Vehicle control device and vehicle control program

Abstract

To prevent vehicle turning performance from deteriorating due to unavailability of a front wheel turning device.SOLUTION: A vehicle 10 includes: a plurality of vehicle devices configured to adjust an amount of travel of the vehicle 10 in a left-right direction; and a handle lock mechanism 20 switchable between an operation state of disabling the rotation of a handle 11 of a steering wheel and a non-operation state of permitting the rotation of the handle 11. One of the plurality of vehicle devices is a front wheel turning device 40 that applies turning force for turning a front wheel 16. A control device 100 switches a state of the handle lock mechanism 20 from the non-operation state to the operation state when a failure occurs in the front wheel turning device 40. The control device 100 activates a device other than the front wheel turning device 40 of the plurality of vehicle devices when the rotation of the handle 11 is disabled, and thus adjusts the amount of travel of the vehicle 10 in the left-right direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device and a vehicle control program. [Background technology]

[0002] Patent document 1 describes an example of a control device that turns a vehicle by generating a braking force difference or a driving force difference between the left and right wheels when an abnormality occurs in a steering device that adjusts the steering of the left and right wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] German Patent Application Publication No. 102016223766 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle is turning, a self-aligning torque is generated in the wheels. Therefore, when a braking force difference or a driving force difference is generated between the left and right wheels as described above to turn the vehicle, the generation of the self-aligning torque may prevent the vehicle from turning as desired. In other words, there is room for improvement in turning the vehicle when the steering device cannot be used. [Means for solving the problem]

[0005] A vehicle control device for solving the above problem comprises a plurality of wheels, a plurality of vehicle devices configured to adjust the amount of left and right movement of the vehicle, a handle lock mechanism that switches between an operating state that disables rotation of the steering wheel and a non-operating state that allows rotation of the handle, and a steering shaft that is connected to front wheels of the plurality of wheels and operates in response to rotation of the handle to turn the front wheels, and is applied to a vehicle in which one of the plurality of vehicle devices is a front wheel steering device that imparts a steering force to the steering shaft to turn the front wheels, and the vehicle control device comprises a handle lock control unit that switches the state of the handle lock mechanism from the non-operating state to the operating state when an abnormality occurs in the front wheel steering device, and an other device control unit that adjusts the amount of left and right movement of the vehicle by operating other devices of the plurality of vehicle devices other than the front wheel steering device when the handle lock mechanism enters the operating state.

[0006] If an abnormality occurs in the front wheel steering device, other devices are activated to adjust the amount of left and right movement of the vehicle. According to the above configuration, the steering lock mechanism is activated in this case. When the steering lock mechanism is activated and the steering wheel cannot be turned, steering of the front wheels is restricted. By activating other devices to adjust the amount of left and right movement of the vehicle in this state, the vehicle can be turned without being affected by self-aligning torque, even when the front wheel steering device cannot be used.

[0007] That is, according to the above configuration, it is possible to suppress a decrease in the turning performance of the vehicle caused by the inability to use the front wheel steering device. A vehicle control program for solving the above problem is a vehicle control program for turning a vehicle that includes a plurality of wheels, a plurality of vehicle devices configured to adjust the amount of left and right movement of the vehicle, a steering lock mechanism that switches between an operating state that disables rotation of the steering wheel and a non-operating state that allows rotation of the steering wheel, and a steering shaft that is connected to front wheels of the plurality of wheels and operates in response to rotation of the steering wheel to turn the front wheels, and one of the plurality of vehicle devices is a front wheel steering device that imparts a steering force to the steering shaft to turn the front wheels, and causes an executing device to execute a steering lock process that switches the state of the steering lock mechanism from the non-operating state to the operating state when an abnormality occurs in the front wheel steering device, and an other device control process that adjusts the amount of left and right movement of the vehicle by operating another device of the plurality of vehicle devices other than the front wheel steering device when the steering lock mechanism enters the operating state.

[0008] According to the above configuration, by having the execution device execute each process, it is possible to obtain the same functions and effects as the above vehicle control device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a vehicle equipped with a control device that is a first embodiment of a vehicle control device. [Figure 2] FIG. 2 is a cross-sectional view illustrating the handle lock mechanism. [Figure 3] FIG. 3 is a cross-sectional view illustrating the handle lock mechanism. [Figure 4] FIG. 4 is a flowchart illustrating a processing routine for the automatic steering function executed by the control device. [Figure 5] FIG. 5 is a time chart showing the execution of the processing routine for the automatic steering function. [Figure 6] FIG. 6 is a diagram showing a schematic configuration of a vehicle equipped with a control device that is a second embodiment of the vehicle control device. [Figure 7] FIG. 7 is a flowchart illustrating a processing routine for the automatic steering function executed by the control device. [Figure 8] FIG. 8 is a diagram illustrating the principle of adjusting the steering angle of the front wheels by steering the rear wheels. [Figure 9] FIG. 9 is a time chart showing the execution of a processing routine for the automatic steering function when an abnormality occurs in the front wheel steering device while the vehicle is traveling straight. [Figure 10] FIG. 10 is a schematic diagram showing how the front and rear wheels are steered in accordance with the execution of a processing routine for the automatic steering function when an abnormality occurs in the front wheel steering device while the vehicle is traveling straight. [Figure 11] FIG. 11 is a schematic diagram showing how the front and rear wheels are steered in accordance with the execution of a processing routine for the automatic steering function when an abnormality occurs in the front wheel steering device while the vehicle is traveling straight. [Figure 12] FIG. 12 is a time chart showing the execution of a processing routine for the automatic steering function when an abnormality occurs in the front wheel steering device while the vehicle is turning. [Figure 13] FIG. 13 is a schematic diagram showing how the front and rear wheels are steered in accordance with the execution of a processing routine for the automatic steering function when an abnormality occurs in the front wheel steering device while the vehicle is turning. [Figure 14] FIG. 14 is a schematic diagram showing a modification of the second embodiment. [Figure 15] FIG. 15 is a schematic diagram showing a modification of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) A first embodiment of a vehicle control device and a vehicle control program will be described below with reference to FIGS.

[0011] FIG. 1 shows a vehicle 10 equipped with a control device 100, which is a vehicle control device according to this embodiment. <Overall vehicle configuration> As shown in Fig. 1, a vehicle 10 includes a steering wheel 11, an input shaft 12, an output shaft 13, two front wheels 16, and two rear wheels 18. The vehicle 10 also includes two vehicle devices configured to adjust the yaw rate YR as the amount of left and right movement of the vehicle 10. One of the two vehicle devices is a front wheel steering device 40, and the other is a steering angle adjustment device 30. In this embodiment, the steering angle adjustment device 30 corresponds to the "other device."

[0012] Because steering wheel 11 is connected to input shaft 12, steering wheel 11 and input shaft 12 rotate as a single unit. Input shaft 12 is connected to output shaft 13 via steering angle adjuster 30. Output shaft 13 is connected to steered shaft 14. Pinion teeth 13a formed on output shaft 13 mesh with rack teeth 14a formed on steered shaft 14. Therefore, output shaft 13 and steered shaft 14 move in conjunction with each other. In other words, when output shaft 13 rotates, steered shaft 14 moves linearly. Both ends of steered shaft 14 are connected to left and right front wheels 16 via tie rods 15. When steered shaft 14 operates in response to the movement of input shaft 12 etc. resulting from the rotation of steering wheel 11, two front wheels 16 are steered.

