Vehicle control device and vehicle control method

Abstract

A vehicle control device according to the present application sets the size of the tire wear radius of a steered wheel to a first positive value or a first negative value when a turning function of a steer-by-wire system has become abnormal. In addition, a vehicle control method according to the present application changes the size of the tire wear radius of a steered wheel when the turning function of the steer-by-wire system has failed from normal operation. Thus, it is possible to suppress a situation in which the turning performance is reduced due to the specification of the tire wear radius of the steered wheel when the turning function of the steer-by-wire system has become abnormal.

Description

Technical Field

[0001] This invention relates to a vehicle control device and a vehicle control method. Background Technology

[0002] Patent Document 1 discloses a vehicle steering device comprising: a steering knuckle, with an upper support point and a lower support point respectively supported on the vehicle body via suspension components, the upper support point being positioned further inward than the inner side of the wheel in the vehicle width direction; a kingpin changing device having a first degree of freedom to change the kingpin offset and a second degree of freedom to change the kingpin tilt angle, the lower support point being movable between a position further inward than the side and a position further outward; a steering control device for controlling the wheel steering angle based on a target steering angle θ; and a kingpin control device for controlling the kingpin changing device according to the target steering angle θ.

[0003] Prior technology documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-202606

[0006] Invention Summary

[0007] The problem that the invention aims to solve

[0008] However, in vehicles equipped with a steer-by-wire system that mechanically separates the steering input mechanism from the steering wheel and other steering input mechanisms and turns the steering wheels, when the steering function of the steer-by-wire system malfunctions, a yaw moment can be generated between the left and right wheels of the vehicle by creating a difference in braking driving force, thereby enabling the vehicle to turn.

[0009] Furthermore, when a difference in braking driving force is generated between the left and right wheels of the steering wheel, the steering wheel will turn due to the tire wear radius, which is a positioning characteristic. Therefore, if the braking driving force is distributed to the steering wheel to make it turn in the direction of the vehicle's turn, the cornering performance can be improved.

[0010] However, depending on the tire wear radius specifications of the steering wheels, sometimes even if braking force is distributed to the steering wheels, it is not possible to fully obtain the turning effect brought about by the steering wheel turning.

[0011] Therefore, the purpose of this invention is to provide a vehicle control device and a vehicle control method that can suppress the reduction in turning performance caused by the tire wear radius specification of the steering wheel when the steering function of the online steering system malfunctions.

[0012] Methods for solving problems

[0013] Therefore, in one embodiment of the vehicle control device of the present invention, when an abnormal signal of the steering function in the steer-by-wire system is received, the actuator for changing the size of the tire wear radius of the steering wheel is controlled so that the size of the tire wear radius of the steering wheel is set to a first positive value or a first negative value.

[0014] Furthermore, in one embodiment of the vehicle control method of the present invention, when the steering function of the wire steering system fails from normal operation, the wear radius of the steering wheel is changed by controlling the actuator.

[0015] Invention Effects

[0016] According to the present invention, when the steering function of the online steering system malfunctions, it is possible to suppress the reduction in turning performance caused by the tire wear radius specification of the steering wheels. Attached Figure Description

[0017] Figure 1 This is a diagram showing the overall structure of the vehicle control system.

[0018] Figure 2 It is a block diagram schematically showing the control system of various actuators.

[0019] Figure 3 This is a line graph illustrating the correlation between the wear radius of the front tire and the lateral force.

[0020] Figure 4 This is a flowchart illustrating the process of turning control.

[0021] Figure 5 This is a timing diagram showing the start timing of the braking drive force distribution in cornering control.

[0022] Figure 6 This is a diagram illustrating one way in which an active suspension system is structured.

[0023] Figure 7 This diagram illustrates the state of the tire wear radius when using active suspension.

[0024] Figure 8 This is a diagram showing one way an actuator is mounted on a suspension arm. Detailed Implementation

[0025] Hereinafter, embodiments of the vehicle control device and vehicle control method involved in the present invention will be described based on the accompanying drawings.

