JP2009035047A - Turning behavior control method and device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately achieve a target yaw moment by excluding influence of a yaw moment due to same direction rolling displacement of right and left driving wheels caused by a braking/driving force difference between the right and left wheels for turning behavior control. <P>SOLUTION: Relation between a total yaw moment of a yaw moment directly applied to a vehicle by the braking/driving force difference between the right and left wheels (a braking/driving force moment) for the turning behavior control and the yaw moment by the rolling displacement of the right and left wheels caused by the braking/driving force difference between the right and left wheels (the braking/driving force moment), and the braking/driving force difference between the right and left wheels (the braking/driving force moment) is obtained. By applying the target yaw moment Mz to the total yaw moment on a horizontal axis by use thereof, a target braking/driving force moment (a target braking/driving force difference between the right and left wheels) necessary to achieve the target moment Mz is obtained, and braking/driving force instruction values of the right and left wheels are respectively obtained based thereon to contribute to the turning behavior control. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for controlling a turning behavior including a yawing motion of a vehicle to be a target behavior corresponding to a driving state, and an apparatus therefor.

As a technique for controlling the turning behavior of a vehicle, for example, a technique described in Patent Document 1 is known.
This turning behavior control technology is premised on a technology for controlling the turning behavior of the vehicle to be the target behavior by giving a yaw moment to the vehicle body by giving a driving force difference between the left and right drive wheels.

  By the way, in this kind of turning behavior control technology, when a driving force difference is given between the left and right driving wheels in the turning behavior control, these left and right driving wheels are caused by compliance steer around the kingpin axis (due to deformation of suspension elastic bushes, etc. The toe angle is changed by (steering), and the compliance steer around the kingpin axis gives a yaw moment to the vehicle body, causing a problem that the turning behavior of the vehicle deviates from the target behavior accordingly.

In order to solve this problem, Patent Literature 1 considers the amount of yaw moment change due to compliance steer around the kingpin axis when a driving force difference is given between the left and right drive wheels for turning behavior control, Proposals have been made to correct the driving force difference between the left and right driving wheels so that the turning behavior is not shifted from the target behavior.
According to this proposed technique, the influence on the turning behavior control by the compliance steer around the kingpin axis can be eliminated, and the turning behavior control of the vehicle can be brought close to the intended one.
JP 2005-354762 A

  However, as described above, in the turning behavior control of the vehicle to achieve the target behavior by providing a driving force difference or a braking force difference between the left and right wheels, the cause of shifting the turning behavior of the vehicle from the target behavior is as described above. In addition to compliance steer around the axis, the following things have also been confirmed to affect the turning behavior control of the vehicle.

  Here, a suspension device for suspending a wheel is considered. As suspension devices, there are typically an axle suspension type suspension device and an independent suspension type suspension device.

  In the former axle suspension type suspension device, knuckles to which left and right wheels are individually attached are connected to each other by a structure called a beam, and this structure (beam) is connected to the vehicle body via an elastic body. It is suspended from the vehicle body in a state where the left and right wheels are directly connected to each other.

  In the latter independent suspension type suspension device, a knuckle on which left and right wheels are individually rotatable is connected to a structure called a suspension member by a suspension arm and a suspension link so as to be swingable in the vertical direction. The structure (suspension member) is elastically supported on the vehicle body via an elastic body, whereby the left and right wheels are suspended from the vehicle body in a state of being indirectly connected to each other by the structure (suspension member).

In any of these types of suspension devices, if a braking / driving force difference is provided between the left and right wheels in the above-described turning behavior control, these left and right wheels are rotated around a common vertical axis (axis perpendicular to the road surface) between the two. As a result, a compliance steer for rolling displacement in the same direction in the left and right wheels is generated, in which both the rollers are displaced in the same direction against the supporting force of the above-mentioned elastic support.
The compliance steer for the rolling displacement in the same direction on the left and right wheels causes a change in tire slip angle between the left and right wheels and gives the vehicle body a yaw moment, which affects the behavior control due to the braking / driving force difference between the left and right wheels. This causes a problem of shifting the turning behavior of the vehicle from the target behavior.

In the conventional turning behavior control technology described in Patent Document 1, when driving force difference is applied between the left and right drive wheels for turning behavior control, the left and right drive is eliminated so as to eliminate the influence of compliance steer around the kingpin axis. In order to correct the wheel driving force difference, it is possible to eliminate the influence of compliance steer around the kingpin axis,
The effect of compliance steering on the rolling displacement in the same direction on the left and right wheels when a driving force difference is applied between the left and right drive wheels for turning behavior control cannot be excluded, and the turning behavior of the vehicle deviates from the target behavior accordingly. This causes the problem.

Furthermore, when the left and right wheels are rear wheels suspended by a rear suspension device, the yaw moment due to the compliance steering of the left and right wheels in the same direction rolling displacement is in a direction that hinders the yaw moment due to the left and right wheel driving force difference. ,
The sum of these two yaw moments acting on the vehicle may result in a yaw moment that is opposite to the direction of the yaw moment due to the difference in driving force between the left and right wheels. In this case, the target yaw moment (target turning behavior) is achieved. There will be a plurality of left and right wheel driving force differences, and it is necessary to select the most suitable left and right wheel driving force difference from these plurality of left and right wheel driving force differences. In this respect as well, the conventional turning behavior control technology described in Patent Document 1 cannot match the turning behavior of the vehicle with the target behavior.

  The present invention follows the type of turning behavior control in which the turning behavior of the vehicle approaches the target behavior due to the difference in braking / driving force between the left and right wheels. It is an object of the present invention to propose a vehicle turning behavior control technology that can match the turning behavior of a vehicle with a target behavior without being affected by compliance steer of rolling displacement.

For this purpose, the vehicle turning behavior control method according to the present invention is a combination of sequential processes as described in claim 1.
First, the vehicle as a premise is a vehicle in which at least one pair of left and right wheels are suspended by being correlated with each other so as to be able to roll and displace in the same direction against a resilient support force around a common vertical axis between these left and right wheels.
In controlling the turning behavior of the vehicle, a target yaw moment is applied to the vehicle body by giving a braking / driving force difference between the left and right wheels.

In controlling the turning behavior of the vehicle based on the difference between the braking / driving force between the left and right wheels,
Obtaining a yaw moment to be applied to the vehicle body along with the rolling displacement in the same direction of the left and right wheels caused by the difference in braking / driving force between the left and right wheels;
By sequentially combining with the step of determining the braking / driving force difference between the left and right wheels so as to achieve the target yaw moment while eliminating the influence of the yaw moment due to the rolling displacement of the left and right wheels thus determined, Turn behavior control shall be performed.

