JPH1164008A - Car sideslip angle detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a car sideslip angle detecting device for obtaining sideslip angle of a car with precision at low cost. SOLUTION: Using a sideslip angle detecting part 1A for detecting car sideslip angle β1, sideslip angular velocity detecting part 2 for detecting car sideslip angular velocity dβ, a sideslip angle β1, and sideslip angular velocity dβ, a correction sideslip angle β' is calculated based on an equation dβ'=-k.β'+(k.β1+dβ), where dβ' is the differential value of a correction sideslip angle and k is filter gain. Such precision sideslip angle as with less offset error, etc., is obtained compared to the case where a sideslip angle is calculated by simply integrating a sideslip angular speed. Further, a device is utilized at a low cost compared to the case of using a ground speed sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle side slip angle detecting device for detecting a vehicle side slip angle, and more particularly to a technique for improving the detection accuracy of the vehicle side slip angle.

[0002]

2. Description of the Related Art For example, Japanese Unexamined Patent Publication No. 7-257337 discloses that a behavior of a vehicle at the time of turning is determined based on a vehicle slip angle β and a vehicle body slip angular velocity dβ / dt to determine whether the vehicle has a tendency to spin or drift out. It describes that the braking force is controlled based on the determination result to stabilize the turning behavior of the vehicle.

At this time, the vehicle slip angle β is determined by detecting the longitudinal speed Vx and the lateral speed Vy of the vehicle using a ground speed sensor, calculating arctan (Vy / Vx), and calculating the vehicle slip angle β. (See FIG. 2 showing the relationship between the vehicle and the vehicle motion state quantity such as the sideslip angle β. However, CG indicates the center of gravity of the vehicle.) The front-rear speed Vx of the vehicle can be relatively easily and accurately detected by using a wheel rotation speed sensor. However, it is relatively difficult to detect the lateral speed Vy. As a ground speed sensor used to detect the lateral speed Vy, there is a sensor utilizing the principle of a spatial filter, but it is mainly used for test measurement and is very expensive.

As another method for detecting the vehicle sideslip angle β, as disclosed in Japanese Patent Application Laid-Open No. 62-83247, the vehicle yaw rate dγ, the longitudinal velocity Vx, the lateral acceleration ay at the vehicle center of gravity, and the like. Is detected by each sensor,
There is also a method of detecting the sideslip angle β0 by performing an integration operation according to the following equation (1). β0 = ∫ (ay / Vx−dγ) dt (1)

[0005]

In the conventional vehicle slip angle detection system, since the vehicle speed Vy is detected by using a ground speed sensor such as a spatial filter as described above, it is very expensive. There was a problem. Further, in the detection method using the above equation (1), since the detected values of the respective sensors are integrated as they are, if there is an error in each detected value, the error is also integrated. for that reason,
If the error is a steady-state error such as a mounting angle error of the lateral acceleration sensor or the yaw rate sensor, the error is accumulated as time passes, and the side slip angle β0
There is a problem that the detection accuracy of the image is reduced. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a vehicle side slip angle detection device capable of obtaining a vehicle side slip angle inexpensively and accurately.

[0006]

According to a first aspect of the present invention, there is provided a vehicle side slip angle detecting device for detecting a side slip angle of a vehicle, a side slip angular speed detecting unit for detecting a side slip angular speed of the vehicle, and a side slip angle. The vehicle further comprises a sideslip angle correction unit that calculates and outputs a corrected sideslip angle from the sideslip angle detected by the angle detection unit and the sideslip angular velocity detected by the sideslip angular velocity detection unit.

According to a second aspect of the present invention, there is provided a vehicle side slip angle detecting device according to the first aspect, wherein the side slip angle correcting means calculates a corrected side slip angle based on the following equation. dβ ′ = − k · β ′ + (k · β1 + dβ) where β ′: corrected side slip angle dβ ′: derivative value of corrected side slip angle k: filter gain β1: detected side slip angle dβ: detected side slip angle angular velocity

According to a third aspect of the present invention, there is provided a vehicle side slip angle detecting device according to the second aspect of the present invention, wherein a vehicle motion state amount detecting means for detecting a vehicle motion state amount such as a yaw rate; Filter gain setting means for setting a filter gain k.

According to a fourth aspect of the present invention, there is provided a vehicle side slip angle detecting device according to any one of the first to third aspects, wherein the side slip angle detecting means includes a plurality of side slip angle detectors for detecting a side slip angle of the vehicle; And a weighted averaging means for obtaining a weighted average of the plurality of sideslip angles detected by the plurality of sideslip angle detection units to obtain a sideslip angle as a detection value of the sideslip angle detection means.

