Vehicle control device and vehicle control method

Abstract

A vehicle control device according to an embodiment of the present disclosure is a device capable of controlling a vehicle that travels as a result of driving a motor. This vehicle control device comprises a control unit whereby it is possible to derive target torque by adding fluctuating torque that fluctuates cyclically to requested torque corresponding to an acceleration request and control the torque of a motor on the basis of the derived target torque. The control unit can change the gain of the fluctuating torque in accordance with road surface conditions when in a transient state that differs from a steady state in which the acceleration and the angular velocity of the vehicle are equal to or less than a predetermined value.

Description

Vehicle control device and vehicle control method

[0001] The present disclosure relates to a vehicle control device mounted on a vehicle and a vehicle control method executed by the vehicle control device.

[0002] 2. Description of the Related Art Various techniques have been proposed for operating a vehicle more safely (see, for example, Patent Documents 1 and 2).

[0003] JP 2017-055618 A JP 2011-205799 A

[0004] A vehicle control device according to an embodiment of the present disclosure is a device capable of controlling a vehicle driven by a motor. The vehicle control device includes a control unit capable of deriving a target torque by adding a periodically fluctuating torque to a required torque according to an acceleration request, and controlling the torque of the motor based on the derived target torque. The control unit is capable of changing a gain of the fluctuating torque in accordance with road surface conditions when the vehicle is in a transient state different from a steady state in which the acceleration and angular velocity of the vehicle are equal to or less than a predetermined value.

[0005] A vehicle control method according to an embodiment of the present disclosure is a method capable of controlling a vehicle driven by a motor. This vehicle control method includes the following two steps: (A) deriving a target torque by adding a periodically fluctuating torque to a required torque according to an acceleration request, and performing torque control of the motor based on the derived target torque; and (B) changing the gain of the fluctuating torque according to road surface conditions when the vehicle is in a transient state different from a steady state in which the acceleration and angular velocity are equal to or less than a predetermined value.

[0006] 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.

[0007] Fig. 1 is a diagram illustrating an example of functional blocks of a vehicle equipped with a vehicle control device according to an embodiment of the present disclosure. Fig. 2(A) is a diagram illustrating an example of a waveform of a required torque. Fig. 2(B) is a diagram illustrating an example of a waveform of a fluctuating torque. Fig. 2(C) is a diagram illustrating an example of a waveform of a target torque. Fig. 3 is a diagram for explaining an example of a procedure for deriving and correcting a target torque in the traveling control unit of Fig. 1. Fig. 4 is a diagram illustrating an example of a target torque waveform.

[0008] In a vehicle driven by a motor, motor output is smoother than engine output. Therefore, a smooth steering feel can be obtained in all driving conditions, such as straight driving, lane changes, and curve driving. However, while such a steering feel can be obtained, the driver receives less information from the vehicle (driver information). On roads with low friction coefficients, such as rainy weather or snowy roads, the vehicle's grip decreases, resulting in even less driver information than on dry roads. This makes it difficult for the driver to grasp the road surface conditions and the vehicle's grip, resulting in a lack of sense of security and steering response. It is desirable to provide a vehicle control device and a vehicle control method that can improve driver information to provide the driver with a sense of security and steering response.

[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] 1. Embodiment [Configuration Example] Fig. 1 illustrates a schematic configuration example of a vehicle 1 equipped with a control unit 20 according to an embodiment of the present disclosure. The control unit 20 corresponds to a specific example of a "control unit" in the present disclosure. The vehicle 1 is capable of traveling by motor drive. As shown in Fig. 1, the vehicle 1 includes, for example, a sensor unit 10, a control unit 20, a storage unit 30, a control flag input unit 40, and a motor 50.

[0011] 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 includes an accelerator operation amount sensor 11, a vehicle state amount sensor 12, and a road surface state amount sensor 13. The sensor unit 10 may include sensors other than those described above.

[0012] The accelerator operation amount sensor 11 detects the accelerator operation amount from the depression amount of the accelerator pedal, and outputs data on the detected accelerator operation amount (accelerator operation amount data) to the control unit 20.

[0013] 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 20. 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, and a steering torque sensor.

[0014] 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 20. 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 20. 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, roll angular velocity, and pitch angular velocity) to the control unit 20.

[0015] The steering angle sensor is capable of detecting the steering angle (steering angle) of the steering wheel of the vehicle 1. The steering angle sensor is capable of outputting time-series data (steering angle data) about the detected steering angle to the control unit 20. 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 20.

