JP2904901B2 - Vehicle operation control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a driving control device for a vehicle.

(Prior Art) A lateral acceleration, which is a gravitational acceleration acting in a lateral direction of a vehicle, is used as a control parameter when controlling a driving state of the vehicle. Later, Japanese Patent Publication No. 63-66703 discloses an anti-skid brake device that controls the brake hydraulic pressure to adjust the braking force of each wheel, thereby preventing the occurrence of a wheel lock or skid state during braking. A system in which the control threshold value of the brake hydraulic pressure of each wheel is changed based on the lateral acceleration is disclosed. In this case, the lateral acceleration is detected by a G sensor.

Also, the coefficient of friction between the vehicle tires and the road surface,
The road surface friction coefficient is also used for controlling the driving state of the vehicle. Generally, a method of estimating the road surface friction coefficient from a change in the wheel speed of a driven wheel due to a change in the driving force is employed.

As means for controlling the driving state of the vehicle, a power steering device, a rear wheel turning control device, a traction control device, and the like are known in addition to the anti-skid brake device.

(Problem to be Solved by the Invention) As described above, the lateral acceleration of the vehicle is useful for controlling the driving state of the vehicle, but conventionally, a G sensor is required to obtain the accuracy of the lateral acceleration.

That is, an object of the present invention is to enable detection of the lateral acceleration of a vehicle without using the above-described G sensor,
An object of the present invention is to make it possible to change the control characteristics of the driving state of the vehicle based on the obtained lateral acceleration, and in particular to change the control characteristics in consideration of the road surface friction coefficient.

(Means for Solving the Problems) In order to solve the above problems, the lateral acceleration G is detected using the rotation speeds of the inner wheel and the outer wheel of the driven wheels of the vehicle, and based on the front wheel turning angle and the vehicle speed. The reference lateral acceleration Go is detected, and the control characteristics of the vehicle are changed based on the result of comparison between the two lateral accelerations G and Go.

Specific means for that are wheel speed detecting means for detecting the rotational speeds of the driven inner wheel and the driven outer wheel of the vehicle; rotating speed of the driven inner wheel and the driven outer wheel detected by the wheel speed detecting means; A lateral acceleration calculating means for calculating a lateral acceleration G occurring in the vehicle based on the tread; a steering angle detecting means for detecting a turning angle of the front wheels; a vehicle speed detecting means for detecting a vehicle speed; A reference lateral acceleration calculation means for calculating a reference lateral acceleration Go by the following equation based on the steering angle θ detected by the means and the vehicle speed v detected by the vehicle speed detection means; and adjusting a driving state of the vehicle. Operating state adjusting means, control means for controlling the operating state adjusting means in accordance with a predetermined control characteristic according to the operating state, lateral acceleration G detected by the lateral acceleration calculating means, and a reference lateral acceleration calculating means. Based on the difference A between the calculated norms lateral acceleration Go by a drive control apparatus for a vehicle, characterized in that a control characteristic changing means for changing the control characteristics of the control means.

Formula; Go = v ² · θ / L · g (where L is a wheel base and g is a gravitational acceleration) In this vehicle driving control device, the control means has different control characteristics depending on the level of the road surface friction coefficient, The control characteristic changing means may change the control characteristic of the control means to a control characteristic of a low road surface friction coefficient when the difference A is equal to or more than the predetermined value A1.

When the control means is related to the power steering device, the control characteristic changing means sets the difference A to a predetermined value A2.
In the above case, the control characteristics are changed so that the force for assisting the steering force is reduced.

When the control means is related to the rear wheel steering control device, the control characteristic changing means controls the steering ratio of the rear wheel to the front wheel to shift to the same phase when the difference A is equal to or more than the predetermined value A3. The characteristics shall be changed.

When the control means is related to the traction control device, the control characteristic changing means changes the control characteristic of the traction control means so that the driving force of the driving wheel is reduced when the difference A is equal to or more than the predetermined value A4. And

(Operation) In the above solution, only means for detecting the rotational speeds of the driven inner wheel and the driven outer wheel may be used as the detecting means for obtaining the lateral acceleration G, and the rotational speeds of the inner and outer driven wheels are actually generated. Therefore, the obtained lateral acceleration G also corresponds to the actually generated lateral acceleration.

Then, the lateral acceleration actually generated in the vehicle becomes smaller than the reference lateral acceleration Go obtained from the vehicle speed and the steering angle due to the influence of the road surface friction coefficient. The difference A between the acceleration G and the reference lateral acceleration Go corresponds to the road surface friction coefficient. Therefore, the difference A
When the control characteristics of the operating state control means are changed based on
Control suitable for the road surface friction coefficient can be performed.

Then, it is assumed that the control characteristics of the control means in the operating state are different depending on the level of the road surface friction coefficient, and the difference A is a predetermined value A1
If the control characteristic of the control means is changed to the control characteristic of the low road surface friction coefficient at the time above, without separately detecting the road surface friction coefficient, when the road surface friction coefficient is low, it is suitable for this road surface friction coefficient. Control can be performed.

Further, when the control means is related to a power steering device, if the control characteristic is changed so that the force for assisting the steering force decreases when the difference A is equal to or greater than the predetermined value A2, the friction coefficient of the road surface is reduced. When it is low, it is possible to prevent the steering angle from becoming excessively large and prevent the vehicle from slipping or spinning.

