JP2970408B2 - Wheel 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 four-wheel steering vehicle that steers wheels according to a steering angle, a vehicle speed, a yaw rate of a vehicle, and a rear wheel steering angle in a vehicle such as an automobile.

[0002]

2. Description of the Related Art Conventionally, various four-wheel steering systems have been proposed for improving the steering stability during running of a vehicle. For example, as disclosed in Japanese Patent Application Laid-Open No. 3-164374, a steering wheel angle sensor detects a steering wheel angle, and a yaw rate sensor detects an actual yaw rate (rotational angular velocity around the center of weight of the vehicle as viewed from above the vehicle body), and The steering speed in the yaw rate suppression direction is multiplied with the steering speed in the yaw rate suppression direction, and the steering control amount in the yaw rate suppression direction is changed according to the steering speed. Can be reduced, and the initial turning performance at the time of sudden steering of the front wheels can be improved.

In Japanese Patent Application Laid-Open No. 60-124572, a target yaw rate is calculated from a steering wheel angle and a vehicle speed.
A yaw rate follow-up control method for steering the rear wheels so that the actual yaw rate follows the target yaw rate has also been proposed.

[0004] In either case, the yaw rate feedback has the effect that even if the course or direction of the vehicle is deviated due to disturbance factors such as crosswinds or bad roads, this can be corrected by rear wheel steering.

[0005]

However, a circuit (bank) and a straight road (Kant) in which the road surface is inclined.
In this case, a phenomenon different from that on a flat road occurs because the gravity term affects the vehicle motion characteristics as a steady disturbance.

More specifically, in bank running, if the vehicle speed is constant, the generated yaw rate is the same regardless of the steering angle.

[0007] In cant running, the steering wheel must be turned to go straight.

In the above dynamic characteristics, a target value for setting the vehicle body slip angle to zero on a flat road from a vehicle speed, a steering wheel angle, and the like is determined, and control is performed by a target yaw rate tracking method for following the target value. A phenomenon (fluctuation) occurs.

In bank running, the target yaw rate value obtained from the steering wheel angle or the like is different from the yaw rate value for stable running during bank running.

[0010] However, since control is performed so that the actual yaw rate follows the target yaw rate, the yaw rate value does not match the bank, and the driver must perform corrective steering.

In cant running, when the steering wheel is turned, the target yaw rate is generated in the direction in which the steering wheel is turned off, and the rear wheels are steered to follow the actual yaw rate.

However, in the cant, since the vehicle travels straight with the steering wheel turned, this rear wheel steering is a steering that hinders the straight traveling, and the driver needs to correct the steering wheel.

Further, if there is a drift in the sensor output, a deviation corresponding to the drift occurs. For example, even when the vehicle is traveling straight, it is erroneously recognized that a yaw rate is occurring, and the rear wheels are steered.

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a vehicle speed sensor for detecting the speed of a vehicle, a steering wheel angle sensor for detecting a turning angle of a steering wheel, and a target vehicle based on the vehicle speed and the steering wheel angle. Target value setting means for setting a target value of the vehicle state quantity as a dynamic characteristic, state quantity detection means for detecting a vehicle state quantity to be followed as a target, and a value detected by the state quantity detection means, Target steering angle calculating means for calculating a steering angle command signal for at least one of a front wheel and a rear wheel so as to follow the target value; and wheel steering means for steering a front wheel or a rear wheel based on the steering angle command signal. In the vehicle wheel steering control device, from the output of each of the sensors and the vehicle model, in a normal state, disturbance traveling determination means for determining whether the disturbance is applied disturbance added state, In accordance with a running state determined by Kigairan travel determining means, a wheel steering angle control apparatus characterized by having a target value changing means for changing the target value.

Further, disturbance running determination means for determining whether the current running state is a normal state or a disturbance-applied state based on the output values of the sensors, the condition values, and the vehicle model. A wheel steering angle control device comprising: target value changing means for changing the target value in accordance with the traveling state determined by the disturbance traveling determination means.

A reference state quantity calculating means for calculating from a vehicle model a vehicle state quantity Yh generated during normal running without disturbance from the outputs and condition values of the sensors, and a reference state quantity Yh and a detected vehicle state quantity A state quantity estimating means for estimating a vehicle state quantity Yg generated by steady disturbance using Y and a target value correcting means for correcting the target value using the estimated vehicle state quantity Yg. Is a wheel steering angle control device.

Further, the change rate of the detected vehicle state quantity Y and the calculated change rate of the vehicle state quantity Yh are calculated by the state quantity change rate determining means.
It is determined whether the vehicle is in a steady disturbance application state or a sudden disturbance application state. In the sudden disturbance application state, the vehicle state quantity Yg estimated by the state quantity estimating means is the current Y and Yh. A wheel steering angle control device characterized in that it is not updated when used.

In the estimated value change rate determining means, a change rate of the vehicle state quantity Yg estimated by the state quantity estimating means is obtained and compared with a certain set value.
The wheel steering angle control device is characterized in that the target value is not corrected by the target value correcting means using this Yg.

The detection error determining means compares the vehicle state quantity Yg estimated by the state quantity estimating means with a certain set value. If the set value is equal to or more than the set value, it is determined that the state quantity detecting means has failed. And a wheel steering angle control device for stopping the state quantity tracking control.

The running condition detected by the condition value detecting means is a road surface friction coefficient, and the disturbance running determining means calculates a vehicle speed, a steering wheel angle, a rear wheel steering angle, and a road surface friction coefficient. The state quantity of the vehicle is calculated from the vehicle model ignoring the gravity term and compared with the detection value detected by the state quantity detection means. And a rear wheel steering angle control device.

The steady state determining means determines whether the vehicle is in a steady straight running state or a steady turning state. Only when it is determined that the vehicle is in the steady state, the disturbance state determining means determines the target value of the vehicle state quantity. And a detected value of a vehicle state quantity, and when the deviation is equal to or more than a predetermined value, it is determined that a disturbance is applied.

