Controller for vehicles

Abstract

To provide a controller for vehicles capable of reducing an adverse effect of disturbance on motions of wheels in a situation where the motions of the wheels may vary due to the disturbance.SOLUTION: A controller 10 for vehicles is adapted to a vehicle 1 including a turning motor 526 that controls turning motions of wheels 3, that is, a right front wheel 31 and a left front wheel 32. The controller 10 for vehicles includes: an acquisition unit 111 that acquires travel environment information Je representing a travel environment of the vehicle 1; a situation determination unit 112 that determines, based on the travel environment information Je representing the travel environment, whether a predetermined situation has arisen in which a disturbance acts on the right front wheel 31 and the left front wheel 32 so as to vary the turning motions; and an inhibition unit 113 that, when the predetermined situation has arisen, suppresses restriction of protection control for protecting the turning motor 526 by regulating a turning current I which is supplied to the turning motor 526.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a vehicle control device.

Background Art

[0002] Conventionally, for example, a steering system disclosed in Patent Document 1 (hereinafter referred to as the "conventional device") is known. The conventional device includes an electric motor that steers the steered wheels of a vehicle to control the steering operation, and as protection control for the electric motor, it prohibits the supply of current exceeding the upper limit value to the electric motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, vehicles have been equipped with electric motors that control the driving state (rotating state), braking state (stopping state), and steering state, which are wheel operations, using electric motors like the conventional device. When operating the mounted electric motor to control the wheel operation, in a situation where the temperature of the electric motor, drive circuit, etc. rises as the electric motor operates, similar to the conventional device, protection control for limiting the current supplied to the electric motor may be executed from the perspective of protecting the system from overheating.

[0005] By the way, in a situation where a vehicle is traveling in a driving environment where there are obstacles that can disturb the wheels, it is necessary to control the operation of the wheels against the disturbance applied from the obstacles to drive, stop, or steer the steered wheels of the vehicle. In these cases, generally, the electric motor needs to generate a greater force (torque) compared to the normal case of traveling in a driving environment where there are no obstacles. For this reason, a larger current is supplied to the electric motor, the drive circuit, etc. compared to the normal case. And in a situation where a large current is supplied, since the electric motor, the drive circuit, etc. are likely to overheat, there is a high possibility that protection control will generally intervene.

[0006] However, when the protection control is executed, since the current supplied to the electric motor is restricted, there is a possibility that the necessary force (torque) cannot be obtained with the force (torque) generated by the electric motor. In this case, even if the operation of the wheels is controlled using the electric motor, there is a possibility that the force (torque) generated by the electric motor cannot withstand the disturbance. As a result, there is a possibility that the operation of the wheels will change due to the disturbance, and there is a risk of affecting the driving of the vehicle.

[0007] An object of the present disclosure is to provide a vehicle control device capable of reducing the influence of a disturbance on the operation of wheels in a situation where the operation of the wheels can be changed by the disturbance.

Means for Solving the Problems

[0008] The vehicle control device of the present disclosure is a vehicle control device applied to a vehicle including an electric motor that controls the operation of wheels, and includes an acquisition unit that acquires driving environment information representing the driving environment of the vehicle, a situation determination unit that determines whether or not a predetermined situation has occurred in which a disturbance acts on the wheels so as to cause a change in the operation based on the driving environment information, and a suppression unit that suppresses the limitation of protection control for protecting the electric motor by restricting the current supplied to the electric motor when the predetermined situation has occurred.

Effects of the Invention

[0009] According to the present disclosure, when the vehicle is in a predetermined situation where a disturbance that causes a change in the operation of the wheels acts, the suppression unit can suppress the limitation of the protection control for protecting the electric motor. Thereby, when the vehicle is in a predetermined situation, a current with the limitation suppressed can be supplied to the electric motor, and the electric motor can generate a force (torque) so as to resist the disturbance acting on the wheels. Therefore, in a predetermined situation, the influence of the disturbance on the operation of the wheels can be reduced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] Hereinafter, a vehicle control device 10 which is an embodiment of the present disclosure will be described in detail with reference to the drawings. It should be noted that the present disclosure can be implemented in various forms with various changes and improvements based on the knowledge of those skilled in the art in addition to the embodiments described below.

[0012] A. First Embodiment (1. Configuration of Vehicle 1 to Which Vehicle Control Device 10 is Applied) In the first embodiment, the vehicle control device 10 is applied to the vehicle 1 shown in FIG. 1. The vehicle 1 includes a vehicle body 2, wheels 3 arranged respectively on the front, rear, left, and right, and a suspension unit 4 that supports the vehicle body 2 and each wheel 3. The wheels 3 are composed of a right front wheel 31, a left front wheel 32, a right rear wheel 33, and a left rear wheel 34. The suspension unit 4 is an independent suspension type arranged corresponding to each of the wheels 3, and has, for example, a coil spring 41 and a hydraulic shock absorber 42. Incidentally, the suspension unit 4 may be, for example, an air suspension unit equipped with an air spring.

[0013] Furthermore, the vehicle 1 includes, for example, a steering system 5 for steering the right front wheel 31 and the left front wheel 32 as steered wheels. Here, in the first embodiment, a case where the control target by the vehicle control device 10 is the steering system 5 is exemplified. The steering system 5 includes, as an operation of the wheels, an electric motor (mainly, a steering motor 526 described later) that controls the steering operation in which the right front wheel 31 and the left front wheel 32 are steered, and is of a steer-by-wire type equipped with a mechanically independent operation device 51 and a steering device 52.

[0014] The operation device 51 mainly includes a steering wheel 511, a steering shaft 512, a steering column 513, and a reaction force applying mechanism 514. The steering wheel 511 is an operation member steered (steering operation) by the driver. The steering shaft 512 has the steering wheel 511 attached to its tip and is rotatably held by the steering column 513. The steering column 513 is supported by an instrument panel reinforcement (not shown).

[0015] The reaction force applying mechanism 514 uses the reaction force motor 515 as a driving force source to apply a reaction force Fc (strictly speaking, "reaction torque", but hereinafter referred to as the commonly used "operating reaction force Fc") to the steering wheel 511 via the steering shaft 512. The reaction force motor 515 can be exemplified by, for example, a three-phase brushless DC motor. Here, the reaction force motor 515 independently has a motor rotation angle sensor 516 that detects the motor rotation angle ω within one rotation for switching the energized phase in the power supply to itself. Since the reaction force applying mechanism 514 has a general structure including a speed reducer and the like, the description of the specific structure is omitted.

[0016] Also, the operating device 51 has an operating angle sensor 517 that detects the operating angle δ of the steering wheel 511 as a steering operation amount. Here, when the position taken by the steering wheel 511 in the straight-ahead state of the vehicle 1 is defined as the neutral position, the rotation angles in the left and right directions from the neutral position are the operating angle δ of the steering wheel 511.

[0017] Also, the operating device 51 has a torsion bar 518 incorporated in the steering shaft 512, similar to a so-called general power steering system. And the operating device 51 has an operating torque sensor 519 that detects the operating torque To as the operating force applied to the steering wheel 511 by the driver based on the amount of twist of the torsion bar 518.

[0018] The steering device 52 integrally steers each of the right front wheel 31 and the left front wheel 32 supported by the vehicle body 2 so as to be steerable by rotating the steering knuckle 43 that constitutes the suspension unit 4. That is, the steering operation of the right front wheel 31 and the left front wheel 32 is mainly controlled by the steering device 52. The steering device 52 has a steering actuator 521 as a main component.

[0019] The steering actuator 521 mainly includes a steering rod 522, a housing 523, and a rod movement mechanism 524. The two ends of the steering rod 522 are respectively connected to the left and right steering knuckles 43 via ring rods 525. Incidentally, the steering rod 522 may also be referred to as a "rack bar". The housing 523 is fixed to the vehicle body and supports the steering rod 522 so as to be movable in the left - right direction.

[0020] The rod movement mechanism 524 uses a steering motor 526, which is an electric motor, as a drive source to move the steering rod 522 in the left - right direction. For example, the rod movement mechanism 524 mainly includes a ball screw mechanism composed of a ball groove (not shown) provided on the steering rod 522 and a nut (not shown) that is screwed through the ball groove and bearing balls (not shown) and is rotated by the steering motor 526.

[0021] Since the ball screw mechanism has a general structure, the description of the specific structure of the rod movement mechanism 524 is omitted. Also, regarding the structure of the rod movement mechanism 524, it is not limited to the ball screw mechanism, and other mechanisms can also be used.

[0022] Here, similar to the reaction force motor 515, the steering motor 526 can be exemplified by, for example, a three - phase brushless DC motor. And the steering motor 526 also independently has a motor rotation angle sensor 527 for detecting the motor rotation angle ν within one rotation for switching the energized phase in the power supply to itself. Also, the steering motor 526 independently has a current sensor 528 for detecting the current I actually supplied to itself (hereinafter, sometimes referred to as the "steering current I").

[0023] Further, the steering device 52 has a steering angle sensor 529 that detects the steering angle θ of the right front wheel 31 and the left front wheel 32, which are steering wheels. Here, when the position of the steering rod 522 in the straight-ahead state of the vehicle 1 is set as the neutral position, the amount of movement (absolute amount) in each of the left and right directions from the neutral position is the steering angle θ of the right front wheel 31 and the left front wheel 32.

[0024] The control of the operating device 51, more specifically, the control of the operating reaction force Fc, that is, the control of the reaction force motor 515 of the operating device 51, is executed by an operation electronic control unit 53 (hereinafter, may be simply referred to as "operation ECU53"). The operation ECU53 is composed of a microcomputer equipped with a CPU, ROM, RAM, and various interfaces, an inverter that is a driver (drive circuit) of the reaction force motor 515, and the like. In FIG. 1 (FIG. 6 described later), the operation ECU53 is shown as "O-ECU53".

