Control device and control method

Abstract

To provide a control device and a control method capable of suppressing a sense of incongruity on driving operation from being imparted to a driver.SOLUTION: A control device includes a controller capable of individually driving, by respective motors, inner wheels and outer wheels of a vehicle. The controller sets a target speed with respect to a reference position in a vehicle width direction of the vehicle according to an input amount in an accelerator operation, and sets target rotation numbers respectively for the inner wheels and the outer wheels so as for the vehicle to travel at the target speed. When the vehicle travels turning, the controller changes the reference position toward the outer wheel side of the reference position during travelling straight.SELECTED DRAWING: Figure 1C

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, a technique has been proposed in which, when a vehicle turns a curve ahead, a target speed during turning is set based on the radius of curvature of the curve (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-89700 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, the target speed is changed when turning, so the vehicle turns at a speed different from the speed the driver expects depending on the amount of accelerator input (operation amount), which may make the driver feel uncomfortable with the driving operation.

[0005] The present invention has been made in view of the above, and has an object to provide a control device and a control method that can reduce the discomfort felt by the driver in relation to driving operations when the vehicle is turning. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, a control device according to the present invention includes a controller capable of individually driving an inner wheel and an outer wheel of a vehicle with a motor. The controller sets a target speed for a reference position in a vehicle width direction of the vehicle according to an input amount of an accelerator operation, and sets target rotation speeds for the inner wheel and the outer wheel so as to achieve the target speed. When the vehicle is turning, the reference position is shifted to the outer wheel side from the reference position when the vehicle is running straight ahead.

[0007] The control device according to the present invention controls a motor of a vehicle that drives an inner wheel and an outer wheel separately. When traveling straight, the control device sets a target speed according to an input amount of accelerator operation and controls the number of revolutions of the motor so that the vehicle moves at the target speed, and when traveling in a corner, the control device sets a target speed of the outer wheel according to the input amount of accelerator operation and controls the number of revolutions of the motor so that the outer wheel moves at the target speed. Effect of the Invention

[0008] According to the present invention, it is possible to reduce the sense of discomfort felt by the driver in relation to driving operations when the vehicle is turning. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1A is a diagram for explaining an overview of a control method performed by a control device according to a first embodiment. [Figure 1B] FIG. 1B is a diagram for explaining an outline of a control method by a control device according to the conventional technology. [Figure 1C] FIG. 1C is a diagram for explaining an outline of a control method performed by the control device according to the first embodiment. [Diagram 2] FIG. 2 is a block diagram showing the configuration of the control device according to the first embodiment. [Diagram 3] FIG. 3 is a diagram for explaining the coefficient information. [Figure 4] FIG. 4 is a flowchart showing a processing procedure executed by the controller of the control device. [Diagram 5] FIG. 5 is a diagram for explaining the outer wheel target rotation speed and the inner wheel target rotation speed during cornering. [Figure 6] FIG. 6 is a diagram illustrating a control method performed by the control device according to the second embodiment. [Figure 7] FIG. 7 is a diagram for explaining the outer ring coefficient and the inner ring coefficient according to the second embodiment. [Figure 8]FIG. 8 is a diagram for explaining the outer ring coefficient and the inner ring coefficient according to the second embodiment. [Figure 9] FIG. 9 is a diagram for explaining a control device according to the third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of a control device and a control method disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below.

[0011] (First embodiment) First, a control method by the control device according to the first embodiment will be described below with reference to Figures 1A to 1C. Figures 1A and 1C are diagrams for explaining an outline of the control method by the control device according to the first embodiment. Figure 1B is a diagram for explaining an outline of the control method by the control device according to the conventional technology.

[0012] As shown in Fig. 1A, the vehicle V according to the first embodiment is a personal mobility or a relatively small mobility that is used by a user such as an elderly person or a physically disabled person to assist the user in moving. In the following, a user who rides in the vehicle V may be referred to as a driver D.

[0013] The vehicle V is, for example, a one-seater vehicle, but may be a vehicle that can accommodate two or more people. Also, the vehicle V is a cart type or wheelchair type as shown in Fig. 1A, but is not limited to this, and may be of various types, for example, a stand-up type.

[0014] The vehicle V includes a control device 10, a steering wheel 11, front wheels 50, and rear wheels 60. The control device 10 controls the entire vehicle V. The detailed configuration of the control device 10 will be described later with reference to FIG.

[0015] The steering wheel 11 is operated by a driver D. For example, when the driver D desires to turn the vehicle V, the driver D operates the steering wheel 11, and the front wheels 50 are steered according to the steering angle of the steering wheel 11, causing the vehicle V to turn.

[0016] The front wheels 50 and the rear wheels 60 are provided on the left and right sides of the vehicle V (the right front wheel 50 and the right rear wheel 60 are not visible in FIG. 1A). In other words, the vehicle V is a four-wheel vehicle equipped with multiple (four in this case) wheels. Note that the number of wheels described above is merely an example and is not limiting.

[0017] The front wheels 50 are steered wheels. Specifically, the front wheels 50 are directly or indirectly connected to the steering wheel 11, and are steered by the driver D operating the steering wheel 11.

