JPH0671864B2 - Vehicle yaw motion control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to a yaw motion control method for a vehicle, which controls the yaw motion based on the output of a steering angle sensor attached to a steering wheel. Regarding

(2) Conventional Technology Conventionally, a steering angle sensor attached to a steering wheel measures a steering angle value by performing pulse counting of a pulsar provided in a tearing column, and a yaw motion of a vehicle It was controlled using the detected turning angle value.

(3) Problems to be Solved by the Invention However, the steering angle sensor often deviates from the actual steering angle when it is attached to the steering wheel. However, the neutral point may shift due to some external force while the vehicle is traveling. When the neutral point shifts in this way, the pulse count value is reset in response to the neutral point pulse even though the neutral point pulse does not match the actual steering angle neutral point. The value is not shown, and the yaw motion control that corrects based on the steering angle value becomes uncertain.

The present invention has been made in view of such circumstances, and detects the steering angle close to the actual steering angle by correcting the output of the steering angle sensor regardless of the mounting state of the steering angle sensor on the steering handle. However, it is an object of the present invention to provide a vehicle yaw motion control method capable of controlling the yaw motion based on the almost accurate steering angle.

B. Configuration of the Invention (1) Means for Solving the Problems The present invention for achieving the above object is a yaw motion of a vehicle that controls the yaw motion based on the output of a steering angle sensor attached to a steering wheel. In the control method, the turning angle is estimated, and the output value of the turning angle sensor is gradually corrected within a fixed time based on the error between the estimated turning angle and the turning angle detected by the turning angle sensor. It is characterized by

(2) Action According to the method of the present invention, the output of the steering angle sensor is corrected by the error from the estimated steering angle, so that the steering angle close to the actual steering angle can be obtained and is constant. Since the correction is made gradually in time, abrupt correction control of the yaw motion is avoided.

(3) Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, speed sensors Sl and Sr are individually provided to left and right rear wheels Wrl and Wrr as free rolling wheels in a front-wheel drive vehicle. The output signals of these speed sensors Sl and Sr, which are additionally provided, are input to the turning angle detection device 1 configured by a computer. A steering angle sensor 2 is attached to the steering wheel H, and the output of the steering angle sensor 2 is also input to the steering angle detection device 1.

The steered angle detection device 1 is a computer, and includes a yaw motion detection means 3 for detecting a yaw rate R as a yaw motion state of the vehicle based on outputs of the speed sensors Sl, Sr, and outputs of the speed sensors Sl, Sr. Based on the vehicle speed detecting means 13 for detecting the vehicle speed V from the average value, the steering gain determining means 14 for determining the steering gain by the output of the yaw motion detecting means 3 and the output of the vehicle speed detecting means 13, and the steering gain G and the yaw rate R. The steering angle estimating means 4 for estimating the steering angle δ _{P of the} vehicle and the steering angle correcting means 5 for correcting the output S of the steering angle sensor 2 by the output of the steering angle estimating means 4 are provided. Steering angle correction means 5
Is an error detection circuit 6 for detecting an error between the output S of the steering angle sensor 2 and the output δ of the steering angle estimation means 4, and a correction circuit 7 for correcting the output of the steering angle sensor 2 by the error. Prepare

The output of the vehicle speed detecting means 13, that is, the vehicle speed V and the turning angle δ ′ obtained by the turning angle detecting device 1 are inputted to the reference yaw rate generating means 8 and the reference yaw rate obtained by the reference yaw rate generating means 8. The yaw rate R obtained by the yaw motion detecting means 3 is input to the subtraction circuit 9. Thus, the subtraction circuit 9 calculates the absolute value of the difference between the reference yaw rate and the yaw rate R. That is, the difference between the current yaw rate and the current yaw rate R is calculated. The output of the subtraction circuit 9 is input to the non-inverting input terminal of the comparator 10,
The reference value is input from the terminal 11 to the inverting input terminal of the comparator 10. Therefore, the comparator 10 outputs a high level signal when the deviation between the current yaw rate and the current yaw rate R is larger than the reference value, and the output of the comparator 10 is the yaw motion correction means 12, for example. It is input to the means for correcting the yaw motion by controlling the engine output.

In the turning angle detecting device 1 which is a computer, the turning angle is obtained by the procedure shown in FIG. First step S1
Then, it is determined whether the flag F is 1. The flag F is for indicating whether or not the steering angle is being corrected, and F = 1 indicates that the steering angle is being corrected. If F = 1 in this first step S1, the 19th step S1
9. If F = 0, then proceed to the second step S2.

