JP2016199146A - Control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a vehicle which can provide stable yaw moment even if load movement occurs to front wheels.SOLUTION: In the control device of a vehicle, when calculating yaw moment at which a yaw rate target value is attained in making the vehicle to generate the yaw moment by controlling torque differences between left and right wheels of at least either one of front and rear wheels, a front/rear wheel cornering power variation estimating portion 600 calculates variations of cornering power which increase in the front wheels and decrease in the rear wheels as the amount of load movement to the front wheels is larger, outputs the variations to DYC control portions 601-604 and makes the yaw moment smaller.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle control device that independently controls torques of left and right wheels.

  As a technique for independently controlling the torque of the left and right wheels, a technique described in Patent Document 1 is known. According to this publication, the yaw moment to be applied to the vehicle is calculated based on the deviation between the target yaw rate and the actual yaw rate, and the drive wheel torque command value necessary to achieve this yaw moment is determined.

JP 2013-28329 A

  As a result of intensive studies by the present inventors, it has been found that the difference between the left and right driving wheel torques required to achieve the necessary yaw moment varies depending on the amount of load movement to the front wheels. For example, the difference between the left and right driving wheel torques that achieves the necessary yaw moment decreases as the amount of load movement to the front wheels increases. Therefore, when the driving wheel torque command value is determined by paying attention only to the deviation between the target yaw rate and the actual yaw rate, the yaw moment may increase excessively as the front wheel load movement amount increases.

  An object of the present invention is to provide a vehicle control device that can give a stable yaw moment even when load movement to the front wheels occurs.

  For this purpose, in the present invention, when generating the yaw moment in the vehicle by controlling the torque difference between the left and right wheels of at least one of the front and rear wheels, when calculating the yaw moment that achieves the yaw rate target value, The larger the amount of load movement to the front wheels, the smaller the yaw moment.

  Therefore, even if load movement occurs, it is possible to stably generate a yaw moment that should achieve the yaw rate target value.

1 is a configuration diagram of a braking / driving system in an electric vehicle according to a first embodiment. FIG. 3 is a control block diagram illustrating a control configuration in a driving force control unit according to the first embodiment. It is a block diagram showing cornering power fluctuation amount estimation of Example 1. FIG. It is a figure showing the structure of the acceleration / deceleration DYC control part of Example 1. FIG. FIG. 3 is a diagram illustrating a configuration of a steering response DYC control unit according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of an understeer suppression DYC control unit according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of a disturbance suppression DYC control unit according to the first embodiment. 6 is a time chart when the cornering power fluctuation due to the forward / backward load movement amount is corrected when the acceleration / deceleration DYC of the first embodiment is performed.

[Example 1]
FIG. 1 is a configuration diagram of a braking / driving system in the electric vehicle according to the first embodiment.
[Configuration of drive system]
The electric vehicle 1 is a rear-wheel drive vehicle, and includes left and right electric motors 3L and 3R that independently drive left and right rear wheels 2RL and 2RR that are drive wheels. The left and right electric motors 3L and 3R are three-phase AC motors. In the first embodiment, a so-called in-wheel motor system in which the left and right electric motors 3L and 3R are arranged on the unsprung side (wheel side) is adopted. Left and right inverters 4L and 4R are connected to the left and right electric motors 3L and 3R. The left and right inverters 4L and 4R are three-phase output inverters using two sets of IGBTs (Insulated Gate Bipolar Transistors) for each phase. A high voltage battery 5 is connected to the left and right inverters 4L and 4R. The left and right inverters 4L and 4R operate according to the gate signal from the driving force control unit 6, and cause the left and right electric motors 3L and 3R to perform power running or regenerative operation.

  The driving force control unit 6 calculates the required motor torque by referring to a preset torque map based on the accelerator opening and the rotation speeds (motor rotation speeds) of the left and right electric motors 3L and 3R, and calculates the calculated right wheel The left and right target powers to be supplied to the left and right electric motors 3L and 3R are calculated by multiplying the final torque command value and the left wheel final torque command value by the motor rotation speeds of the left and right electric motors 3L and 3R in each wheel. The driving force control unit 6 generates a gate signal in which the difference between the actual power supplied to the left and right electric motors 3L and 3R (for example, obtained from the actual voltage and the actual current) and the corresponding target power is zero. The left and right inverters 4L and 4R are driven.

