Driving force control device, vehicle

Abstract

This driving force control device is provided in a vehicle comprising a driving unit that is able to separately drive the left wheels and the right wheels, and comprises: a torque calculating unit that calculates torque command values that are those of torque to be respectively generated by the left wheels and the right wheels; a travel direction calculating unit that calculates the current travel direction of the vehicle; and a target travel direction calculating unit that uses at least one among information about the road surface on which the vehicle is traveling and information about the outside of the vehicle, to calculate a future target travel direction of the vehicle. The torque calculating unit calculates a computation command value so that the current travel direction approaches the target travel direction, and outputs the computation command value to the driving unit as the torque command value.

Description

[Technical Field]

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

[0002] In vehicle control, a technology known as torque vectoring is known, which applies different driving forces to left and right drive wheels. Patent Document 1 discloses a motor input / output coefficient correction device for an independent-wheel-drive electric vehicle, in which left and right wheels are driven independently by individual electric motors and input command values ​​for each electric motor are determined from output target values ​​according to a predetermined motor input / output coefficient between these input command values ​​and output target values, comprising: target traveling direction detection means for detecting a target traveling direction of the vehicle based on the steering direction input to the steering means of the independent-wheel-drive electric vehicle; actual traveling direction detection means for detecting the actual traveling direction of the independent-wheel-drive electric vehicle; and motor input / output coefficient correction means for correcting the predetermined motor input / output coefficient based on the detection results by these means so that the actual traveling direction approaches the target traveling direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-184911 Summary of the Invention [Problem to be solved by the invention]

[0004] The invention described in Patent Document 1 is premised on steering, and there is room for improvement. [Means for solving the problem]

[0005] A driving force control device according to a first aspect of the present invention is a driving force control device for a vehicle having a drive unit capable of driving left and right wheels independently, and includes: a torque calculation unit that calculates a torque command value which is a torque to be generated in each of the left and right wheels; a traveling direction calculation unit that calculates a current traveling direction of the vehicle; and a target traveling direction calculation unit that calculates a future target traveling direction of the vehicle using at least one of information on a road surface on which the vehicle is traveling and information on the external environment of the vehicle, wherein the torque calculation unit calculates a calculated command value to bring the current traveling direction closer to the target traveling direction, and outputs the calculated command value to the drive unit as the torque command value. and an operation acquisition unit that acquires operation information, which is information regarding an operation input by a user to drive the vehicle and includes at least information regarding a steering angle, wherein the torque calculation unit determines whether to override the calculated command value with the user command value based on a deviation between a user command value, which is the torque command value based on the operation information, and the calculated command value, which is the torque command value based on the target traveling direction, and the torque calculation unit evaluates a deviation between a ratio of right wheel torque to left wheel torque in the user command value and a ratio of right wheel torque to left wheel torque in the calculated command value. . A vehicle according to a second aspect of the present invention is a vehicle including a drive unit capable of driving left and right wheels independently, and a drive force control device that outputs to the drive unit a torque command value that instructs the drive unit on the torque to be generated at each of the left and right wheels, wherein the drive force control device includes a torque calculation unit that calculates the torque command value, a traveling direction calculation unit that calculates a current traveling direction of the vehicle, and a target traveling direction calculation unit that calculates a future target traveling direction of the vehicle using at least one of information on a road surface on which the vehicle is traveling and information on the external environment of the vehicle, and the torque calculation unit calculates a calculation command value to bring the current traveling direction closer to the target traveling direction, and outputs the calculation command value to the drive unit as the torque command value. The driving force control device further includes an operation acquisition unit that acquires operation information that is information regarding an operation input by a user to drive the vehicle and that includes at least information regarding a steering angle, and the torque calculation unit determines whether to override the calculated command value with the user command value based on a deviation between a user command value that is the torque command value based on the operation information and the calculated command value that is the torque command value based on the target traveling direction, and the torque calculation unit evaluates the deviation between the ratio of right wheel torque to left wheel torque in the user command value and the ratio of right wheel torque to left wheel torque in the calculated command value. [Effects of the Invention]

[0006] According to the present invention, the driving forces of the left and right wheels can be controlled based on information about the road surface and the outside world. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing the configuration of a vehicle according to a first embodiment; [Figure 2] Diagram showing the definition of an angle [Figure 3] Diagram showing the concept of the driving force table [Figure 4] An example of an override table [Figure 5] Hardware configuration diagram of the driving force control device [Figure 6] Flowchart showing the processing of the driving force control device [Figure 7] Time chart showing the operation of the driving force control device [Figure 8] 1 is a diagram showing the configuration of a vehicle according to a second embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0008] -First embodiment- A first embodiment of a driving force control device will be described below with reference to FIGS.