[0018] The rear wheels 60 are drive wheels. Specifically, a motor 70 is connected to each of the left and right rear wheels 60. The motor 70 is controlled by the control device 10. In more detail, when an accelerator (not shown) provided near the steering wheel 11 is operated by the driver D, the control device 10 controls the motor 70 to rotate the rear wheels 60 so as to reach a target speed according to the input amount (operation amount) of the accelerator operation, thereby causing the vehicle V to travel.

[0019] In the above, a vehicle V in which the front wheels 50 are steered wheels and the rear wheels 60 are driven wheels is given as an example, but this is not limited to this and the vehicle may be of another type, such as a four-wheel drive vehicle in which the front wheels 50 also function as driven wheels.

[0020] In the conventional vehicle, for example, when turning a curve, the target speed is set based on the radius of curvature of the curve. In such a case, the vehicle changes the target speed and turns at a speed different from the speed expected by the driver depending on the amount of accelerator operation. Therefore, the driver may feel uncomfortable with the driving operation.

[0021] Therefore, the control device 10 according to this embodiment is configured to make it difficult for the driver D to feel uncomfortable with the driving operation when the vehicle V is turning.

[0022] In addition, in the vehicle according to the conventional technology, the driver may feel fear, discomfort, and the like in addition to the discomfort described above when the vehicle turns. This will be described with reference to FIG. 1B. FIG. 1B shows a schematic diagram of a transition of a reference position (see white arrow) that serves as a reference when controlling the speed of the vehicle V when the vehicle V travels around a curve and turns. In FIG. 1C and other figures described later, the reference position may be indicated by a solid black arrow.

[0023] Also, FIG. 1B shows an example in which the vehicle V turns to the right. Therefore, the rear wheel 60L on the left side of the vehicle V becomes the "outer wheel" when turning. In the following, the rear wheel 60L may be referred to as the "outer wheel 60L". In addition, the rear wheel 60R on the right side of the vehicle V becomes the "inner wheel" when turning. In the following, the rear wheel 60R may be referred to as the "inner wheel 60R". Although not shown in the drawings, when the vehicle V turns to the left, the rear wheel 60L becomes the "inner wheel" and the rear wheel 60R becomes the "outer wheel".

[0024] When the accelerator is operated, the control device 10 sets a target speed according to the input amount of the accelerator operation. More specifically, the control device 10 sets a target speed for a reference position in the vehicle width direction of the vehicle V according to the input amount of the accelerator operation. Then, the control device 10 sets the target rotation speeds of the rear wheels 60R, 60L (the inner wheel 60R and the outer wheel 60L) so as to reach the set target speed. For example, when the vehicle V travels in a straight line, the control device 10 controls the rotation speeds of the left rear wheel motor 70L and the right rear wheel motor 70R, as shown by the arrow B1, so that the position of the vehicle center A in the vehicle width direction (left-right direction) becomes the reference position and the speed of the reference position becomes the target speed. In the following, the left rear wheel motor 70L and the right rear wheel motor 70R will be described as "motor 70" when there is no particular distinction between them.

[0025] Here, in the control device according to the prior art, even when the vehicle V turns, the same reference position as when the vehicle V runs in a straight line is used, and the motor 70 is controlled so that the speed at the reference position becomes the target speed, as shown by the dashed arrow Ba. Therefore, when the vehicle V turns with a constant input amount of accelerator operation, the speed of the outer wheel 60L side becomes higher than the target speed, so the driver feels that the vehicle is accelerating more than when the vehicle runs in a straight line, which may result in fear, discomfort, etc. Furthermore, when the steering wheel 11 is returned during turning, the speed of the outer wheel 60L side decreases to the target speed, so the driver feels that the vehicle is decelerating and may feel discomfort, etc.

[0026] Therefore, the control device 10 according to this embodiment is configured to make it difficult for the driver D to feel fear, discomfort, or the like when the vehicle V is turning.

[0027] 1C, when the vehicle V turns due to the operation of the steering wheel 11 by the driver D, the control device 10 according to this embodiment changes the reference position of the target speed during turning to the outer wheel 60L side from the reference position during straight-ahead driving, as shown by arrow B2. Specifically, the control device 10 changes the reference position of the target speed during turning to the position of the outer wheel 60L.

[0028] The control device 10 sets a reflection ratio of the inner wheel 60R and the outer wheel 60L with respect to the target rotation speed of the motor 70 according to the changed reference position. The reflection ratio is a ratio indicating how the target rotation speed of the motor 70 calculated according to the target speed is reflected on the inner wheel 60R and the outer wheel 60L. More precisely, the reflection ratio is a ratio indicating how the target rotation speed of the motor 70 calculated from the target speed is reflected on the right rear wheel motor 70R that drives the inner wheel 60R and the left rear wheel motor 70L that drives the outer wheel 60L. The reflection ratio is expressed as a ratio between an inner wheel coefficient and an outer wheel coefficient that are multiplied by the calculated target rotation speed of the motor 70.

