JP5054644B2 - Vehicle steering control device - Google Patents

Description

  The present invention relates to a vehicle steering control device that detects an abnormality of a steering angle sensor.

  A steering angle sensor is used in the vehicle skid prevention device, and the braking force of each wheel is controlled so that the steering state of the driver is calculated from the steering angle and the vehicle behavior according to the steering angle is obtained.

  As described above, the steering angle plays a very important role in controlling the vehicle behavior, and there is a problem that normal control cannot be performed when an abnormality occurs in the steering angle sensor. For this reason, means for detecting an abnormality of the steering angle sensor has been proposed.

  For example, in Patent Document 1, the difference between the relative steering angle obtained from the absolute steering angle obtained from the steering angle sensor and the rotation angle of the motor (steering assistance motor) that generates torque for assisting the steering of the driver exceeds the threshold. A steering angle abnormality detection device is disclosed that detects an abnormality of a steering angle sensor in the event of a failure.

  Further, Patent Document 2 discloses an electric power steering device that determines an abnormality in a steering angle from the amount of change in a steering angle sensor and an inexpensive position detection sensor.

JP 2002-104211 A WO2005 / 105550

  However, in Patent Document 1, the relative steering angle is estimated from the rotation angle of the steering assist motor. However, since only the relative angle can be obtained only by the rotation angle of the steering assist motor, the actual steering angle is obtained. Requires information such as the initial value, the previous value, and the number of laps of the steering assist motor. However, when the steering wheel is turned when the vehicle is turned off, the previous value and the number of laps are indefinite, so there is a problem that the correct steering angle cannot be obtained from the motor rotation angle.

  Further, in Patent Document 2, in order to determine the abnormality of the steering angle from the amount of change of the steering angle sensor and the inexpensive position detection sensor, the abnormality of the steering angle is determined only after the steering wheel or the steering assist motor rotates. However, there is a problem that early abnormality detection cannot be performed when the steering assist motor does not rotate.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle steering control device that detects an abnormality in the steering angle at an early stage without depending on steering when the vehicle is turned off. Is.

The vehicle steering control device according to the present invention includes a steering torque detecting means for detecting a steering torque by a driver, a steering angle detecting means for detecting a steering angle of a steering shaft, and a motor for generating torque for assisting the driver's steering. Motor angle detection means for detecting the rotation angle of the motor, motor drive instruction means for issuing a drive instruction to the motor when the IG is on, and the motor angle while the motor is being driven by the motor drive instruction means. Steering angular velocity estimating means for estimating a steering angular velocity from the output of the detecting means; steering angular velocity detecting means for detecting the steering angular speed based on the output of the steering angle detecting means while driving the motor according to the drive instruction; Deviation calculating means for outputting an absolute value of deviation between the output of the steering angular velocity detecting means and the output of the steering angular velocity estimating means, and the drive instruction If the output of the steering torque detection means is equal to or less than the predetermined threshold value while driving the serial motor, and the output of the deviation calculation means detects the abnormality of the steering angle detecting means when more than a predetermined threshold value Steering angle abnormality detecting means.

  According to the present invention, it is possible to detect an abnormality in the steering angle at an early stage regardless of the ignition-off state of the vehicle, and the safety of the vehicle steering control device can be improved.

Embodiment 1 FIG.
The configuration of the vehicle steering control apparatus according to the first embodiment of the present invention will be described below with reference to FIG.
FIG. 1 is a diagram showing the overall configuration of a typical vehicle steering control apparatus according to the present invention. The steering control ECU 5 mainly generates an assist torque 3 corresponding to the steering torque 2 by the driver, and detects an abnormality of the steering angle detection means 10 that detects the steering angle (absolute angle) of the steering shaft. Function.

  Here, a portion of the function of the steering control ECU 5 that generates the assist torque will be briefly described. The steering torque 2 when the driver turns the steering wheel 1 is measured by the steering torque detection means 4 and sent to the steering control ECU 5 as a steering torque detection signal 6. The steering control ECU 5 controls the motor current 8 in order to generate the assist torque 3 from the motor current 8, the motor angle detection signal 9, and the steering torque detection signal 6, which are the state quantities of the steering assist motor 7.

