JP2007223390A - Behavior control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a behavior control device of a vehicle carrying out vehicle behavior stabilizing control by independently controlling front and rear wheels in accordance with a state estimated value of the front wheels and a state estimated value of the rear wheels by independently estimating the state of the front wheels and the state of the rear wheels. <P>SOLUTION: This behavior control device of the vehicle to control a turning behavior of the vehicle in accordance with a state of the vehicle is furnished with a lateral force sum computing means to independently compute lateral force sums of the front wheels and the rear wheels and a control means to independently control tire working force of the front wheels and the rear wheels in accordance with the respective computed lateral force sums of the front wheels and the rear wheels. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle behavior control apparatus.

Conventionally, as a vehicle behavior control device using yaw angular acceleration, there has been disclosed a control device that improves the course following performance when turning by adjusting the rear wheel turning angle of the vehicle according to the yaw angular acceleration of the vehicle. (For example, refer to Patent Document 1). In addition, by adjusting the driving force distribution of the left and right wheels so that the yaw angular acceleration matches a predetermined target value, stable vehicle turning performance independent of the road surface condition is realized (for example, see Patent Document 2). ). Furthermore, there is also shown a method for realizing vehicle behavior that reduces the driver's anxiety by adjusting the left and right braking force so that the yaw angular acceleration does not exceed a predetermined value (for example, patents). Reference 3).
JP 60-193773 A JP-A-10-84605 JP-A-1-237252

  However, in the above prior art, since the vehicle behavior is controlled according to the sum of the yaw angular acceleration at the front wheels and the yaw angular acceleration at the rear wheels, the yaw angular acceleration of each of the front and rear wheels changes independently. Even in this case, if the sum of the front wheel yaw angular acceleration and the rear wheel yaw angular acceleration does not change, the same control is eventually performed. Therefore, there is a problem that it is impossible to perform highly accurate control in accordance with the yaw angular acceleration unique to the front and rear wheels.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to estimate the state of the front wheel and the state of the rear wheel independently, and to estimate the state of the front wheel and the state of the rear wheel. An object of the present invention is to provide a vehicle behavior control device that performs vehicle behavior stabilization control by independently controlling front and rear wheels.

  To achieve the above object, according to the present invention, in the vehicle behavior control device for controlling the turning behavior of the vehicle based on the vehicle state, the lateral force sum calculating means for independently calculating the lateral force sum of the front wheels and the rear wheels; The control means for independently controlling the tire acting force of the front wheel and the rear wheel based on the calculated lateral force sum of the front wheel and the rear wheel.

  Therefore, by independently estimating the front wheel lateral force sum and the rear wheel lateral force sum, it becomes possible to independently control the front wheels and the rear wheels in accordance with the respective states, and the vehicle that realizes higher-precision control. A behavior control device can be provided.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for realizing a vehicle state estimation and control apparatus according to the present invention will be described below based on an embodiment shown in the drawings.

[System configuration]
The first embodiment will be described with reference to FIGS. FIG. 1 is a system configuration diagram of an electric vehicle in which four wheels are driven by independent electric motors. The electric vehicle includes three-phase synchronous motors 3FL, 3FR, 3RL, and 3RR each having a permanent magnet provided on a rotor. Each motor 3FL to 3RR is connected to each wheel 2fl, 2fr via speed reducers 4fl, 4fr, 4rl, 4rr. 2rl and 2rr. The output characteristics, the reduction ratio, and the wheel radius of each motor 3FL to 3RR, each speed reducer 4fl to 4rr, and each wheel 2FL to 2RR are the same.

  The front wheels 2fl and 2fr are directly steered via the steering rack 14 by the steering force to the steering wheel 11, and the steering rack 14 is displaced in the vehicle width direction as a whole by the auxiliary steering motor 12 (actuator). At the auxiliary steering. That is, the turning angle of the front wheels 2fl and 2fr is the sum of the main turning angle by the steering wheel 11 and the auxiliary turning angle DF by the auxiliary turning motor 12. The auxiliary turning angle DF is controlled by the control circuit 13 so as to match the target auxiliary turning angle tDF (the tire acting force of the front wheels) transmitted by the integrated controller 30 by adjusting the output of the auxiliary turning motor 12. Is done.

