JP2022110971A - Vehicle control device and control method - Google Patents

Abstract

To provide a vehicle control device and a control method which prevent a vehicle from skidding when the same turns.SOLUTION: A vehicle control device 10 controls a vehicle C where a plurality of drive wheels 1 is rotated with motors 2 individually installed for respective drive wheels. The vehicle control device comprises a motor control section which controls torque generated through the motors. When the vehicle is in a front loading state where a load on a front wheel 1F is larger than the load on other drive wheels and in a turning state, the motor control section executes first control which sets torque of the motor rotating the front wheel to be larger than the torque of the other motors.SELECTED DRAWING: Figure 1B

Description

The present invention relates to a vehicle control device and control method.

2. Description of the Related Art Conventionally, there is known a vehicle control device that controls the torque of a motor that rotates left and right wheels according to the load on the left and right wheels when turning (for example, see Patent Document 1).

JP-A-05-328542

However, with the vehicle control device described above, for example, when the brake pedal is depressed and the load on the front wheels increases, the vehicle may skid.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle control device and a control method for preventing sideslip from occurring during cornering.

A vehicle control device according to an aspect of an embodiment controls a vehicle in which a plurality of drive wheels are rotated by different motors. The vehicle control device includes a motor control section that controls torque generated by the motor. When the vehicle is in a preloaded state in which the load on the front wheels is greater than the load on the other drive wheels and the vehicle is turning, the motor control unit increases the torque of the motor that rotates the front wheels. Perform the first control to set to .

According to one aspect of the embodiment, it is possible to prevent sideslip from occurring during cornering.

FIG. 1A is a schematic diagram showing a vehicle in a turning state. FIG. 1B is a schematic diagram illustrating the vehicle in a state in which the driving force of the front wheels is increased compared to the turning state of FIG. 1A. FIG. 2 is a schematic diagram illustrating part of the vehicle according to the embodiment. FIG. 3 is a block diagram showing the configuration of the control device according to the embodiment. FIG. 4 is a map for calculating the vehicle required torque. FIG. 5A is a flowchart for explaining sideslip prevention control according to the embodiment. FIG. 5B is a flowchart for explaining sideslip prevention control according to the embodiment.

Hereinafter, a vehicle control device and a control method according to embodiments will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment.

A control method according to the embodiment will be described. The control method according to the embodiment is executed by the control device 10 (vehicle control device). The control device 10 is mounted on the vehicle C. As shown in FIG. A vehicle C has a plurality of drive wheels 1 . For example, vehicle C has four drive wheels 1 . The vehicle C rotates each driving wheel 1 by a motor 2 different from each other. The motor 2 is a so-called in-wheel motor.

Hereinafter, the front driving wheel 1 of the vehicle C may be referred to as the "front wheel 1F", and the rear driving wheel 1 of the vehicle C may be referred to as the "rear wheel 1R".

The front wheels 1F of the vehicle C are steered wheels, and when the vehicle C is requested to turn, for example, when the steering wheel 5 (see FIG. 2) is operated by the driver, the front wheels 1F are steered in the turning direction. be steered.

At that time, as shown in FIG. 1A, at the front wheels 1F in the turning state, the sum of the cornering force CF at the front wheels 1F and the front wheel traveling direction vertical component F2 of the driving force F1 at the front wheels 1F, and the centrifugal force F3 at the front wheels 1F. be in a balanced state. The cornering force CF is a force perpendicular to the traveling direction T1 of the front wheel 1F and acting in the direction of the center of the turning circle, among the forces generated by the elastic deformation of the front wheel 1F at the ground contact portion of the front wheel 1F (drive wheel 1). be. FIG. 1A is a schematic diagram showing a vehicle C in a turning state. In addition, in FIG. 1A, the cornering force CF is shown shifted for the sake of explanation.

The cornering force CF at the front wheel 1F is calculated by Equation (1) based on the cornering coefficient Cc, the weight m applied to the front wheel 1F, and the slip angle SA. The cornering coefficient Cc is a predetermined constant. The slip angle SA is the angle between the direction in which the driving force F1 acts on the front wheels 1F and the traveling direction T1 of the front wheels 1F.

CF=Cc×m×SA (1)

The cornering force CF increases as the slip angle SA increases. Note that the cornering force CF has a maximum cornering force CFmax and never exceeds the maximum cornering force CFmax. The maximum cornering force CFmax at the front wheel 1F is calculated by Equation (2) based on the coefficient of friction μ, the weight m applied to the front wheel 1F, and the gravitational acceleration g.

CFmax=μ×m×g (2)

In the front wheel 1F, for example, when the centrifugal force F3 increases, the traveling direction T1 of the front wheel 1F shown in FIG. 1A moves counterclockwise. Therefore, the slip angle SA increases and the cornering force CF also increases. When the cornering force CF reaches the maximum cornering force CFmax, the cornering force CF never becomes larger than the maximum cornering force CFmax. Therefore, when the centrifugal force F3 at the front wheels 1F becomes larger than the sum of the maximum cornering force CFmax and the vertical component F2 of the driving force F1 in the direction of travel of the front wheels, the front wheels 1F of the vehicle C skid and understeer. .

