JP2018199402A - Steer-by-wire vehicle - Google Patents

Abstract

To provide a steer-by-wire vehicle which is fault-tolerant while inhibiting an increase in the number of parts and a vehicle mass.SOLUTION: A steer-by-wire vehicle includes a steer-by-wire steering system that performs steering according to a manipulation performed on a steering wheel, and a transmission system. The transmission system supports as speed change modes an automatic mode and a manual mode based on manual handling of gear shifting means. If a manipulation quantity of the steering wheel becomes undetectable, the transmission system is set to the automatic mode, and the steering system performs steering according to the handling performed by the gear shifting means in place of the manipulation performed on the steering wheel.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steer-by-wire vehicle that performs steering by a steer-by-wire system. In particular, the present invention relates to fault tolerant steer-by-wire vehicles.

  A steer-by-wire vehicle that can be steered by a steer-by-wire system is known. In the steer-by-wire system, a mechanical link (such as a steering shaft) that mechanically transmits the rotational force of the steering wheel to the axle of the drive wheel is not used. Instead, by driving the motor in accordance with the steering wheel operation by the driver, the axle of the drive wheel is moved to change the steering angle of the drive wheel. More specifically, the steering angle and steering torque of the steering wheel are detected by using a sensor. Then, based on the detected steering angle and steering torque, a motor control amount that realizes steering reflecting the driver's intention is calculated, and the motor is driven according to the calculated motor control amount.

  In such a steer-by-wire vehicle, for example, when the steering angle sensor for detecting the steering angle fails, steering by the steer-by-wire system is impossible. Therefore, it is desirable to prepare an alternative means (backup) in advance for the occurrence of a failure. That is, a fault tolerant steer-by-wire vehicle is desirable.

  Patent Document 1 discloses a vehicle steering device used in a steer-by-wire steering system. The vehicle steering apparatus includes a first steering shaft that transmits steering of a driver, a first actuator that moves the first steering shaft, a second actuator that moves a steering mechanism that steers a steered wheel, and a first steering shaft. A second steering shaft that transmits the rotation to the steering mechanism and a clutch mechanism (coupling mechanism) are provided. The clutch mechanism is configured to connect the first steering shaft and the second steering shaft so as to be integrally rotatable, or to disconnect the connection between the first steering shaft and the second steering shaft. When either one of the first actuator and the second actuator is out of order, the vehicle steering apparatus connects the first steering shaft and the second steering shaft so as to be integrally rotatable by operating the coupling mechanism. Thereby, it becomes possible to continue steering by a mechanical link system.

  Patent document 2 is disclosing the automatic evacuation apparatus of a vehicle. The automatic evacuation device includes a braking control mechanism and an evacuation control means. The braking control mechanism can control the magnitude of the braking force applied to the wheel. When a failure occurs in the steering system that steers the wheels in conjunction with the steering wheel operation, the retraction control means controls the operation of the braking control mechanism and controls the braking force applied to the left and right wheels to control the course of the vehicle. By changing, the vehicle is stopped in a predetermined retreat area.

  Patent Document 3 discloses a vehicle steering apparatus that can finely adjust the steering amount of a steered wheel. The vehicle steering apparatus includes a steering wheel, a transmission ratio variable unit that is provided between the steering wheel and the steering wheel, and includes an actuator and a reduction gear, and a steering switch provided on the steering wheel. The vehicle steering device drives the actuator of the transmission ratio variable means based on the operation of the steering switch to steer the steered wheels.

JP 2006-132264 A JP 2003-063373 A JP 2001-239950 A

  As described above, it is desirable that an alternative means (backup) is mounted on the steer-by-wire vehicle in case a steering component necessary for steer-by-wire steering fails.

  In the case of the technique disclosed in Patent Document 1, when a failure occurs, steering can be performed by a mechanical link system instead of the steer-by-wire system. However, for that purpose, it is necessary to mount the first steering shaft, the second steering shaft, and the clutch mechanism on the vehicle as backups. That is, parts equivalent to or higher than those of the conventional mechanical link are required as a backup. This causes an increase in the number of parts, vehicle mass, and cost, which is not preferable.

  Instead of using a clutch mechanism and a steering shaft, it is also possible to make the steer-by-wire system itself redundant. However, in this case as well, since the components of the steer-by-wire system are all doubled, the number of parts, vehicle mass, and cost increase.

  One object of the present invention is to provide a technique capable of realizing a fault-tolerant steer-by-wire vehicle while suppressing an increase in the number of parts and vehicle mass.