Further, when the control means is related to the rear wheel turning control device, if the control characteristic is changed so that the rear wheel has the same phase as the front wheel when the difference A is equal to or more than the predetermined value A3, the road surface can be controlled. When the coefficient of friction is low, when the rear wheel is steered in the opposite phase to the front wheel, the steered angle is reduced or set to the same phase as the steered angle so that the rear wheel is in phase with the front wheel. When the vehicle is turned, the steering angle of the vehicle can be made larger to improve the running stability of the vehicle.

Further, when the control means is related to the traction control device, when the difference A is equal to or more than the predetermined value A4, if the control characteristics are changed so that the driving force of the drive wheels is reduced, during the traction control, When the coefficient of friction on the road surface is low, it is possible to prevent the vehicle from spinning due to the decrease in the driving force.

(Effect of the Invention) Therefore, according to the present invention, the difference between the lateral acceleration G obtained from the rotation speed of the driven inner wheel and the rotation speed of the driven outer wheel, and the reference lateral acceleration Go obtained from the vehicle speed and the front wheel steering angle. Since the control characteristics of the vehicle are changed based on A, control suitable for the road surface friction coefficient can be performed without separately providing a G sensor and friction coefficient detection means.

If the control characteristic of the control means is changed to the control characteristic of the low road surface friction coefficient when the difference A is equal to or more than the predetermined value, the low road surface friction coefficient is low without separately providing the friction coefficient detection means. In this case, control suitable for the road surface friction coefficient can be performed.

When the difference A is equal to or larger than a predetermined value, the rear wheel turning control device sets the rear wheel turning ratio to the front wheel to be in the same phase in the rear wheel turning control device so that the power assisting force decreases in the power steering device. In the traction control device, if the control characteristics are changed so that the driving force of the drive wheels is reduced, the running stability of the vehicle can be improved when the road surface friction coefficient is low.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

-Overall configuration-In the vehicle shown in Fig. 1, 1 is an engine, 2FL, 2FR
Are left and right front wheels, and 2RL and 2RR are left and right rear wheels. In this vehicle, the left and right rear wheels 2RL and 2RR are drive wheels driven by the engine 1 via the automatic transmission 3, and the left and right front wheels 2F
L and 2FR are driven wheels. Reference numeral 4 denotes a control unit.

The control unit 4 has a built-in microcomputer, and includes a lateral acceleration calculating means 5, a friction coefficient calculating means 6, a storage means 7, a control means 8 for controlling the driving state of the vehicle, a reference lateral acceleration calculating means 9, A characteristic changing means 10 is provided.

-Vehicle lateral acceleration detecting device-The vehicle lateral acceleration G is calculated by the lateral acceleration calculating means 5 based on detection signals from the wheel speed sensors 66FL, 66FR for detecting the rotational speed of the front wheels 2FL, 2FR. It has become. The calculation formula is the following I formula.

<I formula> G (Vo ² −Vi ² ) / 2 · T · g (where Vo is the rotation speed of the driven outer wheel, Vi is the rotation speed of the driven inner wheel, T is the tread, and g is the gravitational acceleration) Then, right front wheel 2FR is driven outer wheel, left front wheel 2
If FL is the driven inner wheel, Vo is the rotational speed of the right front wheel 2FR, Vi
Means the rotation speed of the left front wheel 2FL. If the turning radius of the left front wheel 2FL is r and the angular velocity is ω, the rotational speeds Vi and Vo are as follows.

 Vi = rω (1) Vo = (r + T) ω (2) By subtracting equation (1) from equation (2), Tω = Vo−Vi From this, ω = (Vo−Vi) / T (3) The turning radius R of the tread center is as follows.

R = (Vo + Vi) / 2 · ω By substituting equation (3) into this, R = T · (Vo + Vi) / {2 · (Vo−Vi)} (4) Assuming that the position t seconds after the rectangular coordinates (r, 0) is the rectangular coordinates (x, y) with respect to the tread center position, x, y are as follows.

x = R · cos (ωt) (5) y = R · sin (ωt) (6) Then, the lateral acceleration G at the above (x, y) point is given by the following equation.

From equation (5) and ^{(6), = ω 2 · R {-cos} (ωt)} = ω 2 · R {-sin (ωt)} Therefore, the equation (7), G = ω ² · R (8) By substituting the equations (3) and (4) into the equation (8) and rearranging, G = (Vo ² −Vi ² ) / 2 · T Expressed using the gravitational acceleration g, G = (Vo ² −Vi ² ) / 2 · T · g That is, the above-described formula I is obtained.

Then, since the rotation speeds Vi and Vo of the inner and outer driven wheels, which are variables included in the above formula I, depend on the magnitude of the actually generated lateral acceleration, the obtained lateral acceleration G is also actually generated. It corresponds to the lateral acceleration that is being performed.

-Road surface friction coefficient detecting device-Road surface friction coefficient μ which is a friction coefficient between the tire and the road surface.
Is calculated from the storage means 7 by the friction coefficient calculating means 6 based on the lateral acceleration G calculated by the lateral acceleration calculating means 5.