For the purpose described above, the vehicle turning behavior control apparatus according to the present invention has the following configuration as described in claim 3.
First, the vehicle as a premise suspends at least one pair of left and right wheels so as to be capable of rolling displacement in the same direction against a resilient force around a common vertical axis between the left and right wheels. A vehicle in which a target yaw moment is applied to the vehicle body by providing a braking / driving force difference therebetween.

The turning behavior control apparatus for a vehicle according to the present invention includes the following left and right wheel braking / driving force difference determining means and left and right wheel driving force difference providing means for the vehicle.
The former left / right wheel braking / driving force difference determining means includes a yaw moment applied to the vehicle body due to the left / right wheel rolling displacement resulting from the left / right wheel braking / driving force difference for turning behavior control, and left / right wheel braking / driving. From the correlation with the yaw moment due to the force difference, the braking / driving force difference between the left and right wheels at which the target yaw moment is achieved is determined.
The latter right / left wheel driving force difference applying means applies the braking / driving force difference thus determined between the left and right wheels.

According to the vehicle turning behavior control method of the present invention, the target yaw moment is eliminated while eliminating the influence of the yaw moment due to the same-direction rolling displacement of the left and right wheels caused by the difference in braking / driving force between the left and right wheels for turning behavior control. Therefore, the difference in braking / driving force between the left and right wheels is determined so as to achieve this, and this will contribute to the vehicle turning behavior control based on the difference in braking / driving force between the left and right wheels.
The yaw moment generated by the rolling displacement of the left and right wheels in the same direction due to the difference in braking / driving force between the left and right wheels for turning behavior control will not shift the turning behavior of the vehicle from the target behavior, and the turning behavior control is as intended. Can be.

According to the vehicle turning behavior control apparatus of the present invention, the yaw moment applied to the vehicle body in association with the rolling displacement of the left and right wheels caused by the difference in braking / driving force between the left and right wheels for turning behavior control, From the correlation with the yaw moment due to the left / right wheel braking / driving force difference, the left / right wheel braking / driving force difference at which the target yaw moment is achieved is determined.
The left and right wheels are controlled so that the yaw moment due to rolling displacement in the same direction of the left and right wheels does not affect the turning behavior control of the vehicle that matches the turning behavior of the vehicle to the target behavior due to the braking / driving force difference between the left and right wheels. The braking / driving force difference can be determined,
It is possible to perform the turning behavior control of the vehicle as intended while eliminating the influence of the yaw moment accompanying the former left and right wheels in the same direction rolling displacement.

Hereinafter, embodiments of the present invention will be described in detail based on the embodiments shown in the drawings.
FIG. 1 shows a vehicle to which a vehicle turning behavior control method and apparatus according to an embodiment of the present invention is applied. 1L is a left steering wheel (left front wheel), 1R is a right steering wheel (right front wheel), and 2L is left. Drive wheel (left rear wheel), 2R is right drive wheel (right rear wheel).

The left and right front wheels 1L and 1R are suspended on the vehicle body 4 so as to be able to move in the vertical direction by the individual front suspension devices 3L and 3R, and can be steered by the steering wheel 5 via the steering gear device 6.
The left and right rear wheels 2L, 2R are suspended on the vehicle body 4 so as to be able to move in the vertical direction by individual independent suspension rear suspension devices including suspension arms 7L, 7R and suspension links 8L, 8R. Suspension arms 7L, 7R and suspension links 8L, 2L, 2R knuckle (not shown) are connected to the corresponding ends (outer ends) of suspension arms 7L, 7R and suspension links 8L, 8R so that they can swing vertically. The other end (inner end) of 8R is connected to a common suspension member 9 so as to be swingable in the vertical direction, and the suspension member 9 is elastically supported on the vehicle body 4 via the elastic body 11 at its four even angles.

Thus, the left and right rear wheels 2L, 2R are suspended from the vehicle body 4 in a state of being indirectly connected to each other via the suspension member 9,
When the left and right rear wheels 2L and 2R are given a braking / driving force difference between them, for example, a braking / driving force moment represented by the product of the vector shown by the arrow in Fig. 2 and the tread b between the left and right wheels is generated. 4 around the common vertical axis (axis perpendicular to the road surface) between the left and right rear wheels 2L, 2R (the elastic center of the suspension member elastic support structure constituted by the four elastic bodies 11 of the suspension member 9). As shown in FIG. 2, it can roll and displace in the same direction as shown in FIG.

The suspension member 9 is further fitted with individual braking / driving motors 12L and 12R for the left and right rear wheels 2L and 2R. The left and right rear wheels 2L and 2R are connected to the suspension member 9 through the output shafts 13L and 13R by the motors 12L and 12R. The above-described left / right wheel braking / driving force difference can be applied as an individual drive or a regenerative braking.
In the present embodiment, the description has been given of the electric vehicle in which the rear two wheels are individually motor-driven by the motors 12L and 12R, respectively, and the braking / driving force difference can be provided between the rear two wheels, but is not limited thereto. If the vehicle can distribute the braking / driving force between the left and right wheels, regardless of whether it is the front wheel or the rear wheel, and the braking / driving force difference between the left and right wheels, it can be controlled by a common power source such as an internal combustion engine. The turning behavior control according to the present invention can be applied even to a vehicle that drives wheels.

In the embodiment of FIGS. 1 and 2, in order to individually brake and drive the left and right rear wheels 2L and 2R, the motors 12L and 12R can be controlled by the common controller 14 via the individual inverters 15L and 15R, This is why the controller 14
A signal from the steering angle sensor 16 for detecting the steering angle θ of the steering wheel 5,
A signal from an accelerator opening sensor 17 that detects an accelerator opening (accelerator pedal depression amount) APO that determines engine output,
A signal from the brake pedal depression force sensor 18 for detecting the brake pedal depression force BPO,
A signal from the vehicle speed sensor 19 for detecting the vehicle speed VSP;
A signal from the yaw rate sensor 21 for detecting the yaw rate γ acting on the vehicle body,
A signal from the longitudinal acceleration sensor 22 that detects the longitudinal acceleration Gx acting on the vehicle body,
A signal from the lateral acceleration sensor 23 for detecting the lateral acceleration Gy acting on the vehicle body is input.

  The controller 14 executes the control program shown in FIG. 3 based on the input information, and controls the left and right rear wheels 2L and 2R so that the turning behavior (yaw moment) of the vehicle becomes the target behavior. In addition to determining the driving force difference, individually determine the braking / driving force command values for the left and right rear wheels 2L and 2R to achieve the target braking force difference between the left and right wheels while maintaining the current running state, The braking / driving force command values of these left and right rear wheels 2L and 2R are commanded to the inverters 15L and 15R.