[0016] 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 20. 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).

[0017] 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 20. 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 20. 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 20.

[0018] 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 20. 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 20.

[0019] The control unit 20 is capable of controlling the entire vehicle 1. The control unit 20 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 20 may be configured to include, for example, a CPU (Central Processing Unit). In this case, the control unit 20 may be capable of controlling the entire vehicle 1 by, for example, executing a program stored in the storage unit 30.

[0020] The control unit 20 is capable of controlling the vehicle 1 that runs by being driven by a motor. The control unit 20 has, for example, a driving control unit 21 as shown in FIG. 1 . The driving control unit 21 is capable of controlling the running of the vehicle 1 (for example, the torque of the motor 50). The driving control unit 21 has, for example, a road surface μ estimator 22, a required torque deriving unit 23, a fluctuation torque deriving unit 24, and a motor torque controller 25 as shown in FIG. 1 .

[0021] The road surface μ estimating unit 22 is capable of estimating the coefficient of friction (estimated μ) of the road surface on which the vehicle 1 is traveling, for example, based on road surface state quantity data input from the road surface state quantity sensor 13. The road surface μ estimating unit 22 is capable of estimating the color, road surface roughness, etc. of the road surface ahead of the vehicle 1, for example, based on camera image data. The road surface μ estimating unit 22 is capable of estimating the amount of moisture on the road surface on which the vehicle 1 is traveling, for example, based on outside air temperature data, road surface temperature data, and near-infrared data. The road surface μ estimating unit 22 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, for example, based on laser light data. The road surface μ estimating unit 22 is capable of estimating the coefficient of friction (estimated μ) of the road surface on which the vehicle 1 is traveling, for example, based on data obtained by estimation (e.g., at least one of the road surface color, road surface roughness, moisture content, road surface condition, and road surface type). The road surface μ estimating unit 22 may be capable of estimating the estimated μ by a method other than the above.

[0022] The required torque derivation unit 23 is capable of deriving the required torque Tr (see FIG. 2A) according to an acceleration request. The acceleration request refers to the depression of the accelerator pedal or a change in the amount of depression of the accelerator pedal. FIG. 2A shows an example of the change over time in the required torque Tr obtained when the driver depresses the accelerator pedal over time. The acceleration request may be made by the driver during manual driving, or by the cruise control unit 21 during automated driving. The required torque derivation unit 23 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 torque fluctuation calculation unit 24 is capable of deriving the torque fluctuation Tf (see FIG. 2B ), which fluctuates periodically. The torque fluctuation Tf is used to intentionally change the behavior of the vehicle 1 and thereby provide the driver with driver information. FIG. 2B shows an example of the change over time of the torque fluctuation Tf.

[0024] The fluctuation range of the fluctuation torque Tf is, for example, approximately 10% of the magnitude of the required torque Tr. The frequency of the fluctuation torque Tf is, for example, 17 Hz, 20 Hz, or 24 Hz. The waveform of the fluctuation torque Tf is, for example, a rectangular or sinusoidal waveform. The fluctuation range, frequency, and waveform of the fluctuation torque Tf are not limited to those described above. For example, the fluctuation torque derivation unit 24 may be capable of changing at least one of the fluctuation range, frequency, and waveform of the fluctuation torque Tf depending on the magnitude of the required torque Tr. For example, the fluctuation torque derivation unit 24 may be capable of keeping at least one of the fluctuation range, frequency, and waveform of the fluctuation torque Tf constant regardless of the magnitude of the required torque Tr.

[0025] When the gain G of the torque fluctuation Tf is input from the motor torque control unit 25, the torque fluctuation derivation unit 24 can correct the torque fluctuation Tf based on the input gain G. For example, the torque fluctuation derivation unit 24 can multiply the torque fluctuation Tf by the gain G, thereby deriving a new torque fluctuation (Tf×G). The gain G will be described in detail later.

[0026] The motor torque control unit 25 derives a target torque Tg (see FIG. 2C) by adding a fluctuating torque (Tf or Tf×G) to the required torque Tr, and is able to control the torque of the motor 50 based on the derived target torque Tg. FIG. 2C shows an example of the change over time of the target torque Tg.

