JP2016146731A - Braking/driving torque control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to suppress tire slip generated when acceleration or deceleration is performed at a place of a low road surface friction coefficient or the like, and to suppress change in a vehicle attitude even if an unnecessary yaw moment is generated in a vehicle.SOLUTION: A braking/driving torque control device comprises: a slip ratio control unit 14 which so suppresses a slip ratio of left and right wheels 2 as to be qual to or less than an upper limit slip ratio and equal to or more than a lower limit slip ratio by controlling a braking/driving torque of the wheels 2; and a vehicle attitude control unit 15. The vehicle attitude control unit 15 comprises: yaw rate deviation calculation means 24 for calculating a deviation between a real yaw rate and a target yaw rate; control wheel setting means 25 for setting the wheel 2 in which the upper limit or lower limit slip ratio is changed as a control wheel; upper limit slip ratio calculation means 26A; and lower limit slip ratio calculation means 26B. The upper limit slip ratio calculation means 26A and the lower limit slip ratio calculation means 26B respectively decrease the upper limit slip ratio or increase the lower limit slip ratio so as to eliminate yaw rate deviation.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a braking / driving torque control device for suppressing tire slip of a vehicle and ensuring posture stability.

  Conventionally, as a traction control method for left and right independent drive vehicles, control that suppresses tire slip that occurs when accelerating or decelerating in places with a low road surface friction coefficient and suppressing unnecessary yaw moment generation in the vehicle Has been proposed. In the prior art 1 (Patent Document 1), the reference speed of the other motor rotation speed to be controlled is determined based on the motor rotation speed of one of the left and right wheels as a pair. A certain allowable speed range is added to the reference speed determined here, and this is set as the speed limit range of the motor rotation speed to be controlled. By providing a limit on the torque command value based on the set speed limit range, stable running can be performed while maintaining grip even on a slippery road surface.

  In Prior Art 2 (Non-Patent Document 1), a target slip ratio of wheels is set in a left and right independent drive vehicle, and the drive torque is controlled in accordance with the difference between the target slip ratio and the actual slip ratio, thereby achieving the target slip ratio. Suppress wheel slip to follow

JP 2008-109787 A

Takeshi Fujita et al .: Traction control of electric vehicles, Automobile Engineering Society Autumn Academic Lecture Preprint, No.107-08 (2008), 11-16

  In the control of the prior art 1, information on road surface conditions and wheel slip such as road surface friction coefficient, front / rear force acting on the wheel, or wheel slip rate is not used, so it is expected that there may be a situation where wheel slip cannot be sufficiently suppressed. Is done.

  In the control of the prior art 2, since the target slip ratio of the left and right wheels is the same, if the road surface characteristics are different between the left and right wheels, a difference between the left and right forces is generated. As a result, an unintended yawing motion may occur.

  In order to solve such problems, we proposed a control that suppresses tire slip that occurs when starting and accelerating in places where the road surface friction coefficient is low, and that suppresses unnecessary yaw moments from being generated in the vehicle. For example, it is unnecessary for the vehicle by estimating the longitudinal force generated on the road surface by the respective driving wheels of the left and right independent driving vehicles and controlling the driving torque so that the left and right longitudinal forces coincide with the lower one. Control so that yaw moment does not occur.

  However, the proposed example has a problem in controlling the vehicle attitude. That is, in the above proposed example, the longitudinal force generated on the road surface by the respective driving wheels of the left and right independent drive vehicles is estimated, and the drive torque is controlled so that the left and right longitudinal forces coincide with the lower one. However, for example, if the external force such as the drag torque of the friction brake is greatly different between the left and right wheels, the estimated longitudinal force is greatly deviated from the actual longitudinal force. Further, although not described in Patent Document 1, when the external force is greatly different between the left and right wheels during braking, the estimated longitudinal force is greatly deviated from the actual longitudinal force. In these cases, even if the braking / driving torque is controlled so that the estimated left / right front / rear forces are matched to the lower side, the actual front / rear forces differ from left to right, so an unnecessary yaw moment is generated in the vehicle and the vehicle posture changes. There is a case. In addition, if there is a sudden change in the road surface friction coefficient such as locally different road surfaces, an unnecessary yaw moment may be generated in the vehicle and the vehicle posture may change if the control cannot be followed with good responsiveness.