In one aspect of the present invention, a steer-by-wire vehicle is provided.
The steer-by-wire vehicle
Steer-by-wire steering device that steers in response to the operation of the steering wheel;
A transmission apparatus having an automatic mode for automatically switching a gear ratio and a manual mode for switching the gear ratio in response to a manual operation of a shift operation unit.
When the operation amount of the steering wheel becomes undetectable,
The transmission device is set to the automatic mode;
The steering device performs steering according to the operation of the shift operation means instead of the operation of the steering wheel.

  According to the present invention, when the operation amount of the steering wheel becomes undetectable, the alternative steer is performed by using the alternative means. Specifically, a shift operation means is used as an alternative means. That is, the steering device performs steering according to the operation of the shift operation means instead of the operation of the steering wheel. Thereby, a fault tolerant steer-by-wire vehicle is realized.

  While the shift operation means is used as an alternative means, the shift operation means cannot be used for its original purpose. However, since the transmission device is set to the automatic mode and the gear ratio is automatically switched, there is no particular problem in vehicle travel.

  The shift operation means is an existing part that is generally mounted on a vehicle. Since such shift operation means is used as an alternative means, an increase in the number of parts and vehicle mass is suppressed. That is, a fault-tolerant steer-by-wire vehicle can be realized while suppressing an increase in the number of parts and the vehicle mass.

  Furthermore, the shift operation means is an existing part that is not inherently related to the steering, and is independent of the steering device. Therefore, the possibility that the shift operating means and the steering device will fail simultaneously is extremely low. In other words, the possibility of failure of the normal system and the backup system at the same time is extremely low. This means that the steer-by-wire vehicle according to the present invention has high reliability.

1 is a block diagram schematically showing a configuration of a steer-by-wire vehicle according to a first embodiment of the present invention. It is the schematic which shows the paddle shift switch in the 1st Embodiment of this invention. It is a conceptual diagram for demonstrating operation of the shift lever in the 1st Embodiment of this invention. It is a block diagram which shows roughly the structure of the steer-by-wire vehicle which concerns on the 2nd Embodiment of this invention. It is a table figure which shows the alternative steering mode of the steer-by-wire vehicle which concerns on the 2nd Embodiment of this invention collectively. It is a block diagram which shows roughly the structure of the steer-by-wire vehicle which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows roughly the structure of the steer-by-wire vehicle which concerns on the 4th Embodiment of this invention. It is a table figure which shows the alternative steer mode of the steer-by-wire vehicle which concerns on the 4th Embodiment of this invention collectively. It is a block diagram showing roughly an example of composition of a steer-by-wire vehicle concerning a 5th embodiment of the present invention. It is a block diagram showing roughly other examples of composition of a steer-by-wire vehicle concerning a 5th embodiment of the present invention. It is a table figure which shows the alternative steer mode of the steer-by-wire vehicle which concerns on the 5th Embodiment of this invention collectively.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

1. 1. First embodiment 1-1. Configuration FIG. 1 is a block diagram schematically showing a configuration of a steer-by-wire vehicle 1 according to a first embodiment of the present invention. The steer-by-wire vehicle 1 is a vehicle that can be steered by a steer-by-wire system. As shown in FIG. 1, the steer-by-wire vehicle 1 according to the present embodiment includes a steering device 10, a transmission device 20, wheels 30, and an alternative steer control device 100.

<Steering device 10>
The steering device 10 is a device for performing steering (steering of the wheels 30). The steering apparatus 10 according to the present embodiment is configured to perform steering by a steer-by-wire system. More specifically, the steering device 10 includes a steering wheel (handle) 11, a steering angle sensor 12, a steering controller 13, and a steering actuator 14.

  The steering wheel 11 is a member operated by a driver during steering. The steering angle sensor 12 is provided to detect the steering angle of the steering wheel 11, that is, the operation amount of the steering wheel 11 by the driver. The rudder angle sensor 12 sends detection information to the steering controller 13.

  The steering actuator 14 is an actuator for turning the wheel 30, and its operation is controlled by the steering controller 13. Typically, the steering actuator 14 includes a motor for moving the axle of the wheel 30. The operation of the motor is controlled by the steering controller 13. The axle of the wheel 30 is moved by the motor operation, whereby the wheel 30 is steered.

  The steering controller 13 is a control device that controls the steering actuator 14 in accordance with the steering angle (operation amount) of the steering wheel 11 detected by the steering angle sensor 12.

