JPS62181959A - Cornering power detector - Google Patents

Abstract

PURPOSE:To make accurate detection performable in relatively easy and simple constitution with the existing sensor, by detecting a specific car speed where a crosswise speed comes to zero while a vehicle performs its steady turning motion, and finding cornering power out of this specific car speed. CONSTITUTION:A crosswise speed detecting device 101 directly or indirectly detects a crosswise speed at a time when detecting a fact that a vehicle is in its steady turning motion with a steady turning motion detecting device 101, while a specific car speed detecting device 102 detects a specific car speed at a time when the crosswise car speed comes to zero during the steady turning motion, and a cornering power operational device 103 finds cornering power with operation on the basis of the detected value of the specific car speed. Therefore, the crosswise car speed is detectable with the crosswise speed detecting device 101 and the specific car speed detecting device 102, and on the basis of this specific car speed, the cornering power can be found. Therefore, using the existing sensor, the cornering power is detectable with relatively easy and simple constitution in an accurate manner.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a cornering power detection device that can detect the cornering power of a vehicle relatively easily and with a simple configuration by detecting a specific vehicle speed. .

(Prior Art) Conventionally, as devices for detecting vehicle motion states 'E and Qlk, only devices that detect motion state quantities that can be easily measured, such as yaw rate sensors and lateral acceleration sensors, have been realized or proposed. .

(9. Problems that the invention attempts to solve) However,
As electronic control technology for vehicles has improved in recent years, it has become necessary to detect a wide variety of motion state quantities. However, many motion state quantities are difficult to actually measure, and these sensing devices are has not been realized. For example, a detection device that accurately detects cornering power has not yet been realized.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes the means shown in FIG.

Steady turning detection means 100 detects that the vehicle is in a steady turning movement state.

The lateral speed detection means 101 is the steady turning detection means 100.
directly or indirectly detects the lateral speed of the vehicle when it is detected that the vehicle is in a steady turning motion state.

The specific vehicle speed detection means 102 detects a specific vehicle speed when the lateral speed detected during steady turning motion becomes zero.

The cornering power calculating means 108 calculates the cornering power of the vehicle based on the detected value of the specific vehicle speed.

(Function) Once the specific vehicle speed is known, the cornering power of the vehicle can be determined relatively easily based on the specific vehicle speed. Further, since the specific vehicle speed can be detected using the lateral speed detection means 101 and the specific vehicle speed detection means 102, the present invention has a relatively easy and simple configuration.
The cornering power of the vehicle can be detected with high accuracy.

(Embodiment) FIG. 1 shows the configuration of an embodiment of the present invention. In this embodiment, the cornering power detection device of the present invention is applied to a vehicle interlocking state quantity estimating device (for details, refer to Japanese Patent Application No. 60-50
558)).

The arithmetic processing device 1 is constituted by a microcomputer or an electric circuit, and is represented by functional blocks in the figure for ease of explanation.

Vehicles on which this embodiment device is installed (hereinafter referred to as "self-armed forces")
A yaw rate sensor 8 that detects the yaw rate that occurs in the vehicle 20 and a lateral acceleration sensor 6 that detects the lateral acceleration α that occurs in the vehicle are installed near the center of gravity of the vehicle 20. On the other hand, another lateral acceleration sensor 7 is arranged at a predetermined distance l in the longitudinal direction of the vehicle body.

Also, near the vehicle weight point, the lateral speed vy of the host vehicle 20 is
A lateral speed sensor 9 is installed to detect the lateral speed sensor 9. This lateral speed sensor 9 may be, for example, an optical ground speed sensor whose detection direction is set parallel to the horizontal axis of the vehicle. use

The steering wheel steering angle sensor 2 detects the steering angle θS of a steering wheel (not shown), and the vehicle speed sensor 8
is for detecting the vehicle speed V of the vehicle 20.

The arithmetic processing device 1 is categorized by function: a yaw angular acceleration detection section 11, a steady turning motion discrimination section 12, a motion state amount estimation section 18, a stability 7 actor identification section 14, a specific vehicle speed detection section 15, and It is divided into a parameter identification section 16.

The yaw angular acceleration detection unit 11 determines the yaw angular acceleration applied to the vehicle 20 using the detected values α of the two lateral accelerations.

It is determined from αR by a simple calculation. The yaw angular acceleration obtained here is the value (f
(This is because accurate output can be obtained in real time since not all calculations are performed for lik). Therefore, the detected value ψ of the yaw angular acceleration is used.

...α −α Specifically, it is determined as ψ−−−1−−−−− (1).

