JP2010188978A - Vehicle steering angle control device and vehicle steering angle control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the abrupt change of a target steered wheel angle when switching a vehicle characteristic mode. <P>SOLUTION: A target yaw rate and a target lateral velocity are calculated based on the state quantity of a vehicle relating to the travelling state of the vehicle estimated from a vehicle body velocity V and a steering wheel angle θ of a steering wheel 1. The target steered wheel angle of a steered wheel is calculated based on the calculated target yaw rate and target lateral velocity. The steered wheel is steered-wheel-controlled via a steered wheel actuator to the target steered wheel angle as the target value. When a switching to select a vehicle characteristic mode by a driver's operation is detected, temporarily, the target yaw rate and the target lateral velocity are calculated based on the state quantity of the vehicle excluding the state quantity relating to transient characteristics. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle steering angle control technique for controlling a steering angle of a steered wheel based on a vehicle body speed and a steering angle.

  As a technique for controlling the turning angle of the steered wheels based on the vehicle body speed and the steering angle, for example, there is a conventional technique described in Patent Document 1. In this prior art, when there is a selection switching of the target turning angle ratio mode (vehicle characteristic mode) selected by the driver, until the target turning angle ratio of the target turning angle ratio mode is reached corresponding to the vehicle speed. Delay time. In other words, even if there is mode switching for switching the steering angle ratio while the vehicle is traveling, the purpose is to moderate the transient response to the target steering angle ratio and prevent a sudden change in the steering angle.

JP 2000-203444 A

However, the above prior art has a limit in suppressing the transient response when the vehicle characteristic mode is switched. In other words, if the steering angle command value calculation using cumulative calculation such as differentiation and integration is performed in consideration of transient characteristics, the previous value is initialized at the time of control switching by vehicle characteristic mode switching, and the calculation result is It changes suddenly. In such a case, there is a possibility that a sudden change in the target turning angle cannot be prevented.
The present invention pays attention to the above points, and an object thereof is to suppress a sudden change in the target turning angle when the vehicle characteristic mode is switched.

In order to solve the above problems, the present invention calculates a target yaw rate and a target lateral speed based on a vehicle state quantity related to a traveling state of the vehicle estimated from a vehicle body speed and a steering angle of a steering wheel. Based on the calculated target yaw rate and target lateral velocity, a target turning angle of the steered wheels is calculated. Using the target turning angle as a target value, the steering wheel is steered via a turning actuator.
At this time, when selection switching of the vehicle characteristic mode is detected by the driver's operation, the target yaw rate and the target lateral speed are calculated temporarily based on the basic vehicle state quantity related to the steady characteristics for a predetermined time.

According to the present invention, the target turning angle of the steered wheels is calculated based on the target yaw rate and the target lateral velocity with suppressed transient response when the vehicle characteristic mode is switched.
As a result, it is possible to suppress a sudden change in the target turning angle when the vehicle characteristic mode is switched.

1 is a schematic diagram showing a system configuration of a vehicle according to an embodiment based on the present invention. It is a figure which shows the structure of the steering angle control controller which concerns on embodiment based on this invention. It is a figure for demonstrating the structure of the target production | generation part which concerns on embodiment based on this invention. It is a figure explaining the process of the control switching part which concerns on embodiment based on this invention. It is a time chart example explaining the operation example which concerns on embodiment based on this invention.

Next, embodiments of the present invention will be described with reference to the drawings.
(Constitution)
FIG. 1 shows a configuration diagram of a vehicle according to this embodiment.
First, the configuration will be described with reference to FIG.
A steering input shaft 2 is connected to a steering wheel 1 operated by a driver. A steering output shaft is connected to the steering input shaft 2 via a mechanical backup device 3. In the normal state, the mechanical backup device 3 is in a state in which torque transmission between the steering input shaft 2 and the steering output shaft is cut off. Further, the mechanical backup device connects the steering input shaft 2 and the steering output shaft based on a command from the rudder angle control controller 4 to enable torque transmission. The mechanical backup device may be omitted, and the steering input shaft 2 and the steering output shaft may be always connected.

