JP3385611B2 - Yaw rate detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yaw rate detecting device for detecting a yaw rate of a vehicle.

[0002]

2. Description of the Related Art A conventional device for detecting a yaw rate of a vehicle from an output of a sensor other than a yaw rate sensor is disclosed in Japanese Unexamined Patent Publication (Kokai) No. Hei 2 (1998).
-70561 gazette. This yaw rate detection device calculates a lateral velocity difference between the front and the rear of the vehicle by time-integrating the lateral acceleration difference between the front and the rear of the vehicle, which is obtained from a lateral acceleration sensor arranged in the front and rear of the vehicle, and detects the yaw rate from this. . Further, the yaw rate detection device that detects the yaw rate from the output of the wheel speed sensor is
It is described in JP-A-4-328029.

[0003]

However, since the output of the lateral acceleration sensor includes a zero point error, its time integrated value diverges, or even if the zero point error should be removed, the error in the integrated value due to the quantization error remains. Inevitable. Further, since the output of the wheel speed sensor contains high-frequency noise that is superimposed when the vehicle is traveling on a rough road, no matter which sensor output is used, the yaw rate cannot be accurately detected as it is.

The present invention has been made in view of the above problems, and an object thereof is to provide a yaw rate detecting device capable of detecting an accurate yaw rate.

[0005]

In order to solve the above-mentioned problems, a yaw rate detecting device according to the present invention is provided with left and right wheel speed sensors for detecting the left and right wheel speeds of a vehicle and spaced apart along the longitudinal direction of the vehicle. Means for detecting the first yaw rate based on the low-frequency component of the speed difference between the left and right wheels obtained from the outputs of the front and rear lateral acceleration sensors, and the vehicle front and rear directions obtained from the outputs of the front and rear lateral acceleration sensors. And a means for obtaining a yaw rate based on the first and second yaw rates, the means for detecting the second yaw rate on the basis of the time integration value of the high frequency component of the lateral acceleration difference.

According to this device, since the first yaw rate is detected based on the low frequency component of the speed difference between the left and right wheels, the influence of high frequency noise superimposed on the output of the wheel speed sensor during traveling on a bad road or the like is affected. Since the second yaw rate is suppressed and is detected based on the time integral value of the high frequency component of the lateral acceleration difference between the front and rear of the vehicle, the influence of the low frequency component of the lateral acceleration sensor output such as a zero point error is suppressed. Since the resulting yaw rate is based on these first and second yaw rates, it is possible to improve the accuracy of the components from the low frequency to the high frequency.

It is preferable that the yaw rate detecting device further comprises means for detecting the vehicle state from the obtained yaw rate and an output value of a yaw rate sensor arranged inside the vehicle for directly detecting the yaw rate. That is, according to the present device, it is possible to detect the vehicle state, for example, the vehicle behavior or sensor abnormality due to the difference between the obtained yaw rate and the output value of the yaw rate sensor. The vehicle status information detected in this way is
It can be used for attitude control of the vehicle and warning display to the driver.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A yaw rate detecting device according to an embodiment will be described below. The same elements or elements having the same function will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a yaw rate detecting device according to an embodiment.

This vehicle has four wheels (front wheels W _FL , W _FR , rear wheels W _RL , W) rotatably provided with respect to the vehicle body BDY.
_RR ). Left and right front wheels (driven wheels) W _FL, W _FR wheel speed sensor 1V respectively corresponding to the _L, 1V _R are provided respectively, and its output is proportional to the left and right wheel speeds. Here, the wheel speed sensors 1V _L, 1V _R detects the rotational speed of the electric / magnetic biological or optically wheels, and outputs a pulse corresponding to the rotational speed, the number of pulses per unit time in rotation speed Shall be proportional.

This vehicle is provided with front and rear lateral acceleration (G) sensors 2G _F and 2G _R , which are spaced apart along the vehicle front-rear direction, on the vehicle center line. Here, the lateral G sensor 2
It is assumed that G _F and 2G _R output a voltage proportional to the lateral acceleration of the vehicle. The distance (tread) between the left and right front wheels W _FL , W _FR is T, and the front and rear lateral G sensors 2G _F , 2G _R
The distance between them is L.