[0025] The control of the steering device 52, more specifically, the control of the steering angle θ, that is, the control of the steering motor 526 of the steering device 52, is executed by a steering electronic control unit 54 (hereinafter, may be referred to as "steering ECU54"). The steering ECU54 is composed of a microcomputer equipped with a CPU, ROM, RAM, and various interfaces, an inverter that is a driver (drive circuit) of the steering motor 526, and the like. In FIG. 1, the steering ECU54 is shown as "S-ECU54".

[0026] The CPU reads data, performs numerical calculations, outputs calculation results, etc. by sequentially executing a predetermined program. The ROM stores programs, maps, etc. executed by the CPU. The RAM temporarily stores data, etc. The various interfaces are connected to a motor rotation angle sensor 516, an operation angle sensor 517, an operation torque sensor 519, etc. in the operation ECU53, and are connected to a motor rotation angle sensor 527, a current sensor 528, a steering angle sensor 529, etc. in the steering ECU54.

[0027] Here, the operation ECU 53 and the steering ECU 54 are connected to the communication line C via various interfaces so that they can communicate with each other. As the communication line C, for example, CAN (Car Area Network or Controllable Area Network) or a dedicated communication line other than CAN can be exemplified.

[0028] The steering force generated by the steering actuator 521 of the steering device 52 to steer the wheels 3 (specifically, the right front wheel 31 and the left front wheel 32) may be a relatively large force in a driving environment where there are obstacles or when driving on an uneven road as described later. That is, a relatively large steering current I may be supplied to the steering motor 526 of the steering actuator 521.

[0029] Therefore, from the viewpoint of protecting the system from overheating, the steering system 5 has a temperature sensor 55 for detecting the motor temperature Tm, which is the temperature of the steering motor 526. Also, from the viewpoint of protecting the system from overheating, the steering system 5 has a temperature sensor 56 for detecting the board temperature Tk, which is the temperature of the board of the drive circuit included in the steering ECU 54. Furthermore, the steering system 5 has a temperature sensor 57 for detecting the ambient temperature Te, which is the temperature of the surrounding environment. The motor temperature Tm detected by the temperature sensor 55, the board temperature Tk detected by the temperature sensor 56, and the ambient temperature Te detected by the temperature sensor 57 are output to the steering ECU 54 via various interfaces.

[0030] Here, regarding the control of the steering system 5, the steering control, which is the control of the steering device 52, and the reaction force control, which is the control of the reaction force applying mechanism 514 of the operation device 51, will be described.

[0031] The steering control is a control for steering the right front wheel 31 and the left front wheel 32 in response to a steering request, that is, in response to the operation angle δ of the steering wheel 511 in the case of manual driving by the driver. The steering control is executed by the steering ECU 54. Hereinafter, normal control during normal times and protection control for protecting the system from overheating of the steering motor 526 will be described.

[0032] In the steering system 5, the motor rotation angle ω of the reaction force motor 515 of the operating device 51 and the operation angle δ of the steering wheel 511 are in a relationship with a predetermined gear ratio. For this reason, the operation ECU 53 acquires the operation angle δ based on the motor rotation angle ω detected by the motor rotation angle sensor 516. Then, the steering ECU 54 acquires the information of the operation angle δ from the operation ECU 53, and multiplies the acquired operation angle δ by the set steering gear ratio Rg according to the following formula (1) to determine the target steering angle θd which is the target of the steering angles θ of the right front wheel 31 and the left front wheel 32. θd = Rg × δ … Formula (1)

[0033] In the steering system 5, the control of the steering angles θ of the right front wheel 31 and the left front wheel 32 is performed using the motor rotation angle ν instead of the steering angle θ. For this reason, the steering ECU 54 determines the target motor rotation angle νd which is the target of the motor rotation angle ν of the steering motor 526 based on the target steering angle θd determined according to the formula (1). Then, the steering ECU 54 detects the actual motor rotation angle ν of the steering motor 526 via the motor rotation angle sensor 527, and determines the motor rotation angle deviation Δν which is the deviation of the motor rotation angle ν with respect to the target motor rotation angle νd according to the following formula (2). Δν = νd - ν … Formula (2)

[0034] Here, in the steering system 5, the steering ECU 54 determines the torque Ts (hereinafter referred to as "steering torque Ts") that the steering motor 526 should generate according to the feedback control law based on the motor rotation angle deviation Δν. That is, the steering ECU 54 determines the steering torque Ts according to the following formula (3). Ts = Gp × Δν + Gi × ∫Δνdt + Gd × dΔν / dt … Equation (3) However, in the above Equation (3), the first term is the proportional term, the second term is the integral term, and the third term is the derivative term. Also, in the above Equation (3), Gp represents the proportional term gain, Gi represents the integral term gain, and Gd represents the derivative term gain.

[0035] In the steering control, the steering ECU 54 supplies a steering current I corresponding to the steering torque Ts determined according to the above Equation (3) to the steering motor 526. Here, the steering current I is generally in a proportional relationship with the steering torque Ts. Therefore, the steering ECU 54 determines, for example, according to the proportional relationship, the steering current I to be supplied to the steering motor 526 based on the determined steering torque Ts. Then, the steering ECU 54 operates the steering motor 526 by supplying the steering current I to the steering motor 526 via an inverter (not shown), for example, and steers the wheels 3, that is, the right front wheel 31 and the left front wheel 32 until the target steering angle θd is reached.

[0036] In the steering system 5, when a large steering current I is supplied to the steering motor 526 of the steering device 52 for a long time, the steering motor 526 and the drive circuit (driver, for example, an inverter) of the steering motor 526 may overheat. For protection against such overheating, usually, the steering system 5, particularly the steering device 52, is provided with a limit on the steering current I. More specifically, the steering ECU 54 sets an upper limit value Ijs for the steering current I supplied to the steering motor 526 according to the driving environment of the vehicle 1, and in principle prohibits supplying a steering current I exceeding the upper limit value Ijs. That is, when the steering current I determined according to the steering torque Ts calculated according to the above Equation (3) as described above exceeds the upper limit value Ijs, the steering ECU 54 executes a protection control to limit the supplied steering current I to be equal to or less than the upper limit value Ijs.

[0037] However, as described later, when the vehicle 1 travels in a predetermined situation, the steering ECU 54 suppresses the restriction so as not to temporarily execute the protection control until the vehicle 1 exits the predetermined situation, or executes it while suppressing the restriction on the decrease amount of the steering current I by the temporary protection control. Here, the upper limit value Ijs is, as a predetermined situation described later, for example, a situation where a disturbance (load) that acts to change the operation of the wheel 3 from obstacles such as rocks existing on the road surface with respect to the wheel 3 is large, and it is necessary to maintain the operation of the wheel 3 against this disturbance. That is, it is set assuming a situation where the steering torque Ts, that is, the steering current I, is larger than the situation where the vehicle 1 normally travels. Therefore, it can be determined that the vehicle 1 is in a predetermined situation when the steering current I is larger than the upper limit value Ijs.

[0038] The reaction force control is a control for applying an operation reaction force Fc to the steering wheel 511 in order to give the driver a feeling of operation for the steering operation. The reaction force control is executed by the operation ECU 53. Specifically, the operation ECU 53 determines the operation reaction force Fc according to the following formula (4) using the steering load-dependent component Fs, which is one of the two components, and the operation force-dependent reduction component Fa. Fc = Fs - Fa … Formula (4)

[0039] Here, the steering load-dependent component Fs in the formula (4) is a component related to the steering force (the steering torque Ts of the steering motor 526) required to steer the right front wheel 31 and the left front wheel 32, and is determined based on the steering current I supplied to the steering motor 526. Although detailed description is omitted, it is recognized that the larger the steering current I, the larger the steering load of the right front wheel 31 and the left front wheel 32, and the steering load-dependent component Fs is determined to be a large value. Note that information regarding the steering current I actually supplied to the steering motor 526 is supplied from the steering ECU 54 to the operation ECU 53 via the communication line C.

[0040] Further, the operation force-dependent reduction component Fa in the formula (4) is, for example, a component for giving the driver the operating feeling in a conventional power steering system. In a conventional power steering system, generally, an assist torque corresponding to the operation torque To is generated by, for example, an electric motor and applied to the steering shaft 512.

[0041] Therefore, the operation force-dependent reduction component Fa is determined according to the following formula (5) so as to reproduce the assist torque. And the operation ECU 53 acquires the operation torque To via the operation torque sensor 519. Fa = β × To … Formula (5) However, β in the formula (5) represents a gain for determining the operation force-dependent reduction component Fa.

[0042] The operation ECU 53 determines a reaction force current Ic, which is a current supplied to the reaction force motor 515, according to the following formula (6) based on the operation reaction force Fc determined according to the formula (4). And the operation ECU 53 supplies the determined reaction force current Ic to the reaction force motor 515. Ic = α × Fc … Formula (6) However, α in the formula (6) represents a preset power determination coefficient.

[0043] Returning again to the description of the configuration of the vehicle 1, the vehicle 1 of the first embodiment includes an engine 6, a transmission 7, and a differential device 8 in order to transmit driving force, more specifically, driving torque, to each of the wheels 3. Incidentally, in the vehicle 1 of the first embodiment, the differential device 8 is composed of a center differential 81, a front differential 82, and a rear differential 83.

[0044] The engine 6 is the driving power source of the vehicle 1. The control of the engine 6 is executed by an engine electronic control unit (not shown). The driving torque generated by the engine 6 is transmitted to the transmission 7. The control of the transmission 7 is executed by a transmission electronic control unit (not shown). The input shaft of the transmission 7 is connected to the engine 6. The output shaft of the transmission 7 is connected to the center differential 81 that constitutes the differential device 8. Thereby, the driving torque is distributed from the output shaft of the transmission 7 to each wheel 3.

[0045] Specifically, the right front wheel 31 and the left front wheel 32 are distributed with driving torque from the transmission 7 via the center differential 81 and the front differential 82. Also, the right rear wheel 33 and the left rear wheel 34 are distributed with driving torque from the transmission 7 via the center differential 81 and the rear differential 83. That is, the vehicle 1 of the first embodiment is a four-wheel drive vehicle in which the right front wheel 31, the left front wheel 32, the right rear wheel 33, and the left rear wheel 34 can be driving wheels.