[0029] In this way, when the vehicle is turning, the control device 10 changes the reference position to the outer wheel 60L side from the reference position during straight driving. In detail, the control device 10 sets the reflection ratio according to where the changed reference position is in the vehicle width direction of the vehicle V (here, the position of the outer wheel 60L). In the example of FIG. 1C, since the reference position is at the position of the outer wheel 60L, the reflection ratio is set so that the speed of the reference position (outer wheel 60L) becomes the target speed. Specifically, the outer wheel coefficient is set to "1" so that the outer wheel 60L (more precisely, the left rear wheel motor 70L that drives the outer wheel 60L) becomes the target rotation speed of the motor 70 calculated according to the target speed.

[0030] In order to turn the vehicle V while maintaining the speed of the outer wheel 60L at a target speed, the control device 10 sets the reflection ratio so that the speed of the inner wheel 60R is lower than the target speed. Specifically, the inner wheel coefficient is set to a value "less than 1" so that the rotation speed of the inner wheel 60R (more precisely, the right rear wheel motor 70R that drives the inner wheel 60R) is lower than the target rotation speed of the motor 70 calculated according to the target speed. As an example, when the steering angle of the steering wheel 11 is 15°, the inner wheel coefficient is set to "0.98".

[0031] Next, the control device 10 sets the target speed according to the input amount of accelerator operation and the target rotation speed of the inner wheel 60R and the outer wheel 60L according to the reflection ratio. For example, the control device 10 detects the input amount of accelerator operation by the driver and sets the target speed (e.g., 6 km / h) according to the detected input amount of accelerator operation. The control device 10 calculates the target rotation speed (e.g., 1000 rpm) of the motor 70 according to the target speed.

[0032] The control device 10 multiplies the calculated target rotation speed (1000 rpm here) of the motor 70 by an outer wheel coefficient (1 here) which is a reflection ratio, to set a target rotation speed (1000 rpm here) of the left rear wheel motor 70L which drives the outer wheel 60L. The control device 10 also multiplies the calculated target rotation speed (1000 rpm here) of the motor 70 by an inner wheel coefficient (0.98 here) which is a reflection ratio, to set a target rotation speed (980 rpm here) of the right rear wheel motor 70R which drives the inner wheel 60R.

[0033] Next, the control device 10 controls the motors 70 that drive the inner wheel 60R and the outer wheel 60L based on the set target rotation speeds. That is, the control device 10 controls the left rear wheel motor 70L that drives the outer wheel 60L to reach the set target rotation speed (1000 rpm). The control device 10 also controls the right rear wheel motor 70R that drives the inner wheel 60R to reach the set target rotation speed (980 rpm).

[0034] As a result, in this embodiment, when the vehicle V turns, the speed of the reference position becomes the speed (target speed) expected based on the input amount of accelerator operation, and the reference position is changed to the outer wheel 60L side, making it less likely that the driver will feel uncomfortable with the driving operation.

[0035] In addition, in this embodiment, when the vehicle V turns, the speed of the outer wheel 60L is maintained at the target speed, so the driver is less likely to feel accelerated than when driving in a straight line, and as a result, the driver is less likely to feel fear, discomfort, etc. In addition, in this embodiment, even if the steering wheel 11 is returned during turning, the speed of the reference position is maintained at the target speed, so the driver is less likely to feel decelerated, and as a result, the driver is less likely to feel discomfort, etc.

[0036] In this way, in the control device 10, when traveling straight, a target speed is set according to the input amount of accelerator operation, and the rotation speed of the motor 70 is controlled so that the vehicle V reaches the target speed. In the control device 10, when traveling in a turn, a target speed of the outer wheel 60L is set according to the input amount of accelerator operation, and the rotation speed of the motor 70 is controlled so that the outer wheel 60L reaches the target speed. As a result, when the vehicle V turns, the outer wheel 60L reaches a speed (target speed) expected according to the input amount of accelerator operation, making it possible to make it less likely that the driver will feel uncomfortable with the driving operation.

[0037] When the vehicle V finishes turning and starts traveling in a straight line, the control device 10 returns the reference position to the vehicle center A, as indicated by arrow B3. The control device 10 controls the motor 70 so that the speed at the reference position becomes a target speed according to the input amount of accelerator operation. Specifically, the control device 10 sets the outer wheel coefficient and the inner wheel coefficient to 1, respectively. As a result, the target rotation speed of the left rear wheel motor 70L and the target rotation speed of the right rear wheel motor 70R are set to be the same. Therefore, the left rear wheel motor 70L and the right rear wheel motor 70R have the same rotation speed (target rotation speed), and therefore the speed at the reference position becomes the target speed.

[0038] Next, the configuration of the control device 10 according to the first embodiment will be described in detail with reference to Fig. 2. Fig. 2 is a block diagram showing the configuration of the control device 10 according to the first embodiment. Note that in Fig. 2, only components necessary for explaining the features of this embodiment are shown as functional blocks, and descriptions of general components are omitted.

[0039] In other words, each component shown in Fig. 2 is a functional concept, and does not necessarily have to be physically configured as shown in the figure. For example, the specific form of distribution and integration of each functional block is not limited to that shown in the figure, and all or part of it can be functionally or physically distributed and integrated in any unit according to various loads, usage conditions, etc.