[0013] The steering angle adjuster 30 separates the power transmission between the steering wheel 11 and the steered shaft 14. That is, the steering angle adjuster 30 includes an electric motor 32 and a reduction gear mechanism 34. The electric motor 32 has a housing 32a and a drive shaft 32b protruding from the housing 32a. A stator and a rotor are housed within the housing 32a. The stator is fixed to the housing 32a in a manner that allows them to rotate integrally. The rotor is connected to the drive shaft 32b in a manner that allows them to rotate integrally. When the drive shaft 32b is rotated by the driving of the electric motor 32, the output shaft 13 rotates relative to the input shaft 12. Accordingly, the steering angle ratio Z, which is the ratio of the steering angle θf of the front wheels 16 to the steering angle θh, which is the rotation angle of the steering wheel 11, changes. Therefore, when the steering angle θh is fixed, the steering angle θf of the front wheels 16 changes by changing the steering angle ratio Z through the operation of the steering angle adjuster 30.

[0014] The steering angle θh is defined as an angle from the neutral position of the steering wheel 11 corresponding to the straight-ahead state of the vehicle 10, and takes a positive or negative value depending on the turning direction of the steering wheel 11. Similarly, the turning angle θf of the front wheels 16 is defined as an angle from the neutral position of the front wheels 16 corresponding to the straight-ahead state of the vehicle 10, and takes a positive or negative value depending on the turning direction of the front wheels 16.

[0015] Front wheel steering device 40 includes an electric motor 42 and a transmission mechanism 44. The drive shaft of electric motor 42 is connected to steering shaft 14 via transmission mechanism 44. Transmission mechanism 44 converts the rotational movement of the drive shaft of electric motor 42 into linear movement of steering shaft 14. Therefore, when steering shaft 14 moves linearly in response to the drive of electric motor 42, the two front wheels 16 are steered. In other words, electric motor 42 applies a steering force to steering shaft 14, which is a force that steers front wheels 16.

[0016] The vehicle 10 is equipped with a steering wheel lock mechanism 20. The steering wheel lock mechanism 20 switches between an activated state in which rotation of the steering wheel 11 is disabled and a deactivated state in which rotation of the steering wheel 11 is permitted. In this embodiment, the steering wheel lock mechanism 20 disables rotation of the steering wheel 11 by restricting rotation of the input shaft 12.

[0017] 2 and 3 show a schematic configuration of the handlebar lock mechanism 20. Fig. 2 shows the relationship between the handlebar lock mechanism 20 and the input shaft 12 when the steering angle θh is 0 (zero). Fig. 3 shows the relationship between the handlebar lock mechanism 20 and the input shaft 12 when the steering angle θh is not 0 (zero).

[0018] The handlebar lock mechanism 20 includes a lock pin 22 and an actuator 24. The lock pin 22 is disposed radially outward of the input shaft 12. A tip 22a of the lock pin 22 faces the circumferential surface of the input shaft 12. When the actuator 24 is driven, the lock pin 22 moves in an approaching direction W1, which is a direction toward the input shaft 12, and in a separating direction W2, which is a direction away from the input shaft 12. That is, when the lock pin 22 moves in the approaching direction W1 due to the driving of the actuator 24, the tip 22a of the lock pin 22 is pressed against the input shaft 12 as shown by the solid line in FIG. 2. On the other hand, when the lock pin 22 moves in the separating direction W2 due to the driving of the actuator 24, the lock pin 22 moves away from the input shaft 12 as shown by the two-dot chain line in FIG. 2.

[0019] In this embodiment, the state of the handle lock mechanism 20 in which the lock pin 22 is pressed against the input shaft 12 by the drive of the actuator 24 is the "activated state." On the other hand, the state of the handle lock mechanism 20 in which the lock pin 22 is separated from the input shaft 12 is the "inactivated state."

[0020] The input shaft 12 is provided with two locking recesses 12a capable of accommodating the tip end 22a of the locking pin 22. The locking recesses 12a are recessed radially inward from the circumferential surface of the input shaft 12. The two locking recesses 12a are each disposed at the same position as the locking pin 22 in the direction along the central axis of the input shaft 12. When the position of the input shaft 12 with which the locking pin 22 contacts when the steering angle θh is 0 (zero) is defined as a reference position 12s, the two locking recesses 12a are disposed such that the reference position 12s is located between the two locking recesses 12a. The distance from one of the two locking recesses 12a to the reference position 12s is the same as the distance from the other locking recess 12a to the reference position 12s.

[0021] As shown in FIG. 2, when the steering angle θh is 0 (zero), the tip 22a of the lock pin 22 is not accommodated in the lock recess 12a even when the steering lock mechanism 20 is activated. Therefore, rotation of the input shaft 12 and the steering wheel 11 is permitted. However, when the steering angle θh changes from 0 (zero) and the lock pin 22 and the lock recess 12a come face to face with each other while the steering lock mechanism 20 is activated, the tip 22a of the lock pin 22 is accommodated in the lock recess 12a as shown in FIG. 3. This prevents the input shaft 12 and the steering wheel 11 from rotating. In this embodiment, the tip 22a of the lock pin 22 can be accommodated in the lock recess 12a whether the steering angle θh changes from 0 (zero) to the positive side or whether the steering angle θh changes from 0 (zero) to the negative side. The steering angle θh when the lock pin 22 and the lock recess 12a come face to face with each other is referred to as the "lock angle θhQ."

[0022] As shown in FIG. 1, the vehicle 10 is equipped with an information detection system. The information detection system includes, for example, a steering angle sensor 81, an output shaft sensor 82, a current sensor 83, and a temperature sensor 84. The information detection system also includes, for example, a vehicle speed sensor 85, a yaw rate sensor 86, a GPS receiver 87, and surroundings monitoring equipment 88. The steering angle sensor 81 detects the steering angle θh of the steering wheel 11. The output shaft sensor 82 detects the rotation angle θu of the output shaft 13. The current sensor 83 detects the value of current MA flowing through the electric motor 42 of the front wheel steering device 40. The temperature sensor 84 detects the temperature MT of the electric motor 42 of the front wheel steering device 40. The vehicle speed sensor 85 detects the vehicle speed V, which is the traveling speed of the vehicle 10. The yaw rate sensor 86 detects the yaw rate YR of the vehicle 10. The GPS receiver 87 receives a signal related to the current position coordinate G of the vehicle 10 from a GPS satellite. The surroundings monitoring equipment 88 includes an imaging device such as a camera, and a radar. The periphery monitoring device 88 acquires periphery monitoring information J of the vehicle 10, such as captured images of the periphery of the vehicle 10 and the presence or absence of obstacles around the vehicle 10. Devices such as sensors that constitute the information detection system output signals to the control device 100 according to the information that they themselves have detected or acquired.

[0023] The vehicle 10 is equipped with an alarm device 90. The alarm device 90 is a device that notifies the occupants of the vehicle 10 of an abnormality in the front wheel steering device 40. The alarm device 90 may be, for example, a lamp, a display screen, or a speaker.

