JP4442215B2 - Steering device - Google Patents

Description

  The present invention belongs to the technical field of a steering device including a steering actuator that steers steered wheels based on a target turning angle.

In a conventional steering device, when self- steering as unintentional steering by the driver occurs, it is determined that the system has failed and the system is stopped to prevent the unintended steering from being continued by the driver. ( See Non-Patent Document 1, for example).
BMW Society Paper (Aachener Kolloquium Fahrzeug-und Motorentechnik2002), Active Steering-Requirements for System Safety and Development Process

  By the way, the time from the failure occurrence to the system stop is defined only by the allowable self-steer angle obtained from the vehicle speed at the time of the failure occurrence. When the system stops, the motor rotates in a direction away from the neutral position until the system stops, and the deviation between the neutral position of the steering wheel and the neutral position of the steering wheel becomes larger. If the amount of deviation at this time is large, there is a problem that the vehicle does not go straight unless the steering wheel is turned off, which gives the driver a feeling of strangeness.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a steering apparatus capable of minimizing a neutral position shift when the system is stopped.

In order to achieve the above-described object, in the present invention, a steering gear ratio, which is provided between the steering operation means and the steered wheels and is the ratio of the steering angle of the steering operation means to the steered angle of the steered wheels, is set as a target. When the difference between the steered actuator that changes according to the steered angle, the target steered angle and the actual steered angle exceeds a predetermined value, a failure judging means that judges that a failure has occurred, and And a system stop means for stopping the rudder actuator, provided with a self-steer direction detecting means for detecting a direction in which self-steer is generated as a steering unintended by the driver, the system stop means If it is determined that there is a failure, and if the self-steer occurs in the direction of turning the steered wheel, the steering actuator is immediately stopped and the self-steer turns off the steered wheel. When occurring in the return direction is characterized by stopping the turning actuator from being determined as a failure after a predetermined system stop permissible time.

In the steering apparatus of the present invention, when self-steering is generated in the turning-increasing direction of the steering wheel, in order to immediately stop the actuator, the neutral position of the neutral position and the steering wheel of the steering operating means An increase in the amount of deviation can be prevented. On the other hand, if the self-steering occurs in steering back direction of the steering wheel, for stopping the turning actuator after a predetermined time has elapsed, it is possible to reduce the amount of deviation to the system stopped.

  Hereinafter, the best mode for carrying out the present invention will be described based on the first embodiment.

First, the configuration will be described.
FIG. 1 is a system block diagram of a vehicle to which the steering device of the first embodiment is applied. The steering device of the first embodiment includes a steering wheel (steering operation means) 1, a column shaft 2, a front wheel steering mechanism 3, and the like. , Front wheels 4 and 4, rear wheel steering mechanism 5, rear wheels 6 and 6, front wheel steering actuator 7, front wheel steering controller 8, rear wheel steering actuator 9, and four wheel active steering controller 10 A steering angle sensor 11 and a vehicle speed sensor 12 are provided.

  The front wheel steering mechanism 3 converts the rotation input to the column shaft 2 from the steering wheel 1 into a lateral movement of the vehicle by a rack and pinion, and steers the front wheels 4 and 4. Further, the rear wheel steering mechanism 5 converts the input of the rear wheel steering actuator 9 into a vehicle lateral movement, and steers the rear wheels 6 and 6.

FIG. 2 is a block diagram illustrating a control system according to the first embodiment.
The front wheel steering actuator 7 includes a DC brushless motor (hereinafter referred to as a motor) 7a provided with a reduction gear, a rotation angle sensor 7b for detecting the rotation angle of the motor 7a, and the like. In FIG. 1 is disposed at a position between the upper column shaft 2 a to which 1 is attached and the lower column shaft 2 b connected to the front wheel steering mechanism 3. This front wheel steering actuator 7 decelerates the rotation input via the upper column shaft 2a by the variable gear ratio and outputs it to the lower column shaft 2b. The steering gear ratio, which is the ratio, is variably controlled. A target front wheel turning angle current command value is input from the front wheel turning controller 8 to the motor 7a. The front wheel steering actuator motor rotation angle, which is the output of the rotation angle sensor 7b, is output to the front wheel steering controller 8.

