Vehicle control device

Abstract

To be able to determine whether a wheel is floating from a road surface or not, for each wheel promptly.SOLUTION: A vehicle control device is provided with: electric motors 221 and 61 that turn or drive a wheel independently and controllers 3A-7D that consecutively supply control currents to the electric motors 221 and 61 in order to hold a turning angle of the wheel or hold driving force of the wheel, at least during linearly travelling of a vehicle. The controllers 3A-7D comprise: current obtaining parts 31 and 71 that obtain current values of actual or target control currents that are supplied to the electric motors 221 and 61; variation calculating parts 32 and 72 that calculate variations Iv per unit time of the current values; and state determining parts 33 and 73 that determine whether the wheel is floating from a road surface or not, on the basis of the variations Iv.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Techniques for determining whether a wheel is lifted have been developed in the past. For example, Japanese Patent Application Laid-Open No. 2009-269594 discloses a technique for determining whether a wheel is lifted based on the detection results of three lateral sway detectors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-269594 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above technology can only estimate wheel lift-up after the vehicle experiences lateral sway, leaving room for improvement in terms of early detection of wheel lift-up. Since lateral sway in the vehicle's sprung mass occurs some time after the wheel lift-up occurs, it takes time to detect the wheel lift-up after the wheel actually lifts up. Furthermore, the above technology cannot determine whether or not each wheel is lifted up. By quickly grasping the state of each wheel in response to changes in the state of each wheel, it becomes possible to set the distribution of tire forces (e.g., longitudinal force and lateral force) among multiple wheels in a more situation-appropriate manner.

[0005] An object of the present invention is to provide a vehicle control device that can determine, for each wheel, whether or not the wheel is lifted off the road surface at an early stage. [Means for solving the problem]

[0006] The vehicle control device of the present invention is a vehicle control device comprising an electric motor that steers or drives each wheel independently, and a controller that continuously supplies a control current to the electric motor to maintain the steering angle of the wheel or to maintain the driving force of the wheel, at least while the vehicle is traveling straight, wherein the controller comprises a current acquisition unit that acquires the current value of the actual or target control current supplied to the electric motor, a change amount calculation unit that calculates the change amount per unit time of the current value, and a state determination unit that determines whether the wheel is lifted from the road surface based on the change amount. [Effects of the Invention]

[0007] According to the present invention, the controller continues to supply a control current (control current > 0) to the electric motor at least while the vehicle is traveling straight. If the electric motor is a steering motor that steers each wheel independently, a control current is continuously supplied to the electric motor while the vehicle is traveling straight, maintaining the steering angle at a predetermined toe angle (for example, a predetermined toe-in amount). Furthermore, if the electric motor is a drive motor that applies driving force to the wheels, a control current is continuously supplied to the electric motor while the vehicle is traveling forward, maintaining the driving force for traveling straight.

[0008] When a wheel is in contact with the road surface, a certain amount of force is required to steer or drive the wheel. In other words, when a wheel is not lifted up, a certain amount of control current is required to maintain the target steering angle or the target rotational speed (target rotational speed). On the other hand, when a wheel is lifted up, no force or resistance occurs between the wheel and the road surface, and the force required to steer or drive the wheel is relatively small. Therefore, when a state transition occurs between a state in which the wheel is in contact with the road surface and a state in which the wheel is lifted up while the vehicle is traveling, the amount of change per unit time in the current value of the control current increases rapidly. According to the present invention, whether or not a wheel is lifted up from the road surface (hereinafter also referred to as a "lifted state") is determined based on this amount of change. In other words, the presence or absence of a lifted state of a wheel can be determined at an early timing, i.e., before the behavior of the vehicle body changes. Furthermore, according to the present invention, the presence or absence of a lifted state can be determined for each wheel provided with an electric motor. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram of a vehicle control device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view of the right front wheel of the present embodiment. [Figure 3] 10A and 10B are conceptual diagrams for explaining the floating state determination process of the present embodiment. [Figure 4] 10 is a flowchart illustrating a floating state determination process according to the present embodiment. [Figure 5] FIG. 2 is a configuration diagram of another example of the vehicle control device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, as a mode for carrying out the present invention, a vehicle control device 1 which is one embodiment of the present invention will be described in detail with reference to the drawings. In addition to the following embodiment, the present invention can be carried out in various forms with various changes and improvements based on the knowledge of those skilled in the art.