[0024] <Overall configuration of the control device> The control device 100 includes a processing circuit 110. The processing circuit 110 includes a CPU 111 and a memory 112. The memory 112 stores various control programs executed by the CPU 111. In other words, the CPU 111 corresponds to an "execution device" that executes the control programs.

[0025] The control device 100 has an automatic driving function. The automatic driving function is a function that causes the vehicle 10 to travel autonomously without the driver of the vehicle 10 operating the vehicle. The control device 100 has an automatic steering function, which is one of the automatic driving functions. The automatic steering function is a function that causes the vehicle 10 to turn autonomously without the driver operating the steering wheel 11.

[0026] By the CPU 111 executing such a control program for the automatic steering function, the processing circuit 110 functions as a request generation unit, an abnormality determination unit, a front wheel steering control unit, a handle lock control unit, and an other device control unit.

[0027] The requirement generation unit derives required basic values ​​required for turning the vehicle 10. As the required basic values, the requirement generation unit derives a required steering angle θf* that is a required value for the steering angle θf of the front wheels 16, and a required yaw rate YR* that is a required value for the yaw rate YR of the vehicle 10. The method of deriving the required steering angle θf* and the required yaw rate YR* will be described later.

[0028] The abnormality determination unit determines whether an abnormality has occurred in front wheel steering device 40. The steering force that needs to be applied to front wheels 16 to adjust the steering angle θf of front wheels 16 based on the required steering angle θf* is called required steering force F1. The steering force that corresponds to the maximum output of electric motor 42 of front wheel steering device 40 is called maximum steering force F2. For example, if an internal abnormality occurs in electric motor 42 due to aging or the like, the amount of current that can be supplied to electric motor 42 may decrease, causing maximum steering force F2 to decrease. If maximum steering force F2 decreases, it may not be possible to make maximum steering force F2 equal to or greater than required steering force F1. Therefore, the abnormality determination unit determines whether an abnormality has occurred in front wheel steering device 40 based on the relative magnitude relationship between maximum steering force F2 and required steering force F1.

[0029] The front wheel steering control unit operates the front wheel steering device 40 when no abnormality has occurred in the front wheel steering device 40, thereby turning the vehicle 10. In other words, the front wheel steering control unit drives the electric motor 42 of the front wheel steering device 40 so that the steering angle θf of the front wheels 16 becomes the required steering angle θf*. On the other hand, when an abnormality has occurred in the front wheel steering device 40, the front wheel steering control unit stops the supply of electricity to the electric motor 42 of the front wheel steering device 40.

[0030] The handle lock control unit switches the state of the handle lock mechanism 20 from a non-operating state to an operating state when an abnormality occurs in the front wheel steering device 40. On the other hand, when no abnormality occurs in the front wheel steering device 40, the handle lock control unit sets the state of the handle lock mechanism 20 to a non-operating state.

[0031] When the steering wheel lock mechanism 20 is in an activated state, the other device control unit adjusts the yaw rate YR of the vehicle 10 by activating other devices other than the front wheel steering device 40. In other words, the other device control unit adjusts the steering angle ratio Z by activating the steering angle adjustment device 30 so that the steering angle θh is the lock angle θhQ and the steering angle θf of the front wheels 16 is the required steering angle θf*.

[0032] In this embodiment, the other device control unit executes a process for disabling rotation of the steering wheel 11 by rotating the steering wheel 11 until the steering angle θh becomes the lock angle θhQ, and a process for steering the front wheels 16 so that the steering angle θf becomes the requested steering angle θf* after the rotation of the steering wheel 11 becomes disabled. Of these processes, the latter process corresponds to a process for adjusting the yaw rate YR of the vehicle 10 through the operation of the steering angle adjuster 30 when the steering wheel lock mechanism 20 is activated and the rotation of the steering wheel 11 becomes disabled.

[0033] <Procedure for making a vehicle turn independently> 4, a processing routine executed by the processing circuit 110 of the control device 100 when turning the vehicle 10 using the automatic steering function will be described. The processing circuit 110 executes this processing routine by having the CPU 111 execute a control program stored in the memory 112 of the processing circuit 110. Therefore, it can be said that the CPU 111, which is an execution device, executes each step constituting this processing routine.

[0034] In this processing routine, in step S10, the processing circuit 110 functions as a request generator to derive the requested yaw rate YR* and the requested steering angle θf* as requested basic values. The processing of step S10 executed by the processing circuit 110 as the request generator is also referred to as "request generation processing."

[0035] An example of the request generation process will be described. When deriving the requested basic value, the processing circuit 110 derives a subsequent target trajectory of the vehicle 10 based on, for example, map data provided by a navigation device, the current position coordinate G of the vehicle 10, and surroundings monitoring information J. Then, the control device 100 derives a requested yaw rate YR* and a requested steering angle θf* based on the derived target trajectory and current driving information of the vehicle 10, such as the vehicle speed V and the yaw rate YR.

[0036] Once the required basic value has been derived, processing circuit 110 proceeds to step S20. In step S20, processing circuit 110 derives required steering force F1. Processing circuit 110 can calculate required steering force F1 using, for example, the following relational expression (Equation 1). In relational expression (Equation 1), "Kf" is the cornering power of front wheels 16, and "β*" is the required value of vehicle body slip angle. "Lf" is the distance between the center of gravity of vehicle 10 and the axle of front wheels 16, and "LN" is the sum of caster trail and pneumatic trail. When deriving required steering force F1, processing circuit 110 substitutes the latest vehicle speed V for "V" in relational expression (Equation 1), and substitutes the required yaw rate YR* and required steering angle θf* derived in step S10 for "YR*" and "θf*" in relational expression (Equation 1). Of the above parameters required to derive the required steering force F1, for example, the required steering angle θf*, which has a positive or negative value, the absolute value is used.

[0037] F1=Kf·(β*+Lf / V·YR*-θf*)·LN…(Formula 1) Next, in step S30, processing circuit 110 derives maximum steering force F2. Control device 100 calculates maximum steering force F2 using, for example, relational expression (Equation 2). In relational expression (Equation 2), "I" is the maximum value of current that can currently be applied to electric motor 42 of front wheel steering device 40, and "LS" is a parameter related to the positional relationship between the ground contact points of front wheels 16 and tie rod 15. Also, "D" is a conversion coefficient. For this reason, the larger the maximum current value I, the larger the value that is derived as maximum steering force F2.

[0038] F2=I·D·LS…(Equation 2) In the next step S40, processing circuit 110 functions as an abnormality determination section, and determines whether or not the required steering force F1 derived in step S20 is equal to or less than the maximum steering force F2 calculated in step S30. If the required steering force F1 is equal to or less than the maximum steering force F2, it is determined that no abnormality has occurred in front wheel steering device 40. On the other hand, if the required steering force F1 is greater than the maximum steering force F2, it is determined that an abnormality has occurred in front wheel steering device 40. In this embodiment, the process of step S40 executed by processing circuit 110 as an abnormality determination section corresponds to the "abnormality determination process."

[0039] If, in step S40, required steering force F1 is equal to or less than maximum steering force F2 (YES), processing circuit 110 proceeds to step S50. In step S50, processing circuit 110 functions as a front wheel steering control unit, thereby controlling front wheel steering device 40 based on required steering angle θf*. Specifically, processing circuit 110 controls electric motor 42 of front wheel steering device 40 so that the steering angle θf of front wheels 16 becomes required steering angle θf*. The processing of step S50, which is executed by processing circuit 110 as a front wheel steering control unit, is also referred to as "front wheel turning processing."

