Vehicle control device

Abstract

To provide a vehicle control device capable of performing torque control corresponding to curve traveling.SOLUTION: A vehicle control device according to an embodiment of the present disclosure includes a control unit capable of deriving a target torque for each wheel by adding a variable torque for each wheel that periodically varies to a required torque for each wheel according to an accelerator operation amount, and performing torque control of each motor on the basis of the derived target torque for each wheel. When the turning of the vehicle is detected, the control unit can set a first gain of the variable torque applied to each motor on the outer wheel side to a value larger than a second gain of the variable torque applied to each motor on the inner wheel side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle control device mounted on a vehicle. [Background technology]

[0002] BACKGROUND ART Various techniques have been proposed for operating a vehicle more safely (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-074947 [Patent Document 2] International Publication No. WO2002 / 000463 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-205799 Summary of the Invention

[0004] A vehicle control device according to an embodiment of the present disclosure is a device capable of controlling a vehicle that has four wheels and four motors, one for each wheel, and that can travel by independently driving each motor. The vehicle control device includes a control unit that derives a target torque for each wheel by adding a periodically fluctuating torque for each wheel to a required torque for each wheel corresponding to an accelerator operation amount, and controls the torque of each motor based on the derived target torque for each wheel. When a turning of the vehicle is detected, the control unit is capable of setting a first gain of the fluctuating torque applied to each motor on the outer wheels to a value greater than a second gain of the fluctuating torque applied to each motor on the inner wheels. [Brief explanation of the drawings]

[0005] The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate one embodiment and, together with the description, serve to explain the principles of the disclosure.

[0006] [Figure 1] FIG. 1 is a diagram illustrating an example of functional blocks of a vehicle according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing an example of the arrangement of four wheels and four motors provided on the vehicle of FIG. [Figure 3] FIG. 3 is a diagram showing a modified example of the arrangement of the four wheels and four motors provided on the vehicle of FIG. [Figure 4] Fig. 4(A) is a diagram showing an example of a waveform of a required torque, Fig. 4(B) is a diagram showing an example of a waveform of a fluctuating torque, and Fig. 4(C) is a diagram showing an example of a waveform of a target torque. [Figure 5] FIG. 5 is a diagram showing an example of waveforms of torque fluctuations for each wheel when turning left. [Figure 6] FIG. 6 is a diagram showing an example of waveforms of torque fluctuations for each wheel when turning right. [Figure 7] FIG. 7 is a diagram showing an example of a procedure for deriving a target torque in the vehicle of FIG. [Figure 8] FIG. 8 is a diagram showing an example of a procedure following FIG. [Figure 9] FIG. 9 is a diagram showing a modified example of the functional blocks of the vehicle shown in FIG. [Figure 10] FIG. 10 is a diagram showing an example of a road surface on which the vehicle of FIG. 9 is traveling. [Figure 11] FIG. 11 is a diagram showing an example of a procedure for deriving a fluctuating torque gain in the vehicle of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] <1. Background> In a vehicle driven by a motor, motor output is smoother than engine output. This provides a smooth feel in all driving conditions, such as straight driving, lane changes, and curve driving. However, while this feeling is provided, the driver receives less information from the vehicle (driver information). On low-friction roads (low μ roads) such as rainy weather, snowy roads, and icy roads, vehicle grip decreases, resulting in even less driver information than on dry roads. This makes it difficult for the driver to grasp road conditions and the vehicle's grip. As a result, tire slip limits can easily be exceeded, causing the vehicle to spin out or understeer due to slippage.

[0008] To address this problem, it is conceivable to derive a target torque by adding a periodically fluctuating torque to a required torque according to an acceleration request, and to control the torque of the motor based on the derived target torque, in order to improve driver information (see, for example, Patent Documents 1 to 3). However, the requirements for such torque control differ depending on the driving state. In particular, when driving on a curve, the behavior of the vehicle differs significantly from the behavior when driving in a straight line, so torque control that corresponds to driving on a curve is required. It is desirable to provide a vehicle control device that can perform torque control that corresponds to driving on a curve.

[0009] Some exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the following description illustrates one specific example of the present disclosure and should not be construed as limiting the present disclosure. For example, each element, including numerical values, shapes, materials, parts, the position of each part, and the connection method of each part, is merely an example and should not be construed as limiting the present disclosure. Furthermore, in the following exemplary embodiments, components not described in independent claims based on the highest concept of the present disclosure are optional and may be provided as needed. The drawings are schematic and are not intended to be drawn to scale. Throughout this specification and the drawings, components having substantially the same function and configuration are designated by the same reference numerals, and redundant description will be omitted. Furthermore, components not directly related to one embodiment of the present disclosure are not shown in the drawings.

[0010] <2. Embodiment> [Configuration example] An example configuration of a control unit 30 and a vehicle 1 according to an embodiment of the present disclosure will be described. FIG. 1 illustrates an example of functional blocks of the vehicle 1 according to the present embodiment. The vehicle 1 is capable of traveling by independently driving four motors, one for each steered wheel. As shown in FIG. 1, the vehicle 1 includes, for example, a sensor unit 10, a storage unit 20, a control unit 30, a control flag input unit 40, and a motor 50. The control unit 30 corresponds to a specific example of a "vehicle control device" or "control unit" according to an embodiment of the present disclosure.

[0011] The motor 50 is configured to drive each steered wheel of the vehicle 1. The motor 50 is capable of independently driving each steered wheel of the vehicle 1 in accordance with a target torque Tg for each steered wheel input from a motor torque control unit 34 (described later). The vehicle 1 is provided with four steered wheels. As shown in FIG. 2 , the vehicle 1 is provided with two front wheels (left front wheel T_FL, right front wheel T_FR) and two rear wheels (left rear wheel T_RL, right rear wheel T_RR). The motor 50 is configured to include a left front wheel motor M_FL provided for the left front wheel T_FL, a right front wheel motor M_FR provided for the right front wheel T_FR, a left rear wheel motor M_RL provided for the left rear wheel T_RL, and a right rear wheel motor M_RR provided for the right rear wheel T_RR. Hereinafter, the left front wheel motor M_FL, the right front wheel motor M_FR, the left rear wheel motor M_RL, and the right rear wheel motor M_RR will be collectively referred to as motor M. Furthermore, the left front wheel T_FL, the right front wheel T_FR, the left rear wheel T_RL, and the right rear wheel T_RR will be collectively referred to as wheels T.