[0011] Vehicle control device 1 of this embodiment is equipped with a single wheel independent steering system 101 that steers wheels independently (left and right independently), and a single wheel independent drive system 102 that drives wheels independently (left and right independently). Specifically, as shown in Fig. 1, vehicle control device 1 is equipped with a left steering device 2A, a right steering device 2B, a left steering controller 3A, a right steering controller 3B, an operation device 4, a reaction force controller 5, a left drive device 6A, a right drive device 6B, a left drive controller 7A, and a right drive controller 7B.

[0012] Communication within the vehicle is carried out using a CAN (car area network or controllable area network) 100. In the drawings, some communication lines are not shown. In this embodiment, the steered wheels are front wheels 11, 12. The left steering device 2A is a device that steers the left front wheel 11. The right steering device 2B is a device that steers the right front wheel 12 independently of the left steering device 2A. Because the left steering device 2A and the right steering device 2B have the same configuration, the configuration of the right steering device 2B will be described and a description of the configuration of the left steering device 2A will be omitted.

[0013] (Single wheel independent steering system) As shown in Fig. 2, the right steering device 2B includes a steering knuckle 21, a steering actuator 22, and a tie rod 23. The steering knuckle 21 is a member that rotatably holds the right front wheel 12. The steering knuckle 21 also functions as a housing for an in-wheel motor unit 6, which will be described later.

[0014] Steering actuator 22 is installed at a location on the base end side of lower arm 91. Steering actuator 22 includes a steering motor 221, a reducer 222, an actuator arm 223, and a rotation angle sensor 224. Steering motor 221 is an electric motor serving as a drive source. Steering motor 221 is, for example, a brushless DC motor.

[0015] Reducer 222 is a gear device that reduces the rotation of steering motor 221. Actuator arm 223 is an arm member that rotates by the rotation of steering motor 221 via reducer 222. Actuator arm 223 functions as a pitman arm. Tie rod 23 is a member that connects knuckle arm 211 provided on steering knuckle 21 and actuator arm 223 of steering actuator 22. One end of tie rod 23 is connected to actuator arm 223 via ball joint 231, and the other end of tie rod 23 is connected to knuckle arm 211 via ball joint 232.

[0016] Rotation angle sensor 224 detects the rotation angle of steering motor 221. There is a specific relationship between the rotation angle of steering motor 221 and the steering angle of right front wheel 12. Therefore, each controller can calculate the steering angle of the wheel corresponding to steering motor 221 based on the rotation angle of steering motor 221. The detection of the steering angle may be by rotation angle sensor 224 or by another steering angle sensor. Rotation angle sensor 224 of left steering device 2A corresponds to a left steering angle sensor that detects the steering angle of left front wheel 11, and rotation angle sensor 224 of right steering device 2B corresponds to a right steering angle sensor that detects the steering angle of right front wheel 12.

[0017] The left steering controller 3A and the right steering controller 3B (hereinafter also referred to as "steering controllers 3A, 3B") are each an electronic control unit (ECU) equipped with one or more processors and one or more memories. Each of the steering controllers 3A, 3B acquires detection results from various sensors.

[0018] Left steering controller 3A controls left steering device 2A based on a steering request (for example, the detection result of steering sensor 42 described below or a command value from an autonomous driving ECU). Right steering controller 3B controls right steering device 2B based on the steering request. For example, in the case of manual driving, each of steering controllers 3A, 3B calculates a target steering angle based on the detection result of steering sensor 42 and the detection result of rotation angle sensor 224, and calculates a target control current based on the target steering angle.

[0019] Each steering controller 3A, 3B supplies a control current to the steering motor 221 of the corresponding steering device (left steering device 2A or right steering device 2B) based on the target control current. Each steering controller 3A, 3B is provided with a current sensor 30 that detects the actual current value (hereinafter also referred to as the "actual current value") supplied to the steering motor 221.

[0020] The operation device 4 has a general structure in a steer-by-wire steering system. As shown in Fig. 1, the operation device 4 includes a steering wheel 41, a steering sensor 42, and a reaction force applying device 43. The steering wheel 41 is an operation member that is operated by the driver to steer the vehicle.

