KR100272631B1 - Safety operation control apparatus of vehicle - Google Patents

Abstract

PURPOSE: A safety traveling control device for a vehicle is provided to control brake torque by accurately calculating a target wheel slip rate based on a vehicle dynamics. CONSTITUTION: A controller for a safety traveling consists of an ECU(electronic control unit)(40) and a hydraulic modulator(6) in a vehicle(60). The ECU comprises a road frictional coefficient outputting unit(42); a tire frictional force calculating unit(44) calculating vertical and horizontal frictional force using a road frictional coefficient; a vehicle dynamics observing unit(46) estimating a tire slip angle and a vehicle side slip angle; a target yield rate calculating unit(48); a target vehicle side slip angle calculating unit(50); a target wheel slip calculating unit(52) comparing a vehicle yield rate with a target yield rate and comparing a vehicle side slip angle with a target vehicle side slip angle for indicating brake torque as target wheel slip rates; and a wheel slip controller(54) obtaining a control signal for the hydraulic modulator to estimate the target wheel slip rates with wheel slip rates.

Description

Vehicle safety control device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to brake control of a vehicle, and more particularly, to a safe driving control apparatus for a vehicle capable of accurately calculating a vehicle side slip angle and a target wheel slip ratio of four wheels based on vehicle dynamics.

In general, a safe driving control device related to braking and driving of a vehicle is a technology in which the wheel locking prevention device and the driving force control device are further developed.

The electronic controller mounted on the vehicle determines whether the vehicle is running safely, and when the vehicle tends to deviate from the driving path, even if the driver does not press the brake pedal, the vehicle independently operates by driving the brakes of the four wheels as needed. Make sure you can drive safely along the route.

1 is a view showing the overall configuration of a conventional safe driving control device, 1-4 is the front and rear left and right four wheels, 11-14 are each wheel speed sensor, 21-24 is a drum or disc brake of each wheel.

6 is a hydraulic modulator connected to the brake master cylinder, which changes the brake torque applied to the wheels 1-4 by adjusting the hydraulic pressure in the wheel cylinder of the drum brake or the caliper of the disc brake via the hydraulic conduit 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 yaw rate and lateral acceleration of the vehicle body in operation, respectively.

5 is a brake pressure sensor to measure the hydraulic pressure of the master cylinder. The electronic controller 40 receives the voltage signals of the wheel speed sensor 11-14, the steering wheel angle sensor 8, the yaw rate sensor 9, the lateral acceleration sensor 10, and the brake pressure sensor 5 as inputs. The hydraulic modulator 6 is driven through the control signal line 16 by performing calculations relating to the dynamics of the controller.

Since a plurality of solenoid valves are built in the hydraulic modulator 6 to adjust the hydraulic pressure of the wheel cylinder or the caliper, the control signal line 16 for improving the driving safety of the vehicle is composed of a plurality of wires.

When the driver rotates the steering wheel 7 while the vehicle is running, the electronic controller 40 calculates the driving path directed by the driver from the steering wheel angle sensor 8 input signal and the vehicle from the various sensor signals as described above. By calculating the actual driving route of the driver, the four-wheel brake torque is controlled to compare the driver-oriented driving route with the actual driving route so that the difference becomes smaller.

In more detail, the electronic controller 40 calculates the yaw rate and side slip angle of the vehicle body directed by the driver from the various sensor signals, and takes the target rate and the target side slip angle with reference to this, and oversteer the vehicle. By controlling the caliper's hydraulic pressure when the understeer is calculated, the actual yaw rate and side slip angle of the car body are controlled.

At this time, the rate can be measured from the input signal of the rate sensor 9, but the side slip angle of the vehicle body cannot be simply measured, and a series of complex calculations based on the vehicle dynamics can be used to obtain a target wheel slip which is a reference for brake torque control. This is necessary.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and an object thereof is to provide a safe driving control apparatus for a vehicle capable of accurately calculating a target wheel slip ratio and controlling brake torque based on vehicle dynamics.

1 is a block diagram showing the overall configuration of a safe driving 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 a steering angle and the tire slip angle of the present invention

<Explanation of symbols for main parts of drawing>

6: hydraulic modulator 40: electronic controller

42: road friction coefficient calculation unit 44: tire friction force calculation unit

46: vehicle dynamics observation unit 50: target vehicle side 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, and is largely comprised of a vehicle 60, an electronic controller 40, and a hydraulic modulator 6.