That is, in turning the vehicle, the front wheels 2FL, 2FR
Cornering power C1, sideslip angle β1, and rear wheels 2RL, 2RR
And the centrifugal force F due to the lateral acceleration are balanced by the cornering power C2 and the side slip angle β2.

F = 2 (C1 · β1 + C2 · β2) In general, the cornering power C increases almost in proportion to the increase of the road surface friction coefficient μ and becomes substantially constant when the road friction coefficient μ increases. Since the centrifugal force F is a product of the lateral acceleration G and the load W of the vehicle, there is a certain relationship between the road surface friction coefficient μ and the lateral acceleration G. The storage means 7 stores this relationship. The friction coefficient calculation means 6 has a minimum value between the tire and the road surface from the storage means 7 based on the lateral acceleration G calculated by the lateral acceleration calculation means 5. This means that the road friction coefficient μ can be calculated.

-Vehicle driving control device- <Outline description> The control means 8 controls the driving state adjusting means 100 such as a brake means for adjusting the driving state of the vehicle and a power cylinder of a power steering apparatus based on various control parameters to a predetermined control characteristic. Is controlled according to the following. The control characteristic changing means 10 controls the control characteristic of the control means 8 based on a comparison result between the lateral acceleration G obtained by the lateral acceleration calculating means 5 and the reference lateral acceleration Go obtained by the reference lateral acceleration calculating means 9. Is to change.

<Reference lateral acceleration calculation> The reference lateral acceleration Go is a reference lateral acceleration to be compared with the lateral acceleration G, and includes a steering angle θ detected by a steering angle detecting unit that detects a steering angle of a front wheel, and a vehicle speed. Is calculated by the reference lateral acceleration calculating means 9 based on the vehicle speed v detected by the vehicle speed detecting means for detecting the following equation II.

<Equation II> Go = v ² · θ / L · g (where L is the wheelbase and g is the gravitational acceleration) <Change of control characteristics> The control characteristic changing means 10 is calculated by the lateral acceleration calculating means 5. Based on the difference A between the lateral acceleration G and the reference lateral acceleration Go calculated by the reference lateral acceleration calculation means 9,
This is to change the control characteristics of the control means 8.

(Specific Example) FIG. 2 shows an overall configuration for anti-skid brake control and traction control.

It should be noted that the control means 70 and control characteristic changing means 73 are shown in FIG.
Are described separately for anti-skid brake control and traction control, but the control contents are different for each.

First, the automatic transmission 3 includes a torque converter 11 and a multi-stage transmission gear mechanism 12. The transmission gear mechanism 12 is of a hydraulically operated type as is known, and in the embodiment, is used for four forward speeds and one reverse speed. That is, gear shifting is performed by changing the combination of excitation and demagnetization of the plurality of solenoids 13a incorporated in the hydraulic circuit. Further, the torque converter 11 has a hydraulically operated lock-up clutch 11a, and by switching between excitation and demagnetization of a solenoid 13b incorporated in the hydraulic circuit,
Fastening and unfastening are performed.

The solenoids 13a and 13b are controlled by an AT controller 60 for controlling a shift of the automatic transmission 3. The AT controller 60 stores shift characteristics and lock-up characteristics in advance, and performs shift control and lock-up control based on these. For this reason, the AT controller 60 receives each throttle opening signal from a main throttle opening sensor 61 for detecting the opening of the main throttle valve 43 and a sub-throttle opening sensor 62 for detecting the opening of the sub-throttle valve 45. ,
A vehicle speed signal (a rotation signal of the propeller shaft 4 in the embodiment) from a vehicle speed sensor 63 that detects a vehicle speed is input.

<Brake Force Adjusting Mechanism> A braking force adjusting mechanism as an operating state adjusting means will be described.

Each wheel 2FL, 2FR, 2RL, 2RR is provided with a brake 21FL-21RR. The calipers (wheel cylinders) 22FL to 22RR of the respective brakes 21FL to 21RR are provided with pipes 23FL to 23FL, respectively.
Brake fluid pressure is supplied via 23RR. The structure for supplying the brake fluid pressure is as follows.

First, the depressing force of the brake pedal 25 is boosted by a hydraulic booster-type booster 26 and transmitted to a tandem-type master cylinder 27. The first discharge port 27a of the master cylinder 27 is connected to a brake pipe 23FL for the front left wheel, and the second discharge port 27b of the master cylinder 27 is connected to a brake pipe 23FR for the front right wheel.

An electromagnetic on-off valve 50A, 51A is interposed between the left front wheel brake pipe 23FL and the right front wheel brake pipe 23FR, and a relief passage 52L connected downstream of the on-off valves 50A, 51A. , 52R are provided with electromagnetic on-off valves 50B, 51B.

Fluid pressure from a pump 29 is supplied to the booster 26 via a pipe 28, and excess hydraulic pressure is returned to a reservoir tank 31 via a return pipe 30. A branch pipe 28a branched from the pipe 28 is connected to a junction a, and an electromagnetic on-off valve 32 is interposed in the branch pipe 28a. Also a booster
The boosting hydraulic pressure generated at 26 is supplied to the junction a via a pipe 33, and the pipe 33 is also provided with an electromagnetic on-off valve 34. And the above piping
The 33 is provided with a one-way valve 35 in parallel with the on-off valve 34 that allows only the flow toward the junction a.