[0026] Figure 1 This is an overall structural diagram showing the vehicle control system 100 installed in the vehicle 10.

[0027] Figure 2This is a block diagram schematically showing the control system of various actuators in the vehicle control system 100.

[0028] Furthermore, as detailed below, when the steering function of the online steering system 100 malfunctions, the vehicle control system 100 turns the vehicle 10 by distributing braking drive force between the front and rear wheels, and while implementing this braking drive force distribution, it performs control to change the tire wear radius of the front wheel, which serves as the steering wheel.

[0029] The following is for reference Figure 1 and Figure 2 Detailed description of the vehicle control system 100.

[0030] The vehicle 10 equipped with the vehicle control system 100 is a four-wheeled automobile with a pair of front wheels 11 and 12 on the left and right and a pair of rear wheels 13 and 14 on the left and right.

[0031] In addition, the front wheels 11 and 12 are the first wheels that act as steering wheels, and the rear wheels 13 and 14 are the second wheels that are not steering wheels.

[0032] For vehicle 10, the drive device 70 that applies driving force to vehicle 10 is a drive force actuator, which includes a motor 71 that applies driving force to the front wheels 11 and 12 and a motor 72 that applies driving force to the rear wheels 13 and 14.

[0033] The drive force control unit 31 obtains information such as the amount of operation of the accelerator pedal 73 from the accelerator pedal sensor 74.

[0034] Furthermore, the drive force control unit 31 controls the drive force applied to the front wheels 11 and 12 and the rear wheels 13 and 14 by outputting control signals to the motors 71 and 72 that correspond to the target drive force based on the amount of operation of the accelerator pedal 73.

[0035] In addition, the vehicle 10 is equipped with a steer-by-wire system 40 that mechanically separates the steering wheel 51, which serves as the steering input mechanism, from the front wheels 11 and 12, which serve as the steering wheels.

[0036] The steer-by-wire system 40 includes: a reaction force actuator 41 that applies an operating reaction torque to the steering wheel 51; a wheel actuator 42 that applies steering force to the front wheels 11 and 12; and a steering control unit 32 that controls the reaction force actuator 41 and the wheel actuator 42.

[0037] In addition, the steering wheel 51 is equipped with an operation angle sensor 52 that detects the operation angle θ, which is the rotation angle of the steering wheel 51.

[0038] The steering control unit 32 acquires information such as the steering angle θ of the steering wheel 51 detected by the steering angle sensor 52, and calculates the target steering angle and the target reaction torque based on the steering angle θ.

[0039] Then, the steering control unit 32 controls the wheel actuator 42 to make the steering angle of the front wheels 11, 12 the target steering angle, and controls the reaction force actuator 41 to make the target reaction force torque be applied to the steering wheel 51.

[0040] In addition, the vehicle 10 is equipped with a braking device 60 that applies braking force to each wheel 11-14.

[0041] The braking device 60 includes: a braking control unit 33, a brake pedal sensor 62 for detecting the amount of operation of the brake pedal 61, and brake actuators 15, 16, 17, and 18 disposed on each of the wheels 11, 12, 13, and 14.

[0042] Furthermore, the brake control unit 33 controls the braking force applied by the brake actuators 15, 16, 17, and 18 to each wheel 11, 12, 13, and 14 based on the output of the brake pedal sensor 62, etc.

[0043] In addition, vehicle 10 is equipped with a tire wear radius variable device 80.

[0044] The tire wear radius variable device 80 includes: tire wear radius variable actuators 81 and 82 that make the tire wear radius of the front wheels 11 and 12 variable, and a suspension control unit 34 that controls the tire wear radius variable actuators 81 and 82.

[0045] As will be explained in detail below, the variable tire radius actuators 81 and 82 are, for example, actuators mounted on the suspension arms of the vehicle 10, active suspensions provided in the vehicle 10, etc.

