JP2010137745A - Vehicle steering controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle steering controller continuing steer-by-wire control while reducing rapid changes in vehicle behaviors. <P>SOLUTION: The vehicle steering controller includes a steering angle detection means for detecting a steering angle of a steering wheel. The controller controls as follows: That is, if no abnormality is detected in a plurality of steering motors by a normal determination means, a command steering angle with respect to a steering motor is calculated based on the steering angle, and the plurality of steering motors are controlled so that an actual steering angle matches the command steering angle. If an abnormality of any one of the plurality of steering motors is detected by an abnormality determination means, the driving of the abnormal steering motor is prohibited. Additionally, a command steering angle is calculated by adding to an actual steering angle an angle difference decreasing amount that is a predetermined angle for decreasing the deviation between the command steering angle and the actual steering angle. Then, the normal steering motors among the plurality of steering motors are controlled so that the actual steering angle matches the command steering angle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle steering control device.

As described in Patent Document 1, in a steering control device for a vehicle, a steering wheel and a steered wheel are mechanically separated at normal times, and a steered wheel is driven by driving a steering motor based on an input to the steering handle. There is known a steer-by-wire system for turning the vehicle. In this technology, a redundant system is configured by providing a plurality of steering motors (hereinafter referred to as steered motors) and controllers for driving the steered wheels. Steer-by-wire can be continued by this system.
Japanese translation of PCT publication No. 2003-529483

  In a vehicle control apparatus that employs a steer-by-wire system as described above, for example, while traveling at a certain turning radius curve at a constant steering angle and a constant vehicle speed, the total output (torque) of a plurality of steered motors is the road surface reaction force. The torque is balanced. At this time, if several systems out of a plurality of systems including a plurality of steering motors and controllers fail and some of the steering motors cannot output a desired torque, the total output of the plurality of steering motors is The steered wheels are pushed back by the road surface reaction force, the actual steered angle becomes smaller than the command steered angle based on the steering input, and the command steered angle and the actual steered angle deviate from each other.

  At that time, in the above prior art, the abnormal system is shut off (the output torque of the steering motor of the system in which the abnormality has occurred is set to 0), and the steer-by-wire control is continued only with the normal system. However, due to the difference between the command turning angle and the actual turning angle, the vehicle has moved out of the track desired by the driver (outside the curve), and the driver increases the steering wheel to return to the desired track. And the command turning angle also increases. Since the normal system of the steering motor is controlled so as to follow the increased command turning angle, the actual turning angle may increase rapidly and the vehicle behavior may change suddenly.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vehicle steering control device capable of continuing steer-by-wire control while reducing sudden changes in vehicle behavior.

  In order to achieve the above object, the present invention includes a steering angle detection means for detecting the steering angle of the steering wheel, and the controller is a normal determination means when any abnormality of a plurality of steerings is not detected. In addition, the command turning angle for the turning motor is calculated based on the steering angle, and the plurality of turning motors are controlled so that the actual turning angle coincides with the command turning angle. When any abnormality of the steering motor is detected, the driving of the abnormal steering motor is prohibited and the deviation between the command turning angle and the actual turning angle is reduced to the actual turning angle. A normal turning motor among a plurality of turning motors is calculated such that the command turning angle is calculated by adding the angle difference reduction amount which is a predetermined angle, and the actual turning angle matches the command turning angle. It was decided to control.

  Therefore, it is possible to provide a vehicle steering control device that can continue steer-by-wire control while reducing sudden changes in vehicle behavior.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for realizing a vehicle steering control apparatus according to the present invention will be described below based on an embodiment shown in the drawings.

[System configuration]
Example 1 will be described. FIG. 1 is a system configuration diagram of the vehicle steering control device. The vehicle steering control device includes a steering handle 1, a steering shaft 9a, a pinion shaft 9b, steered wheels FL and FR, a rack 4, a backup clutch 5, first and second steered motors 6a and 6b, and a first steering wheel. The second steering controllers 11a and 11b and the pinion gear 12 are provided.

  The pinion gear 12 is a gear coupled to the pinion shaft 9b, and rotates with the rotation of the pinion shaft 9b. The pinion gear 12 and the rack 4 are coupled by a gear mechanism to form a so-called rack and pinion mechanism in which the rack 4 moves in the axial direction as the pinion gear 12 rotates.

  The rack 4 steers the steered wheels FL and FR by moving in the axial direction. The first and second steered motors 6a and 6b are connected to the pinion gear 12 via the pinion shaft 9b or directly, and apply turning torque to the pinion gear 12 to steer the steered wheels FL and FR.