According to a fifth aspect of the present invention, in the vehicle side slip angle detecting device according to the fourth aspect of the present invention, as the plurality of side slip angle detecting sections, the first side slip for obtaining the vehicle side slip angle by calculation using a two-wheel model of the vehicle. An angle detector, and a second sideslip angle detector that obtains the sideslip angle of the vehicle using an observer, wherein the weighted averaging means converts the sideslip angles detected by the first and second sideslip detectors into a yaw rate. The weighted average is used accordingly to obtain a side slip angle as a detection value of the side slip angle detecting means.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a block diagram showing a vehicle slip angle detection device according to a first embodiment of the present invention. In the figure, 11 is a yaw rate sensor that detects the yaw rate dγ of the vehicle, 12 is a front-rear speed sensor that detects the front-rear speed Vx of the vehicle, 13 is a steering angle sensor that detects the front wheel steering angle δf, and 14 is a lateral angle at the center of gravity of the vehicle. This is a lateral acceleration sensor that detects the acceleration ay.

Reference numeral 1A denotes a side slip angle detecting section for detecting the side slip angle β1 of the vehicle based on the detection outputs of the yaw rate sensor 11, the longitudinal speed sensor 12, the steering angle sensor 13 and the lateral acceleration sensor 14. 2 is a yaw rate sensor 11, a longitudinal speed sensor 12, and a lateral acceleration sensor 14.
Is a side slip angular velocity detector that detects the side slip angular velocity dβ of the vehicle based on the detection output of the vehicle. Reference numeral 3A denotes a sideslip angle correction unit that calculates and outputs a corrected sideslip angle β ′ from the sideslip angle β1 detected by the sideslip angle detection unit 1 and the sideslip angular velocity dβ detected by the sideslip angular velocity detection unit 2. These sideslip angle detecting section 1A, sideslip angular velocity detecting section 2, and sideslip angle correcting section 3A are constituted by a microcomputer and an input / output device.

FIG. 2 shows the relationship between the vehicle and the vehicle motion state quantity such as the side slip angle β. The longitudinal speed Vx and the longitudinal acceleration ax are each positive in the forward direction of the vehicle. The lateral speed Vy and the lateral acceleration ay are each positive in the left direction of the vehicle. The yaw rate dγ is positive in the direction opposite to the clockwise direction.

Next, the details of the side slip angle detecting section 1A will be described. In the side slip angle detecting section 1A, the side slip angle β1 of the vehicle is obtained from the following equation (2).
This equation (2) is well known as an equation obtained from a two-wheel model of a vehicle. β1 =-(m ・ Vx (dβ + dγ) + (Cf ・ Lf-Cr ・ Lr) dγ / Vx-Cf ・ δf} / (Cf + Cr) =-(m ・ ay + (Cf ・ Lf-Cr ・Lr) dγ / Vx−Cf · δf) / (Cf + Cr) (2) where m: vehicle mass ay: vehicle lateral acceleration Cf: front wheel cornering power Cr: rear wheel cornering power Lf: from vehicle center of gravity Front wheel axle distance Lr: Distance between vehicle center of gravity and rear wheel axle dγ: Yaw rate Vx: Front-rear speed of vehicle δf: Front wheel steering angle

The side slip angle detector 1A detects the yaw rate dγ detected by the yaw rate sensor 11, the vehicle front-rear speed Vx detected by the front-rear speed sensor 12, and the steering angle sensor 13
, And the lateral acceleration ay detected by the lateral acceleration sensor 14 are input, and the vehicle slip angle β1 is calculated and output based on the above equation (2). The vehicle mass m, the front wheel cornering power Cf, the rear wheel cornering power Cr, the distance Lf between the vehicle center of gravity and the front wheel axle, and the distance Lr between the vehicle center of gravity and the rear wheel axle are values set and stored in advance. Is used.

Next, the details of the side slip angular velocity detector 2 will be described. In this side slip angular velocity detecting unit 2,
The side slip angular velocity of the vehicle is obtained from the following equation (3). dβ = ay / Vx−dγ (3) The sideslip angular velocity detector 2 detects the yaw rate dγ detected by the yaw rate sensor 11, the longitudinal velocity Vx of the vehicle detected by the longitudinal velocity sensor 12, and the lateral acceleration sensor 14. The lateral acceleration ay is input, and the lateral slip angular velocity dβ of the vehicle is calculated based on the above equation (3) and output.

Next, the details of the side slip angle correction section 3A will be described. From the sideslip angle β1 detected by the sideslip angle detector 1A and the sideslip angular velocity dβ detected by the sideslip angular velocity detector 2, a corrected sideslip angle β ′ is calculated based on the following equation (4). Here, dβ ′ is a differential value of the corrected side slip angle, and k is a filter gain. dβ ′ = − k · β ′ + (k · β1 + dβ) (4) In the sideslip angle correction unit 3A, the sideslip angle β1 is input from the sideslip angle detection unit 1, and the sideslip angular speed is input from the sideslip angular speed detection unit 2. dβ, and based on the above equation (4),
The side slip angle β 'is calculated and output. Filter gain k
Uses a value set and stored in advance.