[0040] It should be noted that when the front wheels 16 are steered by the front wheel steering device 40 in step S50, the rotation angle of the electric motor 32 of the steering angle adjustment device 30 is maintained. Therefore, the steering wheel 11 rotates in conjunction with the steering of the front wheels 16. Therefore, the steering angle θf of the front wheels 16 and the steering angle θh of the steering wheel 11 are maintained equal. After executing the processing of step S50, the processing circuit 110 temporarily ends this processing routine. Thereafter, when a predetermined control cycle has elapsed, the processing circuit 110 starts executing this processing routine.

[0041] On the other hand, in step S40, if the required steering force F1 is greater than the maximum steering force F2 (NO), processing circuit 110 proceeds to step S100. In step S100, control device 100 causes notification device 90 to notify the occupant that an abnormality has occurred in front wheel steering device 40.

[0042] Subsequently, in step S102, the processing circuit 110 functions as a front wheel steering control unit to stop the supply of electricity to the electric motor 42 of the front wheel steering device 40. Then, the processing circuit 110 moves the processing to step S110.

[0043] In step S110, the processing circuit 110 functions as a steering lock control unit to switch the state of the steering lock mechanism 20 from a non-operated state to an activated state. As a result, the lock pin 22 moves in the approach direction W1, and its tip portion 22a comes into contact with the input shaft 12. In this embodiment, the processing of step S110 executed by the processing circuit 110 as a steering lock control unit corresponds to a "steering lock processing." As described above, even when the steering lock mechanism 20 is in the activated state, the tip portion 22a of the lock pin 22 is not accommodated in the lock recess 12a until the steering angle θh of the steering wheel 11 becomes the lock angle θhQ, and therefore rotation of the steering wheel 11 is permitted. When the steering wheel lock mechanism 20 is switched to the activated state, the processing circuit 110 proceeds to step S160.

[0044] In step S160, processing circuit 110 functions as a request generator to derive a requested yaw rate YR* and a requested turning angle θf* in the same manner as in the processing of step S10. Subsequently, in step S170, processing circuit 110 functions as an other device control unit to adjust the steering angle ratio Z based on the requested turning angle θf* derived in step S160. That is, processing circuit 110 controls electric motor 32 of steering angle adjustment device 30 so that the turning angle θf of the front wheels 16 becomes the requested turning angle θf*. In this case, processing circuit 110 determines the direction in which the front wheels 16 should be steered based on the positive or negative sign of the requested turning angle θf* derived in step S160. Then, processing circuit 110 determines the rotation direction of drive shaft 32b of electric motor 32 relative to housing 32a so that the front wheels 16 are steered in this direction. In this embodiment, the process of step S170 executed by the processing circuit 110 as the other device control unit corresponds to the "other device control process."

[0045] Thereafter, in step S180, the processing circuit 110 determines whether or not a termination condition is met. The termination condition is that both the vehicle 10 is not turning and a request to stop the automatic steering function is made. If it can be determined that the vehicle 10 is traveling straight based on the yaw rate YR or if the vehicle 10 has stopped, it can be assumed that the vehicle 10 is not turning. If the termination condition is not met (S180: NO), the processing circuit 110 proceeds to step S160. On the other hand, if the termination condition is met (S180: YES), the processing circuit 110 terminates this processing routine.

[0046] <Actions and Effects of the First Embodiment> Referring to FIG. 5, a case where the vehicle 10 is turned in a state where an abnormality occurs in the front wheel steering device 40 will be described.

[0047] In the example shown in Figure 5, vehicle 10 is traveling straight at timing t11. As shown by the two-dot chain lines in Figure 5(a) and (b), at timing t12 after timing t11, a turning request occurs and requested yaw rate YR* and requested steering angle θf* become greater than 0 (zero). Note that in Figure 5, for ease of understanding the explanation in the specification, requested yaw rate YR* and requested steering angle θf* are shown to change significantly in one step at timing t12.

[0048] When a turn request is made at timing t12, if the maximum steering force F2 is less than the requested steering force F1 (S40: NO), the state of the steering wheel lock mechanism 20 is switched from the inactive state to the active state (S110). Here, as shown in Figure 5(d), the steering angle θh of the steering wheel 11 at timing t12 is 0 (zero), and the steering angle θh is not the lock angle θhQ. Therefore, even if the steering wheel lock mechanism 20 is activated, rotation of the steering wheel 11 is still permitted.

[0049] When the steering lock mechanism 20 is switched to the activated state, as shown in FIG. 5(c), the steering angle adjuster 30 is activated to start changing the steering angle ratio Z (S170). Here, because the front wheels 16 are in contact with the ground, a force that resists the frictional force acting on the front wheels 16 according to the weight of the vehicle 10 is required to steer the front wheels 16. Due to the balance with this frictional force, immediately after the start of the change in the steering angle ratio Z, the driving force of the electric motor 32 acts to rotate the housing 32a, which is not subject to resistance, rather than the drive shaft 32b of the electric motor 32. In other words, the frictional force acting on the front wheels 16 prevents the rotation of the drive shaft 32b of the electric motor 32 via the output shaft 13. As a result, the housing 32a and the steering wheel 11 rotate without rotating the drive shaft 32b. Therefore, when the change in steering angle ratio Z starts at timing t12, the steering angle θh of the steering wheel 11 begins to change as shown in FIG. 5(d), while the steering angle θf of the front wheels 16 does not change as shown in FIG. 5(b). Note that due to the relative rotational relationship between the housing 32a and the drive shaft 32b of the electric motor 32, the steering wheel 11 rotates in the opposite direction to the rotational direction corresponding to the requested steering angle θf*. As shown in FIG. 5(d), the rotation of the steering wheel 11 causes the steering angle θh to become the lock angle θhQ at timing t13. Then, in the steering wheel lock mechanism 20, the tip portion 22a of the lock pin 22 is accommodated in the lock recess 12a. This disables the rotation of the steering wheel 11.

[0050] Even after the steering wheel 11 becomes unable to rotate, the steering angle ratio Z continues to be changed by the operation of the steering angle adjuster 30. When the steering wheel 11 becomes unable to rotate, the driving force of the electric motor 32 rotates the drive shaft 32b instead of the housing 32a. That is, the driving force of the electric motor 32 rotates the drive shaft 32b, and ultimately the output shaft 13, against the frictional force of the front wheels 16, while receiving a reaction force from the fixed housing 32a. Therefore, as shown in FIG. 5(b), after timing t13 when the steering wheel 11 becomes unable to rotate, the steering angle θf of the front wheels 16 begins to change due to the operation of the steering angle adjuster 30. Then, at timing t14, the steering angle θf of the front wheels 16 becomes the requested steering angle θf*. Through the above-described steering of the front wheels 16, the yaw rate YR of the vehicle 10 changes after timing t13. Then, after timing t14, the vehicle 10 turns according to the requested yaw rate YR*.