  The front wheel turning controller 8 compares the target front wheel turning angle current command value output from the four-wheel active turning controller 10 with the front wheel turning actuator motor rotation angle output from the rotation angle sensor 7b, and performs target turning. A target front wheel turning angle current command value is output to the motor 7a so that the steering angle matches the actual turning angle.

  Like the front wheel steering actuator 7, the rear wheel steering actuator 9 includes a DC brushless motor (hereinafter referred to as a motor) 9a provided with a speed reducer, a rotation angle sensor 9b for detecting the rotation angle of the motor 9a, and the like. The turning angle of the rear wheels 6 and 6 is variably controlled through the rear wheel turning mechanism 5 by the rotation of the motor 9a. A target rear wheel turning angle current command value is input from the four-wheel active turning controller 10 to the motor 9a. Further, the rear wheel steering actuator motor rotation angle that is the output of the rotation angle sensor 9 b is output to the four-wheel active steering controller 10.

  The four-wheel active steering controller 10 is based on the steering steering angle output from the steering angle sensor 11 and the vehicle body speed (= vehicle speed) output from the vehicle speed sensor 12, and the target front wheel steering angle and the target rear wheel steering. An angle is generated, and a target front wheel turning angle current command value and a target rear wheel turning angle current command value are output to the front wheel turning controller 8 and the rear wheel turning actuator 9.

  The four-wheel active steering controller 10 has a front-wheel steering angular current command value calculation unit 13 that is responsible for control related to the steering control of the front wheels 4 and 4. As shown in FIG. 3, the front wheel turning angular current command value calculation unit 13 includes a target front wheel turning angular current command value calculation unit 13a and a failure diagnosis unit 13b.

  The target front wheel turning angle current command value calculation unit 13a calculates a target front wheel turning angle current command value based on inputs such as a steering steering angle, a vehicle body speed, and a front wheel turning actuator motor rotation angle, and a front wheel turning controller. Output to 8.

  The failure diagnosis unit 13b compares the front wheel turning actuator motor rotation angle with the target front wheel turning angle current command value to diagnose a failure of the front wheel turning system, and calculates the diagnosis result as a target front wheel turning angle current command value calculation. To the unit 13a.

  The target front wheel turning angle current command value calculation unit 13a, when it is diagnosed by the failure diagnosis unit 13b that a failure has occurred in the front wheel turning system, the motors 7a, 9a of the front wheel turning actuator 7 and the rear wheel turning actuator 9. The system for turning angle control is stopped by stopping the current supply to the wheel.

Next, the operation will be described.
[System stop control processing]
FIG. 4 is a flowchart showing the flow of the system stop control process executed by the four-wheel active steering controller 10, and each step will be described below.

  In step S1, the front wheel turning actuator motor rotation angle is compared with the target front wheel turning angle current command value, and the process proceeds to step S2.

  In step S2, failure determination is performed based on the comparison result in step S1 (corresponding to failure determination means). If the front wheel turning actuator motor rotation angle and the target front wheel turning angle current command value are different from each other by a predetermined value or more, it is determined that a failure has occurred, and the process proceeds to step S3. If the deviation is smaller than the predetermined value, it is determined that the deviation is normal and the process proceeds to step S11.

  In step S3, the target front wheel turning angle current command value is monitored, and the process proceeds to step S4.

In step S4, the direction of self-steering is determined from the direction of change of the front-wheel steering actuator motor rotation angle (corresponding to self-steering direction detecting means). If the motor 7a is rotating toward the neutral position (N position), the process proceeds to step S5. If the motor 7a is rotating away from the N position, the process proceeds to step S12.