[0040] As shown in FIG. 2, the control device 10 is connected to an input amount sensor 40, a steering angle sensor 41, a vehicle speed sensor 42, a left rear wheel motor 70L, and a right rear wheel motor 70R.

[0041] The input amount sensor 40 detects the amount of accelerator operation input by the driver and outputs information indicating the detected amount of accelerator operation input to the control device 10.

[0042] The steering angle sensor 41 is a sensor that detects the steering angle (in other words, the steering amount (steering angle)) of the steering wheel 11 (see FIG. 1). The steering angle sensor 41 outputs information indicating the detected steering angle of the steering wheel 11 to the control device 10. Note that the information indicating the steering angle also includes information indicating the steering direction of the vehicle V.

[0043] The vehicle speed sensor 42 is a sensor that detects the speed of the vehicle V. The vehicle speed sensor 42 outputs information indicating the detected speed of the vehicle V to the control device 10.

[0044] The left rear wheel motor 70L is connected to the rear wheel 60L (see FIG. 1C) and drives the rear wheel 60L. The right rear wheel motor 70R is connected to the rear wheel 60R (see FIG. 1C) and drives the rear wheel 60R. In this way, the rear wheel (outer wheel when turning) 60L and the rear wheel (inner wheel when turning) 60R are driven by separate motors.

[0045] The control device 10 includes a controller (control unit) 20 and a storage unit 30. The storage unit 30 is realized by a storage device such as a ROM (Read Only Memory), a RAM (Random Access Memory), a flash memory, etc. The storage unit 30 stores target speed information 31, target rotational speed information 32, coefficient information 33, various programs, etc.

[0046] The target speed information 31 is information indicating a target speed corresponding to an input amount of accelerator operation, and is stored in advance in the storage unit 30. The target speed information 31 is set so that the target speed increases as the input amount of accelerator operation increases. As an example, the target speed information 31 is set to "3km / h" when the input amount of accelerator operation is "50%," and is set to "6km / h" when the input amount of accelerator operation is "100%. Note that the specific numerical values ​​of the input amount of accelerator operation and the target speed described above are merely examples and are not limiting.

[0047] The target rotation speed information 32 is information indicating the target rotation speed of the motor 70 calculated according to the target speed, and is stored in advance in the storage unit 30. The target rotation speed information 32 is set so that the target rotation speed increases as the target speed increases. As an example, the target rotation speed information 32 sets the target rotation speed to "500 rpm" when the target speed is "3 km / h", and sets the target rotation speed to "1000 rpm" when the target speed is "6 km / h". Note that the specific numerical values ​​of the target speed and the target rotation speed described above are merely examples and are not limited to these.

[0048] The coefficient information 33 is information indicating an inner wheel coefficient and an outer wheel coefficient corresponding to the steering angle of the steering wheel 11. Since the reflection ratio is expressed as the ratio between the inner wheel coefficient and the outer wheel coefficient, the coefficient information 33 can also be said to be information regarding the reflection ratio.

[0049] Here, the coefficient information 33 will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining the coefficient information 33. In the graph of Fig. 3, the horizontal axis represents the steering angle of the steering wheel 11, and the vertical axis represents the inner wheel coefficient and the outer wheel coefficient. In Fig. 3, the inner wheel coefficient is indicated by a dashed line, and the outer wheel coefficient is indicated by a solid line.

[0050] As shown in Fig. 3, in the coefficient information 33, the inside wheel coefficient is set to decrease as the steering angle increases. As an example, in the coefficient information 33, when the steering angle is "0°", the inside wheel coefficient is set to "1", and when the steering angle is "15°", the inside wheel coefficient is set to "0.98". In addition, in the coefficient information 33, when the steering angle is "30°", the inside wheel coefficient is set to "0.94", and when the steering angle is "45°", the inside wheel coefficient is set to "0.94". In addition, in the coefficient information 33, when the steering angle is "60°", the inside wheel coefficient is set to "0.92".

[0051] In the coefficient information 33, the outer wheel coefficient is set to be constant regardless of the steering angle. As an example, the outer wheel coefficient is set to "1" regardless of the steering angle in the coefficient information 33. Note that the specific numerical values ​​of the steering angle, inner wheel coefficient, and outer wheel coefficient described above are merely examples and are not limiting.

[0052] Returning to the explanation of FIG. 2, the controller 20 corresponds to a so-called processor. The controller 20 is realized by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphical Processing Unit), or the like. The controller 20 executes a program according to an embodiment (not shown) stored in the storage unit 30, using the RAM as a working area. The controller 20 can also be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0053] The controller 20 controls the vehicle V based on outputs from various sensors. For example, the controller 20 controls the left rear wheel motor 70L and the right rear wheel motor 70R based on outputs from the input amount sensor 40 and the steering angle sensor 41.

[0054] In this way, the controller 20 is configured to be able to individually drive the inner wheel 60R and the outer wheel 60L of the vehicle V with the motor 70. In other words, the control device 10 including the controller 20 controls the motor 70 of the vehicle V, which individually drives the inner wheel 60R and the outer wheel 60L.

