JP2000095084A - Vehicle motion control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve vehicle motion control performance. SOLUTION: The vehicle property when the slip factor Si of each wheel is 0 is computed on the basis of the static support load of each wheel, and the target state quantities Fxa, Fya, Ma are computed as the sum of the vehicle property and the target property of behavior control (S250). Differential coefficient dFx, dFy, dM showing the change of the vehicle property to the infinitesimal change dSi of the slip factor of each wheel are computer (S300). The actual value of the vehicle property is computer on the basis of the actual support load of each wheel, and the correction quantities δFx, δFy, δM of the vehicle property are computed on the basis of the differential coefficients and the difference between the target value and actual value of the vehicle property (S200, 350). The slip factor correction quantity δSi of each wheel for attaining these correction quantities is computed (S400), and the previsouly computed target slip factor is corrected with the slip factor correction quantity δSi (S450). Braking force of each wheel is controlled to attain the corrected target slip factor (S550).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion control device for a vehicle, and more particularly, to a motion control device for improving the stability of a vehicle during traveling.

[0002]

2. Description of the Related Art In general, the relationship between the yaw moment required to stabilize the behavior of a vehicle and the slip ratio of each wheel changes depending on the condition of the vehicle and the environment. Due to the limitation of the memory capacity of the computer used for the control device, only a few maps of about 2 or 3 can be set for each wheel, and therefore the accuracy of the behavior control is limited, and therefore the behavior control efficiency is high, but Rear wheel braking, which may impair the safety of the vehicle, cannot be actively used.

In order to deal with such a problem, the present applicant has filed a Japanese Patent Application No. 10-114126 before the publication of the earlier application.
In the specification and the drawings, a means for calculating a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control amount from a tire model and a target value of a vehicle state quantity for stabilizing the motion of the vehicle are set in the vehicle. Means for calculating based on a model or a driver's request, means for calculating a target control amount for each wheel that achieves the target value by convergence calculation using the derivative and the target value, and realizing the target control amount And a means for controlling the wheel operating device to perform the motion control.

[0004] According to the motion control device according to the prior proposal, the control amount of each wheel can be controlled to the target control amount with high accuracy without the need for a large number of maps, whereby the motion of the vehicle can be surely and securely performed. It can be appropriately stabilized.

[0005]

Generally, when a braking force is applied to wheels in order to stabilize the behavior of the vehicle, the vehicle decelerates, and the yaw moment acting on the vehicle changes due to the movement of the load in the longitudinal direction of the vehicle. Although the lateral force of the rear wheel decreases, in the motion control device according to the above-mentioned proposal,
Changes in yaw moment and reduction in rear wheel lateral force due to load movement in the vehicle front-rear direction are not taken into account, and therefore there is room for improvement in improving motion control performance.

According to the present invention, a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control quantity is calculated from a tire model,
A target control amount of each wheel that calculates a target value of a vehicle state quantity for stabilizing the motion of the vehicle based on a vehicle model or a driver's request, and realizes the target value by a convergence calculation using a differential coefficient and a target value. The present invention has been made in view of the above-described problem in the motion control device according to the above-described previous proposal for controlling the wheel operating device to achieve the target control amount, and a main problem of the present invention is Another object of the present invention is to further improve the motion control performance of the vehicle by taking into account the change in the yaw moment and the decrease in the rear wheel lateral force caused by the load movement in the vehicle front-rear direction accompanying the motion control.

[0007]

According to the present invention, the above-mentioned main problem is solved by the configuration according to claim 1, that is, a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control quantity is calculated from a tire model. Means, means for calculating a target value of a vehicle state quantity for stabilizing the motion of the vehicle based on a vehicle model or a driver's request, and the target value by convergence calculation using the differential coefficient and the target value. In a vehicle motion control device having means for calculating a target control amount of each wheel to be realized and means for controlling a wheel operating device so as to realize the target control amount, an actual support load of each wheel is estimated. The target value of the vehicle state quantity is the sum of the target value of the vehicle state quantity when the slip ratio of each wheel is 0 and the target value of the vehicle state quantity for stabilizing the behavior of the vehicle. Is calculated as The target control amount is calculated based on the deviation between the target value and the actual vehicle state amount, and the actual vehicle state amount is calculated based on the actual support load of each wheel estimated by the estimating means. The target value of the vehicle state quantity when the slip ratio of the vehicle is zero is calculated based on the static support load of each wheel, and is achieved by the vehicle motion control device.

According to the configuration of the first aspect, the differential coefficient of the change in the vehicle state quantity with respect to the slight change in the wheel control amount is calculated from the tire model, and the target value of the vehicle state quantity for stabilizing the movement of the vehicle is calculated. Is calculated based on a vehicle model or a driver's request, a target control amount of each wheel that achieves the target value is calculated by a convergence calculation using the differential coefficient and the target value, and the target control amount is realized. Since the wheel operating device is controlled, the control amount of each wheel is controlled to the target control amount with high accuracy without requiring a large number of maps, so that not only the movement of the vehicle is reliably and appropriately stabilized, but also The target value of the vehicle state quantity is calculated as the sum of the target value of the vehicle state quantity when the slip ratio of each wheel is 0 and the target value of the vehicle state quantity for stabilizing the behavior of the vehicle. Target control amount is The actual vehicle state quantity is calculated based on the deviation between the value and the actual vehicle state quantity, and the actual vehicle state quantity is calculated based on the actual support load of each wheel estimated by the estimating means. The target value of the vehicle state quantity is calculated based on the static support load of each wheel, and the calculation of the deviation cancels out the change in the yaw moment and the decrease in the lateral force caused by the load movement in the vehicle front-rear direction. The target control amount of each wheel, in which the change in the yaw moment and the decrease in the lateral force caused by the load movement are offset, is calculated, whereby the motion control of the vehicle is performed in comparison with the motion control device according to the above-mentioned proposal. Performance is improved.

Further, according to the present invention, the above-mentioned main problem is that according to the configuration of claim 2, a means for calculating a differential coefficient of a change in the vehicle state amount with respect to a small change in the wheel control amount from a tire model, Means for calculating a target value of the vehicle state quantity for stabilizing the motion based on a vehicle model or a driver's request; and a means for realizing the target value by a convergence calculation using the derivative and the target value. Means for calculating a target slip rate, and means for controlling a wheel operating device so as to realize the target slip rate, wherein the means for calculating the target slip rate for each of the wheels includes "the actual vehicle state quantity and its target An evaluation consisting of the difference between the "deviation from the value" and the "product of the derivative and the change in the target slip rate", the change in the target slip rate, and the sum of squares of the sum of the target slip rate and the change. Minimum function value In the vehicle motion control device for calculating the change amount of the target slip ratio of each wheel by convergence calculation and correcting the previously calculated target slip ratio with the change amount of the target slip ratio, the evaluation function The weighting factor for the slip ratio of the rear wheels is larger than the weighting factor for the slip ratio of the front wheels.

According to the configuration of the second aspect, similarly to the configuration of the first aspect, the control amount of each wheel is controlled to the target control amount with high accuracy without requiring a large number of maps. Is not only reliably and properly stabilized,
The difference between the "deviation between the actual vehicle state quantity and its target value" and the "product of the derivative and the change in the target slip rate", the change in the target slip rate, and the sum of the target slip rate and the change The amount of change in the target slip rate of each wheel is calculated by convergence calculation so that the value of the evaluation function consisting of the sum of squares of the wheels becomes the minimum, and the previously calculated target slip rate is corrected by the amount of change in the target slip rate. Since the weight coefficient for the slip rate of the rear wheel of the function is larger than the weight coefficient for the slip rate of the front wheel, the weight coefficient for the slip rate of the front wheel is larger than the weight coefficient for the slip rate of the rear wheel, or these weight coefficients are the same. As compared with the case, the rate of increase of the evaluation function with the increase in the slip rate of the rear wheel is increased, and there is a possibility that the braking force of the rear wheel becomes excessive and the lateral force of the rear wheel is greatly reduced. Reduced.