Next, a method for detecting the vehicle side slip angle β 'by the vehicle side slip angle detecting device shown in FIG. 1 will be described with reference to the flowchart shown in FIG. This flowchart is a vehicle slip angle calculation routine executed at each calculation cycle by the microcomputer, and realizes a side slip angle detecting unit 1A, a side slip angular velocity detecting unit 2, and a side slip angle correcting unit 3A. First, step S1
Then, a sensor signal is input. That is, the yaw rate dγ from the yaw rate sensor 11, the longitudinal speed Vx of the vehicle from the longitudinal speed sensor 12, the front wheel steering angle δf from the steering angle sensor 13.
Is input from the lateral acceleration sensor 14 to the lateral acceleration ay at the center of gravity of the vehicle. The front-rear speed sensor 12 calculates the front-rear speed Vx of the vehicle from the wheel speeds of the four wheels, for example, similarly to an ABS control device or the like.

Next, in step S2, the yaw rate dγ,
The longitudinal speed Vx, the front wheel steering angle δf, and the lateral acceleration ay are substituted into the above equation (2) to calculate the side slip angle β1. In addition,
As the vehicle mass m and the like, values set and stored in advance are used. Next, in step S3, the lateral slip angular velocity dβ is calculated by substituting the yaw rate dγ, the longitudinal velocity detection value Vx, and the lateral acceleration ay into the above equation (3). Next, in step S4, the sideslip angle β1, the sideslip angular velocity dβ and the corrected sideslip angle β ′ calculated in steps S2 and S3 are substituted into the above equation (4), dβ ′ is obtained, and a numerical integration operation is performed to perform correction. Determine the sideslip angle β ′. However, when this routine is executed for the first time, there is no corrected side slip angle β ', so the term of the corrected side slip angle β' is substituted by the side slip angle β1 calculated in step S2. Next, in step 5,
The calculated side slip angle β ′ is output to a vehicle behavior control device that controls a vehicle behavior (not shown).

FIG. 4A shows the sideslip angle β1 calculated based on the above equation (2), and FIG. 4B shows the corrected sideslip angle β 'detected by the sideslip angle detecting device shown in FIG.
C indicates the sideslip angle β0 when simple integration is performed based on the above equation (1). 4A to 4C show the sideslip angle β detected by the expensive optical sideslip angle detection device as a substitute for the true value of the sideslip angle. In the case of simple integration, the detected lateral acceleration ay and yaw rate dγ
Is accumulated and the offset error increases with time, whereas when the sideslip angle detection device shown in FIG. 1 is used, the offset error is within a certain offset error, The sideslip angle can be accurately estimated. Further, the error of the sideslip angle β1 calculated based on the above equation (2) is large when the sideslip angle is large, and when viewed as a whole, the corrected sideslip angle β ′ by the sideslip angle detection device shown in FIG. The error is small.

As described above, in the vehicle side slip angle detecting device shown in FIG. 1, the corrected side slip angle is based on both the side slip angle β1 detected by the side slip angle detector 1A and the side slip angular velocity dβ detected by the side slip angular velocity detector 2. β ′ is calculated, and a more accurate slip angle β ′ can be obtained than the slip angle β1 detected only by the slip angle detection unit 1A, and the slip angle obtained by integrating the slip angle velocity dβ is more accurate. Good side slip angle β ′ can be obtained.

Further, the side slip angle β 'is calculated by the above equation (4), and the estimation error of the corrected side slip angle β' can be made smaller than the estimation error of the side slip angle β1.
Hereinafter, this will be described. The estimated error e ′ of the corrected sideslip angle β ′ is β−β ′, and the estimated error e1 of the sideslip angle β1 is β
-Be it β1. When the corrected sideslip angle β ′ is calculated from the sideslip angle β 1 and the sideslip angular velocity dβ using the above equation (4) (for stability, k> 0), the error equation of the following equation (5) is obtained. can get. de '/ dt = dβ- dβ' =-k · e '-k · e1 (5)

When the error equation of the equation (5) is solved, the following equation (6) is obtained.

(Equation 1)

Here, the following assumption is made. 1. The estimation error e1 is bounded. That is, | e1 (t) |
≦ E for ∀t> 0 holds. 2. k (t) is bounded. That is, | k (t) | ≦ A fo
r ∀t> 0 holds. Then, the following equation (7) holds.

(Equation 2)

From the above equation (7), when k is bounded,
If the estimation error e1 is bounded, it is understood that the estimation error e 'is also bounded. Further, it can be seen that the upper limit of the estimation error e 'is equal to or smaller than the upper limit of the estimation error e1. That is, by calculating the sideslip angle β ′ according to the above equation (4), the estimation error of the corrected sideslip angle β ′ is reduced by the sideslip angle β1.
Can be smaller than the estimation error.

