JPH11148818A - Fault detection method for steering angle sensor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To detect a failure of a steering angle sensor early after turning a steering wheel. SOLUTION: A controller 1, a steering wheel angle sensor 2,
And the steering rack stroke sensor 3
A first steering angle and a second steering angle are obtained. First
If the absolute value of the difference between the steering angle and the second steering angle is equal to or larger than the threshold value, it is detected that the steering wheel angle sensor 2 and the steering rack stroke sensor 3 are out of order. The threshold value is reduced as the lateral G becomes smaller, within a range from zero to a threshold value set so that a failure is not erroneously detected during normal driving.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering angle sensor failure detecting method for detecting a steering angle sensor failure.

[0002]

2. Description of the Related Art In recent years, a first steering angle sensor and a second steering angle sensor respectively detect a first steering angle and a second steering angle of a vehicle, and these first steering angle and second steering angle are detected. When the absolute value of the difference from the steering angle is equal to or larger than a threshold value, a method has been proposed for detecting that the first steering angle sensor or the second steering angle sensor has failed (Japanese Patent Laid-Open No. 6-27863).
No. 9).

[0003]

In this case, however, the threshold value is set to such a value that the failure is not erroneously detected during normal running of the vehicle, that is, the steering system (torsion bar, column coupling, etc.) when the lateral G is sufficiently large. etc)
Is a fixed value determined according to the torsion element of Therefore, the failed steering angle sensor cannot be detected until the non-failed steering angle sensor operates normally, and the failure of the first steering angle sensor or the second steering angle sensor is determined by the steering. It is not always possible to detect early after turning off. Therefore, it is desired to detect a failure of the first steering angle sensor or the second steering angle sensor early after the steering is turned.

According to the first and second aspects of the present invention, there is provided a method for detecting a failure of a steering angle sensor.
It is an object of the present invention to solve the problem that the failure of the steering angle sensor cannot always be detected early after the steering is turned.

[0005]

According to a first aspect of the present invention, there is provided a method for detecting a failure in a steering angle sensor, comprising: a first steering angle sensor and a second steering angle sensor; 2 steering angles are detected, and if the absolute value of the difference between the first steering angle and the second steering angle is equal to or greater than a threshold value, the first steering angle sensor or the second steering angle sensor fails. When detecting that the lateral G is smaller, the threshold value is reduced within a range from zero to a threshold value set so that a failure is not erroneously detected during normal driving. It is.

According to a second aspect of the present invention, there is provided a method for detecting a failure of a steering angle sensor, wherein the threshold value which decreases as the lateral G decreases decreases as the steering speed decreases. It is.

[0007]

According to the steering angle sensor failure detecting method according to the first aspect of the present invention, the threshold value is set to zero by paying attention to the occurrence of the twist angle of the steering system which is balanced with the generated cornering force when the lateral G occurs. Within a range from the threshold value set so that a failure is not erroneously detected during normal driving.
Decrease as the value becomes smaller. The absolute value of the difference between the first steering angle and the second steering angle determined by the torsional element of the steering system of the vehicle decreases as the lateral G decreases. Therefore, the threshold value is smaller than a threshold value set so that a failure is not erroneously detected during normal traveling, and when the first steering angle sensor or the second steering angle sensor has failed, Since the absolute value of the difference between the first steering angle and the second steering angle exceeds the threshold value immediately after the driver turns the steering wheel, the failure of the first steering angle sensor or the second steering angle sensor Can be detected early after the driver turns the steering wheel.

