 10f, the integrator 16 removes the steady component of the turning reaction force difference. Here, the steady component of the steering reaction force difference includes an estimation error of the estimated steering reaction force due to a change in the vehicle weight, a detection error of the lane curvature, etc., so the steady component of the steering reaction force difference is eliminated. Is equivalent to eliminating the estimation error of the estimated steering reaction force. In other words, since the estimated turning reaction force can be accurately calculated, the steering angle at which the steering reaction force becomes zero can be accurately shifted to the steering angle set according to the target turning angle, and the turning angle can be reduced. Accurate control to the target turning angle.

  Further, when the vehicle enters a steady turning state after entering the curve, the difference between the actual turning reaction force and the estimated turning reaction force is 0, so the turning reaction force difference corrected by integration is 0, When the steering angle coincides with the steering angle set according to the target turning angle, the steering reaction force becomes zero. When the driver performs corrective steering from left to right from this state, the steering wheel 1 is only subjected to a natural reaction force that returns the steering wheel 1 to the steering angle set according to the target turning angle. It is possible to prevent the handle 1 from being restrained.

Further, in the turning reaction force correction unit 10f of the first embodiment, the turning reaction force correction is performed when the detected curvature of the lane is equal to or less than the straight line determination threshold 1 / r ₀ , that is, when traveling on a straight road. The value is set to 0, and the steering reaction force difference is output as it is to the steering reaction force calculation unit 10c. This is because, in order to move the vehicle straight on a straight road, it is desirable to set the steering angle at which the steering reaction force becomes zero as the steering angle set in accordance with the turning angle when the vehicle goes straight. If the steering angle at which the steering reaction force is 0 is shifted while traveling on a straight road, it is difficult to move the vehicle straight, and therefore it is not preferable to shift the steering angle at which the steering reaction force is 0.

Further, in the turning reaction force correction unit 10f, when the absolute value of the turning reaction force difference exceeds the predetermined value ΔF ₀ , the integral speed of the change amount of the turning reaction force difference is lowered as the absolute value increases. . That is, when the absolute value of the steering reaction force difference is large, the steering angle at which the steering reaction force becomes zero is quickly shifted to the steering angle set according to the target turning angle, rather than eliminating the estimation error. By prioritizing this, it is possible to ensure the vehicle's followability to the target track.

In the turning reaction force correcting unit 10f, when the differential value of the estimated turning reaction force is equal to or less than the predetermined value Fr0 ^ ', the maximum value is set to a constant maximum value, and the differential value of the estimated turning reaction force exceeds the predetermined value Fr0 ^'. In some cases, the larger the differential value, the smaller the value. That is, in Example 1, when the absolute value of the steering reaction force difference exceeds the predetermined value F ₀ as described above, even if the error of the estimated steering reaction force obtained from the curvature of the lane is large, the integral speed And the estimation error cannot be made quickly. Therefore, when the estimated turning reaction force is not changed, the estimation error can be eliminated early by increasing the integral speed. Note that since the estimated turning reaction force has not changed, the followability of the vehicle to the target track is not impaired even if the integral speed is increased.

  Further, in the turning reaction force correcting unit 10f, when the differential value of the actual turning reaction force is equal to or less than the predetermined value Fr0 ′, the turning reaction force correction unit 10f is set to a constant maximum value, and the actual turning reaction force differential value exceeds the predetermined value Fr0 ′. In some cases, the larger the differential value, the smaller the value. Here, the differential value of the actual turning angle indicates that the turning behavior of the vehicle is changing. That is, when the turning behavior of the vehicle is changing, the change in the turning behavior can be transmitted to the driver as the change in the steering reaction force by reflecting it in the steering reaction force.