  The rear wheels 2RL and 2RR are steered by displacing the steering rack 15 as a whole in the vehicle width direction by a steering motor 16 (actuator). The turning angle is controlled by the control circuit 17 to adjust the output of the turning motor 16 so as to coincide with the rear wheel turning angle command value tDR (rear wheel tire acting force) transmitted by the integrated controller 30. The Further, the turning angle δ of each of the wheels 2FL to 2RR is detected by the turning angle sensor 21 and output to the integrated controller 30.

  The integrated controller 30 is an arithmetic unit that calculates torque command values tTFL (left front wheel), tTFR (right front wheel), tTRL (left rear wheel), and tTRR (right rear wheel). In addition to the detection values from the yaw rate sensor 8, the turning angle sensor 21, the brake pedal sensor 22, the accelerator pedal sensor 23, the lateral acceleration sensors 24 and 25, the longitudinal acceleration sensor 26, and the vehicle slip angle sensor 29, the current motor 3FL The current rotation speed and output torque of ~ 3RR are input. Further, an actual auxiliary turning angle value and an actual rear wheel turning angle value of the front wheel turning angle are input from the control circuits 13 and 17.

  Here, the vehicle body slip angle sensor 29 is a type of sensor that detects the vehicle longitudinal slip angle and the vehicle body side slip angle from the ratio of the two spatial filter type speed detectors (by means of the ratio of the longitudinal and lateral slip velocity of the vehicle). (Point P in FIG. 3).

  Based on these input values, the integrated controller 30 calculates torque command values tTFL (left front wheel), tTFR (right front wheel), tTRL (left rear wheel), tTRR (right rear wheel) for the motors 3FL to 3RR. Also, the auxiliary turning angle command value tDF and the rear wheel turning angle command value tDR for the front wheel turning angle are calculated and output to the control circuit 13 and the control circuit 17, respectively.

  The drive circuits 5FL to 5RR control the power running and regenerative torque of the motors 3FL to 3RR by controlling the electric power of the battery 6 based on the torque command values tTFL to tTRR from the integrated controller 30.

[Front and rear wheel command values (torque and turning angle) calculation control]
In order to perform high-precision control according to the unique state of the front and rear wheels, the front wheel lateral force sum and the rear wheel lateral force sum are estimated, and the front wheel state and the rear wheel state are estimated separately. Each wheel load Wfl to Wrr, each wheel braking drive road surface reaction force Fxfl to Fxrr, front and rear wheel lateral force sums Fy_f, Fy_r, etc. are estimated, and each wheel motor torque command value tTFL to tTRR is calculated based on these values. In addition, the front wheel auxiliary steering is calculated based on the slip angles αfl to αrr by calculating the slip angles αfl to αrr of the front and rear wheels 2FL to 2RR from the front and rear wheel lateral force sums Fy_f, Fy_r and the front and rear wheel steering angles δf, δr. The angle command value tDF and the rear wheel turning angle command value tDR are calculated, and the front and rear wheels are controlled independently.

[Front and rear wheel command values (torque and turning angle) calculation control processing]
FIG. 2 is a main flowchart of a torque command value calculation control process executed by the integrated controller 30. Hereinafter, each step will be described.

  In step S201, each sensor signal and data is captured. That is, the detected values of accelerator opening APS, brake pedal force BRK, steering angle STR, lateral acceleration YG1, YG2, longitudinal acceleration XG, and yaw rate γ are taken in, and the rotational speeds Nfl to Nrr and torque command values of the motors 3FL to 3RR are taken. The current value data of TFL to TRR is fetched and the process proceeds to step S202. The lateral accelerations YG1 and YG2 are two detection values of the two lateral acceleration sensors 24 and 25.

In step S202, the vehicle speed V is calculated by the following equation, and the process proceeds to step S203.
(Formula 1)
V = (Nfl / GG * R + Nfr / GG * R + Nrl / GG * R + Nrr / GG * R) / 4
Here, R is the radius of each wheel fl to rr, and GG is the reduction ratio of the reducers 4fl to 4rr.

  In step S203, vehicle conditions such as the weight of each wheel, the braking / driving road surface reaction force of each wheel, the lateral force sum Fy_f of the front left and right tires, the lateral force sum Fy_r of the rear left and right tires are estimated, and the process proceeds to step S204.