According to the steering angle sensor failure detecting method according to the second aspect of the present invention, the threshold value which is decreased as the lateral G becomes smaller is decreased as the turning speed becomes slower. The absolute value of the difference between the first steering angle and the second steering angle has a relationship that decreases as the steering speed decreases. Therefore, when the steering speed is low, the threshold value that is decreased as the lateral G decreases becomes smaller than when the steering speed is not considered, and the first steering angle sensor or the second steering angle sensor can be used. Of the steering angle sensor can be detected more quickly.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for detecting a failure of a steering angle sensor according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a vehicle that implements a method for detecting a failure of a steering angle sensor according to the present invention. Vehicle controller 1
Includes a steering angle (hereinafter, referred to as a steering angle) corresponding to the first steering angle.
It is assumed that “steering angle θ1”. ), A signal from a steering angle sensor 2 as a first steering angle sensor, a signal from a steering rack stroke sensor 3 as a second steering angle sensor for detecting a rack stroke of a steering gear, and a yaw rate are detected. Yaw rate sensor 4
And a signal from the lateral G sensor 5 for detecting the lateral G are input.

The controller 1 performs the following various calculations based on signals from these sensors. The steering wheel angle sensor 2 is of a type that detects a pulse signal, and is disposed below the steering pad. The steering stroke sensor 3 detects a rack displacement of the steering gear, and the controller 1 equivalently calculates a steering value (hereinafter, referred to as “steering angle θ”) corresponding to the second steering angle based on the rack displacement.
2 ". ). Note that the steering stroke sensor 3 is disposed between the steering linkages 6a and 6b. Further, the yaw rate sensor 4 and the lateral G sensor 5
Is placed near the vehicle center of gravity.

FIG. 2 is a diagram showing a deviation between the steering wheel angle and the analog steering angle during the normal running with respect to the lateral G. This figure shows a state in which a side slip angle occurs and the tire cornering force is dominant with respect to the steering input. As shown in the drawing, the deviation (shift of the steering angle value) Δθ between the steering wheel steering angle and the analog steering angle during traveling is determined by the column joint play, the torsion of the rubber coupling, the T / BAR
It corresponds to the sum of the amount of twist, the amount of hiss of rack mount INSUL (rubber for stopping the gear), and the error of the rack-rack sensor, and increases as the lateral G increases.

In this case, the road surface friction coefficient is 1.0,
As the road surface friction coefficient decreases, the deviation of the steering angle value Δθ
Is also smaller. In addition, since there are linearity errors and A / D conversion errors of the analog sensor, it is necessary to consider these as deviations during traveling. That is, the threshold value Co for detecting the failure of the steering angle sensor is the sum of the deviation Δθ of the steering angle value, the linearity error of the analog sensor, and the AD conversion error.

The operation of the embodiment will be described. In this case, as shown in FIG. 3, consider a situation in which the vehicle 7 is steered from going straight. FIG. 4 is a flowchart of a first embodiment of a method for detecting a failure of a steering angle sensor according to the present invention. This routine is determined to be normal for both the steering wheel angle sensor 2 and the steering stroke sensor 3 (both shown in FIG. 1), and is corrected and then started once when the vehicle is traveling straight (for example, lateral G> 0.1) after ignition. Shall be.

First, in step S1, the steering wheel angle sensor 2 (FIG. 1) reads the steering angle θ1. Then
In step S2, the steering stroke sensor 3 (FIG. 1) detects the rack displacement of the steering gear,
The controller 1 (FIG. 1) obtains the steering angle θ2 based on the rack displacement. Next, in step S3,
The lateral G sensor 5 (FIG. 1) reads the lateral G value YG.

Next, in step S4, the horizontal G value Y
A threshold C is obtained based on G. As shown in FIG. 5, the threshold value C is within a range from zero to a threshold value Co that is set so that a failure is not erroneously detected during normal driving.
Decrease as the size of the image becomes smaller. The data of the threshold value C is stored in the controller 1 as data such as a map.
(FIG. 1).

Next, at step S5, the steering angle θ
It is determined whether or not the absolute value of the difference between 1 and the steering angle θ2 is equal to or smaller than the threshold value C. If it is equal to or smaller than the threshold value C, it is determined that both the steering wheel angle sensor 2 and the steering stroke sensor 3 (both shown in FIG. 1) are normal (step S6), and this routine ends. On the other hand, if it is above the threshold value C, it is determined that one of the steering wheel angle sensor 2 and the steering stroke sensor 3 (both shown in FIG. 1) is abnormal (step S7), and this routine ends. .

