JP4506386B2 - Vehicle steering system - Google Patents

Description

  The present invention belongs to the technical field of a vehicle steering apparatus including a gear ratio variable actuator that varies a steering gear ratio according to a traveling state.

  In a vehicle steering apparatus equipped with a variable gear ratio actuator, if the steering wheel is operated when the ignition switch is OFF when the system is not operating, a deviation occurs between the neutral position of the steering wheel and the neutral position of the steering wheel. Neutral deviation occurs.

Therefore, in a conventional vehicle steering system, when a neutral shift occurs when the ignition switch is turned on and the gear ratio variable system is started while the vehicle is stopped, the neutral shift is driven by driving the variable gear ratio actuator. (For example, refer to Patent Document 1).
JP 11-171034 A

  However, in the above prior art, when the neutral switch is corrected when the ignition switch is turned on while the vehicle is stopped with the driver releasing his hand from the steering wheel, the steering wheel rotates, There was a problem of giving the driver a sense of incongruity, such as making the driver think it was a malfunction.

  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 apparatus capable of correcting a neutral shift without giving a driver a sense of incongruity.

In order to achieve the above object, in the present invention,
In a vehicle steering apparatus including a variable gear ratio actuator that varies a steering gear ratio that is a ratio of a steering steering angle of a steering operation unit to a steering angle of a steered wheel,
A neutral deviation detecting means for detecting a neutral deviation of the steering wheel and the steering operation section;
Steering state detection means for detecting whether the steering operation unit is steered or steered;
Vehicle travel determination means for determining whether the vehicle body speed is other than zero and determining that the vehicle is traveling when the vehicle body speed is other than zero;
When the neutral deviation is detected, when the vehicle is running and the steering operation unit is steered, the neutral deviation correction is performed to control the variable gear ratio actuator so as to eliminate the neutral deviation. Control means ,
When the steering direction of the steering operation unit is a direction that increases the neutral deviation amount, the neutral deviation correction control means decreases the neutral deviation correction speed, and the steering direction decreases the neutral deviation amount. In some cases, the neutral shift correction speed is increased .

In the present invention, when the vehicle and the steering operation unit A traveling is steered, comprising a neutral shift correction control means for correcting the neutral shift by driving the variable gear ratio actuator, the neutral When the steering direction of the steering operation unit is a direction that increases the neutral deviation amount, the deviation correction control means decreases the neutral deviation correction speed, and the steering direction is a direction that decreases the neutral deviation amount. In order to increase the neutral deviation correction speed, it is possible to prevent the driver from feeling uncomfortable.

Hereinafter, the best mode for carrying out the present invention will be described based on Reference Example 1 and Example 1 .
(Reference Example 1)

First, the configuration will be described.
FIG. 1 is an overall system diagram of the vehicle steering apparatus of Reference Example 1.
In the vehicle steering apparatus of Reference Example 1, driver steering is performed on a column shaft 13 that connects a steering wheel (steering operation unit) 10 and a front wheel steering mechanism 12 that steers left and right front wheels (steering wheels) 11a and 11b. An angle sensor 1 and a front wheel steering actuator (variable gear ratio actuator) 5 are provided.

  The front wheel steering actuator 5 is constituted by, for example, a motor and a speed reducer, and the output shaft of the motor is connected to the column shaft 13 via the speed reducer. The front-wheel steering actuator 5 decelerates the rotation input via the column shaft 13 by the variable gear ratio according to the steering angle command value from the front-wheel steering controller 4 and outputs the reduced speed to the steering gear of the front-wheel steering mechanism 12. Thus, the steering gear ratio, which is the ratio of the steering angle to the turning angle of the front wheels 11a, 11b, is variably controlled.

  The front wheel steering controller 4 calculates a steering angle command value that eliminates the deviation between the target front wheel steering angle generated by the steering control controller 3 and the actual front wheel steering angle value, and uses the calculated steering angle command value as the front wheel steering actuator. 5 is output.

  The steering control controller 3 generates a target front wheel steering angle in accordance with the driver steering angle detected by the driver steering angle sensor 1 and the vehicle body speed detected by the vehicle speed sensor (vehicle speed detection means) 2. Output to the steering controller 4.

  The variable gear ratio system including the steering control controller 3, the front wheel steering controller 4, and the front wheel steering actuator 5 is activated when the ignition switch is turned on, and continues the gear ratio variable control until the ignition switch is turned off. . Further, the steering control controller 3 is configured such that when the gear ratio variable system is started or when the front wheel steering actuator 5 is stopped, when the neutral deviation occurs between the steering wheel 10 and the front wheels 11a and 11b, the vehicle is stopped, and When the driver holds the steering wheel 10, the front wheel steering actuator 5 is driven to correct the neutral deviation.