However, t is the distance between the two lateral acceleration sensors.

The steady turning motion determination unit 12 calculates the lateral acceleration α detected by the lateral acceleration sensor 6, the yaw rate ψ detected by the yaw rate sensor 8, the vehicle speed V detected by the vehicle speed sensor 8, and the lateral acceleration detected value α. lateral translational acceleration vy
(−α−V÷), the detected yaw angular acceleration value ψ obtained by the yaw angular acceleration detection section 11, and the estimated value V of the lateral translational acceleration obtained by the motion state amount estimation section 18, which will be described later.
.

: , the estimated value ψ of the yaw angular acceleration, and the estimated value α of the lateral acceleration are input, and based on these input information, it is determined whether the vehicle 20 is in steady turning motion.

If it is determined that the vehicle is in steady rotational motion, information F□ indicating this is generated.

The interlocking state quantity estimating unit 18 uses a preset vehicle model (
This is a simulation model set using vehicle specifications and equations of motion), and a steering angle of 0s is used as steering input information.
and vehicle speed V are given, the motion state exhibited by the vehicle model is calculated, and the motion state quantity corresponding to these steering angle θS and vehicle speed V is determined by estimation.

As the estimated value of the motion state mMk, in addition to the estimated value Vy of the degree of estimation of the yaw rate, appropriately required motion state quantities such as lateral acceleration and tire cornering force are estimated.

That is, the motion state quantity estimating unit 18 can output a plurality of vehicle motion state quantities by detecting the steering angle θ8 and the vehicle speed V, and can output a plurality of vehicle motion state quantities by using a plurality of sensing devices that independently detect each motion state quantity. It has the same functionality as if it were equipped.

The stability 7 actor identification unit 14 compares the detected yaw rate value ψ and the estimated yaw rate value ψ, determines the value closest to the stability factor of the actual vehicle based on the comparison result, and uses this value as the stability factor. Output as estimated value A.

That is, this stability factor estimation value A is the stability factor of the vehicle model used by the motion state quantity estimation section 18, and therefore, this stability factor identification section 14 identifies the stability factor of the vehicle model. It can be said that it is something that is done.

The specific vehicle speed detection unit 15 inputs the detected lateral speed value vy, the detected steering angle value θS, and the detected vehicle speed value V, and determines that the detected lateral speed value Vy is V
The vehicle mV when the speed becomes y-o is determined, and this is set as the specific vehicle speed Vp.

Note that the stability 7 actor identifying section 14 and the specific vehicle speed detecting section 15 operate when it is informed by the information F0 that the vehicle is in a steady turning motion state.

The parameter identification unit 16 performs a predetermined calculation on the input specific vehicle speed Vp to determine the front wheel cornering power Ky of the vehicle.
and find the rear wheel cornering power KR. In this calculation process, the estimated stability factor value A given from the stability factor identification section 14 is also used.

The front wheel cornering power KF and the rear wheel cornering power KR determined by the parameter identification section 16 are the front wheel cornering power and the rear wheel cornering power, which are parameters of the vehicle model used in the motion state quantity estimation section 18. given as the value of That is, the parameter identification unit 16 identifies parameters of the vehicle model.

FIG. 8^FIG. 7 is a flowchart showing the processing executed by the arithmetic processing unit 1 when the arithmetic processing unit ff1l is configured using a microcomputer, and each process is repeatedly executed at fixed time intervals. be done.

The steady turning interlock determination process shown in FIG. 8 has the same functions as the yaw angular acceleration detection section 11 and the steady turning movement determination section 12 in FIG. 2.

That is, through the processing of steps 51 to 56, the estimated lateral acceleration value α is set to the predetermined value α. The detected lateral acceleration value α is greater than the predetermined value α. The detected yaw angular acceleration value ψ is equal to or less than a predetermined value (that is, is vy−〇, and the estimated lateral translational acceleration −9 value Vy is Vy−o. Steady 7 lag F for determining that the vehicle is in a steady turning motion state and memorizing that fact.
0 is set to "1" (step 57).

On the other hand, if even one of the conditions in steps 51 to 56 is not satisfied, it is determined that the vehicle is not in steady turning motion, and the steady state flag F0 is reset in step 58.

The linked a amount estimation process shown in FIG. 4 corresponds to the motion state amount estimating section 18 in FIG. 2.

In this process, the motion state quantities corresponding to the steering angle θS and the vehicle speed V are estimated using the vehicle model described above.

