JPH07186989A - Auxiliary steering angle controller for vehicle - Google Patents

Abstract

PURPOSE:To reconcile the prevention of a feeling of incompatibility on car behavior to a driver in time of counter traveling and the secureness of stability to disturbance in time of traveling on a high u road, in this car auxiliary steering angle controller which imparts an auxiliary steering angle by means of yaw rate feedback control or the like. CONSTITUTION:This controller is provided with a road surface friction factor equivalent value detecting means (g) detecting an amount of road surface friction factor equivalent value, a counter travel judging means (h) setting the larger in moving state value deviation threshold value, the larger in road surface friction factor equivalent value, and when a steering angle is more than the specified value as well as when a moving state value deviation is more than the moving state value deviation threshold, judging it as a counter travel state, and a counter travel corresponding desired value correcting means (i) correcting the auxiliary steering angle feedback desired value in a direction, where feedback control is suspended, in time of a counter travel judgement, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle auxiliary rudder angle control device for providing an auxiliary rudder 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 which gives an auxiliary steering angle to a rear wheel by feedforward control + yaw rate feedback control, for example, Japanese Patent Application Laid-Open No. HEI 2-
The device described in Japanese Patent No. 18168 is known.

This conventional source has a reference model which is a desired yaw rate response model, determines a yaw rate target value by using a vehicle speed, a steering angle and a reference model, and obtains the yaw rate target value by interposing a delay element. There is disclosed a technique in which the feedback system operates only when absorbing a disturbance or a parameter variation by setting the calculated value as a yaw rate estimated value used in the yaw rate feedback system.

[0004]

However, in the above-described conventional vehicle auxiliary steering angle control device, the yaw rate feedback control is performed using the yaw rate deviation which is the difference between the standard yaw rate and the vehicle yaw rate, but low μ When the driver gives a correction rudder when the vehicle slips on a road, or when the driver performs drift traveling of the vehicle, the counter applies a running state, that is, by turning the steering wheel in the direction opposite to the turning direction of the vehicle. In the running state, the driver tries to control the vehicle behavior by operating the steering wheel intended by himself, but in the feedback system, the reference yaw rate required by the vehicle speed and the steering rudder angle is largely deviated, and as a result, the rear wheel rudder angle is also obtained. The driver will feel a sense of discomfort because the vehicle is steered with respect to the desired vehicle behavior.

Therefore, the yaw rate deviation is greatly deviated,
When the yaw rate deviation threshold value is exceeded, it is judged that the vehicle is in the counter traveling state and the feedback control is stopped.

However, if the yaw rate deviation threshold value given as a fixed value is set to a large value in this control, the counter traveling judgment is delayed when traveling on a low μ road, the feedback control is not interrupted, and in the traveling where the counter is applied immediately. , The effect of stopping the control becomes low. On the other hand, if the yaw rate deviation threshold value is set to a small value, the counter running state is erroneously judged to be excessive when the vehicle runs on a high μ road, and the function of the yaw rate feedback control is reduced.

The present invention has been made in view of the above problems, and an object thereof is to provide a vehicle auxiliary steering angle control device for providing an auxiliary steering angle by yaw rate feedback control or the like. It is intended to secure both vehicle behavior stability during counter traveling and disturbance stability during traveling on a high μ road.

[0008]

In order to achieve the above object, according to the present invention as set forth in claim 1, as shown in the claim correspondence diagram of FIG. 1, a vehicle speed detecting means a, a steering steering angle detecting means b, and a vehicle speed detecting means. A motion state quantity estimating means c for estimating the motion state quantity occurring in the vehicle based on the detected value and the steering steering angle detection value, and a motion state quantity detecting means d for detecting the motion state quantity of the same kind as the estimated motion state quantity. A motion state quantity deviation calculating means e for calculating a deviation between the motion state quantity detection value and the motion state quantity estimated 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. The value calculation means f, the road surface friction coefficient equivalent value detecting means g for detecting the road surface friction coefficient equivalent value, and the larger the movement surface quantity deviation threshold value, the larger the road surface friction coefficient equivalent value is set, and the steering Corners above a predetermined value, and, when the calculated motion state quantity deviation is more than the motion state quantity deviation threshold value,
Counter traveling determination means h for determining that the vehicle is in the counter traveling state, counter traveling corresponding target value correction means i for correcting the auxiliary steering angle feedback target value in the direction in which feedback control is stopped when the counter traveling is determined, and no correction. The auxiliary steering angle control means k is provided for outputting a control command for obtaining the auxiliary steering angle feedback target value or the corrected auxiliary steering angle feedback target value to the auxiliary steering angle actuator j.