  Next, of the functions of the steering control ECU 5, the abnormality detection function of the steering angle detection means 10 will be described with reference to FIG. The IG state detection means 14 detects from the IG (ignition) signal 13 whether the ignition of the vehicle has started up or has fallen off, and the motor drive instruction means 15 has the IG state detection means 14 turn on the IG. A drive instruction for driving the motor 7 for a predetermined time after detection is output. The steering angular velocity detection means 16 detects the steering angular speed from the steering angle detection signal 11, and the steering angular speed estimation means 18 estimates the steering angular speed based on the output of the motor angle detection means 17 that detects the rotation angle of the steering assist motor 7. The deviation calculating means 19 calculates the deviation between the output of the steering angular speed detecting means 16 and the output of the steering angular speed estimating means 18 and outputs an absolute value. The steering angle abnormality detection means 20 receives the output of the IG state detection means 14, and indicates that the steering angle is abnormal if the output of the deviation calculation means 19 when the IG rises on is above a certain threshold. The signal 12 is output.

Here, the steering angular velocity detection means 16 and the steering angular velocity estimation means 18 will be described. In general, a motor angle sensor used in a vehicle steering control device can measure only a relative angle, not an absolute angle. Further, the steering assist motor 7 is attached to the steering shaft via a reduction gear, and the motor 7 rotates more than ten times while the handle 1 rotates once. Therefore, simply looking at the current value of the motor angle The steering angle cannot be estimated from the motor angle. If the number of laps and the angle from the reference position are known, the steering angle can be estimated from the motor angle, and an abnormality of the steering angle detection means 10 can be detected by calculating a deviation from the steering angle detection signal 11. However, if the number of laps from the reference position of the motor 7 becomes indefinite, such as when the steering wheel is turned when the IG is off, the steering angle cannot be correctly estimated from the motor angle, and an abnormality in the steering angular velocity detection means 16 is erroneously detected There are things to do. Therefore, by detecting and estimating the steering angular velocity from the steering angle detection signal 11 and the motor angle detection signal 9 and comparing the deviations, the abnormality of the steering angle detection means 10 can be detected regardless of the state when the IG is off.
The steering angular velocity estimation means 18 can estimate the steering angular velocity by differentiating the motor angle detection signal 9 with respect to time and dividing it by the reduction gear ratio of the steering assist motor 7. Further, instead of the time differentiation of the motor angle detection signal 9, it is also possible to estimate the steering angular velocity by dividing the signal obtained by passing the motor angle detection signal 9 through the high-pass filter by the reduction gear ratio of the steering assist motor 7. is there.

  Next, the motor drive instruction means 15 will be described. When comparing the angular velocities and detecting an abnormality in the steering angle, it is necessary to generate a certain angular velocity. When the steering angular velocity is generated by the driver's steering, the steering angular velocity is not generated until the driver steers. Therefore, the steering angle is detected for the first time in a high-speed state that tends to become unstable when the vehicle speed is increased while the vehicle is traveling straight ahead. An abnormality of the means 10 is detected, and the abnormality detection is delayed. By forcibly driving the motor 7 by the motor drive instructing means 15 when the IG is turned on to generate a steering angular velocity, an abnormality of the steering angle detecting means 10 can be detected at an early stage before the vehicle starts to move.

Next, the steering angle abnormality detecting means 20 will be described with reference to FIG. The steering angle abnormality detection means 20 compares the comparison between the deviation calculation signal from the deviation calculation means 19 and the threshold value α by the threshold setting device 21 when an IG ON rising signal is acquired from the output of the IG state detection means 14. When the deviation calculation signal is larger than the threshold value α, the steering angle abnormality signal 12 is output.
By outputting the steering angle abnormality signal 12, it is possible to quickly stop the apparatus such as a skid prevention apparatus that uses the steering angle or to make a failure determination.

  Next, the steering angle abnormality detection operation of the steering control ECU 5 having the above-described configuration will be described with reference to the flowchart of FIG. The difference from the prior art of the present invention is that the steering angle abnormality detecting means 20 detects an abnormality of the steering angle, and the configuration of the assist torque control means is the same as that of the conventional electric power steering apparatus. Therefore, only the part that detects an abnormality in the steering angle will be described.