[0021] The steering sensor 42 is a sensor that detects the operation angle, which is the rotation angle of the steering wheel 41, as the operation position or operation amount of the steering wheel 41. For example, if the position of the steering wheel 41 when the vehicle is traveling straight is set to a neutral position, the rotation angle in each of the left and right directions from the neutral position is the operation angle of the steering wheel 41.

[0022] The reaction force application device 43 is a device that applies a reaction force (a reaction force against an operation) to the steering wheel 41. The reaction force application device 43 includes a reaction force motor 431, which is an electric motor serving as a power source, a reducer 432 for transmitting the force of the reaction force motor 431 to the steering wheel 41, and an operation torque sensor 433. The operation torque sensor 433 detects an operation torque as an operation force applied to the steering wheel 41 by the driver based on the amount of twist of a torsion bar (not shown) incorporated in the steering shaft. The steering sensor 42 and / or the operation torque sensor 433 can be considered operation amount sensors that detect the amount of operation of the steering wheel 41 (a value related to the operation). In this embodiment, for the sake of explanation, the detection result of the steering sensor 42 is taken as the amount of operation of the steering wheel 41.

[0023] The reaction force controller 5 is an electronic control unit (ECU) equipped with one or more processors and one or more memories. The reaction force controller 5 calculates a target reaction force based on the detection result of the steering sensor 42 and vehicle speed information. The reaction force controller 5 controls the reaction force motor 431 based on the target reaction force. The vehicle speed can be calculated based on the detection result of wheel speed sensors (not shown) of each of the wheels 11 to 14, for example.

[0024] The suspension geometry of this embodiment is configured so that the steering angle of each of front wheels 11, 12 is in a predetermined toe-in state when the vehicle weight is applied to front wheels 11, 12, which are the steered wheels (for example, when there is no bounding or rebounding and the ignition is off). Therefore, each of steering controllers 3A, 3B continuously supplies a control current to steering motor 221 in order to maintain the steering angle of control target wheels 11, 12, at least while the vehicle is traveling straight. In this embodiment, each of steering controllers 3A, 3B continuously supplies a control current to steering motor 221 in order to maintain a predetermined toe-in state against a moment acting in the toe-out direction, at least while the vehicle is traveling straight.

[0025] (Single-wheel independent drive system) The left drive unit 6A and the right drive unit 6B (hereinafter also referred to as "drive units 6A, 6B") are each composed of an in-wheel motor unit 6. That is, the vehicle is equipped with an in-wheel motor unit 6 on each of the front wheels 11, 12, which are steered wheels, as a drive unit. As will be described later, each of the rear wheels 13, 14 is also equipped with an in-wheel motor unit 6 as a drive unit.

[0026] The in-wheel motor unit 6 includes a steering knuckle 21 that functions as a housing, a drive motor 61, a reducer 62, and an axle hub (not shown). The drive motor 61 is an electric motor that independently drives each wheel to be controlled. The drive motor 61 is, for example, a brushless DC motor.

[0027] The drive motors 61 are built into the steering knuckles 21. Each drive motor 61 is provided with a current sensor 70 that detects the current value of the control current and a rotation angle sensor (not shown) that detects the rotation angle of the motor. The reducer 62 is a gear device that reduces the rotation speed of the drive motor 61. The axle hub is attached to the wheel of the vehicle. The in-wheel motor unit 6 is disposed inside the rim of the wheel of the vehicle.

[0028] The left drive controller 7A and the right drive controller 7B (hereinafter also referred to as "drive controllers 7A, 7B") are each an electronic control unit (ECU) equipped with one or more processors and one or more memories. The drive controllers 7A, 7B are connected to each other via a CAN 100 so that they can communicate with each other.

[0029] The left drive controller 7A sets a control target value, such as a target rotation speed (target rotational speed), for the drive motor 61 of the left drive unit 6A based on a drive request (for example, the amount of accelerator pedal operation or a command value from the autonomous driving ECU) and the detection results of a rotation angle sensor. Similarly, the right drive controller 7B sets a control target value, such as a target rotation speed (target rotational speed), for the drive motor 61 of the right drive unit 6B based on a drive request and the detection results of a rotation angle sensor.

