JP2009286159A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve turning performance by properly controlling yaw moment regardless of a friction coefficient μ of a road surface, replacement of tires, wear, and the like. <P>SOLUTION: Cornering powers Kf, Kr of front and rear wheels reflecting variations of each property of yaw angular speed γ and a vehicle body side slip angle β are calculated in real time, and a stability factor KH of the vehicle is calculated using the cornering power Kf, Kr. Thus, the stability factor reflects whether the vehicle state is in a low grip state such as low μ road traveling or in a high grip state such as high grip tire installation, and becomes a large value in a low grip state and a small value when in a high grip state. In addition, by subtracting a term including the stability factor KH to calculate a target yaw angular speed γref, the target yaw angular speed γref is appropriately set according to the vehicle state such as a road surface μ and tire wear, thereby improving turning performance by properly controlling yaw moment regardless of the differences between the vehicle states. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle control apparatus, and more particularly to a technique for improving the turning performance of a vehicle by appropriately controlling the yaw moment regardless of the friction coefficient μ of the road surface, tire replacement, wear, and the like. is there.

A vehicle control device is known that controls the yaw moment so that the actual yaw angular velocity γ follows the target yaw angular velocity γref when the vehicle is turning (see Patent Document 1). The target yaw angular velocity γref is obtained from, for example, the steering angle (steering angle) δ of the steering wheel, the vehicle speed V, the vehicle-specific stability factor, etc., and controls the driving force distribution ratio of the left and right wheels, and the driving force and braking force of each wheel. The yaw moment can be controlled by individually controlling the yaw moment.
JP-A-5-193387

  However, the stability factor is generally set in advance for each vehicle based on the standard tire, the standard road surface friction coefficient μ, etc., so the same regardless of changes in road surface conditions, tire replacement, wear, etc. In some cases, the target yaw angular velocity γref is set, and a sufficiently satisfactory turning performance cannot be obtained. For example, when the vehicle is understeered, the target yaw angular velocity γref is set to be larger than the actual yaw angular velocity γ. However, when the wheel grip force decreases due to low-μ road running on a snowy road or tire wear, and understeer, the high target yaw angular velocity γref is set and the yaw moment is increased. When it becomes large, the grip performance is low, so that the running performance during turning may be impaired. In addition, when the tire is replaced with a tire having a high grip force, excellent turning performance can be obtained. However, if the target yaw angular velocity γref determined with respect to the standard tire becomes smaller than the actual yaw angular velocity, There is a possibility that a moment is generated and the performance of the tire is not fully utilized.

  The present invention has been made against the background of the above circumstances, and the purpose of the present invention is to control the yaw moment regardless of changes in the vehicle condition related to the wheel grip force such as the friction coefficient μ of the road surface, tire replacement, and wear. The purpose of this is to improve the turning performance by appropriately controlling the vehicle.

  In order to achieve such an object, the first invention is a vehicle control apparatus for controlling a yaw moment so that an actual yaw angular velocity γ follows a target yaw angular velocity γref. Each characteristic of the yaw angular velocity γ and the vehicle body side slip angle β is provided. The vehicle state is determined based on the change of the vehicle, and the target yaw angle γref is set according to the vehicle state.

  According to a second aspect of the present invention, in the vehicle control device of the first aspect, when the characteristic of the yaw angular velocity γ decreases and the characteristic of the vehicle body side slip angle β increases, It is determined that the target yaw angular velocity γref is decreased.

  According to a third invention, in the vehicle control device of the first or second invention, when the characteristic of the yaw angular velocity γ increases and the characteristic of the vehicle body side slip angle β decreases, both the cornering powers of the front and rear wheels increase. The target yaw angular velocity γref is increased by determining the vehicle state.

  According to a fourth aspect of the present invention, in the vehicle control device according to any one of the first to third aspects, when both the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β increase or decrease both, It is determined that only one of the cornering powers is lowered, and the control of the yaw moment based on the target yaw angular velocity γref is prohibited.

According to a fifth aspect of the present invention, in the vehicle control device that controls the yaw moment so that the actual yaw angular velocity γ follows the target yaw angular velocity γref, the yaw angular velocity γ and the vehicle body side slip angle β that accompany changes in the vehicle state related to the grip force of the wheels. The cornering powers Kf [N / rad] and Kr [N / rad] of the front and rear wheels that reflect the change in the characteristics of the front and rear wheels are calculated according to the following equations (5) and (6), respectively. The vehicle stability factor KH [s ² / m ² ] is obtained according to (7), and the target yaw angular velocity γref [rad / s] is determined according to the following equation (8) using the stability factor KH: And

但し、ｍ：車両質量〔ｋｇ〕、Ｖ：車速〔ｍ／ｓ〕、β：車体横すべり角〔ｒａｄ〕、γ：ヨー角速度〔ｒａｄ／ｓ〕、Ｉ：車両のヨー慣性モーメント〔ｋｇｍ² 〕、Ｌｆ：前軸〜重心間距離〔ｍ〕、Ｌｒ：後軸〜重心間距離〔ｍ〕、Ｌ：ホイールベース（＝Ｌｆ＋Ｌｒ）〔ｍ〕、Ｍ：ヨーモーメント制御量〔Ｎｍ〕、δ：前輪操舵角〔ｒａｄ〕、ｇｙ：横加速度〔ｍ／ｓ² 〕

Where m: vehicle mass [kg], V: vehicle speed [m / s], β: vehicle body side slip angle [rad], γ: yaw angular velocity [rad / s], I: vehicle yaw inertia moment [kgm ² ], Lf: distance between front axis and center of gravity [m], Lr: distance between rear axis and center of gravity [m], L: wheel base (= Lf + Lr) [m], M: yaw moment control amount [Nm], δ: front wheel steering Angle [rad], gy: Lateral acceleration [m / s ² ]

  In such a vehicle control device, based on changes in the respective characteristics of the yaw angular velocity γ and the vehicle body side slip angle β, whether the vehicle is in a low grip state such as when traveling on a low μ road or during tire wear, In order to determine whether or not it is in a high grip state, etc., and set the target yaw angle γref according to the vehicle state, the target yaw angular velocity γref is appropriately set according to changes in road surface conditions, tire replacement, wear, etc. It is possible to improve the turning performance in such a vehicle state. For example, when the vehicle is understeered, the target yaw angular velocity γref is increased, and if it is a standard road surface, turning performance is improved and appropriate turning performance can be obtained. When the grip force decreases due to tire wear, etc., and the vehicle becomes understeered, the grip strength is suppressed by suppressing the increase in the target yaw angular velocity γref compared to the case where the vehicle becomes understeered under standard road conditions. It is possible to improve the turning performance by generating an appropriate yaw moment according to the vehicle. Also, when the turning performance is strong, the target yaw angular velocity γref is reduced to reduce the turning performance. However, in the case of a high grip state such as when a high grip tire is mounted, it is compared with a standard grip state such as a standard tire. Thus, by suppressing the decrease in the target yaw angular velocity γref, it is possible to ensure excellent turning performance utilizing the tire performance.