Here, among the parameters of the vehicle model, front wheel cornering power KF and rear wheel cornering power KR are determined by a parameter identification process described later. This front wheel cornering power -KIF and rear wheel cornering power KR are temporarily stored in a predetermined memory area.
and is read from this memory area when step 62 is executed. For other vehicle specifications, values stored in memory in advance as fixed values are read out, and
Used for calculations.

In step 68, the θS and V read in step 61 are given to the vehicle model, and predetermined calculations are performed to obtain the amount of motion state exhibited by the vehicle model by estimation.

The specific vehicle speed detection process shown in FIG. 5 corresponds to the specific vehicle speed detection section 15 in FIG.

In step F1, it is determined whether the vehicle is in steady turning motion or not depending on whether the steady state flag F0 is set. Here, if the determination is YES, step 7
2 or less processing is performed.

In step 72, whether or not the steering wheel is being turned is checked based on whether the steering angle θ8 is larger than a small predetermined value θ8°.

If 6s>θSC, then the process proceeds to step 78, and it is determined whether the detected lateral velocity value Vy is smaller than a predetermined value Vy0 (-o).

Here, if vy<vyo, the detected vehicle speed value V at this time is read, and the first position in the predetermined memory area (Saturday is 1 to
(N natural number) is written t1.

Then, the processes of steps 71 to 75 are repeated until i reaches N, and when N pieces of data are collected, in step 76, the average value of these N pieces of data is calculated, and this is Let be a specific vehicle speed V. That is, . This Vp is the average value obtained when the specific vehicle speed when the detected lateral speed value Vy becomes v, -0 during steady turning motion of the vehicle is determined N times. This is a process for eliminating errors caused by noise components such as vehicle vibrations, because if the detection is performed only once, there is a risk of errors caused by noise components such as vehicle vibration.

After the specific vehicle speed Vp is determined, the above N pieces of data v1
Step 77) and Step 8, the determined specific vehicle speed Vp is output and temporarily stored in a predetermined memory area.

The relationship between the specific vehicle speed V, the lateral speed V, and the vehicle speed V is shown in FIG. 8 (steering angle 03←0).

Furthermore, since VP is 40 to 60 km/h in general vehicles, it is a practically detectable amount.

The stability factor identification process shown in FIG.
This corresponds to the stability factor identification section 14 in yJ.

This process is also executed when the steady 7 lag F knee is 1 (
Step 81).

In step 82, the detected yaw rate value ψ and the estimated yaw rate value ψ (9 is obtained in step 68 of the motion state quantity estimation process and temporarily stored in a predetermined memory area) are read, Compare the size of both.

Then, if 1÷I>Iψ1, the address flag FA is decreased by "1" by the process of step 88,
Conversely, if 1÷1<lψ1, the address flag FA is increased by rlJ through the process of step 84.

1. In step 85, the stability 7 actor estimated value A stored at the address indicated by the address flag FA determined in step 83 or 84 is read out from the data table previously stored in the memory.

In the data table, values of the stability factor that can be taken when the dynamic characteristics of the vehicle vary are selected in a stepwise manner and are arranged in sequence.

These values are determined in advance through calculations, experiments, and the like. For example, the contents of this data table are as shown in Table 1. Note that Table 1 shows an example in which seven different types of stability 7 actors are stored in the data table, but this may be further subdivided to provide eight or more addresses depending on the memory capacity. It is possible.

Table 1 The processing in steps 82 to 86 is repeatedly executed while the vehicle is making steady turning motion, and each time, the stability factor estimated value A is
The value of is identified and the value closest to the actual vehicle stability factor is selected.

The stability 7 actor estimated value A obtained here is not directly used to modify the motion characteristics of the vehicle model, but it is used for calculations in the parameter identification process described later, so it can be used indirectly to modify the vehicle model. Involved in modifying movement characteristics.

The parameter identification process shown in FIG. 7 corresponds to the parameter identification section 16 in FIG.

In step 91, a process is performed to read the specific vehicle speed V detected in the specific vehicle speed detection process, and in step 92, rear wheel cornering power KR is determined using the read specific vehicle speed vp. This calculation of KR is performed according to the following formula.

Here, L: Wheelbase LF; Distance between the front axle and the center of gravity LR: Distance between the rear axle and the center of gravity M: Vehicle weight. In addition, in actual calculation, (2L-LR)/(M
Since LF) is a constant, 1KR-
KR can be determined by a simple calculation such as "kvp".

The reason why the above formula (3) holds true will be described below.

Generally, the lateral speed Vy during steady turning motion is expressed as a transfer function to the known steering angle θ8 as follows.