[0012] The left front wheel motor M_FL, the right front wheel motor M_FR, the left rear wheel motor M_RL, and the right rear wheel motor M_RR are in-wheel motors provided inside the left front wheel T_FL, the right front wheel T_FR, the left rear wheel T_RL, and the right rear wheel T_RR, for example, as shown in Fig. 2. The left front wheel motor M_FL, the right front wheel motor M_FR, the left rear wheel motor M_RL, and the right rear wheel motor M_RR may be motors coupled to the left front wheel T_FL, the right front wheel T_FR, the left rear wheel T_RL, and the right rear wheel T_RR via drive shafts DS_FL, DS_FR, DS_RL, and DS_RR, for example, as shown in Fig. 3.

[0013] The sensor unit 10 is configured to include various sensors mounted on the vehicle 1. For example, as shown in Fig. 1, the sensor unit 10 has an accelerator operation amount sensor 11 and a vehicle state amount sensor 12. The sensor unit 10 may have sensors other than those described above.

[0014] The accelerator operation amount sensor 11 is capable of detecting the accelerator operation amount from the depression amount of the accelerator pedal. The accelerator operation amount sensor 11 is capable of outputting data on the detected accelerator operation amount (accelerator operation amount data) to the control unit 30.

[0015] The vehicle state quantity sensor 12 is capable of detecting vehicle state quantities, which are information indicating the state of the vehicle 1. The vehicle state quantity sensor 12 is capable of outputting time-series data (vehicle state quantity data) on the detected vehicle state quantities to the control unit 30. The vehicle state quantity sensor 12 is configured to include, as sensors capable of detecting the vehicle state quantities, for example, a vehicle speed sensor, an acceleration sensor, an angular velocity sensor, a steering angle sensor, a steering torque sensor, and a load sensor.

[0016] The vehicle speed sensor is capable of detecting the speed (vehicle speed) of the vehicle 1. The vehicle speed sensor is capable of outputting time series data (vehicle speed data) about the detected vehicle speed to the control unit 30. The acceleration sensor is capable of detecting acceleration applied to the vehicle 1. The acceleration sensor is capable of outputting time series data (acceleration data) about the detected acceleration in three directions (longitudinal acceleration, lateral acceleration, and vertical acceleration) to the control unit 30. The angular velocity sensor is capable of detecting the angular velocity of the vehicle 1. The angular velocity sensor is capable of outputting time series data (angular velocity data) about the detected three angular velocities (yaw angular velocity (yaw rate), roll angular velocity, and pitch angular velocity) to the control unit 30.

[0017] The steering angle sensor is capable of detecting the steering angle of the steering wheel of the vehicle 1 (steering angle). The steering angle sensor is capable of outputting time-series data (steering angle data) about the detected steering angle to the control unit 30. The steering torque sensor is capable of detecting the steering torque generated by the driver's steering wheel operation. The steering torque sensor is capable of outputting time-series data (steering torque data) about the detected steering torque to the control unit 30. The load sensor is capable of detecting the load acting on each wheel T. The load sensor is capable of outputting time-series data (load data) about the detected load to the control unit 30.

[0018] The storage unit 20 stores, for example, a control flag 21 input from the control flag input unit 40. The control flag 21 includes an identifier indicating whether the driving mode is a "torque fluctuation control mode" or a "normal mode." The "torque fluctuation control mode" refers to a mode in which torque control is performed by oscillating the target torque Tg at a low frequency. The "normal mode" refers to a mode in which torque control is performed according to the required torque Tr without oscillating the target torque Tg at a low frequency.

[0019] The storage unit 20 may store, for example, a program to be executed by the control unit 30. This program is a program for causing the control unit 30 to execute a series of procedures for controlling the entire vehicle 1. The storage unit 20 is configured by, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device (such as a hard disk), etc.

[0020] The control unit 30 is capable of controlling the entire vehicle 1. The control unit 30 is, for example, a so-called ECU (Electronic Control Unit) and is configured to include, for example, one or more processors and one or more memories. The control unit 30 may be configured to include, for example, a CPU (Central Processing Unit). In this case, the control unit 30 may be capable of controlling the entire vehicle 1 by, for example, executing a program stored in the storage unit 20.

[0021] The control unit 30 is capable of controlling the vehicle 1 that runs by being driven by a motor. The control unit 30 has, for example, a driving control unit 31 as shown in FIG. 1. The driving control unit 31 is capable of controlling the driving of the vehicle 1 (for example, the torque of the motor 50). The driving control unit 31 has, for example, a required torque derivation unit 32, a variable torque derivation unit 33, and a motor torque control unit 34 as shown in FIG. 1.

[0022] The required torque derivation unit 32 is capable of deriving the required torque Tr (see FIG. 4A) according to an acceleration request. The acceleration request refers to the depression of the accelerator pedal or a variation in the amount of depression of the accelerator pedal. In other words, the required torque derivation unit 32 is capable of deriving the required torque Tr according to the amount of accelerator operation. FIG. 4A shows an example of the change over time in the required torque Tr obtained when the driver depresses the accelerator pedal at a constant speed over time. The acceleration request may be made by the driver during manual driving, or by the cruise control unit 31 during autonomous driving. The required torque derivation unit 32 is capable of deriving the amount of torque (required torque Tr) that should be generated by the motor 50, based on accelerator operation amount data obtained from the accelerator operation amount sensor 11.

