JP2940371B2 - Auxiliary steering angle control device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary steering angle control device for a vehicle which gives an auxiliary steering angle by yaw rate feedback control or the like.

[0002]

2. Description of the Related Art Conventionally, as an auxiliary steering angle control device for a vehicle for giving an auxiliary steering angle to rear wheels by feedforward control and yaw rate feedback control, for example, Japanese Patent Application Laid-Open No.
An apparatus described in Japanese Patent No. 18168 is known.

This conventional source has a reference model that is a desired yaw rate response model, determines a yaw rate target value using a vehicle speed, a steering angle, and a reference model, and obtains the yaw rate target value by interposing a delay element. A technique has been disclosed in which a value obtained as a yaw rate estimated value used in a yaw rate feedback system allows the feedback system to operate only when mainly absorbing disturbances and parameter fluctuations.

[0004]

However, in the above-mentioned conventional auxiliary steering angle control device for a vehicle, yaw rate feedback control is performed using a yaw rate deviation which is a difference between a reference yaw rate and a vehicle yaw rate. When the driver gives the correct rudder when the vehicle slips on a road or the like, or when the driver performs drift traveling of the vehicle, the driving state with the counter applied, that is, turn the steering wheel in the opposite direction to the vehicle turning direction In the driving state, the driver attempts to control the vehicle behavior by operating the steering wheel as intended, but in the feedback system, the standard yaw rate required by the vehicle speed and the steering angle is greatly shifted, and as a result, the rear wheel steering angle is also obtained. The steering is shifted with respect to the desired vehicle behavior, which gives the driver an uncomfortable feeling.

[0005] Therefore, the yaw rate deviation greatly shifts,
If the yaw rate deviation exceeds the threshold value, it is determined that the vehicle is in the counter running state, and the feedback control is stopped.

However, in this control, if the yaw rate deviation threshold value given as a fixed value is set to a large value, the counter running judgment is delayed when the vehicle is running on a low μ road, and the feedback control is not interrupted, and the running is such that the counter is immediately applied. The effect of the control suspension is reduced. On the other hand, if the yaw rate deviation threshold value is set to a small value, it is erroneously determined that the vehicle is running in the counter mode when traveling on a high μ road, and the function of the yaw rate feedback control is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem. An object of the present invention is to provide an auxiliary steering angle control device for a vehicle that provides an auxiliary steering angle by yaw rate feedback control or the like. It is an object of the present invention to ensure both vehicle behavior stability during counter running and disturbance stability during high μ road running.

[0008]

According to the first aspect of the present invention, a vehicle speed detecting means a, a steering steering angle detecting means b, and a vehicle speed detecting means are provided. A motion state quantity estimating means c for estimating a motion state quantity generated in the own vehicle based on the detected value and the steering steering angle detection value, and a motion state quantity detecting means d for detecting the same kind of motion state quantity as the estimated motion state quantity Motion state quantity deviation calculating means e for calculating a deviation between the motion state quantity detection value and the motion state quantity estimation value; and an auxiliary steering angle feedback target for calculating an auxiliary steering angle feedback target value by compensation based on the motion state quantity deviation. Value calculation means f; road surface friction coefficient equivalent value detection means g for detecting a road surface friction coefficient equivalent value; and the motion state quantity deviation threshold value is set to a larger value as the road surface friction coefficient equivalent value is larger. Corners above a predetermined value, and, when the calculated motion state quantity deviation is more than the motion state quantity deviation threshold value,
Operate the steering wheel in the direction to cancel the occurrence of the motion state quantity.
A counter traveling determining means h for determining that the vehicle is in the counter traveling state irrespective of whether the vehicle is in the counter traveling state,
Counter running corresponding target value correcting means i for correcting the auxiliary steering angle feedback target value in the direction in which the feedback control is stopped, and control for obtaining an uncorrected auxiliary steering angle feedback target value or a corrected auxiliary steering angle feedback target value And an auxiliary steering angle control means k for outputting a command to the auxiliary steering angle actuator j.
Here, the “counter running state” used in the present invention refers to a turning state.
The motion state quantity deviation calculated at the time of
Means running conditions that satisfy the condition
And steer in the direction to cancel the so-called motion state quantity
It does not simply mean running by counter operation
Absent.