[0030] Each drive controller 7A, 7B sets a target control current based on the control target value of the drive motor 61, and supplies a control current corresponding to the target control current to the drive motor 61. Each drive controller 7A, 7B continuously supplies a control current to the drive motor 61 in order to maintain the drive force of the wheel to be controlled, at least while the vehicle is traveling straight.

[0031] In this embodiment, a single-wheel independent drive system 102 is also provided for the rear wheels 13, 14. That is, a left drive unit 6C similar to the left drive unit 6A and a left drive controller 7C similar to the left drive controller 7A are provided for the left rear wheel 13, and a right drive unit 6D similar to the right drive unit 6B and a right drive controller 7D similar to the right drive controller 7B are provided for the right rear wheel 14.

[0032] (Floating state determination process) The vehicle control device 1 executes a lifted state determination process for determining whether the wheels are lifted from the road surface. In the present embodiment, as an example, the lifted state determination process is executed by the single wheel independent steering system 101 for the front wheels 11 and 12, and by the single wheel independent drive system 102 for the rear wheels 13 and 14.

[0033] (front wheel) Each of the steering controllers 3A, 3B executes current acquisition processing, change amount calculation processing, and state determination processing in relation to the processing for determining the floating state of the front wheels 11, 12. In other words, each of the steering controllers 3A, 3B is equipped with a current acquisition section 31, a change amount calculation section 32, and a state determination section 33 as its functions.

[0034] Current acquisition section 31 acquires information on the current value of the actual or target control current supplied to steering motor 221. The actual current value of steering motor 221 can be acquired based on the detection result of current sensor 30. The current value of the target control current is calculated by each of steering controllers 3A, 3B. Current acquisition section 31 of this embodiment acquires the actual current value as the current value to be used in the floating state determination process.

[0035] The change amount calculation unit 32 calculates the change amount Iv per unit time of the actual current value. In other words, the change amount calculation unit 32 calculates the time derivative (Δi / Δt) of the control current as the change amount Iv. The time derivative of the control current can also be said to be the gradient of the change in the current value of the control current over time.

[0036] State determination unit 33 determines whether or not the control target wheel, which is the wheel (left front wheel 11 or right front wheel 12) to be steered by steering motor 221, is lifted off the road surface, based on calculated change amount Iv. For example, as shown in Fig. 3, if the absolute value of change amount Iv exceeds a predetermined threshold value Th1, state determination unit 33 determines that the state of the control target wheel has switched between a state in which the wheel is in contact with the road surface (hereinafter also referred to as a "ground contact state") and a state in which the wheel is lifted off the road surface (lifted state).

[0037] When the vehicle is traveling straight, each steering controller 3A, 3B supplies a predetermined control current to steering motor 221 in order to maintain corresponding front wheels 11, 12 in a predetermined toe-in state (target steering angle when traveling straight). Wheels 11, 12 in a toe-in state each generate a moment in the toe-out direction while the vehicle is traveling straight. For this reason, each steering controller 3A, 3B needs to continuously supply a control current as a maintaining current to steering motor 221 while the vehicle is traveling straight, in order to maintain the predetermined toe-in state. When the vehicle is turning, as when traveling straight, a control current necessary to maintain the target steering angle is continuously supplied to each steering motor 221.

[0038] When the wheels change from a grounded state to a lifted state, the moment disappears, and the current value required to maintain a predetermined toe-in amount decreases rapidly. Therefore, in this case, the corresponding steering controllers 3A and 3B reduce the control current because the toe-in amount of the wheels would be greater than the target value with the same control current. Conversely, when the wheels change from a grounded state to a lifted state, the moment occurs, and the current value required to maintain a predetermined toe-in amount increases rapidly. Therefore, in this case, the corresponding steering controllers 3A and 3B increase the control current. The torque of steering motor 221 depends on the lateral force (cornering coefficient × ground load × tire slip angle) and is therefore proportional to the ground load. Because the ground load differs significantly between a grounded state and a lifted state, the force required by steering motor 221 also changes with the change in state. Each steering controller 3A and 3B monitors this change in the control current over time to determine the state of the wheels. By monitoring the amount of change Iv, each steering controller 3A and 3B can determine the moment the wheels lift off or touch the ground.