  A front wheel steering actuator 5 is connected to the steering output shaft. The front wheel steering actuator 5 rotates and displaces the steering output shaft based on a command from the front wheel steering controller 6. A steering actuator angle sensor (not shown) is provided in the steering motor of the front wheel steering actuator 5. The steering actuator angle sensor detects the rotational angle position of the motor of the front wheel steering actuator 5 and outputs the detection signal to the front wheel steering controller 6 as a feedback control amount.

  The steering output shaft is connected to the rack shaft 7 via a rack and pinion mechanism. That is, the pinion connected to the steering output shaft meshes with the rack of the rack shaft 7. The rack shaft is arranged with the shaft directed in the vehicle width direction. The rack shaft 7 is displaced in the axial direction toward the vehicle width direction by rotating the steering output shaft. The left and right ends of the rack shaft are connected to the knuckles of the front wheels 8 via left and right tie rods, respectively.

  Reference numeral 9 denotes a rear wheel steering actuator. The rear wheel steering actuator 9 axially displaces the rack shaft 11 in the vehicle width direction in response to a signal from the rear wheel steering controller 10. The left and right end portions of the rack shaft 11 are connected to a knuckle for the rear wheel 12 via left and right tie rods, respectively. A steering actuator angle sensor (not shown) is provided in the steering motor of the rear wheel steering actuator 9. The steered actuator angle sensor detects the rotational angle position of the motor of the rear wheel steered actuator 9 and outputs the detection signal to the rear wheel steered controller 10 as a feedback control amount.

Further, a steering angle sensor 20, a vehicle speed sensor 21, and a mode selection unit 22 are provided.
The steering angle sensor 20 detects the steering angle θ of the steering wheel 1 and outputs the detected steering angle θ signal to the steering angle control controller 4. The steering angle sensor 20 is provided on the steering input shaft 2 or the steering wheel 1. The steering angle sensor 20 includes, for example, a pulse encoder and detects the steering angle θ operated by the driver.

The vehicle speed sensor 21 detects the vehicle body speed V of the vehicle and outputs the detected vehicle body speed signal to the steering angle controller 4.
The mode selection unit 22 is a switch that is operated by the driver to select a vehicle characteristic mode. A switch signal corresponding to the vehicle characteristic mode selected by the driver is output to the rudder angle controller 4. In the present embodiment, a comfort mode (mode A) and a sports mode (mode B) are provided as vehicle characteristic modes. There may be three or more types of vehicle characteristic modes.

The front wheel steering controller 6 performs steering control of the front wheels 8 that are steered wheels via the front wheel steering actuator 5 so that the target front wheel steering angle α ^* calculated by the steering angle control controller 4 is obtained.
The rear wheel steering controller 10 performs steering control on the rear wheels 12 that are steered wheels via the rear wheel steering actuator 9 so that the target rear wheel steering angle δ ^* calculated by the steering angle control controller 4 is obtained. .

The steering angle control controller 4 calculates the target front wheel turning angle α ^* and the target rear wheel turning angle δ ^* based on the vehicle speed V, the steering angle θ of the steering wheel 1, and the selected vehicle characteristic mode. Then, the finally selected target front wheel turning angle α ^* and target rear wheel turning angle δ ^* are output to the front wheel turning controller 6 and the rear wheel turning controller 10, respectively.
As shown in FIG. 2, the rudder angle controller 4 includes a first calculation unit 4A, a second calculation unit 4B, and a control switching unit 4C.

The first calculation means 4A calculates a target yaw rate and a target lateral speed according to the vehicle characteristic mode based on the vehicle state quantity related to the vehicle running state estimated from the vehicle body speed V and the steering angle θ. Then, based on the calculated target yaw rate and target lateral velocity, target steered wheel target turning angles α ^* and δ ^* are calculated.
The second calculation means 4B is selected by the mode selection unit 22 based on the vehicle state quantity excluding the state quantity related to the transient characteristic among the vehicle state quantities related to the vehicle running state estimated from the vehicle body speed V and the steering angle θ. The target yaw rate and the target lateral velocity are calculated according to the vehicle characteristic mode. Then, based on the calculated target yaw rate and target lateral velocity, target steered wheel target turning angles α ^* and δ ^* are calculated.

