KR19990041251A - Safety control of the vehicle - Google Patents

Abstract

The present invention relates to a safe operation control device for a vehicle which can accurately calculate a vehicle side slip angle and a target wheel slip ratio of a fourth wheel based on the vehicle dynamics and is provided with an electronic controller (40) and a vehicle having a hydraulic modulator (60), characterized in that the electronic controller (40) comprises a road surface friction coefficient calculating section (42) for calculating a friction coefficient of the road surface from the measured signal on the tire, and a road surface friction coefficient calculating section Timer Friction And longitudinal tire friction A vehicle dynamics observation unit 46 for estimating a tire slip angle? And a vehicle side slip angle? From a sensor signal, and a vehicle dynamics monitoring unit 46 for calculating a target rate a target yaw rate calculating section 48 for obtaining a target yaw rate m, a target vehicle lateral slip angle calculating unit 50 for calculating a vehicle body yaw rate m, And target rate m and compares the calculated vehicle lateral slip angle [beta] with the target vehicle lateral slip angle [beta] m, and the vehicle body rate This target rate m, and the vehicle side slip angle beta is smaller than the target vehicle side slip angle the brake torque of the fourth wheel required to follow m is set as a target wheel slip ratio _{1 m} , _2m , _3m , Target wheel shown by _4m slip calculating unit 52, a wheel slip rate _{One, 2, 3, 4} target wheel slip rate _{1 m} , _2m , _3m , _And a wheel slip control section 54 for obtaining a control signal required by the hydraulic modulator 6 so as to follow _4m .

Description

Safety control of the vehicle

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a brake control of a vehicle, and more particularly, to a safe running control system for a vehicle, which can accurately calculate a vehicle side slip angle and a target wheel slip ratio of a fourth wheel based on vehicle dynamics.

Generally, the safe running control device related to the braking and driving of the vehicle is a technology in which the wheel lock preventing device and the driving force controlling device are further developed.

The electronic controller mounted on the vehicle judges whether or not the vehicle is safely operated and when the vehicle shows a tendency to deviate from the traveling route, the driver independently drives the brakes of the 4th wheel independently as needed even if the driver does not step on the brake pedal, So that it can run safely along the route.

1 is a general block diagram of a conventional safety operation control device. Reference numerals 1-4 denote four-wheel wheels on the front, rear, left and right sides, reference numerals 11-14 indicate respective wheel speed sensors, and reference numerals 21-24 denote drums or disc brakes of respective wheels.

Reference numeral 6 denotes a hydraulic modulator connected to the brake master cylinder, which changes the brake torque applied to the wheel 1-4 by regulating the hydraulic pressure in the wheel cylinder of the drum brake or the caliper of the disc brake via the hydraulic pipelines 31-34.

The rear wheel brakes 23 and 24 are connected to the hydraulic modulator 6 via pressure proportional valves 25 and 26. [

The steering wheel angle sensor 8 measures the rotation angle of the steering wheel 7. [ The yaw rate sensor 9 and the lateral acceleration sensor 10 installed at the center of gravity of the vehicle measure the yaw rate and the lateral acceleration of the vehicle body in operation, respectively.

5 is the brake pressure sensor and measures the hydraulic pressure of the master cylinder. The electronic controller 40 receives the voltage signals of the wheel speed sensor 11-14 and the steering wheel angle sensor 8, the yaw rate sensor 9, the lateral acceleration sensor 10 and the brake pressure sensor 5, And drives the hydraulic modulator 6 through the control signal line 16. The hydraulic modulator 6 is driven by the control signal line 16,

A plurality of solenoid valves are incorporated in the hydraulic modulator 6 to control the hydraulic pressures of the wheel cylinders or the calipers. Therefore, the control signal line 16 for improving the safety of the vehicle is composed of a plurality of wires.

When the driver rotates the steering wheel 7 when the vehicle is in operation, the electronic controller 40 calculates the driver's intended travel route from the steering wheel angle sensor 8 input signal, And the actual driving route is compared with the driver-oriented driving route, and the brake torque of the fourth wheel is controlled so that the difference is reduced.

More specifically, the electronic controller 40 calculates the yaw rate and side slip angle of the vehicle body that the driver is aimed at from the various sensor signals, takes the target rate and the target side slip angle with reference thereto, ) Or by adjusting the hydraulic pressure of the caliper when the understeer is calculated, thereby controlling the actual rate of the vehicle body and the side slip angle.

At this time, the yaw rate can be measured from the input signal of the yaw rate sensor 9, but the side slip angle of the vehicle body can not be simply measured, and to obtain the target wheel slip, which is the basis of the brake torque control, Is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a safe operation control device for a vehicle which can accurately calculate a target wheel slip ratio based on vehicle dynamics and control a brake torque.

1 is a block diagram showing the entire configuration of a safety operation control apparatus of a conventional vehicle

2 is a block diagram of an electronic controller according to the present invention;

3 is a plan view of a vehicle for explaining the present invention.

