JPH11192959A - Kinetic condition quantity estimating device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a kinetic condition quantity estimation device wherein an estimated value of a kinetic condition quantity can be coincided with an actual true value, in no relation to a delay of change of the kinetic condition quantity relating to steering. SOLUTION: To an observer with a yaw rate γ as a reference input, a detection value of car speed Vx , steering angle θ, yaw rate γ, and a road surface μ, is given, in the case of obtaining a yaw rate estimation value γH and side slip angle estimation value βH, a delay deviation γe between the yaw rate estimation value γB via a matrix C and a yaw rate detection value γ is returned by a gain K to a preceding step of an integrator 1/S, this γe , θ, Vx and a vehicle model A are used, the estimation value γH and βH are obtained. In the case of calculating the delay deviation γe , delaying by a waste time (lengthened in accordance with decreasing a road surface friction coefficient μ) exp(-ls) of a yaw rate relating to steering, the estimation value γH is fed, this delayed estimation value γH is further delayed by a time corresponding to a dynamic characteristic Gγ(s) of the yaw rate sensor, to be made to contribute to calculation of the deviation γe .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating a vehicle motion state quantity which is difficult to directly detect, such as a side slip angle and a lateral speed of a vehicle.

[0002]

2. Description of the Related Art A vehicle steering angle control device and a stability control device directly detect a vehicle motion state quantity such as a yaw rate, which can be easily detected. The vehicle motion state quantity, such as the vehicle motion state quantity, is estimated using the easily detected vehicle motion state quantity, the steering angle and the vehicle speed, and the detected and estimated vehicle motion state quantity is used as control information. Requires a quantity estimator.

[0003] As a device for estimating the motion state quantity of a vehicle, for example, Japanese Patent Application Laid-Open No. 2-45802 and Japanese Patent Application Laid-Open No.
There is one described in JP-A-5650. The conventional device described in the former publication detects a wheel steering angle and a yaw angular acceleration of a vehicle, and uses an observer method based on a vehicle equation of motion using the detected steering angle and yaw angular acceleration to obtain a yaw rate and a lateral acceleration of the vehicle. Is estimated.

The conventional vehicle motion state quantity estimating device described in the latter publication uses an observer method in which the wheel steering angle is used as an input variable, the sideslip angle and the yaw rate are used as state variables, and the yaw rate is used as a reference input. When estimating the side slip angle of the vehicle, when detecting the yaw rate as a reference input, the sensor noise included in the detection signal,
The characteristic of the filter for removing the drift component is added to the state equation of the observer, thereby increasing the estimation accuracy of the vehicle side slip angle.

[0005] The above-mentioned observer is generally constructed as shown in FIG. 5 when estimating the yaw rate (estimated value γ _H ) and the sideslip angle (estimated value β _H ). It is known that the output equation is expressed by the following equation (1), and the output equation is expressed by the following equation (2). (d / dt) X _H = (A−KC) X _H + Kγ + BU (1) Y _H = CX _H (2)

(Equation 1) Becomes

Here, considering the convergence of the observer, the set poles p ₁ and p ₂ are arbitrarily determined, and the gain matrix K of the observer is obtained. Then, k ₁ and k ₂ are as follows. ₁ = ｛p ₁ · p ₂ -a ₁₁ (a ₁₁ -p ₁ -p ₂ ) / a ₂₁ ｝ + a ₁₂ (5) k ₂ = a ₁₁ + a ₂₂ -p ₁ -p ₂ ... (6) The observer of FIG. 5 can be configured.

[0007]

However, in the conventional method of estimating the vehicle motion state quantity, the estimation is performed on the assumption that there is a change in the vehicle motion state quantity corresponding to the wheel steering immediately after the wheel steering. Had the following problems. That is, the vehicle is usually described with reference to FIG. 6 showing the yaw rate gain characteristic and the phase characteristic with respect to the steering frequency. Cause a change in the amount of exercise state.

Conventionally, the dead time has not been taken into account, so that the estimated value (the estimated yaw rate value γ _{H in} FIG. 5) is used for the reference input (actual yaw rate γ in FIG. 5).
Has an error, which causes a problem that the observer tends to be unstable particularly in a high steering frequency region.

As a result, the gain of the observer cannot be increased in the sense of avoiding the instability, and the estimated value cannot be immediately brought to the actual true value. Therefore, the case where the steering angle θ is made as shown in FIG. 7 in the range of ± 120 degrees during traveling at the vehicle speed V _x = 40 km / h will be described. The actual yaw rate true value γ shown by the solid line in FIG. The yaw rate estimated value γ _H , the lateral speed estimated value V _yH , and the estimated side slip angle β _H indicated by the broken line are different from the true lateral velocity V _y and the true side slip angle β in the transient period as indicated by the one-dot chain line. It is inevitable that the convergence of the estimated value to the true value deteriorates. Therefore, when the vehicle motion state quantity estimated by the conventional method is used for the stability control of the vehicle, the control becomes unstable or inaccurate, and the actual control effect cannot be achieved. .

