Vehicle driving control device

Abstract

Provided is a traction control device 50 for a vehicle having a front motor and rear motor that drive wheels, and braking devices respectively provided to the left and right wheels in the front and rear, the traction control device comprising a hybrid control unit 20 for calculating the required drive force for the vehicle on the basis of driver requirements and vehicle behavior, and a control unit 10, 12 for controlling the motors and braking devices on the basis of the required drive force. The hybrid control unit 20 comprises a reference wheel speed calculating part 52 that calculates a target reference wheel speed for each of the left and right wheels in the front and rear, and a target slip rate calculating / distributing part 54 that calculates a target slip rate for the wheels relative to the target reference wheel speeds. The control unit 10, 12 comprises a slip rate control part 62 that calculates the actual slip rate of the wheels and controls the motors and braking devices so as to match the actual slip rate to the target slip rate.

Description

[Technical Field]

[0001] The present invention relates to a vehicle cruise control device. [Background technology]

[0002] In recent years, in order to prevent skidding and improve cornering performance of a vehicle, braking / driving devices have been developed that control the drive torque and braking torque of the vehicle to different values ​​for the left and right wheels (traveling wheels). For example, Patent Document 1 describes, as prior art, a control device for a vehicle in which four wheels are independently driven by electric motors, which controls the drive of each of the four electric motors so that the turning acceleration of the vehicle body detected by a yaw rate sensor achieves a required turning acceleration calculated based on the steering angle, etc. Patent Document 1 also proposes a technology for controlling the drive of a first electric motor and a second electric motor and operating and controlling brake devices for the wheels to control the turning acceleration of the vehicle in a vehicle in which a first electric motor drives the left and right front wheels of the vehicle via a differential device and a second electric motor drives the left and right rear wheels of the vehicle via a differential device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-254590 Summary of the Invention [Problem to be solved by the invention]

[0004] In the vehicle of Patent Document 1, a main control unit (CPU) performs various calculations such as calculations of slip ratio, control amounts of each motor, and pressure adjustment amounts of the brake device. However, even when an electric motor is used, there is a possibility that a control delay may occur in the control unit, and therefore there is a demand for a drive control device that is capable of more responsive slip ratio control (traction control).

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a vehicle driving control device capable of highly responsive traction control. [Means for solving the problem]

[0006] In order to achieve the above object, the vehicle travel control device of the present invention is a vehicle travel control device that includes drive means for driving front, rear, left, and right wheels, and brake means for independently braking the front, rear, left, and right wheels, and that is capable of driving and braking the front, rear, left, and right wheels using the drive means and the brake means, and further includes a main control unit that calculates a required drive force of the vehicle based on a driver request and vehicle behavior, and a control unit that controls the drive means and the brake means downstream of the main control unit. braking means and based on the required driving force, braking means and a sub-control unit for controlling each of the above, wherein the main control unit includes a target reference wheel speed calculation unit that calculates a reference target rotation speed of the wheel, and a target slip ratio calculation unit that calculates a target slip ratio of the wheel that is set for the target reference wheel speed, and calculates the required driving force based on the target slip ratio, and the sub-control unit includes an actual slip ratio calculation unit that calculates an actual slip ratio of the wheel, and a slip ratio control unit that corrects the required driving force so that the actual slip ratio becomes the target slip ratio, and controls the driving means or the braking means.

[0007] As a result, the target slip ratio for the wheels is calculated in the main control unit, while the sub-control units, which are provided downstream of the main control unit for each drive means and brake means and have smaller delays due to communication etc. than the main control unit, control the drive means or brake means to control the actual slip ratio to the target slip ratio, so that the actual slip ratio for each wheel can be controlled to the target slip ratio with good responsiveness.

[0008] Preferably, the target reference wheel speed calculation unit calculates the target reference wheel speed for each of the wheels, and the target slip ratio calculation unit calculates the target slip ratio for each of the wheels. This allows the target reference wheel speed and target slip ratio to be calculated for each wheel, making it possible to control the wheel speed and target slip ratio with high precision for each wheel, thereby enabling precise control of the traction of each wheel and accurate control of the vehicle behavior.