[0055] Here, the processing procedure executed by the controller 20 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the processing procedure executed by the controller 20 of the control device 10. Note that the processing shown in Fig. 4 is repeatedly executed at predetermined intervals while the vehicle V is traveling.

[0056] 4, the controller 20 detects the input amount of accelerator operation and the steering angle of the steering wheel 11 (step S10). Specifically, the controller 20 detects the input amount of accelerator operation by the driver based on the output from the input amount sensor 40. The controller 20 also detects the steering angle of the steering wheel 11 based on the output from the steering angle sensor 41.

[0057] Next, the controller 20 sets a target speed of the vehicle V (step S11). Specifically, the controller 20 reads the target speed information 31 and sets a target speed according to the detected input amount of the accelerator operation. More specifically, the controller 20 sets the target speed with respect to a reference position in the vehicle width direction of the vehicle V according to the input amount of the accelerator operation.

[0058] Next, the controller 20 calculates a target rotation speed of the motor 70 (step S12). Specifically, the controller 20 reads the target rotation speed information 32, and calculates a target rotation speed according to the target speed set in step S11. In other words, the controller 20 calculates, as the target rotation speed, a rotation speed of the motor 70 that will result in the set target speed.

[0059] Next, the controller 20 determines whether the vehicle V is turning (step S13). For example, the controller 20 determines that the vehicle V is turning when the steering angle of the steering wheel 11 is a value indicating that the vehicle V is turning. Note that the value indicating that the vehicle V is turning is, for example, a steering angle other than 0° or a value outside a preset allowable range including 0°, but is not limited thereto.

[0060] When it is determined that the vehicle V is not turning (step S13, No), that is, when it is determined that the vehicle V is traveling straight, the controller 20 sets the reference position to a position during straight traveling (step S14). Specifically, the controller 20 sets the reference position to the vehicle center A (see arrows B1 and B3 in FIG. 1C).

[0061] On the other hand, when it is determined that the vehicle V is turning (step S13, Yes), the controller 20 changes the reference position according to the steering angle (step S15). For example, the controller 20 changes the reference position of the target speed during turning travel to the outer wheel 60L side from the reference position during straight travel (see arrow B2 in FIG. 1C).

[0062] Next, the controller 20 sets the outer wheel coefficient and the inner wheel coefficient, which are reflection ratios, according to the set reference position (step S16). Specifically, the controller 20 sets the reflection ratio according to where the reference position is in the vehicle width direction of the vehicle V and the steering angle. For example, when the vehicle is turning and the reference position is on the outer wheel 60L side, the controller 20 sets the outer wheel coefficient to 1 and the inner wheel coefficient to a value less than 1. Also, when the vehicle is traveling in a straight line and the reference position is the vehicle center A, the controller 20 sets the outer wheel coefficient and the inner wheel coefficient (in other words, the coefficient for the rear wheel 60L and the coefficient for the rear wheel 60R) to 1.

[0063] Next, the controller 20 sets the outer wheel target rotation speed and the inner wheel target rotation speed (step S17). Specifically, the controller 20 multiplies the target rotation speed of the motor 70 calculated according to the target speed by an outer wheel coefficient (for example, 1) which is a reflection ratio, to set the outer wheel target rotation speed of the left rear wheel motor 70L which drives the outer wheel 60L during cornering. Also, the control device 10 multiplies the calculated target rotation speed of the motor 70 by an inner wheel coefficient (for example, a value less than 1) which is a reflection ratio, to set the inner wheel target rotation speed of the right rear wheel motor 70R which drives the inner wheel 60R during cornering. Note that, since the coefficient for the rear wheel 60L and the coefficient for the rear wheel 60R are 1 during straight driving, the controller 20 sets the target rotation speed of the left rear wheel motor 70L and the target rotation speed of the right rear wheel motor 70R to the same rotation speed (target rotation speed).

[0064] Here, the target rotation speed of the outer wheel and the target rotation speed of the inner wheel during turning, which are set in step S17, will be described with reference to Fig. 5. Fig. 5 is a diagram for explaining the target rotation speed of the outer wheel and the target rotation speed of the inner wheel during turning. In the graph of Fig. 5, the horizontal axis represents the steering angle of the steering wheel 11, and the vertical axis represents the target rotation speed. In Fig. 3, the target rotation speed of the inner wheel is indicated by a dashed line, and the target rotation speed of the outer wheel is indicated by a solid line.

[0065] The outer wheel coefficient is set to 1 regardless of the steering angle (see FIG. 3). Therefore, the controller 20 multiplies the target rotation speed of the motor 70 (e.g., 1000 rpm) by the outer wheel coefficient (e.g., 1) to set the outer wheel target rotation speed (1000 rpm) of the left rear wheel motor 70L. Also, the inner wheel coefficient is set to decrease as the steering angle increases (see FIG. 3). Therefore, the controller 20 multiplies the target rotation speed of the motor 70 (e.g., 1000 rpm) by the inner wheel coefficient to set the target rotation speed of the left rear wheel motor 70L that decreases as the steering angle increases.