The road surface friction coefficient equivalent value detecting means g calculates, for example, a lateral acceleration deviation which is a difference between an estimated lateral acceleration based on a yaw rate detection value from a yaw rate sensor and an actual lateral acceleration from a lateral acceleration sensor. Means is used for detecting that the larger the lateral acceleration deviation is, the lower the road friction coefficient is.

[0010]

When the vehicle is running, the motion state quantity estimating means c
The motion state amount generated in the own vehicle is estimated based on the vehicle speed detection value from the vehicle speed detection means a and the steering angle detection value from the steering angle detection means b, and the motion state amount detection means d
In the above, a motion state quantity of the same kind as the estimated motion state quantity is detected, and a deviation between the motion state quantity detection value and the motion state quantity estimation value is calculated by the motion state quantity deviation calculating means e. In the value calculation means f, an auxiliary steering angle feedback target value is calculated by compensation based on the motion state quantity deviation.

On the other hand, in the counter running judgment means h,
As the road surface friction coefficient equivalent value from the road surface friction coefficient equivalent value detection means g is larger, the motion state amount deviation threshold value is set to a larger value, the steering angle is equal to or more than a predetermined value, and the calculated motion state amount deviation is larger. When is greater than or equal to the motion state deviation threshold , operate the steering wheel in the direction to cancel the occurrence of the motion state quantity.
It is determined that the vehicle is in the counter traveling state regardless of whether the vehicle is in the counter traveling state, and the counter traveling corresponding target value modifying means i modifies the auxiliary steering angle feedback target value in the direction of stopping the feedback control when the counter traveling is determined.

The auxiliary steering angle control means k outputs to the auxiliary steering angle actuator j a control command for obtaining an auxiliary steering angle feedback target value which is not corrected or a corrected auxiliary steering angle feedback target value.

Therefore, when the vehicle is traveling on a low μ road, the movement state quantity deviation threshold value used for the judgment of the counter traveling is set to a small value. It is determined that there is, and the auxiliary steering angle feedback target value is corrected in the direction in which the feedback control is stopped, thereby preventing the driver from feeling uncomfortable by the feedback control of the vehicle behavior. In addition, when traveling on a high μ road, the threshold value of the motion state amount deviation used for the judgment of the counter traveling is set to a large value. Is not erroneously determined, and normal feedback control is executed, so that disturbance stability is ensured by the feedback control.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

The configuration will be described.

FIG. 2 is an overall system diagram showing a four-wheel steering vehicle to which the vehicle auxiliary steering angle control device according to the embodiment of the present invention is applied.

In FIG. 2, the front wheels 1 and 2 are steered by a steering handle 3 and a mechanical link type steering mechanism 4.
Done by This includes, for example, a steering gear, a pitman arm, a relay rod, side rods 5, 6, knuckle arms 7, 8, and the like.

The turning of the rear wheels 9, 10 is performed by an electric steering device 11 (corresponding to an auxiliary steering angle actuator j). The rear wheels 9, 10 are connected by a rack shaft 12, side rods 13, 14, and knuckle arms 15, 16, and a rack tube 17 in which the rack 12 is inserted has a speed reduction mechanism 18 and a motor 19.
The motor 19 and the fail-safe solenoid 20 are provided with a vehicle speed sensor 21 (corresponding to a vehicle speed detecting means a) and a front wheel steering angle sensor 22.
(Corresponding to steering steering angle detecting means b), rear steering angle sub-sensor 23, rear steering angle main sensor 24, yaw rate sensor 25 (corresponding to motion state amount detecting means d), lateral acceleration sensor 27, brake switch 28, etc. Is driven and controlled by the controller 26 which inputs the data.

FIG. 3 is a sectional view showing a specific structure of the electric steering apparatus 11.

