JP2768034B2 - Vehicle steering angle control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering angle control device for a vehicle, and more particularly to a control device in which a steering angle control method is improved when a predetermined limit is set for the amount of control steering angle. Things.

[0002]

2. Description of the Related Art As a steering angle control device for a vehicle, for example, a steering angle control method as described in the Transactions of the Society of Instrument and Control Engineers, Vol. There is something. This is a control method for optimizing the movement of the vehicle by rear wheel steering angle control, and the steering angle of the rear wheels is set using a reference model for setting a desired response to the steering angle input and the movement characteristics of the own vehicle. This is a feed-forward model adaptation or tracking control method to be set. If the control amount (turning angle) of the rear wheel steering angle in the four-wheel steering system is sufficient,
By applying the above control method, a response that is extremely close to the response of the reference model can be obtained even in a real vehicle, and a remarkable improvement in the steering stability of the vehicle can be obtained.

[0003] For example, for example, Journal of the Society of Automotive Engineers of Japan Vol.
2, N0.3 “Model following control and four-wheel steering vehicle” (Reference 2) also includes a front and rear wheel steering angle control method. This method
A feedforward in which two yaw rates and lateral speeds are used as controlled amounts, and front and rear wheel steering angles for obtaining a desired yaw rate and lateral speed with respect to a steering input are calculated using a reference model and dynamic characteristics of the own vehicle. If the steering angle control amount (steering angle) of the front and rear wheels is sufficient,
By applying such a control method, extremely good vehicle dynamics performance can be realized.

[0004]

The above technique is based on 2WS.
Compared to the case of a car, it can contribute to adding new vehicle performance to maneuverability and stability, but the following aspects are limited in that it is difficult to fully demonstrate that performance And there is still room for improvement. In other words, when the four-wheel steering system is incorporated, the system configuration requires, for example, a steering angle control amount in order to enable safe traveling even in the event of a failure in the steering angle control mechanism, for example, in terms of space, etc. There may be times when you want to regulate up to a certain amount. More specifically, in the latter case, for example, the system uses the steering angle and the vehicle speed as detection values, sets a rear wheel steering angle target value using a predetermined function (operation) with a microcomputer, and electrically controls the rear wheels. In the case of a steering system, in addition to measures such as providing a strong return spring to keep the rear wheel neutral in the rear wheel steering power cylinder in case of failure such as hydraulic system, This is the case where it is desired to mechanically limit the maximum turning angle of the wheels, that is, the maximum value of the control steering angle amount to a predetermined value.

However, when a steering angle control method using a reference model as shown in the above document is applied to a system in which the maximum value of the steering angle control amount is limited to a relatively small amount,
When a large steering angle is input, the steering angle of the control target wheel (rear wheel or front and rear wheels) is saturated. Such saturation makes it difficult to sufficiently obtain the effect of the steering angle control, for example, by setting the response of the yaw rate, which is the controlled amount, to a control characteristic accompanied by the occurrence of overshoot different from that of the reference model.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned restrictions and to appropriately exert the effect of the steering angle control even when a predetermined limit is provided for the controllable steering angle amount. It is an object of the present invention to provide a vehicular steering angle control device that can be used.

[0007]

According to the present invention, there is provided the following vehicle steering angle control device. That is, it includes a steering angle control mechanism capable of controlling the steering angle of at least one of the front wheels and the rear wheels, and a drive unit that drives the mechanism so that the actual steering angle matches the control input value according to the steering angle control input. A steering device, and at least one of a vehicle yawing motion control amount and a vehicle lateral motion control amount such that the vehicle motion to be realized by controlling the steering angle of the control target wheel becomes the target vehicle motion. A detecting means for detecting a steering angle of a steering wheel or an amount corresponding thereto, and a detecting means for detecting a vehicle speed or an amount corresponding thereto, as a steering angle control device for a four-wheel steering vehicle which controls a motion control amount. And the motion control using outputs from these detecting means.
And car both exercise target value setting means to set the steady-state characteristics and transient characteristics to the steering angle input the amount, so that the actual vehicle response to movement target value set by said vehicle movement target value setting means coincides or follows A steering angle calculation means for calculating a steering angle control input value of the control target wheel and instructing the steering device. Steering angle control device for a vehicle, wherein the steady gain of the motion control amount is given as a function of the steering angle so that the steady gain changes according to the magnitude of the steering angle input. A front wheel auxiliary steering device including a controllable auxiliary steering angle control mechanism, and a drive unit that drives the mechanism so that the actual steering angle matches the control input value in accordance with the front wheel control input, and the rear wheel steering angle can be controlled. Steering angle control mechanism, A rear wheel steering device including a drive unit that drives a mechanism so that the actual steering angle matches the control input value according to the rear wheel control input, and attempts to realize the steering angle control of the front and rear wheels. The vehicle yawing motion control amount is a first motion control amount and the vehicle lateral motion control amount is a second motion control amount so that the yawing motion and the lateral motion of the vehicle become the target vehicle yawing motion and the lateral motion. Second
A steering angle control device for a four-wheel steering vehicle that controls the motion control amount of the vehicle, detecting means for detecting a steering angle of the steering wheel or an amount equivalent thereto, and detecting means for detecting a vehicle speed or an amount equivalent thereto. A vehicle motion target value setting means for setting a steady-state characteristic and a transient characteristic with respect to a steering angle input for each of the first and second motion control amounts using outputs from the detection means; The front wheel steering angle input value and the rear wheel steering angle input value so that the actual vehicle response matches or follows the motion target value of the first motion control amount and the motion target value of the second motion control amount set by And a steering angle calculating means for commanding the front wheel assist steering device and the rear wheel steering device, respectively, wherein the first and second vehicle motion target value setting means set the first and second control values. Exercise The target steady-state value of the control amount is a first motion control amount that can be set so as to obtain a desired first motion control amount and a desired second motion control amount with respect to the steering angle input, regardless of the characteristic of the control target vehicle. A first target steady-state value for the first motion control amount and a second motion control amount for the second motion control amount, which are set based on the first steady-state characteristic for the first motion control amount and the first steady-state characteristic for the second motion control amount, respectively. A first target steady-state value, a second steering characteristic and a second steady-state characteristic for a first motion control amount with respect to a vehicle-specific steering angle, a front wheel control input, and a rear wheel control input, which are preset for the control target vehicle, respectively. From the second target steady-state value for the first motion control amount and the second target steady-state value for the second motion control amount, which are set based on the second steady-state characteristic for the motion control amount. A vehicle steering angle control device, which is set.

[0008]

According to the present invention, it is possible to control the yawing motion of the vehicle with the steering device so that the vehicle motion to be realized by controlling the steering angle of the wheel to be controlled becomes the target vehicle motion. A steering angle control device for a four-wheel steering vehicle that controls at least one of a yaw motion control amount and a lateral motion control amount capable of controlling the lateral motion of the vehicle, wherein the steering device is a front wheel or At least one of the rear wheels is steered based on a steering angle control input, and a vehicle motion target value setting means [for example, FIG.
2a to 4e] is a motion control amount [e.g., using an output from a detecting means for detecting a steering angle or an amount corresponding thereto and a detecting means for detecting a vehicle speed or an amount corresponding thereto.
For the yaw rate (d / dt) φ (the yaw angular velocity (deg / sec) of the vehicle) as a controlled quantity described later, the steady-state characteristics and the transient characteristics with respect to the steering angle input are set. The steady gain of the motion control amount with respect to the steering angle is given as a function of the steering angle so that the steady gain changes according to the magnitude of the steering angle input (for example,
6 and 13], the steering angle calculating means [for example, 5 in FIG.
Thus, the steering angle control input value of the wheel to be controlled is calculated such that the actual vehicle response matches or follows the movement target value set by the vehicle movement target value setting means, and is commanded to the steering device.
Here, the vehicle motion target value setting means [for example, FIG.
In 4a to 4e in FIG. 2, a movement target value of the movement control amount including the transient characteristic can be set, and this can be applied to the steering angle calculation by the steering angle calculation means [for example, Expressions 15, 16, and 17 described below] , Equation 19,2
(Note that the above description in parentheses [] is merely an example, and the present invention is not limited to this. As described below, and as described in the following examples, Changes are possible, and this is the same in the description in [] below). Therefore, the steady-state value of the motion control amount with respect to the steering angle input can be set so that this can be achieved with a steering angle amount smaller than the maximum value of the steerable angle controllable range. For a large steering angle input that would saturate the control steering angle if the steady-state gain was constant, the steering wheel was always controlled during the steering angle control without the steering angle being saturated. Appropriate control is possible in a region that does not saturate. Further, according to the present invention, the target value y of the motion control amount with respect to the steering angle?
_m is a non-linear function G _m
The (theta), the following _{equation, y mo = G m (θ} ) · θ 0 However, y _mo goals steady value of motion control amount, theta ₀ is a steering angle theta
The configuration can be implemented in such a manner that the steady-state gain is changed. Then, as a transfer function, the nonlinear function G _m (θ)
, The steady-state gain of the motion control amount with respect to the steering angle is given as a function of the steering angle, and the steering angle of the controlled wheel is not always saturated by having a nonlinearity that changes the steady-state gain depending on the magnitude of the steering angle input. Control can be enabled [eg, FIG. 6, FIG. 13]. Further, when there is a limit to the controllable steering angle control amount of the control target wheel, the limit amount is set to δ _max ,
_{When a} predetermined amount smaller than _max is set to δ _LIM , the steady-state value of the control steering angle is set to the predetermined amount δ even for a large steering angle input.
_{In order} not to exceed _LIM , the nonlinear function G _m (θ)
The present invention can be implemented as a configuration in which is set. With this configuration, even if a linear reference model that sets a desired response to the steering angle input is used for the vehicle motion target value setting means, the aim of the present invention can be realized, and the magnitude of the steering angle input can be reduced. Accordingly, with respect to a small to medium steering angle input that is equal to or less than the predetermined steering angle input, it is also possible to easily obtain an ideal response in both steady and transient characteristics as set in the reference model. [For example, FIG. 6]. Here, the document 1
For example, when the yaw rate is controlled by a four-wheel steering system (4WS) using rear wheel steering, the reference model is that the steady-state yaw rate gain is based on the base vehicle (2WS (control OFF; non-four-wheel steering)). ) (P. 51 (p. 831), right column, lines 17 to 19, etc.), according to the present invention, the region where the rear wheel is not always saturated in the steady-state characteristics of the reference model. , It is also possible to easily provide a non-linear characteristic of changing the steady gain depending on the magnitude of the steering angle input. Further, in the present invention, instead of the above method, a motion control amount target steady-state value may be given in advance as a function of the steering angle and the vehicle speed, for example, as shown in FIG. The present invention can also be implemented by a map search process for searching for a corresponding steady target value from a two-dimensional map as shown in FIG. 13 according to the steering angle and the vehicle speed, and the present invention includes such an embodiment. It should be noted that the present invention provides a yaw rate model adaptation control (see “3.1 Yaw rate model adaptation”) for controlling a yaw rate using a controlled variable as a yaw rate as described in, for example, “3. Design of Control System” in Document 1. Control)), a "3.2 lateral acceleration model following control" that controls the lateral acceleration using the controlled variable as a lateral acceleration, and a "control that controls both yaw rate and lateral acceleration". 3.3 D * model following control ”can be applied in the same way, and can also be applied to similar systems that electrically steer the front wheels and front / rear wheels.
As shown in 61-91172 and Japanese Patent Application No. 2-115272, a system that sets a target exercise value using a reference model and detects the actual value of the exercise using a sensor to perform feedback compensation, The invention is equally applicable.

