JPH06336173A - Abnormality discriminating device for yaw rate detecting means - Google Patents

Abstract

PURPOSE:To detect abnormalities, including an abnormality that the detected value is too small, over a wide range when only one, not two, yaw rate detecting means is provided. CONSTITUTION:When the front wheel steering angle deltaF of a vehicle 1 is given, the rear wheel steering angle deltaR is given as the sum of the feed-forward quantity from a circuit 5 and the feedback quantity from a circuit 6 corresponding to the yaw rate detected value gammar of a sensor 4. A circuit 9 determines the yaw rate estimated value gammac from the front wheel steering angle deltaF and the vehicle speed V, and a differentiating circuit 10 calculates its change rate (d/dt) gammar. A differentiating circuit 11 differentiates the yaw rate detected value gammar of the sensor 4 and calculates its change rate (d/dt). A circuit 12 determines the absolute value D of the difference between both change rates, and a circuit 13 judges the sensor 4 as abnormal when the deviation D is the reference value R or above. A circuit 7 fixes the feedback quantity of the circuit 6 when the sensor 4 is judged as abnormal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for determining an abnormality in a yaw rate detecting means used in a vehicle yaw rate feedback type auxiliary steering apparatus or the like.

[0002]

2. Description of the Related Art Conventionally, as this type of abnormality discriminating apparatus, for example, one disclosed in Japanese Patent Laid-Open No. 3-253467 is known.

This device determines that the yaw rate sensor has caused an abnormality such as a failure, or the like, when the detected value of the yaw rate sensor shows a sudden change exceeding the yaw rate change that can occur in the vehicle. 2 yaw rate sensors
The sensors are installed as a set, and when the difference between the detection values of both sensors exceeds the set value, it is determined that the sensor is abnormal.

[0004]

However, in the former abnormality determination device, when the yaw rate sensor has a failure that reduces the detection value, this failure cannot be detected. Also,
The latter abnormality determination device has a problem in that it requires two yaw rate sensors, which are expensive per se, which increases the cost.

According to the present invention, the yaw rate detecting means is determined by estimating the yaw rate of the vehicle and comparing the estimated rate of change of the yaw rate with the rate of change of the detected yaw rate to determine the abnormality of the yaw rate detecting means. An object of the present invention is to eliminate the above-mentioned problem by making it possible to detect an abnormality in a wide range including an abnormality in which a detected value becomes small, even if the individual pieces are not provided.

[0006]

For this purpose, an abnormality determining device for yaw rate detecting means according to the present invention has a steering angle detecting means for detecting a steering angle of a steering wheel and a vehicle speed detecting means, as the concept is shown in FIG. A vehicle speed detecting means, a yaw rate estimating means for estimating the yaw rate of the own vehicle based on the vehicle model of the own vehicle from the detected values of these means, and an estimated yaw rate change rate calculating means for calculating the change rate of the yaw rate estimated value, Yaw rate detection means for detecting the actual yaw rate of the vehicle, detected yaw rate change rate calculation means for calculating the change rate of the detection value by the means, and estimated yaw rate change calculated by the detected yaw rate change rate and the estimated yaw rate change rate calculation means. A yaw rate change rate deviation calculating means for obtaining a deviation between the rates, and when the deviation is equal to or more than a preset reference value, It is characterized in that the rate detecting means comprises an abnormality determination means for determining the abnormality.

[0007]

The yaw rate estimating means estimates the yaw rate of the own vehicle based on the vehicle model of the own vehicle from the detected values of the steering wheel steering angle and the vehicle speed detected by the steering angle detecting means and the vehicle speed detecting means. Then, the estimated yaw rate change rate calculation means calculates the estimated yaw rate change rate from the estimated yaw rate obtained by this means.

On the other hand, the detected yaw rate change rate calculation means is
The change rate of the detected value of the actual yaw rate detected by the yaw rate detecting means is calculated.