Further, according to the present invention, the main object is to provide a structure according to claim 3, that is, means for calculating a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control amount from a tire model, Means for calculating a target value of the vehicle state quantity for stabilizing the motion based on a vehicle model or a driver's request; and a means for realizing the target value by a convergence calculation using the derivative and the target value. In a vehicle motion control device having means for calculating a target control amount and means for controlling a wheel operating device so as to realize the target control amount, the target value of the vehicle state amount is a target value of the front wheel lateral force. And the target value of the rear wheel lateral force are independently included.

According to the configuration of the third aspect, similarly to the configuration of the first aspect, the control amount of each wheel can be controlled to the target control amount with high accuracy without requiring a large number of maps, whereby the movement of the vehicle is improved. Is not only reliably and properly stabilized,
Since the target value of the vehicle state quantity independently includes the target value of the front wheel lateral force and the target value of the rear wheel lateral force, the target control amount of each wheel is calculated to realize the target value of the rear wheel lateral force, Therefore, the possibility that the lateral force of the rear wheel becomes insufficient due to the load movement in the vehicle front-rear direction is reduced as compared with the case where the target value of the lateral force of the entire vehicle is calculated.

Further, according to the present invention, the above-mentioned main problem is that according to the configuration of claim 4, means for calculating a differential coefficient of a change in the vehicle state quantity with respect to a small change in the wheel control amount from a tire model, Means for calculating a target value of the vehicle state quantity for stabilizing the motion based on a vehicle model or a driver's request; and a means for realizing the target value by a convergence calculation using the derivative and the target value. In a vehicle motion control device having means for calculating a target control amount and means for controlling a wheel operating device so as to realize the target control amount, the means for calculating the target control amount for each wheel is a current control amount. A correction amount of the target control amount of the front wheels is calculated based on a difference between the vehicle state amount and the target value, and a target control amount of the front wheels is calculated as a sum of the previous target control amount of the front wheels and the correction amount of the front wheels, Predetermined amount of correction for the front wheel The correction amount of the target control amount of the rear wheel is calculated by multiplying the magnification, and the target control amount of the rear wheel is calculated as the sum of the previous target control amount of the rear wheel and the correction amount of the rear wheel. This is achieved by a vehicle motion control device.

According to the configuration of the fourth aspect, similarly to the configuration of the first aspect, the control amount of each wheel is controlled to the target control amount with high accuracy without the need for a large number of maps. Is not only reliably and properly stabilized,
The correction amount of the front wheel target control amount is calculated based on the difference between the current vehicle state amount and the target value, and the front wheel target control amount is calculated as the sum of the previous target control amount of the front wheel and the front wheel correction amount,
The correction amount of the target control amount of the rear wheel is calculated by multiplying the correction amount of the front wheel by a predetermined magnification, and the target control amount of the rear wheel is calculated as the sum of the previous target control amount of the rear wheel and the correction amount of the rear wheel. So that
The possibility that the target control amount of the rear wheel becomes excessive and the lateral force of the rear wheel becomes insufficient is reduced.

According to the present invention, in order to effectively achieve the above-described main object, in the configuration of the fourth aspect, the predetermined magnification is different between when the vehicle goes straight and when it turns. (Configuration of Claim 5).

In general, the deterioration of the stability of the vehicle due to the decrease in the rear wheel lateral force accompanying the load movement in the vehicle front-rear direction is more likely to occur at the time of turning than at the time of straight traveling of the vehicle. According to the configuration of the fifth aspect, the predetermined magnification, that is, the magnification of the target control amount of the rear wheel with respect to the target control amount of the front wheel is different between when the vehicle goes straight and when turning, and therefore, when the vehicle goes straight or when turning. In this case, the motion control is optimally performed.

[0017]

[Basic Principle of the Present Invention] The basic principle of the present invention will be described by taking a brush tire model as an example of a tire model that considers a reduction in lateral force during braking, a load shift, a tire slip angle, and a road surface friction coefficient.

First, based on the brush tire model, the longitudinal force Ftxi and the lateral force Ftyi (i
= Fr, fl, rr, rl), and a change in the tire longitudinal force and a change in the lateral force due to a small change in the slip ratio.

As shown in FIG. 15, the generated force Fti of the tire 100 of each wheel, that is, the longitudinal force Ftxi and the lateral force Ftyi.
Θi, the slip angle of the tire is βi, and the slip ratio of the tire is Si.
i (positive during braking, -∞ <S <1.0), the friction coefficient of the road surface is μ, the ground contact load of the tire is Wi, Ks and Ks
When b is a coefficient (positive constant), the longitudinal force Ftxi and the lateral force Ftyi when the tire is not in a locked state (when ξi ≧ 0) are expressed by the following equations 1 and 2, respectively. Front-rear force Ftx in the state (when ０ <0)
i and the lateral force Ftyi are expressed by the following equations 3 and 4, respectively.

[0020]

(Equation 1)

The coefficient Kb is, as shown in FIG.
Tire slip angle β when slip ratio Si is 0
The coefficient Ks is the slope at the origin of the graph of the lateral force Ftyi with respect to i, and the origin of the graph of the longitudinal force Ftxi with respect to the tire slip ratio Si when the slip angle βi is 0, as shown in FIG. Is the slope at Also
cos θ, sin θ, λ, and ξ are represented by the following equations 5 to 8, respectively.

[0022]

(Equation 2)

By partially differentiating the above equations 1 to 4 with the slip ratio Si, a change in the longitudinal force and a change in the lateral force (tire coordinate system) with respect to a small change in the slip rate are calculated (the following equations 9 and 10). .

[0024]

(Equation 3)

Next, the front-rear force and lateral force (tire coordinate system) of each tire of the right front wheel (fr), the left front wheel (fl), the right rear wheel (rr), and the left rear wheel (rl) according to the following equations 11 to 18: ) Is converted to the vehicle coordinate system to calculate the force acting on the vehicle and to calculate the moment. In the following equations, φf and φ
r is the steering angle of the front and rear wheels, Tr is the tread width of the vehicle, Lf and Lr are the distances from the center of gravity of the vehicle to the front and rear axles, respectively, and T (φf
) And T (φr) are values represented by the following equations 19 and 20, respectively.

[0026]

(Equation 4)

[0027]

(Equation 5)

[0028]

(Equation 6)

[0029]

(Equation 7)

[0030]

(Equation 8)

Similarly, the right front wheel (fr), the left front wheel (fl), the right rear wheel (rr), and the left rear wheel (rl) according to the following equations 21 to 28.
The partial differential value (derivative coefficient) of the force acting on the vehicle is calculated by converting the partial differential value (tire coordinate system) of the longitudinal force and the lateral force of each tire into the vehicle coordinate system, and the partial differential value of the moment ( Differential coefficient).

[0032]

(Equation 9)

[0033]

(Equation 10)

[0034]

[Equation 11]

[0035]

(Equation 12)

Next, based on the brush model, the longitudinal force Fx, the lateral force Fy, and the moment M generated when the slip ratio of each wheel is the target slip ratio Si are expressed by the following equation (2).
9 for the estimation calculation.

[0037]

(Equation 13)

Next, based on the following concepts (A) and (B), the desired longitudinal force Fxa,
The target lateral force Fya and the target moment Ma are calculated. The right side of the following equation 30 represents the longitudinal force, the lateral force, and the moment generated in each wheel when the slip ratio is 0.

(A) The target longitudinal force Fxt and the target moment Mt for stabilizing the behavior of the vehicle by controlling the motion of the vehicle are the longitudinal forces generated when the motion is not controlled (when the slip ratio Si is 0). Fxso and moment Mso
It is considered to be an additional amount to.

(B) Lateral force Fys when motion is not controlled
By setting o as a target lateral force Fya, a decrease in lateral force during motion control is reduced as much as possible.

[0041]

[Equation 14]

Small change in slip ratio dS of four controlled wheels
The change dFx of the longitudinal force acting on the vehicle body, the change dFy of the lateral force, and the change dM of the moment due to i are expressed by the following Expression 32. In the following equation 32, dSfr, dSfl,
dSrr and dSrl are minute changes in the slip ratio of the front right wheel, front left wheel, rear right wheel and rear left wheel, respectively, and J is a Jacobian matrix.