[0027] The motor torque control unit 25 is capable of determining whether the vehicle 1 is in a steady state or a transient state based on, for example, vehicle state quantity data (acceleration data and angular velocity data) obtained from the vehicle state quantity sensor 12. The "steady state" refers to a state in which the acceleration data and angular velocity data are equal to or less than a predetermined value (threshold value). The "steady state" includes constant-speed straight-line traveling. The "steady state" also includes a state in which the vehicle travels at a speed within a range recognized as constant-speed straight-line traveling when the steering angle is 0° or a very small angle. The "transient state" refers to a state different from the "steady state." The "transient state" includes, for example, lane changes and turns. The "transient state" also includes, for example, steady-state circular turns. When the steering angle is greater than a predetermined value (threshold value), the vehicle 1 is turning and can be said to be in a "transient state."

[0028] The motor torque control unit 25 is capable of, for example, changing the gain G of the fluctuation torque Tf in accordance with the road surface conditions. For example, when the vehicle 1 is in a transient state, the motor torque control unit 25 is capable of changing the gain G of the fluctuation torque Tf in accordance with the road surface conditions. The motor torque control unit 25 is capable of determining the road surface conditions based on the estimated μ obtained by the road surface μ estimator 22, for example. For example, when the estimated μ is greater than a predetermined value (threshold), the motor torque control unit 25 is capable of determining that the road surface conditions are a high road friction coefficient road. For example, when the estimated μ is equal to or less than a predetermined value (threshold), the motor torque control unit 25 is capable of determining that the road surface conditions are a low road friction coefficient road.

[0029] When the motor torque control unit 25 determines that the road surface condition is a road with a high friction coefficient, it can set the gain G of the fluctuation torque Tf to Ga (first gain). When the motor torque control unit 25 determines that the road surface condition is a road with a low friction coefficient, it can set the gain G of the fluctuation torque Tf to Gb (second gain) that is larger than Ga. Ga and Gb are values ​​larger than 1.

[0030] The motor torque control unit 25 can determine whether or not the fluctuating torque Tf needs to be added to the required torque Tr, for example, based on a control flag 32 described below. For example, when the control flag 32 indicates a torque fluctuation control mode, the motor torque control unit 25 can derive the target torque Tg by adding the fluctuating torque Tf to the required torque Tr. 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 (e.g., 17 Hz, 20 Hz, or 24 Hz). For example, when the control flag 32 indicates a normal mode, the motor torque control unit 25 can set the required torque Tr as the target torque Tg. 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.

[0031] The storage unit 30 stores data (thresholds 31) regarding the various thresholds described above. The thresholds 31 include, for example, a threshold for acceleration data, a threshold for angular velocity data, a threshold for steering angle, and a threshold for estimated μ. The storage unit 30 stores, for example, a control flag 32 input from a control flag input unit 40 (described later). The storage unit 30 may store, for example, a program executed by the control unit 20. This program causes the control unit 20 to execute a series of procedures for controlling the entire vehicle 1. The storage unit 30 is configured, for example, by a random access memory (RAM), a read-only memory (ROM), an auxiliary storage device (such as a hard disk), etc.

[0032] The control flag input unit 40 is capable of receiving input of a control flag 32 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 32 in the storage unit 30. For example, when the driver simultaneously presses and holds the left and right paddle shifters again after previously storing "1" as the control flag 32 in the storage unit 30, the control flag input unit 40 can store "0" as the control flag 32 in the storage unit 30. For example, when the driver simultaneously presses and holds the left and right paddle shifters again after previously storing "0" as the control flag 32 in the storage unit 30, the control flag input unit 40 can store "1" as the control flag 32 in the storage unit 30.

[0033] When the control flag 32 is "1", it means that the mode is, for example, a torque fluctuation control mode. When the control flag 32 is "0", it means that the mode is, for example, a normal mode in which periodic torque fluctuation control is not performed. Note that the values ​​that the control flag 32 can take are not limited to those described above.

[0034] The motor 50 is configured to drive the steered wheels of the vehicle 1. The motor 50 is capable of driving the steered wheels of the vehicle 1 in accordance with the target torque Tg input from the motor torque control unit 25. In this specification, the steered wheels refer to at least one of the front wheels and the rear wheels. One motor 50 may be provided for the front wheels, and one motor 50 may be provided for the rear wheels. In this case, the cruise control unit 21 may be capable of controlling the motor 50 for the front wheels and the motor 50 for the rear wheels in common. Alternatively, the cruise control unit 21 may be capable of controlling the motor 50 for the front wheels and the motor 50 for the rear wheels independently of each other.

[0035] [Operation] Next, the operation of the driving control unit 21 will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining an example of a procedure for deriving and correcting the target torque Tg.