Further, the present invention is a vehicle having the front wheel assist steering device and the rear wheel steering device, and performing yaw motion and lateral motion of a vehicle to be realized by controlling the steering angle of front and rear wheels. A yaw motion control amount capable of controlling the yawing motion of the vehicle so as to be a yaw motion and a lateral motion is referred to as a first motion control amount, and a lateral motion control amount capable of controlling the lateral motion of the vehicle is referred to as a second motion control amount. A steering angle control device for a four-wheel steering vehicle that controls first and second motion control amounts, wherein the front wheel auxiliary steering device and the rear wheel steering device respectively control the front wheel auxiliary steering and the rear wheel based on the steering angle control input. The vehicle motion target value setting means (for example, 14 in FIG. 14: 14a to 14e in FIG. 15) uses the outputs from the two detection means as in claim 1, 2 motion control amount [for example, yaw Late (d / dt) φ and lateral velocity V
_Y ], a steady-state characteristic and a transient characteristic with respect to the steering angle input are set. In this case, the target steady-state values of the first and second motion control amounts set by the setting means are:
A first steady-state characteristic for a first motion control amount that can be set so as to obtain a desired first motion control amount and a second motion control amount for a steering angle input irrespective of characteristics peculiar to the vehicle to be controlled. And a first target steady-state value relating to the first motion control amount which is set based on the first steady-state characteristic for the second motion control amount [for example, a first yaw rate steady-state target value based on Expression 28 below] (d / dt) φ _mod ] and a first target steady-state value relating to the second motion control amount [for example, a first lateral velocity steady-state target value V _Ymod based on Expression 29 described below] and a target vehicle to be controlled. The second steering angle for the first motion control amount with respect to the vehicle-specific steering angle, front wheel control input, and rear wheel control input previously set as
A second target steady-state value related to the first motion control amount set based on the steady-state characteristic of the second motion control amount and the second steady-state characteristic for the second motion control amount [for example, a second yaw rate steady-state value based on Expression 48 below] The target value (d / dt) φ _mo ] and the second target steady-state value relating to the second motion control amount [for example, a second
From the lateral velocity steady-state target value V _Ymo ].
The steering angle calculating means (for example, 15 in FIG. 14 described later) actually converts the motion target value of the first motion control amount and the motion target value of the second motion control amount set by the vehicle motion target value setting means into actual values. The front wheel steering angle input value and the rear wheel steering angle input value are calculated respectively so that the vehicle response coincides or follows, and commands are issued to the front wheel assist steering device and the rear wheel steering device. In addition, the vehicle motion target value setting means can set the motion target value of the first motion control amount and the motion target value of the second motion control amount including the transient characteristics, similarly to the above. Therefore, also in this case, it is set that the steady target values of the first and second motion control amounts with respect to the steering angle input can be achieved with a steering angle amount smaller than the maximum value of the front and rear wheel steering angle controllable range. If possible, similarly, even when a large steering angle is input, the front and rear wheel steering angles do not saturate, and good characteristics can be obtained for the first and second motion control amounts. It is possible to control the steering angle appropriately. In the selection, when there is a limit to the controllable steering angle of the front wheel control input, the limit amount is set to Δδ _Fmax and the controllable steering angle of the rear wheel control input is set to Δδ _Fmax . the amount of restriction in the case where there is a limit to the [delta] _Rmax, and the .DELTA..delta _Fmax lesser predetermined amount of .DELTA..delta _FLIM, when a predetermined amount less than the [delta] _Rmax was [delta] _RLIM, for the first motion control amount Both the front wheel control input value and the rear wheel control input value for realizing the first target steady-state value and the first target steady-state value relating to the second motion control amount are the predetermined amount Δδ _FLIM and the predetermined amount. If δ _RLIM is not exceeded, the first target steady-state value for the first motion control amount and the first target steady-state value for the second motion control amount are set to the first motion control amount of the vehicle motion target value setting means and Selected as the target steady-state value for the second motion control amount, If either of them is exceeded, the second target steady-state value relating to the first movement control amount and the second target steady-state value relating to the second movement control amount are set to the first movement control amount of the vehicle movement target value setting means. The present invention can be implemented as a configuration for selecting the target steady-state value regarding the second motion control amount. When implemented in such an embodiment, the same operation and effect as those of the third aspect can be obtained. When using the reference model, the designer uses the reference model to determine the first steady-state characteristic for the first movement control amount and the first steady-state characteristic for the second movement control amount by using the reference model.
Regardless of the characteristics specific to the control target vehicle, for example, regardless of the above-mentioned limit amounts Δδ _Fmax and δ _Rmax , it is also possible to arbitrarily provide desired steady-state characteristics that are considered ideal. The advantages of using a model can also be used more effectively. However, also in this case, similarly to the above, instead of such a method, a method of searching for a target steady-state value of the first motion control amount and the second motion control amount from the map and obtaining the same can be employed. ,
It is also possible to calculate in advance including the second steady-state characteristic for the first motion control amount and the second steady-state characteristic for the second motion control amount, and to give the result in the form of a map, The present invention includes such an embodiment. Also, in this case,
The present invention is not limited to the feedforward method, and can be similarly applied to a feedback control system as disclosed in Japanese Patent Application No. 2-115273.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 show an embodiment of a steering angle control device according to the present invention, which is applied to a steering angle control system for steering rear wheels. Furthermore, the apparatus of the embodiment shows an embodiment in a control system to which a yaw rate adaptive control of a feed forward system is applied. Specifically, FIG. 1 is a hardware configuration diagram, and FIG. FIG. 3 is a block diagram of a vehicle motion target value setting unit (a yaw rate target value setting unit in this example). FIGS. 3 to 5 show control programs of a controller.

First, the hardware of FIG. 1 will be described.
Here, the applied steering angle system assumes that the front wheels are mainly steered via the steering gear according to the steering angle of the steering wheel of the vehicle, and the rear wheels of the vehicle are the rear wheel steering mechanism 1 (steering angle control mechanism). ), The steering is performed by a rear wheel steering device including the actuator drive unit 2, and the rear wheel steering angle δ
_R is controlled by the controller 3. Controller 3
Is a yaw rate target value setting unit 4 as a vehicle motion target value setting unit, and a rear wheel so that an actual vehicle response matches or follows a motion target value (here, a yaw rate target value) set by the target value setting unit. And a rear wheel steering angle calculation unit 5 that calculates the steering angle of the vehicle.

More specifically, a yaw rate target value setting unit 4
Receives a signal from a steering angle sensor 11 for detecting a steering angle θ of a steering wheel and a signal from a vehicle speed sensor 12 for detecting a vehicle speed V, and sets a response target value relating to yaw to a steering angle input based on these signals. Then, the rear wheel steering angle calculation unit 5 calculates a rear wheel steering angle for matching the actual vehicle yaw rate response to the yaw rate target value (controlled amount target value) set above based on the dynamic characteristics of the host vehicle. Then, the actuator drive unit 2 drives the actuator of the steering mechanism 1 such that the actual actual steering angle matches the rear wheel steering angle target value δ _RT (command value) calculated in this way. The steering angle sensor can detect the amount corresponding to the steering angle, and the vehicle speed sensor can also detect the vehicle speed equivalent. Here, it is assumed that the maximum value of the rear wheel steering mechanism is limited to, for example, 1 degree by the mechanical steering angle limiting mechanism.

FIG. 2 shows an example where the steady-state characteristic of the reference model has a non-linear characteristic of changing the steady-state gain depending on the magnitude of the steering angle input when the controlled variable is the yaw rate, and the rear wheel is not always saturated. The details of an example of the content of the yaw rate target value setting unit 4, which is a feature of the present control controlled by the control, are shown as functional blocks. The setting unit 4 includes a linear yaw rate steady target value setting unit 4a, a steady rear wheel steering angle calculation unit 4
b, a steady rear wheel steering angle limiter 4c, a yaw rate steady-state target value setting unit 4d, and a yaw rate transient characteristic target value setting unit 4e.

