Vehicle control device, vehicle control method, and vehicle control program

Abstract

To provide a vehicle control device, a vehicle control method, and a vehicle control program that can transition to a lateral movement mode in a short time without unintended movement occurring. [Solution] The vehicle control device according to the embodiment is a vehicle control device that controls a motor for driving provided on each of a plurality of wheels, and has a controller. The controller includes a controller that controls the rotational speed of at least one of the motors to a target rotational speed until all of the plurality of wheels are simultaneously steered in the vehicle width direction when the vehicle's driving mode transitions to a lateral movement mode.

Description

Technical Field

[0001] The present invention relates to a vehicle control device, a vehicle control method, and a vehicle control program.

Background Art

[0002] Conventionally, a vehicle having a lateral movement mode in which the vehicle moves parallel in the vehicle width direction by steering the wheels of the vehicle 90 degrees in the vehicle width direction has been proposed (see, for example, Patent Document 1). Further, Patent Document 1 discloses a technique for preventing the vehicle from unintentionally moving due to its own weight along the slope when shifting to the lateral movement mode while the vehicle is stopped on a slope, by sequentially steering the wheels and applying brakes to the wheels that are not being steered.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art, since the wheels are steered sequentially, it takes time to complete the shift to the lateral movement mode. On the other hand, when multiple wheels are steered simultaneously, when the vehicle is stopped on a slope, all the wheel brakes are released for steering, so there is a risk that the vehicle may move unintentionally due to its own weight (roll down the slope).

[0005] The present invention has been made in view of the above, and an object thereof is to provide a vehicle control device, a vehicle control method, and a vehicle control program that can shift to the lateral movement mode in a short time without causing unintentional movement.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the vehicle control device according to the present invention is a vehicle control device that controls a motor for driving provided on each of a plurality of wheels, and has a controller. When the vehicle's driving mode transitions to a lateral movement mode, the controller performs rotational speed control to control at least one of the motors to a target rotational speed until all of the plurality of wheels are simultaneously steered in the vehicle width direction. [Effects of the Invention]

[0007] According to the present invention, by controlling the motor at a target rotational speed until all wheels have been turned, the actual rotational speed can be made close to the target rotational speed. Therefore, even when the vehicle is stopped on a slope, unintended movement due to its own weight can be suppressed. As a result, all multiple wheels can be turned simultaneously in the vehicle width direction, thus shortening the transition time to the lateral movement mode. In other words, according to the present invention, the transition to the lateral movement mode can be made in a short time without unintended movement occurring. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram showing an overview of the vehicle control method according to this embodiment. [Figure 2] Figure 2 is a block diagram showing an example of the configuration of a vehicle control system. [Figure 3] Figure 3 shows an example of torque control performed by the controller. [Figure 4] Figure 4 shows an example of sequential steering control. [Figure 5] Figure 5 shows an example of sequential steering control. [Figure 6] Figure 6 is a flowchart showing the processing procedure for mode switching performed by the vehicle control device. [Modes for carrying out the invention]

[0009] The vehicle control device, vehicle control method, and vehicle control program according to the embodiments will be described in detail below with reference to the attached drawings. However, the present invention is not limited to the embodiments described below.

[0010] First, an overview of the vehicle control method according to the embodiment will be described using Figure 1. Figure 1 is a diagram showing an overview of the vehicle control method according to the embodiment. The vehicle control method is executed by the vehicle control device 1. The vehicle control device 1 is an ECU (Electronic Control Unit) mounted on the vehicle C that performs various controls on the vehicle C.

[0011] Furthermore, the vehicle C shown in Figure 1 has multiple wheels 20 that serve as drive wheels. Hereafter, as shown in Figure 1, the wheels 20 may be referred to as "right front wheel 20FR," "left front wheel 20FL," "right rear wheel 20RR," and "left rear wheel 20RL."