Wheel speeds V _W1 , V _W2 , V _{W3, and} yaw rate by various sensors installed in the vehicle 60 b.phiv; , Lateral acceleration V _y , brake pressure p are measured, steering angle δ _w is obtained. In addition, the electronic controller 40, the road surface friction coefficient calculation unit 42 for calculating the friction coefficient of the road surface running on the tire from the measured signal, the lateral timer friction force by using the calculated road surface friction coefficient F _S And longitudinal tire friction F _B Timer friction force calculation unit 44 for calculating the reference value, vehicle dynamics observation unit 46 for estimating the tire slip angle α and the vehicle side slip angle β from the sensor signal, and calculates the target rate Ψ m by referring to the rate of the vehicle body directed by the driver. Target rate calculation part 48, the side slip angle of the target vehicle β The target vehicle side slip angle calculation unit 50, which calculates m, compares the vehicle body rate Ψ and the target rate Ψm, and calculates the vehicle side slip angle β and the target vehicle side slip angle. β Comparing m, the body wheel rate Ψ follows the target rate Ψm, and the vehicle wheel slip angle β is the target wheel slip rate for the four-wheel brake torque required to follow the target vehicle side slip angle Ψm. λ _1m , λ _2m , λ _3m , λ Target wheel slip (52), wheel slip ratio in _4m λ _One, λ _2, λ _3, λ _4th Target Wheel Slip Rate λ _1m , λ _2m , λ _3m , λ _The wheel slip control unit 54 is configured to obtain a control signal required by the hydraulic modulator 6 to follow _4m . The electronic controller 40 is configured to repeat the above calculation at every calculation time.

The present invention configured as described above, first, Figure 3 shows a planar model of the vehicle ignoring the influence of the suspension, δ w is the steering angle of the front wheel steering vehicle, F _B1 and F _S1 Are the longitudinal timer frictional force or the braking force and the lateral tire frictional force or the turning force that the road surface exerts on the front left wheel 1, respectively.

The braking force acts parallel to the tire plane and the turning force acts perpendicular to the tire plane. F _B2 Wow F _{S 2} Are respectively the braking force and the turning force on the road front wheel (2).

F _B3 Wow F _S3 Is the braking force and lateral force that the road surface exerts on the rear left wheel (3) while the vehicle is turning, F _B4 Wow F _S4 Are the braking force and the transverse force which the road surface exerts on the rear right wheel 4, respectively.

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

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

4 is a steering angle in the interaction between the tire and the road surface δ _W , Tire slip angle α and vehicle side slip angle at the wheel β _W Define. Steering Angle β _W Is the angle between the x-axis and the tire plane of the vehicle body direction, that is, the tire slip angle α is the angle between the tire plane and the wheel running speed direction, and the vehicle-side slip angle at the wheel β _W Is the angle between the vehicle body direction and the wheel travel speed direction. Therefore, the following equation (1) is established.

β _W = α + δ _W

The calculation performed by the tire friction force calculation unit 44 is as follows. Longitudinal and transverse tire friction of one tire F _B Wow F _S Is given by Equations 2, 3, and 4 below.

here, C _λ Is the longitudinal tire stiffness coefficient, C _α Is the lateral tire stiffness coefficient, μ is the friction coefficient of the road surface estimated by the road surface friction coefficient calculating unit 42, F _N Is the vertical load on the tire. The tire slip ratio λ is defined as in Equation 5 below.

here, V _W Is the wheel speed when the brake torque is applied, V _WN Is the wheel speed that rotates freely when the brake is inactive. The following equation (6) is established from the above equations (2) and (3).

Assuming that the tire slip angle α is fine, Equation 6 is represented by Equation 1 to Equation 7 below.

The calculation performed by the vehicle dynamics observer 46 is as follows. In FIG. 3, the equation of motion of the vehicle in the y direction is given by Equation 8, and the moment equation of motion in the vertical z direction is given by Equation 9.