[0051] Thereafter, the steering angle adjuster 30 is operated to adjust the steering angle θf of the front wheels 16 while the rotation of the steering wheel 11 remains disabled (S170). In other words, by disabling the rotation of the steering wheel 11, the drive shaft 32b of the electric motor 32 in the steering angle adjuster 30 and the front wheels 16 are operated in conjunction with each other. This allows the front wheels 16 to be directly operated by the steering angle adjuster 30, in the same way that the front wheels 16 are operated by the front wheel steering device 40. Therefore, even when the front wheel steering device 40 cannot be used, the vehicle 10 can be turned without being affected by the self-aligning torque.

[0052] Note that the example shown in FIG. 5 is an example of a case where it is determined that an abnormality has occurred in the front wheel steering device 40 before the vehicle 10 starts turning. However, an abnormality may also occur in the front wheel steering device 40 while the vehicle 10 is turning. In this embodiment, the turning state of the vehicle 10 can be maintained even in such a case. That is, if it is determined that an abnormality has occurred in the front wheel steering device 40 while the vehicle 10 is turning (S40: YES), the state of the steering wheel lock mechanism 20 is switched from a non-operated state to an activated state (S110). Then, the steering angle adjustment device 30 is operated to change the steering angle ratio Z (S170). As a result, the steering wheel 11 rotates so that the steering angle θh approaches the lock angle θhQ in relation to the frictional force acting on the front wheels 16. Then, when the steering angle θh reaches the lock angle θhQ, the steering wheel 11 becomes unable to rotate. Once the steering wheel 11 becomes unable to rotate in this way, the steering angle θf of the front wheels 16 can be freely adjusted by operating the steering angle adjustment device 30 thereafter.

[0053] (Second embodiment) A second embodiment of a vehicle control device and a vehicle control program will be described below with reference to FIGS. 6 to 13. In this second embodiment, the vehicle device installed in the vehicle is different from that in the first embodiment, and the content of the other device control process is also different from that in the first embodiment. Other parts are basically the same as those in the first embodiment. Below, the parts that are different from the first embodiment will be mainly described, and the description of the content that overlaps with the first embodiment will be appropriately simplified or omitted. In FIG. 6, parts that are the same as or function substantially the same as those in FIG. 1 are denoted by the same reference numerals as in FIG. 1. In addition, in FIG. 6, the devices that make up the information detection system are collectively denoted by the unified reference numeral 80.

[0054] 6, vehicle 10A is not equipped with a steering angle adjustment device. Therefore, steering wheel 11 and input shaft 12 are directly connected to output shaft 13. That is, steering angle θh of steering wheel 11 and steering angle θf of front wheels 16 are the same.

[0055] Vehicle 10A is equipped with a rear shaft 181 and rear wheel steering device 120. Both ends of rear shaft 181 are connected to the left and right rear wheels 18 via connecting parts 183. Rear wheel steering device 120 is equipped with an electric motor 122 and a transmission mechanism 124. The drive shaft of electric motor 122 is connected to rear shaft 181 via transmission mechanism 124. Transmission mechanism 124 converts the rotational movement of the drive shaft of electric motor 122 into linear movement of rear shaft 181. The rear wheels 18 are steered by the linear movement of rear shaft 181 in response to the drive of electric motor 122. In this way, rear wheel steering device 120 adjusts the steering angle θr of rear wheels 18. In other words, vehicle 10A is equipped with front wheel steering device 40 and rear wheel steering device 120 as vehicle devices configured to adjust yaw rate YR as the amount of left and right movement of vehicle 10A. In this embodiment, the rear wheel steering device 120 corresponds to the "other device."

[0056] In this embodiment, when turning vehicle 10A under conditions in which an abnormality has occurred in front wheel steering device 40, control device 100 utilizes steering wheel lock mechanism 20 and rear wheel steering device 120. To this end, processing circuit 110 of control device 100 performs the following other device control processing after performing the same steering wheel lock processing as in the first embodiment. That is, processing circuit 110 functions as an other device control section, thereby performing first processing and second processing as the other device control processing.

[0057] In the first process, when the handlebar lock mechanism 20 is activated, the other device control unit steers the front wheels 16 by steering the rear wheels 18 using the rear wheel steering device 120. This causes the steering angle θf of the front wheels 16 to become the lock steering angle θfQ. The lock steering angle θfQ is the steering angle θf of the front wheels 16 when the steering angle θh of the handlebar 11 becomes the lock angle θhQ. As described above, the steering angle θf of the front wheels 16 and the steering angle θh of the handlebar 11 are the same. Therefore, the lock steering angle θfQ is the same as the lock angle θhQ.

[0058] In the second process, when the steering wheel 11 becomes unable to be turned due to the execution of the first process, the other device control unit operates the rear wheel steering device 120 to steer the rear wheels 18. This causes the vehicle 10A to turn.

[0059] <Procedure for making a vehicle turn independently> With reference to FIG. 7, a processing routine executed by the processing circuit 110 of the control device 100 when turning the vehicle 10A using the automatic turning function will be described.

[0060] When this processing routine starts, the processing circuit 110 sequentially executes a plurality of processes from steps S10 to S110 shown in Fig. 4. When the state of the handle lock mechanism 20 is switched from the inactive state to the active state by executing the process of step S110, the processing circuit 110 proceeds to step S220.

[0061] In step S220, processing circuit 110 determines whether the absolute value of the steering angle θf of front wheels 16 is less than the absolute value of lock steering angle θfQ. If the absolute value of the steering angle θf is less than the absolute value of lock steering angle θfQ (S220: YES), processing circuit 110 proceeds to step S230. On the other hand, if the absolute value of the steering angle θf is equal to or greater than the absolute value of lock steering angle θfQ (S220: NO), processing circuit 110 proceeds to step S250.

[0062] In step S230, processing circuit 110 functions as an external device control unit to steer rear wheels 18 in the same direction as requested turning angle θf* of front wheels 16. That is, processing circuit 110 determines the steering direction determined as requested turning angle θf* based on the positive or negative sign of requested turning angle θf* derived in step S10. Processing circuit 110 then controls electric motor 122 of rear wheel steering device 120 so that rear wheels 18 are steered in the same direction as requested turning angle θf*. At this time, processing circuit 110 sets steering angle θr of rear wheels 18 to a predetermined first steering angle. Note that, for reasons described below, steering rear wheels 18 in the same direction as requested turning angle θf* allows front wheels 16 to be steered in the direction of requested turning angle θf*. The first steering angle is determined in advance, for example, through experiments or simulations, as an optimal value for facilitating steering of front wheels 16. When the processing circuit 110 steers the rear wheels 18 until the steering angle θr of the rear wheels 18 becomes the first steering angle, the processing proceeds to step S240.

[0063] In step S240, processing circuit 110, functioning as an other device control unit, determines whether or not the steering angle θf of front wheels 16 has reached lock steering angle θfQ. Processing circuit 110 makes the determination in step S240 by comparing the absolute value of steering angle θf with the absolute value of lock steering angle θfQ. Because steering lock mechanism 20 is activated, it can be determined that when the steering angle θf reaches lock steering angle θfQ, it becomes impossible to rotate steering wheel 11. Therefore, if the steering angle θf has not reached lock steering angle θfQ (S240: NO), processing circuit 110 repeatedly executes the determination in step S240 until the steering angle θf reaches lock steering angle θfQ. On the other hand, if the steering angle θf has reached lock steering angle θfQ (S240: YES), processing circuit 110 proceeds to step S250.