  In step S5, the vehicle speed is monitored, and the process proceeds to step S6.

In step S6, to calculate the allowable self-steering angle from the vehicle speed, the process proceeds to step S7. The allowable self-steer angle can be calculated from the characteristic diagram of the allowable self-steer shown in FIG.

In step S7, it determines self-steering threshold. If the generated self-steer is less than or equal to the allowable value, the process proceeds to step S8, and if the generated self-steer is greater than the allowable value, the process proceeds to step S12.

In step S8, an allowable system stop time is calculated, and the process proceeds to step S9. The allowable system stop time can be obtained by a / b [sec] where the allowable self-steer angle calculated in step S6 is a [ deg ] and the turning angular velocity of the front wheels 4 and 4 is b [deg / sec].

  In step S9, the count-up timer starts counting, and the process proceeds to step S10.

  In step S10, the allowable system stop time is compared with the counter value of the count-up timer. If the allowable system stop time is greater than the counter value, step S10 is repeated. If the allowable system stop time is less than or equal to the counter value, the process proceeds to step S12.

  In step S11, normal control is continued.

  In step S12, the current supply to the front wheel steering actuator 7 and the rear wheel steering actuator 9 is stopped, and the system is stopped (corresponding to the system stop means).

[System stop control action]
When a failure occurs in the front wheel steering system, in the flowchart of FIG. 4, the flow proceeds from step S 1 → step S 2 → step S 3 → step S 4. In step S 4, from the direction of change in the rotation angle of the motor 7 a, Self-steer direction is determined.

  Here, when the motor 7a is rotating in the direction away from the N position, the process proceeds from step S4 to step S12, the front wheel steering actuator 7 is immediately stopped, and the system is stopped.

  On the other hand, when the motor 7a is rotating in the direction approaching the N position, the process proceeds from step S4 to step S5 to step S6 to step S7. In step S7, the generated self-steer and the allowable self-steer are compared.

  If the generated self-steer is larger than the allowable self-steer, the process proceeds from step S7 to step S12, and the system stops.

  If the generated self-steer is less than or equal to the allowable self-steer, the process proceeds from step S7 → step S8 → step S9 → step S10.In step S8, the system stop allowable time is calculated, and in step S10, the timer counter value is calculated. Is equal to or longer than the allowable system stop time, the system stops in step S12.

[Problems of conventional technology]
As described above, in the conventional steering device, when self-steering occurs, the time from the occurrence of a failure to the system stop is defined by the allowable self-steer angle obtained from the vehicle speed at the time of the failure. At this time, if the self-steering occurs in the direction of the steering wheel, the steering actuator motor rotates away from the neutral position from the occurrence of the failure until the system stops, and FIG. As shown in FIG. 2, the neutral position shift between the steering wheel and the steering wheel becomes large.

  Therefore, as shown in FIG. 5 (b), there is a problem in that the vehicle does not go straight unless the steering wheel is turned off, and the driver feels uncomfortable. Also, if the amount of deviation is large, it may be difficult for the driver to move the vehicle to a desired position when performing a lane change during high-speed driving.

[System stop action according to self-steer direction]
On the other hand, in the steering device of the first embodiment, as shown in FIG. 6, the direction in which the self-steer is generated is detected, and the direction in which the self-steer increases the tire turning angle (the direction in which the front wheels 4 and 4 are increased). ), It is possible to prevent the shift amount from increasing until the system is stopped by stopping the system immediately.

  On the other hand, when the self-steer occurs in the direction of decreasing the tire turning angle (the direction of turning back the front wheels 4 and 4), the current vehicle speed is adjusted based on the allowable self-steer characteristic diagram shown in FIG. The permissible self-steer is calculated accordingly. At this time, if the generated self-steer is equal to or less than the allowable self-steer, the system is not stopped immediately, and the motor 7a is rotated in the direction approaching the N position until the allowable system stop time elapses. Can be reduced.