Embodiment 2 FIG. FIG. 5 shows a configuration of a vehicle side slip angle detecting device according to a second embodiment of the present invention. In FIG. 5, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. Reference numeral 15 denotes a longitudinal acceleration sensor that detects the longitudinal acceleration ax at the center of gravity of the vehicle. 4 is a yaw rate which is a motion state quantity of the vehicle.
This is a yaw rate sensor that detects dγ. 5 is based on the yaw rate dγ detected by the yaw rate sensor 4,
Filter gain k used in side slip angular velocity correction unit 3B
In the filter gain setting section.

Reference numeral 1B denotes a side slip angle detecting section corresponding to the side slip angle detecting section 1A in the vehicle side slip angle detecting apparatus shown in FIG. 1, and includes a yaw rate sensor 11, a longitudinal speed sensor 12, a lateral acceleration sensor 14, and a longitudinal acceleration sensor 15.
Is a sideslip angle detection unit that detects the sideslip angle β1 of the vehicle based on the detection output of the vehicle. Reference numeral 3B denotes a sideslip angle correction unit corresponding to the sideslip angle correction unit 3A in the vehicle sideslip angle detection device shown in FIG. 1, and the sideslip angle β1 detected by the sideslip angle detection unit 1B and the sideslip angle β1 detected by the sideslip angular velocity detection unit 2. A side slip angle correction unit that calculates and outputs a corrected side slip angle β ′ from the calculated side slip angular velocity dβ and the filter gain k set by the filter gain setting unit 5. The sideslip angle detecting section 1B, sideslip angular velocity detecting section 2, sideslip angle correcting section 3B and filter gain setting section 5 are constituted by a microcomputer and an input / output device.

Next, the details of the side slip angle detecting section 1B will be described. In this side slip angle detecting section 1B, the side slip angle β1 of the vehicle is obtained using an observer (see Japanese Patent Application No. 8-136799). It is known that the relationship between the vehicle motion state quantities such as the lateral velocity Vy and the longitudinal velocity Vx as viewed from the vehicle body fixed coordinate system is expressed by the following equations (8) and (9). dVx / dt = dγ · Vy + ax (8) dVy / dt = −dγ · Vx + ay (9)

The vehicle motion state quantities such as the lateral speed Vy and the longitudinal speed Vx change while maintaining the relations of the above equations (8) and (9). If this is rewritten as a state equation, assuming that the output is the longitudinal speed Vx of the vehicle,
Equations (10) and (11) below are obtained. Note that the system matrix A (t) is time-varying. Also, 'indicates transposition, and; in [] indicates a line feed. dx / dt = A (t) · x + B · u (10) y = C · x (11) where state x = [Vx Vy] ′ input u = [ax ay] ′ output y = Vx system matrix A (t) = [0 dγ; −dγ 0] input matrix B = [10; 01] output matrix C = [10]

When the observer is constructed in the same manner as in a normal time-invariant case, the following equation (12) is obtained. Note that zvx indicates an estimated value of the vehicle longitudinal speed Vx, and zvy indicates an estimated value of the vehicle lateral speed Vy. dz / dt = A (t) · z + Bu · K + (Cz−y) (12) where observer state z = [zvx zvy] ′ observer gain K = [k1 k2] ′

When an observer is used, in order to estimate the state quantity without error, it is necessary to use a gain that makes the differential equation of the estimation error e shown in the following equation (13) stable, that is, the estimation error e converges to 0. There is. de / dt = (A (t) + KC) e (13) However, if e = z−x (A (t) + KC) is stable, the estimation error e converges to zero. That is, the vehicle lateral speed Vy can be estimated.

In order to obtain the gain K for stabilizing the error differential equation of the above equation (13), a feedback gain for stabilizing the dual system of the following equation (14) may be derived. dx / dt = A (t) 'x + C'u (14) For this purpose, assuming that the above system is linearly invariant, the Riccati equation of the following equations (15) and (16) The gain K may be determined from the correct definite solution P. Here, Q and R are quadratic square matrices, Q indicates the weight applied to the state x, and R indicates the weight applied to the input u. It is assumed that R ^ (-1) represents R minus the first power. This is also true for other variables. K = -PC'R ^ (-1) (15) dP / dt + Q + AP + PA'-PC'R ^ (-1) CP = 0 (16)

In order to find the solution of the above differential equation, for example, the following equations (17) to (19) may be solved. However,
P = [P11 P12; P12 P22], Q = [Q11 Q12; Q1
2Q22]. Also, let P11 ^ 2 represent the square of P11. This is also true for other variables. dP11 / dt = -Q11-2dγP12 + R ^ (-1) P11 ^ 2 (17) dP12 / dt = -Q12 + dγP11-dγP22 + R ^ (-1) P11P12 (18) dP22 / dt = -Q22 + 2dγP12 + R ^ ( -1) P12 ^ 2 (19) In the sideslip angle detecting unit 1B, using the relational expression described above,
The vehicle sideslip angle β1 is determined.