[Configuration of braking system]
Wheel cylinders 7FL, 7FR, 7RL, 7RR (hereinafter collectively referred to as wheel cylinders 7) are provided for each wheel (left front wheel 2FL, right front wheel 2FR, left rear wheel 2RL, right rear wheel 2RR) of electric vehicle 1. ) Is provided. Each wheel cylinder 7 applies a friction braking torque to the corresponding wheel by the brake fluid supplied from the hydraulic pressure control unit 8. The hydraulic control unit 8 has a plurality of electromagnetic valves and motor pumps. The hydraulic pressure control unit 8 controls the opening / closing operation of the electromagnetic valve and the rotation speed of the motor pump based on the hydraulic pressure control command from the braking force control unit 9 and supplies the brake fluid to each wheel cylinder 7. The brake fluid supplied to each wheel cylinder 7 can be adjusted independently.

  The braking force control unit 9 includes a brake stroke sensor 10 that detects a brake pedal stroke that represents a driver's braking operation, a yaw rate sensor 12 that detects the yaw rate of the vehicle, and wheel speeds of the wheels 2FL, 2FR, 2RL, and 2RR. A wheel speed sensor 13 to detect, a vehicle speed sensor 14 to detect the vehicle speed from the wheel speed of each wheel 2FL, 2FR, 2RL, 2RR, a steering angle sensor 15 to detect a steering angle representing a steering wheel steering operation of the driver, And a master cylinder pressure sensor 16 for detecting the master cylinder pressure. When a stroke is detected by the brake stroke sensor 10, a required deceleration corresponding to the driver's braking operation is calculated to obtain a target braking torque for achieving the required deceleration.

  The braking force control unit 9 outputs the regenerative braking torque by the left and right electric motors 3L, 3R with priority over the target braking torque, and when the regenerative braking torque alone is insufficient, the shortage is compensated by the friction braking torque, so-called Regenerative cooperative control is performed. The braking force control unit 9 calculates the target regenerative braking torque with the regenerative limit torque determined by the motor speed (≈vehicle speed) and the battery SOC of the high voltage battery 5 as an upper limit, and outputs the target regenerative braking torque to the driving force control unit 6. During regenerative cooperative control, the driving force control unit 6 generates gate signals for the left and right inverters 4L and 4R so that the regenerative braking torque of the left and right electric motors 3L and 3R is half the target regenerative braking torque, respectively. Inverters 4L and 4R are driven. In addition, during regenerative cooperative control, the braking force control unit 9 calculates a target friction braking torque by subtracting the target regenerative braking torque from the target braking torque, obtains a hydraulic pressure control command to obtain the target friction braking torque, Output to the pressure control unit 8.

  In obtaining the hydraulic pressure control command, an appropriate vehicle behavior is achieved by controlling the brake distribution amount to the front wheels to a desired value. For example, when the target braking torque is less than a predetermined value, the target regenerative braking torque may be generated up to the maximum value, and the remaining braking torque may be set to the target friction braking torque on the front wheel side. In this case, since it is not necessary to perform switching control between the friction braking torque and the regenerative braking torque on the rear wheel side while recovering the maximum regenerative energy, the control is easy and the driver may feel uncomfortable. No. On the other hand, if the target braking torque is greater than or equal to a predetermined value, the amount of brake distribution to the front wheels is determined so that ideal braking force distribution is achieved, and braking is performed using both regenerative torque and friction braking torque on the rear wheel side. Also good. As described above, the brake distribution amount to the front wheels is appropriately changed according to the traveling state and the required braking torque. The braking force control unit 9 and the driving force control unit 6 communicate via CAN (Controller Area Network).

  The braking force control unit 9 performs anti-skid control, traction control, skid prevention control, inter-vehicle distance control, and the like as brake control for adjusting the wheel cylinder hydraulic pressure of each wheel cylinder 7 regardless of the driver's braking operation. In anti-skid control, the wheel cylinder hydraulic pressure of the wheel in which braking slip has occurred is reduced to suppress the locking tendency. Specifically, the pressure increase / decrease control is performed so that the vehicle body speed detected by the vehicle speed sensor 14 and the wheel speed of each wheel have a predetermined relationship. In the traction control, the wheel spin is suppressed by increasing the wheel cylinder hydraulic pressure of the left and right rear wheels 2RL and 2RR where the drive slip occurs. In the skid prevention control, the braking force of each wheel 2FL, 2FR, 2RL, 2RR is independently controlled, the actual yaw rate is brought close to the target yaw rate, and the side slip of the vehicle is reduced.