  The vehicle steering control device is a so-called steer-by-wire system, and normally, the backup clutch 5 is opened to disconnect the mechanical connection between the steering shaft 9a and the pinion shaft 9b, and the first and second electric motors. The rack 8 is moved in the axial direction by the steering motors 6a and 6b, and the steered wheels FL and FR are steered.

  For example, during a failure in which both the first and second steered motors 6a and 6b cannot be driven, the backup clutch 5 is engaged to mechanically connect the steering shaft 9a and the pinion shaft 9b, and the steering handle 1 rotates. Can be mechanically transmitted to the rack 4 to allow the rack 4 to move in the axial direction by steering the steering handle 1.

  A steering angle sensor 2, a torque sensor 3, and a reaction force motor 4 are provided on the steering shaft 9a. These are provided closer to the steering handle 1 than the backup clutch 5.

  The steering angle sensor 2 and the torque sensor 3 detect the steering angle θh and the steering torque T input to the steering handle 1 by the driver, respectively, and output them to the steering reaction force controller 10. Further, the first and second steered motor angle sensors 7a and 7b detect the steered motor angles θ1 and θ2, and are output to the steering reaction force controller 10 via the first and second steered controllers 11a and 11b. The

  The steered motor angles θ1 and θ2 and the actual steered wheels FL and FR steered angles (actual steered angles θm) have a unique correlation depending on the gear ratio of the rack and pinion mechanism. The actual turning angle θm can be detected based on the turning motor angles θ1 and θ2, and the actual turning angle θm is calculated based on the turning motor angles θ1 and θ2 unless otherwise specified. Shall.

  The controllers 10, 11a, and 11b are connected to each other through the communication line 12 so that they can communicate with each other. The steering torque T and the steering angle θh input to the steering reaction force controller 10 are the first and second steering controllers 11a. , 11b, the steering motor angles θ1, θ2 input to the first and second steering controllers 11a, 11b are input to the steering reaction force controller 10 via the communication line 12, respectively.

The steering reaction force controller 10 is applied to the steering handle 1 based on the turning motor angles θ1 and θ2 detected by the first and second turning motor angle sensors 7a and 7b (that is, based on the actual turning angle θm). The force T ′ is calculated, and the reaction force motor 4 is driven based on the reaction force T ′.
Further, failure diagnosis of the reaction force motor 4 is performed, and the backup clutch 5 is engaged when the reaction force motor 4 fails.

  When the system is normal (when the backup clutch 5 is disengaged), the turning controllers 11a and 11b calculate the command turning angle θodr based on the steering angle θh, and the calculated command turning angle θodr and the turning motor angle. Based on θ1 and θ2 (based on actual turning angle θm), command currents Is1 and Is2 of the first and second turning motors 6a and 6b are calculated, and the first and second turning motors 6a and 6b are driven. And steer.

  That is, the command turning angle θodr, which is the target value of the turning angle, is calculated based on the steering angle θh, and the first and second turnings are performed based on the deviation between the command turning angle θodr and the actual turning angle θm. By calculating the command currents Is1 and Is2 of the motors 6a and 6b and driving the first and second turning motors 6a and 6b, the command turning angle θodr and the actual turning angle θm are controlled to coincide with each other. Angle control is performed.

  Further, an abnormality diagnosis for detecting an abnormality in the steering motors 6a and 6b is performed, and if both the steering motors 6a and 6b are abnormal, the backup clutch 5 is engaged.

  The command turning angle θodr based on the steering angle θh is calculated based on a ratio between a predetermined steering angle θh and the command turning angle θodr. The ratio between the steering angle θh and the command turning angle θodr is such that, for example, when the vehicle speed is high, the command turning angle θodr with respect to the steering angle θh is small, and when the vehicle speed is low, the command turning angle θodr with respect to the steering angle θh. It may be variable, such as increasing.

  In such a system, when the first and second steering motors 6a and 6b and the reaction force motor 4 are normal, the backup clutch 5 is released to apply a reaction force to the steering handle 1, and the first, Steer-by-wire control for turning by both the second turning motors 6a and 6b is executed.

  When either one of the first and second steering motors 6a, 6b is normal and the reaction force motor 4 is normal, the backup clutch 5 is released to apply a reaction force to the steering handle 1, and the first Steer-by-wire, which prohibits the driving of which one of the first and second steering motors 6a and 6b is abnormal (the output torque is 0, that is, is in a free state) and steers by one normal steering motor Execute control.

  Further, when an abnormality is detected in either the reaction motor 4 or the steering motors 6a and 6b, the backup clutch 5 is engaged and the torque output of the reaction motor 4 and the steering motors 6a and 6b is stopped. In addition, the rack 4 can be directly driven by the steering handle 1 to enable the steering by the driver's steering operation.