Here, a case in which one of the steering wheel angle sensor 2 and the steering stroke sensor 3 (both shown in FIG. 1) is abnormal will be described in detail. It is assumed that the steering angle sensor 2 (FIG. 1) malfunctions due to disconnection, short circuit, etc., and the steering stroke sensor 3 (FIG. 1) operates normally. When the driver turns the steering wheel, time t
1, the steering stroke sensor 3 and the lateral G sensor 5
(Both in FIG. 1) operate normally, but the steering wheel angle sensor 2
The steering angle θ1 obtained by (FIG. 1) is fixed to a certain value.

FIG. 7 is a diagram for explaining the detection time of the sensor failure. As shown in the drawing, when a constant threshold value Co is used as in the related art, an abnormality of the steering wheel angle sensor 2 (FIG. 1) is detected at time t2. On the other hand, when the threshold value C is reduced as the lateral G value YG decreases within the range from zero to the threshold value Co, the absolute value of the difference between the steering angle θ1 and the steering angle θ2 is smaller than the threshold value Co. At time t3 (t2> t2) exceeding the threshold value C, the steering wheel angle sensor 2
The abnormality of FIG. 1 is detected.

According to the present embodiment, the threshold value C is set such that a failure is not erroneously detected during normal driving.
When the steering wheel angle sensor 2 (FIG. 1) or the steering rack stroke sensor 3 (FIG. 1) is out of order, the steering angle θ1 and the steering angle θ2
Since the absolute value of the difference from the steering wheel angle exceeds the threshold value C immediately after the driver turns the steering wheel, the driver may determine that the steering wheel angle sensor 2 (FIG. 1) or the steering rack stroke sensor 3 (FIG. 1) has failed. It can be detected early after turning off.

FIG. 8 is a flowchart of a second embodiment of a method for detecting a failure of a steering angle sensor according to the present invention.
In this case, power steering is used, and the description of the same steps as those in the flowchart of FIG. 4 is omitted. Also in this routine, it is determined that both the steering wheel angle sensor 2 and the steering stroke sensor 3 (both in FIG. 1) are normal.
It is assumed that the correction is started once at the time of 0.1).

After reading the lateral G value YG in step S3, the controller 1 (FIG. 1) determines the differential value dA of the steering angle θ1.
The differential value dANGL2 of the NGL1 and the steering angle θ2 is calculated (steps S11 and S12).

Then, in step S13, the differential value
It is determined whether the absolute value of dANGL1 is greater than the absolute value of differential value dANGL2. When the absolute value of the differential value dANGL1 is larger than the absolute value of the differential value dANGL2, the controller 1 (FIG. 1)
The flag FLGST is set to 1 in the memory (step S1).
4) If not, the flag FLGST is set to 0 in the memory of the controller 1 (FIG. 1) (step S1).
5).

In step S14 or S15, the flag FLGST
Is set to 1 or 0, the process proceeds to step S4, and then, in step S16, it is determined whether or not the value of the flag FLGST is 0. If it is 0, the threshold value C is corrected by the differential value dANGL2; otherwise, that is, the flag FL is corrected.
If the value of GST is 1, the threshold value C is corrected by the differential value dANGL1, and the process proceeds to step S5.

FIG. 9 is a diagram showing the relationship between the lateral G value YG, the absolute value of the difference between the steering angle θ1 and the steering angle θ2, and the steering speed. In the case of power steering, when the steering is suddenly turned, the feeling of the power steering fluid being caught increases. Therefore, as illustrated, the absolute value of the difference between the steering angle θ1 and the steering angle θ2 increases as the steering speed increases.