  In step S204, motor torque command values TFL to TRR for the respective wheels 2FL to 2RR are calculated based on the accelerator opening APS, the brake pedaling force BRK, the steering angle STR, the vehicle speed V, etc., and output to the drive circuits 5FL to 5RR to be output to step S205. Migrate to

  In step S205, the slip angles αfl to αrr of the front and rear wheels 2FL to 2RR are calculated from the front and rear wheel lateral force sums Fy_f and Fy_r, the front and rear wheel steering angles δfl and δrr, and the front wheel auxiliary steering based on the slip angles αfl to αrr. The angle command value tDF and the rear wheel turning angle command value tDR are calculated and output to the control circuits 13 and 17, respectively, and the control is terminated.

[Vehicle condition estimation]
FIG. 3 is a diagram showing the relationship between the vehicle behavior parameters related to the vehicle state estimation in step S203 in the flow of FIG. Based on the steering angle STR, the brake pedal force BRK, and the lateral accelerations YG1 and YG2 detected by the turning angle sensor 21, the brake pedal sensor 22, and the lateral acceleration sensors 24 and 25, the turning angle δ, the braking / driving road surface reaction force Fx, The yaw moment MM and the lateral force YG are calculated, and based on this, the front and rear wheel lateral force sums Fy_f and Fy_r are calculated.

(Calculation of turning angle)
Since the vehicle in the present application is a front wheel steering type, the rear wheel turning angles δrl and δrr are only the auxiliary steering angle DR. Therefore, the values of the front wheel turning angles δfl and δfr corresponding to the steering angle STR to the steering wheel 11 are read from the front wheel and rear wheel turning angle-steering angle maps MAP_STRfl and MAP_STRF, and are calculated as follows. Here, DF is the front wheel auxiliary rudder angle, and DR is the rear wheel auxiliary rudder angle.
(Formula 2)
δfl = MAP_STRF (STR) + front wheel auxiliary rudder angle value DF
δfr = MAP_STRF (STR) + front wheel auxiliary rudder angle value DF
δrl = DR
δrr = DR

(Calculation of braking / driving road surface reaction force)
The braking / driving road surface reaction forces Fxfl to Fxrr are estimated from the motor torque command values TFL to TRR and the rotational speed variation of each wheel 2FL to 2RR. As a specific estimation method, for example, a method disclosed in JP-A-6-98418 (Formula 11) is used. In particular, when using a mechanical brake, the front and rear wheel braking force maps are read from the brake pedal force BRK value, and the braking torque TBL_FBR (BRK) and TBL_RBR (BRK) are combined with the motor torque TFL to TRR. The driving road surface reaction forces Fxfl to Fxrr are calculated. Further, when the anti-skid braking system is operated, a braking torque decrease due to the system operation is detected, and the braking torque is corrected.

(Calculation of yaw angular acceleration and lateral acceleration)
FIG. 4 is a diagram showing the relationship between the lateral acceleration YG and each vehicle behavior parameter in the vehicle behavior control in step S203 in the flow of FIG. The lateral force Fy is positive when the vehicle travels to the left. When the installation position of the lateral acceleration sensor is the position shown in FIG. 4, the yaw angular acceleration γ ′ (unit is rad / s ² , counterclockwise is positive) and the lateral acceleration YG at the center of gravity (unit is m / s ² , where the left direction of the vehicle is positive) is obtained as follows.
(Formula 3)
γ '= (YG2-YG1) / L2
YG = YG1 + (YG2-YG1) * Lc / L2

(Calculation of lateral force and yaw moment)
From the yaw angular acceleration γ 'and the lateral acceleration YG value, the lateral force Fy and yaw moment MM acting on the vehicle are calculated using the vehicle yaw inertia design value I _γ [kgm ² ] and vehicle mass design value M [kg] Calculate as follows.
(Formula 4)
Fy = M * YG
MM = I _γ * γ '

ここでLf は前輪軸重心点距離[m]、Lr は後輪軸重心点距離[m]、Lt はトレッドベース距離(前後輪同一)[m]であり、それぞれ設計定数である。
上記数式５の第３項の影響は小さいものとして無視し、(Fyfl+Fyfr)および(Fyrl+Fyrr)を次のように求める。
（数式６）