When the control switching unit 4C selects the target turning angle calculated by the first calculation unit 4A as an initial value and detects selection switching of the vehicle characteristic mode, the second calculation unit 4B only for a predetermined period under a predetermined condition. The target turning angle calculated by the first is selected. Then, the control switching unit 4C outputs the selected target turning angle to the front wheel turning controller 6 and the rear wheel turning controller 10.
Here, the vehicle state quantity relating to the vehicle running state estimated from the vehicle body speed V and the steering angle θ is a vehicle state quantity relating to the yaw rate and the lateral acceleration specifying the running state.
The first calculation means 4A includes a target value generation unit 4Aa and a first target output value generation unit 4Ab. As shown in FIG. 3, the target value generation unit 4Aa includes a vehicle model calculation unit 4Aa-1 and a front / rear wheel steering target value calculation unit 4Aa-2.

(Vehicle model calculation unit 4Aa-1)
The vehicle model calculation unit 4Aa-1 calculates a vehicle state quantity (vehicle parameter) related to a yaw rate and a lateral speed that specify the traveling state of the vehicle according to the current steering angle θ and the vehicle body speed V according to the vehicle model to be applied. To do. The vehicle state quantities to be calculated are gφ (V), ζφ (V), ωφ (V), Tφ (V), and g _v (V), ζ _v (V), ωφ (V), T _v (V). It is. These state quantities can be calculated from the steering angle θ and the vehicle body speed V according to the following expressions (6) and (8).

Here, as described later, the vehicle state quantities related to the yaw rate are gφ (V), ζφ (V), ωφ (V), and Tφ (V). The vehicle state quantities related to the lateral speed are g _v (V), ζ _v (V), ω _v (V), and T _v (V).
Of these, gφ (V) and g _v (V) are basic vehicle state quantities relating to steady-state characteristics. ζφ (V), ωφ (V), ζ _v (V), and ω _v (V) are vehicle state quantities related to transient characteristics.
Here, the vehicle state quantity using the vehicle model will be described.
When a two-wheel model is adopted as the vehicle model, the yaw rate and lateral speed of the vehicle can be expressed by the following equations. That is, the yaw rate and the lateral speed corresponding to the steering angle θ and the vehicle body speed V can be estimated from the state equation of the following expression (1).

here,
φ ′: Yaw rate s: Differential operator θ: Steering angle of driver (equivalent to front wheel turning angle)
δ: Rear wheel turning angle Vx, V: Vehicle speed Vy: Lateral speed Iz: Vehicle inertia moment M: Vehicle weight Lf: Front axle to center of gravity distance Lr: Center of gravity center to rear axle distance N: Gear ratio Kf: Front wheel cornering power Kr: rear wheel cornering power Cf: front wheel cornering force Cr: rear wheel cornering force

である。
次に、上記状態方程式から、前輪操舵に対するヨーレート、及び横速度の伝達関数を求めると、下記（３）式及び（４）式となる。

It is.
Next, when the transfer function of the yaw rate and the lateral velocity with respect to the front wheel steering is obtained from the above state equation, the following equations (3) and (4) are obtained.

  From the above equation (3), the transfer function of the yaw rate can be expressed by the following equation.

  From the above equation (4), the transfer function of the lateral velocity can be expressed by the following equation.

From the above, the traveling state of the vehicle according to the steering angle θ and the vehicle body speed V can be specified by the yaw rate and the lateral speed.
The vehicle state quantities (vehicle parameters) related to the yaw rate are gφ (V), ζφ (V), ωφ (V), and Tφ (V).
Further, vehicle state quantities (vehicle parameters) relating to the lateral speed are g _v (V), ζ _v (V), ω _v (V), and T _v (V).
Here, gφ (V) and g _v (V) are state quantities (basic vehicle state quantities) indicating the basic state of the characteristic mode.
ζφ (V) and ζ _v (V) are state quantities related to the attenuation term.
ωφ (V) and ω _v (V) are state quantities related to the natural frequency of the spring system.
Tφ (V) and T _v (V) are state quantities related to the steady deviation.

Next, the front / rear wheel turning target value calculation unit 4Aa-2 will be described.
The front / rear wheel steering target value calculation unit 4Aa-2 calculates the vehicle target yaw rate φ ′ ^* fr and the target from the driver steering angle θ, the vehicle body speed V, and the vehicle state quantity calculated by the vehicle model calculation unit 4Aa-1. Obtain the lateral velocity Vy ^* fr.
First, a target characteristic state quantity corresponding to the selected vehicle characteristic mode is calculated.
That is, the vehicle state quantity corresponding to the vehicle model is multiplied by a gain corresponding to each vehicle characteristic mode, as shown in the following equation. Thus, the vehicle state quantity calculated by the vehicle model calculation unit 4Aa-1 is converted into a target characteristic state quantity corresponding to the vehicle characteristic mode.