[0046] Here, the vehicle 1 of the first embodiment includes a transfer switch 84 disposed in the vehicle interior. Thereby, the driver can switch between the "HI range" during normal driving and the "LOW range" during driving on rough roads. In the vehicle 1, for example, the center differential 81 functions as a transfer for the "HI range" or the "LOW range". And when the transfer switch 84 is switched to the LOW range, it outputs a range signal LS to the vehicle control device 10.

[0047] The front differential 82 can absorb the difference in rotational speed between each of the right front wheel 31 and the left front wheel 32. The rear differential 83 can absorb the difference in rotational speed between each of the right rear wheel 33 and the left rear wheel 34. And the center differential 81 can absorb the difference in rotational speed between the right front wheel 31 and the left front wheel 32 and the right rear wheel 33 and the left rear wheel 34.

[0048] And the vehicle 1 of the first embodiment includes a differential lock switch 85 disposed in the vehicle interior. Thereby, when the vehicle 1 travels on an uneven road with obstacles, i.e., during so-called off-road driving, for example, the driver can switch the center differential 81, the front differential 82, and the rear differential 83 to a differential lock state that does not absorb the difference in rotational speed as needed. And when the differential lock switch 85 is switched to the differential lock state, it is configured to output a differential lock signal DS to the vehicle control device 10.

[0049] Furthermore, the vehicle 1 includes a brake system 9 for generating braking force for each of the wheels 3. The brake system 9 of the first embodiment includes a right front wheel brake 91, a left front wheel brake 92, a right rear wheel brake 93, a left rear wheel brake 94, a hydraulic pressure booster 95, and brake pipes 96.

[0050] Each of the right front wheel brake 91, the left front wheel brake 92, the right rear wheel brake 93, and the left rear wheel brake 94 includes, although not shown, a brake disk that rotates integrally with the wheel 3, a pair of brake pads that press the brake disk from both sides, and a brake caliper to which the brake pads are fixed. The hydraulic pressure booster 95 is connected to the brake caliper via the brake pipe 96, and a hydraulic circuit for hydraulic oil is formed between each of the right front wheel brake 91, the left front wheel brake 92, the right rear wheel brake 93, and the left rear wheel brake 94 and the hydraulic pressure booster 95. Thereby, in the wheel brake system 9 of the first embodiment, when the hydraulic pressure booster 95 pressurizes the hydraulic oil, the brake pads press the brake disk, and as a result, frictional force, i.e., braking force, is generated.

[0051] The hydraulic pressure device 95 is composed of a reservoir tank for storing hydraulic oil, a master cylinder, a pump, etc. for pressurizing the hydraulic oil. Note that the reservoir tank, master cylinder, and pump are not shown in the figure. The control of the hydraulic pressure device 95 is executed by a brake electronic control unit (not shown in the figure). That is, the hydraulic pressure device 95 adjusts the pressure of the hydraulic oil (hydraulic pressure) applied to each of the brake pipes 96 according to an instruction from the brake electronic control unit. Thereby, the hydraulic pressure device 95 can generate braking forces with different magnitudes for the right front wheel brake 91, left front wheel brake 92, right rear wheel brake 93, and left rear wheel brake 94 respectively.

[0052] (2. Configuration of the vehicle control device 10) As shown in FIG. 1, the vehicle control device 10 is mounted on the vehicle 1. The vehicle control device 10 mainly includes an electronic control unit 11 (hereinafter, may be simply referred to as "ECU11"). ECU11 is communicable with the driving environment detection unit 12 and the display device 13. Here, ECU11 is also communicable with the operation ECU53 and the steering ECU54 via the communication line C.

[0053] ECU11 is mainly composed of a microcomputer equipped with a CPU, ROM, RAM, and various interfaces. The CPU reads data, performs numerical calculations, outputs calculation results, etc. by sequentially executing a predetermined program. The ROM stores programs, maps, etc. executed by the CPU. The RAM temporarily stores data, etc. The various interfaces are connected to the driving environment detection unit 12 and the display device 13.

[0054] The driving environment detection unit 12 detects the driving environment of the vehicle 1 and outputs driving environment information Je representing various detected driving environments to ECU11. The driving environment detection unit 12 is composed of a vehicle height sensor 121, a vehicle height sensor 122, a vehicle height sensor 123, and a vehicle height sensor 124.

[0055] The vehicle height sensor 121 detects the vehicle height H1 that changes according to the expansion and contraction from the reference position of the suspension unit 4 provided on the right front wheel 31. The vehicle height sensor 122 detects the vehicle height H2 that changes according to the expansion and contraction from the reference position of the suspension unit 4 provided on the left front wheel 32. The vehicle height sensor 123 detects the vehicle height H3 that changes according to the expansion and contraction from the reference position of the suspension unit 4 provided on the right rear wheel 33. The vehicle height sensor 124 detects the vehicle height H4 that changes according to the expansion and contraction from the reference position of the suspension unit 4 provided on the left rear wheel 34.

[0056] Further, the driving environment detection unit 12 includes a vehicle speed sensor 125 and a road surface state detection sensor 126. The vehicle speed sensor 125 detects the vehicle speed V of the vehicle 1. Here, the vehicle speed sensor 125 can calculate and detect the vehicle speed V based on the wheel speeds which are the rotational speeds of the right front wheel 31, the left front wheel 32, the right rear wheel 33, and the left rear wheel 34.

[0057] The road surface state detection sensor 126 includes, for example, a stereo camera or a LiDAR (Light Detection And Ranging, or Laser imaging Detection And Ranging), and detects the state of the road surface in the traveling direction of the vehicle 1. That is, the road surface state detection sensor 126 detects, as the state of the road surface, the unevenness of the road surface, the presence or absence of obstacles such as rocks and side ditches, undulations, ruts, steep downhill slopes, etc.

[0058] Here, obstacles such as rocks and side ditches apply an external disturbance (load) to the wheel 3 (in the first embodiment, particularly the right front wheel 31 and the left front wheel 32 which are the steered wheels) when the wheel 3 is in contact, and can change the operation of the wheel 3 (the steering state in the first embodiment). Then, the road surface state detection sensor 126 outputs road surface information RJ representing the detected state of the road surface.

[0059] Further, the driving environment detection unit 12 can include an accelerator sensor 127 and a brake sensor 128. The accelerator sensor 127 detects the accelerator operation amount A by the driver. The accelerator sensor 127 detects, for example, the depression amount of an accelerator pedal (not shown) by the driver as the accelerator operation amount A. The brake sensor 128 detects the brake operation amount B by the driver. The brake sensor 128 detects, for example, the depression amount of a brake pedal (not shown) by the driver as the brake operation amount B. Incidentally, the driving environment detection unit 12 can also include, for example, a receiver of GNSS (Global Navigation Satellite System), and a current position detection sensor that detects the current position of the vehicle 1 based on the received signal.

[0060] The display device 13 displays various information according to an instruction from the ECU 11. The display device 13 is provided, for example, in the vehicle interior, and can display the notification information J output from the ECU 11 to the driver and passengers as described later.

[0061] (2-1. Configuration of ECU 11) As shown in FIG. 2, the ECU 11 includes an acquisition unit 111, a situation determination unit 112, and a suppression unit 113. Further, the ECU 11 includes a cutoff operation determination unit 114, a situation change determination unit 115, a permission unit 116, a notification unit 117, and a return determination unit 118.

[0062] The acquisition unit 111 collectively acquires the detection results detected by the driving environment detection unit 12 as driving environment information Je. Specifically, the acquisition unit 111 can acquire the vehicle heights H1, H2, H3, and H4 from the vehicle height sensors 121, 122, 123, and 124 as the driving environment information Je. Further, the acquisition unit 12 can acquire the vehicle speed V from the vehicle speed sensor 125 and the road surface information RJ including whether there is an obstacle on the road surface from the road surface state detection sensor 126 as the driving environment information Je. Furthermore, the acquisition unit 111 can acquire the accelerator operation amount A from the accelerator sensor 127 and the brake operation amount B from the brake sensor 128 as the driving environment information Je.

[0063] Based on the driving environment represented by the driving environment information Je acquired by the acquisition unit 111, the situation determination unit 112 determines whether a predetermined situation occurs in which a disturbance acts on the wheels 3 to cause a change in the operation of the wheels 3 controlled by the electric motor, for example, the driving state (rotation state) of the wheels 3, the braking state (stopping state) of the wheels 3, or the steering state of the wheels 3. In the first embodiment, the situation determination unit 112 determines whether a situation occurs in which the vehicle is traveling on an uneven road that changes the steering operation of the right front wheel 31 and the left front wheel 32, which are steering wheels controlled by the steering motor 526, and more specifically, an uneven road with obstacles such as rocks.

[0064] Based on the determination result of the situation determination unit 112, more specifically, based on the determination result that a predetermined situation has occurred, the suppression unit 113 suppresses the restriction of the protection control for protecting the steering motor 526 by restricting the steering current I supplied to the steering motor 526. Specifically, when a predetermined situation occurs, the suppression unit 113 suppresses the execution of the protection control that is normally executed when the steering current I becomes larger than the upper limit value Tjs. That is, when the protection control suppression unit 113 suppresses the restriction in this way, the steering ECU 54 temporarily interrupts and does not execute the protection control.

[0065] Further, when a predetermined situation occurs, the suppression unit 113 determines a decrease amount or a lower limit value Ik after the decrease to decrease the steering current I to be equal to or less than the upper limit value Tjs, and suppresses the restriction by the protection control for determining to cut off the steering current I supplied to the steering motor 526. That is, when the suppression unit 113 suppresses the restriction in this way, the steering ECU 54, unlike the normal protection control, executes the protection control to decrease the steering current I until the determined decrease amount or the lower limit value Ik is reached.

[0066] Then, the suppression unit 113 outputs a command Oc or a command Oh representing the restriction to be suppressed to the steering ECU 54. That is, when the suppression unit 113 suppresses the protection control restriction so as to temporarily interrupt the execution of the protection control, it outputs the command Oc to the steering ECU 54. Further, when the suppression unit 113 determines the decrease amount or the lower limit value Ik of the steering current I and suppresses the protection control restriction, it outputs the command Oh to the steering ECU 54.