ここでδfとして(δfl+δfr)/2を用い、δrとして(δrl+δrr)/2を用いることとし、(Fyfl+Fyfr)を第１前輪横力和Fy_f、(Fyrl+Fyrr)を第１後輪横力和Fy_rに代入する。
なお、上記数式６の近似式として以下の数式７を用いてもよいし、前輪転舵角δfおよび後輪転舵角δrが十分小さいとして以下の数式８などを用いてもよい。
（数式７）

（数式８）

(Calculation of left and right lateral force sum of front and rear wheels)
As shown in FIG. 3, the lateral force generated at the left front wheel is Fyfl, the lateral force generated at the right front wheel is Fyfr, the lateral force generated at the left rear wheel is Fyrl, and the lateral force generated at the right rear wheel is Fyrr, If the left and right turning angles of the front wheels are equal (δfl = δfr = δf) and the left and right turning angles of the rear wheels are equal (δrl = δrr = δr), the following relational expression is given for the lateral force Fy and yaw moment MM acting on the vehicle: Holds.
(Formula 5)

Here, Lf is the front wheel center of gravity distance [m], Lr is the rear wheel center of gravity center distance [m], and Lt is the tread base distance (same front and rear wheels) [m], which are design constants.
The influence of the third term of Equation 5 is ignored as being small, and (Fyfl + Fyfr) and (Fyrl + Fyrr) are obtained as follows.
(Formula 6)

Here, (δfl + δfr) / 2 is used as δf, (δrl + δrr) / 2 is used as δr, (Fyfl + Fyfr) is the first front wheel lateral force sum Fy_f, and (Fyrl + Fyrr) is the first. Substitute in the rear wheel lateral force sum Fy_r.
The following expression 7 may be used as an approximate expression of the above expression 6, or the following expression 8 may be used on the assumption that the front wheel turning angle δf and the rear wheel turning angle δr are sufficiently small.
(Formula 7)

(Formula 8)

ここで、hは重心高[m]、Ltはトレッド幅[m]である。そして、これらの値に基づき、以下の式で各輪の輪荷重を演算する。
（数式１１）

この方法以外に、センサを用いて検出した輪荷重値を用いても良い。 (Calculation of each wheel load)
The front wheel load Wf when the vehicle is stationary and the rear wheel load Wr (unit is N) when the vehicle is stationary are calculated by the following equations.
(Formula 9)
Wf = M * Lr / (Lf + Lr) /2*9.8
Wr = M * Lf / (Lf + Lr) /2*9.8
Next, the front-rear wheel load movement amount ΔWd and the left-right wheel load movement amount ΔWc are calculated as follows from the vehicle longitudinal acceleration XG and the lateral acceleration YG at the center of gravity obtained by Expression 5.
(Formula 10)

Here, h is the center of gravity height [m], and Lt is the tread width [m]. Based on these values, the wheel load of each wheel is calculated by the following equation.
(Formula 11)

In addition to this method, a wheel load value detected using a sensor may be used.

[Vehicle state estimation processing]
FIG. 5 is a routine of the vehicle state estimation process executed in step S203 of FIG. Hereinafter, each step will be described.

  In step S401, each wheel turning angle δfl to δrr is calculated, and the process proceeds to step S402.

  In step S402, each wheel drive road surface reaction force Fxfl to Fxrr is calculated, and the process proceeds to step S403.

  In step S403, yaw moment MM and lateral force YG are calculated, and the process proceeds to step S404.

  In step S404, first front and rear wheel lateral force sums Fy_f and Fy_r are calculated, and the process proceeds to step S405.

  In step S405, the wheel loads Wfl to Wrr are calculated, and this routine ends.

[Motor torque command value calculation control]
In the motor torque command value calculation control in step S204 of FIG. 2, first, the target driving force tTD of the vehicle is read from the vehicle speed-accelerator opening degree map MAP_tTD (see FIG. 6).