[0039] For example, if the ignition (key switch) is turned on and the vehicle moves straight ahead without the floating state determination process having been performed even once, each steering controller 3A, 3B assumes that each front wheel 11, 12 is in a ground contact state, attempts to maintain the steered wheel to be controlled at a predetermined toe-in amount, and supplies a control current corresponding to the target steering angle to steering motor 221. If the amount of change Iv exceeds threshold value Th1, state determination unit 33 determines that the wheel to be controlled has changed from a ground contact state to a floating state. In subsequent determinations, the result of the previous determination is reflected.

[0040] For example, if only the left front wheel 11 changes to a lifted state, only the left front wheel 11 is steered with a small force, so the left steering controller 3A suddenly reduces the current value of the control current that was output assuming a grounded state. If the lifted state continues thereafter, the control current is maintained at a small value. When the left steering controller 3A detects a sudden change in the control current, it determines that the left front wheel 11 has changed to a lifted state. When the left steering controller 3A next detects a change Iv that exceeds threshold Th1, it determines that the left front wheel 11 has switched from a lifted state to a grounded state. Note that if the right steering controller 3B does not detect a change Iv that exceeds threshold Th1, it determines that the right front wheel 12 has not changed from a grounded state. Each steering controller 3A, 3B executes the lifted state determination process as long as the control current is continuously supplied to the steering motor 221, even when the vehicle is turning.

[0041] Furthermore, state determination unit 33 may determine the state of the control-target wheel taking into account the direction of change in the current value, i.e., whether the amount of change Iv is positive or negative. The amount of change Iv can be thought of as, for example, the current current value minus the current value from a unit time ago, and can be a positive or negative value. As shown in Figure 3, when the wheel changes from a ground-contact state to a lifted state, the force required for steering motor 221 decreases, and so the control current changes in a decreasing direction. In other words, state determination unit 33 can determine that the control-target wheel has entered a lifted state when the absolute value of amount of change Iv exceeds threshold value Th1 and the amount of change Iv is a negative value.

[0042] Conversely, when the wheel changes from a lifted state to a grounded state, the force required for steering motor 221 increases, and so the control current changes in an increasing direction. In other words, state determination unit 33 can determine that the control-target wheel has entered a grounded state when the absolute value of change amount Iv exceeds threshold value Th1 and the change amount Iv is a positive value. In this way, state determination unit 33 may determine whether the control-target wheel is in a lifted state or not based on the absolute value of change amount Iv and whether change amount Iv is positive or negative.

[0043] (rear wheel) The floating state determination process for the rear wheels 13, 14 is executed by each drive controller 7C, 7D. Each drive controller 7C, 7D functionally comprises a current acquisition unit 71 corresponding to the current acquisition unit 31, a change amount calculation unit 72 corresponding to the change amount calculation unit 32, and a state determination unit 73 corresponding to the state determination unit 33. The current acquisition unit 71 acquires information on the current value of the actual or target control current supplied to the drive motor 61. The actual current value of the drive motor 61 can be acquired based on the detection result of the current sensor 70. The current value of the target control current is calculated by each drive controller 7C, 7D. In this embodiment, the current acquisition unit 71 acquires the actual current value as the current value used in the floating state determination process.

[0044] Similar to the change amount calculation unit 32, the change amount calculation unit 72 calculates the change amount Iv per unit time of the actual current value. The state determination unit 73 determines whether the control target wheel, which is the wheel (left rear wheel 13 or right rear wheel 14) to be driven by the drive motor 61, is in a lifted state from the road surface based on the calculated change amount Iv. If the absolute value of the change amount Iv exceeds a predetermined threshold value Th2, the state determination unit 73 determines that the state of the control target wheel has switched between a ground contact state and a lifted state (see FIG. 3).

[0045] When the vehicle is traveling (straight or turning), each drive controller 7A, 7B, 7C, 7D continuously supplies a predetermined control current to the drive motor 61 to apply a predetermined torque to the corresponding wheel 11-14. When a wheel goes from a grounded state to a lifted state, road resistance disappears, and the current value required for the drive motor 61 to maintain the target rotation speed suddenly decreases. Therefore, in this case, the corresponding drive controller 7A-7D reduces the control current because the rotation speed of the drive motor 61 would be higher than the target rotation speed if the control current was left unchanged.

