JPH0615339B2 - Vehicle motion status calculator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention estimates a vehicle motion state from a steering wheel steering angle and a vehicle speed by a previously assumed vehicle model, and feeds back a measurable amount of motion state. Therefore, the present invention relates to a vehicle motion state quantity computing device that improves the accuracy of the estimated value or the control performed based on the estimated value.

(Prior Art) Conventionally, as a device for detecting a motion state quantity of a vehicle, only a device such as a yaw rate sensor or a lateral acceleration sensor for detecting an easily-measured motion state quantity has been realized or proposed.

(Problems to be Solved by the Invention) However, with the recent improvement in electronic control technology for vehicles, it has become necessary to detect a wide variety of motion state quantities, but Many of them are difficult to measure, and these sensing devices have not been realized. Further, if one sensing device is provided for one motion state quantity, the number of sensing devices becomes large when various motion state quantities are required, which may make it difficult to mount on the vehicle.

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

The motion state quantity estimating unit 104 calculates the steering angle θ _{S of the} steering wheel and the vehicle speed detected by the steering wheel steering angle detecting unit 100 by calculation based on at least one vehicle model set in advance based on the vehicle specifications and the equation of motion. The motion state quantity corresponding to the vehicle speed V detected by the detection means 101 is estimated.

The motion state quantity actual value detection means 102 detects at least one actual value of the vehicle motion state quantity.

The filter means 103 is the motion state quantity actual value detection means 10
The noise component contained in the actual value M of the vehicle motion state amount detected in 2 is removed.

The delay means 105 estimates the motion state quantity related to the same vehicle motion as the motion state quantity actual value detection means 102 among the motion state quantity estimated values obtained by the motion state quantity estimation means 104. Is delayed for a predetermined time and then output.

The comparison means 106 compares the actual value M ^* of the motion state after the noise component is removed by the filter means 103 with the estimated value ^{* of the} motion state output through the delay means.

The vehicle specification correction means 107 corrects the vehicle specifications in the luck / multi-state quantity estimation means 104 in accordance with the comparison result by the comparison means 106.

(Operation) The motion state quantity estimating means 104 estimates the motion state quantity from a preset vehicle model. This is because it is possible to obtain an exercise state quantity that is difficult to measure by obtaining the required exercise state quantity by estimation. Therefore, the motion state quantity estimating means 104 has the same effect as that provided with a plurality of sensing devices for a single motion state quantity.

Further, in order to improve the accuracy of the estimated value of the motion state quantity or the control based on the estimated value, the motion state quantity actual value detection means 102 detects at least one of the actual values of the vehicle motion state quantity to perform feedback control. ing.

Further, when the actual value of the motion state amount is detected, a noise component caused by the swing or vibration of the vehicle is superimposed on the detected value. Therefore, the filter unit 103 should remove this noise component. ing.

Here, since the output of the filter means 103 is delayed due to its transfer characteristic, if only the filter means 103 is provided, a time difference occurs when comparing the actual value and the estimated value of the motion state in the comparison means 106. A correct comparison cannot be made.

This is specifically shown in FIG. The motion state quantity actual value M detected by the motion state quantity actual value detecting means 102 includes a noise component, and the noise component is removed by the filter means 103, but the motion state passing through the filter means 103 is removed. The actual quantity M ^* is delayed by the predetermined time d.

Therefore, M ^* is delayed by d even with respect to the motion state estimated value obtained by the motion state amount estimating means 104.

Therefore, the present invention, together with the filter means 103,
The delay means 105 is provided so that the motion state quantity estimated value is also delayed by the predetermined time d so that ^* and M ^* coincide with each other in terms of time.

(Embodiment) The configuration of an embodiment of the present invention is shown in FIG.

The arithmetic processing unit 1 is configured by a microcomputer or other electric circuit, and is shown by a functional block in the figure for ease of explanation.