[0043]

(Equation 15)

Next, a slip ratio Si for realizing the target longitudinal force Fxa, the target lateral force Fya, and the target moment Ma is calculated.
However, since it is difficult to analytically solve this slip ratio, it is obtained by the following convergence calculation.

Assuming that the difference between the current longitudinal force, lateral force, and moment and the desired longitudinal force, desired lateral force, and desired moment is Δ, Δ is represented by the following equation 33, and the slip ratio at which Δ is set to 0 is Among the correction amounts, a slip ratio correction amount δS that minimizes the evaluation function L represented by the following Expression 34 using T as a transport is obtained.

[0046]

(Equation 16)

L = δS ^T WdsδS + (S + δS) ^T Ws (S + δS) + E ^T Wf E (34) The slip rate correction amount δS for minimizing the evaluation function L of Expression 34
Is as shown in Expression 35 below. Where Fx, Fy, and M are the longitudinal force, the lateral force, and the moment (Equation 29) generated at the current slip ratio of the controlled wheel, respectively, and Fxa, Fy
a and Ma are a target longitudinal force, a target lateral force, and a target moment (Equation 31), respectively, and S and δS are a slip rate (Equation 36 below) and a slip rate correction amount (Equation 37 below) of each wheel, respectively. And E is the longitudinal force, lateral force by Δ and δS,
The difference from the moment correction amount (Equation 38 below)
ds is a weight for the slip ratio correction amount δS (formula 3 below)
9), Ws is the weight for the slip ratio S (Equation 40 below), and Wf is the weight for each force (Equation 4 below).
1), and each weight is 0 or a positive value.

[0048] δS = (Wds + Ws + J T Wf J) -1 (-Ws S + J T Wf Δ) ...... (35)

[0049]

[Equation 17]

[0050]

(Equation 18)

[0051]

[Equation 19]

[0052]

(Equation 20)

[0053]

(Equation 21)

[0054]

(Equation 22)

Therefore, by correcting the previous target slip ratio Si with the slip ratio correction amount δSi, the target slip ratio Si of each wheel which achieves the target longitudinal force Fxa, the target lateral force Fya, and the target moment Ma is calculated. Can be.

In this case, the static contact load of the tire, that is, the contact load of the tire when the vehicle is in a stationary state is defined as Woi, and the contact load Wi of the tire in the above equations 1 to 4 is represented by WOi.
The slip rate Si is set to 0, the longitudinal force Ftxi and the lateral force Ftyi of each tire are calculated, and based on these, the vehicle coordinate system when the slip rate Si is 0 according to Equations 11 to 20 above. Front and rear force Fxiso, lateral force Fyis
o, the moment Miso is calculated, and the above equations 30 and 31 are calculated.
If the target longitudinal force Fxa, the target lateral force Fya, and the target moment Ma are calculated according to the above, these do not include the change in the moment and the decrease in the lateral force caused by the load movement in the vehicle longitudinal direction due to the movement control.

Therefore, the calculation of the difference Δ between the present longitudinal force, lateral force, and moment and the target longitudinal force, the target lateral force, and the target moment according to the above equation 33 allows a change in moment and a decrease in lateral force due to the load movement. The slip rate correction amount δS that minimizes the evaluation function L of the above equation 34 is calculated from the slip rate correction amounts that make the difference Δ, in which the change in the moment and the decrease in the lateral force are canceled out, zero. Slip ratio S
The longitudinal force Fxiso and the lateral force F in the vehicle coordinate system when i is 0
yiso and moment Miso are also the actual ground load Wi of the tire.
The motion control performance of the vehicle is improved as compared with the case where the calculation is performed based on the longitudinal force Ftxi and the lateral force Ftyi of the tires of each wheel based on the above.

If the weight Wsr of the rear wheel is set to be larger than the weight Wsf of the front wheel among the weights Ws for the slip ratio S expressed by the above equation 40, if the weights are the same or the weight Wsf of the front wheel is As compared with the case where the weight is set larger than the weight Wsr of the wheel, the rate of increase of the evaluation function L with the increase of the slip rate of the rear wheel is increased. The possibility that the lateral force is greatly reduced is reduced (the configuration of claim 2).

The above equations 29 to 33, 36 to 39 and 41 are represented by the following equations 29A to 33A and 36A to 3A, respectively.
9A, which is replaced by equation 41A, whereby the desired lateral force F of the front wheels is added to the desired longitudinal force Fxa and the desired moment Ma.
If yfa and the target lateral force Fyra of the rear wheel are calculated, and if the target slip ratio Si realizing these target control amounts is calculated, the lateral force of the rear wheel is controlled to the target lateral force Fyra. As compared with the case where the target slip ratio Si is calculated according to the formulas (1) to (41), the possibility that the lateral force of the rear wheels becomes insufficient due to the load movement in the vehicle longitudinal direction is reduced.

[0060]

(Equation 23)

[0061]

(Equation 24)

[0062]

(Equation 25)

[0063]

(Equation 26)

[0064]

[Equation 27]

[0065]

[Equation 28]

[0066]

(Equation 29)

[0067]

[Equation 30]

[0068]

(Equation 31)

The above formulas 32, 36, 37, 39, 40
Are the following formulas 32B, 36B, 37B, 39B, respectively.
40B, the slip ratio correction amounts δSfr and δSfl of the front wheels are calculated, and K is set to a predetermined magnification (0
<K ≦ 1), the rear wheel slip ratio correction amounts δSrr, δS
If rl is calculated as K times the front wheel slip ratio correction amounts δSfr and δSfl, the possibility that the target control amount of the rear wheel becomes excessive and the lateral force of the rear wheel becomes insufficient is reduced. The load on the calculation means is reduced (the configuration of claim 4).

[0070]

(Equation 32)

[0071]

[Equation 33]

[0072]

(Equation 34)

[0073]

(Equation 35)

[0074]

[Equation 36]

Further, the ratio of the rear wheel slip ratio correction amounts δSrr and δSrl to the front wheel slip ratio correction amounts δSfr and δSfl can be changed by changing the predetermined magnification K. If the time and the turn are different, it is possible to optimally execute the motion control both in the case of the straight traveling of the vehicle and in the case of the turn (the configuration of claim 5).

[0076]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the estimating means estimates a load moving amount of each wheel based on a longitudinal acceleration and a lateral acceleration of the vehicle. It is configured to estimate the actual support load of each wheel based on the static support load of each wheel and the amount of load movement (preferred mode 1).

According to another preferred embodiment of the present invention, in any one of the first to fourth aspects, the wheel control amount is a wheel slip ratio (preferred embodiment 2). .

According to still another preferred embodiment of the present invention, in any one of the above-mentioned constitutions, the vehicle state quantity is a combination of a longitudinal force, a lateral force and a yaw moment. (Preferred embodiment 3).

According to still another preferred aspect of the present invention, in the configuration of the first aspect, the longitudinal force, the lateral force, and the moment of the vehicle when the slip ratio of each wheel is 0 are respectively Fxso , Fyso, Mso, the target value F of the longitudinal force
xa is calculated as the sum of Fxso and the target longitudinal force Fxt for stabilizing the behavior of the vehicle, and the target value Fya of the lateral force is Fys
The target value Ma of the moment is calculated as the sum of Mso and a target moment Mt for stabilizing the behavior of the vehicle, and the longitudinal force Fxso of the vehicle when the slip ratio of each wheel is 0, the lateral force Fxso, The force Fyso and the moment Mso are configured to be calculated by setting the support load Wi of each wheel to the static support load Woi (preferred mode 4).

According to still another preferred embodiment of the present invention, in any one of the above-mentioned constitutions, the wheel operating device is configured to be a braking / driving force control device (a preferred embodiment). 5).

According to still another preferred embodiment of the present invention, in any one of the first to fourth aspects, the tire model is a brush tire model (preferred embodiment 6).