[0009] Preferably, the target reference wheel speed calculation unit calculates the target reference wheel speed to a value common to the front, rear, left and right wheels, and the target slip ratio calculation unit calculates the target slip ratio for each of the wheels. This allows the target reference wheel speed to be calculated to a common value for all four wheels, thereby reducing the calculation load of the target reference wheel speed on the main control unit. Also, since the target slip ratio is calculated for each wheel, it becomes possible to control the target slip ratio for each wheel, and thus to control the traction of each wheel.

[0010] Preferably, the target reference wheel speed calculation unit calculates the target reference wheel speed for each wheel, and the target slip ratio calculation unit calculates the target slip ratio to a value common to the front, rear, left and right wheels. This allows the target slip ratio to be calculated to a common value for all front, rear, left, and right wheels, thereby reducing the calculation load for the target slip ratio on the main control unit. Also, since the target reference wheel speed is calculated for each wheel, it becomes possible to control the target reference wheel speed for each wheel, and thus to control the traction of each wheel.

[0011] Preferably, the vehicle steering system includes a target yaw rate calculation unit that calculates a target yaw rate of the vehicle based on at least the steering angle of the vehicle, and a yaw rate detection unit that detects an actual yaw rate of the vehicle, and the target slip ratio calculation unit changes the target slip ratio for each wheel based on the target yaw rate or the difference between the target yaw rate and the actual yaw rate.

[0012] This allows the target slip ratio to change depending on the target yaw rate or the difference between the target yaw rate and the actual yaw rate, i.e., depending on the vehicle's turning posture, making it possible to control the vehicle's turning promotion and turning suppression depending on the steering angle. Preferably, the vehicle includes a driving force estimation unit that estimates a total driving force of the vehicle, and the target slip ratio calculation unit changes the target slip ratio for each wheel based on the required driving force or the difference between the required driving force and the total driving force.

[0013] As a result, the target slip ratio changes depending on the vehicle's required driving force or the difference between the required driving force and the total driving force, i.e., depending on the road surface conditions, so it becomes possible to control the vehicle's total driving force corresponding to the accelerator opening so that the required driving force is ensured. Preferably, the driving means and the braking means are composed of a first electric motor that drives the front wheels of the vehicle, a second electric motor that drives the rear wheels of the vehicle, and brake devices that are provided for each of the front, rear, left and right wheels of the vehicle and are capable of applying different braking forces to each wheel.

[0014] This allows a vehicle equipped with two electric motors for driving and a brake device capable of braking each wheel independently to quickly control the actual slip ratio to the target slip ratio for each wheel, thereby improving the vehicle's driving performance. [Effects of the Invention]

[0015] The vehicle driving control device of the present invention can quickly control the actual slip ratio to the target slip ratio for each wheel, thereby enabling responsive traction control and improving the vehicle's driving performance. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of a plug-in hybrid vehicle equipped with a traction control device according to an embodiment of the present invention; [Figure 2]1 is a block diagram showing a schematic configuration of a traction control device according to an embodiment of the present invention; [Figure 3] FIG. 4 is a data flow diagram showing a procedure for calculating a target slip ratio. DETAILED DESCRIPTION OF THE INVENTION

[0017] FIG. 1 is a schematic diagram of a plug-in hybrid vehicle (hereinafter referred to as vehicle 1) equipped with a drive control device according to a first embodiment of the present invention. The vehicle 1 of the first embodiment employing the driving control device of the present invention is a four-wheel drive vehicle that can run by driving the front wheels 3a, 3b (wheels) using the output of the engine 2, and is equipped with an electric front motor 4 (first electric motor, drive means) that drives the front wheels 3a, 3b, and an electric rear motor 6 (second electric motor, drive means) that drives the rear wheels 3c, 3d (wheels).

[0018] The engine 2 is capable of driving a drive shaft 8 of the front wheels 3 via a front transaxle 7, and is also capable of driving a motor generator 9 via the front transaxle 7 to generate electricity. The engine 2 and the front wheels 3a, 3b are connected via a clutch 16 disposed within the front transaxle 7. The front motor 4 is powered by high-voltage power supplied from a drive battery 11 and a motor generator 9 mounted on the vehicle 1 via a front control unit 10 (sub-control unit), and drives the drive shaft 8 of the front wheels 3a, 3b via a front transaxle 7.