4 is a view showing the steering angle and the tire slip angle of the present invention

Description of the Related Art

6: Hydraulic modulator 40: Electronic controller

42: road surface friction coefficient calculating unit 44: tire finish force calculating unit

46: vehicle dynamics observation unit 50: target vehicle lateral slip angle calculation unit

52: target wheel slip calculation unit 54: wheel slip calculation unit

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an electronic controller according to the present invention, which mainly comprises a vehicle 60, an electronic controller 40, and a hydraulic modulator 6. As shown in Fig.

Wheel speed by the various sensors installed in the vehicle _{(60) V W1, V W2} , V W3, rate , The lateral acceleration V _y , and the brake pressure p are measured, and the steering angle _w is obtained. The electronic controller 40 further includes a road surface friction coefficient calculating unit 42 for calculating a friction coefficient of the road surface from the measured signal on the tire, And longitudinal tire friction A vehicle dynamics observing unit 46 for estimating a tire slip angle? And a vehicle side slip angle? From the sensor signal, and a target rate of the vehicle body intended by the driver, a target yaw rate calculating section 48 for obtaining m, a lateral yaw rate a target vehicle lateral slip angle calculating unit 50 for calculating the vehicle body yaw rate m, And target rate m and compares the calculated vehicle lateral slip angle [beta] with the target vehicle lateral slip angle [beta] m, and the vehicle body rate This target rate m, and the vehicle side slip angle [beta] is the target vehicle side slip angle the brake torque of the fourth wheel required to follow m is set as a target wheel slip ratio _{1 m} , _2m , _3m , A target wheel slip 52 indicated by _{4 m} , a wheel slip ratio _{One, 2, 3,} 4 target wheel slip rate _{1 m} , _2m , _3m , _And a wheel slip control unit 54 for obtaining a control signal required by the hydraulic modulator 6 so as to follow _4m . The electronic controller 40 is configured to repeatedly perform the above calculation at every calculation time.

3 is a planar model of a vehicle in which the effect of suspension is ignored, w is a steering angle of the front wheel steering vehicle, and Are the longitudinal timer frictional force or braking force and the lateral tire frictional force or cornering force, respectively, of the road surface on the front left wheel 1. [

The braking force acts parallel to the tire plane, and the turning force acts perpendicular to the tire plane. Wow Are the braking force and the turning force exerted by the road surface on the front right wheel 2, respectively.

Wow Is a braking force and a lateral force on the rear left wheel (3) when the vehicle is turning, Wow Are the braking force and the lateral force on the rear right wheel 4, respectively.

a and b are distances from the center of gravity of the vehicle to the front wheel axle and the rear wheel axle, respectively, and c is the distance from the center of gravity of the vehicle to the left or right wheel. The xy axis represents a fixed body coordinate system having the center of gravity of the vehicle as the origin, Represents the rotation angle of the vehicle body in the xy plane.

In a curved roadway, the driver turns the steering wheel to turn the vehicle. At this time, in order to generate the turning force of the vehicle at the contact side of the tire with the road surface, the direction of the vehicle body, the direction of the tire, and the traveling speed direction of the vehicle do not coincide.

4 is a graph showing the relationship between the steering angle , The tire slip angle alpha and the vehicle side slip angle . Steering angle Is the angle between the x axis of the vehicle body and the tire plane and the tire slip angle alpha is an angle between the tire plane and the wheel advancing speed direction and the vehicle side slip angle Is an angle between the vehicle body direction and the wheel advancing speed direction. Therefore, the following equation (1) is established.

The calculation performed by the tire frictional force calculator 44 is as follows. Tire friction of one tire species and transverse direction Wow Is given by the following equations (2), (3) and (4).

here, Is the longitudinal tire stiffness coefficient, Is the lateral tire stiffness coefficient, 占 is the friction coefficient of the road surface estimated by the road surface friction coefficient calculating unit 42, Is the vertical load on the tire. The tire slip rate [lambda] is defined by the following equation (5).

here, Is the wheel speed at the time of brake torque operation, Is a wheel that rotates freely when the brake is inoperative. The following equation (6) is established from the equations (2) and (3).

Assuming that the tire slip angle? Is fine, Equation (6) becomes Equation (7) from Equation (1).

The calculation performed by the vehicle dynamics observation unit 46 is as follows. 3, the equation of motion of the vehicle with respect to the y direction is given by equation (8), and the equation of momentum equation with respect to the vertically downward z direction is given by equation (9).

Here, m is the mass of the vehicle, Wow The vehicle speed in the x and y directions, Is the z-direction moment of inertia of the vehicle. Substituting Equation (7) into Equation (8), Equation (10) is established, and Equation (7) is substituted into Equation (9).

Here,? _F and? _R are the lateral slip angles of the vehicle on the front axle and the rear axle, respectively, as a function of the lateral slip angle? Of the vehicle at the center of gravity as shown in the following equations (12) and (13).

Substituting Equations (12) and (13) into Equations (10) and (11), the following Equations (14) and (15) are established.

here,

On the other hand, when Equations (12) and (13) are substituted into Equation (10), the vehicle lateral slip angle? Is expressed as Equation (17).