[0066] Returning to the explanation of FIG. 4, the controller 20 controls the motor 70 based on the set target rotation speed (step S18). For example, when turning, the controller 20 controls the left rear wheel motor 70L so that it becomes the set outer wheel target rotation speed (1000 rpm). When turning, the controller 20 controls the right rear wheel motor 70R so that it becomes the set inner wheel target rotation speed. When traveling in a straight line, the controller 20 controls the left rear wheel motor 70L and the right rear wheel motor 70R so that they become the same target rotation speed.

[0067] As described above, the control device 10 according to the embodiment includes the controller 20 that can drive the inner wheel 60R and the outer wheel 60L of the vehicle V individually with the motor 70. The controller 20 sets a target speed for a reference position in the vehicle width direction of the vehicle V according to the input amount of the accelerator operation, and sets the target rotation speeds of the inner wheel 60R and the outer wheel 60L, respectively, so that the target speed is reached. When the vehicle is turning, the controller 20 changes the reference position to the outer wheel 60L side from the reference position during straight running. As a result, when the vehicle V is turning, the speed of the reference position becomes the speed (target speed) expected according to the input amount of the accelerator operation, and the reference position is changed to the outer wheel 60L side, so that the driver is less likely to feel uncomfortable with the driving operation.

[0068] Moreover, the control device 10 according to the embodiment controls the motor 70 of the vehicle V, which drives the inner wheel 60R and the outer wheel 60L separately. When traveling straight, the control device 10 sets a target speed according to the input amount of accelerator operation, and controls the number of revolutions of the motor 70 so that the vehicle V reaches the target speed, and when traveling in a turn, sets a target speed of the outer wheel 60L according to the input amount of accelerator operation, and controls the number of revolutions of the motor 70 so that the outer wheel 60L reaches the target speed. As a result, when the vehicle V turns, the outer wheel 60L reaches a speed (target speed) expected according to the input amount of accelerator operation, making it possible to make it less likely that the driver will feel uncomfortable with the driving operation.

[0069] Also, the controller 20 changes the reference position in accordance with the steering angle of the steering wheel 11. Specifically, the controller 20 sets an outer wheel coefficient and an inner wheel coefficient, which are reflection ratios, in accordance with the set reference position. More specifically, the controller 20 sets the reflection ratio in accordance with where the reference position is in the vehicle width direction of the vehicle V and the steering angle. For example, when turning and the reference position is on the outer wheel 60L side, the controller 20 sets the outer wheel coefficient to 1 and the inner wheel coefficient to a value less than 1.

[0070] As a result, in this embodiment, it is possible to set the target rotation speeds of the motor 70 (motor 70L for the left rear wheel) that drives the inner wheel 60R and the motor 70 (motor 70R for the right rear wheel) that drives the outer wheel 60L to values ​​that correspond to the steering angle of the steering wheel 11. Therefore, in this embodiment, it is possible to make it less likely that the driver will feel uncomfortable with the driving operation.

[0071] Second embodiment Next, a control method by the control device 10 according to the second embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram for explaining the control method by the control device 10 according to the second embodiment. Fig. 6 shows a schematic transition of a reference position that serves as a reference when controlling the speed of the vehicle V as the vehicle V travels around a curve and turns. In the following, the same reference symbols are used for configurations common to the first embodiment, and description thereof will be omitted.

[0072] 6, in the control device 10 according to the second embodiment, when the vehicle V turns by operating the steering wheel 11, the reference position of the target speed during turning is gradually shifted toward the outer wheel 60L side from the reference position during straight-ahead driving, as shown by the arrow B2x. In other words, the controller 20 of the control device 10 shifts the reference position of the target speed during turning so that it moves stepwise toward the outer wheel 60L side from the reference position during straight-ahead driving.

[0073] Furthermore, when the operation of the steering wheel 11 is returned and the vehicle V transitions from turning to straight running, the controller 20 gradually changes the reference position of the target speed changed to the outer wheel 60L side toward the reference position for straight running, as shown by the arrow B2y. In other words, the controller 20 changes the reference position of the target speed changed to the outer wheel 60L side so that it moves stepwise toward the reference position for straight running (i.e., the vehicle center A).

[0074] Next, the controller 20 sets the inner wheel coefficient and the outer wheel coefficient according to the changed reference position. Next, the controller 20 sets the target rotation speeds of the inner wheel 60R and the outer wheel 60L according to the target speed according to the input amount of the accelerator operation and the reflection ratio. The controller 20 controls the motors 70 that drive the inner wheel 60R and the outer wheel 60L based on the set target rotation speeds.

[0075] In this way, in the second embodiment, the reference position is gradually changed according to the steering angle of the steering wheel 11, so that the change in behavior of the vehicle V caused by changing the reference position can be made smooth.

[0076] Here, the outer wheel coefficient and the inner wheel coefficient according to the second embodiment will be described with reference to Figs. 7 and 8. Figs. 7 and 8 are diagrams for explaining the outer wheel coefficient and the inner wheel coefficient according to the second embodiment. Note that the "reference position rotation speed" in Fig. 7 is the target rotation speed calculated from the target speed according to the input amount of the accelerator operation. Fig. 7 shows the reference position, the outer wheel coefficient, the outer wheel target rotation speed, the inner wheel coefficient, and the inner wheel target rotation speed that change according to the steering angle in this case, taking the case where the reference position rotation speed is 1000 rpm as an example. Note that the specific numerical values ​​shown in Fig. 7 are merely examples and are not limited to these.