[0046] Conversely, when a wheel changes from a lifted state to a grounded state, road resistance occurs, and the current value required to maintain the target rotation speed increases rapidly. Therefore, in this case, the corresponding drive controllers 7A to 7D increase their control current. The torque of the drive motor 61 depends on the rolling resistance (resistance coefficient × ground load) and is therefore proportional to the ground load. Because the ground load differs significantly between a lifted state and a grounded state, the force required by the drive motor 61 also changes with the change in state. Each drive controller 7C, 7D monitors such temporal changes in the control current and determines the state of the wheel. Note that each drive controller 7A, 7B may also determine whether the corresponding front wheels 11, 12 are lifted based on the amount of change Iv in the control current. Furthermore, each drive controller 7A to 7D may determine whether the wheel to be controlled is lifted from the road surface based on the absolute value of the amount of change Iv and whether the amount of change Iv is positive or negative. Each drive controller 7A to 7D can execute a lifted state determination process, similar to each steering controller 3A, 3B.

[0047] The thresholds Th1 and Th2 are set by tests and simulations so as to be able to distinguish between road disturbances and changes in the contact state. Furthermore, the thresholds Th1 and Th2 are set to values ​​greater than the maximum expected change Iv of the control current (the expected maximum change) in control based on the intention of the driver or the autonomous driving ECU, for example.

[0048] (flowchart) An example of the flow of the lifted state determination process will be described with reference to Fig. 4. Each of the controllers 3A, 3B, 7C, and 7D (hereinafter also referred to as "each of the controllers 3A to 7D") sets the stored previous state (ground contact state or lifted state) of the wheel to be controlled as the current state (S1). If there is no previous information, each of the controllers 3A to 7D sets the state of the wheel to be controlled to the ground contact state.

[0049] Each controller 3A to 7D acquires the current value of the control current from the corresponding current sensor 30, 70 (S2). Each controller 3A to 7D calculates the amount of change Iv per unit time of the control current = (Δi / Δt) (S3). Each controller 3A to 7D determines whether the absolute value of the amount of change Iv exceeds the corresponding threshold value Th (threshold value Th1 or threshold value Th2) (S4). If the absolute value of the amount of change Iv is equal to or less than the threshold value Th (S4: No), the corresponding controller 3A to 7D determines that there is no change in the state of the wheel to be controlled (S5).

[0050] If the absolute value of the change amount Iv exceeds the threshold value Th (S4: Yes), the corresponding controller 3A to 7D determines whether the previous (current in the setting) state of the controlled wheel was in a ground contact state (S6). If the previous state of the controlled wheel was in a ground contact state (S6: Yes), the corresponding controller 3A to 7D changes the state of the controlled wheel to a lifted state (S7). If the previous state of the controlled wheel was in a lifted state (S6: No), the corresponding controller 3A to 7D changes the state of the controlled wheel to a lifted state (S8).

[0051] According to this embodiment, when a state change occurs between a state in which the wheel is in contact with the road surface and a state in which the wheel is lifted off the road surface while the vehicle is traveling, the change amount Iv per unit time of the current value of the control current increases. According to this embodiment, whether or not the wheel is lifted off the road surface is determined based on this change amount Iv. In other words, the presence or absence of the wheel lifted off the road surface can be determined at an early timing, before the behavior of the vehicle body changes. Furthermore, according to this embodiment, the presence or absence of the wheel lifted off the road surface can be determined for each wheel provided with an electric motor. This enables appropriate tire force distribution (e.g., longitudinal force and lateral force) according to the state. For example, optimal distribution can be achieved by setting a constraint such as not distributing tire force to a wheel in a lifted state. According to this embodiment, it is possible to estimate a momentary wheel lifted off the road surface and a momentary wheel contact with the ground. According to this embodiment, it is possible to estimate the moment (e.g., time) when the wheel lifted off the road surface and the moment (e.g., time) when the wheel contacted the ground surface from the momentary change in the control current.