Wheel speed , , _, Is measured by the wheel speed sensor 11-14, the provision angle? W is obtained from the steering wheel angle sensor 8, the vehicle body rate ψ is measured by the yaw rate sensor 9, Is measured by the lateral acceleration sensor (10), the vehicle lateral slip angle Is accurately calculated using Equation (17).

Likewise, in the target rate calculation section 48, The target vehicle side slip angle calculating unit 50 calculates the target vehicle side slip angle < RTI ID = 0.0 > Is obtained by the following equation (18).

Since the equations (14) and (15) are nonlinear equations, the target slip ratio calculation unit (52) , The vehicle side slip angle , Body rate Is expressed by the sum of the reference wheel slip rate λ _o, based on the vehicle side slip angle β _o, the reference vehicle body rate ψ ₀ and fine wheel slip rate λ _p, fine vehicle side slip angle β _p, fine body rate ψ as follows, respectively.

Substituting equations (19a), (19b), and (19c) into equations (14) and (15), a linearized equation is established as follows.

here,

Equations (20) and (21) can be expressed by Equation (24) of the state space type as follows.

Where a ₁₁ -a ₂₂ is an element of the state matrix and b ₁₁ -b ₂₄ is an element of the input matrix. When the mathematical Riccati equations are solved by applying the optimal control problem method to the matrix equation 24 given by the time-varying linear differential equation, the slip ratios λ _1p , λ _2p , λ _3p , and λ _4p , And is obtained as a function of the vehicle side slip angle [beta] _p and the minute vehicle body rate [psi] _p .

Where the optimal gain matrix elements g ₁₁ -g ₄₂ are given as a function of matrix elements a ₁₁ -a ₂₂ and b ₁₁ -b ₂₄ in equation ( ₂₄ ). Haengryeong element ₁₁ -a ₂₂ a, b ₁₁ -b ₂₄ are wheel speed sensors 11, 12, 13, 14, the steering wheel angle sensor 8, the vehicle body rate sensor 9, lateral acceleration sensor Can be directly calculated using the measurement value measured by the vehicle 10 and the vehicle side slip angle [beta] calculated by the equation (17), so that the optimum gain matrix element g11-g42 can be directly calculated every calculation time.

Based on the vehicle side slip angle β ₀ with the target vehicle side slip angle β _m to take, based on the vehicle body rate ψ ₀ when a take target rate ψ _m target wheel from the equation (25) slip rate _{λ 1m, λ 2m, λ 3m} , λ 4m Is obtained as follows.

Where λ1, λ2, λ3 and λ4 are the wheel slip rates at the present calculation time, β is the vehicle lateral slip angle at the present calculation time, and ψ is the vehicle body rate at the present calculation time.

As described above, according to the present invention, the lateral slip angle of the vehicle and the lateral slip angle of the target vehicle are accurately calculated from the equation based on the vehicle dynamics, using the four wheel speeds, the steering angle, the vehicle body yaw rate, and the lateral acceleration measured by the sensors. Further, since the target wheel slip ratio is accurately calculated on the basis of the vehicle dynamics, the brake torque of the fourth wheel can be independently controlled to achieve safe driving.

Claims (5)

In the vehicle 60 having the electronic controller 40 and the hydraulic modulator 6, The electronic controller (40) includes a road surface friction coefficient calculating unit (42) for calculating a friction coefficient of the road surface from the measured signal to the tire, and a lateral friction coefficient calculating unit And longitudinal tire friction A vehicle dynamics observation unit 46 for estimating a tire slip angle? And a vehicle side slip angle? From a sensor signal, and a vehicle dynamics monitoring unit 46 for calculating a target rate a target yaw rate calculating section 48 for obtaining a target yaw rate m, a target vehicle lateral slip angle calculating unit 50 for calculating a vehicle body yaw rate m, And target rate m and compares the calculated vehicle lateral slip angle [beta] with the target vehicle lateral slip angle [beta] m, and the vehicle body rate This target rate m, and the vehicle side slip angle beta is smaller than the target vehicle side slip angle the brake torque of the fourth wheel required to follow m is set as a target wheel slip ratio _{1 m} , _2m , _3m , Target wheel shown by _4m slip calculating unit 52, a wheel slip rate _{One, 2, 3, 4} target wheel slip rate _{1 m} , _2m , _3m , _And a wheel slip control unit (54) for obtaining a control signal required by the hydraulic modulator (6) so as to follow the wheel speed ( _4m ). The vehicle (60) according to claim 1, , , _, Rate , Lateral acceleration , The brake pressure p is measured, and the steering angle _w of the vehicle is obtained. The safe running control apparatus for a vehicle according to claim 1, characterized in that the target wheel slip calculating section (52) calculates a target wheel slip ratio as expressed by Equation (26). 4. The safe operation control apparatus for a vehicle according to claim 3, characterized in that the optimal gain matrix is obtained as a solution of a mathematical Riccati equation of an optimal control problem method for a linear differential equation of vehicle motion, The method of claim 4, wherein the state matrix elements a ₁₁ -a ₂₂ and the input matrix elements b ₁₁ -b ₂₄ The safe driving control apparatus of a vehicle, characterized in that given by Equation 22a-22f.