[0064] In step S250, processing circuit 110 functions as an other device control unit to steer rear wheels 18 in the direction opposite to the requested turning angle θf* of front wheels 16. That is, similar to the processing of step S230, processing circuit 110 determines the steering direction determined as the requested turning angle θf* based on the positive or negative sign of the requested turning angle θf* derived in step S10. Then, processing circuit 110 controls electric motor 122 of rear wheel steering device 120 so that rear wheels 18 are steered in the direction opposite to this direction. More specifically, processing circuit 110 controls electric motor 122 so that turning angle θr of rear wheels 18 becomes a second turning angle. This second turning angle has the following value. That is, it is the steering angle θr of the rear wheels 18 required to achieve the requested yaw rate YR* derived in step S10 when the steering angle θf of the front wheels 16 is the lock steering angle θfQ in the same direction as the requested steering angle θf*. When the steering angle θr becomes the second steering angle, processing circuit 110 transitions the processing to step S260.

[0065] In this embodiment, the processes of steps S230 to S250 executed by the processing circuit 110 functioning as the other device control unit correspond to “other device control process.” In particular, the processes of steps S230 and S240 correspond to “first process,” and the process of step S250 corresponds to “second process.”

[0066] Here, the processing of step S250 may serve as both the first processing and the second processing of the other device control processing. That is, if the absolute value of the steering angle θf is equal to or greater than the absolute value of the lock steering angle θfQ in step S220 (NO), processing circuit 110 executes the processing of step S250 without going through the processing of steps S230 and S240. In this case, the steering angle θf of front wheels 16 has not reached the lock steering angle θfQ at the start of step S250. If the processing of step S250 is executed in this situation, as will be described in detail later, front wheels 16 are steered so that the steering angle θf of front wheels 16 reaches the lock steering angle θfQ. This makes it impossible to rotate steering wheel 11. After that, a series of operations occur in which vehicle 10A turns according to requested yaw rate YR*. In this case, the processing of step S250 serves as both the first processing and the second processing.

[0067] After executing the process of step S250, processing circuit 110 proceeds to step S260. In step S260, processing circuit 110 derives the required yaw rate YR* and the required steering angle θf* in the same manner as in step S160. Subsequently, in step S270, processing circuit 110 functions as an other device control unit to adjust the steering angle θr of rear wheels 18 based on the required yaw rate YR* derived in step S260. That is, processing circuit 110 controls electric motor 122 of rear wheel steering device 120 so that yaw rate YR becomes the required yaw rate YR*. Then, in step S280, processing circuit 110 determines whether a termination condition is met. The process of step S280 is the same as that of step S180 shown in FIG. 4. Therefore, a description of steps S280 and thereafter will be omitted.

[0068] <Actions and Effects of the Second Embodiment> In this embodiment, when the other device control process is executed, the steering angle θf of the front wheels 16 is adjusted by steering the rear wheels 18. The principle behind this will be explained first. Assume that the vehicle 10A is traveling straight. At this time, suppose that the rear wheels 18 are steered to the right, as shown by the solid line in FIG. 8. Then, the vehicle 10A attempts to turn left, as indicated by arrow N in FIG. 8. At this time, a self-aligning torque acts on the front wheels 16. As a result, the front wheels 16 are steered to the right in phase with the rear wheels 18, as shown by the solid line in FIG. 8. In this embodiment, the steering angle θf of the front wheels 16 is adjusted by utilizing this self-aligning torque acting on the front wheels 16 as the rear wheels 18 are steered. Incidentally, the vehicle 10A can be driven straight by steering the front wheels 16 and the rear wheels 18 in the same direction.

[0069] Based on the above principle, a case where the vehicle 10A is turned when an abnormality occurs in the front wheel steering device 40 will be described. The example shown in FIG. 9 is a case where an abnormality occurs in front wheel steering device 40 while vehicle 10A is traveling straight. In this example, vehicle 10A is traveling straight at timing t21. At timing t22, which is later than timing t21, a turn request occurs and requested yaw rate YR* becomes greater than 0 (zero), as shown by the two-dot chain line in FIG. 9(a). In the example shown in FIG. 9, an abnormality occurs in front wheel steering device 40 and front wheel steering device 40 cannot be operated (S40: NO). Therefore, at timing t22, the state of steering wheel lock mechanism 20 is switched from the inoperative state to the activated state (S110). Here, as shown in FIG. 9(b), the steering angle θf of front wheels 16 at timing t22 is 0 (zero), and the absolute value of this steering angle θf is smaller than the absolute value of lock steering angle θfQ. Therefore, at the timing t22 when the handlebar lock mechanism 20 is switched to the activated state, the rotation of the handlebar 11 and the steering of the front wheels 16 are still permitted.

[0070] For a period of time after timing t22 when the handlebar lock mechanism 20 is switched to the activated state, the rear wheels 18 are steered in the same direction as the requested steering angle θf* of the front wheels 16 (S230), as shown in (c) of Figure 9 and Figure 10. Then, in accordance with the operation of the front wheels 16 according to the self-aligning torque, the front wheels 16 are steered in the same direction as the rear wheels 18, as shown in (b) of Figure 9 and by the solid lines in Figure 10. Then, at timing t23, when the steering angle θf of the front wheels 16 reaches the lock steering angle θfQ (S240: YES), the tip end portion 22a of the lock pin 22 in the handlebar lock mechanism 20 is accommodated in the lock recessed portion 12a. This disables steering of the front wheels 16 and rotation of the handlebars 11.

[0071] After this timing t23, as shown in FIG. 9(c) and FIG. 11, the rear wheels 18 are steered in the direction opposite to the requested steering angle θf* of the front wheels 16 (S250). Accordingly, as shown in FIG. 9(a), the yaw rate YR of the vehicle 10A gradually approaches the requested yaw rate YR*. Then, at timing t24, the yaw rate YR of the vehicle 10A becomes the requested yaw rate YR*. The vehicle 10A then turns in accordance with the requested yaw rate YR*. At this time, because the steering of the front wheels 16 is disabled, the vehicle 10A can turn without being affected by the self-aligning torque.

[0072] The example shown in Figure 12 is a case where an abnormality occurs in front wheel steering device 40 while vehicle 10A is turning. In this example, as shown in Figure 12(a), vehicle 10A is turning at timing t31. At this point, front wheel steering device 40 is normal, and by operating front wheel steering device 40, the steering of front wheels 16 is adjusted so that steering angle θf of front wheels 16 becomes requested steering angle θf*. Also, at this time, steering angle θr of rear wheels 18 is 0 (zero). At timing t32, which is later than timing t31, an abnormality occurs in front wheel steering device 40, making it impossible to operate front wheel steering device 40 (S40: NO). In this case, the state of steering wheel lock mechanism 20 is switched from a non-operated state to an operated state at timing t32 (S110). 12(b), the steering angle θf of the front wheels 16 at time t32 is greater than the lock steering angle θfQ, and the steering angle θf is not the lock steering angle θfQ. Therefore, at time t32 when the handlebar lock mechanism 20 is switched to the activated state, rotation of the handlebars 11 and steering of the front wheels 16 are still permitted.