[0012] Each wheel 20 is equipped with a motor (not shown), and an inverter 10 is connected to each motor. The motors are, for example, in-wheel motors built into the wheels 20. In the following description, as shown in Figure 1, the inverter 10 consists of inverter 10FR connected to the right front wheel 20FR, inverter 10FL connected to the left front wheel 20FL, inverter 10RR connected to the right rear wheel 20RR, and inverter 10RL connected to the left rear wheel 20RL. Each inverter 10 is controlled by the vehicle control device 1 to rotate the motor. Then, each wheel 20 is driven (rotates) by the rotation of the motor, causing the vehicle C to move.

[0013] Furthermore, as shown in Figure 1, the vehicle C in this disclosure has a longitudinal movement mode and a lateral movement mode. The longitudinal movement mode is a driving mode in which the direction of travel of the vehicle C is the vehicle length direction. Specifically, the longitudinal movement mode is a driving mode in which each wheel 20 is facing the vehicle length direction (a state in which the axis of rotation of the wheel 20 is perpendicular to the vehicle length direction). In this longitudinal movement mode, the driver can operate a steering wheel (not shown), causing each wheel 20 to steer according to the amount of steering input, thereby enabling the vehicle to turn right or left.

[0014] Next, the lateral movement mode is a driving mode in which the direction of travel of vehicle C is in the direction of the vehicle width. Specifically, the lateral movement mode is a driving mode in which each wheel 20 is facing in the direction of the vehicle width (the rotation axis of the wheel 20 is perpendicular to the direction of the vehicle width). In this lateral movement mode, steering is disabled, and the vehicle moves parallel in the direction of the vehicle width according to the amount of accelerator operation.

[0015] In this disclosure, when transitioning from vertical movement mode to horizontal movement mode, rotational speed control is performed to control the motors of each wheel 20 to a target rotational speed. This point will be explained with reference to Figure 1.

[0016] Specifically, first, the vehicle control device 1 receives a command from the driver to switch to the lateral movement mode while in the longitudinal movement mode. This command can be received, for example, by the driver using a button (not shown).

[0017] Next, when the vehicle control device 1 receives a switching instruction, if the vehicle C is stationary, it simultaneously steers each wheel 20 in the vehicle width direction. Figure 1 shows the state during mode switching from longitudinal movement mode to lateral movement mode, and each wheel 20 is steered counterclockwise in a top view. In the example shown in Figure 1, the right front wheel 20FR and the right rear wheel 20RR are steered counterclockwise so that they are positioned towards the front in the vehicle length direction, and the left front wheel 20FL and the left rear wheel 20RL are steered counterclockwise so that they are positioned towards the rear in the vehicle length direction. As a result, the vehicle C can steer all four wheels 20 while stationary due to the forward moment from the right front wheel 20FR and the right rear wheel 20RR and the backward moment from the left front wheel 20FL and the left rear wheel 20RL. Note that Figure 1 shows only one example; the right front wheel 20FR and the right rear wheel 20RR may be steered clockwise so that they are positioned towards the rear in the vehicle length direction, while the left front wheel 20FL and the left rear wheel 20RL may be steered clockwise so that they are positioned towards the front in the vehicle length direction. As shown in Figure 1, the vehicle control device 1 completes the transition to the lateral movement mode when the rotation axis of each wheel 20 is oriented perpendicular to the vehicle width direction.

[0018] In the present disclosure, during mode switching, the vehicle control device 1 performs rotational speed control to control the motors of each wheel 20 to the target rotational speed until the transition to the lateral movement mode is completed. Specifically, the vehicle control device 1 performs rotational speed control by feedback control or feedforward control so as to maintain the motors of each wheel 20 at the target rotational speed. Thereby, when the actual rotational speed of the motor is less than the target rotational speed, the vehicle control device 1 increases the driving torque (positive torque) in the motor to raise the actual rotational speed to the target rotational speed. On the other hand, when the actual rotational speed of the motor exceeds the target rotational speed, the vehicle control device 1 increases the braking torque (negative torque) in the motor to lower the actual rotational speed to the target rotational speed.

