Vehicle control device and vehicle control method

Abstract

This vehicle control device (10) controls the drive force of each of a front drive system and a rear drive system of a vehicle (1) that comprises a front drive system that includes a front wheel (5F) to which motive force from a front drive source (2F) is transmitted and a rear drive system that includes a rear wheel (5R) to which motive force from a rear drive source (2R) is transmitted. The vehicle control device (10) comprises a calculation unit (11) and a control unit (13). The calculation unit (11) calculates a sum mode target slip ratio (yS) that corresponds to the sum of target values for respective slip ratios for the front wheel (5F) and the rear wheel (5R) and a difference mode target slip ratio (yD) that corresponds to the difference between the target values for the respective slip ratios. The control unit (13) controls the drive force using a sum mode command torque that is calculated on the basis of the sum mode target slip ratio (yS) and a difference mode command torque that is calculated on the basis of the difference mode target slip ratio (yD).

Description

Vehicle control device and vehicle control method

[0001] This matter relates to a vehicle control device and a vehicle control method related to vehicle driving force control.

[0002] Conventionally, in vehicles equipped with a mechanism that allows adjustment of the driving force of each wheel, there are known systems that control the driving force of each wheel so as torsional vibration of the wheels is suppressed (see Patent Document 1). There are also known systems that set a target slip ratio for the wheels and control the driving force of each wheel so that the actual slip ratio becomes the target slip ratio (see Patent Document 2).

[0003] Japanese Patent Publication No. 2019-103249, International Publication No. 2023 / 013565

[0004] The behavior of the drivetrain differs between when the vehicle is moving straight and when it is turning. Therefore, in controlling the drivetrain force of the front and rear wheels of a vehicle, it is necessary to construct separate control systems for straight-line driving and for turning. For example, if the target slip ratios for the front and rear wheels are different, it becomes difficult to control the vehicle to determine the difference in wheel speed between the front and rear wheels (to keep the difference in wheel speed between the front and rear wheels within a predetermined target range).

[0005] Furthermore, the turning radius of the front wheels relative to the turning center (the distance from the turning center to the center positions of the left and right front wheels) does not necessarily coincide with the turning radius of the rear wheels relative to the turning center (the distance from the turning center to the center positions of the left and right rear wheels). Therefore, it is difficult to optimize the difference in wheel speed and slip ratio between the front and rear wheels with existing control systems.

[0006] One of the objectives of this invention is to provide a vehicle control device and a vehicle control method that were devised in light of the above-mentioned problems and that can improve the controllability of the difference in wheel speed between the front and rear wheels. In addition to this objective, another objective of this invention is to achieve effects that cannot be obtained with conventional technology, which are derived from the various configurations shown in the "Modes for Carrying Out the Invention" described later.

[0007] The disclosed vehicle control device and vehicle control method can be implemented in the embodiments (application examples) disclosed below, and solve at least some of the above-mentioned problems. Embodiments 1 to 11 relate to vehicle control devices. Embodiment 12 relates to vehicle control methods. Embodiments 2 to 11 are all additional embodiments that can be appropriately selected and all are omittable embodiments. Embodiments 2 to 11 do not disclose any embodiments or configurations that are indispensable to this case. The contents of Embodiments 2 to 11 may also apply to Embodiment 12.

[0008] Embodiment 1. The disclosed vehicle control device controls the driving forces of the front drive system and the rear drive system in a vehicle equipped with a front drive system including front wheels to which power is transmitted from a front drive source and a rear drive system including rear wheels to which power is transmitted from a rear drive source. The vehicle control device includes a calculation unit that calculates a sum mode target slip ratio corresponding to the sum of the target values ​​of the slip ratios of the front wheels and the rear wheels and a difference mode target slip ratio corresponding to the difference between the target values ​​of the slip ratios, and a control unit that controls the driving forces using a sum mode instruction torque calculated based on the sum mode target slip ratio and a difference mode instruction torque calculated based on the difference mode target slip ratio.

[0009] Embodiment 2. In an embodiment including Embodiment 1 described above, it is preferable that the calculation unit calculates the sum mode target slip ratio and the difference mode target slip ratio based on the required driving force and estimated driving force of the vehicle. Embodiment 3. In an embodiment including Embodiment 1 described above, it is preferable that the vehicle control device sets upper and lower limits for the sum mode target slip ratio and the difference mode target slip ratio, and includes a limiting unit that limits each of the sum mode target slip ratio and the difference mode target slip ratio calculated by the calculation unit to be less than or equal to the upper limit and greater than or equal to the lower limit.

[0010] Embodiment 4. In an embodiment including Embodiment 3 above, it is preferable that both the upper limit and the lower limit of the differential mode target slip ratio are 0. Embodiment 5. In an embodiment including Embodiment 1 above, it is preferable that the vehicle control device includes a second calculation unit that calculates the front wheel target slip ratio and the rear wheel target slip ratio, which are target values ​​for the slip ratios of the front wheel and the rear wheel, and that the control unit can control the respective driving forces to achieve both the front wheel target slip ratio and the rear wheel target slip ratio.

[0011] Embodiment 6. In an embodiment including Embodiment 1 described above, it is preferable that the vehicle control device includes a limiting unit that limits the sum mode target slip ratio and the difference mode target slip ratio by setting upper and lower limits for each of the sum mode target slip ratio and the difference mode target slip ratio. In this case, it is preferable that the control unit controls each of the driving forces based on the sum mode target slip ratio and the difference mode target slip ratio after they have been limited by the limiting unit.

[0012] Embodiment 7. In an embodiment including Embodiment 6 described above, it is preferable that the upper limit and lower limit of the sum mode target slip ratio are set to be variable. Embodiment 8. In an embodiment including Embodiment 6 described above, it is preferable that the limiting unit sets the upper limit and lower limit based on the actual slip ratios of the front wheel and the rear wheel.

[0013] Embodiment 9. In an embodiment including Embodiment 1 described above, it is preferable that the calculation unit and the control unit are built into the main ECU. Embodiment 10. In an embodiment including Embodiment 1 described above, it is preferable that the calculation unit and the control unit are built into the front MCU and the rear MCU, respectively.

[0014] Embodiment 11. In an embodiment including Embodiment 1 described above, assuming that one of the front MCU and the rear MCU is defined as the first MCU and the other as the second MCU, it is preferable that the calculation unit and the control unit are built into the first MCU. It is preferable that the control unit calculates the front wheel control parameters for the front MCU to drive the front drive source and the rear wheel control parameters for the rear MCU to drive the rear drive source. It is preferable that the first MCU controls one of the front drive source and the rear drive source using one of the front wheel control parameters and the rear wheel control parameters, and transmits the other of the front wheel control parameters and the rear wheel control parameters to the second MCU. It is preferable that the second MCU controls the other of the front drive source and the rear drive source using the other of the front wheel control parameters and the rear wheel control parameters.

[0015] Embodiment 12. The disclosed vehicle control method controls the driving forces of the front drive system and the rear drive system in a vehicle equipped with a front drive system including front wheels to which power is transmitted from a front drive source and a rear drive system including rear wheels to which power is transmitted from a rear drive source. This vehicle control method calculates a sum mode target slip ratio corresponding to the sum of the target values ​​of the slip ratios of the front wheels and the rear wheels, and a difference mode target slip ratio corresponding to the difference between the target values ​​of the slip ratios, calculates a sum mode instruction torque based on the sum mode target slip ratio, and calculates a difference mode instruction torque based on the difference mode target slip ratio, and controls the driving forces using the sum mode instruction torque and the difference mode instruction torque.

[0016] According to the disclosed vehicle control device and vehicle control method, the controllability with respect to the difference in wheel speed between the front and rear wheels can be improved by calculating the sum mode target slip ratio and the difference mode target slip ratio, and controlling the driving forces of the front drive system and rear drive system to achieve a balance between them.

[0017] This is a block diagram of a vehicle to which a vehicle control device is applied. This is a block diagram showing the function (control example) of the vehicle control device. This is a block diagram showing the function (control example) of the slip setting unit of the first embodiment. This is a block diagram showing the configuration when the vehicle control device is applied to the vehicle's PHEV-ECU (main ECU). This is a block diagram showing the configuration when the vehicle control device is applied to the front MCU and rear MCU of the vehicle, respectively. This is a block diagram showing the configuration when the vehicle control device is applied only to the rear MCU of the vehicle. This is a block diagram for explaining a modified example of the slip setting unit of Figure 2. This is a block diagram showing the function (control example) of the slip setting unit of the second embodiment. This is a graph according to the second embodiment, where (A) is a graph showing an example of setting the upper and lower limits of the sum mode target slip ratio, and (B) is a graph showing an example of setting the upper and lower limits of the difference mode target slip ratio. (A) is a graph showing the relationship between the actual slip ratio and longitudinal force during turning for a plurality of lateral slip angles, and (B) is a graph showing the relationship between the actual slip ratio and lateral force during turning for a plurality of lateral slip angles. This is a block diagram showing the function (control example) of the slip setting unit of the third embodiment. Graphs according to the third embodiment, where (A) is a graph for explaining a method for setting an upper limit of the differential mode target slip ratio based on the sum mode actual slip ratio, and (B) is a graph for explaining a method for setting an upper limit of the sum mode target slip ratio based on the differential mode actual slip ratio.Graphs according to the third embodiment, where (A) and (B) are graphs for explaining a method for setting an upper limit of the sum mode target slip ratio and an upper limit of the differential mode target slip ratio based on the required driving force of the vehicle.

[0018] The types of vehicles to which the disclosed vehicle control device and vehicle control method are used include, for example, engine vehicles (gasoline vehicles, diesel vehicles), electric vehicles, and hybrid vehicles. The vehicles to which the control in this case applies are automobiles equipped with at least a drive source for the front wheels and a drive source for the rear wheels. The drive source here includes internal combustion engines and electric motors.

[0019] In this specification, the drive source for the front wheels is referred to as the front drive source or front motor, and the drive source for the rear wheels is referred to as the rear drive source or rear motor. The front wheels may be one or two. In the latter case, the front wheels include the front left wheel and the front right wheel. Similarly, the rear wheels may be one or two. In the latter case, the rear wheels include the rear left wheel and the rear right wheel. The disclosed vehicle control device and vehicle control method are applicable to a vehicle having a front drive system that constitutes a power transmission path from the front drive source to the front wheels and a rear drive system that constitutes a power transmission path from the rear drive source to the rear wheels. The disclosed vehicle control device and vehicle control method relate to output control of the front drive source and the rear drive source.

[0020] The layouts of the front and rear drive sources may or may not be set to correspond to the longitudinal direction, which is determined with respect to the direction of travel of the vehicle. Furthermore, the front and rear drive systems may operate independently of each other, or they may be connected to each other via a power distribution mechanism. The disclosed vehicle control device and vehicle control method can be used for the control and design of in-wheel motor vehicles in which each wheel is driven by an individual motor.

[0021] [1. First Embodiment] [1-1. Configuration] Figure 1 illustrates the configuration of a vehicle 1 relating to a vehicle control device and vehicle control method as a first embodiment. In the figure, the letters F and R added to the numerical symbols indicate the location of the element corresponding to the symbol [located at the front or rear of the vehicle 1].

[0022] Vehicle 1 comprises a motor 2 (drive source), a transaxle 3, axle 4, wheels 5, inverter 6, and battery 7. The wheels 5 include front wheels 5F and rear wheels 5R. Motor 2 is an electric motor and generator that combines the function of driving vehicle 1 using the power of battery 7 and the function of charging battery 7 with power generated by regenerative power generation. Motor 2 includes a front motor 2F (front drive source, front motor) that drives the front wheels 5F and a rear motor 2R (rear drive source, rear motor) that drives the rear wheels 5R. The front motor 2F and rear motor 2R operate independently of each other and output different magnitudes of driving force individually.

[0023] Hereinafter, the power transmission path from the front motor 2F to the front wheel 5F will be referred to as the front drive system. Similarly, the power transmission path from the rear motor 2R to the rear wheel 5R will be referred to as the rear drive system. The transaxle 3 includes a front transaxle 3F and a rear transaxle 3R. The front transaxle 3F is provided in the front drive system, and the rear transaxle 3R is provided in the rear drive system. Each transaxle 3 incorporates a differential mechanism (not shown).

[0024] Axle 4 includes a front axle 4F and a rear axle 4R. The front axle 4F connects the front transaxle 3F and the front wheels 5F. The driving force of the front motor 2F is reduced by the front transaxle 3F and then distributed to the left and right front wheels 5F via the front axle 4F. The rear axle 4R connects the rear transaxle 3R and the rear wheels 5R. The driving force of the rear motor 2R is reduced by the rear transaxle 3R and then distributed to the left and right rear wheels 5R via the rear axle 4R.

[0025] The inverter 6 is a device that converts between the power of the DC circuit on the battery 7 side (DC power) and the power of the AC circuit on the motor 2 side (AC power). The inverter 6 includes a front inverter 6F and a rear inverter 6R. The front motor 2F is connected to the battery 7 via the front inverter 6F, and the rear motor 2R is connected to the battery 7 via the rear inverter 6R.

[0026] Battery 7 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. When motor 2 is operating, DC power is converted to AC power by inverter 6 and supplied to motor 2. When motor 2 is generating power, the generated power is converted to DC power by inverter 6 and charged to battery 7. The operating state of motor 2 and inverter 6 is controlled by vehicle control device 10. Vehicle control device 10 is one of the electronic control units (ECU) mounted on vehicle 1. Vehicle control device 10 has the function of controlling the output of both the front motor 2F and the rear motor 2R.

[0027] The vehicle control device 10 incorporates a processor (central processing unit), memory (main memory), storage device, interface device, etc. (not shown), which are connected to each other via an internal bus so that they can communicate with one another. The decisions and control operations performed by the vehicle control device 10 are recorded and stored in memory as firmware or application programs. When a program is executed, the contents of the program are loaded into the memory space and executed by the processor.

[0028] The vehicle control device 10 is connected to an accelerator pedal position sensor 14, a brake sensor 15, a steering angle sensor 16, a resolver 17 (rotation angle sensor), and a wheel speed sensor 18. The accelerator pedal position sensor 14 is a sensor that detects the amount the accelerator pedal is pressed (accelerator position) and the speed at which it is pressed. The brake sensor 15 is a sensor that detects the amount the brake pedal is pressed (brake pedal stroke) and the speed at which it is pressed. The steering angle sensor 16 is a sensor that detects the steering angle of the wheels 5 (actual steering angle or steering angle).