Target characteristic state ^{quantity, gφ * (V), ζφ} * (V), ωφ * (V), Tφ * (V), and ^{_{g v * (V), ζ}} v * (V), ω v * (V ), T _v ^* (V).
gφ ^* (V) = gφ (V) xyrate_gain_map1
ζφ ^* (V) = ζφ (V) xyrate_zeta_map1
ωφ ^* (V) = ωφ (V) xyrate_omegn_map1
Tφ ^* (V) = Tφ (V) xyrate_zeta_map1
g _v ^* (V) = g _v (V) × vy_gain_map1
ζ _v ^* (V) = ζ _v (V) × vye_zeta_map1
ω _v ^* (V) = ω _v (V) × vy_zero_mapa1
T _v ^* (V) = Tφ (V) xvy_zeta_map1
However, yrate_gain_map1, yrate_omegn_map1, yrate_zeta_map1, yrate_zero_mapa1, vy_gain_map1, vy_omegn_map1, vye_zeta_map1, and vy_zero_mapa1 are preset tuning parameters that change depending on the vehicle speed.

Here, yrate_gain_map1 and vy_gain_map1 have different maps for each vehicle characteristic mode. Then, yrate_gain_map1 and vy_gain_map1 corresponding to the selected vehicle characteristic mode are used. The map switching is performed by the control switching unit 4C.
Next, the front / rear wheel steering target value calculation unit 4Aa-2 applies the target characteristic state quantity corresponding to the vehicle characteristic mode in place of the vehicle state quantity calculated by the vehicle model calculation unit 4Aa-1. Based on the equation, the target yaw rate and the target lateral velocity are obtained from the vehicle body speed V, the steering angle θ, and the target characteristic state quantity.
Here, the target yaw rate is expressed by the following equation (9).

  Further, the target lateral speed is expressed by the following equation (10).

Next, the first target output value generation unit 4Ab will be described.
The first target output value generator 4Ab determines the target turning angles α ^* and δ ^* from the target yaw rate φ ′ ^* fr calculated by the target value generator 4Aa and the target lateral velocity Vy ^* fr.
Since the yaw rate and lateral acceleration control are performed at the time of steering using the front and rear wheels as steered wheels, the target front wheel turning angle α ^* and the target rear wheel turning angle δ ^* are obtained from the following equations (12) and (13). .

Then, the first calculation means 4A outputs the calculated target front wheel turning angle α ^* and the target rear wheel turning angle δ ^* to the control switching unit 4C.
(Second calculation means 4B)
Next, the 2nd calculating means 4B is demonstrated.
The 2nd calculating means 4B is provided with 2nd target output value production | generation part 4Ba. The second target output value generator 4Ba calculates the target front wheel turning angle α ^* and the target rear wheel turning angle according to the vehicle characteristic mode from the steering angle θ, the vehicle body speed V, and the vehicle state quantity not related to the transient response. Find δ ^* .

Here, when the same equation of state (same vehicle model) as the above equation (1) is adopted, in the above equations (5) and (7), the transfer function excluding the differential term and the integral term that become transient response characteristics is It becomes as follows.
φ ′ (s) = gφ (V) · θ (s)
Vy (s) = g _v (V) · θ (s)
That is, the second computing means 4B uses gφ (V) and g _v (V) among the vehicle state quantities described above.
That is, gφ (V) and g _v (V) corresponding to the vehicle speed V and the steering angle θ are calculated based on the following formula.

Next, the calculated vehicle state quantities gφ (V) and g _v (V) are converted into target characteristic state quantities gφ ^* (V) and g _v ^* (V) corresponding to the vehicle characteristic mode.
gφ ^* (V) = gφ (V) xyrate_gain_map1
g _v ^* (V) = g _v (V) × vy_gain_map1
However, yrate_gain_map1 and vy_gain_map1 are preset tuning parameters that change depending on the vehicle speed as described above. The yrate_gain_map1 and vy_gain_map1 have different maps for each vehicle characteristic mode. Then, yrate_gain_map1 and vy_gain_map1 corresponding to the selected vehicle characteristic mode are used. yrate_gain_map1 and vy_gain_map1 themselves have the same values as the parameters used in the first calculation means 4A. The map switching is performed by the control switching unit 4C.
Next, by applying the target characteristic state quantity corresponding to the vehicle characteristic mode instead of the vehicle state quantity, the target yaw rate and the target lateral speed are calculated from the vehicle body speed V, the steering angle θ, and the target characteristic state quantity based on the following equations. Find the speed.
Here, the target yaw rate is expressed by the following equation (16).