For example, if the vehicle C turns after the brake pedal is depressed by the driver, the vehicle C is preloaded. A front load state is a state in which the load on the front wheels 1F is greater than the load on the other driving wheels 1, for example, the rear wheels 1R. When the front load increases the load on the front wheels 1F, the centrifugal force F3 applied to the front wheels 1F increases. When the vehicle C turns, first, the front wheels 1F, which are steered wheels, are steered according to the operation of the steering wheel 5, for example. Therefore, in the turning start state immediately after turning is started, only the front wheels 1F are transitioning to turning motion. When the rear wheels 1R are not in a turning state and only the front wheels 1F are in a turning state, the centrifugal force F3 is applied only to the front wheels 1F.

When the vehicle C turns in a preload state, particularly when the vehicle C is in a preload state due to a brake operation or the like and is in a turning start state, the centrifugal force F3 at the front wheels 1F becomes relatively large. As a result, the front wheels 1F are likely to skid, resulting in understeer. Note that the centrifugal force F3 on the front wheels 1F increases in either the front load state or the turning start state.

When the vehicle C is in the preload state, the control device 10 increases the driving force F1 at the front wheels 1F as indicated by the solid line arrow in FIG. 1B. FIG. 1B is a schematic diagram illustrating the vehicle C in a state in which the driving force F1 of the front wheels 1F is increased compared to the turning state of FIG. 1A. In FIG. 1B, the increased driving force F1 and the front wheel traveling direction vertical component F2 of the increased driving force F1 are indicated by solid lines. In FIG. 1B, the driving force F1 at the front wheels 1F in FIG. 1A and the front wheel traveling direction vertical component F2 are indicated by dashed lines for explanation. Also, in FIG. 1B, for the sake of explanation, the cornering force CF, the driving force F1 in FIG. 1A, and the front wheel traveling direction vertical component F2 are shown shifted.

For example, the control device 10 increases the driving force F1 in the front wheels 1F by increasing the driving torque in the motor 2 that rotates the front wheels 1F (increases the driving torque distributed to the front wheels 1F). The driving torque is torque that causes the drive wheels 1 to generate driving force. The driving torque is positive torque. In addition, below, the torque which produces a braking force in the drive wheel 1 may be called a braking torque and demonstrated. Braking torque is negative torque. The control device 10 sets the driving torque of the motor 2 that rotates the front wheels 1F so that it increases as the load on the front wheels 1F is greater than that on the rear wheels 1R.

By increasing the driving torque of the motor 2 that rotates the front wheels 1F, the control device 10 can increase the front wheel traveling direction vertical component F2 of the driving force F1, thereby suppressing the increase of the cornering force CF (slip angle SA). can do. Therefore, the control device 10 can secure a margin until the cornering force CF reaches the maximum cornering force CFmax. Therefore, the control device 10 can prevent the vehicle C from skidding. For example, the control device 10 can prevent the vehicle C from understeering.

Next, a vehicle C according to the embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating part of the vehicle C according to the embodiment.

A vehicle C includes four driving wheels 1 , four motors 2 , a battery 3 and a control device 10 .

The four drive wheels 1 include a left front wheel 1FL, a right front wheel 1FR, a left rear wheel 1RL, and a right rear wheel 1RR. The four motors 2 include a left front wheel motor 2FL, a right front wheel motor 2FR, a left rear wheel motor 2RL, and a right rear wheel motor 2RR.

The left front wheel motor 2FL rotates the left front wheel 1FL. The right front wheel motor 2FR rotates the right front wheel 1FR. The left rear wheel motor 2RL rotates the left rear wheel 1RL. The right rear wheel motor 2RR rotates the right rear wheel 1RR.

Electric power is supplied to each motor 2 from a battery 3 . Torque in each motor 2 is controlled based on a control signal input from the control device 10 . Specifically, each motor 2 generates drive torque or braking torque based on the control signal. Torque generated by each motor 2 is transmitted to each drive wheel 1 .

The control device 10 is a controller that controls each motor 2 individually. The control device 10 controls each motor 2 by outputting a control signal to each motor 2 according to, for example, the amount of operation of an accelerator pedal, the amount of operation of a brake pedal, and the like.

For example, when the accelerator pedal is operated and the vehicle C is requested to accelerate, the control device 10 controls each motor 2 so that driving torque for accelerating the vehicle C is output from each motor 2 to each driving wheel 1. Control the motor 2. As a result, the vehicle C accelerates.

Further, for example, when the brake pedal is operated and a deceleration request is issued to the vehicle C, the control device 10 causes the motors 2 to output the braking torque for decelerating the vehicle C to the drive wheels 1. , controls each motor 2 . As a result, the vehicle C decelerates. Note that the vehicle C may use a mechanical brake to decelerate when deceleration is requested.

Further, for example, when the steering wheel 5 is operated and the vehicle C is requested to turn, the control device 10 steers the front left wheel 1FL and the front right wheel 1FR as described above.

Next, the configuration of the control device 10 according to the embodiment will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the control device 10 according to the embodiment. In FIG. 3, functional blocks are used to represent only the components necessary for describing the features of the present embodiment, and descriptions of general components are omitted.

In other words, each component illustrated in FIG. 3 is functionally conceptual and does not necessarily need to be physically configured as illustrated. For example, the specific forms of distribution and integration of each functional block are not limited to those shown in the figure, and all or part of them can be functionally or physically distributed in arbitrary units according to various loads and usage conditions.・It is possible to integrate and configure.

The control device 10 includes a control section 11 (motor control section) and a storage section 12 . The storage unit 12 is configured by a storage device such as a nonvolatile memory, data flash, or hard disk drive, for example. The storage unit 12 stores map information, various programs, and the like.