  In the second invention, when the characteristic of the yaw angular velocity γ decreases and the characteristic of the vehicle body side slip angle β increases, the vehicle state in which the cornering powers of the front and rear wheels both decrease, that is, low μ road running such as snow roads and tires It is judged that the grip force is low due to wear of the wearer, etc., and the target yaw angular velocity γref is reduced compared to the standard grip state, so an appropriate yaw moment corresponding to the grip force can be generated. This improves the turning performance.

  In the third invention, when the characteristic of the yaw angular velocity γ increases and the characteristic of the vehicle body side slip angle β decreases, the vehicle state in which the cornering powers of the front and rear wheels both increase, that is, the high grip state such as when the high grip tire is mounted. Since the target yaw angular velocity γref is increased as compared with the standard grip state of a standard tire or the like, excellent turning performance utilizing the performance of the tire can be obtained and the turning traveling performance is improved.

  In the fourth invention, when the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β both increase or decrease, the cornering power of only one of the front and rear wheels is reduced, that is, the cornering power is reduced. This tire is determined to be a temporary tire that does not provide sufficient gripping force, and the yaw moment control based on the target yaw angular velocity γref is prohibited. It is prevented from being damaged.

  The fifth invention calculates the cornering powers Kf and Kr of the front and rear wheels that reflect changes in the actual characteristics of the yaw angular velocity γ and the vehicle body side slip angle β accompanying changes in the vehicle state relating to the grip force of the wheels, respectively. In order to obtain the vehicle stability factor KH from Kf and Kr, the stability factor KH includes whether or not the vehicle is in a low grip state such as when driving on a low μ road or when the tire is worn, or in a high grip state where a high grip tire is attached. The vehicle state such as whether or not is reflected. Then, by determining the target yaw angular velocity γref using the stability factor KH, appropriate yaw moment control reflecting the grip state of the tire can be performed, which is the same as in the first to third inventions. The following effects can be obtained.

  The technical means for calculating the cornering powers Kf and Kr of the front and rear wheels reflecting changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β in the fifth invention are respectively the yaw angular velocity γ and the invention in the first to third inventions. This is substantially the same as determining the vehicle state based on changes in each characteristic of the vehicle body side slip angle β, and the fifth invention can be regarded as one embodiment of the first to third inventions.

The present invention relates to a two-wheel drive vehicle capable of controlling the yaw moment by controlling the driving force distribution ratio of the left and right wheels, controlling the steering angle, and controlling the driving force and braking force of the left and right wheels individually, The present invention can be applied to various vehicles such as a four-wheel drive vehicle. Specifically, for example
(a) A vehicle having an in-wheel motor, VSC (Vehicle Stability Control), or the like that can brake or drive one or both of the front and rear wheels independently.
(b) A vehicle having a left / right torque moving differential device that can move torque between the left and right wheels of one or both of the front and rear wheels, or a left / right driving force distribution device that can control the driving force distribution ratio of the left and right wheels.
(c) A vehicle having VGRS (Variable Gear Ratio Steering), active rear steering or the like that can independently control the steering angle of one or both of the front and rear wheels independently of the driver's steering operation.
It is preferably applied to.

  The yaw angular velocity γ and the vehicle body side slip angle β change depending on the vehicle speed V. The characteristic of the yaw angular velocity γ is a change property that changes depending on the vehicle speed V. The characteristic of the vehicle body side slip angle β is the vehicle speed V. It is a change characteristic that changes depending on And the characteristics of these yaw angular velocity γ and side slip angle β change depending on the change in cornering power of the front and rear wheels, which changes depending on the grip force of the wheels, such as low μ roads such as snowy roads, tire wear, etc. In the low grip state where the grip force has decreased, the cornering power of the front and rear wheels is reduced compared to the standard grip state, the characteristics of the yaw angular velocity γ are reduced (decreased), and the vehicle side slip angle β Therefore, it is possible to determine whether or not the grip state is low based on the change in these characteristics. In the case of a high grip state such as when a high grip tire is mounted, the cornering power of the front and rear wheels is increased compared to the case of the standard grip state, the characteristics of the yaw angular velocity γ are increased and the side slip angle β of the vehicle body is increased. Therefore, it is possible to determine whether or not the grip state is a high grip state based on a change in these characteristics.

  On the other hand, when temporary tires are installed on the front wheels, the cornering power is reduced only on the front wheels compared to the standard grip state, and the characteristics of the yaw angular velocity γ and the vehicle body slip angle β are both reduced (decreased). When temporary tires are installed on the wheels, the cornering power is reduced only on the rear wheels and the characteristics of the yaw angular velocity γ and the side slip angle β are both increased. It is possible to determine whether or not the temporary tire is mounted based on the change in. Appropriate yaw moment control cannot be expected when wearing such temporary tires, so if the yaw angular velocity γ and body slip angle β increase or decrease beyond a predetermined threshold (judgment value), temporary tires are installed. It is desirable to prohibit yaw moment control based on the time.

  In the second invention, when the characteristic of the yaw angular velocity γ decreases and the characteristic of the vehicle body side slip angle β increases, it is determined that the cornering power of the front and rear wheels is reduced, that is, the low grip state. The target yaw angular velocity γref is decreased as compared with the case, but the amount of decrease in the target yaw angular velocity γref can be changed according to the amount of change using the amount of change in the characteristics of the yaw angular velocity γ and the body slip angle β as parameters. The target yaw angular velocity γref may be decreased by a predetermined amount when changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β exceed a certain value. The front and rear wheel cornering powers Kf and Kr reflecting the changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β are calculated, and the cornering powers Kf and Kr are used as parameters to reduce the cornering powers Kf and Kr. The amount of decrease in the target yaw angular velocity γref may be increased as the value increases, or the target yaw angular velocity γref may be decreased by a predetermined amount when the amount of decrease in the cornering powers Kf and Kr exceeds a certain value. Various aspects are possible.