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

[0010]

When the vehicle is running, the motion state quantity estimating means c
Based on the vehicle speed detection value from the vehicle speed detection means a and the steering rudder angle detection value from the steering rudder angle detection means b, the motion state quantity occurring in the vehicle is estimated, and the motion state quantity detection means d
In, the motion state quantity of the same kind as the estimated motion state quantity is detected, and the motion state quantity deviation calculating means e calculates the deviation between the motion state quantity detection value and the motion state quantity estimated value, and the auxiliary steering angle feedback target In the value calculating means f, the auxiliary steering angle feedback target value is calculated by compensation based on the motion state quantity deviation.

On the other hand, in the counter traveling judgment means h,
The larger the road surface friction coefficient equivalent value from the road surface friction coefficient equivalent value detecting means g is, the larger the motion state quantity deviation threshold value is set, the steering angle is a predetermined value or more, and the calculated motion state quantity deviation. Is greater than or equal to the motion state quantity deviation threshold value, it is determined that the vehicle is in the counter traveling state, and the counter traveling-corresponding target value correcting means i determines that the counter traveling is
The auxiliary steering angle feedback target value is corrected in the direction in which the feedback control is stopped.

Then, the auxiliary steering angle control means k outputs a control command for obtaining an uncorrected auxiliary steering angle feedback target value or a corrected auxiliary steering angle feedback target value to the auxiliary steering angle actuator j.

Therefore, when the vehicle is traveling on the low μ road, the motion state quantity deviation threshold value used for the counter traveling determination is set to a small value so that the counter traveling state is immediately obtained when the vehicle travels with the counter on the low μ road. 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, and the driver's uncomfortable feeling is prevented by the feedback control of the vehicle behavior. When traveling on a high μ road, the motion state quantity deviation threshold value used for counter traveling judgment is set to a large value, so that the counter running state can be maintained even when a large movement state quantity deviation appears on a high μ road under the influence of disturbance. The normal feedback control is executed without being erroneously determined to be, and the 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, steering of the front wheels 1 and 2 is performed by a steering handle 3 and a mechanical link type steering mechanism 4.
Done by. This is composed of, for example, a steering gear, a pitman arm, a relay rod, side rods 5, 6 and knuckle arms 7, 8.

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

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

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

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

The fail-safe solenoid 20 includes:
The lock pin 20a is provided so as to be movable back and forth, and when the electronic control system or the like fails, the lock pin 20a is fitted into the lock groove 12b formed in the rack shaft 12 so that the rack shaft 12 is moved to the rear wheels 9 and 10. It is fixed at a position that maintains the neutral rudder 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, and each step will be described below.

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

Here, the actual yaw rate ψ's is 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 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 the phase inversion delay control method using the vehicle speed V and the steering steering angle θ.
^* (Hereinafter, * represents a target value.) Is calculated.

ΔRFF ^* = Kθ + τθ + τ'θ Step 42
Then, when the rear wheel steering angle feedforward target value δRFF ^* is given using the actuator model, the rear wheel steering angle estimated value δRFF ^# (hereinafter, # Represents an estimated value).

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

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

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

The steps 42 to 44 correspond to the motion state quantity 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).

At step 46, the high frequency noise contained in the output of the yaw rate sensor 25 is removed by the feedback compensator-1 which constitutes a first-order lag filter.

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

In step 47, the feedback compensator-2 forming the first-order / first-order filter adjusts the transient response of the vehicle to the disturbance.

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

In step 48, the feedback proportional gain KP is used to feed back the rear wheel steering angle command value δRFBO ^*.
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 this steering angle limiter are δRFBO ^* and the vehicle speed V, and the output signals are δRFBL ^* .

In step 50, the feedback rear wheel steering angle hist command value δRFBH ^* is calculated by providing a hysteresis to the feedback rear wheel steering angle limit command value δRFBL ^* and removing a slight vibration due to the feedback.

The input signal of 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 second / second order filter, and the rear wheel steering angle feedback target value δRFB is set. ^* Is calculated.

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

The steps 46 to 51 correspond to the auxiliary steering angle feedback target value calculation means f.