[0019] The rear motor 6 is driven by high-voltage power supplied from a drive battery 11 via a rear control unit 12 (sub-control unit), and drives a drive shaft 14 of the rear wheels 3c, 3d via a rear transaxle 13. The electric power generated by the motor generator 9 can charge the drive battery 11 via the front control unit 10, and can also supply electric power to the front motor 4 and the rear motor 6.

[0020] The driving battery 11 is composed of a secondary battery such as a lithium ion battery, and has a battery module (not shown) that is made up of multiple battery cells. The driving battery 11 also has a charging rate detector 11a that detects the charging rate SOC of the driving battery 11. The front control unit 10 has the function of controlling the driving torque and regenerative braking torque of the front motor 4 based on control signals from a hybrid control unit 20 (main control unit) mounted on the vehicle 1, as well as controlling the power generation amount and output of the motor generator 9.

[0021] The rear control unit 12 has a function of controlling the driving torque and regenerative braking torque of the rear motor 6 based on a control signal from the hybrid control unit 20 . The engine control unit 22 is a control device for the engine 2, and is configured to include an input / output device, a memory device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), a timer, etc. Based on a control signal (required output) from the hybrid control unit 20, the engine control unit 22 controls the fuel injection amount, fuel injection timing, intake amount, etc. of the engine 2, thereby controlling the drive of the engine 2.

[0022] The vehicle 1 is also provided with a fuel tank (not shown) that stores fuel to be supplied to the engine 2, and a charger 18 that charges the drive battery 11 from an external power source. The hybrid control unit 20 is a control device for performing overall control of the vehicle 1, and includes an input / output device, a memory device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), a timer, and the like.

[0023] The input side of the hybrid control unit 20 is connected to the front control unit 10, rear control unit 12, and engine control unit 22, and receives detection and operation information from these devices. On the other hand, the output side of the hybrid control unit 20 is connected to the front control unit 10, the rear control unit 12, the engine control unit 22, and the clutch 16 of the front transaxle 7.

[0024] The hybrid control unit 20 then calculates the vehicle required output power required to drive the vehicle 1 based on various detected quantities such as the accelerator operation information level of the vehicle 1 and various operational information, and sends control signals to the engine control unit 22, the front control unit 10, and the rear control unit 12 to control switching of driving modes (EV mode, series mode, parallel mode), the output of the engine 2, the front motor 4, and the rear motor 6, the generated power and output of the motor generator 9, and the engagement and disengagement of the clutch 16 in the front transaxle 7.

[0025] In the EV mode, the engine 2 is stopped, and the front motor 4 and rear motor 6 are driven by electric power supplied from the drive battery 11 to drive the vehicle. In series mode, the clutch 16 of the front transaxle 7 is disengaged and the motor generator 9 is operated by the engine 2. The front motor 4 and rear motor 6 are then driven by electric power generated by the motor generator 9 and electric power supplied from the drive battery 11 to drive the vehicle. Also, in series mode, the rotational speed of the engine 2 is set to an efficient value, and electric power generated by surplus output is supplied to the drive battery 11 to charge it.

[0026] In parallel mode, the clutch 16 of the front transaxle 7 is engaged, and power is mechanically transmitted from the engine 2 via the front transaxle 7 to drive the front wheels 3a, 3b. The front motor 4 and rear motor 6 are driven by electric power generated by operating the motor generator 9 using the engine 2 and electric power supplied from the drive battery 11, causing the vehicle to travel.