[0023] The fluctuating torque derivation unit 33 is capable of deriving the fluctuating torque Tf (see FIG. 4(B)), which fluctuates periodically. The fluctuating torque Tf is used to provide the driver with driver information by intentionally changing the behavior of the vehicle 1. FIG. 4(B) shows an example of the change in the fluctuating torque Tf over time. The fluctuating torque Tf is expressed by multiplying the fluctuating torque gain G by the base torque Tf0. The gain G is, for example, a value greater than 0. The gain G may be, for example, zero (0).

[0024] The fluctuation range of the fluctuating torque Tf is, for example, a value within a range of several percent to several tens of percent of the magnitude of the required torque Tr. The frequency of the fluctuating torque Tf (base torque Tf0) is, for example, a value within a range of 10 Hz to 30 Hz. The waveform of the fluctuating torque Tf (base torque Tf0) is, for example, a rectangular or sine waveform. The fluctuation range, frequency, and waveform of the fluctuating torque Tf are not limited to the above specific examples. For example, the fluctuating torque derivation unit 24 may be capable of changing at least one of the fluctuation range, frequency, and waveform of the base torque Tf0 depending on the magnitude of the required torque Tr. For example, the fluctuating torque derivation unit 24 may be capable of keeping at least one of the fluctuation range, frequency, and waveform of the base torque Tf0 constant regardless of the magnitude of the required torque Tr.

[0025] The fluctuating torque derivation unit 33 is capable of detecting whether the vehicle 1 is turning based on data obtained from the vehicle state quantity sensor 12. The fluctuating torque derivation unit 33 is capable of detecting whether the vehicle 1 is turning based on at least one value of the steering angle, the longitudinal and lateral acceleration, and the yaw rate. When the fluctuating torque derivation unit 33 detects that the vehicle 1 is turning, the fluctuating torque derivation unit 33 is capable of setting the gain of the fluctuating torque Tf applied to each motor M on the outer wheel side to a value greater than the gain of the fluctuating torque Tf applied to each motor M on the inner wheel side. The gain of the fluctuating torque Tf applied to each motor M on the outer wheel side corresponds to a specific example of a "first gain" according to an embodiment of the present disclosure. Hereinafter, the gain of the fluctuating torque Tf applied to each motor M on the outer wheel side is referred to as a fluctuating torque gain Gout. The gain of the fluctuating torque Tf applied to each motor M on the inner wheel side corresponds to a specific example of a "second gain" according to an embodiment of the present disclosure. Hereinafter, the gain of the fluctuating torque Tf applied to each motor M on the inner wheel side is referred to as a fluctuating torque gain Gin. The fluctuating torque gain Gout and the fluctuating torque gain Gin are illustrated in FIGS. 5(A) to 5(D) and FIGS. 6(A) to 6(D), which will be described later.

[0026] 5(A) to 5(D) show examples of waveforms of the fluctuating torque Tf for each wheel T when turning left. FIG. 5(E) shows an example of the waveform of the on / off of the torque fluctuation control activation switch. In FIGS. 5(A) to 5(E), t1 indicates when the vehicle 1 enters the left corner, i.e., when the vehicle 1 starts turning left. t2 indicates when the angular velocity of the vehicle 1 becomes constant after entering the left corner, i.e., when the vehicle 1 reaches a steady state. t3 indicates when the vehicle 1 exits the left corner, i.e., when the angular velocity of the vehicle 1 begins to change again. t4 indicates when the vehicle 1 exits the left corner, i.e., when the left turn of the vehicle 1 ends. In FIGS. 5(A) to 5(D), fluctuating torque gains G1, G2, and G3 are examples of gains of the fluctuating torque Tf applied to the motor M. The fluctuating torque gain G2 is a value greater than the fluctuating torque gain G1. The fluctuating torque gain G3 is a value greater than the fluctuating torque gain G2.

[0027] When a left turn of the vehicle 1 is detected, the fluctuating torque derivation unit 33 can set the gain of the fluctuating torque Tf (fluctuating torque gain Gout) applied to the motors M_FR, M_RR on the right front and rear wheels to a value greater than the gain of the fluctuating torque Tf (fluctuating torque gain Gin) applied to the motors M_FL, M_RL on the left front and rear wheels. For example, as shown in Figures 5(A) to 5(D), the fluctuating torque derivation unit 33 can set the fluctuating torque gain Gout to a value greater than the fluctuating torque gain Gin while the vehicle 1 is traveling around the left corner (t1 to t4).

[0028] 6(A) to 6(D) show examples of waveforms of the fluctuating torque Tf for each wheel T when turning right. FIG. 6(E) shows an example of waveforms when the torque fluctuation control operation switch is turned on and off. In FIGS. 6(A) to 6(E), t1 indicates when the vehicle 1 enters the right corner, that is, when the vehicle 1 starts to turn right. t2 indicates when the angular velocity of the vehicle 1 becomes constant after entering the right corner, that is, when the vehicle 1 reaches a steady state. t3 indicates when the vehicle 1 exits the right corner, that is, when the angular velocity of the vehicle 1 begins to change again. t4 indicates when the vehicle 1 exits the right corner, that is, when the vehicle 1 finishes turning right.

[0029] When a right turn of the vehicle 1 is detected, the fluctuating torque derivation unit 33 can set the gain of the fluctuating torque Tf (fluctuating torque gain Gout) applied to the motors M_FL, M_RL on the left front and rear wheels to a value greater than the gain of the fluctuating torque Tf (fluctuating torque gain Gin) applied to the motors M_FR, M_RR on the right front and rear wheels. For example, as shown in Figures 6(A) to 6(D), the fluctuating torque derivation unit 33 can set the fluctuating torque gain Gout to a value greater than the fluctuating torque gain Gin while the vehicle 1 is traveling around a right corner (t1 to t4).