In step 52, the counter traveling correspondence logic shown in FIG. 5 corrects the rear wheel steering angle feedback target value δRFB ^* in the direction in which the feedback control is stopped when the counter traveling state is determined. (Corresponding to target value correction means i corresponding to counter traveling).

In step 53, the rear wheel steering angle feedforward target value δRFF ^* and the rear wheel steering angle feedback target value δ
The rear wheel steering angle target value ΔR ^* is calculated by the sum with RFB ^* .

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). Equivalent to means k).

[Counter Travel Correspondence Logic] FIG. 5 is a flowchart showing the counter travel support logic executed by the controller 26, and each step will be described below.

In step 60, the steering 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. The estimated lateral acceleration value Gψ ′ is the vehicle speed V
And the steering steering angle θ.

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

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

In step 63, the lateral acceleration estimated value Gψ '
The counter start judgment threshold value ANGL_CNTR is read from the map (Fig. 7) using as a parameter.

In step 64, it is determined whether or not the steering angle θ is equal to or greater than the counter start determination threshold value ANGL_CNTR.

In step 65, the lateral acceleration estimated value Gψ '
The counter start judgment threshold value ψ'e_CNTR_ from the map (Fig. 6) that uses the difference between the horizontal acceleration sensor value Gsen and the lateral acceleration sensor value as a parameter.
ON is read.

In step 66, it is determined whether the yaw rate deviation ψ'e is equal to or greater than the counter start judgment threshold value ψ'e_CNTR_ON.

In step 67, the counter start judgment time
CNTR_TIME_ON is incremented by 1 every control cycle.

In 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 counter running determination flag FLAG_CNT is set to FLAG_CNT = 1.

The above steps 60 to 69 correspond to the counter running determination 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 5 ms before the feedback steering angle increase / decrease coefficient.
4 is subtracted from FB_CUT_1.

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

At step 73, it is judged if 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 255, which is the upper limit value.

At step 75, it is judged if 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 value.

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

.Delta.RFB ^* =. Delta.RFB ^* .multidot ^. (FB_CUT / 255) At step 78, the counter cancellation judgment threshold value .phi.e'_C is determined from the map (FIG. 8) using the lateral acceleration estimated value G.psi. 'As a parameter.
NTR_OFF is read.

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

In 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 running determination flag FLAG_CNT is set to FLAG_CNT = 0.

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

[Rear Wheel Steering Angle Control Operation] The rear wheel steering angle control operation 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 the phase inversion delay control method using the steering angle θ and the steering angle θ.

[0080] On the other hand, in step 42 to step 44, the estimated yaw rate [psi's ^# occurring on the vehicle with the model
Is calculated, and in step 45, the yaw rate deviation ψ′e, which is the 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, and 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 traveling state, the rear wheel steering angle feedback target value δRFB ^{* is} set in the direction in which the feedback control is stopped ^.
Is corrected, and in step 53, the rear wheel steering angle target value is calculated by the sum of the rear wheel steering angle feedforward target value δRFF ^* obtained in step 41 and the rear wheel steering angle feedback target value δRFB ^* obtained in step 52. δR ^* is calculated, and in step 54, a control command for obtaining the rear wheel steering angle target value δR ^* is output to the motor 19 of the electric steering apparatus 11.

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

* Counter traveling judgment condition The counter traveling judgment is judged to be the counter traveling state when the state of the shaded portion in FIGS. 6 and 7 continues for tc time.

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

The condition (1) above is unlikely to be counter traveling when the lateral acceleration estimated value Gψ 'estimated by the vehicle speed V and the steering angle θ is small, and traveling in this region is excluded from the judgment. It depends on that there is no problem.

The condition (2) above is because the possibility of counter traveling is low when traveling in a region where the steering angle θ is small, as in (1). However, the lateral acceleration estimated value G
When running with a large ψ ', counter running with a small steering angle θ has a large effect on vehicle behavior.
As shown in the map of FIG. 7, the value of the counter start determination threshold value ANGL_CNTR is set to be smaller as Gψ ′ is larger.

The condition (3) above is the most characteristic yaw rate deviation condition during counter traveling, but this ψ'e_CNTR_
ON is not given as a fixed value, but estimated lateral acceleration value G
According to FIG. 6, which is a map using the difference between ψ ′ and the lateral acceleration sensor value Gsen as a parameter, the value of ψ′e_CNTR_ON becomes smaller as the lateral acceleration deviation increases.