When the vehicle movement determining means determines that the vehicle is out of the disturbance application state by the disturbance running determining means, it is determined whether the current vehicle movement is the vehicle movement to perform the target value tracking control, or A rear wheel steering angle control device characterized in that it is determined based on a steering angle command signal whether the vehicle motion is to perform wheel steering, and the wheel steering control is performed accordingly.

Further, the change speed determining means calculates the steering wheel change speed and the vehicle state quantity change speed, and when the values are equal to or greater than a certain set value, the target value determined by the target value change means is calculated as follows: A rear-wheel steering angle control device that performs a follow-up control by replacing the target value with a target value set by target value setting means.

In addition, the vehicle must be driven on a flat road where the influence of the gravitational term can be neglected from the traveling state quantity, or on a spiral circuit (bank) and a straight road (cant) having a sloping road surface in which the gravitational term affects the dynamic characteristics of the vehicle. A road surface inclination determining means for determining whether the vehicle is traveling on a slope, and a target value changing means for changing the target value according to the road surface state determined by the road surface inclination determining means. This is a rear-wheel steering angle control device for a wheel-steered vehicle.

In the road inclination determining means, the vehicle speed,
Using the respective steering state amounts of the steering wheel angle and the rear wheel steering angle, the state amount of the vehicle is calculated from the vehicle model ignoring the gravitational term, and is compared with the detection value detected by the state amount detection means. Is determined to be running on an incline when a predetermined time is equal to or greater than a predetermined value for a certain period of time.

In the road inclination determining means, when the deviation between the target value set by the target value setting means and the detection value detected by the state quantity detecting means is equal to or more than a certain value for a certain period of time. And a rear wheel steering angle control device for a four-wheel steering vehicle, which determines that the vehicle is traveling on an inclined road.

Further, the road surface inclination determining means includes a steady state determining means for determining whether the vehicle is in a straight running state or a steady turning state, and performs the road surface inclination determination only when it is determined that the vehicle is in the steady state. This is a rear wheel steering angle control device for a four-wheel steering vehicle.

The road inclination determining means has a steady state determining means for determining whether the vehicle is in a straight running state or a steady turning state. The steady state and a target value are detected by the state amount detecting means. If the deviation from the detected value is equal to or greater than the set value,
A rear-wheel steering angle control device for a four-wheel steering vehicle, which determines that the vehicle is running on an inclined road when a predetermined time has elapsed.

The vehicle state quantity detected by the state quantity detecting means is a yaw rate generated in the vehicle, and is a rear wheel steering angle control device for a four-wheel steered vehicle.

The steady state determining means determines that the vehicle is in a steady state when the speed of change of the steering wheel angle and the speed of change of the yaw rate are below a certain set value for a certain period of time. This is a wheel steering angle control device.

In the target value changing means, on a flat road, a target yaw rate set value Y previously set from the vehicle speed and the steering wheel angle is set.
m is used as a target value YM on an inclined road as a target value YM calculated from an actual yaw rate value Y detected by the state quantity detection means, and a rear wheel steering angle control device for a four-wheel steering vehicle.

In the target value changing means, the target value YM
Is gradually changed from Ym to Yd and from Yd to Ym.

In the changing speed switching means, when the target value YM is changed from Ym to Yd by the target value changing means, YM = q1 · Ym + (1-
q1) · Yd (q1 = 1 → 0), and when changing from Yd to Ym,
Using the change parameter q2, YM = (1-q2) · Ym + q2 · Yd (q2 = 1
→ 0) is a rear-wheel steering angle control device for a four-wheel steered vehicle.

Further, in the release determination means, the bank or cant shifts from a steady state to a straight traveling or turning state by steering the steering wheel, and when the condition of the steady determination is deviated, the target value YM is continuously given by Yd. A four-wheel steering vehicle characterized in that when the absolute value of the deviation between the actual yaw rate value Y detected by the state quantity detecting means and the target yaw rate value Ym falls below a certain set value, it is gradually changed to Ym. Is a rear wheel steering angle control device.

On a flat road where the influence of the gravitational term can be neglected from the traveling state quantity, or on a circulating circuit (bank) and a straight road (cant) having a slope of the road surface where the gravitational term is effective for the dynamic characteristics of the vehicle. Road surface inclination determining means for determining whether the vehicle is traveling on a slope, and gain changing means for changing a gain in the control law according to the road surface state determined by the road surface inclination determining means. This is a rear wheel steering angle control device for a four-wheel steering vehicle.

In the rear wheel steering angle calculating means, a control law having an integral term of a deviation between a target value and a detected value is used. Is gradually reduced to zero.

In the gain changing means, during running on a slope, the integral term gain is gradually reduced to zero, and other control gains are also reduced. It is.

Further, there is provided a four-wheel steering vehicle rear wheel steering angle control device comprising an integral term filtering means for using a result obtained by performing a filtering process on an integral term computation result as an integral term computation result.

The filter used in the integral term filtering means is a high-pass filter, and is a rear wheel steering angle control device for a four-wheel steering vehicle.

The update determining means determines whether or not to update the estimated vehicle state quantity Yg based on the rate of change of the steering angle, the rate of change of the vehicle state quantity Y, and the rate of change of the estimated value Yg. Then, the wheel steering angle control device is characterized in that the target value is corrected using the updated estimated value YG.

[0041]

According to the conventional target yaw rate tracking method for determining a target value from the vehicle speed, the steering wheel angle, and the like, when there is a steady disturbance, for example, when there is a bank / cant run or a sensor drift in which a gravitational term is effective, the situation is changed. Since the target value does not become the optimum target value, the steering wheel correction is required, so that a staggering feeling does not occur and the vehicle does not run with a side slip angle of zero.