In FIG. 3, a rack tube 17 in which a rack 12 is inserted is fixed to a vehicle body via a bracket. Side rods 13 and 14 are connected to both ends of the rack 12 via ball joints 30 and 31. The reduction mechanism 18 includes a motor pinion 32 connected to the motor shaft of the motor 19, a ring gear 33 meshing with the motor pinion 32, and a rack pinion 35 fixed to the ring gear 33 and meshing with the rack gear 12a. Have been. Therefore, when the motor shaft of the motor 19 rotates, the rotation is transmitted to the motor pinion 32 → the ring gear 33 → the rack pinion 35, and the rack shaft 12 moves in the axial direction due to the engagement between the rotating rack pinion 35 and the rack gear 12a. The rear wheels 9, 10 are steered. This rear wheel 9,10
Is proportional to the amount of movement of the rack shaft 12, that is, the amount of rotation of the motor shaft.

The rack pinion 35 is provided with a rear steering angle main sensor 24 having a potentiometer structure for detecting a rear wheel steering angle based on the rotation amount.

The fail-safe solenoid 20 includes:
The lock pin 20a is provided so as to be able to advance and retreat, and when the electronic control system or the like fails, the lock shaft 20a is fitted into a lock groove 12b formed in the rack shaft 12 so that the rack shaft 12 and the rear wheels 9, 10 can be moved. It is fixed at a position to maintain the neutral steering angle position.

The operation will be described.

[Rear Wheel Steering Angle Control Operation] FIG. 4 is a flowchart showing the flow of the rear wheel steering angle control operation performed by the controller 26. Each step will be described below.

In step 40, the vehicle speed V, the steering angle θ, the actual yaw rate ψ's, and the rear steering angle main sensor value δ
rs is read.

Here, the actual yaw rate ψ's is calculated based on the yaw rate sensor value Vψ 'from the yaw rate sensor 25 and the latest yaw rate zero correction memory value V obtained by the detected yaw rate correction processing for removing the influence of the temperature drift.
Calculated by ψ'om.

In step 41, the rear wheel steering angle feedforward target value δRFF is calculated by the following equation based on a phase inversion delay control method using the vehicle speed V and the steering angle θ.
^* (Hereinafter, * represents a target value) is calculated.

ΔRFF ^* = Kθ + τθ + τ′θ Step 42
Then, when a rear wheel steering angle feedforward target value δRFF ^* is given using an actuator model, a rear wheel steering angle estimated value δRFF ^# (hereinafter, #, which is the amount by which the rear wheel steering angle actuator actually steers the rear wheels) Represents an estimated value.) Is calculated.

Here, the actuator model is given by a transmission characteristic of an actual rear wheel steering angle obtained by driving an actual actuator with respect to a rear wheel steering angle command value.

In step 43, using the vehicle model, an estimated yaw rate value ψ '^# is calculated assuming that the vehicle is running with the vehicle speed V, the steering angle θ, and the estimated rear wheel angle value δRFF ^# .

Here, as the vehicle model, for example, a linear two-degree-of-freedom plane vehicle model is used.

In step 44, the estimated yaw rate ψ's ^# is calculated from the yaw rate estimated value ψ '^# using the yaw rate sensor model.

Here, the yaw rate sensor model is given by a transfer function based on an experimental result of a sensor dynamic characteristic such as a frequency response of the sensor.

Steps 42 to 44 correspond to the motion state amount estimating means c.

In step 45, the yaw rate deviation ψ'e is calculated from the difference between the actual yaw rate ψ's and the estimated yaw rate ψ's ^# (corresponding to the motion state quantity deviation calculating means e).

In step 46, the high-frequency noise included in the output of the yaw rate sensor 25 is removed by the feedback compensator-1 constituting a first-order lag filter.

The input signal of the feedback compensator-1 is ψ'e, and the output signal is ψ'ec1.

In step 47, the transient response of the vehicle to the disturbance is adjusted by the feedback compensator-2 constituting a first-order / first-order filter.