Next, motor torque command values tTFL to tTRR of the wheels 2FL to 2RR are calculated based on the following formula. Note that tU is determined by reading the V-tU map of FIG. 7 based on the target driving force vehicle speed and the steering amount STR.
(Formula 12)
Left front, rear wheel tTFL, tTRL = tTD * R / GG / 4-tU * R / GG / 4
Right front, rear wheel tTFR, tTRR = tTD * R / GG / 4 + tU * R / GG / 4
Here, GG is a reduction ratio in the reduction gears 4fl to 4rr. The yaw rate γ and the vehicle lateral acceleration YG may be corrected so as to have a desired transient response, and are not particularly limited. For the correction method, refer to Chapter 8 of “Moving and Control of Vehicles (Sankaido, Author: Masato Abe)”. After the calculation, the motor torque command values tTFL to tTRR of the wheels 2FL to 2RR are output to the motor drive circuit.

[Motor torque command value calculation control process]
FIG. 8 is a motor torque command value calculation control processing routine. Hereinafter, each step will be described.

  In step S601, the target driving force tTD is calculated, and the process proceeds to step S602.

  In step S602, motor torque command values tTFL to tTRR for the wheels 2FL to 2RR are calculated, and the process proceeds to step S603.

  In step S603, motor torque command values tTFL to tTRR for the wheels 2FL to 2RR are output, and this routine is terminated.

[Each wheel turning angle limit control]
The lateral force of a wheel basically has a characteristic of increasing as the side slip angle increases, but it tends to decrease as the side slip angle increases beyond a certain side slip angle S (the vehicle bends if the tire is steered too much). It becomes difficult.) Therefore, in this embodiment, according to the estimated value of the front and rear wheel slip angle, the steer angle is limited according to the road surface friction coefficient and the vehicle condition so that the tire side slip angle that causes the sum of the front and rear wheel lateral forces to decrease does not occur. Control.

(Calculation of each wheel slip angle)
The slip angles αfl to αrr of the wheels 2FL to 2RR with respect to the vehicle slip angle β are calculated by the following equation. The relationship between the vehicle slip angle β and the wheel slip angles αfl to αrr is roughly as follows. Chapter 3 (p.54) of “Automotive Movement and Control (Sankaido, Author: Masato Abe)” Is shown in In addition, the traveling direction of the center of the tire is a clockwise direction with respect to the direction of the tire rotation surface (see FIG. 3).
(Formula 13)
αfl = (V * β + (Lf + Lr) * γ) / (V-Lt * γ / 2)-δfl
αfr = (V * β + (Lf + Lr) * γ) / (V + Lt * γ / 2)-δfr
αrl = V * β / (V-Lt * γ / 2)-δrl
αrr = V * β / (V + Lt * γ / 2)-δrr
After the calculation, average slip angles αf and αr at the front wheels 2FL and 2FR and the rear wheels 2RL and 2RR are calculated.
(Formula 14)
αf = (αfl + αfr) / 2
αr = (αrl + αrr) / 2

(Each wheel slip angle limit value calculation)
The maximum limit values αfmax and αrmax for each wheel slip angle are calculated. In the calculation, the front and rear wheel slip angles αf and αr and the front and rear wheel lateral force sums Fy_f and Fy_r within a predetermined time are stored. For example, (αf, αr), (Fy_f, Fy_r) are sampled 400 times each within a predetermined time of 2 seconds, and αf [1] to αf [400], αr [1] to αr [400], Fy_f [1 ] To Fy_f [400] and Fy_r [1] to Fy_r [400].

  FIG. 9 is a diagram showing a relationship between the sampled front wheel slip angle absolute value | αf [j] | and the front wheel lateral force sum absolute value | Fy_f [j] | (j = 1, 2, 3... 400). . First, the maximum limit value αfmax of the front wheel slip angle is obtained based on FIG. The absolute value of the front wheel lateral force sum | Fy_f [1] | ~ | Fy_f [400] | is chosen as the largest value, and | Fy_f [k] | (k is an integer between 1 and 400) .