According to still another preferred aspect of the present invention, in the configuration of the third aspect, the longitudinal force of the vehicle, the lateral force of the front wheel, the lateral force of the rear wheel when the slip ratio of each wheel is zero. Power,
The moments are Fxso, Fyfso, Fyrso, and Mso, respectively, and the target value Fxa of the longitudinal force is calculated as the sum of Fxso and the target longitudinal force Fxt for stabilizing the behavior of the vehicle.
The target value Fyfa of the front wheel lateral force and the target value Fyra of the rear wheel lateral force are set to Fyfso and Fyrso, respectively, and the target value Ma of the moment is calculated as the sum of Mso and the target moment Mt for stabilizing the behavior of the vehicle. (Preferred Embodiment 7).

According to still another preferred aspect of the present invention, in the configuration of the fifth aspect, the predetermined magnification is configured to be smaller when the vehicle turns than when the vehicle is traveling straight. ).

According to still another preferred embodiment of the present invention, in the configuration of the preferred embodiment 8, the predetermined magnification is set to a smaller value as the turning degree of the vehicle is higher (preferable). Aspect 9).

[0085]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the accompanying drawings, in which several preferred embodiments are shown.

First Embodiment FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle motion control device according to the present invention.

In FIG. 1, 10FL and 10FR denote left and right front wheels of the vehicle 12, respectively, and 10RL and 10RR denote left and right rear wheels which are driving wheels of the vehicle, respectively. The left and right front wheels 10FL and 10FR, which are both driven wheels and steered wheels, are driven via tie rods 18L and 18R by a rack-and-pinion type power steering device 16 driven in response to steering of the steering wheel 14 by the driver. Steered.

The braking force of each wheel is controlled by the hydraulic circuit 22 of the braking device 20 so that the wheel cylinders 24FR, 24FL, 24RR,
The control is performed by controlling the braking pressure of 24RL. Although not shown in the figure, the hydraulic circuit 2
2 includes a reservoir, an oil pump, various valve devices, etc.
Normally, the braking pressure of each wheel cylinder is controlled by a master cylinder 28 which is driven in response to a driver's depression operation of a brake pedal 26, and, if necessary, by an electric control device 30 as will be described later in detail. You.

Each of the wheels 10FR to 10RL is provided with a wheel speed sensor 32FR, 32FL, 32RR, 32RL for detecting a wheel speed Vwi (i = fr, fl, rr, rl), and a steering column to which a steering wheel 14 is connected. Is provided with a steering angle sensor 34 for detecting a steering angle φ. The vehicle 12 is provided with a yaw rate sensor 36 for detecting a yaw rate γ of the vehicle, a longitudinal acceleration sensor 38 for detecting a longitudinal acceleration Gx, a lateral acceleration sensor 40 for detecting a lateral acceleration Gy, and a vehicle speed sensor 42 for detecting a vehicle speed V. ing. The steering angle sensor 34, the yaw rate sensor 36, and the lateral acceleration sensor 40 detect the steering angle, the yaw rate, and the lateral acceleration, respectively, assuming that the left turning direction of the vehicle is positive.

As shown, the wheel speed sensors 32FR-32
A signal indicating the wheel speed Vwi detected by the RL, a signal indicating the steering angle φ detected by the steering angle sensor 34, a signal indicating the yaw rate γ detected by the yaw rate sensor 36, and the longitudinal acceleration detected by the longitudinal acceleration sensor 38 A signal indicating Gx, a signal indicating the lateral acceleration Gy detected by the lateral acceleration sensor 40, and a signal indicating the vehicle speed V detected by the vehicle speed sensor 42 are input to the electric control device 30. Although not shown in detail in the figure, the electric control device 30 has, for example, a general configuration in which a CPU, a ROM, a RAM, and an input / output port device are connected to each other by a bidirectional common bus. Includes a microcomputer.

The electric control device 30 determines the longitudinal force Fxso and the lateral force Fx of the vehicle when the slip ratio Si of each wheel is 0 in accordance with the flowcharts shown in FIGS.
The target longitudinal force Fxa, the target lateral force Fya, and the target moment Ma of the vehicle are calculated as the sum of the target longitudinal force Fxt and the target moment Mt for stabilizing the behavior of the vehicle. The differential coefficients dFx, dFy, and dM indicating changes in the longitudinal force, the lateral force, and the moment of the vehicle with respect to the minute change dSi are calculated.

The electric control device 30 is provided with a target longitudinal force F
xa and the actual longitudinal force Fx, the difference between the target lateral force Fya and the actual lateral force Fy, the difference between the target moment Ma and the actual moment M, and the differential coefficients dFx, dFy, and dM. Force correction amount δFx, lateral force correction amount δFy
, The moment correction amount δM is calculated, and the longitudinal force, the lateral force,
The present target slip ratio Si is calculated by calculating the correction amount δSi of the slip ratio of each wheel for achieving the moment correction amount, and correcting the previously calculated target slip ratio with the slip ratio correction amount δSi. If necessary, the target slip ratio Si is corrected, and the braking force of each wheel is controlled so that the actual slip ratio of each wheel becomes the target slip ratio.

In particular, the electric control device 30 of this embodiment
When calculating the longitudinal force Fxso, the lateral force Fyso, and the moment Mso of the vehicle when the slip ratio Si of each wheel is 0, the static support load Woi (i = fr, fl, rr, rl), the actual longitudinal force Fx, the actual lateral force Fy, and the actual moment Ms of the vehicle when the slip ratio Si of each wheel is the target slip ratio are calculated. Actual supporting load Wi of each wheel considering lateral acceleration
(I = fr, fl, rr, rl).

Next, the motion control of the vehicle in the first embodiment will be described with reference to the flowcharts shown in FIGS. The control according to the general flowchart shown in FIG. 2 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, in step 50, the slip ratio Si of each wheel is set to 0 as an initial value, and in step 100, a signal indicating the wheel speed Vwi or the like is read, and in step 150, Calculates the slip angle βr of the rear wheels according to the routine shown in FIG.

In step 200, the longitudinal force Fx, the lateral force Fy, and the longitudinal force Fx of the vehicle at the target slip ratio calculated in the previous step 500 in accordance with the routine shown in FIG.
The moment M, that is, the present longitudinal force, lateral force, and moment are calculated, and in step 250, the target longitudinal force Fxa, the target lateral force Fya,
The target moment Ma is calculated.

In step 300, the above equations 9 and 1
0, a change in the longitudinal force and a change in the lateral force of each wheel with respect to a small change in the slip ratio are calculated, and the above equation 2
The derivative dF of the longitudinal force of the vehicle according to 1-28 and Equation 32
x, a lateral force derivative dFy, and a moment derivative dM are calculated.

In step 350, target values Fxa, Fxa,
As the deviation between Fya, Ma and the actual values Fx, Fy, M, the correction amount δFx of the longitudinal force of the vehicle, the correction amount δFy of the lateral force, and the correction amount δM of the moment are calculated.

In step 400, the slip ratio correction amount for setting the difference Δ between the current longitudinal force, lateral force, and moment of the vehicle and the target longitudinal force, the target lateral force, and the target moment to zero is expressed by the above equation (34). The correction amount δSi of the slip ratio of each wheel to minimize the evaluation function L expressed by

In step 450, the corrected target slip ratio Si is calculated as the sum (Si + δSi) of the previous target slip ratio Si and the correction amount δSi of the slip ratio calculated in step 400.

In step 500, the target slip ratio Si is corrected as necessary in accordance with the routine shown in FIG. 6, and in step 550, the wheel speed Vwi of each wheel is adjusted.
The actual slip ratio of each wheel is calculated based on
The braking force of each wheel is controlled by the wheel speed feedback so that the actual slip ratio of each wheel becomes the target slip ratio Si.

In step 155 of the routine for calculating the slip angle βr of the rear wheel shown in FIG. 3, the deviation of the lateral acceleration as the deviation Gy−Vγ of the lateral acceleration Gy and the product Vγ of the vehicle speed V and the yaw rate γ, that is, The skid acceleration Vyd of the vehicle is calculated, and the skid speed Vy of the vehicle body is calculated by integrating the skid acceleration Vyd.
The ratio V of the vehicle body slip speed Vy to x (= vehicle speed V)
The slip angle β of the vehicle body is calculated as y / Vx.

In step 160, the rear wheel slip angle βr is calculated in accordance with the following equation 42 by using Lr as the distance between the center of gravity of the vehicle and the rear wheel axle in the vehicle longitudinal direction.