  The present invention has been made to solve the above-described problem, and suppresses tire slip that occurs when accelerating or decelerating in a place where the road surface friction coefficient is low, and an unnecessary yaw moment is generated in the vehicle. It is an object of the present invention to provide a braking / driving torque control device for a vehicle that can suppress changes in the vehicle posture.

The vehicle braking / driving torque control device according to the present invention is a vehicle braking / driving torque control device for controlling a vehicle 1 having a braking / driving source 4 capable of independently controlling braking torque or driving torque of left and right wheels 2.
Controlling the braking torque or driving torque of the left and right wheels 2 to control the slip ratio of the wheels 2 below the upper limit slip ratio or above the lower limit slip ratio, and the attitude of the vehicle 1 Vehicle attitude control device 15 for
The vehicle attitude control device 15
Target yaw rate calculation means 23 for calculating a target yaw rate of the vehicle using at least the vehicle speed and the steering angle;
A yaw rate deviation calculating means 24 for calculating a yaw rate deviation which is a deviation between the actual yaw rate measured from the sensor 19 mounted on the vehicle 1 and the target yaw rate;
Control wheel setting means 25 for setting the wheel 2 for changing the upper limit slip ratio or the lower limit slip ratio as a control wheel;
A limit slip ratio calculation means 26 having at least one of an upper limit slip ratio calculation means 26A for calculating the upper limit slip ratio of the control wheel and a lower limit slip ratio calculation means 26B for calculating the lower limit slip ratio;
The control wheel setting means 25 sets either the right or left wheel as a control wheel when the yaw rate deviation occurs in the vehicle,
In order to eliminate the yaw rate deviation of the vehicle 1, the upper limit slip ratio calculation unit 26A makes the upper limit slip ratio smaller than a value before the yaw rate deviation occurs, or the lower limit slip ratio. The calculation means 26B makes the lower limit slip ratio larger than a value before the yaw rate deviation occurs.
It is characterized by that.

The braking / driving torque control device having this configuration is applied to the vehicle 1 capable of independently controlling the braking torque or driving torque of each wheel 2. When the slip ratio generated during braking is positive and the slip ratio generated during driving is negative, if the slip ratio of a certain wheel 2 exceeds a preset upper limit slip ratio, the slip ratio control device 14 The braking torque or driving torque of the wheel 2 is controlled to be as follows. When the slip rate of a certain wheel 2 is lower than a slip rate that is a preset lower limit, the slip rate control device 14 controls the driving torque of the wheel 2 so as to be equal to or higher than the lower limit slip rate ( Slip rate control). In general, during braking, the front / rear force that can be generated saturates as the slip ratio of the wheel 2 increases. Therefore, it is preferable to set the upper limit slip ratio with the slip ratio at which the front / rear force is approximately saturated as an upper limit. Further, since the longitudinal force that can be generated is saturated when the slip ratio of the wheel 2 is reduced during driving, it is preferable to set the lower limit slip ratio with the slip ratio at which the longitudinal force is approximately saturated as a lower limit.
While the vehicle is running, the target yaw rate is calculated by the target yaw rate calculation means 23 from values such as the vehicle speed and the steering angle, and the actual yaw rate is measured by an in-vehicle sensor 19 such as a yaw rate sensor. When the slip ratio control is operating with one or more wheels, if a deviation between the target yaw rate and the actual yaw rate (yaw rate deviation) occurs, the control wheel setting means 25 generates a yaw moment that eliminates the yaw rate deviation. wheel sets the wheels 2 turning inner side of the direction that you want to generate a yaw moment as the control wheel 2 _1, wherein the limit slip rate calculating means 26, during driving of the turning inner wheel side orientation to be generated yaw moment The lower limit slip rate of No. 2 (control wheel) is increased, and the upper limit slip rate of the wheel 2 on the turning outer wheel side in the direction in which the yaw moment is to be generated is reduced during braking. By reducing the upper limit slip ratio, the longitudinal force generated by the wheel 2 is increased and the yaw moment is generated. Further, by increasing the lower limit slip ratio, the longitudinal force generated by the wheel 2 is reduced and the yaw moment is generated.
If the value of the upper limit slip ratio is decreased from positive to negative, the drive torque acts on the control wheel during braking, and if the value of the lower limit slip ratio is increased from negative to positive, the control wheel during drive is increased. The braking torque will act. In the present invention, switching between driving and braking can be performed continuously only by changing the upper limit slip ratio or the lower limit slip ratio.