FIG. 2 is a control block diagram of the steering control controller 3 of the first reference example.
The steering control controller 3 includes a target value generation unit 31, a target output value generation unit 32, and a neutral deviation correction unit 33.

  The target value generation unit 31 generates a target yaw rate based on the driver steering angle and the vehicle body speed, and outputs the target yaw rate to the target output value generation unit 32.

  The target output value generation unit 32 generates a target front wheel steering angle before correction based on the target yaw rate, and generates a target front wheel steering angle based on the target front wheel steering angle before correction, the target corrected steering angle, and the neutral deviation correction flag. And output to the front wheel steering controller 4.

  The neutral deviation correcting unit 33 is a driver steering angle, a target front wheel steering angle before correction, and a front wheel ACTR angle (the operating angle of the front wheel steering actuator 5 is the sum of the front wheel ACTR angle and the driver steering angle). To determine the neutral deviation. The neutral deviation correction unit 33 generates a target correction steering angle according to the neutral deviation determination result, and outputs the target correction steering angle to the target output value generation unit 32. Further, when the neutral deviation correcting unit 33 determines that the neutral deviation is detected, the neutral deviation correcting unit 33 sets a neutral deviation correcting flag and outputs the flag to the target output value generating unit 32.

FIG. 3 is a control block diagram of the target value generation unit 31.
The target value generation unit 31 includes a vehicle model calculation unit 311 and a target value calculation unit 312. The vehicle model calculation unit 311 calculates vehicle parameters using a two-wheel model from the driver steering angle and the vehicle body speed, and outputs the vehicle parameters to the target value calculation unit 312.

  The target value calculation unit 312 calculates a target yaw rate based on the vehicle parameters and the vehicle body speed from the vehicle model calculation unit 311.

FIG. 4 is a control block diagram of the target output value generation unit 32.
The target output value generation unit 32 includes a normal time control calculation unit 321 and a control switching unit 322. The normal control calculation unit 321 calculates a target front wheel steering angle before correction using a vehicle model stored in advance from the target yaw rate.

  When the neutral deviation correction flag is reset (= 0) to the front wheel steering controller 4, the control switching unit 322 outputs the target front wheel steering angle before correction as the target front wheel steering angle, and the neutral deviation correction flag is set ( = 1), the target correction steering angle is output as the target front wheel steering angle.

FIG. 5 is a control block diagram of the neutral deviation correcting unit 33.
The neutral deviation correcting unit 33 includes a neutral deviation determining unit 331 and a corrected steering angle calculating unit 322.

  The neutral deviation determination unit 331 calculates a neutral deviation amount based on the driver steering angle, the front wheel ACTR angle, and the uncorrected target front wheel steering angle, and determines a neutral deviation (neutral deviation detection means). If the neutral deviation is determined, a neutral deviation correction flag is set. If the neutral deviation is not determined, the neutral deviation correction flag is reset. Further, the calculated neutral shift amount is output to the corrected steering angle calculation unit 332.

  The corrected steering angle calculation unit 332 calculates the target corrected steering angle based on the target front wheel steering angle before correction and the neutral deviation amount, and outputs the target correction steering angle to the target output value generation unit 32.

Next, the operation will be described.
[Vehicle model calculation]
In the steering control controller 3, the vehicle model calculation unit 311 of the target value generation unit 31 obtains vehicle parameters using a two-wheel model from the driver steering angle and the vehicle body speed as described below.

In general, assuming a two-wheel model, the yaw angular acceleration of the vehicle can be expressed by the following equation (1).
ψ ″ = a ₁₁ ψ ′ + a ₁₂ V _y + b _f1 θ (1)
Further, the lateral acceleration of the vehicle can be expressed by the following equation (2).
V _y ′ = a ₂₁ ψ ′ + a ₂₂ V _y + b _f2 θ (2)
here,


It is.

When the transfer function of the yaw rate for front wheel steering is obtained from the equations of motion of equations (1) and (2), the following equation (4) is obtained.

The yaw rate transfer function is expressed by the following equation (5) using vehicle parameters.

here,

Therefore, from equation (3), the vehicle parameters

Is required.

[Target value generation]
Next, the target value calculation unit 312 of the target value generation unit 31 obtains the target yaw rate ψ ′ ^* from the vehicle body speed V, the vehicle parameter, and the target value parameter.

