JP6519206B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a travel control device for a vehicle.

  Conventionally, a first step of applying a braking force to one of left and right wheels according to the vehicle behavior, and a second step of increasing the driving force of the other of the left and right wheels when the vehicle behavior is changed by the first step A vehicle behavior control device is known that performs the above (for example, Patent Document 1).

JP, 2010-215164, A

  In the above-mentioned prior art, changes in acceleration and speed of the vehicle tend to be large in the first step and the second step. Therefore, one of the problems of the present invention is, for example, by obtaining a travel control device of a vehicle in which changes in acceleration and speed of the vehicle are likely to be smaller when executing control to suppress understeer of the vehicle when turning the vehicle. is there.

The traveling control device for a vehicle according to the present invention turns when, for example, an understeer state of the vehicle is detected by the traveling state detection unit that detects that the traveling state of the vehicle is an understeer state, and the traveling state detection unit. The vehicle braking device is controlled so that a larger braking force is applied to the inner driving wheel than the turning outer driving wheel, and the vehicle associated with the control of the braking device is controlled on the driving wheel while the braking device is controlled. like the driving force to compensate for the reduction in the acceleration or speed is applied to control the drive of a vehicle, and a turning control section, the vehicle is Ru two-wheel drive vehicle der.
Further, in the travel control device for a vehicle according to the present invention, for example, a travel state detection unit that detects that the travel state of the vehicle is an understeer state, and the travel state detection unit detects the understeer state of the vehicle. Control the braking system of the vehicle so that a larger braking force is applied to the driving wheel inside the turning than the driving wheel outside the turning, and while controlling the braking device, the driving wheel controls the braking device And a turning control unit for controlling a drive device of the vehicle so as to apply a driving force that compensates for the decrease in acceleration or speed of the vehicle, the vehicle is a four-wheel drive vehicle, and the braking device is A braking force is applied to the inside front wheel and the inside rear wheel.
Further, in the travel control device for a vehicle according to the present invention, for example, a travel state detection unit that detects that the travel state of the vehicle is an understeer state, and the travel state detection unit detects the understeer state of the vehicle. Control the braking system of the vehicle so that a larger braking force is applied to the driving wheel inside the turning than the driving wheel outside the turning, and while controlling the braking device, the driving wheel controls the braking device The vehicle includes a turning control unit that controls the drive unit of the vehicle to apply a driving force that compensates for the decrease in acceleration or speed of the vehicle, and the acceleration operation unit is operated to accelerate the drive unit. Of the control of the braking device and the control of the driving device, the turning and traveling control unit can execute only the control of the braking device for a predetermined period of time in a state in which it is not operated. Predetermined time is set as the road surface friction coefficient is small short.

  Further, in the travel control device of the vehicle, for example, the turning travel control unit controls the braking device and performs the driving in a state where an acceleration operation unit that performs an operation for accelerating the driving device is operated. Execute control of the device.

  Further, in the travel control device of the above-mentioned vehicle, for example, while the acceleration operation unit in which the operation for accelerating the drive device is performed is operated, the control by the turning travel control unit is continued.

FIG. 1 is an exemplary and schematic configuration diagram of a vehicle equipped with the travel control device of the vehicle according to the embodiment. FIG. 2 is an exemplary block diagram of a travel control device of a vehicle according to the embodiment. FIG. 3 is a schematic explanatory view showing a braking force and a driving force at each wheel of a front wheel drive vehicle controlled by the travel control device of the vehicle of the embodiment. FIG. 4 is a schematic explanatory view showing the braking force and the driving force at each wheel of the four-wheel drive vehicle controlled by the travel control device of the vehicle of the embodiment. FIG. 5 is a graph showing an example of the correlation between the road surface friction coefficient and the braking force in the travel control device of the vehicle according to the embodiment. FIG. 6 is a graph showing an example of the correlation between the yaw rate deviation and the coefficient (K1) of the braking force in the travel control device of the vehicle according to the embodiment. FIG. 7 is a graph showing an example of the correlation between the operation amount of the acceleration operation unit and the coefficient (K2) of the braking force in the travel control device of the vehicle of the embodiment. FIG. 8 is a graph showing an example of the correlation between the steering angle and the coefficient (K3) of the braking force in the travel control device of the vehicle according to the embodiment. FIG. 9 is an exemplary flowchart showing a procedure of control by the travel control device of the vehicle of the embodiment. FIG. 10 is a graph showing an example of the correlation between the road surface friction coefficient and the duration of control in the travel control device of the vehicle according to the embodiment.

  In the following, exemplary embodiments of the present invention are disclosed. The configurations of the embodiments shown below, and the operations and results (effects) provided by the configurations are examples. The present invention can also be realized with configurations other than the configurations disclosed in the following embodiments. Further, according to the present invention, it is possible to obtain at least one of various effects (including derivative effects) obtained by the configuration.