(aF _{S1 + a} F _S2 -cF _B1 + cF _B2 ) cosδ _w + (cF _S2 -cF _S1 -aF _B1-a F _B2) sinδ _w

Where m is the mass of the vehicle, V _X Wow V _Y Is the vehicle speed in the x and y directions, I _Z Is the z-direction moment of inertia of the vehicle. Substituting Equation 7 into Equation 8 establishes Equation 10, and substituting Equation 7 into Equation 9 establishes Equation 11.

f = r + e

Here, β _F and β _R are vehicle side slip angles at the front and rear axles, respectively, and are given as a function of the vehicle side slip angle β at the center of gravity as shown in Equations 12 and 13 below.

Substituting Equations 12 and 13 into Equations 10 and 11 establishes Equations 14 and 15 below.

β = f ₁ (λ, β, ψ) β + g ₁ (λ, β, ψ) ψ + h ₁ (λ, β, ψ)

ψ = f ₂ (λ, β, ψ) β + g ₂ (λ, β, ψ) + h ₂ (λ, β, ψ)

here, f ₁ (λ, β, ψ) = f ₁ (λ _1, λ _2, λ _3, λ ₄ , β, ψ)

g ₁ (λ, β, ψ) = g ₁ (λ _1, λ _2, λ _3, λ _4, β, ψ)

h ₁ (λβψ) = h ₁ (λ _1, λ _2, λ _3, λ _4, β, ψ)

f ₂ (λ, β, ψ) = f ₂ (λ _1, λ _2, λ _3, λ _4, β, ψ)

Meanwhile, if Equations 12 and 13 are substituted into Equation 10, the vehicle side slip angle β is expressed as Equation 17 below.

β = β (V _w1, V _w2, V _w3, V _w4, δ _w, ψ, V _y )

Wheel speed V _W1 , V _W2 , V _{W3 ,} V _W4 Is measured by the wheel speed sensor 11-14, the provision angle δw is obtained from the steering wheel angle sensor 8, the body yaw rate ψ is measured by the yaw rate sensor 9, and the lateral acceleration V Since the vehicle is measured by the lateral acceleration sensor 10, the slip angle of the vehicle side β Is accurately calculated using equation (17).

Similarly, the target rate in the target rate calculation unit 48 ψ _m Is obtained, the target vehicle side slip angle is calculated by the target vehicle side slip angle calculation unit 50. β _m Is obtained as shown in Equation 18 below.

β _m = β _m (V _w1, V _w2, V _w3, V _w4, δ _w , ψ _m, V _y )

The calculation performed by the target wheel slip calculation unit 52 is as follows. Equations 14 and 15 are nonlinear equations, and thus the wheel slip ratio for linearization is calculated. λ Vehicle side slip angle β The vehicle body ratio Ψ is the sum of the reference wheel slip ratio λ _o , the reference vehicle side slip angle β _o , the reference body body ratio ψ ₀ , the fine wheel slip ratio λ _p , the fine vehicle side slip angle β _p , and the fine vehicle body ratio ψ as shown below. Is displayed.

λ = λ ₀ + λ _p

β = β ₀ + β _p

ψ = ψ ₀ + ψ _p

Substituting Equations 19a, 19b, and 19c into Equations 14 and 15 establishes a linearized equation as follows.

β _p (t) = a ₁₁ (t) β _p (t) + a ₁₂ (t) ψ _p (t) + b ₁₁ (t) λ _1p (t) + b ₁₂ (t) λ _2p (t) + b ₁₃ (t) λ _3p (t) + b ₁₄ (t) λ _4p (t)

ψ _p (t) = a ₂₁ (t) β _p (t) + a ₂₂ (t) ψ _p (t) + b ₂₁ (t) λ _1p (t) + b ₂₂ (t) λ _2p (t) + b ₂₃ (t) λ _3p (t) + b ₂₄ (t) λ _4p (t)

here,

Equations 20 and 21 may be represented by Equation 24 of the state space type as follows.

Where a ₁₁ -a ₂₂ are elements of the state matrix and b ₁₁ -b ₂₄ are elements of the input matrix. Solving the algebraic Ricaty equation by applying the optimal control problem method to the matrix equation 24 given by the time-varying linear differential equation, the fine wheel slip ratios λ _1p , λ _2p , λ _3p , and λ _4p corresponding to the optimal state are as follows. It is obtained as a function of the vehicle side slip angle beta _p and the fine vehicle body rate ψ _p .