As will be described in detail later, the input signal of the feedback compensator-2 is ψ'ec1 and the vehicle speed V, and the output signal is ψ'ec2.

In step 48, the feedback rear wheel steering angle command value δRFBO ^{* is} obtained by the feedback proportional gain KP ^.
Is calculated.

The input signal of the proportional gain is ψ'ec2 and the vehicle speed V, and the output signal is δRFBO ^* .

[0042] At step 49, depending on the vehicle speed V, the following feedback was smoothly limits the maximum value of the feedback rear wheel steering angle command value DerutaRFBO ^* wheel steering angle limit command value DerutaRFBL ^* is calculated.

The input signals of the steering angle limiter are δRFBO ^* and the vehicle speed V, and the output signal is δRFBL ^* .

In step 50, a hysteresis is provided to the feedback rear wheel steering angle limit command value δRFBL ^* , and a feedback rear wheel steering angle hysteresis command value δRFBH ^* from which minute vibration due to feedback is removed is calculated.

The input signal at this small change absorber is δRFBL
^* And the rear wheel steering angle feedback target value ΔRFB ^* , and the output signal is ΔRFBH ^* .

In step 51, the transfer characteristic set in the actuator control system is changed to a desired transfer characteristic by the actuator phase compensator constituting the secondary / secondary filter, and the rear wheel steering angle feedback target value δRFB ^* Is calculated.

The input signal of this actuator phase compensator is δRFBH ^* , and the output signal is δRFB ^* .

Steps 46 to 51 correspond to auxiliary steering angle feedback target value calculating means f.

In step 52, a process for correcting the rear wheel steering angle feedback target value δRFB ^* in a direction to stop the feedback control when it is determined that the vehicle is in the counter running state is performed by the counter running corresponding logic shown in FIG. (Corresponding to the counter running corresponding target value correcting means i).

In step 53, the rear wheel steering angle feed forward target value δRFF ^* and the rear wheel steering angle feedback target value δ
Based on the sum with RFB ^* , a rear wheel steering angle target value ΔR ^* is calculated.

In step 54, a command (motor control current by PWM) for obtaining the rear wheel steering angle target value δR ^* is output using the rear steering angle main sensor value δrs and the robust model matching method (auxiliary steering angle control). Means k).

[Counter running corresponding logic] FIG. 5 is a flowchart showing the counter running corresponding logic executed by the controller 26. Each step will be described below.

In step 60, the steering angle θ,
Lateral acceleration estimated value Gψ ', lateral acceleration sensor value Gsen, yaw rate deviation ψ'e, counter running flag FLAG_CNT
Is read. Note that the estimated lateral acceleration Gψ ′ is the vehicle speed V
And the steering angle θ.

In step 61, it is determined whether or not the counter running determination flag FLAG_CNT is FLAG_CNT = 1 (1; determined, 0; released).

In step 62, the estimated lateral acceleration Gψ '
Is greater than or equal to the counter start determination threshold value Gψ′_CNTR (see FIG. 6).

In step 63, the estimated lateral acceleration Gψ '
The counter start determination threshold value ANGL_CNTR is read from the map (FIG. 7) in which is set as a parameter.

In step 64, it is determined whether the steering angle θ is equal to or greater than a counter start determination threshold value ANGL_CNTR.

In step 65, the estimated lateral acceleration Gψ '
From the map (FIG. 6) in which the difference between the acceleration and the lateral acceleration sensor value Gsen is used as a parameter (FIG. 6), the counter start judgment threshold ψ'e_CNTR_
ON is read.

In step 66, it is determined whether or not the yaw rate deviation ψ'e is equal to or greater than a counter start determination threshold value ψ'e_CNTR_ON.

In step 67, the counter start judgment time
CNTR_TIME_ON is counted up by one every control cycle.

At step 68, the counter start judgment time
It is determined whether CNTR_TIME_ON is equal to or longer than the set time tc.

In step 69, the flag FLAG_CNT is set to FLAG_CNT = 1.