In step S1 of FIG. 3, the target braking / driving force Fd of the vehicle is obtained as follows.
First, from the accelerator opening APO, brake pedal depression force BPO, vehicle speed VSP, etc., the target longitudinal acceleration α required for the vehicle is calculated based on the driving force characteristics of the motors 12L and 12R and the braking force characteristics of the brake device. .
Next, the target braking / driving force Fd of the vehicle for realizing the target longitudinal acceleration α is obtained by correcting the target longitudinal acceleration α, the vehicle body mass Wj corrected by the rotational inertia of each part, and the running resistance Fross (rolling resistance, air resistance, It is obtained by calculation of the following equation based on (gradient resistance).
Fd ＝ Wi ・ α ＋ Fross (1)

In the next step S2, the yaw rate γ to be targeted is obtained from the steering angle θ and the vehicle speed VSP, and the target yaw moment Mz necessary for realizing the target yaw rate γ is calculated as the vehicle body inertia-inertia moment Iz and the differential calculation. It is calculated by the following formula based on the child (d / dt).
Mz ＝ Iz ・ (d / dt) γ (2)
In step S1 and step S2, it is preferable to set so that the target braking / driving force Fd and the target yaw moment Mz of the vehicle do not exceed values of the tire friction circle.

In step S3, in order to realize the target yaw moment Mz from the relationship between the braking / driving force difference between the left and right wheels, that is, the braking / driving force moment described above with reference to FIG. 2 and the total yaw moment applied to the vehicle. Obtain the required target braking / driving force moment (target braking force difference between left and right wheels).
The yaw moment applied to the vehicle by the braking / driving force moment (the difference in braking / driving force between the left and right wheels) includes the yaw moment directly applied to the vehicle body by the difference in braking / driving force between the left and right wheels, and the left and right rear wheels described above with reference to FIG. There is a yaw moment that is applied to the vehicle body as the tire slip angle changes due to the rolling displacement of 2L and 2R in the same direction, and the sum of these is applied to the vehicle by the braking / driving force moment (the difference in braking / driving force between the left and right wheels) Is the total yaw moment.

Since the former yaw moment is well known in turning behavior control based on the difference in braking / driving force between the left and right wheels, a detailed description thereof is omitted here, and the yaw moment caused by the rolling displacement in the same direction on the left and right wheels is described in detail below. Describe.
Since the longitudinal displacement of the left and right rear wheels 2L and 2R is uniquely determined from the longitudinal rigidity of the rear suspension system related to the left and right rear wheels 2L and 2R, when the braking / driving force is applied to the left and right rear wheels 2L and 2R, The relationship between the braking / driving force of the rear wheels 2L and 2R and the longitudinal displacement amount can be prepared in advance as a function or a map.

First, based on these functions and maps, the front and rear displacements D (Fx _RL) illustrated in FIG. 2 of the left and right rear wheels 2L and 2R from the braking / driving forces Fx _RL and Fx _RR to the left and right rear wheels 2L and 2R are illustrated. ), D (Fx _RR ).
Then, by calculating the following equation based on the front and rear displacements D (Fx _RL ) and D (Fx _RR ) of the left and right rear wheels 2L and 2R and the tread b between the left and right rear wheels 2L and 2R, FIG. The toe angle change amount ζ of the left and right rear wheels 2L, 2R illustrated is obtained.
ζ = sin ⁻¹ {[D (Fx _RR ) −D (Fx _RL )] / b}
≒ [D (Fx _RR ) −D (Fx _RL )] / b (3)

The lateral force change amount for one rear wheel is obtained by multiplying the toe angle change amount ζ of the left and right rear wheels 2L and 2R thus obtained by the equivalent cornering power Kij of the rear wheel.
Here, the equivalent cornering power Kij of the rear wheel is set to a constant value obtained in advance.
Then, by multiplying the lateral force change amount for the two rear wheels by the distance Lr between the center of gravity of the vehicle and the rear axle, the example illustrated in FIG. 2 is caused by the braking / driving force difference between the left and right rear wheels 2L, 2R. The yaw moment accompanying the directional rolling displacement can be obtained.

The sum of the yaw moment that accompanies the rolling displacement in the same direction due to the difference in braking / driving force between the left and right rear wheels 2L and 2R, and the yaw moment that is directly applied to the vehicle body due to the difference in braking / driving force between the left and right wheels, that is, The total yaw moment applied to the vehicle by the braking / driving force moment (the difference in braking / driving force between the left and right wheels) tends to be as shown by the solid line in FIG. 4, for example, relative to the braking / driving force moment (the difference in braking / driving force between the left and right wheels) Change with.
In FIG. 4, OS means oversteer, and US means understeer.

The broken line characteristic in Fig. 4 shows the change characteristic of the yaw moment directly applied to the vehicle body due to the difference in braking / driving force between the left and right wheels, and the characteristic that changes linearly with respect to the braking / driving force moment (difference in braking / driving force between the left and right wheels). is there.
On the other hand, the yaw moment caused by the rolling displacement in the same direction due to the braking / driving force difference between the left and right rear wheels 2L and 2R is directly applied to the vehicle body by the difference in braking / driving force between the left and right wheels (shown by broken lines). Therefore, the total yaw moment given to the vehicle by the braking / driving force moment (difference between the left and right wheels) is the sum of these yaw moments. As shown by the arrows, the yaw moment shown in the broken line directly applied to the vehicle body is as shown by the solid line in which the yaw moment generated by the rolling displacement in the same direction of the left and right rear wheels 2L and 2R is reduced.

Therefore, the total yaw moment applied to the vehicle by the braking / driving force moment (difference in braking / driving force between the left and right wheels) is obtained by the difference in braking / driving force between the left and right wheels, as seen in the hatched area in FIG. May be in the opposite direction to the yaw moment (shown in broken lines)
Although turning behavior control aiming at the oversteer tendency of vehicles is desired, turning behavior control in the understeer direction,
On the contrary, there is a case where the turning behavior control in the oversteer direction may be performed although the turning behavior control aiming at the understeer direction of the vehicle is desired.

If the horizontal and vertical axes in Fig. 4 are reversed, the relationship of braking / driving force moment (difference in braking / driving force between the left and right wheels) with respect to the total yaw moment as shown in Fig. 5 is obtained. By applying the target yaw moment Mz to the total yaw moment, the target braking / driving force moment (target braking / driving force difference between the left and right wheels) required to achieve the target yaw moment Mz is obtained.
Incidentally, if the target yaw moment Mz is as small as Mz1 on the horizontal axis in Fig. 5, multiple target braking / driving force moments (difference between the target braking / driving forces between the left and right wheels) required to achieve this are shown (3 in the figure). 1) If the target yaw moment Mz is as large as Mz2 on the horizontal axis in Fig. 5, the target braking / driving force moment (target braking / driving force difference between the left and right wheels) required to achieve this is one. Only.

  In step S4 of FIG. 3, whether or not there are a plurality of target braking / driving force moments (target braking / driving force difference between the left and right wheels) necessary for realizing the target yaw moment Mz obtained as described above in step S3. If there are a plurality, the control proceeds to step S5, step S6, and step S7 sequentially. If there are not a plurality (if there is only one), the control proceeds to step S7.