The control unit 11 includes a detection unit 13 , a calculation unit 14 , a determination unit 15 and a setting unit 16 . The control unit 11 includes, for example, a computer having a CPU, a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk drive, an input/output port, and various circuits.

The CPU of the computer functions as the detection unit 13, the calculation unit 14, the determination unit 15, and the setting unit 16 of the control unit 11 by reading and executing programs stored in the ROM, for example.

At least some or all of the detection unit 13, the calculation unit 14, the determination unit 15, and the setting unit 16 of the control unit 11 may be implemented by hardware such as ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). can also be configured with

Signals from various sensors provided in the vehicle C are input to the detection unit 13 . Various sensors include a steering angle sensor 30, a yaw rate sensor 31, a vehicle speed sensor 32, an accelerator opening sensor 33, a brake sensor 34, a G sensor 35, a steering sensor 36, a temperature sensor 37, and the like.

The detection unit 13 detects the steering angle θ of the steered wheels based on the signal input from the steering angle sensor 30 . The steering angle sensor 30 is provided for each of the front left wheel 1FL and the front right wheel 1FR. That is, the detection unit 13 detects the steering angle θ of the left front wheel 1FL and the steering angle θ of the right front wheel 1FR. In the following description, the steering angle of the front wheel 1F, which is on the inside when turning, may be referred to as "θ1", and the steering angle of the front wheel 1F, which is on the outside when turning, may be referred to as "θ2".

The detection unit 13 detects the current yaw rate Yawreal (hereinafter referred to as “actual yaw rate Yawreal”) of the vehicle C based on the signal input from the yaw rate sensor 31 .

The detector 13 detects the vehicle speed Spd based on the signal input from the vehicle speed sensor 32 . The detector 13 detects an accelerator opening Accel, which is the depression amount of the accelerator pedal, based on a signal input from the accelerator opening sensor 33 .

The detection unit 13 detects the depression amount of the brake pedal based on the signal input from the brake sensor 34 . The detector 13 detects the acceleration ax of the vehicle C in the X direction based on the signal input from the G sensor 35 . The X direction of the vehicle C is the longitudinal direction of the vehicle C. As shown in FIG. As for the acceleration ax in the X direction, the acceleration in the forward direction of the vehicle C has a positive value.

The detection unit 13 detects the steering operation amount Strangl based on the signal input from the steering sensor 36 . The steering operation amount Strangl is an operation amount based on the position of the steering wheel 5 when the vehicle C is traveling straight ahead.

The detector 13 detects the temperature of the motor 2 based on the signal input from the temperature sensor 37 . A temperature sensor 37 is provided for each motor 2 , and the detection unit 13 detects the temperature of each motor 2 .

The calculator 14 calculates the estimated turning radius Rad. The calculation unit 14 calculates an estimated turning radius Rad using Equation (3) based on the wheel base L, the steering angle θ1 of the front wheels 1F that are on the inside when turning, and the steering angle θ2 of the front wheels 1F that are on the outside when turning. do.

Rad=(L/sin θ1+L/tan θ2)/2 (3)

The calculator 14 calculates the upper limit vehicle speed Spdlmt. Specifically, the calculation unit 14 calculates the upper limit vehicle speed Spdlmt using Equation (4) based on the estimated turning radius Rad and the upper limit centrifugal acceleration CNTYDNG. Upper limit centrifugal acceleration CNTYDNG is a value set in advance, and is a value capable of suppressing occurrence of sideslip in vehicle C. FIG. When the centrifugal force F3 increases and the cornering force CF increases, the vehicle C may skid. Centrifugal force F3 is proportional to and related to centrifugal acceleration. Therefore, the calculator 14 calculates the upper limit vehicle speed Spdlmt corresponding to the upper limit centrifugal acceleration CNTYDNG.

Spdlmt=(Rad×CNTYDNG) ^1/2 (4)

The calculation unit 14 calculates the vehicle required torque Cartrq. Specifically, when the detected vehicle speed Spd is equal to or higher than the upper limit vehicle speed Spdlmt, the calculation unit 14 calculates the vehicle required torque Cartrq by feedback control based on the deviation between the vehicle speed Spd and the upper limit vehicle speed Spdlmt. The calculation unit 14 sets the target vehicle speed such that the vehicle speed Spd is equal to or lower than the upper limit vehicle speed Spdlmt, and calculates the vehicle required torque Cartrq that becomes the target vehicle speed. In this case, the vehicle required torque Cartrq is a negative torque that limits the vehicle speed Spd to the upper limit vehicle speed Spdlmt or less. That is, the vehicle required torque Cartrq is braking torque. The vehicle required torque Cartrq is braking torque for making the vehicle speed Spd equal to or lower than the upper limit vehicle speed Spdlmt.

When the detected vehicle speed Spd is lower than upper limit vehicle speed Spdlmt, calculation unit 14 calculates vehicle request torque Cartrq from the map shown in FIG. 4 based on vehicle speed Spd and accelerator opening Accel. FIG. 4 is a map for calculating the vehicle required torque Cartrq. The calculation unit 14 may calculate the vehicle required torque Cartrq from a calculation formula or the like without using the map.

The calculator 14 calculates the front wheel load ratio Frwigtrt. Specifically, the calculator 14 calculates the distance lr from the center of gravity of the vehicle C to the rear wheels 1R, the wheel base L, the height h from the ground to the center of gravity of the vehicle C, the acceleration ax of the vehicle C in the X direction, and the gravity. Based on the acceleration g, the front wheel load ratio Frwigtrt is calculated using equation (5).