[0027] The hybrid control unit 20 sets the driving mode to parallel mode in a range where the engine 2 is efficient, such as a high-speed range. In a range other than parallel mode, i.e., a medium-to-low speed range, the hybrid control unit 20 switches between EV mode and series mode based on the state of charge (SOC) of the drive battery 11. Each of the wheels 3a to 3d of the vehicle 1 is provided with a braking device 30a, 30b, 30c, 30d (braking means) that applies a braking torque. The front wheel braking devices 30a and 30b are controlled by a front brake control unit 31 (sub-control unit), and the rear wheel braking devices 30c and 30d are controlled by a rear brake control unit 32 (sub-control unit), so that the braking torque can be controlled independently for each of the wheels 3a to 3d. The front brake control unit 31 and the rear brake control unit 32 are connected to the hybrid control unit 20 so as to be able to communicate with each other. The front brake control unit 31 may be connected to the hybrid control unit 20 via the front control unit 10, and the rear brake control unit 32 may be connected to the hybrid control unit 20 via the rear control unit 12 so as to be able to communicate with each other. The front brake control unit 31 and the rear brake control unit 32 control the operation of each of the braking devices 30a to 30d based on a brake pedal operation signal or the like from a brake pedal sensor (not shown).

[0028] The front control unit 10, rear control unit 12, front brake control unit 31, and rear brake control unit 32 are each configured to include an input / output device, a memory device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), a timer, etc. These control units 10, 12, 31, and 32 have a faster processing speed than the hybrid control unit 20.

[0029] FIG. 2 is a block diagram showing a schematic configuration of a traction control device 50 (travel control device) according to one embodiment of the present invention. The traction control device 50 of one embodiment of the present invention is made up of a hybrid control unit 20, motor control units (front control unit 10, rear control unit 12), and brake control units (front brake control unit 31, rear brake control unit 32). Although Fig. 2 shows one each of the motor control units 10, 12 and brake control units 31, 32, the vehicle 1 of this embodiment is provided with two sets, one for the front wheels and one for the rear wheels.

[0030] The hybrid control unit 20 includes a driver torque calculation unit 51, a reference wheel speed calculation unit 52 (target reference wheel speed calculation unit), a four-wheel torque distribution unit 53, a target slip ratio calculation and distribution unit 54 (target slip ratio calculation unit), and a torque redistribution unit 55. The driver torque calculation unit 51 receives the accelerator opening, brake depression amount, and steering angle of the vehicle 1 and calculates the driving torque of the entire vehicle required by the driver.

[0031] The reference wheel speed calculation unit 52 receives detection values ​​relating to the turning attitude of the vehicle, such as the yaw rate, wheel speed, and steering angle, and calculates the reference speed (target reference wheel speed) for each of the four wheels. The yaw rate is detected by a yaw rate sensor 74 (yaw rate detection unit) provided on the vehicle 1. The four-wheel torque distribution unit 53 distributes the driving torque of the entire vehicle calculated by the driver torque calculation unit 51 to each wheel, and calculates the driving torque for each of the wheels 3a to 3d. The distribution of the driving torque for each of the wheels 3a to 3d is performed based on vehicle driving operation information such as the accelerator opening, brake depression amount, and steering angle of the vehicle 1, as well as vehicle speed information.

[0032] The target slip ratio calculation and distribution unit 54 calculates the target slip ratio based on the actual wheel speed and the reference wheel speed of each wheel 3a to 3d calculated by the reference wheel speed calculation unit 52. The actual wheel speed may be detected by a rotation speed sensor provided on each wheel 3a, the drive shafts 8, 14, etc. Torque reallocation unit 55 corrects and reallocates the drive torque for each of wheels 3a to 3d calculated by four-wheel torque allocation unit 53 based on the target slip ratio and actual wheel speed for each of wheels 3a to 3d calculated by target slip ratio calculation and allocation unit 54. At this time, the torque required by the driver is not changed, and torque is allocated so that the slip ratios of the four wheels are equal.

[0033] The motor control units 10 and 12 each have a target wheel speed calculation unit 61 and a slip ratio control unit 62 (actual slip ratio calculation unit, slip ratio control unit). The target wheel speed calculation unit 61 calculates the target wheel speed of each of the wheels 3a to 3d based on the reference wheel speed calculated by the reference wheel speed calculation unit 52 and the target slip ratio calculated by the target slip ratio calculation distribution unit .

[0034] The slip ratio control unit 62 calculates an actual slip ratio from the target wheel speed calculated by the target wheel speed calculation unit 61 and the actual wheel speed, corrects and outputs the motor torque command amount so that the actual slip ratio becomes the target slip ratio calculated by the target slip ratio calculation distribution unit 54, and outputs the brake torque command amount of the brake devices 30a to 30d to the brake control units 31 and 32.