However, according to the present invention, it is determined whether or not the vehicle is traveling under the influence of the steady disturbance, or the yaw rate value generated by the steady disturbance is estimated and the target yaw rate value is updated. The driver does not need to steer the steering wheel at this time, and the sense of wobble is eliminated.

Further, erroneous steering of the rear wheels due to sensor drift can be prevented without using a high-pass filter or the like, and running control that makes the side slip angle of the vehicle body zero can be performed.

[0044]

FIG. 1 is a block diagram of a wheel steering angle control device according to the present invention. Both wheels 20 represent front wheels or rear wheels, which are steered directly using the wheel steering means 18. The command signal to the wheel steering means 18 is calculated by the target steering angle calculating means 17.

The state quantity detecting means 13 detects a vehicle state quantity for determining a dynamic running state of the vehicle.

The target value setting means 14 calculates a target value of a vehicle state quantity for realizing a target vehicle dynamic characteristic from the output from the vehicle speed sensor 11 and the output from the steering wheel angle sensor 12.

The target steering angle calculating means 17 calculates a command signal to the wheel steering means 18 so that the output value of the state quantity detecting means 13 follows the target value calculated by the target value setting means 14.

The disturbance traveling determination means 16 determines whether the state in which the vehicle is traveling is a disturbance applied state with disturbance.
It is determined whether the vehicle is in the normal state without disturbance from the output values of the vehicle speed sensor 11 and the steering wheel angle sensor 12, the vehicle state quantity calculated from the vehicle model, and the output value of the state quantity detecting means 13.

The disturbance running determination means 16 sends the result of the determination to the target value changing means 15, and the target value changing means 15 changes the target value to a value corresponding to the running state.

The condition value detecting means 21 shown in FIG. 2 detects a running condition parameter relating to the magnitude of the generated vehicle state quantity, and the disturbance value determining means 21 detects the running condition parameter.
From the vehicle speed sensor 11, the steering wheel angle sensor 12, the rear wheel steering angle sensor 22, and the vehicle model, the vehicle state quantity generated during normal running is calculated by the state value detection means 13 and detected by the state quantity detection means 13. The presence / absence of disturbance can be determined by comparing the actual vehicle state quantity.

The state quantity estimating means 32 shown in FIG. 3 includes a vehicle speed sensor 11, a steering wheel angle sensor 12, a rear wheel steering angle sensor 22, and a condition value detecting means 2 in the reference state quantity calculating means 31.
From the output values of No. 1 and the vehicle state quantity in the normal state calculated from the vehicle model and the current vehicle state quantity detected by the state quantity detecting means 13, the value of the vehicle state quantity generated by the influence of disturbance Is estimated.

Using the estimated value, the target value correcting means 33 corrects the target value to be followed by the actual vehicle state quantity.

FIG. 4 shows a flowchart of the above-mentioned correction method. When the wheel steering angle control is performed in STEP 41, ST
According to EP42, the vehicle speed sensor 11, the steering wheel angle sensor 1
2. Read the sensor output values of the state quantity detecting means 13, the condition value detecting means 21, and the rear wheel steering angle sensor 22;
3, the vehicle state quantity Yh that would occur during normal running is calculated using the sensor outputs.

In step 44, the actual vehicle state quantity Y detected by the state quantity detection means 13 and the calculated vehicle state quantity Y
From h, the vehicle state quantity Yg generated by the steady disturbance is estimated.

In STEP 45, the target vehicle state quantity Ym, which does not take into account the disturbance application state, is corrected with the estimated vehicle state quantity Yg, and the corrected target value is newly set as the target vehicle state quantity YM.

In step 46, the target steering angle is calculated so that the actual vehicle state quantity Y becomes the corrected target value YM, and in step 47, the wheel steering is performed according to the target steering angle.

Here, the change rate of the calculated vehicle state quantity Yh and the actual vehicle state quantity Y is calculated by the state quantity change rate determining means 51 shown in FIG. 5. For example, the change rate of Y is larger than that of Yh. If the rate of change is larger than the change rate by a certain set value or more, it is determined that the vehicle is in a sudden disturbance application state instead of a steady disturbance application state, and the vehicle state quantity Yg estimated by the state quantity estimation means 32 is determined.
May use the previous value without updating using the current Y and Yh.

Alternatively, the estimated value change rate judging means 61 shown in FIG.
The rate of change of the estimated value Yg is obtained from the above. If the rate of change is equal to or greater than a certain set value, it is determined that a sudden disturbance is applied, and the target value correcting means 33 determines the estimated value Yg.
The target value may not be corrected using g.

Alternatively, when the change rate of the steering angle, the change rate of the vehicle state quantity Y, and the change rate of the estimated value Yg are equal to or larger than a certain set value by the update determining means 181 in FIG. The target value may not be corrected using the amount Yg, that is, Yg may not be updated.

When the value of the estimated value Yg is out of a certain set value range by the detection error determination means 71 of FIG.
It is determined that the state quantity detecting means 13 has failed, and the state quantity tracking control can be stopped.

FIG. 8 is a block diagram of a rear wheel steering angle control device according to the present invention.

The left and right rear wheels 19 are directly steered using the motor control means 82. The command signal to the electric motor control means 82 is calculated by the rear wheel steering angle calculating means 81.

The state quantity detecting means 13 detects a vehicle state quantity which indicates a dynamic running state of the vehicle. Condition value detection means 2
1 detects running condition parameters related to the magnitude of the vehicle state quantity to be generated, and the target value setting means 14 receives the vehicle speed sensor 11, the steering wheel angle sensor 12, the rear wheel steering angle sensor 22, and the condition value detecting means 21. Then, the target value of the vehicle state quantity for realizing the target vehicle dynamic characteristic is calculated from the output of.

The rear wheel steering angle calculating means 81 calculates a command signal to the motor control means 82 so that the output value of the state quantity detecting means 13 follows the target value calculated by the target value setting means 14. .