  In step S5, for each of a plurality of target braking / driving force moments (target braking / driving force difference between the left and right wheels), the left and right front wheels 1L, 1R and the left and right rear wheels 2L, In addition to estimating and calculating the 2R friction circle utilization rate as follows, the friction circle utilization rate (the maximum value of the friction circle utilization rate) of the wheel with the highest friction circle utilization rate for each of the two target braking / driving force moments (left and right) Friction circle utilization rate maximum value q1max, q2max, q3max due to wheel-to-wheel target braking / driving force difference).

First, the estimation calculation of the friction circle utilization factor related to each wheel will be described.
For this purpose, the load movement amount of each wheel is obtained from vehicle specifications such as vehicle mass and vehicle center of gravity, and longitudinal acceleration Gx and lateral acceleration Gy, and the initial wheel load of each wheel is adjusted by the load movement amount. , Wheel load Fzij of each wheel {i: F (front wheel) or R (rear wheel), j: R (right wheel) or L (left wheel), hereinafter i and j shall mean the same purpose} Is estimated.

Next, based on the map including the Ackermann characteristic representing the relationship between the steering angle θ and the turning angle, the turning angles δ _L and δ _R of the left and right front wheels 1L and 1R are obtained from the steering angle θ,
From the amount of suspension stroke that can be estimated based on the above-mentioned wheel load movement amount, based on a map that shows the relationship between the suspension stroke amount and the toe angle change amount, each wheel toe angle change amount Φ due to the suspension stroke amount Φ Search for
Thereafter, the vehicle body slip angle in each wheel is obtained from the vehicle speed VSP, the yaw rate γ, and the vehicle body slip angle βbody (estimated value).

The left and right front wheel turning angles δ _L and δ _R obtained as described above, the toe angle change amount Φ of each wheel, and the vehicle body slip angle in each wheel, and the left and right values obtained by the calculation of the expression (3) in step S3. From the toe angle change amount ζ of the rear wheels 2L and 2R, tire slip angles β _FL and β _FR of the left and right front wheels 1L and 1R and tire slip angles β _RL and β _RR of the left and right rear wheels 2L and 2R are respectively Calculate by calculation.
β _FL = β body + (L _F / V) γ + δ _L + φ _FL (4)
β _FR = βbody + (L _F / V) γ + δ _R + φ _FR (5)
β _RL = βbody− (L _R / V) γ + φ _RL + ζ (6)
β _RR = βbody− (L _R / V) γ + φ _RR + ζ (7)

Then, the cornering power of each wheel is estimated from each estimated wheel load Fz and each wheel longitudinal force Fx (previously calculated braking / driving force value).
Here, when the load dependence of the cornering power is approximated by a quadratic function, the cornering power Kij {i: front wheel or rear wheel, j: right wheel or left wheel} of each wheel is a constant determined by the tire, a1 and a2. If the estimated value of the road surface friction coefficient is μ, it can be estimated and calculated by the following equation.
Kij = (a1 · Fzij ² + a2 · Fzij) × {1− (Fxij / [μ · Fzij]) ² } ^1/2 (8)

Based on the tire slip angle βij of each wheel and the cornering power Kij of each wheel determined as described above, the lateral force Fy is calculated as follows.
That is, the non-linear characteristic of the lateral force Fy with respect to the tire slip angle βij can be approximated by a quadratic function, and the lateral force Fy can be estimated by the following equation.
Fyij = Kij · βij− (Kij ² / [4μ · Fzij]) βij ² (9)

Next, the frictional circle utilization factor qij of each wheel is calculated from the following formula using the longitudinal force Fx (previously calculated braking / driving force value) of each wheel, lateral force Fy, vertical load Fz, and road surface friction coefficient μ. Estimate (%).
qij = {(Fxij ² + Fyij ₂ ) ⁻² / (μ · Fzij)} × 100 (10)
The friction circle utilization ratio qij (%) of each wheel is the friction circle of each of the four wheels when multiple target braking / driving force moments (target braking / driving force difference between the left and right wheels) are applied between the left and right rear wheels 2L, 2R. Utilization rate
Friction circle utilization rate (maximum friction circle utilization rate) of the wheel with the highest friction circle utilization rate in each case, and maximum friction circle utilization rate q1max by multiple target braking / driving force moments (target braking / driving force difference between left and right wheels) , Q2max, q3max (maximum friction circle utilization rate corresponding to the three target braking / driving force moments when Mz = Mz1 in Fig. 5).

In the next step S6, the smallest q1max, q2max, or q2max of the friction circle utilization rates q1max, q2max, and q3max when a plurality of target braking / driving force moments (target braking / driving force difference between the left and right wheels) is applied, Alternatively, the target braking / driving force moment (target braking / driving force difference between the left and right wheels) corresponding to q3max is selected.
If there are several smallest friction circle utilization ratios q1max, q2max, and q3max, select the target braking / driving force moment (target braking / driving force difference between the left and right wheels) related to any of these. Also good.

In the next step S7, the braking / driving force command values for the left and right rear wheels 2L and 2R are obtained from the target braking / driving force moment (target braking / driving force difference between the left and right wheels) selected in step S6 and the vehicle longitudinal acceleration target value. To the corresponding inverters 15L and 15R.
In determining the braking / driving force command values for the left and right rear wheels 2L, 2R, first, the target braking / driving force difference between the left and right wheels is determined from the target braking / driving force moment, and then the left and right rear wheels 2L, The total braking / driving force of 2R can be obtained, and the braking / driving force command values for the left and right rear wheels 2L, 2R can be obtained individually from the target braking / driving force difference between the left and right wheels and the total braking / driving force of the left and right rear wheels 2L, 2R. it can.

  If it is not determined in step S4 that there are not a plurality of target braking / driving force moments (target braking / driving force difference between the left and right wheels) for realizing the target yaw moment (Mz), the target braking / driving force moment (target braking between the left and right wheels) Since there is only one driving force difference) and the selection as described above is not required, control is advanced to step S7 by skipping step S5 and step S6, and the single target braking / driving force moment (target between left and right wheels) The braking / driving force command values for the left and right rear wheels 2L, 2R are obtained from the braking / driving force difference) and the vehicle longitudinal acceleration target value, and are output to the corresponding inverters 15L, 15R.