Brake pipes 23RL, 2 for the left and right rear wheels
3RR is connected. An electromagnetic on-off valve 36A or 37A is interposed in the pipes 23RL, 23RR, and a relief passage 3 connected downstream of the on-off valves 36A, 37A.
An electromagnetic on-off valve 36B or 37B is connected to 8L or 38R.

Each of the above on-off valves 32, 34, 36A, 37A, 36B, 37B, 50A, 51A, 50B, 51
B is controlled by the control means 70. In this case, when the traction control (brake control) is not performed, the on-off valve 32 is closed, the on-off valve 34 is opened, the on-off valves 36B and 37B are closed, and the on-off valves 36A and 37A are opened as shown in the figure. Thus, when the brake pedal 25 is depressed, the brake fluid pressure is supplied to the front wheel brakes 21FL and 21FR via the mass cylinder 27. Also, rear wheel brakes 21RL, 21RR
, A boosting hydraulic pressure corresponding to the depressing force of the brake pedal 25 from the hydraulic booster 26 is supplied as the brake hydraulic pressure via the pipe 33.

Further, as described later, when performing traction control, the on-off valve 34 is closed and the on-off valve 32 is opened. Further, the on-off valves 36A, 36B, 37A, 37B, 50A, 51A, 50B, 51B are controlled to be opened and closed by duty control. Further, the brake fluid pressure passing through the branch pipe 28a does not act as a reaction force on the brake pedal 25 due to the action of the one-way valve 35.

<Driving Force Adjusting Mechanism> A driving force adjusting mechanism as operating state adjusting means will be described.

In the case of traction control, in order to reduce the driving torque of the driving wheels 2RL and 2RR, brake control is performed on the driving wheels 2RL and 2RR, and the driving force transmitted to the driving wheels 2RL and 2RR, that is, the generated torque of the engine 1 Also reduce the amount.
For this reason, in the intake passage 41 of the engine 1, the above-mentioned main throttle valve 43 connected to the accelerator pedal 42 and the above-mentioned sub-throttle valve 45 connected to the throttle opening adjustment actuator 44 are arranged. Sub throttle valve 45
To the actuator 44 by the TRC controller 70.
Is controlled via the.

<Anti-Skid Brake Control> Anti-skid brake control (hereinafter referred to as ABS control) will be described.

In this example, a first channel for adjusting the brake pressure of the brake 21FL of the left front wheel 2FL by operating the on-off valves 50A and 50B, and a second channel for adjusting the brake 21FR braking pressure of the right front wheel 2FR by operating the on-off valves 51A and 51B. Channels and on-off valves 36A, 36B, 37A, 37
Actuation of B brakes 21RL, 22R for left and right rear wheels 2RL, 2RR
A third channel for adjusting the braking pressure of R, and these channels are controlled independently of each other.

Control means 70 for controlling the first to third channels
Indicates a brake signal from a brake sensor 72 for detecting whether or not the brake pedal 25 is being depressed, and each of the wheels 2FL to 2FL.
Wheel speed signals from the wheel speed sensors 66FL to 66RR for detecting the rotation speed of the RR and a steering angle signal from the steering angle sensor 69 are input, and ABS control is performed in parallel for each channel. I have.

 Hereinafter, the control contents will be specifically described.

The control means 70 includes a pseudo vehicle speed setting unit and a control threshold setting unit. Phase 0 (ABS non-control state) and phase I (A
Select a phase from the braking pressure reduction state during BS control), phase II (holding state after pressure reduction), phase III (rapid pressure increase state after pressure reduction holding), and phase IV (slow pressure increase state after sudden pressure increase). The brake pressure control signal corresponding to each phase is output to the on-off valves 36A, 36B, 37A, 37B, 50A, 50B, 51A, 51B.

The pseudo vehicle speed Vr is set as a vehicle speed for convenience based on the wheel speed.The maximum wheel speed of the four wheels 2FL to 2RR is set as the pseudo vehicle speed Vr, while the friction of the road surface is set. The speed change amount according to the coefficient is 1.
The correction is performed as follows by setting a value between 2 G · Δt and 3.0 G · Δt, which is a low coefficient of friction. Note that Δt is a sampling period (for example, 7 ms) of the control unit 34.

Vr ← Vr− (1.2 G · Δt to 0.3 G · Δt) The control threshold is set independently for each channel. In this example, the control threshold is set to the phase 0 (ABS non-control). 1) a first wheel deceleration threshold G1 for determining the transition from phase I to decompression, and a second wheel deceleration threshold for determining the transition from phase I to phase II (hold).
G2, a first slip ratio threshold value S1 for determining a transition from phase II to phase III (sudden pressure increase), and a wheel acceleration threshold value G3 for determining a transition from phase III to phase IV (slow pressure increase)
And a second slip ratio threshold S2 for determining transition from phase IV to phase I. The above control threshold is the pseudo vehicle speed.
It is set appropriately according to Vr and the friction coefficient of the road surface.

Regarding the wheel speeds of the rear wheels 2RL and 2RR, the smaller one of the two wheel speeds is selected as the rear wheel speed. The slip ratio is calculated according to the following equation.

