JP3694104B2 - Yaw rate sensor fault diagnosis device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a yaw rate sensor failure diagnosis apparatus for diagnosing a failure of a yaw rate sensor used for feedback control of vehicle behavior.
[0002]
[Prior art]
The rear wheel steering angle is controlled by feedback control (hereinafter referred to as F / B control) so that the model yaw rate value calculated from the front wheel steering amount of the driver and the actual yaw rate value detected by the yaw rate sensor are matched. A configured four-wheel steering system is known (refer to Japanese Patent Laid-Open No. 7-237557). A vehicle that controls the vehicle behavior by this type of F / B control cannot perform normal F / B control if the sensor that detects the actual yaw rate becomes abnormal. Therefore, in the specification of Japanese Patent Application No. 7-180909, the present applicant compares the estimated yaw rate value obtained from the difference between the left and right rotational speeds of the driven wheel with the output value of the yaw rate sensor, and the deviation is a predetermined reference. We proposed a yaw rate sensor fault diagnosis device that diagnoses the sensor depending on whether the value was exceeded.
[0003]
[Problems to be solved by the invention]
However, according to the above technique, for example, when driving on a rough road such as a gravel road, the left-right speed difference of the driven wheel changes irregularly, so the yaw rate estimated value based on this becomes suspicious, and the estimated value and the actual value are The failure diagnosis itself to be compared may be unreliable. Therefore, even when the yaw rate sensor does not break down when traveling on a rough road, there is a possibility that a misdiagnosis that is diagnosed as a failure occurs and the F / B control based on the yaw rate cannot be performed.
[0004]
An object of the present invention is to provide a yaw rate sensor failure diagnosis device that can solve such problems of the prior art and reliably perform failure diagnosis even when traveling on a rough road.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, the present invention provides a failure of a yaw rate sensor for detecting an actual yaw rate used for feedback control of vehicle behavior so as to match at least a model yaw rate calculated from a steering amount of a steered wheel. In a yaw rate sensor failure diagnosis device that diagnoses the road surface based on the deviation between the estimated yaw rate value obtained from the difference between the left and right rotational speeds of the driven wheel and the output value of the yaw rate sensor, a rough road determination that discriminates the road surface irregularities comprising means, as the reference value used for fault diagnosis of the yaw rate sensor, in the case of good road uses a value obtained based on the estimated yaw rate value, when the rough road judgment has been made is the good road In this case , a constant value that is higher than the reference value and is irrelevant to the estimated yaw rate value is set.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0007]
A block diagram of a fault diagnosis system for a yaw rate sensor according to the present invention is shown in FIG. In this fault diagnosis system, the deviation between the actual yaw rate value γ _SENS output from the yaw rate sensor 1 and the estimated yaw rate value γ _KALM obtained from the left-right speed difference of the driven wheel is calculated, and the absolute value processing is performed on this value. A value obtained by adding 2 is input to the failure diagnosis block 3 as an error amount γ _ER . In the failure diagnosis block 3, it is determined whether or not the error amount γ _ER obtained from the deviation between the actual yaw rate value γ _SENS and the estimated yaw rate value γ _KALM is greater than or equal to a threshold value γ _SHF set as a reference value for failure diagnosis. At the same time, it is determined whether or not the state above the threshold has continued for a predetermined time. If the error amount γ _ER exceeds the threshold γ _SHF for a predetermined time, the yaw rate sensor 1 has failed. Make a diagnosis of what you have. If the error amount γ _ER is less than or equal to the threshold value γ _SHF or if the duration is shorter than the threshold value γ _SHF , the yaw rate sensor 1 makes a diagnosis that it is normal.
[0008]
The estimated yaw rate value γ _KALM first sets the yaw rate conversion gain by setting the deviation between the left rear wheel speed signal and the right rear wheel speed signal from the rear wheel speed sensors 4L and 4R provided to the left and right rear wheels as the driven wheels, respectively. The static estimated yaw rate signal γ _VW is obtained by multiplying it by a coefficient obtained in advance by experiment. Next, the static estimated yaw rate signal γ _VW is input to the Kalman filter 8 together with the steering angle signal θ _SW from the steering angle sensor 6 and the rear steering angle signal θ _R from the rear steering angle sensor 7, and the dynamic estimated yaw rate signal γ Convert to _EST .