The second step S2 to the tenth step S10 are for determining whether or not the driving state of the vehicle is in the steady region suitable for steering angle correction, and when it is determined that the vehicle is out of the steady region. The timer T _S is reset in the eleventh step S11. This timer T _S is for counting the time required for determining whether or not the vehicle is in the steady region, for example, 2 seconds.
10 It is reset every time it is determined in step S10 that it is out of the steady region.

Each element for determining whether or not the vehicle is in the steady region will be described individually. First, in a second step S2, it is determined whether or not the vehicle speed V is a lower limit vehicle speed, for example, 8 km / h or more, and a third step S3. Then, the vehicle speed V is the upper limit vehicle speed, for example 50.
It is determined whether or not it is less than km / h. In the fourth step S4, the yaw rate R of the vehicle is set to an allowable yaw rate range, for example, 5 °.
/ sec or less is determined. In the fifth step S5, it is determined whether or not traction control such as braking for suppressing excessive slip of the driving wheels and engine output reduction is being performed. In the sixth step S6, the steering angle S is determined. Is determined to be within the allowable steering angle width. The allowable steering angle width is determined according to the vehicle speed V as shown in FIG. 3, and the allowable steering angle width is set smaller as the vehicle speed V increases.

In the seventh step S7 and the eighth step S8, the yaw rate R and the turning angle S of this time are set to the average yaw rate R of the previous time set in the 23rd step S23 described later immediately after the correction is finished.
It is determined whether or not _A ′ and the average turning angle S _A ′ or more, and if it is, proceed to the 11th step S11. This is because the correction operation is started only when the vehicle is running straight ahead of the average yaw rate R _A or the average steering angle S _A when the error of the steering angle sensor 2 was corrected last time, and a more accurate estimated steering angle is obtained. It is something to try.

In the ninth step S9, it is determined whether the yaw rate R is in the steady region. This steady region is set between the shaded regions in FIG. 4, and the yaw rate R at the time when all the conditions from the second step S2 to the eighth step S8 are satisfied for the first time The steady area (steady turning or straight traveling state) is defined from the center value of R. In the ninth step S9, it is determined whether or not the set time counted by the timer T _S is in the steady region for 2 seconds or more. In the tenth step S10, the steering angle S
Is determined to be in the stationary region. This steady region is set in the same manner as the steady region of the yaw rate R described above.
It is determined in step S10.

In this way, the second step S2 to the tenth step S10
Then, when it is determined that the vehicle operating state is in the steady region, the process proceeds to a twelfth step S12, and when it is determined that the vehicle is not in the steady region, the timer T _S is reset at the eleventh step S11.

In twelfth and thirteenth step S12, S13, an average value S _A of average values R _A and the steering angle S of the yaw rate R is calculated by the equation (1) and the equation (2) below.

Here, N is the cumulative number of samplings from the start of the calculation of the formulas (1) and (2), and the formulas (1) and (2) depend on the elapsed time from the start of the average value calculation. Then, a so-called moving average, which changes the influence of the sampling value on the average value, is used. The subscript ( _-1 ) indicates the previous value.

In the 14th step S14, it is determined whether or not the counting of the set time by the timer T _S has ended. When the time T _S for determining the steady region has elapsed, the flag F is set to 1 in the 15th step S15. To do.

The next 16th step S16 shows the processing in the turning angle estimating means 4, and the estimated turning angle δ _P is obtained by dividing the yaw rate average value R _A by the steering gain G. That is, δ _P = _RA / G and G = G ₀ −G′R. here
G ₀ is a reference gain that is determined depending on the vehicle speed V as shown in FIG. 5, and is theoretically obtained by the following equation (3).

Here, n is a steering gear ratio, l is a wheel base, and K is a stability factor. G'is a correction coefficient for reducing the steering gain when the yaw rate R increases. That is, the relationship between the yaw rate and the steered angle is as shown in FIG. 6 when the vehicle speed is constant, and the yaw rate R and the vehicle speed V are shown.
The lateral acceleration applied to the vehicle is determined from the above, and the influence of the lateral acceleration causes the movement of the vehicle load and the change in the compliance of the suspension, and the steering gain changes accordingly. Therefore, the correction coefficient G'is set according to the vehicle speed. ,
By correcting the theoretical value G ₀ of the steering gain with a value obtained by multiplying the correction coefficient G ′ by the yaw rate R, the steering gain during the actual traveling of the vehicle is approximated.

In the 17th step S17, the error ε ₁ is calculated. That is, the difference between the turning angle δ _P estimated by the turning angle estimating means 4 and the average value S _A of the turning angles S obtained by the turning angle sensor 2 (ε ₁ =
δ _P −S _A ) is calculated. Further next 18th step S18
Then, the following calculation is performed.