  FIG. 2 is a control block diagram illustrating a control configuration in the driving force control unit according to the first embodiment. The driving force control unit 6 includes a right wheel torque command value calculation unit 6a, a left wheel torque command value calculation unit 6b, and a DYC control unit 6c that controls the yaw moment of the vehicle according to the traveling state. The DYC control unit 6c includes a front and rear wheel cornering power fluctuation amount estimation unit 600 that estimates fluctuation amounts ΔKf and ΔKr of the front and rear wheel cornering powers Kf and Kr. In addition, various DYC control units 601 to 604 are provided that apply a yaw moment based on the traveling state of the vehicle and the steering state of the driver.

  The acceleration / deceleration DYC control unit 601 calculates an acceleration / deceleration DYC torque difference ΔT1 for applying a yaw moment that stabilizes the vehicle behavior in the acceleration / deceleration state of the vehicle. The steering response DYC control unit 602 calculates a steering response DYC torque difference ΔT2 for applying a yaw moment so as to achieve a target yaw rate transient characteristic of the vehicle with respect to the driver's steering. The understeer suppression DYC control unit 603 targets the steady yaw rate generated by the steering angle and the vehicle speed when it is assumed that there is no acceleration / deceleration, and the understeer suppression DYC torque for applying the yaw moment to achieve the steady yaw rate of the vehicle The difference ΔT3 is calculated. The disturbance suppression DYC control unit 604 estimates the yaw rate when there is no disturbance based on the steering angle, vehicle speed, etc., and applies the yaw moment so as to eliminate the deviation from the actual yaw rate detected by the yaw rate sensor 12. The disturbance suppression DYC torque difference ΔT4 is calculated.

  The torque limit value calculation unit 605 calculates a torque limit value based on a charge / discharge limit from the high-voltage battery 5 or a limit such as a rated torque. The DYC moment adjustment unit 605 calculates an adjustable torque difference that can be achieved based on the acceleration request level, the priority levels of the torque differences, and the torque limit value among the calculated torque differences ΔT1, ΔT2, ΔT3, and ΔT4. Calculate. The right wheel final torque calculator 607a adds and subtracts the adjusted torque difference from the right wheel torque command value to output a right wheel final torque command value Tright. The left wheel final torque calculator 607b adds and subtracts the adjusted torque difference from the left wheel torque command value Tleft to output a left wheel final torque command value.

FIG. 3 is a block diagram illustrating cornering power fluctuation amount estimation according to the first embodiment. 3A shows a control configuration of the cornering power fluctuation amount estimation unit 600, FIG. 3B shows a cornering resistance calculation map, and FIG. 3C shows a relationship between load movement and cornering power. As shown in FIG. 3A, the traveling resistance estimation unit 600a calculates a traveling resistance torque based on the steering angle, the wheel speed, and the vehicle body speed. The running resistance torque has the following relationship.
(Running resistance) = (Rolling resistance) + (Air resistance) + (Cornering resistance)
Here, the rolling resistance can be calculated by the product of the rolling resistance coefficient μ and the wheel load W. The air resistance can be calculated as a half of the product of the vehicle front projected area, the air density, the air resistance coefficient, and the square of the vehicle speed. The cornering resistance is calculated based on, for example, a cornering resistance calculation map shown in FIG. The cornering resistance increases as the vehicle speed increases, and the cornering resistance increases as the steering angle increases.

The torque command value adding unit 600b adds the right wheel torque command value calculated by the right wheel torque command value calculating unit 6a and the left wheel torque command value calculated by the left wheel torque command value calculating unit 6b to obtain a torque command value. The sum of is calculated. The brake torque calculation unit 600c calculates a brake torque that is a friction braking torque based on the master cylinder pressure detected by the master cylinder pressure sensor 16.
(Brake torque) = (Master cylinder pressure) x (Conversion coefficient)
The conversion coefficient is a predetermined value for converting from the master cylinder pressure to the brake torque. It is desirable to consider the response delay from the generation of the master cylinder pressure to the generation of the brake torque. For example, the estimation accuracy of the brake torque can be improved by filtering the master cylinder pressure with a filter having a predetermined time constant considering the response delay of the brake fluid and using the filter value.