The above steps 60 to 69 correspond to the counter running determining means h.

In step 70, the brake switch 28
It is determined whether the signal from is ON.

In step 71, the feedback steering angle increase / decrease coefficient FB_CUT is the feedback steering angle increase / decrease coefficient 5 ms before.
4 is subtracted from FB_CUT_1.

In step 72, the feedback steering angle increase / decrease coefficient FB_CUT is the feedback steering angle increase / decrease coefficient 5 ms before.
6 is added from FB_CUT_1.

In step 73, it is determined whether or not the feedback steering angle increase / decrease coefficient FB_CUT is equal to or greater than 255 (initial value).

In step 74, the feedback steering angle increase / decrease coefficient FB_CUT is set to the upper limit value of 255.

In step 75, it is determined whether the feedback steering angle increase / decrease coefficient FB_CUT is 0 or less.

In step 76, the feedback steering angle increase / decrease coefficient FB_CUT is set to 0, which is the lower limit.

In step 77, a rear wheel steering angle feedback target value δRFB ^* is calculated by the following equation.

ΔRFB ^* = δRFB ^* · (FB_CUT / 255) At step 78, the counter release judgment threshold value ψe′_C is obtained from the map (FIG. 8) using the estimated lateral acceleration value Gψ ′ as a parameter.
NTR_OFF is read.

In step 79, it is determined whether or not the yaw rate deviation ψ'e is equal to or smaller than a counter release determination threshold value ψe'_CNTR_OFF.

At step 80, the counter release judgment time
CNTR_TIME_OFF is incremented by 1 every control cycle.

In step 81, the counter release judgment time
It is determined whether CNTR_TIME_OFF is equal to or longer than the set time tco.

At step 82, the counter traveling judgment flag FLAG_CNT is set to FLAG_CNT = 0.

In step 83, the feedback steering angle increase / decrease coefficient FB_CUT is the feedback steering angle increase / decrease coefficient 5 ms before.
Two is added from FB_CUT_1.

[Rear Wheel Steering Angle Control Action] The rear wheel steering angle control action during traveling is executed according to the flowchart shown in FIG.

That is, in step 41, the vehicle speed V
The rear wheel steering angle feedforward target value ΔRFF ^* is calculated by an equation based on a phase inversion delay control method using the steering angle θ and the steering angle θ.

On the other hand, in steps 42 to 44, the estimated yaw rate に 's ^#
Is calculated in a step 45, and a yaw rate deviation ψ'e which is a difference between the actual yaw rate ψ's based on the yaw rate sensor value Vψ 'from the yaw rate sensor 25 and the estimated yaw rate ψ's ^# is calculated. In steps 46 to 51, the yaw rate deviation ψ'e is calculated. The rear wheel steering angle feedback target value ΔRFB ^* is calculated by compensation based on the deviation ψ′e.

When it is determined in step 52 that the vehicle is in the counter running state, the rear wheel steering angle feedback target value .delta ^.
Is corrected, and in step 53, the rear wheel steering angle target value δRFB ^* obtained in step 41 and the rear wheel steering angle feedback target value δRFB ^* obtained in step 52 are used to calculate the rear wheel steering angle target value. δR ^* is calculated, and a control command for obtaining the rear wheel steering angle target value δR ^* is output to the motor 19 of the electric steering device 11 in step 54.

[Feedback control action corresponding to counter running] The feedback control action corresponding to counter running performed in step 52 will be described.

* Counter running determination condition The counter running determination is based on the state of the hatched portion in FIGS.
In the direction to cancel the occurrence of the motion state quantity when continuing for c hours
It is determined that the vehicle is in the counter traveling state regardless of whether the steering wheel is operated .

That is, three conditions of (1) Gψ ′ ≧ Gψ′_CNTR (step 62), (2) θ ≧ ANGL_CNTR (step 64), and (3) 3′e ≧ ψ'e_CNTR_ON (step 66) are simultaneously satisfied. It is determined by whether or not.