[0019] Thus, when the vehicle control device 1 transitions to the lateral movement mode, since all of the plurality of wheels 20 are steered in the vehicle width direction simultaneously, the transition time to the lateral movement mode can be reduced. Further, the vehicle control device 1 can control the actual rotational speed at a rotational speed close to the target rotational speed by performing rotational speed control on each motor until the steering of all of the plurality of wheels 20 is completed. Therefore, even in a situation where the rotational speed of the motor increases unintentionally due to a slope, by generating a braking torque and controlling the actual rotational speed at a rotational speed close to the target rotational speed, it is possible to suppress the vehicle C from moving unintentionally along the slope. That is, according to the vehicle control device 1, it is possible to transition to the lateral movement mode in a short time without causing unintentional movement.

[0020] Note that, in the above, an example in which a plurality of wheels 20 are steered simultaneously during the transition to the lateral movement mode has been shown. However, when the vehicle C is stopped on a steep slope, control for sequentially steering the plurality of wheels 20 may be performed. Details of this point will be described later with reference to FIGS. 4 and 5.

[0021] Further, in FIG. 1, an example in which rotational speed control is performed during the switching from the vertical movement mode to the lateral movement mode has been shown. However, rotational speed control may be similarly performed during the switching from the lateral movement mode to the vertical movement mode.

[0022] Next, an example of the configuration of the vehicle control device 1 according to the embodiment will be described using Figure 2. Figure 2 is a block diagram showing an example of the configuration of the vehicle control device 1. As shown in Figure 2, the vehicle control device 1 is connected to a switching operation unit 100, an accelerator sensor 200, a brake sensor 300, a G sensor 400, a steering control device 500, and an inverter 10.

[0023] The switching operation unit 100 is an operating component that receives user input to switch the driving mode. Specifically, the switching operation unit 100 is an operating component that switches between vertical movement mode and horizontal movement mode. The switching operation unit 100 is, for example, a physical switch or a display component such as a switch displayed on the screen of a navigation device.

[0024] The accelerator sensor 200 is a sensor that detects an operation signal corresponding to the amount of accelerator pedal operation performed by the user. The brake sensor 300 is a sensor that detects an operation signal corresponding to the amount of brake pedal operation performed by the user. The G sensor 400 is a sensor that detects the acceleration occurring in vehicle C.

[0025] The steering control device 500 is an ECU that controls the steering of the wheels 20 when switching driving modes. The steering control device 500 controls a plurality of steering actuators 510 connected to each wheel 20. The plurality of steering actuators 510 are actuators that steer each wheel. The steering control device 500 controls the plurality of steering actuators 510 by the control of the vehicle control device 1, which receives a mode switching instruction from the switching operation unit 100. Specifically, the steering control device 500 controls the steering actuators 510 by operating a drive source (for example, a motor) that drives the steering actuators 510. Note that the drive source that drives the steering actuators 510 is a separate motor from the motor for driving (the motor for the wheels 20).

[0026] Furthermore, as shown in Figure 2, the vehicle control device 1 comprises a controller 2 and a storage unit 3.

[0027] Controller 2 includes a microcomputer with a CPU (Central Processing Unit), ROM (Read Only Memory), RAM, and various circuits. Controller 2 executes the operation of the entire vehicle control device 1 by having the CPU execute a program stored in ROM, using RAM as a workspace. Controller 2 may be composed of hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), either partially or entirely.

[0028] The storage unit 3 is, for example, RAM (Random Access Memory) or data flash. Such a storage unit 3 can store information about various programs, etc. The vehicle control device 1 may also acquire the above-mentioned programs and various information via other computers or portable recording media connected by wired or wireless networks.

[0029] Controller 2 performs the process of switching the driving mode. Specifically, first, Controller 2 receives a driving mode switching instruction from the user via the switching operation unit 100. Specifically, Controller 2 receives an instruction to switch from vertical movement mode to horizontal movement mode, or from horizontal movement mode to vertical movement mode.