The optimal gain matrix elements g ₁₁ -g ₄₂ are given as functions of matrix elements a ₁₁ -a ₂₂ and b ₁₁ -b ₂₄ of Equation 24. The command elements a ₁₁ -a ₂₂ and b ₁₁ -b ₂₄ are wheel speed sensors 11, 12, 13 and 14, steering wheel angle sensor 8, body rate sensor 9, lateral acceleration sensor. Since the measured value measured by (10) and the vehicle side slip angle β calculated by Equation 17 can be directly calculated, the optimal gain matrix elements g11-g42 can be directly calculated at every calculation time.

Taking the target vehicle side slip angle β _m at the reference vehicle side slip angle β ₀ , and taking the target rate ψ _m at the reference vehicle body ratio ψ ₀ , the target wheel slip ratios λ _1m , λ _2m , λ _3m , and λ _4m Is obtained as follows.

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

In the present invention as described above, the vehicle side slip angle and the target vehicle side slip angle are accurately calculated from the equation based on the vehicle dynamics using the four-wheel speed, the steering angle, the body's yaw rate, and the lateral acceleration measured by the sensor. In addition, since the target wheel slip ratio is accurately calculated based on the vehicle dynamics, the brake torque of the four wheels can be independently controlled to achieve safe driving.

Claims (5)

In a safety driving control apparatus for a vehicle in which the electronic controller controls the hydraulic modulator according to the signals of the plurality of sensors for detecting the driving state of the vehicle to independently control the brakes of the four wheels and control the vehicle to drive safely. The electronic controller; A road surface friction coefficient calculator for calculating a road surface friction coefficient to the tire based on detection signals of the plurality of sensors; Lateral tire friction force by the road surface friction coefficient calculated by the road surface friction coefficient calculating unit F _S And longitudinal tire friction F _B Tire friction force calculation unit for calculating; Lateral tire friction force calculated by the detection signals of the plurality of sensors and the timer friction force calculator F _S And longitudinal tire friction F _B A vehicle dynamics observation unit for estimating a low tire slip angle α and a vehicle side slip angle β; A target efficiency calculator for obtaining a target efficiency Ψm by referring to the body rate Ψ to which the driver is directed; A target vehicle side slip angle calculator configured to calculate a lateral slim angle βm of the target vehicle; The body rate Ψ is required to follow the target rate Ψm and the slip angle β is required to follow the target vehicle side slip angle βm by comparing the body rate Ψ and target rate Ψm with the calculated vehicle side slip angle β and target vehicle side slip angle βm respectively. Wheel slip ratio aimed at brake torque of four wheels becoming λ _1m , λ _2m , λ _3m and λ A target wheel slip calculation unit outputting _{4 m} ; And The wheel slip ratio λ ₁ , λ ₂ , λ ₃ and λ ₄ is the target wheel slip ratio λ _1m , λ _2m , λ _3m and λ _A device for safe driving control of a vehicle, characterized by comprising a wheel slip manufacturing zone for outputting a control signal required by a hydraulic modulator to follow _{4 m} . According to claim 1, A plurality of sensors installed in the vehicle; Wheel speed V _W1 , V _W2 , V _W3 And V _W4 A wheel speed sensor for detecting a; Steering Speed δ a steering wheel angle sensor for detecting _w ; A rate sensor for detecting a rate Ψ; Lateral acceleration V _Y Transverse acceleration sensor for detecting; And A safety driving control device for a vehicle, characterized in that the brake pressure sensor for detecting the brake pressure P. The method of claim 1, wherein the target wheel slip calculation unit; Safe driving control apparatus for a vehicle, characterized in that for calculating the target wheel slip ratio by the following equation (26). Equation 26

4. The safe driving control apparatus for a vehicle according to claim 3, wherein the optimum gain matrix is obtained by solving the algebraic Ricati equation of the optimal control problem method for the linear differential equation of the vehicle motion as shown in Equation (24).

The method according to claim 4, wherein the state matrix elements a ₁₁ to a ₂₂ and the input matrix elements b ₁₁ to b ₂₄ are each; Safety driving control apparatus for a vehicle, characterized in that given by the following equations (22a) to (221) and (23a to 23f). Equation 22a

Equation 22b

Equation 22c

Equation 22d

Equation 22e

Equation 22f

Equation 22g

Equation 22h

Equation 22i

Equation 22j

Equation 22k

Equation 22l

Equation 23a

Equation 23b

Equation 23c

Equation 23d

Equation 23e

Equation 23f

Images