<Configuration of traveling control device>
The vehicle 1 includes four wheels 2 in total: a front left wheel 2FL, a front right wheel 2FR, a rear left wheel 2RL, and a rear right wheel 2RR. The vehicle 1 is provided with a wheel cylinder 22 corresponding to each of the four wheels 2. The operation of the wheel cylinder 22 is controlled by the brake actuator 21. The brake actuator 21 applies hydraulic pressure to each of the wheel cylinders 22. The wheel cylinder 22 suppresses the rotation of a rotating member 23 such as a disk or a drum that rotates with the wheel 2 according to the applied hydraulic pressure. Thereby, the wheel 2 is braked. The brake actuator 21 is controlled by a brake ECU 10 (electronic control unit). The brake ECU 10 can control the braking force of each wheel 2 by outputting an electric signal (control signal) to the brake actuator 21. The brake ECU 10 is an example of a travel control device. The brake actuator 21, the wheel cylinder 22, the rotating member 23, and the like are examples of a brake device.

  In the vehicle 1 illustrated in FIG. 1, the front wheels 2FL and 2FR are driven by a drive source 3 such as an engine or a motor. In this case, the torque (driving force) of the drive source 3 is transmitted to the wheels 2FL and 2FR via the transmission 4, the shaft 5, a differential gear (not shown), and the like. The transmission 4 is a stepped or stepless transmission, and is, for example, an automatic transmission (AT), a continuously variable transmission (CVT), an automated manual transmission (AMT), a manual transmission (MT), or the like. The wheels 2 driven by the drive source 3 may also be referred to as drive wheels. Although FIG. 1 exemplifies a so-called front wheel drive vehicle in which the front wheels 2FL and 2FR are driven, the travel control device of the present invention is a vehicle having other drive wheels, such as a rear wheel drive vehicle The invention is also applicable to four-wheel drive vehicles. The drive source 3 is an example of a drive device.

  The drive source 3 is controlled by the drive ECU 11. For example, when the drive source 3 is an internal combustion engine, the drive ECU 11 is an engine ECU and controls an electronically controlled throttle valve operated by an electric signal (control signal), an electronically controlled fuel injection valve, etc. (not shown) Thus, the output torque of the drive source 3 and hence the drive force at the drive wheels are controlled. The drive ECU 11 can control the drive source 3 based on detection signals from at least one sensor 31, 32. For example, when the drive source 3 is a gasoline engine, the sensors 31 and 32 are an air flow meter, a throttle sensor, a rotation speed sensor, and the like.

  At least two of the four wheels 2 are steered in response to the rotation of the steering wheel 6. In the vehicle 1 illustrated in FIG. 1, the front wheels 2FL and 2FR are steered. In this case, the rotation of the steering wheel 6 is converted into the operation of the steered member 63 such as a rod or link via the power steering device 61 or the motion conversion mechanism 62 etc., and the wheel 2FL is operated according to the operation of the steered member 63. , 2FR are steered. The wheels 2 steered by the steering member 63 may also be referred to as steered wheels. Although a so-called front wheel steering vehicle is illustrated in FIG. 1, the travel control device of the present invention is also applicable to a vehicle having other steered wheels, such as a four-wheel steered vehicle. The steering amount (steering angle) based on the operation of the steering wheel 6 is detected by the steering angle sensor 33, and the actual turning amount (steering angle) of the steered wheels is detected by the turning amount sensor 34. The steering angle sensor 33 and the turning amount sensor 34 may be simply referred to as sensors 33 and 34.

  The vehicle 1 is provided with an accelerator sensor 35 for detecting the amount of operation of the acceleration operation unit 71 and a brake sensor 36 for detecting the amount of operation of the deceleration operation unit 72. The acceleration operation unit 71 is, for example, an accelerator pedal, the deceleration operation unit 72 is, for example, a brake pedal, and the acceleration sensor 35 and the brake sensor 36 are, for example, a stroke sensor or a position sensor. The accelerator sensor 35 and the brake sensor 36 may be simply referred to as sensors 35 and 36.

  Furthermore, in the vehicle 1, acceleration sensors 37 and 38 and a yaw rate sensor 39 are provided. The acceleration sensor 37 detects the acceleration in the longitudinal direction of the vehicle 1, the acceleration sensor 38 detects the acceleration in the width direction of the vehicle 1, and the yaw rate sensor 39 detects the angular velocity in the turning direction of the vehicle 1. The acceleration sensors 37 and 38 and the yaw rate sensor 39 may also be simply referred to as sensors 37, 38 and 39.

  Each wheel 2 is provided with a wheel speed sensor 40. Based on the detection result of the wheel speed sensor 40, the rotational speed of each wheel 2, the rotational acceleration, the speed of the vehicle 1, the movement distance of the vehicle 1, and the like are calculated. The wheel speed sensor 40 may be simply referred to as a sensor or the like.

  The brake ECU 10 illustrated in FIG. 2 includes a control element 110 and a storage unit 120. The control element 110 is, for example, a CPU (central processing unit) or the like, and the storage unit 120 is, for example, a random access memory (RAM), a read only memory (ROM), a flash memory, a solid state drive (SSD) or the like. is there. Further, the control element 110 includes a brake control unit 111, a turning travel control unit 112, a data transfer control unit 113, and the like. The control element 110 may include a skid control unit (not shown).