First, in step S101, the rising state of IG on is detected from the IG state detection means 14, and in step S102, the motor 7 is driven by the motor drive instruction means 15.
In step S103, the steering angle detection signal 11 detected by the steering angle detection means 10 is read and stored in the memory.
In step S104, the motor angle detection output detected by the motor angle detection means 17 is read and stored in the memory.
In step S105, the steering angular velocity detection means 16 detects the steering angular velocity from the steering angle detection signal 11 stored in the memory, and stores it in the memory.
In step S106, the steering angular velocity estimation means 18 estimates the steering angular velocity from the motor angle detection output stored in the memory, and stores it in the memory.
In step S107, based on the steering angle detection signal 11 stored in the memory and the output of the steering angular velocity estimating means 18, the deviation calculating means 19 calculates the absolute value of the deviation, and compares it with a preset threshold value α. To do.
If it is determined in step S108 that the output of the deviation calculating means 19 is equal to or greater than the threshold value α, it is determined in step S109 that the steering angle is abnormal, and the steering angle abnormality signal 12 is output.

  As described above, according to the first embodiment of the present invention, the motor 7 is forcibly driven when the IG is turned on, and the angular velocity is obtained from the steering angle and the motor angle and compared, so that the steering can be quickly performed regardless of the IG off state. An abnormality of the corner detection means 10 can be detected.

  In the first embodiment, the motor drive instructing means 15 drives the motor 7 when the IG state detecting means 14 rises. However, the motor 7 may be driven for a certain period of time from the rise of IG on. Further, although the steering angle abnormality detection means 20 compares the deviation calculation signal with the threshold value α when the IG state detection means 14 rises, the steering angle abnormality detection means 20 may compare for a certain time from the time when IG ON rises. In this case, the abnormality of the steering angle detection means 10 can be detected with higher accuracy.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing a main configuration of the vehicle steering control apparatus according to Embodiment 2 of the present invention. 5 differs from the first embodiment in that the output of the motor angle detection means 17 is input to the motor drive instruction means 15 and the output of the steering angular velocity estimation means 18 is also input to the steering angle abnormality detection means 20. It is that.

  FIG. 6 is a block diagram showing the configuration of the steering angle abnormality detection means 20 in the second embodiment of the present invention. In FIG. 6, the change from Embodiment 1 is that the threshold value α 21 by the threshold setting device 21 can be changed according to the output of the steering angular velocity estimation means 18.

  Next, the operation of the steering control device having the above configuration will be described based on the flowchart of FIG. Note that the second embodiment will be described only for a portion that detects an abnormality in the steering angle, as in the first embodiment.

First, in step S201, the rising state of IG ON is detected from the IG state detecting means 14.
In step S202, the motor angle detection output detected by the motor angle detection means 17 is read and stored in the memory.
In step S203, the motor 7 is driven by the motor drive instruction means 15 based on the motor angle detection output stored in the memory.
In step S204, the steering angle detection signal 11 detected by the steering angle detection means 10 is read and stored in the memory.
In step S205, the steering angular velocity detection means 16 detects the steering angular velocity from the steering angle detection signal 11 stored in the memory, and stores it in the memory.
In step S206, the steering angular velocity estimation means 18 estimates the steering angular velocity from the motor angle detection output stored in the memory, and stores it in the memory as a steering angle estimated value.
In step S207, the threshold α is set by multiplying the estimated steering angular velocity stored in the memory by the conversion gain.
In step S208, the deviation calculating means 19 calculates the absolute value of the deviation based on the steering angle detection signal 11 and the steering angle estimating means output stored in the memory, and compares the magnitude with the threshold value α set in S207. .
If it is determined in step S209 that the output of the deviation calculating means 19 is greater than or equal to the threshold value α, it is determined in step S210 that the steering angle is abnormal, and the steering angle abnormality signal 12 is output.

  As described above, in the second embodiment, by inputting the motor angle to the motor drive instruction means 15, the forced drive of the steering assist motor 7 can be limited to a certain angle or returned to the initial position. Abnormality of the steering angle detection means 10 can be detected without affecting the feeling. Furthermore, by changing the threshold value α according to the estimated steering angular velocity, the abnormality of the steering angle detecting means 10 can be detected with high accuracy regardless of the magnitude of the angular velocity.

  In the second embodiment, the threshold α is set by applying the conversion gain to the estimated steering angular velocity, but the threshold α may be set from a map corresponding to the estimated steering angular velocity. By setting with a map, a fine threshold can be set according to the angular velocity.