Vehicle on which the device of this embodiment is installed (hereinafter referred to as "own vehicle")
The yaw rate generated in the vehicle 20 near the vehicle body weight center position of 20 A yaw rate sensor 8 for detecting the lateral acceleration, and a lateral acceleration sensor 6 for detecting the lateral acceleration α occurring in the vehicle are attached.
Further, another lateral acceleration sensor 7 is arranged at a predetermined distance l from the lateral acceleration sensor 6 in the front-rear direction of the vehicle body.

The steering wheel steering angle sensor 2 detects a steering angle θ _S of a steering wheel (not shown), and the vehicle speed sensor 3 detects a vehicle speed V of the vehicle 20.

Low-pass filters 9A to 9C are connected to the output stages of the two lateral accelerations 6 and 7 and the yaw rate sensor 8, respectively. Lateral acceleration α ^* after being waved by these low-pass filters 9A to 9C, α _R ^* and yaw rate Is input to the arithmetic processing unit 1.

The low-pass filters 9A to 9C are the actual lateral acceleration values α, α _R detected by the lateral acceleration sensors 6 and 7, and the actual yaw rate value detected by the yaw rate sensor 8. The noise components due to vehicle body vibration and the like included in are removed.

Therefore, the cutoff frequency of the low-pass filters 9A to 9C is set to, for example, about 5 Hz. Then, the transfer characteristic K ₁ of the low-pass filters 9A to 9C is (However, S is a Laplace operator), and a and b are Then, a = 2Q · 2πf = 44.43, b = (2πf) ² = 986.
96.

The arithmetic processing device 1 is classified by function, and includes a steady turning motion determination unit 11, a steady yaw rate detection unit 12, a sideslip angle detection unit 13, a motion state amount estimation unit 14, and two comparison units 15 and 16. It is divided into two correction units 17 and 18, and two filtering units (delay means) 19A and 19B.

The steady turning motion determination unit 11 includes two acceleration sensors 6, 7
In is detected, the low-pass filter 9A, the lateral acceleration actual value alpha ^* which are waves ^9C, and alpha _R ^*, yaw rate sensor 8
The actual yaw rate detected by the low-pass filter 9B , And the vehicle speed V detected by the vehicle speed sensor 3, it is determined whether the vehicle 20 is in a steady turning motion,
When it is determined that the vehicle is in the steady turning motion, the information F indicating that fact is generated.

The steady-state yaw rate detection unit 12 determines the yaw rate (hereinafter, “steady-state yaw rate”) during steady-state turning motion of the vehicle. The actual yaw rate detected by the yaw rate sensor 8 and waved by the low-pass filter 9B when the information F is generated. Steady yaw rate Output as.

The side slip angle detection unit 13 obtains the side slip angle generated in the vehicle, and includes the lateral acceleration α ^* after the wave and the yaw rate. , And the side slip angle β ^* is indirectly detected by a predetermined calculation using the vehicle speed V. The sideslip angle β ^* obtained here is In the same manner as, it becomes delayed with respect to the actual sideslip angle β.

The motion state quantity estimation unit 14 calculates the steering angle of the steering wheel (hereinafter referred to as “steering wheel steering angle” based on a calculation relating to a preset vehicle model (which is a simulation model of vehicle motion set by vehicle specifications and a motion equation)). "Handle steering angle"
Abbreviated as) and theta _S, obtains an estimate of the motion state quantity corresponding to the vehicle speed V.

The estimated value of this state of motion is the estimated value of the yaw rate. In addition to the estimated value of the skid angle and the side slip angle, the required amount of motion state such as the yaw angular acceleration, the tire cornering force, or the roll angle is estimated.

The filtering units 19A and 19B are the yaw rate estimated values calculated by the motion state quantity estimating unit 14. And the side slip angle estimated value are filtered by the same transfer characteristics as the transfer characteristics K of the low-pass filters 9A to 9C, respectively. Therefore, the yaw rate estimated values generated from these filtering units 19A and 19B And the estimated slip angle ^* And the lateral acceleration α ^* or yaw rate after the wave Will be delayed by the same amount of time as.