[Stabilization of vehicle behavior when one system fails]
The steering motors 6a and 6b output torque that balances with the road surface reaction force while traveling at a certain turning radius curve at a constant steering angle and a constant vehicle speed. At this time, when one of the steered motors 6a and 6b fails and the desired torque cannot be output, the steered wheels FL and FR are pushed back by the road surface reaction force.

  Therefore, the actual turning angle θm of the steered wheels FL and FR becomes smaller than the command turning angle θodr based on the steering angle θh, and the command turning angle θodr and the actual turning angle θm deviate. Due to this deviation, the vehicle deviates from the track desired by the driver to the out side (outside the curve).

  When the driver increases the steering wheel 1 to return to the desired trajectory, the command turning angle θodr also increases. Since the normal system is controlled so as to follow the increased command turning angle θodr, the actual turning angle θm increases rapidly (that is, the amount of change in the actual turning angle θm increases) and the vehicle behavior changes suddenly. There is a fear.

  That is, when the driver turns the steering wheel 1 to return to the desired trajectory, the deviation between the command turning angle θodr and the actual turning angle θm causes the steered wheels FL and FR to be pushed back by the road surface reaction force. In some cases, the steering angle increased by the driver may be added to the deviation caused by this, and the deviation between the command turning angle θodr and the actual turning angle θm increases. The normal system of the steering motor is controlled so that this deviation is zero, and the amount of change in the actual steering angle increases.

  Therefore, in the present application, in order to gradually reduce the deviation (angle difference) between the command turning angle θodr and the actual turning angle θm, a final command to be described later is used instead of the command turning angle θodr for the steering motors 6a and 6b. Control is performed with the turning angle θfin as the command turning angle.

  That is, when the command turning angle θodr and the actual turning angle θm deviate from each other, a correction amount (angle difference reduction amount a) that reduces the deviation (angle difference) with respect to the steering motors 6a and 6b in a direction to reduce the deviation. ) Is calculated, the final command turning angle θfin is calculated, and the steering motors 6a and 6b are controlled based on the deviation between the calculated final command turning angle θfin and the actual turning angle θm. The angle difference reduction amount a is obtained from the steering speed-angle difference reduction amount map of FIG.

  In FIG. 2, the angle difference reduction amount a is set larger as the steering speed with respect to the steering handle 1 increases. The driver feels more uncomfortable even if the actual turning angle θm changes greatly because the driver intends to steer larger (to change the amount of steered amount) more when the steering speed is higher. Not give. For this reason, the angle difference reduction amount a is set to be large, and the deviation (angle difference) between the command turning angle θodr and the actual turning angle θm is reduced as quickly as possible.

  Hereinafter, each assumed pattern shown in FIGS. 3 to 8 will be described with respect to the relationship between the command turning angle θodr and the actual turning angle θm when one of the turning motors 6a and 6b fails. In the following embodiments, the difference between the command turning angle θodr and the actual turning angle θm is defined as an angle difference Δθodr.

Note that the commanded turning angles before and after turning are set to θodr1 and θodr2, respectively, and the estimated actual turning angle θm ′ after turning is obtained by the following equation. Δθodr is the difference between θodr1 and θodr2 as described below, and the clockwise direction is positive.
Δθodr = θodr2−θodr1 (1)
θm ′ = θm + Δθodr (2)

(1. Command turning angle θodr> actual turning angle θm)
(1-1. Increased angular difference + increased cut)
FIG. 3 is a diagram showing the final command turning angle θfin and the angle difference reduction amount a when the turning is performed with the command turning angle θodr> the actual turning angle θm. The angle difference reduction amount a is always a positive value.

When the command turning angle θodr> the actual turning angle θm and the command turning angle θodr changes in the direction in which the angle difference increases, the angle difference reduction amount a is added to the estimated actual turning angle θm ′, and the final The command turning angle θfin is obtained.
θfin = θm ′ + a
= Θm + Δθodr + a (1-1)

(1-2. Decrease in angle difference + switch back)
When the turn-back is performed in a state where the command turning angle θodr> the actual turning angle θm, the case division is performed depending on whether the command turning angle θodr changes across the actual turning angle θm due to the turning-back.
Note that the command turning angle θodr changes across the actual turning angle θm means that the command turning angle θodr is less than the actual turning angle θm due to the driver's switchback or additional steering. It means the case where it changes to a value larger than θm, or the case where it changes from a value larger than the actual turning angle θm to a value less than the actual turning angle θm. It is written as “Straddle”.