According to the first aspect of the present invention, the feedback gain can be increased by making it possible to quickly match the estimated value of the vehicle motion state quantity including the transition period with the actual motion state quantity. Thus, an object of the present invention is to solve the above-mentioned problem.

A second aspect of the present invention is to achieve the object of the first aspect more reliably.

A third object of the present invention is to ensure that the object of the first invention can be achieved irrespective of the coefficient of road friction.

According to a fourth aspect of the present invention, the dynamic characteristic of the means for detecting the vehicle motion state quantity prior to obtaining the delay deviation between the estimated value of the vehicle motion state quantity and the actual true value is determined. Regardless, the object of the first invention is to be achieved reliably.

A fifth aspect of the present invention provides a vehicle motion state quantity estimating apparatus suitable for estimating a side slip angle as a vehicle motion state quantity using an observer.

[0015]

According to a first aspect of the present invention, there is provided an apparatus for estimating a motion state of a vehicle using a steering angle, a vehicle speed, and a detected value of a certain vehicle motion state. In a device for estimating a vehicle motion state quantity and another vehicle motion state quantity, a steering angle, a vehicle speed, a delay deviation between a detected value and an estimated value of the certain vehicle motion state quantity, and a vehicle model are calculated. The vehicle motion state quantity and the other vehicle motion state quantity are estimated, and the estimated value of the certain vehicle motion state quantity is delayed for a predetermined time to contribute to the calculation of the delay deviation. Is what you do.

According to a second aspect of the present invention, in the first aspect, the delay time of the certain vehicle motion state quantity with respect to wheel steering is measured in advance as a dead time, and the certain vehicle motion state quantity is estimated. The method is characterized in that the estimated value of the amount is delayed by a predetermined time corresponding to the dead time to contribute to the calculation of the delay deviation.

A third aspect of the present invention is directed to the vehicle motion state estimating apparatus according to the second aspect, wherein the dead time is increased as the road surface friction coefficient decreases.

According to a fourth aspect of the present invention, there is provided the vehicle motion state quantity estimating apparatus according to the second or third invention, wherein the estimated value of the certain vehicle motion state quantity delayed by the dead time is replaced with the certain vehicle motion state quantity. The present invention is characterized in that it is configured to further delay by a time corresponding to the dynamic characteristic of the vehicle motion state amount detection means used for the detection and to contribute to the calculation of the delay deviation.

According to a fifth aspect of the present invention, there is provided the vehicle motion state quantity estimation device according to any one of the first to fourth inventions, wherein the certain vehicle motion state quantity is a yaw rate of the vehicle, and the other vehicle motion state quantity. , An observer using the vehicle's side slip angle as a state variable and a yaw rate as a reference input is configured, and the side slip angle of the vehicle is estimated using the observer.

[0020]

According to the first aspect of the invention, when a certain vehicle motion state quantity and another vehicle motion state quantity are estimated using a steering angle, a vehicle speed, and a certain vehicle motion state quantity detection value. Estimating the certain vehicle motion state quantity and the other vehicle motion state quantity using the steering angle, the vehicle speed, the delay deviation between the detected value and the estimated value of the certain vehicle motion state quantity, and the vehicle model. In addition, since the estimation value of the certain vehicle motion state amount is delayed for a predetermined time to contribute to the calculation of the delay deviation, it is concluded that the vehicle actually produces a corresponding behavior change with a delay of dead time from steering. As a result, the estimated value of the vehicle motion state quantity can be made to better match the actual value.

Therefore, in the first invention, the above estimation does not become unstable even in a high steering frequency range, and the gain can be increased at the time of the estimation without worrying about this. Can be improved to the true value.

In the second invention, the delay time of the certain vehicle motion state amount with respect to wheel steering is measured in advance as a dead time, and the estimated value of the certain vehicle motion state amount is determined as a predetermined value corresponding to the dead time. Since the time is delayed by a time to contribute to the calculation of the delay deviation, the above-mentioned predetermined time is more matched to the actual situation in accordance with the delay time of the vehicle motion state quantity, and the object of the first invention is more reliably achieved. be able to.