The comparison unit 15 determines the steady yaw rate. And the yaw rate estimated value delayed by the filtering unit 19A. And the comparison unit 16 uses the steady yaw rate. To the skid angle detection value β ^* And yaw rate estimate after filtering And the estimated slip angle ^* It is to compare the size with.

FIGS. 4 to 7 show the arithmetic processing device 1 when the arithmetic processing device 1 is configured by using a microcomputer.
It is a flow chart which shows the processing performed by.

The steady turning motion determination process shown in FIG. 4 has the same function as the steady turning motion determination unit 11 in FIG.

That is, the lateral acceleration α ^* and the yaw rate after the wave input through the low-pass filters 9A to 9C (and further converted into a digital amount by the A / D converter). Then, based on the vehicle speed V from the vehicle speed sensor 3, it is determined whether or not the vehicle is in a steady turning motion (step 2).
Then, when it is determined that the steady turning motion is being performed, the normal flag F is set (step 213) and the fact is stored. If the steady turning motion is not being performed, the steady flag F is reset (step 214).

The motion state quantity detection process shown in FIG. 5 has the same functions as the steady yaw rate detection unit 12 and the sideslip angle detection unit 13 in FIG.

In the processing of step 221, the lateral acceleration α ^* after wave and the yaw rate are , And the vehicle speed V are read, and it is determined in the next step 222 whether or not the steady state flag F is set.

If the determination in step 222 is YES, it means that the vehicle at that time is in a steady turning motion. Therefore, the yaw rate actual value detected at this time is Is the steady-state yaw rate, and therefore, Steady yaw rate The latest is stored as (step 233). Step 22
If the determination of 2 is NO, the steady yaw rate Is not updated.

In the processing of step 224, Is used to determine the sideslip angle β ^* .

this is, It is calculated by The sideslip angle β ^* obtained by this calculation is the same as the α ^* or the sideslip angle β actually generated in the vehicle 20. It has the same delay time as the delay time of. This is proved as follows.

In the equation (2), input The transfer characteristics when (However, S is a plus operator).

Here, from the equation (1), Therefore, by substituting equations (4) and (5) into equation (3), Becomes here, Therefore, equation (6) is Therefore, β ^* becomes equal to the output after the actual side slip angle β is waved by the low-pass filter having the same transfer characteristic as the low-pass filters 9A to 9C.

The motion state quantity estimating process shown in FIG. 6 is performed by the motion state quantity estimating unit 14 and the filtering units 19A and 19B shown in FIG.
It has the same function as.

That is, the motion state quantity corresponding to the steering wheel steering angle θ _S and the vehicle speed V is obtained from the calculation relating to the preset vehicle model.

The vehicle model is a simulation model set by the vehicle specifications of the own vehicle and the equation of motion, and corresponds to θ _S and V by giving the steering wheel steering angle θ _S and the vehicle speed V as variables. You can estimate the amount of exercise.

The estimated value of the above-mentioned motion state quantity is the estimated value of the yaw rate. And the estimate of the sideslip angle are included (step 23
3).

Also, in order to improve the accuracy of the estimated value of the motion state quantity,
The front wheel cornering power K _F and the rear wheel cornering power K _R corrected by the comparison / correction processing described later are used as the vehicle specifications of the vehicle model (step 232).

Then, in the processing of step 234, the yaw rate estimated value of the motion state quantity obtained in step 233 is calculated. And filtering processing of the estimated side slip angle value.

This filtering process is performed by the low-pass filter 9A.
By performing filtering with the same transfer characteristic as the transfer characteristic K of 9C, And α ^* or A value with the same delay time as the delay time of And

these Is calculated according to the following calculation.