(1-2-1. When θodr2 straddles θm)
FIG. 4 is a diagram illustrating a case where the command turning angle θodr crosses the actual turning angle θm by switching back. That is, the command turning angle θodr1 before switching back is larger than the actual turning angle θm before switching back, and the command turning angle θodr2 after switching back is less than the actual turning angle θm before switching back. It represents. By switching back, the angle difference between the command turning angle θodr1 before steering and the actual turning angle θm changes.

  At that time, if the commanded steering angle θodr2 after steering changes across the actual steering angle θm, the estimated actual steering angle θm ′ calculated based on the above equation (2) is the commanded steering angle after switching back. It is located on the neutral side with respect to θodr2.

Here, in order to reduce the angle difference between the estimated actual turning angle θm ′ after switching back and the command turning angle θodr2, the final command turning is performed by adding the angle difference reduction amount a to the estimated actual turning angle θm ′. The angle θfin is calculated. Note that Δθodr is a negative value because of switchback.
θfin = θm ′ + a
= Θm + Δθodr + a (3)

  However, if the value of the angle difference reduction amount a is excessive, the value of the final command turning angle θfin becomes larger than the command turning angle θodr2 after switching back.

  Since the command turning angle θodr2 after switching back corresponds to the driver's switching back steering angle, if the final command turning angle θfin is larger than θodr2, the command turning angle θodr1 before switching back and the final command turning. The amount of switchback, which is the difference from the angle θfin, becomes too small, the amount of change in the actual turning angle θm with respect to the change in the steering angle is small, and the driver feels uncomfortable.

  Therefore, when the command turning angle θodr crosses the actual turning angle θm by the driver's steering, an upper limit value is set for the angle difference reduction amount a. As a result, the value of the final command turning angle θfin is prevented from becoming larger than the command turning angle θodr2 after switching back, and the switching back amount is prevented from becoming excessively small. Therefore, the uncomfortable feeling given to the driver is reduced.

In order not to give the driver a sense of incongruity, the allowable range of the final command turning angle θfin is set to the estimated actual turning angle θm ′ <θfin <switched command turning angle θodr2
It is necessary to limit to the range. Therefore, the relationship between the final command turning angle θfin and the command turning angle θodr2 after the switch back is θfin <θodr2 (4)
If it becomes.

Here, from the above equation (3), θfin = θm + Δθodr + a <θodr2
From the above equation (1), θodr2 = θodr1 + Δθodr

Thus, using the above equation (4), θm + Δθodr + a <θodr1 + Δθodr
a <θodr1-θm
Therefore, the upper limit value amax of the angle difference reduction amount a is amax = θodr1−θm (1-2-1)
It becomes.

(1-2-2. When θodr2 does not cross θm)
FIG. 5 is a diagram illustrating a case where the command turning angle θodr does not straddle the actual turning angle θm even by switching back. Unlike FIG. 3, since the command turning angle θodr2 after the switch back is larger than the actual turning angle θ m before the switch back, the final command turning angle θ fin is on the neutral side with respect to the actual turning angle θ m before the switch back. If so, the driver will not feel uncomfortable.

Therefore, in this case, the allowable range of the final command turning angle θfin is the estimated actual turning angle θm ′ <θfin <the actual turning angle before switching back θm.
Using the above equation (3), θfin = θm + Δθodr + a <θm

Therefore, a <−Δθodr
Since the angle difference reduction amount a is always positive and Δθodr at the time of switching back is negative, the upper limit value amax of a is amax = | Δθodr | (1-2-2)
It becomes.

(2. Actual turning angle θm> command turning angle θodr)
(2-1. Angle difference decrease + increase)
Whether the command turning angle θodr changes across the actual turning angle θm as in the case of (1-2) also when the turning is performed with the actual turning angle θm> the command turning angle θodr. Cases are classified according to whether or not.

(2-1-1. When θodr2 straddles θm)
FIG. 6 is a diagram illustrating a case where the command turning angle θodr straddles the actual turning angle θm due to the additional turning. Since the actual turning angle θm> the command turning angle θodr1, the angle difference between the command turning angle θodr1 before the steering and the actual turning angle θm is changed by increasing the turning angle.

  At this time, if the command turning angle θodr changes over the actual turning angle θm by steering (the command turning angle θodr2 after steering becomes larger than the actual turning angle θm), the calculation is performed based on the above equation (2). The estimated actual turning angle θm ′ is larger than the command turning angle θodr2 after the increase.