Βr = β−Lrγ / V (42) In step 165, it is determined whether or not the slip angle βr of the rear wheel exceeds the reference value βrc, using the reference value βrc as a positive constant. When a negative determination is made, the process proceeds to step 175, and when a positive determination is made, the process proceeds to step 175.
At 70, the rear wheel slip angle βr is set to a reference value βrc.

Similarly, in step 175, it is determined whether or not the rear wheel slip angle βr is less than -βrc. If a negative determination is made, step 20 is continued.
0, and when a positive determination is made, step 180
Then, the slip angle βr of the rear wheel is set to −βrc.

In step 205 of the routine for calculating the longitudinal force Fx, the lateral force Fy, and the moment M at the target slip ratio shown in FIG. 4, the actual steering angle φf of the front wheels is calculated based on the steering angle φ. In addition, the slip angle βf of the front wheels is calculated according to the following equation 43, where Lf is the distance between the center of gravity of the vehicle and the front wheel axle in the vehicle longitudinal direction.

Βf = −φf + β + Lfγ / V (43) In step 210, the following equation 44 is used based on the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle body, where g is the gravitational acceleration.
Is calculated based on the following equation.

Μ = (Gx ² + Gy ² ) ^1/2 / g (44) In step 215, based on the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle body, each is determined in a manner well known in the art. The load movement amount ΔWi of each wheel is calculated, and the support load Wi of each wheel is calculated as the sum (Woi + ΔWi) of the static support load Woi (constant) of each wheel and the load movement amount ΔWi.

In step 220, the judgment value ξi of the grip state of each wheel is calculated according to the above equation 8, and in step 225, it is judged whether or not the judgment value ξi is positive or 0, ie, if the wheel is It is determined whether or not the vehicle is in the grip state. When the determination is affirmative, the longitudinal force Ftxi and the lateral force Ftyi of each wheel are calculated according to the above equations 1 and 2.
When a negative determination is made, in step 235, the longitudinal force Ftxi and the lateral force Fty of each wheel are calculated according to the above equations 3 and 4.
i is calculated. Steps 225 to 235 are executed for each wheel.

In step 240, the longitudinal force F of the vehicle
The components of each wheel with respect to x, lateral force Fy, and moment M are calculated according to the above equations 11 to 20, and in step 245, the actual longitudinal force Fx, actual lateral force Fy, and actual moment of the vehicle are calculated according to equation 29 above. M is calculated, and then the routine proceeds to step 250.

In step 255 of the routine for calculating the target longitudinal force Fxa, the target lateral force Fya, and the target moment Ma of the vehicle shown in FIG. 5, Kh is used as a stability factor, H is used as a wheelbase, and the following equation 45 is used. The target yaw rate γc is calculated, and the reference yaw rate γt is calculated according to the following equation 46 using T as a time constant and s as a Laplace operator. Incidentally, the target yaw rate γc may be calculated in consideration of the lateral acceleration Gy of the vehicle in consideration of a dynamic yaw rate.

Γc = Vφ / (1 + KhV ² ) H (45) γt = γc / (1 + Ts) (46) In step 260, the drift-out amount DV is calculated according to the following equation 47. Drift out amount DV
May be calculated according to Equation 48 below using H as the wheelbase. DV = (γt−γ) (47) DV = H (γt−γ) / V (48) In step 265, the turning direction of the vehicle is determined based on the sign of the yaw rate γ, and the vehicle is in a drift-out state. Quantity DS
Is calculated as DV when the vehicle is turning left, and as -DV when the vehicle is turning right. When the calculation result is a negative value, the drift-out state amount is set to zero.

In step 270, the coefficient Kg is calculated from the map corresponding to the graph shown in FIG. 7 based on the drift-out state amount DS. In step 275, Km1 and Km2 are each set to a positive constant. The target moment Mt of the behavior control is calculated according to the following equation 49, where βd is the differential value of the slip angle β of the vehicle, and βt and βtd are the differential values of the target slip angle and the target slip angle of the vehicle, respectively. Note that both the target slip angle βt and the derivative value βtd of the target slip angle may be zero.

Mt = Km1 (β−βt) + Km2 (βd−βtd) (49) In step 280, the coefficient K is calculated according to the following equation 50.
The target longitudinal force Fxt for behavior control is calculated as the product of g, the mass Mt of the vehicle, and the gravitational acceleration g.

Fxt = −Kg Mtg (50) In step 285, the slip ratio Si of each wheel is set to 0 in the above equations 1 to 4, and the tire contact load Wi is set.
Is set to the static support load Woi of each wheel, the longitudinal force Ftxi and the lateral force Ftyi of each wheel are calculated, and
According to the formulas 11 to 20, when the slip ratio Si is 0, the longitudinal force Ftxi of each wheel and the longitudinal force Fxiso of the vehicle due to the lateral force Ftyi, lateral force Fyiso, moment Miso (i = f
r, fl, rr, rl), and the longitudinal force Fxso of the vehicle when the slip ratio Si of each wheel is 0 according to the above equation (30).
, Lateral force Fyso, and moment Mso are calculated. In step 290, the target longitudinal force Fxa, lateral force Fya, and moment Ma of the vehicle are calculated according to the above equation 31, and thereafter, the routine proceeds to step 300.

In step 505 of the target slip ratio correction calculation routine shown in FIG.
It is determined whether a is negative, the rear wheel slip angle βr is positive, and the yaw rate γ of the vehicle is positive.
When a negative determination is made, the routine proceeds to step 510, and when an affirmative determination is made, the target slip ratios Srr and Srl of the rear wheels are set to 0 in step 515, and thereafter the routine proceeds to step 550.

In step 510, it is determined whether the target moment Ma is positive, the rear wheel slip angle βr is negative and the vehicle yaw rate γ is negative, and an affirmative determination is made. If the determination is negative, the process proceeds to step 515, and if a negative determination is made, the process directly proceeds to step 55.
Go to 0.

Thus, according to the first embodiment, in step 150, the slip angle βr of the rear wheel is calculated, and in step 200, the present longitudinal force Fx and lateral force Fx of the vehicle are calculated.
y, the moment M is calculated, and the longitudinal force F of the vehicle when the slip ratio Si of each wheel is 0 in step 250
xso, lateral force Fyso, moment Mso and target longitudinal force Fxt and target moment Mt for stabilizing the behavior of the vehicle.
The target longitudinal force Fxa, lateral force Fya, and moment Ma of the vehicle are calculated as the sum of the above and the change in the longitudinal force, lateral force, and moment of the vehicle with respect to the minute change dSi of the slip ratio of each wheel in step 300. Derivative coefficients dFx, dFy, d
M is calculated.

In step 350, the target longitudinal force F
xa and the actual longitudinal force Fx, the difference between the target lateral force Fya and the actual lateral force Fy, the difference between the target moment Ma and the actual moment M, and the differential coefficients dFx, dFy, and dM. Force correction amount δFx, lateral force correction amount δFy
, The correction amount δM of the moment is calculated, and
At 0, the correction amount δSi of the slip ratio of each wheel for achieving the correction amount of the longitudinal force, the lateral force, and the moment is calculated,
In step 450, the target slip rate calculated last time is corrected by the slip rate correction amount δSi to calculate the current target slip rate Si. In step 500, the target slip rate Si is corrected as needed. Then, in step 550, control is performed so that the actual slip ratio of each wheel becomes the target slip ratio.

Therefore, according to this embodiment, the longitudinal force Fx of the vehicle becomes the target longitudinal force Fxa, and the lateral force Fy becomes the target lateral force Fx.
Since the slip ratio of each wheel is controlled so that the moment becomes ya and the moment M becomes the target moment Ma, the movement of the vehicle, particularly, the behavior at the time of turning can be reliably stabilized.

In this case, the longitudinal force Fxso, the lateral force Fyso, and the moment Mso of the vehicle when the slip ratio Si of each wheel is 0 are obtained by setting the supporting load Wi of each wheel to the static supporting load Woi. The slip rate correction amount δSi calculated based on the front-rear force Ftxi and the lateral force Ftyi of each wheel, and calculated according to the above equations 33 to 41, indicates the change in the moment and the change in the lateral force caused by the load movement in the vehicle front-rear direction. Since the control amounts that cancel each other are included, the motion can be favorably controlled without being affected by the change in the moment and the decrease in the lateral force due to the load movement in the vehicle longitudinal direction.