In the third aspect of the present invention, since the above-mentioned dead time is increased as the road surface friction coefficient becomes lower, the delay of the vehicle motion state amount with respect to wheel steering becomes larger on a low μ road surface. The object of the first invention can be reliably achieved regardless of the coefficient.

In the fourth invention, the estimated value of the certain vehicle motion state amount delayed by the dead time corresponds to the dynamic characteristic of the vehicle motion state amount detection means used for detecting the certain vehicle motion state amount. Since the delay is further delayed by a time to contribute to the calculation of the delay deviation, the object of the first invention can be reliably achieved regardless of the dynamic characteristics of the vehicle motion state amount detecting means.

According to a fifth aspect of the present invention, there is provided an observer which uses the yaw rate of the vehicle as the certain vehicle motion state quantity, the vehicle side slip angle as the other vehicle motion state quantity, and the yaw rate as a reference input. Then, since the sideslip angle of the vehicle is estimated using the observer, the sideslip angle is estimated using the observer, and it is practical and
A suitable vehicle motion state amount estimation device can be constructed.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.
This will be described in detail based on FIG. FIG. 1 shows a vehicle according to the invention.
Exercise state amount estimation device is composed of microcomputer 10
In this case, a micro computer
The steering angle θ of the steering wheel
Signal from the steering angle sensor 11 _xDetect
A signal from the vehicle speed sensor 12, a yaw rate γ
-Signal from the rate sensor 13 and coefficient of road friction μ
Road surface sensor 14 (wiper that turns ON in rainy weather)
Signal from the switch).
Through the signal processing circuits 15-18. Each signal
The processing circuits 15 to 18 filter the inputted detection signals.
Filtering and digital conversion
It is assumed to be input to the computer 10.

Based on the input information, the microcomputer 10 uses the functional block diagram shown in FIG.
In accordance with the program, the slip angle and the yaw rate are estimated by the calculation described later in detail, and signals relating to the estimated slip angle β _H and the estimated yaw rate γ _H are converted into analog signals by D / A converters 19 and 20, respectively. Thereafter, the signals are amplified by the amplifiers 21 and 22 and output.

Here, the microcomputer 10 corresponds to FIG.
As shown in FIG. 6, the same-dimensional observer is functionally constructed, and the vehicle speed V _x and the steering angle θ (where the steering gear ratio is N, the front wheel steering angle δ _F is represented by δ _F = θ / N) The yaw rate γ and the side slip angle β are estimated as the motion state quantities of the vehicle to be determined (however, the rear wheel steering is not performed and the rear wheel steering angle δ _R is always 0). First, explaining the estimation theory, the as input variables and U 2, when the state variable and X _H, using the motion equation of the vehicle between them, the system matrix A which represents the vehicle model, the observation matrix B Therefore, it is known that there is a relationship of (d / dt) X _H = AX _H + BU (7).

Since the input variable U is the front wheel steering angle δ _F and the state variables X _H are the sideslip angle β and the yaw rate γ, the vehicle motion state equation is expressed by the following equation.

(Equation 2) Here, each element of the system matrix and each element of the observation matrix are as follows.

(Equation 3)

(Equation 4) M: vehicle mass Iz: yaw moment of inertia K _F : front-wheel equivalent cornering power K _R : rear-wheel equivalent cornering power L _F : distance from vehicle center of gravity to front wheel axle L _R : distance from vehicle center of gravity to rear wheel axle

Therefore, based on the state equation of the above equation (7), an observer is set up using the yaw rate γ as a state variable (reference input) that can be observed, and the vehicle parameters are set as known constants measured in advance, and the vehicle speed is set. V _x , steering angle θ (front wheel steering angle δ
_{If F} ) and the yaw rate γ are detected and given, the estimated yaw rate γ _H and the estimated side slip angle β _H can be obtained using the above-described observer.

In this embodiment, the delay deviation γ _e between the estimated yaw rate value γ _H via the observation matrix C and the actual detected yaw rate value γ is represented by the feedback gain K and the integrator 1 / s of the back to front, and thereby the steering angle [delta] _F, and the vehicle speed V _x and the yaw rate delay deviation gamma _e above, by using the vehicle model a, the yaw rate estimated value gamma _H and sideslip angle estimates beta _H I will ask for it.

Incidentally, in the present embodiment, when calculating the yaw rate delay deviation γ _e , the estimated yaw rate γ _H is not directly used for the calculation.
As described above, the dead time exp (-ls) corresponding to the yaw rate generation delay time Δt for the wheel steering is measured in advance, and the yaw rate estimated value γ _H is transmitted with a delay by the dead time exp (-ls). Then, the delayed yaw rate estimated value γ _H is passed through a filter corresponding to the dynamic characteristic Gγ (s) of the yaw rate sensor 13 (see FIG. 1), and further delayed by the time corresponding to the dynamic characteristic Gγ (s). This contributes to the calculation of the yaw rate delay deviation γ _e .