[0046] Furthermore, as detailed below, when the suspension control unit 34 receives an abnormal signal of the steering function in the steer-by-wire system 40, it controls the tire wear radius variable actuators 81 and 82 so that the size of the tire wear radius of the front wheels 11 and 12 is set to a predetermined target value (a first positive value or a first negative value).

[0047] In other words, when the steering function of the online steering system 40 fails from normal operation, the suspension control unit 34 controls the tire wear radius variable actuators 81 and 82 to change the size of the tire wear radius of the front wheels 11 and 12.

[0048] When the steering function of the drive force control unit 31 and the brake control unit 33 malfunctions, they implement steering control to make the vehicle 10 turn by distributing the braking drive force to each wheel 11-14.

[0049] Furthermore, in order to stably obtain the turning effect brought about by the steering of the front wheels 11 and 12 in this turning control, the suspension control unit 34 has the function of changing the tire wear radius of the front wheels 11 and 12 from the standard specification value to the target value suitable for turning control.

[0050] The drive force control unit 31, steering control unit 32, braking control unit 33 and suspension control unit 34 are equipped with microcomputers 31A, 32A, 33A and 34A respectively.

[0051] Furthermore, the microcomputers 31A, 32A, 33A, and 34A respectively have an MPU (Microprocessor Unit), ROM (Read Only Memory), and RAM (Random Access Memory), which are not shown in the figure. Various functions are realized by making the program stored in the ROM, which is the storage unit, operate in the MPU.

[0052] In addition, the drive force control unit 31, the steering control unit 32, the brake control unit 33 and the suspension control unit 34 constitute the vehicle control device 30 for controlling the vehicle 10.

[0053] In addition, microcomputers 31A, 32A, 33A, and 34A function as the control unit 30A of the vehicle control device 30.

[0054] The steering control unit 32 and the brake control unit 33, the steering control unit 32 and the drive force control unit 31, and the steering control unit 32 and the suspension control unit 34 are configured to communicate with each other.

[0055] Furthermore, when the brake control unit 33, the drive force control unit 31, and the suspension control unit 34 receive an abnormal signal from the steering control unit 32 regarding the steering function in the steer-by-wire system 40, they replace the steer-by-wire system 40 to perform turning control to change the direction of travel of the vehicle 10.

[0056] That is, the steering control unit 32 has the function of diagnosing whether there is any abnormality in the steering function of the steer-by-wire system 40.

[0057] In addition, the abnormality of the steering function means that the steering of the front wheels 11 and 12, which are steering wheels, cannot be performed, and the steering angle of the front wheels 11 and 12 cannot be controlled to the target steering angle corresponding to the operation angle θ of the steering wheel 51. The reasons are the failure of the wheel actuator 42, the abnormality of the drive circuit of the wheel actuator 42, the failure of various sensors, etc.

[0058] Here, the vehicle control device 30 may have a higher-level control unit, namely the vehicle integrated control unit, which serves as the drive force control unit 31, the steering control unit 32, the braking control unit 33, and the suspension control unit 34.

[0059] Furthermore, the vehicle integrated control unit can also obtain abnormal steering function signals from the steering control unit 32 and output steering control command signals to the brake control unit 33, drive force control unit 31 and suspension control unit 34.

[0060] The following is a detailed explanation of the steering control when the steering function of the steer-by-wire system 40 malfunctions.

[0061] The turning control implemented by the brake control unit 33 and the drive force control unit 31 is: vehicle yaw moment control that causes the vehicle 10 to generate a yaw moment, and steering control that uses positioning characteristics to turn the front wheels 11 and 12.

[0062] The vehicle yaw moment control is achieved by generating a braking driving force difference between the left and right rear wheels 13 and 14, thereby causing the vehicle 10 to generate a yaw moment corresponding to the steering wheel 51 operating angle θ, thus controlling the vehicle 10 to turn in the steering wheel 51 operating direction.