  The control element 110 can execute processing according to the installed and loaded program to realize each function. That is, by executing the process according to the program, the control element 110 can function as the brake control unit 111, the cornering control unit 112, the data transfer control unit 113, and the like. In this case, the program includes modules corresponding to the brake control unit 111, the turning travel control unit 112, the data transfer control unit 113, and the like. Further, the storage unit 120 stores a program, data corresponding to the detection result by the sensor, data used in arithmetic processing of each part, data of a result of arithmetic processing, and the like. The storage unit 120 may include a non-volatile rewritable storage unit. Note that at least a part of the functions of the above-described units may be realized by hardware.

  The brake control unit 111 controls the brake actuator 21. Further, the data transfer control unit 113 controls transfer of data (signal) between the brake ECU 10 and another ECU, for example, the drive ECU 11. Data exchange is performed via an interface unit such as a connector or a bus (not shown).

  The turning travel control unit 112 includes a start condition determination unit 112a, an end condition determination unit 112b, a braking force calculation unit 112c, a driving force calculation unit 112d, and the like. A condition satisfying the condition for starting control by the turning control unit 112 by, for example, comparing each parameter calculated based on detection values by the sensors 31 to 40 with a predetermined threshold value, for example. It is determined whether the The condition satisfying the condition for starting the control by the turning control unit 112 by comparing the predetermined threshold with each parameter calculated based on the detection value by the sensors 31 to 40, for example It is determined whether the The turning control unit 112 executes control (first control) to brake the vehicle 1 and, at the same time as the first control, driving power to compensate for the decrease in acceleration or speed of the vehicle 1 accompanying braking. Can be executed (second control) for applying the driving wheel to the drive wheel.

  The braking force calculation unit 112 c calculates the braking force applied to the drive wheel inside the turning in the control by the turning travel control unit 112. Further, the driving force calculation unit 112 d is an acceleration (speed of the vehicle 1) which is reduced by the braking force calculated by the braking force calculation unit 112 c being applied to the drive wheels inside the turning under the control of the turning control unit 112. Calculate the driving force that compensates). In addition, "compensation" here should just be compensation of the driving force of the magnitude | size 100% or less of damping | braking force. That is, the driving force may be increased by this compensation as compared with the case where the compensation is not performed. However, compensation over 100 percent is not performed.

  The turning control unit 112 can obtain or calculate the value of each parameter used in the turning control based on the detection results (detection values) of the sensors 31 to 40. Note that the turning travel control unit 112 is mounted as a part of the brake ECU 10 in the example of FIG. 2 and mounted on the same control element 110 as the brake control unit 111, but is not limited thereto. May be included in another ECU, or may be implemented as an element different from the brake control unit 111.

<Determination of braking force and driving force in cornering control (1)>
Here, referring to FIG. 3, in the travel control device of the present embodiment, the braking force applied to the drive wheel inside the turning and the driving force applied to the drive wheel in the control by the turning travel control unit 112 will be described. Do. First, the case where it is applied to the front wheel drive vehicle illustrated in FIG. 3 will be described. In FIG. 3, the longitudinal direction of the vehicle is the vertical direction of FIG. 3, the lateral direction of the vehicle is the lateral direction of FIG. 3, and the upper side of FIG. 3 is the front side of the vehicle 1. Here, first, the case where the vehicle 1 turns to the left as shown in FIG. 3 is exemplified.

ここに、Ｖ：車両速度、Ｓｔ：舵角、ｎ：ステアリングギヤ比、Ｌ：ホイールベース、Ｋｈ：スタビリティファクタである。 Turning control section 112, in order to suppress the understeer during turning of the vehicle 1, deviation Yr _d between the target yaw rate Yr _t and the actual yaw rate Yr _s is controlled to approach zero. Deviation Yr _d can be expressed by the following equation (1).

Here, V: vehicle speed, St: steering angle, n: steering gear ratio, L: wheel base, Kh: stability factor.

ここに、Ｉ：車両のヨー方向の慣性モーメント、Ｔ：トレッド、δ_ｆ：駆動輪の舵角、Ｌ_ｆ：重心位置Ｃｇから駆動輪（車輪２ＦＬ，２ＦＲ）までの車両前後方向の距離、である。制動力算出部１１２ｃは、式（１）および式（２）から、車両１の旋回の内側の駆動輪（車輪２ＦＬ）に加える制動力Ｆｂ_ｆを、算出することができる。旋回走行制御部１１２は、車両１の旋回の内側の駆動輪（車輪２ＦＬ）に、式（１）および式（２）から算出された制動力Ｆｂ_ｆが生じるよう、ブレーキアクチュエータ２１を制御する。これにより、車両１のアンダーステアが低減される。なお、旋回の内輪の制動力が外輪の制動力よりも、｜Ｆｂ_ｆ｜だけ大きい状態であれば、同様の結果が得られる。 Further, the turning of the vehicle 1, a braking force Fb _f applied to the inside of the drive wheels of the turning vehicle 1 (wheel 2FL), a deviation Yr _d of formula (1), the following equation (2) containing a The shown equation of motion holds.