In order to reduce the angle difference between the estimated actual turning angle θm ′ and the commanded turning angle θodr2 after rounding up, the final command turning angle θfin is calculated by subtracting the angle difference reduction amount a from the estimated actual turning angle θm ′. To do. Δθodr is a positive value because of rounding.
θfin = θm ′ + a
= Θm + Δθodr-a (6)

  Here, if the value of the angle difference reduction amount a is excessive, the amount of subtraction from the estimated actual turning angle θm ′ becomes too large and the final command turning angle θfin is smaller than the command turning angle θodr2 after being increased. turn into. Since the command turning angle θodr2 corresponds to the driver's increased steering angle, if the final command turning angle θfin is smaller than θodr2, the command turning angle θodr1 before the increase and the final command turning angle θfin The amount of additional rounding, which is the difference, becomes too small, giving the driver a sense of incongruity.

  Therefore, similarly to the above (1-2), when the command turning angle θodr2 after the steering is over the actual turning angle θm, an upper limit value is set for the angle difference reduction amount a. As a result, the value of the final command turning angle θfin is prevented from becoming smaller than the command turning angle θodr2 after being increased, and the uncomfortable feeling given to the driver is reduced.

The allowable range of the final command turning angle θfin that does not give the driver a sense of incongruity is the command turning angle θodr2 <θfin <estimated actual turning angle θm ′
It becomes. Therefore, the relationship between the final command turning angle θfin and the command turning angle θodr2 after the addition is θfin> θodr2 (7)
If it becomes.

Here, using the above equation (6), θfin = θm + Δθodr−a> θm ′
From equation (2), θm ′ = θm + Δθodr
Therefore, θm + Δθodr−a> θm + Δθodr
a <−Δθodr + θm

Since the angle difference reduction amount a is always positive, amax = | Δθodr−θm | (2-1-1)
It becomes.

(2-1-2. When θodr2 does not straddle θm)
FIG. 7 is a diagram illustrating a case in which the command turning angle θodr does not straddle the actual turning angle θm due to the additional turning. Unlike FIG. 6, if the final command turning angle θfin is larger than the actual turning angle θm before the increase, the driver will not feel uncomfortable.

Therefore, the allowable range of the final command turning angle θfin in this case is the actual turning angle before switching back θm <θfin <estimated actual turning angle θm ′.
Using the above equation (6), θm <θfin = θm + Δθodr−a

Therefore, a <Δθodr
Since the angle difference reduction amount a is always positive, the upper limit value amax of a is amax = | Δθodr | (2-1-2)
It becomes.

(2-2. Increase in angle difference + switch back)
FIG. 8 is a diagram when switching back is performed in a state where the actual turning angle θm> the command turning angle θodr. In this case, if the final command turning angle θfin is larger than the command turning angle θodr2 after switching back, the driver does not feel uncomfortable. Therefore, θfin> θodr2

From the above equation (6), θfin = θm + Δθodr−a> θodr2
Substituting θodr2 using the above equation (2), θm + Δθodr−a> θodr1 + Δθodr

Therefore, a <θm−θodr1
Since the angle difference reduction amount a is always positive, amax = | θm−θodr1 |
It becomes.

As described above, when the patterns are combined, steering is performed in a direction in which the angle difference decreases, and when the command turning angle θodr does not straddle the actual turning angle θm before turning, the angle difference reduction amount amax = | Δθodr |
When straddling, angle difference reduction amount amax = | θodr1-θm |
It becomes.

  That is, the direction in which the final command turning angle θfin changes is only the same direction as the direction in which the steering angle θh changes with respect to the command turning angle θodr2 after turning. An upper limit value is set for the angle difference reduction amount a, and the final command turning angle θfin is always positioned on the steering direction side of the driver with respect to the commanded turning angle θodr2 after turning, thereby reducing the uncomfortable feeling given to the driver. .

[Steering delay reduction control processing]
FIG. 9 is a flowchart of the steering delay reduction control by adding the angle difference reduction amount a. Hereinafter, each step will be described.

  In step S1, the vehicle speed VI, the steering angle θh, and the actual turning angle θm are read, and the process proceeds to step S2.

  In step S2, the command turning angle θodr1 is calculated based on the steering angle θh, and the process proceeds to step S3.

  In step S3, the steering speed ω is calculated based on the steering angle θh, and the process proceeds to step S4.

  In step S4, it is determined whether or not any of the first and second steered motors 6a and 6b has failed. If YES, the process proceeds to step S5, and if NO, the process proceeds to step S10.

  In step S5, an abnormal motor is shut off among the first and second steered motors 6a and 6b, and the process proceeds to step S6.

  In step S6, it is determined whether or not the difference between the command turning angle θodr1 and the actual turning angle θm is greater than or equal to a predetermined value θo. If YES, the process proceeds to step S7, and if NO, the process proceeds to step S10. The difference takes an absolute value, and the predetermined value θo is 2 ° to 3 °.