[0029] The resolvers 17 (17F, 17R) are sensors that detect the angular velocity of the motors 2 and are individually installed on each motor 2. The resolvers 17 output information about the rotation angle of the motors 2 as a two-phase AC voltage. The angular velocity of the motors 2 is determined from the change in these AC voltages over time. The wheel speed sensors 18 (18F, 18R) are sensors that detect the angular velocity of the axle 4 or the wheels 5. The vehicle control device 10 controls the output of the motors 2 (2F, 2R) by controlling the operating state of the inverters 6 (6F, 6R) based on the information detected by the various sensors 14 to 18 described above. Note that other sensors with different internal structures and operating principles (such as Hall sensors or encoders) may be used instead of the resolvers 17.

[0030] [1-2. Vehicle Control Device] As shown in Figure 1, the vehicle control device 10 includes a calculation unit 11, a limiting unit 12, and a control unit 13 as elements for controlling the driving force of the front drive system and the rear drive system. These elements are a convenient classification of the functions of the vehicle control device 10. These elements may be described as independent programs to realize the function of each element. Alternatively, multiple elements may be combined and described as a single composite program.

[0031] The calculation unit 11 calculates the sum mode target slip ratio y, which corresponds to the sum of the target slip ratios of the front wheel 5F and the rear wheel 5R. Ｓ The difference mode target slip ratio y corresponds to the difference between the target slip ratios of the front wheel 5F and the rear wheel 5R. Ｄ The calculation unit 11 calculates the sum mode target slip ratio y based on the required driving force and estimated driving force of the vehicle 1. Ｓ and difference mode target slip ratio y Ｄ The following is calculated. The required driving force here includes the required torque, required rotational speed (required angular velocity), and required output (required horsepower, required power) for motor 2 and wheel 5, while the estimated driving force includes the estimated torque, estimated rotational speed (required angular velocity), and estimated output (estimated horsepower, estimated power) for motor 2 and wheel 5.

[0032] In the vehicle control device 10 of the first embodiment, the required torque T for the front axle 4F is specified. ＦＬ The difference between this value and the estimated front axle torque (front axle torque deviation), which is the estimated actual torque of the front axle 4F, is calculated, and the rear axle required torque T required for the rear axle 4R is also calculated. ＲＬ The difference between this value and the estimated rear axle torque, which is the estimated actual torque of the rear axle 4R, is calculated (rear axle torque deviation). In addition, the calculation unit 11 calculates the sum mode torque deviation, which is equivalent to the sum of the front axle torque deviation and the rear axle torque deviation, and also calculates the difference mode torque deviation, which is equivalent to the difference between the front axle torque deviation and the rear axle torque deviation. Subsequently, the sum mode target slip ratio y is calculated based on the sum mode torque deviation. Ｓ The differential mode target slip ratio y is calculated based on the differential mode torque deviation. Ｄ This is calculated.

[0033] The limiting unit 12 sets the upper and lower limit values of the sum mode target slip ratio y Ｓ and the difference mode target slip ratio y Ｄ and limits each of the sum mode target slip ratio y Ｓ and the difference mode target slip ratio y Ｄ calculated by the calculation unit 11 to be not more than the upper limit value and not less than the lower limit value (limiter). The upper and lower limit values of the sum mode target slip ratio y Ｓ are preset fixed values. Specific examples of the upper and lower limit values of the sum mode target slip ratio y Ｓ include, for example, +0.1 and -0.1, +0.2 and -0.2, etc. In the first embodiment, the absolute values of the upper and lower limit values are the same, and only the signs are different values.

[0034] Similarly, the upper and lower limit values of the difference mode target slip ratio y Ｄ are preset fixed values. Specific examples of the upper and lower limit values of the difference mode target slip ratio y Ｄ include, for example, +0.05 and -0.05, 0 (both the upper and lower limit values are 0), etc. In the first embodiment, the absolute values of the upper and lower limit values are the same, and only the signs are different values. Note that the limiting unit 12 can be omitted.

[0035] The control unit 13 controls the driving forces of the front drive system and the rear drive system using the sum mode instruction torque T Ｓ calculated based on the sum mode target slip ratio y Ｓ and the difference mode instruction torque T Ｄ calculated based on the difference mode target slip ratio y Ｄ . For the method of calculating the sum mode instruction torque T Ｓ from the sum mode target slip ratio y Ｓ , a known calculation method can be applied. The same applies to the method of calculating the difference mode instruction torque T Ｄ from the difference mode target slip ratio y Ｄ .

[0036] In the control unit 13, the sum mode instruction torque T Ｓ and the difference mode instruction torque T ＤTo ensure that both are achieved, the front motor instruction torque T ＦＭ And the motor instruction torque T ＲＭ The following is calculated. Then, the calculated pre-motor instruction torque T is calculated. ＦＭ and the motor instruction torque T ＲＭ The inverter 6 is controlled so that the desired state is achieved. This makes it easier to control the motion state of the front drive system and the rear drive system with precision so that they reach the desired state.

[0037] [1-3. Specific Example] Figure 2 is a block diagram showing a specific control example by the vehicle control device 10. The vehicle control device 10 is provided with a slip setting unit 21 including a calculation unit 11 and a limiting unit 12, and the control unit 13 is responsible for calculating the control amount related to the slip control of the vehicle 1. The control unit 13 is provided with a sum mode control unit 22, a difference mode control unit 23, and a front / rear conversion unit 24.

[0038] The vehicle control device 10 is also equipped with a requested driving force setting unit 51, an estimated driving force observer 52, a sum-difference conversion unit 53, a vibration damping control unit 54, and a front-to-rear conversion unit 57. The vibration damping control unit 54 is responsible for calculating the control amount related to vibration damping control (vibration suppression control) of the vehicle 1. In this vehicle control device 10, the final motor command torque T is calculated by adding the control amount of slip control by the control unit 13 and the control amount of vibration damping control by the vibration damping control unit 54. ＦＭ , T ＲＭ This is the result.

[0039] The requested driving force setting unit 51 sets the driving force that the driver requests from the vehicle 1. Here, for example, based on the accelerator opening, brake pedal stroke, steering angle, vehicle speed, etc., the requested front axle torque T is set for the front axle 4F. ＦＬ The rear axle torque T required for the rear axle 4R ＲＬ The required torque T for the front axle is calculated here. ＦＬ and the required torque T for the rear axle ＲＬ This information is transmitted to the sum-difference conversion unit 53.

[0040] The estimated driving force observer 52 calculates an estimated value corresponding to the actual driving force of the vehicle 1. Here, for example, based on the motor command torque related to the control signal output to the inverter 6 in the previous control cycle, the motor angular velocity detected by the resolver 17, the wheel speed detected by the wheel speed sensor 18, etc., the estimated driving torque of the front axle 4F, the front axle estimated torque T, is calculated. ＦＬ ′ and the estimated rear axle torque T, which is the estimated drive torque of the rear axle 4R. ＲＬ The ′ is calculated. The vehicle control device 10 sets the front axle required torque T ＦＬ Estimated torque T from the front axle ＦＬ Front axle torque deviation with ' subtracted, and rear axle required torque T ＲＬ Estimated torque T from the rear axle ＲＬ The axle torque deviation is calculated after subtracting '. The information on the front axle torque deviation and rear axle torque deviation calculated here is transmitted to the calculation unit 11 of the slip setting unit 21.

[0041] The sum-and-difference conversion unit 53 converts the front axle required torque T ＦＬ and the required torque T for the rear axle ＲＬ The sum mode torque and differential mode torque are calculated. The value of the sum mode torque is, for example, the required torque T for the front axle. ＦＬ and the required torque T for the rear axle ＲＬ It is considered to be half of the sum. The sum mode torque information is transmitted to the sum mode control unit 55 of the vibration damping control unit 54. The difference mode torque value is, for example, the front axle required torque T ＦＬ and the required torque T for the rear axle ＲＬ It is said to be half of the difference. The differential mode torque information is transmitted to the differential mode control unit 56 of the vibration damping control unit 54.

[0042] The sum mode control unit 55 is a filter for removing vibration components (for example, sum mode-compatible vibrations of a few Hz to tens of Hz) that may occur when the vehicle 1 is moving straight from the sum mode torque. By passing through the sum mode control unit 55, the sum mode torque becomes one in which vibrations that may occur in the straight-ahead state are suppressed. The difference mode control unit 56 is a filter for removing vibration components (for example, vibrations with a lower frequency than the sum mode-compatible vibrations) that may occur when the vehicle 1 is turning from the difference mode torque. By passing through the difference mode control unit 56, the difference mode torque becomes one in which vibrations that may occur in the turning state are suppressed.

[0043] The front-to-rear conversion unit 57 performs calculations to distribute the sum mode torque obtained by the sum mode control unit 55 and the difference mode torque obtained by the difference mode control unit 56 to the front and rear motors 2. Here, the instruction torque for vibration damping control that should be borne by the front motor 2F and the rear motor 2R is calculated by a calculation equivalent to the inverse calculation of the sum-to-difference conversion unit 53. For example, the sum of the sum mode torque obtained by the sum mode control unit 55 and the difference mode torque obtained by the difference mode control unit 56 is used as the instruction torque for vibration damping control of the front motor. Also, the difference between the sum mode torque obtained by the sum mode control unit 55 and the difference mode torque obtained by the difference mode control unit 56 is used as the instruction torque for vibration damping control of the rear motor.

[0044] The slip setting unit 21 sets parameters related to the target slip ratio of the front wheel 5F and the rear wheel 5R. Figure 3 is a block diagram showing a specific control example by the slip setting unit 21. In addition to the calculation unit 11 and limiting unit 12 mentioned above, the slip setting unit 21 is provided with a sum / difference wheel speed calculation unit 36 ​​and multipliers 37 and 38. The calculation unit 11 is provided with a sum / difference calculation unit 31, a sum mode target slip ratio calculation unit 32, and a difference mode target slip ratio calculation unit 33. The limiting unit 12 is provided with a sum mode target slip ratio limiting unit 34 and a difference mode target slip ratio limiting unit 35.

[0045] The sum-difference calculation unit 31 calculates the sum-mode torque deviation, which corresponds to the sum of the front axle torque deviation and the rear axle torque deviation, and the difference-mode torque deviation, which corresponds to the difference between the front axle torque deviation and the rear axle torque deviation. The value of the sum-mode torque deviation is, for example, half of the sum of the front axle torque deviation and the rear axle torque deviation (sum of the deviations). The sum-mode torque deviation information is transmitted to the sum-mode target slip ratio calculation unit 32. The difference-mode torque deviation value is, for example, half of the difference between the front axle torque deviation and the rear axle torque deviation (amount of difference between the deviations). The difference-mode torque deviation information is transmitted to the difference-mode target slip ratio calculation unit 33.

[0046] The sum mode target slip ratio calculation unit 32 calculates the sum mode target slip ratio y, which corresponds to the sum of the target values ​​of the slip ratios of the front wheels 5F and the rear wheels 5R. Ｓ This calculates the sum mode target slip ratio y based on the required driving force and estimated driving force of vehicle 1. Ｓ The following is calculated: For example, the sum mode target slip ratio y is calculated based on the value obtained by integrating the value obtained by subtracting the estimated driving force from the required driving force (error). Ｓ The following is calculated. In the first embodiment, the sum mode target slip ratio y is calculated based on the value obtained by integrating the sum mode torque deviation. Ｓ The sum mode target slip ratio y calculated here is then used. Ｓ This information is transmitted to the sum mode target slip ratio limiting unit 34.

[0047] The differential mode target slip ratio calculation unit 33 calculates the differential mode target slip ratio y, which corresponds to the difference between the target values ​​of the slip ratios of the front wheels 5F and the rear wheels 5R. Ｄ This calculates the differential mode target slip ratio y based on the required driving force and estimated driving force of vehicle 1. Ｄ The following is calculated: For example, the differential mode target slip ratio y is calculated based on the value obtained by integrating the value obtained by subtracting the estimated driving force from the required driving force (error). Ｄ The following is calculated. In the first embodiment, the differential mode target slip ratio y is calculated based on the value obtained by integrating the differential mode torque deviation. Ｄ The following is calculated: The difference mode target slip ratio y calculated here Ｄ This information is transmitted to the differential mode target slip ratio limiting unit 35.

[0048] The sum mode target slip ratio limiting unit 34 controls the sum mode target slip ratio y. Ｓ This limits the value so that it falls within a predetermined range. Here, the sum mode target slip ratio y Ｓ Upper and lower limits are set, and the target slip rate y of the sum mode is set. Ｓ The value is restricted to be less than or equal to the upper limit and greater than or equal to the lower limit. The upper and lower limits set here are fixed values ​​that have been set in advance.

[0049] The sum mode target slip ratio y calculated by the calculation unit 11 (sum mode target slip ratio calculation unit 32) Ｓ If the value exceeds the upper limit, that value is replaced with the upper limit and output from the sum mode target slip ratio limiting unit 34. Conversely, the sum mode target slip ratio y Ｓ If the value is less than the lower limit, that value is replaced with the lower limit and output from the sum mode target slip ratio limiting unit 34. Sum mode target slip ratio y Ｓ If the value is greater than or equal to the lower limit and less than or equal to the upper limit, the value is output as is from the sum mode target slip ratio limiting unit 34.

[0050] Similarly, the differential mode target slip ratio limiting unit 35 sets the differential mode target slip ratio y Ｄ This limits the value so that it falls within a predetermined range. Here, the differential mode target slip ratio y Ｄ Upper and lower limits are set for the range that can be taken, and the differential mode target slip rate y Ｄ It is restricted to be below the upper limit and above the lower limit. The upper and lower limits set here are fixed values ​​that have been set in advance.

[0051] The differential mode target slip ratio y calculated by the calculation unit 11 (differential mode target slip ratio calculation unit 33) Ｄ If the value exceeds the upper limit or falls below the lower limit, the calculated value is replaced with the upper or lower limit and output from the differential mode target slip ratio limiting unit 35. ＤIf the value is greater than or equal to the lower limit and less than or equal to the upper limit, the value is output as is from the differential mode target slip ratio limiting unit 35.