Next, details of the filter gain setting section 5 will be described. The observer used in the sideslip angle detecting unit 1B has a system matrix A as shown in the following equation (20).
Since the element of (t) is the yaw rate dγ, the yaw rate dγ
Is 0, the system matrix A (t) = 0, and considering the linear time-invariant observer theory, the system is no longer observable, the observer does not hold, and the estimation error increases. System matrix A (t) = [0 dγ; −dγ 0] (20) Therefore, when the detected yaw rate dγ is small, the filter gain setting unit 5 reduces the filter gain k. If the accuracy of the sideslip angle β1 is low,
The influence of the side slip angle β1 on the corrected side slip angle β ′ is reduced. For example, as shown in FIG. 6, the filter gain k is set according to the yaw rate dγ.

The sideslip angle correcting section 3B includes a sideslip angle β1 detected by the sideslip angle detecting section 1B, a sideslip angular velocity dβ detected by the sideslip angular velocity detecting section 2, and a filter gain k set by a filter gain setting section 5. Then, the corrected side slip angle β ′ is calculated based on the above equation (4). Other configurations of the vehicle side slip angle detecting device shown in FIG. 5 are the same as those of the vehicle side slip angle detecting device shown in FIG.

Next, a method for detecting the vehicle side slip angle β 'by the vehicle side slip angle detecting device shown in FIG. 5 will be described with reference to the flowchart shown in FIG. Note that this flowchart is a vehicle slip angle calculation routine executed at each calculation cycle by the microcomputer, and realizes a slip angle detection unit 1B, a slip angle speed detection unit 2, a slip angle correction unit 3B, and a filter gain setting unit 5. Things.

First, in step S11, a sensor signal is input. That is, the yaw rate dγ from the yaw rate sensor 11 and the longitudinal velocity Vx
, The lateral acceleration ay at the center of gravity of the vehicle from the lateral acceleration sensor 14 and the longitudinal acceleration ax at the center of gravity of the vehicle from the longitudinal acceleration sensor 15 are input. In the longitudinal speed sensor 12, for example, like an ABS control device,
The longitudinal speed Vx of the vehicle is calculated from the four wheel speeds.

Next, at step S12, the yaw rate d
γ, vehicle longitudinal velocity Vx, longitudinal acceleration ax, lateral acceleration ay
Is input to the observer to determine the sideslip angle β1. First, the differential coefficient of the observer gain is calculated from the above equations (17) to (19), and this is numerically integrated, whereby P
To obtain each component. Then, P is calculated by the above equation (15), (1)
6) Substitute into the equation to obtain the observer gain. further,
Based on the above equation (12), the differential coefficient of the observer state variable z is calculated using the sensor input value and the observer gain, and each component of z is obtained by numerically integrating this. The second row, first column component of z is the observer output of the lateral velocity Vy, from which the sideslip angle β1 is obtained from arctan (Vy / Vx).

Next, in step S13, the yaw rate d
γ, the longitudinal velocity Vx, and the lateral acceleration ay are substituted into the above equation (3) to calculate the lateral slip angular velocity dβ. Next, step S
At 14, the filter gain k is set according to the yaw rate dγ, which is the vehicle motion state quantity. The relationship between the yaw rate dγ and the filter gain k is stored in a map, and the filter gain k corresponding to the yaw rate dγ is read. By setting the filter gain k in this way, it is possible to compensate for the characteristic of the observer in which the estimation accuracy of the sideslip angle deteriorates when the yaw rate dγ is small. That is, when the yaw rate dγ is small, the weight using the sideslip angle β1 obtained from the observer is reduced, and the sideslip angular velocity dβ
The weight using the integration result of can be increased.

Next, in step S15, step S12
~ Slip angle β1, calculated in S14, sideslip angular velocity d
The value β, the filter gain k, and the corrected side slip angle β ′ are substituted into the above equation (4) to obtain dβ ′, and a numerical integration operation is performed to obtain the corrected side slip angle β ′. However, when this routine is executed for the first time, there is no corrected side slip angle β ', so the term of the corrected side slip angle β' is substituted by the side slip angle β1 calculated in step S12. Next, in step S16, the calculated sideslip angle β 'is output to a vehicle behavior control device that controls the vehicle behavior (not shown).

As described above, in the vehicle side slip angle detecting device shown in FIG. 5, the corrected side slip angle is based on both the side slip angle β1 detected by the side slip angle detector 1B and the side slip angular velocity dβ detected by the side slip angular velocity detector 2. β ′ is calculated, and a more accurate slip angle β ′ can be obtained than the slip angle β1 detected only by the slip angle detection unit 1B, and the accuracy is more accurate than the slip angle obtained by integrating the slip angular velocity dβ. Good side slip angle β ′ can be obtained.