The tire generation torque estimation unit 600d estimates the torque acting on the tire from the sum of the torque command values and the brake torque.
(Tire generated torque) = (sum of torque command values)-(brake torque)
The acceleration torque calculator 600e calculates the acceleration torque that is finally transmitted to the road surface by subtracting the running resistance from the tire generated torque.
(Acceleration torque) = (Tire generated torque)-(Running resistance)
The longitudinal acceleration calculation unit 600f calculates the longitudinal acceleration of the vehicle based on the acceleration torque.
(Vehicle longitudinal acceleration) = (Acceleration torque) / (Tire dynamic radius) / (Vehicle weight)
The vehicle load movement amount calculation unit 600g calculates the front and rear wheel load movement amount based on the vehicle longitudinal acceleration.
(Longitudinal load travel) = (Vehicle longitudinal acceleration) x (vehicle weight) x (center of gravity height) x (wheel base)

  The front and rear wheel cornering power fluctuation amount calculation unit 600h calculates the front and rear wheel cornering power fluctuation amounts ΔKf and ΔKr based on the front and rear load movement amount. FIG. 3C is a characteristic diagram showing the relationship between the front wheel cornering power and the load and the relationship between the rear wheel cornering power and the load. When the load moves to the front wheel side by deceleration from the initial load, the initial front wheel cornering power Kf increases and the initial rear wheel cornering power Kr decreases. The increase and decrease are calculated as cornering power fluctuation amounts ΔKf and ΔKr, and output to each DYC control unit.

[About acceleration / deceleration DYC]
FIG. 4 is a diagram illustrating the configuration of the acceleration / deceleration DYC control unit of the first embodiment. The steering yaw rate estimation unit 601a estimates the yaw rate generated by steering when there is no acceleration / deceleration (hereinafter referred to as steering yaw rate r1) based on the following relational expression.
m × V (dβ / dt + r1) =-2Kf [β + (Lf / V) r1-δf] -2Kr [β- (Lr / V) r1]
I _Z (dr1 / dt) =-2Kf [β + (Lf / V) r1−δf] Lf + 2Kr [β- (Lr / V) r1] Lr
here,
m: Vehicle weight
V: Vehicle speed δf: Steering angle β: Vehicle slip angle
r1: Steering yaw rate
Lf: Distance from vehicle center of gravity to front wheels
Lr: Distance from vehicle center of gravity to rear wheel
I _Z : Vehicle rotation inertia. The vehicle body slip angle β may be calculated by calculation from the steering angle δf, the vehicle body speed V, the yaw rate sensor value, etc., and if a separate lateral acceleration sensor is provided, it may be calculated based on various sensor values. Not limited.

The acceleration / deceleration yaw rate estimator 601b estimates the yaw rate during acceleration / deceleration (hereinafter referred to as acceleration / deceleration yaw rate r2) based on the cornering power fluctuation amounts ΔKf and ΔKr. If the front and rear wheel cornering power during acceleration / deceleration is Kf * and Kr *, the following relationship is established.
m × V (dβ / dt + r2) =-2Kf * [β + (Lf / V) r2-δf] -2Kr [β- (Lr / V) r2]
I _Z (dr2 / dt) =-2Kf * [β + (Lf / V) r2−δf] Lf + 2Kr * [β- (Lr / V) r2] Lr
Kf * = Kf + δKf
Kr * ＝ Kr ＋ δKr

The acceleration / deceleration steering yaw rate correction amount calculation unit 601c calculates a deviation between the steering yaw rate r1 and the acceleration / deceleration yaw rate r2, and calculates a yaw rate correction amount Δr *.
δr * ＝ r1−r2

The brake distribution corresponding yaw rate correction unit 601d corrects the yaw rate correction amount Δr * to be small according to the brake distribution amount to the front wheels, and calculates the corrected yaw rate correction amount Δr. FIG. 4B is a gain map showing the relationship of the correction gain x1 to the front wheel brake distribution. When the front wheel brake distribution increases, the front-rear tire force of the front wheels increases, so that the cornering power decreases even if the friction circle increases due to load movement. Therefore, by correcting the yaw rate correction amount Δr * to be small, an appropriate correction amount can be calculated regardless of the state of brake distribution to the front wheels.
δr = δr * × x1