Slip ratio = (1−wheel speed / pseudo vehicle speed) × 100 The above control threshold value is set as shown in FIG. 3 without excessively reducing the lateral drag coefficient μL of the wheel with respect to the road surface. Is set so that the coefficient of friction μ between them can be increased, that is, characteristics in the range of Ss can be obtained.

The deceleration and acceleration of the wheel are obtained by dividing the difference between the previous value and the current value of the wheel speed by the sampling period Δt, and converting the result to a gravitational acceleration.

Therefore, normally, the increase / decrease control of the braking pressure as shown in FIG. 4 is performed.

That is, when the brake pedal 25 is depressed from the constant speed traveling state, the braking pressure increases, and the wheel speed decreases accordingly.

When the wheel deceleration becomes larger than the first wheel deceleration threshold value G1, the process proceeds to the ABS control, phase I is selected, and the braking pressure is reduced according to a predetermined pressure reduction mode.

When the wheel deceleration becomes smaller than the second wheel deceleration threshold value G2, phase II is selected and the braking pressure is maintained in a reduced pressure state.

If the slip ratio decreases with the above-described pressure reduction and exceeds the first slip ratio threshold S1, Phase III is selected,
A sudden increase in the braking pressure takes place.

When the wheel acceleration decreases and becomes equal to or less than the combined wheel acceleration threshold value G3 due to the rapid pressure increase, the phase IV is selected, and the braking pressure is gradually increased.

When the slip rate exceeds the second slip rate threshold value S2 due to the above-described slow pressure increase, phase I is selected.

As described above, for each of the first to third channels,
By controlling the increase and decrease of the braking pressure independently of each other, the occurrence of the lock or skid state of each wheel is prevented, and the vehicle is stopped at a short braking distance without losing directional stability.

<Traction Control> In traction control (hereinafter referred to as TRC control), brake control, engine control by controlling the throttle opening adjustment actuator 44, and lock-up through an AT controller 60 for speed change control. Control. The control means 70 includes a throttle opening sensor 61,
In addition to the signals from the vehicle speed sensor 63 and the vehicle speed sensor 63, the wheel speed signals from the wheel speed sensors 66FL to 66RR for detecting the speed of each wheel 2FL to 2RR, and the accelerator opening sensor 67 for detecting the accelerator opening. An accelerator opening signal, a steering angle signal from a steering angle sensor 69 for detecting a steering angle, and a mode signal from a manually operated switch 71 are input.

(Contents of Traction Control) The contents of the traction control by the control means 70 are shown in FIG.
FIG. In the figure, the target value for the engine (the target slip value of the drive wheels) is indicated by SET, and the target value for the brake is indicated by SET (SBT> SET).

until time point t ₁ before, a large slip on the drive wheels has not occurred, the engine control is not performed, thus the sub-throttle valve 45 is a fully open, the throttle opening Tn (of both throttle valves 43, 45 (The combined opening, which corresponds to the opening of the throttle valve with the smaller opening) is the main throttle opening TH · M corresponding to the accelerator opening.

In time point t _1, the slip value of the driving wheels, a significant slip incurred became the target value SET for the engine. In the embodiment, it is adapted to start the traction control when the slip value of the driving wheels is equal to or higher than SET, the t ₁
At this point, the throttle opening is reduced at once to the lower limit control value SM (feedforward control). And once SM
After that, the slip value of the drive wheel becomes the engine target value SE.
The opening degree of the sub-throttle valve 45 is feedback-controlled so as to be T. At this time, the throttle opening Tn becomes the sub-throttle valve opening TH · S.

t In ₂ time, the slip value the brake target value SE of the drive wheel
At this time, the brake fluid pressure is supplied to the brakes 21RL and 21RR of the drive wheels, and traction control by both engine control and brake control is started. The brake fluid pressure is feedback-controlled so that the slip value of the drive wheel becomes the brake target value SBT.

t ₃ At the time, the slip value target value for the brake of the drive wheel
This is the time when the pressure is below SBT, whereby the brake fluid pressure is gradually reduced, and eventually the brake fluid pressure becomes zero.
However, the slip control by the engine is still continued.

In the embodiment, the condition for terminating the traction control is when the accelerator opening is fully closed.

(Calculation of slip value) The slip value of the driving wheel is calculated by the wheel speed sensors 66FR, 66FL, 66R.
It is detected based on the detection signal from R and 66RL. That is,
The slip value is calculated by subtracting the rotation speed of the driven wheel from the rotation speed of the driving wheel. In calculating the slip value, in the case of engine control,
The larger one of the left and right drive wheels is selected as the rotation speed of the drive wheel, and the average value of the left and right driven wheels is used as the rotation speed of the driven wheel. For brake control, the rotational speed of the driven wheels is the same as that for engine control, but when controlling the braking force on the left and right drive wheels independently of each other, the rotational speed of the left and right drive wheels is Are respectively used.

(Setting of target values SET, SBT) FIG. 6 is a block diagram showing a circuit for determining the target values SET and SBT. The determination parameters include vehicle speed, accelerator opening, steering wheel angle. And the operating state of the mode switch 71, and the maximum friction coefficient μmax of the road surface.