[0063] For example, when making the vehicle 10 turn right, by applying braking force to the right rear wheel 14, a yaw moment can be generated that makes the vehicle 10 turn right.

[0064] In addition, the steering control is achieved by generating a braking driving force difference between the front wheels 11 and 12, and using the positioning characteristics (tire wear radius) to make the front wheels 11 and 12 turn in a direction corresponding to the operating angle θ of the steering wheel 51.

[0065] For example, when making vehicle 10 turn right, if the tire wear radius of the front wheels 11 and 12 is negative, then by applying braking force to the left front wheel 11, the front wheels 11 and 12 can be turned to the right.

[0066] Here, depending on the tire wear radius specifications of the front wheels 11 and 12, sometimes even if braking drive force distribution is implemented in order to turn the front wheels 11 and 12 (for example, applying braking force to one side of the wheels), it is not possible to achieve a full turning effect.

[0067] Therefore, when the steering function of the online steering system 40 malfunctions, the suspension control unit 34 changes the tire wear radius of the front wheels 11 and 12 from the standard specification to a pre-adapted target tire wear radius. This target tire wear radius is the tire wear radius that can achieve sufficient turning effect by distributing the braking driving force to the front wheels 11 and 12.

[0068] Then, the braking control unit 33 and the driving force control unit 31 implement the braking driving force distribution (in other words, steering control) of the front wheels 11 and 12 when the tire wear radius of the front wheels 11 and 12 is changed to the target tire wear radius.

[0069] Figure 3 This is a line graph illustrating the correlation between the wear radius of the front wheels 11 and 12 and the lateral force generated from the front wheels 11 and 12 when the braking drive force distribution of the front wheels 11 and 12 is implemented (in other words, the cornering effect).

[0070] In addition, such as Figure 3 The correlation between the wear radius and lateral force shown varies depending on the wheel track and wheelbase of vehicle 10.

[0071] exist Figure 3 In the middle, the range of tire wear radius where the lateral force is below the threshold is the area where even if the braking drive force distribution of the front wheels 11 and 12 is implemented, the turning effect brought about by the steering of the front wheels 11 and 12 cannot be expected.

[0072] When the tire wear radius of the front wheels 11 and 12 is negative and the vehicle 10 is turning right, in order to turn the front wheels 11 and 12 to the right, for example, apply braking force to the left front wheel 11.

[0073] However, applying braking force to the left front wheel 11 will generate a yaw moment that causes the vehicle 10 to turn to the left.

[0074] Therefore, if the turning effect of steering to the right is small, the turning effect of steering will be canceled out by the yaw moment that makes the vehicle 10 turn in the opposite direction, so the turning effect of steering cannot be expected.

[0075] Therefore, when the target tire radius is set to negative, the size of the target tire radius (more specifically, the absolute value of the distance) needs to be large enough so that the turning effect brought about by the rudder turn exceeds the turning force generated by the yaw moment in the opposite direction.

[0076] On the other hand, when the tire wear radius of the front wheels 11 and 12 is positive and the vehicle 10 is turning to the right, in order to make the front wheels 11 and 12 turn to the right, for example, braking force is applied to the right front wheel 12.

[0077] The braking drive force distribution to turn the front wheels 11 and 12 to the right will also generate a yaw moment that turns the vehicle 10 to the right. Therefore, even if the target tire wear radius is shorter than when the target tire wear radius is set to a negative value, the turning effect brought about by steering can still be obtained when the target tire wear radius is set to a positive value.

[0078] Therefore, the range of tire wear radii below the threshold lateral force largely includes the negative region. Figure 3 In one example, it becomes the range from near zero wear to the specified negative value.

[0079] Furthermore, the target wear radius is set as a first negative or first positive value within the range of wear radii that deviate from the threshold value of the lateral force.