[0030] When entering a corner, which is the start of a turn, the fluctuating torque derivation unit 33 is able to set the fluctuating torque gain GFout, which is applied to the front wheel motor M among the outer wheel motors M, to a value greater than the fluctuating torque gain GRout, which is applied to the rear wheel motor M among the outer wheel motors M. When exiting a corner, which is the end of a turn, the fluctuating torque derivation unit 33 is able to set the fluctuating torque gain GRout to a value greater than the fluctuating torque gain GFout. The fluctuating torque gain GFout corresponds to a specific example of a "third gain" according to an embodiment of the present disclosure. The fluctuating torque gain GRout corresponds to a specific example of a "fourth gain" according to an embodiment of the present disclosure.

[0031] For example, as shown in Figures 5(C) and 5(D), when entering a corner (t1 to t2), which is the start of a left turn, the fluctuating torque derivation unit 33 can set the fluctuating torque gain GFout applied to the right front wheel motor M_FR to a value greater than the fluctuating torque gain GRout applied to the right rear wheel motor M_RR.For example, as shown in Figures 5(C) and 5(D), when exiting a corner (t3 to t4), which is the end of a left turn, the fluctuating torque derivation unit 33 can set the fluctuating torque gain GRout to a value greater than the fluctuating torque gain GFout.

[0032] For example, as shown in Figures 6(A) and 6(B), when entering a corner (t1 to t2), which is the start of a right turn, the fluctuating torque derivation unit 33 can set the fluctuating torque gain GFout applied to the left front wheel motor M_FL to a value larger than the fluctuating torque gain GRout applied to the left rear wheel motor M_RL.For example, as shown in Figures 6(A) and 6(B), when exiting a corner (t3 to t4), which is the end of a right turn, the fluctuating torque derivation unit 33 can set the fluctuating torque gain GRout to a value larger than the fluctuating torque gain GFout.

[0033] The fluctuating torque derivation unit 33 is capable of smoothly changing the values ​​of the fluctuating torque gain GFout and the fluctuating torque gain GRout in accordance with changes in the load acting on each outer wheel T. The fluctuating torque derivation unit 33 is capable of calculating changes in load based on load data obtained by a load sensor, for example. The fluctuating torque derivation unit 33 may also be capable of calculating changes in load based on data obtained from various sensors other than the load sensor, for example.

[0034] For example, as shown in FIG. 5(C), when entering a corner (t1 to t2), which is the start of a left turn, the fluctuating torque derivation unit 33 can smoothly change (increase) the value of the gain of the right front wheel fluctuating torque Tf_FR (fluctuating torque gain GFout) in response to changes in the load acting on the right front wheel T_FR. For example, as shown in FIG. 5(C), when exiting a corner (t3 to t4), which is the end of a left turn, the fluctuating torque derivation unit 33 can smoothly change (decrease) the value of the gain of the right front wheel fluctuating torque Tf_FR (fluctuating torque gain GFout) in response to changes in the load acting on the right front wheel T_FR. For example, as shown in FIG. 5(D), when exiting a corner (t3 to t4), which is the end of a left turn, the fluctuating torque derivation unit 33 can smoothly change (temporarily increase) the value of the gain of the right rear wheel fluctuating torque Tf_RR (fluctuating torque gain GRout) in response to changes in the load acting on the right rear wheel T_RR.

[0035] For example, as shown in FIG. 6A, when entering a corner (t1 to t2), which is the start of a right turn, the fluctuating torque derivation unit 33 can smoothly change (increase) the value of the gain of the left front wheel fluctuating torque Tf_FL (fluctuating torque gain GFout) in accordance with changes in the load acting on the left front wheel T_FL. For example, as shown in FIG. 6A, when exiting a corner (t3 to t4), which is the end of a right turn, the fluctuating torque derivation unit 33 can smoothly change (decrease) the value of the gain of the left front wheel fluctuating torque Tf_FL (fluctuating torque gain GFout) in accordance with changes in the load acting on the left front wheel T_FL. For example, as shown in FIG. 6B, when exiting a corner (t3 to t4), which is the end of a right turn, the fluctuating torque derivation unit 33 can smoothly change (temporarily increase) the value of the gain of the left rear wheel fluctuating torque Tf_RL (fluctuating torque gain GRout) in accordance with changes in the load acting on the left rear wheel T_RL.

[0036] When it is detected that the vehicle 1 is traveling straight, the fluctuating torque derivation unit 33 is able to set the gain of the fluctuating torque Tf applied to each motor M to a value equal to or less than the fluctuating torque gain Gout and equal to or greater than the fluctuating torque gain Gin. Specifically, when it is detected that the vehicle 1 is traveling straight, the fluctuating torque derivation unit 33 is able to set the gain of the fluctuating torque Tf applied to each motor M to a value smaller than the fluctuating torque gain Gout applied to the outside front wheel motor M when turning in a steady state (t2 to t3) and larger than the fluctuating torque gain Gin applied to the inside front wheel motor M when turning in a steady state (t2 to t3).

[0037] The motor torque control unit 34 is capable of independently controlling the torque of the four motors (left front wheel motor M_FL, right front wheel motor M_FR, left rear wheel motor M_RL, and right rear wheel motor M_RR). When the driving mode is the normal mode, the motor torque control unit 34 is capable of setting the required torque Tr for each wheel T as the target torque Tg for each wheel T. The motor torque control unit 34 is further capable of controlling the torque of the four motors (left front wheel motor M_FL, right front wheel motor M_FR, left rear wheel motor M_RL, and right rear wheel motor M_RR) based on the set target torque Tg for each wheel T.

[0038] When the driving mode is the torque fluctuation control mode, the motor torque control unit 34 is capable of deriving a target torque Tg (see FIG. 4(C)) for each wheel T by adding the fluctuation torque Tf for each wheel T to the required torque Tr for each wheel T. The motor torque control unit 34 is further capable of controlling the torque of the four motors (left front wheel motor M_FL, right front wheel motor M_FR, left rear wheel motor M_RL, and right rear wheel motor M_RR) based on the derived target torque Tg for each wheel T.