In the moment calculation unit 601e, the vehicle moment M _Z that realizes the corrected yaw rate correction amount Δr * based on the corrected yaw rate correction amount δr, the steering angle δf, the vehicle body speed V, and the front and rear wheel cornering powers Kf and Kr. Is calculated by inverse calculation. Here, the following relational expression is obtained by substituting 0 as the steering angle δf and the corrected yaw rate correction amount δr as the yaw rate r into the relational expression used in the acceleration / deceleration yaw rate estimation unit 601b. As is clear from the following equation, the moment calculation unit 601e uses the front and rear wheel cornering powers Kf * and Kr * taking into account the cornering power fluctuation amounts δKf and δKr, and therefore changes according to the front and rear load movement amount. A vehicle moment M _Z taking into account the cornering power is calculated.
M _Z = {[1+ (2ζ / ω _n ) × s + (1 / ω _n ² ) × s ² ] / [A _G (1 + T _G × s)]} δr
A _G = (1 / ω _n ² ) × [2 (Kf * + Kr *) / (m × V × I _Z )]
T _G = m × V / [2 (Kf * + Kr *)]
ω _n = {[(4l ² × Kf * × Kr *) / (m × V ² × I _Z )] − 2 (Lf × Kf * −Lr × Kr *) / I _Z } ^1/2
ζ = {[m (Lf ² × Kf * + Lr ² × Kr *) + I _Z (Kf * + Kr *)] / (m × V × I _Z )} / {(4l ² × Kf * × Kr *) / ( m × V ² × I _Z ) −2 (Lf × Kf * −Lr × Kr *) / I _Z } ^1/2
s: Laplace operator

The front wheel brake distribution correspondence correction unit 601f largely corrects the vehicle moment M _Z according to the brake distribution amount to the front wheels, and calculates the corrected vehicle moment M _Z. FIG. 4C is a gain map showing the relationship of the correction gain x2 to the front wheel brake distribution. As the front wheel brake distribution increases, the front-rear tire force on the rear wheel side decreases and the rear wheel cornering power Kr increases. Therefore, it is possible to generate an appropriate yaw moment by correcting the vehicle moment M _Z to increase. .

In the left and right driving force difference calculation unit 601g, it calculates the acceleration and deceleration DYC lateral torque difference ΔT1 based on the calculated corrected vehicle moment M _Z. For example, when a moment is applied in the right turn direction, 1/2 (ΔT1) is subtracted from the right wheel torque command value Tright, and 1/2 (ΔT1) is added to the left wheel torque command value Tleft. As a result, a right turning moment can be applied without changing the overall torque.

[About steering response DYC]
FIG. 5 is a diagram illustrating the configuration of the steering response DYC control unit according to the first embodiment. Since 602d to 602g are substantially the same as 601d to 601g of acceleration / deceleration DYC, only different points will be described. The steering target yaw rate estimation unit 602a calculates the yaw rate transient characteristic of the vehicle targeted for steering. For example, it can be represented by a low-pass filter having a plurality of orders. The time constant is determined as a characteristic that can reduce the driver's uncomfortable feeling.
The steering yaw rate estimation unit 602b estimates the yaw rate generated by steering when there is no acceleration / deceleration.
m × V (dβ / dt + r1) =-2Kf [β + (Lf / V) r1-δf] -2Kr [β- (Lr / V) r1]
I _Z (dr1 / dt) =-2Kf [β + (Lf / V) r1−δf] Lf + 2Kr [β- (Lr / V) r1] Lr

The steering response yaw rate correction amount calculation unit 602c calculates a deviation between the steering target yaw rate r3 and the steering yaw rate r4, and calculates a yaw rate correction amount Δr *.
δr * ＝ r3−r4
As a result, the yaw rate correction amount δr * necessary for matching the yaw rate transient characteristic of the target vehicle with the actual steering yaw rate can be calculated. The yaw rate correction amount Δr * is subjected to front wheel brake distribution correspondence yaw rate correction, moment reverse calculation, and front wheel brake distribution correspondence correction to calculate a steering response DYC left-right torque difference ΔT2.