In the condition (1), when the estimated lateral acceleration Gψ ′ estimated from the vehicle speed V and the steering angle θ is small, the possibility of the counter running is low, and the running in this region is excluded from the judgment. Even if there is no problem.

The condition (2) is, as in (1), because the possibility of counter running is low when the vehicle is running in a region where the steering angle θ is small. Here, the estimated lateral acceleration G
When ψ 'is large, the effect on the vehicle behavior is large even if the counter is driven by a small steering angle θ.
As shown in the map of FIG. 7, the value of the counter start determination threshold value ANGL_CNTR is set to decrease as Gψ ′ increases.

The condition (3) is the most characteristic yaw rate deviation condition during the counter running.
ON is not given as a fixed value, but the estimated lateral acceleration G
According to FIG. 6, which is a map in which the difference between ψ ′ and the lateral acceleration sensor value Gsen is used as a parameter, the value of ψ′e_CNTR_ON is given by a variable value that decreases as the lateral acceleration deviation increases.

First, for example, when the vehicle is running on a low μ road, the tire gripping force on the road surface becomes small, so that the lateral acceleration detected from the lateral acceleration estimated value Gψ ′ estimated from the vehicle speed V and the steering angle θ is obtained. As the acceleration sensor value Gsen decreases, the lateral acceleration deviation increases as the road surface friction coefficient decreases. Therefore, by detecting that the road friction coefficient is lower μ as the lateral acceleration deviation is larger, the lateral acceleration deviation can be used as indirect road friction coefficient information (corresponding to road friction coefficient equivalent value detecting means g). .

Second, as shown in FIG. 9, the relationship between the magnitude of the yaw rate deviation ψ'e, the road surface μ and the feedback control request is such that as the road surface becomes lower μ, the feedback control is desired even if the yaw rate deviation is smaller. There is no relationship.

Therefore, as shown in FIG. 10 in which the two-dimensional map shown in FIG. 6 is represented as a three-dimensional map, the value of ψ'e_CNTR_ON decreases as the lateral acceleration deviation increases and the road surface μ decreases. I did it.

As a result, when traveling on a low μ road, the value of ψ'e_CNTR_ON used for counter traveling determination is set to a small value, so that when the vehicle runs on a low μ road with a counter applied, the vehicle is immediately in a counter traveling state. Is determined, and the rear wheel steering angle feedback target value ΔRFB ^* is corrected in the direction in which the feedback control is stopped.

Also, when traveling on a high μ road, the value of ψ'e_CNTR_ON used for determining the counter traveling is set to a large value, so that when the yaw rate deviation ψ'e becomes large due to the influence of disturbance on the high μ road, the counter value is increased. Normal feedback control is performed without erroneous determination that the vehicle is in the running state, and disturbance stability is ensured by yaw rate feedback control.

* Operation after Start of Counter Control When the counter traveling is determined, the rear wheel steering angle feedback target value δRFB ^* is changed according to the state of the brake switch 28.

That is, when the brake is released, in step 71, the feedback steering angle increase / decrease coefficient FB_CUT is set to 5
The feedback steering angle increase / decrease coefficient FB_CUT_1 is subtracted by 4 from the feedback steering angle increase / decrease coefficient FB_CUT_1 before ms, and the rear wheel steering angle is gradually controlled so as to stop the feedback control.
Six is added from the feedback steering angle increase / decrease coefficient FB_CUT_1 ms before, and the rear wheel steering angle is controlled in a direction to maintain the feedback control or return to the feedback control. In this way, by controlling the rear wheel steering angle in the direction in which the feedback control is stopped at the time of the brake operation, it is possible to prevent the sudden change in the vehicle behavior from increasing.

* Counter running cancellation condition The counter running cancellation judgment is made by the state of the hatched portion in FIG.
When the time has continued, it is determined that the vehicle is in the counter running release state.

That is, in step 79, it is determined under the condition that the yaw rate deviation ψ'e is equal to or smaller than the counter release determination threshold value ψe'_CNTR_OFF.