Frwigtrt=(lr/L)+h×ax/(L×g) (5)

The calculator 14 calculates the target yaw rate Yawtag. The calculator 14 calculates a target yaw rate Yawtag based on the vehicle speed Spd and the estimated turning radius Rad. The calculation unit 14 calculates the target yaw rate Yawtag using Equation (6).

Yawtag=Spd ² /Rad (6)

The calculator 14 calculates the yaw rate deviation Delyaw. The calculator 14 calculates the deviation between the target yaw rate Yawtag and the actual yaw rate Yawreal as the yaw rate deviation Delyaw.

The calculation unit 14 calculates the front wheel required driving torque Frtrqrq. Specifically, the calculating unit 14 calculates the front wheel required driving torque Frtrqrq using the equation (7) based on the front wheel required driving base torque BASETRQ, the front wheel load ratio Frwigtrt, and the yaw rate deviation Delyaw. The front wheel required driving base torque BASETRQ is a preset value.

Frtrqrq=BASETRQ×Frwigtrt×Delyaw (7)

When the vehicle C starts turning, the yaw rate deviation Delyaw, which is the deviation between the target yaw rate Yawtag and the actual yaw rate Yawreal, increases. Therefore, when the vehicle C starts turning, the required front wheel drive torque Frtrqrq increases. Further, the front wheel required drive torque Frtrqrq increases as the front wheel load ratio Frwigtrt increases. That is, the front wheel required driving torque Frtrqrq increases as the load on the front wheels 1F is greater than that on the rear wheels 1R.

The calculator 14 calculates the lower limit torque Rrtrqmn in the motor 2 that rotates the rear wheel 1R. The calculator 14 calculates the lower limit torque Rrtrqmn based on, for example, the temperature of the motor 2 that rotates the rear wheel 1R. The calculator 14 calculates the lower limit torque Rrtrqmn when the temperature of the motor 2 that rotates the rear wheel 1R is higher than a preset upper limit temperature. The lower limit torque Rrtrqmn may be calculated according to the temperature of the motor 2 that rotates the rear wheel 1R. For example, the lower limit torque Rrtrqmn increases as the temperature of the motor 2 that rotates the rear wheel 1R increases. The calculation unit 14 doubles the larger torque of the lower limit torque Mtrltrqmn of the left rear wheel motor 2RL that rotates the left rear wheel 1RL and the lower limit torque Mtrrtrqmn of the right rear wheel motor 2RR that rotates the right rear wheel 1RR. Torque is calculated as the lower limit torque Rrtrqmn. Note that the lower limit torque Rrtrqmn is a negative value. Therefore, as the temperature of the motor 2 that rotates the rear wheel 1R increases, the absolute value of the lower limit torque Rrtrqmn decreases.

The determination unit 15 determines whether or not the vehicle speed Spd is equal to or higher than the upper limit vehicle speed Spdlmt.

The determination unit 15 determines whether or not the vehicle C is in a front load turning state. Specifically, the determination unit 15 determines whether or not the vehicle C is in a preloaded state and in a turning state. The determination unit 15 determines that the vehicle C is in the preload turning state when the vehicle C is in the preload state and in the turning state.

The determination unit 15 determines that the vehicle C is in the front load state when the front wheel load ratio Frwigtrt is greater than or equal to the load determination value FRWRTOV. The load determination value FRWRTOV is a preset value.

The determination unit 15 determines that the vehicle C is in a turning state when the steering operation amount Strangl is equal to or greater than the steering operation determination value STRQNGLTH. The steering operation determination value STRQNGLTH is a preset value. The steering operation determination value STRQNGLTH is set according to left turning and right turning.

The determination unit 15 determines whether or not a predetermined torque condition is satisfied. Specifically, the determining unit 15 determines that the predetermined torque condition is satisfied when the vehicle required torque Cartrq is a positive value and the vehicle required torque Cartrq is smaller than the front wheel required driving torque Frtrqrq. The determination unit 15 determines that the predetermined torque condition is not satisfied when the vehicle required torque Cartrq is equal to or less than zero. If the vehicle required torque Cartrq is greater than or equal to the front wheel required driving torque Frtrqrq, the determination unit 15 determines that the predetermined torque condition is not satisfied.

The determination unit 15 determines whether or not a provisional torque TemtrqR of the rear wheel 1R, which will be described later, is smaller than a lower limit torque Rrtrqmn.

The setting unit 16 sets the provisional torque Temtrq. The setting unit 16 sets the provisional torque Temtrq when the vehicle C is in the preload turning state and does not satisfy the predetermined torque condition. Specifically, the setting unit 16 sets the front wheel required drive torque Frtrqrq as the provisional torque TemtrqF for the front wheels 1F. The setting unit 16 sets a torque obtained by subtracting the front wheel required drive torque Frtrqrq from the vehicle required torque Cartrq as the provisional torque TemtrqR for the rear wheels 1R.

The setting unit 16 sets the torque generated by each motor 2 .

When the state of the vehicle C is not the preload turning state, the setting unit 16 sets the torque generated by each motor 2 to the normal torque. For example, the state of the vehicle C that is not in the front load turning state includes the case where the vehicle C is not in the turning state, that is, the case where the vehicle C is traveling straight ahead. The state of the vehicle C that is not in the preload turning state includes the case where the vehicle C is not in the preload state and turns. The normal torque is a torque that is evenly generated by each wheel with respect to the vehicle required torque Cartrq. For example, the setting unit 16 sets the torque obtained by dividing the vehicle request torque Cartrq into four equal parts as the normal torque of each motor 2 .