[0067] The cutoff operation determination unit 114 determines the presence or absence of a cutoff operation for cutting off the supply of the steering current I to the steering motor 526 based on various information acquired via the communication line C, for example. Note that examples of the cutoff operation include operations in which an ignition switch (not shown), a power switch (not shown), a start / stop switch (not shown), etc., operated by the driver are switched from the on state to the off state.

[0068] When the cutoff operation determination unit 114 determines that a cutoff operation has been performed, the situation change determination unit 115 determines whether or not the situation has changed to a stable situation in which the steering operations of the right front wheel 31 and the left front wheel 32 do not change from a predetermined situation based on the traveling environment information Je acquired by the acquisition unit 111. Then, as a determination result, the situation change determination unit 115 supplies information indicating whether the situation is a predetermined situation in which the situation has not changed or a stable situation in which the situation has changed to the permission unit 116 and the notification unit 117.

[0069] Here, when a predetermined situation occurs, for example, when a cutoff operation performed by the driver is accepted, the steering current I to the steering motor 526 is cut off. In this case, as described above, since the steering motor 526 does not generate force (torque), the steering operations of the right front wheel 31 and the left front wheel 32 are likely to change due to the action of disturbances. As a result, the vehicle 1 is likely to fall into an unintended situation, for example, a stack state in which forward and backward movement becomes impossible due to the presence of an obstacle.

[0070] On the one hand, when changing from a predetermined situation to a stable situation, for example, when the vehicle 1 is stopped stably, even if the steering motor 526 is not generating force (torque), the steering operation (or steering state) of the right front wheel 31 and the left front wheel 32 is less likely to change due to the action of disturbances. Therefore, the vehicle 1 is less likely to fall into, for example, a stacked state.

[0071] For this reason, based on the determination result of the situation change determination unit 115, when changing from a predetermined situation to a stable situation, the permission unit 116 permits the execution of a cutoff process corresponding to a cutoff operation. That is, the permission unit 116 permits the execution of a predetermined cutoff process for various electronic control units mounted on the vehicle 1 including, for example, the operation ECU 53 and the steering ECU 54 only when changing to a stable situation. Thereby, for example, the operation ECU 53 cuts off the supply of current to the reaction force motor 515, and the steering ECU 54 cuts off the supply of the steering current I to the steering motor 526.

[0072] The notification unit 117 notifies that the execution of the cutoff process is impossible when the cutoff operation has been performed and the situation has not changed from a predetermined situation to a stable situation based on the determination result of the situation change determination unit 115. Specifically, when the predetermined situation still exists and the cutoff operation is performed, the notification unit 117 outputs notification information J indicating that the cutoff operation by the driver is not accepted to the display device 13.

[0073] Based on the driving environment information Je acquired by the acquisition unit 111, when changing from a predetermined situation to a stable situation that does not cause a change in the operation of the wheel 3, the return command unit 118 returns the restriction of the protection control suppressed by the suppression unit 113 in the predetermined situation to the restriction of the protection control before being suppressed by the suppression unit 113 in the predetermined situation. That is, accompanying the change from a predetermined situation to a stable situation, the return command unit 118 commands to execute the normal protection control for protecting the steering motor 526 from overheating.

[0074] Specifically, when the return instruction unit 118 outputs an instruction Oc to temporarily interrupt the execution of the protection control by the suppression unit 113 due to a change to a stable state, the return instruction unit 118 outputs a return instruction Om to the steering ECU 54 to resume the execution of the protection control. Further, when the return instruction unit 118 outputs an instruction Oh to determine the decrease amount or lower limit value Ik of the steering current I and perform protection control by the suppression unit 113 due to a change to a stable state, the return instruction unit 118 outputs a return instruction Om to the steering ECU 54 to execute the normal protection control.

[0075] (3. Description of the Processing of the Vehicle Control Device 10) Next, the processing by the vehicle control device 10 will be described. Specifically, the ECU 11 of the vehicle control device 10 executes a control program shown by the flowchart in FIG. 3.

[0076] The ECU 11 (more specifically, the CPU of the microcomputer constituting the ECU 11) starts the execution of the control program at step S10. In the subsequent step S11, the ECU 11 acquires driving environment information Je representing the environment in which the vehicle 1 is currently driving. That is, the ECU 11 acquires the vehicle speed V from the driving environment detection unit 12, and in the first embodiment, acquires the vehicle heights H1 and H2 corresponding to the right front wheel 31 and the left front wheel 32, which are the steering wheels. Further, when the transfer switch 84 is operated, the ECU 11 acquires a range signal LS, and when switched to the defrost state, acquires a defrost signal DS. In addition, the ECU 11 acquires the steering current I detected by the current sensor 528 from the steering ECU 54 of the steering device 52, and acquires the steering angle θ detected by the steering angle sensor 529.

[0077] In step S12, based on the driving environment information Je acquired from the driving environment detection unit 12, the ECU 11 determines whether the vehicle 1 is in a predetermined situation, that is, whether there is an obstacle that can change the steering operation of the right front wheel 31 and the left front wheel 32 due to disturbances applied to the right front wheel 31 and the left front wheel 32. Here, as an example of the "predetermined situation", a situation where the vehicle 1 is driving on an uneven road can be exemplified. And in the situation where the vehicle 1 is driving on an uneven road, as shown in FIG. 4, for example, a large rock existing on the road surface can be exemplified as an "obstacle".

[0078] Regarding the vehicle height H1 on the right front wheel 31 side and the vehicle height H2 on the left front wheel 32 side included in the driving environment information Je, as shown in FIG. 4, the ECU 11 determines whether the deviation (or the absolute value of the difference) between the vehicle height H1 and the vehicle height H2 is greater than a preset left and right wheel deviation threshold Hs. And when the deviation between the vehicle height H1 and the vehicle height H2 is greater than the left and right wheel deviation threshold Hs, the ECU 11 determines "Yes" because the vehicle 1 is in a situation of driving on an uneven road.

[0079] Here, as shown in FIG. 4, assume a case where the right front wheel 31 and the left front wheel 32, which are the steering wheels, are riding on obstacles (such as rocks) with different heights. In this case, the deviation between the vehicle height H1 and the vehicle height H2 becomes large and the vehicle body 2 is tilted. And in this situation, for example, due to the influence of gravity acting as a disturbance, the left front wheel 32 on the side of the high rock is likely to rotate to the lower side in accordance with the tilt of the vehicle body 2, as indicated by the thick solid arrow in FIG. 4. Still, in the first embodiment, since the right front wheel 31 and the left front wheel 32 are connected via a steering actuator, a force to rotate the right front wheel 31 on the side of the low rock in the same direction as the left front wheel 32 also acts.

[0080] Incidentally, if the left front wheel 32 rotates in the direction of the arrow due to external disturbance, the left front wheel 32 may roll down from a high rock. In this case, for example, a high rock is located between the left front wheel 32 and the left rear wheel 34 and becomes an obstacle, and there is a possibility that the vehicle 1 cannot move forward or backward and gets stacked. Therefore, in the vehicle 1 traveling on an uneven road, it is important that the right front wheel 31 and the left front wheel 32, which are the steered wheels, cannot be rotated (steered) by external disturbance until the vehicle 1 reaches a stable state where it stops stably.

[0081] Therefore, in the subsequent step S13, the ECU 11 temporarily interrupts the execution of the protection control for the steering ECU 54. That is, the ECU 11 temporarily interrupts the execution of the protection control by the steering ECU 54 even in a situation where, for example, the steering torque Ts required to maintain the steering operation (steering state) of the right front wheel 31 and the left front wheel 32 against external disturbance is large, in other words, the steering current I supplied to the steering motor 526 is large, and a temperature rise due to heat generation of the steering motor 526 or the like may occur. As a result, the steering ECU 54 does not execute the protection control until the vehicle 1 exits the predetermined state of traveling on an uneven road and enters a stable state. Then, when the ECU 11 temporarily stops executing the protection control, it executes the step process of step S15.

[0082] On the other hand, when the deviation (or the absolute value of the difference) between the vehicle height H1 and the vehicle height H2 is equal to or less than the preset left-right wheel deviation threshold value Hs, the ECU 11 determines "No" because the vehicle 1 is in a stable state where it is not traveling on an uneven road. Then, the ECU 11 executes the step process of step S14.

[0083] Also, when the ECU 11 acquires the range signal LS from the transfer switch 84, or when it acquires the defrost signal DS from the defrost switch 85, since the vehicle 1 is in a situation of traveling on an uneven road, it determines "Yes". Then, in the subsequent step S13, the ECU 11 temporarily stops executing the protection control for the steering ECU 54. As a result, the steering ECU 54 does not execute the protection control until the vehicle 1 gets out of the situation of traveling on an uneven road. And when the ECU 11 temporarily stops executing the protection control, it executes the step process of step S15.

[0084] On the other hand, when the ECU 11 does not acquire the range signal LS from the transfer switch 84 and does not acquire the defrost signal DS from the defrost switch 85, since the vehicle 1 is not in a situation of traveling on an uneven road, it determines "No". Then, the ECU 11 executes the step process of step S14.

[0085] Furthermore, regarding the steering current I acquired from the current sensor 528, when the steering current I supplied to the steering motor 526 for controlling the steering operations of the right front wheel 31 and the left front wheel 32 is greater than the upper limit value Ijs, since the vehicle 1 is in a situation of traveling on an uneven road as a predetermined situation, it determines "Yes". Then, in the subsequent step S13, the ECU 11 temporarily interrupts executing the protection control for the steering ECU 54. As a result, the steering ECU 54 does not execute the protection control until the vehicle 1 gets out of the predetermined situation of traveling on an uneven road and enters a stable situation. That is, as shown in (b) in FIG. 5, the steering ECU 54 does not execute the protection control of cutting off the steering current I even when the steering current I becomes greater than the upper limit value Ijs.