[0080] After such tire wear radius change control is implemented, if the braking drive force distribution of the front wheels 11 and 12 is implemented, regardless of the tire wear radius specification in the vehicle 10, the situation where the yaw moment generated by the braking drive force distribution is suppressed due to the turning effect caused by steering can be suppressed, thereby fully obtaining the turning effect caused by the steering of the front wheels 11 and 12.

[0081] Figure 4 This is a flowchart illustrating the process of steering control (in other words, vehicle control method) when the steering function of the steer-by-wire system 40 malfunctions.

[0082] Furthermore, in the vehicle control system 100, the drive force control unit 31, steering control unit 32, brake control unit 33 and suspension control unit 34 coordinately perform cornering control, but for the sake of simplicity, it will be described in terms of being performed by the control unit 30A of the vehicle control device 30.

[0083] In step S101, the control unit 30A performs a diagnostic of the steering function of the steer-by-wire system 40.

[0084] For example, the control unit 30A can diagnose the steering function based on the change in the absolute value of the deviation between the target steering angle and the actual steering angle. When the absolute value of the deviation is greater than or equal to a threshold for a specified time, it can diagnose the occurrence of an abnormality in the steering function.

[0085] Next, in step S102, the control unit 30A determines whether an abnormality in the steering function is diagnosed based on the result of diagnosing the steering function of the steer-by-wire system 40.

[0086] Here, when the control unit 30A diagnoses that the steer-by-wire system 40 is normal and can control the steering angle of the front wheels 11 and 12 to the target steering angle, it proceeds to step S103.

[0087] In step S103, the control unit 30A calculates the target steering angle (in other words, the target tire angle) of the front wheels 11 and 12, which are steering wheels, based on the operating angle θ of the steering wheel 51.

[0088] Then, the control unit 30A controls the wheel actuators 42 of the steer-by-wire system 40 based on the target steering angle, and turns the front wheels 11 and 12 to the target steering angle.

[0089] On the other hand, when the steer-by-wire system 40 malfunctions and is unable to control the steering angle of the front wheels 11 and 12 to the target steering angle, the control unit 30A advances from step S102 to step S105 and thereafter, replacing the steer-by-wire system 40 to implement turning control by distributing braking driving force to the wheels 11-14 to change the direction of travel of the vehicle 10.

[0090] In addition, in cornering control based on brake drive force distribution, the control unit 30A implements control to change the tire wear radius of the front wheels 11 and 12 as needed.

[0091] That is, when the microcomputer 34A of the steering control unit 32 detects an abnormality in the steering function of the steer-by-wire system 40, it outputs an abnormal signal to the brake control unit 33, the drive force control unit 31 and the suspension control unit 34, and instructs to implement turning control.

[0092] Then, the brake control unit 33 and the drive force control unit 31 implement the distribution of braking drive force, and the suspension control unit 34 implements the change of the tire wear radius of the front wheels 11 and 12.

[0093] In step S105, the control unit 30A determines whether the standard specifications of the tire wear radius of the front wheels 11 and 12 are included in the specified range set as a range where the turning effect cannot be expected from steering.

[0094] Furthermore, when the standard tire wear radius of current wheels 11 and 12 is within a range where turning effect from steering cannot be expected, the control unit 30A determines that it needs to be changed to a target tire wear radius that deviates from this range (refer to...). Figure 3 ).

[0095] In other words, the control unit 30A controls the tire radius variable actuators 81 and 82 to change the tire radius of the front wheels 11 and 12 from the standard specification only when the tire radius of the front wheels 11 and 12 is less than the specified value.

[0096] When the control unit 30A needs to change the tire wear radius of the front wheels 11 and 12, that is, when the standard specifications of the tire wear radius of the front wheels 11 and 12 are within the range where the turning effect brought about by steering cannot be expected, it proceeds to step S106 and thereafter.

[0097] On the other hand, if the tire wear radius of the front wheels 11 and 12 does not need to be changed, that is, when the standard specifications of the tire wear radius of the front wheels 11 and 12 are not within the range where the turning effect brought about by steering cannot be expected, the control unit 30A skips steps S106-S109 and proceeds to step S110 to cancel the tire wear radius change process.