The linear yaw rate steady-state target value setting section 4a is a setting section for setting a first yaw rate steady-state target value (d / dt) φ _mod . Here, the steady-state target value (d / dt) φ _mod is: Under the condition that the vehicle speed V is constant, the steady rear wheel steering angle calculation unit 4b which is given in proportion to the steering angle θ is set by the steering angle θ and the vehicle speed V and the linear yaw rate steady target value setting unit 4a. According to the first yaw rate steady-state target value (d / dt) φ _mod , the first steady-state characteristic of the own vehicle represented by the stability factor A, the wheelbase L, and the steering gear ratio N of the own vehicle is used to perform the first Yaw rate steady-state target value (d / dt) φ _{mod
Is calculated} (that is, a steady rear wheel steering angle required to obtain the first yaw rate steady target value (d / dt) φ _mod set above).

The steady rear wheel steering angle limiter 4c uses a preset rear wheel steering angle limit δ _RLIM value, and calculates the δ _RLIM value and the rear wheel steering angle calculated by the steady rear wheel steering angle calculation unit 4b. comparing the angular constant value [delta] _ROD, sets the Write absolute value thereof becomes smaller as the stationary rear-wheel steering angle target value [delta] _RO. Here, regarding the first yaw rate steady-state target value setting (setting unit 4a), the designer can arbitrarily give characteristics regardless of the limit value _δRmax of the steering angle control amount in the vehicle. However, the above δ
The absolute value of _RLIM is the maximum turning angle of such rear wheel steering angle δ
_The limiter 4c performs a limit check using δ _RLIM set in advance, and sets δ _RO according to the comparison result.

The steady yaw rate target value setting section 4d is a setting section for setting a final steady yaw rate target value. That is, here, the final yaw rate steady target value (d / dt) φ _mo is determined based on the steering angle θ, the vehicle speed V, and the steady rear wheel steering angle target value δ _Ro determined by the steady rear wheel steering angle limiter 4c. Is set. The yaw rate transient characteristic target value setting section 4e sets a yaw rate and a yaw angular acceleration target value for obtaining a desired transient response.
(d / dt) φ _m and (d ² / dt ² ) φ _m are set, and the rear wheel steering angle calculation unit 5
Performs a control steering angle calculation for realizing these target values.

As described above, the yaw rate target setting section 4, which is a vehicle motion target value setting section, sets a steady-state characteristic and a transient response characteristic with respect to the steering angle input using the reference model for setting a desired response to the steering angle input. However, in this case, the steady-state gain of the yaw rate with respect to the steering angle is given as a function of the steering angle θ as the steering angle θ becomes larger as the steering angle θ increases, as the steering angle θ becomes closer to the base vehicle (2WS). In other words, the steady-state yaw rate value for the steering angle input is set such that it can be achieved with a steering angle amount smaller than the maximum value of the steering angle controllable range.

3 and 4 are flowcharts of an example of a rear wheel steering angle control program according to the present control executed by the controller 3. is there. This program is executed in an interrupt process every fixed time ΔT. Steps 101 to 104 (FIG. 3) and snaps 105 and 106 (FIG. 4) are executed as shown in FIGS.
The reference numerals attached to the corresponding parts in are also added.

In step 100, every time this step is executed, the steering angle θ and the vehicle speed V detected by the sensors 11 and 12 are read, and the rear wheel steering angle (target value) δ _RT is obtained based on these by the following calculation and the like. . That is, step 101 is a process in which the first yaw rate steady target value δ (d / dt) φ _mod is arbitrarily given by the designer.
First, here, (d / dt) φ
_{The mod} is calculated by (d / dt) φ _mod = {V / NnL (1 + AnV ² )} · θ ----- 11 The above means that if V = constant, the (d / dt) φ _mod value will be given in proportion to the steering angle θ, and thus will be a linear yaw rate steady state target value. Note that Nn is a stability factor, An is a steering gear ratio (gear ratio), and L is a wheelbase.
Nn = 13, An = 3.0 × 10 ⁻³ , and L = 2.5 m for the wheelbase.

Next, in step 102, step 10
The steady rear wheel steering angle δ _Rod required to obtain the first yaw rate steady target value (d / dt) φ _mod obtained in 1 is calculated. Here, using the steering gear ratio N of the own vehicle, the wheel base L, and the stability factor A, the value of δ _Rod is calculated as follows: δ _Rod = θ / N-{L (1-AV ² ) / V} · (d / dt) φ _mod ------ Calculated by 12. Here, the stability factor A is
It is given by the following equation from vehicle specifications used in the calculation in step 106 described later. A =-(M / 2L ² ) ・ ｛(L _F・ eK _F -L _R・ K _R ) / (eK _F・ K _R ) 13 ----- 13 where M: vehicle mass, L _F : front wheel −Distance between centers of gravity, L _R :
Rear wheel-center of gravity distance, eK _F : Front equivalent corner rig power, K _R : Rear cornering power

In the following step 103, if the limit check is satisfied, a process for limiting the steady rear wheel steering angle is executed. What shows the contents here is a subroutine program as exemplified in FIG. 5. First, using the calculated value δ _Rod and a preset limit amount δ _RLIM (> 0), δ _Rod ≦ −δ _Check if it is _RLIM (step 200)
If the answer is YES, the steady rear wheel steering angle target value δ _RO is set to −δ _RLIM (step 201), and this subroutine ends. on the other hand,
If the answer is NO and the negative limit is not exceeded, then δ
Check if _Rod ≧ δ _RLIM (Step 202)
If NO, and therefore does not exceed the positive set limit value, the value δ _Rod calculated by the above equation is reset as the target value δ _RO (step 203), and if not, the target value δ _RO is set to δ
_RLIM is set (step 204), and this subroutine is terminated.

Thus, here, the limit amount is δ_RLIMage
And (a) δ_Rod≤- δ_RLIMΔ_RO= -δ_RLIM,
(B) -δ_RLIM <δ_Rod<Δ_RLIMΔ_RO = δ
_Rod, (C) δ_RLIM≤δ_RodΔ_RO= δ_RLIMAnd husband
The positive and negative limit amounts are set in the steady state.
The steady rear wheel steering angle target value is set so as not to exceed
Become. Where δ_RLIMIs the maximum rear wheel steering angle δ _Rmax(> 0)
It is necessary to set it smaller than
In the simulations described below, for example, δ_Rmax= 1
For degrees, δ_RLIMIs δ_RLIM= 0.6 degrees is set.

Returning to FIG. 3, the next step 104 is to set the steady-state rear wheel steering angle target value δ _RO set in step 103 (ie, the δ _RO value set in steps 201, 204 and 203 in FIG. 5). Calculate the yaw rate steady value given. This calculation is performed by the following equation: (d / dt) φ _mo = ∫ ｛V / (1 + Av ² )｝ · (θ / N- δ _RO ) ---------- 14 d / dt) _φmo is used as the final yaw rate steady-state target value.

The following step 105 (FIG. 4) is a yaw rate transient characteristic setting calculation processing for causing the yaw rate to respond to the steering angle input with a first-order delay based on the time constant τ. The yaw rate and yaw angular acceleration target values are as follows. (d / dt) φ _m ,
(d ² / dt ²⁾ to set the phi _m. (d / dt) φ _m = ∫ ((d ² / dt ² ) φ _m ) dt ----- 15 (d ² / dt ² ) φ _m = ((d / dt) φ _mo- (d / dt ) φ _m ) / τ ----- 16 That is, the target yaw angular acceleration value (d ² / dt ² ) φ _m corresponding to the steering angle θ is obtained based on the primary delay system of the time constant τ, and (d ² / dt ² )
Request phi yaw rate should aim by integration of _{m (d / dt) φ m} . In the case of digital computation, when the above _{integral, (d / dt) φ m} = (d / dt) φ m + ΔT · (d 2 / dt 2) is approximated by φ _m ----- 17. This process is performed in a similar manner when the subsequent integration is required.

Next, at step 106, the rear wheel steering angle calculation unit 5
Is performed. Here, the rear wheel steering angle target value δ is calculated based on the well-known equation of motion of the vehicle as follows.
Calculate _RT . That is, the calculation of the rear wheel steering angle that satisfies (d / dt) φ _m and (d ² / dt ² ) φ _m set in step 105 is executed using the dynamic characteristics of the own vehicle. First, for the lateral velocity V _Y , the integral of the previous dV _Y / dt determined as described below, V _Y = ∫ (d / dt) V _Y ----- 18 (V _Y = V _Y + ΔT by · (d / dt) is approximated by V _Y), obtains the V _Y value, based on this with the (d / dt) φ _m, the front wheel side slip angle _{β F, B F = θ /} N- ( determined by _{V Y + L F · (d} / dt) φ m) / V ----- 19, further calculates the following equation a wheel cornering force C _F from the beta _F. C _F = eK _F・ β _F ----- 20 These are estimates of the amount of cornering force generated by the front wheel by the correction, and when the front wheel cornering force comes out, the above-mentioned the wheel cornering force C _R after required to produce the target yaw angular acceleration ^{(d 2 / dt 2) φ} m, C R = {L F · C F - (I z · (d 2 / dt 2) φ m _{/ 2)} / L R -----} 21 (I z: calculating a yaw inertia).