[0086] When the ECU 11 temporarily stops executing the protection control, it executes the step process of step S15. Note that as shown in (a) in FIG. 5, when a predetermined time has elapsed after the vehicle speed V becomes "0", that is, when it can be determined that the vehicle is in a stable state, the steering ECU 54 can reduce the steering current I as shown by the broken line in (b) in FIG. 5.

[0087] Also, in step S13, the ECU 11 causes the steering ECU 54 to set a lower limit value Ik so as to limit the decrease amount of the steering current I when reducing the steering current I below the upper limit value Ijs by protection control as shown in (c) in FIG. 5, and executes the protection control. As a result, the steering ECU 54 sets the lower limit value Ik and reduces the steering current I to the lower limit value Ik less than the upper limit value Ijs by executing the protection control.

[0088] Note that the steering ECU 54 sets the lower limit value Ik based on the steering current I that generates a steering torque Ts that can resist disturbances assumed when the vehicle 1 travels on an uneven road, that is, a degree such that the state of the wheel 3 does not change due to the disturbance. When the ECU 11 suppresses the limitation of the normal protection control and executes the protection control, it executes the step process of step S15.

[0089] On the other hand, when the steering current I is less than or equal to the upper limit value Ijs, since the vehicle 1 is not traveling on an uneven road, the ECU 11 determines "No". Then, the ECU 11 executes the step process of step S14.

[0090] In step S14, since the vehicle 1 is traveling on a good road that is not an uneven road, the ECU 11 can execute the normal protection control. Also, in step S14, since the vehicle has changed from a predetermined state of traveling on an uneven road to a stable state of traveling on a good road, the ECU 11 can resume and execute the normal protection control. As a result, when the steering current I becomes larger than the upper limit value Ijs, the steering ECU 54 can execute the normal protection control.

[0091] Still, in step S12, the ECU 11 can also determine a situation of traveling on an uneven road, that is, a predetermined situation, by appropriately combining the above three determinations. For example, when the deviation between the vehicle height H1 and the vehicle height H2 is larger than the left and right wheel deviation threshold value Hs and the steering current I is larger than the upper limit value Ijs, since the vehicle 1 is in a situation of traveling on an uneven road as a predetermined situation, it can be determined as "Yes". Also, when the ECU 11 acquires the range signal LS from the transfer switch 84 or acquires the differential lock signal DS from the differential lock switch 85 and the steering current I is larger than the upper limit value Ijs, since the vehicle 1 is in a situation of traveling on an uneven road as a predetermined situation, it can be determined as "Yes".

[0092] Also, when the deviation between the vehicle height H1 and the vehicle height H2 is larger than the left and right wheel deviation threshold value Hs and the ECU 11 acquires the range signal LS from the transfer switch 84 or acquires the differential lock signal DS from the differential lock switch 85, since the vehicle 1 is in a situation of traveling on an uneven road as a predetermined situation, it can be determined as "Yes". Furthermore, when the deviation between the vehicle height H1 and the vehicle height H2 is larger than the left and right wheel deviation threshold value Hs, the ECU 11 acquires the range signal LS from the transfer switch 84 or acquires the differential lock signal DS from the differential lock switch 85, and the steering current I is larger than the upper limit value Ijs, since the vehicle 1 is in a situation of traveling on an uneven road as a predetermined situation, it can be determined as "Yes".

[0093] In step S15, the ECU 11 determines, as a cutoff operation for cutting off the supply of the steering current I to the steering motor 526, whether or not an off operation is performed to switch off, for example, the above-described ignition switch or the like (hereinafter simply referred to as "I / G or the like"). That is, if the I / G or the like is turned off by the driver, the ECU 11 determines "Yes" and executes the step process of step S16. On the other hand, if the I / G or the like is not turned off by the driver, that is, if the I / G or the like is maintained in the on state so as not to cut off the supply of the steering current I to the steering motor 526, the ECU 11 determines "No" and executes each step process after step S11 again.

[0094] In step S16, the ECU 11 determines whether or not the steering current I is equal to or less than the upper limit value Ijs. That is, in step S16, the ECU 11 determines whether or not the steering current I is equal to or less than the upper limit value Ijs in a state where it is determined in step S15 that the I / G or the like has been turned off.

[0095] Specifically, in step S16, if the steering current I is equal to or less than the upper limit value Ijs, the ECU 11 determines "Yes" and executes the step process of step S17. That is, in this case, based on the fact that the steering current I is equal to or less than the upper limit value Ijs, the ECU 11 determines that at least the steering motor 526 is not in a situation of maintaining the steering operation (steering state) of the wheel 3 against disturbances input from the road surface of the rough road or obstacles. In other words, the ECU 11 determines that there is a low possibility that an unintended change in the operation of the wheel 3 occurs due to disturbances and that the vehicle 1 is in a stable state where it has stopped stably, and that there is a low possibility that a non-drivable state such as a stack occurs in the vehicle 1. Therefore, in this case, the ECU 11 determines to accept the off operation of the I / G or the like, which is a cutoff operation for cutting off the supply of the steering current I to the steering motor 526.

[0096] In step S17, in accordance with the off operation of the ignition switch (I / G) or the like by the driver, the ECU 11 permits the various electronic control units mounted on the vehicle 1, including the operation ECU 53 and the steering ECU 54, to perform a shut-off process, that is, to switch the ignition switch (I / G) or the like from the on state to the off state. As a result, each of the various electronic control units executes a predetermined shut-off process when the ignition switch (I / G) or the like is switched to the off state. Accordingly, the operation ECU 53 shuts off the supply of current to the reaction motor 515, and the steering ECU 54 shuts off the supply of the steering current I to the steering motor 526.

[0097] When receiving the off operation of the ignition switch (I / G) or the like by the driver in step S17, the ECU 11 temporarily terminates the execution of the control program in step S19. Then, when a predetermined short period of time has elapsed, the ECU 11 starts the execution of the control program again in step S10.

[0098] On the other hand, in step S16, if the steering current I is not less than the upper limit value Ijs, the ECU 11 determines "No" and executes the step process of step S18. That is, in this case, based on the fact that the steering current I is not less than the upper limit value Ijs, the ECU 11 determines that the steering motor 526 is still in a predetermined state of maintaining the steering operation (steering state) of the wheel 3 against the disturbance input from the road surface of the rough road or an obstacle. In other words, the ECU 11 determines that there is a high possibility that an unintended change in the operation of the wheel 3 will occur due to the disturbance, and as a result, there is a high possibility that the vehicle 1 will not stop stably and a non-drivable state such as stacking will occur in the vehicle 1. Accordingly, in this case, the ECU 11 determines not to accept the off operation of the ignition switch (I / G) or the like, which is a shut-off operation for shutting off the supply of the steering current I to the steering motor 526.

[0099] In step S18, the ECU 11 notifies the driver and passengers that it does not accept the off operation of the I / G or the like by the driver. Specifically, the ECU 11 or the like causes the display device 13 to display a message or a figure such as "Please move the vehicle to a safe place and then operate the ignition switch." When notifying, instead of or in addition to displaying on the display device 13, it is also possible to notify by voice using a speaker or the like provided in the vehicle 1. Then, when the ECU 11 notifies the driver and passengers, it temporarily terminates the execution of the control program in step S19. Then, when a predetermined short time elapses, the ECU 11 starts the execution of the control program again in step S10.

[0100] As can be understood from the above description, the vehicle control device 10 according to the first embodiment is applied to a vehicle 1 including a steering motor 526 as an electric motor that controls the steering operation, which is the operation of the wheels 3, that is, the right front wheel 31 and the left front wheel 32. The vehicle control device 10 includes an acquisition unit 111 that acquires driving environment information Je representing the driving environment of the vehicle 1, a situation determination unit 112 that determines whether or not a predetermined situation has occurred in which a disturbance acts on the right front wheel 31 and the left front wheel 32 so as to cause a change in the steering operation based on the driving environment information Je, and a suppression unit 113 that suppresses the limitation of the protection control for protecting the steering motor 526 by limiting the steering current I supplied to the steering motor 526 when the predetermined situation has occurred.

[0101] In this case, the vehicle control device 10 includes a cutoff operation determination unit 114 that determines the presence or absence of a cutoff operation for cutting off the supply of the steering current I in a predetermined situation, a situation change determination unit 115 that determines whether or not a change has occurred to a stable situation in which the operations of the right front wheel 31 and the left front wheel 32 do not change from the predetermined situation when the cutoff operation is performed, and a permission unit 116 that permits the execution of the cutoff process corresponding to the cutoff operation when a change has occurred from the predetermined situation to the stable situation. In this case, the vehicle control device 10 includes a notification unit 117 that notifies that the execution of the cutoff process is impossible when the cutoff operation is performed and the change from the predetermined situation to the stable situation has not occurred.

[0102] Further, in this case, the predetermined situation is a situation where there is an obstacle that can change the operations of the right front wheel 31 and the left front wheel 32 by disturbing the right front wheel 31 and the left front wheel 32.

[0103] Further, in this case, the predetermined situation is a situation where the vehicle 1 travels on an uneven road surface.

[0104] Further, in this case, the vehicle control device 10 suppresses the limitation by the suppression unit 113 temporarily interrupting the execution of the protection control.

[0105] Further, in this case, the vehicle control device 10 suppresses the limitation such that the amount of decrease in the steering current I when the suppression unit 113 decreases the steering current I in the protection control is smaller than the amount of decrease when the predetermined situation does not occur.

[0106] Further, in this case, the vehicle control device 10 suppresses the limitation such that the lower limit value Ik of the steering current I when the suppression unit 113 decreases the steering current I in the protection control is larger than the lower limit value Ik when the predetermined situation does not occur.

[0107] Further, in this case, the vehicle control device 10 determines that the predetermined situation has occurred when the deviation between the vehicle heights H1 and H2 of the right front wheel 31 and the left front wheel 32 on the left and right is larger than a preset left-right wheel deviation threshold value Hs by the situation determination unit 112.