[0036] The cruise control unit 21 acquires an acceleration request from the accelerator operation amount sensor 11 (step S101). Next, the cruise control unit 21 derives a required torque Tr according to the acquired acceleration request (step S102). Next, when the control flag 32 input from the control flag input unit 40 indicates the torque fluctuation control mode (step S103; Y), the cruise control unit 21 derives a periodically fluctuating torque fluctuation Tf (step S104). If the cruise control unit 21 has derived the fluctuating torque Tf in step S104, the cruise control unit 21 derives a target torque Tg by adding the required torque Tr to the fluctuating torque Tf (step S105). On the other hand, when the control flag 32 input from the control flag input unit 40 indicates the normal mode (step S103; N), the cruise control unit 21 sets the required torque Tr to the target torque Tg (step S105).

[0037] Next, the driving control unit 21 determines whether the vehicle 1 is in a transient state (step S106). As a result, if the vehicle 1 is not in a transient state, i.e., if the vehicle 1 is in a steady state (step S106; N), the driving control unit 21 controls the torque of the motor 50 based on the target torque Tg without periodic torque fluctuations. On the other hand, if the vehicle 1 is in a transient state, the driving control unit 21 determines whether the road surface conditions of the lane on which the vehicle 1 is traveling are a low road friction coefficient road (step S107). As a result, if the road surface conditions of the lane on which the vehicle 1 is traveling are not a low road friction coefficient road, i.e., if the road surface conditions of the lane on which the vehicle 1 is traveling are a high road friction coefficient road (step S107; N), the driving control unit 21 multiplies the fluctuation torque Tf by a gain Ga for a high road friction coefficient road, thereby deriving a new fluctuation torque (Tf × Ga) (step S108). On the other hand, if the road surface condition of the lane on which the vehicle 1 is traveling is a road with a low road friction coefficient, the cruise control unit 21 multiplies the fluctuation torque Tf by a gain Gb for a road with a low road friction coefficient, thereby deriving a new fluctuation torque (Tf × Gb) (step S109). In this way, the target torque Tg is derived and corrected.

[0038] Thereafter, the driving control unit 21 derives the target torque Tg by adding a fluctuating torque (Tf×Ga or Tf×Gb) to the required torque Tr, and controls the torque of the motor 50 based on the derived target torque Tg. In this manner, the torque of the motor 50 is controlled.

[0039] Next, the operation of the driving control unit 21 will be described with reference to FIG.

[0040] FIG. 4(A) shows an example of the waveform of the target torque Tg. FIG. 4(B) shows an example of the time change of the road surface μ estimated value (estimated μ). FIG. 4(C) shows an example of the time change of the on / off of the torque fluctuation control activation switch. The on / off of the torque fluctuation control activation switch corresponds to "1" or "0" of the control flag 32 described above. FIG. 4(D) shows an example of the time change of the state of the vehicle 1. FIG. 4(D) illustrates an example of the state of the vehicle 1 being either the steady state described above or the transient state described above.

[0041] First, the vehicle 1 is in a steady state, and the torque fluctuation control activation switch is off. Furthermore, the road surface μ estimated value (estimated μ) is μa, and the road surface on which the vehicle 1 is traveling is a high μ road surface. Furthermore, the torque of the motor 50 is controlled by the target torque Tg, which does not have periodic torque fluctuations. At this time, the driver inputs the control flag 32, which indicates the torque fluctuation control mode, via the control flag input unit 40 at time ta. Then, the cruise control unit 21 starts to control the torque of the motor 50 based on the periodically fluctuating target torque Tg (= Tr + Tf), based on the control flag 32 input from the control flag input unit 40.

[0042] Then, at time tb, the road surface μ estimated value (estimated μ) changes from μa to μb. The cruise control unit 21 determines that the road surface on which the vehicle 1 is traveling is still a high μ road surface, and continues to control the torque of the motor 50 based on the periodically fluctuating target torque Tg (= Tr + Tf). Then, when the cruise control unit 21 detects at time tc that the vehicle 1 has entered a transient state, it multiplies the fluctuating torque Tf by a gain Ga for a high road friction coefficient road, and thereby begins to control the torque of the motor 50 based on the target torque Tg (= Tr + Tf × Ga) whose amplitude fluctuates more significantly. The cruise control unit 21 controls the torque of the motor 50 based on the target torque Tg (= Tr + Tf × Ga) whose amplitude fluctuates more significantly from then until time td (Δt1).