[0052] The sum-and-difference wheel speed calculation unit 36 ​​calculates the sum-mode reference wheel speed, which corresponds to the sum of the front axle reference wheel speed and the rear axle reference wheel speed, and the difference-mode reference wheel speed, which corresponds to the difference between the front axle reference wheel speed and the rear axle reference wheel speed. The value of the sum-mode reference wheel speed is, for example, half of the sum of the front axle reference wheel speed and the rear axle reference wheel speed, and the value of the difference-mode reference wheel speed is, for example, half of the difference between the front axle reference wheel speed and the rear axle reference wheel speed. The values ​​of the front axle reference wheel speed and the rear axle reference wheel speed are calculated based on, for example, the detected value of the wheel speed sensor 18 and the steering angle.

[0053] The multiplier 37 receives the sum mode target slip ratio y output from the sum mode target slip ratio limiting unit 34. Ｓ The sum mode target wheel speed is output by multiplying it by the sum mode reference wheel speed. The information of the sum mode target wheel speed output here is transmitted to the sum mode control unit 22 of the control unit 13. The multiplier 38 also receives the differential mode target slip ratio y output from the differential mode target slip ratio limiting unit 35. Ｄ The differential mode target wheel speed is output by multiplying this value by the differential mode reference wheel speed. The information of the differential mode target wheel speed output here is transmitted to the differential mode control unit 23 of the control unit 13.

[0054] As shown in Figure 2, the sum mode control unit 22 sets the sum mode target slip ratio y Ｓ Based on this, the sum mode torque is calculated to optimize the slip ratio of vehicle 1 when it is moving straight. The differential mode control unit 23 also calculates the differential mode target slip ratio y Ｄ Based on this, the differential mode torque is calculated to optimize the slip ratio during vehicle 1's turning. The sum mode torque and differential mode torque information is transmitted to the front / rear conversion unit 24.

[0055] The front-to-rear conversion unit 24, like the front-to-rear conversion unit 57, performs calculations to distribute the sum mode torque obtained by the sum mode control unit 22 and the difference mode torque obtained by the difference mode control unit 23 to the front and rear motors 2. For example, the sum of the sum mode torque and the difference mode torque is used as the front motor instruction torque for slip control, and the difference between the sum mode torque and the difference mode torque is used as the rear motor instruction torque for slip control.

[0056] The final front motor instruction torque T is obtained by adding the front motor instruction torque for vibration damping control obtained in the front / rear conversion unit 57 and the front motor instruction torque for slip control obtained in the front / rear conversion unit 24. ＦＭ Similarly, the rear motor instruction torque for vibration damping control obtained in the front-to-rear conversion unit 57 and the rear motor instruction torque for slip control obtained in the front-to-rear conversion unit 24 are added together to obtain the final rear motor instruction torque T. ＲＭ This is the result.

[0057] [1-4. Application to On-board ECUs] The vehicle control device 10 may be mounted on the vehicle 1 separately from the existing on-board ECU. Alternatively, the functions of the vehicle control device 10 may be built into the existing on-board ECU. In other words, the vehicle control device 10 may be applied to an existing on-board ECU. Figures 4 to 6 are diagrams illustrating a specific method for applying the vehicle control device 10 to a vehicle 1 equipped with a PHEV-ECU 10A (main ECU), a front MCU 10B, and a rear MCU 10C. The front MCU 10B shown in Figures 4 to 6 is an ECU that controls the operating state of the front motor 2F and the front inverter 6F. The rear MCU 10C is an ECU that controls the operating state of the rear motor 2R and the rear inverter 6R. The PHEV-ECU 10A is a higher-level ECU that comprehensively manages various ECUs mounted on the vehicle 1, including the front MCU 10B and the rear MCU 10C.

[0058] The vehicle control device 10 may be applied to any one of the PHEV-ECU 10A, front MCU 10B, or rear MCU 10C, or it may be applied in a distributed manner to multiple ECUs. Figure 4 is a block diagram showing the case when the vehicle control device 10 is applied to the PHEV-ECU 10A. Based on driving operation information and driving condition information, the PHEV-ECU 10A calculates, for example, the required front wheel driving force (e.g., required front wheel torque and required front wheel angular velocity) and the required rear wheel driving force (e.g., required rear wheel torque and required rear wheel angular velocity) required to the rear wheel 5R.

[0059] Information regarding the required driving force for the front wheels is transmitted to the front MCU 10B. The front MCU 10B controls the operating state of the front motor 2F and front inverter 6F based on the information regarding the required driving force for the front wheels. Information regarding the required driving force for the rear wheels is transmitted to the rear MCU 10C. The rear MCU 10C controls the operating state of the rear motor 2R and rear inverter 6R based on the information regarding the required driving force for the rear wheels.

[0060] The configuration shown in Figure 4 has the advantage of consolidating the drive force calculation in the high-performance PHEV-ECU 10A, eliminating the need for drive force calculations in the front MCU 10B and rear MCU 10C. On the other hand, depending on the communication speed between the PHEV-ECU 10A, the front MCU 10B, and the rear MCU 10C (the communication speed of the in-vehicle network), it may take time for the drive force calculation in the PHEV-ECU 10A to be reflected in the actual state of the motor 2, which may make it difficult to improve controllability. Therefore, the configuration shown in Figure 4 is suitable when the communication speed of the in-vehicle network is sufficiently fast.

[0061] Figure 5 is a block diagram showing the case where the vehicle control device 10 is applied to the front MCU 10B and the rear MCU 10C, respectively. Driving operation information and driving condition information are transmitted to the PHEV-ECU 10A, the front MCU 10B, and the rear MCU 10C, respectively. Based on the driving operation information and driving condition information, the PHEV-ECU 10A calculates, for example, the total required driving force required for the entire vehicle 1. The information on the total required driving force is transmitted to the front MCU 10B and the rear MCU 10C, respectively.

[0062] The front MCU 10B calculates the required driving force for the front wheels based on information about the total required driving force, driving operation information, and driving conditions, and controls the operating state of the front motor 2F and front inverter 6F based on this. In parallel with this, the rear MCU 10C calculates the required driving force for the rear wheels based on information about the total required driving force, driving operation information, and driving conditions, and controls the operating state of the rear motor 2R and rear inverter 6R based on this.

[0063] The configuration shown in Figure 5 has the advantage of being able to quickly control the requested driving force of the front wheels and the requested driving force of the rear wheels in a synchronized manner, regardless of the communication speed of the in-vehicle network. On the other hand, the computational load on both the front MCU 10B and the rear MCU 10C becomes large. Therefore, the configuration shown in Figure 5 is suitable only when the front MCU 10B and the rear MCU 10C are sufficiently high-performance.

[0064] Figure 6 is a block diagram showing the case where the vehicle control device 10 is applied to only one of the front MCU 10B and rear MCU 10C (rear MCU 10C in Figure 10). Driving operation information and driving condition information are transmitted to the PHEV-ECU 10A and rear MCU 10C. Based on the driving operation information and driving condition information, the PHEV-ECU 10A calculates, for example, the total required driving force required for the entire vehicle 1. The information on the total required driving force is transmitted to the rear MCU 10C.

[0065] The rear MCU 10C calculates rear wheel control parameters (e.g., rear wheel required driving force, rear wheel required torque, rear wheel required angular velocity, rear wheel target driving force, rear wheel target torque, rear wheel target angular velocity, etc.) based on information on total required driving force, driving operation information, and driving condition information, and controls the operating state of the rear motor 2R and rear inverter 6R based on these parameters. The rear MCU 10C also calculates front wheel control parameters (e.g., front wheel required driving force, front wheel required torque, front wheel required angular velocity, front wheel target driving force, front wheel target torque, front wheel target angular velocity, etc.) based on the total required driving force and rear wheel control parameters, and transmits these to the front MCU 10B.

[0066] If the rear wheel control parameter is the rear wheel required driving force, the front wheel required driving force can be easily calculated as a front wheel control parameter by subtracting the rear wheel required driving force from the total required driving force. If the rear wheel control parameter is something other than the rear wheel required driving force, the rear wheel control parameter should be converted to the rear wheel required driving force, then subtracted from the total required driving force, and that value should then be converted to a front wheel control parameter other than the front wheel required driving force. The front MCU 10B and the rear MCU 10C are connected by a dedicated line, enabling high-speed information exchange. The front MCU 10B controls the operating state of the front motor 2F and the front inverter 6F based on the front wheel control parameter calculated by the rear MCU 10C.

[0067] The configuration shown in Figure 6 has the advantage of enabling rapid control of the front wheel control parameters and rear wheel control parameters while synchronizing them, regardless of the communication speed of the in-vehicle network. Furthermore, it reduces the computational load on the front MCU 10B, thereby lowering the performance requirements for the front MCU 10B. The configuration shown in Figure 6 is particularly suitable, for example, in a vehicle 1 equipped with a standard in-vehicle network, where either the front MCU 10B or the rear MCU 10C can be replaced with a high-performance ECU.

[0068] [1-5. Effects] (1) The vehicle control device 10 of the first embodiment controls the driving force of the front drive system and the rear drive system in a vehicle 1 which has a front drive system including a front wheel 5F to which power is transmitted from a front motor 2F (front drive source) and a rear drive system including a rear wheel 5R to which power is transmitted from a rear motor 2R (rear drive source). The vehicle control device 10 comprises a calculation unit 11 and a control unit 13.

[0069] The calculation unit 11 calculates the sum mode target slip ratio y, which corresponds to the sum of the target slip ratios of the front wheel 5F and the rear wheel 5R. Ｓ The difference mode target slip ratio y corresponds to the difference between the target values ​​of each slip ratio and the target slip ratio. Ｄ The control unit 13 calculates the sum mode target slip ratio y. Ｓ The sum mode indicated torque T is calculated based on the above. Ｓ and difference mode target slip ratio y Ｄ The differential mode indicated torque T is calculated based on the above. ＤControl the driving forces of the front drive system and the rear drive system using these.

[0070] Thus, the sum mode target slip ratio y Ｓ and the difference mode target slip ratio y Ｄ are calculated, and by controlling the driving forces of the front drive system and the rear drive system so as to make these compatible, the controllability regarding the wheel speed difference between the front wheels 5F and the rear wheels 5R can be improved. For example, when individual target slip ratios are set for each of the front wheels 5F and the rear wheels 5R, the actual wheel speeds of each will be controlled according to the individual target slip ratios, and it is difficult to control the wheel speed difference between the front wheels 5F and the rear wheels 5R to a specific target value. In contrast, according to the vehicle control device 10 of the first embodiment, the distribution of the driving force that makes the sum mode target slip ratio y Ｓ and the difference mode target slip ratio y Ｄ compatible becomes easy, and it becomes possible to control the wheel speed difference between the front wheels 5F and the rear wheels 5R within a specific target range.

[0071] Also, even when the turning radius of the front wheels 5F with respect to the turning center is different from the turning radius of the rear wheels 5R with respect to the turning center, or when these change, the state quantities of each of the front wheels 5F and the rear wheels 5R can be accurately controlled. Therefore, the controllability (for example, control accuracy and control response speed) can be improved with a simple configuration.

[0072] (2) The calculation unit 11 of the first embodiment calculates the sum mode target slip ratio y Ｓ and the difference mode target slip ratio y Ｄ based on the required driving force and the estimated driving force of the vehicle 1. With such a configuration, the control responsiveness regarding the slip ratio can be improved, and the actual slip ratios of the front wheels 5F and the rear wheels 5R can be accurately controlled. Therefore, the controllability regarding the wheel speed difference between the front wheels 5F and the rear wheels 5R can be further improved, and the running performance and stability of the vehicle 1 can be improved.

[0073] (3) The vehicle control device 10 of the first embodiment sets the upper limit value and the lower limit value of the sum mode target slip ratio y Ｓ and the difference mode target slip ratio y Ｄ , and the sum mode target slip ratio y Ｓand differential mode target slip ratio y Ｄ The system includes a limiting unit 12 that restricts each of the following to be below an upper limit and above a lower limit. With this configuration, the sum mode target slip ratio y Ｓ and differential mode target slip ratio y Ｄ This ensures that the value remains within an appropriate range (from the lower limit to the upper limit). Therefore, the controllability regarding the wheel speed difference between the front wheel 5F and the rear wheel 5R can be further improved.

[0074] (4) The target slip ratio y of the differential mode Ｄ By setting both the upper and lower limits to 0, the differential mode target wheel speed calculated by the multiplier 38 can be set to 0. This makes it easy to implement torque distribution in the control unit 13 so that the wheel speed difference between the front axle reference wheel speed and the rear axle reference wheel speed is maintained. Therefore, the controllability regarding the wheel speed difference between the front wheel 5F and the rear wheel 5R can be further improved.

[0075] (5) The above-described vehicle control device 10 can be applied to the PHEV-ECU 10A (main ECU) as shown in Figure 4. In this case, the calculation unit 11 and the control unit 13 are built into the PHEV-ECU 10A. With this configuration, the driving force calculation can be consolidated into the high-performance PHEV-ECU 10A, and the driving force calculation in the front MCU 10B and rear MCU 10C can be omitted.

[0076] (6) The above-described vehicle control device 10 can be applied to the front MCU 10B and the rear MCU 10C, respectively, as shown in Figure 5. In this case, the calculation unit 11 and the control unit 13 are built into the front MCU 10B and the rear MCU 10C, respectively. With this configuration, the requested driving force for the front wheels and the requested driving force for the rear wheels can be quickly controlled in synchronization, without depending on the communication speed of the in-vehicle network.

[0077] (7) The above-described vehicle control device 10 may be applied to either the front MCU 10B or the rear MCU 10C. The calculation unit 11 and control unit 13 shown in Figure 6 are built into the rear MCU 10C. The control unit 13 calculates the front wheel control parameters and the rear wheel control parameters. The front wheel control parameters are used by the front MCU 10B to drive the front motor 2F. The rear wheel control parameters are used by the rear MCU 10C to drive the rear motor 2R. The control unit 13 of the rear MCU 10C calculates both of these parameters.