[0035] The slip ratio control section 62 feeds back to the hybrid control unit 20 the correction amount for the motor torque command amount. The calculation of the target slip ratio in the hybrid control unit 20 will be described in detail with reference to FIG. FIG. 3 is a data flow diagram showing the procedure for calculating the target slip ratio.

[0036] As shown in FIG. 3, the hybrid control unit 20 calculates the required torque from the accelerator opening, and adds the required brake torque calculated from the brake depression amount, etc., to calculate the required driving force (required driving force calculation unit 71). The required driving force is added to the estimated total driving force (described later), and the value is adjusted using a dead zone map and a low-pass filter to suppress chattering. From this value, the target reference slip ratio (rate) is calculated using a reference slip base map.

[0037] On the other hand, the accelerator opening is corrected using an accelerator correction map, and the corrected accelerator opening is multiplied by the above-mentioned reference slip ratio to calculate a target reference slip ratio. Furthermore, a target yaw rate is calculated from the detected value of the steering wheel angle (target yaw rate calculation unit 73), and a target longitudinal relative slip ratio is calculated based on the target yaw rate and the detected value of the yaw rate.

[0038] Then, a target slip ratio is calculated based on the target reference slip ratio and the target front / rear relative slip ratio (target slip ratio calculation / distribution unit 54). The calculated target slip ratio is sent to motor control units 10, 12. The motor control units 10 and 12 calculate the actual slip ratio from the actual wheel speed, and calculate the motor correction torque and brake correction torque so that this actual slip ratio becomes the target slip ratio.

[0039] Then, the hybrid control unit 20 outputs the motor final torque to the motor control units 10 and 12 based on the motor correction torque, and outputs the brake final torque to the brake control units 31 and 32 based on the brake correction torque. The front motor 4 and rear motor 6 output drive torque as the final motor torque after correcting the requested motor torque from the hybrid control unit 20 with the motor correction torque calculated by the motor control units 10 and 12. Regarding braking, the requested brake torque from the hybrid control unit 20 and the requested brake correction torque calculated by the motor control units 10 and 12 are output to the brake control units 31 and 32, respectively, and the brake control units 31 and 32 perform torque correction and output the brake torque as the final brake torque.

[0040] Furthermore, the hybrid control unit 20 calculates an estimated total driving force of the vehicle 1 (total driving force estimation unit 72 (driving force estimation unit)) based on the motor feedback torque after feedback control in the motor control units 10 and 12, and the final brake torque, actual wheel speed, and actual motor rotation speed in the brake control units 31 and 32. This estimated total driving force is used when adding it to the required driving force in the preceding stage of the dead zone map described above.

[0041] As described above, in this embodiment, traction control of each wheel 3a to 3d is performed by controlling the drive torque and braking torque of the front, rear, left and right wheels 3a to 3d through torque control of the front motor 4 and rear motor 6 for driving the vehicle and brake torque control of the brake devices 30a to 30d. In this embodiment, the hybrid control unit 20 calculates the drive torque of each of the wheels 3a to 3d, but the control of the slip ratio of each of the wheels 3a to 3d, more specifically, the feedback control of the wheel speed, is performed by the motor control units 10, 12 and the brake control units 31, 32.

[0042] As described above, the motor control units 10, 12 and the brake control units 31, 32 have higher processing performance than the hybrid control unit 20, and furthermore, have a shorter time lag (communication delay, etc.) until the final torque output. In this way, by controlling the slip ratio using units with high processing performance and little communication delay, the responsiveness of the slip ratio control, i.e., traction control, can be improved, and the driving performance of the vehicle 1 can be improved.

[0043] In this embodiment, when controlling the slip ratio, the reference wheel speed (target reference wheel speed) is set independently for each of the four wheels, and the target slip ratio is set independently for each of the four wheels. By setting at least one of the reference wheel speed and the target slip ratio independently for each of the four wheels, it is possible to improve the vehicle's turning ability while maintaining the off-road capability and driving stability of a direct-drive 4WD vehicle with a locked center differential.