That is, in the figure, the basic value STA0 of SET and the basic value STB0 of SBT are stored in the map 81 using the maximum friction coefficient as a parameter (STB0> STA0). Then, by multiplying the basic values STB0 and STA0 by the correction gain coefficient KD, SET and SBT are obtained.

The above-mentioned correction gain coefficient KD is determined by the respective gain coefficients VG, ACPG and ST.
Obtained by multiplying RG and MODEG. The gain coefficient VG uses the vehicle speed as a parameter and is stored as a map 82. The gain coefficient ACPG uses the accelerator opening as a parameter, and is stored as a map 83. The gain coefficient STRG uses the steering wheel angle as a parameter and is stored as a map 84. The gain coefficient MODEG is manually selected by the driver and is stored in the table 85. The table 85 is provided with three types: a sports mode, a normal mode, and a safety mode.

(Change of control characteristic in ABS control) In this case, the change of the control characteristic is performed by changing the control threshold.

That is, the control characteristic changing unit 73 determines that the difference A between the lateral acceleration G calculated by the lateral acceleration calculating unit 5 and the reference lateral acceleration Go calculated by the standard lateral acceleration calculating unit 8 is equal to or greater than the predetermined value A1. Sometimes, the control threshold is changed to a control threshold corresponding to a low road surface friction coefficient, that is, a control threshold that reduces the braking efficiency.

Specifically, a first wheel deceleration threshold value G1 for determining a transition from the steering speed phase 0 (when ABS is not controlled) to a phase I (decompression), and a determination for a transition from the phase I to the phase II (holding). Phase II to lower the deceleration threshold G2
The first slip ratio threshold value G2 for determining the transition from (pressure reduction holding) to phase III (sudden pressure increase) and the second slip ratio threshold value S2 for determining the transition from phase IV to phase I are low, that is, the pseudo vehicle speed. The respective thresholds are changed so as to be shallower in view of Vr, and to increase the wheel acceleration threshold G3 for determining transition from phase III to phase IV (slow pressure increase).

(Change of the control characteristic in the TRC control) In this case, the control characteristic is changed by changing the basic value STA0 of the SET and the basic value STB0 of the SBT as the control threshold shown in FIG. Performed by That is, when the difference A is equal to or larger than the predetermined value A1, the control characteristic changing unit 73 issues a command to the control unit 70 to calculate the lowest basic values STA0 and STB0 from the map 81.

When the difference A is equal to or larger than the predetermined value A2, the control characteristic changing unit 73 issues a command to the control unit 70 to reduce the throttle opening TH · S. In this case, A1> A2.

(Power Steering Apparatus) FIG. 7 shows an overall configuration of a vehicle speed sensitive power steering apparatus of a vehicle. In the figure, 101 is the left and right front wheels 2FL, 2
A power cylinder 101 extending in the vehicle width direction between the FRs, and the power cylinder 101 is provided with a piston 103 mounted on a steering rod 102 and a cylinder left chamber 101L and a cylinder right chamber 1L.
01R is defined. The steering rod 102 is provided with a rack 106 that meshes with a pinion 105 provided at the lower end of a steering shaft 104. The steering force of a wheel 107 at the upper end of the steering shaft is controlled by the rack 106 and the pinion.
It is converted and transmitted by the 105 as the movement of the steering rod 102 in the axial direction (vehicle width direction). A tie rod 123 and a knuckle arm 124 are provided on both left and right ends of the steering rod 102, respectively.
The front wheels 2FL and 2FR are connected via the.

Reference numeral 110 denotes a gear control valve attached to the lower end of the steering shaft 104, which communicates with an oil pump 122 driven by the engine 1 through a pressure oil supply path 111, and is responsive to rotation of the steering wheel 107. The pressure oil is switched and supplied to the left chamber 101L and the right chamber 101R of the power cylinder 101. A return passage 112 extends from the gear control valve 110.

In the pressure oil supply path 111, an electromagnetic flow control valve 113 for controlling the pressure oil supply amount and a pressure regulating valve 115 are interposed in parallel with each other. The flow control valve 113 causes the spool 117 to narrow the flow path as the amount of current supplied to the coil 116 increases. A vehicle speed sensor 118 is linked to the flow control valve 113 via a control means 119, and the amount of current supplied to the coil 116 increases as the vehicle speed increases. The pressure regulating valve 115 drains part of the pressure oil in accordance with the pressure difference between the upstream side and the downstream side of the flow control valve 113.

In FIG. 7, reference numeral 120 denotes a battery, and 121 denotes an oil tank.

(Change of Control Characteristics of Power Steering) 130 is control characteristic changing means. The control characteristic changing means 130 uses the lateral acceleration G calculated by the above-described lateral acceleration calculating means 5 and the reference lateral acceleration calculating means 8. When the calculated difference A from the reference lateral acceleration Go is equal to or larger than a predetermined value A2, a control characteristic change command is issued to the control means 119 so as to reduce the amount of pressure oil supplied by the flow control valve 113.

(Rear Wheel Steering Control Device) FIG. 8 shows the overall configuration of a vehicle rear wheel steering control device (four-wheel steering device). In the figure, 200 is the left and right front wheels 2FL, 2
Front wheel steering mechanism that steers LR, 210 is left and right rear wheels 2RL, 2RR
Is a rear wheel steering mechanism that steers the vehicle.