[0078] The rear MCU 10C controls the rear motor 2R using rear wheel control parameters and transmits front wheel control parameters to the front MCU 10B. The front MCU 10B controls the front motor 2F using these front wheel control parameters. Even with this configuration, the requested driving force for the front wheels and the requested driving force for the rear wheels can be controlled quickly and synchronously, without depending on the communication speed of the in-vehicle network. In addition, the computational load on the front MCU 10B can be reduced, and the performance required of the front MCU 10B can be lowered.

[0079] [1-6. Others] The above-described first embodiment is merely illustrative, and there is no intention to exclude various modifications or applications of techniques not explicitly shown in the first embodiment. Each component of the first embodiment can be modified in various ways without departing from its intended purpose. Furthermore, each component of the first embodiment can be selected or combined as needed.

[0080] For example, in the example shown in Figure 6, the calculation unit 11 and the control unit 13 are built into the rear MCU 10C, but the calculation unit 11 and the control unit 13 may also be built into the front MCU 10B. In this case, in the control described above using Figure 6, the front MCU 10B and the rear MCU 10C are swapped, with the front MCU 10B becoming the "first MCU" as described in the claim, and the rear MCU 10C becoming the "second MCU". Furthermore, in the first embodiment described above, a vehicle 1 equipped with a front motor 2F and a rear motor 2R as drive sources was exemplified, but an internal combustion engine may be used instead of the motors 2, and the specific type of drive source is not limited.

[0081] In the above first embodiment, the vehicle control device 10 including the calculation unit 11 that calculates the sum mode target slip ratio y of the front wheels 5F and the rear wheels 5R has been exemplified. However, separately from this calculation unit 11, a second calculation unit 41 that calculates the target slip ratio y of each of the front wheels 5F and the rear wheels 5R may be provided. That is, the slip control based on the individual target slip ratios y and the slip control based on the sum mode target slip ratio y and the difference mode target slip ratio y may be selectively used. Ｓ and the difference mode target slip ratio y Ｄ has been exemplified. However, separately from this calculation unit 11, a second calculation unit 41 that calculates the target slip ratio y of each of the front wheels 5F and the rear wheels 5R may be provided. That is, the slip control based on the individual target slip ratios y Ｆ , y Ｒ may be selectively used. Ｆ , y Ｒ and the slip control based on the sum mode target slip ratio y Ｓ and the difference mode target slip ratio y Ｄ may be selectively used.

[0082] FIG. 7 is a block diagram for explaining a modification example of the slip setting unit 21 in FIG. 2. The slip setting unit 21 is provided with a second calculation unit 41, a second limiting unit 44, multipliers 47, 48, and a sum-difference conversion unit 49. The second calculation unit 41 is provided with a front wheel target slip ratio calculation unit 42 and a rear wheel target slip ratio calculation unit 43. The front wheel target slip ratio calculation unit 42 calculates the front wheel target slip ratio y which is the target value of the slip ratio of the front wheels 5F. The rear wheel target slip ratio calculation unit 43 calculates the rear wheel target slip ratio y which is the target value of the slip ratio of the rear wheels 5R. Ｆ which is the target value of the slip ratio of the front wheels 5F. The rear wheel target slip ratio calculation unit 43 calculates the rear wheel target slip ratio y Ｒ which is the target value of the slip ratio of the rear wheels 5R.

[0083] The second limiting unit 44 is provided with a front wheel target slip ratio limiting unit 45 and a rear wheel target slip ratio limiting unit 46. The front wheel target slip ratio limiting unit 45 sets the upper limit value and the lower limit value of the front wheel target slip ratio y, and limits the front wheel target slip ratio y calculated by the front wheel target slip ratio calculation unit 42 to be not more than the upper limit value and not less than the lower limit value. Similarly, the rear wheel target slip ratio limiting unit 46 sets the upper limit value and the lower limit value of the rear wheel target slip ratio y, and limits the rear wheel target slip ratio y calculated by the rear wheel target slip ratio calculation unit 43 to be not more than the upper limit value and not less than the lower limit value. Ｆ and limits the front wheel target slip ratio y calculated by the front wheel target slip ratio calculation unit 42 to be not more than the upper limit value and not less than the lower limit value. Similarly, the rear wheel target slip ratio limiting unit 46 sets the upper limit value and the lower limit value of the rear wheel target slip ratio y Ｆ and limits the rear wheel target slip ratio y calculated by the rear wheel target slip ratio calculation unit 43 to be not more than the upper limit value and not less than the lower limit value. Ｒ and limits the rear wheel target slip ratio y calculated by the rear wheel target slip ratio calculation unit 43 to be not more than the upper limit value and not less than the lower limit value. Ｒ to be not more than the upper limit value and not less than the lower limit value.

[0084] The multiplier 47 multiplies the front wheel target slip ratio y output from the front wheel target slip ratio limiting unit 45 ＦThe front axle target wheel speed is output by multiplying this by the front axle reference wheel speed. The multiplier 48 outputs the rear wheel target slip ratio y output from the rear wheel target slip ratio limiting unit 46. Ｒ The rear axle target wheel speed is output by multiplying the front axle target wheel speed by the rear axle reference wheel speed. The sum-difference conversion unit 49 calculates the sum mode target wheel speed and the difference mode target wheel speed based on the front axle target wheel speed and the rear axle target wheel speed. The sum mode target wheel speed is, for example, half of the sum of the front axle target wheel speed and the rear axle target wheel speed, and the difference mode target wheel speed is, for example, half of the difference between the front axle target wheel speed and the rear axle target wheel speed. The information on the sum mode target wheel speed and the difference mode target wheel speed is transmitted to the control unit 13.

[0085] Thus, the slip setting unit 21 shown in Figure 7 sets the sum mode target slip ratio y Ｓ and differential mode target slip ratio y Ｄ The target wheel speed derived from and the front wheel target slip ratio y Ｆ and target slip ratio y of the rear wheel Ｒ The control unit 13 outputs the target wheel speed derived from the above to the control unit 13. Upon receiving this, the control unit 13 may perform control based on the former target wheel speed, or it may perform control based on the latter target wheel speed. In the latter case, the control unit 13 sets the front wheel target slip ratio y Ｆ and target slip ratio y of the rear wheel Ｒ The driving forces of the front and rear drive systems are controlled to achieve both objectives simultaneously. This allows the latter control to be implemented under conditions unsuitable for the former control (for example, partially frozen road surfaces where the road surface friction coefficient μ in the direction of travel fluctuates, bridge entrances and exits, tunnel entrances and exits, etc.), thereby improving the controllability regarding the wheel speed difference between the front wheels 5F and the rear wheels 5R.

[0086] [2. Second Embodiment] The vehicle 1 relating to the vehicle control device 10 and vehicle control method as a second embodiment has the same configuration as illustrated in Figures 1 and 2 as in the first embodiment. Hereinafter, elements that are the same as (or corresponding to) those in the first embodiment will be denoted by the same reference numerals and described accordingly, and redundant content will be omitted as appropriate. In the vehicle control device 10 of the second embodiment as well, the limiting unit 12 is the sum mode target slip ratio y Ｓ and differential mode target slip ratio y ＤSet the upper and lower limits. These upper and lower limits are variable.

[0087] [2-1. Specific Example] Figure 8 is a block diagram showing a specific control example by the slip setting unit 21. In addition to the calculation unit 11 and limiting unit 12 mentioned above, the slip setting unit 21 is provided with a sum / difference wheel speed calculation unit 36 ​​and multipliers 37 and 38. The calculation unit 11 is provided with a sum / difference calculation unit 31, a sum mode target slip ratio calculation unit 32, and a difference mode target slip ratio calculation unit 33. The limiting unit 12 is provided with an upper and lower limit setting unit 39, a sum mode target slip ratio limiting unit 34, and a difference mode target slip ratio limiting unit 35.

[0088] The sum-difference calculation unit 31 calculates the sum-mode torque deviation, which corresponds to the sum of the front axle torque deviation and the rear axle torque deviation, and the difference-mode torque deviation, which corresponds to the difference between the front axle torque deviation and the rear axle torque deviation. The value of the sum-mode torque deviation is, for example, half of the sum of the front axle torque deviation and the rear axle torque deviation (sum of the deviations). The sum-mode torque deviation information is transmitted to the sum-mode target slip ratio calculation unit 32. The difference-mode torque deviation value is, for example, half of the difference between the front axle torque deviation and the rear axle torque deviation (amount of difference between the deviations). The difference-mode torque deviation information is transmitted to the difference-mode target slip ratio calculation unit 33.

[0089] The sum mode target slip ratio calculation unit 32 calculates the sum mode target slip ratio y, which corresponds to the sum of the target values ​​of the slip ratios of the front wheels 5F and the rear wheels 5R. Ｓ This calculates the sum mode target slip ratio y based on the required driving force and estimated driving force of vehicle 1. Ｓ The following is calculated: For example, the sum mode target slip ratio y is calculated based on the value obtained by integrating the value obtained by subtracting the estimated driving force from the required driving force (error). Ｓ The following is calculated. In this embodiment, the sum mode target slip ratio y is calculated based on the value obtained by integrating the sum mode torque deviation. Ｓ The sum mode target slip ratio y calculated here is then used. Ｓ This information is transmitted to the sum mode target slip ratio limiting unit 34.

[0090] The differential mode target slip ratio calculation unit 33 calculates the differential mode target slip ratio y, which corresponds to the difference between the target values ​​of the slip ratios of the front wheels 5F and the rear wheels 5R. Ｄ This calculates the differential mode target slip ratio y based on the required driving force and estimated driving force of vehicle 1. Ｄ The following is calculated: For example, the differential mode target slip ratio y is calculated based on the value obtained by integrating the value obtained by subtracting the estimated driving force from the required driving force (error). Ｄ The following is calculated. In this embodiment, the differential mode target slip ratio y is calculated based on the value obtained by integrating the differential mode torque deviation. Ｄ The following is calculated: The difference mode target slip ratio y calculated here Ｄ This information is transmitted to the differential mode target slip ratio limiting unit 35.

[0091] The upper and lower limit setting unit 39 sets the target slip ratio y for the sum mode. Ｓ and differential mode target slip ratio y Ｄ This sets upper and lower limits for each of the following. Here, at least the sum mode target slip ratio y Ｓ The upper and lower limits are set variably. Sum mode target slip ratio y Ｓ The upper limit is set as a variable value that fluctuates within a range of, for example, 0.1 to 0.7. (Sum mode target slip ratio y) Ｓ The lower limit is set as a variable value that fluctuates within a range of approximately -0.7 to -0.1, corresponding to the upper limit.

[0092] Differential mode target slip ratio y Ｄ The upper and lower limits may be fixed values ​​set in advance, or they may be set as variable values ​​that can change depending on the situation. If they are fixed values, both the upper and lower limits may be set to 0. Alternatively, the upper limit may be a fixed value within a range of, for example, 0 to 0.1. Differential mode target slip ratio y Ｄ The lower limit may be a fixed value within a range of approximately -0.1 to 0, corresponding to the upper limit. Sum mode target slip ratio y Ｓ The upper and lower limit information is transmitted to the sum mode target slip ratio limiting unit 34, and the difference mode target slip ratio y ＤThe upper and lower limit information is transmitted to the differential mode target slip ratio limiting unit 35.

[0093] Japanese mode target slip ratio y Ｓ The upper and lower limits are set as variable values ​​based on parameters related to the driver's input, such as accelerator opening, brake pedal stroke, and steering angle. Alternatively, the sum mode target slip ratio y Ｓ The upper and lower limits are set as variable values ​​based on parameters related to the driving state of the vehicle 1, such as vehicle speed, required torque, yaw rate, roll rate, pitch rate, and steering angle of the wheels 5.

[0094] Figure 9(A) shows the sum mode target slip ratio y based on the total required torque. Ｓ This graph shows examples of setting upper limits (solid line) and lower limits (dashed line). Total required torque refers to, for example, the required torque T for the front axle. ＦＬ and the required torque T for the rear axle ＲＬ This is the torque equivalent to the sum of the torques required for the front wheels 5F and the rear wheels 5R of vehicle 1. The value of the total required torque is calculated, for example, based on the accelerator opening, brake pedal stroke, and vehicle speed (motor angular velocity).

[0095] In Figure 9(A), the total required torque is a positive predetermined value T. １ If it is less than the target slip ratio y of the sum mode, Ｓ The upper limit of is a positive predetermined value y １ It is set to a predetermined negative value -y １ It is set to a predetermined value T. ２ That's all (however T １ <T ２ ) If this is the case, the target slip ratio y of the sum mode Ｓ The upper limit of is a positive predetermined value y ２ (However, y １ <y ２ ) is set to a predetermined negative value -y ２ It is set to a predetermined value T. １ The above and the predetermined value T ２If the value is less than the given value, the absolute values ​​of the upper and lower limits increase as the total required torque increases.

[0096] Figure 9(B) shows the differential mode target slip ratio y based on the steering angle. Ｄ This graph shows examples of setting the upper limit (solid line) and lower limit (dashed line) of the steering angle. Here, the predetermined value -T is negative. ３ A predetermined value T that is greater than or equal to and positive ３ If it is less than the differential mode target slip ratio y Ｄ Both the upper and lower limits are set to 0. The steering angle is a positive predetermined value T. ４ That's all (however T ３ <T ４ ) or a negative predetermined value -T ４ If it is less than the difference mode target slip ratio y Ｄ The upper limit of is a positive predetermined value y ３ It is set to a predetermined negative value -y ３ It is set to a predetermined value T. ３ The above and the predetermined value T ４ If the value is less than T, the absolute values ​​of the upper and lower limits increase as the steering angle increases. Also, if the steering angle is less than the predetermined value - T ４ The above and the predetermined value - T ３ If the value is less than the specified limit, the larger the steering angle, the smaller the absolute values ​​of the upper and lower limits become.