The yaw rate change rate deviation calculating means obtains a deviation between the detected yaw rate change rate calculated by the detected yaw rate change rate calculating means and the estimated yaw rate change rate calculated by the estimated yaw rate change rate calculating means. When this deviation is equal to or greater than a preset reference value, it is determined that the yaw rate detecting means is abnormal.

By the way, since the yaw rate of the own vehicle is estimated and the abnormality rate of the yaw rate detecting means is determined by comparing the change rate of the estimated yaw rate with the change rate of the detected yaw rate, two yaw rate detecting means are used. Even if it is not provided, the abnormality can be detected in a wide range including the abnormality in which the detected value becomes small, and the above-mentioned conventional problems can be eliminated.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows an embodiment of the abnormality determining device of the present invention used in a yaw rate feedback type rear wheel auxiliary steering device for a vehicle. In this figure, 1 indicates a vehicle, which is given a front wheel steering angle δ _F accompanying a steering input (steering angle) θ from a steering wheel (not shown), and
Given the rear wheel steering angle δ _R , the sideslip angle β and yaw rate γ are generated.

Here, the rear wheel rudder angle δ _R is, for example, "Automobile Technology" Vol. 45, No. It is determined as follows in a well-known manner described in 3. Therefore, the front wheel steering angle sensor 2 as the steering angle detecting means, the vehicle speed sensor 3 as the vehicle speed detecting means, and the yaw rate sensor as the yaw rate detecting means for respectively detecting the front wheel steering angle δ _F , the vehicle speed V, and the actual yaw rate γ. 4, a feedforward control gain circuit 5, a feedback control gain circuit 6, a peak hold circuit 7 used for abnormality processing at the time of abnormality detection described later, and a differential amplifier 8 are provided in association with these sensors. It constitutes a wheel steering angle control device.

The feedforward control gain circuit 5 calculates the feedforward control gain K _F.

[Formula 1] K _F = −C _F / C _R (1) where C _{F is the} front wheel cornering power C _{R is the} rear wheel cornering power, and this is the front wheel steering angle δ detected by the sensor 2. _F
The multiplication value (feedforward amount) K _F · δ _F of is input to the differential amplifier 8.

Further, the feedback control gain circuit 6
Is the feedback control gain K _B based on the vehicle speed V detected by the sensor 3.

[Number 2] _{K B = {2 (aC F} -bC R) + mV 2} / 2C R V ···· (2) where, a: distance between the center of gravity, front axle b: distance between the axes after the center of gravity, m: Calculated from the vehicle body weight and multiplied by the detected value γ _r of the actual yaw rate γ detected by the sensor 4 (feedback amount) K _B ·
γ _r is input to the differential amplifier 8. The peak hold circuit 7 continues to input the feedback amount K _B · γ _r to the differential amplifier 8 as it is until an abnormality is detected as described later.

The differential amplifier 8 calculates the rear wheel steering angle δ _R by summing the above feedforward amount K _F · δ _F and feedback amount K _B · γ _r , and steers the rear wheels by this calculated steering angle.

The abnormality of the yaw rate sensor 4 which is the yaw rate detecting means is determined by the following structure. Therefore, the vehicle body model calculation circuit 9 as the yaw rate estimation means, the differentiation circuit 10 as the estimated yaw rate change rate calculation means, the differentiation circuit 11 as the detected yaw rate change rate calculation means, and the difference as the yaw rate change rate deviation calculation means. A circuit 12 and a comparator 13 as an abnormality determining means are provided.

Here, by steering the front and rear wheels of the vehicle 1 as described above, the yaw rate generated in the vehicle can be estimated from the two-wheel model of FIG. 3 as follows. That is, S is the Laplace operator, θ is the steering angle of the steering wheel determined from the front wheel steering angle δ _F and the steering gear ratio N by N · δ _F , the moment of inertia about the vehicle center of gravity O is I, the wheel base is L, and the two-wheel vehicle is Where K is the stability factor of, the yaw rate response (yaw rate gain) γ _C (S) / θ (S) with respect to the steering angle θ is

## EQU3 ## γ _C (S) / θ (S) = γ _O / (T · S + 1) (3)

[Formula 4] T = I · V / (2L · a · C _F + b · m · V ² ) ... (4)

[Number 5] _{γ O = V (1-K} F) / NL (1 + KV 2 + K B V) ··· (5)

[6] _{K = -m (aC F -bC R} ) / 2L 2 · C F · C R that can be obtained by (6), therefore, generated in the vehicle based on the steering angle θ and the vehicle speed V The yaw rate that would be possible can be estimated as γ _C.