  Further, the target lateral speed is expressed by the following equation (17).

Here, since there is no term of transient characteristics, the differential value of the target yaw rate and the differential value of the target lateral velocity are zero.
Next, the target front and rear wheel steering angles α ^* and δ ^* are determined from the calculated target yaw rate φ ′ ^* and the target lateral velocity Vy ^* .
Since the yaw rate and lateral acceleration control are performed when steering with the front and rear wheels as steered wheels, the target front wheel turning angle α ^* and the target rear wheel turning angle δ ^* are obtained from the following equations (18) and (19). .

Then, the second calculation means 4B outputs the calculated target front wheel turning angle α ^* and the target rear wheel turning angle δ ^* to the control switching unit 4C.
Next, the process of the control switching unit 4C will be described with reference to FIG.
The control switching unit 4C performs a target turning angle selection process and a vehicle characteristic mode map switching process. The switched map is used by the first calculation means 4A and the second calculation means 4B.
First, in step S10, a mode selection switch signal is read. Subsequently, in step S20, it is determined whether the communication of the mode selection switch signal is normal. If it is determined to be normal, the process proceeds to step S30. If it is determined that it is not normal, the process proceeds to step S70. That is, if not normal, it is fixed to the previous control characteristic mode and switching is not performed.

In step S30, the mode of the mode selection switch signal is determined. If the mode is A, the process proceeds to step S40. If the mode is B, the process proceeds to step S50. In step S40 and S50, the selected mode is stored.
Subsequently, in step S60, the current mode is compared with the previous mode to determine whether the switch is switched. If it determines with having switched, it will transfer to step S80 and will implement a control switching process. If it determines with not having switched, it will transfer to step S70.

In step S70, the control mode is fixed to the previous control characteristic mode and switching is not performed, and the process proceeds to step S120.
In step S80, it is determined whether the mode of the stored mode selection switch signal is A or not. If the mode is A, the process proceeds to step S90, and a control characteristic map for MODE_A is selected. On the other hand, if the mode is B, the process proceeds to step S100, and a control characteristic map for MODE_B is selected. By this process, the map used in the first calculation means 4A and the second calculation means 4B is changed to become the map of the selected vehicle characteristic mode.

  Subsequently, in step S110, it is determined whether or not the steering angle θ is equal to or smaller than a predetermined angle and the steering angular velocity is equal to or smaller than a predetermined speed. If the condition is satisfied, control switching is permitted and the process proceeds to step S160. On the other hand, if the condition is not satisfied, the process proceeds to step S120. Here, by making the threshold value of the steering angle θ sufficiently small, it is possible to obtain substantially the same effect as permitting control switching only when the steering angular velocity is low.

In step S120, it is determined whether the previous selection has used the target turning angle on the first calculation means 4A side. If the condition is satisfied, the process proceeds to step S130. On the other hand, if the condition is not satisfied, the process proceeds to step S140.
In step S130, the target turning angle calculated by the first calculation means 4A is selected. Then return.
In step S140, it is determined using a timer whether or not a certain period of time has elapsed after the transition to the second calculation means 4B. If the condition is satisfied, the process proceeds to step S160. On the other hand, if the condition is not satisfied, the process proceeds to step S150.

In step S150, it is determined whether or not the state where the difference between the target turning angle calculated by the first calculation means 4A and the target turning angle calculated by the second calculation means 4B is equal to or less than a predetermined value continues for a predetermined time. . If the condition is satisfied, the process proceeds to step S130. On the other hand, if the condition is not satisfied, the process proceeds to step S160. Since it is determined in step S140 whether or not the predetermined time has elapsed, the time determination as to whether or not the state where the difference is equal to or less than the predetermined value continues for the predetermined time may be omitted.
In step S160, the target turning angle calculated by the second calculation means 4B is selected. Then return.