In the first embodiment, the support load Wi of each wheel is set to the static support load Woi in step 285, so that the slip ratio when the slip ratio Si is 0 is set to zero. The longitudinal force Fxso, the lateral force Fyso, and the moment Mso of the vehicle are calculated. Mb is the mass of the vehicle, Hcg is the height of the center of gravity of the vehicle, and Rsf and Rsr are the roll stiffness of the front and rear wheels, respectively. (0 <Rsf <1, R
sr = 1−Rsf), in step 215, the supporting load Wi of each wheel is calculated according to the following equations 51 to 54,
In step 285, the supporting load Wi of each wheel is calculated according to the following equations 51A to 54A, whereby the influence of the longitudinal acceleration Gx, that is, the influence of the load movement in the longitudinal direction of the vehicle may be eliminated.

[0123]

(37)

[0124]

(38)

In the above-described first embodiment, the static support load Woi of each wheel is a constant. However, when the vehicle height sensor is provided on the vehicle suspension, the static support load The Woi may be estimated from the vehicle height when the vehicle is stationary, and when the suspension of each wheel is provided with a load sensor or a pressure sensor for detecting the internal pressure of the shock absorber, the Woi can be estimated. The actual support load Woi and the support load Wi may be calculated based on the detection results of these sensors.

Second Embodiment FIG. 10 is a general flowchart showing a motion control routine according to a second embodiment of the vehicle motion control device according to the present invention. FIG. Actual front-rear force Fx, front wheel lateral force F
FIG. 12 is a flowchart showing a routine for calculating yf, the lateral force Fyr of the rear wheel, and the moment M. FIG. Force Fyra, moment M
It is a flowchart which shows a calculation routine. FIG. 10
12 to 12, the same steps as those shown in FIGS. 2, 4 and 5 are denoted by the same step numbers as those given in these figures.

In this embodiment, steps 50 to 50
150 and steps 450 to 550 are executed in the same manner as in the first embodiment.
0, the longitudinal force Fx of the vehicle at the target slip ratio calculated in the previous step 500 in accordance with the routine shown in FIG.
, Front wheel lateral force Fyf, rear wheel lateral force Fyr, and moment M, that is, the current front-rear force, front wheel lateral force, rear wheel lateral force, and moment are calculated. In step 250, the vehicle is operated according to the routine shown in FIG. Target front-rear force Fxa, front wheel target lateral force F
yfa, the target lateral force Fyra of the rear wheel, and the target moment Ma are calculated.

In step 300, the above equations 9 and 1
0, the change of the longitudinal force and the change of the lateral force of each wheel with respect to the minute change of the slip angle are calculated, and
According to Eqs. 1-28 and equation 32A, the differential coefficient dFx of the longitudinal force of the vehicle and the differential coefficient dF of the lateral force of the front wheel with respect to the minute slip angle changes dSf, dSrr and dSrl of the front wheel, the right rear wheel and the left rear wheel.
yf, derivative of rear wheel lateral force dFyr, derivative of moment dM
Is calculated.

In step 350, the target values Fxa, Fyfa, Fyra, Ma of the longitudinal force, the front wheel lateral force, the rear wheel lateral force, and the moment, and the actual values Fx, Fyf, The correction amount δFx of the longitudinal force of the vehicle, the correction amount δFyf of the front wheel lateral force, as the deviation Δ from Fyr, M,
The correction amount δFyr of the rear wheel lateral force and the correction amount δM of the moment are calculated.

In step 400, the present vehicle longitudinal force, front wheel lateral force, rear wheel lateral force, moment and target longitudinal force,
Of the slip ratio correction amounts that make the difference Δ between the target lateral force of the front wheel, the target lateral force of the rear wheel, and the target moment zero, the slip ratio of each wheel that minimizes the evaluation function L expressed by the above equation (34) Is calculated in accordance with the above equation (35).

Steps 205 to 240 of the flowchart shown in FIG. 11 are executed in the same manner as in the first embodiment. In step 245, the actual longitudinal force Fx and the moment M are added according to the above equation 29A. Thus, actual front wheel lateral force Fyf and rear wheel lateral force Fyr are calculated.

Steps 255 to 280 in the flowchart shown in FIG. 12 are executed in the same manner as in the first embodiment. In step 285, the vehicle when the slip ratio Si is 0 according to the above equation 30A is set. Front-rear force Fxs
o, front wheel lateral force Fyfso, rear wheel lateral force Fyrso, moment Mso
Is calculated, and the target longitudinal force Fx is calculated according to the above equation 31A.
a, the target lateral force Fyfa of the front wheel, the target lateral force Fyra of the rear wheel, and the target moment Ma are calculated.

As described above, according to the second embodiment, the target lateral force Fyfa of the front wheel and the target lateral force Fyra of the rear wheel are individually calculated as the target values of the lateral force of the vehicle, and the target lateral force Fyra of the rear wheel is calculated.
Is controlled so that the target lateral force of the entire vehicle is calculated without distinction between the front and rear wheels due to the movement of the load in the vehicle front-rear direction by the motion control. As a result, it is possible to reliably prevent the lateral force of the rear wheels from being insufficient and to thereby prevent the stability of the vehicle from deteriorating, thereby improving the motion control performance of the vehicle.

In the second embodiment shown in the drawing, the target lateral force Fyfa of the front wheels and the target lateral force Fyra of the rear wheels are individually calculated to improve the motion control performance of the vehicle. However, the target lateral force Fyfa of the front wheel and the target lateral force Fyra of the rear wheel are individually calculated, and the weight coefficient Wsr for the rear wheel slip rate in the above equation 40 is calculated from the weight coefficient Wsf for the front wheel slip rate. May be set large. In this case, the rate of increase of the evaluation function L with the increase of the slip rate of the rear wheel increases, so that the braking force of the rear wheel becomes excessive and the lateral force of the rear wheel greatly decreases. It is possible to further reduce the risk of occurrence.

As in the case of the motion control device according to the above-mentioned proposal and the first embodiment, the target lateral force Fyfa of the front wheel and the target lateral force Fyra of the rear wheel are not calculated individually. In the configuration in which the target lateral force Fya of the entire vehicle is calculated, the weight coefficient Wsr for the slip rate of the rear wheel in the above equation 40 may be set to be larger than the weight coefficient Wsf for the slip rate of the front wheel. Also in this case, it is possible to effectively prevent the braking force on the rear wheel from becoming excessive and the lateral force on the rear wheel from being greatly reduced.

Third Embodiment FIG. 13 is a general flowchart showing a motion control routine in a vehicle motion control device according to a third embodiment of the present invention. In FIG. 13, the same steps as those shown in FIG. 2 are denoted by the same step numbers as those shown in FIG.

In this embodiment, steps 50 to 50
Steps 250, 350, 500, and 550 are executed in the same manner as in the first embodiment. In step 300, the change in the longitudinal force and the lateral force of each wheel with respect to the minute change in the slip rate is calculated according to the above equations 9 and 10. The change in force is calculated, and the differential coefficient dFx of the longitudinal force of the vehicle, the differential coefficient dFy of the lateral force, and the differential coefficient of the moment with respect to the minute slip rate changes dSfr and dSfl of the left and right front wheels are calculated according to the equations 21 to 28 and 32B. The coefficient dM is calculated.

In step 400, among the slip ratio correction amounts of the left and right front wheels for making the difference Δ between the current longitudinal force, lateral force, moment of the vehicle and the target longitudinal force, target lateral force, target moment zero, The correction amounts δSfr and δSfl of the left and right front wheel slip ratios that minimize the evaluation function L expressed by Expression 34 are calculated according to Expression 35 above.

In step 405, a map corresponding to the graph shown in FIG. 14 based on the absolute value of the yaw rate γ of the vehicle is set such that the magnification K (0 <K ≦ 1) decreases as the turning degree of the vehicle increases. Then, the magnification K is calculated.