Therefore, a normal steering angle sensor (in this case, the steering wheel angle sensor 2 (FIG. 1) or the steering rack stroke sensor 3 (FIG. 1)) is estimated to some extent from the absolute value of the differential value dANGL1 and the absolute value of the differential value dANGL2. Then, by calculating the turning speed, the threshold value C that decreases as the lateral G value YG decreases can be reduced as the turning speed decreases. This allows
Failure of the steering wheel angle sensor 2 (FIG. 1) or the steering rack stroke sensor 3 (FIG. 1) can be detected more quickly.

FIG. 10 is a diagram showing a case where the threshold steering speed for the lateral G is considered and a case where the steering speed is not considered. A curve C1 indicates a change in the threshold value when only the lateral G value YG is considered, and a curve C2 indicates a change in the threshold value when the lateral G value YG and the turning speed are considered. As shown in the figure, when the lateral G value YG and the turning speed are considered, the lateral G value YG is better.
In this case, the threshold value is smaller than that in the case where only the steering angle sensor 2 (FIG. 1) or the steering rack stroke sensor 3 (FIG. 1) is faulty.

The present invention is not limited to the above-described embodiment, and many modifications and variations are possible. For example, although the first steering angle sensor and the second steering angle sensor are respectively a steering wheel angle sensor and a steering rack stroke sensor, other conventionally known sensors may be used. Also, the handle angle sensor is of a type that detects a pulse signal, but may be of a resistance type.

In steps S11 to S15 in FIG. 8, the failure of the steering angle sensor is estimated from the differential values dANGL1 and dANGL2 of the steering angles θ1 and θ2.
The failure of the steering angle sensor can be estimated from the increase / decrease tendency of the value YG or the like.

Further, in estimating the failed steering angle sensor in the flowchart of FIG. 8, it can be estimated from the relationship between the yaw rate, the lateral G sensor 5 (FIG. 1), the vehicle speed, the wheel speed difference, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic view of a vehicle that implements a method for detecting a failure of a steering angle sensor according to the present invention.

FIG. 2 is a diagram showing a deviation between a steering wheel angle and an analog steering angle during normal running with respect to a lateral G;

FIG. 3 is a diagram showing turning of the vehicle from straight ahead.

FIG. 4 is a flowchart of a first embodiment of a method for detecting a failure of a steering angle sensor according to the present invention.

FIG. 5 is a diagram showing a change in a threshold value C with respect to a horizontal G value YG.

FIG. 6 is a diagram showing changes over time of steering angles θ1, θ2 and a lateral G value YG.

FIG. 7 is a diagram illustrating a detection time of a sensor failure.

FIG. 8 is a flowchart of a second embodiment of a method for detecting a failure of a steering angle sensor according to the present invention.

FIG. 9 is a diagram showing a relationship between a lateral G value YG, an absolute value of a difference between the steering angle θ1 and the steering angle θ2, and a turning speed.

FIG. 10 is a diagram illustrating a case where a steering speed of a threshold value C with respect to a lateral G value YG is considered and a case where the steering speed is not considered;

[Explanation of symbols]

 Reference Signs List 1 Controller 2 Handle angle sensor 3 Steering rack stroke sensor 4 Yaw rate sensor 5 Lateral G sensor 6a, 6b Steering linkage 7 Vehicle C, Co, C1, C2 Threshold values t1, t2, t3 Time YG Lateral G value θ1, θ2 Steering angle

Claims (2)

[Claims] 1. A first steering angle sensor and a second steering angle sensor detect a first steering angle and a second steering angle of a vehicle, respectively, and the first steering angle and the second steering angle are detected. If the absolute value of the difference from the threshold value is equal to or greater than the threshold value, the threshold value is erroneously changed from zero to normal during normal traveling when detecting that the first steering angle sensor or the second steering angle sensor has failed. A method for detecting a failure in a steering angle sensor, wherein the value is reduced as the lateral G decreases within a range up to a threshold value set so as not to detect the steering angle sensor. 2. The method according to claim 1, wherein the threshold value that decreases as the lateral G decreases decreases as the steering speed decreases.