Based on this idea, the vehicle body model calculation circuit 9 detects the front wheel steering angle δ _F and the vehicle speed V detected by the sensors 2 and 3.
Based on the above, the yaw rate estimated value γ _C is obtained by the calculation of the above equations (3) to (6). The differentiating circuit 10 time-differentiates the estimated yaw rate value γ _C to obtain a rate of change (d / d).
t) Calculate γ _C.

The other differentiating circuit 11 differentiates the yaw rate detection value γ _r of the sensor 4 with respect to time, and changes its rate (d / d).
t) Calculate γ _r .

The difference circuit 12 calculates the estimated yaw rate change rate (d / dt) γ _C and the detected yaw rate change rate (d).
/ Dt) γ _r , the absolute value D of the difference is D = | (d / dt) γ _C
-(D / dt) γ _r |

When the difference D is equal to or greater than the reference value R, the comparison circuit 13 determines that the yaw rate sensor 4 is abnormal, and if the abnormality does not continue to be solved for a set time or longer, the abnormal signal T _r is peak-held. It shall be applied to the circuit 7. The peak hold circuit 7 inputs a feedback amount K _B · γ _r from the circuit 6 to the differential amplifier 8 while the abnormal signal is input.
Is fixed to the value at the time of abnormality determination.

In the above embodiment, the operation when the steering angle θ of the steering wheel is changed from 0 degree to 30 degrees as shown in FIG. 4 will be described with reference to FIG.

When the abnormality of the yaw rate detecting means is detected and no countermeasure is taken against this abnormality, the yaw rate detection value γ _r is suddenly changed at the instant t _{0 due} to the abnormality and the rear wheel steering angle δ _R
Then, as shown by δ _R 'in FIG. 4, a sudden change is caused to cause unnatural vehicle behavior.

In this example, in the event of such an abnormality, the abnormality is discriminated and countermeasures are taken as follows. That is, the vehicle body model calculation circuit 9 obtains the yaw rate estimated value γ _C from the front wheel steering angle δ _F detected by the sensors 2 and 3 and the vehicle speed V by the calculation of the equations (3) to (6) as shown in FIG. . The differentiating circuit 10 differentiates the estimated yaw rate value γ _C with respect to time, and the change rate (d / dt) γ _C
Is calculated as shown in FIG. On the other hand, the differentiating circuit 11 differentiates the yaw rate detection value γ _r of the sensor 4 with respect to time to calculate the change rate (d / dt) γ _r as shown in FIG.

The difference circuit 12 calculates the estimated yaw rate change rate (d / dt) γ _C and the detected yaw rate change rate (d).
/ Dt) γ _r , the absolute value D of the difference is D = | (d / dt) γ <sub>C
- (d / dt) γ r</sub> | determined by, comparing circuit 13, when the yaw rate change rate deviation D is greater than or equal to the reference value R, it is determined that the yaw rate sensor 4 is abnormal, abnormal as shown in FIG. 4 _{Emits a} signal T _r . Even if the yaw rate change rate deviation D momentarily becomes less than the reference value R, the abnormal signal _Tr continues to be output unless this state continues for a set time or longer.

By the way, according to this abnormality determination method,
The yaw rate of the host vehicle is estimated (estimated value γ _C ), and the estimated yaw rate change rate (d / dt) γ _C and the detected yaw rate γ _r
Since the abnormality of the yaw rate sensor 4 is determined from the comparison with the change rate (d / dt) γ _{r of} (4), the abnormality is detected in a wide range including the abnormality in which the detection value becomes small without providing two yaw rate sensors 4. be able to.