In step 450, the previous target slip rates Sfr and Sfl for the left and right front wheels and the correction amount δSfr of the slip rate calculated in step 400, respectively,
The corrected target slip ratios Sfr, Sfl are calculated as the sum of δSfl (Sfr + δSfr, Sfl + δSfl), and the previous target slip ratios Srr, Srl and the corrected amounts of the slip ratios calculated in step 400 for the left and right rear wheels, respectively. δ
Sum of Sfr and δSfl with K times (Srr + KδSrr, Srl + K
The corrected target slip ratios Srr and Srl are calculated as δSrl).

Thus, according to the third embodiment, the right and left front wheel slip ratio correction amounts for setting the difference Δ between the current longitudinal force, lateral force, moment of the vehicle and the target longitudinal force, target lateral force, target moment to 0 are zero. The correction amounts δSfr and δSfl of the left and right front wheels that minimize the evaluation function L are calculated, and the previous target slip ratios Sfr and Sfl for the left and right front wheels are respectively calculated.
The corrected target slip ratios Sfr and Sfl are calculated as the sum of the corrected slip ratios δSfr and δSfl, and the previous target slip ratios Srr and Srl and the corrected slip ratios δSfr and δSfl for the right and left rear wheels, respectively. The corrected target slip ratios Srr and Srl are calculated as the sum of K times and the magnification K is a value larger than 0 and equal to or smaller than 1, so that the target slip ratio of the rear wheel becomes excessive and the lateral slip of the rear wheel is increased. It is possible to reduce the possibility of insufficient power, thereby improving the motion control performance of the vehicle, and reduce the calculation load of the electric control device for matrix calculation.

In particular, according to the illustrated embodiment, the magnification K is variably set in accordance with the absolute value of the yaw rate γ so that the higher the turning degree of the vehicle, the smaller the magnification K. Is set to a constant value, the abrupt change of the magnification K in a situation where the turning degree of the vehicle changes can be prevented, and the motion control of the vehicle can be favorably performed.

In the illustrated embodiment, the magnification K is variably set in accordance with the absolute value of the yaw rate γ such that the magnification K decreases as the turning degree of the vehicle increases. The magnification K may be set to a constant value, for example, 1 and 0.2, respectively, when the vehicle is traveling straight and when turning, so that the magnification when the vehicle is traveling straight is smaller than the magnification when the vehicle is traveling straight.

According to each of the above-described embodiments, the slip ratio correction amount δSi of each wheel is calculated by subtracting the difference Δ between the current longitudinal force, lateral force, and moment of the vehicle from the target longitudinal force, the target lateral force, and the desired moment. Is calculated according to the above equation 35 as the amount of slip rate correction of each wheel that minimizes the evaluation function L expressed by the above equation 34 among the slip rate correction quantities to be calculated. There is no need to set a large number of maps showing the correspondence between the slip ratio of each wheel and the longitudinal force, lateral force, and moment for stabilizing the motion of the vehicle. This makes it easy to configure the motion control device. In addition, the target slip ratio can be calculated more quickly than when the slip ratio Si of each wheel that achieves the target longitudinal force, the target lateral force, and the target moment is calculated by analysis. Respond to exercise It is not can be appropriately controlled.

When the target state quantity for stabilizing the motion of the vehicle is only the target longitudinal force and the target moment, the decrease in the lateral force is not taken into account, so that the course tracing property of the vehicle is likely to deteriorate. According to the illustrated embodiment, the target lateral force is considered in addition to the target longitudinal force and the target moment, so that it is possible to reliably avoid the deterioration of the course tracing property of the vehicle due to the decrease in the lateral force.

As shown in FIG. 8, the rear wheel 10RR
When the magnitude of the slip angle βr at 10 RL is large, the target slip ratios Srr and Srl become high even when a small longitudinal force is applied to the rear wheels, and the turning direction is reversed in such a situation. Then, the wheel speed of the rear wheel is too low, and the vehicle easily spins.

According to each of the above embodiments, step 16
When the slip angle βr of the rear wheel is large in the range of 5 to 180, the slip angle βr of the rear wheel becomes the reference value βrc or −
Since step 200 and subsequent steps are executed with βrc set, the target slip ratios Srr and Srl of the rear wheels may be calculated to be high even when the actual slip angle of the rear wheels is large. Therefore, even when the turning direction of the vehicle is reversed, it is possible to reliably prevent the vehicle from spinning due to the rear wheel speed being too low.

Further, as shown in FIG. 9, when the sign of the target moment Ma and the sign of the slip angle βr of the rear wheel are opposite, the lateral force Fyrr, Fyrl of the rear wheel is reduced to achieve the target moment. When the target slip ratios Srr and Srl of the rear wheels are calculated to be high values and the sign of the slip angle of the rear wheels reverses in such a situation, the direction of the lateral force of the rear wheels also reverses. However, since the target slip ratio of the rear wheel is high and the lateral force of the rear wheel is small, the target moment is not achieved, so that the target slip ratio of the rear wheel sharply decreases, and such a sudden change in the target slip ratio of the rear wheel is reduced. If this occurs during the reversal of the turning direction, the reduction of the braking force on the rear wheels cannot be made in time, and the spin of the vehicle will be promoted.

On the other hand, according to each of the above-described embodiments, if it is determined in step 505 or 510 that the signs of the target moment and the sign of the rear wheel slip angle have the opposite relationship, then in step 515, Wheel target slip ratio Srr
And Srl are each reduced to 0, so that even if the sign of the slip angle of the rear wheel is reversed, the target slip ratio does not change abruptly, and the spin of the vehicle is reduced due to a delay in reducing the braking force of the rear wheel. It is possible to reliably avoid being promoted.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the above-described embodiment, in step 250, the target longitudinal force Fxa and the target lateral force Fy of the vehicle are set.
a, the target lateral force of the behavior control is set to 0 in Equation 31 for calculating the target moment Ma. However, the target lateral force Fyt of the behavior control is a positive constant of Ky1 and Ky2. In the same way as the target moment Mt,
5, the target longitudinal force Fxa, the target lateral force Fya, and the target moment Ma of the vehicle may be calculated according to the following equation 56.

Fyt = Ky1 (β−βt) + Ky2 (βd−βtd) (55)

[0153]

[Equation 39]

In the above embodiment, the actual slip ratio of each wheel is controlled to the target slip ratio Si by controlling the braking force of each wheel in step 550. However, the braking force or the driving force of each wheel may be controlled by controlling the output of an engine (not shown).

Further, in the above-described embodiment, the target longitudinal force Fxt and the target moment Mt of the behavior control are determined in step 2.
55 to 280. The target longitudinal force Fxt and the target moment Mt of the behavior control or the target longitudinal force Fxt, the target lateral force Fyt, and the target moment My of the behavior control are defined in the art. The calculation may be performed in any known manner.

[0156]

As is apparent from the above description, according to the configuration of the first aspect of the present invention, the control amount of each wheel can be controlled to the target control amount with high accuracy without requiring a large number of maps. Not only stabilizes the motion of the vehicle reliably and properly, but also calculates the target control amount of each wheel in which the change in the yaw moment and the decrease in the lateral force due to the load movement in the longitudinal direction of the vehicle are offset. Thereby, the motion control performance of the vehicle can be improved as compared with the motion control device according to the above-mentioned proposal.

According to the structure of claim 2, the control amount of each wheel is controlled to the target control amount with high accuracy without requiring a large number of maps, thereby stably and appropriately stabilizing the motion of the vehicle. Not only can the weight factor for the front wheel slip rate be greater than the weight coefficient for the rear wheel slip rate, or when the weight factor for the rear wheel is the same, the weight factor for the rear wheel slip rate increases. Since the rate of increase of the evaluation function is high, it is possible to prevent the braking force on the rear wheel from becoming excessive and the lateral force on the rear wheel from being greatly reduced. As a result, the motion control performance of the vehicle can be improved.