In the present invention, by controlling the slip ratio of each wheel 2, tire slip that occurs when accelerating or decelerating at a place where the road surface friction coefficient is low is suppressed below the upper limit slip ratio or above the lower limit slip ratio. In this specification, the term “acceleration” includes “start”. Furthermore, a moment for eliminating the yaw rate deviation may be generated by lowering the upper limit slip ratio or increasing the lower upper limit slip ratio according to the yaw rate deviation generated in the vehicle 1, thereby suppressing the change in the vehicle posture. Since the control is to suppress the slip ratio by decreasing the upper limit slip ratio or increasing the lower limit slip ratio, there is no possibility of wheel spin or tire lock due to braking / driving torque, and the vehicle posture can be further stabilized.
As described above, the present invention suppresses tire slip that occurs when accelerating or decelerating in a place where the road surface friction coefficient is low, and also changes the vehicle posture even when an unnecessary yaw moment is generated in the vehicle 1. It can be suppressed.

In the present invention, the limit slip ratio calculating means 26 includes the upper limit slip ratio calculating means 26A, and the upper limit slip ratio calculating means 26A corresponds to the upper limit slip on the turning inner wheel side according to the magnitude of the yaw rate deviation during braking. The rate may be reduced.
In the present invention, the limited slip ratio calculating means 26 includes the lower limit slip ratio calculating means 26B, and the lower limit slip ratio calculating means 26B is configured to reduce the lower limit slip on the turning outer wheel side according to the magnitude of the yaw rate deviation during driving. The rate may be increased.
As the magnitude of the yaw rate deviation is larger, the generated upper yaw rate deviation is decreased or the lower limit slip ratio is increased, so that the generated yaw rate deviation can be eliminated early.

In these cases, the upper limit slip ratio calculating means 26A may provide a lower limit value for the upper limit slip ratio. As a result, it is possible to limit the change in the vehicle posture when the upper limit slip ratio is reduced.
Further, the lower limit slip ratio calculating means 26B may provide an upper limit value for the lower limit slip ratio. Thereby, it is possible to limit the change in the vehicle posture when the lower limit slip ratio is increased.

In the present invention, the control wheel setting means 25 may set a plurality of wheels 2 as the control wheel.
For example, in a four-wheel drive vehicle, the front and rear wheels 2 on the turning inner wheel side may be brake wheels. Although only one wheel may be used as a brake wheel, the vehicle posture can be stabilized more effectively by using a plurality of wheels as brake wheels.

In the present invention, when the sign of torque differs between the left and right wheels, the limited slip ratio calculating means 26 may hold the upper limit slip ratio at a preset value. (ESC control etc.).
As described above, when the slip ratio is controlled when torques having different signs are generated on the left and right wheels, the upper limit slip ratio or the lower limit slip ratio is maintained at a preset value, thereby enabling stable control. Easy to do.

In the present invention, the vehicle 1 may be configured to include the electric motor 4 on each of the plurality of wheels 2.
The present invention can be applied even when the braking / driving source 4 is an internal combustion engine. However, when the braking / driving source 4 is provided with an electric motor 4, the present invention is superior in responsiveness and controllability compared to the internal combustion engine. The posture can be stabilized more effectively by controlling the driving torque.