Further, the side slip angle β 'is calculated by the above equation (4), and the estimation error of the corrected side slip angle β' can be made smaller than the estimation error of the side slip angle β1.
Further, the yaw rate d detected by the yaw rate sensor 4
The filter gain k is set in accordance with γ, and can compensate for the characteristic of the observer in which the estimation accuracy of the sideslip angle deteriorates when the yaw rate dγ is small. That is, when the yaw rate dγ is small, the weight using the side slip angle β1 obtained from the observer in the side slip angle detection unit 1B can be reduced, and the weight using the integration result of the side slip angular velocity dβ can be increased. 'Can be estimated.

Embodiment 3 FIG. 8 shows a configuration of a vehicle side slip angle detecting device according to Embodiment 3 of the present invention. 8, parts corresponding to those in FIGS. 1 and 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the vehicle side slip angle detecting device shown in FIG. 8, the vehicle side slip angle detecting unit 1 constituting the vehicle side slip angle detecting device of FIG.
A and a sideslip angle detection unit 1B that constitutes the vehicle sideslip angle detection device of FIG.

The side slip angle detecting section 1A is based on the detection outputs of the yaw rate sensor 11, the longitudinal speed sensor 12, the steering angle sensor 13 and the lateral acceleration sensor 14 as described above.
Formula obtained from the two-wheel model of the vehicle (see formula (2) above)
Is a side slip angle detection unit that detects a side slip angle of the vehicle. The sideslip angle detection unit 1B detects the sideslip angle of the vehicle using an observer based on the detection outputs of the yaw rate sensor 11, the longitudinal speed sensor 12, the lateral acceleration sensor 14, and the longitudinal acceleration sensor 15 as described above. Department.

6 calculates a weighted average of the sideslip angle β2 detected by the sideslip angle detector 1A and the sideslip angle β3 detected by the sideslip angle detector 1B, and calculates the sideslip as a detection value of the sideslip angle detecting means. This is a side slip angle weighted average section that obtains the angle β1 and supplies it to the side slip angle correction section 3A. Side slip angle detectors 1A and 1B, sideslip angular velocity detector 2,
Side slip angle correction unit 3A and side slip angle weighted average unit 6
Is composed of a microcomputer and an input / output device.

The details of the side slip angle weighted average section 6 will be described. In the sideslip angle weighted averaging unit 6, the sideslip angle β2 detected by the sideslip angle detection unit 1A and the sideslip angle β3 detected by the sideslip angle detection unit 1B are represented by the following (21).
The sideslip angle β1 is obtained by weighted averaging according to the equation. β1 = c2 · β2 + c3 · β3 (21) where c2 + c3 = 1

Here, the weighted average weights c2 and c3 of the sideslip angles β2 and β3 are set as follows according to the yaw rate dγ detected by the yaw rate sensor 11. That is, the error of the sideslip angle β3 detected by the sideslip angle detection unit 1B using the observer increases when the yaw rate dγ is small. Therefore, as shown in FIG. 9, when the yaw rate dγ is small, the weight c3 of the sideslip angle β3 is set to be small. Thereby, a more accurate side slip angle β1 can be obtained.

In the side slip angle correcting section 3B, the side slip angle β1 obtained by the side slip angle weighted averaging section 6 as described above is used.
Then, the corrected sideslip angle β ′ is calculated from the sideslip angular velocity dβ detected by the sideslip angular velocity detection unit 2 based on the above-described equation (4). The filter gain k may use a value which is set and stored in advance, but may be set according to a vehicle motion state quantity such as a yaw rate as in the vehicle side slip angle detecting device shown in FIG. Good.
Other configurations of the vehicle side slip angle detection device shown in FIG.
This is the same as the vehicle slip angle detection device shown in FIGS. 1 and 5.

Next, a method for detecting the vehicle slip angle β 'by the vehicle slip angle detecting device shown in FIG. 8 will be described with reference to the flowchart shown in FIG. Note that this flowchart is a vehicle slip angle calculation routine executed at each calculation cycle by the microcomputer, and includes a side slip angle detection section 1A, a side slip angle detection section 1B, a side slip angle weighted average section 6, a side slip angular velocity detection section 2, and a side slip angle. This implements the angle correction unit 3A.

First, in step S31, a sensor signal is input. That is, the yaw rate dγ from the yaw rate sensor 11 and the longitudinal velocity Vx
, The front wheel steering angle δf from the steering angle sensor 13, the lateral acceleration ay at the center of gravity of the vehicle from the lateral acceleration sensor 14, and the longitudinal acceleration ax at the center of gravity of the vehicle from the longitudinal acceleration sensor 15. The front-rear speed sensor 12 calculates the front-rear speed Vx of the wheels based on the wheel speeds of the four wheels, for example, similarly to an ABS control device. Next, in step S32, the side slip angle β2 is calculated by substituting the yaw rate dγ, the longitudinal speed Vx of the vehicle, the front wheel steering angle δf, and the lateral acceleration ay into the above equation (2). The vehicle mass m is set in advance,
Use the stored value.