[0077] FIG. 8 is a diagram for explaining each numerical value used when calculating the outer wheel coefficient and the inner wheel coefficient. In FIG. 8, point C is the turning center, and the distance from the turning center C to the vehicle center A is the turning radius E1. The length of the turning radius E1 varies depending on the steering angle. That is, the turning radius E1 becomes shorter as the steering angle increases. FIG. 8 also shows the reference position distance E2 from the vehicle center A to the reference positions B2x, B2y, the outer wheel distance E3 from the turning center C to the outer wheel 60L, and the inner wheel distance E4 from the turning center C to the inner wheel 60R.

[0078] First, the outer ring factor and the inner ring factor are calculated using the following formulas (1) and (2). Outer wheel coefficient = ((outer wheel distance E3) / (turning radius E1 + reference position distance E2)) × (vehicle characteristic coefficient) Formula (1) Inner wheel coefficient = ((inner wheel distance E4) / (turning radius E1 + reference position distance E2)) × (vehicle characteristic coefficient) Equation (2) The vehicle characteristic coefficients in equations (1) and (2) are coefficients for correcting the outer wheel coefficient and the inner wheel coefficient according to the characteristics of each vehicle.

[0079] In Fig. 7, when the rotation speed at the reference position is "1000 rpm", the steering angle is "0°", and the reference position distance E2 is "0", the outer wheel coefficient is "1" and the inner wheel coefficient is "1". Therefore, the outer wheel target rotation speed is "1000 rpm" when the rotation speed at the reference position (1000 rpm) is multiplied by the outer wheel coefficient (1). Also, the inner wheel target rotation speed is "1000 rpm" when the rotation speed at the reference position (1000 rpm) is multiplied by the inner wheel coefficient (1).

[0080] Also, Fig. 7 shows that when the rotation speed at the reference position is "1000 rpm", the steering angle is "30°", and the reference position distance E2 is "125", the outer wheel coefficient is "1.2" and the inner wheel coefficient is "0.96". Therefore, the outer wheel target rotation speed is "1200 rpm" when the rotation speed at the reference position (1000 rpm) is multiplied by the outer wheel coefficient (1.2). Also, the inner wheel target rotation speed is "960 rpm" when the rotation speed at the reference position (1000 rpm) is multiplied by the inner wheel coefficient (0.96).

[0081] Also, FIG. 7 shows that when the rotation speed at the reference position is "1000 rpm", the steering angle is "60°", and the reference position distance E2 is "250", the outer wheel coefficient is "1" and the inner wheel coefficient is "0.85". Therefore, the outer wheel target rotation speed is "1000 rpm" when the rotation speed at the reference position (1000 rpm) is multiplied by the outer wheel coefficient (1). Also, the inner wheel target rotation speed is "850 rpm" when the rotation speed at the reference position (1000 rpm) is multiplied by the inner wheel coefficient (0.85). The maximum value of the reference position distance E2 is half the length of the vehicle width (when the reference position is at the position of the outer wheel 60L), but is not limited to this.

[0082] As can be seen from Figure 7, as the steering angle increases from 0° to 30°, the target rotation speed of the outer wheel increases relative to the rotation speed at the reference position. Also, as the steering angle increases from 30° to 60°, the target rotation speed of the outer wheel decreases toward the rotation speed at the reference position. As the steering angle increases from 0° to 60°, the target rotation speed of the inner wheel increases relative to the rotation speed at the reference position.

[0083] In this way, by setting the outer wheel target rotation speed and the inner wheel target rotation speed according to the steering angle, the controller 20 can gradually change the reference position of the target speed during cornering toward the outer wheel 60L side from the reference position during straight running (see arrow B2x in FIG. 6). Also, when the operation of the steering wheel 11 is released and the vehicle V transitions from cornering to straight running, the controller 20 can gradually change the reference position of the target speed, which has been changed toward the outer wheel 60L side, toward the reference position during straight running (see arrow B2y in FIG. 6).

[0084] (First Modification) Next, a control device 10 according to a first modified example will be described. An acceleration sensor 43 mounted on a vehicle V is connected to the control device 10 according to the first modified example, as shown by an imaginary line in Fig. 2. The acceleration sensor 43 is a sensor that detects the acceleration of the vehicle V. More specifically, the acceleration sensor 43 is a sensor that detects the acceleration of the vehicle V in the direction of the outer wheel 60L. The acceleration sensor 43 outputs information indicating the detected acceleration of the vehicle V in the direction of the outer wheel 60L to the controller 20 of the control device 10.

[0085] The controller 20 determines whether or not the vehicle V is turning, based on the acceleration in the direction of the outer wheel 60L detected by the acceleration sensor 43. For example, in the process of step S13 in FIG. 4, the controller 20 determines that the vehicle V is turning when the acceleration in the direction of the outer wheel 60L exceeds a preset threshold value.