In the disturbance running determination means 16, the detection value detected by the condition value detection means 21 and the vehicle speed sensor 1
1, the steering wheel angle sensor 12, the rear wheel steering angle sensor 22, the output value of the condition value detection means 21 and the vehicle state quantity generated during normal running are calculated from the vehicle model, and the actual vehicle detected by the state quantity detection means 13. The presence or absence of disturbance application is determined by comparing the state quantity.

The disturbance running determination means 16 sends the result of the determination to the target value changing means 15, and the target value changing means 15 changes the target value to a value corresponding to the running state.

Further, the steady state determining means 91 shown in FIG. 9 determines whether the traveling state is a steady straight running or a steady turning, and performs the disturbance traveling determining means 16 only when it is determined that the vehicle is in the steady state.

Specifically, the absolute values of the respective rates of change are obtained from the output values of the steering wheel angle sensor 12 and the state quantity detecting means 21 and are compared with the respective set values. When it is equal to or less than the set value, it is determined that the vehicle is in a steady running state.

The vehicle motion determining means 101 shown in FIG.
Determines the final value of the rear wheel target steering angle from the steering direction of the steering wheel angle when the disturbance traveling determination means 16 determines that the vehicle is out of the disturbance application state.

More specifically, when the steering wheel is steered in a direction away from the center point, the rear wheels are controlled using the target rear wheel steering angle calculated from the normal target value tracking control law.

Conversely, when the steering wheel angle is steered toward the center point, the conditions are not satisfied until the target rear wheel steering angle calculated from the target value following control law becomes a value in the direction toward the center point. Be sure to hold the rear wheel.

Thus, when the condition is not satisfied, it is possible to prevent the target rear wheel steering angle from being uncomfortable when the vehicle is immediately controlled with the target rear wheel steering angle calculated from the normal target value following control law. I can do it.

Further, the vehicle speed is determined by the change speed determining means 111 shown in FIG. 11 using the actual vehicle state quantity value detected by the state quantity detecting means 13 and the steering angle value detected by the steering angle sensor. Calculates the speed of change of the amount and the speed of change of the steering angle of the steering wheel to judge whether it is sudden disturbance or sudden steering of the steering wheel. Do
It is possible to prevent disturbance suppression effect and deterioration of steering response.

FIG. 12 is a block diagram of a rear-wheel steering angle control device according to the present invention. The left and right rear wheels 19 are directly steered using the motor control means 82. The command signal to the electric motor control means 82 is calculated by the rear wheel steering angle calculating means 81.

The rear wheel steering angle calculating means 81 calculates the actual yaw rate value detected by the state detecting means 13 from the output values of the vehicle speed sensor 11 and the steering wheel angle sensor 12 by the target value setting means 14. The command signal to the motor control means 82 is calculated so as to follow.

The road surface inclination determining means 121 determines whether or not the road surface on which the vehicle is traveling is an inclined road surface such as a cant or a bank by checking the vehicle speed sensor 11, the steering wheel angle sensor 12, the rear wheel steering angle sensor 22, The presence or absence of the inclination and the degree of the inclination are determined by calculating from each sensor output value of the detection means 13.

The road surface inclination determining means 121 sends the result of the determination to the target value changing means 15, and the target value changing means 15 changes the target yaw rate value to a yaw rate value corresponding to the road surface inclination.

The road surface inclination determining means 121 determines the vehicle speed sensor 11 and the steering wheel angle sensor 1 according to the determination result.
2. The input from the rear wheel steering angle sensor 22 and the state detecting means 13 to the rear wheel steering angle calculating means 81 is controlled so that the influence of the yaw rate caused by the inclination of the road surface is canceled. May be.

Hereinafter, the algorithm in the arithmetic unit will be described. The two-degree-of-freedom vehicle model is represented by the following (Equation 1).

[0080]

(Equation 1)

From (Equation 1)

[0082]

(Equation 2)

When expanding (Equation 2),

[0084]

(Equation 3)

In the above equation, the coefficients a, b and d are functions of the vehicle speed V. A reference model of the yaw rate is given by the following equation.

[0086]

(Equation 4)

Here, Y ₀ is a two-wheel model and β (S) / θf (S) =
It is a steady yaw rate gain derived when 0 (β: side slip angle) is obtained, and is expressed by the following equation.

[0088]

(Equation 5)

Therefore, the target yaw rate when there is no disturbance such as a gravitational term or a sensor drift is given by the following equation from (Equation 4).

[0090]

(Equation 6)

The above calculation is performed by the target value setting means 14. Next, the target value changing means 15 and the target value correcting means 3
The target yaw rate changed or corrected in step 3 is Y
M, Y is the actual yaw rate detected by the state quantity detecting means 13, Yh is the yaw rate in a running state without steady disturbance predicted by the reference state quantity calculating means 31 based on the values of the front and rear wheel steering angles, the vehicle speed, and the like. If the deviation e = YM-Y, the following relationship is established in the target yaw rate follow-up control.

(No disturbance) When following: Y = YM, e = 0 At this time, Yh = Y (= Y
M) Transient: Y-> YM, e-> 0 At this time, Yh ≒ Y (≠ Y
M) (Disturbance applied state) Following: Y = YM, e = 0, Yh ≠ Y Transient: Y-> YM, e-> 0 At this time, Yh ≠ Y・ Y = Y for transient
It can be seen that h + Yg. Here, Yg is
It is a yaw rate value generated due to a gravity term, a sensor drift, or the like.

The reference state quantity calculating means 31 calculates the reference state quantity Yh by the following equation, for example.

[0094]

(Equation 7)

In the steady state, Yh = d / b (θf−θr), that is, the following equation is obtained.

[0096]

(Equation 8)

However, A = 2 · kf · kr · L, B = I · m (lf · k
f−lr · kr), L = lf + lr From the above, Yg due to the steady disturbance estimated by the state quantity estimating means 32 can be obtained by the following equation.