[0009]
On the other hand, the static estimated yaw rate signal γ _VW and the dynamic estimated yaw rate signal γ _EST are input to the nonlinear region compensation block 9 to obtain a linearly compensated signal, which is added to the dynamic estimated yaw rate signal γ _EST. In addition, by performing absolute value processing, an estimated yaw rate value γ _KALM used for comparison with the actual yaw rate value γ _SENS is obtained.
[0010]
Since the signal accuracy from the rear wheel speed sensors 4L and 4R deteriorates during rough road driving, the linearly compensated signal is excluded from the estimated yaw rate value γ _KALM by turning off the switch means 10 during bad road determination described later. Is done.
[0011]
On the other hand, the linearly compensated signal is subjected to dead band processing 11 and absolute value processing 12 in order to remove harmful noise generated near the neutral point of the yaw rate sensor due to vehicle vibration etc. The base value of The base value of this threshold value is also excluded from the threshold value when a rough road determination is made.
[0012]
The present system is provided with a rough road determination block 14 for determining an irregular road surface condition. Regarding this rough road determination, since the method disclosed in Japanese Patent Laid-Open No. 64-29636 can be applied, detailed description is omitted here, but roughly speaking, when traveling on a rough road, the difference between the left and right wheel speeds of the driven wheels Is noisy compared to when driving on a good road, and is obtained from the static estimated yaw rate signal γ _VW obtained from the deviation of the outputs of the left and right rear wheel speed sensors 4L and 4R via a bandpass filter. A specific frequency component is extracted, and the absolute value of the signal is compared with a predetermined threshold value for determining a rough road. If it is larger than the threshold value, it is determined that the road is a bad road. Note that the determination threshold value is preferably changed according to the vehicle speed and the lateral acceleration because the wheel speed also changes depending on the traveling state of the vehicle when traveling on a rough road.
[0013]
When it is determined that the current state is traveling on a rough road according to the determination result in the rough road determination block 14, the switch means 15 for selecting the added value of the failure diagnosis threshold value is switched, and normally 3 deg / s. Is output as an added value, but 30 deg / s is output. In other words, when a failure diagnosis reference value obtained by adding 3 deg / s to the base threshold value on a normal good road is determined as a bad road, the reference value is uniformly replaced with 30 deg / s. As a result, the reference value used for the failure diagnosis of the yaw rate sensor 1 is set to be larger than the normal value when traveling on a rough road, thereby preventing erroneous diagnosis.
[0014]
【The invention's effect】
As described above, according to the present invention, when driving on a rough road, the failure diagnosis threshold value of the yaw rate sensor is increased from that in the normal state, thereby improving the certainty of the failure diagnosis and resulting from a misdiagnosis during the rough road driving. It is prevented that the F / B control based on the yaw rate is not performed. Therefore, a great effect can be obtained in ensuring the stability of the control.
[Brief description of the drawings]
FIG. 1 is a control block diagram of a yaw rate sensor failure diagnosis apparatus according to the present invention.
DESCRIPTION OF SYMBOLS 1 Yaw rate sensor 2 Absolute value process 3 Fault diagnosis block 4 Wheel speed sensor 5 Yaw rate conversion gain setting machine 6 Steering angle sensor 7 Rear rudder angle sensor 8 Kalman filter 9 Non-linear area compensation block 10 Switch means 11 Dead zone process 12 Absolute value process 14 Bad road Determination block 15 switch means

Claims (1)

The failure of the yaw rate sensor for detecting the actual yaw rate used for feedback control of the vehicle behavior so as to match at least the model yaw rate calculated from the steering amount of the steered wheel was obtained from the difference in rotational speed between the left and right of the driven wheel. A yaw rate sensor failure diagnosis device for diagnosing based on a deviation between an estimated yaw rate value and an output value of the yaw rate sensor,
Provided with rough road determination means for determining road surface irregularity conditions, in the case of a good road, a reference value used for failure diagnosis of the yaw rate sensor , using a value obtained based on the estimated yaw rate value,
Rough road when the determination has been made, the good road yaw rate sensor failure diagnosis apparatus characterized by setting the independent constant value high and the estimated yaw rate values than the reference value in the case of.

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