(Operation)
In order to detect the actual traveling state of the vehicle as much as possible, the yaw rate and the lateral speed representing the traveling state of the vehicle are calculated using the vehicle model, and the target yaw rate and the target lateral speed corresponding to the vehicle characteristic mode are obtained. And the target turning angle for implement | achieving the target yaw rate and target lateral velocity is calculated.
For this reason, the target yaw rate and the target lateral velocity include a transient response. For this reason, if the target yaw rate and the target lateral velocity calculated by the first calculation means 4A are used regardless of the mode switching, the calculated value by the integral calculation changes suddenly when the vehicle characteristic mode is switched, as shown by A in FIG. There is a risk of sudden changes in the target turning angle.

  On the other hand, in this embodiment, as shown in FIG. 5, instead of the value A by the first calculation means 4A only during the period in which the steering angle command value not intended by the first calculation means 4A occurs immediately after the control switching, The value B calculated by the second calculation means 4B is used. As a result, since an unexpected change in the steering angle command value is suppressed, it is possible to prevent the driver from feeling uncomfortable.

Here, the front wheel steering actuator 5 and the rear wheel steering actuator 9 constitute a steering actuator. The vehicle speed sensor 21 constitutes vehicle body speed acquisition means. The steering angle sensor 20 constitutes a steering angle acquisition means. The selection unit 22 constitutes selection means.
The first calculation means 4A constitutes first target turning angle calculation means. The 2nd calculating means 4B comprises the 2nd target turning angle calculating means. The control switching unit 4C constitutes a target turning angle selection unit. The front wheel steering controller 6 and the rear wheel steering controller 10 constitute a steering controller.

(Effect of this embodiment)
(1) The first target turning angle calculation means is selected by the selection means based on the basic vehicle state quantity related to the steady state characteristic related to the vehicle running state and the vehicle state quantity related to the attenuation characteristic estimated from the vehicle body speed V and the steering angle θ. The target yaw rate and the target lateral speed according to the vehicle characteristic mode thus calculated are calculated, and the target turning angle of the steered wheels is calculated based on the calculated target yaw rate and target lateral speed. The second target turning angle calculation means responds to the vehicle characteristic mode selected by the selection means based on the basic vehicle state quantity among the vehicle state quantities related to the vehicle running state estimated from the vehicle body speed V and the steering angle θ. The target yaw rate and the target lateral speed are calculated, and the target turning angle of the steered wheels is calculated based on the calculated target yaw rate and target lateral speed. The target turning angle selection means selects the target turning angle calculated by the first target turning angle calculation means as an initial value, and when the selection switching of the vehicle characteristic mode is detected, the second target turning angle calculation means Select the calculated target turning angle. The steered controller steers the steered wheel via the steered actuator using the target steered angle selected by the target steered angle selecting means as a target value.
Suppresses the occurrence of transient response when switching the vehicle characteristic mode. This can prevent the driver from feeling uncomfortable.

(2) The target turning angle selection means performs selection of the target turning angle calculated by the second target turning angle calculation means when the steering angle θ and the absolute value of the steering angular velocity are each equal to or less than a predetermined threshold value.
Accordingly, the target turning angle calculated by the second target turning angle calculation means is selected only when a transient response of a predetermined value or more occurs. As a result, unnecessary switching of the target turning angle is suppressed.
Further, when the absolute values of the steering angle θ and the steering angular velocity are each equal to or less than a predetermined threshold, the target turning angle calculated by the second target turning angle calculation means is switched. For this reason, at the time of switching, the target turning angle calculated by the second target turning angle calculation means is a value close to the target turning angle calculated by the second target turning angle calculation means. Can be realized.

(3) The target turning angle selection means is after a predetermined time has elapsed since the selection of the target turning angle calculated by the second target turning angle calculation means, and the second target turning angle calculation means calculates. When it is determined that the deviation between the target turning angle and the target turning angle calculated by the first target turning angle calculation means is equal to or less than a predetermined position, the target turning angle calculated by the first target turning angle calculation means is selected. To do.
Thereby, it is possible to prevent the driver from feeling uncomfortable when the vehicle characteristic mode is switched from the target turning angle calculated by the second target turning angle calculating means to the target turning angle calculated by the first target turning angle calculating means. .