  In the third invention, when the characteristic of the yaw angular velocity γ increases and the characteristic of the vehicle body side slip angle β decreases, it is determined that the cornering power of the front and rear wheels is increased, that is, the high grip state. The target yaw angular velocity γref is increased compared to the standard grip state. The amount of increase in the target yaw angular velocity γref depends on the amount of change in the characteristics of the yaw angular velocity γ and the side slip angle β as parameters. The target yaw angular velocity γref may be increased by a predetermined amount when changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β exceed a certain value. The front and rear wheel cornering powers Kf and Kr reflecting the change in characteristics of the yaw angular velocity γ and the vehicle body side slip angle β are calculated, and the cornering powers Kf and Kr are used as parameters to increase the cornering powers Kf and Kr. As the value increases, the increase amount of the target yaw angular velocity γref may be increased, or the target yaw angular velocity γref may be increased by a predetermined fixed amount when the increase amounts of the cornering powers Kf and Kr exceed a certain value. Various aspects are possible.

  The decrease or increase in the target yaw angle γref based on the changes in the characteristics of the yaw angular velocity γ and vehicle side slip angle β as described above reflects changes in the characteristics of the yaw angular velocity γ and vehicle body slip angle β, and changes in those properties. It is desirable to constantly monitor changes in the cornering powers Kf and Kr of the front and rear wheels, and to perform in real time based on these changes. For example, when the target yaw angular velocity γref is determined by calculating the front and rear wheel cornering powers Kf and Kr as in the fifth invention, the cornering powers Kf and Kr are determined in real time at a predetermined cycle time during turning. It is only necessary to calculate the target yaw angular velocity γref sequentially based on the cornering powers Kf and Kr. However, each time a series of turnings in which the steering angle of the front wheels is greater than or equal to a predetermined value, the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β, or the values of the cornering powers Kf and Kr of the front and rear wheels that reflect changes in those characteristics. The vehicle state such as the low grip state, the high grip state, or the standard grip state is determined based on the above, and the correction amount of the target yaw angular velocity γref may be determined for each series of turns. Various modes are possible, such as determining the vehicle state at time intervals and updating the correction amount of the target yaw angular velocity γref.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram illustrating a vehicle drive device 10 to which the present invention is applied, and is for a four-wheel drive vehicle based on a front engine front wheel drive (FF). In FIG. 1, the output generated by the engine 12, which is the main power source, is output to the left front wheel 20L, right through the torque converter 13, the transmission 14, the front wheel differential gear device 16, and the left and right front wheel axles 18L, 18R. While being transmitted to the front wheel 20R, it is branched by the front wheel differential gear device 16, and the propeller shaft 22, the front and rear driving force distribution device 24, the shaft 25, the rear wheel differential gear device 26, and the right and left It is transmitted to the left rear wheel 30L and the right rear wheel 30R via the rear wheel axles 28L, 28R. Both the front wheel differential gear device 16 and the rear wheel differential gear device 26 are bevel gear differential gear devices. The front / rear driving force distribution device 24 is an electromagnetic multi-plate friction clutch or the like that can continuously change the transmission torque capacity including interruption of power transmission, and is arranged in series with the propeller shaft 22. The transmission torque capacity is controlled by the driving force distribution electronic control device 50, so that the driving force distribution ratio on the rear wheels 30L, 30R side with respect to the total driving force is adjusted to a predetermined value.

  An assisting electric motor 32 and a driving force unequal distribution mechanism 34 are arranged around the left rear axle 28L. The electric motor 32, the driving force unequal distribution mechanism 34, and the rear A driving force distribution device 36 is configured including the wheel differential gear device 26. The electric motor 32 can be driven to rotate in both forward and reverse directions, and its rotor is connected to a hollow shaft 52 integrally fixed to the differential case 26 i of the differential gear device 26 for the rear wheel via a one-way clutch 54. Connected. The one-way clutch 54 allows the differential case 26 i of the differential gear device 26 for the rear wheel to rotate at a speed higher than the rotational speed of the electric motor 32 during forward travel, and prevents the speed from dropping below the rotational speed of the electric motor 32. Is configured to do.

  The electric motor 32 is rotationally driven in the forward direction when the vehicle is started in the forward direction by the driving force distribution electronic control device 50, and includes the one-way clutch 54 and the rear wheel differential gear device 26. Thus, assist torque is applied to the left and right rear wheels 30L, 30R. FIGS. 2 and 3 both linearly connect the rotational speeds of the three rotating elements of the rear wheel differential gear device 26, that is, the differential case 26i as the first input member, and the left and right side gears as the output members. In the collinear chart, “L” at the left end represents the left side gear and further the left rear wheel 30L, “R” at the right end represents the right side gear and further the right rear wheel 30R, and the center “I” "Represents the differential case 26i, that is, the first input member. The distance between L and I is the same as the distance between R and I, and the torque input to the first input member I, that is, the differential case 26i, is evenly distributed to the left rear wheel 30L and the right rear wheel 30R.

  FIG. 2A shows a case where assist torque is applied to the left and right rear wheels 30L and 30R by the electric motor 32 when the vehicle starts moving in the forward direction, and is input to the differential case 26i via the one-way clutch 54. The motor torque Tm of the electric motor 32 is evenly distributed to the left and right rear wheels 30L and 30R, and an assist torque having a magnitude of Tm / 2 is applied. This state is an even distribution state in which the torque Tm of the electric motor 32 is evenly distributed to the left and right rear wheels 30L, 30R. The rear wheel differential gear device 26 receives the rear wheel side distribution torque Tin from the engine 12 through the front and rear driving force distribution device 24 at a predetermined front and rear driving force distribution ratio. The side distribution torque Tin is also distributed equally to the left and right rear wheels L and R. Accordingly, the torques TL and TR of the left rear wheel 30L and the right rear wheel 30R in this case are both (Tin + Tm) / 2.

  If the operation of the electric motor 32 is stopped when the predetermined traveling state is reached, the electric motor 32 is automatically disconnected from the rear wheel differential gear device 26 by the idle rotation of the one-way clutch 54. The left and right rear wheels 30L and 30R are rotationally driven only by the rear wheel side distribution torque Tin. FIG. 2B shows the state in which the torque assist by the electric motor 32 is thus completed, and the torques TL and TR of the left rear wheel 30L and the right rear wheel 30R at this time are both Tin / 2.