Next, at step S33, the yaw rate d
γ, the longitudinal velocity Vx, the longitudinal acceleration ax, and the lateral acceleration ay are input to the observer to determine the side slip angle β3. First, a differential coefficient of the observer gain is calculated from the above equations (17) to (19), and each component of P is obtained by numerically integrating this. Then, P is substituted into the above equations (15) and (16) to obtain an observer gain. Further, the above (1)
Based on the equation (2), the differential coefficient of the observer state variable z is calculated using the sensor input value and the observer gain, and each component of z is obtained by numerical integration. The second row, first column component of z is the observer output of the lateral velocity Vy, from which the sideslip angle β3 is determined from arctan (Vy / Vx).

Next, in step S34, based on the map shown in FIG. 9, the weighted average weights c2 and c3 are calculated from the yaw rate dγ.
Set. Next, in step S35, the sideslip angle β
The side slip angle β1 is calculated from 2, β3 and the weighted average weights c2 and c3 based on the above equation (21). Next, in step S36, the yaw rate dγ, the longitudinal velocity Vx, and the lateral acceleration ay
Into the equation (3) to obtain the sideslip angular velocity dβ
Is calculated.

Then, in step S37, the sideslip angle β1, the sideslip angular velocity dβ and the corrected sideslip angle β ′ calculated in steps S35 and S36 are substituted into the above equation (4) to obtain dβ ′, and a numerical integration operation is performed. To obtain the corrected side slip angle β ′. However, when this routine is executed for the first time, since the corrected sideslip angle β 'does not exist, the sideslip angle β1 calculated in step S35 is substituted for the term of the corrected sideslip angle β'. Next, step S3
In step 8, the calculated sideslip angle β 'is output to a vehicle behavior control device for controlling vehicle behavior (not shown).

As described above, in the vehicle side slip angle detecting device shown in FIG. 8, the corrected side slip is based on both the side slip angle β1 obtained by the side slip angle weighted average section 6 and the side slip angular velocity dβ detected by the side slip angular velocity detecting section 2. The angle β ′ is calculated, and a more accurate side slip angle β ′ can be obtained than the side slip angle β1, and the side slip angular velocity d
It is possible to obtain a more accurate side slip angle β ′ than the side slip angle obtained by integrating β. In addition, the side slip angle β ′ is calculated by the above equation (4), and the estimation error of the corrected side slip angle β ′ can be made smaller than the estimation error of the side slip angle β1.

Further, the vehicle slip angle β2 obtained by the equation (see the above equation (2)) obtained from the two-wheel model of the vehicle and the vehicle slip angle β3 obtained by using the observer are calculated by the yaw rate The weight average is determined according to dγ to determine the sideslip angle β1, and when the yaw rate dγ is small, the weighted average weight c3 of the sideslip angle β3 determined using an observer whose accuracy deteriorates is reduced. As a result, a highly accurate sideslip angle β1 can be obtained, and as a result, a more accurate sideslip angle β ′ can be obtained. Although the vehicle side slip angle detecting device shown in FIG. 8 includes two sideslip angle detectors 1A and 1B, it includes three or more sideslip angle detectors, and similarly has a more accurate side slip angle. It is also possible to obtain β1.

[0056]

According to the first aspect of the present invention, the corrected sideslip angle is calculated based on both the sideslip angle detected by the sideslip angle detector and the sideslip angular velocity detected by the sideslip angular velocity detector. There is an effect that a more accurate side slip angle can be obtained than the side slip angle detected by only the side slip angle detection unit. Further, a more accurate side slip angle can be obtained than the side slip angle obtained by integrating the side slip angular velocity. That is, even if the detection outputs of the longitudinal acceleration, the lateral acceleration, and the yaw rate include an offset error, a highly accurate side slip angle with less offset error and the like is obtained as compared with a side slip angle obtained by simply integrating the side slip angular velocity. There is an effect that can be.

Further, according to the apparatus for switching and outputting the sideslip angle obtained by integrating the sideslip angle detected by the sideslip angle detector and the sideslip angular velocity detected by the sideslip angular velocity detector, the output sideslip angle is discontinuous. However, according to the invention of claim 1, there is no discontinuous change in the output sideslip angle, and there is an effect that good control of the vehicle behavior can be executed. Further, there is an effect that the apparatus can be manufactured at a lower cost than when a ground speed sensor is used.

According to a second aspect of the present invention, in the first aspect, dβ ′ = − k · β ′ + (k · β1 + dβ) where β ′: corrected side slip angle dβ ′: corrected side slip angle Derivative value k: Filter gain β1: Detected sideslip angle dβ: Calculates sideslip angle β 'using the equation of detected sideslip angular velocity. The estimated error of corrected sideslip angle β' is smaller than the estimated error of sideslip angle β1. There is an effect that can be.