The target yaw angular acceleration is represented by the following equation (7) from equation (5).
ψ " ^* = − 2ζ _{ψ ′ *} (V) ω _{ψ ′ *} (V) ψ ′ ^* (s) + ω _{ψ ′ *} (V) ² T _{ψ ′ *} (V) θ (s)
+ 1 / s × ω _{ψ '*} (V) ² (g _{ψ' *} (V) θ (s) −φ ' ^* (s))… (7)

Here, the target value parameter is set as shown in the following equation (8).

However, yrate_gain_map, yrate_omegn_map, yrate_zeta_map, and yrate_zero_map are tuning parameters.

The target yaw rate ψ ′ ^* can be obtained from the target yaw angular acceleration ψ ″ ^* by the following equation (9).
ψ ' ^* (s) = 1 / s x ψ " ^* (s)… (9)

[Target front wheel steering angle calculation before correction]
The normal time control calculation unit 321 of the target output value generation unit 32 calculates the target front wheel steering angle θ ₁ ^* before correction using the following equation (10) from the target yaw rate ψ ′ ^* .
ψ ″ ^* = a ₁₁ ψ ′ ^* + a ₁₂ V _y + b _f1 θ ₁ ^* (10)
Therefore, the target front wheel steering angle θ ₁ ^* before correction is expressed by the following equation (11).
θ ₁ ^* = (ψ ″ ^{* −} a ₁₁ ψ ′ ^{* −} a ₁₂ V _y ) / b _f1 (11)

[Neutral misalignment calculation]
The neutral deviation determination unit 331 performs neutral deviation determination based on the driver steering angle θ, the front wheel ACTR angle θ _actr, and the pre-correction target front wheel steering angle θ ₁ ^* . This neutral shift determination is performed when the ignition is turned on or when the front wheel steering actuator 5 is stopped.

First, the neutral deviation amount Δθ is calculated by the following equation (12).
Δθ = θ ₁ ^* − (θ + θ _actr )… (12)
Subsequently, the neutral deviation is determined by comparing the calculated neutral deviation amount Δθ with a neutral deviation threshold Θ _N (constant), and the neutral deviation correction flag F _N is determined.

The neutral deviation threshold value Θ _N is set based on the range in which the driver does not feel neutral deviation during straight traveling, the accuracy of drive control of the front wheel steering actuator 5, the accuracy of the rotation angle sensor of the front wheel steering actuator 5, and the like. For example, about 10 °.
When | Δθ |> Θ _N , F _N = 1 (13)
When | Δθ | ≦ Θ _N F _N = 0 (14)

[Correction steering angle calculation]
The corrected steering angle calculation unit 332 of the neutral deviation correcting unit 33 calculates the target corrected steering angle θ _N ^* from the target front wheel steering angle θ ₁ ^* before correction and the neutral deviation amount Δθ as follows.

First, it is determined whether or not the driver is holding or turning the steering wheel 10. A steering angle command value for the minimum steering angle is given as follows. As a result, it is determined from the ACTR current command value I _a transmitted from the front wheel steering controller 4 whether or not it is released.
θ _N ^* = θ + Δθ + A _θ (15)
A _θ is the minimum control rotation angle.

(1) When the ACTR current command value I _a is equal to or greater than the ACTR current value I _a0 when the steering wheel 10 that is not steered rotates, it is determined that the steering wheel is being steered, and the following processing is executed. Here, neutral deviation correction control at the time of steering is performed in which the neutral deviation is corrected by fast rotation.
^{_{θ N * = θ + Δθ-}} ∫dA 1 dt (dA 1: ACTR angular velocity constant) ... (16)

(2) ACTR current command value I _a is, when the steering wheel 10 is not fixed steering is smaller than the ACTR current value I _a0 when rotating, it is determined that the in let go, executes the following processing.
θ _N ^* = θ + Δθ−∫dA ₂ dt (dA ₂ : ACTR angular velocity constant) (17)
Here, the ACTR angular velocity constant dA ₂ ≈0 (dA ₁ > dA ₂ ) is set, and the neutral deviation correction control is performed to correct the neutral deviation at an extremely low rotation level such that the rotation of the steering wheel 10 is unknown to the driver. . Note that dA ₂ = 0, and neutral deviation correction may not be performed during hand release.

[Target front wheel steering angle calculation]
The switching section 322 of the target output value generating unit 32, corrected before the target front-wheel steering angle theta ₁ ^* and the neutral displacement correction flag F _N and the target corrective steering angle theta _N ^*, determines a target front wheel steering angle theta ^*.
When F _N = 0,
θ ^* = θ ₁ ^* (18)
As a result, normal control is performed.
When F _N = 1,
θ ^* = θ _N ^* (19)
As shown in FIG.