[0098]

(Equation 9)

From the Yg and the Ym, the target value correcting means 33 gives the target yaw rate YM to be followed by the following equation.

[0100]

(Equation 10)

By using this YM, it is possible to correct a steady disturbance element or a slowly changing disturbance element. That is, the influence of the gravity term can be removed, and the drift of the yaw rate sensor can be corrected.

Next, the operation of the road surface inclination determining means 121 will be described. First, FIG. 17 (1) during bank running,
Think about (2). If the vehicle is traveling on a flat road in FIG. 17A, the generated Yh is θf = 0 and θr = 0 (Equation 8).
The actual yaw rate Y should be Yh = 0.
| Y |> Yh = 0, which indicates that the vehicle is running on a bank.

Similarly, in FIG. 17 (2), Yh∝V '/ L
.Theta.f, and the deviation from the actual yaw rate Y is | Y-Yh
If |> α, it can be determined that the vehicle is running on a bank.

The same can be said for straight running with a cant (FIG. 17 (3)). Since the vehicle is traveling straight with the steering wheel turned, the actual yaw rate Y is Y = 0, but Yh∝V ′ / L · θf should occur on a flat road.

Summarizing the above, in the steady state, | Y−
If Yh |> α, it can be determined that the vehicle is in bank or cant driving. FIG. 12 shows a configuration for realizing this.

Therefore, the steady state determining means 91 in FIG.
Determines that it is in a steady state at Bank Kant,
If the target yaw rate YM is changed to a yaw rate value Yd that allows stable running with the bank cant, a stable and smooth running state without fluctuation can be realized.

The conditions for determination by the road surface inclination determining means 121 are as follows. (Judgment condition)

[0108]

[Equation 11]

Normally, if the target yaw rate Ym is followed at Tmsec on a flat road, it may be considered that Yh = Ym. Therefore, the third term of the judgment condition is | Y−Ym |> α
Can be replaced with

However, from (Equation 4)

[0111]

(Equation 12)

Is given by In addition, △ in the above determination conditions
Is an operator that calculates the difference between t1 (> control cycle L) for each control cycle. That is, it is not a differential value of the control system but a change speed for the determination condition.

Incidentally, Yd is a value obtained from the actual yaw rate Y used in the determination condition, and for example, an average value of Y is used.

Further, in order to eliminate the sense of discontinuity due to the change of the target value, the change parameter q is used to

[0115]

(Equation 13)

Then, the target yaw rate can be gradually changed. Here, when it is determined that the vehicle is running at YM = Ym in a steady state and it is determined that the vehicle is on an inclined road, the parameter q is changed by the change speed switching means 131, and the target value YM is changed by the following equation. This configuration is shown in FIG.

[0117]

[Equation 14]

On the other hand, if it is out of the steady state determination or the slope determination, the target value is changed by the following equation.

[0119]

(Equation 15)

The calculations of (Equation 14) and (Equation 15) are performed by the target value changing means 15. Usually, a straight road exiting from a bank is provided with a cant, and conversely, when turning from a straight line with a cant, it is usually a bank.

Therefore, by making the changing speed of q2 smaller than q1, it is possible to maintain the target value of the ramp and reduce the sense of discontinuity.

When the conditions for steady-state determination and the condition for determining the slope are satisfied again during the change in (Equation 15), q1 = 1−
As q2, YM is changed by (Equation 14).

As a method of eliminating the discontinuity due to the change of the target value other than the above, the following method is considered.

When the vehicle is running stably while following the target yaw rate value of YM = Yd while traveling in a bank or cant, when the condition deviates from the condition determined by the above (Equation 11),
Until the target value YM becomes | Ym-Y | <[epsilon], the release determination means 141 given by YM = Yd is used. Here, Yd is a value that is sequentially calculated and updated from the actual yaw rate value Y.
FIG. 14 shows the configuration.

Further, in the target yaw rate tracking method in which the target yaw rate is calculated from the vehicle speed and the steering wheel angle without considering the gravity term, on a slope surface which is affected by the gravity term,
The target yaw rate does not become a target yaw rate value at which the vehicle can travel stably on an inclined road surface.

Therefore, in the normal target value follow-up control law, since there is an integral term of the deviation between the target value and the actual yaw rate value, the actual yaw rate value becomes a target yaw rate value that is not suitable on the slope surface. The rear wheels are steered, and the rear wheels are turned off until they match.

Therefore, the driver is required to perform corrective steering. Therefore, when the road surface inclination determining means determines that the vehicle is on a slope, if the gain of the integral term is set to zero, the rear wheels are fixed at a certain angle, so that the vehicle can run stably in a certain equilibrium state. it can.

This structure is shown in FIG. To change the gain of the above-mentioned integral term to zero, the gain changing means 151 is used.

By inserting a high-pass filter into the integral term, when the deviation between the target yaw rate Ym and the actual yaw rate Y always has the same sign, the integral term is not effective and the same effect as described above is obtained. This configuration is shown in FIG.
Shown in

[0130]

According to the present invention, it is determined whether or not the vehicle is traveling in the bank cant, and when the vehicle is traveling in the bank cant, the target yaw rate value is corrected to a yaw rate value suitable for the bank cant. -The driver does not need to correct the steering wheel at the cant, and the feeling of wander is eliminated.

The following effects can be obtained particularly by providing the vehicle motion determining means. If the bank and cant conditions are not met, the normal target yaw rate follow-up control is performed. It is unlikely that the slope of the road will suddenly disappear.However, the target rear wheel steering angle depends on the steering wheel steering condition because it is controlled at the target yaw rate assumed on a flat road despite the slope. Value will not be appropriate.

The final value of the rear wheel target steering angle is determined by the vehicle motion determining means from the steering direction of the steering wheel angle.

Specifically, when the steering wheel is steered in a direction away from the center point, the rear wheels are controlled using the target rear wheel steering angle calculated from the normal target yaw rate follow-up control law.