  In step S7, it is determined whether or not a flag set in step S12 described later (a flag set when final command turning angle θfin = actual turning angle θm) is set. If YES, the process proceeds to step S8. If NO, the process proceeds to step S12.

In step S8, it is determined whether or not steering is in progress (turning up or turning back the steering wheel 1). If YES, the process proceeds to step S9, and if NO, the control is terminated.
The actual turning angle θm is maintained during steering that is not turning back or turning back, and only during steering for turning back or turning back, the process proceeds to step S9 to reduce the deviation between the command turning angle θodr and the actual turning angle θm. Let
This avoids intervention of control for reducing the angle difference between the command turning angle θodr and the actual turning angle θm during non-steering, and prevents the driver from feeling uncomfortable.

  In step S9, it is determined whether or not the pre-steering command turning angle θodr1> the actual turning angle before turning θm, the process proceeds to step S14 if YES, and the process proceeds to step S16 if NO.

  In step S10, final command turning angle θfin = current command turning angle θodr is set, and the process proceeds to step S11.

  In step S11, the flag set in step S13 is cleared, and the control ends.

  In step S12, the final command turning angle θfin = actual turning angle θm is set, and the control is terminated.

  In step S13, a flag is set when the final command turning angle θfin = actual turning angle θm is set, and the control is terminated.

  In step S14, the angle difference reduction amount a in the case of θodr1> θm is calculated, and the process proceeds to step S15.

  In step S15, the final command turning angle θfin in the case of θodr1> θm is calculated, and the control is terminated.

  In step S16, the angle difference reduction amount a in the case of θodr1 <θm is calculated, and the process proceeds to step S17.

  In step S17, the final command turning angle θfin when θodr1 <θm is calculated, and the control is terminated.

[Change in steering control over time]
FIG. 10 is a comparative example, and FIG. 11 is a time chart of steering control in the present application.
(Comparative example)
(Time t1)
An abnormality occurs at time t1, and one of the first and second steered motors 6a and 6b fails. For this reason, the turning torque becomes insufficient with respect to the road surface reaction force, and the actual turning angle θm decreases although the command turning angle θodr is a constant value. The yaw rate follows with a delay.

(Time t2)
At time t2, the actual turning angle θm is controlled to follow the command turning angle θodr, and the actual turning angle θm increases.

(Time t3)
At time t3, the driver performs additional turning, and the command turning angle θodr and the actual turning angle θm increase.

(Time t4)
At time t4, the switch is made from switching back to switching back.

(Time t5)
At time t5, the steering is maintained. From time t1 to time t5, the yaw rate follows the actual turning angle θm with a delay.

(This application)
(Time t11)
An abnormality occurs at time t11, and one of the first and second steered motors 6a and 6b fails. For this reason, the turning torque becomes insufficient with respect to the road surface reaction force, and the actual turning angle θm decreases although the command turning angle θodr is a constant value. The yaw rate follows with a delay.
When the angle difference (difference) between the command turning angle θodr and the actual turning angle θm is equal to or greater than θo, control for reducing the angle difference is executed (FIG. 9: Step S6 and subsequent steps).

(Time t12)
At time t12, the driver enters the steering holding state. At time t12, any abnormality of the first and second steered motors 6a and 6b is established, and the angle difference reduction control is performed according to FIG. As a result, the deviation between the final command turning angle θfin and the actual turning angle θm is reduced.

(Time t13)
At time t13, the driver performs additional rounding.

(Time t14)
At time t14, steering by the driver is performed.

(Time t15)
At time t15, the driver performs switching back.

[Effect of Example 1]
(1) a steering handle 1 that can be steered by a driver;
Steered wheels FL and FR mechanically separated from the steering handle 1;
A plurality of steered motors 6a, 6b for imparting steered torque to the steered wheels FL, FR;
Steering controllers 11a and 11b for controlling the steering motors 6a and 6b;
Steering angle detection means (steering angle sensor 2) for detecting the steering angle θh of the steering handle 1;
Steering angle detection means (steering motor angle sensors 7a, 7b) for detecting the actual turning angle θm that is the turning angle of the steered wheels FL, FR;
In the vehicle steering control device including abnormality determination means (step S4) for determining abnormality of the plurality of steered motors 6a and 6b,
The steering controllers 11a and 11b are
If any abnormality of the plurality of turnings is not detected by the abnormality determining means, the turning angle θodr for the turning motors 6a and 6b is calculated based on the steering angle θh, and the actual turning angle θm is calculated. The plurality of steered motors 6a and 6b are controlled so as to coincide with the command steered angle θodr,
If any abnormality of the plurality of steering motors 6a, 6b is detected by the abnormality determining means, the driving of the steering motors 6a, 6b that has become abnormal is prohibited and the actual turning angle θm is set. The command turning angle θodr is calculated by adding the angle difference reduction amount a which is a predetermined angle for reducing the deviation between the command turning angle θodr and the actual turning angle θm, and the actual turning angle θm is determined as the command turning. A normal steering motor among the plurality of steering motors 6a and 6b is controlled so as to coincide with the angle θodr.