According to the turning behavior control of the first embodiment described above, the braking / driving force moment (the difference in braking / driving force between the left and right wheels), the yaw moment directly applied to the vehicle body by this, and the braking / driving force moment (between the left and right wheels) The sum of the yaw moment generated by the rolling displacement in the same direction of the left and right rear wheels 2L and 2R illustrated in Fig. 2 due to the difference in braking / driving force), that is, the braking / driving force moment (braking / driving force between the left and right wheels) The target braking / driving force moment (target wheel / branch force difference between the left and right wheels) required to achieve the target yaw moment Mz is calculated from the relationship (see Fig. 5) with the total yaw moment applied to the vehicle. Because it contributes to turning behavior control by the difference in braking and driving force between the left and right wheels of the vehicle,
In order to achieve the target yaw moment Mz while eliminating the influence of the yaw moment due to the same-direction rolling displacement illustrated in Fig. 2 of the left and right wheels caused by the difference in braking / driving force between the left and right wheels for turning behavior control By determining the braking / driving force difference, this will contribute to the vehicle's turning behavior control by the braking / driving force difference between the left and right wheels.
The yaw moment generated by the rolling displacement of the left and right wheels in the same direction due to the difference in braking / driving force between the left and right wheels for turning behavior control will not shift the turning behavior of the vehicle from the target behavior, and the turning behavior control is as intended. Can be.

If it is determined in step S4 in FIG. 3 that there are a plurality of target braking / driving force moments (differences in target braking / driving force difference between the left and right wheels), a plurality of target braking / driving force moments (right and left wheels) are determined in steps S5 and S6. Between the left and right rear wheels 2L and 2R, the friction circle utilization rate of each of the four wheels is determined, and the friction circle utilization rate (friction) of the wheel with the highest friction circle utilization rate is obtained. The maximum circle usage rate) is the frictional circle usage rate maximum value q1max, q2max, q3max due to multiple target braking / driving force moments (target braking / driving force difference between the left and right wheels), and the smallest of these q1max, q2max, q3max To select the desired braking / driving force moment (target braking / driving force difference between the left and right wheels) corresponding to q1max, q2max, or q3max and use it for the above-mentioned turning behavior control,
Avoiding the risk of selecting a target braking / driving force moment (difference between the target braking / driving force between the left and right wheels) where there is a wheel exceeding the friction circle limit, and the target braking / driving force moment with the best friction circle utilization rate (The left / right wheel target braking / driving force difference) can be selected,
The target behavior can be achieved even in a scene that is close to the limit, such as when turning with a large acceleration / deceleration.

The above-mentioned effects are added at the time of starting acceleration in which the vehicle body 4 is started from the position indicated by the solid line in FIG. 6 (a) and accelerated while the steering wheel steering angle θ is increased from θo to turn at a constant turning radius r. To
The point where the turning radius r cannot be maintained and the turning radius starts to become larger than r as indicated by R is the limit point (friction circle limit), and the vehicle body 4 turns as the target turning as indicated by the two-dot chain line Deviates from the turning trajectory of radius r.

  The target braking / driving force moment corresponding to the smallest q1max, q2max, or q3max among the maximum frictional circle usage values q1max, q2max, q3max due to multiple target braking / driving force moments (target braking / driving force difference between the left and right wheels) When selecting other than the left and right wheel target braking / driving force difference) and using it for turning behavior control, the target yaw rate γ is initially realized as shown by the dashed line in FIG. 6 (b). After that, the frictional circle cannot be used effectively, and a limit point (frictional circle limit) occurs at a small yaw rate γ1, and after that, the target yaw rate γ is set because one or more wheels exceeds the frictional circle limit. Unachievable.

  On the other hand, as in the present embodiment, the smallest q1max, q2max, or q3max among the frictional circle utilization rate maximum values q1max, q2max, q3max due to a plurality of target braking / driving force moments (target braking / driving force difference between the left and right wheels) When the target braking / driving force moment (target difference between left and right wheels) is selected and used for turning behavior control, the friction circle can be used effectively, as shown by the solid line in Fig. 6 (b). It is possible to continue to achieve the target yaw rate γ even at a small yaw rate γ1 or higher, and a limit point (friction circle limit) occurs only at a large yaw rate γ2, and the yaw rate limit is increased from γ1 to γ2 to achieve a higher target yaw rate. Is feasible.

FIG. 7 shows another embodiment (second embodiment) of turning behavior control according to the present invention. This embodiment corresponds to steps S8 and S8 for the left and right rear wheel braking / driving force command value calculation program shown in FIG. S9 is added.
There are things that exceed the friction circle limit when selecting the maximum frictional circle usage rate q1max, q2max, q3max with multiple target braking / driving force moments (target braking / driving force difference between left and right wheels) In this case, it is necessary to increase the yaw rate limit as described above with reference to FIG. 6 by excluding this, and two or more of the maximum frictional circle utilization values q1max, q2max, q3max have the frictional circle limit. If it does not exceed, the yaw rate limit is the same regardless of which of these is selected. Therefore, it is preferable to control the behavior so that the change in behavior of the vehicle becomes as small as possible.

In view of this requirement, in this embodiment, in step S8 added between step S5 and step S6, whether or not any one of the frictional circle utilization rate maximum values q1max, q2max, q3max obtained in step S5 exceeds the set value ( Check that two or more of q1max, q2max, and q3max do not exceed the set value).
Here, the set values related to q1max, q2max, and q3max are for determining whether or not the frictional circle limit is exceeded, and are set to values near 100%.

  When it is determined in step S8 that any one of the friction circle utilization rate maximum values q1max, q2max, and q3max exceeds the set value, the control proceeds to step S6 to exclude the exceeding value, and the friction circle utilization is performed here. Of the maximum rate values q1max, q2max, and q3max, the target braking / driving force moment (the target braking / driving force difference between the left and right wheels) corresponding to the smallest q1max, q2max, or q3max is selected to contribute to the calculation in step S7. As a result, the effect of increasing the yaw rate limit is realized as described above with reference to FIG.

However, if it is determined in step S8 that two or more of the frictional circle utilization rate maximum values q1max, q2max, q3max do not exceed the set value, in step S9, two or more target braking / driving force moments corresponding to them ( Select the target braking / driving force moment (target braking / driving force difference between the left and right wheels) that is closest to the current braking / driving force moment (difference between the braking / driving forces between the left and right wheels) Contributes to the calculation in step S7.
In this case, the yaw rate limit is the same regardless of which of the above two or more target braking / driving force moments (target braking / driving force difference between left and right wheels), but the current braking / driving force moment (braking between left and right wheels) Since the target braking / driving force moment (difference between the left and right wheels) is selected and contributes to behavior control, behavior control with less discomfort is achieved so that changes in vehicle behavior become as small as possible. Highly preferred.

This action and effect will be supplemented by FIG.
In the first embodiment in which step S8 and step S9 are excluded from FIG. 7 and the control program of FIG. 3 is executed, when there are a plurality of friction circle utilization rate maximum values q1max, q2max, and q3max that do not exceed the above set values. In this case, the target braking / driving force moment (the target braking / driving force difference between the left and right wheels) corresponding to the smallest one of the maximum friction circle utilization values q1max, q2max, q3max is selected, which contributes to behavior control.
As shown by the broken line in FIG. 8, every time the smallest one of the maximum frictional circle utilization values q1max, q2max, q3max is switched, the target braking / driving force moment (target braking / driving force difference between the left and right wheels) to be used is also controlled. The control is switched regardless of the driving force moment (the difference in braking / driving force between the left and right wheels) and fluctuates greatly, and the control is accompanied by repeated large behavior changes.