  For example, the steering controller 13 holds a map indicating the correspondence between the input parameters including the steering angle of the steering wheel 11 and the target steering angle of the wheel 30. The steering controller 13 calculates a target steering angle (or target yaw moment) according to the input parameter by using the map. Furthermore, the steering controller 13 calculates a motor control amount for controlling the motor of the steering actuator 14 according to the calculated target steering angle. Then, the steering controller 13 outputs a motor control signal including the calculated motor control amount to the steering actuator 14. The motor of the steering actuator 14 is driven according to a motor control signal from the steering controller 13, thereby turning the wheels 30. The steering controller 13 may perform feedback control based on the difference between the target yaw moment corresponding to the target rudder angle and the actual yaw moment.

  Such a steering controller 13 is typically realized by an ECU (Electronic Control Unit). The ECU is a microcomputer including a processor, a storage device, and an input / output interface. Various data processing and control processing are realized by the processor executing the control program stored in the storage device.

  Thus, the steering apparatus 10 performs steering according to the operation of the steering wheel 11 by the driver. Here, it should be noted that in the steer-by-wire system, a mechanical link (such as a steering shaft) that mechanically transmits the rotational force of the steering wheel 11 to the axle of the wheel 30 is not used. Instead, the steering angle sensor 12 and the steering actuator 14 are used. That is, the steer-by-wire type steering apparatus 10 performs steering without using a mechanical link by using the steering angle sensor 12 and the steering actuator 14.

  The steering device 10 according to the present embodiment further includes a failure detection unit 15. The failure detection unit 15 is provided to detect a failure in a steering component necessary for steering by the steer-by-wire method. For example, the failure detection unit 15 detects a failure of the steering angle sensor 12 or the steering actuator 14.

<Transmission device 20>
The transmission device 20 includes a speed change mechanism 24. The speed ratio (gear ratio) in the speed change mechanism 24 can be switched. The transmission device 20 according to the present embodiment has two “automatic mode” and “manual mode” as speed change modes for switching the gear ratio.

  In the automatic mode, the transmission device 20 automatically switches the gear ratio. For example, the transmission device 20 automatically switches the gear ratio according to the vehicle speed and the engine rotation speed. On the other hand, in the manual mode, the transmission device 20 switches the gear ratio according to a manual operation by the driver.

  More specifically, as shown in FIG. 1, the transmission device 20 includes a shift operation means 21, a transmission controller 23, and a speed change mechanism 24.

  The shift operation means 21 is a member that is manually operated by the driver to switch the gear ratio in the manual mode. As the shift operation means 21, a known paddle shift switch or shift lever is exemplified. When operated by the driver, the shift operation means 21 outputs a shift operation signal corresponding to the operation to the transmission controller 23. As the shift operation signal, a shift-up signal indicating a shift-up operation and a shift-down signal indicating a shift-down operation can be considered.

  The transmission controller 23 is a control device for controlling the switching of the transmission gear ratio in the transmission mechanism 24. The transmission controller 23 switches the gear ratio in one of the two speed modes (that is, the automatic mode and the manual mode). In the automatic mode, the transmission controller 23 automatically switches the gear ratio. On the other hand, in the manual mode, the transmission controller 23 switches the gear ratio according to the manual operation of the shift operation means 21 by the driver. That is, in the manual mode, the transmission controller 23 switches the gear ratio according to the shift operation signal output from the shift operation means 21. Such a transmission controller 23 is realized by an ECU, for example.

  The transmission device 20 further includes a failure detection unit 25. The failure detection unit 25 is provided for detecting a failure of a component of the transmission device 20. For example, the failure detection unit 25 detects a failure of the shift operation means 21.

<Alternative steer control device 100>
The steer-by-wire vehicle 1 according to the present embodiment is equipped with an alternative means (backup) in case the steer-by-wire steering device 10 breaks down. Steering using the alternative means is hereinafter referred to as “alternative steer”. The alternative steer control device 100 is a control device that controls the alternative steer.

  For example, the alternative steer control device 100 according to the present embodiment is realized by an ECU. The alternative steer control device 100, the steering controller 13, and the transmission controller 23 may be realized by a single ECU, or may be realized by separate ECUs. As long as the alternative steer control according to the present embodiment is realized, the configuration of the alternative steer control device 100 is arbitrary.

  The mode in which the steer-by-wire vehicle 1 performs alternative steer is “alternative steer mode”. Hereinafter, the alternative steer mode according to the present embodiment will be described in detail.

1-2. Alternative Steer Mode In the present embodiment, a case where the steering angle sensor 12 of the steering device 10 fails is considered. When the steering angle sensor 12 breaks down, it becomes impossible to detect the operation amount of the steering wheel 11 by the driver, and the steering by the steer-by-wire method cannot be performed as it is. In this case, the alternative steer control device 100 sets the steer-by-wire vehicle 1 to the alternative steer mode.