[Steering control processing]
FIG. 6 is a flowchart showing the flow of the steering control process executed by the steering control controller 3 of Reference Example 1, and each step will be described below.

  In step S1, it is determined whether the ignition switch is turned on. If YES, the process proceeds to step S2, and if NO, this control is terminated.

In step S2, the normal time control calculation unit 321 calculates the uncorrected target front wheel steering angle θ ₁ ^* from the steering angle θ and the vehicle body speed V, and the process proceeds to step S3.

In step S3, the neutral deviation determination unit 331 calculates a neutral deviation amount Δθ from the steering angle θ, the front wheel ACTR angle θ _actr, and the pre-correction target front wheel steering angle θ ₁ ^*, and the _{process proceeds} to step S4.

In step S4, the control switching unit 322 determines whether or not the neutral deviation correction flag F _N is 1. If YES, the process proceeds to step S5. If NO, the process proceeds to step S10.

  In step S5, the corrected steering angle calculation unit 332 determines whether the vehicle body speed V is zero, that is, whether the vehicle is stopped (corresponding to vehicle stop determination means). If YES, the process proceeds to step S6. If NO, the process proceeds to step S10.

In step S6, the corrected steering angle calculation unit 332 determines whether or not the steering wheel 10 is being held based on whether or not the ACTR current command value I _a is equal to or greater than I _a0 (corresponding to the steering state detection means). . If YES, the process proceeds to step S7, and if NO, the process proceeds to step S8.

In step S7, the corrected steering angle calculation unit 332 calculates the target corrected steering angle θ _N ^* based on the equation (16), and at the time of steering while setting the target corrected steering angle θ _N ^* as the target front wheel steering angle θ ^*. Neutral deviation correction control is executed (equivalent to neutral deviation correction control means), and the process proceeds to step S9.

In step S8, the corrected steering angle calculation unit 332 calculates the target corrected steering angle θ _N ^* based on the equation (17), and sets the target corrected steering angle θ _N ^* as the target front wheel steering angle θ ^*. The deviation correction control is executed, and the process proceeds to step S9.

In step S9, the control switching unit 322 determines whether or not the neutral deviation correction flag F _N is zero. If YES, the process proceeds to step S10. If NO, the process proceeds to step S2.

In step S10, normal control for driving the front wheel steering actuator 5 is executed with the uncorrected target front wheel steering angle θ ₁ ^* calculated by the normal-time control calculation unit 321 as the target front wheel steering angle θ ^* , and this control is terminated.

[Steering control operation]
When the neutral deviation occurs when the ignition is ON and the steering wheel 10 is steered or steered, step S1, step S2, step S3, step S4, step S5, step in the flowchart of FIG. S6 → proceeds to step S7 → step S9, the process proceeds at step S9, to neutral shift corrected until the flag F _N is zero, step S2 → step S3 → step S4 → step S5 → step S6 → step S7 → step S9 The flow is repeated.

That is, in step S7, neutral deviation correction control for driving the front wheel steering actuator 5 is performed with the target correction steering angle θ _N ^* calculated based on the equation (16) as the target front wheel steering angle θ ^* . Therefore, when the vehicle is stopped and the driver keeps or steers the steering wheel 10, the front wheel steering actuator 5 is driven at a high speed (ACTR angular velocity constant dA ₁ ), and the steering wheel accompanying the neutral deviation correction. 10 is suppressed, and the amount of neutral deviation Δθ can be corrected before starting, so that the vehicle can be prevented from turning when starting.

When the neutral deviation correction flag F _N becomes zero in step S9, the process proceeds from step S9 to step S10. That is, in step S10, normal control is performed in which the uncorrected target front wheel steering angle θ ₁ ^* calculated by the normal-time control calculation unit 321 is the target front wheel steering angle θ ^* .

If a neutral deviation occurs when the ignition is on and the driver is not steering the steering wheel 10, in the flowchart of FIG. 6, step S1, step S2, step S3, step S4, step S5, step S6 → proceeds to step S8 → step S9, the process proceeds at step S9, to neutral shift corrected until the flag F _N is zero, step S2 → step S3 → step S4 → step S5 → step S6 → step S8 → step S9 The flow is repeated.