[0009] FIG. 1 is a configuration diagram of a vehicle C including a driving force control device 10 according to a first embodiment. The vehicle C includes the driving force control device 10, an external sensor 21, an internal sensor 22, a GPS receiver 23, a map information storage device 24, a navigation device 25, and a drive unit 27. Hereinafter, a person who rides in and operates the vehicle C will be referred to as a "user." The driving force control device 10 outputs a torque command value to the drive unit 27. The torque command value is a summary of information on the torques to be generated in the left and right wheels of the vehicle C. The driving force control device 10 includes, as its functions, a current traveling direction calculation unit 11, a target traveling direction calculation unit 12, a change amount calculation unit 13, a torque calculation unit 14, and an operation acquisition unit 15. The driving force control device 10 stores a steering torque correspondence table 16, a driving force table 18, and an override table 19.

[0010] The drive unit 27 includes a drive device 28 and a driving force distribution device 29. The drive device 28 is a power generation source that generates power to drive the vehicle C. The drive device 28 is, for example, an engine or a motor. The driving force distribution device 29 distributes the power generated by the drive device 28 to the left and right wheels of the vehicle C based on the torque command value output by the driving force control device 10. The driving force distribution device 29 is, for example, an electronically controllable differential gear.

[0011] The external sensor 21 is a sensor that senses the outside of the vehicle C. Examples of the external sensor 21 include a camera, a laser range finder, and a LiDAR (light detection and ranging). The internal sensor 22 is a sensor that senses the inside of the vehicle C. Examples of the internal sensor 22 include a yaw rate sensor, a steering angle sensor, and a depression amount sensor. The yaw rate sensor may be a gyro sensor that can measure multiple attitude angles including the yaw angle of the vehicle C. The steering angle sensor detects the steering angle of the steering wheel by the user. The depression amount sensor detects the amount of depression of the accelerator pedal and the brake pedal by the user.

[0012] The GPS receiver 23 receives radio waves from multiple satellites that make up a satellite navigation system and analyzes the signals contained in the radio waves to calculate the vehicle's position, i.e., its latitude and longitude. The GPS receiver 23 outputs the calculated latitude and longitude to the driving force control device 10. The map information storage device 24 is a non-volatile storage device that stores map information including the area in which the vehicle C will travel. The map information includes, for example, the latitude and longitude of nodes such as road edges and intersections, as well as detailed information about the shapes of the links connecting the nodes. Detailed information about the shape of the links includes the number of lanes, the spacing between lanes, the radius of curvature of the links, and auxiliary points on the links that indicate multiple latitudes and longitudes. When the user inputs a destination, the navigation device 25 calculates a route to the destination and outputs the route to the driving force control device 10.

[0013] In this embodiment, the yaw angle of vehicle C, i.e., the angle indicating the north-east-west and north-south directions, is referred to as the "vehicle angle θ." The vehicle angle θ is defined, for example, as the angle between the front direction of vehicle C and north, and takes a value greater than or equal to 0 degrees and less than 360 degrees. The vehicle angle θ of the current vehicle C is particularly referred to as the "current vehicle angle θn," and the vehicle angle θ of vehicle C that should be in the future is referred to as the "target vehicle angle θt."

[0014] The operation acquisition unit 15 acquires operation information of the accelerator pedal and steering wheel by the user. In other words, the operation acquisition unit 15 acquires information regarding operation inputs by the user to drive the vehicle C (hereinafter referred to as "operation information"). The operation information includes at least information regarding the steering angle.