When the vehicle C is in the preload turning state and the predetermined torque condition is satisfied, the setting unit 16 sets the torque generated by each motor 2 to the first preload turning torque. The first front load turning torque is a torque that causes the vehicle required torque Cartrq to be generated only by the motor 2 that rotates the front wheels 1F. That is, with the first front load turning torque, the torque in the motor 2 that rotates the rear wheel 1R becomes zero.

The setting unit 16 sets the torque obtained by dividing the vehicle request torque Cartrq into two equal parts as the first front load turning torque in the left front wheel motor 2FL and the first front load turning torque in the right front wheel motor 2FR. The setting unit 16 also sets the first front load turning torque in the left rear wheel motor 2RL and the first front load turning torque in the right rear wheel motor 2RR to zero.

When the vehicle required torque Cartrq is a positive value and is smaller than the front wheel required driving torque Frtrqrq, and the driving torque generated by the entire vehicle C becomes the front wheel required driving torque Frtrqrq, the vehicle C suddenly There is a risk of acceleration. Therefore, when the vehicle C is in the preload turning state and the predetermined torque condition is satisfied, the setting unit 16 sets the torque generated by each motor 2 to the first preload turning torque. As a result, it is possible to prevent the output of a torque greater than the torque required by the driver as the driving torque of the vehicle C, thereby avoiding giving the driver a feeling of being out of control.

If the state of the vehicle C is a front load turning state, the predetermined torque condition is not satisfied, and the provisional torque TemtrqR of the motor 2 that rotates the rear wheels 1R is equal to or higher than the lower limit torque Rrtrqmn, the setting unit 16 sets each motor 2 is set as the second preload turning torque. As a result, the first control is performed to increase the torque in the motor 2 that rotates the front wheel 1F.

Specifically, the setting unit 16 sets the provisional torque Temtrq as the second preload turning torque. The setting unit 16 divides the provisional torque TemtrqF of the front wheels 1F, specifically, the torque obtained by dividing the front wheel required driving torque Frtrqrq into two equal parts, as the second front load turning torque in the left front wheel motor 2FL and the second front load turning torque in the right front wheel motor 2FR. 2 Set as preload turning torque. The setting unit 16 sets the torque obtained by dividing the provisional torque TemtrqR of the rear wheel 1R into two equal parts as the second front load turning torque in the left rear wheel motor 2RL and the second front load turning torque in the right rear wheel motor 2RR. do.

As described above, at the start of turning, the yaw rate deviation Delyaw increases, so the required front wheel drive torque Frtrqrq increases. Therefore, at the start of turning, the second front load turning torque in the left front wheel motor 2FL and the second front load turning torque in the right front wheel motor 2FR increase. Further, by setting the second preload turning torque, the difference between the actual yaw rate Yawreal and the target yaw rate Yawtag is eliminated, and when the yaw rate deviation Delyaw becomes smaller, the front wheel required drive torque Frtrqrq becomes smaller. When the yaw rate deviation Delyaw becomes smaller, the second front load turning torque in the left front wheel motor 2FL and the second front load turning torque in the right front wheel motor 2FR become smaller.

It should be noted that even when the yaw rate deviation Delyaw becomes large due to factors such as when the turning radius becomes smaller during turning or when the amount of operation of the steering 5 increases during turning, the front wheel required drive torque Frtrqrq is increased even if it is not at the start of turning. increases, the second front load turning torque in the left front wheel motor 2FL and the second front load turning torque in the right front wheel motor 2FR also increase.

Further, the front wheel required drive torque Frtrqrq increases as the front wheel load ratio Frwigtrt increases. Therefore, the larger the load on the front wheels 1F than on the rear wheels 1R, the greater the second front load turning torque in the left front wheel motor 2FL and the second front load turning torque in the right front wheel motor 2FR.

Further, when the vehicle required torque Cartrq is negative, that is, when the vehicle speed Spd is limited to the upper limit vehicle speed Spdlmt or less, the setting unit 16 sets the second load turning torque so that the vehicle speed Spd becomes the upper limit vehicle speed Spdlmt or less. do. As a result, the second control is performed to control the torque of each motor 2 so that the vehicle speed Spd is equal to or lower than the upper limit vehicle speed.

For example, when the front wheel required drive torque Frtrqrq is "50 Nm" and the vehicle required torque Cartrq is "-30 Nm", the setting unit 16 sets the second front load turning torque in the motor 2 that rotates the front wheels 1F ( "50 Nm" is set as the provisional torque TemtrqF). Further, in order to realize the vehicle required torque Cartrq as the torque of the entire vehicle C, the setting unit 16 sets the second front load turning torque (temporary torque TemtrqR of the rear wheels 1R) in the motor 2 that rotates the rear wheels 1R to: "-80 Nm" is set by subtracting "50 Nm", which is the front wheel drive torque Frtrqrq, from "-30 Nm", which is the vehicle required torque Cartrq. That is, when the vehicle required torque Cartrq is negative, the second front load turning torque in the motor 2 that rotates the rear wheels 1R becomes the braking torque. In this way, when the execution conditions for both the first control and the second control are satisfied, the first control is given priority, and in the second control, braking torque is generated in the motor 2 that rotates the rear wheel 1R.