  In the second embodiment, the threshold value α is set from the steering angular velocity estimation value obtained by the steering angular velocity estimation unit 18. However, the threshold value α may be set from the output of the steering angular velocity detection unit 16. Even if the threshold value α is set from the steering angular velocity detection output, the abnormality of the steering angle detection means 10 can be detected with the same accuracy as when the threshold value α is set from the estimated steering angular velocity value.

Embodiment 3 FIG.
FIG. 8 is a block diagram showing a main configuration of the vehicle steering control apparatus according to Embodiment 3 of the present invention. 8 differs from the first embodiment in that the output of the motor current detection means 23 is input to the motor drive instruction means 15 and the output differentiated by the differentiation means 24 of the steering torque detection signal 6 and the steering angle detection signal 11 Is input to the steering angular velocity detection means 16 and the steering torque detection signal 6 is input to the steering angle abnormality detection means 20.

  FIG. 9 is a block diagram showing the configuration of the steering angle abnormality detecting means 20 according to Embodiment 3 of the present invention. 9 is different from the first embodiment in that a comparison unit 26 for comparing the output of the steering torque detection signal 6 and the threshold value β by the threshold setting unit 25 is added, and the logical product of the comparison unit 22 and the comparison unit 26 is obtained. That is, the steering angle abnormality signal 12 is output from the AND 27.

Next, the operation of the steering control apparatus of the structure will be described with reference to the flowchart of FIG. 10. Note that the third embodiment will be described only for the portion that detects an abnormality in the steering angle, as in the first embodiment.

First, in step S301, the IG state detection means 14 detects the rising state of IG on.
In step S302, the motor current detection output detected by the motor current detection means 23 is read and stored in the memory.
In step S303, the motor 7 is driven by the motor drive instruction means 15 based on the motor current detection output stored in the memory.
In step S304, the steering angle detection signal 11 detected by the steering angle detection means 10 is read and stored in the memory.
In step S305, the motor angle detection output detected by the motor angle detection means 17 is read and stored in the memory.
In step S306, the steering torque detection signal 6 detected by the steering torque detection means 4 is read and stored in the memory.
In step S307, the steering torque detection signal 6 stored in the memory is differentiated and stored in the memory as a steering torque differential output.
In step S308, the steering angular velocity is detected by the steering angular velocity detecting means 16 from the steering angle detection signal 11 and the steering torque differential output stored in the memory, and stored in the memory.
In step S309, the steering angular velocity estimation means 18 estimates the steering angular velocity from the motor angle detection output stored in the memory, and stores it in the memory as a steering angle estimated value.
In step S310, the deviation calculating means 19 calculates the absolute value of the deviation based on the steering angle detection signal 11 and the estimated steering angle value stored in the memory, and compares the magnitude with a preset threshold value α.
In step S311, the steering torque detection signal 6 stored in the memory is compared with a preset threshold value β.
If it is determined in step S312 that the output of the deviation calculating means 19 is equal to or greater than the threshold value α and the output of the steering torque detection signal 6 is equal to or less than the threshold value β, it is determined that the steering angle is abnormal. The signal 12 is output.

  As described above, in the third embodiment, by inputting the output of the motor current detecting means 23 to the motor drive instructing means 15, it is possible to instruct the drive with a constant current, and a transient large current is applied to the motor 7. It can be prevented from flowing. Further, the steering angular velocity detection value is corrected by the steering torque differential output obtained by differentiating the steering torque detection signal 6 by the differentiating means 24, so that the steering angle detecting means 10 and the motor angle detecting means 17 by the steering inertia or the driver's steering are maintained. Therefore, it is possible to detect the abnormality of the steering angle detecting means 10 with high accuracy. Further, by detecting the steering angle abnormality only when the steering torque detection signal 6 is equal to or less than the threshold value β, it is possible to prevent erroneous detection when the steering wheel is fixed by steering or the like.

  In the third embodiment, the steering torque is differentiated by the differentiating means 24, but the steering torque may be differentiated by a high-pass filter. By using a high-pass filter, the differential processing can be performed while reducing the influence of high-frequency noise.