[0026] Thus, obtained by inverse operation subsequent to wheel slip angle beta _R after to obtain the cornering force C _R by _{β R = C R / K R} ----- 22, based on the slip angle beta _R Then, the rear wheel steering angle δ _RT is calculated by the following equation. δ _RT = β _R + (V _Y -L _R・ (d / dt) φ _m ) / V ----- 23 And (d / dt) V _{Y to be} used in the next operation cycle
It is assumed that the value is calculated by (d / dt) V _Y = (2C _F + 2C _R ) · MV · (d / dt) φ _m −−24

Thus, in step 107, the rear wheel steering angle value δ _RT calculated as described above is set as a target value and a signal corresponding to the target value is output to the actuator drive unit 2, and the rear wheel steering mechanism 1 calculates the rear wheels. Steer only the steering angle.

According to the steering angle control as described above, even if the maximum turning angle of the rear wheel, that is, the maximum value of the control steering angle is relatively small (for example, about ± 1 degree), the system is mechanically limited. Even in such a case, the steady-state yaw rate value for the steering angle input can be set so that it can be achieved with a steering angle amount smaller than the maximum value of the steering angle controllable range, and the steering angle is saturated for any steering input. Instead, a desired response intended by the designer can be always obtained at least with respect to the transient response characteristic of the controlled variable.

In this embodiment, step 102, step 103 (FIG. 5), and step 104 after step 101 are performed.
, The steering angle input is relatively small, and δ _Rod-
If δ _RLIM <δ _Rod <δ _RLIM , that is, if δ _RO = δ _Rod (step 204), the final yaw rate steady state target value (d / dt) φ _m is (d / dt) φ _mo = (d / dt) φ _mod . More specifically, in this case, the expression 14 in step 104
Equation 12 in step 102 as the steady rear wheel steering angle target value δ _RO of
Results calculated value [delta] _Rod is applied by a final yaw rate steady target value will be linear yaw rate steady target value according to Equation 11 in step 101 (d / dt) φ _mod as it is set (as described below This means that, for a small to medium steering angle input, an ideal response can be obtained in both the steady and transient characteristics as set by the reference model.) On the other hand, in a range other than the above (δ _Rod ≦ −δ _RLIM , δ _RLIM ≦ δ _Rod ), the value of (d / dt) φ _mo is not set to (d / dt) φ _mod as it is, but The set value in steps 210 and 204 is applied to the δ _RO value of the reference model, the value is set as a value corrected from the value calculated by the equation 11, and as a result, the steady-state characteristics of the reference model depend on the magnitude of the steering angle input. A non-linear characteristic that changes the steady gain is provided.

FIG. 6 shows an example of the relationship between the steering angle and the yaw rate steady-state target value when the vehicle speed is 120 km / h (that is, when V = constant), based on the basic characteristic (2ws), and on the linear standard. This is shown in comparison with the respective models using the model (conventional) ((a) in the figure), and the relationship between the steering angle and the steady value of the rear wheel steering angle at that time is shown in the figure (b). (However, δ
_RLIM = 0.6 degrees). According to the figure, in the case of this control, in the range of small to medium steering angles, the linear reference model (where the linearity is V = constant (120 km / h in this example), It is the same as the characteristic when the steady gain is constant regardless of the magnitude of the angle input, that is, when (d / dt) φ _mo ∝θ ₀ (subscript 0 indicates a steady state). However, in the range where the steering angle is large, the characteristic shown by the solid line is exhibited. Therefore, the steady-state gain of the yaw rate with respect to the steering angle is given as a function of the steering angle, and by providing the nonlinearity that changes the steady-state gain according to the magnitude of the steering angle input, it is possible to perform control in which the rear wheels are not always saturated. The overshoot in the yaw rate response that would occur if the rear wheel steering angle was saturated can be suppressed well (note that reference numerals 4b, 4c, and 4d in FIG. 2).
In FIG. 3, the processing is omitted in steps 102, 103, and 104 of the corresponding processing section, and (d)
/ dt) _φmo , which is equivalent to control by the conventional method).

Hereinafter, a detailed description will be given with reference to simulation results. 7 and 8 show simulation results in the case of this control, FIG. 9 shows an example of setting of the reference model steady-state characteristics, and FIG. 10 shows an example of simulation results in a case where the control steering angle is not saturated. 11,
FIG. 12 shows a simulation result as a comparative example when the control steering angle is saturated.
The following will be described. In this case, the comparative example is based on the control described in “3.1 Yaw rate model adaptation control” of Document 1.

First, the vehicle to be controlled (own vehicle) is
Tability factor A = 1.5 × 10^-3, Steering gear
Ratio N = 15, Wheelbase L = 2.5m. At this time,
Steady yaw when the base vehicle, that is, the rear wheel steering angle is fixed to zero
Late gain G_2ws(V) is expressed as follows. G_2ws(V) = V / NL (1 + AV^Two) ----- 25 On the other hand, the steady-state gain
 G_m(V) allows turning with a smaller steering angle at low speed.
And at high speeds, lower the gain to increase stability.
For example, set as follows. G_m(V) = V / N_nL (1 + AnV^Two) N_n= 13 ----- 26 A_n= 3.0 × 10^-3  The steady-state gain characteristic of the reference model with this setting
Fig. 9 shows the characteristics of the vehicle compared to the base vehicle (2WS).
You.

The above-described reference model has a transient response characteristic of a first-order lag system having no overshoot with respect to the input of the steering angle θ, as shown by the following yaw rate target value (d / dt) φ _m in the following equation. And the constant τ is given by
For example, τ = 0.05 (sec) is set so as to obtain a sufficiently agile response within a range that does not require an excessive load on the actuator. (d / dt) φ _m = G _m (V) ・ {1 / (1+ τS)} ・ θ ---------- 27 where S: derivative operator

FIGS. 10 to 12 show the results of the vehicle motion simulation when the reference model is set and the rear wheel steering angle is controlled in this way. The vehicle speed is 120 km / h. First, FIG. 10 shows that the vehicle speed V =
The rear wheel steering angle and the yaw rate response (Figures (b) and (c)) when a steering input of 30 degrees is given at 120 km / h (Figure (a)) are shown. With a maximum of about 0.7 degrees, the yaw rate has a good response as set in the reference model. However, as shown in FIG. 11, when a large steering angle (60 degrees) is input (FIG. 11B), the rear wheel steering angle (δ _R ) command value exceeds 1 degree (see FIG. 11). (B)). Here, as shown in FIG. 10, when there is no limitation on the rear wheel steering angle control amount (there is no saturation yet), the steering angle input as shown in FIG. steering angle system good response similar to the case of the steering angle input of 30 degrees is where obtained by the reference model, which is limited below the above [delta] _R command value of the steering angle control range of the rear wheel as described above in (Here δ _Rmax = 1
), The rear wheel steering angle is saturated, and there is a tendency for overshoot to occur in the yaw rate response.

FIG. 12 shows a simulation result in a case where a further turning operation is performed from a large steering input (60 degrees). In general, in the case of a 2WS vehicle, an overshoot of the yaw rate occurs as the steering wheel is further turned, and this may trigger a spin.
In the simulation of FIG. 12, in addition to the step steering,
When the rear wheel steering angle is limited, the vehicle behavior with respect to such a turning operation is the same as in the case of 2WS, and an overshoot occurs.

As can be seen from the results of FIGS. 10 to 12, when a linear reference model is given and the rear wheel steering angle control is performed, a small to medium steering angle steering angle input is obtained as shown in FIG. Although sufficient effective control can be performed, when a steering angle of a large steering angle is input so that the steering angle of the rear wheel is saturated (Fig. 11), or when a turning operation is performed after turning at a large steering angle ( In FIG. 12), it is difficult to obtain a sufficient control effect.

On the other hand, the simulation results of FIGS. 7 and 8 by this control are shown in comparison with the cases of FIGS. 11 and 12, respectively, and the same simulation conditions as those of the comparative example (for example, the vehicle speed V = 120 km) / h etc.), the response of the vehicle to which the present control is applied when the same steering angle input is given. In addition, the characteristics of the base vehicle (2WS),
It is also shown in comparison with the case where the rear wheel steering angle control amount is not limited (ideal). Steering angle of large steering angle as shown in FIG.
When this control is applied to the input of (60 degrees) and the increase from the large steering angle input as shown in FIG. 8, the steady value of the yaw rate is limited to the rear wheel steering angle. An ideal transient response without overshoot is realized within a range of the rear wheel steering angle of 1 degree, although it is larger than that in the case where there is no steering wheel angle. Compared with the results of FIGS. 11 and 12, even if the rear wheel steering system has a relatively small maximum value of the steering angle control amount of δ _Rmax = 1 degree, it has good characteristics even with a large steering angle input. As a matter of course, an ideal response for both steady and transient characteristics can be obtained for a small to middle steering angle input as in FIG.

In the above example, each part 4a, 4b, 4 in FIG.
According to c and 4d, and in the program, steps 101 and 101 in FIG.
Although the method of obtaining the final yaw rate steady-state target value as the second yaw rate steady-state target value by 102, 103, and 104 is adopted, as another method, the controller may have the following function. That is, instead of these arithmetic processes,
As shown in FIG. 13, the yaw rate steady-state target value may be given in advance as a function of the steering angle and the vehicle speed. In the case of such a configuration, steps 101 to 104 are programmatically performed.
Is calculated according to the read steering angle θ and the vehicle speed V as shown in FIG.
It replaces the map search process for searching for a corresponding yaw rate steady-state target value from a dimensional map.

Further, the application of the steering angle control according to the present invention is not limited only to the rear wheel steering angle control system based on the yaw rate model adaptation control when the controlled variable is the yaw rate. The same applies to the "3.2 Lateral acceleration model following control" or "3.3 D * model following control" where the lateral acceleration of 1 is the controlled variable, as well as the front wheels and front / rear wheels. Is also applicable in a similar system that electrically steers the vehicle.