[Understeer suppression DYC]
FIG. 6 is a diagram illustrating the configuration of the understeer suppression DYC control unit according to the first embodiment. Since 603d to 603g are substantially the same as 601d to 601g of acceleration / deceleration DYC, only different points will be described. The steady target yaw rate calculation unit 602a calculates a yaw rate (hereinafter referred to as a steering yaw rate r1) generated by steering when there is no acceleration / deceleration based on the following relational expression.
m × V × r1 = -2Kf [β + (Lf / V) r1-δf] -2Kr [β- (Lr / V) r1]
2Kf [β + (Lf / V) r1-δf] Lf = 2Kr [β- (Lr / V) r1] Lr
The steady steering yaw rate estimation unit 603b estimates the current steady yaw rate r5 from the lateral acceleration and the vehicle body speed. The understeer characteristic mainly in the high lateral acceleration region is calculated based on the steady yaw rate map shown in FIG. The lateral acceleration may be estimated from the steering angle δf and the vehicle body speed V, or a lateral acceleration sensor may be separately provided, and is not particularly limited.

The steady steering yaw rate correction amount calculation unit 602c calculates the deviation between the steady target yaw rate r1 and the steady steering yaw rate r5, and calculates the yaw rate correction amount Δr *.
δr * ＝ r1−r5
As a result, the yaw rate correction amount δr * required to match the steady yaw rate characteristic of the vehicle targeted for steering with the actual steady steering yaw rate can be calculated. This yaw rate correction amount Δr * is subjected to front wheel brake distribution correspondence yaw rate correction, moment reverse calculation, and front wheel brake distribution correspondence correction, and an understeer suppression DYC left-right torque difference ΔT3 is calculated.

[Disturbance suppression DYC]
FIG. 7 is a diagram illustrating the configuration of the disturbance suppression DYC control unit according to the first embodiment. Since 604d to 604g are substantially the same as 601d to 601g of acceleration / deceleration DYC, only different points will be described. The yaw rate estimator 604a, a steering angle delta] f, the vehicle speed V, the cornering power variation amount δKf, δKr, from the vehicle moment M _Z, estimates the yaw rate r6 when disturbance is not.
m × V (dβ / dt + r6) =-2Kf * [β + (Lf / V) r6-δf] -2Kr * [β- (Lr / V) r6]
I _Z (dr6 / dt) =-2Kf * [β + (Lf / V) r6-δf] Lf + 2Kr * [β- (Lr / V) r6] Lr + M _{Z (n-1)}
Kf * = Kf + δKf
Kr * ＝ Kr ＋ δKr
Here, M _{Z (n−1)} is the vehicle moment M _Z calculated in the previous control cycle.
The disturbance suppression yaw rate correction amount calculation unit 604c calculates the deviation between the estimated yaw rate r6 and the actual yaw rate r detected by the yaw rate sensor 12, and calculates the yaw rate correction amount Δr *.
δr * = r6−r

(Cornering power fluctuation correction by front and rear load travel)
FIG. 8 is a time chart when the cornering power fluctuation due to the longitudinal load movement amount is corrected when the acceleration / deceleration DYC of the first embodiment is performed. FIG. 8A shows a time chart on the acceleration side, and FIG. 8B shows a time chart on the deceleration side. In addition, a dotted line in FIG. 8 represents a time chart in a case where correction accompanying cornering power fluctuation is not performed (hereinafter referred to as a comparative example). In FIG. 8, the side on which the steering angle increases in the positive direction is referred to as right steering, and the side on which the yaw rate increases in the positive direction is referred to as right turn.

(Operation on the acceleration side)
At time t1, the driver starts steering from the low-speed traveling state of the vehicle, and yaw rate is generated. At this time, the motor torque command value for the left and right wheels is 0, indicating a coasting state.
At time t2, the steering angle δf is in a steady state, and a steady yaw rate is generated.
When the driver depresses the accelerator pedal at time t3 to request acceleration, left and right wheel torque command values are output to the left and right electric motors 3L and 3R. At this time, load movement occurs on the rear wheel side with acceleration, the cornering power on the front wheel side decreases, and the cornering power on the rear wheel side increases, so that the vehicle acts in a stable direction. Therefore, the desired yaw rate cannot be generated as shown by the dotted line in FIG. In other words, the vehicle is more difficult to turn than the driver's steering intention. Therefore, an acceleration / deceleration DYC left-right torque difference ΔT1 corresponding to the cornering power fluctuation amounts ΔKf, ΔKr that varies depending on the load movement amount accompanying acceleration is given, and a yaw moment in the turning direction is generated in the vehicle. At this time, half of ΔT1 is added to the left wheel torque command value, and half of ΔT1 is subtracted from the right wheel torque command value. Therefore, there is no change in the total value of the left and right wheel torque command values. Thereby, even if acceleration occurs and the front and rear wheel cornering power fluctuates due to load movement, a stable turning state can be achieved.