This vehicle is provided with a yaw rate sensor 3Y which is arranged inside the vehicle and directly detects the yaw rate. Here, the yaw rate sensor 3Y is a so-called vibration gyro and outputs a voltage proportional to the yaw rate.

Each sensor 1V _L , 1V _R , 2G _F , 2G _R , 3
The output from Y is input to an ECU (electronic control unit) 10 arranged inside the vehicle, and the ECU 10 displays the information on the display 4D based on the input information, or if necessary. Drive means for controlling the vehicle body behavior (for example, a brake, a suspension, etc.).
For example, when it is determined that the sensor is abnormal, the ECU 10 invalidates the control of the drive unit that is controlled based on the output of this sensor or reduces the effectiveness to control the drive unit. Alternatively, the ECU 10 can also estimate the behavior of the vehicle body such as the slip state from the obtained information and control the drive unit according to the estimated behavior.

In any case, it is necessary to detect the vehicle state first. Here, for simplicity, it is assumed that an example of the vehicle state is a sensor abnormality, and the ECU 10 has a function of displaying a sensor abnormality warning on the display 4D. The display 4D is an LED (light emitting diode), an LCD (liquid crystal display), or the like, and the warning display can be performed in any case.

FIG. 2 is a system configuration diagram of the vehicle shown in FIG. The outputs of the wheel speed sensors 1V _L and 1V _R are input to the left and right wheel speed calculation units 10a and 10b, respectively, from which wheel speeds V _WL , which are values that can be calculated in the subsequent circuit,
V _WR is output. These detected wheel speeds V _WL , V
_WR is input to the wheel speed estimation yaw rate calculation unit 10c,
An estimated yaw rate γ _W ′ calculated based on the input wheel speeds V _WL and V _WR is now output. The calculation formula in the wheel speed estimation yaw rate calculation unit 10c is as follows.

Γ _W ′ = (V _WR −V _WL ) / T The estimated yaw rate γ _W ′ calculated by the wheel speed estimated yaw rate calculation unit 10c is considered in consideration of superimposition of high frequency noise on the rough yaw rate when traveling on a rough road. , The low frequency component is more reliable. Therefore, in this device, the output estimated yaw rate γ _W 'is determined by the low-pass filter (LP
F) 10d, the LPF 10d outputs the low-frequency component as an estimated yaw rate γ _W (first yaw rate) from the wheel speed.

On the other hand, the outputs G _F and G _R of the lateral G sensors 2G _F and 2G _R are input to a difference calculating circuit 10e, such as a differential amplifier or a subtractor, which calculates a difference, and the difference calculating circuit 10e.
Is the difference between them, that is, the lateral acceleration difference ΔG ′ (= G _F
-G _R) to output. The output lateral accelerations G _F and G _R are
Includes zero point error. That is, the lateral G sensor 2G _F ,
Even if the 2G _R ideally produces a zero output in a horizontal state, its output does not become zero even in a horizontally stationary state of the vehicle due to a product error or an assembly error when mounting the sensor, and a zero point error from the sensor is generated. There is a case where a constant offset output (low frequency noise) is output. When this zero-point error is integrated over time, the integrated value diverges, so in this device, the obtained lateral acceleration difference ΔG ′ is input to the high-pass filter (HPF) 10f to reduce the low frequency of the lateral acceleration difference. The high-frequency component ΔG, which is more effective than the component, is now output. The high frequency component ΔG of the lateral acceleration difference is input to the lateral G estimated yaw rate calculation unit 10g, and the lateral G estimated yaw rate calculation unit 10g temporally integrates the high frequency component ΔG of the lateral acceleration difference,
By dividing this by the inter-sensor distance L, the estimated yaw rate (second yaw rate) γ _G from the lateral acceleration is output. The calculation formula in the lateral G estimated yaw rate calculation unit 10g is as follows.

Γ _G = ∫ (ΔG / L) dt First and second yaw rates γ _W , γ _G obtained as described above
Is input to the adder 10h, and the final estimated yaw rate γ = γ _W + γ _G is output. The estimated yaw rates γ _W and γ _G for which the low frequency component and the high frequency component are effective
In order to prevent divergence at the time of integration, LPF 10d and HPF 10f which are filters of second order or higher are used for the frequency separation.