If the vehicle C is in a preloaded state, does not satisfy the predetermined torque condition, and the provisional torque TemtrqR of the motor 2 that rotates the rear wheels 1R is smaller than the lower limit torque Rrtrqmn, the setting unit 16 sets each motor 2 to The torque to be generated is set to the third preload turning torque. As a result, the first control is performed to increase the torque in the motor 2 that rotates the front wheel 1F. Second control is performed to control the torque of each motor 2 so that the vehicle speed Spd is equal to or lower than the upper limit vehicle speed Spdlmt.

Specifically, the setting unit 16 sets the lower limit torque Rrtrqmn as the third preload turning torque in the motor 2 that rotates the rear wheel 1R. That is, the setting unit 16 limits the braking torque of the motor 2 that rotates the rear wheel 1R to the lower limit torque Rrtrqmn with respect to the provisional torque TemtrqR of the rear wheel 1R. When the second control is performed, if the braking torque that limits the vehicle speed Spd to the upper limit vehicle speed Spdlmt is smaller than the lower limit torque Rrtrqmn, the braking torque of the motor 2 that rotates the rear wheels 1R is limited to the lower limit torque Rrtrqmn. be.

Further, the setting unit 16 limits the drive torque in the motor 2 that rotates the front wheels 1F based on the limit amount of the braking torque in the motor 2 that rotates the rear wheels 1R. The setting unit 16 sets the absolute value of the deviation between the provisional torque TemtrqR of the motor 2 that rotates the rear wheel 1R and the lower limit torque Rrtrqmn as the limit amount, and subtracts the control amount from the provisional torque TemtrqF of the motor 2 that rotates the front wheel 1F. is set as the third preload turning torque in the motor 2 that rotates the front wheel 1F. That is, when the second control is performed and the braking torque for limiting the vehicle speed Spd to the upper limit vehicle speed Spdlmt is smaller than the lower limit torque Rrtrqmn, the first The driving torque of the front wheels 1F in the control is limited.

For example, when the front wheel required drive torque Frtrqrq is "50 Nm", the vehicle required torque Cartrq is "-30 Nm", and the lower limit torque Rrtrqmn is "-60 Nm", the provisional torque in the motor 2 that rotates the rear wheels 1R TemtrqR is "-80 Nm" obtained by subtracting "50 Nm", which is the front wheel drive torque Frtrqrq, from "-30 Nm", which is the vehicle required torque Cartrq.

In this case, since the provisional torque TemtrqR of the motor 2 that rotates the rear wheel 1R is smaller than the lower limit torque Rrtrqmn, the setting unit 16 sets the lower limit torque Rrtrqmn as the third preload turning torque of the motor 2 that rotates the rear wheel 1R. Set to "-60Nm". Further, the setting unit 16 calculates "20 Nm" as the limit amount of the limit torque, and subtracts the limit amount from "50 Nm", which is the provisional torque TemtrqF (front wheel required drive torque Frtrqrq) of the motor 2 that rotates the front wheels 1F. is set as the third preload turning torque of the motor 2 that rotates the front wheels 1F.

The setting unit 16 sets the torque obtained by dividing the lower limit torque Rrtrqmn into two equal parts as the third front load turning torque in the left rear wheel motor 2RL and the third front load turning torque in the right rear wheel motor 2RR. The setting unit 16 divides the torque obtained by subtracting the control amount from the provisional torque TemtrqF of the front wheels 1F into two equal parts as the third front load turning torque in the left front wheel motor 2FL and the third front load turning torque in the right front wheel motor 2FR. Set as turning torque.

A control signal for controlling each motor 2 is output to each motor 2 so that the torque set by the setting unit 16 is generated in each motor 2 . Thereby, the torque generated by each motor 2 is controlled.

Next, skid prevention control according to the embodiment will be described with reference to FIGS. 5A and 5B. FIG. 5A and FIG. 5B are flowcharts for explaining skid prevention control according to the embodiment.

The control device 10 calculates an estimated turning radius Rad (S100) and calculates an upper limit vehicle speed Spdlmt (S101). The control device 10 determines whether or not the vehicle speed Spd is equal to or higher than the upper limit vehicle speed Spdlmt (S102).

When the vehicle speed Spd is equal to or higher than the upper limit vehicle speed Spdlmt (S102: Yes), the control device 10 calculates the vehicle required torque Cartrq by feedback control based on the deviation between the vehicle speed Spd and the upper limit vehicle speed Spdlmt (S103). When the vehicle speed Spd is lower than the upper limit vehicle speed Spdlmt (S102: No), the control device 10 calculates the required vehicle torque Cartrq using, for example, a map based on the vehicle speed Spd and the accelerator opening Accel (S104).

The control device 10 determines whether or not the vehicle C is in the front load turning state (S105). When the state of the vehicle C is not the preload turning state (S105: No), the control device 10 sets the torque of each motor 2 to the normal torque (S106).

When the vehicle C is in the front load turning state (S105: Yes), the control device 10 calculates the yaw rate deviation Delyaw (S107) and calculates the front wheel drive required torque (S108).

The control device 10 determines whether the state of the vehicle C satisfies a predetermined torque condition (S109). When the state of the vehicle C satisfies the predetermined torque condition (S109: Yes), the control device 10 sets the torque of each motor 2 to the first front load turning torque (S110).

When the state of the vehicle C does not satisfy the predetermined torque condition (S109: No), the control device 10 calculates the provisional torque Temtrq (S111). Control device 10 calculates lower limit torque Rrtrqmn (S112).