The abnormal signal T _r is applied to the peak hold circuit 7, and the peak hold circuit 7 supplies the feedback amount K _B · γ _r from the circuit 6 to the differential amplifier 8 while the abnormal signal is input. As shown in FIG. 4, the value can be fixed to the value at the time of abnormality determination to eliminate a feeling of strangeness in which the vehicle behavior suddenly changes when the yaw rate sensor 4 is abnormal.

The abnormality processing is performed when the yaw rate change rate deviation D continuously becomes less than the reference value R or when the steering angle θ
When the yaw rate change rate deviation D continuously becomes less than the reference value R, the normal rear wheel assist steering control is resumed and the steering angle θ becomes zero. Alternatively, when it approaches 0, the feedback amount K _B · γ _r from the circuit 6 to the differential amplifier 8 is returned to 0.

According to such abnormality processing, Japanese Patent Laid-Open No. 62-1 is used.
As in the conventional processing disclosed in Japanese Patent No. 39756, the rear wheel steering angle that is fixed when the yaw rate sensor is abnormal continues to continue even after the transition to straight running, which causes an adverse effect of generating unnecessary yaw rate in the vehicle. There is no. Also,
In the conventional abnormality processing described in JP-A-4-135980, since the rear wheel steering angle is set to 0 when the yaw rate sensor is abnormal, there is no problem when an abnormality occurs while the rear wheel steering angle is decreasing. Although the vehicle behavior cannot avoid a sudden change when an abnormality occurs while the rear wheel steering angle is increasing, the abnormality processing of the present embodiment does not cause such an adverse effect.

[0030]

As described above, the abnormality determining device for the yaw rate detecting means according to the present invention estimates the yaw rate of the own vehicle and compares the rate of change of the estimated yaw rate with the rate of change of the detected yaw rate. Since the abnormality of the yaw rate detecting means is determined from the above, it is possible to detect the abnormality in a wide range including the abnormality in which the detection value becomes small without providing two yaw rate detecting means, and it is possible to eliminate the above-mentioned conventional problems. it can.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an abnormality determination device of a yaw rate detection means according to the present invention.

FIG. 2 is a schematic system diagram of a vehicle rear wheel steering system showing an embodiment of the abnormality determination device of the present invention.

FIG. 3 is a two-wheel model diagram used for calculating a yaw rate estimated value in the same example.

FIG. 4 is an operation time chart of the abnormality determination device in the same example.

[Explanation of symbols]

 1 vehicle 2 front wheel steering angle sensor (steering angle detecting means) 3 vehicle speed sensor (vehicle speed detecting means) 4 yaw rate sensor (yaw rate detecting means) 5 feedforward control gain circuit 6 feedback control gain circuit 7 peak hold circuit 8 differential amplifier 9 vehicle body Model calculation circuit (yaw rate estimation means) 10 Differentiation circuit (estimated yaw rate change rate calculation means) 11 Differentiation circuit (detected yaw rate change rate calculation means) 12 Difference circuit (yaw rate change rate deviation calculation means) 13 Comparator (abnormality determination means)

Claims (1)

[Claims] 1. A steering angle detecting means for detecting a steering angle of a steering wheel, a vehicle speed detecting means for detecting a vehicle speed, and a yaw rate estimation for estimating a yaw rate of the own vehicle from a detection value of these means based on a vehicle model of the own vehicle. Means, an estimated yaw rate change rate calculating means for calculating a change rate of the estimated yaw rate, a yaw rate detecting means for detecting an actual yaw rate of the vehicle, and a detected yaw rate change rate calculating means for calculating a change rate of the detected value by the means. And a yaw rate change rate deviation calculating means for obtaining a deviation between the detected yaw rate change rate and the estimated yaw rate change rate calculated by the estimated yaw rate change rate calculating means, and when the deviation is equal to or greater than a preset reference value, A yaw rate detecting means, characterized in that the yaw rate detecting means includes an abnormality determining means for determining that the yaw rate detecting means is abnormal. Abnormality determination device.