In practicing the present invention, when a steady gain of the controlled variable with respect to the steering angle is given as a function of the steering angle, the controlled variable target value with respect to the steering angle θ is
When y _m , the stationary characteristic of y _m is given by the following nonlinear function G _m (θ) with respect to the steering angle θ: y _mo = G _m (θ) · θ ₀ (where y _mo and θ ₀ are (Representing the controlled value and the steady value of the steering angle, respectively). Further, for such G _m (θ), when the electrically controllable steering angle control amount is limited, the absolute value of the amount is set to δ _max , and a predetermined amount smaller than the δ _max is set to δ _LIM (δ _{When LIM} > 0), the function G _m (θ) must be set so that the absolute value of the steady-state value of the control steering angle does not exceed δ _LIM for any steering angle input. Can be.

Furthermore, Japanese Patent Application No. 61-91172 and Japanese Patent Application No. 2-11
The present invention can be similarly applied to a system in which a target value of exercise is set using a reference model and the actual value of the exercise is detected using a sensor to perform feedback compensation, as shown in Japanese Patent No. 5272.

In the following, an example will be described in which the at least one variable relating to the yaw and lateral plane motion of the vehicle is controlled based on signals from both the steering angle sensor and the vehicle speed sensor. Desired steady-state characteristics and transient response characteristics with respect to the steering angle input for the control amount are set by a vehicle motion target value setting unit, and the front wheels or rear wheels are set so that the actual vehicle response matches or follows the motion target value thus set. In the case where the steering angle of the target wheel is electrically controlled such that at least one of the steering angles is calculated by the steering angle calculation unit, and the thus calculated steering angle target value matches the actual steering angle. The steady-state gain of the controlled variable with respect to the steering angle set by the vehicle motion target value setting section is given as a function of the steering angle so that the larger the steering angle, the closer to that of the base vehicle. Contrast there was the, first, vehicle,
A steering mechanism mechanically coupled to the steering wheel,
An electrically controllable auxiliary steering angle control mechanism (front wheel control input) provided on the front wheel, an electrically controllable steering angle control mechanism (rear wheel control input) provided on the rear wheel, and a steering angle calculation unit A front wheel assist steering angle drive unit that drives the front wheel assist steering angle control mechanism so that the actual steering angle matches the calculated front wheel control input value, and a rear wheel control input obtained by the steering angle calculation unit A rear wheel steering angle drive unit that drives a rear wheel steering angle control mechanism so that the actual steering angle matches the actual steering angle; secondly, a steering angle sensor (or a sensor that detects an amount equivalent thereto) and A signal from a vehicle speed sensor (or a sensor for detecting an amount corresponding thereto) is input to input a steering angle for each of a first control amount and a second control amount relating to yaw and lateral plane movement of the vehicle. Steady-state and transient characteristics are set by the vehicle motion target value setting unit The steering angle calculation unit calculates the front wheel control input value and the rear wheel control input value so that the actual vehicle response matches or follows the two motion target values set in this way. In this case, the vehicle motion target value setting The first set in the section
And the target steady-state value of the second controlled variable is a first target steady-state set based on a given steady-state characteristic (steady-state gain) irrespective of a characteristic peculiar to the vehicle for each controlled variable. And a second target steady-state value that is set based on a predetermined steering angle specific to the vehicle, a steady-state characteristic (steady-state gain) of the first and second controlled variables with respect to the front wheel control input and the rear wheel control input. Is set selectively.

In the above selection, the target value setting section preferably sets the limit amount in the front wheel system to Δδ _Fmax when the controllable steering angle amount of the front wheel control input and the rear wheel control input is limited, the limit amount of system and [delta] _Rmax, and each .DELTA..delta _FLIM a predetermined amount less than these .DELTA..delta _Fmax, [delta] _Rmax
(> 0), [delta] when the _RLIM, first absolute value either is .DELTA..delta _FLIM of front and rear wheel control input constant value for realizing the target steady value, if not exceeding [delta] _FRIM, the first target The steady value is selected as the target steady value of the vehicle motion target setting unit, and if any one of them exceeds the value, the second target set value is selected.

Hereinafter, a description will be given with reference to FIGS. 14 to 18 and FIGS. 19 and the like showing the results of the simulation in this example together with comparative examples. FIG. 14 is a hardware configuration diagram of a system to which the front and rear wheel steering angle control in this example is applied. In comparison with FIG. 1, the rear wheel steering mechanism 1R and the rear wheel steering angle drive for driving the same are shown. In addition to the rear wheel steering actuator drive unit 2R as a unit, a front wheel auxiliary steering device including a front wheel auxiliary steering mechanism 1F (auxiliary steering angle control mechanism) and a front wheel auxiliary steering actuator drive unit 2R is provided. Further, the controller 3
Is a vehicle motion target value setting unit 14 for setting a response target value related to yaw and lateral motion with respect to the steering angle input, and a front wheel auxiliary steering angle for realizing the yaw and lateral motion target values set by the setting unit 14. It has each function of the front and rear wheel steering angle calculation unit 15 that calculates the rear wheel steering angle based on the specification values of the own vehicle.

FIG. 15 is a block diagram showing in more detail an example of the contents of the vehicle motion target value setting section 14, which is a feature of this control. In the figure, a first yaw rate / lateral speed steady-state target value setting unit 14a includes a first yaw rate steady-state target value (d) based on arbitrarily given steady-state gains between the steering angle and the yaw rate and between the steering angle and the lateral speed. / dt) φ _mod and the first lateral speed steady-state target value V _Ymod are set by the designer, and the designer can determine the ideal value regardless of the limit values Δδ _Fmax and δ _Rmax of the front and rear rudder angle control amount. A steady gain characteristic can be given.

The steady front and rear wheel steering angle calculation unit 14b is provided with the setting unit
The steady state values of the front and rear wheel steering angles _{Δδ Fod} and δ _Rod necessary to simultaneously achieve the first yaw rate and the lateral speed steady-state target values (d / dt) φ _mod and V _Ymod set in 14a are _calculated based on the steady state of the base vehicle. Calculate based on characteristics. In the steady front and rear wheel steering angle limiter 14c, a preset steady steering angle limit value of the front and rear wheels Δδ _FLIM ,
From δ _RLIM and the steering angle steady values _{Δδ Fod} and δ _{Rod of} the front and rear wheels calculated by the calculation unit 14b, in both front and rear wheels, in a steady state, the front wheel steady steering angle limit value Δδ _FLIM and the rear wheel steady steering angle limit value so as not to exceed the [delta] _RLIM, front and rear wheels constant value Δδ _Fo, δ _Ro
Set. Here, the steady steering angle limit value Δ for the front and rear wheels
For δ _FLIM and δ _RLIM , _respectively , _{Δδ Fmax} > Δδ _FLIM
> 0, is set to [delta] _Rmax> [delta] _FLIM> 0.

The second yaw rate / lateral speed steady-state target value setting section 14d calculates the steering angle θ, the vehicle speed V, and the front and rear wheel steady values Δδ _FO and δ _RO set by the steady front and rear wheel steering angle limiter 14c. Yaw rate steady-state target value (d / dt) φ _mo of the second and the second
Set the lateral speed steady-state target value V _Ymo for. In the vehicle transient characteristic target value setting unit 14e, a yaw rate target value (d / dt) φ _m for obtaining a desired transient response, a yaw angular acceleration target value (d ² / dt ² )
φm, lateral velocity target value V _Ym and lateral acceleration target value α _m are set. The front and rear wheel steering angle calculation unit 15 in FIG. 14 calculates the front wheel auxiliary steering angle target value Δδ _FT and the rear wheel steering angle δ _RT for realizing the target values of yaw and lateral motion set in this way.

The vehicle movement target value setting unit 14 and the steering angle calculation unit 15 described above are realized by a microcomputer program.
Shown in 16 and 17. Note that this program is also executed by an interrupt process for a predetermined time ΔT, and the corresponding steps are also denoted by the reference numerals of the corresponding parts in FIGS.
In FIG. 14, in step 300, a reading process of the steering angle θ and the vehicle speed V is performed in the same manner as in the above-mentioned example.
(d / dt) φ _mod and the first lateral velocity steady-state target value V _Ymod are calculated. (d / dt) φ _mod = G _yrmo (V) ・ θ ----- 28 V _Ymod = G _VYmo (V) ・ θ ----- 29 where G _yrmo (V) and G _VYmo (V ) Is the steady-state gain of the yaw rate and the lateral speed with respect to the steering angle arbitrarily given by the designer as a function of the vehicle speed (Note that G _yrmo (V)
The suffix “yr” in is for yaw rate and the suffix “VY” in G _VYmo (V) is for lateral velocity).

Next, at step 302, the front and rear wheel steering angles for simultaneously satisfying the first yaw rate steady-state target value (d / dt) φ _mod and the first lateral speed steady-state target value V _Ymod obtained at step 301 are described. The steady values _{Δδ Fod} and δ _Rod are calculated according to the following equations, respectively. _{Δδ Fod} = ｛1 / (G _VYFO (V) + G _VYRO (V))｝ ・ ｛(G _VYRO (V) / G _yro (V)) ・ (d / dt) φ _mod + V _Ymod ｝-θ / N ----- 30 δ _Rod = _{Δδ Fod} + θ / N- (1 / G _yro (V)) ・ (d / dt) φ _mod ----- 31 Here, the equation shown above is Each can be derived as follows.