  Returning to FIG. 1, the drive force unequal distribution mechanism 34 includes a first pinion type first planetary gear unit 38 having a first sun gear S1, a first carrier C1, and a first ring gear R1, a second sun gear S2, And a single pinion type second planetary gear device 40 having a second carrier C2 and a second ring gear R2. The first planetary gear device 38 and the second planetary gear device 40 have the same gear ratio ρ (the number of teeth of the sun gear / the number of teeth of the ring gear), and the ring gears R1 and R2 are the common ring gear R. It is composed of. Since the ring gears R1 and R2 are configured by the common ring gear R in this way, the first planetary gear device 38 and the second planetary gear device 40 have five rotational elements that can rotate relative to each other, that is, the first sun gear S1. The first carrier C1, the ring gear R, the second carrier C2, and the second sun gear S2. The first sun gear S1 is integrally connected to the left rear axle 28L, the first carrier C1 is integrally fixed to the case 42 and cannot be rotated, the ring gear R is rotatable, and the second carrier C2 is rotatable. Is selectively connected to the rotor of the electric motor 32 via the clutch CL, and the second sun gear S2 is integrally connected to the hollow shaft 52. The second carrier C2 is an input member of the drive force unequal distribution mechanism 34 and corresponds to a second input member.

  2 and 3 are nomographic charts in which the rotational speed of each of the five rotating elements can be connected by a straight line for each pair of planetary gear units 38 and 40. These are shown together in the diagram, and are located in the order of the first sun gear S1, the first carrier C1, the ring gear R, the second carrier C2, and the second sun gear S2 from the left end, and are connected to the left rear wheel axle 28L. The first sun gear S1 is rotated integrally with “L” representing the left rear wheel 30L, and the second sun gear S2 connected to the hollow shaft 52 is matched with “I” representing the differential case 26i. It can be rotated integrally. These intervals are determined in accordance with the gear ratio ρ of the planetary gear units 38 and 40. In this embodiment, the gear ratio ρ of the planetary gear units 38 and 40 is equal, so that the ring gear R and the carriers C1 and C2 are separated from each other. The distance between the sun gear S1 and the carrier C1, and the distance between the sun gear S2 and the carrier C2 are also equal, while the distance between the ring gear R and the carriers C1 and C2, the sun gears S1 and S2, and the carriers C1 and C2. The ratio of the distance to is ρ: 1.

  The clutch CL is constituted by, for example, an electromagnetic clutch, and is connected and disconnected between the electric motor 32 and the second carrier C2 by being engaged and released by the driving force distribution electronic control device 50. Then, as shown in FIG. 2B, when the clutch CL is engaged during forward travel when the assist control is finished, and the electric motor 32 is driven to rotate in the forward direction, it is shown in FIG. Thus, the motor torque Tm in the positive direction (upward in the drawing) acts on the second carrier C2, and the torque of the right rear wheel 30R becomes TR = Tin / 2 + ρTm / (2 (1 + ρ)), and the torque TL of the left rear wheel 30L = Tin / 2−ρTm / (2 (1 + ρ)). That is, the forward torque increases by ρTm / (2 (1 + ρ)) at the right rear wheel 30R, while the forward torque decreases by ρTm / (2 (1 + ρ)) at the left rear wheel 30L. The right rear wheel 30R side is accelerated in accordance with a torque difference (TR−TL) = ρTm / (1 + ρ). This state is a first unequal distribution state in which the right rear wheel 30R side is accelerated based on the torque Tm of the electric motor 32.

  When the clutch CL is engaged and the electric motor 32 is rotationally driven in the reverse direction, the motor torque Tm in the reverse direction (downward in the figure) is applied to the second carrier C2 as shown in FIG. Acts, the torque of the left rear wheel 30L becomes TL = Tin / 2 + ρTm / (2 (1 + ρ)), and the torque of the right rear wheel 30R becomes TR = Tin / 2−ρTm / (2 (1 + ρ)). That is, while the forward torque is increased by ρTm / (2 (1 + ρ)) at the left rear wheel 30L, the forward torque is decreased by ρTm / (2 (1 + ρ)) at the right rear wheel 30R. The left rear wheel 30L side is accelerated according to the torque difference (TL-TR) = ρTm / (1 + ρ). This state is a second unequal distribution state in which the left rear wheel 30L side is accelerated based on the torque Tm of the electric motor 32.

  In other words, the driving force of the left and right rear wheels 30L and 30R can be unequally distributed by connecting the clutch CL during forward travel and rotating the electric motor 32 in the forward or reverse direction with a predetermined motor torque Tm. In the VSC control, cornering control, etc., the vehicle can be changed to a first unequal distribution state in which the right rear wheel 30R is accelerated or a second unequal distribution state in which the left rear wheel 30L is accelerated. The running stability and cornering performance can be improved. The driving force distribution device 36 can control both the driving force distribution ratio of the front and rear wheels and the driving force distribution ratio of the left and right wheels, and controls the yaw moment of the vehicle by controlling these driving force distribution ratios. be able to.

  When there is a difference in rotational speed between the left and right rear wheels 30L and 30R as shown in FIGS. 3A and 3B, the clutch CL is connected to the electric motor 32 in the reverse rotation direction, that is, ( In the case of (a), it is possible to apply a torque in the reverse direction (downward), and in the case of (b) in FIG. When the electric motor 32 is a motor generator capable of regenerative control, the electric motor 32 is regeneratively controlled to apply a braking torque, thereby restricting the rotation of the second carrier C2 to an unequal distribution state. You can also.