[0015] The current traveling direction calculation unit 11 calculates the current vehicle angle θn using the outputs of the external sensor 21 and the internal sensor 22. The current traveling direction calculation unit 11 can calculate the current vehicle angle θn using, for example, the following methods. The current traveling direction calculation unit 11 can calculate the current vehicle angle θn by integrating the output of the yaw rate sensor included in the internal sensor 22. The current traveling direction calculation unit 11 can also calculate the current vehicle angle θn by map matching or the like by combining the output of the external sensor 21 with map information stored in the internal sensor 22. Furthermore, the current traveling direction calculation unit 11 can calculate the current vehicle angle θn using the outputs of the GPS receiver 23 at different times.

[0016] The target traveling direction calculation unit 12 calculates the target vehicle angle θt using the outputs of the external sensor 21, the internal sensor 22, and the GPS receiver 23, etc. The calculation of the target vehicle angle θt by the target traveling direction calculation unit 12 does not use operation information, particularly steering angle information. The specific method for calculating the target vehicle angle θt is not particularly limited, but it can be calculated, for example, as follows. The target traveling direction calculation unit 12 first identifies the future position of vehicle C on the road based on the shape of the link on which vehicle C is currently traveling, the current position of vehicle C, the traveling direction of vehicle C on the link, and distance D. For example, it is assumed here that vehicle C travels in the center of the traveling lane. The "traveling direction on the link" here refers to information indicating whether vehicle C is traveling south or north on a link that extends north-south, for example. Next, the target traveling direction calculation unit 12 calculates an appropriate vehicle angle θ for vehicle C at that position and sets this as the target vehicle angle θt. The appropriate host vehicle angle θ is the angle at which the center line of vehicle C is parallel to the nearest lane marking that defines the driving lane.

[0017] Fig. 2 is a diagram showing the definition of angles in this embodiment. In Fig. 2, the top is north. Two vehicles C are displayed in Fig. 2, with the bottom showing the current position and the top showing the future position. The angle between the current traveling direction of vehicle C and north is the current host vehicle angle θn, and the angle between the future traveling direction of vehicle C and north is the target host vehicle angle θt.

[0018] The change amount calculation unit 13 calculates a target slip angle ω, which is the difference between the target vehicle angle θt and the current vehicle angle θn. For example, the target slip angle ω is defined as the value obtained by subtracting the current vehicle angle θn from the target vehicle angle θt. Note that if the target slip angle ω is a positive value, the torque on the left wheel of vehicle C should be greater than the torque on the right wheel.

[0019] The torque calculation unit 14 calculates a calculated command value and a user command value, and outputs either one of them to the drive unit as a torque command value. The calculated command value is a torque command value calculated using the target traveling direction calculated by the target traveling direction calculation unit 12. Considering that the calculated command value is the basis of the output by the torque calculation unit 14, it can also be said that the torque calculation unit 14 determines whether or not to override the calculated command value with the user command value. However, if the user does not operate the steering wheel, the torque calculation unit 14 determines that there is no override.

[0020] The calculated command value and the user command value each include information on a torque command value for the right wheel and information on a torque command value for the left wheel. The calculated command value and the user command value may each be represented as individual numerical values ​​for the torque command value for the right wheel and the torque command value for the left wheel, or may be represented as a sum of the two and a ratio thereof, or may be represented as a sum of the two and a difference therebetween.

[0021] The torque calculation unit 14 refers to the driving force table 18 and the override table 19 to calculate the calculated command value. The torque calculation unit 14 refers to the steering torque correspondence table 16 to calculate the user command value.

[0022] The driving force table 18 is a lookup table created in advance, which shows the correspondence between the target slip angle ω and the target left-right driving force difference Td. However, in this embodiment, the driving force table 18 is merely described as a lookup table for convenience. In other words, it is not essential that the driving force table 18 be expressed in tabular form, and it may be expressed in other forms, such as a mathematical formula. Therefore, the driving force table 18 can also be called "correspondence information between angle difference and torque difference" which shows the correspondence between the target slip angle ω and the target left-right driving force difference Td.

[0023] FIG. 3 is a diagram showing the concept of the driving force table 18. FIG. 3 shows the correspondence between the target slip angle ω and the target left-right driving force difference Td. The driving force table 18 may also take into account the inclination of the road surface. In this case, the correspondence between the target slip angle ω and the target left-right driving force difference Td is shifted as shown by the dashed dotted line in FIG. 3. The target left-right driving force difference Td corresponding to the target slip angle ω is calculated in advance so that, for example, the yaw angle of the vehicle C changes by the same amount as the target slip angle ω after one control cycle of the driving force control device 10.