[0108] Further, in this case, the vehicle control device 10 determines that the predetermined situation has occurred when the center differential 81 as a transfer mounted on the vehicle 1 is set to the LOW range indicating a low speed, or when the differential device 8 mounted on the vehicle 1 is set to the diff lock indicating that it is locked by the situation determination unit 112.

[0109] Further, in this case, the vehicle control device 10 determines that the predetermined situation has occurred when the magnitude of the steering current I supplied to the steering motor 526 to control the steering operation is larger than the magnitude of a preset upper limit value Ijs by the situation determination unit 112.

[0110] Furthermore, in this case, when the vehicle control device 10 changes from a predetermined situation to a stable situation where the operations of the right front wheel 31 and the left front wheel 21 do not change based on the driving environment information Je representing the driving environment, the vehicle control device 10 has a return command unit 118 that returns the restriction of the protection control suppressed by the suppression unit 113 in the predetermined situation to the restriction of the protection control before being suppressed by the suppression unit 113 in the predetermined situation.

[0111] According to the vehicle control device 10, when the suppression unit 113 is in a predetermined situation where a disturbance that causes the vehicle 1 to change the steering operation of the right front wheel 31 and the left front wheel 32 acts, the suppression unit 113 can suppress the restriction of the protection control for protecting the steering motor 526. Thereby, when the vehicle 1 is in a predetermined situation, a steering current I with the restriction suppressed can be supplied to the steering motor 526, and the steering motor 526 can generate a force (torque) to resist the disturbance acting on the right front wheel 31 and the left front wheel 32. Therefore, in a predetermined situation, the influence of the disturbance on the steering operations of the right front wheel 31 and the left front wheel 32 can be reduced.

[0112] Note that the steering motor 526 is provided in the steering system 5. The steering system 5 of the first embodiment is a steer-by-wire type including an operation device 51 having a steering wheel 511 as an operation member operated by a driver, a steering device 52 having the steering motor 526 and steering the right front wheel 31 and the left front wheel 32, and an operation ECU 53 and a steering ECU 54 which are controllers that realize the steering of the right front wheel 31 and the left front wheel 32 according to the operation of the steering wheel 511 by the steering device 52 by controlling the steering current I supplied to the steering motor 526.

[0113] B. Second Embodiment (1. Configuration of the vehicle 1 to which the vehicle control device 10 is applied) In the second embodiment, the vehicle control device 10 is applied to the vehicle 1 shown in FIG. 6. In the vehicle 1 of the second embodiment, the steering system 5 has a wheel steering device 58 capable of independently steering each of the right front wheel 31 and the left front wheel 32, which are steered wheels, instead of the steering device 52 of the first embodiment described above. Specifically, in the second embodiment, each wheel steering device 58 is incorporated in the wheel arrangement module 200.

[0114] Here, in the second embodiment, instead of the steering device 52, a pair of wheel steering devices 58 are arranged corresponding to each of the right front wheel 31 and the left front wheel 32, which are steered wheels. Therefore, as shown in FIG. 6, in order to independently control each wheel steering device 58, the steering ECU 54 described in the first embodiment above is composed of a steering ECU 541 that controls the wheel steering device 58 arranged on the right front wheel 31 and a steering ECU 542 that controls the wheel steering device 58 arranged on the left front wheel 32. And the steering ECU 541 and the steering ECU 542 are configured to execute normal protection control in the same manner as the steering ECU 54. In FIG. 6, the steering ECU 541 is shown as "S-ECU541" and the steering ECU 542 is shown as "S-ECU542".

[0115] Also, in the second embodiment, with the provision of the wheel steering device 58 instead of the steering device 52, the motor rotation angle sensor 527, the current sensor 528, and the steering angle sensor 529 described in the first embodiment are respectively shown as a motor rotation angle sensor 587, a current sensor 588, and a steering angle sensor 589 as shown in FIG. 6. Also, the temperature sensor 55 that detects the motor temperature Tm described in the first embodiment is shown as the temperature sensor 59. The motor rotation angle sensor 587, the current sensor 588, the steering angle sensor 589, and the temperature sensor 59 detect the target physical quantities in the same manner as the motor rotation angle sensor 527, the current sensor 528, the steering angle sensor 529, and the temperature sensor 55 of the first embodiment described above.

[0116] In the second embodiment as well, steering system 5 which is the object of control by vehicle control device 10 is a steer-by-wire type equipped with mechanically independent operation device 51 and a pair of wheel turning devices 58. Here, in steering system 5 equipped with a pair of wheel turning devices 58, operation ECU 53 which controls operation device 51 supervises a pair of steering ECUs 541 and 542 which respectively control the pair of wheel turning devices 58.

[0117] As shown in Fig. 7, the wheel installation module 200 has a wheel drive unit 210 as a drive system. The wheel drive unit 210 has a housing 211, an electric motor as a drive source built into the housing 211, a reducer for reducing the rotation of the electric motor (both not shown), and an axle hub (hidden in Fig. 6) to which a wheel constituting the wheel 3 is attached. The wheel drive unit 210 is disposed inside the rim of the wheel constituting the wheel 3, and is a so-called in-wheel motor unit. Note that the wheel drive unit 210, that is, the in-wheel motor unit, has a well-known structure, and therefore description of its structure will be omitted.

[0118] The wheel installation module 200 also has a suspension unit 220. In the suspension unit 220, a housing 211 of the wheel drive unit 210 functions as a carrier that rotatably supports the wheel 3, and the housing 211 functions as a steering knuckle in a wheel turning device 58 described later, allowing vertical movement relative to the vehicle body 2. Therefore, the suspension unit 220 is configured to include a lower arm 221 which is a suspension arm, the housing 211 of the wheel drive unit 210, a coil spring 222, and a hydraulic shock absorber 223.

[0119] Furthermore, the wheel arrangement module 200 has a brake unit 230 as a braking system. The brake unit 230 includes a disk rotor 231 that is attached to an axle hub together with the wheel constituting the wheel 3 and rotates with the wheel 3, and a brake caliper 232 that is held by the housing 211 of the wheel drive unit 210 so as to straddle the disk rotor 231. In the second embodiment, the brake caliper 232 has an electric motor that generates a pressing force for pressing a brake pad as a friction member against the disk rotor 231. That is, the brake unit 230 of the second embodiment is an electric brake unit that generates a braking force depending on the force generated by the electric motor.

[0120] Furthermore, the wheel arrangement module 200 has a wheel steering device 58. The wheel steering device 58 is a single-wheel independent steering device for steering only one of a pair of left and right front wheels 31 and 32 (for example, the right front wheel 31) independently of the other (for example, the left front wheel 32). The wheel steering device 58 includes a housing 211 of the wheel drive unit 210 that functions as a steering knuckle, a steering actuator 240 disposed on the lower arm 221 at a position close to the base end portion of the lower arm 221 of the suspension unit 220, and a tie rod 241 that connects the steering actuator 240 and the housing 211 (steering knuckle).

[0121] Here, the steering actuator 240 includes a steering motor 242 that is an electric motor, a speed reducer 243 that decelerates the rotation of the steering motor 242, and an actuator arm 244 that is rotated by the rotation of the steering motor 242 via the speed reducer 243 and functions as a pitman arm.

[0122] The base end portion of the tie rod 241 is connected to the actuator arm 244 via a ball joint 245. Also, the tip end portion of the tie rod 241 is connected to a knuckle arm 212 of the housing 211 (steering knuckle) via a ball joint 246.

[0123] The steering control of the wheel steering device 58 incorporated in each of the pair of wheel arrangement modules 200 is control for steering each of the right front wheel 31 and the left front wheel 32, which are steering wheels, to a steering angle θ corresponding to a steering request. Also, in the steering system 5 having the wheel steering device 58, similar to the steering system 5 of the first embodiment having the steering device 52, the operation ECU 53 acquires the operation angle δ, and determines the target steering angles θd of the right front wheel 31 and the left front wheel 32 according to the formula (1).

[0124] Then, the steering ECU 541 and the steering ECU 542 each determine a target motor rotation angle νd, which is the target of the motor rotation angle ν of the steering motor 242, based on the target steering angle θd, similar to the steering ECU 54 of the first embodiment. Then, the steering ECU 541 and the steering ECU 542 detect the actual motor rotation angle ν of the steering motor 526 via the motor rotation angle sensor 527, and determine a motor rotation angle deviation Δν, which is the deviation of the motor rotation angle ν with respect to the target motor rotation angle νd, according to the formula (2).

[0125] Also, the steering ECU 541 and the steering ECU 542 determine a steering torque Ts to be generated by the steering motor 242 according to a feedback control law based on the motor rotation angle deviation Δν, similar to the steering ECU 54 of the first embodiment. That is, the steering ECU 541 and the steering ECU 542 also determine the steering torque Ts according to the formula (3).

[0126] Furthermore, similar to the steering ECU 54 in the first embodiment, the steering ECUs 541 and 542 provide an upper limit value Ijs for the steering current I supplied to the steering motor 242 according to the driving environment of the vehicle 1, and in principle, it is prohibited to supply a steering current I exceeding the upper limit value Ijs. That is, when the steering current I determined according to the steering torque Ts calculated according to the above formula (3) exceeds the upper limit value Ijs, the steering ECUs 541 and 542 can also execute protection control to make the supplied steering current I not exceed the upper limit value Ijs. When the steering ECUs 541 and 542 execute protection control in the second embodiment, the motor temperature Tm, which is the temperature of the steering motor 242, is detected by the temperature sensor 59.

[0127] Here, in the second embodiment, the case where the wheel arrangement modules 200 are arranged on each of the right front wheel 31 and the left front wheel 32 of the vehicle 1 is exemplified. However, if necessary, the wheel arrangement modules 200 can also be arranged on each of the right rear wheel 33 and the left rear wheel 34 of the vehicle 1. That is, in this case, the vehicle 1 is configured such that the right front wheel 31, the left front wheel 32, the right rear wheel 33, and the left rear wheel 34 are driven and steered. And in this case, in order to control the wheel steering devices 58 of the wheel arrangement modules 200 arranged on the right rear wheel 33 and the left rear wheel 34, corresponding steering ECUs are provided, and each steering ECU also controls the corresponding wheel steering device 58 in the same manner as the above-described steering ECUs 541 and 542.