Conversely, when the steering wheel angle is steered toward the center point, the target rear wheel steering angle calculated from the target yaw rate follow-up control law becomes a value in the direction toward the center point.
Hold the rear wheel when the condition is not met.

Thus, when the condition is not satisfied, it is possible to prevent the target rear wheel steering angle from being uncomfortable when the vehicle is immediately controlled with the target rear wheel steering angle calculated from the normal target yaw rate follow-up control law. I can do it.

Further, the following effects can be obtained by providing the change speed determining means. When the vehicle deviated from the determination conditions due to crosswind or sudden steering while running in a steady state, the control was gradually changed to the normal target yaw rate follow-up control, so that the disturbance suppression effect and the steering response were deteriorated.

The change speed judging means uses the actual yaw rate value detected by the state quantity detecting means and the steering angle value detected by the handle angle sensor to calculate the yaw rate changing speed and the steering angle changing speed. Is calculated, and it is determined whether the vehicle is in a side wind disturbance or when the steering wheel is suddenly steered, and the normal target yaw rate follow-up control is quickly performed in the case of the side wind disturbance and the sudden steering to prevent a disturbance suppression effect and a deterioration in steering response. I can do it.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a wheel steering angle control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a wheel steering angle control device according to another embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a wheel steering angle control device according to still another embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation of the wheel steering angle control device according to the embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a wheel steering angle control device according to still another embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a wheel steering angle control device according to still another embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a wheel steering angle control device according to still another embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to an embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 14 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 15 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration of a rear wheel steering angle control device of a four-wheel steering vehicle according to still another embodiment of the present invention.

FIG. 17 is an explanatory view of a vehicle traveling on an inclined road surface.

FIG. 18 is a block diagram showing a configuration of a wheel steering angle control device according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Vehicle speed sensor 12 Handle angle sensor 13 State quantity detecting means 14 Target value setting means 15 Target value changing means 16 Disturbance running determining means 17 Target steering angle calculating means 18 Wheel steering means 19 Rear wheel 20 Wheel 21 Condition value detecting means 22 Rear wheel Steering angle sensor 31 Reference state quantity calculation means 32 State quantity estimation means 33 Target value correction means 181 Update determination means

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI B62D 137: 00 (56) References JP-A-5-238402 (JP, A) JP-A 5-338548 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) B62D 6/00 B62D 7/14

Claims (28)