This counter release judgment threshold value ψe'_CNTR_
OFF is set in a relation substantially opposite to the relation shown in FIG. Note that this release condition is only a yaw rate deviation condition,
The cancellation of the counter running is determined as early as possible.

* Operation after canceling counter control After canceling the counter control, the rear wheel steering angle feedback target value δRFB ^* is gradually returned to return to the feedback control.

That is, in step 83, the feedback steering angle increase / decrease coefficient FB_CUT is added by 2 from the feedback steering angle increase / decrease coefficient FB_CUT_1 5 ms before, and the feedback steering angle increase / decrease coefficient FB_CUT is set to 1 (= 255/255. It is added for each control cycle until it becomes complete recovery).

This prevents a sudden change in vehicle behavior due to a sudden return from the feedback control suspended state to the feedback control.

Next, the effects will be described.

(1) In a vehicular auxiliary steering angle control device that provides a rear wheel steering angle by feedforward control and yaw rate feedback control, the lateral acceleration deviation between the estimated lateral acceleration value Gψ ′ and the lateral acceleration sensor value Gsen is large, and μ
Is smaller, the value of ψ'e_CNTR_ON is set to a smaller value, and the steering angle θ is set to the counter start determination threshold value AN.
When the yaw rate deviation ψ'e is equal to or greater than GL_CNTR and the counter start determination threshold value 以上 'e_CNTR_ON is greater than or equal to カ ウ ン タ e_CNTR_ON, a counter that performs control for gradually correcting the rear wheel steering angle feedback target value δRFB ^* in a direction to stop feedback control. Since the device is provided with the traveling correspondence logic, it is possible to achieve both the avoidance of discomfort given to the driver during the counter traveling and the securing of disturbance stability during the traveling on the high μ road.

(2) In detecting the road surface μ, the detection is performed based on the magnitude of the lateral acceleration deviation between the lateral acceleration estimated value Gψ ′ and the lateral acceleration sensor value Gsen. The road surface friction coefficient can be detected well.

(3) The apparatus performs a control for correcting the rear wheel steering angle feedback target value δRFB ^* in a direction to maintain or return the feedback control at the time of counter running judgment and brake operation. This is because during a counter running including a brake operation, it is determined that the driver wants to decelerate the vehicle, that is, the stability of the vehicle. Nature can be secured.

(4) Since the control for gradually returning the rear wheel steering angle feedback target value δRFB ^* when returning to the counter running mode is performed, it is possible to prevent a sudden change in vehicle behavior such as when returning to sudden feedback control. Can be.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to the embodiment, and even if there are changes and additions without departing from the gist of the invention, the invention is included in the invention. It is.

For example, in the embodiment, the example of the auxiliary steering angle control device for giving the auxiliary steering angle only to the rear wheel is shown. However, the auxiliary steering angle control device for giving the auxiliary steering angle only to the front wheel or the front and rear wheels is also used. Can be applied.

In the embodiment, the example in which the yaw rate is used as the motion state amount has been described. However, the lateral speed, the lateral acceleration, or the yaw momentum expressing these in a complex manner may be used.

In the embodiment, the example in which the electric steering device is used as the auxiliary steering angle actuator has been described. However, the present invention can be applied to a hydraulic or pneumatic steering device.

In this embodiment, a preferred example of detecting the road surface μ by detecting the magnitude of the lateral acceleration deviation between the estimated lateral acceleration value Gψ ′ and the lateral acceleration sensor value Gsen has been described. It may be performed by a method or by directly detecting the road surface condition.