The control device 10 determines whether or not the provisional torque TemtrqR of the rear wheels 1R is smaller than the lower limit torque Rrtrqmn (S113). When the provisional torque TemtrqR of the rear wheels 1R is smaller than the lower limit torque Rrtrqmn (S113: Yes), the control device 10 sets the torque of each motor 2 to the third preload turning torque (S114).

When the provisional torque TemtrqR of the rear wheels 1R is equal to or higher than the lower limit torque Rrtrqmn (S113: No), the control device 10 sets the torque of the rear wheels 1R in each motor 2 to the second front load turning torque (S115).

Next, effects of the control device 10 according to the embodiment will be described.

A control device 10 controls a vehicle C in which four drive wheels 1 are rotated by different motors 2, respectively. The control device 10 includes a control section 11 . The control unit 11 controls torque generated by the motor 2 . The control unit 11 controls the motor 2 to rotate the front wheels 1F when the vehicle C is in a front load state in which the load on the front wheels 1F is larger than the load on the other drive wheels 1 and the vehicle C is in a turning state. A first control is performed so that the torque at is increased.

As a result, the control device 10 can increase the front wheel traveling direction vertical component F2 of the driving force F1 applied to the front wheels 1F, thereby suppressing the increase of the cornering force CF (slip angle SA) applied to the front wheels 1F. Therefore, the control device 10 can secure a margin until the cornering force CF reaches the maximum cornering force CFmax. Therefore, the control device 10 can prevent the vehicle C from skidding when the vehicle C turns, and can prevent the vehicle C from understeering.

The first control performed by the control unit 11 sets the torque in the motor 2 that rotates the front wheels 1F based on the yaw rate deviation Delyaw, which is the deviation between the target yaw rate Yawtag and the actual yaw rate Yawreal of the vehicle C.

Accordingly, the control device 10 can accurately control the drive torque of the motor 2 that rotates the front wheels 1F based on the yaw rate of the vehicle C. FIG. Therefore, the control device 10 can further prevent the vehicle C from skidding when it turns. In addition, the control device 10 can stabilize the running of the vehicle C by accurately controlling the drive torque of the motor 2 that rotates the front wheels 1F when the vehicle is in the preload state and in the turning state.

In the first control performed by the control unit 11, the torque in the motor 2 that rotates the front wheels 1F is set to increase as the load on the front wheels 1F is greater than that on the rear wheels 1R.

Thereby, the control device 10 can secure a margin until the cornering force CF reaches the maximum cornering force CFmax. Therefore, the control device 10 can prevent sideslip from occurring when the vehicle C turns, and can prevent the vehicle C from understeering.

The first control performed by the control unit 11 is performed when the vehicle C is in a turning start state. As a result, the control device 10 can prevent the vehicle C from understeering even when the vehicle C starts to turn when understeering is likely to occur.

The control unit 11 performs a second control to set the torque of each motor 2 so that the vehicle speed Spd is equal to or lower than the upper limit vehicle speed Spdlmt at which the centrifugal acceleration of the vehicle C is equal to or lower than the upper limit centrifugal acceleration CNTYDNG.

As a result, the control device 10 limits the vehicle speed Spd when the vehicle C turns, thereby suppressing an increase in the centrifugal force F3 and further ensuring a margin until the cornering force CF reaches the maximum cornering force CFmax. be able to. Therefore, the control device 10 can further prevent skidding from occurring.

When the execution conditions for both the first control and the second control are satisfied, the control unit 11 gives priority to the first control and, in the second control, causes the motor 2 that rotates the rear wheel 1R to generate braking torque.

As a result, the control device 10 can increase the front-wheel traveling-direction vertical component F2 of the driving force F1 applied to the front wheels 1F. can be suppressed from increasing, and a margin can be secured until the cornering force CF at the front wheels 1F reaches the maximum cornering force CFmax. Therefore, the control device 10 can further prevent skidding from occurring.

When performing the second control, if the braking torque for limiting the vehicle speed Spd to the upper limit vehicle speed Spdlmt is smaller than the lower limit torque Rrtrqmn, the control unit 11 reduces the braking torque in the motor 2 that rotates the rear wheels 1R to the lower limit torque Rrtrqmn. limit to Further, the control unit 11 limits the driving torque of the front wheels 1F in the first control based on the limit amount of braking torque in the motor 2 that rotates the rear wheels 1R.

As a result, the control device 10 can prevent skidding while generating the maximum braking torque.

The control device 10 according to the above-described embodiment calculates the front wheel required driving torque Frtrqrq using the equation (7) based on the front wheel load ratio Frwigtrt when the vehicle C is in the front load turning state. is not limited to The control device 10 according to the modification may calculate the front wheel required driving torque Frtrqrq using the equation (7) based on the front wheel load ratio Frwigtrt only when the vehicle C starts turning.

For example, after step S107 in FIG. 5B, the control device 10 according to the modification determines whether or not it is time to start turning. to calculate the front wheel required drive torque Frtrqrq. The control device 10 according to the modified example sets the front wheel required driving base torque BASERQ as the front wheel required driving torque Frtrqrq when the turning is not started. For example, when the yaw rate deviation Delyaw is larger than a preset deviation, the control device 10 according to the modification determines that it is time to start turning. The control device 10 may determine that it is time to start turning based on the amount of change in the steering angle θ for a predetermined time. For example, the control device 10 determines that it is time to start turning when the amount of change in the steering angle θ is greater than a preset value.