(57) [Claims] 1. A vehicle speed sensor for detecting a speed of a vehicle, a steering wheel angle sensor for detecting a turning angle of a steering wheel, and a target value of a vehicle state quantity which is a target vehicle dynamic characteristic based on the vehicle speed and the steering wheel angle. Target value setting means, a state quantity detecting means for detecting a vehicle state quantity to be followed as a target, and at least one of a front wheel or a rear wheel so that a value detected by the state quantity detecting means follows the target value. A target steering angle calculating means for calculating one steering angle command signal; and a wheel steering control device for a vehicle including a wheel steering means for steering a front wheel or a rear wheel based on the steering angle command signal. Disturbance running determination means for determining whether the vehicle is in a normal state or a disturbance-applied state based on a vehicle model, and responding to the running state determined by the disturbance running determination means. Te wheel steering angle control apparatus characterized by having a target value changing means for changing the target value. 2. A vehicle speed sensor for detecting a speed of a vehicle, a steering wheel angle sensor for detecting a steering angle of a steering wheel, a rear wheel steering angle sensor for detecting a steering angle of a rear wheel, and a parameter relating to a magnitude of a vehicle state quantity. A condition value detecting means for detecting a running condition, a target value setting means for setting a target value of a vehicle state quantity such that a target vehicle dynamic characteristic is obtained from a vehicle speed, a steering wheel angle, and a condition value; State quantity detecting means for detecting a state quantity of a vehicle to be driven, and a target rudder for calculating a steering angle command signal for at least one of a front wheel and a rear wheel so that a value detected by the state quantity detecting means follows the target value. In a wheel steering angle control device for a vehicle, comprising: an angle calculation unit; and a wheel steering unit that steers a front wheel or a rear wheel based on the steering angle command signal. From Dell, the current running state is a normal state, a disturbance running determination means for determining whether the disturbance is applied disturbance applied state, and according to the running state determined by the disturbance running determination means, A wheel steering angle control device comprising target value changing means for changing a target value. 3. A vehicle speed sensor for detecting a vehicle speed, a steering wheel angle sensor for detecting a steering wheel angle, a rear wheel steering angle sensor for detecting a rear wheel steering angle, and a magnitude of the vehicle state quantity Y. Condition value detecting means for detecting a running condition which is a parameter; target value setting means for setting a target value YM of a vehicle state quantity such that a target vehicle dynamic characteristic is obtained from a vehicle speed, a steering wheel angle and a condition value; State quantity detection means for detecting an actual vehicle state quantity Y to be followed; and a steering angle command signal for at least one of a front wheel and a rear wheel such that a value detected by the state quantity detection means follows the target value. A steering angle control device for a vehicle, comprising: a target steering angle calculating means for calculating a steering angle; and a wheel steering means for steering a front wheel or a rear wheel based on the steering angle command signal. Means for calculating a vehicle state quantity Yh generated during normal running without disturbance from a vehicle model, and a vehicle state generated by a steady disturbance using the reference state quantity Yh and the detected vehicle state quantity Y. Quantity Yg
And a target value correcting means for correcting the target value by using the estimated vehicle state quantity Yg. 4. A state quantity change rate determining means calculates a change rate of the detected vehicle state quantity Y and a calculated change rate of the vehicle state quantity Yh. It is determined whether the vehicle is in a steady disturbance application state or a sudden disturbance application state. In the sudden disturbance application state, the vehicle state quantity Yg estimated by the state quantity estimating means is the current Y and Yh. The wheel steering angle control device according to claim 3, wherein the device is not updated when used. 5. An estimated value change rate judging means obtains a change rate of the vehicle state quantity Yg estimated by the state quantity estimating means, compares it with a certain set value, and if it is equal to or more than the set value, sets the target value. 4. The wheel steering angle control device according to claim 3, wherein the target value is not corrected by using the value Yg in the value correction means. 6. A detection error judging means compares the vehicle state quantity Yg estimated by the state quantity estimating means with a certain set value, and judges that the state quantity detecting means has failed if the vehicle state quantity Yg is not less than the set value. 4. The wheel steering angle control device according to claim 3, wherein the state quantity tracking control is stopped. 7. A vehicle speed sensor for detecting a vehicle speed, a steering wheel angle sensor for detecting a steering wheel angle, a rear wheel steering angle sensor for detecting a rear wheel steering angle, and a parameter related to a magnitude of a vehicle state quantity. A condition value detecting means for detecting a running condition, a target value setting means for setting a target value of a vehicle state quantity such that a target vehicle dynamic characteristic is obtained from a vehicle speed, a steering wheel angle, and a condition value; State quantity detection means for detecting a vehicle state quantity to be detected, and rear wheel steering angle calculation means for calculating a rear wheel steering angle command signal so that the value detected by the state quantity detection means follows the target value; In a four-wheel steering control device for a vehicle including a motor control means for steering rear wheels based on the rear wheel steering angle command signal, a current running state is determined based on an output value of each sensor and the condition value and a vehicle model. Normal Or a disturbance running determination unit that determines whether the vehicle is in a disturbance application state to which disturbance is applied, and a target value changing unit that changes the target value according to the running state determined by the disturbance running determination unit. A rear-wheel steering angle control device for a four-wheel steering vehicle. 8. The running condition detected by the condition value detecting means is a road surface friction coefficient.
Using the values of vehicle speed, steering wheel steering angle, rear wheel steering angle, and road surface friction coefficient, calculate the state quantity of the vehicle from the vehicle model ignoring the gravity term and compare with the detection value detected by the state quantity detection means. 8. The method according to claim 7, wherein when the deviation is equal to or greater than a predetermined value for a predetermined time, it is determined that a disturbance is applied.
A rear-wheel steering angle control device according to the above-mentioned four-wheel steering vehicle. 9. A steady state determining means for determining whether the vehicle is in a steady straight running state or a steady turning state. Only when it is determined that the vehicle is in a steady state, the disturbance state determining means determines a target value of the vehicle state quantity. 8. A rear wheel steering angle control device for a four-wheel steering vehicle according to claim 7, wherein the controller compares the vehicle state quantity with a detected value of the vehicle state quantity, and determines that a disturbance is applied when the deviation is equal to or greater than a predetermined value. . 10. When the vehicle movement determination means determines that the vehicle is out of the disturbance application state by the disturbance traveling determination means, the current vehicle movement is the vehicle movement for which the target value tracking control is to be performed, or the current vehicle movement. 8. The rear wheel steering angle control device for a four-wheel steering vehicle according to claim 7, wherein it is determined whether or not the vehicle is to be steered based on the steering angle command signal of the vehicle, and the wheel steering control is performed accordingly. 11. A change speed determining means calculates a steering wheel change speed and a vehicle state quantity change speed, and when the values are equal to or greater than a certain set value, sets a target value determined by the target value changing means to: The rear wheel steering angle control device according to claim 7, 9 or 10, wherein the tracking control is performed by replacing the target value with a target value set by a target value setting means. 