In other words, in step S8, the neutral displacement correction control during the release of driving the front wheel steering actuator 5 is performed with the target correction steering angle θ _N ^* calculated based on the equation (17) as the target front wheel steering angle θ ^* . Therefore, when the vehicle is stopped and the driver releases his hand from the steering wheel 10, the front wheel steering actuator 5 is driven at an extremely low speed (ACTR angular velocity dA ₂ ), and the neutral deviation amount Δθ is unknown to the driver. Fixed at speed. In the equation (17), when the ACTR angular velocity dA _{2 is set} to zero, the neutral deviation amount Δθ is not corrected.

[Neutral deviation judgment control processing]
FIG. 7 is a flowchart showing the flow of the neutral deviation determination control process executed by the steering control controller 3 of Reference Example 1, and each step will be described below.

  In step S21, it is determined whether the ignition switch is turned on. If YES, the process proceeds to step S22. If NO, this control is terminated.

In step S22, the neutral deviation determination unit 331 determines whether or not the absolute value | Δθ | of the neutral deviation amount is larger than the neutral deviation threshold Θ _N. If YES, the process proceeds to step S23, and if NO, the process proceeds to step S24.

In step S23, the neutral shift determination unit 331, sets the neutral displacement correction flag F _N (= 1), and the process proceeds to step S25.

In step S24, the neutral shift determination unit 331, resets the neutral displacement correction flag F _N (= 0), and the process proceeds to step S25.

  In step S25, it is determined whether or not the ignition key switch has been turned OFF. If YES, the process proceeds to return, and if NO, the process proceeds to step S22.

[Neutral deviation judgment control operation]
When neutral deviation has occurred (| Δθ |> Θ _N ), the flow proceeds from step S21 to step S22 to step S23 to step S25 in the flowchart of FIG. 7, and in step S23, the neutral deviation correction flag is set. F _N is set (= 1).

When neutral deviation has not occurred (| Δθ | ≦ Θ _N ), the flow proceeds from step S21 to step S22 to step S24 to step S25 in the flowchart of FIG. 7, and in step S24, the neutral deviation correction flag is set. F _N is reset (= 0).

[Neutral misalignment correction]
FIG. 8 is a time chart showing the neutral deviation correcting action of Reference Example 1. At time t1, the driver's ignition is turned off, the power supply to the front wheel steering actuator 5 is stopped, and the gear ratio variable system is terminated.

  Then, since the driver steers the steering wheel 10 from the time point t1 to the time point t2 when the gear ratio variable system is not activated, at the time point t2, the driver steering angle and the actual steering angle of the front wheels 11a and 11b are During this time, a neutral deviation of the deviation amount Δθ occurs.

  At time t3, the variable gear ratio system is activated by turning on the ignition. At this time, since the vehicle is stopped and the driver is steering the steering wheel 10, neutral deviation correction control during steering is performed, and the front wheels 11 a and 11 b are steered by driving the front wheel steering actuator 5. The actual steering angle is corrected to the original target front wheel steering angle at high speed. At this time, since the steering wheel 10 is held by the driver, the rotation of the steering wheel 10 associated with neutral deviation correction is suppressed, and the driver does not feel uncomfortable.

  At time t4, since the neutral deviation is corrected, thereafter, normal control is performed until the ignition is turned off.

Next, the effect will be described.
In the vehicle steering apparatus of Reference Example 1, the effects listed below are obtained.

  (1) In a vehicle steering apparatus having a front wheel steering actuator 5 that varies a steering gear ratio that is a ratio of a steering steering angle of the steering wheel 10 to a steering angle of the front wheels 11a and 11b, the front wheels 11a and 11b and the steering wheel 10 A neutral deviation determination unit 331 for detecting a neutral deviation, a steering state detecting means for detecting whether or not the driver holds or steers the steering wheel 10, and when the neutral deviation is detected, the driver When the steering wheel 10 is steered or steered, the vehicle is provided with neutral deviation correction control means for driving and controlling the front wheel steering actuator 5 so as to eliminate the neutral deviation. Therefore, the steering wheel 10 is neutral without rotating. The misalignment can be corrected, and the uncomfortable feeling given to the driver can be prevented.

(2) It is provided with a vehicle stop determination means for determining whether the vehicle is stopped, and the neutral deviation correction control means corrects the neutral deviation when the vehicle is stopped, so that the neutral deviation can be corrected before starting. Become.
Example 1

Example 1 during running of the vehicle, an example of performing neutral shift corrected when the steering wheel is operated. In addition, since it is the same as that of the reference example 1 shown to FIGS. 1-5 about a structure, the same code | symbol is attached | subjected to the same component and description is abbreviate | omitted.