The front wheel steering mechanism 200 includes a steering shaft 104 having a steering wheel 107, a pair of left and right knuckle arms 124 and a tie rod 123, and the tie rods 124, 12
4 Steering shaft 102 and front wheel steering rod 102
A pinion 105 provided at a lower end of the front wheel 104 and engaged with a rack 106 of the front wheel steering rod 102.

Further, the rear wheel steering mechanism 210 is provided with the front wheel steering mechanism 200.
Similarly to the first embodiment, a pair of left and right knuckle arms 211 and 211, tie rods 212 and 212, and a rear wheel steering rod 213 are provided. Also,
A reduction mechanism 214 is connected to the rear wheel steering rod 213, and the reduction mechanism 214 is connected to an output shaft of the servo motor 215. The rotation of the servo motor 215 drives the rear wheel steering rod 213 via the reduction mechanism 214. To the rear wheel 2RL, 2RR
Is configured to be steered.

Further, in the rear wheel steering mechanism 210, an electromagnetic brake 216 is disposed on the output shaft of the servomotor 215, and locks the motor output shaft and the rear wheel steering rod 213 during the braking operation to rotate the rear wheels 2RL and 2RR. Maintain the rudder state. An electromagnetic clutch 217 is interposed between the output shaft of the servomotor 215 and the speed reduction mechanism 214, and the rear wheel steering rod 213 has a position return mechanism for returning the steering rod 213 to a neutral position. 218 is disposed, and when the rear wheel steering is abnormal, the servo motor 215 is opened by opening the electromagnetic clutch 217.
By releasing the connection between the rear wheel steering rod 213 and the rear wheel steering rod 213 and returning the rear wheel steering rod 213 to the neutral position by the position return mechanism 218, the rear wheels 2RL and 2RR are positioned at the neutral position of the steering angle of zero. Has become.

Reference numeral 220 denotes control means for controlling the steering angle of the rear wheels, which basically controls the servomotor 215 via the drive circuit 219 and also controls the electromagnetic brake 216. The control means 220 receives detection signals from various sensors. 225
Is a steering rudder angle sensor, 227 and 228 are two vehicle speed sensors, 229 is a neutral clutch switch for detecting the N (neutral) position of the manual transmission and the time of depressing the clutch pedal, and 230 is the N position or P (parking) of the automatic transmission. ) Inhibitor switch for detecting the position, 232 is an engine switch for detecting when the engine is running, 233 is a rotation angle sensor for detecting the rotation angle of the servo motor 215, 234 is the rotation of the rear wheel according to the amount of movement of the rear wheel steering rod 213. This is a rear wheel steering angle sensor that detects a steering angle.

The control means 220 stores in advance the steering ratio characteristics of the rear wheels shown in FIG. Here, the steering ratio characteristics, steering angle ratio of the rear wheels (a clogging rear wheel steered angle theta _R / wheel turning angle theta _F, the front wheel turning angle theta _F is proportional to the steering angle theta _H) is This is a characteristic that changes according to the vehicle speed, and changes from the opposite phase side to the same phase side as the vehicle speed changes from the low vehicle speed to the high vehicle speed. In the characteristic II shown by the broken line, the characteristic I shown by the dashed line is set such that the steering ratio at the same vehicle speed value is deviated to the same phase side as the characteristic I. Characteristic I
Is used for normal control of the control means 220,
The characteristic II is used when the control characteristic changing unit 240 receives a control characteristic change command.

(Change of Control Characteristics in Rear Wheel Steering Control) The control characteristic changing means 240
When the difference A between the lateral acceleration G calculated by the formula (1) and the reference lateral acceleration Go calculated by the reference lateral acceleration calculating means 8 is equal to or more than a predetermined value A2, the control means 119 is controlled to select and use the characteristic II. Issue a characteristic change command.

FIG. 10 is a flowchart of a control characteristic change flow in the ABS control, the TRC control, the power steering control, and the rear wheel steering control. Various data are input to calculate the lateral acceleration G and the reference lateral acceleration Go (steps S1 to S3). ). And with the above G
When the difference A from Go is equal to or larger than the predetermined value A1, the control unit determines that the road friction coefficient is low, and changes the control threshold values of the ABS resin and the TRC control to those corresponding to the low road friction coefficient (steps S4 to S6).

Therefore, in the ABS control, the braking efficiency is reduced, the turning performance is improved, and the running stability of the vehicle is improved even with a low road surface friction coefficient. On the other hand, in the TRC control, both the target value SET for the engine and the target value SBT for the brake become low, and when the slip of the drive wheel occurs, the control is started early to improve the running stability of the vehicle.

When the difference A between G and Go is equal to or larger than a predetermined A2,
Command to reduce hydraulic oil supply to power cylinder 101 in power steering system, characteristics in rear wheel steering control system
Each output of the II selection command and the driving force reduction command in the TRC control device is performed (steps S7 to S10).