According to a third aspect of the present invention, in the second aspect of the present invention, the filter gain k is set according to the vehicle motion state quantity. For example, the accuracy of the sideslip angle β1 is smaller than the accuracy of the sideslip angular velocity dβ. When the vehicle behavior is good, increasing the filter gain k can increase the weight of the sideslip angle β1 when calculating the corrected sideslip angle β ′, and has the effect that the sideslip angle can be estimated more accurately.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, a plurality of sideslip angles detected by the plurality of sideslip angle detection units are weighted and averaged to obtain a detection value of the sideslip angle detection means. As the sideslip angle as
For example, by setting the weighted average weight of a plurality of sideslip angles to always increase the weight of the more accurate sideslip angle in accordance with the vehicle motion state amount, there is an effect that the sideslip angle can be more accurately estimated.

According to a fifth aspect of the present invention, in the invention of the fourth aspect, the vehicle sideslip angle obtained by the equation obtained from the two-wheel model of the vehicle and the vehicle sideslip angle obtained by using the observer are obtained. Is a weighted average according to the yaw rate to obtain a sideslip angle as a detection value of the sideslip angle detection means.When the yaw rate is small, the weight of the sideslip angle obtained using an observer whose accuracy deteriorates becomes small. By setting to be small, it is possible to obtain a highly accurate side slip angle, and as a result, it is possible to obtain a more accurate corrected side slip angle.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a vehicle side slip angle detection device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a vehicle and a vehicle motion state quantity such as a side slip angle β;

FIG. 3 is a flowchart illustrating a method for detecting a side slip angle of a vehicle according to the first embodiment.

FIG. 4 shows a side slip angle β ′ output by the side slip angle detecting device of the present invention, a side slip angle β0 obtained by simply integrating the side slip angular velocity, and a side slip angle β1 calculated based on an equation obtained from a two-wheel model. FIG.

FIG. 5 is a block diagram showing a configuration of a vehicle side slip angle detection device for describing Embodiment 2 of the present invention.

FIG. 6 is a diagram illustrating a relationship between a yaw rate and a filter gain to be set according to a second embodiment.

FIG. 7 is a flowchart illustrating a method for detecting a side slip angle of a vehicle according to a second embodiment.

FIG. 8 is a block diagram showing a configuration of a vehicle side slip angle detecting device as a third embodiment of the present invention.

FIG. 9 is a diagram illustrating a relationship between a yaw rate and a weighted average weight of a set side slip angle for explaining the third embodiment;

FIG. 10 is a flowchart illustrating a method of detecting a sideslip angle of a vehicle according to a third embodiment.

[Explanation of symbols]

1A, 1B side slip angle detecting section, 2 sideslip angular velocity detecting section, 3A, 3B side slip angle correcting section, 4,11 yaw rate sensor, 5 filter gain setting section, 6 sideslip angle weighted average section, 12 forward / backward speed sensor, 13 steering angle sensor , 14 lateral acceleration sensor, 15 longitudinal acceleration sensor.

Claims (5)

[Claims] 1. A side slip angle detecting unit for detecting a side slip angle of a vehicle, a side slip angular speed detecting unit for detecting a side slip angular speed of the vehicle, and a side slip angle detected by the side slip angle detecting unit and the side slip angular speed detecting unit. A vehicle sideslip angle detecting device, comprising: sideslip angle correction means for calculating and outputting a corrected sideslip angle from a detected sideslip angular velocity. 2. The vehicle sideslip angle detecting device according to claim 1, wherein the sideslip angle correction means calculates the corrected sideslip angle based on the following equation. dβ ′ = − k · β ′ + (k · β1 + dβ) where β ′: corrected side slip angle dβ ′: differential value of corrected side slip angle k: filter gain β1: detected side slip angle dβ: detected side slip angle angular velocity 3. A vehicle motion state quantity detecting means for detecting a vehicle motion state quantity such as a yaw rate; and a filter gain setting means for setting the filter gain k in accordance with the vehicle motion state quantity. The vehicle side slip angle detecting device according to claim 2, wherein 4. The side slip angle detecting means includes: a plurality of sideslip angle detectors for detecting the sideslip angle of the vehicle; and a weighted average of a plurality of sideslip angles detected by the plurality of sideslip angle detectors. The vehicle side slip angle detection device according to any one of claims 1 to 3, further comprising a weighted average unit that sets a side slip angle as a detection value of the angle detection unit. 5. A first sideslip angle detecting section for obtaining a sideslip angle of a vehicle by calculation using a two-wheel model of a vehicle as the plurality of sideslip angles detecting sections, and a second side for obtaining a sideslip angle of the vehicle using an observer. A side slip angle detection unit, wherein the weighted averaging unit calculates a weighted average of the sideslip angles detected by the first and second sideslip detection units according to a yaw rate, and calculates a weighted average as a detection value of the sideslip angle detection unit. The side slip angle detecting device for a vehicle according to claim 4, wherein the side slip angle is set.