The driving force distribution electronic control unit 50 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU stores in the ROM in advance using a temporary storage function of the RAM. By performing signal processing according to the programmed program, the front / rear driving force distribution device 24 and the driving force distribution device 36 are controlled to control the front / rear wheel driving force distribution ratio and the left / right wheel driving force distribution ratio. As shown in FIG. 4, various signals necessary for such control are supplied. That is, an accelerator operation amount sensor 60 that detects an accelerator operation amount (accelerator opening) Acc that is operated by the driver in accordance with a required output amount, and an output shaft rotational speed N _OUT of the automatic transmission 14 that corresponds to the vehicle speed V. A vehicle speed sensor 62 to detect, a wheel speed sensor 64 to detect the speed (wheel speed) of each wheel 20L, 20R, 30L, 30R, a lateral acceleration sensor 66 to detect the actual lateral acceleration gy, and an actual yaw angular velocity γ A yaw angular velocity sensor 68 that detects an actual yaw angular acceleration, a steering angle sensor 72 that detects a steering angle (steering angle) δ of a steering wheel, a vehicle side slip angular velocity sensor 74 that detects a vehicle side slip angular velocity, A vehicle body side slip angle sensor 76 for detecting the side slip angle β is provided, and the accelerator operation amount Acc, Speed V (output shaft rotation speed N _OUT), the wheel speed, lateral acceleration gy, yaw angular velocity gamma, yaw angular acceleration, the steering angle [delta], the vehicle slip angular velocity signal representative of such vehicle body slip angle β are each driving force distribution electronics It is supplied to the control device 50. Each of the above sensors functions as a detecting means and may have a calculation function. For example, the yaw angular acceleration sensor 70 differentiates the yaw angular velocity γ detected by the yaw angular velocity sensor 68 to obtain the yaw angular acceleration. It may be what you want. The vehicle side slip angular velocity sensor 74 calculates the vehicle side slip angular velocity from the lateral acceleration sensor 66, the yaw angular velocity sensor 68, the lateral acceleration gy detected by the vehicle speed sensor 62, the yaw angular velocity γ, and the vehicle speed V according to a predetermined arithmetic expression. good. The vehicle body slip angle sensor 76 may integrate the vehicle body slip angular velocity detected or calculated by the vehicle body slip angular velocity sensor 74 to obtain the vehicle body slip angle β.

The drive force distribution electronic control device 50 is shown in the functional block diagram of FIG. 5 with respect to yaw moment control mainly performed for the drive force distribution ratio control of the left and right rear wheels 30L and 30R while the vehicle is turning. As described above, the apparatus includes a cornering power calculation means 80, a stability factor calculation means 82, a target yaw angular velocity calculation means 84, a yaw moment control means 86, and a yaw moment control availability determination means 88, and according to a predetermined arithmetic expression. The target yaw angular velocity γref is calculated to control the yaw moment. The meaning and unit of each symbol used in the following arithmetic expressions are as follows. FIG. 6 is a model diagram visually showing some of these symbols, taking the right front wheel 20R and the rear wheel 30R as an example.
m: Vehicle mass [kg]
V: Vehicle speed [m / s]
β: Side slip angle [rad]
βf: Front wheel side slip angle [rad]
βr: Rear wheel side slip angle [rad]
γ: Yaw angular velocity [rad / s]
Yf: Front wheel cornering force [N]
Yr: Rear wheel cornering force [N]
I: Vehicle yaw moment of inertia [kgm ² ]
Lf: Distance between front axis and center of gravity [m]
Lr: Distance between rear axis and center of gravity [m]
L: Wheel base (= Lf + Lr) [m]
M: Yaw moment control amount [Nm]
δ: Front wheel steering angle [rad]
KH: Stability factor [s ² / m ² ]
γref: target yaw angular velocity [rad / s]
gy: lateral acceleration [m / s ² ]

The cornering power calculation means 80 calculates the vehicle cornering power Kf [N / rad] and the rear wheel cornering power Kr [N / rad] according to the following equations (5) and (6), respectively. Calculate in real time with a predetermined cycle time. That is, since the following equations (1) to (4) are satisfied for a vehicle that is turning, the following equations (1) to (4) are used to eliminate Yf, Yr, βf, and βr from the equations (1) to (4). (5) and (6) are obtained.

  Here, the cornering powers Kf and Kr obtained in accordance with the above equations (5) and (6) are obtained using the yaw angular velocity γ and the vehicle body side slip angle β as parameters, and the wheels 20L, 20R, 30L, and 30R. Changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β accompanying the difference in the grip state are reflected. That is, the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β (change characteristics with respect to the vehicle speed V) depend on changes in the cornering powers Kf and Kr of the front and rear wheels that change depending on the grip force of the wheels 20L, 20R, 30L and 30R. When the grip power is reduced due to low μ roads such as snowy roads or tire wear, the cornering powers Kf and Kr of the front and rear wheels decrease when compared to the standard grip state. The characteristic of the yaw angular velocity γ decreases (decreases) and the characteristic of the vehicle body side slip angle β increases. In other words, when the characteristics of the yaw angular velocity γ decrease and the characteristics of the vehicle body slip angle β increase compared to the standard grip state, the cornering powers Kf and Kr of the front and rear wheels both decrease. Due to such changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β, or the changes in the cornering power Kf, Kr of the front and rear wheels, the grip state has decreased due to low μ roads such as snowy roads and tire wear. It can be judged that it is in a grip state.

  Specifically, FIG. 7 is a diagram showing specifications of each part, characteristics of the yaw angular velocity γ and the vehicle body slip angle β when turning on a road surface having a standard friction coefficient μ determined in advance when the standard tire is mounted. Thus, the graphs of the yaw angular velocity γ and the vehicle body side slip angle β shown in (b) and (c) are obtained from the equations (5) and (6) using the specifications shown in (a). Is obtained as a parameter. FIG. 8 assumes a low grip state in which the grip force is reduced due to low μ roads such as snow roads or tire wear, and lowers the cornering powers Kf and Kr of the front and rear wheels, respectively, as compared to the standard grip of FIG. In the same manner as in FIG. 7, using the specifications shown in (a), the characteristics of the yaw angular velocity γ and the vehicle body slip angle β can be obtained from the equations (5) and (6) using the vehicle speed V and the steering angle δ as parameters. It is what I have sought. As is apparent from the graphs of FIGS. 7 and 8 (b) and 8 (c), FIG. 8 in which the cornering powers Kf and Kr of the front and rear wheels are both reduced is compared with the standard grip of FIG. It can be seen that the characteristic of the vehicle body side slip angle β increases as the characteristic of the yaw angular velocity γ decreases.

  Further, when the cornering powers Kf and Kr of the front and rear wheels increase in a high grip state such as when a high grip tire is mounted, the characteristics of the yaw angular velocity γ increase and the vehicle side slip angle β increases. Decrease (decrease). In other words, when the characteristic of the yaw angular velocity γ increases and the characteristic of the vehicle body slip angle β decreases compared to the standard grip state, the cornering powers Kf and Kr of the front and rear wheels both increase. From such changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β, or the changes in the cornering powers Kf and Kr of the front and rear wheels, it can be determined that the vehicle state is a high grip state such as when a high grip tire is mounted.