  Furthermore, in the turning reaction force correction unit 10f, when the automatic turning control is turned from ON to OFF, the turning reaction force correction value is gradually set to zero. For example, if the turning reaction force correction value is set to 0 at the same time when the automatic turning control is switched to the normal control, the target steering reaction force generated according to the turning reaction force rapidly increases, and the driver may feel uncomfortable. is there. Thus, in the first embodiment, the steering reaction force correction value is gradually set to 0 in a time a that does not give the driver a sense of incongruity, so that a sudden change in the steering reaction force when returning to normal control can be suppressed. .

Next, the effect will be described.
The vehicle steering control apparatus according to the first embodiment has the following effects.

  (1) During the automatic turning control, the steering controller 10 integrates the change amount of the turning reaction force difference, which is the difference between the detected turning reaction force and the estimated turning reaction force. The correction value is calculated, the steering reaction force according to the difference between the turning reaction force difference and the turning reaction force correction value, and the steering angle set according to the target turning angle (second target turning angle) A steering reaction force obtained by adding a steering reaction force based on a deviation from the actual steering angle is applied to the handle 1. Thereby, the steering angle at which the steering reaction force becomes 0 can be positively shifted according to the target turning angle that changes every moment, and the uncomfortable feeling given to the driver can be suppressed.

(2) When the detected curvature is equal to or less than the predetermined straight line determination threshold value 1 / r ₀ , the steering controller 10 sets the turning reaction force correction value to 0, and thus the steering reaction force becomes 0 on a straight road. It is possible to prevent the vehicle from becoming difficult to travel straight by shifting the corner.

  (3) Since the steering controller 10 lowers the integration speed of the change amount of the steering reaction force difference as the absolute value of the steering reaction force difference is larger, the followability of the vehicle to the target track can be ensured.

  (4) The steering controller 10 increases the integration speed of the change amount of the steering reaction force difference as the estimated differential value of the steering reaction force is smaller. Can be achieved.

  (5) Since the steering controller 10 lowers the integrated speed of the change amount of the steering reaction force difference as the change in the vehicle behavior is larger, the change in the turning behavior can be transmitted to the driver as a change in the steering reaction force.

  (6) When the automatic steering control is canceled, the steering controller 10 gradually returns the steering angle at which the steering reaction force becomes 0 to the steering angle at the time of straight traveling of the vehicle. Can be suppressed.

  (7) Steering reaction force is estimated from the curvature of the road on which the vehicle is traveling, and the steering reaction force, which is the difference between the detected steering reaction force and the estimated steering reaction force during automatic steering control The change amount of the difference is integrated to calculate the turning reaction force correction value, the steering reaction force according to the difference between the turning reaction force difference and the turning reaction force correction value, and the target turning angle (second target turning angle). A steering reaction force obtained by adding a steering reaction force based on a deviation between the steering angle set in accordance with the steering angle and the actual steering angle is applied to the handle 1. Thereby, the steering angle at which the steering reaction force becomes 0 can be positively shifted according to the target turning angle that changes every moment, and the uncomfortable feeling given to the driver can be suppressed.

(Other examples)
The best mode for carrying out the present invention has been described above based on the embodiments. However, the specific configuration of the present invention is not limited to the embodiments and is within the scope of the invention. Any design changes are included in the present invention.

  For example, in the embodiment, during the automatic turning control, the steering reaction force is not generated when the absolute value of the target deviation angle is equal to or less than | α |. However, the present invention is not limited to this, and the actual turning reaction is not limited thereto. A small steering reaction force corresponding to the magnitude of the steering reaction force difference, which is the difference between the force and the estimated steering reaction force (for example, steering calculated when the absolute value of the target deviation angle exceeds | α | (Reaction force × 0.1 or the like) may be applied.