  In the alternative steer mode, the driver's steering intention is detected by using means different from the steering angle sensor 12. Specifically, the driver's steering intention is detected by using the “shift operation means 21” as a backup.

  As an example, consider the case where the shift operating means 21 is a paddle shift switch 21-1 with reference to FIG. The paddle shift switch 21-1 is attached to the steering wheel 11. The paddle shift switch 21-1 includes a pair of a shift up switch 21-1U for upshifting and a shift down switch 21-1D for downshifting. In the normal manual mode, the driver can manually shift up and down by operating each of the shift up switch 21-1U and the shift down switch 21-1D.

  When the steering angle sensor 12 fails and the operation amount of the steering wheel 11 becomes undetectable, the driver uses the paddle shift switch 21-1 instead of the steering wheel 11 to change the steering intention to the steer-by-wire vehicle 1. Tell. For example, the continuous operation of the upshift switch 21-1U located on the right side when viewed from the driver is associated with “right steering”. On the other hand, the continuous operation of the shift down switch 21-1D located on the left side when viewed from the driver is associated with “left steering”. Further, the simultaneous operation of the upshift switch 21-1U and the downshift switch 21-1D is associated with “return to the steering angle midpoint (steering angle 0 point)”.

  As another example, consider the case where the shift operating means 21 is a shift lever 21-2 installed on the floor with reference to FIG. Normally, when the driver puts the shift lever 21-2 in the “D position”, the shift mode becomes the automatic mode. On the other hand, when the driver puts the shift lever 21-2 in the “M position”, the shift mode becomes the manual mode. In the normal manual mode, the driver can manually shift up and down by moving the shift lever 21-2 from "M position" to "+ position" and "-position", respectively.

  When the steering angle sensor 12 breaks down and the operation amount of the steering wheel 11 becomes undetectable, the driver uses the shift lever 21-2 instead of the steering wheel 11 to transmit the steering intention to the steer-by-wire vehicle 1. . For example, the movement operation of the shift lever 21-2 to “+ position” is associated with “right steering”. On the other hand, the movement operation of the shift lever 21-2 to “−position” is associated with “left steering”. Further, the operation of returning the shift lever 21-2 from the “M position” to the “D position” is associated with “return to the steering angle midpoint (steering angle 0 point)”.

  With reference to FIG. 1 again, the alternative steer mode according to the present embodiment will be described in more detail. First, the failure detection unit 15 detects a failure of the rudder angle sensor 12. When the failure of the steering angle sensor 12 is detected, the failure detection unit 15 outputs an error signal indicating the failure to the alternative steer control device 100. In response to the error signal, the alternative steer control device 100 sets the steer-by-wire vehicle 1 (the steering device 10 and the transmission device 20) to the alternative steer mode.

  In the alternative steer mode, the alternative steer control device 100 sets the transmission mode of the transmission device 20 to “automatic mode”. This is because, as described above, the shift operation means 21 is used for alternative steering, and the manual mode (manual shift) based on the shift operation means 21 cannot be used. In the alternative steer mode, the shift operation means 21 cannot be used for its original purpose. However, since the transmission device 20 is set to the automatic mode and the gear ratio is automatically switched, there is no particular problem in vehicle travel.

  The alternative steer control device 100 may use the notification device 200 to provide various notifications to the driver. As various notifications, “an abnormality has occurred in steering”, “inhibition of manual mode (manual shift)”, “steering method using shift operation means 21”, and the like can be considered. Examples of the notification device 200 include a display and a speaker.

  The driver steers by operating the shift operation means 21 instead of the steering wheel 11 (see FIGS. 2 and 3). When operated by the driver, the shift operation means 21 outputs a shift operation signal corresponding to the operation to the transmission controller 23. As the shift operation signal, a shift-up signal indicating a shift-up operation and a shift-down signal indicating a shift-down operation can be considered. The alternative steering control device 100 instructs the transmission controller 23 to transfer the shift operation signal output from the shift operation means 21 to the steering controller 13.

  In the alternative steer mode, the alternative steer control device 100 instructs the steering device 10 to perform steering according to the operation of the shift operation means 21 instead of the operation of the steering wheel 11. Specifically, the steering controller 13 receives the shift operation signal from the transmission device 20. The alternative steer control device 100 instructs the steering controller 13 to control the steering actuator 14 based on the shift operation signal.