[0039] The motor torque control unit 34 is capable of determining whether or not it is necessary to add the fluctuating torque Tf to the required torque Tr based on the control flag 22. For example, when the control flag 22 indicates the torque fluctuation control mode, the motor torque control unit 34 is capable of deriving the target torque Tg by adding the fluctuating torque Tf to the required torque Tr. For example, when the control flag 22 indicates the normal mode, the motor torque control unit 34 is capable of setting the required torque Tr as the target torque Tg without adding the fluctuating torque Tf to the required torque Tr.

[0040] The control flag input unit 40 is capable of receiving input of the control flag 22 from the driver. The control flag input unit 40 is, for example, a paddle shifter attached to a steering wheel. For example, when the driver simultaneously presses and holds the left and right paddle shifters, the control flag input unit 40 can store "1" as the control flag 22 in the storage unit 20. For example, when the driver simultaneously presses and holds the left and right paddle shifters again after previously storing "1" as the control flag 22 in the storage unit 20, the control flag input unit 40 can store "0" as the control flag 22 in the storage unit 20. For example, when the driver simultaneously presses and holds the left and right paddle shifters again after previously storing "0" as the control flag 22 in the storage unit 20, the control flag input unit 40 can store "1" as the control flag 22 in the storage unit 20.

[0041] When the control flag 22 is "1", it means, for example, that the torque fluctuation control mode is selected. When the control flag 22 is "0", it means, for example, that the normal mode is selected, in which periodic torque fluctuation control is not performed. Note that the values ​​that the control flag 22 can take are not limited to those described above.

[0042] [Operation] Next, the operation of the traveling control unit 31 will be described with reference to Figures 7 and 8. Figures 7 and 8 show an example of a procedure for deriving the target torque Tg.

[0043] The traveling control unit 31 acquires an acceleration request from the accelerator operation amount sensor 11 (step S101). Next, the traveling control unit 31 derives a required torque Tr according to the acquired acceleration request (step S102). Next, when the control flag 22 input from the control flag input unit 40 indicates the normal mode (step S103; N), the traveling control unit 31 sets the target torque Tg of all wheels T to Tr (step S104).

[0044] When the control flag 22 input from the control flag input unit 40 indicates the torque fluctuation control mode (step S103; Y), the driving control unit 31 sets the fluctuation torque gain G of all the wheels T to G2 (step S105). The driving control unit 31 further sets the target torque Tg of all the wheels T to Tr+Tf (=Tr+G×Tf0) using the set fluctuation torque gain G (step S106).

[0045] The driving control unit 31 determines whether the vehicle 1 is traveling straight based on at least one value of the steering angle, the longitudinal and lateral acceleration, and the yaw rate (step S107). If the driving control unit 31 determines that the vehicle 1 is traveling straight (step S107; Y), it executes step S105. If the driving control unit 31 determines that the vehicle 1 is not traveling straight (step S107; N), it determines whether the vehicle 1 is turning left (step S108).

[0046] If the driving control unit 31 determines that the vehicle 1 is turning left (step S108; Y), it determines whether or not the vehicle 1 is entering a corner, i.e., at the start of a left turn (step S109). If the driving control unit 31 determines that the vehicle 1 is entering a corner, i.e., at the start of a left turn (step S109; Y), it increases the fluctuating torque gain G of the right front wheel T_FR to G3 (step S110). The driving control unit 31 further decreases the fluctuating torque gain G of the left front and rear wheels to G1 (step S111). If the driving control unit 31 determines that the vehicle 1 is not entering a corner, i.e., at the start of a left turn (step S109; N), it determines whether or not the vehicle 1 is exiting a corner (step S112).

[0047] If the cruise control unit 31 determines that the vehicle 1 is exiting a corner (step S112; Y), it temporarily increases the fluctuating torque gain G of the right rear wheel T_RR to G3 (step S113). The cruise control unit 31 further decreases the fluctuating torque gain G of the right front wheel T_FR to G2 (step S114). If the cruise control unit 31 determines that the vehicle 1 is not exiting a corner, that is, that the angular velocity of the vehicle 1 is constant (step S112; N), it maintains the fluctuating torque gain G of each wheel T.

[0048] If the driving control unit 31 determines that the vehicle 1 is not turning left, that is, is turning right (step S108; N), it determines whether or not the vehicle 1 is entering a corner, i.e., at the start of a right turn (step S115). If the driving control unit 31 determines that the vehicle 1 is entering a corner, i.e., at the start of a right turn (step S115; Y), it increases the fluctuating torque gain G of the left front wheel T_FL to G3 (step S116). The driving control unit 31 further decreases the fluctuating torque gain G of the right front and rear wheels to G1 (step S111). If the driving control unit 31 determines that the vehicle 1 is not entering a corner, i.e., at the start of a right turn (step S115; N), it determines whether or not the vehicle 1 is exiting a corner (step S118).

[0049] If the driving control unit 31 determines that the vehicle 1 is exiting a corner (step S118; Y), it increases the fluctuating torque gain G of the left rear wheel T_RL to G3 (step S119). The driving control unit 31 further decreases the fluctuating torque gain G of the left front wheel T_FL to G2 (step S120). If the driving control unit 31 determines that the vehicle 1 is not exiting a corner, that is, that the angular velocity of the vehicle 1 is constant (step S118; N), it maintains the fluctuating torque gain G of each wheel T.

[0050] The driving control unit 31 sets the fluctuating torque gains G of the four motors M (left front wheel motor M_FL, right front wheel motor M_FR, left rear wheel motor M_RL, and right rear wheel motor M_RR) as described above. When turning left, the driving control unit 31 sets the target torque Tg for each wheel T based on the fluctuating torque gain G for each wheel T set as shown in FIGS. 5(A) to 5(D), for example, and controls the torque of each motor based on the set target torque Tg for each wheel T. When turning right, the driving control unit 31 sets the target torque Tg for each wheel T based on the fluctuating torque gain G for each wheel T set as shown in FIGS. 6(A) to 6(D), for example, and controls the torque of each motor based on the set target torque Tg for each wheel T.