Here, I: inertia moment in the yaw direction of the vehicle, T: tread, δ _f : steering angle of the drive wheel, L _f : distance in the vehicle longitudinal direction from the center of gravity Cg to the drive wheel (wheels 2FL, 2FR) is there. The braking force calculation unit 112c can calculate the braking force Fb _f to be applied to the drive wheel (wheel 2FL) inside the turning of the vehicle 1 from Expression (1) and Expression (2). The turning control unit 112 controls the brake actuator 21 so that the braking force Fb _f calculated from the equations (1) and (2) is generated on the drive wheel (wheel 2FL) inside the turning of the vehicle 1. Thereby, the understeer of the vehicle 1 is reduced. The same result can be obtained as long as the braking force of the turning inner ring is larger than the braking force of the outer ring by | Fb _f |.

ここに、α：係数である。係数αは、例えば１以下に設定される。旋回走行制御部１１２は、車両１の駆動輪（車輪２ＦＬ，２ＦＲ）に、式（３）で算出された駆動力ΔＦｄを追加する。駆動力ΔＦｄは、各駆動輪に分配される。なお、図３中のＦｄは、駆動力である。 Furthermore, the driving force calculation unit 112 d calculates a driving force ΔFd that compensates for the acceleration (velocity) of the vehicle 1 reduced with the braking force Fb _f according to the following equation (3).

Here, α is a coefficient. The coefficient α is set to, for example, 1 or less. The turning control unit 112 adds the driving force ΔFd calculated by equation (3) to the drive wheels (wheels 2FL and 2FR) of the vehicle 1. The driving force ΔFd is distributed to each driving wheel. Note that Fd in FIG. 3 is a driving force.

Further, although not shown, the same control can be performed when the front wheel drive vehicle 1 turns to the right. However, in this case, the braking force Fb _f calculated from the equation (1) and the equation (2) is applied to the front side and the right side wheel 2FR, and the driving force ΔFd calculated from the equation (3) is the front side wheel 2FL , 2FR is added.

ここに、Ｌ_ｒ：重心位置Ｃｇから駆動輪までの車両前後方向の距離である。なお、この場合にあっても、旋回の内輪の制動力が外輪の制動力よりも、｜Ｆｂ_ｒ｜だけ大きい状態であれば、同様の結果が得られる。 Further, although not shown, in the case of a rear wheel drive vehicle, the braking force calculation unit 112 c is an inner drive wheel of the turning of the vehicle 1 from the equation (1) and the equation (4) similar to the equation (2) it is possible to calculate the braking force Fb _r applied to the wheels 2RL or wheels 2RR).

Here, L _r is the distance between the center of gravity Cg and the drive wheel in the front-rear direction of the vehicle. Even in this case, similar results can be obtained as long as the braking force of the turning inner wheel is larger than the braking force of the outer wheel by | Fb _r |.

旋回走行制御部１１２は、車両１の駆動輪（車輪２ＲＬ，２ＲＲ）に、式（３）で算出された駆動力ΔＦｄを追加する。駆動力ΔＦｄは、各駆動輪に分配される。 The driving force calculating unit 112d is the driving force ΔFd to compensate for acceleration (velocity) of the vehicle 1 decreases along with the braking force Fb _r, is calculated by the following equation (5).

The turning control unit 112 adds the driving force ΔFd calculated by the equation (3) to the driving wheels (wheels 2RL and 2RR) of the vehicle 1. The driving force ΔFd is distributed to each driving wheel.

  Next, with reference to FIG. 4, when the vehicle 1 is a four-wheel drive vehicle, the braking force and the driving force applied in the control by the turning travel control unit 112 will be described. In FIG. 4, the longitudinal direction of the vehicle is the vertical direction of FIG. 4, the lateral direction of the vehicle is the lateral direction of FIG. 4, and the upper side of FIG. 4 is the front side of the vehicle 1. Here, first, the case where the vehicle 1 turns to the left as shown in FIG. 4 is exemplified.

ここに、ｍ：車両１の重量、Ｇ_ｘ：車両前後方向の車両１の加速度、Ｇ_ｙ：車幅方向の車両１の加速度、ｈ：車両１の重心の路面からの高さである。 The load movement amount ΔWx due to the pitch of the vehicle 1 and the load movement amount ΔWy due to the roll of the vehicle 1 can be expressed by the following equations (6) and (7).

Here, m: weight of the vehicle 1, G _x : acceleration of the vehicle 1 in the longitudinal direction of the vehicle, G _y : acceleration of the vehicle 1 in the vehicle width direction, h: height of the center of gravity of the vehicle 1 from the road surface.

The load W _{fl of} the wheel 2FL, the load W _{fr of} the wheel 2 FR, the load W _{rl of} the wheel 2 RL, and the load W _{rr of the} wheel 2 RR when the load movement amounts ΔWx and ΔWy occur while the vehicle 1 is turning have the following equations ( 8) to (11).

ここに、δ_ｆ：前側の駆動輪の舵角、δ_ｒ：後側の駆動輪の舵角、Ｌ_ｆ：重心位置Ｃｇから前側の駆動輪（車輪２ＦＬ，２ＦＲ）までの車両前後方向の距離、Ｌ_ｒ：重心位置Ｃｇから後側の駆動輪（車輪２ＲＬ，２ＲＲ）までの車両前後方向の距離、である。 Then, the turning of the vehicle 1 in this case, the inside of the drive wheels (wheels 2FL, 2RL) of turning of the vehicle 1 to the applied braking force _Fb f, and Fb _r, and deviation Yr _d of formula (1), the The equation of motion shown by the following equation (12) including is satisfied.