[0030] (Vertical movement mode → Horizontal movement mode) Here, we will specifically explain the process of switching from vertical movement mode to horizontal movement mode. Note that the process of switching from horizontal movement mode to vertical movement mode is the same as the process of switching from vertical movement mode to horizontal movement mode, so we will omit the explanation.

[0031] When controller 2 receives a switching instruction, it determines whether vehicle C is stationary or not. If vehicle C is not stationary (i.e., is moving), controller 2 notifies the driver to stop vehicle C. On the other hand, if vehicle C is stationary, controller 2 starts switching to lateral movement mode. In this way, controller 2 can avoid vehicle C unintentionally moving during the transition to lateral movement mode by starting the switch to lateral movement mode only when vehicle C is stationary.

[0032] When vehicle C is stopped, controller 2 disables operation via the accelerator pedal, sets the requested torque to zero, and sets the brake operation amount to zero (brake off).

[0033] Next, the controller 2 detects the tilt of vehicle C based on the detection results of the G sensor 400. Specifically, the controller 2 detects which direction (front, back, left, or right) vehicle C is tilted when parked, and also detects the angle of the tilt.

[0034] The controller 2 decides, based on the angle of inclination, whether to steer all four wheels 20 simultaneously (hereinafter referred to as four-wheel steering) or to steer the four wheels 20 sequentially (hereinafter referred to as sequential steering). Specifically, the controller 2 performs four-wheel steering if the angle of inclination is less than a threshold, and performs sequential steering if the angle of inclination is greater than or equal to the threshold. Details of sequential steering will be described later in Figures 4 and 5.

[0035] When performing four-wheel steering, the controller 2 instructs the steering control device 500 to start steering all four wheels 20 simultaneously. Upon receiving the instruction from the controller 2, the steering control device 500 controls the four steering actuators 510 to simultaneously steer all four wheels 20.

[0036] Furthermore, as soon as steering of the wheels 20 begins, the controller 2 performs rotational speed control to control all four motors of the wheels 20 at a target rotational speed. For example, the controller 2 performs rotational speed control at a target rotational speed that is below a threshold. This allows the controller 2 to perform rotational speed control at a low rotational speed, thus keeping the movement speed of the wheels 20 low during mode switching. The target rotational speed may be set to gradually increase over time, for example, as long as it is below a threshold, but it is preferable to set it at a constant rotational speed. In other words, the controller 2 performs rotational speed control to maintain a constant target rotational speed. This allows the controller 2 to perform rotational speed control at a constant rotational speed, thus keeping the movement speed of the wheels 20 constant during mode switching.

[0037] Furthermore, in rotational speed control, controller 2 calculates the deviation between the actual rotational speed of the motor and the target rotational speed, and determines the required torque based on the deviation. Here, we will specifically explain torque control in rotational speed control using Figure 3.

[0038] Figure 3 shows an example of torque control performed by controller 2. Figure 3 shows the change in output torque during vertical movement mode and the change in output torque during mode switching. The target torque T1 shown in Figure 3 is the torque value based on the target rotational speed when the accelerator pedal is depressed to a predetermined amount. The target torque T2 is the torque value based on the target rotational speed during rotational speed control during mode switching.

[0039] As shown in Figure 3, in the vertical movement mode, the controller 2 controls the output torque so that it reaches the target torque T1 in a short time. Specifically, in the initial timing when the difference between the output torque and the target torque T1 is large, the controller 2 increases the required torque to rapidly increase the output torque. Then, as the difference between the output torque and the target torque T1 decreases, the controller 2 controls the output torque to gradually approach the target torque T1 by decreasing the rate of increase of the required torque. In this way, in the vertical movement mode, control can be performed to bring the output torque closer to the target torque T1 in a short time.