The integral calculation in the above equations (8) and (9) is performed by using the rectangular integration method or the like.

The comparison / correction process shown in FIG. 7 is performed by the comparison unit 1 in FIG.
5, 16 and the correction units 17, 18. This processing is executed when the vehicle is in the steady turning motion, that is, when the steady flag F is set (step 241).

The processing of Steps 242 to 245 corrects an error between the motion characteristic during the steady turning motion of the vehicle model used for obtaining the motion state estimated value (hereinafter referred to as "steady motion characteristic") and the actual steady motion characteristic. It is a process to do.

All inputs used in this process are post-wave or post-filtering values, that is, actual post-wave steady-state yaw rate values. And the actual sideslip angle (which was mentioned earlier as being equivalent to the wave value) β ^* , and the yaw rate estimate after filtering. And the estimated side slip angle ^* , and in the following explanation, the steady-state yaw rate actual value is simply , Actual sideslip angle β ^* , estimated yaw rate , Lateral slip angle estimated value ^* is abbreviated.

In general, the problem at the time of steady turning motion is steady US-
It is an OS characteristic (US means understeer, OS means oversteer), and if the steady-state US-OS characteristic is different between the actual characteristic and the characteristic held by the vehicle model, a difference in the yaw rate value occurs.

Accordingly, in the processing of step 242, the steady yaw rate actual value is And yaw rate estimate The match of When If there is a certain value or more, the steady-state US of the vehicle model
-The front and rear wheel yaw ringing powers K _F and K _R are performed so that the OS characteristics match the actual characteristics.

When it is, it is determined that the front wheels are slipping outward during turning, and the front wheel cornering power K _F is increased by a predetermined amount ΔK and the rear wheel cornering power K _R is decreased by a predetermined amount ΔK (steps 243 and 244). . As a result, the steady-state US-OS characteristic of the vehicle model is corrected in the oversteer direction, and approaches the actual characteristic.

Also, At the time of turning, it is determined that the rear wheels are slipping outward during turning, the rear wheel cornering power K _R is increased by a predetermined amount ΔK, and the front wheel cornering power K _F is decreased by a predetermined amount ΔK (steps 243, 245). ). As a result, the steady US-OS characteristic of the vehicle model is corrected in the understeer direction, and approaches the actual characteristic.

The reason why the steady US-OS characteristic can be adjusted by increasing or decreasing the front and rear wheel cornering powers K _F and K _R in this way will be described below.

Yaw rate during steady turning motion Is It is represented by. Here, L: wheel base N: steering gear ratio A: stapler actor, and further, stapler actor A is It is represented by. However, M: vehicle mass L _F : distance between the front axle and the center of gravity _LR : distance between the rear axle and the center of gravity

Therefore, among the numerator (L _F K _F −L _R K _R ) of the above formula (11), K _F
Is set to be large or K _R is made small, the yaw rate gain becomes large, and the steady US-OS characteristic shifts to the oversteer side. Conversely, if K _F is made small or K _R is made large, Move to understeer side.

The processes of steps 246 to 249 are the motion characteristics (hereinafter referred to as “transient characteristics”) of the vehicle model during the transient motion (the state in which the vehicle moves from the straight-ahead state to the turning motion and reaches the steady turning motion).
And) of the actual transient characteristics.

By the processing of steps 242 to 245, even if the steady motion characteristics of the vehicle model are corrected to match the actual characteristics, the transient characteristics cannot be corrected. This is US
The -OS characteristic is determined by the ratio of K _F and K _R , as can be seen from the above formula (11), and is not affected by their magnitude.

Therefore, in order to match the transient characteristics of the vehicle model with the actual characteristics, the actual side slip angle β is compared with the estimated side slip angle, and the front and rear wheel cornering powers are corrected so that they match. To do.

In general, the sideslip angle β _S during steady turning motion is It is represented by. Where β _S / And ask Becomes From this equation (13), the magnitude of K _R It turns out that is decided.