[0098] In step S106, the control unit 30A calculates the braking drive force command of the rear wheels 13 and 14 based on the driver's operation amount, specifically based on the acceleration operation amount, braking operation amount, and the steering wheel 51 operation angle θ.

[0099] That is, in step S106, the control unit 30A, in response to the driver's acceleration or deceleration request, determines the braking drive force distribution of the rear wheels 13 and 14 to generate a yaw moment in the vehicle 10 corresponding to the steering wheel 51 operating angle θ.

[0100] Next, in step S107, the control unit 30A controls the tire wear radius variable actuators 81 and 82 to change the tire wear radius of the front wheels 11 and 12 from the standard specification to the target tire wear radius in the turning control when the steer-by-wire system 40 fails (specifically, a first positive value or a first negative value).

[0101] Furthermore, the target grinding radius can be pre-fixed to either a first positive value or a first negative value.

[0102] In addition, the control unit 30A can select either a first positive value or a first negative value based on the standard specifications of the tire wear radius of the front wheels 11 and 12 (or the tire wear radius of the front wheels 11 and 12 when the steering function malfunctions), the variable range of the tire wear radius realized by the tire wear radius variable actuators 81 and 82, etc.

[0103] In step S108, the control unit 30A controls the braking force applied to the rear wheels 13 and 14 respectively based on the braking driving force command calculated in step S106, thereby generating a braking driving force difference between the left and right wheels of the rear wheels 13 and 14, causing the vehicle 10 to generate a yaw moment.

[0104] That is, in step S108, the control unit 30A turns the vehicle 10 by controlling the braking driving force of the wheels other than the steering wheels (front wheels 11, 12), namely the rear wheels 13, 14.

[0105] In step S109, the control unit 30A determines whether the change control of the tire wear radius of the front wheels 11 and 12 has been completed, that is, whether the tire wear radius of the front wheels 11 and 12 has been changed to the target tire wear radius, or whether the tire wear radius of the front wheels 11 and 12 is in a transitional state towards the target tire wear radius.

[0106] Here, before the tire wear radius of the front wheels 11 and 12 has reached the target tire wear radius, the control unit 30A returns to step S108 and turns the vehicle 10 by controlling the braking drive force of the rear wheels 13 and 14.

[0107] On the other hand, when the wear radius of the front wheels 11 and 12 reaches the target wear radius, the control unit 30A proceeds from step S109 to step S110, and similarly to step S106, calculates the braking drive force command of the rear wheels 13 and 14 based on the driver's operation amount.

[0108] Next, the control unit 30A proceeds to step S111, and based on the braking driving force command of the rear wheels 13 and 14 obtained in step S110, controls the braking driving force applied to the rear wheels 13 and 14. In order to turn the front wheels 11 and 12 to a turning direction corresponding to the operation angle θ of the steering wheel 51, the control unit controls the braking driving force applied to the front wheels 11 and 12 to generate a braking driving force difference between the front wheels 11 and 12.

[0109] That is, when a change in the tire wear radius of the front wheels 11 and 12 is requested, the control unit 30A performs cornering control (in other words, vehicle yaw moment control) based on the brake drive force distribution of the rear wheels 13 and 14 until the tire wear radius of the front wheels 11 and 12 is set to the target tire wear radius, and performs cornering control based on the brake drive force distribution of the front wheels 11 and 12 after the change in tire wear radius is completed and set to the target tire wear radius.

[0110] On the other hand, if there is no need to change the tire wear radius of the front wheels 11 and 12 and the process proceeds from step S102 to step S110, the control unit 30A starts turning control based on the braking drive force distribution of the rear wheels 13 and 14 and turning control based on the braking drive force distribution of the front wheels 11 and 12 in parallel.