[0024] The steering torque correspondence table 16 is a lookup table created in advance, which shows the correspondence between the steering angle operated by the user and the user command value. For example, the steering torque correspondence table 16 is obtained by replacing the target slip angle ω on the vertical axis of the driving force table 18 shown in Figure 3 with the steering angle.

[0025] The override table 19 is a table created as appropriate by the torque calculation unit 14, and is a table that is referenced to determine whether or not to override the calculated command value with the user command value. However, in this embodiment, the override table 19 is merely described as a table for convenience. In other words, it is not essential that the override table 19 be expressed in table form, and it may be expressed in other forms, for example, as a mathematical formula. Therefore, the override table 19 can also be called "override determination information."

[0026] FIG. 4 is a diagram showing an example of the override table 19. In FIG. 4, two regions are shown based on a calculated command value calculated using a target traveling direction. These two regions are a first region shown by hatching and a second region not shown by hatching. The first region is a region where no override is performed, and the second region is a region where override is performed. The first region is a region surrounded by dashed lines L1 to L4, which will be described later. As described above, the calculated command value is a torque command value calculated using a target traveling direction, and the user command value is a torque command value calculated using operation information by a user. Hereinafter, the torque command value for the right wheel included in the calculated command value will be referred to as a calculated right wheel torque SR, and the torque command value for the left wheel included in the calculated command value will be referred to as a calculated right wheel torque SL.

[0027] The torque command value for the right wheel included in the user command value is called the user right wheel torque UR, and the torque command value for the left wheel included in the user command value is called the user right wheel torque UR. The ratio between the calculated left wheel torque SL and the calculated right wheel torque SR, or more precisely, the absolute value of the value obtained by dividing the calculated left wheel torque SL by the calculated right wheel torque SR, is called the calculated torque ratio Rs. The ratio between the user left wheel torque UL and the user right wheel torque UR, or more precisely, the absolute value of the value obtained by dividing the user left wheel torque UL by the user right wheel torque UR, is called the user torque ratio Ru. In FIG. 3, the region between the dashed lines L1 and L2 is a region where the absolute value of the difference between the calculated torque ratio Rs and the user torque ratio Ru is smaller than the threshold value α. In FIG. 4, the region between the dashed lines L3 and L4 is a region where the absolute value of the difference between the sum of the calculated left wheel torque SL and the calculated right wheel torque SR and the sum of the user left wheel torque UL and the user right wheel torque UR is smaller than the threshold value β.

[0028] In Fig. 4, square markers indicate calculated command values. When the user command values ​​are the values ​​indicated by the star markers (UL1, UR1), the torque calculation unit 14 outputs the calculated command value as the torque command value without overriding since the user command value is included in the first region. When the user command values ​​are the values ​​indicated by the triangular markers (UL2, UR2), the torque calculation unit 14 outputs the calculated command value as the torque command value without overriding since the user command value is included in the second region. Note that in this embodiment, the left and right wheels are steered based on the operation of the steering wheel by the user, regardless of whether an override is performed.

[0029] FIG. 5 is a hardware configuration diagram of the driving force control device 10. The driving force control device 10 includes a CPU 801, which is a central processing unit (CCU), a ROM 802, which is a read-only storage device, a RAM 803, which is a readable / writable storage device, and a communication device 805. The CPU 801 loads programs stored in the ROM 802 into the RAM 803 and executes them to perform the various calculations described above. The driving force control device 10 may be realized by a field programmable gate array (FPGA), which is a rewritable logic circuit, or an application specific integrated circuit (ASIC), which is an application specific integrated circuit, instead of the combination of the CPU 801, the ROM 802, and the RAM 803. Furthermore, the driving force control device 10 may be realized by a different combination of components, such as a combination of the CPU 801, the ROM 802, the RAM 803, and an FPGA, instead of the combination of the CPU 801, the ROM 802, and the RAM 803. The communication device 805 communicates with other devices installed in the vehicle C. The communication device 805 is compatible with communication standards such as CAN (registered trademark) and IEEE802.3.