According to the third aspect of the present invention, the control amount of each wheel is controlled to the target control amount with high accuracy without requiring a large number of maps, whereby the movement of the vehicle is reliably and appropriately stabilized. In addition to the above, it is possible to calculate the target control amount of each wheel so as to realize the lateral force target value of the rear wheel, and therefore, the vehicle can be compared with the case where the target value of the lateral force of the entire vehicle is calculated. To reduce the possibility that the lateral force of the rear wheel becomes insufficient due to the load movement in the front-rear direction, thereby improving the motion control performance of the vehicle as compared with the motion control device according to the above-mentioned proposal. Can be.

According to the structure of claim 4, the control amount of each wheel is controlled to the target control amount with high accuracy without requiring a large number of maps, thereby stably and appropriately stabilizing the motion of the vehicle. Not only that, the correction amount of the front wheel target control amount is calculated based on the difference between the current vehicle state amount and the target value, and the front wheel target amount is calculated as the sum of the previous front wheel target control amount and the front wheel correction amount. The control amount is calculated, the correction amount of the front wheel is multiplied by a predetermined magnification, and the correction amount of the target control amount of the rear wheel is calculated.The rear wheel is calculated as the sum of the previous target control amount of the rear wheel and the correction amount of the rear wheel. Since the target control amount of the rear wheel is calculated, the possibility that the target control amount of the rear wheel becomes excessive and the lateral force of the rear wheel becomes insufficient is reduced,
Thereby, the motion control performance of the vehicle can be improved as compared with the motion control device according to the above-mentioned proposal.

According to the fifth aspect of the present invention, since the ratio of the target control amount of the rear wheel to the target control amount of the front wheel is different between when the vehicle goes straight and when turning, the ratio of the target control amount of the rear wheel is different from that when turning. In this case, the motion control can be optimally performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle motion control device according to the present invention.

FIG. 2 is a general flowchart showing a motion control routine according to the first embodiment.

FIG. 3 is a step 15 of the flowchart shown in FIG. 2;
7 is a flowchart showing a rear wheel slip angle βr calculation routine at 0.

FIG. 4 is a step 20 of the flowchart shown in FIG. 2;
Actual longitudinal force Fx at 0, lateral force Fy, moment M
9 is a flowchart illustrating an arithmetic routine.

FIG. 5 is a step 25 of the flowchart shown in FIG. 2;
Target longitudinal force Fxa, lateral force Fya, moment Ma at zero
9 is a flowchart illustrating an arithmetic routine.

FIG. 6 shows a step 50 of the flowchart shown in FIG. 2;
7 is a flowchart showing a target slip ratio Si calculation routine at 0.

FIG. 7 is a graph showing a relationship between a drift-out state amount DV and a coefficient Kg.

FIG. 8 is an explanatory diagram showing a situation where the magnitude of the slip angle βr of the left and right rear wheels is large.

FIG. 9 shows a target moment Ma and a rear wheel slip angle βr.
It is explanatory drawing which shows the situation in which the code | symbol of the opposite has a reverse relationship.

FIG. 10 is a general flowchart showing a motion control routine according to the second embodiment.

11 is a flowchart showing an actual longitudinal force Fx, front wheel lateral force Fyf, rear wheel lateral force Fyr, and moment M calculation routine in step 200 of the flowchart shown in FIG.

12 is a diagram showing a target longitudinal force Fxa and a target lateral force Fyfa of a front wheel in step 250 of the flowchart shown in FIG.
Is a flowchart showing a routine for calculating a target lateral force Fyra and a moment Ma of a rear wheel.

FIG. 13 is a general flowchart showing a motion control routine in a vehicle motion control device according to a third embodiment of the present invention.

FIG. 14 is a graph showing a relationship between an absolute value of a yaw rate γ of a vehicle and a magnification K.

FIG. 15 is an explanatory diagram showing an angle θi and the like formed by a tire generated force Fti with respect to a lateral direction of the tire.

FIG. 16 is a graph showing the relationship between the tire slip angle βi and the lateral force Ftyi when the slip ratio is zero.

FIG. 17 is a graph showing the relationship between the tire slip ratio Si and the longitudinal force Ftxi when the slip angle βi is 0.

[Explanation of symbols]

 10FR-10RL Wheel 20 Braking device 28 Master cylinder 30 Electric control device 32FR-32RL Wheel speed sensor 34 Steering angle sensor 36 Yaw rate sensor 38 Front-back acceleration sensor 40 Lateral acceleration sensor 42 Vehicle speed sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshikazu Hattori 41-1, Oku-cho, Yokomichi, Nagakute-machi, Aichi-gun, Aichi F-term in Toyota Central R & D Laboratories Co., Ltd. 3D045 BB40 GG00 GG10 GG11 GG25 GG26 GG27 GG28 3D046 BB31 BB32 HH00 HH08 HH22 HH25 HH26 HH29 HH36 JJ06

Claims (5)

[Claims] A means for calculating, from a tire model, a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control amount; and setting a target value of a vehicle state quantity for stabilizing the motion of the vehicle to a vehicle model or a driver. Means for calculating a target control amount of each wheel that achieves the target value by convergence calculation using the derivative and the target value, and wheel operation to achieve the target control amount. A vehicle motion control device having means for controlling the device, the vehicle control device further comprising estimating means for estimating an actual supporting load of each wheel, wherein the target value of the vehicle state quantity is when the slip ratio of each wheel is 0. Is calculated as the sum of the target value of the vehicle state quantity and the target value of the vehicle state quantity for stabilizing the behavior of the vehicle, and the target control amount of each wheel is a deviation between the target value and the actual vehicle state quantity. Is calculated based on The vehicle state quantity at that time is calculated based on the actual supporting load of each wheel estimated by the estimating means, and the target value of the vehicle state quantity when the slip ratio of each wheel is 0 is the static support of each wheel. A motion control device for a vehicle, which is calculated based on a load. 2. A means for calculating, from a tire model, a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control amount, and a target value of a vehicle state quantity for stabilizing the motion of the vehicle is determined by a vehicle model or a driver. Means for calculating the target slip rate of each wheel that achieves the target value by convergence calculation using the differential coefficient and the target value, and wheel operation to achieve the target slip rate. Means for controlling the apparatus, wherein the means for calculating the target slip rate of each wheel includes "the deviation between the actual vehicle state quantity and its target value" and "the difference between the differential coefficient and the change amount of the target slip rate." Product), the amount of change in the target slip rate, and the amount of change in the target slip rate of each wheel so that the value of the evaluation function consisting of the sum of squares of the sum of the target slip rate and the change is minimized. Calculated by convergence operation In the motion control apparatus for a vehicle that corrects the previously calculated target slip rate based on the amount of change in the target slip rate, the weight coefficient for the rear wheel slip rate of the evaluation function is the weight coefficient for the front wheel slip rate. A motion control device for a vehicle, wherein the motion control device is larger than the vehicle. 3. A means for calculating, from a tire model, a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control amount, and a target value of a vehicle state quantity for stabilizing the movement of the vehicle is determined by a vehicle model or a driver. Means for calculating a target control amount of each wheel that achieves the target value by convergence calculation using the derivative and the target value, and wheel operation to achieve the target control amount. Wherein the target value of the vehicle state quantity independently includes a target value of the front wheel lateral force and a target value of the rear wheel lateral force. Vehicle motion control device. 4. A means for calculating, from a tire model, a differential coefficient of a change in a vehicle state quantity with respect to a small change in a wheel control amount, and a target value of a vehicle state quantity for stabilizing the movement of the vehicle is determined by a vehicle model or a driver. Means for calculating a target control amount of each wheel that achieves the target value by convergence calculation using the derivative and the target value, and wheel operation to achieve the target control amount. Means for controlling the apparatus, wherein the means for calculating the target control amount for each wheel is a correction of the target control amount for the front wheels based on the difference between the current vehicle state amount and the target value. The control amount of the front wheel is calculated as a sum of the previous target control amount of the front wheel and the correction amount of the front wheel, and the correction amount of the front wheel is multiplied by a predetermined magnification to calculate the target control amount of the rear wheel. Calculate the amount of correction, and Vehicle motion control apparatus characterized by calculating a target control amount of the rear wheel target control amount and the sum of the correction amount of the rear wheel. 5. The vehicle motion control device according to claim 4, wherein the predetermined magnification is different between when the vehicle is traveling straight and when it is turning.