As a result, when one of the plurality of steered motors 6a and 6b becomes abnormal and the desired steered torque cannot be output, the steered wheels FL and FR are pushed back by the road surface reaction force, and the driver pushes the steering handle 1. Even when the steering is suddenly performed, the deviation (angle difference) between the command turning angle θodr and the actual turning angle θm is reduced.
Therefore, even when the driver suddenly increases or decreases the steering wheel 1, the vehicle behavior can be stabilized by suppressing a sudden change in the actual turning angle θm.

  (2) The steering controllers 11a and 11b maintain the actual turning angle θm during the steering by the driver when any abnormality of the plurality of steering motors 6a and 6b is detected by the abnormality determination unit. Only during the steering by the driver, the command turning angle θodr is calculated by adding the angle difference reduction amount a that reduces the deviation between the command turning angle θodr and the actual turning angle θm to the actual turning angle θm. It was.

  Thereby, the angular difference between the normal motor command turning angle θodr and the actual turning angle θm can be reliably reduced. Further, it is possible to avoid the intervention of the control for reducing the angle difference between the command turning angle θodr and the actual turning angle θm during non-steering, and to prevent the driver from feeling uncomfortable.

  (3) The angle difference reduction amount a is set to increase as the steering speed ω with respect to the steering handle 1 increases.

  Since the driver intends to steer larger as the steering speed increases at the time of increase in the number of gears, the angle difference reduction amount a is set to a larger value, and the angle difference between the commanded steering angle θodr and the actual turning angle θm is promptly increased. Can be reduced.

  (5) The turning controllers 11a and 11b add the angle difference reduction amount a to the actual turning angle θm so that the command turning angle θodr changes in the same direction as the change direction of the steering angle θh.

In order to quickly reduce the angle difference between the command turning angle θodr and the actual turning angle θm, the final command turning angle θfin is set to the command turning angle θodr1 before turning from the command turning angle θodr2 after turning. It may be desirable to change the position to the side, but in that case, the driver may feel uncomfortable.
Accordingly, an upper limit value is provided for the angle difference reduction amount a, and the final command turning angle θfin is always positioned on the steering direction side of the driver with respect to the commanded turning angle θodr2 after turning, thereby reducing the uncomfortable feeling given to the driver. can do.

  (6) The steering controllers 11a and 11b change the command turning angle θodr in the direction in which the deviation between the command turning angle θodr and the actual turning angle θm increases due to the driver's steering operation, and When the steering turning angle θodr is changed from a value smaller than the actual turning angle θm to a larger value or from a value larger than the actual turning angle θm to a smaller value, an upper limit value of the angle difference reduction amount a is set. It was.

  As a result, the final command turning angle θfin can always be positioned on the steering direction side of the driver with respect to the commanded turning angle θodr2 after turning, and the uncomfortable feeling given to the driver can be surely reduced.

  Example 2 will be described. The basic configuration is the same as that of the first embodiment. In the first embodiment, the angle difference reduction amount a is calculated based on the steering speed (see FIG. 2), but the second embodiment is different in that it is calculated based on the vehicle speed.

  FIG. 12 is a map of the vehicle speed-angle difference reduction amount a. FIG. 13 is a vehicle speed-yaw rate gain map. The vehicle speed-yaw rate gain map function is an inverse function of the vehicle speed-angle difference reduction amount a map.

  The yaw rate gain that increases the yaw rate as the vehicle speed increases is set according to FIG. In this case, since the vehicle behavior change with respect to the steering input changes depending on the yaw rate gain, in FIG. 12, the angle difference reduction amount a is set large in the low vehicle speed region where the yaw rate gain is small and the vehicle behavior change due to the yaw rate is small.

  Since both the angle difference reduction amount a and the yaw rate cause an increase in vehicle behavior change due to an increase in value, the angle difference reduction amount a is set to be large in a low vehicle speed region where the yaw rate is small, and the angle difference is reduced in a high vehicle speed region where the yaw rate is small. By setting the amount a small, a sudden change in vehicle behavior is avoided while ensuring the value of the angle difference reduction amount a.