(Operation on the deceleration side)
At time t11, the driver starts steering from the state where the vehicle is traveling at a constant speed, and yaw rate is generated.
At time t12, the steering angle δf is in a steady state, and a steady yaw rate is generated.
When the driver depresses the brake pedal at time t13 and a deceleration request is made, the left and right electric motors 3L and 3R output the left and right wheel torque command values as regenerative braking torque, and the wheel cylinders 7 according to the situation. Brake fluid is supplied and friction braking torque is generated. At this time, load movement occurs on the front wheel side as the vehicle decelerates, the cornering power on the rear wheel side decreases, and the cornering power on the front wheel side increases, so that the vehicle can easily turn. Therefore, as shown by the dotted line in FIG. 8B, the yaw rate is generated more than the desired yaw rate. In other words, the vehicle is easier to turn than the driver's steering intention. Therefore, an acceleration / deceleration DYC left-right torque difference ΔT1 corresponding to the cornering power fluctuation amounts ΔKf and ΔKr that varies depending on the load movement amount accompanying deceleration is given, and a yaw moment in the non-turning direction is generated in the vehicle. At this time, half of ΔT1 is added to the right wheel torque command value, and half of ΔT1 is subtracted from the left wheel torque command value. Thereby, even if deceleration occurs and the front and rear wheel cornering power fluctuates due to load movement, a stable turning state can be achieved.

  Similar to the acceleration / deceleration DYC, the steering response DYC, the understeer suppression DYC, and the disturbance suppression DYC can generate an appropriate yaw moment by correcting the yaw moment generated according to the amount of forward / backward load movement.

As described above, the effects listed below are obtained in the first embodiment.
(1) A vehicle control device provided with a DYC control unit 6c (yaw rate control means) for generating a yaw moment in the vehicle by controlling the torque difference between the left and right rear wheels (at least one of the front and rear wheels). When calculating the yaw moment for achieving the yaw rate target value, the DYC control unit 6c decreases the yaw moment as the load movement amount to the front wheels increases.
Therefore, even if load movement occurs, it is possible to stably generate a yaw moment that should achieve the yaw rate target value.

(2) The front and rear wheel cornering power fluctuation amount estimation unit 600 calculates the load movement amount to the front wheel based on the acceleration / deceleration torque command value for each wheel, and the front and rear wheel cornering based on the load movement amount to the front wheel. The power (tire lateral force characteristics) is calculated, and the moment calculation units 601e, 602e, 603e and 605e calculate the yaw moment based on the cornering power.
Therefore, since a calculation error accompanying a change in cornering power can be eliminated when calculating the yaw moment, a stable yaw moment can be generated.

(3) The DYC control unit 6c calculates the yaw rate correction amount δr * (yaw rate target value) for stabilizing the vehicle behavior in the acceleration / deceleration state of the vehicle in the acceleration / deceleration DYC control unit 601, and the steering response DYC control unit 602 The yaw rate correction amount δr * for achieving the target yaw rate transient characteristic for the driver's steering is calculated and the understeer suppression DYC control unit 603 assumes that there is no acceleration / deceleration, depending on the steering angle and vehicle speed. In order to eliminate the deviation from the actual yaw rate by calculating the yaw rate correction amount δr * for achieving the steady yaw rate of the vehicle with the target steady yaw rate generated, and estimating the yaw rate when there is no disturbance in the disturbance suppression DYC control unit 604 Yaw rate correction amount δr * is calculated, and the moment calculation units 601e, 602e, 603e, and 604e calculate each yaw rate by inverse calculation from each yaw rate correction amount δr *. Calculates a vehicle moment M _Z to achieve the correction amount [delta] r * (yaw moment), and controls the torque difference between the left and right wheels based on the yaw moment.
Therefore, when calculating the yaw moment in various controls, the torque difference between the left and right wheels is controlled based on each yaw moment in consideration of the influence of the load movement amount. it can.