[0044] In this embodiment, the hybrid control unit 20 sets both the reference wheel speed and the target slip ratio for each of the wheels 3a to 3d, so that the wheel speed and the target slip ratio can be controlled with high precision for each of the wheels 3a to 3d. This makes it possible to precisely control the traction of each of the wheels 3a to 3d and to precisely control the behavior of the vehicle 1. Note that either the reference wheel speed or the target slip ratio may be set for each of the wheels 3a to 3d. That is, the reference wheel speed may be common to the wheels 3a to 3d and the target slip ratio may be set for each of the wheels 3a to 3d, or the target slip ratio may be common to the wheels 3a to 3d and the reference wheel speed may be set for each of the wheels 3a to 3d.

[0045] For example, when the reference wheel speed is common to the wheels 3a to 3d and the target slip ratio is set for each wheel 3a to 3d, the target slip ratio is changed for each wheel 3a to 3d depending on the turning situation and road surface conditions. The turning attitude is calculated based on the difference between a target yaw rate determined by the steering angle and vehicle speed and the actual yaw rate. The target slip ratio is changed based on the turning attitude to facilitate or inhibit turning of the vehicle. For example, turning is facilitated by making the slip ratio of the rear wheels 3c, 3d greater than that of the front wheels 3a, 3b, and turning is inhibited by making the slip ratio of the front wheels 3a, 3b greater than that of the rear wheels 3c, 3d. Since the target yaw rate is calculated based on at least the steering wheel angle (steering angle), changing the target yaw rate in response to the driver's steering operation allows the target slip ratio to be set for each of the wheels 3a-3d, enabling the driver to control turning promotion or inhibition of the vehicle 1. Regarding the change in the target slip ratio based on the turning attitude, the target slip ratio may be changed based on the target yaw rate.

[0046] On the other hand, road surface conditions are calculated based on the difference between the target drive torque and the estimated drive torque. The target slip ratio is then changed based on the road surface conditions, thereby ensuring the torque required by the driver. Regarding the change in the target slip ratio based on the road surface conditions, the target slip ratio may be changed based on the target drive torque. The target drive torque is set based on at least the accelerator pedal position, so the target slip ratio changes as the accelerator pedal depression changes. This allows the slip ratios of all four wheels to be equalized by operating the accelerator.

[0047] In contrast, conventional traction control devices are known to use methods that, for example, suppress the drive torque (total torque) of the entire vehicle when a wheel slips, thereby suppressing slippage and stabilizing the vehicle's behavior, or to assist the driver in stabilizing the vehicle's behavior by optimally distributing the drive torque among the four wheels without changing the total torque of the vehicle. In this embodiment, the driver can control the amount of slip suppression by the accelerator depression amount, etc., and can assist the driver in creating a vehicle posture that meets his or her expectations.

[0048] Although the description of the embodiment has been completed, aspects of the present invention are not limited to the above embodiment. For example, the vehicle 1 in the above embodiment is a four-wheel drive vehicle using two motors, the front motor 4 and the rear motor 6, and the left and right slip ratios are equalized by controlling the front, rear, left, and right brake devices 30a-30d. Alternatively, in a vehicle in which the left rear wheel 3c and the right rear wheel 3d are driven by individual motors, and thus the vehicle has a total of three driving motors including the front motor 4, the left and right slip ratios of the front wheels 3a and 3b can be equalized by controlling the left front brake device 30a and the right front brake device 30b. In a vehicle equipped with an active yaw control device that controls two motors for driving the rear wheels 3c and 3d, specifically, if the rear control unit 12 or the hybrid control unit 20 is equipped with a yaw control control section, the active yaw control device can be used to equalize the left and right slip ratios. Furthermore, the left and right brake devices 30c and 30d may be used together on the rear wheels 3c and 3d to equalize the left and right slip ratios. When the brake devices 30c, 30d for the rear wheels 3c are electric brakes, the responsiveness of the brake control is improved, making it possible to perform traction control with good responsiveness.

[0049] In addition, in the above embodiment, a front control unit and a rear control unit are provided as the motor control unit, and a front brake control unit and a rear brake control unit are provided as the brake control unit, but each of these may be provided for each motor or brake device, or one may be provided for each vehicle.