Therefore, When If does not match (when the determination in step 246 is NO), If so, the rear wheel cornering power K _R is reduced by a predetermined amount ΔK _R , and the front wheel cornering power K _F is also reduced by a predetermined amount ΔK _F (steps 247, 24).
8). Also, If so, the rear wheel cornering power K _R is increased by a predetermined amount ΔK _R , and the front wheel cornering power K _F is also increased by a predetermined amount ΔK _F.

Thereby, the transient characteristic of the vehicle model is corrected so as to approach the actual characteristic. Further, by performing the increase and decrease of the front wheel cornering power K _F in accordance with the increase or decrease of the rear wheel cornering power K _F, K _F and K the ratio of _R so as not to change the constant U, which is corrected by the processing of step 242 to 245
The transient characteristic can be corrected while maintaining the S-OS characteristic.

Through the above-described processing, the apparatus of the present embodiment detects a plurality of steering wheel steering angles θ _S and two variables of the vehicle speed V, and thereby a plurality of motion state quantities are calculated by a calculation relating to the vehicle model of the own vehicle set in advance. Can be estimated, and it has a function equivalent to detecting the motion state quantity of the own vehicle by a plurality of sensors.

Also, the yaw rate is relatively easy to measure. And lateral acceleration α, α _R are detected, and the steady yaw rate is detected. By calculating the sideslip angle β and feeding back, both the steady motion characteristics and the transient motion characteristics of the vehicle model are corrected to match the actual characteristics, and the accuracy of the estimated value of the motion state quantity is Can be improved.

Further, the low-pass filters 9A to 9C remove noise components contained in the lateral acceleration detection signal and the yaw rate detection signal, whereby the actual values of the lateral acceleration and the yaw rate can be detected with high accuracy.

In addition, by delaying the yaw rate estimated value and the side slip angle estimated value to be compared with each other in accordance with the actual values of the lateral acceleration and the yaw rate and the lateral slip that have been delayed by the low-pass filters 9A to 9C, It is possible to avoid the occurrence of an error in the correction of the motion characteristics of the vehicle model.

In the above embodiment, the steady state yaw rate is used as the actual value of the motion state quantity used for the feedback. However, other motion state quantities may be used.
Like the device of the present invention proposed by No. 60-50553,
The actual values of the yaw rate and the yaw angular acceleration may be feedback-controlled.

Further, the present invention can be used for controlling various vehicles as a device for obtaining a plurality of motion state quantities.

For example, it can be used as a measuring instrument for the tire equivalent cornering power of front and rear wheels due to a change in road surface condition. Further, since there is a strong correlation between the road surface friction coefficient and the tire cornering power, the road surface friction coefficient should be obtained from the cornering power of the vehicle model determined by the device of the present invention and used for controlling the brake and the drive system. Is also possible.

Furthermore, the applicant of the present invention has previously proposed the vehicle steering angle control device proposed in Japanese Patent Application No. 59-188153, Japanese Patent Application No. 59-188154, etc.
The present invention can be applied.

That is, the vehicle steering angle control device described above sets in advance a vehicle model having a target motion performance (this is set as a “target vehicle model” and a vehicle model of the own vehicle, and motion based on the target vehicle model is performed. The state quantity is estimated, and the wheel steering angle required to realize this estimated value in the vehicle is estimated based on the vehicle model of the vehicle. It controls the wheel steering angle, and by such control, the exercise performance of the host vehicle is made equal to the target exercise performance.

Therefore, if the present invention is introduced into the portion for estimating the wheel steering angle, a more accurate estimated value of the wheel steering angle can be obtained,
In both the steady turning motion and the transient motion, the accuracy of achieving the target motion performance is improved.

In this embodiment, the filtering means is used as the delay means, but the invention is not limited to this, and the delay time may be controlled by a timer or the like.