[0030] 6 is a flowchart showing the processing of the driving force control device 10. In step S301, the current traveling direction calculation unit 11 calculates the current vehicle angle θn. The current vehicle angle θn may be calculated using the output of the internal sensor 22, or may be calculated using the position information of the vehicle C output by the GPS receiver 23. In step S302, the target traveling direction calculation unit 12 determines the distance D to the target point. The distance D may be, for example, the distance traveled in a predetermined time at the current speed of the vehicle C, or may be a preset fixed value. The predetermined time may be a preset fixed time, for example, one second, or one control cycle of the driving force control device 10.

[0031] In step S303, the target traveling direction calculation unit 12 calculates the target vehicle angle θt. The target traveling direction calculation unit 12 first identifies the future position of vehicle C on the road based on the shape of the link on which vehicle C is currently traveling, the current position of vehicle C, the traveling direction of vehicle C, and distance D. Next, the target traveling direction calculation unit 12 calculates an appropriate vehicle angle θ for vehicle C at that position, and sets this as the target vehicle angle θt. The appropriate vehicle angle θ is the angle at which the center line of vehicle C is parallel to the nearest lane marking. In step S304, the change amount calculation unit 13 calculates the target slip angle ω, which is the difference between the target vehicle angle θt and the current vehicle angle θn.

[0032] In the next step S305, the torque calculation unit 14 calculates the target left-right driving force difference Td corresponding to the target slip angle ω. Specifically, the torque calculation unit 14 references the driving force table 18 and reads the target left-right driving force difference Td corresponding to the target slip angle ω. However, if the torque calculation unit 14 determines, based on the information stored in the map information storage device 24, that the link on which the vehicle C is traveling is inclined, it changes the read target left-right driving force difference Td according to the degree of inclination. Note that the target left-right driving force difference Td may be an integer value that is positive when the torque of the right wheel is greater than the torque of the left wheel. In this case, the target left-right driving force difference Td is expressed as "+10" or "-3." The target left-right driving force difference Td may also be a combination of a sign specifying the larger side and a numerical value indicating the difference in magnitude. In this case, the target left-right driving force difference Td is expressed as "R10" or "L3."

[0033] In the following step S306, the torque calculation unit 14 calculates a calculated left wheel torque SL and a calculated right wheel torque SR using the target driving force difference Td calculated in step S305. The total value of the torque command values ​​for the left and right wheels is determined, for example, by the amount of accelerator pedal depression by the user or the legal speed of the link on which vehicle C is traveling. For example, if the target driving force difference Td is "R10" and the total value of the torque command values ​​for the left and right wheels is "50 N·m," the torque command value for the right wheel is calculated to be "30 N·m" and the torque command value for the left wheel is calculated to be "20 N·m."

[0034] In the following step S307, the torque calculation unit 14 creates an override table 19. The override table 19 is created using the torque command value for the right wheel and the torque command value for the left wheel calculated in step S306. In the following step S308, the torque calculation unit 14 identifies the user's steering amount included in the operation information, and calculates the user left wheel torque UL and the user right wheel torque UR by referring to the steering torque correspondence table 16. In the following step S309, the torque calculation unit 14 arranges the user command values ​​calculated in step S308, i.e., the user left wheel torque UL and the user right wheel torque UR, in the override table 19 created in step S307.

[0035] In the following step S310, the torque calculation unit 14 determines whether the user command value is in the override region in the override table 19, i.e., the second region. If the torque calculation unit 14 determines that the user command value is in the override region, the process proceeds to step S311, and if the torque calculation unit 14 determines that the user command value is not in the override region, the process proceeds to step S312. In step S311, the torque calculation unit 14 outputs the user command value as a torque command value and ends the process shown in Fig. 6. In step S312, the torque calculation unit 14 outputs the calculated command value as a torque command value and ends the process shown in Fig. 6.

[0036] FIG. 7 is a time chart showing the operation of the driving force control device 10. In FIG. 7, the further to the right in the figure, the later the time. From the top, FIG. 7 shows the changes over time in the vehicle angle, angular velocity, steering angle, and torque. The steering angle is always zero within the range shown in FIG. 7. In other words, the user is not operating the steering wheel. At time t10, vehicle C is traveling straight, and the current vehicle angle θn is "θ0". At time t10, the target traveling direction calculation unit 12 calculates that the target vehicle angle θt will remain unchanged at "θ0", and the calculated left wheel torque SL and the calculated right wheel torque SR are both set to "T3".