[Effect of Example 2]
(4) The angle difference reduction amount a is set to be larger as the yaw rate gain, which is a change in the yaw rate of the vehicle with respect to the change in the steering angle θh of the steering wheel 1, is smaller.

  The smaller the yaw rate, the smaller the change in vehicle behavior during steering. Therefore, when the gain based on the yaw rate is small, the vehicle behavior is suppressed to a small value even when the angle difference reduction amount a is set large. Therefore, the angle difference reduction amount a can be set large, and the angle difference between the command turning angle θodr and the actual turning angle θm can be quickly reduced.

[Other embodiments]
The best mode for carrying out the present invention has been described based on the embodiments. However, the specific configuration of the present invention is not limited to each embodiment, and the scope of the invention is not deviated. Design changes and the like are included in the present invention.

It is a system block diagram of the steering control device for vehicles of this application. It is a steering speed-angle difference reduction amount map. It is a figure at the time of rounding up in the state of command turning angle> actual turning angle. It is a figure which shows the case where the command turning angle after steering crosses an actual turning angle by switchback. It is a figure which shows the case where the command turning angle after steering does not straddle an actual turning angle also by switchback. FIG. 6 is a diagram showing a case where the turning is performed in a state where the actual turning angle> the command turning angle, and the command turning angle after steering crosses the actual turning angle due to the turning increase. It is a figure which shows the case where the command turning angle after rounding does not straddle the actual turning angle. It is a figure at the time of switching back in the state of actual turning angle> instruction | command turning angle. It is a flowchart of steering delay reduction control. It is a time chart of steering control in a comparative example. It is a time chart of the steering control in this application. 7 is a vehicle speed-angle difference reduction amount map according to the second embodiment. 6 is a vehicle speed-yaw rate gain map in the second embodiment.

Explanation of symbols

1 Steering handle 2 Steering angle sensor (steering angle detection means)
6a, 6b Steering motor 7a, 7b Steering motor angle sensor (steering angle detection means)
11a, 11b Steering controller (controller)
FL, FR steered wheels

Claims (6)

A steering wheel that the driver can steer;
Steered wheels mechanically separated from the steering handle;
A plurality of steering motors for applying a steering torque to the steered wheels;
A controller for controlling the steering motor;
Steering angle detection means for detecting a steering angle of the steering wheel;
A turning angle detection means for detecting an actual turning angle that is a turning angle of the turning wheel;
An abnormality determining means for determining an abnormality of the plurality of steered motors;
In a vehicle steering control device comprising:
A turning angle detecting means for detecting a turning angle of the turning wheel;
The controller is
When any abnormality of the plurality of turnings is not detected by the abnormality determining means, a command turning angle for the turning motor is calculated based on the steering angle, and the actual turning angle is set as a command. Controlling the plurality of steered motors to match the steered angle,
When any abnormality of a plurality of turning motors is detected by the abnormality determining means, the abnormality turning means prohibits the driving of the turning motor that has become abnormal and sets the actual turning angle to a command turning angle. A command turning angle is calculated by adding an angle difference reduction amount that is a predetermined angle that reduces a deviation from the actual turning angle, so that the actual turning angle matches the command turning angle. A vehicle steering control device that controls a normal steering motor among a plurality of steering motors. The vehicle steering control device according to claim 1,
The controller holds the actual turning angle during steering by the driver when any abnormality of the plurality of steering motors is detected by the abnormality determining means, and only during steering by the driver, A vehicle steering control device, wherein a command turning angle is calculated by adding an angle difference reduction amount for reducing a deviation between the command turning angle and the actual turning angle to an actual turning angle. The vehicle steering control device according to claim 1,
The angle difference reduction amount is set to be larger as the steering speed with respect to the steering handle is increased. The vehicle steering control device according to claim 1,
The vehicle steering control device according to claim 1, wherein the angle difference reduction amount is set to be larger as a yaw rate gain, which is a change in the yaw rate of the vehicle with respect to a change in the steering angle of the steering wheel, is smaller. The vehicle steering control device according to claim 2,
The controller is
A vehicle steering control device, wherein an angle difference reduction amount is added to the actual turning angle so that the command turning angle changes in the same direction as the change direction of the steering angle. The vehicle steering control device according to claim 5,
The controller changes the command turning angle in a direction in which a deviation between the command turning angle and the actual turning angle increases by a driver's steering operation, and the command turning angle is set by a driver's steering operation. A vehicular steering control device, wherein an upper limit value of the angle difference reduction amount is set when the value changes from a value smaller than the actual turning angle to a larger value or from a value larger than the actual turning angle to a smaller value.

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