[0052] Furthermore, by using the information on whether the amount of change Iv is positive or negative in the floating state determination process, it is possible to more accurately determine whether the state of the wheel to be controlled is floating. Each of the controllers 3A to 7D can determine the state depending on whether the amount of change Iv is positive or negative, for example, rather than switching from the previous state.

[0053] (others) The present invention is not limited to the above-described embodiment. For example, as shown in Fig. 5, left rear wheel 13 may be provided with a left steering device 2C and a left steering controller 3C, similar to left front wheel 11, and right rear wheel 14 may be provided with a right steering device 2D and a right steering controller 3D, similar to right front wheel 12. In other words, a single-wheel independent steering system 101 (which may also be called a single-wheel independent 4WS) may be applied to all four wheels. In this case, the steering controllers 3C and 3D may perform the lift-off state determination process for rear wheels 13 and 14.

[0054] Furthermore, in the example of this embodiment, the lift-off state determination process for each of wheels 11-14 may be performed by drive controllers 7A, 7B, 7C, and 7D corresponding to each of wheels 11-14. In this manner, when a steering motor 221 and a drive motor 61 are provided for each of wheels 11-14, the state of the wheel to be controlled may be determined based on the amount of change Iv in the control current of at least one of steering motor 221 and drive motor 61. The lift-off state determination process can be performed for each of the wheels provided with at least one of steering motor 221 and drive motor 61. Therefore, the vehicle may have, for example, a single-wheel independent 4WS steering system, and the drive system may use a drive shaft or the like provided on the vehicle body rather than a wheel. In this case, the state of each wheel is determined based on the amount of change Iv in the control current of each of steering motors 221. Alternatively, each of wheels may be provided with an in-wheel motor unit 6, and the steering system may use a steering rod such as a rack bar. In this case, the state of each wheel is determined based on the amount of change Iv in the control current of each of drive motors 61. In this way, the present invention can also be applied to a vehicle equipped with only the single wheel independent steering system 101 or only the single wheel independent drive system 102. The functions of a current acquisition unit, a change amount calculation unit, and a state determination unit can be added to each steering controller and each drive controller as appropriate.

[0055] The drive motor 61 may be one that exerts a regenerative braking force. The continuous supply of control current by the steering controllers 3A, 3B may be due to, for example, jack-up torque. The present invention is also applicable to autonomous vehicles. The road surface includes paved roads, unpaved roads, and the ground.

[0056] Furthermore, the current acquisition units 31, 71 may acquire information on the target control current (target current value) calculated by their own controllers 3A to 7D instead of the detection results of the current sensors 30, 70. In this case, the change amount calculation units 32, 72 calculate the amount of change in the target control current. The state determination units 33, 73 determine whether the controlled wheel is lifted from the road surface based on the amount of change in the target control current.

[0057] The target control current is a target value of the control current supplied to the corresponding electric motor by the controller 3A to 7D, and is calculated by each controller 3A to 7D based on, for example, a steering request or a drive request and a sensor detection value (motor rotation angle). The controllers 3A to 7D supply the control current to the electric motor based on the target control current. Therefore, there is a correspondence between the target control current and the detection result of the current sensor 30, 70. In other words, the amount of change Iv in the current value of the control current corresponds to the amount of change in the target control current. Therefore, the state determination unit 33, 73 can determine whether the controlled wheel is lifted from the road surface based on the amount of change in the target control current.

[0058] The configuration of this embodiment can be described as follows: Vehicle control device 1 is equipped with left steering motor 221, which is an electric motor that independently steers left front wheel 11 or left rear wheel 13 (hereinafter referred to as "left wheels 11, 13"), and right steering motor 221, which is an electric motor that independently steers right front wheel 12 or right rear wheel 14 (hereinafter referred to as "right wheels 12, 14") that is paired with left wheels 11, 13. Vehicle control device 1 is also equipped with left steering controller 3A (3C) that continuously supplies a control current to left steering motor 221 in order to maintain the steering angle of left wheels 11, 13 at least while the vehicle is traveling straight, and right steering controller 3B (3D) that continuously supplies a control current to right steering motor 221 in order to maintain the steering angle of right wheels 12, 14 at least while the vehicle is traveling straight. The left steering controller 3A (3C) is provided with a current acquisition section 31, a change amount calculation section 32, and a state determination section 33 for the left steering motor 221. The right steering controller 3B (3D) is provided with a current acquisition section 31, a change amount calculation section 32, and a state determination section 33 for the right steering motor 221.