  For example, the steering controller 13 associates one of the upshift signal and the downshift signal with “right steering” and the other with “left steering” (see FIGS. 2 and 3). Further, the steering controller 13 associates a specific shift operation signal with “returning to the steering angle midpoint (steering angle 0 point)” (see FIGS. 2 and 3). With such association, the steering controller 13 can use the shift operation signal as a substitute for the steering angle (operation amount) of the steering wheel 11. The calculation of the target rudder angle and the control of the motor of the steering actuator 14 are the same as in normal times.

1-3. Effect As described above, according to the present embodiment, when the steering angle sensor 12 fails and the operation amount of the steering wheel 11 becomes undetectable, the alternative steering is performed by using the alternative means. Is called. Specifically, the shift operation means 21 is used as an alternative means. That is, the steering device 10 performs steering according to the operation of the shift operation means 21 instead of the operation of the steering wheel 11. Thereby, the fault tolerant steer-by-wire vehicle 1 is realized.

  While the shift operation means 21 is used as an alternative means in the alternative steer mode, the shift operation means 21 cannot be used for its original purpose. However, since the transmission device 20 is set to the automatic mode and the gear ratio is automatically switched, there is no particular problem in vehicle travel.

  The shift operation means 21 is an existing part that is generally mounted on a vehicle. Since such shift operation means 21 is used as an alternative means, an increase in the number of parts and vehicle mass is suppressed. That is, it becomes possible to realize the fault-tolerant steer-by-wire vehicle 1 while suppressing an increase in the number of parts and the vehicle mass.

  Furthermore, the shift operation means 21 is an existing part that is not inherently related to the steering, and is independent of the steering device 10. Therefore, the possibility that the shift operation means 21 and the steering device 10 break down at the same time is extremely low. In other words, the possibility that the normal system and the backup system fail at the same time is extremely low. This means that the reliability of the steer-by-wire vehicle 1 according to the present embodiment is high.

  Even if the shift operation means 21 breaks down, the steering device 10 is likely to remain normal. Since the shift operation means 21 is often repaired while the steering apparatus 10 is normal, the possibility of developing a double failure between the steering apparatus 10 and the shift operation means 21 is extremely low.

  In addition, the transmission device 20 including the shift operation means 21 itself is very important for vehicle travel, and therefore has extremely high reliability by itself. By using such a transmission device 20 as a backup, the steer-by-wire vehicle 1 having extremely high reliability can be realized.

  In order to explain the effect of the present embodiment in more detail, a comparison with a comparative example is performed.

  First, as a first comparative example, a technique disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2006-132264) is considered. In the case of the first comparative example, when a failure occurs, steering is performed by a mechanical link method instead of the steer-by-wire method. However, for this purpose, it is necessary to mount the first steering shaft, the second steering shaft, and the clutch mechanism on the vehicle as backups. That is, parts equivalent to or higher than those of the conventional mechanical link are required. This leads to an increase in the number of parts, vehicle mass, and cost.

  Further, when steering is performed by the steer-by-wire method, the relationship between the steering angle of the steering wheel 11 and the steering angle of the wheel 30 may be different from that when the steering is performed by the mechanical link method. There is. Therefore, when a failure occurs, the steering angle midpoint position of the steering wheel 11 and the steering angle midpoint position of the wheel 30 may be shifted from the steer-by-wire method to the mechanical link method. That is, the steering angle midpoint shift may occur. In order to cope with this problem, it is necessary to further devise the clutch mechanism, which leads to system complexity and cost increase.

  On the other hand, according to the present embodiment, the mechanical link is not used as a backup when a failure occurs. Therefore, the problem as in the first comparative example does not occur. Further, by eliminating the mechanical link, the degree of freedom in designing the passenger compartment and the engine compartment can be improved.

  Next, as a second comparative example, consider duplexing the steer-by-wire system itself. However, in this case, since all the components of the steer-by-wire system are doubled, the number of components, vehicle mass, and cost are still increased.

  On the other hand, according to the present embodiment, it is not necessary to duplicate the steer-by-wire system. Instead, the shift operation means 21 is used as a backup. The shift operation means 21 is an existing part that is generally mounted on a vehicle. In addition, the additional configuration necessary for realizing the alternative steer mode according to the present embodiment is only a few wires and ECU software. Therefore, it is possible to realize an alternative steer while suppressing an increase in the number of parts and the vehicle mass.

2. Second Embodiment FIG. 4 is a block diagram schematically showing a configuration of a steer-by-wire vehicle 1 according to a second embodiment of the present invention. The description overlapping with the first embodiment is omitted as appropriate.