[0073] At timing t32, vehicle 10A is turning, and steering angle θf is greater than lock steering angle θfQ (S220: NO). Therefore, as shown in FIG. 12(c) and FIG. 13, after timing t32, rear wheels 18 are steered in the direction opposite to requested steering angle θf* of front wheels 16. Then, in accordance with the operation of front wheels 16 according to the self-aligning torque, front wheels 16 are steered to face the same direction as rear wheels 18, as shown by arrow K in FIG. 12(b) and FIG. 13, and the absolute value of steering angle θf of front wheels 16 decreases. Then, at timing t33, steering angle θf of front wheels 16 reaches lock steering angle θfQ. Then, in steering wheel lock mechanism 20, tip portion 22a of lock pin 22 is accommodated in lock recessed portion 12a. As a result, steering of front wheels 16 and rotation of steering wheel 11 become impossible. Thereafter, the vehicle 10A continues to turn according to the required yaw rate YR* by adjusting the steering angle θr of the rear wheels 18. At this time, the front wheels 16 cannot be steered, so the vehicle 10A can turn without being affected by the self-aligning torque.

[0074] As described above, in this embodiment, if an abnormality occurs in front wheel steering device 40, steering of front wheels 16 is disabled and then yaw rate YR of vehicle 10A is adjusted by rear wheels 18. Disabling steering of front wheels 16 eliminates the influence of self-aligning torque. Therefore, even when front wheel steering device 40 cannot be used, vehicle 10A can be turned without being influenced by self-aligning torque.

[0075] (Example of change) The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0076] The above termination conditions are not limited to those in the above embodiment, as long as they can terminate the other device control process at an appropriate timing. Even if the termination conditions are changed from those in the above embodiment, it is preferable to set conditions such that the other device control process terminates after the vehicle 10, 10A has finished turning. If the automatic driving mode based on the automatic driving function is switched to manual driving mode based on the driver's operation while the vehicle 10, 10A is traveling straight, the burden of driving operations on the driver is reduced.

[0077] The method for determining whether an abnormality has occurred in the front wheel steering device 40 is not limited to the methods described in the above embodiments. For example, it may be determined that an abnormality has occurred in the front wheel steering device 40 when the temperature MT of the electric motor 42 is higher than a specified threshold. Regardless of the method for determining an abnormality, in other words, regardless of how an abnormality is defined, if the front wheel steering device 40 cannot be used normally, the steering wheel lock mechanism 20 can be switched to an activated state and the yaw rate YR of the vehicle 10, 10A can be adjusted by a vehicle device other than the front wheel steering device 40.

[0078] It is not essential that the notification device 90 notify the driver when an abnormality occurs in the front wheel steering device 40. For example, when an abnormality occurs in the front wheel steering device 40, if the automatic driving function is stopped and the driver is notified of the end of the automatic driving function when the vehicle 10, 10A has finished turning, notification by the notification device 90 is not necessarily required.

[0079] As in the above embodiment, after adjusting the yaw rate YR of the vehicle 10, 10A using a vehicle device other than the front wheel steering device 40, the steering lock mechanism 20 may be switched to a deactivated state, for example, after the vehicle 10, 10A has finished turning. For example, the front wheel steering device 40 may accidentally be determined to be abnormal. In this case, even if the yaw rate YR of the vehicle 10, 10A is adjusted using a vehicle device other than the front wheel steering device 40 as in the above embodiment, the front wheel steering device 40 can then be used again. By switching the steering lock mechanism 20 to a deactivated state, the front wheels 16 can be steered by the front wheel steering device 40 as usual.

[0080] Regarding the second embodiment, the configuration of the rear wheel steering device 120 is not limited to the above example. The rear wheel steering device 120 may have any configuration as long as it can adjust the steering angle θr of the rear wheels 18. As shown in FIG. 14 , in the second embodiment, the vehicle 10A may be equipped with the following two devices instead of the rear-wheel steering device 120. The two devices are a front-wheel drive device 130 that can adjust the difference in driving force applied to the left front wheel 16A and the right front wheel 16B, and a rear-wheel drive device 140 that can adjust the difference in driving force applied to the left rear wheel 18A and the right rear wheel 18B. The front-wheel drive device 130 and the rear-wheel drive device 140 are vehicle devices configured to adjust the yaw rate YR of the vehicle 10A. Even when these drive devices are equipped, the vehicle 10A can be turned without using the front-wheel steering device 40 by using the same principle as in the second embodiment. For example, if an abnormality occurs in the front-wheel steering device 40 while the vehicle 10A is traveling straight, the steering lock mechanism 20 is switched to an activated state, and then, as a first process of the other device control process, the front-wheel drive device 130 is used to create a difference in driving force between the left front wheel 16A and the right front wheel 16B. As a result, the front wheels 16 are steered so that the turning angle θf of these front wheels 16A, 16B becomes the lock turning angle θfQ. Note that, as a first process, the rear-wheel drive device 140 may be used to impart a difference in driving force to the left rear wheel 18A and the right rear wheel 18B. As a result, the front wheels 16 may be steered so that the turning angle θf of these front wheels 16A, 16B becomes the lock turning angle θfQ by utilizing the self-aligning torque acting on the two front wheels 16A, 16B. Thereafter, as a second process of the other device control process, the rear-wheel drive device 140 is used to impart a difference in driving force to the left rear wheel 18A and the right rear wheel 18B. As a result, the yaw rate YR of the vehicle 10A is adjusted. If an abnormality occurs in the front-wheel steering device 40 while the vehicle 10A is turning, the rear-wheel drive device 140 may be used to impart a difference in driving force to the left rear wheel 18A and the right rear wheel 18B. This allows the first process and the second process to be performed simultaneously. In Fig. 14, parts that are the same as or have substantially the same functions as those in Fig. 6 are given the same reference numerals as those in Fig. 6. This also applies to Fig. 15, which will be referred to later.

[0081] In the above modified example, the vehicle 10A may be provided with only the rear-wheel drive unit 140 out of the front-wheel drive unit 130 and the rear-wheel drive unit 140. As long as the vehicle 10A is provided with the rear-wheel drive unit 140, the vehicle 10A can turn in the same manner as in the second embodiment, as described above.

[0082] As shown in FIG. 15 , in the second embodiment, the vehicle 10A may be provided with the following two devices instead of the rear-wheel steering device 120. That is, the two devices are a front-wheel braking device 150 that can adjust the difference in braking force applied to the left front wheel 16A and the right front wheel 16B, and a rear-wheel braking device 160 that can adjust the difference in braking force applied to the left rear wheel 18A and the right rear wheel 18B. The front-wheel braking device 150 and the rear-wheel braking device 160 are vehicle devices configured to adjust the yaw rate YR of the vehicle 10A. Even when these braking devices are provided, the vehicle 10A can turn in the same manner as in the second embodiment, as in the above-described modified example of the drive system. That is, instead of providing a difference in driving force between the left and right wheels in the above-described modified example of the drive system, a difference in braking force can be provided between the left and right wheels.