[0111]

As described above, according to the present invention, in a vehicle auxiliary steering angle control device for providing an auxiliary steering angle by yaw rate feedback control or the like, a road surface friction coefficient equivalent value for detecting a road surface friction coefficient equivalent value. The detection means, the threshold value of the motion state quantity deviation is set to a larger value as the road surface friction coefficient equivalent value is larger, the steering angle is more than a predetermined value,
When the calculated motion state quantity deviation is equal to or larger than the motion state quantity deviation threshold value, the movement in the direction of canceling the motion state quantity is canceled.
A counter running determining means for determining that the vehicle is in the counter running state irrespective of whether the dollar is being operated or not , and a counter running corresponding target for correcting the auxiliary steering angle feedback target value in a direction to stop the feedback control when the counter running is determined. The device is provided with a value correcting means, so that the behavior of the vehicle during counter running can be prevented from being uncomfortable to the driver, and a high μ
An effect is obtained that it is possible to achieve compatibility with disturbance stability during road running.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to a claim showing an auxiliary steering angle control device for a vehicle according to the present invention.

FIG. 2 is an overall system diagram showing a four-wheel steering vehicle to which the vehicle auxiliary steering angle control device of the embodiment is applied.

FIG. 3 is a cross-sectional view of the electric steering device of the embodiment device.

FIG. 4 is a flowchart illustrating a flow of a rear wheel steering angle control operation performed by a controller of the embodiment device.

FIG. 5 is a flowchart illustrating a counter running correspondence logic executed by a controller of the embodiment device.

FIG. 6 is a yaw rate deviation map used to determine the start of counter running control.

FIG. 7 is a map of a steering angle used for determining the start of counter running control.

FIG. 8 is a yaw rate deviation map used for determination of cancellation of counter running control.

FIG. 9 is a diagram showing a counter running control image in the present embodiment on a plane based on a yaw rate deviation and a road surface μ.

FIG. 10 is a diagram in which a threshold value changed by a lateral acceleration deviation in the map of FIG. 6 is represented by three-dimensional characteristics.

[Explanation of symbols]

 a vehicle speed detecting means b steering rudder angle detecting means c moving state quantity estimating means d moving state quantity detecting means e moving state quantity deviation calculating means f auxiliary steering angle feedback target value calculating means g road surface friction coefficient equivalent value detecting means h counter running judgment Means i Counter-running target value correction means j Auxiliary steering angle actuator k Auxiliary steering angle control means

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI B62D 137: 00 (58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 6/00 B62D 7/14

Claims (2)

(57) [Claims] 1. A vehicle speed detecting means, a steering steering angle detecting means, a moving state amount estimating means for estimating a moving state amount generated in the own vehicle based on the vehicle speed detected value and the steering steering angle detected value, Exercise state quantity detection means for detecting the same kind of state quantity as exercise state quantity; Exercise state quantity deviation calculation means for calculating a deviation between the exercise state quantity detection value and the exercise state quantity estimation value; Compensation based on the exercise state quantity deviation An auxiliary steering angle feedback target value calculating means for calculating an auxiliary steering angle feedback target value, a road surface friction coefficient equivalent value detecting means for detecting a road surface friction coefficient equivalent value, and a motion state quantity deviation as the road surface friction coefficient equivalent value increases. set the threshold to a larger value, in the steering angle is greater than a predetermined value, and, when the calculated motion state quantity deviation is more than the motion state quantity deviation threshold value, beat generation of motion state quantity To be direction
A counter running determining means for determining that the vehicle is in a counter running state irrespective of whether or not the steering wheel is operated; and a counter running corresponding target for correcting the auxiliary steering angle feedback target value in a direction in which the feedback control is stopped when the counter running is determined. Value correction means, and auxiliary steering angle control means for outputting to the auxiliary steering angle actuator a control command for obtaining an auxiliary steering angle feedback target value that is not corrected or a corrected auxiliary steering angle feedback target value. An auxiliary steering angle control device for a vehicle, comprising: 2. The vehicle auxiliary steering angle control device according to claim 1, wherein the road surface friction coefficient equivalent value detecting means includes an estimated lateral acceleration based on a yaw rate detection value from a yaw rate sensor and an actual lateral acceleration from a lateral acceleration sensor. And the lateral acceleration deviation, the larger the lateral acceleration deviation, the lower the road surface friction coefficient.
A vehicle auxiliary steering angle control device, characterized in that it is means for detecting that