  The absolute absolute value of the front wheel slip angle corresponding to the absolute value of the front wheel lateral force | Fy_f [k] | is obtained, and the absolute value of the front wheel slip angle is determined from among | αf [1] | to | αf [400] | Select all | αf [m] | (| αf [m] |> | αf [k] |) values greater than the value | αf [k] |. If the corresponding | αf [m] | does not exist, αfmax = 1rad (a sufficiently large value).

| Fy_f [m] | corresponding to the selected | αf [m] | is selected, and among these | Fy_f [m] |, | Fy_f [n] | Note that the value of Δ (> 0) is a coefficient determined according to the required accuracy of each wheel slip angle limit value.
(Formula 15)
| Fy_f [k] | -Δ> | Fy_f [n] | and | αf [n] |> | αf [k] |
If | Fy_f [n] | corresponding to Equation 15 exists, the minimum value of the corresponding | αf [n] | is set as the maximum front wheel slip angle limit value αfmax. If the corresponding | Fy_f [n] | does not exist, αfmax = 1 rad (a sufficiently large value).
(Formula 16)
| Αf [n] | min = αfmax if | Fy_f [n] |
If | Fy_f [n] | does not exist, αfmax = 1rad

The rear wheel slip angle maximum limit value αrmax is also obtained in the same manner as the front wheel based on the following Expression 17.
(Formula 17)
| Fy_r [k] | -Δ> | Fy_r [n] | and | αr [n] |> | αr [k] |
| Αr [n] | min = αrmax if | Fy_r [n] |
If | Fy_r [n] | does not exist, αrmax = 1 rad

(Auxiliary rudder angle command value calculation)
1. Front wheel auxiliary rudder angle command value tDF
The front wheel auxiliary steering angle command value tDF is basically set to 0, but the front wheel auxiliary steering angle command is based on the following formula so as to limit the front wheel slip angle αf so that the turning performance does not deteriorate when the driver turns the steering wheel 11. Calculate the value tDF.
(Formula 18)
tDF = max [-αfmax + {V * β + (Lf + Lr) * γ} / V-MAP_STRF (STR),
min [αfmax + {V * β + (Lf + Lr) * γ} / V-MAP_STRF (STR), 0]]

2. Rear wheel auxiliary rudder angle command value tDR
As for the rear wheel auxiliary steering angle command value tDR, basically, the auxiliary steering angle command value tDR is calculated in the following manner in proportion to and in reverse phase with respect to the front wheel turning angle δf by the steering of the steering wheel 11.
(Formula 19)
(-K * MAP_STRF (STR))
As with the front wheels, the rear wheel turning angle command value tDR is calculated as follows using K as a constant so as to limit the rear wheel slip angle αr so that the turning performance does not deteriorate when the driver turns the steering wheel.
(Formula 20)
tDR = max [-αrmax + β, min {αrmax + β, -K * MAP_STRF (STR)}]

[Each wheel turning angle limit control process]
FIG. 10 shows each wheel turning angle restriction control processing routine. Hereinafter, each step will be described.

  In step S501, the slip angles αfl and αfr of the front wheels 2FL and 2FR with respect to the vehicle slip angle β are calculated to obtain the average front wheel slip angle αf, and the process proceeds to step S502.

  In step S502, the slip angles αrl and αrr of the rear wheels 2RL and 2RR with respect to the vehicle slip angle β are calculated to obtain the average rear wheel slip angle αr, and the process proceeds to step S503.

  In step S503, the front and rear wheel slip angles αf and αr and the front and rear wheel lateral force sums Fy_f and Fy_r within a predetermined time are sampled, and the process proceeds to step S504.

  In step S504, a front wheel auxiliary steering angle command value αfmax is calculated, and the process proceeds to step S505.

  In step S505, the rear wheel auxiliary rudder angle command value αrmax is calculated, and the process proceeds to step S506.

  In step S506, the front and rear wheel auxiliary rudder angle command values tDF and tDR are calculated, and the control is terminated.

[Effect of the embodiment of the present application]
(1) In the embodiment of the present application, in the vehicle behavior control device including the lateral force sum calculating means for calculating the lateral force sums Fy_f and Fy_r of the vehicle wheels 2FL to 2RR based on the vehicle state, the lateral force sum calculating means includes: The lateral force sums Fy_f and Fy_r of the front wheels 2FL and 2FR and the rear wheels 2RL and 2RR are independently calculated, the front wheel auxiliary turning angle command value tDF which is the tire acting force of the front wheels 2FL and 2FR and the rear wheels 2RL and 2RR, and the rear Wheel turning angle command value tDR
It was decided to provide a control means for independently controlling. As a result, the front wheels 2FL and 2FR and the rear wheels 2RL and 2RR can be controlled independently according to the respective states, and more accurate vehicle behavior control can be performed.