  The braking / driving torque control device for a vehicle according to the present invention is the vehicle braking / driving torque control device for controlling a vehicle having a braking / driving source capable of independently controlling the braking torque or driving torque of the left and right wheels. A slip ratio control device for controlling the braking torque or the driving torque to suppress the slip ratio of the wheel to an upper limit slip ratio or less or a lower limit slip ratio, and a vehicle attitude control device for controlling the attitude of the vehicle, The vehicle attitude control device includes a target yaw rate calculating means for calculating a target yaw rate of the vehicle using at least a vehicle speed and a steering angle, and a yaw rate that is a deviation between an actual yaw rate measured from a sensor mounted on the vehicle and the target yaw rate. A yaw rate deviation calculating means for calculating a deviation; and changing the upper limit slip ratio or the lower limit slip ratio. A limited slip having at least one of control wheel setting means for setting a wheel to be controlled as a control wheel, upper limit slip ratio calculation means for calculating the upper limit slip ratio of the control wheel, and lower limit slip ratio calculation means for calculating the lower limit slip ratio Rate control means, and when the yaw rate deviation occurs in the vehicle, the control wheel setting means sets either the right or left wheel as a control wheel, and the limit slip ratio calculation means In order to eliminate the yaw rate deviation, the upper limit slip ratio calculating means is less than the upper limit slip ratio before the yaw rate deviation occurs, or the lower limit slip ratio calculating means determines the lower limit slip ratio as the yaw rate deviation. Occurs when accelerating or decelerating in places where the coefficient of friction of the road surface is low. In addition to suppressing tire slip, changes in the vehicle posture can be suppressed even when an unnecessary yaw moment is generated in the vehicle.

1 is a system configuration diagram showing a conceptual configuration of a vehicle braking / driving torque control device according to an embodiment of the present invention; FIG. It is a block diagram which shows the one part specific example of the braking / driving torque control apparatus of the vehicle. It is explanatory drawing which shows the effect | action at the time of the drive of the braking / driving torque control apparatus of the vehicle. It is explanatory drawing which shows the effect | action at the time of braking of the braking / driving torque control apparatus of the vehicle. It is a graph which shows the relationship between the slip ratio of a wheel, and the longitudinal force. It is sectional drawing which shows an example of the in-wheel motor drive device of the vehicle to which the same braking / driving torque control device is applied.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a conceptual configuration of an electric vehicle that is a left and right wheel independent drive type vehicle equipped with a braking / driving torque control device according to this embodiment, and the right side of the figure is the front side of the vehicle. This electric vehicle is a four-wheel independent drive vehicle in which the left and right rear wheels 2 and the left and right front wheels 2 of the vehicle 1 are independently driven by a motor 4 as a braking / driving source. . The front wheel 2 is a steering wheel. In FIG. 1, the left side of the page is the front of the vehicle. Each motor 4 is an electric motor and constitutes, for example, the in-wheel motor drive device 5 of FIG. 6, but may be an on-board type mounted on a chassis (not shown).

  In FIG. 6, the in-wheel motor drive device 5 includes a motor 4 that is an in-wheel motor (IWM), a speed reducer 6, and a wheel bearing 7, and a part or all of these are arranged in the wheel 2. . The rotation of the motor 4 is transmitted to the wheel 2 via the speed reducer 6 and the wheel bearing 7. A brake rotor 8a constituting the friction brake device 8 is fixed to the flange portion of the hub wheel 7a of the wheel bearing 7, and the brake rotor 8a rotates integrally with the wheel 2. The motor 4 is, for example, an embedded magnet type synchronous motor in which a permanent magnet is built in the core portion of the rotor 4a. The motor 4 is a motor in which a radial gap is provided between a stator 4b fixed to the housing 4c and a rotor 4a attached to the rotation output shaft 9.

The control system will be described with reference to FIG. The vehicle 1 includes an ECU (electric control unit) 11 and a plurality (four in this example) of inverter devices 12 provided for each motor 4. The ECU 11 includes a main ECU unit 13 having a general function, and a slip ratio control device 14 and a vehicle attitude control device 15 that are specific to this embodiment. Note that the slip ratio control device 14 and the vehicle attitude control device 15 may be provided as independent ECUs or in the inverter device 12 instead of being provided in the ECU 11.
The ECU 11 includes a computer such as a microcomputer, a program executed by the computer, and various electronic circuits. The ECU 11 and each inverter device 12 are connected by an in-vehicle communication network such as a CAN (control area network).