[0097] The sum mode target slip ratio limiting unit 34 controls the sum mode target slip ratio y set in the upper and lower limit setting unit 39. Ｓ Based on the upper and lower limit information, the sum mode target slip ratio y Ｓ The value is limited so that it falls within the range from the lower limit to the upper limit. The sum mode target slip ratio y calculated by the calculation unit 11 (sum mode target slip ratio calculation unit 32) Ｓ If the value exceeds the upper limit, that value is replaced with the upper limit and output from the sum mode target slip ratio limiting unit 34. Conversely, the sum mode target slip ratio y Ｓ If the value is less than the lower limit, that value is replaced with the lower limit and output from the sum mode target slip ratio limiting unit 34. Sum mode target slip ratio y ＳIf the value is greater than or equal to the lower limit and less than or equal to the upper limit, the value is output as is from the sum mode target slip ratio limiting unit 34.

[0098] Similarly, the differential mode target slip ratio limiting unit 35 limits the differential mode target slip ratio y set in the upper and lower limit setting unit 39. Ｄ Based on the upper and lower limit information, the differential mode target slip ratio y Ｄ The value is limited so that it falls within the range from the lower limit to the upper limit. The differential mode target slip rate y calculated by the calculation unit 11 (differential mode target slip rate calculation unit 33) Ｄ If the value exceeds the upper limit, that value is replaced with the upper limit and output from the differential mode target slip ratio limiting unit 35. Conversely, the differential mode target slip ratio y Ｄ If the value is less than the lower limit, that value is replaced with the lower limit and output from the differential mode target slip ratio limiting unit 35. Differential mode target slip ratio y Ｄ If the value is greater than or equal to the lower limit and less than or equal to the upper limit, the value is output as is from the differential mode target slip ratio limiting unit 35.

[0099] The sum-and-difference wheel speed calculation unit 36 ​​calculates the sum-mode reference wheel speed, which corresponds to the sum of the front axle reference wheel speed and the rear axle reference wheel speed, and the difference-mode reference wheel speed, which corresponds to the difference between the front axle reference wheel speed and the rear axle reference wheel speed. The value of the sum-mode reference wheel speed is, for example, half of the sum of the front axle reference wheel speed and the rear axle reference wheel speed, and the value of the difference-mode reference wheel speed is, for example, half of the difference between the front axle reference wheel speed and the rear axle reference wheel speed. The values ​​of the front axle reference wheel speed and the rear axle reference wheel speed are calculated based on, for example, the detected value of the wheel speed sensor 18 and the steering angle.

[0100] The multiplier 37 receives the sum mode target slip ratio y output from the sum mode target slip ratio limiting unit 34. Ｓ The sum mode target wheel speed is output by multiplying it by the sum mode reference wheel speed. The information of the sum mode target wheel speed output here is transmitted to the sum mode control unit 22 of the control unit 13. The multiplier 38 also receives the differential mode target slip ratio y output from the differential mode target slip ratio limiting unit 35. ＤThe differential mode target wheel speed is output by multiplying this value by the differential mode reference wheel speed. The information of the differential mode target wheel speed output here is transmitted to the differential mode control unit 23 of the control unit 13.

[0101] As shown in Figure 2, the sum mode control unit 22 sets the sum mode target slip ratio y Ｓ Based on this, the sum mode torque is calculated to optimize the slip ratio of vehicle 1 when it is moving straight. The differential mode control unit 23 also calculates the differential mode target slip ratio y Ｄ Based on this, the differential mode torque is calculated to optimize the slip ratio during vehicle 1's turning. The sum mode torque and differential mode torque information is transmitted to the front / rear conversion unit 24.

[0102] The front-to-rear conversion unit 24, like the front-to-rear conversion unit 57, performs calculations to distribute the sum mode torque obtained by the sum mode control unit 22 and the difference mode torque obtained by the difference mode control unit 23 to the front and rear motors 2. For example, the sum of the sum mode torque and the difference mode torque is used as the front motor instruction torque for slip control, and the difference between the sum mode torque and the difference mode torque is used as the rear motor instruction torque for slip control.

[0103] The final front motor instruction torque T is obtained by adding the front motor instruction torque for vibration damping control obtained in the front / rear conversion unit 57 and the front motor instruction torque for slip control obtained in the front / rear conversion unit 24. ＦＭ Similarly, the rear motor instruction torque for vibration damping control obtained in the front-to-rear conversion unit 57 and the rear motor instruction torque for slip control obtained in the front-to-rear conversion unit 24 are added together to obtain the final rear motor instruction torque T. ＲＭ This is the result.

[0104] [2-2. Application to On-board ECU] The vehicle control device 10 of the second embodiment may be mounted on the vehicle 1 separately from the existing on-board ECU, similar to the vehicle control device 10 of the first embodiment. Alternatively, the functions of the vehicle control device 10 of the second embodiment may be built into the existing on-board ECU. In other words, the vehicle control device 10 of the second embodiment may be applied to an existing on-board ECU. The method of applying the vehicle control device 10 to the vehicle 1 as shown in Figures 4 to 6 can be applied not only to the first embodiment but also to the second embodiment.

[0105] [2-3. Effects] (1) The vehicle control device 10 of the second embodiment controls the driving force of the front drive system and the rear drive system in a vehicle 1 which has a front drive system including a front wheel 5F to which power is transmitted from a front motor 2F (front drive source) and a rear drive system including a rear wheel 5R to which power is transmitted from a rear motor 2R (rear drive source). The vehicle control device 10 comprises a calculation unit 11, a limiting unit 12, and a control unit 13.

[0106] The calculation unit 11 calculates the sum mode target slip ratio y, which corresponds to the sum of the target slip ratios of the front wheel 5F and the rear wheel 5R. Ｓ The difference mode target slip ratio y corresponds to the difference between the target values ​​of each slip ratio and the target slip ratio. Ｄ The limiting unit 12 calculates the sum mode target slip ratio y. Ｓ and differential mode target slip ratio y Ｄ The slip ratio y of the sum mode after being limited by the limiting unit 12 is set by the upper and lower limits of each. Ｓ and differential mode target slip ratio y Ｄ Based on this, the driving force of the front and rear drive systems is controlled. Also, the sum mode target slip ratio y Ｓ The upper and lower limits are set variably.

[0107] Thus, the target slip ratio y in the sum mode Ｓ By setting the upper and lower limits as variable values, for example, the sum of the target slip ratios of the front wheel 5F and the rear wheel 5R can be increased to make slipping easier, or conversely, the sum of the target slip ratios of the front wheel 5F and the rear wheel 5R can be decreased to make slipping more difficult. Therefore, the target slip ratios of the front wheel 5F and the rear wheel 5R can be comprehensively changed, and the controllability related to the balance between longitudinal and lateral forces of the wheel 5 in the control of the front and rear wheels can be improved. This balance between longitudinal and lateral forces will be described in detail below.

[0108] Figure 10(A) is a graph showing the relationship between the actual slip ratio and longitudinal force [the longitudinal component of the frictional force acting on the wheels 5 (the circumferential component of the wheels 5)] when the vehicle 1 is turning. In Figure 10(A), four graphs show the relationship between the actual slip ratio and longitudinal force obtained when the magnitude of the lateral slip angle, which changes according to the steering angle, is changed in four stages. The thick solid line graph corresponds to the case where the lateral slip angle is relatively small, and the thin dashed line graph corresponds to the case where it is relatively large. Figure 10(B) is a graph showing the relationship between the actual slip ratio and lateral force [the lateral component of the frictional force acting on the wheels 5 (the component in the direction perpendicular to the circumferential direction of the wheels 5)] when the vehicle 1 is turning. In Figure 10(B), four graphs are also shown, corresponding to each of the four cases in which the magnitude of the lateral slip angle is changed in four stages.

[0109] As shown in Figure 10(A), in a turning state where the sideslip angle is relatively large (e.g., the fine dashed line graph), the actual slip ratio is λ １ from λ ２ If increased to this, the longitudinal force becomes F Ｘ１ From F Ｘ２ It increases to λ. In contrast, as shown in Figure 10(B), the lateral force is such that in a turning state where the sideslip angle is relatively large (for example, the thin dashed line graph), the actual slip ratio is λ １ from λ ２ By increasing it to F Ｙ１ From F Ｙ２ It decreases to [a certain point].

[0110] Here, the longitudinal force F in Figure 10(A) Ｘ１ , F Ｘ２ If the corresponding points are plotted as white circles in Figure 10(B), the actual slip ratio is λ １ from λ ２ By changing it to this, we can see that the relationship between the magnitudes of the longitudinal force and the lateral force is reversed. In other words, the actual slip ratio is λ １ When this is the case, the lateral force is greater than the longitudinal force (F Ｘ１ <F Ｙ１ ) whereas the actual slip ratio is λ ２ When this is the case, the longitudinal force is greater than the lateral force (F Ｙ２ <F Ｘ２ )

[0111] Therefore, the target slip ratio y in the sum mode Ｓ Setting a larger upper limit (and a smaller lower limit) allows for a larger absolute value of the actual slip ratio, which promotes an increase in longitudinal forces and a decrease in lateral forces. In other words, the sum mode target slip ratio y Ｓ By making the upper and lower limits variable, the balance between the longitudinal force and the lateral force of the wheel 5 can be changed. This allows the driver to increase the actual slip ratio by pressing the accelerator pedal harder, thereby increasing the longitudinal force and decreasing the lateral force, and achieving the desired turning state (e.g., a drift) as intended. Conversely, by releasing the accelerator pedal, the actual slip ratio can be decreased, increasing the lateral force and decreasing the longitudinal force, allowing the driver to achieve the desired turning state (e.g., a grip) as intended.

[0112] Furthermore, even when the turning radius of the front wheel 5F relative to the turning center differs from that of the rear wheel 5R relative to the turning center, or when these differ, the respective state quantities of the front wheel 5F and rear wheel 5R can be controlled with high precision. Therefore, controllability (e.g., control accuracy and control response speed) can be improved with a simple configuration.

[0113] (2) In the second embodiment, the sum mode target slip ratio y Ｓ The upper and lower limits of the slip ratio y can be changed according to parameters related to the driver's input. Specific examples of these parameters include accelerator opening, brake pedal stroke, and steering angle. With this configuration, an appropriate sum mode target slip ratio y can be obtained in response to the driver's input. Ｓ This allows for precise setting of the range. Therefore, the controllability related to the balance between the longitudinal and lateral forces of the wheel 5 can be further improved.

[0114] (3) In the second embodiment, the sum mode target slip ratio y ＳThe upper and lower limits of the slip ratio y can be changed according to parameters related to the driving state of vehicle 1. Specific examples of these parameters include vehicle speed, required torque, yaw rate, roll rate, pitch rate, and steering angles of the front wheels 5F and rear wheels 5R. With this configuration, an appropriate sum mode target slip ratio y can be set according to the driving state of vehicle 1. Ｓ This allows for precise setting of the range. Therefore, the controllability related to the balance between the longitudinal and lateral forces of the wheel 5 can be further improved.

[0115] (4) In the second embodiment, the sum mode target slip ratio y Ｓ Not only the upper and lower limits, but also the differential mode target slip ratio y Ｄ The upper and lower limits of this can also be set variably. With this configuration, the difference in the actual slip ratio of the front wheels 5F and the rear wheels 5R during turning can be appropriately adjusted to improve turning performance and stability. Note that the target slip ratio y in the difference mode Ｄ The upper and lower limits may be changed according to parameters related to the driver's input, or according to parameters related to the driving state of vehicle 1. With such a configuration, for example, an appropriate differential mode target slip ratio y in response to the driver's input. Ｄ This makes it possible to set the range with high precision. Therefore, the controllability related to the balance between longitudinal and lateral forces of the wheel 5 can be further improved. Also, for example, an appropriate sum mode target slip ratio y according to the driving state of the vehicle 1. Ｓ This allows for precise setting of the range. Therefore, the controllability related to the balance between the longitudinal and lateral forces of the wheel 5 can be further improved.

[0116] (5) The vehicle control device 10 of the second embodiment can be applied to the PHEV-ECU 10A (main ECU) as shown in Figure 5. In this case, the calculation unit 11, the limiting unit 12, and the control unit 13 are built into the PHEV-ECU 10A. With this configuration, the driving force calculation can be consolidated into the high-performance PHEV-ECU 10A, and the driving force calculation in the front MCU 10B and rear MCU 10C can be omitted.

[0117] (6) The vehicle control device 10 of the second embodiment can be applied to the front MCU 10B and the rear MCU 10C, respectively, as shown in Figure 6. In this case, the calculation unit 11, the limiting unit 12, and the control unit 13 are built into the front MCU 10B and the rear MCU 10C, respectively. With this configuration, the requested driving force for the front wheels and the requested driving force for the rear wheels can be quickly controlled in synchronization, without depending on the communication speed of the in-vehicle network.

[0118] (7) The vehicle control device 10 of the second embodiment may be applied to either the front MCU 10B or the rear MCU 10C. The calculation unit 11, limiting unit 12, and control unit 13 shown in Figure 7 are built into the rear MCU 10C. The control unit 13 calculates the front wheel control parameters and the rear wheel control parameters. The front wheel control parameters are used by the front MCU 10B to drive the front motor 2F. The rear wheel control parameters are used by the rear MCU 10C to drive the rear motor 2R. The control unit 13 of the rear MCU 10C calculates both of these parameters.

[0119] The rear MCU 10C controls the rear motor 2R using rear wheel control parameters and transmits front wheel control parameters to the front MCU 10B. The front MCU 10B controls the front motor 2F using these front wheel control parameters. Even with this configuration, the requested driving force for the front wheels and the requested driving force for the rear wheels can be controlled quickly and synchronously, without depending on the communication speed of the in-vehicle network. In addition, the computational load on the front MCU 10B can be reduced, and the performance required of the front MCU 10B can be lowered.

[0120] [3. Third Embodiment] The vehicle 1 relating to the vehicle control device 10 and vehicle control method as the third embodiment has the same configuration as the first embodiment, as illustrated in Figures 1 and 2. Hereinafter, elements that are the same as (or corresponding to) the first embodiment will be denoted by the same reference numerals and described accordingly, and redundant content will be omitted as appropriate. In the vehicle control device 10 of the third embodiment as well, the limiting unit 12 is the sum mode target slip ratio y Ｓ and differential mode target slip ratio y Ｄ Set the upper and lower limits.