[0037] At time t11, the target traveling direction calculation unit 12 calculates the target vehicle angle θt at time t13 to be "θ1" based on information about the road surface on which the vehicle C is traveling, etc. Then, the torque calculation unit 14 identifies the target left-right driving force difference Td corresponding to the target slip angle "θ1-θ0" by referring to the driving force table 18, and calculates the calculated left wheel torque SL and the calculated right wheel torque SR using the sum of torques determined by factors such as the legal speed on the link on which the vehicle C is traveling. In the example shown in FIG. 7, the calculated left wheel torque SL is calculated to be "T4" and the calculated right wheel torque SR is calculated to be "T2". The torque calculation unit 14 outputs this torque command value to the drive unit 27, which causes the vehicle angle and angular velocity of the vehicle C to increase little by little.

[0038] At time t13, the change amount calculation unit 13 calculates the future target vehicle angle θt to be "θ1," that is, the same as the value calculated at time t11. Then, the torque calculation unit 14 sets the calculated left wheel torque SL and the calculated right wheel torque SR to "T3" because the target slip angle is zero and the target left / right driving force difference Td is also zero. As a result, the angular velocity of vehicle C becomes zero and the vehicle angle remains at "θ1." This concludes the explanation of Figure T1C.

[0039] According to the first embodiment described above, the following advantageous effects can be obtained. (1) The driving force control device 10 is provided in a vehicle C that includes a drive unit 27 capable of driving the left and right wheels independently. The driving force control device 10 includes a torque calculation unit 14 that individually calculates a calculated torque target value, which is the torque to be generated in each of the left and right wheels; a current traveling direction calculation unit 11 that calculates the current traveling direction of the vehicle C; and a target traveling direction calculation unit 12 that calculates a future target traveling direction of the vehicle C using at least one of information on the road surface on which the vehicle C is traveling and information on the external environment of the vehicle. The torque calculation unit 14 calculates the calculated torque target value so as to bring the current traveling direction closer to the target traveling direction. Therefore, the torque of the left and right wheels can be controlled regardless of the steering angle operation by the user.

[0040] (2) The drive unit 27 includes one drive device 28 and a drive force distribution device 29 that can distribute the output of the electric motor to the left and right wheels. Therefore, the present invention can be implemented in a vehicle C that includes one drive device 28.

[0041] (3) The torque calculation unit 14 calculates the calculated torque command value so that the current traveling direction coincides with the target traveling direction, thereby making it possible to make the traveling direction of the vehicle C coincide with the target traveling direction.

[0042] (4) The driving force control device 10 includes an operation acquisition unit 15 that acquires operation information related to an operation input by a user for driving the vehicle, including at least information related to the steering angle. The torque calculation unit 14 determines whether to override the calculated command value with the user command value based on the difference between the user command value, which is a torque target value based on the operation information, and the calculated command value, which is a torque command value based on the target traveling direction. This allows for control of the vehicle C that prioritizes user operation.

[0043] (Variation 1) Vehicle C may not accept driving operations by the user. In other words, vehicle C may be a vehicle that only performs autonomous driving. In this case, driving force control device 10 does not need to include operation acquisition unit 15, and torque calculation unit 14 always outputs a calculated command value without determining whether to override. In other words, driving force control device 10 can omit the processing from step S307 onwards in FIG. 6, and outputs the torque command value calculated in step S306.

[0044] (Variation 2) 6 may be reversed, with the target vehicle angle θt being estimated after step S301, and the distance D to the target point being determined after that. In this case, for example, based on the shape of the link on which vehicle C is currently traveling and the current position of vehicle C, the closest position at which the vehicle angle θ of vehicle C traveling along the road changes from the current vehicle angle θn by more than a predetermined angle is identified.