[0083] The vehicle 10A may be equipped with a plurality of vehicle devices other than the front wheel steering device 40. For example, the vehicle 10A may be equipped with a rear wheel steering device 120, a front wheel drive device 130, and a rear wheel drive device 140. Alternatively, for example, the vehicle 10A may be equipped with a rear wheel steering device 120, a front wheel braking device 150, and a rear wheel braking device 160. Alternatively, for example, the vehicle 10A may be equipped with a rear wheel steering device 120, a front wheel drive device 130, a rear wheel drive device 140, a front wheel braking device 150, and a rear wheel braking device 160. These may be used in combination to realize the turning of the vehicle 10A similar to that of the second embodiment.

[0084] The configuration of the front wheel steering device 40 is not limited to the example of the above embodiment. For example, the front wheel steering device 40 may be connected to the output shaft 13. The steering force may be applied to the steering shaft 14 via the output shaft 13. The front wheel steering device 40 may be configured in any way so as to be able to apply a steering force to the steering shaft 14.

[0085] The handlebar lock mechanism 20 is not limited to the example of the above embodiment. For example, the number, position, etc. of the lock recesses 12a may be changed from the example of the above embodiment. In other words, the lock angle θhQ may be changed. The number, position, etc. of the lock recesses 12a are not important as long as the handlebar 11 can be made unrotatable at an appropriate steering angle θh. The handlebar lock mechanism 20 does not have to use the lock recesses 12a and the lock pin 22. The handlebar lock mechanism 20 may be configured to switch between an activated state that disables the handlebar 11 from rotating and a deactivated state that allows the handlebar 11 to rotate.

[0086] The configuration of the steering angle adjustment device 30 is not limited to the example of the first embodiment. The steering angle adjustment device 30 may have any configuration as long as it can adjust the steering angle ratio Z by rotating the input shaft 12 and the output shaft 13 relative to each other.

[0087] Vehicle devices that can adjust the amount of left and right movement of the vehicle 10, 10A and that can be used as vehicle devices other than the front wheel steering device 40 are not limited to those described in the above embodiment and modified example. Any device can be used as long as it can adjust the amount of left and right movement of the vehicle 10, 10A when the steering lock mechanism 20 is activated and the steering wheel 11 cannot be turned. The content of the other device control process can be adjusted depending on the vehicle device to be used. The other device control process only needs to be able to appropriately turn the vehicle 10, 10A when the steering wheel 11 cannot be turned.

[0088] The amount of left and right movement of the vehicle 10, 10A may be calculated using the yaw rate, the lateral position, turning curvature, lateral speed, and lateral acceleration of the vehicle 10, 10A. The processing circuit 110 of the control device 100 is not limited to one that includes a CPU and ROM and executes software processing. In other words, the processing circuit 110 may have any one of the following configurations (a) to (c): (a) Having one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. Memory, i.e., computer-readable media, includes any available medium that can be accessed by a general-purpose or special-purpose computer. (b) It is equipped with one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASIC or FPGA. ASIC is an abbreviation for "Application Specific Integrated Circuit." FPGA is an abbreviation for "Field Programmable Gate Array." (c) It is equipped with a processor that executes part of the various processes in accordance with a computer program, and a dedicated hardware circuit that executes the remaining part of the various processes.

[0089] <Technical philosophy> The technical ideas that can be understood from the above-described embodiments and modifications will be described. A control method for controlling a vehicle comprising a plurality of wheels, a plurality of vehicle devices configured to be able to adjust the amount of left and right movement of the vehicle, a steering lock mechanism that switches between an operating state that disables rotation of the steering wheel and a non-operating state that allows rotation of the steering wheel, and a steering shaft that is connected to front wheels of the plurality of wheels and operates in response to rotation of the steering wheel to steer the front wheels, wherein one of the plurality of vehicle devices is a front wheel steering device that imparts a steering force to the steering shaft to steer the front wheels, a handle lock process for switching the state of the handle lock mechanism from the inoperative state to the activated state when an abnormality occurs in the front wheel steering device; and an other device control process for adjusting the amount of left and right movement of the vehicle by activating other devices other than the front wheel steering device among the plurality of vehicle devices when the handlebar lock mechanism is in the activated state. [Explanation of symbols]

[0090] 10, 10A...Vehicle 11...Handle 12...Input shaft 13...Output shaft 14...Rudder shaft 16...Front wheel 18...Rear wheel 20...Handle lock mechanism 30...Steering angle adjustment device 40...Front wheel steering device 100...Control device 120...Rear wheel steering device 130...Front-wheel drive 140...Rear wheel drive 150…Front wheel braking device 160…Rear wheel braking device

Claims

1. a steering lock mechanism that switches between an operating state that disables rotation of the steering wheel and a non-operating state that allows rotation of the steering wheel; a steering shaft that is connected to front wheels of the plurality of wheels and operates in response to rotation of the steering wheel to steer the front wheels, wherein the plurality of vehicle devices include a front wheel steering device that imparts a steering force to the steering shaft for turning the front wheels, and a steering angle adjustment device that separates power transmission between the steering wheel and the steering shaft, and adjusts a steering angle ratio that is a ratio of the steering angle of the front wheels to a steering angle that is a rotation angle of the steering wheel by relatively rotating an input shaft that rotates integrally with the steering wheel and an output shaft that rotates in conjunction with the operation of the steering shaft, When the steering wheel lock mechanism is in the activated state, it disables rotation of the steering wheel when the steering angle reaches a preset lock angle, whereas when the steering wheel lock mechanism is in the inactivated state, it allows rotation of the steering wheel even when the steering angle reaches the lock angle, The vehicle control device includes: a handle lock control unit that switches the state of the handle lock mechanism from the inoperative state to the activated state when an abnormality occurs in the front wheel steering device; a request generator that calculates a required steering angle, which is a required value of the steering angle of the front wheels; and an other device control unit that, when the handlebar lock mechanism is in the activated state, operates the steering angle adjustment device to adjust the steering angle ratio so that the steering angle of the front wheels becomes the required steering angle, thereby adjusting the amount of left and right movement of the vehicle. Vehicle control device.

2. a steering lock mechanism that switches between an operating state that disables rotation of the steering wheel and a non-operating state that allows rotation of the steering wheel; a steering shaft that is connected to front wheels of the plurality of wheels and operates in response to rotation of the steering wheel to steer the front wheels; and an execution device, wherein the plurality of vehicle devices include a front wheel steering device that imparts a steering force to the steering shaft to turn the front wheels, and a steering angle adjustment device that separates power transmission between the steering wheel and the steering shaft and adjusts a steering angle ratio that is a ratio of the steering angle of the front wheels to a steering angle that is a rotation angle of the steering wheel by relatively rotating an input shaft that rotates integrally with the steering wheel and an output shaft that rotates in conjunction with the operation of the steering shaft, When the steering wheel lock mechanism is in the activated state, it disables rotation of the steering wheel when the steering angle reaches a preset lock angle, whereas when the steering wheel lock mechanism is in the inactivated state, it allows rotation of the steering wheel even when the steering angle reaches the lock angle, The execution device, a handle lock process for switching the state of the handle lock mechanism from the inoperative state to the activated state when an abnormality occurs in the front wheel steering device; a request generation process for calculating a requested steering angle, which is a requested value of the steering angle of the front wheels; and an other device control process for adjusting the amount of left and right movement of the vehicle by activating the steering angle adjustment device and adjusting the steering angle ratio so that the steering angle of the front wheels becomes the required steering angle when the handlebar lock mechanism is in the activated state.

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