As a result, the control device 10 according to the modification sets the front wheel required driving torque Frtrqrq based on the front wheel load ratio Frwigtrt only when the vehicle C is likely to skid, and performs torque control using the front wheel required driving torque Frtrqrq. I do. Therefore, the control device 10 according to the modified example can generate a torque in each drive wheel 1 according to the situation of the vehicle C, and can suppress giving the driver a sense of discomfort.

The control device 10 according to the above embodiment calculates the upper limit vehicle speed Spdlmt based on the estimated turning radius Rad and the upper limit centrifugal acceleration CNTYDNG. Instead of this, the control device 10 according to the modified example detects centrifugal acceleration applied to the vehicle C in the lateral direction using a G sensor, and calculates the estimated turning radius Rad and the detected centrifugal acceleration applied to the vehicle C in the lateral direction. Based on this, the upper limit vehicle speed Spdlmt may be calculated. That is, the upper limit vehicle speed Spdlmt is calculated with respect to the current centrifugal acceleration applied to the vehicle C in the lateral direction.

When the steering device of vehicle C is a steer-by-wire system and vehicle speed Spd is limited to upper limit vehicle speed Spdlmt, torque control in each motor 2 starts before steering angle θ of front wheels 1F is adjusted by the actuator. may be The control delay of the actuator with respect to the operation of the steering wheel 5 is set to such an extent that the driver does not feel the delay in the turning motion of the vehicle C.

As a result, the control of the vehicle speed Spd is started before the steering angle of the drive wheels 1 is actually changed, so that the vehicle C can be prevented from skidding.

The control device 10 according to the modification may execute the skid prevention control during turning regardless of whether the vehicle C is in a preload state. In this case, the control device 10 sets the torque of each motor 2 during turning so that the vehicle speed Spd is equal to or lower than the upper limit vehicle speed Spdlmt corresponding to the upper limit centrifugal acceleration CNTYDNG.

In the above embodiment, the torque distribution between the left and right wheels in the front wheel 1F and the torque distribution between the left and right wheels in the rear wheel 1R are equally divided, but the present invention is not limited to this. The distribution amounts for the left and right drive wheels 1 may be different. For example, the distribution amount for the drive wheels 1 on the outside of the turn may be larger than the distribution amount for the drive wheels 1 on the inside of the turn.

In the above embodiment, the vehicle C having four driving wheels 1 was described as an example. are provided with three or more drive wheels 1. Further, a plurality of driving wheels 1 may be arranged side by side in the left-right direction on one side of the vehicle C in the left-right direction.

In such a case, for example, the control device 10 controls only the torque of the outermost and frontmost front wheel 1F and the innermost and rearmost rear wheel 1R. Further, for example, the control device 10 controls the torque of the drive wheels 1 other than the outermost and rearmost rear wheel 1R and the innermost and frontmost front wheel 1F. Further, for example, the control device 10 groups the wheels into front wheels 1F and rear wheels 1R depending on whether they are forward or rearward of the center of the vehicle C, and groups them into left wheels and right wheels depending on whether they are left or right of the center of the vehicle C. and control the torque of the drive wheel 1 corresponding to each group.

In the above-described embodiment, the sideslip prevention control that is executed before sideslip occurs has been described. may be In other words, the control device 10 may execute sideslip prevention control and, when sideslipping occurs, may also execute sideslip prevention control. Also, part of the skid suppression control may be applied to the vehicle C that is automatically driven.

Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments so shown and described. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and equivalents thereof.

1 driving wheel 1F front wheel 1R rear wheel 2 motor 10 control device 11 control unit (motor control unit)
13 detection unit 14 calculation unit 15 determination unit 16 setting unit C vehicle

Claims (8)

A vehicle control device for controlling a vehicle in which a plurality of drive wheels are rotated by different motors,
a motor control unit that controls the torque generated by the motor,
When the vehicle is in a preload state in which the load on the front wheels is larger than the load on the other drive wheels and the vehicle is in a turning state, the motor control unit controls the torque in the motor that rotates the front wheels. A vehicle control device, characterized in that a first control is set to increase 2. The vehicle control according to claim 1, wherein the first control performed by the motor control unit sets torque in a motor that rotates the front wheels based on a deviation between a target yaw rate and an actual yaw rate of the vehicle. Device. 3. The first control performed by the motor control unit sets the torque of the motor that rotates the front wheels so that it increases as the load on the front wheels is larger than that on the rear wheels. Vehicle controller as described. The vehicle control device according to any one of claims 1 to 3, wherein the first control performed by the motor control unit is performed when the vehicle is in a turning start state. 5. The motor control unit performs a second control to set the torque of each motor so that the vehicle speed is equal to or lower than the upper limit vehicle speed corresponding to the upper limit centrifugal acceleration. The vehicle control device according to any one of The motor control unit gives priority to the first control when the execution conditions for both the first control and the second control are satisfied, and in the second control, the braking torque is applied to the motor that rotates the rear wheels. 6. The vehicle control device according to claim 5, characterized by: When performing the second control, if the braking torque for limiting the vehicle speed to the upper limit vehicle speed is smaller than the lower limit torque, the motor control unit reduces the braking torque of the motor for rotating the rear wheels to the lower limit torque. 7. The vehicle control device according to claim 6, wherein the drive torque of the front wheels in the first control is limited based on a limit amount of braking torque in a motor that rotates the rear wheels. A control method for controlling a vehicle in which a plurality of drive wheels are rotated by different motors,
When the vehicle is in a preloaded state in which the load on the front wheels is greater than the load on the other drive wheels and the vehicle is turning, the torque in the motor that rotates the front wheels is set to increase. A control method characterized by performing a first control to control.

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