[0043] At time td, the road surface friction coefficient estimated value (estimated μ) changes from μb to μc, which is lower than μb. The cruise control unit 21 then determines that the road surface on which the vehicle 1 is traveling has changed to a low-μ road surface and multiplies the fluctuating torque Tf by a gain Gb for low-friction-coefficient roads. As a result, the cruise control unit 21 begins controlling the torque of the motor 50 based on the target torque Tg (=Tr+Tf×Gb) whose amplitude fluctuates more significantly. Thereafter, while there is no change in the traveling state of the vehicle 1 or the road surface friction coefficient estimated value (estimated μ) (Δt2), the cruise control unit 21 controls the torque of the motor 50 based on the target torque Tg (=Tr+Tf×Gb) whose amplitude fluctuates more significantly. In this way, the cruise control unit 21 changes the magnitude of the periodic fluctuations in the target torque Tg based on the traveling state of the vehicle 1 and the road surface friction coefficient estimated value (estimated μ).

[0044] [Effects] Next, effects of the control unit 20 according to the embodiment of the present disclosure will be described.

[0045] In this embodiment, in a vehicle 1 driven by a motor, a target torque Tg is derived by adding a periodically fluctuating torque Tf to a required torque Tr corresponding to an acceleration request, and the torque of the motor 50 is controlled based on the derived target torque Tg. When the vehicle 1 is in a transient state, the gain G of the fluctuating torque Tf changes depending on road conditions. This allows the driver to easily grasp road conditions and the grip of the vehicle 1 during transient states, such as lane changes and curve driving, and provides a sense of security and a positive response when steering. In this way, the improved driver information in this embodiment provides the driver with a sense of security and a positive response when steering. In addition, the appropriate vibration provides the driver with a driving feel similar to that of an internal combustion engine vehicle.

[0046] In this embodiment, it is determined whether the vehicle 1 is in a steady state or a transient state based on the acceleration data and angular velocity data obtained by the vehicle state quantity sensor 12. Furthermore, the friction coefficient (estimated μ) of the road surface on which the vehicle 1 is traveling is estimated based on the road surface state quantity data obtained by the road surface state quantity sensor 13, and the road surface conditions are determined based on the estimated μ. This makes it easier for the driver to grasp the road surface conditions and the grip of the vehicle 1 in a transient state, such as changing lanes or driving around a curve, and allows the driver to feel a sense of security and a positive response when steering. In this way, the improved driver information in this embodiment allows the driver to feel a sense of security and a positive response when steering. Furthermore, the appropriate vibration allows the driver to feel a driving sensation similar to that of an internal combustion engine vehicle.

[0047] In this embodiment, when the estimated μ is greater than a predetermined value (threshold), the road surface condition is determined to be a high friction coefficient road, and the gain G of the fluctuating torque Tf is set to Ga. Also, when the estimated μ is equal to or less than the predetermined value (threshold), the road surface condition is determined to be a low friction coefficient road, and the gain G of the fluctuating torque Tf is set to Gb, which is greater than Ga. This allows the driver to easily grasp the road surface condition and the grip of the vehicle 1 during transient conditions, such as lane changes and curve driving, and provides a sense of security and a positive response when steering. Thus, in this embodiment, the improved driver information provides the driver with a sense of security and a positive response when steering. Furthermore, the appropriate vibration provides the driver with a driving feel similar to that of an internal combustion engine vehicle.

[0048] In this embodiment, whether or not the fluctuating torque Tf needs to be added to the required torque Tr is determined based on the control flag 32 input via the control flag input unit 40 provided in the vehicle 1, and when the control flag 32 indicates the torque fluctuation control mode, the target torque Tg is derived by adding the fluctuating torque Tf to the required torque Tr. This makes it possible to obtain a driving feeling that meets the driver's needs.

[0049] 2. Modifications The present disclosure has been described above by giving embodiments, but the present disclosure is not limited to these embodiments and various modifications are possible.

[0050] In the above embodiment, one motor 50 may be provided for each front wheel and one for each rear wheel. In this case, the travel control unit 21 may be capable of controlling the motor 50 for the front wheels and the motor 50 for the rear wheels independently of each other. Furthermore, the motor torque control unit 25 may be capable of performing torque control for the front wheels and torque control for the rear wheels separately from each other.

[0051] In this case, the motor torque control unit 25 changes the gain G of the fluctuating torque Tf separately for the front wheels and the rear wheels, thereby appropriately adjusting the driving feel obtained from the front wheels and the driving feel obtained from the rear wheels, respectively, and as a result, the behavior of the vehicle 1 can be more accurately grasped.

