JP3147639B2 - Vehicle behavior detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle behavior detecting device, and more particularly to a vehicle behavior detecting device for detecting a vehicle behavior such as a yaw rate occurring in a vehicle.

[0002]

2. Description of the Related Art Conventionally, there has been known a technique for improving a turning performance by controlling a brake or the like when a vehicle turns.
For example, in Japanese Patent Application Laid-Open No. 3-276852, a target yaw rate is set based on the vehicle speed and the steering angle, and the braking force of each wheel is controlled so that the detected actual yaw rate of the vehicle matches the target yaw rate.

The actual yaw rate of a vehicle can be detected by a yaw rate gyro sensor. However, since the yaw rate gyro sensor is expensive, the yaw rate is estimated based on the output value of the acceleration sensor.

For example, Japanese Unexamined Patent Publication No. 2-70561 discloses a system in which a pair of acceleration sensors for detecting lateral acceleration are provided at the front and rear of a vehicle body. Is described.

[0005]

In the conventional method of calculating the yaw angular velocity using the acceleration detected by a pair of acceleration sensors, the yaw rate of the vehicle can be obtained only by integrating the yaw angular velocity with time. For this reason, there has been a problem that a quantization error when the output signal of the acceleration sensor is digitized for calculation is also integrated, and it is difficult to estimate a yaw rate with high accuracy.

[0006] The present invention has been made in view of the above points,
It is an object of the present invention to provide a vehicle behavior detecting device that can detect the magnitude of a yaw rate without the need for time integration by calculating the magnitude of a yaw rate from the detection values of a pair of acceleration sensors, and that can perform high-precision detection with a small error. Aim.

[0007]

In the present invention, a pair of acceleration detecting means are provided at positions separated from each other on a straight line on the plane of the vehicle, and detect the acceleration in the straight line direction.

[0008] The yaw rate calculation means calculates the magnitude of the yaw rate of the vehicle based on the acceleration detected by the pair of acceleration detection means.

[0009]

In the present invention, since the magnitude of the yaw rate is calculated from the detection values of the pair of acceleration sensors, the magnitude of the yaw rate can be detected without the need for time integration. Accuracy can be detected.

[0010]

FIG. 1 is a block diagram of a first embodiment of the apparatus of the present invention. In the figure, longitudinal acceleration sensors 11 and 12 are attached at a distance L on a straight line extending in the longitudinal direction passing through the center of gravity 0 of the vehicle 10. The detection signals of the acceleration sensors 11 and 12 are supplied to a microcomputer 15 as a yaw rate calculating means.

As shown in FIG. 2, when the vehicle moves at the position of the center of gravity at the speed V (x component Vx, y component Vy) and the yaw rate γ, the equation of the vehicle motion is expressed by the following equation.

Gx = ΔVx−Vy · γ (1a) Gy = ΔVy + Vx · γ (1b) The x component Vx ₁ and y component Vy ₁ of the velocity at the position (a ₁ , 0), the longitudinal acceleration Gx ₁ , and the position At (a ₂ , 0), the x component Vx ₂ and y component Vy ₂ of the velocity, the longitudinal acceleration Gx ₂ , where a ₂ <0, and the center of gravity (0, 0),
When the x component Vx ₀ and the y component Vy _{0 of the} velocity are represented by Δ, the ΔVx and Vy at the positions (a ₁ , 0) and (a ₂ , 0) are represented by the following equations.

Vy ₁ = Vy ₀ + a ₁ · γ Vy ₂ = Vy ₀ + a ₂ · γ ΔVx ₁ = ΔVx ₀ ΔVx ₂ = ΔVx ₀ (2) By substituting equation (2) into equation (1a), Gx ₁ = ΔVx _0- (Vy ₀ + a ₁ · γ) · γ Gx ₂ = ΔVx _0- (Vy ₀ + a ₂ · γ) · γ (3) From this, γ ² = − (Gx ₁ −Gx ₂ ) / ( a ₁ −a ₂ ) (4) However, (Gx ₁ −Gx ₂ ) is always negative regardless of the direction of the yaw rate γ. Here, since a ₁ -a ₂ = L,

[0014]

(Equation 1)

Difference in longitudinal acceleration shown in equation (5)
(Gx ₁ −Gx ₂ ) and the yaw rate γ have the relationship shown in FIG.

The absolute value of the yaw rate γ can be obtained by performing the calculation of the equation (5) by the microcomputer 15 shown in FIG. In this case, the direction of the yaw rate is not known, but when the cornering limit is determined and the front-rear distribution control of the braking force is performed, or when the front and rear roll rigidity distribution control is performed, the absolute value of the yaw rate γ may be known. .

As described above, in this embodiment, since the yaw rate absolute value | γ | can be calculated without performing time integration,
No quantization error is accumulated in the obtained yaw rate absolute value | γ |, and the yaw rate absolute value | γ | can be detected with high accuracy.

As can be seen from equation (4), L = a ₁ −a ₂
Is larger, (Gx ₁ -Gx ₂ ) becomes larger and the measurement error becomes smaller. In order to increase the distance L, sensors 11 and 12 for detecting diagonal acceleration in a diagonal direction of the vehicle may be attached as shown in FIG.

FIG. 5 is a block diagram of a second embodiment of the apparatus of the present invention. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals. In FIG. 5, instead of the longitudinal acceleration sensors 11 and 12, respectively, longitudinal and lateral acceleration sensors 16 and 17 are attached at a distance L in the longitudinal direction passing through the center of gravity 0 of the vehicle 10. The longitudinal accelerations Gx ₁ and Gx ₂ and the lateral accelerations Gy ₁ and Gy ₂ detected by the sensors 16 and 17 are supplied to the microcomputer 15.