Where δ _f : steering angle of the front drive wheel, δ _r : steering angle of the rear drive wheel, L _f : distance in the vehicle longitudinal direction from the center of gravity position Cg to the front drive wheel (wheels 2FL, 2FR) , L _r : A distance in the vehicle longitudinal direction from the gravity center position Cg to the rear drive wheels (wheels 2RL, 2RR).

したがって、制動力算出部１１２ｃは、式（１）、式（１２）、および式（１３）から、車両１の旋回の内側の駆動輪（車輪２ＦＬ，２ＲＬ）に加える制動力Ｆｂ_ｆ，Ｆｂ_ｒを、算出することができる。旋回走行制御部１１２は、車両１の旋回の内側の駆動輪（車輪２ＦＬ，２ＲＬ）に、式（１）、式（１２）、および式（１３）から算出された制動力Ｆｂ_ｆ，Ｆｂ_ｒが生じるよう、ブレーキアクチュエータ２１を制御する。これにより、車両１のアンダーステアが低減される。また、四輪駆動の車両１が右方向に旋回する場合も同様に制御されうる。ただし、この場合は、車両１の旋回の内側の駆動輪（車輪２ＦＲ，２ＲＲ）に加える制動力Ｆｂ_ｆ，Ｆｂ_ｒの配分は、次の式（１４）により決定する。

そして、式（１）、式（１２）、および式（１４）によって算出された制動力Ｆｂ_ｆが前側かつ右側の車輪２ＦＲに加えられ、制動力Ｆｂ_ｒが後側かつ右側の車輪２ＲＲに加えられる。なお、この場合にあっても、旋回の内輪の制動力が外輪の制動力よりも、｜Ｆｂ_ｆ｜または｜Ｆｂ_ｒ｜だけ大きい状態であれば、同様の結果が得られる。 Here, inside of the drive wheels (wheels 2FL, 2RL) of turning of the vehicle 1 braking force _Fb f applied to the allocation of Fb _r, as in the following equation (13), the load acting on the front and rear of the drive wheels Determined by ratio.

Therefore, the braking force calculation unit 112c applies the braking forces Fb _f and Fb _{r to} the drive wheels (wheels 2FL and 2RL) inside the turning of the vehicle 1 from the equations (1), (12) and (13). Can be calculated. The turning control unit 112 causes the driving wheels (wheels 2FL and 2RL) on the inner side of turning of the vehicle 1 to obtain the braking forces Fb _f and Fb _r calculated from the expressions (1), (12) and (13). Control the brake actuator 21 so that Thereby, the understeer of the vehicle 1 is reduced. Also, the same control can be performed when the four-wheel drive vehicle 1 turns to the right. However, in this case, the inside of the drive wheels of the turning vehicle 1 (wheel 2FR, 2RR) braking force _Fb f applied to the allocation of Fb _r is determined by the following equation (14).

Then, equation (1), equation (12), and the braking force Fb _f calculated by Equation (14) is applied to the front and right wheels 2FR, in addition to the braking force Fb _r is rear and right wheel 2RR Be Even in this case, similar results can be obtained as long as the braking force of the turning inner wheel is larger than the braking force of the outer wheel by | Fb _f | or | Fb _r |.

ここに、α：係数である。係数αは、例えば１以下に設定される。
旋回走行制御部１１２は、車両１の駆動輪（車輪２ＦＬ，２ＦＲ，２ＲＬ，２ＲＲ）に、式（１５）で算出された駆動力ΔＦｄを追加する。駆動力ΔＦｄは、各駆動輪に分配される。なお、図４中のＦｄは、駆動力である。 Furthermore, the driving force calculating unit 112d is the driving force ΔFd for compensating the braking force _Fb f, Fb _r in association with Decreased vehicle 1 acceleration (velocity) is calculated by the following equation (15).

Here, α is a coefficient. The coefficient α is set to, for example, 1 or less.
The turning control unit 112 adds the driving force ΔFd calculated by the equation (15) to the driving wheels (wheels 2FL, 2FR, 2RL, 2RR) of the vehicle 1. The driving force ΔFd is distributed to each driving wheel. Note that Fd in FIG. 4 is a driving force.

<Determination of braking force and driving force in cornering control (2)>
Equation (1), (2), (4), from (12) or the like, the braking force _Fb f, Fb _r is the yaw rate and the deviation Yr _d of the steering angle [delta] _f, may vary depending on the [delta] _r, etc. I can understand. Further, the inventors conducted intensive studies, the braking force Fb _f, Fb _r is found and the friction coefficient of the road surface, the operation amount of the acceleration operation section 71, the speed of the vehicle 1, be changed even by the change speed of the steering angle doing. Therefore, the braking force calculating unit 112c, the braking force _Fb f, predetermined parameters and the braking force to change the size of the Fb _{r Fb} f, based on the correlation between the Fb _r, the braking force _Fb f, the Fb _r It can be calculated. The correlation is obtained in advance based on theoretical examination as described above, examination by experiments and simulations, etc., and is stored in the storage unit 120 as a function (numerical expression), map, table or the like. Also, the function (formula) may be stored in a program or may be incorporated in hardware as a logic operation circuit.