[0086] In this way, in the first modified example, the output of the acceleration sensor 43 is used, so that it is possible to accurately determine whether or not the vehicle V is turning.

[0087] (Second Modification) Next, a control device 10 according to a second modified example will be described. An inclination sensor 44 mounted on a vehicle V is connected to the control device 10 according to the second modified example, as shown by an imaginary line in Fig. 2. The inclination sensor 44 is a sensor that detects the inclination angle (e.g., the inclination angle in the front-rear direction and the inclination angle in the left-right direction) of the road surface on which the vehicle V runs. The inclination sensor 44 outputs information indicating the detected inclination angle of the road surface to the controller 20 of the control device 10.

[0088] The controller 20 sets an upper limit value for the target speed when it determines, based on the output from the inclination sensor 44, that the vehicle V is traveling on a road that slopes downward in the forward direction. For example, when it determines that the vehicle V is traveling on a road that slopes downward in the forward direction, the controller 20 sets the upper limit value so that the target speed of the vehicle V is lower than the target speed corresponding to the input amount of the accelerator operation.

[0089] As a result, in the second variant, the speed of the vehicle V when traveling on a road that slopes downward in the forward direction can be suppressed compared to a target speed corresponding to the input amount of accelerator operation, thereby making it less likely that the driver will feel fear when traveling on a road that slopes downward.

[0090] Furthermore, the controller 20 sets an upper limit value for the target speed when it determines, based on the output from the inclination sensor 44, that the vehicle V is traveling on a road that slopes downward toward the outer wheel 60L. For example, when it determines that the vehicle V is traveling on a road that slopes downward toward the outer wheel 60L, the controller 20 sets the upper limit value so that the target speed of the vehicle V is lower than the target speed corresponding to the input amount of the accelerator operation.

[0091] As a result, in the second modified example, the speed of the vehicle V when traveling on a road that slopes downward toward the outer wheel 60L can be suppressed compared to the target speed according to the input amount of accelerator operation. Therefore, it is possible to make it difficult for the driver to feel fear when traveling on a road that slopes downward.

[0092] (Third Modification) Next, a control device 10 according to a third modified example will be described with reference to Fig. 9. Fig. 9 is a diagram for explaining the control device 10 according to the third modified example.

[0093] 9, the controller 20 according to the third modification changes the reference position to the outer wheel side (the front wheel 50L here) of the left and right front wheels 50R, 50L of the vehicle V. In detail, the controller 20 according to the third modification changes the reference position to the outer wheel side (the front wheel 50L) of the left and right front wheels 50R, 50L of the vehicle V during cornering.

[0094] This allows the front wheels 50R, 50L, where the driver is more likely to sense the speed of the vehicle V, to be set as the reference position, thereby making it possible to further reduce the likelihood that the driver will feel uncomfortable when driving.

[0095] Further advantages and modifications may readily occur to those skilled in the art. Thus, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof. [Explanation of symbols]

[0096] 10 Control device 20 Controller 70 Motor

Claims

1. A controller is provided that can drive the inner and outer wheels of the vehicle individually using a motor; The controller: a target speed is set with respect to a reference position in a vehicle width direction of the vehicle according to an input amount of an accelerator operation, and target rotational speeds of the inner wheel and the outer wheel are respectively set so as to achieve the target speed; When the vehicle is turning, the reference position is changed to be closer to the outer wheel side than the reference position when the vehicle is traveling straight ahead. Control device.

2. The control device includes: changing the reference position in response to a steering angle; The control device according to claim 1 .

3. The control device includes: determining whether the vehicle is turning based on an acceleration in an outer wheel direction detected by an acceleration sensor mounted on the vehicle; The control device according to claim 1 .

4. The control device includes: shifting the reference position to the outer wheel side of the left and right front wheels of the vehicle; The control device according to claim 1 .

5. The control device includes: When the vehicle is traveling on a roadway that slopes downward in a forward direction, an upper limit value is set for the target speed. The control device according to claim 1 .

6. The control device includes: When the vehicle is traveling on a roadway that slopes downward toward the outer wheel, an upper limit value is set for the target speed. The control device according to claim 1 .

7. A control method executed by a controller capable of individually driving inner and outer wheels of a vehicle using a motor, comprising: setting a target speed with respect to a reference position in a vehicle width direction of the vehicle in accordance with an input amount of an accelerator operation, and setting target rotational speeds of the inner wheel and the outer wheel so as to achieve the target speed; When the vehicle is turning, the reference position is changed to be closer to the outer wheel side than the reference position when the vehicle is traveling straight ahead. Control methods.

8. A control device for controlling a motor of a vehicle that drives an inner wheel and an outer wheel separately, When the vehicle is traveling straight ahead, a target speed is set according to an input amount of an accelerator operation, and the number of revolutions of the motor is controlled so that the vehicle reaches the target speed. During cornering, a target speed of the outer wheel is set in accordance with an input amount of the accelerator operation, and the rotation speed of the motor is controlled so that the outer wheel reaches the target speed. Control device.

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