FIG. 6 shows a flowchart of the yaw rate calculation processing executed by the microcomputer 15. This process is executed, for example, every several msec to several tens msec. In FIG. 10, in step S10, the equation (5) is calculated using the longitudinal accelerations Gx ₁ and Gx ₂ obtained by the sensors 16 and 17, respectively, to calculate the yaw rate absolute value | γ |. In the next step S20, the differential value d | γ | / dt is calculated by taking the difference between the previously calculated yaw rate absolute value and the currently calculated yaw rate absolute value.

In step S30, the lateral accelerations Gy ₁ and Gy obtained by the sensors 16 and 17 based on the conventional method are respectively obtained.
_The yaw angular velocity dγ / dt is calculated by the following equation using ₂ .

Dγ / dt = (Vy ₁ −Vy ₂ ) / L (6) Here, with respect to the actual yaw rate γ shown by the solid line in FIG. 7A, the yaw rate absolute value | γ | In a relationship. Also, yaw angular velocity dγ / d obtained by differentiating yaw rate γ
7B changes as indicated by the solid line, while the differential value d | γ | / dt of the absolute value of the yaw rate becomes as indicated by the broken line, and dγ / dt when the yaw rate γ is positive (leftward).
And d | γ | / dt have the same sign and the sign of dγ / dt and d | γ | / dt are different when the yaw rate γ is negative (to the right).

In step S40, d | γ | / dt and dγ / d obtained in steps S20 and S30 based on the above principle
It is determined whether or not the signs of t are the same. If the signs are different, a negative sign is added to the yaw rate absolute value | γ | in step S50, and the process is terminated if the signs match, and in step S60, the yaw rate absolute value | γ | The process is terminated with a positive sign.

In this embodiment, the yaw rate γ including the sign can be obtained with high accuracy without time integration.

Further, in the third embodiment shown in FIG.
Lateral acceleration near zero center of gravity with acceleration sensors 11 and 12
A degree sensor 18 is provided.
Data 15. The microcomputer 15
Detection values Gx of the sensors 11 and 12 ₁, Gx_TwoFrom equation (5)
After calculating the yaw rate absolute value | γ |
The absolute value of the yaw rate |
The yaw rate γ can be obtained by adding γ |.

FIG. 9 is a block diagram showing a fourth embodiment of the apparatus of the present invention. In the figure, a distance L in the lateral direction passing through the center of gravity 0 of the vehicle 10 is shown.
The lateral acceleration sensors 21 and 22 are attached at a distance from each other. The detection signals of the acceleration sensors 21 and 22 are supplied to the microcomputer 15.

In this case, FIG. 2 is rotated by 90 degrees clockwise around the center of gravity 0, and the distance L is set across the center of gravity 0 on the y-axis.
(0, b ₁ ) and (0, b ₂ ), where b ₂ <0. Position (0, b ₁ ),
ΔVy and Vx at (0, b ₂ ) are represented by the following equations.

ΔVy ₁ = ΔVy ₀ ΔVy ₂ = ΔVy ₀ Vx ₁ = Vx ₀ -b ₁ · γ Vx ₂ = Vx ₀ -b ₂ · γ By substituting the above expression into the expression (1b), Gy ₁ = ΔVy ₀ + ( Vx ₀ −b ₁ · γ) · γ Gy ₂ = ΔVy ₀ + (Vx ₀ −b ₂ · γ) · γ The following equation is obtained.

[0029]

(Equation 2)

In the microcomputer 15, the sensor 2
After calculating the yaw rate absolute value | γ | from the detected values Gy ₁ and Gy _{2 of} the sensors 21 and 22 by the equation (7), the sensors 21 and 22 are used.
The average value of the detected values Gy ₁ and Gy ₂ of Gy is set as Gy, and the sign of this average value Gy is directly added to the yaw rate absolute value | γ |

In this embodiment, the yaw rate γ can be obtained only by the two lateral acceleration sensors 21 and 22.

[0032]

As described above, according to the vehicle behavior detecting device, the magnitude of the yaw rate can be detected without time integration by calculating the magnitude of the yaw rate from the detection values of the pair of acceleration sensors. Is detected without time integration of the yaw angular velocity, so that errors do not accumulate, the errors are small, and the yaw rate can be detected with high accuracy, which is extremely useful in practice.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a diagram for explaining the principle of the present invention.

FIG. 3 is a diagram illustrating a relationship between a yaw rate and longitudinal acceleration.

FIG. 4 is a diagram for explaining a mounting position of a sensor.

FIG. 5 is a configuration diagram of the present invention.

FIG. 6 is a flowchart of a yaw rate calculation process.

FIG. 7 is a diagram for explaining the present invention.

FIG. 8 is a configuration diagram of the present invention.

FIG. 9 is a configuration diagram of the present invention.

[Explanation of symbols]

 10 vehicle 11,12,16,17,21,22 acceleration sensor 15 microcomputer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01P 15/00-15/08 B62D 6/00-6/06

Claims (1)

(57) [Claims] 1. A pair of acceleration detecting means which are provided at positions separated from each other on a straight line on a plane of a vehicle and detect acceleration in the straight line direction, based on acceleration detected by the pair of acceleration detecting means. A yaw rate calculating means for calculating the magnitude of the yaw rate of the vehicle.