  (2) Based on the vehicle condition, the lateral force sums Fy_f and Fy_f of the front wheels 2FL and 2FR and the rear wheels 2RL and 2RR are independently calculated, and the tire acting force of the front wheels is controlled based on the front wheel lateral force sum Fy_f. The tire acting force of the rear wheel is controlled based on the lateral force sum Fy_f of the rear wheel. As a result, the different states of the front and rear wheels can be grasped with higher accuracy, and independent control of the front and rear wheels can be reliably performed based on this.

  (3) Steering angle detecting means for detecting the turning angles δfl to δrr of the wheels 2FL to 2RR, braking / driving reaction force calculating means for calculating the braking / driving reaction forces Fxfl to Fxrr of the wheels 2FL to 2RR, and a vehicle Lateral acceleration detecting means for detecting the two lateral accelerations YG1 and YG2 above, lateral force calculating means for calculating the lateral force FY at the vehicle center of gravity based on the two lateral accelerations YG1 and YG2, and two lateral forces Yaw moment calculating means for calculating the yaw moment γ 'at the center of gravity of the vehicle based on the accelerations YG1 and YG2, and the lateral force sum calculating means each wheel turning angle δfl ~ δrr, each wheel braking drive reaction force Fxfl ~ Fxrr The lateral force sums Fy_f and Fy_r of the front wheels and the rear wheels are calculated based on the lateral force FY and the yaw moment γ ′.

  This makes it possible to independently calculate the yaw moment γ ′ for the front and rear wheels, and the yaw moment γ ′ for the front and rear wheels changes independently even if the sum of the yaw moment γ ′ for the front and rear wheels does not change. If so, the vehicle state can be more accurately grasped by grasping the state of the front and rear wheels independently.

によって、またはこの数式の近似式によって、横力和Fy_f,Fy_rを演算することとした。これにより、数式を用いて演算することで、横力和Fy_f,Fy_rをより高精度かつ高速度で演算することができる。 (4) The lateral force sum calculation means is such that Lf is the longitudinal distance between the front wheel axis and the vehicle center of gravity, Lr is the longitudinal distance between the rear wheel axis and the vehicle center of gravity, Lt is the tread base distance, δf is the front wheel steering angle, and δr is As the rear wheel rudder angle, the following formula

The lateral force sums Fy_f and Fy_r are calculated according to the above or an approximate expression of this mathematical expression. Accordingly, the lateral force sums Fy_f and Fy_r can be calculated with higher accuracy and higher speed by calculating using mathematical expressions.

  (5) The turning angle of each wheel is used as the tire acting force, and the control means controls the auxiliary turning motor 12 and the turning motor for controlling the turning angles of the front wheels 2FL and 2FR and / or the rear wheels 2RL and 2RR. It was set to 16. As a result, the yaw moments of the front and rear wheels can be controlled independently, and vehicle behavior control can be performed with higher accuracy.

  (6) The control means controls the front and rear wheel turning angles δfl to δrr according to the front and rear wheel lateral force sums Fy_f and Fy_r within a range in which the front and rear wheel lateral force sums Fy_f and Fy_r do not decrease. The lateral force of a wheel basically has a characteristic of increasing as the side slip angle increases, but it tends to decrease as the side slip angle increases beyond a certain side slip angle S (the vehicle bends if the tire is steered too much). It becomes difficult.) The front and rear wheel lateral force sums Fy_f and Fy_r start to decrease in accordance with the front and rear wheel slip angles αfl to αrr because the steering angles δfl to δrr are limited to perform control according to the road surface friction coefficient and vehicle condition. Can be avoided and the vehicle behavior can be made more stable.

(Other examples)
As mentioned above, although the steering device of the present invention has been described based on the embodiments, the specific configuration is not limited to these, and the design of the steering device is not limited unless it deviates from the gist of the invention according to each claim of the claims. Changes and additions are allowed.