[0059] The configuration of this embodiment can be described as follows: The vehicle control device 1 includes a left drive motor 61, which is an electric motor that independently drives the left wheels 11, 13, and a right drive motor 61, which is an electric motor that independently drives the right wheels 12, 14 that are paired with the left wheels 11, 13. The vehicle control device 1 also includes a left drive controller 7A (7C) that continuously supplies a control current to the left drive motor 61 to maintain the driving force of the left wheels 11, 13 at least while the vehicle is traveling straight, and a right drive controller 7B (7D) that continuously supplies a control current to the right drive motor 61 to maintain the driving force of the right wheels 12, 14 at least while the vehicle is traveling straight. The left drive controller 7A (7C) includes a current acquisition unit 71, a change amount calculation unit 72, and a state determination unit 73 for the left drive motor 61. The right drive controller 7B (7D) includes a current acquisition unit 71, a change amount calculation unit 72, and a state determination unit 73 for the right drive motor 61. Each controller continuously supplies a control current to the corresponding electric motor at least while the vehicle is traveling straight. [Explanation of symbols]

[0060] 1...vehicle control device, 2A, 2C...left steering device, 2B, 2D...right steering device, 221...steering motor (electric motor, left steering motor, right steering motor), 3A, 3C...left steering controller, 3B, 3D...right steering controller, 30, 70...current sensor, 31, 71...current acquisition unit, 32, 72...variation amount calculation unit, 33, 73...state determination unit, 61...drive motor (electric motor, left drive motor, right drive motor), 7A, 7C...left drive controller, 7B, 7D...right drive controller

Claims

1. An electric motor that steers each wheel independently, a controller that continuously supplies a control current to the electric motor to maintain the steering angle of the wheels at least while the vehicle is traveling straight; A vehicle control device comprising: The controller: a current acquisition unit that acquires a current value of the actual or target control current supplied to the electric motor; a change amount calculation unit that calculates a change amount per unit time of the current value; a state determination unit that determines whether the wheel is lifted from the road surface based on the amount of change; Equipped with The vehicle control device includes: a left steering motor which is the electric motor that steers the left wheels independently; a right steering motor which is the electric motor that independently steers a right wheel that is paired with the left wheel; a left steering controller that continuously supplies the control current to the left steering motor in order to maintain the steering angle of the left wheels at least while the vehicle is traveling straight; a right steering controller that continuously supplies the control current to the right steering motor in order to maintain the steering angle of the right wheel at least while the vehicle is traveling straight; Equipped with the left steering controller includes the current acquisition unit, the change amount calculation unit, and the state determination unit for the left steering motor, The right steering controller includes the current acquisition unit, the change amount calculation unit, and the state determination unit for the right steering motor. Vehicle control device.

2. An electric motor that drives each wheel independently; a controller that continuously supplies a control current to the electric motor to maintain a driving force of the wheels at least while the vehicle is traveling straight; A vehicle control device comprising: The controller: a current acquisition unit that acquires a current value of the actual or target control current supplied to the electric motor; a change amount calculation unit that calculates a change amount per unit time of the current value; a state determination unit that determines whether the wheel is lifted from the road surface based on the amount of change; Equipped with The vehicle control device includes: a left drive motor that is the electric motor that independently drives a left wheel; a right drive motor that is the electric motor that independently drives a right wheel that is paired with the left wheel; a left drive controller that continuously supplies the control current to the left drive motor to maintain the driving force of the left wheel at least while the vehicle is traveling straight; a right drive controller that continuously supplies the control current to the right drive motor to maintain the driving force of the right wheel at least while the vehicle is traveling straight; Equipped with the left drive controller includes the current acquisition unit, the change amount calculation unit, and the state determination unit for the left drive motor; The right drive controller includes the current acquisition unit, the change amount calculation unit, and the state determination unit for the right drive motor. Vehicle control device.

3. the state determination unit determines whether the wheel is lifted off the road surface based on the absolute value of the amount of change and whether the amount of change is positive or negative. The vehicle control device according to claim 1 or 2.

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