  The main ECU 13 has, as its basic configuration, a function of performing overall control and cooperative control of the entire vehicle, and a braking / driving command generation function. This braking / driving command generation function includes a drive command that is a command of an operation amount detected by an accelerator pedal sensor 16 provided on an accelerator pedal (not shown), and a brake pedal sensor provided on a brake pedal (not shown). 36 is a function for generating a drive command such as a torque command to be distributed to each motor 4 from a braking / driving command (braking command and drive command) which is a command of the operation amount detected by 36. The accelerator pedal and the brake pedal may be operating means other than a pedal type. The braking / driving command generated by the main ECU 13 is normally sent to the inverter device 12, but in this embodiment is sent to the inverter device 12 via the vehicle attitude control device 15 and the slip ratio control device 14.

  Each inverter device 12 is means for converting DC power of a battery (not shown) into AC power for driving the motor 4, and has a control unit (not shown) for controlling the output thereof. The motor 4 in charge is controlled in accordance with a braking / driving force command such as a distributed torque command. Each inverter device 12 includes a power circuit unit (not shown) such as a bridge circuit of a switching element that converts AC power, and a control unit that controls the power circuit unit.

  In addition to the accelerator pedal sensor 16 and the brake pedal sensor 36, the vehicle 1 is provided with a steering angle sensor 17, a vehicle speed sensor 18, and a yaw rate sensor 19 as sensors. The steering angle sensor 17 is a sensor that detects the steering angle of a steering means (not shown) such as a steering handle. The steering angle sensor 17 may be a sensor that detects a steering angle of a steering device (not shown). The motor 4 is provided with a rotation sensor (not shown) for detecting the motor rotation speed, and the inverter device 12 has means (not shown) for calculating the wheel speed from the detection signal of the rotation sensor. doing.

  When the driver operates the accelerator pedal to instruct driving, an accelerator command value is input from the accelerator pedal sensor 16 to the main ECU unit 13. When the brake pedal 36 is operated and braking is instructed, a brake command value is input from the brake pedal sensor 36 to the main ECU unit 13. The input accelerator command value and brake command value are input from the main ECU 13 to the slip ratio control device 14 of each wheel 2 as a torque command value for driving each wheel 2.

  The slip ratio control device 14 is means for controlling the braking torque or driving torque of the left and right wheels 1 to suppress the slip ratio of the wheels to be equal to or lower than the upper limit slip ratio and higher than the lower limit slip ratio. As shown in FIG. 2, the slip ratio control device 14 includes a slip ratio calculation means 21 and a braking / driving torque calculation means 22. In this example, the slip ratio calculating means 21 calculates the slip ratio using the vehicle speed input from the vehicle speed sensor 18 (that is, the vehicle speed) and the wheel speed input from the inverter device 12. In the braking / driving torque calculating means 22, the final slip rate is controlled by PID control so that the slip rate does not exceed the upper limit slip rate set in advance before practical operation of the vehicle 1 or during maintenance, or does not fall below the lower limit slip rate. Calculate the torque command value. The calculated final torque command value is given to the inverter device 12 as a braking / driving command.

  Assuming that the slip ratio generated during braking is positive and the slip ratio generated during driving is negative, the front / rear force that can be generated is saturated when the wheel slip ratio increases as shown in FIG. The upper limit slip ratio is set with the upper limit of the slip ratio at which the force is approximately saturated. Further, during driving, the front / rear force that can be generated saturates when the wheel slip ratio decreases, so the lower limit slip ratio is set with the slip ratio at which the front / rear force is approximately saturated as a lower limit. The upper limit slip ratio and the lower limit slip ratio can be changed by input from input means (not shown) provided in the vehicle attitude control device 15 (see FIG. 2). The slip ratio control device 14 (see FIG. 2) outputs a final torque command value to the inverter, controls the current so as to be the final torque command value, and drives the motor. The inverter calculates the wheel speed from the motor rotation speed of the in-wheel motor.