[0040] On the other hand, during mode switching, controller 2 controls the vehicle C to maintain a low actual rotational speed to prevent it from unintentionally rolling downhill. Specifically, controller 2 reduces the target torque T2 by setting the target rotational speed below a threshold. Furthermore, since the objective of controller 2 during mode switching is to maintain the target rotational speed (not to reach the target rotational speed in a short time), it gradually increases the output torque. Specifically, controller 2 sets the required torque low so that the output torque increases by a fixed amount regardless of the difference between the output torque and the target torque T2. As a result, controller 2 can gradually increase the actual rotational speed toward the target rotational speed, making it less likely for the actual rotational speed to temporarily exceed the target rotational speed by increasing the actual rotational speed in a short time, as described above. In addition, by setting the required torque so that the output torque increases gradually, controller 2 can maintain the actual rotational speed at the target rotational speed with high precision by generating braking torque, even in situations where, for example, the rotational speed of vehicle C unintentionally increases due to a slope.

[0041] Next, the controller 2 detects that the steering of the wheel 20 by the steering control device 500 has been completed. Specifically, the controller 2 detects that the steering of the wheel 20 has been completed when the wheel 20 is facing in the direction of the vehicle width (the axis of rotation of the wheel 20 is perpendicular to the direction of the vehicle width). More specifically, the controller 2 detects that the wheel 20 has been steered 90 degrees in the direction of the vehicle width. For example, the controller 2 detects that the steering of the wheel 20 has been completed when the cumulative distance traveled by the wheel 20 (number of rotations) reaches a target value (the distance required for a 90-degree steering). Note that if the wheel 20 was steered by a predetermined angle at the start of mode switching (in the case of a steering state due to turning), the controller 2 sets the distance required to go from the predetermined angle to 90 degrees as the target value. Note that in addition to detecting steering completion from the rotation distance of the wheel 20, the controller 2 may also detect steering completion from the angle of steering. The steering angle can be detected, for example, by detecting it using a steering angle sensor (not shown) or by estimating it from the steering control amount of the steering control device 50.

[0042] When controller 2 detects that the steering of the wheels 20 is complete, it stops the rotation speed control and activates the brakes on all four wheels 20 to complete the transition to lateral movement mode. In other words, controller 2 completes the transition to lateral movement mode with the brakes applied to all four wheels 20.

[0043] Next, sequential steering control will be explained in detail using Figures 4 and 5. Figures 4 and 5 are diagrams illustrating examples of sequential steering control. Figure 4 shows an example of steering one wheel at a time, and Figure 5 shows an example of steering two wheels at a time.

[0044] As described above, when the tilt of vehicle C exceeds a threshold, controller 2 performs sequential steering as shown in Figure 4 or Figure 5. More specifically, when the tilt of vehicle C is between the first threshold and the second threshold, controller 2 performs sequential steering of two wheels at a time as shown in Figure 5, and when the tilt is above the second threshold, controller 2 performs sequential steering of one wheel at a time as shown in Figure 4. Furthermore, when the tilt of vehicle C is below the first threshold, controller 2 performs the four-wheel steering described above.

[0045] As shown in Figure 4, in sequential steering of one wheel at a time, the controller 2 selects any wheel 20 from the four wheels 20 to be steered. In the example shown in Figure 4, the controller 2 first selects the right front wheel 20FR as the target for steering. The controller 2 starts steering the right front wheel 20FR in a counterclockwise direction and controls the inverter 10FR to maintain the target rotational speed. In other words, the controller 2 steers the right front wheel 20FR to move forward in the vehicle length direction while controlling its rotational speed. The controller 2 also applies the brakes to the other three wheels besides the right front wheel 20FR.

[0046] Next, controller 2 selects the left front wheel 20FL as the target for steering. Controller 2 begins steering the left front wheel 20FL counterclockwise and controls the inverter 10FL to maintain the target rotational speed. In other words, controller 2 steers the left front wheel 20FL toward the rear in the vehicle length direction while controlling its rotational speed. Controller 2 also applies the brakes to the other three wheels besides the left front wheel 20FL.

[0047] Next, controller 2 selects the left rear wheel 20RL as the target for steering. Controller 2 begins steering the left rear wheel 20RL counterclockwise and controls the inverter 10RL to maintain the target rotational speed. In other words, controller 2 steers the left rear wheel 20RL toward the rear in the vehicle length direction while controlling its rotational speed. Controller 2 also applies the brakes to the other three wheels besides the left rear wheel 20RL.