The steering control controller 3 according to the first embodiment is configured such that when a neutral shift occurs between the steering wheel 10 and the front wheels 11a and 11b when the variable gear ratio system is started or when the front wheel steering actuator 5 is stopped, When the driver is operating the steering wheel 10, the front wheel steering actuator 5 is driven to correct the neutral deviation.

Next, the operation will be described.
[Correction steering angle calculation]
The corrected steering angle calculation unit 332 of the neutral deviation correcting unit 33 calculates the target corrected steering angle θ _N ^* from the target front wheel steering angle θ ₁ ^* before correction and the neutral deviation amount Δθ as follows.

First, the steering angular velocity dθ is calculated from the driver steering angle θ by differential calculation. Here, the sign of the driver steering angle θ defines that the counterclockwise direction is + and the clockwise direction is − when viewed from the driver side. The sign of the neutral deviation amount Δθ defines the counterclockwise direction + as viewed from the driver side and the clockwise direction as −, based on the pre-correction target front wheel steering angle θ ₁ ^* .

Compare the sign of steering angular velocity dθ and neutral deviation amount Δθ,
(1) If the signs are the same (a state where Δθ is added), the following processing is executed.
θ _N ^* = θ + Δθ−G _a1 ∫dθdt (G _a1 : ACTR angular velocity gain) (20)
(2) If the signs are not identical (a state where Δθ is subtracted), the following processing is executed.
θ _N ^* = θ + Δθ + G _a2 ∫ dθdt (G _a2 : ACTR angular velocity gain) (21)
However, the ACTR angular velocity gain is set so that _Ga1 <1 < _Ga2 .

FIG. 9 is a characteristic diagram of the ACTR angular velocity gain G _a1 . As shown in the figure, the ACTR angular velocity gain G _a1 decreases as the steering angular velocity dθ increases, and approaches 1 as the vehicle body speed V increases. Is set to

FIG. 10 is a characteristic diagram of the ACTR angular velocity gain G _a2 , and as shown in the figure, the ACTR angular velocity gain G _a2 increases as the steering angular velocity dθ increases, and approaches 1 as the vehicle body speed V increases. Is set to

[Steering control processing]
FIG. 11 is a flowchart showing the flow of the steering control process executed by the steering control controller 3 according to the first embodiment. Each step will be described below. In FIG. 11, steps S31 to S34, S43, and S44 perform the same processing as steps S1 to S4, S9, and S10 shown in FIG. 6, and therefore only different steps will be described.

  In step S35, the corrected steering angle calculation unit 332 determines whether the vehicle body speed is other than zero (corresponding to vehicle travel determination means). If yes, then continue with step S36, otherwise continue with step S44.

In step S36, the corrected steering angle calculation unit 332 calculates the steering angular velocity dθ from the time differential value of the steering angle θ (corresponding to the operation speed detection means and the steering determination means), and proceeds to step S38.
In step S37, the corrected steering angle calculation unit 332 determines whether or not the steering wheel 10 is being steered based on whether or not the ACTR current command value I _a is I _a0 or more and the steering angular velocity dθ is zero or more. . If YES, the process proceeds to step S38, and if NO, the process proceeds to step S44.

  In step S38, the corrected steering angle calculation unit 332 determines whether the operation direction of the steering wheel 10 and the neutral deviation direction are the same. If YES, the process proceeds to step S39, and if NO, the process proceeds to step S40.

In step S39, the corrected steering angle calculating unit 332, a steering angular velocity d [theta] and ACTR angular velocity gain G _a1, calculates a target ACTR angular d [theta] _a, the process proceeds to step S41.

At step S40, the corrected steering angle calculating unit 332, a steering angular velocity d [theta] and ACTR angular velocity gain G _a2, it calculates a target ACTR angular d [theta] _a, the process proceeds to step S41.

In step S41, the corrected steering angle calculation unit 332 calculates the target corrected steering angle θ _N ^* from the driver steering angle θ, the neutral deviation amount Δθ, and the target ACTR angular velocity dθ _a, and the process proceeds to step S42.

In step S42, neutral deviation correction control is executed with the target correction steering angle θ _N ^* calculated in step S41 as the target front wheel steering angle θ ^*, and the process proceeds to step S43.

[Steering control operation]
When the driver is holding or turning the steering wheel 10 when the neutral deviation occurs during traveling, in the flowchart of FIG. 11, step S31 → step S32 → step S33 → step S34 → step S35 → The process proceeds from step S36 to step S37 to step S38.