  9 assumes a high grip state such as when a high grip tire is mounted, and the cornering powers Kf and Kr of the front and rear wheels are respectively increased as compared with the standard grip of FIG. ), The characteristics of the yaw angular velocity γ and the vehicle body slip angle β are obtained from the equations (5) and (6) using the vehicle speed V and the steering angle δ as parameters. As is apparent from the graphs (b) and (c) of FIGS. 7 and 9, FIG. 9 in which both the cornering powers Kf and Kr of the front and rear wheels are increased is compared with the standard grip of FIG. It can be seen that the characteristic of the vehicle body side slip angle β decreases as the characteristic of the yaw angular velocity γ increases.

  On the other hand, when temporary tires are mounted on the front wheels 20L and 20R, only the cornering power Kf of the front wheels is reduced as compared to the standard grip state, and the characteristics of the yaw angular velocity γ and the vehicle body slip angle β are both reduced (decreased). . Further, when temporary tires are mounted on the rear wheels 30L and 30R, only the cornering power Kr of the rear wheels is reduced as compared with the standard grip state, and the characteristics of the yaw angular velocity γ and the vehicle body slip angle β are both increased. In other words, when the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β are both reduced or increased as compared with the standard grip state, only one of the cornering powers Kf and Kr of the front and rear wheels is reduced. Based on such changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β, or the changes in the cornering powers Kf and Kr of the front and rear wheels, it is determined that the vehicle is in a state where temporary tires are mounted on either of the front and rear wheels. it can.

  FIG. 10 assumes a case where a temporary tire is mounted on either of the front wheels 20L and 20R, and shows a case where the cornering power Kf of the front wheel is reduced as compared with the case of the standard grip in FIG. ), The characteristics of the yaw angular velocity γ and the vehicle body slip angle β are obtained from the equations (5) and (6) using the vehicle speed V and the steering angle δ as parameters. As apparent from the graphs (b) and (c) of FIGS. 7 and 10, in FIG. 10 in which the cornering power Kf of the front wheels is lowered, the yaw angular velocity γ and the vehicle body are compared with those in the standard grip of FIG. It can be seen that the characteristics of the side slip angle β are all reduced.

  FIG. 11 shows a case where a temporary tire is mounted on either of the rear wheels 30L and 30R, and the cornering power Kr of the rear wheel is reduced as compared with the case of the standard grip in FIG. Similarly, using the specifications shown in (a), the characteristics of the yaw angular velocity γ and the vehicle slip angle β are obtained from the equations (5) and (6) using the vehicle speed V and the steering angle δ as parameters. As apparent from the graphs (b) and (c) of FIGS. 7 and 11, in FIG. 11 in which the cornering power Kr of the rear wheel is lowered, the yaw angular velocity γ and It can be seen that both the characteristics of the vehicle body side slip angle β increase.

Returning to FIG. 5, the stability factor calculation means 82 calculates the stability factor KH according to the following equation (7) using the cornering powers Kf and Kr, and the target yaw angular velocity calculation means 84 calculates the stability factor. The target yaw angular velocity γref is calculated according to the following equation (8) using KH. Then, the yaw moment control means 86 obtains the target yaw moment, that is, the driving force distribution ratio of the left and right wheels in accordance with the deviation so that the actual yaw angular velocity γ follows the target yaw angular velocity γref, and the driving force The driving force distribution device 36 is feedback-controlled according to the distribution ratio.

  In the above equation (7), since the product of the cornering powers Kf and Kr of the front and rear wheels is in the denominator, the cornering powers Kf and Kr of the front and rear wheels are both reduced compared to the standard grip state. In the low grip state, the denominator is reduced and the stability factor KH is increased, and the term KH, gy, V including the stability factor KH is subtracted in the equation (8). The yaw angular velocity γref is reduced. This suppresses an increase in the target yaw angular velocity γref so that the vehicle is forced to turn during low grip such as on a low μ road, thereby improving the turning performance such as improving the running stability during turning. In addition, the denominator of equation (7) becomes larger in the high grip state such as when wearing high grip tires where the cornering powers Kf and Kr of the front and rear wheels are both increased compared to the standard grip state. As the value of the factor KH decreases, the target yaw angular velocity γref obtained by subtracting the term KH · gy · V including the stability factor KH increases. This prevents the target yaw angular velocity γref from being reduced so as to hinder the turning performance due to the high grip when the high grip tire is installed, etc., and provides excellent turning performance utilizing the performance of the high grip tire. As a result, the turning performance is improved.

  On the other hand, the yaw moment control availability determination means 88 determines whether or not proper yaw moment control is possible based on the target yaw angular velocity γref calculated by the target yaw angular velocity calculation means 84. When a temporary tire is attached to one of the wheels, sufficient grip performance cannot be obtained, so appropriate yaw moment control cannot be expected depending on the target yaw angular velocity γref. In such cases, yaw moment control is not possible. Is prohibited. That is, when temporary tires are mounted on either of the front wheels 20L and 20R, only the cornering power Kf of the front wheels is reduced as compared with the standard grip state, and the characteristics of the yaw angular velocity γ and the vehicle body slip angle β are both reduced. On the other hand, when a temporary tire is mounted on either of the rear wheels 30L, 30R, only the cornering power Kr of the rear wheel is reduced as compared with the standard grip state, and the characteristics of the yaw angular velocity γ and the vehicle body slip angle β are both. If only one of the cornering powers Kf and Kr of the front and rear wheels decreases beyond a predetermined judgment value as compared with the standard grip, a vehicle having temporary tires attached to either of the front and rear wheels. The yaw moment is determined by the target yaw angular velocity γref calculated by the target yaw angular velocity calculating means 84. It is to prohibit the control of.