  According to the present embodiment, the shift operation means 21 used as a backup is duplicated. Specifically, as shown in FIG. 4, the shift operation means 21 includes both a paddle shift switch 21-1 (see FIG. 2) and a shift lever 21-2 (see FIG. 3). Therefore, even if one of the paddle shift switch 21-1 and the shift lever 21-2 breaks down, the other can be used as a backup. That is, in the alternative steer mode, the steering device 10 can perform steering in accordance with the operation of the paddle shift switch 21-1 and the shift lever 21-2 that has not failed. Therefore, the fault tolerance and reliability of the steer-by-wire vehicle 1 are further improved.

  A failure of the paddle shift switch 21-1 or the shift lever 21-2 is detected by the failure detection unit 25. When the failure detection unit 25 detects a failure of the paddle shift switch 21-1 or the shift lever 21-2, the failure detection unit 25 outputs an error signal indicating the failure to the alternative steering control device 100. In the alternative steer mode, the alternative steer control device 100 selects the paddle shift switch 21-1 or the shift lever 21-2 that has not failed as a backup.

  FIG. 5 is a table schematically showing an alternative steer mode of steer-by-wire vehicle 1 according to the present embodiment.

  When any one of the steering angle sensor 12, the paddle shift switch 21-1 (backup 1), and the shift lever 21-2 (backup 2) fails, it is a “single failure”. When the backup is duplicated, normal driving can be continued even if a single failure occurs.

  When two of the steering angle sensor 12, the paddle shift switch 21-1, and the shift lever 21-2 fail, it is a “double failure”. After the double failure occurs, if the last remaining means also fails, it becomes impossible to steer. In consideration of such a risk, when a double failure occurs, evacuation traveling is performed. Even during the retreat travel, the remaining normal means can be used for steering.

  When the paddle shift switch 21-1 or the shift lever 21-2 fails, the alternative steer control device 100 may notify the driver of the failed part using the notification device 200 and prompt repair. When a double failure occurs, the alternative steer control device 100 may notify the driver of “immediately stopping and repairing” together with the failure portion using the notification device 200.

  As described above, according to the present embodiment, the backup is also duplicated. As a result, compared to the first embodiment described above, the fault tolerance and reliability of the steer-by-wire vehicle 1 are further improved. In particular, even if a single failure occurs, it is possible to continue normal driving, which is preferable.

3. Third embodiment 3-1. Configuration FIG. 6 is a block diagram schematically showing the configuration of a steer-by-wire vehicle 1 according to the third embodiment of the present invention. The description overlapping with the first embodiment is omitted as appropriate.

  The steer-by-wire vehicle 1 according to the present embodiment includes a yaw moment generator 40. The yaw moment generator 40 is a device for generating a desired yaw moment in the steer-by-wire vehicle 1. More specifically, the yaw moment generating device 40 includes at least one of the braking device 50 and the driving device 60. The yaw moment generating device 40 may be a combination of the braking device 50 and the driving device 60.

  The braking device 50 is configured to be able to control the braking force of each wheel 30 independently. More specifically, the braking device 50 includes a brake actuator that can independently control the pressure of the brake fluid supplied to the wheel cylinder of each wheel 30. A desired yaw moment can be generated by appropriately controlling the difference between the left and right braking forces.

  The drive device 60 is configured to be able to independently control the drive force of the left and right wheels 30 (drive wheels). For example, the drive device 60 is an in-wheel motor disposed in the vicinity of the drive wheel. A desired yaw moment can be generated by appropriately controlling the difference between the driving forces of the left and right driving wheels.

3-2. Alternative Steer Mode In this embodiment, a case where the steering actuator 14 of the steering device 10 fails is considered. When the steering actuator 14 breaks down, the wheel 30 cannot be steered by the steering actuator 14, and the steering by the steer-by-wire system cannot be performed as it is. Therefore, also in this case, the alternative steer control device 100 sets the steer-by-wire vehicle 1 to the alternative steer mode.

  For the sake of distinction, the alternative steer mode described in the first and second embodiments is referred to as “first alternative steer mode”, and the alternative steer mode in the present embodiment is referred to as “second alternative steer mode”. May be called.

  In the second alternative steer mode, since the steering of the wheel 30 by the steering actuator 14 is impossible, a desired vehicle turning is realized by using another means. Specifically, a desired yaw moment, that is, a desired vehicle turn is realized by using the “yaw moment generator 40” as a backup.