[0050] Furthermore, although the vehicle 1 in the above embodiment is a plug-in hybrid vehicle (PHEV) equipped with an engine 2 and capable of external charging and external power supply, the present invention can also be applied to hybrid vehicles (HEVs) and electric vehicles (EVs). The present invention can also be applied to vehicles in which the driving or braking of each of the four wheels can be electrically controlled independently. [Explanation of symbols]

[0051] 1 vehicle 3a, 3b Front wheels (wheels) 3c, 3d rear wheel (wheel) 4. Front motor (first electric motor, driving means) 6 rear motor (second electric motor, drive means) 20 Hybrid control unit (main control unit) 10 Front control unit (sub-control unit) 12 Rear control unit (sub-control unit) 30a to 30d Brake device (braking means) 31 Front brake control unit (sub-control unit) 32 Rear brake control unit (sub-control unit) 50 Traction control device (driving control device) 52 Reference wheel speed calculation section (target reference wheel speed calculation section) 54 Target slip ratio calculation distribution unit (target slip ratio calculation unit) 62 Slip ratio control unit (actual slip ratio calculation unit, slip ratio control unit) 72 Total driving force estimation unit (driving force estimation unit) 73 Target yaw rate calculation unit 74 Yaw rate sensor (yaw rate detection section)

Claims

1. A vehicle travel control device comprising: drive means for driving front, rear, left, and right wheels; and braking means for independently braking the front, rear, left, and right wheels, wherein the drive means and the braking means can drive and brake the front, rear, left, and right wheels, a main control unit that calculates a required driving force of the vehicle based on a driver request and a vehicle behavior; a sub-control unit provided downstream of the main control unit for each of the driving means and the braking means, the sub-control unit controlling each of the driving means and the braking means based on the required driving force; The main control unit a target reference wheel speed calculation unit that calculates a target reference wheel speed, which is a reference target rotation speed of the wheel; a target slip ratio calculation unit that calculates a target slip ratio of the wheel that is set with respect to the target reference wheel speed, Calculating the required driving force based on the target slip ratio; The sub-control unit an actual slip ratio calculation unit that calculates an actual slip ratio of the wheel; a slip ratio control unit that corrects the required driving force to control the driving means or the braking means so that the actual slip ratio becomes the target slip ratio. A vehicle driving control device characterized by:

2. the target reference wheel speed calculation unit calculates the target reference wheel speed for each of the wheels, The target slip ratio calculation unit calculates the target slip ratio for each of the wheels.

2. The vehicle driving control device according to claim 1.

3. the target reference wheel speed calculation unit calculates the target reference wheel speed to a value common to the front, rear, left, and right wheels, The target slip ratio calculation unit calculates the target slip ratio for each of the wheels.

2. The vehicle driving control device according to claim 1.

4. the target reference wheel speed calculation unit calculates the target reference wheel speed for each of the wheels, The target slip ratio calculation unit calculates the target slip ratio to a value common to the front, rear, left, and right wheels.

2. The vehicle driving control device according to claim 1.

5. a target yaw rate calculation unit that calculates a target yaw rate of the vehicle based on at least a steering angle of the vehicle; a yaw rate detection unit that detects an actual yaw rate of the vehicle, The target slip ratio calculation unit changes the target slip ratio for each wheel based on the target yaw rate or a difference between the target yaw rate and the actual yaw rate.

4. The vehicle driving control device according to claim 2 or 3.

6. a driving force estimating unit that estimates a total driving force of the vehicle; The target slip ratio calculation unit changes the target slip ratio for each wheel based on the required driving force or a difference between the required driving force and the total driving force.

4. The vehicle driving control device according to claim 2 or 3.

7. The driving means and the braking means are a first electric motor that drives the front wheels of the vehicle; a second electric motor that drives the rear wheels of the vehicle; Brake devices are provided for the front, rear, left, and right wheels of the vehicle, and are capable of applying different braking forces to each wheel; 2. The vehicle driving control device according to claim 1, wherein the vehicle driving control device is configured by:

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