  (4) The yaw rate correction amount δr * is decreased as the brake distribution to the front wheels increases. That is, when the front wheel brake distribution increases, the front-rear tire force of the front wheels increases, so that the cornering power decreases even if the friction circle increases due to load movement. Therefore, by reducing the yaw rate correction amount Δr * as the load movement amount increases, an appropriate correction amount can be calculated regardless of the brake distribution.

(5) The vehicle moment M _Z calculated from the yaw rate correction amount δr * is decreased as the brake distribution to the front wheels increases. When the front wheel braking-force distribution is increased, the longitudinal direction the tire force of the rear wheel side is decreased, because the rear wheel cornering power Kr is increased, by correcting such vehicle moment M _Z increases, proper regardless of the braking-force distribution Yaw moment can be generated.

  (6) The load movement amount is calculated based on the rolling resistance of the tire, the air resistance acting on the vehicle, and the cornering resistance generated during turning, and the load movement amount is calculated based on the traveling resistance. Therefore, the estimation accuracy of the load movement amount can be improved.

As described above, the description has been made based on the first embodiment. However, the present invention is not limited to the above-described embodiment but includes other configurations. In the first embodiment, the electric vehicle provided with the in-wheel motor on each of the rear wheels has been described. However, the front wheel may be provided with the in-wheel motor. Further, the present invention is not limited to the electric motor, and any configuration that can generate a torque difference between the left and right wheels may be used. In the first embodiment, a plurality of controls such as acceleration / deceleration DYC control, steering response DYC control, understeer suppression DYC control, disturbance suppression DYC control are processed in parallel, and various target yaw rates and estimated yaw rates or sensor detection yaw rates are processed as yaw rate target values. The yaw rate correction amount δr * which is a deviation from the above is calculated, and the yaw moment is calculated from the yaw rate correction amount δr *. On the other hand, it is not necessary to provide all the controls, and any one or more controls may be provided.

1 Electric vehicle
2 wheels
3R right electric motor
3L left electric motor
5 High voltage battery
6 Driving force control unit
7 Wheel cylinder
8 Hydraulic control unit
9 Braking force control unit
600 Front and rear wheel cornering power fluctuation estimation unit
606 DYC moment adjustment part

Claims (6)

In a vehicle control device including a yaw rate control means for generating a yaw moment in a vehicle by controlling a torque difference between at least one of the front and rear wheels,
The yaw rate control means, when calculating a yaw moment that achieves a yaw rate target value, reduces the yaw moment as the load movement amount to the front wheels increases. The vehicle control device according to claim 1,
The yaw rate control means calculates a load movement amount to the front wheel based on an acceleration / deceleration torque command value for each wheel, calculates tire lateral force characteristics of the front and rear wheels based on the load movement amount to the front wheel, and A vehicle control device that calculates a yaw moment based on tire lateral force characteristics. The vehicle control device according to claim 1 or 2,
The yaw rate control means includes:
A yaw rate target value for stabilizing the vehicle behavior in the acceleration / deceleration state of the vehicle,
The yaw rate target value to achieve the target vehicle yaw rate transient characteristic with respect to the driver's steering,
Targeting the steady yaw rate generated by the steering angle and vehicle speed when assuming no acceleration / deceleration, the yaw rate target value for achieving the steady yaw rate of the vehicle,
Estimate the yaw rate when there is no disturbance, the yaw rate target value to eliminate the deviation from the actual yaw rate,
Vehicle control, wherein a yaw moment that achieves each yaw rate target value is calculated by inverse calculation from each yaw rate target value, and a torque difference between left and right wheels is controlled based on each yaw moment apparatus. The vehicle control device according to any one of claims 1 to 3,
The vehicle control apparatus characterized in that the yaw rate target value is decreased as the brake distribution to the front wheels increases. The vehicle control device according to any one of claims 1 to 4,
The vehicle control apparatus characterized in that the yaw moment calculated from the yaw rate target value is reduced as the brake distribution to the front wheels increases. The vehicle control device according to any one of claims 1 to 5,
The load movement amount is calculated based on a rolling resistance of a tire, an air resistance acting on a vehicle, and a cornering resistance generated during turning, and a load movement amount is calculated based on the running resistance. A vehicle control device.

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