[0052] 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.

[0053] Furthermore, the present disclosure may take the following forms. (1) A vehicle control device capable of controlling a vehicle traveling by motor drive, comprising a control unit capable of deriving a target torque by adding a periodically fluctuating torque to a required torque according to an acceleration request, and performing torque control of the motor based on the derived target torque, wherein the control unit is capable of changing a gain of the fluctuating torque in accordance with road surface conditions when the vehicle is in a transient state different from a steady state in which the acceleration and angular velocity of the vehicle are equal to or lower than predetermined values. (2) The vehicle control device described in (1), wherein the control unit is capable of determining whether the vehicle is in the steady state or the transient state based on acceleration data and angular velocity data obtained by a first sensor, and further capable of estimating a road surface friction coefficient based on road surface data obtained by a second sensor, and determining the road surface conditions based on the estimated road surface friction coefficient. (3) The vehicle control device according to (2), wherein the control unit is capable of determining that the road surface conditions are a high friction coefficient road and setting the gain of the fluctuating torque to a first gain when the road surface friction coefficient is greater than a predetermined value, and determining that the road surface conditions are a low friction coefficient road and setting the gain of the fluctuating torque to a second gain greater than the first gain when the road surface friction coefficient is equal to or less than the predetermined value. (4) The vehicle control device according to any one of (1) to (4), wherein the control unit is capable of determining whether the fluctuating torque needs to be added to the required torque based on a control flag input via an input unit provided in the vehicle, and is capable of deriving the target torque by adding the fluctuating torque to the required torque when the control flag indicates that the fluctuating torque needs to be added to the required torque.(5) A vehicle control device capable of controlling a vehicle traveling by motor drive, comprising: deriving a target torque by adding a periodically fluctuating torque to a required torque according to an acceleration request, and controlling the torque of the motor based on the derived target torque; and changing a gain of the fluctuating torque according to road surface conditions when the vehicle is in a transient state different from a steady state in which the acceleration and angular velocity are equal to or less than predetermined values.

[0054] The control unit 20 shown in FIG. 1 can be implemented by circuitry 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 a portion of the various functions of the control unit 20 shown in FIG. 1 by reading instructions from at least one non-transitory, tangible computer-readable medium. Such media 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 a portion of the various functions of the control unit 20 shown in FIG. 1. An FPGA is an integrated circuit designed to be configurable after manufacture to perform all or part of the various functions of control unit 20 shown in FIG.

Claims

1. A vehicle control device capable of controlling a vehicle driven by a motor, comprising a control unit capable of deriving a target torque by adding a periodically fluctuating torque to a required torque according to an acceleration request, and controlling the torque of the motor based on the derived target torque, wherein the control unit is capable of changing the gain of the fluctuating torque according to road surface conditions when the vehicle is in a transient state other than a steady state in which the acceleration and angular velocity are below a predetermined value.

2. A vehicle control device as described in claim 1, wherein the control unit is capable of determining whether the vehicle is in the steady state or the transient state based on acceleration data and angular velocity data obtained by a first sensor, and further, estimating a road surface friction coefficient based on road surface data obtained by a second sensor, and determining the road surface conditions based on the estimated road surface friction coefficient.

3. The vehicle control device according to claim 2, wherein the control unit is capable of determining that the road conditions are a high friction coefficient road when the road friction coefficient is greater than a predetermined value and setting the gain of the fluctuating torque to a first gain, and is capable of determining that the road conditions are a low friction coefficient road when the road friction coefficient is equal to or less than the predetermined value and setting the gain of the fluctuating torque to a second gain greater than the first gain.

4. A vehicle control device as described in claim 1, wherein the control unit determines whether or not it is necessary to add the fluctuating torque to the required torque based on a control flag input via an input section provided in the vehicle, and when the control flag indicates that it is necessary to add the fluctuating torque to the required torque, it is possible to derive the target torque by adding the fluctuating torque to the required torque.

5. A vehicle control device capable of controlling a vehicle driven by a motor, comprising: deriving a target torque by adding a periodically fluctuating torque to a required torque according to an acceleration request, and controlling the torque of the motor based on the derived target torque; and changing a gain of the fluctuating torque according to road surface conditions when the vehicle is in a transient state other than a steady state in which the acceleration and angular velocity are equal to or lower than a predetermined value.

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