Specifically, in the case of a front wheel drive vehicle, the braking force calculation unit 112c can calculate the braking force Fb _{f according} to equation (16).
Fb _f = f (μ) × K1 × K2 × K3 (16)
Here, mu: road surface friction coefficient, f (μ): a function of road surface friction coefficient mu (Fig. 5), K1: coefficient corresponding to the yaw rate deviation Yr _d (FIG. 6), K2: operating amount of an acceleration operating section 71 As K3: a coefficient corresponding to the steering angle St (FIG. 8). Also in this case, the driving force calculation unit 112 d may calculate the driving force ΔFd that compensates for the acceleration (velocity) of the vehicle 1 reduced with the braking force Fb _f according to the above equations (3) and (5). it can. The characteristics (correlation) of the equation (16) and FIGS. 6 to 8 are merely examples, and the braking force Fb _f is not limited to these, and may be calculated based on other parameters, or the other. It may be calculated based on the characteristics (correlation) of Further, in the case of rear-wheel drive vehicle, the braking force Fb _r is calculated by the equation similar to equation (16), the above equation based on the braking force Fb _r (3), the braking force ΔFd by (5) It can be calculated. Further, in the case of a four-wheel drive vehicle, the total value of the braking forces for both the front and rear wheels is calculated by the same equation as equation (16), and the distribution shown in equations (13) and (15) braking force _Fb f, Fb _r is calculated, the braking force ΔFd can be calculated by equation (14). The road surface friction coefficient μ may be replaced by an acceleration in the vehicle width direction of the vehicle 1, or the road surface friction coefficient μ may be calculated based on the acceleration in the vehicle width direction of the vehicle 1. The coefficients K1, K2, and K3 may also be referred to as gains.

<Procedure of turning control>
Here, with reference to FIG. 9, an example of the procedure of the turning travel control will be described. At each time step, at least one of S1 to S4 in FIG. 9 is performed. First, the start condition determination unit 112a determines whether the start condition is satisfied based on the value of the parameter acquired or calculated by the turning travel control unit 112 (S1). If the start condition is not satisfied in S1 (No in S1), the turning travel control is not executed and ends. The start condition at S1 is set, for example, as follows.
_{[1-1] sgn (Yr t)} · Yr d ≧ Yth and [1-2] V ≧ Vth and [1-3] St ≧ Sth and [1-4] Bs ≦ Bth
Here, sgn (Yr _t) is the sign function, when the _{Yr t> 0 sgn (Yr t} ) = 1, Yr when the _{t = 0 sgn (Yr t)} = 0, Yr t < 0 when the sgn _(Yr t) = - 1. Further, Yth: threshold of the yaw rate deviation Yr _d, Vth: the threshold of the vehicle speed V, Sth: threshold of the steering angle St, Bs: operation amount of the reduction operation unit 72, Bth: the threshold of the manipulated variable Bs of deceleration operation unit 72 is there.

  Based on [1-1], it can be determined whether the vehicle 1 is in the understeer tendency. [1-1] is set so that the turning control of the present embodiment is started in a state where the vehicle 1 tends to understeer. The threshold Yth is set to, for example, a value close to 0 (zero). The code function sgn () takes into consideration that the sign of the yaw rate or the like changes depending on the turning direction. The start condition determination unit 112a is an example of a traveling state detection unit.

  Further, according to [1-2], for example, it is possible to exclude low speed traveling such as parking or leaving from the cornering control.

Further, for example, a state in which the steering angle St is small can be excluded from turning travel control by [1-3]. The steering angles δ _f and δ _{r of the} respective wheels 2 may be used instead of the steering angle St, or the speed (angular velocity) of the steering angle may be used.

  Further, due to the setting of [1-4], when the driver performs a braking operation, turning travel control is not executed. The cornering control unit 112 aims to reduce the understeer of the vehicle 1 when the vehicle 1 travels while turning, and when the driver tries to brake the vehicle 1, it is excluded from control. In addition, the inequality sign of said Formula [1-1]-[1-4] does not need to contain an equal sign. Moreover, each determination formula (inequalities) of the start conditions of turning traveling control is not limited to the example of said Formula [1-1]-[1-4]. Also, other conditions may be added, or some of the above conditions may be reduced.

  In the flow of FIG. 9, when the start condition of S1 is satisfied, that is, when the above [1-1] to [1-4] are all satisfied (Yes in S1), the braking force is applied to the drive wheel of the turning inner wheel. Is added (S2), and a driving force is applied to the drive wheels to compensate for the decrease in acceleration (velocity) of the vehicle 1 due to S3 (S3). The turning control unit 112 can execute S2 and S3 in parallel. The braking force and the driving force in S2 and S3 are determined by (1) and (2) of the determination of the braking force and the driving force in the turning control described above. S2 is an example of the first control, and S3 is an example of the second control.

After S3, the termination condition determination unit 112b determines whether the termination condition is satisfied based on the value of the parameter acquired or calculated by the turning travel control unit 112 (S4). If the termination condition is not satisfied in S4 (No in S4), the process returns to S2. The termination condition in S4 is set, for example, as follows.
_{[2-1] sgn (Yr t)} · Yr d ≦ 0 or [2-2] Bs> Bth or [2-3] As ≦ Ath and Kt ≧ Kth
Here, As: operation amount of the acceleration operation unit 71, Ath: threshold value of the operation amount As of the acceleration operation unit 71, Kt: continuation time from the start of cornering control, Kth: control time from the start of cornering control It is a threshold.