That is, first, the steering angle θ, the front wheel auxiliary steering angle Δδ
_F, Rear wheel steering angle δ_RSteady-state yaw rate for
(d / dt) φ₀And lateral speed V_YOIs written as follows. (d / dt) φ₀= G_yro(V) ・ ｛(θ / N) + Δδ_F-δ_R｝ ---- 32 V_YO = G_VYFO(V) ・ ｛(θ / N) + Δδ_F｝ + G_VYRO(V)_R ---- 33 where G in the above equation is_yro(V), G_VYFO(V), G_VYRO
(V) is based on the well-known linear two-degree-of-freedom vehicle model.
As a function of vehicle speed,
You. G_yro(V) = V / L (1 + AV) ----- 34 G_VYFO(V) = ｛L_R・ V- (M ・ L_F・ V^Three/ 2L ・ K_R)｝ ・ ｛L (1 + AV^Two)｝^-1 ----- 35 G_VYRO(V) = ｛L_F・ V- (M ・ L_R・ V^Three/ 2L ・ eK_F)｝ ・ ｛L (1 + AV^Two)｝^-1 ----- 36 Note that the front wheels are separate from the main steering with the steering wheel.
Front-wheel auxiliary steering system and rear-wheel steering for steering control of the rear and rear wheels, respectively
In the case of a vehicle with a rudder system, a 2-degree-of-freedom secondary model (front wheel supplementary
In assist steering + rear wheel steering), the equation of motion is
expressed. I_Z・ (D^Two/ dt^Two) φ = 2L_F・ C_F-2L_R・ C_R ----- 37 M ・ α = M ((d / dt) V_Y+ V ・ (d / dt) φ) = 2C_F+ 2C_R ----- 38 where α: lateral acceleration dV_Y Front and rear wheel cornering force C_F, C_R, Next to the front and rear wheels
Slip angle β_F, β_RAre as follows respectively. C_F= eK_F・ Β_F  C_R= K_R・ Β_R ----- 39 β_F= θ / N + Δδ_F-(V_Y+ L_F・ (D / dt) φ) / V β_R= δ_R-(V_Y-L_R・ (D / dt) φ / V ----- 40

Here, in the steady state, (d / dt) φ ₀ =
_{(d / dt) φ mod,} V YO = V Ymo s respectively front and rear wheel steering angle value which satisfies .DELTA..delta _Fod, when the [delta] _Rod, firstly, the following relationship is obtained from the equation 32. That is, in Equation 32, (d / dt) φ _{0 is changed} to (d / d
t) φ _mod , δ _Ro to _{Δδ Fod} , and δ _R to δ _Rod
Then, when rearranging each other for δ _Rod , the above-mentioned equation 31 of δ _Rod = _{Δδ Fod} + θ / N- (1 / G _yro (V)) · (d / dt) φ _mod is obtained. Further, similarly, the following expression is obtained from Expression 33 and Expression 31. V _Ymod = G _VYFO (V) ・ ｛(θ / N) + _{Δδ Fod} ｝ + G _VYFO (V) ・ ｛ _{Δδ Fod} + θ / N- (1 / G _yro (V)) ・ (d / dt) φ _mod ----- 41 41 _整理 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41.
Equation 28 described above is obtained. By the above, step
The operation expression at 302 is derived.

Next, at step 303, a limit check and setting process for the steady front and rear wheel steering angles are performed by a subroutine program as exemplified in FIG. In the figure, step 400, 401, respectively stationary steering angle of the aforementioned front and rear wheels limit .DELTA..delta _FLIM, with _{δ RLIM | Δδ Fod | ≦ Δδ} FLIM,
| Δ _Rod | ≦ δ _RLIM is a discrimination step, and the front and rear wheel steering angle steady value Δ calculated in step 302 is
If _both the absolute values of δ _Fod and δ _Rod | _{Δδ Fod} │ and _{│δ Rod} │ are less than or equal to _{Δδ FLIM} and δ _RLIM (when the answers of steps 400 and 401 are both YES), in this example, step 402
Then, the front wheel steady value Δδ applied to the calculation in step 304 described later
_{As FO} and the rear wheel steady value δ _RO , _{Δδ FO} = _{Δδ Fod} ,
This program ends with δ _RO = δ _Rod .

On the other hand, the calculated front and rear wheel steering angle steady values _{Δδ Fod} , δ
Limit any either one of the absolute value of the _{Rod Δδ FLIM,}
If it is _larger than δ _RLIM (when at least one of the answers in steps 400 and 401 is NO), in this example, first in step 403
In the above, the ratios γ _F , γ _R are calculated by the following equations, respectively: γ _F = _{Δδ FLIM} / | _{Δδ Fod} | ---- 42 γ _R = δ _RLIM / | δ _Rod | ---- 43 At 404, it is determined whether or not γ _F ≦ γ _R. According to the above determination result, if the answer is YES, the smaller of γ _F and γ _R is used as a correction coefficient, and in step 405, the following equation is obtained: _{Δδ FO} = γ _F · _{Δδ Fod} ---- 44 δ _RO = γ _F・According to δ _Rod ---- 45, if the other answer is NO, in step 406, _{Δδ FO} = γ _R・_{Δδ Fod} ---- 46 δ _RO = γ _R・ δ _Rod ---- 47, respectively _Change the corresponding correction coefficient to the calculated value δ _Fod , δ
_The value obtained by multiplying _Rod is the front and rear wheel steady value Δδ _FO , δ _RO
And the subroutine is terminated.

Returning to FIG. 16, a step following step 303
In 304, the front and rear wheel steady values Δδ _FO , δ thus set
_{Using RO} , the following equations according to the above equations 32 and 33, respectively, (d / dt) φ _mo = G _yro (V) ・ ｛(θ / N) + Δδ _FO -δ _RO ｝ ----- 48 V _Yom = G _VYF (V) ・ ｛(θ / N) + _{Δδ FO} ｝ + G _VYRO (V) ・ δ _Ro ----- Based on the second yaw rate steady-state target value (d / dt) φ _mo And a second lateral speed steady-state target value V _Yom is set.

By the above processing, the steady-state target values of the yaw rate and the lateral speed as the controlled variables are determined by the above-described steps.
The first yaw rate steady target value at 301 (d / dt) _mod and a first lateral speed steady target value V _Ymod or as it is, the second yaw rate steady target value (d / dt) φ _mo and second lateral It will be selectively set to one of the steady-state speed target values V _Ymo .
For example, as for the steady-state target value of the yaw rate, when _{Δδ FO} = _{Δδ Fod} , δ _RO = δ _Rod is set in step 402, the right side of the equation 48 is expressed by G _yro (V) ・ ｛(θ / N) + _{Δδ Fod} -Δδ _Rod ｝ = G _yro (V) ・ ｛(θ / N) + _{Δδ Fod-Δδ Fod-} (θ / N) + (1 / G _yro ( V)) · (d / dt) φ _mod ｝ = (d / dt) φ _mod , which means that the first yaw rate steady target value is obtained. The same applies to the target steady-state value of the lateral acceleration.

Thus, in this example, each target steady-state value is set as a first target steady-state value set based on arbitrarily given steady-state characteristics that the designer considers ideal for each controlled variable. (D / dt) φ _mod , V _Ymod and the second target steady state which is set based on the previously determined vehicle-specific steering angle, the steady-state characteristic of the controlled _variable with _respect to the front wheel control input and the rear wheel control input. (d / dt) φ _mo and V _Ymo are selectively switched and set. Limited to controllable steering angle
When there is (Δδ _Fmax, δ _Rmax ), the target steady-state values of the yaw rate and the lateral speed are not set uniformly by the reference model, but the front-wheel and rear-wheel control input steady-states for realizing the first target steady-state value are obtained. If the absolute values of the values _{Δδ Fod and Δδ Rod} do not exceed the limit values _{Δδ FLIM} and δ _RLIM , the first target steady-state value is selected as the target steady-state value of the vehicle motion target value setting unit. If any one of them is exceeded, the second target steady-state value is selected.

This focuses on the following yaw rate, lateral speed, and lateral acceleration responses in a vehicle. That is, similarly to the above example, the stability factor A, the steering gear ratio N, and the wheelbase L
Is a vehicle with A = 2 × 10 ⁻³ , N = 15, L = 2.5 m, and a vehicle subject to front and rear wheel steering angle control is considered. _{Is set} to zero, the steady-state yaw rate gain G _yro2ws (V) is _expressed by G _yro2ws (V) = V / NL (1 + AV ² ) 50 as in the case of Equation 25. On the other hand, first, a yaw rate reference model for setting a yaw rate response target has a steady-state gain that is the same as that of the base vehicle and a transient characteristic that is a first-order lag with respect to the steering angle input as follows. Shall be set to (d / dt) φ _m = G _yrmo (V) ・ ｛1 / (1+ τ _yr S)｝ ・ θ G _mo (V) = G _yr2ws (V) ----- 51 (d / dt) φ _m : target yaw rate τ _yr : time constant On the other hand, it is generally said that the lateral speed (side slip angle = lateral speed / vehicle speed) is preferably zero or desirable. Therefore, the lateral speed target value V _Ym is Give as follows. V _Ym = 0 ----- 52

The target characteristics of the yaw rate and the lateral speed are set as described above, and the vehicle having the maximum control steering angle of 1 degree in both the front and rear directions is controlled by the method shown in "3.1 Front and rear wheel steering angle system" of Document 2 described above. The results of the vehicle motion simulation are shown in FIGS. Figures 19 and 20 and Figures 21 and 22 show vehicle speed
When a step-like steering angle is input at V = 180km / h (Fig.
The front wheel control steering angle (each (b)), rear wheel steering angle (each (c), yaw rate (each (d)), and lateral acceleration (see Figs. 20, 22) (E) and lateral speed (each (f)). As shown in FIGS. 19 and 20, when the steering angle input is small (10 degrees), the front and rear wheels In both cases, the control steering angle is within 0.5 degrees, the yaw rate and the lateral acceleration have a very good characteristic of a first-order lag with respect to the steering angle input, and the lateral speed always keeps zero.