[0048] Next, controller 2 selects the right rear wheel 20RR as the target for steering. Controller 2 begins steering the right rear wheel 20RR counterclockwise and controls inverter 10RR to maintain the target rotational speed. In other words, controller 2 steers the right rear wheel 20RR forward in the vehicle length direction while controlling its rotational speed. Controller 2 also applies the brakes to the other three wheels besides the right rear wheel 20RR.

[0049] Then, after the steering of the four wheels 20 is complete, controller 2 applies the brakes to the four wheels 20, completing the transition to lateral movement mode.

[0050] Note that the steering sequence shown in Figure 4 (right front wheel 20FR → left front wheel 20FL → left rear wheel 20RL → right rear wheel 20RR) is just one example, and steering can be performed in any order.

[0051] In this way, when the incline of vehicle C is steep (above the second threshold), controller 2 can steer one wheel at a time sequentially and apply the brakes to the other wheels 20 that are not being steered, thereby enabling a stable transition to lateral movement mode.

[0052] Next, in sequential steering of two wheels at a time, the controller 2 selects any two wheels 20 from the four wheels 20 to be steered. In the example shown in Figure 5, the controller 2 first selects the right front wheel 20FR and the left rear wheel 20RL to be steered. The controller 2 starts steering the right front wheel 20FR and the left rear wheel 20RL in a counterclockwise direction, and simultaneously controls the inverters 10FR and 10RL to maintain the target rotational speed. In other words, the controller 2 steers the right front wheel 20FR to the front in the vehicle length direction and the left rear wheel 20RL to the rear in the vehicle length direction while controlling the rotational speed of the right front wheel 20FR and the left rear wheel 20RL. The controller 2 also applies the brakes to the other two wheels besides the right front wheel 20FR and the left rear wheel 20RL.

[0053] Next, controller 2 selects the left front wheel 20FL and the right rear wheel 20RR as the wheels to be steered. Controller 2 begins to steer the left front wheel 20FL and the right rear wheel 20RR in a counterclockwise direction, and simultaneously controls inverters 10FL and 10RR to maintain the target rotational speed. In other words, controller 2 controls the rotational speed of the left front wheel 20FL and the right rear wheel 20RR, while steering the left front wheel 20FL to the rear in the vehicle length direction and the right rear wheel 20RR to the front in the vehicle length direction. Controller 2 also applies the brakes to the other two wheels besides the left front wheel 20FL and the right rear wheel 20RR.

[0054] Then, after the steering of the four wheels 20 is complete, controller 2 applies the brakes to the four wheels 20, completing the transition to lateral movement mode.

[0055] Thus, when the incline of vehicle C is not relatively steep (between the first threshold and the second threshold), controller 2 can steer two wheels at a time and apply the brakes to the other wheels 20 that are not being steered, thereby enabling a stable transition to lateral movement mode in a short time.

[0056] Furthermore, as shown in Figure 5, it is preferable that the combination of two wheels to be steered consists of two wheels 20 located diagonally opposite each other. This allows the brakes to be applied to the diagonally opposite wheels 20, thereby supporting the "front," "rear," "right," and "left" sides of the vehicle C with the brakes, and thus enabling stable steering. Specifically, when braking the left front wheel 20FL and the right rear wheel 20RR, the left front side ("left side" and "front") and the right rear side ("right side" and "rear") of the vehicle C can be supported.

[0057] Furthermore, the combination of two wheels that are subject to steering is not limited to two wheels 20 located diagonally opposite each other; the two front wheels and the two rear wheels may be paired together, or the two right wheels and the two left wheels may be paired together.

[0058] Next, the processing procedure for the mode switching process performed by the vehicle control device 1 will be explained using Figure 6. Figure 6 is a flowchart showing the processing procedure for the mode switching process performed by the vehicle control device 1.