On the other hand, if it is determined in step S8 in FIG. 7 that there are a plurality of frictional circle utilization rate maximum values q1max, q2max, and q3max that do not exceed the set value, two or more target braking / driving forces corresponding to these in step S9. Select the target braking / driving force moment (target braking / driving force difference between the left and right wheels) that is closest to the current braking / driving force moment (difference between the left and right wheels). In the case of the second embodiment contributing to behavior control,
The yaw rate limit is the same regardless of which of the above two or more target braking / driving force moments (the difference between the left and right wheel target braking / driving force), but the current braking / driving force moment (the difference between the left and right wheel braking / driving force) The target braking / driving force moment (target braking / driving force difference between the left and right wheels) closest to is selected, so the time series change of the target braking / driving force moment (target braking / driving force difference between the left and right wheels) shown in FIG. Therefore, it is highly preferable that the yaw rate limit can be increased by the behavior control with less uncomfortable feeling so that the behavior change of the vehicle becomes as small as possible.

FIG. 9 shows still another embodiment (third embodiment) of the turning behavior control according to the present invention. In this embodiment, step S10 is executed on the left and right rear wheel braking / driving force command value calculation program shown in FIG. Step S11 and step S12 are added.
In step S10 added between step S4 and step S5, as illustrated in FIGS. 10A and 10B corresponding to FIG. 5, the total yaw moment (target yaw moment Mz) and braking / driving force moment (right and left wheels) Total yaw moment area (hatched) with multiple target braking / driving force moments (target braking / driving force difference between left and right wheels) required to achieve the target yaw moment Mz calculated from the relationship with the braking / braking force difference) It is checked whether or not the area shown in FIG.

When the total yaw moment area (hatched area) where there are multiple target braking / driving force moments (difference between the target braking / driving forces between the left and right wheels) is wider than the set range ± ε as shown in Fig. 10 (a) Only the control proceeds to step S5, and behavior control similar to that of the second embodiment described above with reference to FIG. 7 is performed.
However, as shown in FIG. 10 (b), the total yaw moment area (the area shown with hatching) where there are multiple target braking / driving force moments (target braking / driving force difference between the left and right wheels) is narrower than the set range ± ε. In this case, control proceeds to step S12, and the smallest target braking / driving force moment (target braking / driving force difference between left and right wheels) is selected from among a plurality of target braking / driving force moments (target braking / driving force difference between left and right wheels). This contributes to the calculation (turning behavior control) of the left and right rear wheel braking / driving force command values in step S7.

When the total yaw moment area (area shown with hatching) where there are multiple target braking / driving force moments (the difference between the target braking / driving forces between the left and right wheels) is narrower than the set range ± ε, the smallest target braking According to the turning behavior control of this embodiment that selects the driving force moment (the target braking / driving force difference between the left and right wheels),
In order to achieve a small target yaw moment Mz within the setting range ± ε, it is possible to avoid the adverse effect that a large braking / driving force moment (difference in braking / driving force between the left and right wheels) beyond the necessity is wasted. It is possible to stably realize the target behavior even when a disturbance is input by suppressing a change in behavior with respect to a disturbance that does not occur.
Therefore, the above set range ± ε is preferably set to about the maximum value of the yaw moment generated by the disturbance.

In step S11, which is selected when it is determined in step S8 that two or more of the friction circle utilization rate maximum values q1max, q2max, q3max do not exceed the set value, the absolute value of the target yaw moment Mz is set to the set time. It is determined whether or not it is less than a set value (for example, yaw moment corresponding to a traveling state close to straight traveling).
When it is determined that the absolute value of the target yaw moment Mz is less than the set value for a set time or longer due to continuation of a running state close to straight running, the control proceeds to step S12 and a plurality of target braking / driving force moments ( Select the smallest target braking / driving force moment (target braking / driving force difference between left and right wheels) from the left / right wheel target braking / driving force difference) and calculate the left / right rear wheel braking / driving force command value in step S7 (turning behavior) Control).

According to such turning behavior control, it is possible to eliminate, or at least minimize, the adverse effect that the braking / driving force moment (the difference in braking / driving force between the left and right wheels) continues to be applied even when the vehicle is traveling straight ahead. The target braking / driving force moment (target braking / driving force difference between the left and right wheels) that maximizes the equivalent cornering power of the tire (the larger the braking / driving force is, the greater the value) is. You can choose.
As a result, when an unexpected disturbance or the like is applied to the vehicle, it is possible to suppress a change in behavior with respect to the disturbance and to achieve an effect that the target behavior can be realized more reliably.

  In step S8, it is determined that two or more of the maximum frictional circle utilization values q1max, q2max, q3max do not exceed the set value, and in step S11, it is determined that the absolute value of the target yaw moment Mz is not less than the set value. When it is determined that this state does not continue for the set time or longer even if the absolute value of the target yaw moment Mz is less than the set value, the control proceeds to step S9, and the current braking / driving force moment (between the left and right wheels) By selecting the target braking / driving force moment (target braking / driving force difference between the left and right wheels) closest to the braking / driving force difference), the effect of the second embodiment described above with reference to FIG. 9 is achieved.

  FIG. 11 shows still another embodiment (fourth embodiment) of turning behavior control according to the present invention. In this embodiment, step S13 is added to the left / right rear wheel braking / driving force command value calculation program shown in FIG. The transient response of the left and right rear wheel rolling displacement (see Fig. 2) with respect to the change in braking / driving force moment (difference in braking / driving force between the left and right wheels) is calculated, and this transient response is used for the calculation in step S3. is there.

First, in step S13, how to calculate the transient response of the left and right rear wheel rolling displacement with respect to the change in braking / driving force moment (difference in braking / driving force between the left and right wheels) will be described.
Since the rolling displacements of the left and right rear wheels 2L and 2R are symmetric rolling displacements as is apparent from FIG. 2, calculation is performed here focusing on the rolling displacement on one side as shown in FIG.

As shown in Fig. 12, the mass of the part that rotates with the rolling displacement of the rear wheel (see Fig. 2) is m (the sum of the mass of the suspension member and the unsprung load of the rear wheel), and before and after the suspension. If the spring constant determined by the stiffness value is k (obtained by a static characteristic test), and the damping coefficient determined by the physical characteristics of the elastic body (bush) 11 connecting the suspension member 9 and the vehicle body 4 is c,
The rotational motion of the suspension member 11 associated with the rolling displacement of the rear wheel (see Fig. 2) can be approximated to the motion of a vibration system with one degree of freedom, and the frequency response characteristics (gain and phase) related to this rotational motion It can be obtained as shown in FIG.
For this reason, the braking / driving force Fx _RL and Fx _RR for each of the left and right wheels are used as inputs, and the displacements D _RL and D _RR for each of the left and right wheels are used as outputs, so The transient response of the left and right wheel rolling displacement when the left and right wheel braking / driving force changes with this change can be calculated as follows.