(4) The vehicle state quantity related to the attenuation characteristic is a state quantity that becomes a coefficient of the differential term and the integral term when calculating the target yaw rate and the target lateral velocity.
Thereby, the characteristic of the target turning angle calculated by the second target turning angle calculating means is a characteristic of only the steady characteristic excluding the transient characteristic, and the transient response at the time of switching the vehicle characteristic mode can be surely suppressed. I can do it.

4 Steering angle controller 4A 2nd calculating means 4Aa Target value generating part 4Aa-1 Vehicle model calculating part 4Aa-2 Front / rear wheel steering target value calculating part 4Ab 1st target output value generating part 4B 2nd calculating means 4Ba 2nd target Output value generation unit 4C Control switching unit 5 Front wheel steering actuator 6 Front wheel steering controller 9 Rear wheel steering actuator 10 Rear wheel steering controller 12 Rear wheel 20 Steering angle sensor 21 Vehicle speed sensor 22 Mode selection unit V Vehicle speed Vy ^* Target lateral speed φ ^* Target yaw rate α ^* Target front wheel turning angle δ ^* Target rear wheel turning angle θ Driver's steering angle

Claims (5)

Steering actuator that steers steered wheels, vehicle body speed acquisition means for acquiring vehicle body speed, steering angle acquisition means for acquiring the steering angle of the steering wheel, and selection that the driver operates to select the vehicle characteristic mode Means,
The target yaw rate and the target lateral speed corresponding to the vehicle characteristic mode selected by the selection means are determined based on the basic vehicle state quantity related to the steady state characteristic related to the vehicle running state and the vehicle state quantity related to the transient characteristic estimated from the vehicle body speed and the steering angle. First target turning angle calculating means for calculating and calculating a target turning angle of the steered wheels based on the calculated target yaw rate and target lateral velocity;
The target yaw rate and the target lateral speed corresponding to the vehicle characteristic mode selected by the selection means are calculated based on the basic vehicle state amount related to the steady characteristic related to the vehicle running state estimated from the vehicle body speed and the steering angle, and the calculated Second target turning angle calculating means for calculating a target turning angle of the steered wheel based on the target yaw rate and the target lateral speed;
When the target turning angle calculated by the first target turning angle calculation means is selected as an initial value and the selection switching of the vehicle characteristic mode is detected, the target turning angle calculated by the second target turning angle calculation means is selected. Target turning angle selection means to perform,
A steering controller that steers the steered wheels via the steering actuator, with the target turning angle selected by the target turning angle selection means as a target value;
A vehicle rudder angle control device comprising:   The target turning angle selection means performs the selection of the target turning angle calculated by the second target turning angle calculation means when the absolute values of the steering angle and the steering angular velocity are each equal to or less than a predetermined threshold value. The vehicle steering angle control device according to claim 1.   The target turning angle selection means is a target turning angle calculated by the second target turning angle calculation means after a predetermined time has elapsed since the selection of the target turning angle calculated by the second target turning angle calculation means. When it is determined that the deviation between the steering angle and the target turning angle calculated by the first target turning angle calculation means is equal to or less than a predetermined position, the target turning angle calculated by the first target turning angle calculation means is selected. The vehicle steering angle control device according to claim 1 or 2, characterized in that   4. The vehicle state quantity relating to the transient characteristic is a state quantity that is a coefficient of a differential term and an integral term when calculating a target yaw rate and a target lateral velocity. The vehicle steering angle control device described in the item. The target yaw rate and the target lateral speed are calculated based on the vehicle state quantity related to the running state of the vehicle estimated from the vehicle body speed and the steering angle of the steering wheel, and the steered wheel target is calculated based on the calculated target yaw rate and the target lateral speed. A vehicle steering angle control method for calculating a steering angle, using the target steering angle as a target value and steering-controlling steered wheels via a steering actuator,
When the vehicle characteristic mode selection switching is detected by the driver's operation, the basic vehicle state related to the steady state is temporarily selected from the vehicle state quantities related to the running state of the vehicle estimated from the vehicle body speed and the steering angle of the steering wheel. A vehicle steering angle control method, wherein a target yaw rate and a target lateral velocity are calculated based on a quantity, and a target turning angle of a steered wheel is calculated based on the calculated target yaw rate and target lateral velocity.

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