  Whether or not the vehicle 1 is in the oversteer tendency can be determined according to [2-1]. [2-1] is set so that the cornering control of the present embodiment is ended while the vehicle 1 is in the oversteer tendency.

  Further, due to the setting of [2-2], when the driver performs a braking operation, the cornering control is ended. The cornering control unit 112 aims to reduce the understeer of the vehicle 1 when the vehicle 1 travels while turning, and when the driver tries to brake the vehicle 1, it is excluded from control.

  Further, in the state where the operation of the acceleration operation unit 71 is being performed by [2-3], the turning travel control of the present embodiment is continued. As soon as the turning control is finished when the condition of [2-1] is satisfied, the vehicle 1 is in the understeering state again, and the understeering state and the turning control of the present embodiment are executed. A state in which the understeer tendency is eliminated occurs repetitively, and the change in acceleration of the vehicle 1 may be relatively large or the vehicle 1 may meander slightly. In this point, in the present embodiment, in the state where the operation of the acceleration operation unit 71 is performed according to [2-3], the turning travel control of the present embodiment is continued, and such an adverse phenomenon occurs. hard. The threshold Ath is set to, for example, a value close to 0 (zero).

  Further, in [2-3], even if the operation of the acceleration operation unit 71 is not performed, the continuation time Kt from the start of the turning control is equal to or more than the threshold value Kth (predetermined time) In the case of a short time, the turning travel control of the present embodiment is continued. The continuation time Kt is an elapsed time after the condition of S1 is satisfied. According to the inventors' intensive studies, the effect of the braking control (first control, S2) related to the traveling control of the present embodiment is effective even in the traveling state in which no driving force is generated on the wheel 2 It turns out. However, the purpose of the turning travel control according to the present embodiment is to reduce the understeer tendency of the vehicle 1 while the vehicle 1 is turning and also from the state where the operation of the acceleration operation unit 71 is not performed. When the operation of the acceleration operation unit 71 is started, the vehicle 1 may be slightly oversteered, which is not preferable. Therefore, by setting the continuation time Kt from the start of the turning control as shown in [2-3], the constant time (in the continuation time Kt) can be obtained when the operation of the acceleration operation unit 71 is not being performed. By performing the turning travel control of the present embodiment only for the threshold time Kth), the understeer tendency of the vehicle 1 is reduced even when the operation of the acceleration operation unit 71 is not performed. As a result, it is easy to suppress the vehicle 1 from falling into an unstable behavior with the start of the operation of the acceleration operation unit 71. The above-described S3 (FIG. 9, second control) is not essential for control in a state where the operation of the acceleration operation unit 71 described above is not performed. In addition, according to the setting of [2-3], the effect of the preliminary control before the control for preventing the side slip of the vehicle 1 is executed by the side slip prevention control device or the side slip control unit (not shown) mounted on the vehicle 1 May be obtained. As a result, the side slip prevention control may facilitate smooth transition, or the side slip prevention control may be more easily obtained. The threshold value Kth is an example of a predetermined time, and may also be referred to as a limit time, a set time, a time threshold, or the like.

  Furthermore, the threshold value Kth of the duration Kt of [2-3] may be set shorter as the road surface friction coefficient μ is lower, as illustrated in FIG. When the road surface friction coefficient μ is low, the behavior of the vehicle 1 is likely to be unstable due to the turning travel control of this embodiment. Therefore, by setting the threshold Kth of the duration Kt short according to the road surface friction coefficient μ, it is easy to suppress the behavior of the vehicle 1 from becoming more unstable. In addition, the inequality sign of said Formula [2-1]-[2-3] does not need to contain an equal sign. Moreover, each judgment formula (inequalities) of the start conditions of turning traveling control is not limited to the example of said Formula [2-1]-[2-3]. Also, other conditions may be added, or some of the above conditions may be reduced.

  When the end condition of S4 is satisfied, that is, when at least one of the above [2-1] to [2-3] is satisfied (Yes in S4), the turning travel control of the present embodiment is ended. . At the next time step, determination of the start condition of S1 is performed.

  As described above, in the present embodiment, when the traveling state of the vehicle 1 is the under-steer state, the turning travel control unit 112 applies a braking force larger than that of the turning outer driving wheel to the inner driving wheel of the turn. While controlling the brake actuator 21 (braking device) of the vehicle 1 so as to apply (first control, S2), while controlling the brake actuator 21, the driving wheel is controlled to accelerate or decelerate the acceleration or speed of the vehicle 1 The drive source 3 (drive device) of the vehicle 1 is controlled to apply a driving force that compensates for the reduction (second control, S3). Therefore, according to the present embodiment, the understeer state of the vehicle 1 is easily reduced. Further, according to the present embodiment, for example, it is possible to suppress the decrease in the acceleration or the speed of the vehicle 1 along with the braking control for reducing the understeer state. That is, according to the present embodiment, when performing control to suppress understeer of the vehicle 1 when the vehicle 1 is turning, changes in acceleration and speed of the vehicle 1 tend to be smaller.