[0051] [effect] Next, the effects of the control unit 30 and the vehicle 1 according to the embodiment of the present disclosure will be described.

[0052] In this embodiment, a target torque Tg for each wheel T is derived by adding a periodically fluctuating torque Tf for each wheel T to the required torque Tr for each wheel T corresponding to the accelerator operation amount, and torque control of each motor M is performed based on the derived target torque Tg for each wheel T. At this time, if a turning of the vehicle 1 is detected, the gain of the fluctuating torque Tf applied to each motor M on the outer wheels is set to a value greater than the gain of the fluctuating torque Tf applied to each motor M on the inner wheels. As a result, when the vehicle 1 is traveling around a curve, a target torque Tg with a large vibration amplitude is applied to the motor M of the outer wheels, which is subjected to a larger load than the inner wheels, and a target torque Tg with a small vibration amplitude is applied to the motor M of the inner wheels, which is subjected to a smaller load than the outer wheels. As a result, on a low-friction coefficient road (low μ road) such as in rainy weather or on a snowy or icy road, a decrease in grip of the outer wheels can be notified to the driver early, thereby preventing the vehicle 1 from spinning or understeer due to slippage. As described above, this embodiment enables torque control suitable for traveling around a curve.

[0053] Furthermore, in this embodiment, when entering a corner, which is the start of turning, the gain of the fluctuating torque Tf applied to the motor M of the front outer wheel is set to a value greater than the gain of the fluctuating torque Tf applied to the motor M of the rear outer wheel. As a result, when the vehicle 1 enters a corner, a target torque Tg with a large vibration amplitude is applied to the motor M of the front outer wheel, which is subjected to a greater load than the rear outer wheel, and a target torque Tg with a small vibration amplitude is applied to the motor M of the rear outer wheel, which is subjected to a smaller load than the front outer wheel. Furthermore, when exiting a corner, which is the end of turning, the gain of the fluctuating torque Tf applied to the motor M of the rear outer wheel is set to a value greater than the gain of the fluctuating torque Tf applied to the motor M of the front outer wheel. As a result, when the vehicle 1 exits a corner, a target torque Tg with a large vibration amplitude is applied to the motor M of the rear outer wheel, which is subjected to a greater load than the front outer wheel, and a target torque Tg with a small vibration amplitude is applied to the motor M of the front outer wheel, which is subjected to a smaller load than the rear outer wheel.

[0054] As a result, on rainy days or on roads with a low coefficient of friction (low μ roads) such as snowy or icy roads, the driver can be notified early of a decrease in grip of the front outer wheels when entering a corner or a decrease in grip of the rear outer wheels when exiting a corner. This makes it possible to prevent the vehicle 1 from spinning or understeer due to slippage. As described above, in this embodiment, torque control can be performed in accordance with curve driving.

[0055] Furthermore, in this embodiment, the gain value of the fluctuating torque Tf applied to the motor M of the outer wheel changes smoothly in response to changes in the load acting on the outer wheel. This allows the vehicle's behavior to change smoothly, while also notifying the driver early on of a decrease in grip of the front outer wheel when entering a corner, or a decrease in grip of the rear outer wheel when exiting a corner. This makes it possible to prevent the vehicle 1 from spinning or understeering due to slippage. As described above, in this embodiment, torque control can be performed that is suited to curve driving.

[0056] Furthermore, in this embodiment, when straight-ahead traveling of the vehicle 1 is detected, the fluctuating torque gain G given to each motor M is set to a value smaller than the fluctuating torque gain G given to the motor M of the outer wheel when the vehicle 1 is traveling around a curve, and is set to a value larger than the fluctuating torque gain G given to the motor M of the inner wheel when the vehicle 1 is traveling around a curve. This makes it possible to notify the driver early of a decrease in grip of each wheel T when traveling straight on a low-friction coefficient road (low μ road) such as in rainy weather or on a snowy or icy road. Therefore, it is possible to prevent the vehicle 1 from spinning due to slippage. From the above, in this embodiment, torque control corresponding to straight-ahead traveling can be performed.

[0057] In this embodiment, whether or not the vehicle 1 is turning is detected based on at least one value of the steering angle, the longitudinal and lateral acceleration, and the yaw rate. This allows torque control to be performed in accordance with whether the vehicle is traveling around a curve or in a straight line.

[0058] <2. Modifications> Although the present disclosure has been described above by giving the embodiments, the present disclosure is not limited to these embodiments and various modifications are possible.

[0059] [Variation A] 9 shows a modified example of the functional blocks of the vehicle 1 according to the above embodiment. In this modified example, for example, as shown in FIG. 9, the sensor unit 10 may further include a road surface state quantity sensor 13, and the driving control unit 31 may further include a road surface μ estimator 35.

[0060] The road surface state quantity sensor 13 is capable of detecting road surface state quantities, which are information indicating the road surface conditions of the lane on which the vehicle 1 is traveling. The road surface state quantity sensor 13 is capable of outputting time-series data (road surface state quantity data) on the detected road surface state quantities to the control unit 30. The road surface state quantity sensor 13 is configured to include, as sensors capable of detecting road surface state quantities, for example, a camera, a temperature sensor (outside air temperature sensor, road surface temperature sensor), a near-infrared sensor, and a laser light sensor (TOF (Time Of Flight) sensor).

[0061] The camera is capable of acquiring images of the area ahead of the vehicle 1. The camera is capable of outputting time-series data (image data) about the acquired images to the control unit 30. The outside air temperature sensor is capable of detecting the temperature around the vehicle 1. The outside air temperature sensor is capable of outputting time-series data (outside air temperature data) about the detected temperature to the control unit 30. The road surface temperature sensor is capable of detecting the temperature of the road surface of the lane on which the vehicle 1 is traveling. The road surface temperature sensor is capable of outputting time-series data (road surface temperature data) about the detected temperature to the control unit 30.