  The second alternative steer mode will be described in more detail with reference to FIG. First, the failure detection unit 15 detects a failure of the steering actuator 14. When the failure of the steering actuator 14 is detected, the failure detection unit 15 outputs an error signal indicating the failure to the alternative steering control device 100. In response to the error signal, the alternative steer control device 100 sets the steer-by-wire vehicle 1 (the steering device 10 and the yaw moment generator 40) to the second alternative steer mode.

  In the second alternative steer mode, the alternative steer control device 100 instructs the steering device 10 to supply the yaw moment generator 40 with information indicating the steering angle requested by the driver. In the present embodiment, the steering angle sensor 12 is normal, and the steering angle requested by the driver is detected by the steering angle sensor 12. Therefore, the alternative steering control device 100 instructs the steering controller 13 to transfer the steering angle signal output from the steering angle sensor 12 to the yaw moment generator 40. In accordance with the instruction, the steering controller 13 supplies a steering angle signal to the yaw moment generator 40.

  Further, the alternative steer control device 100 instructs the yaw moment generator 40 to generate a target yaw moment according to the steering angle requested by the driver. The yaw moment generator 40 generates a target yaw moment corresponding to the steering angle requested by the driver in accordance with the instruction. The yaw moment generator 40 may detect the actual yaw moment that is actually generated and perform feedback control based on the difference between the actual yaw moment and the target yaw moment.

  During normal running, the vehicle stability control such as VSC (Vehicle Stability Control) can be performed using the yaw moment generator 40. In the second alternative steer mode, since the yaw moment generator 40 is used for the alternative steer, the function of such vehicle stability control is limited. Therefore, the alternative steer control device 100 may notify the driver that “the vehicle abnormality control is limited” together with “the abnormality has occurred in the steering” using the notification device 200.

3-3. Effect As described above, according to the present embodiment, when the steering by the steering actuator 14 becomes impossible, instead, the yaw moment generator 40 generates the target yaw moment, and the desired vehicle Realize turning. The yaw moment generation device 40 (braking device 50, drive device 60) is an existing part that is not generally related to steering, but is generally mounted on a vehicle. By using such a yaw moment generator 40 as a backup, the same effects as those of the first embodiment can be obtained.

4). Fourth Embodiment FIG. 7 is a block diagram schematically showing a configuration of a steer-by-wire vehicle 1 according to a fourth embodiment of the present invention. The description overlapping with the third embodiment will be omitted as appropriate.

  In the present embodiment, a braking device 50 is used as the yaw moment generator 40. The braking device 50 supplies brake fluid to the wheel cylinder of the wheel 30 through the hydraulic system 51. In the present embodiment, the braking device 50 includes two independent hydraulic systems 51-1 and 51-2.

  More specifically, the braking device 50 includes a first hydraulic system 51-1, a second hydraulic system 51-2, a brake controller 53, and a brake actuator 54. The first hydraulic system 51-1 and the second hydraulic system 51-2 have, for example, a well-known H-type piping shape. The brake actuator 54 supplies brake fluid using these two hydraulic systems 51-1 and 51-2 to generate a braking force. The brake controller 53 is a control device that controls the operation of the brake actuator 54. Typically, the brake controller 53 is realized by an ECU.

  In the second alternative steer mode, the steering controller 13 of the steering device 10 supplies information indicating the steering angle requested by the driver to the brake controller 53. The brake controller 53 calculates a target yaw moment according to the steering angle requested by the driver. The brake controller 53 controls the operation of the brake actuator 54 so that the target yaw moment is achieved.

  Here, according to the present embodiment, there are two hydraulic systems 51-1 and 51-2. Therefore, even if either one of the two hydraulic systems 51-1 and 51-2 fails, there is a possibility that the target yawment can be realized by using the other normal one. That is, according to the present embodiment, the backup of the steering actuator 14 is duplicated. As a result, the fault tolerance and reliability of the steer-by-wire vehicle 1 are further improved.

  A failure of the first hydraulic system 51-1 or the second hydraulic system 51-2 is detected by the failure detection unit 55. When the failure detection unit 55 detects a failure in the first hydraulic system 51-1 or the second hydraulic system 51-2, the failure detection unit 55 outputs an error signal indicating the failure to the alternative steering control device 100. In the second alternative steer mode, the alternative steer control device 100 selects, as a backup, one of the first hydraulic system 51-1 and the second hydraulic system 51-2 that has not failed. Then, the alternative steer control device 100 instructs the braking device 50 (brake controller 53) to generate the target yaw moment using the selected hydraulic system 51.

  FIG. 8 is a table schematically showing the second alternative steer mode of steer-by-wire vehicle 1 according to the present embodiment.