[0045] (Variation 3) In the first embodiment described above, the torque calculation unit 14 overrides the calculated command value with the user command value in the following two cases. That is, in the first case, the absolute value of the difference between the calculated torque ratio Rs and the user torque ratio Ru is greater than the threshold value α. In the second case, the absolute value of the difference between the sum of the calculated left wheel torque SL and the calculated right wheel torque SR and the sum of the user left wheel torque UL and the user right wheel torque UR is greater than the threshold value β. However, it is also possible to override only one of the cases, or to evaluate the difference instead of the ratio. Evaluating the difference instead of the ratio means evaluating whether the absolute value of the difference between the difference between the calculated left wheel torque SL and the calculated right wheel torque SR and the difference between the user left wheel torque UL and the user right wheel torque UR is greater than the threshold value γ.

[0046] This modification provides the following advantages. (5) The torque calculation unit 14 evaluates the difference between the ratio of the right wheel torque to the left wheel torque in the user command value and the ratio of the right wheel torque to the left wheel torque in the calculated command value, and determines whether or not to override. (6) The torque calculation unit 14 evaluates the difference between the right wheel torque and the left wheel torque in the user command value and the difference between the right wheel torque and the left wheel torque in the calculated command value, and determines whether or not to override.

[0047] (Variation 4) The target slip angle ω may be calculated simply by using the radius of curvature of the link on which vehicle C is traveling and the distance D. For example, if the radius of curvature of the link on which vehicle C is traveling is "r" and the distance D calculated in step S302 is "d", the target slip angle ω [deg] is calculated as 360*d / (2*π*r).

[0048] (Variation 5) In the first embodiment described above, the torque command value calculated by the torque calculation unit 14 is a certain constant value, and is set to that constant value until a new calculation is performed. For example, in FIG. 7, the torque command value is changed at time t11 and time t13, but remains unchanged at other times. Therefore, the angular velocity changes linearly, and the host vehicle angle θ changes quadratically. However, the torque command value does not have to be a constant value; for example, the torque calculation unit 14 may control the torque so that the amount of change in the host vehicle angle over time is constant, i.e., the angular velocity is constant.

[0049] (Variation 6) The torque calculation unit 14 may set the value of the target left-right driving force difference Td by determining only whether the target slip angle ω is positive, zero, or negative, rather than by determining the actual numerical value of the target slip angle ω. In this case, the value of the target left-right driving force difference Td is, for example, "+D," "0," or "-D." In other words, the torque calculation unit 14 may simply determine the value of the target left-right driving force difference Td so that the current traveling direction approaches the target traveling direction even slightly.

[0050] --Second embodiment-- A second embodiment of a driving force control device will be described with reference to Figure 8. In the following description, the same components as those in the first embodiment are given the same reference numerals, and differences will be mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment mainly in that the vehicle is equipped with multiple driving devices.

[0051] FIG. 8 is a configuration diagram of a vehicle C1 including a driving force control device 10 according to the second embodiment. The vehicle C1 includes a driving unit 27A instead of the driving unit 27 of the first embodiment. The driving unit 27A includes a right wheel inverter device 28A, a right wheel electric motor 29A, a left wheel inverter device 28B, and a left wheel electric motor 29B. The driving unit 27A operates based on a torque command value output by the driving force control device 10. The right wheel electric motor 29A and the left wheel electric motor 29B are, for example, in-wheel motors. The right wheel inverter device 28A supplies electric power to the right wheel electric motor 29A based on a torque command value for the right wheel included in the torque command value. The left wheel inverter device 28B supplies electric power to the left wheel electric motor 29B based on a torque command value for the left wheel included in the torque command value.

[0052] The configuration of the driving force control device 10 is the same as that of the first embodiment, and therefore a description thereof will be omitted. That is, the present embodiment differs from the first embodiment in the configuration for driving the vehicle C1.

[0053] According to the second embodiment described above, the following advantageous effects can be obtained. (7) The drive unit 27A includes a left wheel electric motor 29B that drives the left wheels and a right wheel electric motor 29A that drives the right wheels and is different from the left wheel electric motor 29B. Therefore, the present invention can be implemented in a vehicle C1 that includes electric motors that drive the left and right wheels, respectively.

[0054] In each of the above-described embodiments and modifications, the functional block configurations are merely examples. Some functional configurations shown as separate functional blocks may be configured as an integrated unit, or a configuration shown in a single functional block diagram may be divided into two or more functions. Furthermore, some of the functions of each functional block may be provided by other functional blocks.