[0062] The near-infrared sensor is capable of irradiating the road surface of the lane on which the vehicle 1 is traveling with near-infrared rays and detecting light reflected in the near-infrared range from the road surface. The near-infrared sensor is capable of outputting time-series data (near-infrared data) about the detected reflected light in the near-infrared range to the control unit 30. The laser light sensor is capable of irradiating the road surface of the lane on which the vehicle 1 is traveling with laser light and detecting the reflected light of the laser light from the road surface. The laser light sensor is capable of outputting time-series data (laser light data) about the detected reflected light of the laser light to the control unit 30.

[0063] The road surface μ estimating unit 35 is capable of estimating a road surface μ value based on road surface state quantity data input from the road surface state quantity sensor 13. The road surface μ estimating unit 35 is capable of estimating the color, road surface roughness, etc. of the road surface ahead of the vehicle 1 from, for example, camera image data. The road surface μ estimating unit 35 is capable of estimating the amount of moisture on the road surface on which the vehicle 1 is traveling based on, for example, outside air temperature data, road surface temperature data, and near-infrared data. The road surface μ estimating unit 35 is capable of estimating the road surface condition (e.g., dry, wet) and road surface type (e.g., asphalt, snow, ice) on which the vehicle 1 is traveling based on, for example, laser light data. The road surface μ estimating unit 35 is capable of estimating the friction coefficient (road surface μ value) of the road surface on which the vehicle 1 is traveling based on, for example, data obtained by estimation (e.g., at least one of road surface color, road surface roughness, moisture content, road surface condition, and road surface type). The road surface μ estimating unit 35 may be capable of estimating the road surface μ value by a method other than the above.

[0064] The road surface μ estimating unit 35 is further capable of calculating the slip ratio s for each wheel T, for example, using the following equation: In the following equation, V is the speed of the vehicle 1, and Vw is the speed of the wheel T. The road surface μ estimating unit 35 is capable of outputting the road surface μ value obtained by estimation and the slip ratio s obtained by calculation to the motor torque control unit 34. s=(V-Vw) / Vw

[0065] Based on the road surface μ value obtained by the road surface μ estimator 35, the motor torque controller 34 is capable of detecting a low μ region α included in the road surface ahead of the vehicle 1 and a high μ region β included in the road surface ahead of the vehicle 1, for example, as shown in FIG. 10. The low μ region α is a region where the road surface μ value is smaller than the road surface μ value of the surrounding road surface. When the low μ region α is detected, the motor torque controller 34 is capable of setting the gain of the fluctuating torque Tf applied to the motor M corresponding to the wheel T passing through the low μ region α to a value larger than the gain of the fluctuating torque Tf applied to the motor M corresponding to the wheel T that has not passed through the low μ region α.

[0066] Next, the operation of the driving control unit 31 will be described with reference to Fig. 11. Fig. 11 shows an example of a procedure for deriving the variable torque gain G.

[0067] The driving control unit 31 acquires road surface state quantity data from the road surface state quantity sensor 13 (step S201). The driving control unit 31 estimates a road surface μ value based on the acquired road surface state quantity data (step S202). The driving control unit 31 further calculates a slip ratio s for each wheel T using s = (V - Vw) / Vw (step S203).

[0068] The driving control unit 31 detects a low μ region α included in the road surface ahead of the vehicle 1 and a high μ region β included in the road surface ahead of the vehicle 1 based on the road surface μ value. When the low μ region α is detected, the driving control unit 31 determines whether or not any wheel T among the motors M passes through the low μ region α (step S204). When any wheel T among the motors M passes through the low μ region α (step S204; Y), the driving control unit 31 increases the gain of the fluctuating torque Tf applied to the motor M corresponding to the wheel T passing through the low μ region α by ΔG1 (step S205).

[0069] The traveling control unit 31 determines whether or not a stick-slip wheel T is present based on the slip ratio s for each wheel T (step S206). If a stick-slip wheel T is present (step S206; Y), the traveling control unit 31 increases the gain of the fluctuating torque Tf applied to the motor M corresponding to the stick-slip wheel T by ΔG2 (step S205). In this way, a fluctuating torque gain G that takes into account the low μ region α is obtained.

[0070] Next, the effects of the vehicle 1 according to this embodiment will be described.

[0071] In this modified example, when the low μ region α is detected, the gain of the fluctuating torque Tf applied to the motor M corresponding to the wheel T passing through the low μ region α is set to a value greater than the gain of the fluctuating torque Tf applied to the motor M corresponding to the wheel T that has not passed through the low μ region α. ​​This allows the driver to be notified early that the vehicle 1 has passed through the low μ region α on a low friction coefficient road (low μ road) such as in rainy weather or on a snowy or icy road, thereby preventing the vehicle 1 from spinning or understeering due to slippage. As described above, in this modified example, torque control suitable for driving on a low μ road can be performed.

[0072] The effects described in this specification are merely examples, and the effects of the present disclosure are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present disclosure.

[0073] Furthermore, the present disclosure may take the following aspects. (1) A vehicle control device capable of controlling a vehicle that has four wheels and four motors, one for each wheel, and that can travel by independently driving each of the motors, a control unit that derives a target torque for each wheel by adding a periodically fluctuating torque for each wheel to a required torque for each wheel according to an accelerator operation amount, and performs torque control of each of the motors based on the derived target torque for each wheel; When a turn of the vehicle is detected, the control unit is capable of setting a first gain of the fluctuating torque applied to each of the motors on the outer wheel side to a value greater than a second gain of the fluctuating torque applied to each of the motors on the inner wheel side. Vehicle control device. (2) The control unit When entering a corner, which is the start of the turning, a third gain of the fluctuating torque imparted to the front wheel motor among the motors on the outer wheel side is set to a value larger than a fourth gain of the fluctuating torque imparted to the rear wheel motor among the motors on the outer wheel side; When the turning is completed and the vehicle is coming out of the corner, the fourth gain is set to a value greater than the third gain. It is possible to carry out A vehicle control device as described in (1). (3) The control unit is capable of smoothly changing the values ​​of the third gain and the fourth gain in accordance with a change in load acting on each of the outer wheels. (2) A vehicle control device according to the present invention. (4) When it is detected that the vehicle is traveling straight, the control unit is capable of setting the gain of the fluctuating torque applied to each of the motors to a small value that is smaller than the first gain and larger than the second gain. A vehicle control device according to any one of (1) to (3). (5) When a low μ region in which a road surface μ value is smaller than the road surface μ value of the surrounding road surface is detected, the control unit is capable of setting the gain of the fluctuating torque given to the motor corresponding to the wheel passing through the low μ region to a value larger than the gain of the fluctuating torque given to the motor corresponding to the wheel that has not passed through the low μ region. A vehicle control device according to any one of (1) to (4).