Subsequently, when the operation direction of the steering wheel 10 and the neutral deviation direction are the same in step S38, the process proceeds from step S39 to step S41 to step S42 to step S43. In step S43, the neutral deviation correction flag F _N Step S32 → Step S33 → Step S34 → Step S35 → Step S36 → Step S37 → Step S38 → Step S39 → Step S41 → Step S42 → Step S43 is repeated until becomes zero.

That is, in step S39, the target ACTR angular velocity d [theta] _a is calculated by the steering angular speed d [theta] and ACTR angular velocity gain G _a1, in step S42, the target front-wheel steering angle target correction steering angle theta _N ^* on the basis of the equation (20) θ ^* As described above, neutral deviation correction control for driving the front wheel steering actuator 5 is performed. Therefore, when the steering wheel 10 is operated in a direction in which the neutral deviation amount Δθ increases, the turning speed of the front wheels 11a and 11b is moderated to suppress an increase in the neutral deviation amount Δθ associated with the operation of the steering wheel 10. However, the neutral shift is corrected so as not to give the driver a sense of incongruity.

If the operation direction of the steering wheel 10 and the neutral deviation direction are not the same in step S38, the process proceeds from step S40 to step S41 to step S42 to step S43. In step S43, the neutral deviation correction flag _FN is zero. Until this happens, the flow of step S32 → step S33 → step S34 → step S35 → step S36 → step S37 → step S38 → step S40 → step S41 → step S42 → step S43 is repeated.

That is, in step S40, the target ACTR angular velocity d [theta] _a is calculated by the steering angular speed d [theta] and ACTR angular velocity gain G _a2, at step S42, the target front-wheel steering angle target correction steering angle theta _N ^* on the basis of the equation (21) θ ^* As described above, neutral deviation correction control for driving the front wheel steering actuator 5 is performed. Therefore, when the steering wheel 10 is operated in a direction in which the neutral deviation amount Δθ decreases, the turning speed of the front wheels 11a and 11b is increased, and the neutral deviation is quickly corrected according to the steering of the driver. .

The target ACTR angular velocity d [theta] _a is, since the value obtained by multiplying the steering angular speed d [theta] to the ACTR angular velocity gain G _a1 (or G _a2), the steering holding time and running straight steering angular speed d [theta] is zero, the target front-wheel steering The angle θ ^* becomes θ + Δθ, and the neutral deviation is not corrected. Therefore, it is possible to prevent a phenomenon in which the vehicle bends or the steering wheel 10 rotates during straight traveling.

Further, as the steering angular velocity dθ is higher, G _a1 is reduced and G _a2 is increased to increase the neutral deviation correction speed. Therefore, the neutral deviation can be quickly eliminated in accordance with the driver's steering. Further, as the vehicle body speed V is higher, G _a1 and G _a2 are made closer to 1 and the neutral deviation correction speed is reduced, so that the influence on the vehicle behavior due to the neutral deviation correction can be suppressed.

[Neutral misalignment correction]
FIG. 12 is a time chart showing the neutral deviation correcting action of the first embodiment. Since the period from the time point t1 to the time point t2 is the same as that of the reference example 1 illustrated in FIG. 8, the description thereof is omitted.

  At time point t3, the gear ratio variable system is activated, but the neutral deviation correction control is not performed because the steering wheel 10 is not steered.

  At time t4, since the steering wheel 10 is steered, neutral deviation correction control is performed, and the actual steering angle is corrected to the original target front wheel steering angle at high speed. At this time, since the steering wheel 10 is steered in a direction in which the neutral deviation amount increases, the neutral deviation is corrected at a moderate speed that does not give the driver a sense of incongruity while suppressing an increase in the neutral deviation amount Δθ.

  At time t5, the neutral deviation has been corrected, and thereafter normal control is performed until the ignition is turned off. Note that, when the neutral shift occurs due to the gear ratio variable system being reset due to a communication error or the like during normal control, the neutral shift correction control is executed when the steering wheel 10 is steered.

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

  (3) The vehicle travel determination means for determining whether or not the vehicle is traveling and the steering determination means for determining whether or not the steering wheel 10 is operated. The neutral deviation correction control means includes: When the steering wheel 10 is steered, the neutral deviation is corrected, so that the neutral deviation can be corrected without giving the driver a sense of incongruity. Further, when the steering wheel 10 is not steered, the neutral deviation is not corrected, so that it is possible to prevent a phenomenon that the vehicle bends or the steering wheel 10 rotates during steering or straight traveling.