For example, there is a transient delay from the occurrence of each wheel slip angle αfl to αrr to the occurrence of lateral force on each wheel. When the transfer characteristic until occurrence of T is defined as T (s), Equation 14 may be replaced with the following equation, and the flowchart of FIG. Here, s is a differential operator.
(Formula 21)
αf = T (s) * (αfl + αfr) / 2
αr = T (s) * (αrl + αrr) / 2

  In the embodiment of the present invention, the front wheel auxiliary turning angle command value tDF and the rear wheel turning angle command value tDR of the front wheels 2FL, 2FR and the rear wheels 2FL, 2RR are used as the tire acting force, but the front wheels 2FL, 2FR are used as the tire acting force. The vehicle behavior control may be performed by using the braking / driving forces Fxf and Fxr of the rear wheels 2FL and 2RR and independently controlling them.

It is a system block diagram of the electric vehicle which drives 4 wheels with an independent electric motor. It is a main flowchart of a torque command value calculation control process. It is a figure which shows the relationship between a vehicle body slip angle and each vehicle behavior parameter. It is a figure which shows the relationship between a lateral acceleration and each vehicle behavior parameter. It is a routine of a vehicle behavior control process. It is a vehicle speed-accelerator opening degree map. It is a vehicle speed-steering angle map. It is a motor torque command value calculation control processing routine. It is a figure which shows the relationship between the sampled front wheel slip angle absolute value and front wheel lateral force sum absolute value. It is each wheel turning angle restriction control processing routine.

Explanation of symbols

3FL to 3RR Wheel 4fl to 4rr Reducer 5FL to 5RR Drive circuit 6 Battery 8 Yaw rate sensor 11 Steering wheel 12 Auxiliary steering motor 14 Steering rack 15 Steering rack 16 Steering motor 17 Control circuit 21 Steering angle sensor 22 Brake pedal Sensor 23 Accelerator pedal sensors 24, 25 Lateral acceleration sensor 26 Longitudinal acceleration sensor 29 Car body slip angle sensor 30 Integrated controller

Claims (6)

In a vehicle behavior control device that controls the turning behavior of a vehicle based on the vehicle state,
The lateral force sum calculating means for independently calculating the lateral force sum of the front wheel and the rear wheel;
A vehicle behavior control device comprising: control means for independently controlling tire acting forces of the front wheels and the rear wheels based on the calculated lateral force sum of the front wheels and the rear wheels. The vehicle behavior control apparatus according to claim 1,
Based on the vehicle state, the lateral force sum of the front wheel and the rear wheel is independently calculated, the tire acting force of the front wheel is controlled based on the lateral force sum of the front wheel, and based on the lateral force sum of the rear wheel, A vehicle behavior control device characterized by controlling a tire acting force on a rear wheel. In the vehicle behavior control device according to claim 1 or 2,
A turning angle detection means for detecting a turning angle of each wheel;
Braking / driving reaction force calculating means for calculating the braking / driving reaction force of each wheel;
Lateral acceleration detecting means for detecting lateral acceleration at two locations on the vehicle;
Lateral force calculating means for calculating lateral force at the vehicle center of gravity based on the two lateral accelerations;
A yaw moment calculating means for calculating a yaw moment at the center of gravity of the vehicle based on the two lateral accelerations;
The lateral force sum calculating means calculates a lateral force sum of the front and rear wheels based on a turning angle of each wheel, a braking / driving reaction force of each wheel, the lateral force, and the yaw moment. A vehicle behavior control device. In the vehicle behavior control apparatus according to claim 3,
The lateral force sum calculating means is such that Lf is the front-rear distance between the front wheel axis and the vehicle center of gravity, Lr is the front-rear distance between the rear wheel axis and the vehicle center of gravity, Lt is the tread base distance, δf is the front wheel steering angle, and δr is the rear wheel As the steering angle, the following formula

Or the approximate expression of the mathematical formula is used to calculate the lateral force sum. In the vehicle behavior control apparatus according to any one of claims 1 to 4,
The tire acting force is a turning angle of each wheel,
A vehicle behavior control device comprising an actuator for controlling a turning angle of the front wheel and / or the rear wheel. In the vehicle behavior control apparatus according to claim 5,
The vehicle behavior control device characterized by controlling the front-rear wheel turning angle in accordance with the lateral force sum of the front and rear wheels within a range in which the lateral force sum of the front and rear wheels does not decrease.

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