The estimated yaw rate γ obtained as described above can be used alone for various controls, and thereby the accurate yaw rate can be estimated without installing the yaw rate sensor 3Y. However, even when the yaw rate sensor 3Y is installed, this can be used for the abnormality determination of the yaw rate sensor 3Y, for example. In this case, the yaw rate output γ _Y from the yaw rate sensor 3Y is input to the determination unit 10i together with the estimated yaw rate output γ.

The determination unit 10i determines the difference Δγ = γ _Y −γ.
When the difference Δγ is equal to or more than a predetermined value, the yaw rate sensor 3Y or a circuit on a path from the yaw rate sensor 3Y to the determination unit 10i,
Alternatively, the estimated yaw rate output γ is determined to be abnormal, and the determination result is output. Although this determination result can be used for vehicle stability control inside the ECU 10, this information is also displayed on the display 4D. That is, in the case of the above output abnormality, the display device 4D displays a warning to that effect. If it is determined that the output is abnormal,
It is also possible to specify which sensor output is abnormal by using other information and perform various controls using only the normal yaw rate output.

[0021] As described above, the yaw rate detecting device, the left and right wheel speed sensors 1V _L for detecting the left and right wheel speeds of the vehicle, 1V _R and the lateral acceleration of the front and rear, which are spaced apart along the longitudinal direction of the vehicle sensor 2G _F, 2G _R and the left and right wheel speed sensors 1V _L, means for detecting a first yaw rate gamma _W based on the low-frequency component of the velocity difference between the left and right wheels obtained from the output of 1V _R 10a, 10b, 10c, Means 10e, 10f, 10g for detecting the second yaw rate γ _G based on 10d and the time integration value of the high frequency component of the lateral acceleration difference between the front and rear of the vehicle obtained from the outputs of the front and rear lateral acceleration sensors 2G _F , 2G _R.
And a means 10h for obtaining the yaw rate γ based on the first and second yaw rates γ _W and γ _G.

In this device, the yaw rate γ obtained as a result is based on the first and second yaw rates γ _W and γ _G , so that the accuracy of the components from the low frequency to the high frequency can be improved.

Although the first and second yaw rates γ _W and γ _G are added in the above embodiment, the estimated yaw rate can be obtained by weighting them according to the accuracy of the sensor and adding them. It can be calculated. Further, the position of the filter can be changed as needed.

Further, the yaw rate detecting device has an output value γ _Y of the yaw rate thus obtained and a yaw rate sensor 3Y arranged inside the vehicle for directly detecting the yaw rate.
Further comprises means 10i for detecting the vehicle condition from
It is possible to detect vehicle behavior, sensor abnormality, and the like.

[0025]

As described above, according to the yaw rate detecting device of the present invention, since the means for obtaining the yaw rate based on the first and second yaw rates is provided, the accurate yaw rate can be detected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a yaw rate detection device according to an embodiment.

FIG. 2 is a system configuration diagram of the vehicle shown in FIG.

[Explanation of symbols]

1V _L, 1V _R ... wheel speed sensors, 2G _F, 2G _R ... lateral acceleration sensor, 10a, 10b, 10c, 10d ... first yaw rate detection means, 10e, 10f, 10g ... second yaw rate detection means, 10h ... yaw rate detection Means, 3Y ... Yaw rate sensor.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01P 15/00-15/18 G01C 19/58

Claims (2)

(57) [Claims] 1. Left and right wheel speed sensors for detecting the left and right wheel speeds of a vehicle, front and rear lateral acceleration sensors spaced apart in the vehicle front-rear direction, and left and right wheels obtained from the outputs of the left and right wheel speed sensors. Based on the low frequency component of the speed difference of
Means for detecting a yaw rate, means for detecting a second yaw rate based on a time integral value of a high frequency component of a lateral acceleration difference between the front and rear of the vehicle obtained from outputs of the front and rear lateral acceleration sensors, and the first and second yaw rates. And a means for obtaining a yaw rate based on the above. 2. The vehicle according to claim 1, further comprising means for detecting a vehicle state from the obtained yaw rate and an output value of a yaw rate sensor arranged inside the vehicle for directly detecting the yaw rate. Yaw rate detector.