On the other hand, when a relatively large steering angle (here, 30 degrees) is inputted as shown in FIGS. 21 and 22, the control steering angle command values for the front wheels and the rear wheels exceed 1 degree. In this case, when a limit of 1 degree at the maximum is set by the mechanical steering angle limiting mechanism, each actual value is limited to 1 degree by the mechanical steering angle limiting mechanism ((b), (c) )). As a result, the yaw rate, the lateral acceleration, and the lateral speed greatly deviate from the target values, respectively ((d), (e), (f)). Although the response is still good as compared with the base characteristic without control, the oscillatory behavior of the base control appears to some extent. The yaw rate has an overshoot, and the lateral velocity has an oscillating behavior in the transient characteristics, and the lateral acceleration also has an overshoot. When the front and rear wheel steering angle control method based on the linear theory is applied to a system in which the control steering angle is limited, the control steering angle is saturated with a large steering angle input, and it is difficult to obtain a sufficient control effect. In order to suppress and mitigate such behavior as described above, in order to set the target set values of the yaw rate and the lateral speed so that the control steering angles of the front wheels and the rear wheels do not steadily saturate for any steering angle input, The calculation of the above steps 302, 303, 304 (corresponding portions 14b, 14c, 14d in FIG. 15) is to be introduced to the setting of the target steady-state value.

In the flowchart of FIG. 18, if the absolute values of the front and rear wheel steering angle steady values _{Δδ Fod} and δ _Rod are both equal to or less than the limit values _{Δδ FLIM} and δ _RLIM , steps 402 and 304 are skipped. Therefore (d / dt) φ _m0 = (d / dt)
φ _mod, placed directly with the V _Ymo = V _Ymod, step described below
305 The following process may be performed. (D / dt) φ _m0 , V
The _{Ymo, (d / dt) φ} m0 = (d / dt) φ mod, if you put a V _Ymo = V _Ymod, the same control system as a conventional method (Reference 2,3.1).

When the process proceeds from step 304 to step 305, the target yaw rate value (d / dt) φ _m and the target yaw angular acceleration value (d ² ) are set to obtain a desired transient response to the steering input. / dt ² ) Calculate φ _m , target lateral velocity V _Ym , and target lateral acceleration α _m . First, as the yaw rate target value calculation, the yaw angular acceleration target value (d ² / dt ² ) φ _m = ((d / dt) φ _mo- (d
/ dt) determine the _{φ m) / τ yr, (} d 2 / dt 2) φ m integral (approximate calculation) by at yaw rate should aim (d / dt) phi _m (here in, the primary delay due tau _yr ). In this embodiment, an arithmetic expression is given so that the yaw rate has a first-order delay with respect to the steering angle input, and an arithmetic expression is given so that the lateral velocity has a second-order delay of the damping coefficient 1.
That is, in the calculation of the target value of the lateral speed and the lateral acceleration, the lateral speed V _Ym and the lateral acceleration α _m to be targeted are obtained based on the following equations. V _Ym = ∫ ((d / dt) V _Ym ) dt ----- 53 (However, V _Ym = V _Ym + ΔT ・ (d / dt) Approximate calculation using V _Ym ) (d / dt) V _Ym = ∫ ((d ² / dt ² ) V _Ym ) dt ----- 54 (However, (d / dt) V _Ym = (d / dt) V _Ym + ΔT ・ (d ² / dt ² )
Approximate calculation using V _Ym ) (d ² / dt ² ) V _Ym = (V _Ym0 -V _Ym -2 ・ τ _VY・ (d / dt) V _Ym ) / τ _VY ² ----- 55 (where τ _(VY : time constant) α _m = (d / dt) V _Ym + V ・ (d / dt) φ _m ----- 56

In the next step 306, the front and rear wheel steering angles for the actual vehicle behavior to coincide with the vehicle motion target value set in step 305 are derived by using the inverse calculation of the two-degree-of-freedom vehicle motion equation described above. . That is, first, the front and rear wheel cornering forces C _F and C _R for obtaining the exercise target value are calculated by the above equations.
(D ² / dt ² ) φ at 37, 38, the following equation rearranged for C _F , C _R by applying the calculated value (d ² / dt ² ) φ _m at step 305 as α, α _m , C _F = (M ・ L _R・ α _m + Iz ・ (d ² / dt ² ) φ _m ) / 2 ・ L ----- 57 C _R = (M ・ L _F・ α _m + Iz ・ (d ² / dt ² ) φ _m ) / 2 · L ----- Obtained from 58.

Hereafter, the front and rear wheel slip angles β _F and β _R for obtaining these cornering forces by the inverse operation are calculated as follows: β _F = C _F / e K _F ----- 59 β _R = C _R / K _R ----- 60 (inverse calculation of the above equation 39), and then, based on these, the target values Δδ _FT , δ _R of the front wheel auxiliary steering angle and the rear wheel steering angle are calculated. Here, in view of the above Equation 40, these are Δδ _FT = β _F + (V _Ym + L _F・ (d / dt) φ _m ) / V− (θ / N) ----- 61 δ _R = β _R + (V _Ym + L _R・ (d / dt) φ _m ) / V ----- 62, and therefore, according to the above equations 61 and 62, and set in step 305 (d / dt ) By using φ _m and V _Ym , a front wheel auxiliary steering angle Δδ _FT and a rear wheel steering angle δ _RT to be targeted are calculated.

Thus, in the output processing of the next step 307, signals corresponding to these calculated values (command values) are output to the actuator driving sections 2F, 2R, and the front and rear wheels are steered by the corresponding steering mechanisms 1F, 1R, respectively. Control.

According to the present control, the steady target values of the yaw rate and the lateral speed with respect to the steering angle input can be achieved with a steering angle amount smaller than the maximum value of the front and rear wheel steering angle controllable range. Even when the steering angle is input, the front and rear wheel steering angles are not saturated, and a desired transient response intended by the designer with respect to yawing and lateral motion can always be obtained.

FIGS. 23 and 24 show a case where this control is applied.
In the results of the meeting, the vehicle speed was 18 as in the case of FIGS.
When the steering angle is 30 degrees at 0 km / h ((a) in Fig. 23)
Vehicle behavior ((b), (c), (d), and FIG.
(E) and (f)). Here in this simulation
In this case, the first yaw rate steady-state target value and the first lateral speed
The steady-state gain for setting the steady-state target value is G
_yrmo = G_yro (Same as steady yaw gain of base car)
1), G_VYmo = 0, yaw rate and lateral speed
The transient response characteristics are set as follows. (d / dt) φ_m= G_yrmo・ ｛1 / (1+ τ_yrS) ----- 63 (τ_yr = 0.05 sec) V_Ym = G_VYmo・ ｛1 / (1+ τ_VYS) (1+ τ_VYS)｝ = G_VYmo・ ｛1 / (1 + 2τ_VYS + τ_VY ^TwoS^Two)｝ ----- 64 (τ_VY = 0.2 sec) Also, the steady steering angle limit value Δδ for the front and rear wheels_FLIM, δ_RLIMYes
The gap is set at 0.6 degrees. Further, (d) of FIG.
The ideal values in (e) and (f) of FIG.
This corresponds to a case where the steering angle control amount is not limited.

Referring to the results of FIGS. 23 and 24, in the case of this control, the steering angle of 30 degrees at which the control steering angle would be saturated if it was the same as that of the comparative example of FIGS. The turning angle of the front and rear wheels is less than 1 degree for the input (Fig.
23 (b) and (c)), the yaw rate agrees well with the ideal response (ibid.). In addition, the following can be seen for the lateral speed and the lateral acceleration. That is, although the lateral speed is generated to some extent in a steady state, it is lower than that of the base vehicle, and the transient characteristic does not show any oscillating behavior ((f) in FIG. 24). Also, as for the lateral acceleration, it takes a longer time to reach a steady state as compared with the ideal response, but good characteristics without overshoot can be obtained. As shown above,
The results of 23 and 24 show that the application of this control makes it possible to obtain better characteristics even with a large steering angle input than the results of the comparative example of FIGS. 21 and 22. It can be seen that even in a system in which the maximum value of the control amount is relatively small, the effect of the front and rear wheel steering angle control can be exerted even at a large steering input. Of course, a very good vehicle response similar to that shown in FIGS. 19 and 20 can be obtained for a small steering input.

In this embodiment, similarly to the above-described embodiment, it is also possible to adopt a method of searching for a steady-state target yaw rate target value and a steady-state lateral speed target value from a map. That is, as a configuration method of this control, the (d / dt) φ _mo value and V _Ymo
In addition to the method of calculating the values, the calculations in steps 301 to 304 are calculated in advance for the entire possible range of the steering angle and the vehicle speed, and the steady-state target values (d / dt) φ _mo of the yaw rate and the lateral speed with respect to the steering angle input are calculated. , V _Ymo can be given in the form of a map for each vehicle speed as a function of the steering angle.

Although the above description has been made in comparison with the feed-forward type front and rear wheel steering angle control method described in 3.1 of Document 2 above, the present invention provides a feedback control system as disclosed in Japanese Patent Application No. 2-115273. Is similarly applicable.