First, the yaw moment of the vehicle generated by the rolling displacement of the rear wheels 2R and 2L (see FIG. 2) is obtained.
When braking / driving forces Fx _RR and Fx _RL are applied to the rear two wheels 2R and 2L, the rear two wheels 2R and 2L roll forward and backward. _Are D _RR and D _RL respectively, and b is the tread between the rear two wheels 2R and 2L, the toe angle change amount ζ due to the forward and backward rolling displacement of the rear two wheels 2R and 2L corresponds to the above equation (3). It is calculated by the following formula.
ζ = sin ⁻¹ {[D _RR −D _RL ] / b}
≒ [D _RR −D _RL ] / b (11)

The left and right front wheel turning angles δ _L and δ _R obtained as described above, the toe angle change amount Φ of each wheel, the vehicle body slip angle in each wheel, and the left and right rear wheels 2L obtained by the calculation of the above equation (11). , 2R toe angle change amount ζ, tire slip angles β _FL , β _FR of left and right front wheels 1L, 1R and tire slip angles β _RL , β _RR of left and right rear wheels 2L, 2R were respectively described above (4) to Obtained by the calculation of equation (7) (described again below for convenience).
β _FL = β body + (L _F / V) γ + δ _L + φ _FL (4)
β _FR = βbody + (L _F / V) γ + δ _R + φ _FR (5)
β _RL = βbody− (L _R / V) γ + φ _RL + ζ (6)
β _RR = βbody− (L _R / V) γ + φ _RR + ζ (7)

Then, the cornering power of each wheel is estimated from each estimated wheel load Fz and each wheel longitudinal force Fx (previously calculated braking / driving force value).
Here, when the load dependence of the cornering power is approximated by a quadratic function, the cornering power Kij {i: front wheel or rear wheel, j: right wheel or left wheel} of each wheel is a constant determined by the tire, a1 and a2. When the road surface friction coefficient estimated value is μ, it can be estimated and calculated by the above-described equation (8) (described again below for convenience).
Kij = (a1 · Fzij ² + a2 · Fzij) × {1− (Fxij / [μ · Fzij]) ² } ^1/2 (8)

Based on the tire slip angle βij of each wheel and the cornering power Kij of each wheel determined as described above, the lateral force Fy is calculated as follows.
That is, by approximating the nonlinear characteristic of the lateral force Fy with respect to the tire slip angle βij by a quadratic function, the lateral force Fy can be estimated by the above-described equation (9) (described again below for convenience).
Fyij = Kij · βij− (Kij ² / [4μ · Fzij]) βij ² (9)

Of the lateral forces Fyij described above, the lateral force of the front wheels is multiplied by the distance Lf between the front axle and the vehicle center of gravity, and the lateral force of the rear wheels is multiplied by the distance Lr between the rear axle and the vehicle center of gravity. The yaw moment generated in the vehicle can be determined by the rolling displacement (see FIG. 2).
The sum of the yaw moment due to the rolling displacement of the rear wheels 2L and 2R thus obtained and the yaw moment directly applied to the vehicle by the braking / driving force moment (difference in braking / driving force between the left and right wheels) is This is the total yaw moment that the braking / driving force moment for turning behavior (the difference in braking / driving force between the left and right wheels) is indirectly and directly applied to the vehicle.

Next, the relationship between the target moment Mz and the target braking / driving force moment (right and left wheel target braking / driving force difference) necessary to achieve this is obtained.
The relationship between the braking / driving force moment (the difference in braking / driving force between the left and right wheels) and the total yaw moment is determined as shown by the broken line in FIG. 14 (the same as the solid line characteristics in FIG. 5).
The braking / driving force moment (braking force between the left and right wheels) is delayed by the transient response of the rolling displacement of the left and right rear wheels 2L and 2R (see Fig. 2) to the change in braking / driving force moment (difference in braking force between the left and right wheels). The relationship between the difference and the total yaw moment changes from a solid line characteristic to a broken line characteristic.

Therefore, in the embodiment shown in FIG. 14, when the target braking / driving force moment (target braking / driving force difference between the left and right wheels) is obtained in step S3, the left / right rear is changed with respect to the change in braking / driving force moment (difference between braking force on the left and right wheels). While the rolling displacement of the wheels 2L and 2R (see Fig. 2) is delayed, the braking / driving force moment (difference in braking / driving force between the left and right wheels) and the total yaw moment change accordingly. The target braking / driving force moment (target braking / driving force difference between the left and right wheels) is obtained based on
Therefore, in the present embodiment, even when the target braking / driving force moment (the target braking / driving force difference between the left and right wheels) changes abruptly, the target yaw moment Mz can be achieved with certainty.

1 is a diagrammatic plan view of a vehicle provided with a turning behavior control device according to an embodiment of the present invention. 1 is a diagrammatic plan view similar to FIG. 1 illustrating the rolling displacement state of the left and right rear wheels when a braking / driving force difference for turning behavior control is applied between the left and right rear wheels, which are the drive wheels of the vehicle shown in FIG. It is. FIG. 2 is a flowchart showing a control program executed when the controller in FIG. 1 obtains left and right rear wheel braking / driving force command values necessary for giving a left / right rear wheel braking / driving force difference for turning behavior control. FIG. 6 is a characteristic diagram showing a relationship between a left / right wheel braking / driving force difference (braking / driving force moment) and a total value of yaw moments that are directly and indirectly applied to the vehicle. From the relationship between the total yaw moment obtained from the characteristics in Fig. 4 and the braking / driving force difference between left and right wheels (braking and driving force moment), the target braking / driving force difference between left and right wheels (target) required to achieve the target yaw moment. It is explanatory drawing which shows the point which calculates | requires braking / driving force moment. It is a figure for explaining a yaw rate limit, (a) is an explanatory view showing the turning traveling state of the vehicle which is a premise when explaining the yaw rate limit, (b) shows the occurrence situation of the limit yaw rate with respect to the target yaw rate It is explanatory drawing. FIG. 4 is a flowchart of a control program similar to FIG. 3, showing another embodiment of the present invention. The time series change of the target braking / driving force difference (target braking / driving force moment) between the left and right wheels in this embodiment is the time series change of the target braking / driving force difference (target braking / driving force moment) between the left and right wheels in the first embodiment. It is a time chart shown in comparison. FIG. 8 is a flowchart of a control program similar to FIGS. 3 and 7, showing still another embodiment of the present invention. FIG. In this example, two examples of the relationship between the total yaw moment and the braking / driving force difference between the left and right wheels (braking / driving force moment) are shown, where (a) is for achieving the target yaw moment. Relationship line between the total yaw moment and the left / right wheel braking / driving force difference (braking / driving force moment) when there is a wide range of total yaw moment where there are multiple target braking / driving force differences (target braking / driving force moment) Fig. (B) shows the total yaw moment and the left / right wheel braking / driving when the total yaw moment area is narrow and there are multiple target braking / driving force differences between the left and right wheels (target braking / driving force moment) to achieve the target yaw moment. It is a relationship diagram with a force difference (braking / driving force moment). 10 is a flowchart of a control program similar to FIGS. 3, 7, and 9 showing still another embodiment of the present invention. It is the schematic diagram which showed typically the support structure of the suspension member with respect to a vehicle body. It is a frequency characteristic figure which shows the gain change and phase change with respect to the frequency of the support structure. FIG. 6 is a characteristic diagram similar to FIG. 5 showing a change state of the relationship between the left / right wheel braking / driving force difference (braking / driving force moment) and the total yaw moment at the time of transition when the target yaw moment changes suddenly.