[0074] In a vehicle control device according to an embodiment of the present disclosure, a target torque for each wheel is derived by adding a periodically fluctuating torque for each wheel to the required torque for each wheel corresponding to the accelerator operation amount, and torque control for each motor is performed based on the derived target torque for each wheel. When a vehicle turning is detected, the gain of the fluctuating torque applied to each motor on the outer wheel side is set to a value greater than the gain of the fluctuating torque applied to each motor on the inner wheel side. As a result, when the vehicle is traveling around a curve, a target torque with a large vibration amplitude is applied to the motor on the outer wheel, which is subjected to a greater load than the inner wheel, and a target torque with a small vibration amplitude is applied to the motor on the inner wheel, which is subjected to a smaller load than the outer wheel. As a result, on low-friction coefficient roads (low μ roads) such as rainy weather or snowy or icy roads, a decrease in grip of the outer wheel can be notified to the driver early, thereby preventing the vehicle from spinning or understeer due to slippage. Based on the above, the present disclosure enables torque control suitable for traveling around a curve.

[0075] The control unit 30 shown in FIGS. 1 and 8 can be implemented by a circuit including at least one semiconductor integrated circuit, such as at least one processor (e.g., a central processing unit (CPU)), at least one application-specific integrated circuit (ASIC), and / or at least one field-programmable gate array (FPGA). The at least one processor can be configured to perform all or some of the functions of the control unit 30 shown in FIGS. 1 and 8 by reading instructions from at least one non-transitory, tangible computer-readable medium. Such medium can take various forms, including, but not limited to, various magnetic media such as hard disks, various optical media such as CDs or DVDs, and various semiconductor memories (i.e., semiconductor circuits) such as volatile or non-volatile memories. Volatile memories can include DRAM and SRAM. Non-volatile memories can include ROM and NVRAM. An ASIC is an integrated circuit (IC) specialized to perform all or some of the functions of the control unit 30 shown in FIGS. 1 and 8. The FPGA is an integrated circuit that is designed to be configurable after manufacture so as to perform all or part of the various functions of the control unit 30 shown in FIGS. [Explanation of symbols]

[0076] 1...vehicle, 10...sensor section, 11...accelerator operation amount sensor, 12...vehicle state quantity sensor, 13...road surface state quantity sensor, 20...storage section, 21...control flag, 30...control unit, 31...travel control section, 32...required torque derivation section, 33...variable torque derivation section, 34...motor torque control section, 35...road surface μ estimator, 40...control flag input section, 50...motor, G, G1, G2, G3...variable torque gain, M_FL...left front wheel motor, M_FR...right front wheel motor, M_RL...left Rear wheel motor, M_RR...right rear wheel motor, s...slip ratio, Tf0...basic torque, Tf_FL...left front wheel fluctuating torque, Tf_FR...right front wheel fluctuating torque, Tf_RL...left rear wheel fluctuating torque, Tf_RR...right rear wheel fluctuating torque, Tf...fluctuating torque, Tg_FL...left front wheel target torque, Tg_FR...right front wheel target torque, Tg_RL...left rear wheel target torque, Tg_RR...right rear wheel target torque, Tg...target torque, α...low μ region, β...high μ region, ΔG1, ΔG2...additional gains.

Claims

1. A vehicle control device capable of controlling a vehicle that has four wheels and four motors, one for each wheel, and that can travel by independently driving each of the motors, a control unit that derives a target torque for each wheel by adding a periodically fluctuating torque for each wheel to a required torque for each wheel according to an accelerator operation amount, and performs torque control of each of the motors based on the derived target torque for each wheel; When a turn of the vehicle is detected, the control unit is capable of setting a first gain of the fluctuating torque applied to each of the motors on the outer wheel side to a value greater than a second gain of the fluctuating torque applied to each of the motors on the inner wheel side. Vehicle control device.

2. The control unit When entering a corner, which is the start of the turning, a third gain of the fluctuating torque imparted to the front wheel motor among the motors on the outer wheel side is set to a value greater than a fourth gain of the fluctuating torque imparted to the rear wheel motor among the motors on the outer wheel side; When the turning is completed and the vehicle is coming out of the corner, the fourth gain is set to a value greater than the third gain. It is possible to carry out The vehicle control device according to claim 1 .

3. The control unit is capable of smoothly changing the values ​​of the third gain and the fourth gain in accordance with a change in the load acting on each of the outer wheels. The vehicle control device according to claim 2.

4. When it is detected that the vehicle is traveling straight, the control unit is capable of setting the gain of the fluctuating torque applied to each of the motors to a small value that is smaller than the first gain and larger than the second gain. The vehicle control device according to claim 1 .

5. When a low μ region in which a road surface μ value is smaller than the road surface μ value of the surrounding road surface is detected, the control unit is capable of setting the gain of the fluctuating torque given to the motor corresponding to the wheel passing through the low μ region to a value larger than the gain of the fluctuating torque given to the motor corresponding to the wheel that has not passed through the low μ region. The vehicle control device according to claim 1 .

Images