[0121] [3-1. Specific Example] Figure 11 is a block diagram showing a specific control example by the slip setting unit 21. In addition to the calculation unit 11 and limiting unit 12 mentioned above, the slip setting unit 21 is provided with a front / rear calculation unit 66, multipliers 37, 38, and sum / difference calculation unit 69. The calculation unit 11 is provided with a sum / difference calculation unit 31, a sum mode target slip ratio calculation unit 32, and a difference mode target slip ratio calculation unit 33. The limiting unit 12 is provided with an upper / lower limit setting unit 40, a sum mode target slip ratio limiting unit 34, and a difference mode target slip ratio limiting unit 35.

[0122] The sum-difference calculation unit 31 calculates the sum-mode torque deviation, which corresponds to the sum of the front axle torque deviation and the rear axle torque deviation, and the difference-mode torque deviation, which corresponds to the difference between the front axle torque deviation and the rear axle torque deviation. The value of the sum-mode torque deviation is, for example, half of the sum of the front axle torque deviation and the rear axle torque deviation (sum of the deviations). The sum-mode torque deviation information is transmitted to the sum-mode target slip ratio calculation unit 32. The difference-mode torque deviation value is, for example, half of the difference between the front axle torque deviation and the rear axle torque deviation (amount of difference between the deviations). The difference-mode torque deviation information is transmitted to the difference-mode target slip ratio calculation unit 33.

[0123] The sum mode target slip ratio calculation unit 32 calculates the sum mode target slip ratio y, which corresponds to the sum of the target values ​​of the slip ratios of the front wheels 5F and the rear wheels 5R. Ｓ This calculates the sum mode target slip ratio y based on the required driving force and estimated driving force of vehicle 1. Ｓ The following is calculated: For example, the sum mode target slip ratio y is calculated based on the value obtained by integrating the value obtained by subtracting the estimated driving force from the required driving force (error). Ｓ The following is calculated. In this embodiment, the sum mode target slip ratio y is calculated based on the value obtained by integrating the sum mode torque deviation. Ｓ The sum mode target slip ratio y calculated here is then used. Ｓ This information is transmitted to the sum mode target slip ratio limiting unit 34.

[0124] The differential mode target slip ratio calculation unit 33 calculates the differential mode target slip ratio y, which corresponds to the difference between the target values ​​of the slip ratios of the front wheels 5F and the rear wheels 5R. ＤThis calculates the differential mode target slip ratio y based on the required driving force and estimated driving force of vehicle 1. Ｄ The following is calculated: For example, the differential mode target slip ratio y is calculated based on the value obtained by integrating the value obtained by subtracting the estimated driving force from the required driving force (error). Ｄ The following is calculated. In this embodiment, the differential mode target slip ratio y is calculated based on the value obtained by integrating the differential mode torque deviation. Ｄ The following is calculated: The difference mode target slip ratio y calculated here Ｄ This information is transmitted to the differential mode target slip ratio limiting unit 35.

[0125] The upper and lower limit setting unit 40 sets the target slip ratio y for the sum mode. Ｓ and differential mode target slip ratio y Ｄ The upper limit y for each of the following ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This sets the following: For example, the restricted sum mode target slip ratio y output from the limiting unit 12. Ｓ and differential mode target slip ratio y Ｄ However, in order to stay within the slip ratio range that simulates the tire limits of the front wheel 5F and the rear wheel 5R, the upper limit value y for each is set. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This is set. Note that the upper limit value y ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ The value is preferably set within a slip ratio range that simulates the tire limit, but it is also possible to set it to a value that exceeds the slip ratio range to the extent that the stability of vehicle 1 is maintained.

[0126] These upper limits y ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬThis may be set based on the actual slip ratio of the front wheels 5F and rear wheels 5R (parameters corresponding to the actual slip ratio). Alternatively, instead of the actual slip ratio (parameters corresponding to the actual slip ratio), it may be set based on the target slip ratio of the front wheels 5F and rear wheels 5R (parameters corresponding to the target slip ratio). Or, it may be set based on the required driving force of vehicle 1 (parameters corresponding to the required driving force).

[0127] For example, the upper limit y mentioned above. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This is the sum mode actual slip ratio λ Ｓ or difference mode actual slip ratio λ Ｄ It may be set based on the sum mode actual slip ratio λ. Ｓ This parameter corresponds to the sum of the actual slip ratios of the front wheel 5F and the rear wheel 5R. Similarly, the difference mode actual slip ratio λ Ｄ This parameter corresponds to the difference in the actual slip ratio between the front wheel 5F and the rear wheel 5R.

[0128] Also, the above upper limit y ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This is the sum mode target slip ratio y calculated by the calculation unit 11. Ｓ Ya difference mode target slip ratio y Ｄ It may be set based on the limited sum mode target slip ratio y output from the limiting unit 12. Ｓ and differential mode target slip ratio y Ｄ It may be set based on the following. Also, the sum mode required driving force F Ｓ or difference mode required driving force F Ｄ It may be set based on the sum mode indicated torque T Ｓ Differential mode indicated torque T Ｄ It may be set based on this.

[0129] [3-2. Setting Upper and Lower Limits Based on Actual Slip Ratio] Sum Mode Actual Slip Ratio λ Ｓ and differential mode actual slip ratio λ Ｄ The value of is calculated based on, for example, the following formula: λ in the formula Ｒis the rear-wheel actual slip ratio, λ Ｆ is the front-wheel actual slip ratio. The combined-mode actual slip ratio λ Ｓ is, for example, the rear-wheel actual slip ratio λ Ｒ and the front-wheel actual slip ratio λ Ｆ is set to be half of their sum. The differential-mode actual slip ratio λ Ｄ is, for example, the rear-wheel actual slip ratio λ Ｒ and the front-wheel actual slip ratio λ Ｆ is set to be half of their difference. Incidentally, the rear-wheel actual slip ratio λ Ｒ , the front-wheel actual slip ratio λ Ｆ is, for example, the value obtained by dividing the absolute value of the difference between the reference wheel speed (the vehicle body speed in the vicinity of each wheel 5) and the actual wheel speed for each wheel 5 by the reference wheel speed. The reference wheel speed is calculated based on, for example, the vehicle body speed, yaw rate, vehicle specifications, etc. at the vehicle center of gravity point.

[0130]

[0131] [ A ] Combined-Mode Priority Logic Diagram 12(A) is a graph for explaining a method of setting the upper limit value y Ｓ of the differential-mode target slip ratio y Ｄ based on the combined-mode actual slip ratio λ ＤＨ In this method, it is assumed that the upper limit value y Ｓ of the combined-mode target slip ratio y ＳＨ is set in advance to the first predetermined value y １ The upper limit value y Ｄ of the differential-mode target slip ratio y ＤＨ is set so that the combined-mode target slip ratio y Ｓ and the differential-mode target slip ratio y Ｄ are at least within the region surrounded by the graph shown by the solid line in FIG. 12(A), the X-axis, and the Y-axis. This region corresponds to the part in the first quadrant of the above-mentioned "slip ratio range simulating the tire limits of the front wheels 5F and the rear wheels 5R".

[0132] The first predetermined value y １ is a value set in advance as the maximum value that the combined-mode target slip ratio y Ｓ can take (0 ≤ y １ ≤ 1). The third predetermined value y ３ is the differential-mode target slip ratio y ＤThis is a value that has been provisionally set as the maximum value that can be taken (0 ≤ y ３ ≦1). second predetermined value y ２ This is the differential mode target slip ratio y Ｄ The maximum value (y ３ ) When this is the case, the target slip ratio y of the sum mode Ｓ This is a value that has been set in advance as the maximum value that can be taken (0 ≤ y ２ ≤ y １ ). Fourth predetermined value y ４ This is the target slip ratio y in the sum mode. Ｓ The maximum value (y １ ) When the difference mode target slip ratio y is Ｄ This is a value that has been set in advance as the maximum value that can be taken (0 ≤ y ４ ≤ y ３ ).

[0133] Note that the second predetermined value y ２ , fourth predetermined value y ４ If both are not 0, the shape of the region enclosed by the graph shown by the solid line and the X and Y axes will be a pentagon (home plate shape), as shown in Figure 12(A). Second predetermined value y ２ , fourth predetermined value y ４ If only one of the two is 0, the shape of the region enclosed by the graph shown by the solid line, the X axis, and the Y axis will be a rectangle (trapezoid). Second predetermined value y ２ , fourth predetermined value y ４ When both are 0, the shape of the region enclosed by the graph shown by the solid line, the X-axis, and the Y-axis is triangular.

[0134] The upper and lower limit setting unit 40 assumes a point moving along the graph shown by the solid line in Figure 12(A), where the X coordinate is the sum mode actual slip ratio λ. Ｓ The value of the Y coordinate of the corresponding point is the difference mode target slip ratio y Ｄ Upper limit y ＤＨ Set it as follows: For example, the sum mode actual slip ratio λ Ｓ The second predetermined value y ２ If less than the third predetermined value y ３ The upper limit value y ＤＨ It outputs as follows. Also, the sum mode actual slip ratio λ Ｓ The second predetermined value y ２ The first predetermined value y is as described above. １If less than , the upper limit of the magnitude y depends on the slope of the graph. ＤＨ Outputs the sum mode actual slip ratio λ. Ｓ is the first predetermined value y １ If the above is true, then the fourth predetermined value y ４ The upper limit value y ＤＨ Output as follows. Note that the differential mode target slip ratio y Ｄ Lower limit y ＤＬ The upper limit is y ＤＨ Assume that the absolute values ​​are the same negative values.

[0135] With this setting, the sum mode actual slip ratio λ Ｓ The smaller the difference, the more the target slip ratio y of the differential mode. Ｄ Upper limit y ＤＨ The slip rate y increases as the differential mode target slip rate y rises. Ｄ It becomes permissible to increase the sum mode actual slip ratio λ. Ｓ The larger the difference, the more the target slip ratio y of the differential mode. Ｄ Upper limit y ＤＨ The differential mode target slip ratio y decreases. Ｄ This is limited to a small value. Therefore, the longitudinal and lateral forces of the wheels 5 are efficiently utilized in the control of the driving force of the front and rear wheels.

[0136] Sum mode actual slip ratio λ Ｓ The target slip ratio y based on the difference mode. Ｄ Upper limit y ＤＨ The following is an example of a calculation formula related to the setting.

[0137] [B] Difference mode priority logic diagram 12(B) shows the difference mode actual slip ratio λ Ｄ Based on the sum mode target slip ratio y Ｓ Upper limit y ＳＨ This graph illustrates the method for setting the differential mode target slip ratio y. Ｄ Upper limit y ＤＨ However, a third predetermined value y is set in advance. ３ It is assumed that the setting is as follows. The upper and lower limit setting unit 40 assumes a point that moves along the graph shown by the solid line in Figure 12(B), and the Y coordinate is the difference mode actual slip ratio λ. Ｄ The sum of the X-coordinate values ​​of the corresponding points is the target slip ratio y.Ｓ Upper limit y ＳＨ Set it as follows.

[0138] For example, the differential mode slip ratio λ Ｄ is the fourth predetermined value y ４ If less than the first predetermined value y １ The upper limit value y ＳＨ It outputs as follows. Also, the differential mode actual slip ratio λ Ｄ is the fourth predetermined value y ４ The third predetermined value y is as described above. ３ If less than , the upper limit of the magnitude y depends on the slope of the graph. ＳＨ Outputs the difference mode actual slip ratio λ. Ｄ is the third predetermined value y ３ If the above is true, then the second predetermined value y ２ The upper limit value y ＳＨ Output as follows. Note that the target slip ratio y in sum mode Ｓ Lower limit y ＳＬ The upper limit is y ＳＨ Assume that the absolute values ​​are the same negative values.

[0139] With this setting, the differential mode actual slip ratio λ Ｄ The smaller the value, the more the target slip rate y in the sum mode. Ｓ Upper limit y ＳＨ As the value increases, the target slip rate y in the sum mode increases. Ｓ It becomes permissible to increase the differential mode slip ratio λ. Ｄ The larger the sum mode target slip ratio y, the greater the sum mode target slip ratio y. Ｓ Upper limit y ＳＨ As the sum mode target slip rate y decreases, Ｓ This is limited to a small value. Therefore, the longitudinal and lateral forces of the wheels 5 are efficiently utilized in the control of the driving force of the front and rear wheels.

[0140] Differential mode actual slip ratio λ Ｄ The target slip ratio y based on the sum mode. Ｓ Upper limit y ＳＨ The following is an example of a calculation formula related to the setting.

[0141] [3-3. Setting Upper and Lower Limits Based on Target Slip Ratio] The sum mode actual slip ratio λ ＳThis is the target slip ratio y in the sum mode. Ｓ It can be replaced with the above difference mode actual slip ratio λ Ｄ This is the differential mode target slip ratio y Ｄ It can be replaced with the sum mode target slip ratio y used here. Ｓ and differential mode target slip ratio y Ｄ The value may be the value calculated by the calculation unit 11, or it may be the value after restriction output from the restriction unit 12.

[0142] For example, in the graph shown in Figure 12(A), the sum mode actual slip ratio λ Ｓ Instead, the target slip rate y in the sum mode Ｓ By applying this, the target slip ratio y of the differential mode Ｄ Upper limit y ＤＨ You may also set this. Also, in the graph shown in Figure 12(B), the difference mode actual slip ratio λ Ｄ Instead, the differential mode target slip ratio y Ｄ By applying this, the target slip ratio y of the sum mode Ｓ Upper limit y ＳＨ You may set it to that.

[0143] [3-4. Setting Upper and Lower Limits Based on Required Driving Force] Sum Mode Required Driving Force F Ｓ and differential mode required driving force F Ｄ The value of is the required driving force for the front wheels 5F, which is the required driving force for the front wheels F. Ｆ The required driving force for the rear wheel 5R is the rear wheel required driving force F. Ｒ It is calculated based on the following: Sum mode required driving force F Ｓ The value of is, for example, the required driving force F of the front wheels. Ｆ and rear wheel required driving force F Ｒ It is considered to be half of the sum, and the difference mode required driving force F Ｄ The value of is, for example, the required driving force F of the front wheels. Ｆ and rear wheel required driving force F Ｒ It is said to be half the difference. Front wheel required driving force F Ｆ and rear wheel required driving force F Ｒ Each of these is calculated based on, for example, the accelerator opening, brake pedal stroke, steering angle, vehicle speed, road inclination, yaw rate, etc.