Accordingly, in the power steering device, the assisting force (assisting force) of the steering force is reduced by the reduction in the supply amount of the pressure oil, and excessive turning at a low road surface friction coefficient is prevented, and slip or spin occurs in the vehicle. Is prevented. In the rear wheel turning control, by selecting the characteristic II, the turning of the rear wheels is shifted to the same phase side, and the running stability at a low road surface friction coefficient is improved. Further, in the TRC control, the occurrence of vehicle spin when the road surface has a low coefficient of friction is prevented due to a reduction in driving force.

In the above embodiment, each output condition of the pressure oil supply amount reduction command to the power cylinder 101 in the power steering device, the selection command of the characteristic II in the rear wheel steering control device, and the driving force reduction command in the TRC control device is set. Also G
Although the difference A from Go is equal to or larger than the predetermined A2, the difference may be different from each other.

[Brief description of the drawings]

Drawings show an embodiment of the present invention, FIG. 1 is an overall configuration diagram of an embodiment, FIG. 2 is an overall configuration diagram of an apparatus for ABS control and TRC control, FIG. 3 is a slip ratio and a friction coefficient, and FIG. FIG. 4 is a time chart of the ABS control, FIG. 5 is a time chart of the TRC control, and FIG. 6 is for determining each slip target value for the engine and the brake. 7, FIG. 7 is an overall configuration diagram of a power steering device, FIG. 8 is an overall configuration diagram of a rear wheel steering control device, FIG. 9 is a steering ratio characteristic diagram, and FIG. 10 is a flow of control characteristic change control. FIG. 2FL, 2FR Front wheel (driven wheel) 2RL, 2RR Rear wheel (drive wheel) 5 Lateral acceleration calculation means 6 Friction coefficient calculation means 7 Storage means 8, 70, 119, 220 Control means 9 Standard lateral acceleration calculating means 10, 73, 130, 240 Control characteristic changing means 44 Actuator (driving force adjusting means) 66FL-66RR Wheel speed sensor 69 Steering angle sensor 63 Vehicle speed sensor 100 Operating condition adjusting means 101 ... Power cylinder

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruki Okazaki 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-2-70941 (JP, A) JP-A-1 JP-A-3-138428 (JP, A) JP-A-62-1201046 (JP, U) JP-A-2-71244 (JP, U) (58) Fields investigated (Int. Cl) . ^6, DB name) B60K 41/00 - 41/28 B60T 7/12 - 7/22 B60T 8/32 - 8/96 B62D 6/00 - 6/06 F02D 29/00 - 29/06

Claims (5)

(57) [Claims] 1. A wheel speed detecting means for detecting rotational speeds of a driven inner wheel and a driven outer wheel of a vehicle, and a rotational speed of the driven inner wheel, a rotational speed of the driven outer wheel, and a tread of the vehicle detected by the wheel speed detecting means. Lateral acceleration calculating means for calculating a lateral acceleration G generated in the vehicle, steering angle detecting means for detecting a turning angle of the front wheels, vehicle speed detecting means for detecting a vehicle speed, and detection by the steering angle detecting means. Reference lateral acceleration calculation means for calculating reference lateral acceleration Go by the following equation based on the detected turning angle θ and the vehicle speed v detected by the vehicle speed detection means, and driving state adjustment for adjusting the driving state of the vehicle. Means, control means for controlling the operating state adjusting means in accordance with a predetermined control characteristic in accordance with the operating state, and lateral acceleration G detected by the lateral acceleration calculating means and calculated by the reference lateral acceleration calculating means. Norms lateral acceleration was
A driving control device for a vehicle, comprising: control characteristic changing means for changing the control characteristic of the control means based on a difference A from Go. Formula; Go = v ² · θ / L · g (where L is the wheelbase and g is the gravitational acceleration) The control means has different control characteristics depending on the level of the road surface friction coefficient. The control characteristic changing means changes the control characteristic of the control means when the difference A is equal to or greater than a predetermined value A1. The vehicle operation control device according to claim 1, wherein the control characteristic is changed to a control characteristic. 3. The driving state adjusting means is a power cylinder for assisting the steering force of the steering, and the control means controls the power cylinder in accordance with a predetermined control characteristic so that a predetermined assisting force is obtained by a steering input. The power steering control means, wherein the control characteristic changing means changes the control characteristic of the power steering control means such that when the difference A is equal to or more than a predetermined value A2, the force for assisting the steering force decreases. The vehicle operation control device according to item (1). 4. The driving state adjusting means is a rear wheel steering means for steering a rear wheel. The control means controls the rear wheel steering means according to a predetermined control characteristic in accordance with steering of a front wheel. Control characteristic changing means for controlling the rear wheel turning ratio of the front wheel to the front wheel when the difference A is equal to or greater than a predetermined value A3. The operation control device for a vehicle according to claim 1, wherein the control characteristic of the rear wheel steering control means is changed so as to shift to the side. 5. The driving state adjusting means is a driving force adjusting means for adjusting a driving force of a driving wheel. When the driving wheel is slipping, the driving means adjusts the driving force.
Traction control means for controlling the driving force adjusting means such that the driving wheel has a target slip value in accordance with a predetermined control characteristic. When the difference A is equal to or greater than a predetermined value A4, the control characteristic changing means controls the driving wheel. The vehicle operation control device according to claim 1, wherein the control characteristic of the traction control means is changed so that the driving force is reduced.