12. A vehicle speed sensor for detecting a vehicle speed, a steering wheel angle sensor for detecting a steering wheel rotation angle, a rear wheel steering angle sensor for detecting a rear wheel steering angle, and a target vehicle based on the vehicle speed and the steering wheel angle. Target value setting means for setting a target value of the vehicle state quantity as a dynamic characteristic, state quantity detection means for detecting a vehicle state quantity to be followed as a target, and a value detected by the state quantity detection means, Four-wheel steering of a vehicle comprising: a rear wheel steering angle calculating means for calculating a rear wheel steering angle command signal so as to follow the target value; and a motor control means for steering rear wheels based on the rear wheel steering angle command signal. In the control device, the vehicle is driven on a flat road in which the influence of the gravitational term can be neglected from the traveling state amount, or the circuit has a sloping circuit (bank) and a straight road (kant) having a sloping road surface in which the gravitational term affects the vehicle dynamic characteristics. On a ramp Rear-wheel steering of a four-wheel-steered vehicle, comprising: road surface inclination determining means for determining whether the target value is changed, and target value changing means for changing the target value in accordance with the road surface state determined by the road surface inclination determining means. Angle control device. 13. A road surface inclination determining means calculates a state quantity of a vehicle from a vehicle model ignoring a gravity term by using each traveling state quantity of a vehicle speed, a steering wheel angle, and a rear wheel steering angle. 13. The four-wheel steering vehicle according to claim 12, wherein the detected value is compared with a value detected by the amount detecting means, and when the deviation is equal to or greater than a certain set value for a predetermined time, it is determined that the vehicle is traveling on an inclined road. Wheel steering angle control device. 14. When the deviation between the target value set by the target value setting means and the detection value detected by the state quantity detection means is equal to or greater than a certain value for a certain period of time. 13. The rear wheel steering angle control device according to claim 12, wherein it is determined that the vehicle is running on an inclined road. 15. A road surface inclination determining means for determining whether the vehicle is in a straight running state or a steady turning state, and determining the road surface inclination only when it is determined that the vehicle is in a steady state. The rear wheel steering angle control device according to claim 12, characterized in that: 16. A road surface inclination judging means comprising a steady state judging means for judging whether the vehicle is in a straight running state or a steady turning state, wherein a steady state and a target value are detected by the state quantity detecting means. 13. The rear-wheel steering angle control device for a four-wheel steered vehicle according to claim 12, wherein when a deviation from the detected value is equal to or greater than a set value and a predetermined time has elapsed, it is determined that the vehicle is traveling on an inclined road. 17. The rear wheel steering angle control device according to claim 12, wherein the vehicle state quantity detected by the state quantity detecting means is a yaw rate generated in the vehicle. 18. The steady state determining means determines that the vehicle is in a steady state when the steering wheel angle change speed and the yaw rate change speed are equal to or less than a set value for a certain period of time. 18. The rear wheel steering angle control device according to claim 17, wherein: 19. A target value changing means for calculating a target yaw rate set value Ym set in advance from a vehicle speed and a steering wheel angle on a flat road, and an actual yaw rate value Y detected by said state quantity detecting means on a slope road. 19. The rear-wheel steering angle control device for a four-wheel steering vehicle according to claim 18, wherein Yd obtained is used as a target value YM. 20. The rear wheel steering angle control according to claim 19, wherein the target value changing means gradually changes the target value YM from Ym to Yd and from Yd to Ym. apparatus. 21. In the changing speed switching means, when the target value changing means changes the target value YM from Ym to Yd by using the changing parameter q1, YM = q1.Ym + (1-q1).
Yd (q1 = 1 → 0), and when changing from Yd to Ym, using the change parameter q2, YM = (1-q2) · Ym + q2 · Yd (q2 = 1 → 0)
20. The rear-wheel steering angle control device according to claim 19, wherein: 22. A cancellation determination means which shifts from a steady state of the bank or cant to a straight running or turning state by steering the steering wheel, and when the condition of the steady state determination is deviated, the target value YM is continuously given by Yd. When the absolute value of the deviation between the actual yaw rate value Y detected by the state quantity detection means and the target yaw rate value Ym falls below a certain set value,
20. The rear-wheel steering angle control device for a four-wheel steered vehicle according to claim 18, wherein the angle is gradually changed to Ym. 23. A vehicle speed sensor for detecting a vehicle speed, a steering wheel angle sensor for detecting a steering wheel rotation angle, a rear wheel steering angle sensor for detecting a rear wheel steering angle, and a target vehicle based on the vehicle speed and the steering wheel angle. Target value setting means for setting a target value of the vehicle state quantity as a dynamic characteristic, state quantity detection means for detecting a vehicle state quantity to be followed as a target, and a value detected by the state quantity detection means, In a four-wheel steering control device for a vehicle including a rear wheel steering angle calculating means for calculating a rear wheel steering angle command signal so as to follow the target value, and a motor control means for steering the rear wheels, It is determined whether the vehicle is traveling on a flat road where the influence of the term can be neglected, or whether the vehicle is traveling on a sloping road (a bank) or a straight road (a cant) with a sloping road surface where the gravitational term affects the vehicle dynamic characteristics. Road surface inclination judgment hand When, in accordance with the road surface state determined by the road surface slope determination means, wheel steering angle control system of a four-wheel steering vehicle, characterized in that it comprises a gain changing means for changing the gain in the control law. 24. A rear wheel steering angle calculating means using a control law having an integral term of a deviation between a target value and a detected value, wherein said gain changing means includes an integral term gain during traveling on a slope. 24. The rear wheel steering angle control device according to claim 23, wherein is gradually reduced to zero. 25. The four-wheel-steered vehicle according to claim 23, wherein the gain changing means gradually reduces the integral term gain to zero and other control gains during running on a slope. Wheel steering angle control device. 26. A vehicle speed sensor for detecting a speed of a vehicle, a steering wheel angle sensor for detecting a rotation angle of a steering wheel, a rear wheel steering angle sensor for detecting a rear wheel steering angle, and a target vehicle based on the vehicle speed and the steering wheel angle. Target value setting means for setting a target value of the vehicle state quantity as a dynamic characteristic, state quantity detection means for detecting a vehicle state quantity to be followed as a target, and a value detected by the state quantity detection means, A vehicle comprising: a calculating means for calculating a rear wheel steering angle command signal using a control law having an integral term of a deviation between a target value and a detected value so as to follow the target value; and a motor control means for steering rear wheels. The four-wheel steering control device according to any one of claims 1 to 3, further comprising an integral term filtering means for using, as a result of the integral term operation, a result obtained by performing a filtering process on the operation result of the integral term. 27. The rear wheel steering angle control device according to claim 26, wherein the filter used in the integral term filtering means is a high-pass filter. 28. A vehicle speed sensor for detecting a vehicle speed, a steering wheel angle sensor for detecting a steering wheel angle, a rear wheel steering angle sensor for detecting a rear wheel steering angle, and a magnitude of the vehicle state quantity Y. Condition value detecting means for detecting a running condition which is a parameter; target value setting means for setting a target value YM of a vehicle state quantity such that a target vehicle dynamic characteristic is obtained from a vehicle speed, a steering wheel angle and a condition value; State quantity detection means for detecting an actual vehicle state quantity Y to be followed; and a steering angle command signal for at least one of a front wheel and a rear wheel such that a value detected by the state quantity detection means follows the target value. A steering angle control device for a vehicle, comprising: a target steering angle calculating means for calculating a steering angle; and a wheel steering means for steering a front wheel or a rear wheel based on the steering angle command signal. A reference state quantity calculating means for calculating, from the vehicle model, a vehicle state quantity Yh generated during normal running without disturbance from the values, and a vehicle generated by a steady disturbance using the reference state quantity Yh and the detected vehicle state quantity Y. State quantity Y
a state quantity estimating means for estimating g, and determining whether to update the estimated vehicle state quantity Yg based on the rate of change of the steering wheel angle, the rate of change of the vehicle state quantity Y, and the rate of change of the estimated value Yg. A wheel steering angle control device, comprising: an update determination unit that performs the correction; and a target value correction unit that corrects the target value by using the estimated value YG updated by the update determination unit.