[0059] As shown in Figure 6, the controller 2 first receives a switching instruction from the user to switch to the lateral movement mode via the switching operation unit 100 (step S101).

[0060] Next, when controller 2 receives the switching instruction, it disables control via the accelerator pedal (step S102), sets the requested torque to zero (step S103), and turns off control via the brake pedal (step S104). In other words, controller 2 prevents the vehicle from being controlled by the user's driving operations.

[0061] Next, the controller 2 detects the tilt of vehicle C and determines whether the tilt is below a threshold (step S105).

[0062] If the incline is below a threshold (step S105: Yes), controller 2 simultaneously starts steering all four wheels 20 in the vehicle width direction (step S106). Subsequently, controller 2 measures the actual rotational speed of the motors of the wheels 20 (step S107).

[0063] Next, controller 2 calculates the required torque from the difference between the target rotational speed and the actual rotational speed (step S108), and controls the motor based on the required torque (step S109).

[0064] Next, the controller 2 determines whether the cumulative distance traveled by the wheels 20 due to steering has reached the target value (step S110). Specifically, the controller 2 determines whether the wheels 20 have moved from the vehicle length direction to the vehicle width direction due to a 90-degree change in their orientation.

[0065] If the cumulative distance reaches the target value (step S110: Yes), controller 2 turns on the brakes on all four wheels 20 (step S111) and ends the process of switching to lateral movement mode. If the cumulative distance has not reached the target value (step S110: No), controller 2 returns to step S107.

[0066] Furthermore, in step S105, if the incline is greater than or equal to a threshold (step S105: No), the controller 2 initiates steering of any one of the four wheels 20 by rotational speed control and applies the brakes to the other three wheels (step S112).

[0067] Next, controller 2 measures the actual rotational speed of the motor of wheel 20 (step S113).

[0068] Next, controller 2 calculates the required torque from the difference between the target rotational speed and the actual rotational speed (step S114), and controls the motor based on the required torque (step S115).

[0069] Next, the controller 2 determines whether the cumulative distance traveled by the wheels 20 due to steering has reached the target value (step S116). Specifically, the controller 2 determines whether the wheels 20 have moved from the vehicle length direction to the vehicle width direction due to a 90-degree change in their orientation.

[0070] When the cumulative distance reaches the target value (step S116: Yes), the controller 2 determines whether or not all four wheels 20 have been turned (step S117).

[0071] If the steering of all four wheels 20 is complete (step S117: Yes), the controller 2 proceeds to step S111. On the other hand, if the steering of all four wheels 20 is not complete (step S117: No), the controller 2 proceeds to step S112 and processes the wheels 20 that have not been steered.

[0072] Furthermore, in step S116, if the cumulative distance has not reached the target value (step S116: No), the controller 2 returns to step S113.

[0073] As described above, the vehicle control device 1 according to this embodiment controls the motors for driving provided on each of the multiple wheels 20. When the vehicle's driving mode transitions to a lateral movement mode, the controller 2 performs rotational speed control to control at least one of the motors to a target rotational speed until all of the multiple wheels 20 are simultaneously steered in the vehicle width direction.

[0074] According to this disclosure, when transitioning to lateral movement mode, all of the wheels 20 are steered simultaneously in the vehicle width direction, thus shortening the transition time to lateral movement mode. Furthermore, by controlling the rotational speed of the motors until all wheels 20 have completed steering, the actual rotational speed can be brought close to the target rotational speed. Therefore, even when vehicle C is stopped on a slope, unintended movement of vehicle C due to its own weight can be suppressed. In other words, according to this disclosure, it is possible to transition to lateral movement mode in a short time without unintended movement occurring.