(Effects of the Invention) As described in detail above, according to the present invention, a plurality of vehicle motion state quantities are estimated from the measured values of the steering angle of the steering wheel and the escape speed by the calculation related to the preset vehicle model. Can be asked for.

Therefore, it is possible to obtain a motion state quantity that is difficult to measure, and it has a function equivalent to having a plurality of sensing devices for a single motion state quantity.

Further, by appropriately selecting the vehicle model to be set, the estimated motion state quantity is different from the actual motion state quantity of the vehicle, for example, a vehicle model having ideal motion characteristics is set, and the vehicle motion is set. It can also be used for control.

Then, by detecting a motion state quantity that is easy to measure and feeding back, the motion characteristics of the vehicle model can be corrected to match the actual characteristics, and the estimated value of the motion state quantity The accuracy can be improved.

Furthermore, by removing the noise component contained in the above-mentioned feedback-backed motion state quantity by the filter means,
By increasing the accuracy of the feedback amount and delaying the motion state quantity estimated value to be compared with this feedback amount according to the delay time of the feedback amount, the time between the actual value and the estimated value of the movement amount to be compared It is possible to prevent the occurrence of an error in the correction of the motion characteristics of the vehicle model.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the present invention, and FIG. 3 is a diagram showing a partial functional block diagram of the configuration of an embodiment of the present invention. FIG. 7 to FIG. 7 are flow charts showing the processing executed by the arithmetic processing unit in FIG. 100 ...... Steering wheel steering angle detection means 101 ...... Vehicle speed detection means 102 ...... Motion state amount actual value detection means 103 ...... Filter means 104 ...... Motion state amount estimation means 105 ...... Delay means 106 ・ ・ ・ Comparison means 107 ・ ・ ・… Vehicle specification correction means 1… Arithmetic processing unit 2 …… Steering wheel steering angle sensor 3 …… Vehicle speed sensor, 6,7 …… Lateral acceleration sensor 8 …… Yaw rate sensor 9A-9C …… Low pass filter 19A, 19B …… Filtering section 20 …… Vehicle, θ _S …… Steering wheel steering angle V …… Vehicle speed, α, α _R …… Lateral acceleration ...... Yaw rate, ...... steady yaw rate β ...... slip angle K _F ...... front wheel cornering off Orth K _R ...... rear wheel cornering off Orth …… Estimated yaw rate …… Estimated side slip angle

Continuation of front page (56) Reference JP-A-60-148770 (JP, A) JP-A-57-60974 (JP, A) JP-A-60-4466 (JP, A) JP-A-50-14028 (JP , A) JP 59-23775 (JP, A) JP 60-71370 (JP, A) JP 60-92978 (JP, A)

Claims (2)

[Claims] 1. A steering wheel steering angle detecting means for detecting a steering angle of a steering wheel, a vehicle speed detecting means for detecting a vehicle speed, and a motion state amount actual value detecting means for detecting at least one actual value of a vehicle motion state amount. Filter means for removing noise components contained in the actual motion state quantity detected by the actual motion quantity detection means, and calculation based on at least one vehicle model preset by vehicle specifications and equations of motion And a motion state quantity estimating means for estimating a motion state quantity corresponding to the steering wheel steering angle and the vehicle speed, and the motion state quantity actual value detection of the motion state quantity estimated value obtained by the motion state quantity estimating means. Delay means for delaying and outputting an estimated value of the motion state quantity related to the same vehicle movement detected by the means for a predetermined time; Comparing means for comparing the motion state quantity actual value after the noise component has been removed by the filter means with the motion state quantity estimated value output through the delay means, and corresponding to the comparison result by the comparison means. A vehicle motion state quantity computing device, comprising: vehicle specification correction means for correcting the vehicle specifications in the motion state quantity estimation means. 2. The vehicle motion state quantity computing device according to claim 1, wherein the delay means is an estimated value filtering means for performing filtering with the same transfer characteristic as the filter means.