In this embodiment, the dead time correcting section corrects the dead time exp (-ls) so as to be longer as the road friction coefficient μ becomes smaller. The reason is,
This is because, as the road surface friction coefficient μ decreases, deformation of the wheel tires hardly occurs. As a result, as the road surface friction coefficient μ decreases, the delay time of the yaw rate generation with respect to wheel steering increases.

In the present embodiment having the above-described configuration, the motion state equation is represented by the following equation with a system for feeding back the yaw rate delay deviation γ _e with the gain K added to the equation (7). (d / dt) X _H = AX _H -K [γ _H · exp (-ls) · Gγ (s) -γ] + BU (11)

That is, in the present embodiment, the microcomputer 10 (see FIG. 1)
_H is delayed by a dead time exp (-ls) corrected so as to become longer as the road surface friction coefficient μ decreases, and the delayed yaw rate estimation value γ _H is calculated as the dynamic characteristic Gγ (s) Is further delayed by a time corresponding to the above, and is compared with the yaw rate detection value γ. Then, a yaw rate delay deviation γ _e between the estimated yaw rate value γ _H and the detected yaw rate value γ is calculated, and this is fed back with a gain K to obtain an estimated yaw rate value γ _H and an estimated side slip angle value β _H. Note that the matrices A, B, and K represent the vehicle speed V
Needless to say, it is stored in a memory as a function of _x and read out and used when necessary.

Therefore, even if there is a dead time exp (-ls) from the wheel steering to the change of the vehicle motion state quantity, and even if this dead time changes according to the road surface friction coefficient μ, The yaw rate detection value γ is the yaw rate sensor 13
7 may be delayed due to the dynamic characteristic Gγ (s) of FIG.
As is clear from the simulation result of FIG. 4 performed under the same conditions as in FIG. 4, the estimated yaw rate value γ _H can be constantly made to substantially match the actual detected value γ, and the estimated yaw rate value V _yH and the vehicle speed V _x ( V _yH / V _x ) is also calculated as the actual slip angle estimated value β _H
Can be almost matched.

Although the functions performed by the microcomputer 10 are shown in FIG. 2 as a block diagram for convenience, it is actually a control program as shown in FIG. 3 which is executed by a periodic interruption every predetermined time ΔT. The flowchart will be described below. In step 31, the steering angle θ and the vehicle speed V
_x , yaw rate γ, and road friction coefficient μ,
These are used as the current detected steering angle θ (i) and the detected vehicle speed V _x
(I), the yaw rate detection value γ (i), and the road surface friction coefficient detection value μ (i) are stored in the memory.

Next, at step 32, the input variable U
(I) is substituted for the detected steering angle θ (i),
Rate estimate γ_HAccording to the road friction coefficient detection value μ (i).
Delay by exp (-ls)
Calculated value γ of the estimated yaw rate value_H(I-
n) is the dynamic characteristic G of the yaw rate sensor 13 (see FIG. 1).
γ obtained by further delaying by the time corresponding to γ (s)
_H(In) · Gγ (s), the detected yaw rate value γ
(I), that is, the yaw rate delay deviation γ
_e(I) is calculated.

Next, at step 33, the detected vehicle speed V
_x The A matrix in accordance with (i) prepared by reference to Table 1, in step 34, the B matrix corresponding to the vehicle speed detection value V _x (i) prepared by reference to Table 2, in step 35, the vehicle speed detection A K matrix corresponding to the value V _x (i) is created by referring to Table 3.

In the next step 36, an observer matrix (d / dt) X _H (i) = AX _H (i−1) −Kγ _e (i) + BU (i) based on the above equation (11) is created. At this time, the state variable vector _XH is calculated in the previous calculation cycle, that is, (i−
1) Use the calculated value X _H (i-1) for the first time. Where X _H
Is a state variable vector including the estimated sideslip angle value β _H and the estimated yaw rate value γ _H. Further, in step 37,
By performing the operation of the above equation (11), the state variable vector X
Differential value of _H (i) the _{(d / dt) X H (} i) determined.

In step 38, the differential value (d / dt) X _H (i) of the state variable vector calculated in step 37 is integrated. X _H (i) = ∫ (d / dt) X _H (i) · The calculation of dt (12) is performed to calculate the estimated value X _H (i) of the state variable composed of the current estimated slip angle β _H (i) and the estimated yaw rate γ _H (i). Specifically, one operation cycle ΔT
Using previous the (i-1) times the estimated value at the first X _H (i-1), the estimated value X _H of this i-th operation _{(i) = X H (i} -1) + ΔT · (d / dt ) X _H (i) Calculated from the equation (13).