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

Secondly, regarding the relationship between the magnitude of the yaw rate deviation ψ'e, the road surface μ and the feedback control requirement, as shown in FIG. 9, the lower the road surface μ, the more the feedback control is desired even if the yaw rate deviation is small. There is no relationship.

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

As a result, when traveling on a low μ road, the value of ψ′e_CNTR_ON used for the counter traveling judgment is set to a small value, so that the counter traveling state is immediately obtained when the vehicle travels with the counter on the low μ road. Therefore, the rear wheel steering angle feedback target value ΔRFB ^* is corrected in the direction in which the feedback control is stopped.

Further, when traveling on a high μ road, the value of ψ'e_CNTR_ON used for the counter traveling judgment is set to a large value so that the counter can be used even when the yaw rate deviation ψ'e appears on a high μ road due to the influence of disturbance. Normal feedback control is executed without misjudging that the vehicle is running, and the stability of the disturbance is ensured by the yaw rate feedback control.

* Operation after Counter Control Starts When the counter running is judged, the rear wheel steering angle feedback target value δRFB ^* is changed depending on the state of the brake switch 28.

That is, when the brake is released, the feedback steering angle increase / decrease coefficient FB_CUT is 5 in step 71.
4 is subtracted from the feedback steering angle increase / decrease coefficient FB_CUT_1 before ms, and the rear wheel steering angle is gradually controlled to stop the feedback control. However, at the time of braking, the feedback steering angle increase / decrease coefficient FB_CUT is 5 in step 72.
6 is added from the feedback steering angle increase / decrease coefficient FB_CUT_1 before ms, and the rear wheel steering angle is controlled in the direction of maintaining the feedback control or returning to the feedback control. With this, by controlling the rear wheel steering angle in the direction in which the feedback control is stopped at the time of braking, it is possible to prevent the sudden change of the vehicle behavior from becoming large.

* Counter running cancellation condition The judgment of counter running cancellation is made when the state of the shaded portion in FIG. 8 is tco.
When the time has continued, it is determined that the counter running state is cancelled.

That is, in step 79, the yaw rate deviation ψ'e is judged under the condition that the counter cancellation judgment threshold ψe'_CNTR_OFF is equal to or less than the threshold.

This counter cancellation judgment threshold value ψe'_CNTR_
OFF is set in a relationship almost opposite to the relationship shown in FIG. This release condition is only the yaw rate deviation condition,
The decision is made to cancel the counter running as soon as possible.

* Operation after the counter control is released After the counter control is released, 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 rudder angle increase / decrease coefficient FB_CUT is added by 2 from the feedback rudder angle increase / decrease coefficient FB_CUT_1 5 ms before, and the feedback rudder angle increase / decrease coefficient FB_CUT is set to 1 (= 255/255 to perform feedback control). It is added every control cycle until it is completely restored.

As a result, a sudden change in the vehicle behavior caused by the rapid return to the feedback control from the feedback control stopped state is prevented.

Next, the effect will be described.

(1) In an auxiliary steering angle control device for a vehicle which gives a rear wheel steering angle by feedforward control + yaw rate feedback control, a lateral acceleration deviation between a lateral acceleration estimated value Gψ ′ and a lateral acceleration sensor value Gsen is large and a road surface μ
The lower μ is, the smaller the value of ψ'e_CNTR_ON is set, and the steering angle θ becomes the counter start judgment threshold AN.
A counter for gradually correcting the rear wheel steering angle feedback target value δRFB ^* in the direction to stop the feedback control when the yaw rate deviation ψ'e is equal to or more than the GL_CNTR and the yaw rate deviation ψ'e is equal to or more than the counter start determination threshold ψ'e_CNTR_ON. Since the device is provided with the logic for traveling, it is possible to avoid the discomfort given to the driver during traveling on the counter and to secure the disturbance stability during traveling on the high μ road.

(2) When detecting the road surface μ, since the device for detecting is based on the magnitude of the lateral acceleration deviation between the lateral acceleration estimated value Gψ ′ and the lateral acceleration sensor value Gsen, it is possible to easily and accurately use a vehicle-mounted sensor. The road friction coefficient can be detected well.