[0144] Figure 13(A) shows the sum mode required driving force F Ｓ and differential mode required driving force F Ｄ Based on the sum mode target slip ratio y Ｓ Upper limit y ＳＨ and differential mode target slip ratio y Ｄ Upper limit y ＤＨ This graph illustrates the method for setting the upper and lower limit setting unit 40. In the coordinate system shown in Figure 13(A), the slope of the sum mode required driving force F Ｓ Differential mode required driving force F Ｄ Assume a straight line passing through the origin that is equal to the ratio of (driving force ratio). Also, the X coordinate of the intersection point of this straight line and the solid line graph in Figure 13(A) is the sum of the mode target slip ratio y Ｓ Upper limit y ＳＨ Set as follows, and the Y coordinate of the intersection is the difference mode target slip ratio y Ｄ Upper limit y ＤＨ Set as follows: Here, "Sum mode target slip ratio y" Ｓ Upper limit y ＳＨ The target slip ratio y for the differential mode. Ｄ Upper limit y ＤＨ If we define the ratio of the upper limit as the upper limit ratio, the upper and lower limit setting unit 40 sets two upper limit values ​​y such that the upper limit ratio matches the driving force ratio. ＳＨ , y ＤＨ This means that the setting is configured as follows:

[0145] With this setting, the differential mode required driving force F Ｄ The smaller the relative value (i.e., the smaller the driving force ratio), the target slip ratio y in sum mode. Ｓ Upper limit y ＳＨ As it rises, the differential mode target slip rate y Ｄ Upper limit y ＤＨ This reduces the sum mode target slip ratio y. Ｓ It becomes easier to tolerate an increase in the differential mode target slip ratio y Ｄ This tends to limit the value to a small one.

[0146] Conversely, the difference mode required driving force F Ｄ The larger the relative size (i.e., the larger the driving force ratio), the greater the target slip ratio y in the differential mode. ＤThe upper limit value y ＤＨ increases, and the upper limit value y Ｓ of the sum mode target slip ratio y ＳＨ decreases. As a result, it becomes easier to increase the difference mode target slip ratio y Ｄ , and the sum mode target slip ratio y Ｓ tends to be restricted to a small value. In any case, it becomes possible to efficiently utilize the longitudinal and lateral forces of the wheel 5 in the driving force control of the front and rear wheels.

[0147] The upper limit value y Ｓ based on the sum mode required driving force F Ｄ and the difference mode required driving force F ＳＨ , y ＤＨ is calculated as follows.

[0148] The example shown in FIG. 13(B) is a graph for explaining a setting method when two upper limit values y ＳＨ , y ＤＨ are set so that the upper limit value ratio is proportional to the driving force ratio. In this example, the upper limit value ratio does not exactly match the driving force ratio, but two upper limit values y ＳＨ , y ＤＨ are set so that the upper limit value ratio matches the product of a predetermined coefficient k (proportionality constant) and the driving force ratio. As a result, the larger the driving force ratio, the larger the upper limit value ratio, and the smaller the driving force ratio, the smaller the upper limit value ratio. The value of the coefficient k may be a preset fixed value or a variable value that varies according to the running state of the vehicle 1 or the driver's operation. The case where the value of the coefficient k is 1 corresponds to the example shown in FIG. 13(A).

[0149] The upper and lower limit setting unit 40 assumes a straight line passing through the origin whose slope is equal to "the product of a predetermined coefficient k and the ratio of the difference mode required driving force F Ｓ to the sum mode required driving force F Ｄ (driving force ratio)" in the coordinate system shown in FIG. 13(B). Further, the X coordinate of the intersection of this straight line and the solid line graph in FIG. 13(B) is set as the upper limit value y Ｓ of the sum mode target slip ratio y ＳＨ , and the Y coordinate of the intersection is set as the upper limit value y Ｄ of the difference mode target slip ratio y ＤＨis set as such. Even in such a setting, it is possible to efficiently utilize the longitudinal and lateral forces of the wheel 5 in the driving force control of the front and rear wheels. Also, by changing the value of the coefficient k, the balance between the sum-mode target slip ratio y Ｓ and the difference-mode target slip ratio y Ｄ can be adjusted.

[0150] For example, when k is set to a value smaller than 1, the slope of the straight line in Fig. 13(B) becomes smaller. That is, the upper limit value y Ｓ of the sum-mode target slip ratio y ＳＨ tends to increase, and the upper limit value y Ｄ of the difference-mode target slip ratio y ＤＨ tends to decrease. As a result, slip control that emphasizes acceleration and deceleration performance (motion performance in the straight-ahead direction) can be realized. If k is set to 0, it will behave similarly to the above sum-mode priority logic.

[0151] Also, when k is set to a value larger than 1, the slope of the straight line in Fig. 13(B) becomes larger. That is, the upper limit value y Ｄ of the difference-mode target slip ratio y ＤＨ tends to increase, and the upper limit value y Ｓ of the sum-mode target slip ratio y ＳＨ tends to decrease. As a result, slip control that emphasizes turning performance (motion performance in the turning direction) can be realized. If k is set to infinity (the maximum value allowed in control), it will behave similarly to the above difference-mode priority logic.

[0152] The calculation formulas for setting the upper limit values y Ｄ / F Ｓ and y ＳＨ , y ＤＨ based on the driving force ratio (F Ｄ / F Ｓ ) and the coefficient k are exemplified below.

[0153] [3-5. Setting of upper and lower limit values based on required torque] The above sum-mode required driving force F Ｓ can be replaced with the sum-mode torque, and the above difference-mode required driving force F ＤThis can be replaced with differential mode torque. The values ​​of sum mode torque and differential mode torque used here may be values ​​calculated by the sum-difference conversion unit 53, or the front axle required torque T set by the required driving force setting unit 51. ＦＬ and the required torque T for the rear axle ＲＬ The value may be calculated based on [the formula / method].

[0154] For example, in the graph shown in Figure 13(A), let's assume a straight line passing through the origin with a slope equal to the "ratio of differential mode torque to sum mode torque (torque ratio)," and set the X and Y coordinates of the intersection point of this straight line and the solid line graph in Figure 13(A) to the upper limit value y. ＳＨ , y ＤＨ It may also be set as follows. The same applies to the graph shown in Figure 13(B), where the upper limit ratio is proportional to the torque ratio, and the two upper limits y ＳＨ , y ＤＨ You may set it to that.

[0155] As shown in Figure 11, the sum mode target slip ratio limiting unit 34 limits the sum mode target slip ratio y set in the upper and lower limit setting unit 40. Ｓ Upper limit y ＳＨ and lower limit y ＳＬ Based on the information, the target slip ratio y in the sum mode Ｓ The lower limit y ＳＬ From the upper limit y ＳＨ The value is limited so that it falls within the specified range. The sum mode target slip ratio y calculated by the calculation unit 11 (sum mode target slip ratio calculation unit 32) Ｓ The value of the upper limit y ＳＨ If it exceeds the upper limit y, ＳＨ It is replaced and output from the sum mode target slip ratio limiting unit 34. Conversely, the sum mode target slip ratio y Ｓ The value of the lower limit y ＳＬ If the value is less than the lower limit y, then that value is the lower limit y. ＳＬ It is replaced and output from the sum mode target slip ratio limiting unit 34. Sum mode target slip ratio y Ｓ The value of the lower limit y ＳＬ The above and the upper limit y ＳＨ If the value is less than or equal to the following, the value as is will be output from the sum mode target slip ratio limiting unit 34.

[0156] Similarly, the differential mode target slip ratio limiting unit 35 limits the differential mode target slip ratio y set in the upper and lower limit setting unit 40. Ｄ Upper limit y ＤＨ and lower limit y ＤＬ Based on the information, the differential mode target slip ratio y Ｄ The lower limit y ＤＬ From the upper limit y ＤＨ The value is limited so that it falls within the specified range. The differential mode target slip ratio y calculated by the calculation unit 11 (differential mode target slip ratio calculation unit 33) Ｄ The value of the upper limit y ＤＨ If it exceeds the upper limit y, ＤＨ It is replaced and output from the differential mode target slip ratio limiting unit 35. Conversely, the differential mode target slip ratio y Ｄ The value of the lower limit y ＤＬ If the value is less than the lower limit y, then that value is the lower limit y. ＤＬ It is replaced and output from the differential mode target slip ratio limiting unit 35. Differential mode target slip ratio y Ｄ The value of the lower limit y ＤＬ The above and the upper limit y ＤＨ If the value is less than or equal to the following, the value is output as is from the differential mode target slip ratio limiting unit 35.

[0157] The front / rear calculation unit 66 calculates the sum mode target slip ratio y obtained by the sum mode target slip ratio limiting unit 34. Ｓ and the differential mode target slip ratio y obtained by the differential mode target slip ratio limiting unit 35 Ｄ This involves performing a calculation to convert the sum of the mode target slip ratio y. Ｓ and difference mode target slip ratio y Ｄ The difference is the target slip ratio y of the rear wheel 5R. Ｒ This is then transmitted to the multiplier 37. Also, the sum mode target slip ratio y Ｓ and difference mode target slip ratio y Ｄ The sum of these is the target slip ratio y for the front wheel 5F. Ｆ This is then transmitted to the multiplier 38.

[0158] The multiplier 37 receives the target slip ratio y output from the front / rear calculation unit 66.Ｒ The product of the target slip ratio y output from the front / rear calculation unit 66 is calculated and output to the sum / difference calculation unit 69. Similarly, the multiplier 38 calculates the product of the target slip ratio y output from the front / rear calculation unit 66. Ｆ The product of the front wheel 5F's reference wheel speed is calculated and output to the sum-difference calculation unit 69. The sum-difference calculation unit 69 calculates the sum mode target wheel speed and the difference mode target wheel speed based on the two values ​​output from the multipliers 37 and 38. The sum mode target wheel speed is, for example, half of the sum of the two values ​​output from the multipliers 37 and 38, and the difference mode target wheel speed is, for example, half of the difference between the two values ​​output from the multipliers 37 and 38. As shown in Figure 2, the sum mode target wheel speed information is transmitted to the sum mode control unit 22 of the control unit 13, and the difference mode target wheel speed information is transmitted to the difference mode control unit 23 of the control unit 13.

[0159] The sum mode control unit 22 calculates the sum mode torque to optimize the slip ratio of the vehicle 1 when it is moving straight, based on the sum mode target wheel speed obtained by the slip setting unit 21. The difference mode control unit 23 calculates the difference mode torque to optimize the slip ratio of the vehicle 1 when it is turning, based on the difference mode target wheel speed obtained by the slip setting unit 21.

[0160] The front-to-rear conversion unit 24, like the front-to-rear conversion unit 57, performs calculations to distribute the sum mode torque obtained by the sum mode control unit 22 and the difference mode torque obtained by the difference mode control unit 23 to the front and rear motors 2. For example, the sum of the sum mode torque and the difference mode torque is used as the front motor instruction torque for slip control, and the difference between the sum mode torque and the difference mode torque is used as the rear motor instruction torque for slip control.

[0161] The final front motor instruction torque T is obtained by adding the front motor instruction torque for vibration damping control obtained in the front / rear conversion unit 57 and the front motor instruction torque for slip control obtained in the front / rear conversion unit 24. ＦＭ Similarly, the rear motor instruction torque for vibration damping control obtained in the front-to-rear conversion unit 57 and the rear motor instruction torque for slip control obtained in the front-to-rear conversion unit 24 are added together to obtain the final rear motor instruction torque T. ＲＭ This is the result.

[0162] [3-6. Application to On-board ECU] The vehicle control device 10 of the third embodiment may be mounted on the vehicle 1 separately from the existing on-board ECU, similar to the vehicle control device 10 of the first embodiment. Alternatively, the functions of the vehicle control device 10 of the third embodiment may be built into the existing on-board ECU. In other words, the vehicle control device 10 of the third embodiment may be applied to an existing on-board ECU. The method of applying the vehicle control device 10 to the vehicle 1 as shown in Figures 4 to 6 can be applied not only to the first embodiment but also to the third embodiment.

[0163] [3-7. Effects] (1) The vehicle control device 10 of the third embodiment controls the driving force of the front drive system and the rear drive system in a vehicle 1 which has a front drive system including a front wheel 5F to which power is transmitted from a front motor 2F (front drive source) and a rear drive system including a rear wheel 5R to which power is transmitted from a rear motor 2R (rear drive source). The vehicle control device 10 comprises a calculation unit 11, a limiting unit 12, and a control unit 13.

[0164] The calculation unit 11 calculates the sum mode target slip ratio y, which corresponds to the sum of the target slip ratios of the front wheel 5F and the rear wheel 5R. Ｓ The difference mode target slip ratio y corresponds to the difference between the target values ​​of each slip ratio and the target slip ratio. Ｄ The limiting unit 12 calculates the sum mode target slip ratio y. Ｓ and differential mode target slip ratio y Ｄ Each upper limit y ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ Set the target slip ratio y in the sum mode. Ｓ and differential mode target slip ratio y Ｄ This limits the slip ratio y of the sum mode so that it remains within the slip ratio range that simulates the tire limits of the front wheel 5F and the rear wheel 5R. Ｓ and differential mode target slip ratio y Ｄ The control unit 13 limits the sum mode target slip ratio y after it has been limited by the limiting unit 12. Ｓ and differential mode target slip ratio y Ｄ Based on this, the driving force of the front and rear drive systems is controlled.

[0165] With this configuration, for example, as shown in Figures 12(A) and 12(B), the sum mode target slip ratio y Ｓ and differential mode target slip ratio y Ｄ This makes it easier to reliably keep the slip ratio within the specified range, and allows for setting a target slip ratio in which the longitudinal and lateral forces of the wheel 5 are efficiently utilized in the control of the front and rear wheels. Therefore, it is possible to set a target slip ratio in which the longitudinal and lateral forces of the wheel 5 are efficiently utilized in the drive force control of the front and rear wheels.

[0166] Furthermore, according to the above configuration, the target slip ratio y of the sum mode Ｓ If the difference mode target slip ratio y increases, Ｄ The value becomes smaller, and the target slip ratio y in the sum mode Ｓ If it becomes smaller, the target slip ratio y in the differential mode will decrease. Ｄ This increases the slip ratio of the wheel 5. Therefore, the target slip ratio of the wheel 5 can be comprehensively changed, and the controllability related to the balance between the longitudinal force and the lateral force of the wheel 5 can be improved. This balance between the longitudinal force and the lateral force is as described in the second embodiment [see Figures 10(A) and (B)].