[0111] Figure 5 This is a timing diagram showing the different start timings of the brake drive force distribution in cornering control when the tire wear radius of the front wheels 11 and 12 is changed.

[0112] exist Figure 5 At time t1, when the steering function of the steer-by-wire system 40 fails from normal operation, the abnormality flag of the steering function rises.

[0113] Furthermore, based on the rise of the abnormal indicator of the steering function, the tire wear radius of the front wheels 11 and 12 is changed to the target tire wear radius in the turning control, and the tire wear radius of the front wheels 11 and 12 changes from the standard specification to the target tire wear radius.

[0114] In addition, when the abnormal indicator of the steering function rises, the braking drive force control begins to generate a yaw moment in the vehicle 10 by using the difference in braking drive force between the left and right wheels of the rear wheels 13 and 14, so that the vehicle 10 turns in the direction of the driver's intended turn.

[0115] For example, when the vehicle 10 is turning right, braking force is applied to the right rear wheel 14, resulting in a yaw rate in the right turning direction.

[0116] Then, at time t2, when the yaw moment is generated by the braking drive force distribution of the rear wheels 13 and 14, when the tire wear radius of the front wheels 11 and 12 reaches the target tire wear radius, the braking drive force distribution with the difference in braking drive force between the left and right wheels of the front wheels 11 and 12 begins, and the front wheels 11 and 12 turn the rudder in the turning direction.

[0117] For example, when the vehicle 10 turns right and the target tire wear radius is set to a first negative value, the front wheels 11 and 12 are turned to the right by applying braking force to the left front wheel 11.

[0118] As described above, by starting the braking drive force control of the front wheels 11 and 12 after the tire wear radius of the front wheels 11 and 12 reaches the target tire wear radius, the turning effect brought about by steering can be stably exerted.

[0119] In addition, the control unit 30A can also start braking drive force control of the front wheels 11 and 12 when the wear radius of the front wheels 11 and 12 approaches the target wear radius to a certain extent (in other words, when the wear radius reaches the intermediate value between the standard specification and the target wear radius).

[0120] The following details the variable grinding radius actuators 81 and 82.

[0121] Figure 6 This is a front view of one configuration of the active suspension structure for the variable tire radius actuators 81 and 82.

[0122] The front wheels 11 and 12 have tires 91 on the outer periphery and wheels 92 in the center.

[0123] Furthermore, wheel 92 is mounted on hub 93, and brake disc 94 constituting braking device 60 is mounted on hub 93.

[0124] The wheel hub 93 is mounted on the vehicle body 10A via the upper arm 95 and the lower arm 96, and an active suspension 97 is provided between the upper arm 95 and the vehicle body 10A.

[0125] The active suspension 97 is a mechanism that can arbitrarily change the vehicle height 10.

[0126] Figure 7 Show Figure 6 The tire wear radius of the front wheels 11 and 12 shown has been changed from the standard specification state to the target tire wear radius state due to an abnormality in the steering function.

[0127] When changing the tire wear radius, the active suspension 97 is used to travel, causing the vehicle body 10A to tilt. This causes the upper arm 95 and lower arm 96 connected to the vehicle body 10A to tilt, resulting in the front wheels 11 and 12 having an outward camber angle, and thus the tire wear radius of the front wheels 11 and 12 changes.

[0128] That is, when the vehicle 10 is equipped with an active suspension 97, the control unit 30A can change the tire wear radius of the front wheels 11 and 12 to the target tire wear radius by controlling the travel of the active suspension 97.

[0129] Figure 8 This is a diagram of one method of mounting actuators 81 and 82 on the suspension arm as variable tire radius actuators.

[0130] The front wheels 11 and 12 have tires 91 on the outer periphery and wheels 92 in the center.

[0131] Furthermore, wheel 92 is mounted on hub 93, and brake disc 94 constituting braking device 60 is mounted on hub 93.