  When any one of the steering actuator 14, the first hydraulic system 51-1 (backup 1), and the second hydraulic system 51-2 (backup 2) fails, it is a “single failure”. When the backup is duplicated, normal driving can be continued even if a single failure occurs.

  When two of the steering actuator 14, the first hydraulic system 51-1 and the second hydraulic system 51-2 fail, it is a “double failure”. After the double failure occurs, if the remaining last means also fails, the vehicle cannot turn. In consideration of such a risk, when a double failure occurs, evacuation traveling is performed. Even during the retreating traveling, it is possible to turn the vehicle using the remaining normal means.

  When the first hydraulic system 51-1 or the second hydraulic system 51-2 fails, the alternative steer control device 100 may notify the driver of the failed part using the notification device 200 and prompt repair. When a double failure occurs, the alternative steer control device 100 may notify the driver of “immediately stopping and repairing” together with the failure portion using the notification device 200.

  As described above, according to the present embodiment, the backup is also duplicated. As a result, compared with the third embodiment described above, the fault tolerance and reliability of the steer-by-wire vehicle 1 are further improved. In particular, even if a single failure occurs, it is possible to continue normal driving, which is preferable.

5). Fifth Embodiment The fifth embodiment of the present invention is a combination of the first or second embodiment and the third or fourth embodiment. Such a combination further improves the fault tolerance and reliability of the steer-by-wire vehicle 1.

  FIG. 9 is a block diagram schematically showing an example of the configuration of the steer-by-wire vehicle 1 according to the present embodiment. The example shown in FIG. 9 is a combination of the first embodiment (see FIG. 1) and the third embodiment (see FIG. 6). By such a combination, the effects of both the first embodiment and the third embodiment can be obtained.

  FIG. 10 is a block diagram schematically showing another example of the configuration of the steer-by-wire vehicle 1 according to the present embodiment. The example shown in FIG. 10 is a combination of the second embodiment (see FIGS. 4 and 5) and the fourth embodiment (see FIGS. 7 and 8). By such a combination, the effects of both the second embodiment and the fourth embodiment can be obtained.

  In order to describe the alternative steer mode in the configuration shown in FIG. 10 in more detail, a “steering detection system” and an “actuator system” are defined. The steering detection system includes a steering angle sensor 12, a paddle shift switch 21-1 (backup 1), and a shift lever 21-2 (backup 2). On the other hand, the actuator system includes a steering actuator 14, a first hydraulic system 51-1 (backup 1), and a second hydraulic system 51-2 (backup 2).

  The alternative steer mode when no failure has occurred in the actuator system and a single failure or double failure has occurred in the steering detection system is the same as in the second embodiment (see FIG. 5). On the other hand, the alternative steer mode when no failure has occurred in the steering detection system and a single failure or double failure has occurred in the actuator system is the same as in the fourth embodiment (see FIG. 8).

  Next, consider a case where a single failure occurs in each of the steering detection system and the actuator system, resulting in a double failure as a whole. FIG. 11 is a table schematically showing an alternative steer mode in such a case. As described above, when the backup is duplicated, normal traveling can be continued even if a single failure occurs (see FIGS. 5 and 8). Therefore, even when a single failure occurs in each of the steering detection system and the actuator system and a double failure occurs as a whole, normal traveling can be continued.

  Thus, according to the present embodiment, steer-by-wire vehicle 1 having excellent fault tolerance and reliability is realized.

DESCRIPTION OF SYMBOLS 1 Steer-by-wire vehicle 10 Steering device 11 Steering wheel 12 Steering angle sensor 13 Steering controller 14 Steering actuator 15 Failure detection unit 20 Transmission device 21 Shift operation means 21-1 Paddle shift switch 21-2 Shift lever 23 Transmission controller 24 Transmission mechanism 25 Failure Detection unit 30 Wheel 40 Yaw moment generator 50 Braking device 51 Hydraulic system 51-1 First hydraulic system 51-2 Second hydraulic system 53 Brake controller 54 Brake actuator 55 Failure detection unit 60 Drive device 100 Alternative steer control device 200 Notification device

Claims (1)

Steer-by-wire steering device that steers in response to the operation of the steering wheel;
A transmission device having an automatic mode for automatically switching a gear ratio, and a manual mode for switching the gear ratio in response to a manual operation of a shift operation means,
When the operation amount of the steering wheel becomes undetectable,
The transmission device is set to the automatic mode;
The steering device steers in accordance with the operation of the shift operation means instead of the operation of the steering wheel.

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