  1 and 2, information on the vehicle speed and the steering angle is input to the vehicle attitude control device 15 from the vehicle speed sensor 18 and the steering angle sensor 17 through the main ECU unit 13. The actual yaw rate measured by the on-vehicle yaw rate sensor 19 is also input.

  In FIG. 2, the vehicle attitude control device 15 includes target yaw rate calculation means 23, yaw rate deviation calculation means 24, control wheel setting means 25, and limit slip ratio calculation means 26. The limited slip ratio calculating means 26 includes an upper limit slip ratio calculating means 26A and a lower limit slip ratio calculating means 26B. The target yaw rate calculation means 23 is a means for calculating the target yaw rate of the vehicle using at least the vehicle speed and the steering angle. The target yaw rate calculation means 23 calculates the target yaw rate of the vehicle 1 from information on the vehicle speed and the steering angle, and vehicle parameters such as the vehicle weight and the position of the center of gravity set in advance before practical operation of the vehicle 1 or during maintenance. .

The yaw rate deviation calculating means 24 subtracts the actual yaw rate from the target yaw rate and outputs the yaw rate deviation. When the yaw rate deviation occurs when the slip ratio control is operating with one or more wheels, the control wheel setting means 25 and the upper limit slip ratio calculating means 26A or the lower limit slip ratio are calculated. The rate calculation means 26B functions.
The control wheel setting means 25 is a means for setting the wheel 1 for changing the upper limit slip ratio as a control wheel. The control wheel setting means 25 determines whether the vehicle 1 has an understeer tendency or a spin tendency from the target yaw rate, the actual yaw rate, and the sign of the yaw rate deviation, and drives so as to generate a yaw moment that eliminates the yaw rate deviation. when sets the wheels 2 turning inner side of the direction that you want to generate a yaw moment as the control wheel 2 ₁ (Figure 3). Further, braking is set to the turning outer wheel side orientation to be generated yaw moment as the control wheel 2 ₁ (FIG. 4). Controlled wheel 2 ₁ may be one wheel of the turning inner wheel side, may be multiple rings.

  The upper limit slip ratio calculating means 26A is means for lowering the upper limit slip ratio from a value before the yaw rate deviation occurs in order to eliminate the yaw rate deviation of the vehicle. The upper limit slip ratio calculating means 26A calculates the upper limit slip ratio by PID control so that the yaw rate deviation is zero. Further, the lower limit slip ratio calculating means 26B is means for increasing the lower limit slip ratio from a value before the yaw rate deviation occurs in order to eliminate the yaw rate deviation of the vehicle. The lower limit slip ratio calculating means 26B calculates the lower limit slip ratio by PID control so that the yaw rate deviation is zero. By reducing the upper limit slip ratio, the braking force generated by the wheel 1 is reduced and the yaw moment is generated. Further, by increasing the lower limit slip ratio, the driving force generated by the wheels is reduced and the yaw moment is generated. As the magnitude of the yaw rate deviation is larger, the generated upper yaw rate deviation is decreased or the lower limit slip ratio is increased. If the value of the upper limit slip ratio is decreased from positive to negative, the drive torque acts on the control wheel during braking, and if the value of the lower limit slip ratio is increased from negative to positive, the control wheel during drive is increased. The braking torque will act.

  In this embodiment, switching between driving and braking can be performed continuously only by changing the upper limit slip ratio or the lower limit slip ratio. Further, in order to limit the change in the vehicle posture when the upper limit slip ratio is lowered, a lower limit value may be set for the upper limit slip ratio, or the change in the vehicle posture when the lower limit slip ratio is increased. In order to set a limit, an upper limit value may be set for the lower limit slip ratio.