[0167] Therefore, the target slip ratio y in the sum mode Ｓ Upper limit y ＳＨ Make it larger (lower limit y) ＳＬ Setting it to a small value allows the absolute value of the actual slip ratio to be larger, which promotes an increase in longitudinal forces and a decrease in lateral forces. In other words, the sum mode target slip ratio y Ｓ Upper limit y ＳＨ and lower limit y ＳＬ By making this variable, the balance between the longitudinal force and the lateral force of wheel 5 can be changed. This allows the driver, for example, to increase the actual slip ratio by pressing the accelerator pedal harder, thereby increasing the longitudinal force and decreasing the lateral force, and achieving the desired turning state (e.g., a drift) as intended. Conversely, by releasing the accelerator pedal, the actual slip ratio can be decreased, increasing the lateral force and decreasing the longitudinal force, allowing the driver to achieve the desired turning state (e.g., a grip) as they wish.

[0168] Furthermore, even when the turning radius of the front wheel 5F relative to the turning center differs from that of the rear wheel 5R relative to the turning center, or when these differ, the respective state quantities of the front wheel 5F and rear wheel 5R can be controlled with high precision. Therefore, controllability (e.g., control accuracy and control response speed) can be improved with a simple configuration.

[0169] (2) The limiting unit 12 of the third embodiment has an upper limit value y based on the actual slip ratio of the front wheel 5F and the rear wheel 5R. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This allows setting the actual slip state of wheel 5 to an upper limit value y. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This can be reflected in the calculations. Therefore, the target slip ratio that efficiently utilizes the longitudinal and lateral forces of the wheel 5 can be set with precision, and the controllability related to the balance between the longitudinal and lateral forces of the wheel 5 can be further improved.

[0170] (3) The limiting portion 12 of the third embodiment is, for example, as shown in Figure 12(B), the difference mode actual slip ratio λ corresponding to the difference in the actual slip ratio of the front wheel 5F and the rear wheel 5R. Ｄ Based on this, the target slip ratio y in the sum mode Ｓ Upper limit y ＳＨ and lower limit y ＳＬ This allows setting the differential mode actual slip ratio λ. Ｄ Target slip ratio y in the sum mode Ｓ This can be reflected in the system, enabling slip control where turning performance (movement performance in the turning direction) is important.

[0171] (4) The limiting portion 12 of the third embodiment is, for example, as shown in Figure 12(A), the sum mode actual slip ratio λ which corresponds to the sum of the actual slip ratios of the front wheel 5F and the rear wheel 5R. Ｓ Based on this, the target slip ratio y of the differential mode Ｄ Upper limit y ＤＨ and lower limit y ＤＬ This allows setting the sum mode actual slip ratio λ. Ｓ Differential mode target slip ratio y ＤThis can be reflected in the system, enabling slip control that prioritizes acceleration and deceleration performance (straight-line motion performance).

[0172] (5) In the third embodiment, the limiting section 12 sets an upper limit value y based on the target slip ratio of the front wheel 5F and the rear wheel 5R. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This allows setting the upper limit value y without specifying the actual slip state of wheel 5. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This allows for setting a target slip ratio that efficiently utilizes the longitudinal and lateral forces of the wheel 5 with a simple control configuration, thereby further improving the controllability related to the balance between the longitudinal and lateral forces of the wheel 5.

[0173] (6) The limiting unit 12 of the third embodiment, as shown in Figure 13(A), sets an upper limit value y based on the required driving force of the vehicle 1. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This allows setting the upper limit value y to the actual driving force transmitted to the wheel 5. ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This can be reflected in the settings. Therefore, the target slip ratio that efficiently utilizes the longitudinal and lateral forces of the wheel 5 can be set with precision, and the controllability related to the balance between the longitudinal and lateral forces of the wheel 5 can be further improved.

[0174] (7) The limiting unit 12 of the third embodiment is a sum mode required driving force F which corresponds to the sum of the required driving forces at each of the front wheels 5F and the rear wheels 5R. Ｓ The difference mode required driving force F corresponds to the difference in required driving force between the front wheel 5F and the rear wheel 5R. Ｄ Based on the driving force ratio, which is the ratio of to the upper limit y ＳＨ , y ＤＨ and lower limit y ＳＬ , y ＤＬ This allows setting the driving force ratio to an upper limit value y. ＳＨ , y ＤＨ and lower limit yＳＬ , y ＤＬ This can be reflected in the settings. Therefore, the target slip ratio that efficiently utilizes the longitudinal and lateral forces of the wheel 5 can be set with precision, and the controllability related to the balance between the longitudinal and lateral forces of the wheel 5 can be further improved.

[0175] (8) The limiting portion 12 of the third embodiment is, for example, as shown in Figure 13(B), the sum mode target slip ratio y Ｓ Upper limit y ＳＨ and difference mode target slip ratio y Ｄ Upper limit y ＤＨ The upper limit ratio, which is the ratio of to the driving force ratio, can be made proportional to the driving force ratio. In this case, the characteristics (flavoring) of the slip control can be changed according to the coefficient k, which corresponds to the proportionality constant. For example, by setting the coefficient k to a small value, slip control that emphasizes acceleration / deceleration performance (motion performance in the straight direction) can be realized. Conversely, by setting the coefficient k to a large value, slip control that emphasizes turning performance (motion performance in the turning direction) can be realized.

[0176] (9) Furthermore, the limiting unit 12 of the third embodiment can change the proportionality constant (coefficient k) of the upper limit ratio to the driving force ratio according to the driving state of the vehicle 1 or the driver's operation. This makes it possible to change the characteristics (flavoring) of the slip control according to the driving state and the driver's operation, thereby further improving controllability and convenience.

[0177] (10) The vehicle control device 10 of the third embodiment can be applied to the PHEV-ECU 10A (main ECU) as shown in Figure 6. In this case, the calculation unit 11, the limiting unit 12, and the control unit 13 are built into the PHEV-ECU 10A. With this configuration, the driving force calculation can be consolidated into the high-performance PHEV-ECU 10A, and the driving force calculation in the front MCU 10B and rear MCU 10C can be omitted.

[0178] (11) The vehicle control device 10 of the third embodiment can be applied to the front MCU 10B and the rear MCU 10C, respectively, as shown in Figure 7. In this case, the calculation unit 11, the limiting unit 12, and the control unit 13 are built into the front MCU 10B and the rear MCU 10C, respectively. With this configuration, the requested driving force for the front wheels and the requested driving force for the rear wheels can be quickly controlled in synchronization, without depending on the communication speed of the in-vehicle network.

[0179] (12) The vehicle control device 10 of the third embodiment may be applied to either the front MCU 10B or the rear MCU 10C. The calculation unit 11, limiting unit 12, and control unit 13 shown in Figure 8 are built into the rear MCU 10C. The control unit 13 calculates the front wheel control parameters and the rear wheel control parameters. The front wheel control parameters are used by the front MCU 10B to drive the front motor 2F. The rear wheel control parameters are used by the rear MCU 10C to drive the rear motor 2R. The control unit 13 of the rear MCU 10C calculates both of these parameters.

[0180] The rear MCU 10C controls the rear motor 2R using rear wheel control parameters and transmits front wheel control parameters to the front MCU 10B. The front MCU 10B controls the front motor 2F using these front wheel control parameters. Even with this configuration, the requested driving force for the front wheels and the requested driving force for the rear wheels can be controlled quickly and synchronously, without depending on the communication speed of the in-vehicle network. In addition, the computational load on the front MCU 10B can be reduced, and the performance required of the front MCU 10B can be lowered.

[0181] In realizing the vehicle control device according to the present case, the driving force control methods described in the following reference documents can be referred to. - Hiroshi Fujimoto, Takeshi Takano, Hidehisa Nobumoto, Toshimi Okazaki, "Driving Force Control Technology by High-Precision Slip Ratio Control", Mazda Technical Report, No. 32, p. 228-233 (2015) - Hiroshi Fujimoto, Junya Amada, Takayuki Miyajima, "Development and Control of Electric Vehicles with Variable Drive Unit Systems", Proceedings of the 2013 Spring Annual Conference of the Japan Society of Automotive Engineers, No. 8-13, p. 17-20 (2013) - Masaki Yoshimura, Hiroshi Fujimoto, "Drive Torque Control Method for Electric Vehicles Equipped with In-Wheel Motors", Transactions of the Institute of Electrical Engineers of Japan D, Vol. 131, No. 5, p. 721-728 (2011)

[0182] The present case is applicable to the manufacturing industry of vehicle control devices mounted on vehicles, and is also applicable to the manufacturing industry of vehicles on which vehicle control devices are mounted.

[0183] 1 Vehicle 2 Motor 2F Front motor (front drive source) 2R Rear motor (rear drive source) 3 Transaxle 4 Axle 4F Front axle 4R Rear axle 5 Wheel 5F Front wheel 5R Rear wheel 6 Inverter 7 Battery 10 Vehicle control device 10A PHEV-ECU (main ECU) 10B Front MCU (second MCU) 10C Rear MCU (first MCU) 11 Calculation unit 12 Limiting unit 13 Control unit 14 Accelerator opening sensor 15 Brake sensor 16 Steering angle sensor 17 Resolver 18 Wheel speed sensor 21 Slip setting unit 22 Sum mode control unit 23 Difference mode control unit 24 Front-rear conversion unit 31 Sum-difference calculation unit 32 Sum mode target slip ratio calculation unit 33 Difference mode target slip ratio calculation unit 34 Sum mode target slip ratio limiting unit 35 Difference mode target slip ratio limiting unit 36 Sum-difference wheel speed calculation unit 39, 40 Upper and lower limit setting units 41 Second calculation unit 42 Front wheel target slip ratio calculation unit 43 Rear wheel target slip ratio calculation unit 44 Second limiting unit 45 Front wheel target slip ratio limiting unit 46 Rear wheel target slip ratio limiting unit 49 Sum-difference conversion unit 51 Required driving force setting unit 52 Estimated driving force observer 53 Sum-difference conversion unit 54 Vibration control unit 55 Sum mode control unit 56 Difference mode control unit 57 Front-rear conversion unit 66 Front-rear calculation unit 69 Sum-difference calculation unit yＳ Japanese mode target slip ratio y Ｄ Differential mode target slip ratio y Ｆ Front wheel target slip ratio y Ｒ Rear wheel target slip ratio

Claims

1. A vehicle control device for controlling the driving forces of a front drive system and a rear drive system, in a vehicle having a front drive system including front wheels to which power is transmitted from a front drive source and a rear drive system including rear wheels to which power is transmitted from a rear drive source, comprising: a calculation unit that calculates a sum mode target slip ratio corresponding to the sum of target values ​​of the slip ratios of the front wheels and the rear wheels and a difference mode target slip ratio corresponding to the difference between the target values ​​of the slip ratios; and a control unit that controls the driving forces using a sum mode instruction torque calculated based on the sum mode target slip ratio and a difference mode instruction torque calculated based on the difference mode target slip ratio.

2. The vehicle control device according to claim 1, characterized in that the calculation unit calculates the sum mode target slip ratio and the difference mode target slip ratio based on the required driving force and estimated driving force of the vehicle.

3. The vehicle control device according to claim 1, characterized in that it includes a limiting unit that sets upper and lower limits for the sum mode target slip ratio and the difference mode target slip ratio, and limits each of the sum mode target slip ratio and the difference mode target slip ratio calculated by the calculation unit to be less than or equal to the upper limit and greater than or equal to the lower limit.

4. The vehicle control device according to claim 3, characterized in that both the upper limit and the lower limit of the differential mode target slip ratio are 0.

5. The vehicle control device according to claim 1, further comprising a second calculation unit that calculates target values ​​for the slip ratios of the front and rear wheels, namely the front wheel target slip ratio and the rear wheel target slip ratio, wherein the control unit can control the respective driving forces to achieve both the front wheel target slip ratio and the rear wheel target slip ratio.

6. The vehicle control device according to claim 1, comprising a limiting unit that sets upper and lower limits for the sum mode target slip ratio and the difference mode target slip ratio, respectively, and wherein the control unit controls each of the driving forces based on the sum mode target slip ratio and the difference mode target slip ratio after they have been limited by the limiting unit.

7. The vehicle control device according to claim 6, characterized in that the upper limit and lower limit of the sum mode target slip ratio are variably set.

8. The vehicle control device according to claim 6, characterized in that the limiting unit sets the upper limit and the lower limit based on the actual slip ratio of the front wheel and the rear wheel.

9. The vehicle control device according to claim 1, characterized in that the calculation unit and the control unit are built into the main ECU.

10. The vehicle control device according to claim 1, characterized in that the calculation unit and the control unit are built into the front MCU and the rear MCU, respectively.

11. Assuming that either the front MCU or the rear MCU is defined as the first MCU and the other as the second MCU, the vehicle control device according to claim 1, characterized in that the calculation unit and the control unit are built into the first MCU, the control unit calculates front wheel control parameters for the front MCU to drive the front drive source and rear wheel control parameters for the rear MCU to drive the rear drive source, the first MCU controls one of the front drive source and the rear drive source using one of the front wheel control parameters and the rear wheel control parameters, and transmits the other of the front wheel control parameters and the rear wheel control parameters to the second MCU, and the second MCU controls the other of the front drive source and the rear drive source using the other of the front wheel control parameters and the rear wheel control parameters.

12. A vehicle control method for controlling the driving forces of a vehicle equipped with a front drive system including front wheels to which power is transmitted from a front drive source and a rear drive system including rear wheels to which power is transmitted from a rear drive source, characterized in that the method involves calculating a sum mode target slip ratio corresponding to the sum of target values ​​of the slip ratios of the front wheels and the rear wheels and a difference mode target slip ratio corresponding to the difference between the target values ​​of the slip ratios, calculating a sum mode instruction torque based on the sum mode target slip ratio and calculating a difference mode instruction torque based on the difference mode target slip ratio, and controlling the driving forces using the sum mode instruction torque and the difference mode instruction torque.

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