[0075] In the embodiment described above, an example was shown in which the rotational speed of all wheels 20 is controlled during the transition to the lateral movement mode (while the wheels 20 are being steered), but it is not necessary to control the rotational speed of all wheels 20. Specifically, the vehicle control device 1 may control the rotational speed of at least one wheel 20. For example, the vehicle control device 1 changes the number of wheels 20 that are subject to rotational speed control depending on the inclination state of the parked vehicle. Specifically, the vehicle control device 1 increases the number of wheels 20 that are subject to rotational speed control as the inclination increases. In this case, the vehicle control device 1 uses the threshold in step S105 of Figure 6 as the first threshold, and when the inclination is less than the first threshold, it determines in stages whether it is below one of several thresholds lower than the first threshold, and determines the number of wheels 20 to be controlled based on which of the multiple thresholds it is above. In other words, the vehicle control device 1 performs threshold determinations in stages, such as targeting all four wheels for rotational speed control when the incline is below the first threshold but above the second threshold, and targeting all three wheels for rotational speed control when the incline is below the second threshold but above the third threshold. The thresholds are set in the order of lowest value: first threshold, second threshold, and third threshold. Furthermore, when targeting rotational speed control for fewer than four wheels, the decision of which wheels 20 to target is the same as the concept of which wheels 20 to steer while applying the brakes to them, as explained in Figures 4 and 5.

[0076] Furthermore, in the above-described embodiment, during the transition to the lateral movement mode (while the wheels 20 are being steered), rotational speed control is basically performed with a constant target rotational speed (a low rotational speed at which the wheels are almost not rotating) as the target value. However, the target rotational speed does not necessarily have to be exactly the same throughout the transition period. For example, the vehicle control device 1 may vary the target rotational speed during the period, as long as it remains within the range of low rotational speeds at which the wheels 20 are almost not rotating.

[0077] Furthermore, although the above-described embodiment uses the example of a vehicle with four wheels 20, it may also be a vehicle with fewer wheels than four, such as three wheels, or more wheels than four, such as six wheels.

[0078] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0079] 1. Vehicle control system 2 Controllers 3 Storage section 10 Inverters 20 wheels 20FL left front wheel 20FR right front wheel 20RL left rear wheel 20RR Right Rear Wheel 100 Switching operation unit 200 Accelerator Sensor 300 Brake Sensor 400 G sensor 500 Steering control device 510 Steering Actuator C Vehicle

Claims

1. A vehicle control device that controls a motor for driving, provided on each of the multiple wheels, When the vehicle's driving mode transitions to a lateral movement mode, the system includes a controller that controls the rotational speed of at least one of the motors to a target rotational speed until all of the multiple wheels are simultaneously steered in the vehicle width direction. Vehicle control device.

2. The aforementioned controller, The motor is controlled to a target rotational speed that is below a threshold. The vehicle control device according to claim 1.

3. The aforementioned controller, The motor is subjected to rotational speed control to maintain it at a constant rotational speed, which is the target rotational speed. The vehicle control device according to claim 1.

4. The aforementioned controller, If the vehicle's inclination is below a threshold, all of the wheels are steered simultaneously in the vehicle width direction; if it is above the threshold, the wheels are steered sequentially in the vehicle width direction. The vehicle control device according to claim 1.

5. The vehicle has four wheels, The aforementioned controller, If the inclination of the vehicle is greater than or equal to a first threshold but less than a second threshold, the four wheels are steered two at a time in the vehicle width direction; if it is greater than or equal to the second threshold, the four wheels are steered one at a time in the vehicle width direction. The vehicle control device according to claim 4.

6. The aforementioned controller, When the vehicle is stationary, the driving mode is switched to the lateral movement mode. The vehicle control device according to claim 1.

7. A vehicle control method performed by a vehicle control device that controls a motor for driving provided on each of the multiple wheels, When the vehicle's driving mode transitions to a lateral movement mode, rotational speed control is performed to control at least one of the motors to a target rotational speed until all of the multiple wheels are simultaneously steered in the vehicle width direction. Vehicle control method.

8. A vehicle control program executed by a vehicle control device that controls the motors for driving, which are provided on each of the multiple wheels, When the vehicle's driving mode transitions to a lateral movement mode, rotational speed control is performed to control at least one of the motors to a target rotational speed until all of the multiple wheels are simultaneously steered in the vehicle width direction. Vehicle control program.

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