Even if self-steering occurs in a direction that reduces the tire turning angle, if the generated self-steering exceeds the allowable self-steering, the system is immediately stopped , giving the driver a sense of discomfort. Can be reduced .

Next, the effect will be described.
In the steering device of the first embodiment, the following effects can be obtained.

(1) When the four-wheel active steering controller 10 determines that a failure has occurred, if the self-steering occurs in the direction of switching back the front wheels 4 and 4, the allowable system stop time calculated from the allowable self-steering If the system is stopped after a lapse of time and self-steering occurs in the direction of increasing the front wheels 4 and 4, the system is immediately stopped. can Ru.

(2) When the four-wheel active steering controller 10 is determined to be out of order and self-steering occurs in the direction of switching back the front wheels 4 and 4, and the self-steering angle is greater than the allowable self-steering angle, immediate order to stop the system to, Ru can reduce the sense of discomfort given to the driver.

(3) Since the four-wheel active steering controller 10 sets the allowable system stop time based on the allowable self-steer angle calculated from the vehicle body speed, when the self-steer is generated in the return direction of the front wheels 4 and 4 , while reducing the sense of discomfort given to the driver, Ru it is possible to reduce the neutral position deviation at the time of failure.

(4) Since the four-wheel active steering controller 10 sets the allowable system stop time based on the allowable self-steer angle and the turning angular velocity of the front wheels 4 and 4, the allowable system stop time that can further reduce the uncomfortable feeling given to the driver. you can configure the.

(Other examples)
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment and does not depart from the gist of the present invention. Such design changes are included in the present invention.

  For example, in the first embodiment, the configuration in which the turning angles of the front wheels 4 and 4 and the rear wheels 6 and 6 are variably controlled using the front wheel steering actuator 7 and the rear wheel steering actuator 9 is shown. The apparatus can also be applied to a configuration that variably controls only the front wheels 4 and 4 that are steered wheels.

1 is a system block diagram of a vehicle to which a steering device according to a first embodiment is applied. FIG. 3 is a block diagram illustrating a control system according to the first embodiment. It is a block diagram which shows a front wheel turning angle electric current command value calculating part. 3 is a flowchart showing a flow of a system stop control process executed by a four-wheel active steering controller 10. It is explanatory drawing which shows the neutral position shift at the time of a system stop. It is explanatory drawing which shows the effect | action of Example 1. FIG. FIG. 6 is a characteristic diagram of allowable self-steering according to vehicle speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Column shaft 2a Upper column shaft 2b Lower column shaft 3 Front wheel steering mechanism 4 Front wheel 5 Rear wheel steering mechanism 6 Rear wheel 7 Front wheel steering actuator 7a Motor 7b Rotation angle sensor 8 Front wheel steering controller 9 Rear wheel steering actuator 9a Motor 9b Rotation angle sensor 10 Wheel active turning controller 11 Steering angle sensor 12 Vehicle speed sensor 13 Front wheel turning angle current command value calculation unit 13a Target front wheel turning angle current command value calculation unit 13b Failure diagnosis unit

Claims (1)

A steering actuator that is provided between the steering operation means and the steered wheel and changes a steering gear ratio, which is a ratio of the steering angle of the steering operation means to the steered angle of the steered wheel, according to the target turning angle; ,
Failure determination means for determining a failure when the difference between the target turning angle and the actual turning angle exceeds a predetermined value;
System stop means for stopping the steering actuator when it is determined that there is a failure;
In a steering device with
A self-steer direction detecting means for detecting the direction in which self-steer is generated as a steering not intended by the driver is provided,
When the system stop means is determined to be a failure,
If self-steering occurs in the direction of turning the steered wheels, stop the steering actuator immediately,
A steering device characterized in that, when self-steering occurs in the direction of turning back a steered wheel, the steering actuator is stopped after a predetermined system stop allowable time elapses after the failure is determined.

Images