Explanation of symbols

1L left steering wheel (front left wheel)
1R right steering wheel (right front wheel)
2L left drive wheel (left rear wheel)
2R right drive wheel (left rear wheel)
4 body
5 Steering wheel
6 Steering gear device
7L, 7R suspension arm
8L, 8R suspension link
9 Suspension member
11 Elastic body
12L, 12R braking drive motor
13L, 13R Motor output shaft
14 Controller
15L, 15R inverter
16 Steering angle sensor
17 Accelerator position sensor
18 Brake pedal force sensor
19 Vehicle speed sensor
21 Yaw rate sensor
22 Longitudinal acceleration sensor
23 Lateral acceleration sensor

Claims (9)

A vehicle in which at least one pair of left and right wheels are suspended so as to be capable of rolling displacement in the same direction against a resilient force around a common vertical axis between these left and right wheels,
When controlling the turning behavior of the vehicle by giving a target yaw moment to the vehicle body by giving a braking / driving force difference between the left and right wheels,
Obtain the yaw moment to be applied to the vehicle body with the rolling displacement of the left and right wheels due to the difference in braking / driving force between the left and right wheels,
A turning behavior control method for a vehicle, wherein the difference in braking / driving force between the left and right wheels is determined such that the target yaw moment is achieved while eliminating the influence of the yaw moment associated with the rolling displacement of the left and right wheels. In the vehicle turning behavior control method according to claim 1,
The left and right wheels so that the sum of the yaw moment resulting from the rolling displacement of the left and right wheels due to the difference in braking / driving force between the left and right wheels and the yaw moment due to the difference in braking / driving force between the left and right wheels becomes the target yaw moment. A method for controlling a turning behavior of a vehicle, characterized by determining a difference in braking / driving force. Suspend at least one pair of left and right wheels so that they can roll and displace in the same direction against a resilient force around a common vertical axis between these left and right wheels,
In a vehicle in which a yaw moment to be targeted is given to the vehicle body by giving a braking / driving force difference between the left and right wheels,
From the correlation between the yaw moment applied to the vehicle body due to the rolling displacement of the left and right wheels due to the difference in braking / driving force between the left and right wheels, and the yaw moment due to the difference in braking / driving force between the left and right wheels, the target A left-right wheel braking / driving force difference determining means for determining a left / right wheel braking / driving force difference at which the yaw moment is achieved;
A turning behavior control device for a vehicle, comprising: a driving force difference applying means between right and left wheels for applying the braking / driving force difference determined by the means between the left and right wheels. In the vehicle turning behavior control device according to claim 3,
The left and right wheel braking / driving force difference determining means includes:
Means for obtaining the relationship between the yaw moment applied to the vehicle body in association with the rolling displacement of the left and right wheels, the sum of yaw moments due to the difference in braking / driving force between the left and right wheels, and the difference in braking / driving force between the left and right wheels When,
From the relationship obtained by the means, the left-right wheel braking / driving is instructed to the left-right wheel driving force difference applying means by applying the left-right wheel braking / driving force difference obtained by applying the target yaw moment to the sum of the yaw moments. A turning behavior control device for a vehicle characterized by comprising force difference command means. In the vehicle turning behavior control device according to claim 4,
The left and right wheel braking / driving force difference command means includes:
From the relationship between the sum value of the yaw moment and the braking / driving force difference between the left and right wheels, when there are a plurality of left / right wheel braking / driving force differences obtained by applying the target yaw moment to the sum of the yaw moments, these Among the plurality of left and right wheel braking / driving force differences, the right / left wheel braking / driving force difference is selected so as to minimize the friction circle utilization rate of the wheel having the highest friction circle utilization rate. A turning behavior control device for a vehicle, characterized in that it instructs the means. In the vehicle turning behavior control device according to claim 5,
The left and right wheel braking / driving force difference command means includes:
When there are a plurality of left and right wheel braking / driving force differences such that the maximum friction circle utilization rate of the left and right wheels does not exceed the set value, the right and left wheels closest to the current left / right wheel braking / driving force difference A turning behavior control device for a vehicle, characterized in that a difference in driving force between the left and right wheels is selected and commanded to the driving force difference applying means. In the vehicle turning behavior control device according to claim 5 or 6,
The left and right wheel braking / driving force difference command means includes:
From the relationship between the sum value of the yaw moment and the left / right wheel braking / driving force difference, there are a plurality of left / right wheel braking / driving force differences obtained by applying the target yaw moment to the yaw moment sum value, and When the absolute value of the target yaw moment is less than the set value over a set time, the smallest left-right wheel braking / driving force difference is selected from the plurality of left-right wheel braking force differences, and the left-right wheel driving force is selected. A turning behavior control device for a vehicle, characterized in that it commands the difference giving means. In the turning behavior control device for a vehicle according to any one of claims 4 to 7,
The left and right wheel braking / driving force difference command means includes:
From the relationship between the sum value of the yaw moment and the braking / driving force difference between the left and right wheels, a target having a plurality of left / right wheel braking / driving force differences obtained by applying the target yaw moment to the sum of the yaw moments. When the yaw moment range is narrower than the set range, the smallest left-right wheel braking / driving force difference among the plurality of left-right wheel braking / driving force differences is selected and the left-right wheel driving force difference providing means is selected. A turning behavior control device for a vehicle, characterized by being commanded. In the vehicle turning behavior control device according to any one of claims 4 to 8,
The left and right wheel braking / driving force difference command means includes:
Based on the transient response characteristics of the left and right wheel rolling displacement to the change in the left and right wheel braking / driving force difference, the relationship between the target yaw moment, the left / right wheel braking / driving force difference, and the yaw moment accompanying the left and right wheel rolling displacement A vehicle turning behavior control device characterized by correcting the vehicle.

Images