In this embodiment, by controlling the slip rate of each wheel 2, the tire slip that occurs when accelerating or decelerating at a place where the road surface friction coefficient is low is suppressed to be equal to or lower than the upper limit slip rate or higher than the lower limit slip rate. Further, by reducing the upper limit slip rate or increasing the upper limit slip rate according to the yaw rate deviation generated in the vehicle 1, a change in the vehicle posture is suppressed by generating a moment that eliminates the yaw rate deviation. Since the control is to suppress the slip ratio by reducing the upper limit slip ratio or increasing the lower limit slip ratio, there is no possibility of wheel spin or tire lock due to braking / driving torque, and the vehicle posture can be further stabilized.
Further, when the slip ratio is controlled when torques having different signs are generated in the left and right wheels, the upper limit slip ratio or the lower limit slip ratio is held at a preset value (ESC control or the like).

  The operation of the above configuration will be summarized and described. This embodiment is applied to the vehicle 1 in which the braking torque or driving torque of each wheel 2 can be controlled independently. When the slip ratio generated during braking is positive and the slip ratio generated during driving is negative, if the slip ratio of a certain wheel 2 exceeds a preset upper limit slip ratio, the slip ratio control device 14 The braking torque or driving torque of the wheel 2 is controlled to be as follows. When the slip rate of a certain wheel 2 is lower than a slip rate that is a preset lower limit, the driving torque of the wheel 2 is controlled to be equal to or higher than the lower limit slip rate (slip rate control). In general, during braking, the front / rear force that can be generated saturates as the slip ratio of the wheel 2 increases. Therefore, it is preferable to set the upper limit slip ratio with the slip ratio at which the front / rear force is approximately saturated as an upper limit. Further, since the longitudinal force that can be generated is saturated when the slip ratio of the wheel 2 is reduced during driving, it is preferable to set the lower limit slip ratio with the slip ratio at which the longitudinal force is approximately saturated as a lower limit.

  While the vehicle is running, the target yaw rate is calculated by the target yaw rate calculation means 23 from values such as the vehicle speed and the steering angle, and the actual yaw rate is measured by an in-vehicle sensor 19 such as a yaw rate sensor. When the slip ratio control is operating with one or more wheels, if a deviation between the target yaw rate and the actual yaw rate (yaw rate deviation) occurs, the control wheel setting means 25 generates a yaw moment that eliminates the yaw rate deviation. Increases the lower limit slip rate of the turning inner wheel side wheel 2 (control wheel) in the direction in which the yaw moment is desired during driving, and the upper limit of the turning outer wheel side wheel 2 in the direction in which yaw moment is desired during braking. Reduce slip ratio. By reducing the upper limit slip ratio, the longitudinal force generated by the wheels is increased and the yaw moment is generated.

  Further, by increasing the lower limit slip ratio, the longitudinal force generated by the wheel 2 is reduced and the yaw moment is generated. As the magnitude of the yaw rate deviation is larger, the generated upper yaw rate deviation is decreased or the lower limit slip ratio is increased, so that the generated yaw rate deviation can be eliminated early. If the value of the upper limit slip ratio is decreased from positive to negative, the drive torque acts on the control wheel during braking, and if the value of the lower limit slip ratio is increased from negative to positive, the control wheel during drive is increased. The braking torque will act.

  In this embodiment, switching between driving and braking can be performed continuously only by changing the upper limit slip ratio or the lower limit slip ratio. Further, in order to limit the change in the vehicle posture when the upper limit slip ratio is lowered, a lower limit value may be set for the upper limit slip ratio, or the change in the vehicle posture when the lower limit slip ratio is increased. In order to set a limit, an upper limit value may be set for the lower limit slip ratio.

  In the above embodiment, an in-wheel motor type four-wheel drive vehicle has been described. However, the present invention can be applied to a rear wheel drive vehicle in which only two rear wheels have an in-wheel motor or a non-in-wheel motor type. An electric vehicle configured to transmit the output of two motors installed on the vehicle body corresponding to each of the left and right wheels, for example, to each wheel via a drive shaft or the like, and independently control the driving torque of each wheel It can also be applied. Furthermore, the present invention can also be applied to a vehicle having a braking / driving source having an internal combustion engine as a driving source and a friction brake as a braking source.