  In the third embodiment, the threshold value α is set in advance. However, as in the second embodiment, the threshold value α may be set from the estimated steering angular velocity value or the detected steering angular velocity value. By setting the threshold value α in accordance with the magnitude of the angular velocity, it is possible to accurately detect the abnormality of the steering angle detection means 10 regardless of the magnitude of the angular velocity.

  The embodiments of the present invention have been described above. However, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the scope of the claims. Various modifications based on this are possible.

1 is a block diagram showing an overall configuration of a vehicle steering control apparatus according to Embodiment 1 of the present invention. FIG. It is a block diagram which shows the principal part structure of the steering control apparatus for vehicles by Embodiment 1 of this invention. It is a block diagram which shows the structure of the steering angle abnormality detection means in Embodiment 1 of this invention. It is a flowchart which shows the steering angle abnormality detection operation | movement of the steering control apparatus for vehicles by Embodiment 1 of this invention. It is a block diagram which shows the principal part structure of the steering control apparatus for vehicles by Embodiment 2 of this invention. It is a block diagram which shows the structure of the steering angle abnormality detection means in Embodiment 2 of this invention. It is a flowchart which shows the steering angle abnormality detection operation | movement of the steering control apparatus for vehicles by Embodiment 2 of this invention. It is a block diagram which shows the principal part structure of the steering control apparatus for vehicles by Embodiment 3 of this invention. It is a block diagram which shows the structure of the steering angle abnormality detection means in Embodiment 3 of this invention. It is a flowchart which shows the steering angle abnormality detection operation | movement of the steering control apparatus for vehicles by Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 2 ... Steering torque, 3 ... Assist torque, 4 ... Steering torque detection means, 5 ... ECU for vehicle steering control, 6 ... Steering torque detection signal, 7 ... Motor, 8 ... Motor current, 9 ... Motor angle detection Signal 10, Steering angle detection means 11, Steering angle detection signal 12, Steering angle abnormality signal, 13 IG signal, 14 IG state detection means 15, Motor drive instruction means 16, Steering angular velocity detection means 17 DESCRIPTION OF SYMBOLS ... Motor angle detection means, 18 ... Steering angular velocity estimation means, 19 ... Deviation calculation means, 20 ... Steering angle abnormality detection means, 21 ... Threshold setting device, 22 ... Comparison means, 23 ... Motor current detection means, 24 ... Differentiation means, 25 ... Threshold setting device, 26 ... Comparison means, 27 ... AND

Claims (6)

Steering torque detection means for detecting steering torque by the driver;
Steering angle detection means for detecting the steering angle of the steering shaft;
A motor that generates torque to assist the steering of the driver;
Motor angle detecting means for detecting the rotation angle of the motor;
Motor drive instruction means for issuing a drive instruction to the motor when the IG is on;
Steering angular velocity estimation means for estimating a steering angular velocity from the output of the motor angle detection means while driving the motor by the motor drive instruction means;
Steering angular velocity detecting means for detecting a steering angular velocity based on the output of the steering angle detecting means while driving the motor according to the drive instruction;
Deviation calculating means for outputting an absolute value of deviation between the output of the steering angular velocity detecting means and the output of the steering angular velocity estimating means;
When the output of the steering torque detecting means is below a predetermined threshold while the motor is driven by the drive instruction, and when the output of the deviation calculating means is above a predetermined threshold, the steering angle detecting means the vehicle steering control apparatus characterized by comprising a steering rudder angle abnormality detecting means that detect the abnormality.   2. The vehicle steering control device according to claim 1, wherein the steering angle abnormality detection unit changes a threshold according to an output of the steering angular velocity estimation unit or the steering angular velocity detection unit. 3.   The vehicle steering control device according to claim 1 or 2, wherein the steering angular velocity estimation means estimates a steering angular velocity based on an output differential value of the steering torque detection means and an output of the motor angular velocity detection means.   4. The vehicle steering control device according to claim 1, wherein the motor drive instruction means issues a drive instruction to drive the motor for a predetermined time when the IG is on. 5.   4. The vehicle steering control device according to claim 1, wherein the motor drive instructing unit instructs the motor to rotate until the motor is rotated by a certain angle when the IG is on. 5. 4. The vehicle steering control device according to claim 1, wherein the motor drive instruction means issues a drive instruction to drive the motor with a constant current when the IG is on. 5.

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