(3) When the counter traveling is judged and the brake is operated, the device for performing the control for correcting the rear wheel steering angle feedback target value δRFB ^* in the direction in which the feedback control is maintained or returned. This is because the driver is determined to want to decelerate the vehicle, that is, the stability of the vehicle during counter traveling including brake operation. Therefore, the feedback control is performed regardless of the counter traveling to stabilize the vehicle. It is possible to secure the sex.

(4) Since the device for performing the control for gradually returning the rear wheel steering angle feedback target value δRFB ^* when the counter traveling is cancelled, it is necessary to prevent a sudden change in the vehicle behavior such as when returning to the sudden feedback control. You can

Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

For example, in the embodiment, the example of the auxiliary steering angle control device which gives the auxiliary steering angle only to the rear wheels is shown, but the auxiliary steering angle control device which gives the auxiliary steering angle only to the front wheels 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 quantity has been shown, but the lateral velocity, the lateral acceleration, or the yaw momentum which represents these in combination may be used.

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

In the embodiment, when detecting the road surface μ, a preferable example in which the lateral acceleration difference between the estimated lateral acceleration value Gψ ′ and the lateral acceleration sensor value Gsen is detected is shown, but other indirect detection is possible. 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 the vehicle auxiliary steering angle control device for providing the auxiliary steering angle by the yaw rate feedback control or the like, the road surface friction coefficient equivalent value for detecting the road surface friction coefficient equivalent value is detected. As the detection means and the road surface friction coefficient equivalent value are larger, the motion state quantity deviation threshold value is set to a larger value, and the steering angle is equal to or larger than a predetermined value.
In addition, when the calculated motion state quantity deviation is equal to or more than the motion state quantity deviation threshold value, the counter traveling determination means for determining that the vehicle is in the counter traveling state, and the auxiliary steering angle in the direction of stopping the feedback control when the counter traveling is determined. Since the device is equipped with a counter value corresponding to the target value for correcting the feedback target value, it is possible to prevent the driver from feeling uncomfortable when the vehicle is running on the counter and to ensure the stability of the disturbance when driving on a high μ road. The effect that can be achieved is obtained.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing an auxiliary steering angle control device for a vehicle of 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 an electric steering device of the embodiment device.

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

FIG. 5 is a flow chart showing a counter-running corresponding logic executed by the controller of the embodiment apparatus.

FIG. 6 is a yaw rate deviation map diagram used for determining the start of counter running control.

FIG. 7 is a steering steering angle map diagram used for determining whether to start counter traveling control.

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

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

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

[Explanation of symbols]

 a vehicle speed detection means b steering rudder angle detection means c motion state quantity estimation means d motion state quantity detection means e motion state quantity deviation calculation means f auxiliary steering angle feedback target value calculation means g road surface friction coefficient equivalent value detection means h counter traveling judgment Means i Counter-travel target value correction means j Auxiliary steering angle actuator k Auxiliary steering angle control means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B62D 137: 00

Claims (2)

[Claims] 1. A vehicle speed detecting means, a steering rudder angle detecting means, a motion state quantity estimating means for estimating a motion state quantity occurring in a vehicle based on the vehicle speed detection value and the steering rudder angle detection value, and the estimated motion. Motion state quantity detection means for detecting the same kind of motion state quantity as the state quantity; motion state quantity deviation calculation means for calculating the deviation between the motion state quantity detection value and the motion state quantity estimated value; and compensation based on the motion state quantity deviation The auxiliary rudder angle feedback target value calculation means for calculating the auxiliary rudder angle feedback target value by means, the road surface friction coefficient equivalent value detection means for detecting the road surface friction coefficient equivalent value, and the larger the road surface friction coefficient equivalent value, the greater the deviation of the motion state amount. When the threshold value is set to a large value, the steering angle is equal to or greater than a predetermined value, and the calculated motion state quantity deviation is equal to or larger than the motion state quantity deviation threshold value, the counter is in a traveling state. Counter traveling judgment means for judging, counter traveling corresponding target value correcting means for correcting the auxiliary steering angle feedback target value in the direction to stop the feedback control at the time of counter traveling judgment, and auxiliary steering angle feedback target value not corrected An auxiliary rudder angle control device for a vehicle, comprising: an auxiliary rudder angle control means that outputs a control command for obtaining the above-mentioned auxiliary rudder angle feedback target value to an auxiliary rudder angle actuator. 2. The vehicle auxiliary rudder 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. The lateral friction coefficient is lower than the lateral friction coefficient.
An auxiliary steering angle control device for a vehicle, characterized in that it is a means for detecting that