Δε = ε ₁ / N ₁ (4) In this equation (4), N ₁ is determined by N ₁ = T _C / T _LOOP , and T _C is the steering wheel after the steady region determination as shown in FIG. The time is set for correction of the angular value, and is set to 1 second, for example. Therefore, the equation (4) is for obtaining the correction amount Δε for each loop in the processing procedure shown in FIG.

In the 19th step S19, the correction value ε ₀ is obtained by the following equation (5).

ε ₀ = ε ₀ + Δε (5) Furthermore, in the twentieth step S20, it is determined whether or not the time T _C set for the correction of the steering angle value has elapsed, and if not, the 24th step S24 proceeds to When the time has passed, the process proceeds to the 21st step S21. In the 21st step S21, the flag F is set to 0, and in the 22nd step S22, the timers T _S and T _{C are set.}
After resetting, the yaw rate average value R _{A is set} to R _A ′ and the steering angle average value S _A is set to S _A ′ in the 23rd step S23.

In the 24th step S24, the steering angle δ ′ output from the steering angle detection device 1 is calculated by the following equation (6).

δ ′ = S + ε ₀ (6) Next, the operation of this embodiment will be described. In the processing procedure shown in FIG. 2, in the second step S2 to the tenth step S10, the turning angle sensor 2 detects the turning angle. Rudder angle S
It is determined whether or not the vehicle is in the steady region in order to perform the correction of 1., and when it is determined that the vehicle is in the steady region, the flag F is set to 1 in the fifteenth step S15 and the process proceeds to the next step.

After the vehicle is determined to be in the steady operation state as described above, the correction amount Δε per processing loop is calculated in the 16th step S16 to the 18th step S18. That sixteenth step S16 the yaw rate R _A steering gain estimated steering angle by dividing the G [delta] _P is obtained, the error of the steering angle mean value S _A based on the output of the estimated steering angle [delta] _P and the steering angle sensor 2 ε ₁ is obtained in the 17th step S17, and the error ε ₁ causes the processing loop 1
The correction amount Δε per operation is obtained in the 18th step S18.
Such 16th step S16 to 18th step S18,
It is executed only in the first processing loop after it is determined that the operating state of the vehicle is in the steady region, and thereafter, the process proceeds from the first step S1 to the nineteenth step S19.

Here, referring to FIG. 7, assuming that there is an error of ε ₁ between the detected turning angle S by the turning angle sensor 2 and the estimated turning angle δ _P by the turning angle estimating means 4, The correction value ε ₀ obtained by adding the correction amount Δε for each processing loop is added to the turning angle S, and the turning angle detection device 1 is operated before the set time T _C elapses.
The output δ ′ from is corrected to the estimated turning angle δ _P. That is, the difference between the detected turning angle S and the estimated turning angle δ _P is the set time.
By the time T _C elapses, it gradually becomes 0. By making redundant corrections in this way, abrupt correction control by the yaw motion correction means 12 is avoided and correction of yaw motions is performed. It becomes possible to do it gently.

In the above embodiment, the turning angle is estimated based on the yaw rate and the vehicle speed, but the turning angle may be estimated based on the lateral acceleration of the vehicle and the vehicle speed.

C. Effects of the Invention As described above, according to the present invention, the steering angle is estimated, and based on the error between the estimated steering angle and the steering angle detected by the steering angle sensor, the steering angle sensor Since the output value is gradually corrected within a fixed time, it is possible to obtain a nearly accurate steering angle regardless of how the steering angle sensor is attached to the steering wheel. By being performed gradually, the rapid correction control of the yaw motion is avoided.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a block diagram showing the overall configuration, FIG. 2 is a flow chart showing processing time, and FIG. 3 is a diagram showing a setting state of an allowable steering angle width. ,
FIG. 4 is a diagram showing an allowable width for judging the stable state of the yaw rate and the turning angle, FIG. 5 is a characteristic diagram of the reference steering gain, and FIG. 6 is a relationship between the yaw rate and the turning angle in a constant vehicle speed state. FIG. 7 is a diagram for explaining a steering angle correction procedure. 2 ... Steering angle sensor H ... Steering handle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B62D 113: 00 137: 00 (56) References JP-A-63-251373 (JP, A) JP-A Sho 60-161260 (JP, A) JP 59-186775 (JP, A) JP 58-128962 (JP, A)

Claims (2)

[Claims] 1. A yaw motion control method for a vehicle, which controls a yaw motion based on an output of a steering angle sensor attached to a steering handle, estimates a steering angle, and estimates the steering angle and the steering angle. A yaw motion control method for a vehicle, characterized in that an output value of a steering angle sensor is gradually corrected within a fixed time based on an error from a steering angle detected by a sensor. 2. A yaw motion control method for a vehicle according to claim 1, wherein the steering angle is estimated based on the yaw rate and the vehicle speed of the vehicle.