[0132] The wheel hub 93 is supported by the upper arm 95 and the lower arm 96, and a shock absorber 98 is installed between the lower arm 96 and the body 10A.

[0133] In addition, the steering knuckle 99 has an upper support point moving device 99A and a lower support point moving device 99B, and is provided with actuators 100A and 100B that act on the upper support point moving device 99A and the lower support point moving device 99B to move the position of the steering knuckle 99.

[0134] Here, the control unit 30A changes the kingpin position by controlling the actuators 100A and 100B. Figure 8 (As shown by the dashed line), it can change the tire grinding radius to the target tire grinding radius.

[0135] The technical concepts described in the above embodiments can be appropriately combined and used within the scope of not causing contradictions.

[0136] Furthermore, while the present invention has been specifically described with reference to preferred embodiments, it is self-evident that those skilled in the art can employ various modifications based on the basic technical ideas and teachings of the present invention.

[0137] For example, a vehicle can also be one in which the first wheel, which is turned by a steer-by-wire system and serves as the steering wheel, is designated as the rear wheel, and the second wheel, other than the steering wheel, is designated as the front wheel.

[0138] Furthermore, the steering control based on the distribution of braking force to the front and rear wheels is not limited to implementation in the manual driving mode performed by the driver, but can also be applied to the steering function of the steer-by-wire system in the automatic driving mode when it malfunctions.

[0139] In addition, the target value of the tire wear radius of the steering wheel can be changed according to the driving state of the vehicle 10 when the steering function of the steer-by-wire system malfunctions, the unevenness of the road surface on which the vehicle 10 is traveling, and other driving conditions. Specifically, the first negative value or the first positive value can be specified.

[0140] In addition, the steering input mechanism in a steer-by-wire system is not limited to a steering wheel; it can also be a stick, joystick, or other similar device.

[0141] Explanation of reference numerals in the attached figures

[0142] 10...vehicle, 11, 12...front wheel (steering wheel, first wheel), 13, 14...rear wheel (second wheel other than the steering wheel), 30...vehicle control unit, 30A...control unit, 40...steer-by-wire system, 60...braking device, 70...drive device, 81, 82...variable tire radius actuator (actuator).

Claims

1. A vehicle control device disposed in a vehicle, the vehicle comprising: a steer-by-wire system that, when a steering wheel of the vehicle is used as a first wheel, causes the first wheel, which is mechanically separated from a steering input mechanism, to turn; and an actuator that, by being controlled, changes the size of the tire wear radius of the first wheel. When the control unit of the vehicle control device receives an abnormal signal of the steering function in the steer-by-wire system, it controls the actuator to set the wear radius of the first wheel to a first positive value or a first negative value.

2. The vehicle control device according to claim 1, wherein, After the wear radius of the first wheel is set to the first positive value or the first negative value, the control unit applies a braking driving force to the first wheel and performs steering control of the first wheel.

3. The vehicle control device according to claim 2, wherein, When the wheels other than the steering wheels are used as the second wheels... The control unit performs vehicle yaw moment control by applying braking driving force to the second wheel and causing the vehicle to generate yaw moment during the period before the size of the wear radius of the first wheel is set to the first positive value or the first negative value.

4. The vehicle control device according to claim 1, wherein, The control unit controls the actuator only when it receives an abnormal signal from the steering function of the steer-by-wire system, provided that the wear radius of the first wheel is less than a specified value.

5. The vehicle control device according to claim 1, wherein, The actuator is an actuator mounted on the suspension arm of the vehicle.

6. The vehicle control device according to claim 1, wherein, The actuator is an active suspension mounted on the vehicle.

7. A vehicle control method, executed by a control unit disposed in a vehicle, the vehicle comprising: a steer-by-wire system for turning steering wheels mechanically separated from a steering operation input mechanism; and an actuator for controlling the change in the tire wear radius of the steering wheels. When the steering function of the steer-by-wire system fails from normal operation, the wear radius of the steering wheel is changed by controlling the actuator.

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