[0055] In the above-described embodiments and modifications, the program is stored in ROM 802. However, the program may be stored in a non-volatile memory (not shown). Furthermore, the driving force control device 10 may be provided with an input / output interface (not shown), and the program may be loaded from another device as needed via the input / output interface and a medium available to the driving force control device 10. Here, the medium refers to, for example, a storage medium detachable from the input / output interface, or a communication medium, i.e., a wired, wireless, or optical network, or a carrier wave or digital signal propagating through the network. Furthermore, some or all of the functions realized by the program may be realized by a hardware circuit or FPGA.

[0056] The above-described embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention. [Explanation of symbols]

[0057] 10... Driving force control device 11…Current direction calculation unit 12…Target traveling direction calculation unit 14...Torque calculation section 15...Operation acquisition section 27, 27A...Drive unit 28...Drive unit 28A...Right wheel inverter device 28B...Left wheel inverter device 29...Drive force distribution device 29A…Right wheel electric motor 29B…Left wheel electric motor

Claims

1. A driving force control device for a vehicle having a drive unit capable of driving left and right wheels individually, a torque calculation unit that calculates torque command values ​​that are torques to be generated on the left wheel and the right wheel; a traveling direction calculation unit that calculates a current traveling direction of the vehicle; a target traveling direction calculation unit that calculates a future target traveling direction of the vehicle using at least one of information on a road surface on which the vehicle is traveling and information on an external environment of the vehicle, the torque calculation unit calculates a calculation command value so as to bring the current traveling direction closer to the target traveling direction, and outputs the calculation command value to the drive unit as the torque command value; an operation acquisition unit that acquires operation information relating to an operation input for a user to drive the vehicle, the operation information including at least information relating to a steering angle; the torque calculation unit determines, based on a deviation between a user command value, which is the torque command value based on the operation information, and the calculated command value, which is the torque command value based on the target traveling direction, whether or not to override the calculated command value with the user command value; The torque calculation unit evaluates a deviation between the ratio of right wheel torque to left wheel torque in the user command value and the ratio of right wheel torque to left wheel torque in the calculated command value.

2. 2. The driving force control device according to claim 1, The drive unit includes at least one drive device and a differential device that can distribute the output of the drive device to the left wheel and the right wheel.

3. 2. The driving force control device according to claim 1, A driving force control device, wherein the drive unit includes a left wheel electric motor that drives the left wheel, and a right wheel electric motor that drives the right wheel and is different from the left wheel electric motor.

4. 2. The driving force control device according to claim 1, The torque calculation unit calculates the calculation command value so that the current traveling direction becomes the target traveling direction.

5. a drive unit capable of driving the left and right wheels individually; a driving force control device that outputs a torque command value instructing the drive unit to generate torque at each of the left wheel and the right wheel, The driving force control device includes: a torque calculation unit that calculates the torque command value; a traveling direction calculation unit that calculates a current traveling direction of the vehicle; a target traveling direction calculation unit that calculates a future target traveling direction of the vehicle using at least one of information on a road surface on which the vehicle is traveling and information on an external environment of the vehicle, the torque calculation unit calculates a calculation command value so as to bring the current traveling direction closer to the target traveling direction, and outputs the calculation command value to the drive unit as the torque command value; the driving force control device further includes an operation acquisition unit that acquires operation information relating to an operation input for a user to drive the vehicle, the operation information including at least information relating to a steering angle; the torque calculation unit determines, based on a deviation between a user command value, which is the torque command value based on the operation information, and the calculated command value, which is the torque command value based on the target traveling direction, whether or not to override the calculated command value with the user command value; The torque calculation unit evaluates a deviation between a ratio of right wheel torque to left wheel torque in the user command value and a ratio of right wheel torque to left wheel torque in the calculated command value.

6. 6. The vehicle according to claim 5, The vehicle, wherein the drive section includes at least one drive device and a differential device capable of distributing the output of the drive device to the left wheel and the right wheel.

7. 6. The vehicle according to claim 5, The drive unit includes a left wheel electric motor that drives the left wheels, and a right wheel electric motor that drives the right wheels and is different from the left wheel electric motor.

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