In step 39, the current state variable estimated value X _H (i) is converted to X _H (i-1) for the next calculation.
To update, but to retard yaw rate estimated value gamma _H a (i) a predetermined time of the state variable estimates X _H (i) in the present embodiment, stores gamma _H (i) to the memory. Then, in step 40, a process of calculating γ _H (in) delayed by a predetermined time (ΔT · n) is performed, and the calculated value is stored in the memory. Finally, in step 41, the estimated state variable X _H (i), ie, the estimated slip angle β
_H (i) and a signal corresponding to the yaw rate estimated value γ _H (i) are converted into the D / A converters 19 and 20 and the amplifier 2 shown in FIG.
The data is sequentially output through 1 and 22.

Since the above processing is performed by the periodic interruption every predetermined time ΔT as described above, this calculation cycle Δ
By setting T appropriately, the estimated yaw rate γ
_The predetermined time for delaying _H (i) can be set freely, whereby the estimated yaw rate value γ _H (i) is changed to a dead time exp (−) from the wheel steering to the change in the vehicle motion state quantity.
ls), this dead time is also the coefficient of road friction μ
Even if the yaw rate detection value γ is further delayed by the dynamic characteristic Gγ (s) of the yaw rate sensor 13 as shown in the simulation result of FIG. ) Can be almost timed.

As a result, the estimated value of the sideslip angle β _H (i)
Also, as shown in FIG. 4, it is possible to substantially match the actual detection value γ (i), so that the above estimation does not become unstable even in a high steering frequency region.
The gain can be increased during the estimation without worrying about this, and the convergence of the estimated value to the true value can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a vehicle motion state quantity estimation device according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of a motion state amount estimating function executed by a microcomputer in the same embodiment.

FIG. 3 is a flowchart of exercise state amount estimation control executed by the microcomputer in the same embodiment.

FIG. 4 is a change time chart of various detection signals and estimation signals when a motion state amount is estimated in the same embodiment.

FIG. 5 is a block diagram showing a conventional general vehicle motion state amount estimation device.

FIG. 6 is a diagram showing a yaw rate gain characteristic and a phase characteristic of a vehicle.

FIG. 7 is a change time chart of various detection signals and estimated signals when a motion state amount of a vehicle is estimated by a conventional motion state amount estimation device.

[Explanation of symbols]

 10 Microcomputer 11 Steering angle sensor 12 Vehicle speed sensor 13 Yaw rate sensor 14 Road surface μ sensor 15 Signal processing circuit 16 Signal processing circuit 17 Signal processing circuit 18 Signal processing circuit 19 D / A converter 20 D / A converter 21 Amplifier 22 Amplifier

Claims (5)

[Claims] 1. An apparatus for estimating a certain vehicle motion state quantity and another vehicle motion state quantity using a steering angle, a vehicle speed, and a detected value of a certain vehicle motion state quantity. Angle, vehicle speed, a delay deviation between the detected value and the estimated value of the certain vehicle motion state amount, and using a vehicle model, estimating the certain vehicle motion state amount and other vehicle motion state amounts, An apparatus for estimating a motion state amount of a vehicle, wherein the estimation value of the certain vehicle motion state amount is delayed for a predetermined time to contribute to the calculation of the delay deviation. 2. The method according to claim 1, wherein a delay time of the certain vehicle motion state quantity with respect to wheel steering is measured in advance as a dead time, and the estimated value of the certain vehicle motion state quantity corresponds to the dead time. An apparatus for estimating a motion state amount of a vehicle, wherein the apparatus is configured to contribute to the calculation of the delay deviation by delaying by a predetermined time. 3. The vehicle motion state estimating device according to claim 2, wherein the dead time is made longer as the road surface friction coefficient becomes lower. 4. The dynamic characteristic of a vehicle motion state quantity detecting means according to claim 2, wherein an estimated value of the certain vehicle motion state quantity delayed by the dead time is used for detecting the certain vehicle motion state quantity. The vehicle motion state quantity estimating device is further configured to contribute to the calculation of the delay deviation by further delaying the time by a time corresponding to the following. 5. The yaw rate according to claim 1, wherein a yaw rate of the vehicle is used as the certain vehicle motion state quantity, and a side slip angle of the vehicle is used as the other vehicle motion state quantity. A motion state estimating device for a vehicle, characterized in that the observer is configured to use the observer as a reference input, and the side slip angle of the vehicle is estimated using the observer.