  Moreover, in the present embodiment, in the state where the acceleration operation unit 71 is operated, the turning travel control unit 112 executes the first control (S2) and the second control (S3). That is, according to the present embodiment, it is possible to suppress the decrease in the acceleration or the speed of the vehicle 1 in the state where the acceleration operation unit 71 is operated. Therefore, for example, it is easy to obtain the behavior of the vehicle 1 corresponding to the operation of the acceleration operation unit 71 by the driver while reducing the understeer state of the vehicle 1. Further, for example, it is difficult for the behavior of the vehicle 1 not corresponding to the operation of the acceleration operation unit 71 of the driver to occur. In addition, for example, the behavior of the vehicle 1 that deviates from the behavior of the vehicle 1 assumed by the driver with respect to the operation of the acceleration operation unit 71 hardly occurs.

  Further, in the present embodiment, the control by the turning travel control unit 112 is continued while the acceleration operation unit 71 is operated. Therefore, according to the present embodiment, for example, the state of the understeer tendency and the state in which the cornering control of the present embodiment is executed and the understeer tendency is reduced occur repeatedly, and the change of the acceleration of the vehicle 1 is The disadvantage that the vehicle is relatively large or the vehicle 1 slightly meanders does not easily occur.

  Further, in the present embodiment, the turning and traveling control unit 112 performs the second control (S3) in a state where the acceleration operation unit 71 for performing an operation for accelerating the drive source 3 (drive device) is not operated. Only the first control (S2) can be executed in a state where the second control is not executed. Therefore, according to the present embodiment, for example, even when the acceleration operation unit 71 is not operated, the understeer state of the vehicle 1 is easily reduced.

  Further, in the present embodiment, the turning travel control unit 112 ends the first control (S2) when the threshold Kth (predetermined time) has elapsed since the start of the control, and the threshold Kth indicates the road surface friction. The smaller the coefficient μ, the shorter it is set. Thus, the vehicle 1 is less likely to be unstable.

  As mentioned above, although the embodiment of the present invention was illustrated, the above-mentioned embodiment is an example and it is not intended to limit the range of the present invention. The above embodiment can be implemented in other various forms, and various omissions, replacements, combinations, and changes can be made without departing from the scope of the invention. In addition, the specifications (structure, type, number, etc.) of each configuration, shape, etc. can be appropriately changed and implemented.

  Reference Signs List 1 vehicle 2 wheel 3 drive source (drive device) 10 brake ECU (travel control device) 21 brake actuator (braking device) 22 wheel cylinder (braking device) 23 rotating member (rotational member) Braking device), 71 ... acceleration operation unit, 112 ... turning travel control unit, 112a ... start condition determination unit (traveling condition detection unit).

Claims (5)

A traveling state detection unit that detects that the traveling state of the vehicle is understeered;
The braking device of the vehicle is controlled such that a braking force larger than that of the driving wheel on the outside is applied to the driving wheel on the inside of the turn when the understeer state of the vehicle is detected by the traveling state detection unit. A cornering control unit that controls a drive device of the vehicle such that a drive force that compensates for a decrease in acceleration or speed of the vehicle accompanying the control of the braking device is applied to the driving wheels while controlling the braking device;
Equipped with
The travel control device for a vehicle , wherein the vehicle is a two-wheel drive vehicle . A traveling state detection unit that detects that the traveling state of the vehicle is understeered;
The braking device of the vehicle is controlled such that a braking force larger than that of the driving wheel on the outside is applied to the driving wheel on the inside of the turn when the understeer state of the vehicle is detected by the traveling state detection unit. A cornering control unit that controls a drive device of the vehicle such that a drive force that compensates for a decrease in acceleration or speed of the vehicle accompanying the control of the braking device is applied to the driving wheels while controlling the braking device;
Equipped with
The vehicle is a four-wheel drive vehicle,
The travel control device for a vehicle, wherein the braking device applies a braking force to an inner front wheel of turning and an inner rear wheel of turning . A traveling state detection unit that detects that the traveling state of the vehicle is understeered;
The braking device of the vehicle is controlled such that a braking force larger than that of the driving wheel on the outside is applied to the driving wheel on the inside of the turn when the understeer state of the vehicle is detected by the traveling state detection unit. A cornering control unit that controls a drive device of the vehicle such that a drive force that compensates for a decrease in acceleration or speed of the vehicle accompanying the control of the braking device is applied to the driving wheels while controlling the braking device;
Equipped with
In a state in which the acceleration operation unit for performing the operation for accelerating the drive device is not operated, the turning travel control unit controls only the control of the braking device among the control of the braking device and the control of the drive device. It can be performed for a predetermined time,
The predetermined time, the road surface friction coefficient is set smaller short, vehicles running control device. In a state where the acceleration operation section operation for accelerating the drive is performed is operated, the turning control section executes control of the control and the drive of the braking device, according to claim 1 to 3 The travel control device for a vehicle according to any one of the above. The travel control device for a vehicle according to claim 4 , wherein control by the turning travel control unit is continued while an acceleration operation unit in which an operation for accelerating the drive device is performed is operated.

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