  FIG. 12 summarizes the yaw moment control according to the present embodiment for each case. The change in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β and the vehicle state estimated by the cornering powers Kf and Kr of the front and rear wheels are shown in FIG. FIG. 5 is a diagram showing a relationship with yaw moment control according to the vehicle state. In FIG. 12, in the case 1 in which the characteristic of the yaw angular velocity γ decreases and the characteristic of the vehicle body slip angle β increases as compared with the standard grip state, the cornering powers Kf and Kr of the front and rear wheels are both reduced. The target yaw angular velocity γref obtained according to the above equation (8) is reduced compared with the standard grip in order to prevent the vehicle from turning forcibly when the grip is low and can be judged as a low grip state such as road driving. In case 2 where the characteristic of the yaw angular velocity γ increases and the characteristic of the vehicle body side slip angle β decreases compared to the standard grip state, the cornering powers Kf and Kr of the front and rear wheels both increase. The target yaw angular velocity γref obtained according to the above equation (8) is made larger than that in the standard grip so that it can be determined that the grip state is high and the turning performance due to the high grip is prevented. Further, in case 3 in which the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β are both reduced as compared with the standard grip state, the front wheel 20L or 20R in which only the front wheel cornering power Kf is reduced can be determined as a temporary tire. In the case 4 in which the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β are both increased as compared with the grip state, the rear wheel 30L or 30R in which only the cornering power Kr of the rear wheel decreases can be determined as a temporary tire. In this case, yaw moment control is prohibited because appropriate yaw moment control cannot be expected.

  As described above, in the vehicle control apparatus of the present embodiment, the cornering power Kf of the front and rear wheels that reflects changes in the actual characteristics of the yaw angular velocity γ and the vehicle body side slip angle β accompanying changes in the vehicle state relating to the grip force of the wheels, Kr is calculated in real time according to the equations (5) and (6), respectively, and the vehicle stability factor KH is calculated according to the equation (7) using the cornering powers Kf and Kr. Reflects vehicle conditions such as whether the vehicle is in a low grip state such as when driving on low μ roads or when tires are worn, or whether the vehicle is in a high grip state with high grip tires attached. While the stability factor KH is larger than in the normal state, the stability factor is higher in the high grip state than in the standard grip state. It factors KH is reduced. Then, the target yaw angular velocity γref is calculated by subtracting the term KH · gy · V including the stability factor KH according to the equation (8), so that the vehicle condition such as a change in road surface μ, tire replacement, wear, etc. can be obtained. Accordingly, the target yaw angular velocity γref is appropriately set, and the yaw moment is controlled so that the actual yaw angular velocity γ follows the target yaw angular velocity γref. It is properly controlled to improve turning performance.

  Specifically, for example, when the vehicle is understeered, the target yaw angular velocity γref is increased, and if the road surface is in a standard condition, turning performance is improved and appropriate turning performance can be obtained. When the grip force decreases due to road driving, tire wear, etc., and understeer, the increase in the target yaw angular velocity γref should be suppressed compared to the case where the vehicle is understeered under standard road conditions. Thus, an appropriate yaw moment corresponding to the grip force is generated to improve the turning performance. That is, when the grip is low, the characteristics of the yaw angular velocity γ are decreased and the characteristics of the vehicle body slip angle β are increased as compared with the standard grip state, so that the cornering powers Kf and Kr of the front and rear wheels are both reduced. Since the stability factor KH is increased, the target yaw angular velocity γref is decreased accordingly, and the target yaw angular velocity γref is prevented from increasing forcibly so that the running stability during turning is improved.

  Also, when the turning performance is strong, the target yaw angular velocity γref is reduced to reduce the turning performance. However, in the case of a high grip state such as when a high grip tire is mounted, it is compared with a standard grip state such as a standard tire. Thus, by suppressing the decrease in the target yaw angular velocity γref, excellent turning performance utilizing the tire performance is ensured. That is, at the time of high grip, the characteristic of the yaw angular velocity γ increases and the characteristic of the vehicle body side slip angle β decreases as compared with the standard grip state, so that the cornering powers Kf and Kr of the front and rear wheels both increase. As the stability factor KH is reduced, the target yaw angular velocity γref is increased accordingly, and the target yaw angular velocity γref is reduced so as to inhibit the turning performance of the high grip when the grip is high such as when wearing a high grip tire. Is suppressed, and excellent turning performance utilizing the performance of the high grip tire can be obtained.

  Further, in this embodiment, when only one of the cornering powers Kf and Kr of the front and rear wheels is reduced by increasing or decreasing both the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β, It is determined that the tire with the reduced cornering power is a temporary tire and sufficient grip force cannot be obtained, and control of the yaw moment based on the target yaw angular velocity γref is prohibited. Control is performed to prevent the turning performance from being impaired.

  In the above-described embodiment, the cornering powers Kf and Kr of the front and rear wheels reflecting the changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β that change according to the vehicle state relating to the grip force of the wheels are expressed by the equations (5) and (6). The stability factor KH is calculated according to the equation (7), and the target yaw angular velocity γref is calculated according to the equation (8). The yaw angular velocity γ and the vehicle body slip angle β are calculated according to the case shown in FIG. The vehicle state may be determined from the change in characteristics, and the target yaw angular velocity γref may be corrected. That is, as shown in FIG. 13, the target yaw angular velocity calculation means 90 uses the stability factor KH in which a constant value is determined for each vehicle on the premise that the vehicle is running on a road having a standard friction coefficient μ with a standard tire, for example. While calculating the target yaw angular velocity γref in the same manner as described above, the vehicle state determination means 96 determines whether or not the characteristics of the actual yaw angular velocity γ and the vehicle body side slip angle β have changed compared to those in the standard grip state. If there is a change, the characteristics of the yaw angular velocity γ and the vehicle body slip angle β are changed using the determination criteria shown in FIG. ) To determine the vehicle state. Whether the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β have changed as compared with the standard grip state is determined by, for example, the yaw angular velocity γ and the vehicle body side slip angle β in the standard grip state as parameters of the vehicle speed V and the steering angle δ, respectively. The yaw angular velocity γ and the vehicle body side slip angle β at the time of the standard grip may be obtained from the current vehicle speed V and the steering angle δ and compared with the actual values.