  As mentioned above, although the form for implementing this invention based on the Example was demonstrated, embodiment disclosed here is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Vehicle 2 ... Wheel 4 ... Motor (braking / driving source)
5 ... In-wheel motor drive device 6 ... Reducer 7 ... Wheel bearing 8 ... Friction brake device 11 ... ECU
DESCRIPTION OF SYMBOLS 12 ... Inverter device 13 ... Main ECU part 14 ... Slip rate control device 15 ... Vehicle attitude control device 16 ... Accelerator pedal sensor 17 ... Rudder angle sensor 18 ... Vehicle speed sensor 19 ... Yaw rate sensor 21 ... Slip rate calculation means 22 ... Braking / driving torque Calculation means 23 ... Target yaw rate calculation means 24 ... Yaw rate deviation calculation means 25 ... Control wheel setting means 26 ... Limit slip ratio calculation means 26A ... Upper limit slip ratio calculation means 26B ... Lower limit slip ratio calculation means 36 ... Brake pedal sensor

Claims (8)

In a vehicle braking / driving torque control device for controlling a vehicle having a braking / driving source capable of independently controlling braking torque or driving torque of left and right wheels,
A slip ratio control device for controlling the braking torque or driving torque of the left and right wheels to suppress the slip ratio of the wheels to an upper limit slip ratio or less or a lower limit slip ratio and a vehicle attitude control for controlling the attitude of the vehicle With the device,
The vehicle attitude control device includes:
Target yaw rate calculating means for calculating a target yaw rate of the vehicle using at least the vehicle speed and the steering angle;
A yaw rate deviation calculating means for calculating a yaw rate deviation which is a deviation between an actual yaw rate measured from a sensor mounted on a vehicle and the target yaw rate;
Control wheel setting means for setting a wheel for changing the upper limit slip ratio or the lower limit slip ratio as a control wheel;
A limit slip ratio calculating means having at least one of an upper limit slip ratio calculating means for calculating the upper limit slip ratio of the control wheel and a lower limit slip ratio calculating means for calculating the lower limit slip ratio;
The control wheel setting means sets the right or left wheel as a control wheel when the yaw rate deviation occurs in the vehicle,
In order to eliminate the yaw rate deviation of the vehicle, the upper limit slip rate calculating means is configured such that the upper limit slip ratio is smaller than a value before the yaw rate deviation occurs, or the lower limit slip ratio calculating means , Making the lower limit slip ratio larger than the value before the yaw rate deviation occurs,
A braking / driving torque control device for a vehicle.   2. The braking / driving torque control device for a vehicle according to claim 1, wherein the limit slip ratio calculation means includes the upper limit slip ratio calculation means, and the upper limit slip ratio calculation means corresponds to the magnitude of the yaw rate deviation during braking. A braking / driving torque control device for a vehicle that reduces the upper limit slip ratio on the turning inner wheel side.   2. The braking / driving torque control device for a vehicle according to claim 1, wherein the limiting slip ratio calculating means includes the lower limit slip ratio calculating means, and the lower limit slip ratio calculating means corresponds to the magnitude of the yaw rate deviation during driving. A braking / driving torque control device for a vehicle that increases the lower limit slip ratio on the turning outer wheel side.   The braking / driving torque control device for a vehicle according to claim 2, wherein the upper limit slip ratio calculating means sets a lower limit value for the upper limit slip ratio.   4. The vehicle braking / driving torque control device according to claim 3, wherein the lower limit slip ratio calculating means sets an upper limit value for the lower limit slip ratio.   6. The braking / driving torque control device for a vehicle according to claim 1, wherein the control wheel setting means sets a plurality of wheels as the control wheel.   7. The vehicle braking / driving torque control device according to claim 1, wherein when the sign of torque differs between the left and right wheels, the limited slip ratio calculating means calculates the upper limit slip ratio. A braking / driving torque control device for a vehicle that maintains a preset value.   The braking / driving torque control device for a vehicle according to any one of claims 1 to 7, wherein the vehicle includes an electric motor for each of a plurality of wheels.

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