1 is an overall configuration diagram of a steer-by-wire system to which a vehicle steering control device according to a first embodiment is applied. It is a gain map of lane keep control. FIG. 3 is a control block diagram of the steering controller 10 according to the first embodiment. 3 is a target turning angle addition amount setting map according to a target deviation angle of the first embodiment. It is a block diagram of the steering reaction force correction | amendment part 10f of Example 1. FIG. 6 is a setting map of a gain K1 according to the first embodiment. 6 is a setting map of a gain K2 according to the first embodiment. 3 is a setting map for a gain K3 according to the first embodiment. 3 is a setting map of a gain K4 according to the first embodiment. It is explanatory drawing which shows the steering reaction force correction method at the time of transfering from automatic steering control in Example 1 to normal control.

Explanation of symbols

1 Handle 2 Front wheel (steering wheel)
3 Steering mechanism 4 Column shaft 5 Reaction force motor 6 Steering angle sensor 7 Steering motor 8 Pinion shaft 9 Steering angle sensor 10 Steering controller (reaction force control means)
10a Steering angle computing unit 10b Angle servo computing unit 10c Steering reaction force computing unit 10d Automatic steering computing unit (steering reaction force estimating means)
10e Target deviation angle correction unit 10f Steering reaction force correction unit 11 Rack axial force sensor (steering reaction force detection means)
12 Vehicle speed sensor 13 Yaw rate sensor 14 Camera (curvature detection means)
15 Automatic steering switch 16 Rack

Claims (7)

The steering mechanism and the steering mechanism that steers the steering wheel are mechanically separated,
Based on the first target turning angle set according to the steering angle of the steering wheel, the normal control for controlling the turning angle of the steered wheels and the second target turning set according to the traveling state of the vehicle. In a vehicle steering control device that executes automatic steering control that controls a steering angle of the steered wheel based on a steering angle,
Steering reaction force detecting means for detecting the steering reaction force acting on the steering wheel,
Curvature detection means for detecting the curvature of the road on which the vehicle travels;
A steering reaction force estimating means for estimating a steering reaction force from the detected curvature;
During automatic turning control, the amount of change in the turning reaction force difference, which is the difference between the detected turning reaction force and the estimated turning reaction force, is integrated to calculate a turning reaction force correction value. Reaction force control means for applying a steering reaction force to the steering wheel according to the difference between the steering reaction force difference and the steering reaction force correction value;
A vehicle steering control device comprising: The vehicle steering control device according to claim 1,
The vehicle steering control device, wherein the reaction force control means sets the turning reaction force correction value to 0 when the detected curvature is equal to or less than a predetermined straight line determination threshold value. The vehicle steering control device according to claim 2,
The vehicle steering control device, wherein the reaction force control means lowers the integration speed of the change amount of the steering reaction force difference as the absolute value of the steering reaction force difference increases. In the vehicle steering control device according to claim 3,
The vehicle steering control device, wherein the reaction force control means increases the integral speed of the change amount of the steering reaction force difference as the estimated differential value of the steering reaction force is smaller. The vehicle steering control device according to any one of claims 1 to 3,
The vehicle steering control device, wherein the reaction force control means lowers the integration speed of the change amount of the steering reaction force difference as the change in vehicle behavior is larger. The vehicle steering control device according to any one of claims 1 to 5,
When the automatic steering control is canceled, the reaction force control means gradually returns the steering angle at which the reaction force becomes 0 to the steering angle when the vehicle goes straight ahead. Normal control for controlling the steering angle of the steered wheel based on the first target steered angle set according to the steering angle of the steering wheel mechanically separated from the steered mechanism that steers the steered wheel And a vehicle steering control method for executing automatic steering control for controlling a steering angle of the steered wheel based on a second target steering angle set in accordance with a traveling state of the vehicle.
Estimate the steering reaction force from the curvature of the road on which the vehicle travels,
During automatic turning control, the amount of change in the turning reaction force difference, which is the difference between the detected turning reaction force and the estimated turning reaction force, is integrated to calculate a turning reaction force correction value. A steering control method for a vehicle, wherein a steering reaction force corresponding to a difference between a steering reaction force difference and a steering reaction force correction value is applied to the steering wheel.

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