  (4) When the steering direction of the steering wheel 10 is a direction that increases the amount of neutral deviation, the neutral deviation correction control means neutralizes as the steering wheel 10 is steered in order to reduce the neutral deviation correction speed. The neutral deviation can be corrected at a moderate speed that does not give the driver a sense of incongruity while suppressing an increase in the deviation amount Δθ. Further, when the steering direction of the steering wheel 10 is a direction to reduce the neutral deviation, the neutral deviation can be corrected quickly without giving the driver an uncomfortable feeling because the neutral deviation correction speed is increased.

  (5) Steering speed detection means for detecting the steering speed (steering angular speed dθ) of the steering wheel 10 is provided, and the neutral deviation correction control means increases the neutral deviation correction speed as the steering speed increases. Neutral deviation can be quickly eliminated according to the steering.

  (6) The vehicle speed detection means for detecting the vehicle speed V is provided, and the neutral deviation correction control means lowers the neutral deviation correction speed as the vehicle speed increases, so that the influence on the vehicle behavior associated with the neutral deviation correction can be suppressed.

(Other examples)
The best mode for carrying out the present invention has been described based on Reference Example 1 and Example 1 , but the specific configuration of the present invention is not limited to the configuration of Reference Example 1 and Example 1. Even if there is a design change or the like without departing from the gist of the invention, it is included in the present invention.

For example, in Reference Example 1 and Example 1 , it is determined that the vehicle is stopped at a vehicle speed of zero. However, when the select lever of the automatic transmission is in the parking range or the parking brake is ON, the vehicle is stopped. It is judged not good.

1 is an overall system diagram of a vehicle steering apparatus according to a reference example 1; FIG. 5 is a control block diagram of a steering control controller 3 of Reference Example 1. FIG. 3 is a control block diagram of a target value generation unit 31. FIG. 3 is a control block diagram of a target output value generation unit 32. FIG. 5 is a control block diagram of a neutral deviation correcting unit 33. FIG. 4 is a flowchart showing a flow of steering control processing executed by a steering control controller 3 of Reference Example 1. 7 is a flowchart showing a flow of neutral deviation determination control processing executed by the steering control controller 3 of Reference Example 1. 10 is a time chart showing a neutral deviation correcting action of Reference Example 1. It is a characteristic diagram of ACTR angular velocity gain G _a1. It is a characteristic diagram of ACTR angular velocity gain G _a2. 4 is a flowchart illustrating a flow of a steering control process executed by the steering control controller 3 according to the first embodiment. 3 is a time chart showing a neutral deviation correcting action of the first embodiment.

DESCRIPTION OF SYMBOLS 1 Driver steering angle sensor 2 Vehicle speed sensor 3 Steering control controller 31 Target value generation part 32 Target output value generation part 33 Neutral deviation correction part 311 Vehicle model calculation part 312 Target value calculation part 321 Normal time control calculation part 322 Control switching part 331 Neutral deviation determination unit 332 Corrected steering angle calculation unit 4 Front wheel steering controller 5 Front wheel steering actuator 10 Steering wheels 11a and 11b Left and right front wheels 12 Front wheel steering mechanism 13 Column shaft

Claims (3)

In a vehicle steering apparatus including a variable gear ratio actuator that varies a steering gear ratio that is a ratio of a steering steering angle of a steering operation unit to a steering angle of a steered wheel,
A neutral deviation detecting means for detecting a neutral deviation of the steering wheel and the steering operation section;
Steering state detection means for detecting whether the steering operation unit is steered or steered;
Vehicle travel determination means for determining whether the vehicle body speed is other than zero and determining that the vehicle is traveling when the vehicle body speed is other than zero;
When the neutral deviation is detected, when the vehicle is running and the steering operation unit is steered, the neutral deviation correction is performed to control the variable gear ratio actuator so as to eliminate the neutral deviation. Control means ,
When the steering direction of the steering operation unit is a direction that increases the neutral deviation amount, the neutral deviation correction control means decreases the neutral deviation correction speed, and the steering direction decreases the neutral deviation amount. In some cases, the vehicle steering apparatus is characterized in that a correction speed of the neutral deviation is increased . The vehicle steering apparatus according to claim 1,
  A steering speed detecting means for detecting a steering speed of the steering operation section;
  The vehicle steering apparatus according to claim 1, wherein the neutral deviation correction control means increases the neutral deviation correction speed as the steering speed increases. The vehicle steering apparatus according to any one of claims 1 and 2,
Vehicle speed detection means for detecting the vehicle speed,
The vehicle steering apparatus according to claim 1, wherein the neutral deviation correction control means decreases the neutral deviation correction speed as the vehicle speed increases.