[0128] In addition, in the second embodiment, the case where the wheel arrangement module 200 includes a wheel drive unit 210 (in-wheel motor unit) as a drive system and a brake unit 230 (electric brake unit) as a brake system is exemplified. However, if necessary, the wheel drive unit 210 can be omitted from the wheel arrangement module 200, or the brake unit 230 can be omitted from the wheel arrangement module 200. That is, in this case, the wheel arrangement module 200 is configured to include a suspension unit 220 and a wheel steering device 58 that constitutes the steering system 5.

[0129] When the wheel drive unit 210 is omitted from the wheel arrangement module 200, the vehicle 1 can include, for example, the engine 6, the transmission 7, and the differential device 8, similar to the first embodiment described above. Thereby, the vehicle 1 can travel with a driving force applied to the wheels 3. Also, when the brake unit 230 is omitted from the wheel arrangement module 200, the vehicle 1 can include, for example, the right front wheel brake 91 and the left front wheel brake 92, similar to the first embodiment described above. Thereby, the vehicle 1 can stop with a braking force applied to the wheels 3.

[0130] (2. Description of the processing of the vehicle control device 10) In the second embodiment, the ECU 11 of the vehicle control device 10 executes the control program shown by the flowchart of FIG. 8. Note that the control program executed by the ECU 11 in the second embodiment mainly changes the processing restrictions of steps S12 and S16 of the control program executed by the ECU 11 in the first embodiment described above. Therefore, in the following, "100" is added to each step number of the "control program" described in the first embodiment to show the "control program" of the second embodiment in FIG. 8. And, by omitting the detailed description of the substantially same step processing, the processing substantially changed in the second embodiment will be described in detail.

[0131] In the second embodiment, the ECU 11 starts the execution of the control program in step S100, and then acquires the driving environment information Je in step S111. Then, the ECU 11 executes the step processing of step S112.

[0132] In step S112, the comparison process of comparing the steering current I supplied to the steering motor 526 shown in step S12 of the control program of the first embodiment described above with the upper limit value Ijs is omitted. And in step S112, the comparison process of the steering current IR supplied to the steering motor 242 arranged on the right side (right front wheel 31 (or right rear wheel 33)) of the vehicle 1 with the upper limit value Ijs, and the comparison process of the steering current IL supplied to the steering motor 242 arranged on the left side (left front wheel 32 (or left rear wheel 34)) of the vehicle 1 with the upper limit value Ijs are newly added.

[0133] Thereby, in step S112, for the steering current IR acquired from the current sensor 528 arranged on the right front wheel 31, when the steering current IR is larger than the upper limit value Ijs, since the vehicle 1 is in a situation of traveling on an uneven road as a predetermined situation, the ECU 11 determines "Yes". And in the subsequent step S113, the ECU 11 temporarily interrupts the execution of the protection control for the steering ECU 541 or sets the lower limit value Ik to cause the protection control to be executed. Thereby, the steering ECU 541 does not execute the normal protection control until the vehicle 1 gets out of the predetermined situation of traveling on an uneven road and enters a stable situation.

[0134] Also, for the acquired steering current IR, when the steering current IR is less than or equal to the upper limit value Ijs, since the vehicle 1 is not in a situation of traveling on an uneven road, the ECU 11 determines "No". And in the subsequent step S114, since the vehicle 1 is in a situation of traveling on a good road that is not an uneven road, the ECU 11 enables the execution of the normal protection control. Also, in step S114, since the situation has changed from a predetermined situation of traveling on an uneven road to a stable situation of traveling on a good road, the ECU 11 enables the restoration and execution of the normal protection control. Thereby, when the steering current IR becomes larger than the upper limit value Ijs, the steering ECU 541 can execute the normal protection control.

[0135] Also, in step S112, regarding the steering current IL acquired from the current sensor 528 disposed on the left front wheel 32, when the steering current IL is greater than the upper limit value Ijs, since the vehicle 1 is traveling on an uneven road as a predetermined situation, it is determined as "Yes". Then, in the subsequent step S113, the ECU 11 temporarily interrupts the execution of the protection control for the steering ECU 542 or sets the lower limit value Ik and causes the protection control to be executed. As a result, the steering ECU 542 does not execute the normal protection control until the vehicle 1 exits the predetermined situation of traveling on an uneven road and enters a stable situation.

[0136] Also, regarding the acquired steering current IL, when the steering current IL is less than or equal to the upper limit value Ijs, the ECU 11 determines "No" because the vehicle 1 is not traveling on an uneven road. Then, in the subsequent step S114, since the vehicle 1 is traveling on a good road that is not an uneven road, it is possible to execute the normal protection control. Also, in step S114, since the situation has changed from the predetermined situation of traveling on an uneven road to a stable situation of traveling on a good road, it is possible to resume and execute the normal protection control. As a result, the steering ECU 542 can execute the protection control normally when the steering current IL becomes greater than the upper limit value Ijs.

[0137] Here, in the second embodiment, the steering motors 242 are respectively disposed on the right front wheel 31 and the left front wheel 32. For this reason, as shown in (b) of FIG. 9, for example, the steering current IR supplied to the steering motor 242 of the right front wheel 31 does not become greater than the upper limit value Ijs, and as shown in (c) and (d) of FIG. 9, for example, the steering current IL supplied to the steering motor 242 of the left front wheel 32 may become greater than the upper limit value Ijs. In this case, the steering ECU 541 that controls the steering motor 242 on the right front wheel 31 side does not execute any protection control including the normal protection control.

[0138] On the other hand, as shown in FIG. 9(b), the steering ECU 542 that controls the steering motor 242 on the left front wheel 32 side does not execute the protection control to cut off the steering current I even when the steering current IR becomes larger than the upper limit value Ijs. Incidentally, as shown in FIG. 9(a), when a predetermined time has elapsed after the vehicle speed V becomes "0", the steering ECU 54 can lower the steering current I as indicated by the broken line in FIG. 9(b).

[0139] Further, when executing the protection control, the steering ECU 542 temporarily suppresses the limitation of the normal protection control. Specifically, a lower limit value Ik is set, and by executing the suppressed protection control, the steering current IR is decreased to the lower limit value Ik that is less than the upper limit value Ijs. Incidentally, the lower limit value Ik determined by the steering ECU 542 in the second embodiment is also set based on, for example, the steering torque Ts that can resist the disturbance assumed when the vehicle 1 travels on an uneven road surface, that is, the steering current IR that can prevent the state of the wheel 3 from changing due to the disturbance.

[0140] Incidentally, in the vehicle 1 of the second embodiment, the transfer switch 84 and the differential lock switch 85 are not provided. Therefore, in step S112, the ECU 11 omits the determination of whether the range signal LS is acquired from the transfer switch 84 or the differential lock signal DS is acquired from the differential lock switch 85. However, as described above, when the wheel drive unit 210 is omitted from the wheel arrangement module 200 and the differential device 8 is mounted on the vehicle 1, the ECU 11 makes the same determination as in step S12 of the first embodiment described above, that is, determines whether the range signal LS is acquired from the transfer switch 84 or the differential lock signal DS is acquired from the differential lock switch 85.

[0141] Then, after the step process of step S113 or step S114, the ECU 11 determines whether a cutoff operation has been performed in step S115, and if a cutoff operation has been performed, executes the step process of step S116.

[0142] In step S116, the ECU 11 determines whether the steering current IR is equal to or less than the upper limit value Ijs, and whether the steering current IL is equal to or less than the upper limit value Ijs. That is, in step S116 as well, the ECU 11 determines whether the steering current IR and the steering current IL are equal to or less than the upper limit value Ijs in a state where it has been determined in step S115 that the cutoff operation has been performed.

[0143] Specifically, in step S116, if the steering current IR and the steering current IL are equal to or less than the upper limit value Ijs, the ECU 11 determines "Yes" and executes the step process of step S117. On the other hand, in step S116, if the steering current IR or the steering current IL is greater than the upper limit value Ijs, the ECU 11 determines "No" and executes the step process of step S118. Then, in step S119, the ECU 11 temporarily terminates the execution of the control program, and when a predetermined short time has elapsed, it starts the execution of the control program again in step S10.

[0144] As can be understood from the above description, the steering system 5 of the second embodiment includes an operating device 51 having a steering wheel 511 operated by a driver, a wheel steering device 58 as a pair of steering devices that respectively steer the right front wheel 31 and the left front wheel 32 (and the right rear wheel 33 and the left rear wheel 34) of the vehicle 1, and a steering ECU 541 and a steering ECU 542 that are controllers for realizing the respective steering of the right front wheel 31 and the left front wheel 32 (and the right rear wheel 33 and the left rear wheel 34) according to the operation of the steering wheel 511 by each of the pair of wheel steering devices 58 by controlling the steering current IR and the steering current IL supplied to each of the steering motors 242 of the pair of wheel steering devices 58. It is a steer-by-wire type. And in the second embodiment as well, the same effects as those of the first embodiment described above can be obtained.

[0145] C. Modification In the above-described first and second embodiments, as the electric motors to be controlled by the vehicle control device 10, a drive system (for example, the wheel drive unit 210) that drives the wheels 3, a brake system (for example, the brake unit 230) that brakes the wheels 3, and among the steering systems 5 that steer the wheels 3, at least the steering motors 526 and 242 provided in the steering system 5 have been exemplified and described. By the way, the vehicle control device can control an electric motor for which protection control is executed as a control target.

[0146] Specifically, for example, an in-wheel motor that constitutes a drive system (wheel drive unit 210), a traveling motor mounted on an EV (electric vehicle), an electric motor provided in an electric caliper that constitutes a brake system (brake unit 230), or the above-described reaction force motor 515 that constitutes the steering system 5 or an electric motor (EPS motor) that constitutes an electric power steering device can be made a control target of the vehicle control device. For these electric motors, for example, protection control may be executed when traveling on an uneven road and can become a control target of the vehicle control device.