  Then, a correction command is output to the target yaw angular velocity correction means 92 so as to change the target yaw angular velocity γref as shown in the column “treatment” in FIG. That is, in the case 1 in which the characteristic of the yaw angular velocity γ is decreased and the characteristic of the vehicle body slip angle β is increased as compared with the standard grip state, the cornering powers Kf and Kr of the front and rear wheels are both reduced. The target yaw angular velocity γref determined by the target yaw angular velocity calculating means 90 is reduced. In case 2 where the characteristic of the yaw angular velocity γ increases and the characteristic of the vehicle body slip angle β decreases compared to the case of the standard grip state, the cornering powers Kf and Kr of the front and rear wheels are both increased. And the target yaw angular velocity γref obtained by the target yaw angular velocity calculating means 90 is increased. In the case 3 in which the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β are both reduced as compared with the standard grip state, the front wheel 20L or 20R in which only the cornering power Kf of the front wheel is reduced is determined as a temporary tire. In case 4 in which the characteristics of the yaw angular velocity γ and the vehicle body slip angle β both increase compared to the standard grip state, the rear wheel 30L or 30R in which only the rear wheel cornering power Kr decreases is determined as a temporary tire. In this case, the target yaw angular velocity γref = 0 obtained by the target yaw angular velocity calculating means 90 is set so that the yaw moment control is prohibited because appropriate yaw moment control cannot be expected.

  Similarly to the yaw moment control means 86, the yaw moment control means 94 changes the actual yaw angular speed γ following the target yaw angular speed γref after being corrected by the target yaw angular speed correction means 92 as necessary. Thus, the target yaw moment, that is, the driving force distribution ratio of the left and right wheels is obtained according to these deviations, and the driving force distribution device 36 is feedback-controlled according to the driving force distribution ratio. Also in this case, substantially the same effect as the above-described embodiment can be obtained.

  As mentioned above, although the Example of this invention was described in detail based on drawing, these are one Embodiment to the last, This invention is implemented in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. be able to.

It is a schematic block diagram explaining the drive device for vehicles provided with the vehicle control apparatus of this invention. FIGS. 2A and 2B are collinear diagrams for explaining the operation of the driving force distribution device provided in the vehicle drive device of FIG. 1, in which FIG. 1A shows a state at the start assist time, and FIG. In the same collinear chart as FIG. 2, (a) shows a state where the torque of the right axle is increased, and (b) shows a state where the torque of the left axle is increased. It is a block diagram explaining the control system with which the drive device for vehicles of FIG. 1 is provided regarding drive force distribution control. FIG. 5 is a block diagram illustrating functions that the electronic controller for driving force distribution of FIG. 4 has regarding yaw moment control. FIG. 6 is a model diagram for explaining each symbol of an arithmetic expression used when the target yaw angular velocity is finally calculated by the cornering power calculating unit, the stability factor calculating unit, and the target yaw angular velocity calculating unit of FIG. 5. It is a figure which shows an example of the characteristic of each part in a standard grip state, and the characteristic of yaw angular velocity (gamma) and vehicle body side slip angle (beta). It is a figure which shows an example of the characteristic of each part at the time of the cornering power fall of a front-and-rear wheel, and the characteristic of yaw angular velocity (gamma) and vehicle body side slip angle (beta). It is a figure which shows an example of the characteristic of each part at the time of cornering power increase of a front-and-rear wheel, and the characteristic of yaw angular velocity (gamma) and vehicle body side slip angle (beta). It is a figure which shows an example of the characteristic of each part at the time of the cornering power fall of a front wheel, and the characteristic of yaw angular velocity (gamma) and vehicle body side slip angle (beta). It is a figure which shows an example of the characteristic of each part at the time of the cornering power fall of a rear wheel, and the characteristic of yaw angular velocity (gamma) and vehicle body side slip angle (beta). FIG. 5 is a diagram for explaining that a target yaw angular velocity is set according to vehicle states having different gripping forces, and is a vehicle estimated by changes in characteristics of yaw angular velocity γ and vehicle body side slip angle β and cornering powers Kf and Kr of front and rear wheels. It is a figure which shows the relationship between a state and the target yaw angular velocity set according to the vehicle state. It is a functional block diagram explaining the other Example of this invention.

Explanation of symbols

  36: Driving force distribution device 50: Electronic control device for driving force distribution 68: Yaw angular velocity sensor 76: Car body side slip angle sensor 80: Cornering power calculation means 82: Stability factor calculation means 84: Target yaw angular velocity calculation means 86, 94: Yaw moment control means 88: Yaw moment control availability determination means 90: Target yaw angular speed calculation means 92: Target yaw angular speed correction means 96: Vehicle state determination means γ: Yaw angular speed γref: Target yaw angular speed β: Body slip angle

Claims (5)

In the vehicle control device that controls the yaw moment so that the actual yaw angular velocity γ follows the target yaw angular velocity γref,
A vehicle control device that determines a vehicle state based on changes in characteristics of the yaw angular velocity γ and the vehicle body side slip angle β, and sets the target yaw angle γref according to the vehicle state. When the characteristic of the yaw angular velocity γ decreases and the characteristic of the vehicle body side slip angle β increases, it is determined that the vehicle state in which the cornering powers of the front and rear wheels are both reduced, and the target yaw angular velocity γref is reduced. The vehicle control device according to claim 1. When the characteristics of the yaw angular velocity γ increase and the characteristics of the vehicle body side slip angle β decrease, it is determined that the cornering power of the front and rear wheels has increased, and the target yaw angular velocity γref is increased. The vehicle control device according to claim 1 or 2. When the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β both increase or decrease, it is determined that the cornering power of only one of the front and rear wheels has decreased, and based on the target yaw angular velocity γref The vehicle control device according to any one of claims 1 to 3, wherein control of the yaw moment is prohibited. In the vehicle control device that controls the yaw moment so that the actual yaw angular velocity γ follows the target yaw angular velocity γref,
The cornering powers Kf [N / rad] and Kr [N / rad] of the front and rear wheels reflecting the changes in the characteristics of the yaw angular velocity γ and the vehicle body side slip angle β accompanying the change in the vehicle state with respect to the grip force of the wheels are respectively expressed by the following formulas: 5) The vehicle stability factor KH [s ² / m ² ] is calculated from the cornering powers Kf and Kr according to the following equation (7), and the stability factor KH is used to calculate the following equation: The target yaw angular velocity γref [rad / s] is determined according to (8).

Where m: vehicle mass [kg], V: vehicle speed [m / s], β: vehicle body side slip angle [rad], γ: yaw angular velocity [rad / s], I: vehicle yaw inertia moment [kgm ² ], Lf: distance between front axis and center of gravity [m], Lr: distance between rear axis and center of gravity [m], L: wheel base (= Lf + Lr) [m], M: yaw moment control amount [Nm], δ: front wheel steering Angle [rad], gy: Lateral acceleration [m / s ² ]
The vehicle control apparatus characterized by the above-mentioned.

Images