[0070]

According to the present invention, when setting a steady-state characteristic and a transient characteristic with respect to a steering angle input for a motion control amount,
The steady gain of the motion control amount with respect to the steering angle is given as a function of the steering angle so that the steady gain changes according to the magnitude of the steering angle input. It can be set to be achievable with a steering angle smaller than the maximum value of the possible range, and can be controlled in a region where the steering angle does not saturate even for a large steering angle input, and the transient response of the motion control amount It is easy to realize that the characteristics are those of the response intended by the designer.

Further, according to the present invention, the first
And the steady-state target value of the second motion control amount can be set to be achievable with a steering angle amount smaller than the maximum value of the front and rear wheel steering angle controllable range. On the other hand, the front and rear wheel steering angles do not saturate, and therefore, it is easy to obtain the transient response intended by the designer with respect to yawing and lateral motion in front and rear wheel steering angle control using two motion control amounts. Things.

[Brief description of the drawings]

FIG. 1 is a hardware block diagram showing an embodiment of the apparatus of the present invention.

FIG. 2 is a block diagram showing an example of the content of a yaw rate target value setting unit of the example.

FIG. 3 is a flowchart showing an example of the control program of the same example in a divided manner, and showing a part of the flowchart.

FIG. 4 is also a diagram showing another part.

5 is a program flowchart showing an example of the content of step 103 in FIG. 3;

FIG. 6 is a diagram illustrating an example of a relationship between a steering angle and a steady yaw rate target value, and a relationship between a steering angle and a rear wheel steering angle steady value, which are used to describe features of the embodiment device.

FIG. 7 is a diagram showing an example of the effect of the embodiment device,
It is a figure showing a simulation result at the time of large rudder angle input.

FIG. 8 is a view showing a simulation result at the time of a further cutting operation.

FIG. 9 is a diagram illustrating an example of a steady-state characteristic setting of an applicable reference model.

FIG. 10 is a diagram illustrating an example of a simulation result when the control steering angle in the steering angle control using the reference model is not saturated.

11 is a diagram illustrating a simulation result when the control steering angle is saturated in a comparative example shown in comparison with FIG. 7;

FIG. 12 is a view showing a simulation result in a comparative example shown in comparison with FIG. 8;

FIG. 13 is a diagram for explaining another configuration method of the embodiment device, showing an example of the characteristic when a map is used.

FIG. 14 is a hardware block diagram showing an apparatus according to another embodiment of the present invention.

FIG. 15 is a block diagram showing an example of the contents of a vehicle motion target value setting unit of the example.

FIG. 16 is a flowchart showing an example of the control program of the same example in a divided manner, showing a part of the flowchart.

FIG. 17 is a view showing another part in the same manner.

18 is a program flowchart showing an example of the contents of step 304 in FIG. 16;

FIG. 19 is a diagram illustrating an example of a simulation result when the control steering angle in the front and rear wheel steering angle control is not saturated, and a diagram illustrating a part thereof;

FIG. 20 is a view showing another part in the same manner.

FIG. 21 is a diagram showing a simulation result when the control steering angle is saturated as a comparative example, and showing a part of the simulation result.

FIG. 22 is a view showing another part in the same manner.

FIG. 23 is a diagram corresponding to FIGS. 21 and 23, showing a simulation result for explaining the effect of the embodiment device, and showing a part thereof.

FIG. 24 is a diagram showing another part in the same manner.

[Explanation of symbols]

 1 Rear wheel steering mechanism 1R Rear wheel steering mechanism 1F Front wheel steering mechanism 2 Actuator drive 2R Rear wheel actuator drive 2F Front wheel actuator drive 3 Controller 4 Yaw rate target value setting section 4a Linear yaw rate steady target value setting section 4b Steady rear wheel steering Angle calculation unit 4c Steady rear wheel steering angle limiter 4d Yaw rate steady target value setting unit 4e Yaw rate transient characteristic target value setting unit 5 Rear wheel steering angle calculation unit 11 Steering angle sensor 12 Vehicle speed sensor 14 Vehicle motion target value setting unit 14a First Steady yaw rate and lateral speed target value setting unit 14b Steady front and rear wheel steering angle calculation unit 14c Steady front and rear wheel steering angle limiter 14d Second yaw rate and lateral speed steady target value setting unit 14e Vehicle transient characteristic target value setting unit 15 Front and rear wheel steering angle Calculation section

Continuation of the front page (56) References JP-A-61-146676 (JP, A) JP-A-61-244670 (JP, A) JP-A-2-18168 (JP, A) JP-A-3-10970 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 6/00 B62D 7/14 B62D 101: 00 B62D 113: 00 B62D 137: 00

Claims (5)

(57) [Claims] 1. A steering angle control mechanism capable of controlling a steering angle of at least one of a front wheel and a rear wheel, and a drive for driving a mechanism according to a steering angle control input such that an actual steering angle matches a control input value. Department have a steering device including a control object wheel
The vehicle movement that is to be realized by controlling the steering angle
Vehicle yawing motion control amount so as to achieve the target vehicle motion
Control of at least one of the vehicle and the lateral motion control amount
Angle Control in a Four-Wheel-Steered Vehicle Controlling the Amount
A detecting means for detecting a steering angle of the steering wheel or an amount corresponding thereto; a detecting means for detecting a vehicle speed or an amount corresponding thereto; and an output from the detecting means, the output of which is used as the motion control amount . Then, set the steady-state characteristics and transient characteristics for the steering angle input.
That car and both exercise target value setting means, and calculates the steering angle control input values of the controlled wheel so that the actual vehicle response to movement target value set by said vehicle movement target value setting means coincides or follows wherein a steering angle controller you and a steering angle calculating means for instructing the steering system, the steering angle set by said vehicle movement target value setting means
The steady gain of the motion control amount depends on the magnitude of the steering angle input.
As a function of the steering angle so that the steady gain changes accordingly.
A steering angle control device for a vehicle, characterized in that the steering angle control device is provided. 2. A target value y of a motion control amount with respect to a steering angle θ.
_m is a non-linear function G _m
The (theta), the following _{equation, y mo = G m (θ} ) · θ 0 However, y _mo goals steady value of motion control amount, theta ₀ is a steering angle theta
The vehicle steering angle control device according to claim 1, wherein the vehicle steering angle control device is set as a steady value . 3. A controllable steering angle control amount of a wheel to be controlled.
When there is a limit, the amount of the limit is δ _max ,
When a predetermined amount smaller than δ _max is δ _LIM ,
When the steering angle is input, the steady value of the control
Non-linear function G _m (θ) is set so as not to exceed δ _LIM
It is the vehicle for steering angle control apparatus according to claim 2, wherein a. 4. A front wheel assist steering device comprising: an auxiliary steering angle control mechanism capable of controlling a steering angle of a front wheel; and a drive unit for driving the mechanism such that an actual steering angle matches a control input value according to a front wheel control input. A steering angle control mechanism capable of controlling the steering angle of the rear wheels, and a rear wheel steering device including a drive unit that drives the mechanism so that the actual steering angle matches the control input value according to the rear wheel control input. By controlling the steering angle of the front and rear wheels
The yaw and lateral movements of the vehicle are the target
Vehicle yawing motion control so as to perform
And the vehicle lateral motion control amount is set to the second motion control amount.
These first and second motion control amounts are controlled as motion control amounts.
A steering angle control device for a four-wheel steering vehicle, a detecting means for detecting a steering angle of a steering wheel or an amount corresponding thereto, a detecting means for detecting a vehicle speed or an amount corresponding thereto, The first and second
And car both exercise target value setting means to set the steady-state characteristics and transient characteristics to the steering angle input for each of the motion control amount s, the first motion set by said vehicle movement target value setting means
The front wheel steering angle input value and the rear wheel steering angle input value are calculated respectively so that the actual vehicle response matches or follows the movement target value of the control amount and the movement target value of the second movement control amount. wherein a front wheel auxiliary steering system and a steering angle control device you and a steering angle calculating means for instructing the rear wheel steering device, the first and second set in said vehicle motion target value setting means
The target steady-state value of the motion control amount depends on the steering angle input regardless of the characteristic of the control target vehicle.
A desired first motion control amount and second motion control amount are obtained.
Steady state characteristic for a first motion control variable that can be set to
And a first steady-state characteristic for the second motion control amount.
A first target setting related to a first motion control amount, which is set individually
The first target steady-state value relating to the normal value and the second motion control amount
And the vehicle specific set in advance for the vehicle to be controlled.
No. of steering angle, front wheel control input and rear wheel control input
Second steady state characteristic and second movement control for one movement control amount
The first operation set based on the second steady-state characteristic for the quantity.
Second target steady value related to movement control amount and the second motion control
A steering angle control device for a vehicle, which is selectively set from a second target steady-state value related to an amount . 5. Limiting the controllable steering angle of the front wheel control input
If there is a limit amount of Δδ _Fmax , rear wheel control
When there is a limit on the amount of controllable steering angle,
The amount of restriction and [delta] _Rmax, and where less than the .DELTA..delta _Fmax
A predetermined amount is Δδ _FLIM , and a predetermined amount smaller than δ _Rmax is δ
_RLIM , a first target steady-state value for the first motion control amount and a second
For realizing the first target steady-state value related to the motion control amount.
Both the front wheel control input value and the rear wheel control input value
If the specified amount _{Δδ FLIM} and the specified amount δ _RLIM are not exceeded,
A first target steady-state value related to the first motion control amount and a second target steady-state value;
The first target steady-state value relating to the motion control amount of the vehicle
The first motion control amount and the second motion control amount of the value setting means
Selected as the target steady-state value for
The second target steady state for the first motion control amount.
Value and a second target steady-state value relating to the second motion control amount.
The first movement control amount and the second movement control amount of both movement target value setting means.
5. The vehicle steering angle control device according to claim 4 , wherein the control value is selected as a target steady value related to the dynamic control amount .