[0147] Also, in the above-described first and second embodiments, the case where the operating device 51 is operated by the driver has been exemplified. That is, the case where the vehicle control device 10 is applied to the vehicle 1 that travels by manual driving by the driver has been exemplified. Instead of this, it is also possible to apply the vehicle control device 10 to the vehicle 1 that travels by autonomous driving. Also in this case, regardless of the difference between manual driving and autonomous driving, since a predetermined situation can occur in the traveling environment of the vehicle 1, the vehicle control device 10 can control the steering motors 526 and 242 that are electric motors, similarly to the above-described first and second embodiments. Therefore, also in this case, the same effects as those of the above-described first and second embodiments can be obtained.

[0148] Here, the vehicle control device according to the first aspect of the present disclosure is a vehicle control device applied to a vehicle equipped with an electric motor that controls the operation of wheels, and includes an acquisition unit that acquires driving environment information representing the driving environment of the vehicle, a situation determination unit that determines whether or not a predetermined situation has occurred in which a disturbance acts on the wheels so as to cause a change in the operation based on the driving environment information, and a suppression unit that suppresses the limitation of protection control for protecting the electric motor by limiting the current supplied to the electric motor when the predetermined situation has occurred.

[0149] Further, the vehicle control device according to the second aspect of the present disclosure is the vehicle control device according to the first aspect, and includes a cutoff operation determination unit that determines whether or not there is a cutoff operation for cutting off the supply of current in a predetermined situation, a situation change determination unit that determines whether or not a change has occurred to a stable situation in which a change in the operation is not caused from the predetermined situation when the cutoff operation is performed, and a permission unit that permits the execution of a cutoff process corresponding to the cutoff operation when a change has occurred from the predetermined situation to the stable situation.

[0150] Further, the vehicle control device according to the third aspect of the present disclosure is the vehicle control device according to the second aspect, and includes a notification unit that notifies that the execution of the cutoff process is impossible when the cutoff operation is performed and the situation has not changed from the predetermined situation to the stable situation.

[0151] Further, the vehicle control device according to the fourth aspect of the present disclosure is the vehicle control device according to any one of the first to third aspects, and the predetermined situation is a situation in which there is an obstacle that can change the operation by disturbing the wheels.

[0152] Further, the vehicle control device according to the fifth aspect of the present disclosure is the vehicle control device according to any one of the first to third aspects, and the predetermined situation is a situation in which the vehicle is traveling on an uneven road.

[0153] Further, the vehicle control device according to the sixth aspect of the present disclosure is the vehicle control device according to any one of the first to fifth aspects, and the suppression unit suppresses the limitation by temporarily interrupting the execution of the protection control.

[0154] Further, in the vehicle control device according to the seventh aspect of the present disclosure, in any one of the vehicle control devices according to the first to sixth aspects, when the suppression unit reduces the current in the protection control, the suppression unit suppresses the limitation so that the reduction amount is smaller than the reduction amount when the predetermined situation does not occur.

[0155] Further, in the vehicle control device according to the eighth aspect of the present disclosure, in any one of the vehicle control devices according to the first to seventh aspects, when the suppression unit reduces the current in the protection control, the suppression unit suppresses the limitation so that the lower limit value is larger than the lower limit value when the predetermined situation does not occur.

[0156] Further, in the vehicle control device according to the ninth aspect of the present disclosure, in any one of the vehicle control devices according to the first to eighth aspects, the situation determination unit determines that a predetermined situation has occurred when the deviation in vehicle height between the left and right wheels is greater than a preset left-right wheel deviation threshold.

[0157] Further, in the vehicle control device according to the tenth aspect of the present disclosure, in any one of the vehicle control devices according to the first to ninth aspects, the situation determination unit determines that a predetermined situation has occurred when the transfer mounted on the vehicle is set to the LOW range indicating low speed, or when the differential device mounted on the vehicle is set to the deflock indicating that it is locked.

[0158] Further, in the vehicle control device according to the eleventh aspect of the present disclosure, in any one of the vehicle control devices according to the first to tenth aspects, the situation determination unit determines that a predetermined situation has occurred when the magnitude of the current supplied to the electric motor to control the operation is greater than the magnitude of a preset upper limit value.

[0159] Further, in the vehicle control device according to the twelfth aspect of the present disclosure, in any one of the vehicle control devices according to the first to eleventh aspects, based on the driving environment, when the vehicle changes from a predetermined situation to a stable situation where the operation does not change, a return command unit is provided to return the protection control limitation suppressed by the suppression unit in the predetermined situation to the protection control limitation before being suppressed by the suppression unit in the predetermined situation.

[0160] Furthermore, in the vehicle control device according to the thirteenth aspect of the present disclosure, in any one of the vehicle control devices according to the first aspect to the twelfth aspect, the electric motor is provided in at least the steering system among a drive system that drives the wheels, a brake system that brakes the wheels, and a steering system that steers the wheels.

[0161] Furthermore, the vehicle control device according to the fourteenth aspect of the present disclosure is the vehicle control device according to the thirteenth aspect, wherein the steering system is a steer-by-wire type including an operating device having an operating member operated by a driver, a steering device having an electric motor and steering the wheels, and a controller that controls the current supplied to the electric motor to realize the steering of the wheels according to the operation of the operating member by the steering device.

[0162] Furthermore, the vehicle control device according to the fifteenth aspect of the present disclosure is the vehicle control device according to the thirteenth aspect, wherein the steering system is a steer-by-wire type including an operating device having an operating member operated by a driver, a pair of steering devices that respectively steer the left and right wheels of the vehicle, and a controller that controls the current supplied to each of the electric motors of the pair of steering devices to realize the steering of each of the left and right wheels according to the operation of the operating member by each of the pair of steering devices.

Description of Reference Numerals

[0163] 1... Vehicle, 2... Vehicle body, 3... Wheels, 4... Suspension unit, 5... Steering system, 526... Steering motor (electric motor), 8... Differential device, 9... Brake system, 10... Vehicle control device, 11... ECU, 111... Acquisition unit, 112... Situation determination unit, 113... Suppression unit, 114... Cut-off operation determination unit, 115... Situation change determination unit, 116... Permission unit, 117... Notification unit, 118... Return command unit, 12... Driving environment detection unit, 13... Display device, 200... Wheel arrangement module, 242... Steering motor (electric motor), Je... Driving environment information, I... Steering current (current), Ijs... Upper limit value, Ik... Lower limit value

Claims

1. A vehicle control device applied to a vehicle equipped with an electric motor that controls the operation of wheels, comprising: an acquisition unit that acquires driving environment information representing the driving environment of the vehicle; a situation determination unit that determines whether or not a predetermined situation has occurred in which a disturbance acts on the wheels so as to cause a change in the operation based on the driving environment information; a suppression unit that suppresses a limitation of protection control for protecting the electric motor by limiting the current supplied to the electric motor when the predetermined situation has occurred; A vehicle control device comprising:

2. a cutoff operation determination unit that determines whether or not there is a cutoff operation for cutting off the supply of the current in the predetermined situation; a situation change determination unit that determines whether or not a change has occurred to a stable situation in which the operation does not change from the predetermined situation when the cutoff operation is performed; The vehicle control device according to claim 1, further comprising: a permission unit that permits execution of a cutoff process corresponding to the cutoff operation when a change has occurred from the predetermined situation to the stable situation.

3. The vehicle control device according to claim 2, further comprising: a notification unit that notifies that execution of the cutoff process is impossible when the cutoff operation has been performed and a change has not occurred from the predetermined situation to the stable situation.

4. The vehicle control device according to claim 1, wherein the predetermined situation is a situation in which there is an obstacle capable of changing the operation by applying the disturbance to the wheels.

5. The vehicle control device according to claim 1, wherein the predetermined situation is a situation in which the vehicle travels on an uneven road.

6. The vehicle control device according to claim 1, wherein the suppression unit suppresses the limitation by temporarily interrupting execution of the protection control.

7. The vehicle control device according to claim 1, wherein the suppression unit suppresses the limitation such that, with respect to a decrease amount when the current is decreased in the protection control, the decrease amount is smaller than the decrease amount when the predetermined situation has not occurred.

8. The vehicle control device according to claim 1, wherein the suppression unit suppresses the limitation such that, with respect to a lower limit value when the current is decreased in the protection control, the lower limit value is larger than the lower limit value when the predetermined situation has not occurred.

9. The vehicle control device according to claim 1, wherein the situation determination unit determines that the predetermined situation has occurred when a deviation in vehicle height between the left and right wheels is greater than a preset left-right wheel deviation threshold value.

10. The vehicle control device according to claim 1, wherein the situation determination unit determines that the predetermined situation has occurred when the transfer mounted on the vehicle is set to the LOW range indicating low speed, or when the differential device mounted on the vehicle is set to the deflock indicating that it is locked.

11. The vehicle control device according to claim 1, wherein the situation determination unit determines that the predetermined situation has occurred when the magnitude of the current supplied to the electric motor for controlling the operation is greater than the magnitude of a preset upper limit value.

12. Based on the driving environment, when changing from the predetermined situation to a stable situation that does not cause a change in the operation, a return command unit that returns the restriction of the protection control suppressed by the suppression unit in the predetermined situation to the restriction of the protection control before being suppressed by the suppression unit in the predetermined situation. The vehicle control device according to claim 1.

13. The electric motor is The vehicle control device according to claim 1, which is provided in at least the steering system among a drive system that drives the wheels, a brake system that brakes the wheels, and a steering system that steers the wheels.

14. The steering system is An operating device having an operating member operated by a driver, A steering device having the electric motor and steering the wheels, A controller that realizes steering of the wheels according to the operation of the operating member by the steering device by controlling the current supplied to the electric motor. The vehicle control device according to claim 13, which is of a steer-by-wire type.

15. The steering system is An operating device having an operating member operated by a driver, A pair of steering devices that respectively steer the left and right wheels of the vehicle, A controller that realizes steering of each of the left and right wheels according to the operation of the operating member by each of the pair of steering devices by controlling the current supplied to each of the electric motors of the pair of steering devices. The vehicle control device according to claim 13, which is of a steer-by-wire type.

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