However, a −I12 b −2/V(M(KyLy” 1KRLR)+Iz
(KF+Kn))C=4KFKRL/V-2
M (KFLF -KRLR) d-2KF engineering.

e = 4KFKR (LF + LR)/V -2Ky
LyMV, and N steering gear ratio I2: ljt moment S nila plus operator.

Here, let S → 0, It is.

Therefore, if we find the condition for Vy-0 from equation (6), we get
From the numerator -○ of equation (5), if KR is found from this equation (6), the above equation (8) is obtained.O Once the rear wheel cornering power KR is found in this way, next in step 98, the stability 7 actor estimated value A is read, and in the next step 94, a calculation is performed to obtain the front wheel cornering power KF using this value and the KR. This calculation is performed according to the following formula.

Note that the reason why K2S and KX are used instead of KF and KR in steps 92 and 94 is to simplify intermediate calculations. Therefore, K2S and KF, or K
For conversion between R and KR, the calculation time can be shortened by storing the calculation value in advance as a data table and determining the conversion value by table lookup processing.

Front wheel cornering power determined as above
The WK cornering power KR after Ky is the specific vehicle speed v.
Since it was obtained by a simple four-uIl calculation using the detected value of p, it is a value that matches the actual front wheel cornering power and rear wheel cornering power, and although indirectly, it I can say that.

Then, in step 95, the front wheel cornering power obtained in steps 92 and 94 is applied to the front wheel cornering power, and the rear wheel) + I
Output to the specified memory area. This memory area is an area read out in step 62 of the exercise state JIt estimation process described above.

That is, through the process of step 62, the parameters of the vehicle model are identified (the objects of identification are the front wheel cornering power and the rear wheel cornering power).

Therefore, interlocking letter 7L? k< The motion state quantity estimated by the estimation process is determined by the luck of the vehicle model so that it always matches the motion and characteristics of the actual vehicle through parameter identification of the vehicle model. Since the II characteristic is corrected, the estimated value becomes more accurate. In addition, the calculation burden on the microcomputer is light, and this can be used for other controls.

The device of this embodiment can be used to control various types of vehicles as a device for determining a plurality of motion state quantities.

For example, the applicant of the present application previously applied for Japanese Patent Application No. 59-18815.
It can be applied to the vehicle steering angle control device proposed in No. 3, Japanese Patent Application No. 59-188154, etc.

Further, the cornering power detection device of the present invention is widely applicable to devices that perform vehicle control using detected values of cornering power, as well as devices that can be used for parameter identification of vehicle models as in the above embodiments. Needless to say. For example, in addition to the embodiments described above, it is also possible to obtain the road surface friction coefficient from the detected value of cornering power and use it for controlling the brakes and drive system.

(Effects of the Invention) As explained in detail above, the present invention detects a specific vehicle speed when the lateral speed becomes zero during steady turning motion of the vehicle, and calculates the vehicle speed based on the detected specific vehicle speed. By determining the cornering power, it is possible to accurately detect the cornering power of the vehicle using an existing sensor with a relatively easy and simple configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the present invention; FIG. 2 is a block diagram of an embodiment of the present invention; FIGS. 3 to 7 are flowcharts showing processing executed in the arithmetic processing device a in FIG. 2; FIG. 8 is a characteristic diagram showing the relationship between lateral speed and specific vehicle speed. 100... Steady turning detection means 101... Lateral speed detection means 102... Specific vehicle speed detection means 108... Cornering power calculation means 1... Arithmetic processing bag Pft2... Steering angle sensor 3...・Vehicle speed sensor 6, 7...Lateral acceleration sensor 8・-H-ray)
Sensor 9... Lateral speed sensor Vy '' Lateral speed detected value α, αR... Lateral acceleration detected value 9... Yaw rate detected value θS... Steering angle detected value V... Vehicle speed detected value ψ ...Yaw angular acceleration detected value vp...Specific vehicle speed A...Stability factor estimated value Ky...Front wheel cornering power (detected value) KR...
・Rear wheel cornering power (detected value) Patent applicant Nissan Motor Co., Ltd. Figure 3 Figure 6

Claims (1)

[Claims] 1. Steady turning detection means for detecting that the vehicle is in a steady turning motion; and direct or direct detection of the lateral speed of the vehicle when the steady turning detection means detects that the vehicle is in a steady turning motion lateral speed detection means that indirectly detects; specific vehicle speed detection means that detects a specific vehicle speed when the lateral velocity detected during the steady turning motion becomes zero; and based on the detected value of the specific vehicle speed. 1. A cornering power detection device comprising: cornering power calculation means for calculating the cornering power of a vehicle.